JP5981527B2 - Thickener - Google Patents

Description

  The present invention relates to a thickener containing a specific polyoxyalkylene-modified vinyl alcohol polymer. More specifically, the present invention relates to a thickener that contains a polyoxyalkylene-modified vinyl alcohol polymer, has high solubility in water or a water-containing solvent, and increases in viscosity with an increase in temperature.

  Since vinyl alcohol polymers (hereinafter sometimes abbreviated as “PVA”) have few surface active properties and strength properties as a few crystalline water-soluble polymers, various binders, paper processing, fiber processing and In addition to being used as a stabilizer for emulsions, it occupies an important position as a raw material for PVA films and PVA fibers. On the other hand, the pursuit of high functionality in which specific performance is improved by controlling crystallinity or introducing a functional group has been performed, and various so-called modified PVAs have been developed.

  It is known that alkyl-modified PVA into which a long-chain alkyl group, which is a hydrophobic group, is introduced exhibits a markedly thickening action due to the association of hydrophobic groups due to hydrophobic group interaction in an aqueous solvent, thereby giving a high-viscosity solution. Specifically, it has been proposed to use a thickener composed of a high-viscosity solution of a long-chain alkyl group-modified PVA as a thickener for vinyl acetate emulsions (see Patent Document 1). The alkyl-modified PVA has a higher solution viscosity as the content of the alkyl group in the PVA increases. However, when the content exceeds a certain content, the water solubility of the alkyl-modified PVA decreases. For this reason, it has been difficult to obtain a high viscosity solution using PVA having a high alkyl group content.

  Further, the aqueous solution of alkyl-modified PVA gives a high-viscosity solution in a temperature range below room temperature. However, when the aqueous solution temperature rises, the viscosity decreases, and when the temperature such as summer increases, the performance as a thickener does not appear. There was a case. For this reason, a thickener that exhibits thickening performance even when the surrounding temperature is high has been desired.

  As such a thickener, for example, a thickener containing polyoxyalkylene-modified PVA having a polyoxybutylene group in the side chain has been proposed (see Patent Document 2). However, the polyoxyalkylene group-modified PVA has a high viscosity of an aqueous solution even near room temperature, and has difficulty in handling.

JP-A-8-060137 International Publication No. 2011/040377

  The present invention has been made based on the above circumstances, and an object thereof is to provide a thickener having excellent thickening, particularly in a temperature region higher than room temperature. Furthermore, it aims at providing the composition (emulsion etc.) which is excellent in storage stability using this thickener especially in the temperature range higher than room temperature.

（式（Ｉ）中、Ｒ^１は水素原子または炭素数１〜８のアルキル基を表す。Ｒ^２およびＲ^３は、いずれか一方がメチル基であり、他方が水素原子である。１０≦ｍ≦４０であり、１≦ｎ≦５０である。）
［２］前記ポリオキシアルキレン変性ビニルアルコール系重合体の４質量％水溶液の粘度を、ロータ回転数が６ｒｐｍの条件でＢＬ型粘度計により測定したとき、２０℃における粘度η_１と６０℃における粘度η_２との比η_２／η_１が２．０以上である上記［１］の増粘剤；
［３］さらに、水または水含有溶媒を含有する上記［１］または［２］の増粘剤；
［４］上記［１］〜［３］のいずれかの増粘剤、油分および水を含有する組成物であって、油分１００質量部に対して前記ポリオキシアルキレン変性ビニルアルコール系重合体を０．１質量部以上５０質量部以下含有する組成物；
に関する。That is, the present invention
[1] A thickener containing a polyoxyalkylene-modified vinyl alcohol polymer, wherein the polyoxyalkylene-modified vinyl alcohol polymer is composed of a polyoxypropylene block and a (poly) oxyethylene block. It has a polyoxyalkylene group represented by the following general formula (I) in the side chain, has a viscosity average polymerization degree P of 200 or more and 5000 or less, a saponification degree of 40 mol% or more and 99.99 mol% or less, A thickener having an oxyalkylene group modification rate S of 0.05 mol% or more and 10 mol% or less;

(In formula (I), R ¹ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ^One of R ² and R ³ is a methyl group, and the other is a hydrogen atom. 10 ≦ m ≦ 40 and 1 ≦ n ≦ 50.)
[2] When the viscosity of a 4% by mass aqueous solution of the polyoxyalkylene-modified vinyl alcohol polymer is measured with a BL-type viscometer under the condition that the rotor rotational speed is 6 rpm, the viscosity η _{1 at} 20 ° C. and the viscosity at 60 ° C. the ratio eta ₂ / eta ₁ and eta ₂ is 2.0 or more thickeners according to [1];
[3] The thickener according to [1] or [2] above, further containing water or a water-containing solvent;
[4] A composition containing the thickener according to any one of [1] to [3] above, an oil component and water, wherein the polyoxyalkylene-modified vinyl alcohol polymer is 0 with respect to 100 parts by mass of the oil component. A composition containing from 1 part by weight to 50 parts by weight;
About.

  The thickener of the present invention has excellent thickening even in a temperature range higher than room temperature. Furthermore, a composition (emulsion or the like) to which the thickener of the present invention is added is excellent in storage stability particularly in a temperature range higher than room temperature.

  Hereinafter, embodiments of the thickener of the present invention and a composition (emulsion, etc.) using the same will be described in detail.

[Thickener]
Since the thickener of the present invention contains PVA having a specific polyoxyalkylene group (hereinafter sometimes abbreviated as “POA group”), which will be described in detail below, in the side chain, it exhibits excellent viscosity. Further, the emulsion to which the thickener is added is excellent in storage stability. The thickener of the present invention may be a powdery thickener made of the above PVA, or may be a liquid thickener containing water or a water-containing solvent. Here, the water-containing solvent is composed of water and a solvent other than water. This liquid thickener is suitable for use in water-dispersible emulsion-containing materials such as paints and adhesives. The liquid thickener may further contain other components in addition to the PVA and water or a water-containing solvent.

(PVA)
The PVA is a polyoxyalkylene-modified vinyl alcohol polymer (hereinafter sometimes abbreviated as “POA-modified PVA”) having a POA group represented by the general formula (I) in the side chain. For example, the POA-modified PVA includes a monomer unit having a POA group represented by the general formula (I) composed of a polyoxypropylene block and a (poly) oxyethylene block in the side chain, and a vinyl alcohol unit (- CH ₂ —CHOH—), and may further have other monomer units.

  The POA group represented by the general formula (I) in the side chain of the POA-modified PVA has a polyoxypropylene block in which the number of repeating units of oxypropylene units is m and the number of repeating units of oxyethylene units is n (poly ) An oxyethylene block, and the (poly) oxyethylene block is arranged on the terminal side of the POA group. Here, when n is 1, the POA group is composed of a polyoxypropylene block and an oxyethylene block. When n is 2 or more, the POA group is a polyoxypropylene block and a polyoxypropylene block. It is comprised from an ethylene block. When the POA group has such a structure, excellent temperature-sensitive thickening and storage stability due to the interaction between the POA groups are exhibited. Although details of the mechanism at this time have not been clarified, as will be described later, the relatively hydrophilic (poly) oxyethylene block is located on the terminal side of the POA group. Hydrophobic interaction between POA groups is promoted, and strong intermolecular crosslinking occurs even in an aqueous solution or a composition (emulsion, etc.) to which the thickener of the present invention is added, thereby increasing in a temperature range higher than room temperature. It is thought to be excellent in viscosity and storage stability.

  The number m of repeating units of the oxypropylene unit in the POA group represented by the general formula (I) needs to satisfy 10 ≦ m ≦ 40, preferably 15 ≦ m ≦ 38, and more preferably 20 ≦ m ≦ 35. When m is less than 10, the temperature-sensitive thickening due to the interaction between POA groups is not sufficiently exhibited. Further, the number n of repeating units of the oxyethylene unit needs to satisfy 1 ≦ n ≦ 50, preferably 3 ≦ n ≦ 40, and more preferably 5 ≦ n ≦ 10. When n is 0, the temperature-sensitive thickening due to the interaction between POA groups is not sufficiently exhibited. On the other hand, even when n exceeds 50, the interaction between POA groups is not sufficiently exhibited.

R ¹ in the POA group represented by the general formula (I) needs to be a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ¹ is preferably a hydrogen atom, a methyl group or a butyl group, more preferably a hydrogen atom or a methyl group.

One of R ² and R ³ in the POA group represented by the general formula (I) is a methyl group, and the other is a hydrogen atom. At this time, it is preferable that R ² is a methyl group and R ³ is a hydrogen atom because it is easy to produce POA-modified PVA.

  The method for producing the POA-modified PVA contained in the thickener of the present invention is not particularly limited, and is composed of a polyoxypropylene block and a (poly) oxyethylene block, and has a POA group represented by the above general formula (I). A method of copolymerizing an unsaturated monomer and a vinyl ester monomer and saponifying the obtained POA-modified vinyl ester polymer is preferable.

  Here, as the unsaturated monomer having a POA group represented by the general formula (I), an unsaturated monomer represented by the following general formula (II) is preferable. Therefore, as a method for producing POA-modified PVA, an unsaturated compound represented by the following general formula (II), which is composed of a polyoxypropylene block and a (poly) oxyethylene block and has a POA group represented by the general formula (I) A method of saponifying the resulting POA-modified vinyl ester polymer by copolymerizing the monomer and the vinyl ester monomer is more preferable.

In the formula (II), R ¹ , R ² , R ³ , m, and n are the same as those in the general formula (I). R ⁴ represents a hydrogen atom or a —COOM group, where M represents a hydrogen atom, an alkali metal or an ammonium group. R ⁵ represents a hydrogen atom, a methyl group or a —CH ₂ —COOM group, where M is as defined above. X represents —O—, —CH ₂ —O—, —CO—, — (CH ₂ ) _k —, —CO—O— or —CO—NR ⁶ —. When X is asymmetric, the direction is not limited. Here, R ⁶ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and 1 ≦ k ≦ 15.

In the unsaturated monomer represented by the general formula (II), preferred examples and numerical ranges of R ¹ , R ² , R ³ , m, and n are the same as those described above in the description of the general formula (I). In particular, from the viewpoint of ease of synthesis of the unsaturated monomer represented by the general formula (II), it is preferable that R ² is a methyl group and R ³ is a hydrogen atom.

In the unsaturated monomer represented by the general formula (II), R ¹ is preferably a hydrogen atom or a methyl group, R ⁴ is a hydrogen atom, and R ⁵ is preferably a hydrogen atom or a methyl group. .

When R ^{1 in the} general formula (II) is a hydrogen atom, R ⁴ is a hydrogen atom, and R ⁵ is a hydrogen atom or a methyl group, the unsaturated monomer represented by the general formula (II) is a polyoxyalkylene mono (Meth) acrylamide, polyoxyalkylene mono (meth) allyl ether, polyoxyalkylene monovinyl ether, polyoxyalkylene mono (meth) acrylate, and the like, specifically, polyoxypropylene (poly) oxyethylene monoacrylamide, Polyoxypropylene (poly) oxyethylene monomethacrylamide, polyoxypropylene (poly) oxyethylene monoallyl ether, polyoxypropylene (poly) oxyethylene monomethallyl ether, polyoxypropylene (poly) oxyethylene monovinyl ether, polyoxypropylene Examples include len (poly) oxyethylene monoacrylate and polyoxypropylene (poly) oxyethylene monomethacrylate. Among them, polyoxypropylene (poly) oxyethylene monoacrylamide, polyoxypropylene (poly) oxyethylene monomethacrylamide, polyoxypropylene (poly) oxyethylene monoallyl ether are preferably used, and polyoxypropylene (poly) oxyethylene Monomethacrylamide and polyoxypropylene (poly) oxyethylene monoallyl ether are particularly preferably used.

When R ^{1 in the} above general formula (II) is an alkyl group having 1 to 8 carbon atoms, specifically, as the unsaturated monomer represented by the general formula (II), R ^{1 in the} general formula (II) is hydrogen. Examples include those in which the hydroxyl group at the terminal of the unsaturated monomer exemplified in the case of atoms is substituted with an alkoxy group having 1 to 8 carbon atoms. Among them, an unsaturated monomer in which a hydroxyl group at the terminal of polyoxypropylene (poly) oxyethylene monomethacrylamide or polyoxypropylene (poly) oxyethylene monoallyl ether is substituted with a methoxy group is preferably used. An unsaturated monomer in which the terminal hydroxyl group of (poly) oxyethylene monomethacrylamide is substituted with a methoxy group is particularly preferably used.

  The temperature when copolymerizing the unsaturated monomer represented by the general formula (II) and the vinyl ester monomer is not particularly limited, but is preferably 0 ° C. or higher and 200 ° C. or lower, and 30 ° C. or higher and 140 ° C. The following is more preferable. When the copolymerization temperature is lower than 0 ° C., it is difficult to obtain a sufficient polymerization rate. Moreover, when the temperature which superposes | polymerizes is higher than 200 degreeC, it is difficult to obtain POA modified PVA which has the POA group modification rate S prescribed | regulated by this invention. As a method for controlling the temperature employed in the copolymerization to 0 ° C. or more and 200 ° C. or less, for example, by controlling the polymerization rate, the heat generated by the polymerization is balanced with the heat released from the surface of the reactor. Examples thereof include a method and a method of controlling by an external jacket using an appropriate heat medium, but the latter method is preferable from the viewpoint of safety.

  The polymerization method employed for the copolymerization of the unsaturated monomer represented by the general formula (II) and the vinyl ester monomer is batch polymerization, semi-batch polymerization, continuous polymerization, or semi-continuous polymerization. Either of these may be used. As the polymerization method, an arbitrary method can be adopted from known methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. Among these, a bulk polymerization method or a solution polymerization method in which polymerization is performed in the absence of a solvent or in the presence of an alcohol solvent is preferably employed. For the purpose of producing a copolymer having a high degree of polymerization, an emulsion polymerization method is employed. As the alcohol solvent used in the bulk polymerization method or the solution polymerization method, methanol, ethanol, n-propanol or the like can be used, but is not limited thereto. These solvents can be used in combination of two or more.

  As the initiator used for copolymerization, conventionally known azo initiators, peroxide initiators, redox initiators and the like are appropriately selected according to the polymerization method. As the azo initiator, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4- Dimethyl valeronitrile) and the like, and peroxide initiators include perisopropyl compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate and diethoxyethyl peroxydicarbonate; t-butyl Perester compounds such as peroxyneodecanate, α-cumylperoxyneodecanate, and t-butylperoxydecanate; acetylcyclohexylsulfonyl peroxide; 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate, etc. Is mentioned. Furthermore, the initiator can be combined with potassium persulfate, ammonium persulfate, hydrogen peroxide, or the like to form an initiator. Moreover, as a redox-type initiator, what combined said peroxide and reducing agents, such as sodium hydrogen sulfite, sodium hydrogencarbonate, tartaric acid, L-ascorbic acid, Rongalite, is mentioned.

  In addition, when copolymerization of the unsaturated monomer represented by the general formula (II) and the vinyl ester monomer is performed at a high temperature, coloring of PVA caused by decomposition of the vinyl ester monomer, etc. May be seen. In that case, an antioxidant such as tartaric acid may be added to the polymerization system in an amount of 1 ppm to 100 ppm (with respect to the mass of the vinyl ester monomer) for the purpose of preventing coloring.

  Vinyl ester monomers used for copolymerization include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, vinyl caproate, vinyl caprylate, and lauric acid. Examples thereof include vinyl, vinyl palmitate, vinyl stearate, vinyl oleate, vinyl benzoate and the like. Of these, vinyl acetate is most preferred.

  When the unsaturated monomer represented by the above general formula (II) and the vinyl ester monomer are copolymerized, other monomers may be copolymerized within a range not impairing the gist of the present invention. Examples of monomers that can be used include α-olefins such as ethylene, propylene, n-butene, and isobutylene; acrylic acid and salts thereof; acrylic acid esters; methacrylic acid and salts thereof; methacrylic acid esters; acrylamide; -Methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid and its salt, acrylamidopropyldimethylamine and its salt or quaternary salt thereof, N-methylolacrylamide and its derivative, etc. Acrylamide derivatives; methacrylamide; N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and its salts, methacrylamidepropyldimethylamine and Methacrylamide derivatives such as salts thereof or quaternary salts thereof, N-methylol methacrylamide and derivatives thereof; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t- Vinyl ethers such as butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, 2,3-diacetoxy-1-vinyloxypropane; nitriles such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene chloride , Vinylidene halides such as vinylidene fluoride; allyl compounds such as allyl acetate, 2,3-diacetoxy-1-allyloxypropane, allyl chloride; maleic acid, itaconic acid, Examples thereof include unsaturated dicarboxylic acids such as fumaric acid and salts or esters thereof; vinylsilyl compounds such as vinyltrimethoxysilane; isopropenyl acetate and the like.

  In addition, for the purpose of adjusting the degree of polymerization of the resulting POA-modified vinyl ester polymer in the copolymerization of the unsaturated monomer represented by the general formula (II) and the vinyl ester monomer, Copolymerization may be carried out in the presence of a chain transfer agent as long as the gist of the present invention is not impaired. Chain transfer agents include aldehydes such as acetaldehyde and propionaldehyde; ketones such as acetone and methyl ethyl ketone; mercaptans such as 2-hydroxyethanethiol; halogenated hydrocarbons such as trichloroethylene and perchloroethylene; sodium phosphinate 1 Examples thereof include phosphinic acid salts such as hydrates, among which aldehydes and ketones are preferably used. The addition amount of the chain transfer agent can be determined according to the chain transfer constant of the chain transfer agent to be added and the degree of polymerization of the target vinyl ester polymer, but is generally 0 with respect to the vinyl ester monomer. .1% by mass to 10% by mass is desirable.

  For the saponification reaction of the POA-modified vinyl ester polymer, an alcohololysis reaction using a conventionally known basic catalyst such as sodium hydroxide, potassium hydroxide or sodium methoxide or an acidic catalyst such as p-toluenesulfonic acid or the like. Hydrolysis reactions can be applied. Examples of the solvent that can be used in this reaction include alcohols such as methanol and ethanol; esters such as methyl acetate and ethyl acetate; ketones such as acetone and methyl ethyl ketone; aromatic hydrocarbons such as benzene and toluene; These can be used alone or in combination of two or more. Among them, it is convenient and preferable to perform the saponification reaction using methanol or a methanol / methyl acetate mixed solution as a solvent and sodium hydroxide as a catalyst.

  The POA-modified PVA needs to have a POA group modification rate (S) of 0.05 mol% to 10 mol%, preferably 0.1 mol% to 5 mol%, preferably 0.15 mol% to 2 mol % Or less is more preferable. The POA group modification rate S is represented by the mole fraction of POA groups with respect to the total of monomer units constituting the POA-modified PVA. When the POA group modification rate S exceeds 10 mol%, the ratio of the POA groups contained in one molecule of the POA-modified PVA increases, so that the solubility of the PVA in water or a water-containing solvent decreases. On the other hand, when the POA group modification rate S is less than 0.05 mol%, the water solubility of the POA modified PVA is excellent, but the proportion of POA groups contained in one molecule of the POA modified PVA is low, The thickening due to the interaction and the storage stability of the composition to which the thickener of the present invention is added (emulsion, etc.) are not sufficiently exhibited. The POA group modification rate S is an unsaturated monomer having a POA group represented by the above general formula (I) in the side chain in the number of moles of all monomer units constituting the POA-modified PVA. It is the ratio (mol%) of the number of moles of the unit. The POA group modification rate S of the POA-modified PVA may be obtained from the POA-modified PVA or from the precursor POA-modified vinyl ester polymer, and both can be obtained by proton NMR.

In particular, when the POA-modified PVA is composed only of a vinyl alcohol unit, a vinyl ester unit, and a unit of an unsaturated monomer having a POA group represented by the above general formula (I) in the side chain, the POA group modification is performed by the following method. The rate S can be calculated. That is, for example, when obtaining from a POA-modified vinyl ester polymer, specifically, first, the reprecipitation purification of the POA-modified vinyl ester polymer is sufficiently performed three or more times using an n-hexane / acetone mixed solvent. After that, drying is performed under reduced pressure at 50 ° C. for two days to prepare a sample of POA-modified vinyl ester polymer for analysis. The sample is then dissolved in CDCl ₃ and measured at room temperature using proton NMR. And the area of the peak α (4.7 to 5.2 ppm) derived from the proton of the main chain methine of the vinyl ester monomer and the peak β (0.8 to 0.8 derived from the proton of the terminal methyl group of the oxypropylene unit) The POA group modification rate S can be calculated from the area of 1.0 ppm) using the following formula. In the formula, m represents the number of repeating units of the oxypropylene unit.

POA group modification rate S (mol%) = [(Area of peak β / 3 m) / {Area of peak α + (Area of peak β / 3 m)}] × 100

  The viscosity average polymerization degree (P) of the POA-modified PVA needs to be 200 or more and 5000 or less, preferably 1000 or more and 4500 or less, and more preferably 2500 or more and 4000 or less. When the viscosity average polymerization degree P of the POA-modified PVA exceeds 5000, the productivity of the POA-modified PVA is lowered and is not practical. Further, when the viscosity average polymerization degree P of the POA-modified PVA is less than 200, the temperature-sensitive thickening is not sufficiently exhibited.

The viscosity average polymerization degree P of the POA-modified PVA is measured according to JIS K6726. That is, after the POA-modified PVA is re-saponified and purified, it is obtained by the following equation from the intrinsic viscosity [η] (unit: deciliter / g) measured in water at 30 ° C.

Viscosity average polymerization degree P = ([η] × 10 ³ /8.29) ^{(1 / 0.62)}

  The saponification degree of the POA-modified PVA needs to be 40 mol% or more and 99.99 mol% or less, preferably 60 mol% or more and 99.5 mol% or less, and more preferably 70 mol% or more and 99 mol% or less. When the degree of saponification of the POA-modified PVA is less than 40 mol%, the water solubility of the POA-modified PVA is lowered, and the temperature-sensitivity is increased, and the composition (emulsion etc.) to which the thickener of the present invention is added is increased. Viscosity and storage stability are not fully developed. On the other hand, if the degree of saponification of the POA-modified PVA exceeds 99.99 mol%, the production of the POA-modified PVA becomes difficult, which is not practical. The saponification degree of the POA-modified PVA is a value that can be measured according to JIS K6726.

The POA-modified PVA has a viscosity η _{1 at} 20 ° C. and a viscosity η _{2 at} 60 ° C. when the viscosity of a 4% by mass aqueous solution of the POA-modified PVA is measured with a BL-type viscometer at a rotor rotational speed of 6 rpm. The ratio η ₂ / η ₁ is preferably 2.0 or more, more preferably 5.0 or more, further preferably 10 or more, and particularly preferably 100 or more. When the viscosity ratio η ₂ / η ₁ is less than 2.0, the interaction between POA groups is small, and the thickening accompanying POA modification may not be sufficiently exhibited. But not limited viscosity ratio η ₂ / η ₁ of the upper limit particularly, it is preferred that the viscosity ratio η ₂ / η ₁ is 2000 or less, more preferably 1000 or less.

  When the thickener of the present invention is water or a liquid thickener containing a water-containing solvent, the solvent other than water contained in the water-containing solvent includes alcohol solvents such as methanol and ethanol; methyl acetate Ester solvents such as ethyl acetate; ether solvents such as diethyl ether, 1,4-dioxane, methyl cellosolve, cellosolve, butyl cellosolve, MTBE (methyl tertiary butyl ether), butyl carbitol; ketones such as acetone and diethyl ketone Solvent: Glycol solvents such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol; diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether, 3-methoxy-3-methyl Examples include glycol ether solvents such as 1-butanol; glycol ester solvents such as ethylene glycol monomethyl ether acetate, PMA (propylene glycol monomethyl ether acetate), diethylene glycol monobutyl ether acetate, and diethylene glycol monoethyl ether acetate. Is not to be done.

  In the case of the liquid thickener, the content of the POA-modified PVA in the thickener is preferably 10 parts by weight or more and 70 parts by weight or less, and preferably 10 parts by weight or more and 40 parts by weight or less with respect to 100 parts by weight of the solvent. Less than the mass part is more preferable. The method for preparing the liquid thickener is not particularly limited. For example, the liquid thickener can be obtained by adding the POA-modified PVA to water or a water-containing solvent and mixing them by heating.

  The thickener of the present invention may further contain a plasticizer, a surfactant, an antifoaming agent, an ultraviolet absorber, and the like as long as the gist of the present invention is not impaired.

  In addition, the thickener of the present invention is not limited to other water-soluble polymers such as various PVA, starch, carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose and the like as long as they do not impair the spirit of the present invention. It may contain. The content of such other water-soluble polymer is preferably 50 parts by mass or less with respect to 100 parts by mass of the POA-modified PVA.

  The thickener of the present invention containing the above-mentioned POA-modified PVA has excellent thickening particularly in a temperature range higher than room temperature, and the composition having the thickener has a case where the temperature in summer increases. Stable storage stability performance is exhibited. Therefore, it can be suitably used as a thickener used in aqueous solutions and aqueous emulsions such as paints, paints, cement, concrete, paper coatings, binders, adhesives and cosmetics.

[Composition]
The composition which is another aspect of the present invention contains the above thickener of the present invention, oil and water. The composition can be obtained by mixing the thickener, oil and water of the present invention by a conventional method. Specifically, the premixed oil and water are added to the thickener. The method is preferred. The oil component is preferably a water-dispersible resin that can be dispersed in water. Examples of the water-dispersible resin include homopolymers or copolymers of olefinically unsaturated monomers. Specifically, polyacrylate, polyvinyl acetate, polyurethane, polyester, ethylene-vinyl acetate copolymer, IR (cis -1,4-polyisoprene), SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), CR (chloroprene rubber), VP (styrene-butadiene rubber copolymerized with 2-vinylpyridine monomer), MBR ( Methyl acrylate-butadiene copolymer) and the like. That is, examples of the composition include an aqueous dispersion of an olefinically unsaturated monomer alone or a copolymer, and specifically, a polyacrylate aqueous dispersion, a polyvinyl acetate aqueous dispersion, a polyurethane. And aqueous polyester dispersions and polyester aqueous dispersions. The content of the POA-modified PVA in the composition is preferably 0.1 parts by mass or more and 50 parts by mass or less, and more preferably 0.3 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the oil content. .

  Hereinafter, the present invention will be described in detail by way of examples and comparative examples. In the following Examples and Comparative Examples, “part” and “%” mean mass basis unless otherwise specified.

  The PVA obtained by the following production examples was evaluated according to the following method.

[Viscosity average polymerization degree P and degree of saponification of PVA]
The viscosity average polymerization degree P and saponification degree of PVA were determined by the method described in JIS K6726.

[POA group modification rate S of PVA]
The POA group modification rate S of PVA was determined according to the method using proton NMR described above. For proton NMR, JEOL GX-500 (500 MHz) was used.

[Production Example 1: Production of PVA1]
A 3 L reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet, a monomer dropping port and an initiator addition port was added to 900 g of vinyl acetate, 100 g of methanol, and a single monomer that is an unsaturated monomer having a POA group. Monomer A (monomer A is represented by general formula (II), R ^{1 to} R ⁵ , X, m and n are as shown in Table 2) 3.7 g was charged while nitrogen bubbling was performed. The system was purged with nitrogen for a minute. Further, a monomer solution in which the monomer A was dissolved in methanol to a concentration of 20% was prepared as a delay solution, and nitrogen substitution was performed by bubbling nitrogen gas. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., 0.25 g of 2,2′-azobisisobutyronitrile (AIBN) was added to initiate polymerization. While the delay solution was added dropwise so that the monomer composition (ratio of vinyl acetate and monomer A) in the polymerization solution was constant, polymerization was performed at 60 ° C. for 3 hours, and then the polymerization was stopped by cooling. The total amount of comonomer solution added until the polymerization was stopped was 17 g. Further, the solid content concentration when the polymerization was stopped was 26.2%. Subsequently, unreacted vinyl acetate monomer was removed while occasionally adding methanol at 30 ° C. under reduced pressure to obtain a methanol solution (concentration 35%) of POA-modified vinyl ester polymer (POA-modified PVAc). Furthermore, 14.0 g of alkaline solution (10% methanol solution of sodium hydroxide) was added to 386 g of POA-modified PVAc methanol solution prepared by adding methanol to this solution (100.0 g of POA-modified PVAc in the solution). (POA modified PVAc concentration in saponification solution 25%, molar ratio of sodium hydroxide to vinyl acetate unit in POA modified PVAc 0.03). A gel-like product was formed in about 1 minute after the addition of the alkaline solution. This was pulverized with a pulverizer and allowed to stand at 40 ° C. for 1 hour to proceed with saponification, and then 500 g of methyl acetate was added to leave the remaining alkali. Neutralized. After confirming that the neutralization was completed using a phenolphthalein indicator, a white solid was obtained by filtration, 2000 g of methanol was added thereto, and the mixture was allowed to stand and washed at room temperature for 3 hours. After the above washing operation was repeated three times, the white solid obtained by centrifugal drainage was left to dry in a dryer at 65 ° C. for 2 days to obtain POA-modified PVA (PVA1). PVA1 had a viscosity average polymerization degree P of 3000, a saponification degree of 98 mol%, and a POA group modification rate S of 0.2 mol%.

[Production Examples 2-15, 18-24, 26, 27: Production of PVA2-15, 18PVAi-vii, ix]
Charge amount of vinyl acetate and methanol (before the start of polymerization), kind of unsaturated monomer having POA group used during polymerization (Table 2) and its use amount, polymerization rate, concentration of POA-modified PVAc during saponification, acetic acid Various POA-modified PVA (PVA2-15, PVAi-vii, ix) were prepared in the same manner as in Production Example 1 except that the molar ratio of sodium hydroxide to vinyl unit was changed as shown in Tables 1 and 2. Obtained. Table 3 shows the viscosity average polymerization degree P, POA group modification rate S, and saponification degree of these POA-modified PVA.

[Production Example 16: Production of PVA 16]
Monomer I which is an unsaturated monomer having 850 g of vinyl acetate, 150 g of methanol and POA group was added to a 3 L reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and an initiator addition port. The body I was represented by the general formula (II), and 42 g of R ^{1 to} R ⁵ , X, m and n were as shown in Table 2), and the system was purged with nitrogen for 30 minutes while carrying out nitrogen bubbling. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., 0.25 g of 2,2′-azobisisobutyronitrile (AIBN) was added to start polymerization, and polymerization was performed at 60 ° C. for 3 hours. Then, the polymerization was stopped by cooling. The solid content concentration when the polymerization was stopped was 25.5%. Subsequently, unreacted vinyl acetate monomer was removed while occasionally adding methanol at 30 ° C. under reduced pressure to obtain a methanol solution (concentration 30%) of POA-modified vinyl ester polymer (POA-modified PVAc). Furthermore, 16.7 g of an alkaline solution (10% methanol solution of sodium hydroxide) was added to 463.2 g of a methanol solution of POA-modified PVAc prepared by adding methanol thereto (120.0 g of POA-modified PVAc in the solution). Saponification was carried out (POA modified PVAc concentration in saponified solution 25%, molar ratio of sodium hydroxide to vinyl acetate units in POA modified PVAc 0.03). A gel-like product was formed in about 1 minute after the addition of the alkaline solution. This was pulverized with a pulverizer and allowed to stand at 40 ° C. for 1 hour to proceed with saponification. Neutralized. After confirming that the neutralization was completed using a phenolphthalein indicator, a white solid was obtained by filtration, 2000 g of methanol was added thereto, and the mixture was allowed to stand at room temperature for 3 hours and washed. After the above washing operation was repeated three times, the white solid obtained by centrifugal drainage was left to dry in a dryer at 65 ° C. for 2 days to obtain POA-modified PVA (PVA16). PVA16 had a viscosity average polymerization degree P of 2400, a saponification degree of 98 mol%, and a POA group modification rate S of 0.2 mol%.

[Production Examples 17 and 25: Production of PVA17 and PVAviii]
Various POA-modified PVA (PVA17) were produced in the same manner as in Production Example 16 except that the type (Table 2) and the amount of unsaturated monomer having a POA group used during polymerization were changed as shown in Table 1. , PVAviii) was obtained. Table 3 shows the viscosity average polymerization degree P, POA group modification rate S, and saponification degree of these POA-modified PVA.

[Production Examples 28 and 29: Production of PVAx and PVAxi]
An unsaturated monomer (compound III or IV) having a POA group having the following structure was used at the time of polymerization, and the amount used and the amounts of vinyl acetate and methanol (before polymerization started) were changed as shown in Table 1. Except for this, various modified PVA (PVAx, PVAxi) were obtained in the same manner as in Production Example 1. Table 3 shows the viscosity average polymerization degree P, POA group modification rate S, and saponification degree of these POA-modified PVA.

(In compound III, the oxypropylene unit and the oxyethylene unit are each arranged in a block form, and the positions of the polyoxyethylene block and the polyoxypropylene block are as described in the above formula.)

(The oxypropylene units and oxyethylene units in Compound IV are randomly arranged.)

[Production Example 30: Production of PVAxii]
700 g of vinyl acetate and 300 g of methanol were charged into a 3 L reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and an initiator addition port, and the system was purged with nitrogen for 30 minutes while bubbling nitrogen. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., 0.25 g of 2,2′-azobisisobutyronitrile (AIBN) was added to start polymerization, and polymerization was performed at 60 ° C. for 3 hours. Then, the polymerization was stopped by cooling. The solid content concentration when the polymerization was stopped was 17.0%. Subsequently, unreacted vinyl acetate monomer was removed while occasionally adding methanol under reduced pressure at 30 ° C. to obtain a methanol solution (concentration 30%) of an unmodified vinyl ester polymer (unmodified PVAc). Furthermore, 16.7 g of an alkaline solution (10% methanol solution of sodium hydroxide) was added to 463.2 g of methanol solution of unmodified PVAc prepared by adding methanol to this (120.0 g of unmodified PVAc in the solution). Saponification was carried out (25% unmodified PVAc concentration in the saponified solution, 0.03 molar ratio of sodium hydroxide to vinyl acetate units in the unmodified PVAc). A gel-like product was formed in about 1 minute after the addition of the alkaline solution. This was pulverized with a pulverizer and allowed to stand at 40 ° C. for 1 hour to proceed with saponification, and then 500 g of methyl acetate was added to leave the remaining alkali. Neutralized. After confirming that the neutralization was completed using a phenolphthalein indicator, a white solid was obtained by filtration, 2000 g of methanol was added thereto, and the mixture was allowed to stand at room temperature for 3 hours and washed. After the above washing operation was repeated three times, the white solid obtained by centrifugal drainage was left to dry in a dryer at 65 ° C. for 2 days to obtain unmodified PVA (PVAxii). PVAxii had a viscosity average polymerization degree P of 1700 and a saponification degree of 98 mol%.

[Production Example 31: Production of PVAxiii]
Into a 3 L reactor equipped with a stirrer, reflux condenser, nitrogen inlet, monomer dropping port and initiator addition port, 800 g of vinyl acetate, 200 g of methanol, and 5 g of 1-hexadecene were charged, and nitrogen bubbling was performed. Then, the system was purged with nitrogen for 30 minutes. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., 2.8 g of 2,2′-azobisisobutyronitrile (AIBN) was added to initiate polymerization. After polymerization at 60 ° C. for 2 hours, the polymerization was stopped by cooling. The solid content concentration when the polymerization was stopped was 32.5%. Subsequently, unreacted vinyl acetate monomer was removed while occasionally adding methanol under reduced pressure at 30 ° C. to obtain a methanol solution (concentration 35%) of an alkyl-modified vinyl ester polymer (alkyl-modified PVAc). Furthermore, 16.7 g of an alkaline solution (10% methanol solution of sodium hydroxide) was added to 453.4 g of an alkyl-modified PVAc methanol solution prepared by adding methanol thereto (100.0 g of the alkyl-modified PVAc in the solution). Saponification was carried out (concentration of alkyl-modified PVAc in saponification solution 20%, molar ratio of sodium hydroxide to vinyl acetate unit in alkyl-modified PVAc 0.03). A gel-like product was formed in about 1 minute after the addition of the alkaline solution. This was pulverized with a pulverizer and allowed to stand at 40 ° C. for 1 hour to proceed with saponification, and then 500 g of methyl acetate was added to leave the remaining alkali. Neutralized. After confirming that the neutralization was completed using a phenolphthalein indicator, a white solid was obtained by filtration, 2000 g of methanol was added thereto, and the mixture was allowed to stand at room temperature for 3 hours and washed. After the above washing operation was repeated three times, the white solid obtained by centrifugal drainage was left to dry in a dryer at 65 ° C. for 2 days to obtain alkyl-modified PVA (PVAxiii). PVAxiii had a viscosity average polymerization degree P of 1700, a saponification degree of 98 mol%, and an alkyl modification rate of 0.3 mol%.

[Examples 1-18, Comparative Examples 1-13]
Each PVA (PVA1-18, PVAi-xiii) obtained by manufacture examples 1-31 was used as a thickener of Examples 1-18 and Comparative Examples 1-13, and the following evaluation was performed. Moreover, the composition containing this thickener was evaluated by the following method. The evaluation results are shown in Table 3.

[Thickening (viscosity of PVA aqueous solution)]
A PVA aqueous solution having a concentration of 4% was prepared, and the viscosity η ₂ at a temperature of 60 ° C. was measured at a rotor rotation speed of 6 rpm using a BL type viscometer. The viscosity η ₁ was measured under the same conditions except that the temperature was changed to 20 ° C., and the viscosity ratio η ₂ / η ₁ between the viscosity η _{2 at} 60 ° C. and the viscosity η _{1 at} 20 ° C. was determined.

[Thickening (thickening test of ethylene-vinyl acetate copolymer emulsion)]
100 parts of an ethylene-vinyl acetate copolymer emulsion (OM-4200NT manufactured by Kuraray Co., Ltd., concentration 55%) and 11.0 parts of a 10% concentration PVA aqueous solution (the solid content of PVA is 2 parts per 100 parts of emulsion solids). 0.0 part) and 1.2 parts of water were added to prepare a mixed aqueous solution of PVA and emulsion having a concentration of 50%, and the viscosity at a rotor speed of 6 rpm and a temperature of 40 ° C. was measured using a BL type viscometer, Judgment was made according to the following criteria.
A: 10,000 mPa · s or more B: 7,000 mPa · s or more and less than 10,000 mPa · s C: 5,000 mPa · s or more and less than 7,000 mPa · s D: 3,000 mPa · s or more and less than 5,000 mPa · s E: Less than 3,000 mPa · s

[Storage stability of ethylene-vinyl acetate copolymer emulsion (Em)]
The emulsion used for the thickening test was stored in a dryer at 50 ° C., the number of days when the emulsion layer and the aqueous layer were separated was observed, and judged according to the following criteria.
A: 30 days or more B: 15 days or more and less than 30 days C: 7 days or more and less than 15 days D: 3 days or more and less than 7 days E: Less than 3 days

  From the evaluation results of Table 3, the thickener of the present invention is excellent in viscosity increase, particularly in a temperature range higher than room temperature, and is excellent in temperature-sensitive viscosity increase in which the viscosity of the solution increases as the temperature of the solution increases. Furthermore, it can be seen that compositions (emulsions, etc.) obtained by further adding the thickener are excellent in storage stability, particularly in a temperature range higher than room temperature (Examples 1 to 17). Therefore, even under high temperatures such as in summer, the composition is excellent in thickening and storage stability of emulsions and the like. On the other hand, when the viscosity average polymerization degree P, POA group modification rate S or saponification degree of the POA-modified PVA contained in the thickener does not satisfy the prescribed range (Comparative Examples 1 to 4), the POA group has a prescribed structure. (Comparative Examples 5 to 13), the thickening of the thickener in a temperature region higher than room temperature decreases, or the storage stability of a composition such as an emulsion obtained by adding the thickener It can be seen that decreased.

  As described above, since the thickener of the present invention contains a specific POA-modified PVA, it is excellent in thickening, particularly in a temperature range higher than room temperature, and further contains the thickener. Compositions such as emulsions are excellent in storage stability. Therefore, the thickener of the present invention is suitably used as a thickener for various emulsions and paints.

Claims (4)

A thickener containing a polyoxyalkylene-modified vinyl alcohol polymer,
The polyoxyalkylene-modified vinyl alcohol polymer has a polyoxyalkylene group represented by the following general formula (I) composed of a polyoxypropylene block and a (poly) oxyethylene block in the side chain, and has a viscosity average Thickener having a polymerization degree P of 200 or more and 5000 or less, a saponification degree of 40 mol% or more and 99.99 mol% or less, and a polyoxyalkylene group modification rate S of 0.05 mol% or more and 10 mol% or less. .

(In formula (I), R ¹ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ^One of R ² and R ³ is a methyl group, and the other is a hydrogen atom. 10 ≦ m ≦ 40 and 1 ≦ n ≦ 50.) When the viscosity of a 4% by mass aqueous solution of the polyoxyalkylene-modified vinyl alcohol polymer was measured with a BL type viscometer under the condition that the rotor rotation speed was 6 rpm, the viscosity η _{1 at} 20 ° C. and the viscosity η _{2 at} 60 ° C. The thickener according to claim 1, wherein the ratio η ₂ / η ₁ is 2.0 or more.   Furthermore, the thickener of Claim 1 or 2 containing water or a water containing solvent.   It is a composition containing the thickener in any one of Claims 1-3, oil content, and water, Comprising: 0.1 mass part of said polyoxyalkylene modified vinyl alcohol-type polymers with respect to 100 mass parts of oil content A composition containing 50 parts by mass or less.