HK1154877B - Coating composition comprising autoxidisable component - Google Patents

Description

Coating compositions containing autoxidisable components

The present invention relates to coating compositions containing autoxidisable components and to methods of preparing these compositions. After the composition of the present invention is applied to a surface, the resulting coating reduces show-through of surface defects.

When applying decorative or protective coatings to substrates, it is a general requirement to obtain a smooth surface without visible defects. The extent to which the underlying surface can be visibly confirmed by the coating is often described as strike-through (i.e. giving a clear unaesthetic or premature cue for something to appear). It has been found that defects on substrates such as wood that result in roughness are often telegraphed through conventional dry coatings.

Thicker coating materials are typically used to reduce show-through because they are able to adequately even out any unevenness on the surface. Thus, the roughness of the lower surface of the substrate appears to a reduced extent, resulting in a visually smooth final coating. However, thicker coatings have the disadvantage of increasing cost because they may need to be applied in several layers. Furthermore, when thicker layers are used, slow through-drying, wrinkling and sagging may occur.

Organic solvents have been used to reduce show-through. However, due to the continuing concern over the use of organic solvents, there is a long felt need for waterborne coating compositions having properties comparable to those obtained using organic solvent-based compositions.

The coating should also dry fast enough to avoid dust adhesion and ensure that the coating quickly becomes water resistant (e.g. in the case of outdoor applications), block resistant, tack free.

Aqueous compositions such as water-dilutable, autoxidisable esters (also known as water-dilutable unsaturated alkyd resins or alkyd emulsions) are also used to address the aforementioned print-through problem. However, these systems have some well-known problems.

Water-dilutable alkyds may also suffer from backbone hydrolysis. This may result in performance that varies over time, which is less than ideal. Conventional alkyd emulsions are discussed in the following references: tuck, "Water borne and solvent based weights and the end user applications", Vol.VI, Wiley/Sita Series In Surface Coatings technology; (ISBN471985910), published in 2000.

Another common problem with conventional alkyd emulsions is that the emulsions have a tendency to develop shrinkage (lubricating or crawling) when applied as an overcoat. Shrinkage refers to the retraction from the surface when the coating rejects the formation of a continuous film, collecting into small spheres and leaving on the partially exposed surface, thereby reducing the appearance of the coated object.

Another drawback of conventional alkyd systems, especially those containing a relatively high percentage of unsaturated fatty acid residues, is that they have a tendency to yellow (light or dark) significantly over time.

Current coatings lack some or all of the above performance characteristics, so a desirable coating has low strike-through combined with the following properties: the alkyd resin has minimal backbone hydrolysis, low yellowing over time, and/or low shrinkage. In many markets, existing waterborne coatings are not widely accepted as a replacement for solvent-based coatings. For example, solvent-based alkyd resins are still preferred in the decorative market, where very low strike-through is required because the coating is typically applied by brush. It is also desirable that the aqueous composition be clear or transparent, rather than opalescent or opaque.

It is also generally known that polyester-based alkyds (PE alkyds) typically have a broad molecular weight distribution and thus contain significant amounts of low molecular weight materials, which dry more slowly, thus implying longer periods of coating tack (i.e. with long tack free times). The presence of lower molecular weight materials cannot be avoided for several reasons. For example, glycerol (with three fatty acids-triglycerides) and pentaerythritol (with four fatty acids) are common raw materials for making PE alkyds. To address the problems caused by the presence of the low molecular weight fraction, the PE alkyd resin may be prepared in a highly branched form to obtain a faster drying high molecular weight fraction. However, the resulting branched PE alkyds have significantly increased viscosity and reduced flow (compared to the less branched equivalents), and therefore must be diluted with more organic solvent before they can be used. This is undesirable because, for example, it increases the amount of Volatile Organic Compounds (VOCs) and adversely affects the flowability of the composition.

Known autoxidisable vinyl polymers can be prepared by: the vinyl monomer is subjected to radical polymerization in the presence of a fatty acid derivative. However, the resulting polymers have a broad molecular weight distribution and these polymers require larger amounts of solvent to prepare the coating, which often also contains high levels of free monomer. Without wishing to be bound by theory, it is believed that the unsaturated fatty acid delays free radical polymerization and grafts onto the vinyl polymer, resulting in more material with higher molecular weight and broader molecular weight distribution.

WO 2002-. The oligomers described in this application have low amounts of fatty acids (< 40 wt%). As the comparative data in this document indicates, these oligomers are designed for different purposes (improving open time) and the coatings produced do not have a satisfactory body within a few days (in the tests defined herein) and do not give a satisfactory open time.

US 5089342, EP 0370299 and EP 0316732 (all Bayer) disclose an aqueous air-drying coating composition comprising a water-soluble air-drying polyacrylate having a molecular weight greater than 1000 g/mole and 5-40 wt.% chemically incorporated fatty acids and 50-100 milliequivalents of chemically incorporated quaternary ammonium fragments per 100 grams of solids. The systems described in this reference are cationic, teaching the use of no anionic system (see, e.g., column 1, line 53) and the use of styrenic monomers as part of the vinyl monomer, which is not so good because the monomer may cause yellowing of the final product.

DE 10106561(Kansai Paint) describes coating compositions from silicone-modified vinyl copolymers having a fatty acid component.

WO 02/18456(Johnson Polymer) discloses a continuous process for preparing polymers having at least one functional group. This first polymer is transferred to a second reaction zone together with at least one modifier having a group complementary to the above-mentioned functional group.

US 4727100(Du Pont) discloses a solvent borne coating composition comprising a reactive urethane component, an acrylic fatty acid drying oil resin and a metal catalyst.

US 6509417(Lilly) discloses a glossy coating composition comprising 20 to 80% of a solvent and 20 to 80% of a reactive binder (relative to the weight of the composition), said binder comprising relative to the weight of the binder a)0 to 24% of an acrylic anhydride polymer having at least two reactive anhydride groups; B)5 to 50% of a fatty acid modified glycidyl polymer having hydroxyl functional groups, at least two reactive glycidyl groups and at least two unsaturated groups; and C)5 to 60% of a polymeric compound containing a plurality of hydroxyl groups.

US 7235603(Rohm and Haas) discloses a process for preparing room temperature curable aqueous dispersions comprising a) a step of preparing polymer particles having one or more stages by preparing a first order polymer containing at least one epoxy group and at least one pendant ethylenically unsaturated side chain. The first order polymer described above was prepared by: 1) preparing a precursor polymer containing at least one epoxy group by free radical addition polymerization of at least one ethylenically unsaturated monomer; 2) the precursor is reacted with a co-reactive olefin material. This patent document describes fatty acid functional acrylic polymers with low fatty acid content (< 40% by weight) prepared by incorporating fatty acid functional groups into the aqueous phase.

GB 767476(Canadian Industries) describes a resin-type material which is the thermal reaction product of a styrene/glycidyl methacrylate copolymer and oleic acid.

JP 60110765 describes the reaction of a copolymer of an α, β unsaturated acid (such as acrylic acid) and other monomers with a glycidyl ester of an unsaturated fatty acid to form a resin which is combined with another resin to give a thick aqueous coating.

We have now found various ways to overcome the above-mentioned drawbacks, especially when a combination of more than one problem needs to be overcome in one coating system.

The present invention aims to address some or all of the problems identified herein. It is a preferred object of the present invention to provide a method of improving the appearance of a coated substrate, which substrate has visible defects. In a more preferred object of the invention, the method can be used with a variety of coating compositions.

The applicant has found that certain vinyl polymers made by free radical polymerisation of certain vinyl/acrylic monomers can contain significantly lower low molecular weight fractions (such as the triglycerides mentioned above), thereby avoiding the need to use significant high molecular weight materials, for example to improve drying. The applicant has also surprisingly found that certain vinyl polymers (of specific molecular weight, PDi and T) prepared by free-radical polymerization of epoxy-functionalized vinyl monomers and other vinyl monomers, followed by reaction with certain unsaturated fatty acids_gValues) can overcome some or all of the above-described problems with existing vinyl polymers.

Accordingly, the present invention broadly provides a coating composition comprising an autoxidisable vinyl polymer, said composition being selected from the group consisting of a waterborne coating composition and a solvent based (also known as solvent borne) coating composition, wherein:

I) the autoxidisable vinyl polymer having:

i) a vinyl polymer backbone in an amount of 25% to 75% relative to the weight of the autoxidisable vinyl polymer;

ii) a fatty acid residue in an amount of 25% to 75% relative to the weight of the autoxidisable vinyl polymer;

iii) -T from 60 ℃ to +20 ℃_g；

iv) a weight average molecular weight (M) of 3,500 to 50,000g/mol_w) (ii) a And

v) PDi from 2 to 10;

II) the autoxidisable vinyl polymer is derived or obtainable from a process comprising the steps of:

(A) polymerizing an ethylenically unsaturated vinyl monomer comprising:

i) at least one epoxy-functional vinyl monomer in an amount of 15% to 100% relative to the weight of the total monomers in step (a); and

ii) at least one other ethylenically unsaturated vinyl monomer in a content of 0% to 85% relative to the weight of the total monomers in step (A);

(B) reacting the epoxy-functional vinyl polymer obtained in step (A) with an average iodine value of 30 to 250g I₂V (100g of fatty acid) is reacted;

III) the composition:

a) optionally having a content of co-solvent of less than or equal to 40% relative to the total weight of the composition; and is

b1) When an aqueous composition, has a solids content greater than or equal to 30% relative to the total weight of the aqueous composition;

b2) when solvent-based, has a solids content greater than or equal to 60% relative to the total weight of the solvent-based composition; and

IV) the composition when a film has a show-through value of less than 10 gloss units,

wherein the strike-through value is the difference of an initial smooth gloss value of the film minus an initial matte gloss value, the initial smooth gloss value being the gloss of the film cast on smooth PVC (Rz ═ 1 μm [ + -0.25 μm ]), the initial matte gloss value being the gloss of the film cast on matte PVC (Rz ═ 25 micrometers [ μm ] [ + -5 μm ]); and is

Each film has a dry film thickness of 52 μm [ + -6 μm ];

each initial gloss value was measured at a 20 ° angle one day (24 hours) after the film was cast.

PVC as used herein refers to the polyvinyl chloride substrate used as described in the test methods herein.

Dry film thickness is herein determined under standard conditions after 24 hours of drying. The term "standard conditions" as used herein, unless otherwise stated, means a relative humidity of 50% ± 5%, an ambient temperature and an air flow rate of less than or equal to 0.1 m/s; the term "ambient temperature" means 23 ℃. + -. 2 ℃.

The show value (telegraphing value) used herein is a positive value. Generally, the more the reduction in strike-through, the smaller the strike-through value.

As used herein, the term "comprising" means that the listed items immediately following it are open-ended and may or may not include any other additional suitable items, such as, for example, one or more other features, components, ingredients, and/or substituents, as desired. As used herein, "substantially comprises" means that one component or a plurality of components listed is present in a given material in an amount greater than or equal to about 90 wt%, preferably greater than or equal to 95 wt%, more preferably greater than or equal to 98 wt%, relative to the total amount of the given material. The term "consisting of … …" as used herein means that the listed items thereafter are closed and do not contain additional items.

For all upper and lower limits of any parameter given herein, the upper and lower limits are included in the respective ranges for the respective parameter. All combinations of minimum and maximum values of the parameters described herein may be used to define the parameter ranges of the various embodiments of the invention.

It will be understood that the sum of any content expressed as a percentage herein cannot (with rounding errors allowed) exceed 100%. For example, the sum of all components making up a composition of the invention (or a portion thereof), when expressed as a weight (or other) percentage of the composition (or the same portion thereof), will total 100% (with rounding errors allowed). However, where the listed components are open-ended, the sum of the percentages of each such component may be less than 100%, thereby leaving some percentages for the additional amount of any additional component not explicitly recited herein.

The terms "oligomer" and "polymer" as used herein both refer to a macromolecule containing a plurality of units derived, actually or conceptually, from a lower molecular weight molecule. These terms may also be used in an adjective form to describe a portion or all of a macromolecule. In general, the term "oligomer" may be used to refer more specifically to a macromolecule of relatively intermediate molecular weight, wherein the properties of the oligomer change significantly with the removal of one or several units. A polymer may describe any macromolecule in general, but may also describe a macromolecule of relatively high molecular weight more specifically, where the addition or removal of one or several units generally has a negligible effect on the properties of the molecule (although this may not always be the case, for example, where certain properties of the polymer are critically dependent on the fine details of the molecular structure). It will be understood that the molecular weight boundaries between oligomers and polymers (in their specific rather than general sense) may vary depending on the particular macromolecule and/or application of interest, so the molecular weight boundaries may overlap significantly where the same macromolecule may be considered to be both an oligomer and a polymer. Thus, unless the context herein clearly dictates otherwise, the terms "oligomer" and "polymer" are used interchangeably herein.

Preferably, the coating composition of the present invention is a non-adherent composition. The term "non-adhesive composition" as used herein refers to any composition that is substantially non-tacky after drying at ambient conditions for a certain length of time that is commercially acceptable. Non-adhesive compositions may be those having a tack-free time of less than or equal to 16 hours, preferably less than or equal to 10 hours, more preferably less than or equal to 6 hours, most preferably less than or equal to 4 hours. Open time is suitable for determination as described herein.

Preferably, the autoxidisable vinyl polymer comprises fatty acid residues in an amount of 41% to 75% relative to the weight of the autoxidisable vinyl polymer.

Preferably, the at least one other ethylenically unsaturated vinyl monomer (ii) in step (a) is not styrene, alpha-methylstyrene, vinyltoluene and/or mixtures thereof. More preferably, the at least one other ethylenically unsaturated vinyl monomer does not comprise any styrenic monomer, i.e. does not comprise monomers comprising optionally substituted vinylbenzene segments.

The compositions of the invention may be aqueous (including aqueous solutions and/or emulsions in which the continuous phase is aqueous) or solvent-based (including solvents other than water, such as organic solvents).

Preferably, when the composition is an aqueous composition, the aqueous composition has a co-solvent content of less than 25% relative to the total weight of the composition.

Another aspect of the present invention provides a process for obtaining an autoxidisable vinyl polymer wherein:

the autoxidisable vinyl polymer is capable of forming a coating composition that when in film form has a print-through value (as defined herein) of less than 10 gloss units;

the method comprises the following steps:

(I) polymerizing an ethylenically unsaturated vinyl monomer comprising:

i) at least one epoxy-functional vinyl monomer in an amount of 15% to 100% relative to the weight of the total monomers in step (I); and

ii) at least one other ethylenically unsaturated vinyl monomer in an amount of 0% to 85% relative to the weight of the total monomers in step (I);

(II) reacting the epoxy-functionalized vinyl polymer obtained in step (I) with an average iodine value of 30 to 250g I₂V (100g of fatty acid) is reacted;

wherein the obtained autoxidisable vinyl polymer has:

i) a vinyl polymer backbone in an amount of 25% to 75% relative to the weight of the autoxidisable vinyl polymer;

ii) a fatty acid residue in an amount of 25% to 75% relative to the weight of the autoxidisable vinyl polymer;

iii) -T from 60 ℃ to +20 ℃_g；

iv) a weight average molecular weight (M) of 3,500 to 50,000g/mol_w) (ii) a And

v) PDi from 2 to 10.

Preferably, in one embodiment of the present invention, the resulting autoxidisable vinyl polymer comprises a vinyl polymer backbone in an amount of from 25% to 72%, more preferably from 25% to 63%, most preferably from 25% to 59% by weight of the autoxidisable vinyl polymer. Suitably, where the composition is solvent based, the autoxidisable vinyl polymer comprises a vinyl polymer backbone in an amount of from 25% to 55% by weight of the autoxidisable vinyl polymer.

Preferably, in another embodiment of the present invention, the resulting autoxidisable vinyl polymer comprises fatty acid residues in an amount of from 28% to 75%, more preferably from 37% to 75%, most preferably from 41% to 75% relative to the weight of the autoxidisable vinyl polymer.

Preferably, the at least one other ethylenically unsaturated vinyl monomer (ii) in step (I) is not styrene, alpha-methylstyrene, vinyltoluene and/or mixtures thereof. More preferably, the at least one other ethylenically unsaturated vinyl monomer does not include any styrenic monomer.

Preferably, the compositions of the present invention are substantially free of cationic quaternary ammonium materials.

Preferably, the epoxy-functionalized vinyl polymer (prepared prior to fatty acid functionalization as described herein) has a number average molecular weight (M) of from 1500 to 10000g/mol, more preferably from 1600 to 5000g/mol, most preferably from 1700 to 4000g/mol_n)。

At least 70% of all epoxy groups present in the epoxy-functionalized polymer obtained as described herein are reacted with the fatty acid.

Preferred compositions of the present invention produce coatings having a show-through value (as defined herein) of less than 7 gloss units, more preferably less than 4 gloss units, most preferably less than 2 gloss units.

Preferably, the initial matte gloss should not significantly degrade over time. This can be measured by "gloss decay" which is defined as the difference between the initial matte gloss and the matte gloss measured at a later specified time. For example, "gloss decay (" n "days)" is calculated as the difference between the initial matte gloss (measured 1 day after film formation) minus the matte gloss measured "n" days after film formation (i.e., in this case, n is always > 1). Preferably, gloss decay is measured 4 days, more preferably 7 days, most preferably 14 days after film formation. Preferred gloss decay values (e.g. after the respective time periods given above) are less than 14 gloss units, more preferably less than 10 gloss units, most preferably less than 7 gloss units, in particular less than 4 gloss units.

Without wishing to be bound by any theory, it is believed that the vinyl polymers of the present invention have a comb-type structure, which allows for excellent control of the molecular weight distribution to obtain a relatively narrow distribution, resulting in good flow, reduced show-through and rapid drying. In contrast, conventional vinyl polymers are generally highly branched, which are typically used near their gel point. The vinyl polymers of the invention also have better hydrolytic stability and their backbone is more resistant to hydrolysis. These properties are particularly important for decorative coatings that may be stored on the shelf for a long period of time.

The polymers of the present invention have a narrow molecular weight distribution (PDi) and a relatively small weight average molecular weight (Mw), and thus have an improved balance of Mw and PDi. Because such polymers contain less low molecular weight materials, the compositions of the present invention (containing the above polymers) can be dried quickly, e.g., with short dust holding times and/or short tack-free times. The compositions of the present invention also have other advantages. Since the amount of high molecular weight materials is reduced, they can be prepared at lower viscosities. For example, in solvent-based systems, less solvent is required to achieve a certain viscosity; in aqueous systems, lower viscosity can reduce print-through. Alternatively, compositions having solvent content similar to the prior art but higher overall molecular weight can be prepared. It is also possible to prepare the compositions of the invention with a high solids content.

M_pIs the molecular weight of the strongest signal (i.e., the peak apex) in the chromatogram obtained by measuring the molecular weight of the composition of the invention using Gel Permeation Chromatography (GPC). M_pAlso known as peak value M_w。M_pValues are found in model Size Exclusion Liquid Chromatography, W.W.Yau, J.K.Kirkland and D.D.Bly, John Wiley&Sons, USA, 1997.

The composition of the invention may also comprise one or more autoxidisable reactive diluents, wherein the diluent has one or more of the following properties:

I)M_p1700 to 4000 g/mol;

II) PDi from 1 to 2; and/or

III) oil content > 50%.

The content of reactive diluent in the composition according to the invention is from 0% to 50%, more preferably from 5% to 50%, with respect to the autoxidisable vinyl polymer.

The term "oil content" as used herein refers to the percentage of oil (i.e., miscible in liquid state in organic solvents) in a resin or polymer relative to the weight of the resin or polymer, and can be measured by any conventional method known to those of ordinary skill in the art.

Preferred reactive diluents (which may or may not be autoxidisable and/or have the properties given above) may also have one or more of the following properties:

mn > 1000g/mol, more preferably > 1500g/mol, most preferably > 2000 g/mol;

mn is less than 5000g/mol, more preferably less than 4000g/mol, in particular less than 3500 g/mol; and/or

Alternatively (e.g. where the reactive diluent is autoxidisable), 60 to 90 wt%, more preferably 75 to 90%, most preferably 80 to 90% of the fatty acid residues have 50 to 175, more preferably 80 to 150g I₂/(weight of 100g sample) iodine value.

Preferably, the autoxidisable vinyl polymer is cross-linked at ambient temperature. By natural oxidative crosslinking is meant: the crosslinking results from oxidation (usually involving a free radical mechanism) occurring in the presence of air, preferably metal catalyzed, resulting in the formation of covalent bonds. Suitable autoxidation is provided, for example, by fatty acid residues containing unsaturation, allyl-functionalized residues, and/or β -ketoester groups, preferably by fatty acid residues containing unsaturation.

As used herein, "fatty acid residue" (or FA residue) refers to fatty acids, simple derivatives thereof (such as esters (e.g., esters), salts, soaps, oils, fats, and/or waxes), and mixtures thereof. As used herein, "fatty acid" refers to any unbranched, acyclic (preferably substantially linear) predominantly aliphatic carboxylic acid comprising essentially an aliphatic hydrocarbon chain and at least one carboxyl group (preferably one terminal carboxyl group, i.e. located at the end of the chain), preferably consisting of an aliphatic hydrocarbon chain and at least one carboxyl group (preferably one terminal carboxyl group, i.e. located at the end of the chain). The fatty acids may contain a limited number of other substituents (such as hydroxyl groups) and may be saturated, monounsaturated, or polyunsaturated.

The fatty acid residues may be derived from one or more natural and/or artificial sources. Natural sources include animal sources and/or plant sources. Animal sources may include animal fats, butter fats, fish oils, lard, liver fats, whale and/or tallow, and waxes. Examples of waxes are beeswax, candelilla wax (candelilla) and/or montan wax. The vegetable source may comprise waxes and/or oils, such as vegetable oils and/or non-vegetable oils. Examples of vegetable oils are balsam pear, borage, calendula, canola, castor, tung oil (china wood), coconut, pine nut, corn, cottonseed, dehydrated castor, linseed (flaxseed), grape seed, Jacaranda mimosifolia seed, linseed (Linseed), olive, palm kernel, peanut, pomegranate seed, rapeseed, safflower, snake melon, soybean (bean), sunflower, tung tree and/or wheat. Man-made sources include synthetic waxes (such as microcrystalline waxes and/or paraffin waxes), distilled tall oil (a by-product of processing pine wood), and/or synthetics (e.g., by chemical and/or biochemical methods). Fatty oil residues having conjugated double bonds may be obtained by catalytic isomerization of natural fatty acids and/or dehydrated castor oil. The conjugated oil is preferably obtained by dehydration of castor oil. The fatty acid residues are obtained and/or obtainable from a variety of the above sources and/or other sources not listed herein.

Preferred fatty acid residues may include those having 4 to 36, more preferably 8 to 26, most preferably 10 to 24, particularlyFatty acids of 12 to 22 carbon atoms. Generally, fatty acids obtained from natural sources have an even number of carbon atoms due to their biosynthetic process; while fatty acids having an odd number of carbon atoms may also be used in the present invention. The fatty acid residue may comprise a fatty acid having one or more carboxylic acid groups, such as a dimerised fatty acid or a trimerised fatty acid. Preferred fatty acids are monofunctional carboxylic acids, more preferably C_10-24Monofunctional carboxylic acids, most preferably C_12-22Linear monofunctional terminal carboxylic acids.

The fatty acid residues may also comprise one or more saturated fatty acids and/or oils, as long as oxidative drying of the polymer is unaffected, but at least some unsaturated fatty acids are required for autoxidation. Generally, the more unsaturation, the faster the autoxidation drying.

Iodine values can be used to indicate the amount of unsaturation contained in the fatty acid, with higher iodine values indicating more unsaturated double bonds are present. Preferably, the unsaturated residues used herein have a value of greater than or equal to 50, more preferably greater than or equal to 80, most preferably greater than or equal to 100g I₂V average iodine value of (100g fatty acid). Preferably, the fatty acid residues used herein have a value of less than or equal to 200, more preferably less than or equal to 180, most preferably less than or equal to 150g I₂V average iodine value of (100g fatty acid). The iodine value may be measured in a conventional manner or, preferably, in the manner described in the test modes herein.

To determine the amount of fatty acid residues used to obtain the vinyl polymer of the present invention, it is appropriate to calculate the weight of the fatty acid reactant by: including the carbonyl group in the terminal acid group of the fatty acid molecule, but not including the hydroxyl group in the terminal acid group of the fatty acid molecule.

Preferably, the minimum amount of fatty acid residues in the autoxidisable vinyl polymer is greater than or equal to 35%, more preferably greater than or equal to 40%, most preferably greater than or equal to 45%, in particular greater than or equal to 48% by weight of the polymer.

Preferably, the maximum amount of fatty acid residues in the autoxidisable vinyl polymer is less than or equal to 68%, more preferably less than or equal to 62%, most preferably less than or equal to 58% by weight of the polymer.

Preferably, the fatty acid residue comprises C_10-30Fatty acids, more preferably C_16-20Fatty acids in a content greater than or equal to 80% relative to the weight of fatty acid residues. More preferably, the fatty acid residue comprises essentially C_10-30Fatty acid (specifically C)_16-20Fatty acids), most preferably from C_10-30Fatty acid (specifically C)_16-20Fatty acids).

If the fatty acid residue comprises saturated fatty acids, the content of saturated fatty acids is less than or equal to 50%, more preferably less than or equal to 20%, most preferably between 3% and 18% by weight relative to the weight of the fatty acid residue.

Preferred vinyl polymers are those wherein the autoxidisable groups are derived primarily from fatty acid residues. More preferably, the fatty acid residue comprises predominantly unsaturated fatty acids, most preferably, the fatty acid residue comprises essentially unsaturated fatty acids. Useful unsaturated fatty acids have two or more double bonds, and more preferably the unsaturated fatty acid is a conjugated fatty acid.

Preferably, at least 40% (more preferably at least 60%) by weight of the unsaturated fatty acids in the fatty acid residue are fatty acids containing at least two ethylenically unsaturated groups (i.e. polyunsaturated fatty acids).

Preferred fatty acid residues comprise at least one conjugated fatty acid. The total amount of conjugated fatty acids may be greater than 0%, preferably ≥ 10%, by weight relative to the weight of unsaturated fatty acids. The total amount of conjugated fatty acids may be less than or equal to 70%, preferably less than or equal to 55%, more preferably less than or equal to 40%, relative to the weight of unsaturated fatty acids. The autoxidisable vinyl polymer may be derived from a mixture of conjugated and non-conjugated fatty acids.

Some autoxidisable coating compositions have known problems as follows: the resulting coatings have a tendency to yellow, particularly where the autoxidisable groups are derived from polyunsaturated fatty acids such as those described herein. This may be unacceptable depending on the desired color of the resulting coating.

Thus, in another embodiment of the present invention to reduce yellowing, preferred autoxidisable vinyl polymers are those wherein the unsaturated fatty acid residue comprises a minor amount of a highly polyunsaturated fatty acid. For example, the more yellowing resistant vinyl polymer is derived from and/or obtainable from fatty acid residues comprising less than or equal to 10%, more preferably less than or equal to 7%, most preferably less than or equal to 4%, especially less than or equal to 2% of fatty acids having three or more double bonds by weight relative to the total fatty acids. Examples of fatty acids containing three or more double bonds are given herein

Preferred compositions of the present invention have an initial yellowness value of less than or equal to 10, more preferably less than or equal to 7, and most preferably less than or equal to 4, as determined using the test method described herein. Preferred compositions show only a small increase in yellowness (. DELTA.b value) after 3 weeks storage in the dark at 52 ℃, preferably (. DELTA.b) is less than or equal to 10, still more preferably ≦ 7, most preferably ≦ 5, in particular ≦ 3.

In yet another embodiment of the present invention (e.g., where yellowing is not a concern), preferred autoxidisable vinyl polymers are those where the unsaturated fatty acid residue comprises a greater amount of highly polyunsaturated fatty acids (such as fatty acids having three or more double bonds) as this may improve the rate of autoxidative drying.

Preferably, the unsaturated fatty acid is covalently bound to the vinyl polymer in a one-step process either by using a fatty acid functionalized vinyl monomer or by reaction of the fatty acid and the vinyl polymer.

Preferably, glycidyl esters of unsaturated fatty acids are not used in the preparation of autoxidisable vinyl polymers, as the synthesis of these glycidyl esters requires toxic raw materials such as epichlorohydrin which would also give chlorine-containing waste, which is undesirable. Glycidyl esters of unsaturated fatty acids are epoxy-functionalized fatty acid materials (usually number average molecules)Quantity (M)_n) Less than 400) in which the acid groups have reacted to give glycidyl end groups.

Optionally, the fatty acid residue may also comprise one or more alkynyl groups and/or one or more (non-carboxyl) hydroxyl groups.

Some non-limiting examples of common fatty acids that may be used in the present invention are listed below in the form of their systematic (IUPAC) name and known common names (in brackets). It will be appreciated that in practice most fatty acid residues (especially those derived from natural sources) comprise mixtures of some of these acids as well as other acids not specifically enumerated herein.

The saturated fatty acids may be selected from: butyric acid [ butyric acid ]](C₄H₈O₂) Valeric acid [ valeric acid ]](C₅H₁₀O₂) Hexanoic acid [ caproic acid](C₆H₁₂O₂) Heptanoic acid [ thaumaric acid ]](C₇H₁₄O₂) Octanoic acid [ caprylic acid ]](C₈H₁₆O₂) Pelargonic acid [ pelargonic acid ]](C₉H₁₈O₂) Capric acid](C₁₀H₂₀O₂) Dodecanoic acid [ lauric acid ]](C₁₂H₂₄O₂) Myristic acid [ myristic acid ]](C₁₄H₂₈O₂) Hexadecanoic acid [ palmitic acid ]](C₁₆H₃₂O₂) Heptadecanoic acid [ nacreous acid and daturanic acid](C₁₇H₃₄O₂) Stearic acid [ stearic acid ]](C₁₈H₃₆O₂) Eicosanoic acid [ arachidic acid ]](C₂₀H₄0O₂) Behenic acid, behenic acid](C₂₂H₄₄O₂) Lignoceric acid, tetracosanoic acid](C₂₄H₄₈O₂) Cerotic acid](C₂₆H₅₂O₂) Dicoceric acid, dicoceric acid](C₂₇H₅₄O₂) Octacosanoic acid [ montanic acid ]](C₂₈H₅₆O₂) Melissic acid, melissic acid](C₃₀H₆₀O₂) Triacontanoic acid [ lac lacquer wax acid ]](C₃₂H₆₄O₂) Thirty-threeAcids [ cermic acids and pediculosis lice acids ]](C₃₃H₆₆O₂) Triacontanoic acid](C₃₄H₆₈O₂) And/or thirty-five acids [ wax plastic acid ]](C₃₅H₇₀O₂)。

The monounsaturated fatty acid can be selected from (Z) -deca-4-enoic acid [ obtusilic acid ]](C₁₀H₁₈O₂) (Z) -dec-9-enoic acid [ caproleic acid ]](C₁₀H₁₈O₂) (Z) -undecylenoic acid and 10-hendecenoic acid](C₁₁H₂₀O₂) (Z) -Docosa-4-enoic acid](C₁₂H₂₂O₂) (Z) -dodec-5-enoic acid (lauroleic acid) (C)₁₂H₂₂O₂) (Z) -tetradeca-4-enoic acid [ crude leaseic acid ]](C₁₄H₂₆O₂) (Z) -tetradeca-5-enoic acid [ sperm whale acid ]](C₁₄H₂₆O₂) (Z) -tetradeca-9-enoic acid [ myristoleic acid ]](C₁₄H₂₆O₂) (Z) -hexadec-6-enoic acid [ sapienic acid ]](C₁₆H₃₀O₂) (Z) -hexadec-9-enoic acid [ palmitoleic acid ]](C₁₆H₃₀O₂) (Z) -Octadeca-6-enoic acid [ petroselinic acid ]](C₁₈H₃₄O₂) (E) -Octadeca-9-enoic acid [ elaidic acid](C₁₈H₃₄O₂) (Z) -Octadeca-9-enoic acid [ oleic acid ]](C₁₈H₃₄O₂) (Z) -Octadeca-11-enoic acid [ vaccenic acid and ascopic acid](C₁₈H₃₄O₂) (Z) -eicosa-9-enoic acid [ gadoleic acid ]](C₂₀H₃₈O₂) (Z) -eicosa-11-enoic acid [ megacephalin acid](C₂₀H₃₈O₂) (Z) -docosahexen-11-enoic acid [ cetenoic acid](C₂₂H₄₂O₂) (Z) -docosahexen-13-enoic acid [ erucic acid](C₂₂H₄₂O₂) And/or (Z) -tetracos-15-enoic acid [ nervonic acid ]](C₂₄H₄₆O₂)。

The di-unsaturated fatty acids may be selected from: (5Z, 9Z) -hexadeca-5, 9-dienoic acid (C)₁₆H₂₈O₂) (5Z, 9Z) -octadeca-5, 9-dienoic acid [ taxoleic acid ]](C₁₈H₃₂O₂) (9Z, 12Z) -octadeca-9, 12-dienoic acid [ linoleic acid ]](C₁₈H₃₂O₂) (9Z, 15Z) -octadeca-9, 15-dienoic acid (C)₁₈H₃₂O₂) And/or (7Z, 11Z) -eicosa-7, 11-dienoic acid [ dihydromotaxoic acid](C₂₀H₃₆O₂)。

The tri-unsaturated fatty acids may be selected from: (5Z, 9Z, 12Z) -heptadeca-5, 9, 12-trienoic acid (C)₁₇H₂₈O₂) (3Z, 9Z, 12Z) -octadeca-3, 9, 12-trienoic acid (C)₁₈H₃₀O₂) (5Z, 9Z, 12Z) -octadeca-5, 9, 12-trienoic acid](C₁₈H₃₀O₂) (6Z, 9Z, 12Z) -octadeca-6, 9, 12-trienoic acid [ gamma-linolenic acid and GLA](C₁₈H₃₀O₂) (8E, 10E, 12Z) -octadeca-8, 10, 12-trienoic acid](C₁₈H₃₀O₂) (8Z, 10E, 12Z) -octadeca-8, 10, 12-trienoic acid](C₁₈H₃₀O₂) (9E, 11E, 13E) -octadeca-9, 11, 13-trienoic acid [ beta-eleostearic acid and beta-oleostearic acid](C₁₈H₃₀O₂) (9E, 11E, 13Z) -octadeca-9, 11, 13-trienoic acid [ catalpic acid ]](C₁₈H₃₀O₂) (9Z, 11E, 13E) -octadeca-9, 11, 13-trienoic acid [ alpha-eleostearic acid and alpha-oleostearic acid](C₁₈H₃₀O₂) (wherein, the alpha-eleostearic acid accounts for more than 65% of fatty acid in tung oil), (9Z, 11E, 13Z) -octadeca-9, 11, 13-trienoic acid [ punicic acid and trichosanthes acid ]](C₁₈H₃₀O₂) (9Z, 11E, 15Z) -octadeca-9, 11, 13-trienoic acid](C₁₈H₃₀O₂) (9Z, 13E, 15Z) -octadeca-9, 13, 13-trienoic acid (C)₁₈H₃₀O₂) (9Z, 12Z, 15Z) -octadeca-9, 12, 15-trienoic acid [ alpha-linolenic acid and ALA](C₁₈H₃₀O₂) 5Z, 8Z, 11Z-eicosa-5, 8, 11-trienoic acid [ di-homo-gamma-linolenic acid ]](C₂₀H₃₄O₂) (5Z, 11Z, 14Z) -eicosa-8, 11, 14-trienoic acid [ sciadonic]acid(C₂₀H₃₄O₂) and/or (8Z, 11Z, 14Z) -eicosa-8, 11, 14-trienoic acid [ mead acid](C₂₀H₃₄O₂)。

The tetraunsaturated fatty acids may be selected from: (6Z, 8Z, 10Z, 12Z) -hexadeca-6, 8, 10, 15-tetraenoic acid (C)₁₆H₂₄O₂) (6Z, 8Z, 10Z, 12Z) -octadecane-6, 8, 10, 12-tetraenoic acid (C)₁₈H₂₈O₂) (6Z, 9Z, 12Z, 15Z) -octadeca-6, 9, 12, 15-tetraenoic acid](C₁₈H₂₈O₂) (9Z, 11E, 13E, 15Z) -octadecane-9, 11, 13, 15-tetraenoic acid [ alpha ] -parinaric acid](C₁₈H₂₈O₂) (9Z, 11Z, 13Z, 15Z) -octadecane-9, 11, 13, 15-tetraenoic acid [ beta ] -parinaric acid](C₁₈H₂₈O₂) (5Z, 8Z, 11Z, 14Z) -eicosa-5, 8, 11, 14-tetraenoic acid [ arachidonic acid and AA ]](C₂₀H₃₂O₂) , (6Z, 8Z, 10Z, 12Z) -eicosa-6, 8, 10, 12-tetraenoic acid (C)₂₀H₃₂O₂) (8Z, 11Z, 14Z, 11Z) -eicosa-8, 11, 14, 17-tetraenoic acid (C)₂₀H₃₂O₂) (6Z, 8Z, 10Z, 12Z) -docosatetraenoic acid (C)₂₂H₃₆O₂) And/or (7Z, 10Z, 13Z, 16Z) -docosatetraenoic acid (C)₂₂H₃₆O₂)。

The pentaunsaturated fatty acids may be selected from: (x, 6Z, 8Z, 10Z, 12Z) -hexadeca-x, 6, 8, 10, 12-pentaenoic acid (C)₁₆H₂₂O₂) Wherein x refers to a fifth double bond, optionally in a position not conjugated to the other four conjugated olefinic double bonds; (x ', 6Z, 8Z, 10Z, 12Z) -eicosa-x', 6, 8, 10, 12-pentaenoic acid(s) (C)₂₀H₃₀O₂) Wherein x' refers to a fifth double bond, optionally in a position not conjugated to the other four conjugated olefinic double bonds; (5E, 7E, 9E, 14Z, 17Z) -eicosa-5, 8, 11, 14, 17-Pentaenoic acid (C)₂₀H₃₀O₂) (ii) a (5Z, 7E, 9E, 14Z, 17Z) -eicosa-5, 8, 11, 14, 17-pentaenoic acid (C)₂₀H₃₀O₂) (ii) a (5Z, 8Z, 11Z, 14Z, 17Z) -eicosa-5, 8, 11, 14, 17-pentaenoic acid [ EPA](C₂₀H₃₀O₂) (ii) a (7Z, 10Z, 13Z, 16Z.19Z) -docosapentaenoic acid [ clupanodonic acid ] clupanodonic acid](C₂₂H₃₄O₂) (ii) a (4Z, 7Z, 10Z, 13Z, 16Z) -docosapentaenoic acid [ osbond acid ] or a salt thereof](C₂₂H₃₄O₂) And/or (7Z, 10Z, 13Z, 16Z, 19Z) -docosapentaenoic acid [ DPA ] or a pharmaceutically acceptable salt thereof](C₂₂H₃₄O₂)。

The hexaunsaturated fatty acids may be selected from: (x ", y", 6Z, 8Z, 10Z, 12Z) -eicosa-x ", y", 6, 8, 10, 12-hexaenoic acid (C)₂₀H₂₈O₂) Wherein x "and y" refer to the fifth and sixth double bonds, optionally in positions that are not conjugated to the other four conjugated olefinic double bonds; (4Z, 7Z, 10Z, 13Z, 16Z, 19Z) -docosahexa-4, 7, 10, 13, 16, 19-enoic acid [ DHA](C₂₂H₃₂O₂) And/or (6Z, 9Z, 12Z, 15Z, 18Z, 21Z) -tetracosenic-6, 9, 12, 15, 18, 21-hexaenoic acid [ nicotinic acid ]](C₂₄H₃₆O₂)。

The heptaunsaturated fatty acid may be selected from (w ' ", x '", y ' ", 6Z, 8Z, 10Z, 12Z) -docosal-w '", x ' ", y '", 6, 8, 10, 12-heptaenoic acid (C ' ")₂₂H₃₀O₂) Wherein w ' ", x '" and y ' "refer to the fifth, sixth and seventh double bonds, optionally in positions which are not conjugated with the other four conjugated olefinic double bonds; and/or (4Z, 7Z, 9Z, 11Z, 13Z, 16Z, 19Z) -docosae-4, 7, 9, 11, 13, 16, 19-heptaenoic acid](C₂₂H₃₀O₂)。

The alkynyl-functionalized fatty acid may be selected from (9Z) -octadec-9-en-12-ynoic acid [ Cycloyangtianoic acid](C₁₈H₃₀O₂)。

The hydroxy-functionalized fatty acid may be selected from 12-hydroxy- (9Z) -octadec-9-enoic acid [ ricinoleic acid ]](C₁₈H₃₄O₃)。

The crosslinking of the vinyl polymer herein is by autoxidation. In a preferred embodiment, metal ion crosslinking is used in combination with an autoxidation mechanism, for example by using a coordinating drying agent well known to those skilled in the art. Alternatively (but less preferably), autoxidation is used in combination with other crosslinking mechanisms known in the art. Other crosslinking mechanisms known in the art include: reaction of alkoxysilane functional groups; schiff base crosslinking; reaction of an epoxy group with an amino group, a carboxylic acid group or a mercapto group; reaction of amino or mercapto groups with ethylenically unsaturated groups (such as fumarate groups and acryloyl groups); reaction of the masked epoxy groups with amino or mercapto groups; reaction of isothiocyanates with amines, alcohols or hydrazines; reaction of an amine (e.g., ethylenediamine or polyfunctional amine-terminated polyalkylene oxide) with a β -diketone (e.g., acetoacetoxy or acetoacetamide) group to form an enamine.

The drying process of the coating composition can be divided into several stages, for example the period of time necessary to achieve a non-stick dust and/or non-stick coating using the tests described herein.

Preferably, the dust tack free time is less than or equal to 4 hours, more preferably less than or equal to 2 hours, most preferably less than or equal to 1 hour.

Preferably, the tack-free time is less than or equal to 10 hours, more preferably less than or equal to 6 hours, most preferably less than or equal to 4 hours, particularly preferably less than 3 hours.

A problem generally encountered with aqueous autoxidisable vinyl polymers is that they have poor hydrolytic stability. This is a particular problem when introducing polymers with bound carboxylic acid groups by reaction with anhydrides, especially when the polymer is in neutralized form. This problem can be significantly reduced by reducing the water solubility of the autoxidisable resin. However, in practice, a balance of hydrolytic stability and water solubility is required.

The autoxidisable vinyl polymer may comprise bound hydrophilic water-dispersing groups. Suitable hydrophilic groups are well known in the art and may be ionic or nonionic water dispersing groups. Preferably, the nonionic water-dispersing group is a polyalkylene oxide group, more preferably a polyethylene oxide group. A small number of segments of the polyethylene oxide group may be replaced by propylene oxide segments and/or butylene oxide segments, but the polyethylene oxide group still contains Ethylene Oxide (EO) as a major component. When the water-dispersing group is polyethylene oxide, the preferred EO chain length is 4 EO units or more, more preferably 8 EO units or more, and most preferably 15 EO units or more. Preferably, if the autoxidisable vinyl polymer comprises polyalkylene oxide groups, the content of polyalkylene oxide (optionally EO) in the vinyl polymer is at least 0% or more, more preferably 2% or more, most preferably 3.5% or more, in particular 5% or more, and/or not more than 50%, preferably 30% or less, most preferably 15% or less, in particular 9% or less, relative to the weight of the autoxidisable vinyl polymer. Preferably, the Mw of the polyalkylene oxide (optionally EO) groups is from 175 to 5000g/mol, more preferably from 350 to 2200g/mol, most preferably from 660 to 2200 g/mol.

Preferred ionic water-dispersing groups are anionic water-dispersing groups, especially carboxylic, phosphoric, phosphonic or sulfonic acid groups. Most preferred are carboxylic, phosphoric or phosphonic acid groups. The anionic water-dispersing groups are preferably wholly or partly in the form of salts. The conversion into the salt form is preferably effected optionally during the preparation of the autoxidisable vinyl polymer and/or during the preparation of the composition of the invention by neutralising the autoxidisable vinyl polymer with a base. Anionic water-dispersing groups may in some cases be provided by using monomers having neutralized acid groups in the synthesis of the autoxidisable vinyl polymer, so that further neutralization is not necessary. If anionic water-dispersing groups are used in combination with nonionic water-dispersing groups, neutralization may not be necessary.

If the anionic water-dispersing base is neutralizedThe base used to neutralize the group is preferably an amine or an inorganic base. Suitable amines include tertiary amines such as triethylamine or N, N-dimethylethanolamine. Suitable inorganic bases include alkali metal hydroxides and carbonates, for example lithium hydroxide, sodium hydroxide and/or potassium hydroxide. Typically, a base is used to provide the necessary counter ion desired for the composition. For example, preferred counterions include tertiary amines or Li⁺、Na⁺、K⁺。

Cationic water-dispersing groups may also be used, but are less preferred. Examples include pyridyl, imidazolyl and/or quaternary ammonium groups (which may be neutralized or permanently ionized).

The autoxidisable vinyl polymer preferably has AN acid value (AV, also known as acid number or AN) of from 0 to 60, more preferably from 0 to 40, most preferably from 0 to 12, in particular from 2 to 8mg KOH/g when in AN aqueous coating composition.

The autoxidisable vinyl polymer preferably has an AV of from 0 to 17, more preferably from 2 to 10mg KOH/g when in a solvent borne coating composition.

The autoxidisable vinyl polymer, if it has carboxylic acid functionality, preferably conforms to the following relationship: ND XaV ≧ 22, more preferably ≧ 27, most preferably ≥ 33mg KOH/g, and ND XaV ≤ 65, more preferably ≤ 60mg KOH/g, where ND refers to the degree to which the carboxylic acid of the polymer is neutralized.

ND is a dimensionless fraction of 0 to 1, which represents the amount of neutralizing agent present in the polymer. For example, if 80% of the acid groups in the polymer are neutralized, then the ND value is 0.8. The reported AV is in units of mg KOH/g, resulting in the product ND × AV having units of mg KOH/g. When the polymer is not neutralized, ND is 0, so ND × AV is also 0.

The autoxidisable vinyl polymer preferably has a hydroxyl number of at least 25, more preferably 48 and/or not more than 135, more preferably 110mg KOH/g.

The aqueous coating composition of the present invention preferably has a pH of at least ≥ 2.0, more preferably ≥ 3.4, most preferably ≥ 5.1 and/or not more than ≤ 9.2, more preferably ≤ 8.4, most preferably ≤ 7.6.

Preferably, the weight average molecular weight (Mw) of the autoxidisable vinyl polymer is at least ≥ 4000, more preferably ≥ 5000, most preferably ≥ 7000, and/or not more than ≤ 40000, more preferably ≤ 35000, most preferably ≤ 25000, in particular ≤ 20000, for example less than ≤ 17000 g/mol. Mw is determined by GPC using polystyrene standards as described herein.

Preferably, most of any crosslinking reaction occurs only after the aqueous coating composition is applied to the substrate, thereby avoiding an excessive increase in molecular weight that may lead to an increase in viscosity of the aqueous coating composition on the substrate at the early stage of drying.

The Molecular Weight Distribution (MWD) of the autoxidisable vinyl polymer has an effect on the viscosity of the vinyl polymer in the composition and thus on print-through. MWD is generally described by polydispersity index (PDi). PDi is defined as the quotient of the weight-average molecular weight and the number-average molecular weight (M)_w/M_n) It is dimensionless. It has been found that for compounds having a specific M_wFor polymers of (2), lower PDi generally results in lower viscosity and improved flow. Preferably, the PDi of the autoxidisable vinyl polymer is not more than 8.3, more preferably not more than 7, most preferably not more than 5, in particular not more than 4 and/or at least not more than 2.5.

Preferably, the weight average particle size of the autoxidisable vinyl polymer (optionally when in an aqueous coating composition) is at least 50nm or more, more preferably 80nm or more, most preferably 120nm or more, in particular 150nm or more. Preferably, at least 80% of the particles have a weight average particle size of 1000nm or less, more preferably 750nm or less, most preferably 550nm or less, in particular 400nm or less.

The weight average particle size may be determined by any suitable method, such as the methods described in the test methods herein.

Glass transition temperature (T) of autoxidisable vinyl polymers_g) (DSC measurement by solid MaterialAnd/or) can vary within wide limits, preferably at least ≥ 60 ℃, more preferably ≥ 40 ℃, more preferably ≥ 25 ℃ and/or preferably no more than +20 ℃, more preferably ≤ 10 ℃, most preferably ≤ 0 ℃, in particular ≤ 5 ℃. Generally, T of autoxidisable vinyl polymers for use in aqueous coating compositions_gMay be from-15 ℃ to 0 ℃ and for solvent-based coating compositions may be from-45 ℃ to-10 ℃.

For use in waterborne coating compositions, the backbone of the autoxidisable vinyl polymer described herein preferably has a Tg of at least 0 ℃ and more preferably at least +10 ℃, more preferably at least +20 ℃, and/or preferably no greater than +90 ℃, more preferably no greater than +60 ℃, and most preferably no greater than +40 ℃.

For use in solvent borne coating compositions, the backbone of the autoxidisable vinyl polymer described herein preferably has a Tg of at least ≧ 25 ℃, more preferably ≧ 5 ℃, more preferably ≧ 10 ℃, and/or preferably no greater than ≦ 60 ℃, more preferably ≦ 45 ℃, and most preferably ≦ 40 ℃.

If Tg cannot be determined by DSC because the first derivative of the DSC curve does not show any discernible maximum, an alternative for determining Tg is to calculate Tg using the following equation which relates the viscosity of a pure vinyl polymer to its Tg (from the Williams-Landau-Ferry [ WLF ] equation):

Ln(η)＝27.6-[40.2x(T-T_g)]/[51.6+(T-Tg)]

wherein:

ln (η) ═ the natural logarithm of the viscosity of the pure polymer expressed in pa.s (in the range of 0.005 to 1s at ambient temperature)^-1Shear rate determination of);

t ═ 23 ℃ ± 1 ℃ (i.e., ambient temperature was used to determine the viscosity of the neat polymer); and

T_gglass transition temperature, in ℃.

Two general approaches can be used to introduce functional groups (such as fatty acid residues or water-dispersing groups) into autoxidisable vinyl polymers: i) using a monomer having a functional group during polymerization to form an autoxidisable polymer having a functional group; or ii) using a monomer bearing a selected reactive group which is subsequently reacted with a compound bearing a functional group and a specific type of reactive group which will react with the selected reactive group on the monomer, thereby attaching the functional group to the autoxidisable vinyl polymer by covalent bonding. Thus, the autoxidisable vinyl polymer may be obtained by polymerising an autoxidisable vinyl monomer with other vinyl monomers or the autoxidisable groups may be attached to the vinyl polymer after free radical polymerisation of the vinyl monomer to produce the vinyl polymer. Preferably, the autoxidisable groups react with the vinyl polymer. More preferably, the vinyl polymer contains epoxy functionality, most preferably glycidyl (meth) acrylate monomers such as GMA.

The autoxidisable vinyl polymer may be prepared from GMA optionally together with other free radically polymerisable ethylenically unsaturated monomers and may contain polymerised units of a wide range of the above monomers, including in particular those conventionally used in the preparation of adhesives for the coatings industry. By "vinyl polymer" herein is meant a homopolymer or copolymer obtained by addition polymerization of one or more ethylenically unsaturated monomers using a free radical initiated process, which may be carried out in an aqueous or non-aqueous medium. Thus, "vinyl monomer" refers to an ethylenically unsaturated monomer.

Examples of vinyl monomers that can be used to form the vinyl polymer include, but are not limited to, 1, 3-butadiene, isoprene, styrene, alpha-methylstyrene, divinylbenzene, acrylonitrile, methacrylonitrile, vinyl ethers, vinyl esters (such as vinyl acetate, vinyl propionate, vinyl laurate and vinyl esters of versatic acids, such as VeoVa 9 and VeoVa 10, VeoVa being a trademark of Shell), heterocyclic vinyl compounds, alkyl esters of monoethylenically unsaturated dicarboxylic acids (such as di-n-butyl maleate and di-n-butyl fumarate) and the acrylic and methacrylic esters of formula 1:

CH₂＝CR¹-COOR²formula 1

In the formula 1, R¹Is H or methyl, R²Is optionally substituted C_1-20Alkyl (preferably C)_1-8Alkyl) or optionally substituted C_3-20Cycloalkyl (preferably C)_3-8A cycloalkyl group),

examples of the above-mentioned acrylic esters and methacrylic esters of formula 1 are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-propyl acrylate, n-propyl methacrylate, and hydroxyalkyl (meth) acrylates such as hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl methacrylate, and modified analogs thereof, such as Tone M-100(Tone is a trademark of UniCaron Carbide Corporation).

Ethylenically unsaturated monocarboxylic, sulfonic and/or dicarboxylic acids such as acrylic acid, methacrylic acid, beta-carboxyethyl acrylate, fumaric acid and/or itaconic acid may be used. Ethylenically unsaturated monomers such as (meth) acrylamide and/or methoxypolyethyleneoxy (meth) acrylate may also be used.

The vinyl monomer may optionally contain functional groups that aid in crosslinking the vinyl polymer in the coating. Examples of such groups include maleic, epoxy, fumaric, acetoacetoxy, β -diketo, acryloyl, methacryloyl, styryl, (meth) allyl, mercapto, keto, or aldehyde groups (such as methyl vinyl ketone MEK, diacetone acrylamide, and (meth) acrolein).

Preferred vinyl oligomers have a backbone made from a monomer system comprising at least 40% relative to the weight of the oligomer of one or more monomers of formula 1. Vinyl oligomers having the preferred backbones described above are defined herein as (meth) acrylic oligomers. Particularly preferred autoxidisable vinyl oligomers are autoxidisable acrylic oligomers (i.e. based mainly on at least one acrylate and/or methacrylate). More preferably, the monomer system constituting the vinyl backbone comprises at least 50%, most preferably at least 60% of the above monomers relative to the weight of the oligomer. The other monomers, if used, in the above-described acrylic-type autoxidisable vinyl oligomer may comprise one or more of the above-described other vinyl monomers and/or may comprise monomers other than the above-described other monomers.

Particularly preferred monomers include butyl acrylate (all isomers), butyl methacrylate (all isomers), methyl methacrylate, ethylhexyl methacrylate, esters of (meth) acrylic acid, acrylonitrile, vinyl acetate.

Monomers that can be used to react fatty acids with vinyl polymers to give fatty acid residues include epoxy-functionalized vinyl monomers such as glycidyl (meth) acrylate (GMA) or 3, 4-epoxy-cyclohexyl methyl-acrylate. Preferably, the batch process is used in a non-aqueous environment, defined as a water content of less than 10%, more preferably less than 2%, most preferably 0% by weight of the total composition.

In a preferred embodiment, 30 to 70 wt% of the epoxy functional monomer is used prior to functionalization to give the autoxidisable vinyl polymer of the invention. Preferably, the vinyl polymer containing the epoxy functional monomer is then reacted with a fatty acid, wherein preferably 0.4 to 0.95 equivalents of the fatty acid react with the functional groups present on the vinyl polymer. For this purpose, we believe that the hydroxyl function can react once with the fatty acid, whereas the epoxy function can react twice due to the additionally formed hydroxyl group upon ring opening. A particularly preferred epoxy functional monomer is GMA.

The vinyl polymer backbone obtained in step I of the process of the present invention preferably comprises at least 15% or more, more preferably 20% or more, most preferably 30% or more, in particular 35% or more and/or not more than 100% or less, more preferably 85% or less, still more preferably 80% or less, most preferably 70% or less, in particular 65% or less epoxy-functionalized vinyl monomer by weight of the vinyl polymer backbone. The vinyl polymer backbone obtained in step I of the process of the present invention preferably comprises 35% to 60%, more preferably 40% to 55%, most preferably 47% to 53%, e.g. 50% GMA relative to the weight of the vinyl polymer backbone.

GMA has the advantage over HE (M) A-based acrylates of maintaining a narrower PDi after functionalization with fatty acids.

Preferably, the vinyl polymer prepared in step I (prior to fatty acid functionalization) comprises less than or equal to 5%, more preferably less than or equal to 2%, most preferably 0% of hydroxy-functional monomers (such as HEA and HEMA) relative to the weight of the vinyl polymer prepared in step I.

Preferably, the vinyl polymer prepared in step I (prior to fatty acid functionalization) comprises less than or equal to 40%, more preferably less than or equal to 25%, most preferably less than or equal to 15% of styrenic monomers relative to the weight of the vinyl polymer prepared in step I.

Preferably, the vinyl polymer prepared in step I (prior to fatty acid functionalization) is substantially free of chlorine-containing monomers. By "substantially free" is meant that the amount of monomer is 1% by weight or less, more preferably 0.5% by weight or less, and specifically 0% by weight or less, relative to the weight of the vinyl polymer produced in step I.

Preferably, the autoxidisable vinyl polymer obtained by the process of the invention is substantially free of urethane groups (-NH-C (═ O) -O-), as the presence of such groups can result in higher molecular weight, broader molecular weight distribution, higher viscosity, lower solids content and poorer flowability.

The autoxidisable vinyl polymers are preferably prepared by free radical polymerisationAlthough anionic polymerization may be used in some cases. Free radical polymerization may be carried out by techniques known in the art, for example, by emulsion polymerization, solution polymerization, suspension polymerization, or bulk polymerization. For example, the vinyl polymer may be prepared in solvent/bulk and then dispersed in water, which may be accomplished by: a) neutralizing the acid groups; b) having already neutralized acid groups (e.g. SO)₃Na); c) adding a surfactant; and/or any combination of the above.

It is desirable to use a free radical generating initiator to initiate vinyl polymerization to free-radically polymerize the vinyl monomer to form a crosslinkable vinyl, an autoxidisable vinyl polymer or a precursor vinyl autoxidisable vinyl polymer. Suitable free radical generating initiators include inorganic peroxides such as hydrogen peroxide; alkyl hydroperoxides such as tert-butyl hydroperoxide and cumyl hydroperoxide; dialkyl peroxides such as di-t-butyl peroxide and the like; and azo initiators, such as AIBN; mixtures may also be used. In some cases, the peroxy compound is advantageously combined with a suitable reducing agent, such as Na or K metabisulfite or Na or K bisulfite and erythorbic acid (redox system).

It may be desirable to add chain transfer agents to the free radical polymerization process to control molecular weight. Conventional chain transfer agents such as mercaptans, sulfides, disulfides and halocarbons may be used. A technique known as Catalytic Chain Transfer Polymerization (CCTP) can be used to provide low molecular weight. In this case, the radical polymerization is carried out using a radical-forming initiator and using catalytic amounts of a selected transition metal complex, in particular a selected cobalt chelate, as a Catalytic Chain Transfer Agent (CCTA). Such techniques have been described, for example, in J.Polym.chem.Ed. of N.S.Enikolopyyan et al, Vol 19, 879(1981), US 4526945, US 4680354, EP-A-0196783, EP-A-0199436, EP-A-0788518 and WO-A-87/03605.

The use of catalytic chain transfer agents has four important benefits:

a) very low concentrations of CCTA (typically 1 to 1000ppm relative to the weight of the vinyl polymer) are required to obtain the preferred low molecular weight polymers, and therefore the polymers do not have the odor normally associated with conventional chain transfer agents.

b) Vinyl autoxidisable vinyl polymers prepared by CCTP contain unsaturated end groups on some, although not on every vinyl polymer molecule. Such unsaturated end groups may participate in autoxidation, for example, in a fatty acid crosslinking system. Thus, the crosslinkable vinylic autoxidisable vinylic polymers of the invention have not only autoxidisable crosslinking groups (including unsaturated groups derived from fatty acids) but also unsaturated end groups derived from CCTP.

c) The PDi of vinyl autoxidisable vinyl polymers prepared by CCTP is narrower than the PDi of vinyl polymers obtainable by using low Mw autoxidisable vinyl polymers with conventional chain transfer agents.

d) When epoxy functional monomers are used, CCTP has the following advantages: unlike other conventional chain transfer agents such as thiols, which react with peroxides, CCTA does not react with epoxy groups.

The autoxidisable vinyl polymer may be dispersed in water using techniques well known in the art. When such autoxidisable vinyl polymers have a low acid number or a low degree of neutralization, an external surfactant is generally required to disperse the polymer in water. Mixing under high shear may also be used to aid dispersion. Suitable surfactants include, but are not limited to, conventional anionic surfactants, cationic surfactants, and/or nonionic surfactants, such as Na, K, and NH dialkylsulfosuccinates₄Salts, sulfated oils of Na, K and NH₄Salts, Na, K and NH of alkylsulfonic acids₄Salts, Na, K and NH of alkylsulfuric acids₄Salts, alkali metal salts of sulfonic acids; fatty alcohols, ethoxylated fatty acids and/or fatty amides, and Na, K and NH of fatty acids₄Salts (such as Na stearate and Na oleate). Other anionic surfactants include alkyl or (alk) aryl groups linked to a sulphonic acid groupA linker, a linker in which an alkyl or (alk) aryl group is attached to a sulfate half-ester group, which in turn is attached to a polyethylene glycol ether group, a linker in which an alkyl or (alk) aryl group is attached to a phosphonic acid group, a linker in which an alkyl or (alk) aryl group is attached to a phosphoric acid analog and a phosphate ester, or a linker in which an alkyl or (alk) aryl group is attached to a carboxylic acid group. Cationic surfactants include those in which an alkyl or (alk) aryl group is attached to a quaternary ammonium salt group. The nonionic surfactant includes polyethylene glycol ether compounds and polyethylene oxide compounds. The surfactant may also be a polymeric surfactant, which is also described as a wetting agent.

The total amount of surfactant used in the aqueous composition of the present invention is preferably at least 0.1% or more, more preferably 1% or more, most preferably 3% or more and/or preferably not more than 11%, more preferably not more than 9%, most preferably not more than 7% by weight of the autoxidisable vinyl polymer. Preferably, a mixture of anionic and nonionic surfactants is used.

If the aqueous composition comprises an anionic surfactant, the anionic surfactant may comprise Ethylene Oxide (EO) groups in an amount of preferably not more than 90%, more preferably not more than 70%, most preferably not more than 55% and/or preferably at least not less than 10% and/or not more than 20% relative to the weight of the surfactant. Preferred anionic surfactants comprise sulfate, sulfonate, phosphate and/or phosphonate groups.

The aqueous composition may comprise a nonionic surfactant in an amount of preferably at least 0.1% or more, more preferably 0.5% or more, still more preferably 1% or more, most preferably 1.5% or more, and/or preferably not more than 12% or less, more preferably not more than 9% or less, still more preferably not more than 5% or less, most preferably not more than 3.5% by weight of the vinyl polymer solids.

Optionally, to reduce the effect of shrinkage, the composition comprises an amount of ionic surfactant preferably at least 0.1% or more, more preferably 0.5% or more, still more preferably 1% or more, most preferably 1.5% or more, and/or preferably not more than 12%, more preferably not more than 9%, most preferably not more than 5% by weight of the vinyl polymer solids.

It is also possible to use dispersants (such as dispersing compounds and/or dispersing resins, which are preferably autoxidisable, such as described in EP1870442 or W-3000 available from Perstor, in place of or in combination with more conventional surfactants alternatively, if used, the amount of surfactant relative to the weight of solid resin is preferably at least 0.1% or more, more preferably 3% or more, most preferably 5% or more, and/or preferably not more than 30% or less, more preferably 20% or less, most preferably 12% or less).

The solids content of the aqueous coating composition of the invention is preferably at least 33% or more, more preferably 38% or more, most preferably 42% or more, in particular 49% or more, and/or preferably not more than 72% or less, more preferably < 65% or less, most preferably 63% or less, relative to the total weight of the composition.

The solvent-based coating composition of the present invention preferably has a solids content of 65% or more, more preferably 70% or more, most preferably 75% or more, particularly 80% or more, relative to the total weight of the composition. In theory, the solvent-based composition may have 100% solids because the molecular weight of the polymer component is relatively low. In practice, the upper limit of the solids content of the solvent-based compositions of the invention is generally from 95% to 100% relative to the weight of the composition.

Surprisingly, the coatings obtained from the high solids solvent-based compositions of the present invention have a short dust-free time, are fast to block and mar, and can be sanded in a short time after application. These beneficial properties are not generally seen in conventional autoxidisable coatings having high solids content.

Both the aqueous coating composition and the solvent-based coating composition of the present invention are particularly useful in coating formulations (i.e., compositions intended to be applied to a substrate without further treatment or addition thereof) or to provide the major component of a coating formulation. Examples of coating compositions are protective or decorative coating compositions (e.g. paints, lacquers or varnishes). To prepare the coating composition, the initially prepared composition may optionally be further diluted with water and/or organic solvent, and/or combined with other ingredients; or the initially prepared composition may be brought into a more concentrated form by optionally evaporating water and/or organic components of the liquid medium of the initially prepared composition.

The organic solvent may optionally be added before, during and/or after the polymerization process used to prepare the autoxidisable vinyl polymer to control viscosity. Examples of the solvent include water-miscible solvents such as propylene glycol-based solvents, specifically propylene glycol monomethyl ether and dipropylene glycol monomethyl ether; and glycol ethers such as butyl diglycol. Optionally, no organic solvent is added.

Co-solvents well known in the coating art are organic solvents used in aqueous compositions to improve their drying characteristics, in particular to reduce the minimum film-forming temperature. The co-solvent may be a solvent incorporated or used during the preparation of the autoxidisable vinyl polymer and/or may be added during the formulation of the aqueous composition. The co-solvent content in the aqueous composition of the invention may preferably be at least 2% by weight, more preferably 3.5% by weight and/or preferably not more than 15%, more preferably not more than 9%, most preferably not more than 6% by weight of solids. Most preferably, substantially no co-solvent is used, as this results in improved storage stability and better ecology.

In general, it has been found that aromatic or heterocyclic nitrogen-containing ligands (excluding pyridine) or aromatic and aliphatic primary and secondary (di) amines will extend drying times to a considerable extent (as reported in Coordinationchemistry Reviews 249(2005) 1709-1728). Examples include heterocyclic nitrogen-containing solvents such as N-methylpyrrolidone (NMP) and N-ethylpyrrolidone.

Preferably, the aqueous coating composition contains no more than 13%, more preferably no more than 10%, most preferably no more than 5%, and particularly no more than 0.5% NMP by weight relative to polymer solids.

Preferably, the aqueous coating composition contains only a small amount of nitrogen-containing molecules having an evaporation rate (calculated below) of 0.1 or less, more preferably 0.05 or less, which molecules are aromatic primary and secondary diamines, heterocyclic primary and secondary diamines, or aliphatic primary and secondary diamines, wherein the weight percent of nitrogen is 5% or more, more preferably 10% or more.

Preferably, the content of the above nitrogen-containing molecules in the aqueous coating composition is 13% or less, more preferably 10% or less, most preferably 5% or less, in particular 0.5% or less, by weight relative to the polymer solids.

The values for the evaporation rate have been reported by Texaco Chemical Company in bulletin Solvent Data; solvent Properties (1990). These values are defined relative to the evaporation rate as the evaporation rate of 1.00 of n-butyl acetate. The determination of the solvent evaporation rate not listed in the above bulletin is described in ASTM D3539. The co-solvent with a low evaporation rate acts as a plasticizer, adversely affecting the final coating, resulting in slow hardening.

Preferably, the co-solvent has an evaporation rate of between 0.05 and 0.005% with respect to the weight of polymer solids of < 16%.

The aqueous or solvent-based coating compositions of the present invention can be applied to a variety of substrates, including wood, board, stone, concrete, glass, fabric, leather, paper, plastic, foam, and the like, by any conventional method, including brushing, dipping, flow coating, spraying, and the like. However, they are particularly suitable for providing coatings on wood and board. The aqueous carrier medium is removed by natural drying or accelerated drying (by application of heat) to form a coating. Thus, in another embodiment of the present invention, there is provided a coating obtainable from the aqueous coating composition of the present invention.

The aqueous coating composition of the present invention may contain other conventional ingredients including pigments, dyes, emulsifiers, surfactants, plasticizers, thickeners, heat stabilizers, leveling agents, anti-cratering agents, fillers, sedimentation inhibitors, UV absorbers, antioxidants, dispersants, reactive diluents (such as those described above), waxes, neutralizing agents, adhesion promoters, defoamers, co-solvents, wetting agents, and the like, introduced at any stage of the manufacturing process or subsequently. Flame retardants such as antimony oxide may also be incorporated into the dispersion to enhance flame retardancy.

Preferably, when the aqueous composition is formulated as a paint, the composition comprises from 2% to 10%, more preferably from 3% to 9%, of solvent relative to the weight of the total paint composition. Preferably, at least 50 wt%, more preferably 80 wt%, most preferably 95 wt% of the total solvent is a solvent having an evaporation rate (as defined herein) of above 0.012, more preferably 0.018 to 0.5, most preferably below 0.21.

Preferably, the aqueous coating composition when applied to a substrate and dried for 24 hours forms a coating that is resistant to water (e.g., as measured in the test described herein) for 30 minutes, more preferably 1 hour, and most preferably 3 hours.

Preferably, the aqueous coating composition, when applied to a substrate and dried for 24 hours, forms a coating having a level 3 or greater block resistance at room temperature, more preferably a level 3 or greater block resistance at 52 ℃.

In one embodiment of the present invention, there is provided an aqueous autoxidisable coating composition having low show-through and comprising an autoxidisable vinyl polymer obtained by the process of the present invention, the composition comprising:

i) 33% to 65% of the autoxidisable vinyl polymer;

ii)0 to 20%, more preferably 0 to 15%, most preferably 0 to 10%, in particular 0 to 5% of a co-solvent; and

iii) 15% to 58% water;

wherein the percentages are by weight of the total composition and i) + ii) + iii) is 100%.

In another embodiment of the present invention, there is provided an aqueous autoxidisable coating composition having low show-through and comprising an autoxidisable vinyl polymer obtained by the process of the present invention, the composition comprising:

i) 20% to 45%, preferably 20% to 40% TiO₂；

ii) from 20% to 45%, preferably from 25% to 40%, of the autoxidisable vinyl polymer;

iii)0 to 10%, preferably 0 to 5%, of a co-solvent;

iv) 0.1% to 3% thickener solids;

v)0 to 10%, preferably 0 to 5%, of a dispersant; and

vi) 20% to 60% water;

wherein the percentages are relative to the weight of the total composition, and i) + ii) + iii) + iv) + v) ═ 100%.

In particular, the aqueous coating compositions of the invention and formulations containing the same advantageously comprise a desiccant salt. Desiccant salts are well known in the art for further improving the curability of unsaturated film-forming materials. Generally, the desiccant salt is a metal soap, i.e., a salt of a metal and a long chain carboxylic acid. It is said that the metal ions affect the curing action of the film coating and the fatty acid component makes it compatible in the coating medium. Examples of desiccant salts are cobalt, manganese, zirconium, lead, , lanthanum and calcium. The desiccant salt will generally provide a metal amount of, for example, 0.01 to 0.5% relative to the weight of the autoxidisable vinyl polymer at the level of the composition.

The desiccant salt is typically supplied as a solution in a solvent for use in solvent borne alkyd systems. However, they can also be used in aqueous coating compositions in a rather satisfactory manner, since they can generally be dispersed rather easily in the abovementioned systems. The drier salt may be incorporated into the aqueous coating composition at any convenient stage. For example, the desiccant salt may be added prior to dispersion in water. A desiccant promoter may be added to the desiccant salt described above. Suitable desiccant promoters include 2, 2' -bipyridine and 1, 10-phenanthroline.

The aqueous dispersions of the invention can, if desired, be used in combination with other polymer dispersions or solutions not according to the invention.

If the compositions of the present invention comprise an ethylene-based polymer other than the autoxidisable ethylene-based polymer described herein, then such other ethylene-based polymer is present in the composition in an amount of no greater than 35%, more preferably no greater than 20%, most preferably no greater than 10%, and particularly no greater than 4% by weight of the total ethylene-based polymer solids present.

Preferably, less than or equal to 10%, more preferably less than or equal to 5%, of the autoxidisable vinyl polymer solids comprise vinyl polymer covalently bonded to fatty acid wherein the covalent bond is generated by a grafting reaction of a growing vinyl radical on an unsaturated fatty acid. In the latter case, the fatty acid may be a free unsaturated fatty acid, or an unsaturated fatty acid constituting part of the polymeric structure. Most preferably, there is no grafting of the vinyl monomer to the fatty acid. Preferably, the coating composition of the present invention is a one-component system, which means that preferably no additional crosslinking agent (such as polyaziridine, polycarbodiimide, polyisocyanate or melamine) is added to the coating composition prior to applying the coating to the substrate.

Preferably, the coating composition is free of photoinitiator and is cured without the use of a radiation curing device.

Another aspect of the present invention provides a coating derived from and/or obtainable from the coating composition of the present invention and having a show-through value (as defined herein) of less than 10 gloss units.

Another aspect of the invention provides a substrate coated with a coating of the invention.

Another aspect of the invention provides a method of coating a substrate, the method comprising the steps of: i) applying the coating composition of the present invention to a substrate; ii) drying the substrate to form a coating thereon, wherein the coating has a show-through value (as defined herein) of less than 10 gloss units.

Another aspect of the present invention provides the use of the autoxidisable vinyl polymer and/or coating composition of the present invention to obtain a coating having a show-through value (as defined herein) of less than 10 gloss units.

Several other variations of the present invention will be apparent to those skilled in the art and such variations are intended to be included within the broad scope of the present invention. Other aspects of the invention and preferred features thereof are set out in the claims herein.

The invention will now be described by way of the following non-limiting examples. All parts, percentages and ratios are by weight unless otherwise indicated. The prefix C before the example indicates that the example is a comparative example. The term "working" means that the example is according to the invention. The term "non-working" means that the example is not according to the invention (i.e. comparative example).

Various registered trademarks, other names, and/or abbreviations are used herein to designate some of the ingredients used to prepare the polymers and compositions of the present invention. These are identified below by chemical and/or trade names and optionally their manufacturer or supplier. However, where the chemical name and/or supplier of the materials described herein is not mentioned, such materials can be readily found, for example, in references known to those skilled in the art: hawley's Condensed Chemical Dictionary (14 th edition), such as' McCutcheon's Emulsifiers and detergents', Rock Road, Glen Road, NJ.07452-1700, USA, 1997 and/or Lewis Richard J., Sr.; john Wiley & Sons.

'AIBN' refers to azobisisobutyronitrile; 'Additol VXW 4940' refers to the dry type pigment commercially available from Elementis under this trade name;

'Atlas G5000' refers to a nonionic polyalkylene glycol ether commercially available under this name from Uniquma;

'BA' refers to n-butyl acrylate; '3, 5-BHT' refers to 3, 5-di-tert-butyl-4-methylphenol (also known as butylhydroxytoluene);

'BMA' refers to n-butyl acrylate;

' CoF ' refers to catalyst (bis 4, 4 ' -dimethylbenzoyldioxime) diboron difluoride Co II as described in EP 1742973-A, US2007219328 and WO 2005105855;

'Dehydran 1293' refers to a solution of a specially modified polydimethylsiloxane defoamer, commercially available from Cognis under this trade name;

'Disperbyk 190' refers to a solution of a high molecular weight block copolymer with pigment affinity groups, which is a dispersing additive for pigments and is commercially available under this trade name BYK Chemie;

'Dow PnP' refers to a propylene glycol n-propyl ether mixture commercially available from Dow Chemicals under the trade name Dowanol PnP;

'dtAP' means di-tert-amyl peroxide;

'dtBP' means di-tert-butyl peroxide;

'FES 77' refers to a dispersant which is a sodium salt of a fatty alcohol glycol ether sulfuric acid and is commercially available from Cognis under the tradename Disponil FES 77;

'FES 993' refers to a dispersant which IS a sodium salt of a fatty alcohol glycol ether sulfuric acid and IS commercially available from Cognis under the trade name Disponil FES993 IS;

'GMA' refers to glycidyl methacrylate;

'HHPA' refers to hexahydrophthalic anhydride;

'Kronos 2190' refers to titanium dioxide pigment commercially available from Kronos under this trade name;

'MMA' refers to methyl methacrylate;

'MSA' nail sulfonic acid;

'NuCa 10' refers to a pigment commercially available from Rockwood Pigments under the tradename Nuodex calcium 10 (10 weight percent calcium carboxylate in a hydrocarbon solvent);

'NuCo 10' refers to a pigment commercially available from Rockwood Pigments under the trade designation Nuodex cobalt 10 (10% by weight cobalt carboxylate in a solvent of diarylated kerosene and methoxypropoxypropanol);

'NuZr 18' refers to a pigment commercially available from Rockwood Pigments under the tradename Nuodex zirconia 18 (18% by weight zirconium carboxylate in a solvent for diarylated kerosene);

'PAA' refers to conventional polyacrylic acid having a weight average molecular weight (Mw) of 200 to 250k daltons, prepared by the applicants;

'PVC' refers to polyvinyl chloride;

'Sefose' refers to a soy compound (soyate) made from partially hydrogenated soybean oil, commercially available under the trade name Sefose 1618SC from P & G Chemicals;

'Sun-FA' refers to sunflower fatty acid;

'tBP' refers to tert-butyl peroxide;

'tBPD' refers to tert-butyl peroxybenzoate;

'TEA' refers to triethylamine;

'THF' refers to tetrahydrofuran; and

'TRAP' refers to triphenylethylphosphonium bromide.

Test method

Standard conditions

Standard conditions (e.g., for drying a film) as used herein refer to a relative humidity of 50% ± 5%; the ambient temperature is 23 +/-2 ℃; the air flow rate is less than 0.1 m/s.

Particle size

As used herein, particle size is the size of the weight average particles, which is stated as the linear dimension (i.e., particle diameter) because the particles are considered to be substantially spherical. The weight average particle size can be determined using scanning/transmission electron microscopy and photon correlation spectroscopy (photon correlation spectroscopy).

Iodine number

The iodine number (also referred to herein as the iodine number) is a measure of the amount of ethylenically unsaturated double bonds in a sample, which increases with increasing unsaturation. The iodine number can be defined according to DIN 53241-1 as the mass m of iodine added to the ethylenically unsaturated double bond (decolorized) of the sample to be analyzed_IAnd mass m of the sample_B(the mass of solids in the sample in the case of a solution or dispersion). Iodine value may be in centigram iodine per gram of sample (cg I)₂In units of/g) or in grams of iodine per 100 grams of sample (g I)₂The unit is/100 g). Standard methods for analysis may be used, such as ASTM D5768-02(2006) and DIN 53241. One common method (which is used to measure the iodine values given herein) is the Wjjs method, in which the amount of iodine absorbed is determined by titrating the unreacted reagent with sodium thiosulfate, and then calculating the iodine value by:

print-through

Two types of PVC substrates were used to determine the degree of strike-through of an uncolored coating containing an autoxidisable resin:

the first type of PVC is a 2mm thick coarse PVC substrate with a regular, uniformly rough surface, commercially available under the trade name vikupper white PVC film (model JD11) from Vink kunststoffen b.v (Didam, Holland). This substrate was analyzed for a 1.9 × 2.5mm area using Wyko optical profilometer NT 1100 with a magnification of 2.5, to give Rz ═ 25 μm ± 5 μm. Rz refers to the "ten point height," which is the average of the five largest peak-to-valley distances in the scanned area, and is considered to be a general value of surface roughness. The second type of PVC is a 3mm thick smooth PVC substrate having a regular, smooth surface, commercially available under the trade designation Vikupor white PVC film gloss number 206221 from Vink Kunststoffen. Rz ═ 1 μm ± 0.25 μm (measured as crude PVC).

An unpigmented coating containing, optionally, a flow agent and wetting agent and, if desired, a thickener, was cast onto both of the above PVC substrates (rough and smooth) and yielded smooth, defect-free films with a theoretical dry film thickness of between 52 μm ± 6 μm. The film was dried under standard conditions for 24 hours and then measured for gloss at 20 degrees. The gloss measurements were repeated after 4 days, 7 days and 14 days. The difference in gloss readings between films on rough PVC and smooth PVC is a quantitative measure of how well the rough surface of the PVC is telegraphed through to the dry coating surface. The smaller this difference in gloss values, the smaller the print-through and the better the coating masks the substrate roughness.

Moreover, the absolute value of the gloss reading on the rough PVC should not decrease significantly over time, so that low print-through is maintained.

Drying time

To test the dust-free drying time and the tack-free drying time of the compositions prepared in the following examples, the compositions were formulated and applied to glass panels at a wet film thickness of 80 μm. Drying time tests were conducted at regular intervals under standard conditions.

Time of dust sticking

The dust-free time (DFT) is determined as follows: a piece of cotton wool (about 1 cm)³I.e. 0.1g) falls onto the dried film from a distance of 25 cm. If the piece of cotton wool can be used by peopleThey blow immediately from the substrate without leaving any lint or marks in or on the film, and the film is considered dust-free.

Time to surface dry

The tack-free time (TFT) is determined as follows: a piece of cotton wool (about 1 cm)³I.e., 0.1g) was placed on the dry film and a 1kg weight (10 seconds) was placed on the piece of batting. The film is considered to be tack-free if the piece of batt can be removed from the substrate by hand without leaving any batt or mark in or on the film.

Adhesion test

A 100 μm thick wet film was cast on a Leneta card and dried under standard conditions for 24 hours. The blocking resistance was measured using a blocking tester, in which the film coatings of a pair of coated test cards were placed face to face and at 250g/cm²At ambient temperature for 4 hours or at 52 ℃ for 2 hours. After cooling to ambient temperature (if necessary), the test cards were peeled apart and evaluated for blocking resistance, which ranged from 0 (very poor blocking resistance) to 5 (excellent blocking resistance). When the test card can be peeled off with a small force without damaging the film surface, blocking was evaluated as 3.

Measurement of film yellowing

The degree of yellowing of the coating was measured using Dr Lange Spectropen for a specific period of exposure to sunlight or darkness. The apparatus is calibrated to the defined values of the calibration plate and then the b values are determined according to the CIE L, a, b method. Dark yellowing is defined as the increase in the degree of yellowing (. DELTA.b) of the coating during storage at 52 ℃ in the dark for 21 days.

Determination of molecular weight

Gel Permeation Chromatography (GPC) analysis for determining the molecular weight of polymers was carried out on Alliance Waters 2695 GPC with three consecutive PL-gel columns (model Mixed-B, l/d 300/7.5mm), using 1cm³Tetrahydrofuran (THF, HPLC grade, using 3, 5-di-tert-butyl-4-hydroxytoluene [ BHT ]]Preferably stabilized with 1.0 vol.% acetic acid) as eluent, and an Alliance Waters 2410 refractive index detector was used. The GPC was calibrated using a set of polystyrene samples (analyzed according to DIN 55672). A sample corresponding to about 16mg of solid material was dissolved in 8cm³In THF. The sample was shaken periodically, allowed to dissolve for at least 24 hours to completely "untangle" and placed in an autosampler unit of Alliance Waters 2695. The injection volume was 150. mu.L and the temperature of the column oven was determined to be 35 ℃.

Glass transition temperature(T_G)

Tg was determined by DSC using a TA instruments DSC Q1000 with 50 μ l standard TA instruments aluminum cup. The flow rate was 50ml/min of nitrogen and the sample was placed at ambient temperature. The sample was cooled until it reached an equilibrium temperature of-90 ℃ and then heated to 100 ℃ at a rate of 10 ℃/min, held at 100 ℃ for 5 minutes, cooled to-90 ℃ at a rate of 20 ℃/min, held at-90 ℃ for 5 minutes, and then heated to 100 ℃ at a rate of 10 ℃/min.

The Tg values in the examples and tables herein are the intermediate points as determined by DSC as above.

Water resistance

A100 μm thick wet film was cast on a Leneta card and dried for 24 hours under standard conditions. Three drops of water were then placed on the film, and one drop was removed after 30 minutes, 1 hour and 3 hours. Water resistance was evaluated immediately after water removal and then after 24 hours. Water resistance rating 0-very poor, dissolved; acceptable 3 ═ acceptable; excellent 5 ═ without damage to the coating.

Gloss measurement method

Gloss measurements were performed according to ASTM D523-89 on a BYK Gardner micro-TRI-gloss 20-60-85 gloss meter.

Each example herein is prepared by the following general method with reference to each alphanumeric designation listed below, modified as indicated in the table.

General procedure

Step (A1) preparation of epoxy-functionalized vinyl Polymer (option 1)

In an alternative step (A1), a round-bottomed reaction Vessel (VOL) equipped with a stirrer, baffles and a cooler was charged with water (a), Na under a nitrogen atmosphere₂SO₄(b) And paa (c). The mixture was neutralized with NaOH until pH > 8 and the mixture temperature reached 60 ℃. A mixture of MMA (d), BMA (e), GMA (f), AIBN (g) and CoF (h) is transferred to a reactor and the reaction temperature is brought to 80 ℃. After time t1, a mixture of FES993(i) and water (j) was added to the reactor. After time t2, the temperature was raised to 85 ℃ and maintained at this temperature for 60 minutes. Then, the reaction vessel was cooled to ambient temperature, and polymer pellets were obtained, which were washed and dried for use in the next step (B).

The polymer obtainable in this step (a1) is characterized as follows:

M_n＝k；M_w＝I；PDi＝m；T_g＝n。

step (A2) preparation of epoxy-functionalized vinyl Polymer (option 2)

A round bottom reactor (VOL ') equipped with a stirrer and a cooler and optionally with high pressure (in the case indicated herein) is charged with solvent (SOL1, a ') under nitrogen atmosphere and heated to T ' 1. A homogeneous mixture of styrene (b '), GMA (c '), BA (dd '), BMA (d '), d-BP (e ') and t-BPB (f) is fed to the reactor by means of a pump under pressure (g ') over a period of time t ' 1.

Optionally, after the ingredients are added to the reactor, the pump is flushed with more solvent (SOL1, h ') and the reactor is heated to T' 2 for a time T '2, cooled to T' 3, and then dtAP (i ') is added in portions at time T' 3.

The mixture was kept at 140 ℃ for a time t' 4 and then the reactor was cooled to ambient temperature. Optionally, further solvent (SOL1, j') was added.

The polymer obtainable in step (a2) is characterized as follows:

solid content k'; m_n＝I’；M_w＝m’；PDi＝n’。

Step (B) preparation of an aqueous autoxidisable vinyl Polymer

An amount (p) of the vinyl polymer prepared according to the above general method step (a1 or a2) was dissolved in a solvent (SOL2, q). SunFA (r) and TRAP(s) were added to the resulting solution to form a mixture, which was heated at 120 ℃ under nitrogen. The reaction was continued until AN acid value (AN) was reached (t).

In AN optional further step, further SunFA (ta) and MSA (tb) are added, the mixture is heated again to 120 ℃ under nitrogen atmosphere and esterification is continued until the Acid Number (AN) (tc) is reached.

SOL2 was removed by distillation under reduced pressure and the resulting polymer was characterized as follows:

M_n＝u；M_w＝v；PDi＝w；T_g＝x。

step (C1) Dispersion of the vinyl Polymer obtainable in step (B) (option 1)

To a quantity (y) of polymer prepared according to the general procedure described above in step (B) is added Atlas G5000(z), ales (aa) and Ingredient 1(IGD1, ab). Water (ac) was then slowly added to form a dispersion which was stirred for a time t5 before storage under a nitrogen atmosphere. The dispersion was characterized as follows:

solid content ad; pH 2; ND × AV ═ ae

Step (C2) DispersionVinyl Polymer obtainable by step (B) (option 2)

To an amount (y ') of polymer (z ' solid, dissolved in solvent SOL 3) prepared according to the general procedure described above for step (B) was added HHPA (aa '). The mixture was held at temperature T6 until substantially all of the anhydride had reacted as determined by the infrared spectroscopy of the reaction mixture. The anhydride group is usually at 1785cm^-1And 1865cm^-1Shows two absorption peaks which disappear once the reaction is complete and are at 1740cm^-1A new ester carbonyl absorption peak appears. Then, SOL3 was removed by distillation under the reduced pressure, thereby obtaining a fatty acid-functionalized acrylic acid (FA acrylic acid) having AN acid value of (AN) (ab'). To FA acrylic (ac ') was added Ingredient2(IGD2, ad ') and TEA (ae '), followed by water (af) to give an aqueous composition characterized as follows:

solid content ag'; pH 3; t9 ═ ah'; m_n＝ai′；M_w＝ aj′；PDi＝ak′&(ND×AV)＝al′

Step (C3) Dispersion of the vinyl Polymer obtainable in step (B) (option 3)

To a quantity (y ") of polymer (z" solid, dissolved in solvent SOL 3') prepared as described in general method step (B) above was added NuCa10(aa "), NuCo10 (ab") and NuZr18(ac ") to give the product.

All examples were prepared according to the general methods described with reference to the data in the tables (described below). In the table, NM indicates that the parameter was not determined; NA indicates that this parameter is not available for this example. Some embodiments may be prepared by more than one step at each stage (A, B or C as indicated in the tables), so [ a1 and a2] and [ C1, C2 and/or C3] are not always alternatives, but may also be combined.

Data in general methods tables

A11 (Process), 2 (characterization)

A23 (characterisation), 4a & 4b (art)

B5 (Art & characterization)

C16 (Art & characterization)

C27 (Process), 8 (characterization)

C39 (Art & characterization)

Only substantially all of the product from step C was not neutralized (except Ex 8C), so ND was 0, and thus ND × AV was 0. The values of ND × AV of Ex8c are shown in Table 8.

Claims (42)

1. A coating composition comprising an autoxidisable vinyl polymer, said composition being selected from the group consisting of an aqueous coating composition and a solvent based coating composition, wherein:

I) the autoxidisable vinyl polymer having:

i) a vinyl polymer backbone in an amount of 25% to 59% relative to the weight of the autoxidisable vinyl polymer;

ii) fatty acid residues in an amount of 41% to 75% relative to the weight of the autoxidisable vinyl polymer;

iii) -T from 60 ℃ to +20 ℃_g；

iv) a weight average molecular weight (M) of 3,500 to 50,000g/mol_w) (ii) a And

v) PDi from 2 to 10;

II) the autoxidisable vinyl polymer is obtained by a process comprising the steps of:

(A) polymerizing an ethylenically unsaturated vinyl monomer comprising:

i) at least one epoxy-functional vinyl monomer in an amount of 15% to 100% relative to the weight of the total monomers in step (a); and

ii) at least one other ethylenically unsaturated vinyl monomer in an amount of from 0% to 85% relative to the weight of the total monomers in step (A);

(B) reacting the epoxy-functional vinyl polymer obtained in step (A) with an average iodine value of 30 to 250g I₂Reaction is carried out on 100g of fatty acid;

III) the composition:

a) optionally having a content of co-solvent of less than or equal to 40% relative to the total weight of the composition; and is

b1) When an aqueous composition, has a solids content greater than or equal to 30% relative to the total weight of the aqueous composition;

b2) when solvent-based, has a solids content greater than or equal to 60% relative to the total weight of the solvent-based composition; and

IV) the composition when a film has a show-through value of less than 10 gloss units,

wherein the strike-through value is the difference of an initial smooth gloss value minus an initial matte gloss value of the film, the initial smooth gloss value being the gloss of the film cast on smooth PVCRz 1 μm ± 0.25 μm, the initial matte gloss value being the gloss of the film cast on matte PVCRz 25 μm ± 5 μm; and is

Each film has a dry film thickness of 52 μm ± 6 μm;

each initial gloss value was measured at a 20 ° angle one day (24 hours) after the film was cast.

2. The coating composition of claim 1, which is a non-adherent composition.

3. The coating composition of any one of the preceding claims, wherein the epoxy-functionalized ethylene-based polymer prepared in step (II) (a) has an M of 1,500 to 10,000g/mol_n。

4. The coating composition of any of the preceding claims 1 or 2, wherein the epoxy-functionalized vinyl polymer prepared in step (II) (a) comprises 0 to 1% of acid-functionalized vinyl monomer, relative to the weight of the epoxy-functionalized vinyl polymer.

5. A coating composition according to claim 3, wherein the epoxy-functionalized vinyl polymer prepared in step (II) (a) comprises 0 to 1% of acid-functionalized vinyl monomer, relative to the weight of the epoxy-functionalized vinyl polymer.

6. The coating composition of any of the preceding claims 1, 2 or 5, wherein the epoxy-functionalized vinyl polymer prepared in step (II) (a) comprises less than 5% of a hydroxyl-functional monomer, relative to the weight of the epoxy-functionalized vinyl polymer.

7. A coating composition according to claim 3, wherein the epoxy-functionalized vinyl polymer prepared in step (II) (a) comprises less than 5% of a hydroxyl-functional monomer, relative to the weight of the epoxy-functionalized vinyl polymer.

8. The coating composition of claim 4, wherein the epoxy-functionalized vinyl polymer prepared in step (II) (A) comprises less than 5% of a hydroxyl-functional monomer, relative to the weight of the epoxy-functionalized vinyl polymer.

9. The coating composition of any of the preceding claims 1, 2, 5, 7-8, wherein the epoxy-functionalized vinyl polymer prepared in step (II) (a) comprises less than 40% of styrenic monomers relative to the weight of the epoxy-functionalized vinyl polymer.

10. A coating composition according to claim 3, wherein the epoxy-functionalized vinyl polymer prepared in step (II) (a) comprises less than 40% of styrenic monomers relative to the weight of the epoxy-functionalized vinyl polymer.

11. The coating composition of claim 4, wherein the epoxy-functionalized vinyl polymer prepared in step (II) (A) comprises less than 40% of styrenic monomers relative to the weight of the epoxy-functionalized vinyl polymer.

12. The coating composition of claim 6, wherein the epoxy-functionalized vinyl polymer prepared in step (II) (A) comprises less than 40% of styrenic monomers relative to the weight of the epoxy-functionalized vinyl polymer.

13. A coating composition according to any one of the preceding claims 1, 2, 5, 7-8, 10-12, wherein the fatty acid residues are substantially free of fatty acid glycidyl esters.

14. A coating composition according to claim 3, wherein the fatty acid residues are substantially free of fatty acid glycidyl esters.

15. A coating composition according to claim 4, wherein the fatty acid residues are substantially free of fatty acid glycidyl esters.

16. A coating composition according to claim 6, wherein the fatty acid residues are substantially free of fatty acid glycidyl esters.

17. A coating composition according to claim 9, wherein the fatty acid residues are substantially free of fatty acid glycidyl esters.

18. The coating composition of any one of the preceding claims 1, 2, 5, 7-8, 10-12, 14-17, which is aqueous.

19. The coating composition of claim 3, which is aqueous.

20. The coating composition of claim 4, which is aqueous.

21. The coating composition of claim 6, which is aqueous.

22. The coating composition of claim 9, which is aqueous.

23. The coating composition of claim 13, which is aqueous.

24. The coating composition of claim 18, comprising no more than 13% N-methylpyrrolidone, relative to the weight of the total composition.

25. A coating composition according to any one of claims 19 to 23, comprising no more than 13% N-methylpyrrolidone, relative to the weight of the total composition.

26. The coating composition of claim 18 comprising no more than 13% of nitrogen-containing molecules having an evaporation rate of 0.1 or less, the molecules being aromatic primary and secondary diamines, heterocyclic primary and secondary diamines, or aliphatic primary and secondary diamines, wherein the weight% of nitrogen is > 5% relative to the weight of the molecules.

27. The coating composition of any one of claims 19 to 24, comprising no more than 13% of nitrogen-containing molecules having an evaporation rate of 0.1 or less, the molecules being aromatic primary and secondary diamines, heterocyclic primary and secondary diamines, or aliphatic primary and secondary diamines, wherein the weight% of nitrogen is > 5% relative to the weight of the molecules.

28. The coating composition of claim 25 comprising no more than 13% of nitrogen-containing molecules having an evaporation rate of 0.1 or less, the molecules being aromatic primary and secondary diamines, heterocyclic primary and secondary diamines, or aliphatic primary and secondary diamines, wherein the weight% of nitrogen is > 5% relative to the weight of the molecules.

29. The coating composition of any one of claims 1, 2, 5, 7-8, 10-12, 14-17, which is solvent-based.

30. The coating composition of claim 3, which is solvent-based.

31. The coating composition of claim 4, which is solvent-based.

32. The coating composition of claim 6, which is solvent-based.

33. The coating composition of claim 9, which is solvent-based.

34. The coating composition of claim 13, which is solvent-based.

35. A process for obtaining a polymer comprising at least one autoxidisable vinyl polymer wherein:

the autoxidisable vinyl polymer is capable of forming a coating composition that when in film form has a print-through value of less than 10 gloss units, wherein the print-through value is as defined in claim 1;

the method comprises the following steps:

(I) polymerizing an ethylenically unsaturated vinyl monomer comprising:

i) at least one epoxy-functional vinyl monomer in an amount of 15% to 100% relative to the weight of the total monomers in step (I); and

ii) at least one other ethylenically unsaturated vinyl monomer in an amount of from 0% to 85% relative to the weight of the total monomers in step (I);

(II) reacting the epoxy-functionalized vinyl polymer obtained in step (I) with an average iodine value of 30 to 250g I₂Reaction is carried out on 100g of fatty acid;

wherein the obtained autoxidisable vinyl polymer has:

i) a vinyl polymer backbone in an amount of 25% to 59% relative to the weight of the autoxidisable vinyl polymer;

ii) fatty acid residues in an amount of 41% to 75% relative to the weight of the autoxidisable vinyl polymer;

iii) -T from 60 ℃ to +20 ℃_g；

iv) a weight-average molecular weight M of from 3,500 to 50,000g/mol_w(ii) a And

v) PDi from 2 to 10.

36. A polymer obtained by the process of claim 35.

37. A coating composition comprising the polymer of claim 36.

38. A coating obtained from the coating composition of any one of claims 1 to 34 and 37 and having a show-through value of less than 10 gloss units, the show-through value being as defined in claim 1.

39. A substrate coated with the coating of claim 38.

40. A method of coating a substrate, the method comprising the steps of:

i) applying the coating composition of any one of claims 1 to 34 and 37 to a substrate;

ii) drying the substrate to form a coating thereon,

wherein the coating has a show-through value of less than 10 gloss units, the show-through value being as defined in claim 1.

41. Use of the autoxidisable vinyl polymer according to claim 36 or the coating composition according to any one of claims 1 to 34 and 37 for obtaining a coating having a show-through value of less than 10 gloss units, wherein the show-through value is as defined in claim 1.

42. A process for preparing the autoxidisable vinyl polymer of claim 36 or the coating composition of any one of claims 1 to 34 and 37 to obtain a coating having a show-through value of less than 10 gloss units, wherein the show-through value is as defined in claim 1.