EP1769031A2

EP1769031A2 - Aqueous vinyl graft copolymer compositions

Info

Publication number: EP1769031A2
Application number: EP05768448A
Authority: EP
Inventors: Saskia Van Der Slot; Tijs Nabuurs
Original assignee: DSM IP Assets BV
Current assignee: DSM IP Assets BV
Priority date: 2004-07-16
Filing date: 2005-07-08
Publication date: 2007-04-04
Also published as: GB0415934D0; WO2006007999A3; WO2006007999A2

Abstract

An aqueous composition comprising a vinyl graft copolymer and 0 to 50 wt% of organic co-solvent by weight of the graft copolymer where the vinyl graft copolymer comprises 20 to 95 wt% of a polymeric backbone and 80 to 5 wt% of a macromonomer(s) where the macromonomer(s) is obtained using at least two different vinyl monomer feeds which comprise in the range of from 0 to 50 wt% of vinyl monomers carrying anionic or potentially anionic water dispersing groups.

Description

AQUEOUS VINYL GRAFT COPOLYMER COMPOSITIONS

The present invention relates to certain aqueous vinyl graft copolymer compositions, to a process for the production of such aqueous vinyl graft copolymer compositions and to their use.

The use of aqueous vinyl polymer compositions is well known in the art for numerous applications, and in particular for the provision of a binder material in coating applications. It is also known to be advantageous in some applications to employ an aqueous vinyl graft copolymer composition.

EP 261 ,942 discloses compositions comprising at least 15 mol % of a macromonomer and processes for preparing the macromonomers using catalytic chain transfer agents. All the disclosed examples are to homo-macromonomers prepared using a single feed.

WO 93/22351 and WO 93/22355 disclose the use of a macromonomer prepared using a single vinyl monomer feed having terminal ethylenic unsaturation acting as a chain transfer agent for controlling the molecular weight of polymers prepared in the presence of the macromonomer.

US 6,248,826 discloses an aqueous dispersed copolymer formed by emulsion polymerisation of terminally unsaturated carboxylic acid oligomers with ethylenically unsaturated vinyl monomers so as to have low viscosities over a broad pH range.

WO 95/32228 and WO 95/32229 describe aqueous coating and lacquer compositions comprising a graft copolymer having carboxylic-acid functional macromonomers attached at a terminal end thereof to a polymeric backbone.

US 5,231 ,131 describes a pigment dispersion containing a graft copolymer dispersant having a hydrophobic backbone and hydrophilic macromonomer side chains. Both the macromonomer and backbone are prepared in solvent.

We have now discovered how to prepare aqueous vinyl graft copolymer compositions where the mechanical and physical properties such as for example adhesion, crosslinkability, minimum film forming temperatures, hardness, blocking and chemical resistances are easily tailorable.

According to the present invention there is provided an aqueous composition comprising a vinyl graft copolymer and containing < 50 wt% of organic co-solvent by weight of the graft copolymer, said vinyl graft copolymer comprising: i) 20 to 95 wt% of a polymeric backbone; and ii) 80 to 5 wt% of a macromonomer(s) of Formula (1 ) grafted to the polymeric backbone:

CH₂=C(R¹HX]_n (1 )

where R¹ = optionally substituted aryl, -C(O)OR² or -C(O)NR² R³; R² = -H, -CH₃ or optionally substituted C₁ to C₁₈ alkyl, cycloalkyl, aryl

(alkyl)aryl;

R³ = -H, -CH₃ or optionally substituted C₁ to C₁₈ alkyl, cycloalkyl, aryl

(alkyl)aryl;

X = residue of vinyl monomer; n = an integer in the range of from 2 to 50,000; where the macromonomer(s) is obtained using at least two different vinyl monomer feeds; where the at least two different vinyl monomer feeds comprise in the range of from 0 to 50 wt%, preferably 0 to 42 wt% and especially 0 to 20 wt% of vinyl monomers carrying anionic or potentially anionic water-dispersing groups; and where i) and ii) add up to 100%.

In a second embodiment of the invention there is provided an aqueous composition comprising a vinyl graft copolymer and containing < 50 wt% of organic co-solvent by weight of the graft copolymer, said vinyl graft copolymer comprising: i) 20 to 95 wt% of a polymeric backbone; and ii) 80 to 5 wt% of at least two different macromonomers comprising: a) a first macromonomer of Formula (1 ); b) a second macromonomer of Formula (1); c) optionally further macromonomers of Formula (1);

CH₂=C(R¹HX]_n (1)

where R¹ = optionally substituted aryl, -C(O)OR² or -C(O)NR² R³;

R² = -H, -CH₃ or optionally substituted C₁ to C₁₈ alkyl, cycloalkyl, aryl, (alkyl)aryl;

R³ = -H, -CH₃ or optionally substituted C₁ to C₁₈ alkyl, cycloalkyl, aryl, (alkyl)aryl;

X = residue of vinyl monomer; n = an integer in the range of from 2 to 50,000; grafted to the polymeric backbone; wherein the macromonomers are obtained using at least two different vinyl monomer feeds; where the at least two different vinyl monomer feeds comprise in the range of from 0 to 50 wt%, preferably 0 to 42 wt% and especially 0 to 20 wt% of vinyl monomers carrying anionic or potentially anionic water-dispersing groups; and where i) and ii) add up to 100%.

In a third embodiment of the invention there is provided an aqueous composition comprising a vinyl graft copolymer and containing < 50 wt% of organic co-solvent by weight of the graft copolymer, said vinyl graft copolymer comprising: i) 20 to 95 wt% of a polymeric backbone; and ii) 80 to 5 wt% of at least two different macromonomers comprising: a) 0 to 99 wt% of a first macromonomer of Formula (1 ); b) 1 to 99 wt% of a second macromonomer of Formula (1 ); c) 0 to 80 wt% of further macromonomers of Formula (1 );

CH₂=C(R¹HX]_n (1)

where R¹ = optionally substituted aryl, -C(O)OR² or -C(O)NR² R³;

R² = -H₁ -CH₃ or optionally substituted Ci to C₁₈ alkyl, cycloalkyl, aryl, (alkyl)aryl;

R³ = -H, -CH₃ or optionally substituted Ci to C₁₈ alkyl, cycloalkyl, aryl, (alkyl)aryl;

X = residue of vinyl monomer; n = an integer in the range of from 2 to 50,000; a), b), and c) add up to 100 %; grafted to the polymeric backbone; where a) and c) are obtained using at least one vinyl monomer feed; where b) is obtained using at least two different vinyl monomer feeds; where the vinyl monomer feeds comprise in the range of from 0 to 50 wt%, preferably 0 to 42 wt% and especially 0 to 20 wt% of vinyl monomers carrying anionic or potentially anionic water-dispersing groups; and where i) and ii) add up to 100%.

In a fourth embodiment of the invention there is provided a macromonomer of Formula (1 ):

CH₂=C(R¹HX]_n (1)

where R¹ = optionally substituted aryl, -C(O)OR² or -C(O)NR² R³;

X = residue of vinyl monomer; n = an integer in the range of from 2 to 50,000; where the macromonomer is obtained using at least two different vinyl monomer feeds; where the at least two different vinyl monomer feeds comprise in the range of from 0 to 50 wt%, preferably 0 to 42 wt% and especially 0 to 20 wt% of vinyl monomers carrying anionic or potentially anionic water-dispersing groups.

For clarity, the terms: a vinyl graft copolymer, a vinyl monomer, a polymeric backbone and a macromonomer are intended to cover the singular as well as the plural. The aqueous composition of the invention may be a solution, dispersion, emulsion or suspension of the vinyl graft copolymer in an aqueous carrier medium.

The macromonomer(s) is obtained using at least two different vinyl monomer feeds by which is meant that the macromonomer(s) is preferably prepared using a sequential polymerisation process or a gradient polymerisation process to give a gradient polymeric morphology. The macromonomer(s) may also be obtained by a blend of at least two macromonomers where each macromonomer is obtained from a different vinyl monomer feed. Preferably if the macromonomer(s) is obtained by such a blend of at least two macromonomers then the macromonomers are each obtained by a solution polymerisation process, blended and then dispersed in an aqueous medium. This ensures an intimate blend of the macromonomers to be grafted to the polymeric backbone. Preferably at least one of the macromonomers is obtained using at least two different vinyl monomer feeds.

Sequential polymerisations are well known in the art and are described in, for example, EP 492301 and are defined as polymerisations carried out using at least two feeds where the second vinyl monomer feed is added when most or all of the first vinyl monomer feed has been reacted.

The macromonomer prepared using a gradient process may be prepared by any of the process variations (also often described as a power feed process) as disclosed in US 3,804,881, US 4,195,167 and WO 97/12921 (incorporated herein by reference).

A typical gradient process for preparing a macromonomer comprises introducing a first vinyl monomer feed to a reactor, where the first vinyl monomer feed continually varies in its composition due to the addition of a different second vinyl monomer feed to the first vinyl monomer feed and polymerising the vinyl monomers introduced into the reactor.

The addition of the second vinyl monomer feed to the first vinyl monomer feed may be in parallel to the introduction of the first vinyl monomer feed to the reactor (i.e. both feeds start and end at the same time). Alternatively the start of the first vinyl monomer feed to the reactor may precede the start of the addition of the second vinyl monomer feed to the first vinyl monomer feed for example when preparing a macromonomer using a seeded polymerisation process, or both vinyl monomer feeds may be started simultaneously but the time taken for the addition of the second vinyl monomer feed to the first vinyl monomer feed may exceed the time taken for the introduction of the first vinyl monomer feed to the reactor. The seed may comprise up to 20 wt%, more preferably up to 15 wt% and especially up to 10 wt% of the first vinyl monomer feed.

A gradient process may also comprise simultaneously introducing a first vinyl monomer feed and a different second vinyl monomer feed into a reactor where the rate of introduction of the first vinyl monomer feed varies with respect to the rate of introduction of the second vinyl monomer feed and polymerising the vinyl monomers introduced into the reactor.

The at least two vinyl monomer feeds used to prepare the macromonomer usually differ in composition. The difference between the macromonomers resulting from the at least two vinyl monomer feeds may be any, including for example a difference in glass transition temperature (Tg), vinyl monomer functionality (for example the use of crosslinking, acid functional or adhesion promoting vinyl monomers), hydrophilicity, refractive index, molecular weight (by varying, for example, the amount or type of catalytic chain transfer agent used) or simply a variation in the concentration of the respective vinyl monomers in each vinyl monomer feed and any combinations thereof.

Preferably there is a calculated Tg difference of at least 10⁰C, more preferably at least 15⁰C and especially at least 2O⁰C between two of the at least two vinyl monomer feeds.

Alternatively and/or additionally there is preferably a different concentration in functional groups between two of the at least two vinyl monomer feeds. Preferably the functional groups are selected from crosslinking groups, water-dispersing groups, fluorinated groups and adhesion promoting groups as described herein.

Preferably the first vinyl monomer feed is the vinyl monomer feed with the most hydrophilic composition, followed by a second vinyl monomer feed with a more hydrophobic composition.

Preferably the weight ratio of the first vinyl monomer feed to the second different vinyl monomer feed is in the range of from 10:90 to 90:10, more preferably 70:30 to 30:70.

Preferably the weight average molecular weight of the macromonomer is less than 500,000, more preferably less than 200,000, most preferably less than 100,000, and especially between 50,000 and 10,000 g/mol.

The weight % ratio of polymeric backbone to macromonomer is preferably between 25:75 to 90:10, more preferably between 30:70 to 85:15, most preferably between 35:65 to 80:20 and especially between 40:60 to 70:30.

The macromonomer and the polymeric backbone are derived from free-radically polymerisable olefinically unsaturated monomers, which are also usually referred to as vinyl monomers, and can contain polymerised units of a wide range of such vinyl monomers, especially those commonly used to make binders for the coatings industry.

Examples of vinyl monomers which may be used to form the polymeric backbone and/or the macromonomer include but are not limited to olefinically unsaturated vinyl monomers such as 1 ,3-butadiene, isoprene, divinyl benzene, aromatic vinyl monomers such as styrene, α-methyl styrene; vinyl monomers such as acrylonitrile, methacrylonitrile; vinyl halides such as vinyl chloride; vinylidene halides such as vinylidene chloride; vinyl esters such as vinyl acetate, vinyl propionate, vinyl laurate; vinyl esters of versatic acid such as VeoVa 9 and VeoVa 10 (VeoVa is a trademark of Resolution); heterocyclic vinyl compounds; alkyl esters of mono-olefinically unsaturated dicarboxylic acids such as di-n- butyl maleate and di-n-butyl fumarate and, in particular, esters of acrylic acid and methacrylic acid of formula CH₂=CR⁵-COOR⁴ wherein R⁵ is H or methyl and R⁴ is optionally substituted C₁ to C₂₀, more preferably C₁ to C₈, alkyl, cycloalkyl, aryl or (alkyl)aryl which are also known as acrylic monomers, examples of which are methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate (all isomers), 2-ethylhexyl (meth)acrylate, isopropyl (meth)acrylate, propyl (meth)acrylate (all isomers), and hydroxyalkyl (meth)acrylates such as hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and their modified analogues like Tone M- 100 (Tone is a trademark of Union Carbide Corporation).

Particularly preferred is a polymeric backbone and/or a macromonomer made from a vinyl monomer system comprising at least 40 wt%, more preferably at least 50 wt% and especially at least 60 wt% of one or more vinyl monomers of the formula CH₂=CR⁵COOR⁴ as defined above. Such a preferred polymeric backbone and/or macromonomer is defined herein as an acrylic polymeric backbone and an acrylic macromonomer respectively. Particularly preferred acrylic monomers include butyl (meth)acrylate (all isomers), methyl (meth)acrylate, octyl (meth)acrylate (all isomers) and ethyl (meth)acrylate. Other preferred vinyl monomers include (meth)acrylic amides, (meth)acrylonitrile and vinyl acetate. The other vinyl monomers in such acrylic polymeric backbones and/or macromonomers may include one or more of the other vinyl monomers mentioned above, and/or may include ones different to such other vinyl monomers.

The vinyl monomers may also include vinyl monomers carrying functional groups as exemplified below. Such functional vinyl monomers may be introduced directly in the vinyl graft copolymer by free radical polymerisation, or alternatively the functional group may be introduced by a reaction of a reactive precursor into the macromonomer or polymeric backbone using a reactive compound carrying a functional group.

Water-dispersing functional groups provide the facility of self-dispersibility, stability, solubility in water and/or a substrate. The water dispersing groups may be ionic, potentially ionic, non-ionic or a mixture of such water-dispersing groups. Ionic water- dispersing groups need to be in their dissociated (i.e. salt) form to effect their water- dispersing action. If they are not dissociated they are considered as potential ionic groups which become ionic upon dissociation. The ionic water-dispersing groups are preferably fully or partially in the form of a salt in the final composition of the invention. Ionic water- dispersing groups include cationic water-dispersing groups such as basic amine groups, quaternary ammonium groups and anionic water-dispersing groups such as acid groups, for example phosphoric acid groups, sulphonic acid groups, and carboxylic acid groups. Conversion to the salt form is described below.

Preferred vinyl monomers providing anionic or potentially anionic water-dispersing groups include (meth)acrylic acid, itaconic acid, maleic acid, β-carboxyethyl acrylate, monoalkyl maleates (for example monomethyl maleate and monoethyl maleate), citraconic acid, styrenesulphonic acid, vinylbenzylsulphonic acid, vinylsulphonic acid, acryloyloxyalkyl sulphonic acids (for example acryloyloxymethyl sulphonic acid), 2-acrylamido-2-alkylalkane sulphonic acids (for example 2-acrylamido-2- methylethanesulphonic acid), 2-methacrylamido-2-alkylalkane sulphonic acids (for example 2-methacrylamido-2-methylethanesulphonic acid), mono(acryloyloxyalkyl)phosphates (for example, mono(acryloyloxyethyl)phosphate and mono(3-acryloyloxypropyl)phosphates) and mono(methacryloyloxyalkyl)phosphates.

The polymeric backbone and/or macromonomer may comprise functional vinyl monomers that may become cationic upon addition of acid, such as dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, and dimethylaminopropyl (meth)acrylamide. Such potentially ionic functional vinyl monomers may contribute to improved adhesion and may also improve stability or appearance on specific substrates such as wood.

Preferably the acid value of the macromonomer is in the range of from 0 to 300, more preferably 0 to 100 and especially 0 to 40 mgKOH/g.

Preferably the acid value of the polymeric backbone is in the range of from 0 to 80 mgKOH/g and especially in the range of from 10 to 50 mgKOH/g.

Preferably the acid value of the vinyl graft copolymer is < 160 mgKOH/g, more preferably in the range of from 0 to 75 mgKOH/g, especially in the range of from 0 to 40 mgKOH/g and most especially in the range of from 2 to 40 mgKOH/g.

Non-ionic water-dispersing groups may be in-chain, pendant or terminal groups. Preferably non-ionic water-dispersing groups are pendant polyoxyalkylene groups, more preferably polyoxyethylene groups such as methoxy(polyethyleneoxide (meth)acrylate) or hydroxyalkyl (meth)acrylates such as hydroxyethyl (meth)acrylate (HE(M)A).

Preferred vinyl monomers providing non-ionic water-dispersing groups include alkoxy polyethylene glycol (meth)acrylates, hydroxy polyethylene glycol (meth)acrylates, alkoxy prolyproplene glycol (meth)acrylates and hydroxy polypropylene glycol (meth)acrylates, preferably having a number average molecular weight of from 350 to 3000. Examples of such vinyl monomers which are commercially available include ω- methoxypolyethylene glycol (meth)acrylate. Other vinyl monomers providing non-ionic water-dispersing groups include (meth)acrylamidemono(methacryloyloxethyl)phosphate).

Such non-ionic functional vinyl monomers may contribute to improved stability and improved pigment and substrate wetting.

Preferably the vinyl graft copolymer comprises 0 to 20 wt%, more preferably 0 to 15 wt%, most preferably 0 to 10 wt% and especially 0 to 5 wt% of vinyl monomers carrying non-ionic water-dispersing groups.

Preferably the macromonomer comprises 0 to 15 wt%, more preferably 0 to 10 wt% and most preferably 0 to 5 wt% of vinyl monomers carrying non-ionic water- dispersing groups.

Preferably the polymeric backbone comprises 0 to 20 wt%, more preferably 0 to 15 wt%, most preferably 0 to 10 wt% and especially 0 to 5 wt% of vinyl monomers carrying non-ionic water-dispersing groups.

Vinyl monomers carrying crosslinker groups include for example allyl, glycidyl or hydroxyalkyl (meth)acrylates, keto functional vinyl monomers such as acetoacetoxy esters of hydroxyalkyl (meth)acrylates, keto-containing amides such as diacetone acrylamide (DAAM), (meth)acrylamide, methylol (meth)acrylamides and silane functional (meth)acrylic monomers such as methacryloxy propyltrimethoxy silane.

Preferred vinyl monomers carrying crosslinker groups are diacetone acrylamide, acetoacetoxy ethyl methacrylate (AAEM), glycidyl methacrylate and silane functional (meth)acrylic vinyl monomers. Examples include Silquest A-2171 , Silquest A-174, CoatOSil 1757, Silquest A-151 and Silquest A-171 available from OSI Specialty Chemicals (Silquest and CoatOSil are trade marks). Also possible are combinations of AAEM and Silquest A-1100 or A-1101 or combinations of acid functional vinyl monomers and Silquest A-186 or A-187.

The polymeric backbone and/or macromonomer may optionally contain other functional groups to contribute to the optional crosslinking of the vinyl graft copolymer. Examples of such other groups include unsaturated groups such as those provided by maleic, fumaric, acryloyl, methacryloyl, styrenic, allylic and mercapto groups, these allow crosslinking through Michael Addition by using polyamines or UV crosslinkability to be introduced into the vinyl graft copolymer.

The polymeric backbone may comprise up to 5 wt% of olefinically polyunsaturated vinyl monomers.

Preferably the vinyl graft copolymer comprises 0 to 30 wt%, more preferably 0 to 25 wt%, most preferably 0 to 20 wt% and especially 2 to 10 wt% of vinyl monomers carrying crosslinker groups.

Preferably the macromonomer comprises 0 to 50 wt%, more preferably 0 to 40 wt%, most preferably 0 to 30 wt% and especially 2 to 15 wt% of vinyl monomers carrying crosslinker groups.

Preferably the polymeric backbone comprises 0 to 30 wt%, more preferably 0 to 20 wt%, most preferably 0 to 15 wt% and especially 0 to 10 wt% of vinyl monomers carrying crosslinker groups.

The vinyl monomer composition for preparing the macromonomer and/or polymeric backbone may comprise functional vinyl monomers that are capable of forming hydrogen bridging links, such as (meth)acrylamide, methylol (meth)acrylamide, butoxymethyl (meth)acrylamide and ureido vinyl monomers (such as Sipomer WAM available from Rhodia).

The polymeric backbone and/or macromonomer may also comprise functional vinyl monomers that induce a dipole moment, such as cyano functional vinyl monomers, such as (meth)acrylonitrile. Such functional vinyl monomers contribute to improved mechanical properties, including toughness and elongation at break, a better hardness- MFFT balance and improved blocking properties.

The polymeric backbone and/or macromonomer may comprise functional vinyl monomers that include fluorinated groups, more preferably fluorinated groups having alcohol units of the formula: -O(CH₂)_m-(CF₂)_pF, where 0 < m < 4, and 1 < p < 4. Such functional vinyl monomers may contribute to improved chemical resistances, better cleanability and improved scratch resistance.

The polymeric backbone and/or macromonomer may also comprise functional vinyl monomers that act as adhesion promoters, such as Sipomer WAM (ex. Rhodia), Cylink C4 (ex. Cytec), and Norsocryl 104 (ex. Atofina), or vinyl monomers with long alkyl chains, such as iauryl (meth)acrylate, and stearyl (meth)acrylate or adhesion promoters such as β-napthyl methacrylate.

Preferably the macromonomer is prepared from at least a first vinyl monomer feed and a different second vinyl monomer feed where either the first vinyl monomer feed and/or the second vinyl monomer feed comprises composition (a): i) 10 to 100 wt%, more preferably 20 to 100 wt% and most preferably 25 to

95 wt% of CH₂=CR⁶-COOR⁷ wherein R⁶ is H or methyl and R⁷ is optionally substituted alkyl or cycloalkyl of 1 to 20 carbon atoms; Ii) 0 to 40 wt%, more preferably 0 to 30 wt% and most preferably 0 to 25 wt% of aromatic vinyl monomers; iii) 0 to 15 wt%, more preferably 0 to 10 wt% and most preferably 0 to 6 wt% of acid functional vinyl monomers; iv) 0 to 15 wt%, more preferably 0 to 7 wt% and most preferably 0 to 5 wt% of crosslinking functional vinyl monomers: v) 0 to 20 wt%, more preferably 0 to 15 wt% and most preferably 0 to 10 wt% of vinyl monomers not in i) to iv); where i) + ii) + iii) + (iv) + (v) add up to 100%; and wherein said second vinyl monomer feed is different from said first vinyl monomer feed.

Preferably either the first vinyl monomer feed and/or the second vinyl monomer feed comprises composition (b): i) 10 to 98 wt%, more preferably 20 to 95 wt% and most preferably 25 to

90 wt% of CH₂=CR⁶-COOR⁷ wherein R⁶ is H or methyl and R⁷ is optionally substituted alkyl or cycloalkyl of 1 to 20 carbon atoms; ii) 0 to 40 wt%, more preferably 0 to 30 wt% and most preferably 0 to 25 wt% of aromatic vinyl monomers; iii) 2 to 20 wt%, more preferably 2 to 15 wt% and most preferably 2 to 10 wt% of acid functional vinyl monomers; iv) 0 to 30 wt%, more preferably 0 to 7 wt% and most preferably 0 to 5 wt% of crosslinking functional vinyl monomers: v) 0 to 20 wt%, more preferably 0 to 15 wt% and most preferably 0 to 10 wt% of vinyl monomers not in i) to iv); where i) + ii) + iii) + (iv) + (v) add up to 100%; and wherein said second vinyl monomer feed is different from said first vinyl monomer feed. Most preferably when the first vinyl monomer feed comprises composition (a), the different second vinyl monomer feed comprises composition (b) and when the first vinyl monomer feed comprises composition (b) the different second vinyl monomer feed comprises composition (a).

In a fifth embodiment of the present invention there is provided a process for the preparation of an aqueous composition comprising a vinyl graft copolymer and containing < 50wt% of organic co-solvent by weight of the graft copolymer, said process comprising the steps:

A) polymerising at least two different vinyl monomer feeds where the at least two vinyl monomer feeds comprise in the range of from 0 to 50 wt%, preferably 0 to 42 wt% and especially 0 to 20 wt% of vinyl monomers carrying anionic or potentially anionic water-dispersing groups using an aqueous free radical polymerisation process to obtain a macromonomer(s) of Formula 1 :

CH₂=C(R¹HX]_n (1)

where R¹ = optionally substituted aryl, -C(O)OR² or -C(O)NR² R³;

R² = -H, -CH₃ or optionally substituted Ci to Ci₈ alkyl; cycloalkyl, aryl,

(alkyl)aryl;

R³= -H, -CH₃or optionally substituted Ci to Ci₈ alkyl; cycloalkyl, aryl,

(alkyl)aryl;

X = residue of a vinyl monomer; n = an integer in the range of from 2 to 50,000;

B) polymerising i) 20 to 95 wt% of vinyl monomer in the presence of ii) 80 to 5 wt% of the macromonomer(s) prepared in step a) using an aqueous free radical polymerisation process, where i) and ii) add up to 100%.

General methods for preparing aqueous vinyl polymers are reviewed in the Journal of Coating Technology, volume 66, number 839, pages 89 to 105 (1995) and these methods are included herein by reference.

The macromonomer and the polymeric backbone are preferably prepared by free radical polymerisation. The free radical polymerisation can be performed by techniques well known in the art, for example, as emulsion polymerisation, solution polymerisation, suspension polymerisation or bulk polymerisation. Furthermore the free radical polymerisation may be carried out as a batch or as a semi-continuous polymerisation process.

The macromonomer may be prepared by any known technique including those discussed above and may include directly synthesising the macromonomer in the presence of water (for example by emulsion polymerisation, suspension polymerisation, micro-suspension polymerisation or mini emulsion polymerisation), or by solution polymerisation where the solution may be water or any organic solvent. If the solution is water the monomers are preferably soluble in water. Preferably the macromonomer is prepared by solution polymerisation, emulsion polymerisation or suspension polymerisation. Preferably the macromonomer is prepared in an aqueous process. Preferably the continuous phase of the aqueous process comprises > 50 wt% , more preferably > 80 wt% and most preferably > 95 wt% of water.

Preferably the polymeric backbone is prepared in an aqueous process. Preferably the polymeric backbone is prepared by solution polymerisation or emulsion polymerisation.

The process for preparing the vinyl graft copolymer may be carried out in a number of modes including but not limited to polymerising all of the macromonomer and vinyl monomers in one batch, pre-charging the macromonomer to a reactor and subsequently feeding in the vinyl monomers in one or more stages and/or using a gradient feeding technique (or vice versa), feeding both macromonomer and vinyl monomers to a reactor (optionally pre-charged with some macromonomer), preparing a graft copolymer by feeding the vinyl monomers to the macromonomer which is simultaneously fed into a reactor (optionally pre-charged with some macromonomer) or continuously feeding a mixture of macromonomer and vinyl monomers into a reactor.

Preferably the free-radical polymerisation is effected by heating the reactor contents to a temperature in the range of from 30 to 100⁰C and more preferably in the range of from 30 to 90⁰C.

A free-radical polymerisation of vinyl monomers will require the use of free-radical- yielding initiator to initiate the vinyl polymerisation. Suitable free-radical-yielding initiators include inorganic peroxides such as K, Na or ammonium persulphate, hydrogen peroxide, or percarbonates; organic peroxides, such as acyl peroxides including e.g. benzoyl peroxide, alkyl hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide; dialkyl peroxides such as di-t-butyl peroxide; peroxy esters such as t-butyl perbenzoate and the like; 2,2'-azo-bis(2-methyl butane nitrile) (ANBN); mixtures may also be used. The peroxy compounds are in some cases advantageously used in combination with suitable reducing agents (redox systems) such as Na or K pyrosulphite or bisulphite, and iso-ascorbic acid. Metal compounds such as Fe. EDTA (EDTA is ethylene diamine tetracetic acid) may also be usefully employed as part of the redox initiator system. Azo functional initiators may also be used. Preferred azo initiators include azobis(isobutyronitrile) and 4,4'-azobis(4-cyanovaleric acid). It is possible to use an initiator partitioning between the aqueous and organic phases, e.g. a combination of t-butyl hydroperoxide, iso-ascorbic acid and Fe.EDTA. The amount of initiator or initiator system to use is conventional, e.g. within the range 0.05 to 6 wt% based on the total vinyl monomer(s) used. Preferred initiators for preparing the macromonomers include ammonium persulphates, sodium persulphates, potassium persulphates, azobis(isobutyronitrile) and/or 4,4'-azobis(4-cyanovaleric acid). Preferred initiators for preparing the polymeric backbone include redox systems and persulphates as described above. A further amount of initiator may optionally be added at the end of the polymerisation process to assist the removal of any residual vinyl monomers.

Macromonomers may be prepared by a number of processes including but not limited to the use of catalytic chain transfer agents, diarylethene or high temperature processes (such as those described in US 5710227).

To prepare a macromonomer a catalytic chain-transfer agent is preferably added to the free radical polymerisation process. The macromonomer is in this invention a vinyl polymer with a terminal unsaturated group which is preferably prepared by free-radical emulsion polymerisation or suspension polymerisation of at least two different vinyl monomer feeds in the presence of a catalytic chain-transfer agent. Use of a catalytic chain-transfer agent allows control over the molecular weight of the macromonomer as well as creating terminal unsaturated groups. In catalytic chain-transfer polymerisation (CCTP) a free radical polymerisation is carried out using a free radical forming initiator and a catalytic amount of a selected transition metal complex acting as a catalytic chain transfer agent (CCTA), and in particular a selected cobalt chelate complex. Such a technique has been described fairly extensively in the literature within the last twenty years or so. For example, various literature references, such as N. S. Enikolopyan et al, J.Polym.Chem.Ed, VoI 19, 879 (1981), discloses the use of cobalt Il porphyrin complexes as chain transfer agents in free radical polymerisation, while US 4,526,945 discloses the use of dioxime complexes of cobalt Il for such a purpose. Various other publications, e.g. US 4,680,354, EP-A-0196783, EP-A-0199436 and EP-A-0788518 describe the use of certain other types of cobalt Il chelates as chain-transfer agents for the production of oligomers of vinyl monomers by free radical polymerisation. WO-A-87/03605 on the other hand claims the use of certain cobalt III chelate complexes for such a purpose, as well as the use of certain chelate complexes of other metals such as iridium and rhenium.

Preferably in the range of from 0 to 100 wt ppm of catalytic chain-transfer agents based on the weight of vinyl monomer required for the macromonomer is used, more preferably < 60 wt ppm, most preferably < 35 wt ppm and especially < 20 wt ppm is used.

The preferred process for preparing a macromonomer is using a free-radical- initiated aqueous emulsion polymerisation in a polymerisation reactor of at least one vinyl monomer, which process employs a hydrophobic Co chelate complex as a CCTA, a stabilising substance for the emulsion polymerisation process and a vinyl monomer feed stage wherein an aqueous pre-emulsified mixture, comprising at least part of the Co chelate employed, at least part of the stabilising substance employed and (i) a non- polymerisable organic solvent and/or (ii) a polymerisable vinyl monomer in unpolymerised or at least partially polymerised form, is contacted in the reactor with vinyl monomer feed stage at the beginning of and/or during the course of the vinyl monomer feed stage.

Furthermore, if used, the cobalt chelate catalysts may be added in stages between the vinyl monomer feeds.

Preferably when using a cobalt chelate catalyst the ratio of acrylic to methacrylic vinyl monomers is in the range of from 40:60 to 100:0 for the polymeric backbone.

Preferably when using a cobalt chelate catalyst the ratio of acrylic to methacrylic vinyl monomers is in the range of from 0:100 to 40 : 60 for the macromonomer(s).

In a further preferred embodiment of the invention the macromonomer is prepared by the use of diarylethene. The use of diarylethene is described in detail in W. Bremser et al, Prog.Org.Coatings, 45, (2002, 95 and JP 3135151, DE 10029802 and US 2002/0013414, incorporated herein by reference. Examples of diarylethene include but are not limited to diphenylethene. Preferably < 7.5 wt%, more preferably < 5 wt%, especially < 3 wt% and most especially 0.5 to 2.5 wt% of diarylethene, based on the weight of vinyl monomers required for the macromonomer, is used.

Preferably when obtaining the macromonomer using at least two different vinyl monomer feeds, long feed times per feed are used. Preferably the complete vinyl monomer feed may take up to 4 hours. If a sequential polymerisation is carried out to obtain the macromonomer it is preferred that the vinyl monomer residue from the first feed is as low as possible. This is usually achieved by waiting for ah hour between the end of the first feed and the start of the second feed.

Molecular weight control additional to that provided by catalytic chain-transfer agents may be provided by using additional chain-transfer agents such as mercaptans and halogenated hydrocarbons as exemplified below. Preferably < 2 wt% by weight of chain-transfer agent based on vinyl monomers required for the macromonomer is used, more preferably < 1 wt%, most preferably < 0.5 wt% and especially 0 wt% is used. After the macromonomer has been formed the vinyl monomers required for the polymeric backbone are added to the macromonomer and are preferably polymerised by a free radical aqueous emulsion or suspension polymerisation in the presence of a conventional initiator.

To prepare the polymeric backbone a chain-transfer agent may be added to control the molecular weight of the polymeric backbone. Suitable chain-transfer agents include mercaptans such as n-dodecylmercaptan, n-octylmercaptan, t-dodecylmercaptan, mercaptoethanol, iso-octyl thioglycolurate, C₂ to C₈ mercapto carboxylic acids and esters thereof such as 3-mercaptopropionic acid and 2-mercaptopropionic acid; and halogenated hydrocarbons such as carbon tetrabromide and bromotrichloromethane.

Preferably < 5% by weight of chain-transfer agent based on vinyl monomers required for the polymeric backbone is used, more preferably < 4 wt% and most preferably < 3 wt%.

Surfactants can be utilised in order to assist in the dispersion of the emulsification of the vinyl graft copolymer in water (even if it is self-dispersible). Suitable surfactants include but are not limited to conventional anionic, cationic and/or non-ionic surfactants and mixtures thereof such as Na, K and NH₄ salts of dialkylsulphosuccinates, Na, K and NH₄ salts of sulphated oils, Na, K and NH₄ salts of alkyl sulphonic acids, Na, K and NH₄ alkyl sulphates, alkali metal salts of sulphonic acids; fatty alcohols, ethoxylated fatty acids and/or fatty amides, and Na, K and NH₄ salts of fatty acids such as Na stearate and Na oleate. Other anionic surfactants include alkyl or (alk)aryl groups linked to sulphonic acid groups, sulphuric acid half ester groups (linked in turn to polyglycol ether groups), phosphonic acid groups, phosphoric acid analogues and phosphates or carboxylic acid groups. Cationic surfactants include alkyl or (alk)aryl groups linked to quaternary ammonium salt groups. Non-ionic surfactants include polyglycol ether compounds and preferably polyethylene oxide compounds as disclosed in "non-ionic surfactants - Physical chemistry" edited by M.J. Schick, M. Decker 1987. The amount of surfactant used is preferably 0 to 15% by weight, more preferably 0 to 8% by weight, still more preferably 0 to 5% by weight, especially 0.1 to 3% by weight and most especially 0.3 to 2% by weight based on the weight of the vinyl graft copolymer.

If desired the aqueous composition of the invention can be used in combination with other polymer compositions which are not according to the invention.

Furthermore the vinyl graft copolymer may comprise macromonomers that are not according to the invention such as macromonomers obtained using a single feed. Preferably the vinyl graft copolymer comprises < 50 wt%, more preferably < 30 wt%, especially < 10 wt% and most especially < 1 wt% of macromonomer obtained using a single feed.

According to a sixth embodiment of the present invention there is provided a process for preparing an aqueous composition comprising at least one vinyl graft copolymer as according to the present invention and containing < 50 wt% of organic co- solvent by weight of the graft copolymer and at least one additional vinyl polymer comprising the steps: a) polymerising at least two different vinyl monomer feeds where the at least two different vinyl monomer feeds comprise in the range of from 0 to 50 wt%, preferably 0 to 42 wt% and especially 0 to 20 wt% of vinyl monomers carrying anionic or potentially anionic water-dispersing groups; using an aqueous free radical polymerisation process to obtain a macromonomer(s) of Formula 1 :

CH₂=C(R¹HX]_n (1)

where R¹ = optionally substituted aryl, -C(O)OR² or -C(O)NR² R³;

R² = -H, -CH₃ or optionally substituted Ci to Ci₈ alkyl, cycloalkyl, aryl, (alkyl) aryl;

R³= -H, -CH₃or optionally substituted C₁ to C₁₈ alkyl, cycloalkyl, aryl, (alkyl) aryl;

X = residue of vinyl monomer; n = an integer in the range of from 2 to 50,000; b) polymerising i) 20 to 95 wt% of vinyl monomer in the presence of ii) 80 to 5 wt% of the macromonomer(s) prepared in step a) using an aqueous free radical polymerisation process, where i) and ii) add up to 100%; c) polymerising iii) 0 to 70 wt% of vinyl monomer in the presence of iv) 100 to 30 wt% of the vinyl graft copolymer prepared in step b), to form said additional vinyl polymer; where iii) and iv) add up to 100%.

The aqueous composition of the present invention may be applied to a variety of substrates including wood, board, metals, stone, concrete, glass, cloth, leather, paper, plastics, foam and the like, by any conventional method including brushing, dipping, flow coating, spraying, flexo printing, gravure printing, ink-jet printing, any other graphic arts application methods and the like. The aqueous carrier medium is removed by natural drying or accelerated drying (by applying heat) to form a coating.

Accordingly, in a further embodiment of the invention there is provided a coating, a polymeric film, a printing ink and/or an overprint lacquer obtainable from an aqueous composition of the present invention.

It has also been found that the aqueous composition of the invention is suitable for use as an adhesive, accordingly there is also provided an adhesive obtainable from an aqueous composition of the present invention. Types of adhesives include pressure sensitive adhesives, hot melt, contact and laminating adhesives.

The aqueous composition of the invention may contain conventional ingredients, some of which have been mentioned above; examples include pigments, dyes, emulsifiers, surfactants, plasticisers, thickeners, heat stabilisers, levelling agents, anti- cratering agents, fillers, sedimentation inhibitors, UV absorbers, antioxidants, drier salts, organic co-solvents, wetting agents and the like introduced at any stage of the production process or subsequently. It is possible to include an amount of antimony oxide in the dispersions to enhance the fire retardant properties.

Preferably the process for preparing an aqueous composition according to the invention is carried out in the presence of 0 to 50 wt%, more preferably 0 to 40 wt%, most preferably 0 to 35 wt%, especially 0 to 25 wt% and most especially 0 to 15 wt% of organic co-solvent by weight of the vinyl graft copolymer.

Preferably the aqueous composition of the invention comprises 0 to 50 wt%, more preferably 0 to 40 wt% and most preferably 0 to 35 wt% of organic co-solvent by weight of the vinyl graft copolymer.

Suitable organic co-solvents which may be added during the process or after the process during formulation steps are well known in the art and include xylene, toluene, butyl acetate and 1-methyl-2-pyrrolidinone.

Optionally an external crosslinking agent may be added to the aqueous composition of the invention to aid crosslinking during or after drying. Examples of reactive functional groups on the polymeric backbone or macromonomer which may be utilised for reaction with an external crosslinking agents include but are not limited to hydroxyl functional groups reacting with isocyanate (optionally blocked), melamine or glycouril functional groups; keto, aldehyde and/or acetoacetoxy carbonyl functional groups reacting with amine, hydrazide, semi-carbazide or hydrazine functional groups; carboxyl functional groups reacting with aziridine, epoxy or carbodiimide functional groups; silane functional groups reacting with silane functional groups; epoxy functional groups reacting with amine or mercaptane groups as well as carboxyl functional groups undergoing metal ion (such as zinc) crosslinking.

The solids content of the aqueous composition of the invention is preferably within the range of from 20 to 60 wt%, and most preferably within the range of from 30 to 50 wt%.

The present invention is now illustrated by reference to the following examples. Unless otherwise specified, all parts, percentages and ratios are on a weight basis. The term comparative means that it is not according to the invention and is denoted with a C.

In the examples, the following abbreviations and terms are specified:

MMA methyl methacrylate

BA n-butyl acrylate

MAA methacrylic acid

2-EHA 2-ethylhexyl acrylate

BMA n-butyl methacrylate

EMA ethyl methacrylate

AA acrylic acid

Mn number average molecular weight

Mw weight average molecular weight

MM macromonomer

SLS sodium lauryl sulphate (surfactant 30% solution in water)

APS ammonium persulphate (initiator)

CCTP catalytic chain transfer polymerisation

GPC gel permeation chromatography

CTA chain transfer agent n.d. not done

MPEGMA methoxy polyethylene glycol methacrylate (Mw 350)

AAEM acetoacetoxy ethyl methacrylate

PS particle size

MFFT minimum film forming temperature

Cobalt chelate complex = Co Il (bis 4,4'-dimethylbenzildioxime diborondifluoride) as disclosed in US 5,962,609.

Molecular weights were determined by GPC relative to polystyrene standards. Preparation of Hvdrophilic Oligomer HO1

A hydrophilic oligomer for use as a stabilising substance in the invention process was prepared using the following procedure. In a round-bottomed flask equipped with a stirrer and reflux condenser, 1044.1 parts of water and 1.64 parts of SLS and 0.59 parts of APS were mixed and heated to 85⁰C. 5 weight % a pre-emulsified feed of 473.5 parts of MMA, 46.2 parts of MAA, 57.7 parts of AAEM, 238.5 parts of water, 9.3 parts of SLS and 15.6 parts of CTA (3-mercaptopropionic acid) was added to the reactor phase at 6O⁰C. At reaction temperature the remaining monomer feed was added over a period of 60 minutes. An initiator feed of 1.37 parts of APS dissolved in 141.1 parts of water was added over a period of 70 minutes. When the initiator feed had been completed the reaction mixture was kept at 85⁰C for 20 minutes. After 20 minutes the temperature was reduced to 60°C. The pH of the reactor phase was increased to 8 using a mixture of 45.48 parts aqueous NH₃ (25 wt% in water) and 36.25 parts of water. A solution of 0.82 parts of sodium metabisulphite in 13.6 parts of water was fed to the reactor phase in 45 minutes, directly after the start of this feed a slurry of 0.78 parts of t-butyl hydroperoxide and 2.27 parts of water was added. This was repeated after 15 and 30 minutes after the start of the sodium metabisulphite feed. After completion of the sodium metabisulphite feed the reactor phase was cooled to 30°C and filtered. The final product had a pH=8.0 and a solids content of 30% The molecular weight of the hydrophilic oligomer HO1 was 12,000 g/mol.

Macromonomer (MM) preparation with CCTP

Preparation of a single-phase macromonomer C1 to C10

In a round-bottomed flask equipped with a stirrer and reflux condenser 47.17 parts of oligomer material HO1 (30% solids, example C2 to C9) or 28.3 parts of SLS (30% solids, example C1), or 16.7 parts of SLS (30% solids, example C10) were mixed with a preformed solution of 0.003 parts of cobalt chelate complex and 14.15 parts of MMA at room temperature. After mixing for 1 hour at room temperature the emulsified mixture was diluted with 1196 parts of water and heated to 75°C thereby forming a pre-emulsified mixture. At 75°C, 5.66 parts of an APS solution (2.5% in water) was added to the reactor phase to start the polymerisation in the pre-emulsified mixture in the reactor. The reactor phase was further heated to 85⁰C. The reactor phase was kept at 85⁰C for 10 minutes. At this point a vinyl monomer feed as described in table 1 below and a separate APS initiator feed, comprising 109 parts of an APS solution (2.5% in water) and 9.43 parts of SLS (30% solution in water) at a pH of 8.5, to the reactor were started. The vinyl monomer feed and separate initiator feed were added over a period of 240 minutes. Following the addition of the vinyl monomer feed the vinyl monomer feed tank was rinsed with 53.8 parts of water. The polymerisation mixture kept at 85⁰C for 90 minutes. The emulsion was cooled to room temperature and filtered. The specifications of the final single-phase macromonomers C1 to C10 are given in table 2 below. Preparation of a sequential macromonomer S1 to S10

In a round-bottomed flask equipped with a stirrer and reflux condenser 47.17 parts of oligomer material HO1 (30% solids, example S2 to S9) or 28.3 parts of SLS (30% solids, example S1), or 16.7 parts of SLS (30% solids, example S10) were mixed with a preformed solution of 0.003 parts of cobalt chelate complex and 14.15 parts of MMA at room temperature. After mixing for 1 hour at room temperature the emulsified mixture was diluted with 1196 parts of water and heated to 75°C thereby forming a pre-emulsified mixture. At 75°C, 5.66 parts of an APS solution (2.5% in water) was added to the reactor phase to start the polymerisation in the pre-emulsified mixture in the reactor. The reactor phase was further heated to 85°C. The reactor phase was kept at 85°C for 10 minutes. At this point a vinyl monomer feed MF1 with a composition as described in table 1 and a separate APS initiator feed, comprising A parts of an APS solution (2.5% in water) (see table 1) and 5.66 parts of SLS (30% solution in water) at a pH of 8.5, were fed to the reactor in B minutes (see table 1 below). After completion of the vinyl monomer feed the reaction mixture was kept at 85⁰C for 60 minutes. After 60 minutes a vinyl monomer feed stage MF2, with a composition as described in table 1 and a separate APS initiator feed, comprising C parts of an APS solution (2.5% in water) (see Table 1) and 3.66 parts of SLS (30% solution in water) at a pH of 8.5, was fed to the reactor in D minutes (see table 1). Following the addition of the vinyl monomer feed the vinyl monomer feed tank was rinsed with 53.8 parts of water. The polymerisation mixture kept at 85°C for 90 minutes. The emulsion was cooled to room temperature and filtered. The specifications of the sequential macromonomers S1 to S10 are given in table 2 below.

Preparation of a macromonomer using a gradient process P1 to P10

In a round-bottomed flask equipped with a stirrer and reflux condenser 47.17 parts of oligomer material HO1 (30% solids, example P2 to P9) or 28.3 parts of SLS (30% solids, example P1), or 16.7 parts of SLS (30% solids, example P10) were mixed with a preformed solution of 0.003 parts of cobalt chelate complex and 14.15 parts of MMA at room temperature. After mixing for 1 hour at room temperature the emulsified mixture was diluted with 1196 parts of water and heated to 75°C thereby forming a pre-emulsified mixture. At 75⁰C, 5.66 parts of an APS solution (2.5% in water) was added to the reactor phase to start the polymerisation in the pre-emulsified mixture in the reactor. The reactor phase was further heated to 85°C. The reactor phase was kept at 85°C for 10 minutes. At this point a vinyl monomer feed MF1 with a composition as displayed in table 1 below and a separate APS initiator feed comprising A parts of an APS solution (2.5% in water) (see table 1) and 9.43 parts of SLS (30% solution in water) at a pH of 8.5, was fed to the reactor in 240 minutes. At the same time a second vinyl monomer feed MF2 was started. The second vinyl monomer feed stage MF2 with a composition as displayed in table 1 was fed to vinyl monomer feed MF1 in 240 minutes. Following the addition of the vinyl monomer feed the vinyl monomer feed tank was rinsed with 53.8 parts of water. The polymerisation mixture kept at 85⁰C for 90 minutes. The emulsion was cooled to room temperature and filtered. The specifications of the gradient macromonomers P1 to P10 are shown in table 2 below.

Table 1

o

Table 1 continued

N

Macromonomer preparation with diphenyl ethene

Preparation of a single-phase macromonomer C11

In a round-bottomed flask equipped with a stirrer and reflux condenser 1.46 parts of SLS (30% solids) and 517.81 parts of water were mixed and heated to 75⁰C. At 75⁰C, 3.67 parts of an APS solution (2.5% in water) and 10% of an emulsified monomer feed comprising 46.93 parts of water, 13.12 parts of SLS (30% solids) 218.70 parts of MMA, 72.90 parts of BA and 0.73 parts of diphenyl ethene was added to the reactor phase. The reactor phase was further heated to 85°C. The reactor phase was kept at 85°C for 5 minutes. At this point the remaining part of the monomer feed and a separate APS initiator feed, comprising 70 parts of an APS solution (2.5% in water) (see table 1) and 4.86 parts of SLS (30% solution in water) were started. The vinyl monomer feed and separate initiator feed were added over a period of 180 minutes. Following the addition of the vinyl monomer feed the vinyl monomer feed tank was rinsed with 50 parts of water. The polymerisation mixture kept at 85°C for 120 minutes. The emulsion was cooled to room temperature and filtered. The specifications of the final macromonomer C11 is given in table 2 below.

Preparation of a sequential macromonomer S11

In a round-bottomed flask equipped with a stirrer and reflux condenser 1.46 parts of SLS (30% solids) and 517.81 parts of water were mixed and heated to 75°C. At 75°C, 3.67 parts of an APS solution (2.5% in water) and 13% of an emulsified monomer feed comprising 35.20 parts of water, 9.84 parts of SLS (30% solids), 218.70 parts of MMA and 0.55 parts of diphenyl ethene was added to the reactor phase. The reactor phase was further heated to 85°C. The reactor phase was kept at 85°C for 5 minutes. At this point the remaining part of the monomer feed and a separate APS initiator feed, comprising 9.84 parts of an APS solution (2.5% in water) and 3.65 parts of SLS (30% solution in water), were fed to the reactor in 145 minutes. After completion of the vinyl monomer feed the reaction mixture was kept at 85°C for 60 minutes. After 60 minutes a vinyl monomer feed stage MF2, comprising 11.73 parts of water, 3.28 parts of SLS (30% solids), 72.90 parts of BA and 0.18 parts of diphenylethene and a separate APS initiator feed, comprising 18.37 parts of an APS solution (2.5% in water) and 3.28 parts of SLS (30% solution in water), was fed to the reactor in 45 minutes. Following the addition of the vinyl monomer feed the vinyl monomer feed tank was rinsed with 50 parts of water. The polymerisation mixture kept at 85⁰C for 120 minutes. The emulsion was cooled to room temperature and filtered. The specifications of the final macromonomer S11 is given in table 2 below.

Preparation of a macromonomer with using a gradient process P11

In a round-bottomed flask equipped with a stirrer and reflux condenser 1.46 parts of SLS (30% solids) and 517.81 parts of water were mixed and heated to 75°C. At 75°C, 3.67 parts of an APS solution (2.5% in water) and 13% of an emulsified monomer feed comprising 35.20 parts of water, 9.84 parts of SLS (30% solids), 218.70 parts of MMA and 0.55 parts of diphenyl ethene was added to the reactor phase. The reactor phase was further heated to 85°C. The reactor phase was kept at 85°C for 5 minutes. At this point the remaining part of the monomer feed and a separate APS initiator feed, comprising 73.48 parts of an APS solution (2.5% in water) and 4.86 parts of SLS (30% solution in water), were fed to the reactor in 180 minutes (see table 1). The second vinyl monomer feed stage MF1 comprising 11.73 parts of water, 3.28 parts of SLS, 72.90 parts of BA and 0.18 parts of diphenyl ethene was fed to vinyl monomer feed 1 in 180 minutes. Following the addition of the vinyl monomer feed the vinyl monomer feed tank was rinsed with 50 parts of water. The polymerisation mixture kept at 85⁰C for 120 minutes. The emulsion was cooled to room temperature and filtered. The specifications of the final macromonomer P11 is shown in table 2 below.

Table 2

K

Table 2 continued

Ol

Preparation of vinyl graft copolymers (examples 1 to 28)

In a round-bottomed flask (the reactor) equipped with a stirrer and reflux condenser X parts of macromonomer dispersion (see table 3), Y parts of SLS (30% solution in water) and Z parts of water were mixed. The reactor phase was heated to 6O⁰C. At this temperature a monomer mixture as described in table 3 was added to the reactor phase. The reactor phase mixed for 1 hour at 60⁰C. After 1 hour, A parts of an isoascorbic acid solution (2.5% in water, pH=8.5) was added to the reactor phase followed by B parts of a t-butyl peroxide (tBHPO) solution (30% in water). The polymerisation reaction was initiated with 0.3 parts of a solution of Fe(EDTA) (1 % in water). The batch became exothermic, the temperature increased to 80⁰C. After the peak temperature was reached the reactor phase was kept at 80°C for 30 minutes. After 30 minutes C parts of an isoascorbic acid solution (2.5% in water, pH=8.5) was added to the reactor phase followed by D parts of a t-butyl peroxide solution (30% in water). The reactor phase was kept at 8O⁰C for 30 minutes. The emulsion was cooled to room temperature. The pH was adjusted to pH of 8.5 with ammonia. 3.45 parts of Proxel Ultra 10 was added and the emulsion was filtered. The specifications of the final vinyl graft copolymer emulsions are shown in table 4 below.

Table 3

S

Table 3 continued

CO

Table 4

Formulation of the coating compositions

The example emulsions of the invention and the comparative example emulsions were formulated with coalescent and if necessary a wetting agent. Before formulation the pH of the emulsion was increased to a pH in the range of 7.0 to 7.5 with an ammonia solution (12.5%). To each emulsion was added drop wise between 5 to 10 wt% on total emulsion of butyl diglycol and optionally 1 wt% of BYK 346 (wetting agent). The butyl diglycol was adjusted to a pH of 7 using ammonia. The formulated emulsions were allowed to stand at room temperature for 24 hours and then were cast with a blade roller (125 μm wet) on Leneta chart or (80 μm wet) on glass. The resultant films were dried at room temperature after which they were annealed at 52°C for 16 hours (all the resultant films were tack-free) and then scratch resistance, Kδnig Hardness, elongation at break and toughness were determined. The results are shown below in Table 5.

Test Methods

Surface hardness: Konig Hardness as used herein is a standard measure of hardness, being a determination of how the viscoelastic properties of a film formed from the dispersion slows down a swinging motion deforming the surface of the film, and is measured according to DIN 53157 NEN 5319 using an Erichsen hardness equipment.

Scratch resistance: Scratch resistance was determined by scratching the surface with a finger nail in one swift motion. The damage to the film was assessed, a 0 being very poor (film was completely removed) and a 5 excellent (no damage to the film was observed).

MFFT: Minimum film forming temperature of an aqueous composition as used herein is the temperature where the composition forms a smooth and crack free coating or film using DIN 53787 and applied using a Sheen MFFT bar SS3000.

Tensile tests: A 400 micron wet film of the formulated aqueous coating composition of the invention was dried for 4 hours at room temperature, followed by 16 hours annealing at 52°C. A halter according to DIN 52 910-53 was prepared. Toughness (MPa) and elongation at break (%) of the free film were determined using an lnstron optical tension meter.

Sediment: Sediment is unstabilised solid material (in the order of microns rather than nanometers) which is formed during dispersing or reaction and which will settle or precipitate upon storage and / or heating. It may be determined quantitatively by centrifuging. The sediment content was determined by taking 50cm³ of the resultant dispersion of the examples prepared above, diluting this with water (1 :1) and centrifuging the diluted composition for 15 minutes at 1500rpm (276G) in a centrifuge tube.

Each division on the tube tip represents 0.05 cm³ or 0.05% sediment. The outcome, i.e. the level of solid sediment in the tube tip was then multiplied by 2 to take into account the dilution factor. Table 5

CO

Table 5 continued

Claims

1. An aqueous composition comprising a vinyl graft copolymer and containing < 50 wt% of organic co-solvent by weight of the graft copolymer, said vinyl graft copolymer comprising: i) 20 to 95 wt% of a polymeric backbone; and ii) 80 to 5 wt% of a macromonomer(s) of Formula (1 ) grafted to the polymeric backbone:

CH₂=C(R¹HX]_n (1)

where R¹ = optionally substituted aryl, -C(O)OR² or -C(O)NR² R³;

R² = -H, -CH₃ or optionally substituted C₁ to Ci₈ alkyl, cycloalkyl, aryl

(alkyl)aryl;

R³= -H, -CH₃ or optionally substituted Ci to C₁₈ alkyl, cycloalkyl, aryl

(alkyl)aryl;

X = residue of vinyl monomer; n = an integer in the range of from 2 to 50,000; where the macromonomer(s) is obtained using at least two different vinyl monomer feeds; where the at least two different vinyl monomer feeds comprise in the range of from 0 to 50 wt% of vinyl monomers carrying anionic or potentially anionic water-dispersing groups; and where i) and ii) add up to 100%.

2. An aqueous composition according to claim 1 wherein the macromonomer(s) is obtained from a process comprising introducing a first vinyl monomer feed to a reactor, where the first vinyl monomer feed continually varies in its composition due to the addition of a different second vinyl monomer feed to the first vinyl monomer feed and polymerising the vinyl monomers introduced into the reactor.

3. An aqueous composition according to claim 1 wherein the macromonomer(s) is obtained from a process comprising simultaneously introducing a first vinyl monomer feed and a different second vinyl monomer feed into a reactor where the rate of introduction of the first vinyl monomer feed varies with respect to the rate of introduction of the second vinyl monomer feed and polymerising the vinyl monomers introduced into the reactor.

4. An aqueous composition according to claim 1 wherein the macromonomer(s) is obtained from a sequential polymerisation process.

5. An aqueous composition according to claim 1 wherein the macromonomer(s) is obtained by the polymerisation of a first vinyl monomer feed and a different second vinyl monomer feed.

6. An aqueous composition according to claim 5 where the weight ratio of the first vinyl monomer feed to the second vinyl monomer feed is in the range of from 10:90 to 90:10.

7. An aqueous composition according to claim 5 where either the first vinyl monomer feed and/or the second vinyl monomer feed comprises composition (a): i) 10 to 100 wt% of CH₂=R⁶COOR⁷ where R⁶ is H or methyl and R⁷ is optionally substituted alkyl or cycloalkyl of 4 to 20 carbons atoms; ii) 0 to 40 wt% of aromatic vinyl monomers; iii) 0 to 15 wt% of acid functional vinyl monomers; iv) 0 to 10 wt% of crosslinking functional vinyl monomers; v) 0 to 20 wt% of vinyl monomers not in i) to iv); where i) + ii) + iii) + iv) + v) add up to 100%; and wherein said second vinyl monomer feed is different from said first vinyl monomer feed.

8. An aqueous composition according claim 5 where either the first vinyl monomer feed and/or the second vinyl monomer feed comprises composition (b): i) 10 to 98 wt% of CH₂=CR⁶-COOR⁷ where R⁶ is H or methyl and R⁷ is optionally substituted alkyl or cycloalkyl of 1 to 20 carbon atoms; ii) 0 to 40 wt% of aromatic vinyl monomers; iii) 2 to 20 wt% of acid functional vinyl monomers; iv) 0 to 30 wt% of crosslinking functional vinyl monomers; v) 0 to 20 wt% of vinyl monomers not in i) to iv); where i) + ii) + iii) + iv) + v) add up to 100%; and wherein said second vinyl monomer feed is different from said first vinyl monomer feed.

9. An aqueous composition comprising a vinyl graft copolymer and containing < 50 wt% of organic co-solvent by weight of the graft copolymer, said vinyl graft copolymer comprising: i) 20 to 95 wt% of a polymeric backbone; and ii) 80 to 5 wt% of at least two different macromonomers comprising: a) a first macromonomer of Formula (1 ); b) a second macromonomer of Formula (1 ); c) optionally further macromonomers of Formula (1);

CH₂=C(R¹HX]_n (D where R¹ = optionally substituted aryl, -C(O)OR² or -C(O)NR² R³;

R² = -H, -CH₃ or optionally substituted C₁ to C₁₈ alkyl, cycloalkyl, aryl,

(alkyl)aryl;

R³ = -H, -CH₃ or optionally substituted C₁ to C₁₈ alkyl, cycloalkyl, aryl,

(alkyl)aryl;

X = residue of vinyl monomer; n = an integer in the range of from 2 to 50,000; grafted to the polymeric backbone; wherein the macromonomers are obtained using at least two different vinyl monomer feeds; where the at least two different vinyl monomer feeds comprise in the range of from 0 to 50 wt% of vinyl monomers carrying anionic or potentially anionic water-dispersing groups; and where i) and ii) add up to 100%.

10. An aqueous composition according to claim 9 wherein the weight ratio of a) : b) + c) is in the range of from 10:90 to 90:10.

11. An aqueous composition comprising a vinyl graft copolymer and containing < 50 wt% of organic co-solvent by weight of the graft copolymer, said vinyl graft copolymer comprising: i) 20 to 95 wt% of a polymeric backbone; and ii) 80 to 5 wt% of at least two different macromonomers comprising: a) 0 to 99 wt% of a first macromonomer of Formula (1 ); b) 1 to 99 wt% of a second macromonomer of Formula (1 ); c) 0 to 80 wt% of further macromonomers of Formula (1 );

CH₂=C(R¹HX]_n (1)

where R¹ = optionally substituted aryl, -C(O)OR² or -C(O)NR² R³;

(alkyl)aryl;

R³ = -H, -CH₃ or optionally substituted C₁ to Ci₈ alkyl, cycloalkyl, aryl,

(alkyl)aryl;

X = residue of vinyl monomer; n = an integer in the range of from 2 to 50,000; a), b), and c) add up to 100%; grafted to the polymeric backbone; where a) and c) are obtained using at least one vinyl monomer feed; where b) is obtained using at least two different vinyl monomer feeds; where the vinyl monomer feeds comprise in the range of from 0 to 50 wt% of vinyl monomers carrying anionic or potentially anionic water-dispersing groups; and where i) and ii) add up to 100%.

12. An aqueous composition according to any one of the preceding claims comprising at least one additional vinyl polymer.

13. A process for the preparation of an aqueous composition according to any one of claims 1 to 12, said process comprising the steps:

A) polymerising the at least two different vinyl monomer feeds where the at least two different vinyl monomer feeds comprise in the range of from 0 to 50 wt% of vinyl monomers carrying anionic or potentially anionic water-dispersing groups using an aqueous free radical polymerisation process to obtain a macromonomer(s) of Formula 1 :

CH₂=C(R¹MX]_n (1)

where R¹ = optionally substituted aryl, -C(O)OR², -C(O)NR² R³;

R² = -H, -CH₃, optionally substituted C₁ to C₁₈ alkyl, cycloalkyl, aryl,

(alkyl)aryl;

R³= -H, -CH₃, optionally substituted C₁ to Ci₈ alkyl, cycloalkyl, aryl,

(alkyl)aryl;

14. A process for the preparation of an aqueous composition according to claim 12 said process comprising the steps;

A) polymerising at the least two different vinyl monomer feeds where the at least two different vinyl monomer feeds comprise in the range of from 0 to 50 wt% of vinyl monomers carrying anionic or potentially anionic water-dispersing groups using an aqueous free radical polymerisation process to obtain a macromonomer(s) of Formula 1 :

CH₂=C(R¹HX]_n (1)

where R¹ = optionally substituted aryl, -C(O)OR² or -C(O)NR² R³;

(alkyl)aryl;

R³= -H, -CH₃ or optionally substituted C₁ to C₁₈ alkyl, cycloalkyl, aryl, (alkyl)aryl;

B) polymerising i) 20 to 95 wt% of vinyl monomer in the presence of ii) 80 to 5 wt% of the macromonomer prepared in step A) using an aqueous free radical polymerisation process, where i) and ii) add up to 100%;

C) polymerising iii) 0 to 70 wt% of vinyl monomer in the presence of iv) 100 to 30 wt% of the vinyl graft copolymer prepared in step A), to form said additional vinyl polymer; where iii) and iv) add up to 100%.

15. A process according to claim 13 or claim 14 wherein said macromonomer(s) is prepared using a solution polymerisation process, an aqueous emulsion polymerisation process or an aqueous suspension polymerisation process.

16. A process according to claim 13 or claim 14 wherein said macromonomer is prepared in an aqueous process.

17. A process according to claim 13 or claim 14 wherein said vinyl monomer polymerised in step B) are polymerised using an aqueous emulsion polymerisation process or an aqueous suspension polymerisation process.

18. A process according to any one of claims 13 to 17 using in the range of from 0 to 100 wt pm of catalytic chain transfer agent for step A).

19. A process according to any one of claims 13 to 17 using < 7.5 wt% of diarylethene for step A).

20. A macromonomer of Formula (1 ):

CH₂=C(R¹HX]_n (1 )

where R¹ = optionally substituted aryl, -C(O)OR² or -C(O)NR² R³;

R² = -H, -CH₃ or optionally substituted C-i to C₁₈ alkyl, cycloalkyl, aryl, (alkyl)aryl;

X = residue of vinyl monomer; n = an integer in the range of from 2 to 50,000; where the macromonomer is obtained using at least two different vinyl monomer feeds; where the at least two different vinyl monomer feeds comprise in the range of from 0 to 50wt% of vinyl monomers carrying anionic or potentially anionic water-dispersing groups.

21. Use of an aqueous composition according to any one of claims 1 to 12 as a coating composition.

22. Use of an aqueous coating composition according to any one of claims 1 to 12 in graphic art applications.

23. A coating obtainable from an aqueous composition according to any one of claims 1 to 12.

24. An adhesive obtainable from an aqueous composition according to any one of claims 1 to 12.