WO2023190884A1

WO2023190884A1 - Aqueous solution, coating gent, adhesive, paper processing agent, dispersant for emulsion polymerization, aqueous emulsion, multilayer body and method for producing aqueous emulsion

Info

Publication number: WO2023190884A1
Application number: PCT/JP2023/013207
Authority: WO
Inventors: 美鈴藤森; 依理子今岡
Original assignee: 株式会社クラレ
Priority date: 2022-03-31
Filing date: 2023-03-30
Publication date: 2023-10-05

Abstract

The purpose of the present invention is to provide an aqueous solution which is configured such that the aqueous solution itself or coated paper or the like obtained using the aqueous solution is excellent in terms of storage stability, coatability, air resistance, silicone curability, adhesion between a release layer and a base material, initial adhesion and water-resistant adhesion. The present invention provides an aqueous solution which contains a vinyl alcohol polymer that comprises a carbonyl group, a formyl group and an alkenyl group in a same molecule or in different molecules.

Description

Aqueous solutions, coating agents, adhesives, paper processing agents, dispersants for emulsion polymerization, aqueous emulsions, laminates, and methods for producing aqueous emulsions

The present invention relates to an aqueous solution, a coating agent, an adhesive, a paper processing agent, a dispersant for emulsion polymerization, an aqueous emulsion, a laminate, and a method for producing an aqueous emulsion.

Vinyl alcohol polymer (hereinafter also referred to as "PVA") is known as a water-soluble synthetic polymer, and in addition to being used as a raw material for fibers and films, it is also used as a paper processing agent, fiber processing agent, and inorganic material. It is widely used as a binder, adhesive, stabilizer for emulsion polymerization and suspension polymerization, etc. In particular, coating agents based on PVA are used as paper processing agents. By coating paper with PVA, which has excellent film-forming properties, it is possible to impart barrier properties against gas and oil resistance.

Paper coated with PVA is sometimes used as barrier paper, and release paper base paper is a typical example of barrier paper. Release paper base paper is usually manufactured by coating the surface of a cellulose base material with PVA. A release paper is obtained by forming a release layer (silicone layer) on the surface of this release paper base paper. PVA in release paper plays the role of a filler that suppresses the penetration of expensive silicone and platinum into the base material. Recently, there has been a demand for a release paper base paper that, in addition to such sealing properties, can accelerate the curing of the silicone in the release layer and improve the adhesion between the PVA layer and the silicone layer.

Patent Document 1 describes a cellulose base material coated with PVA in which double bonds have been introduced into the side chains through an acetalization reaction. Usually, the acetalization reaction is carried out in water under acidic conditions, and a basic compound is added to perform a neutralization treatment. When this reaction solution is used as a coating agent, the solution stability of the coating agent is low due to a large amount of salt generated by the neutralization treatment.

Patent Document 2 describes a release base paper in which a base material is coated with a coating agent containing PVA in which a double bond is introduced into the side chain by an esterification reaction. However, the pyridine used in the esterification reaction may remain in the PVA and act as a catalyst poison, inhibiting the silicone curing reaction of the release layer.

Patent Document 3 describes a peeling method in which a coating agent containing PVA having a double bond in a side chain, which is obtained by esterifying PVA with a carboxylic acid having an unsaturated double bond or a salt thereof, is applied to a base material. The original paper is listed. When this coating agent is applied to the release base paper, it has excellent sealing properties for the silicone on the release base paper, accelerates the curing of the silicone in the release layer, and improves the adhesion between the base material and the release layer. has been done. However, since the PVA having a double bond in the side chain described in Patent Document 3 also contains components that are insoluble in water, the coating property is insufficient when used as a coating liquid.

Furthermore, adhesives containing PVA as a main component are inexpensive and have excellent adhesive properties, and are used for bonding paperboard, corrugated paper, paper tubes, sliding doors, wallpaper, wood, etc. Furthermore, adhesives made by mixing various emulsions and PVA are used as adhesives for woodworking, textile processing, paper, and the like. As described above, adhesives containing PVA (PVA-based water-based adhesives) are used in a wide range of applications. However, even in PVA-based water-based adhesives, in order to respond to the recent trend toward high-speed coating, it has been proposed to use various modified PVAs for the purpose of improving adhesive properties including initial adhesion.

As such modified PVA, Patent Document 4 describes alkyl-modified PVA. A PVA-based water-based adhesive using this modified PVA is said to have excellent initial adhesion, water-resistant adhesion, and storage stability of the adhesive. However, the water-resistant adhesion of adhesives using such modified PVA is insufficient.

Patent Document 5 describes aldehyde-modified PVA. Adhesives containing this modified PVA are said to be excellent in initial adhesive strength, normal adhesive strength, durable adhesive strength, and storage stability of the main agent. However, even in adhesives using such modified PVA, there is room for improvement in initial adhesive strength, and the effects when no curing agent is used are not disclosed.

PVA is also known as a protective colloid for emulsion polymerization of vinyl ester monomers typified by vinyl acetate. Aqueous emulsions obtained by emulsion polymerization using PVA as a dispersant for emulsion polymerization are widely used in the fields of various adhesives, paint bases, various binders for impregnated paper and nonwoven products, and various coating agents. There is.

Aqueous emulsions synthesized using PVA as a dispersant for emulsion polymerization have (a) excellent adhesion to substrates without migration of low-molecular components, and (b) easy viscosity adjustment and good coating properties. It has good suitability for coating applications. On the other hand, in such aqueous emulsions, the monomers that can usually be used are limited to vinyl acetate and vinyl chloride, which have high radical reactivity, and there are problems with conventional aqueous emulsions that use only surfactants as dispersion stabilizers. In comparison, improvements are expected in terms of insufficient physical properties such as water resistance, oil resistance, mechanical stability, and freeze-thaw stability.

In response to this point, Patent Document 6 describes a technique for improving dispersibility by introducing a sulfone group into PVA, which is a dispersant. However, in emulsions produced by such methods, PVA is often physically adsorbed to the polymer in the emulsion, and physical properties such as polymerization stability and mechanical stability may be insufficient.

Patent Document 7 discloses that a polymer of ethylenically unsaturated monomers such as acrylic monomers, styrene monomers, and diene monomers is dispersed using PVA containing diacetone acrylamide units as a dispersant. Aqueous emulsions are described. Although such PVA has excellent polymerization stability and mechanical stability, it is necessary to add a crosslinking agent separately in order to exhibit required physical properties such as water resistance and oil resistance.

Additionally, a method has been proposed in which a graft reaction between PVA and dispersoids is promoted to obtain an aqueous emulsion having desired physical properties. Patent Document 8 describes the use of a polyvinyl alcohol polymer having a mercapto group at the molecular end as a dispersant for emulsion polymerization. However, such PVA is synthesized by chain transfer polymerization, and a mixture of PVA with mercapto groups and PVA without mercapto groups is obtained, so the degree of polymerization and the rate of introduction of mercapto groups, etc. There are limitations to the molecular design of

Special Publication No. 2013-531136 International Publication 2009/147283 International Publication 2018/124241 International Publication 2011/155546 Japanese Patent Application Publication No. 2006-52245 Japanese Unexamined Patent Publication No. 50-155579 Japanese Patent Application Publication No. 2001-220409 Japanese Patent Application Publication No. 2003-171567

The present invention provides that an aqueous solution containing a vinyl alcohol polymer or a coated paper produced using the aqueous solution has storage stability, coatability, air permeation resistance, silicone curability, release layer and base material. The primary objective is to provide an aqueous solution that has excellent adhesion, initial adhesion, and water-resistant adhesion, and coating agents, adhesives, and paper processing agents containing such an aqueous solution.
Furthermore, the present invention provides a dispersant for emulsion polymerization that is capable of synthesizing an aqueous emulsion that has excellent mechanical stability, produces little aggregates, and can produce coated paper and the like that have excellent oil resistance. A second object of the present invention is to provide an aqueous emulsion containing such a dispersant for emulsion polymerization, a method for producing the same, and a laminate.

The purpose is
[1] An aqueous solution containing a vinyl alcohol polymer having a carbonyl group, a formyl group, and an alkenyl group in the same or different molecules;
[2] The aqueous solution of [1], wherein the vinyl alcohol polymer has a structure represented by the following formula (1) containing the carbonyl group;

In formula (1), m is an integer from 1 to 11.
[3] An aqueous solution containing a vinyl alcohol polymer having a group represented by the following formula (2) at the end of the polymer chain;

In formula (2), R ¹ is an alkenyl group.
[4] The aqueous solution of [3], wherein the alkenyl group represented by R ¹ in the formula (2) has a methylene group at the end on the carbonyl group side;
[5] The aqueous solution of any one of [1] to [4], wherein the vinyl alcohol polymer has a tertiary carbon atom;
[6] The aqueous solution of any one of [1] to [5], wherein the vinyl alcohol polymer has a structural unit derived from an aliphatic unsaturated aldehyde;
[7] The aqueous solution of [6], wherein the aliphatic unsaturated aldehyde has 3 to 14 carbon atoms;
[8] The aqueous solution of [6] or [7], wherein the aliphatic unsaturated aldehyde has a carbon-carbon double bond at the end;
[9] The aqueous solution according to any one of [1] to [8], wherein the concentration of the vinyl alcohol polymer is 0.5% by mass or more and 30% by mass or less;
[10] A coating agent containing the aqueous solution of any one of [1] to [9];
[11] An adhesive containing the aqueous solution of any one of [1] to [9];
[12] A paper processing agent containing the aqueous solution of any one of [1] to [9];
[13] A dispersant for emulsion polymerization containing a vinyl alcohol polymer having a carbonyl group, a formyl group, and an alkenyl group in the same or different molecules;
[14] The dispersant for emulsion polymerization according to [13], wherein the vinyl alcohol polymer has a structure represented by the following formula (1) containing the carbonyl group;

In formula (1), m is an integer from 1 to 11.
[15] A dispersant for emulsion polymerization containing a vinyl alcohol polymer having a group represented by the following formula (2) at the end of the polymer chain;

In formula (2), R ¹ is an alkenyl group.
[16] The dispersant for emulsion polymerization according to [15], wherein the alkenyl group represented by R ¹ in the formula (2) has a methylene group at the end on the carbonyl group side;
[17] The dispersant for emulsion polymerization according to any one of [13] to [16], wherein the vinyl alcohol polymer has a tertiary carbon atom;
[18] The dispersant for emulsion polymerization according to any one of [13] to [17], wherein the vinyl alcohol polymer has a structural unit derived from an aliphatic unsaturated aldehyde;
[19] The dispersant for emulsion polymerization according to [18], wherein the aliphatic unsaturated aldehyde has 3 to 14 carbon atoms;
[20] The dispersant for emulsion polymerization according to [18] or [19], wherein the aliphatic unsaturated aldehyde has a carbon-carbon double bond at the end;
[21] The dispersant for emulsion polymerization according to any one of [13] to [20], wherein the vinyl alcohol polymer has a saponification degree of 80 mol% or more;
[22] A polymer containing a structural unit derived from at least one selected from the group consisting of ethylenically unsaturated monomers and diene monomers, and the dispersion for emulsion polymerization of any one of [13] to [21] an aqueous emulsion containing an agent;
[23] The aqueous compound of [22], wherein the ethylenically unsaturated monomer is at least one selected from the group consisting of styrene monomers, acrylic ester monomers, and methacrylic ester monomers. Emulsion;
[24] A laminate comprising a base material and a layer formed from the aqueous emulsion of [22] or [23];
[25] The laminate of [24], wherein the base material is paper.
[26] A laminate comprising a base material and a layer containing the emulsion polymerization dispersant according to any one of [13] to [21];
[27] At least one monomer selected from the group consisting of ethylenically unsaturated monomers and diene monomers in the presence of the emulsion polymerization dispersant according to any one of [13] to [21]. A method for producing an aqueous emulsion, including a step of emulsion polymerization;
[28] The ethylenically unsaturated monomer is at least one monomer selected from the group consisting of styrene monomers, acrylic ester monomers, and methacrylic ester monomers, [27] ] Method for producing an aqueous emulsion;
This is achieved by providing

The aqueous solution of the present invention or coated paper produced using the aqueous solution has storage stability, coatability, air permeation resistance, silicone curability, adhesion between the release layer and the base material, initial adhesion, and Excellent water-resistant adhesion. Therefore, the aqueous solution is suitably used for coating agents, adhesives, paper processing agents, and the like.
The dispersant for emulsion polymerization of the present invention is an aqueous emulsion with excellent mechanical stability and little generation of aggregates, and is capable of synthesizing an aqueous emulsion that can produce coated paper etc. with excellent oil resistance. can. Therefore, the obtained aqueous emulsion is suitably used for various adhesives, paints, various binders, admixtures, coating agents, laminates, etc.

In this specification, a numerical range described using "~" means that the numerical values described before and after "~" are included as lower and upper limits.

<Aqueous solution according to the first form>
The aqueous solution according to the first aspect of the present invention contains a vinyl alcohol polymer (PVA) having a carbonyl group, a formyl group, and an alkenyl group in the same or different molecules, and water. The aqueous solution itself or coated paper produced using the aqueous solution has storage stability, coating properties, air permeation resistance, silicone curability, adhesion between the release layer and the base material, initial adhesion, and water resistance. Excellent adhesion.

The aqueous solution may contain a solvent other than water, such as an organic solvent. The proportion of water in the solvent in the aqueous solution is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and 95% by mass or more based on the total amount of the solvent. In some cases, it is even more preferable. Further, the proportion of water in the solvent in the aqueous solution may be 100% by mass or less, or 99% by mass or less. Further, it is preferable that the solvent in the aqueous solution consists essentially of water.

Although there is no particular restriction on the lower limit of the concentration of the PVA contained in the aqueous solution, for example, 0.5% by mass is preferred, 1% by mass is more preferred, 2% by mass is still more preferred, and even more preferably 4% by mass. be. Further, there is no particular restriction on the upper limit of the concentration of the PVA contained in the aqueous solution, but for example, 30% by mass is preferable, 25% by mass is more preferable, and 20% by weight may be even more preferable. When the concentration of the PVA in the aqueous solution is within the above range, coating efficiency is improved and high-speed coating properties are better.

The upper limit of the insoluble content in the aqueous solution is preferably 1000 ppm, more preferably 500 ppm, even more preferably 200 ppm, even more preferably 100 ppm, particularly preferably 70 ppm, more particularly preferably 50 ppm, and even more particularly preferably 10 ppm. Further, the lower limit of the insoluble content in the aqueous solution is preferably 0 ppm, and may be 1 ppm. This undissolved portion may be an undissolved portion of PVA. Note that the insoluble content in the aqueous solution is the mass ratio of the component remaining dissolved in the aqueous solution to the total amount of PVA contained in the aqueous solution, and is specifically measured by the following method.

The aqueous solution is passed through a metal filter with an opening of 63 μm, and the filter is further washed with warm water at 90° C. to obtain solids that remain undissolved in the aqueous solution. The ratio of the mass of undissolved solids to the mass of PVA contained in the aqueous solution before filtration is calculated, and this is defined as the undissolved content in the aqueous solution.

The aqueous solution may contain other solutes than the PVA. Other solutes include water-soluble resins other than the PVA, surfactants, salts, and the like. However, the lower limit of the content of PVA with respect to all solutes contained in the aqueous solution is preferably 70% by mass, more preferably 80% by mass, even more preferably 90% by mass, 95% by mass, 99% by mass, or 99.9% by mass. In some cases, mass % is even more preferable. The upper limit of the content of PVA with respect to all solutes contained in the aqueous solution may be 100% by mass, 99.9% by mass, 99% by mass, or 95% by mass.

The aqueous solution is suitable for coating agents, adhesives, paper processing agents, etc. The method for producing the aqueous solution is not particularly limited. For example, it can be obtained by dissolving solid PVA in a solvent such as water.

<Vinyl alcohol polymer>
As mentioned above, PVA contained in the aqueous solution according to the first embodiment of the present invention has a carbonyl group, a formyl group, and an alkenyl group in the same or different molecules. The same applies to PVA contained in the dispersant for emulsion polymerization according to the first embodiment of the present invention, which will be described later. Hereinafter, the case where the PVA is used as a dispersant for emulsion polymerization will also be explained. The PVA does not need to contain all of the carbonyl group, formyl group, and alkenyl group in one molecule. That is, the PVA may be, for example, a mixture of PVA (a) having two groups out of a carbonyl group, a formyl group, and an alkenyl group, and PVA (b) having the remaining one group. At this time, both PVA (a) and PVA (b) may have one or more of a carbonyl group, a formyl group, and an alkenyl group. The PVA may be a mixture of three or more types of PVA. In addition, there are two forms of PVA that have all of a carbonyl group, a formyl group, and an alkenyl group in one molecule, and a form that is a mixture of multiple types of PVA and in which this mixture has a carbonyl group, a formyl group, and an alkenyl group. have substantially similar properties, and it is generally extremely difficult to distinguish these two forms by analysis or the like.

The PVA is a polymer having vinyl alcohol units as structural units. Usually, the PVA is obtained by polymerizing a vinyl ester in the presence of an aliphatic unsaturated aldehyde and saponifying the obtained vinyl ester polymer, as will be described in detail later. The lower limit of the degree of saponification of the PVA is not particularly limited, but may be, for example, 20 mol%, 30 mol%, or 40 mol%. The lower limit of the degree of saponification of the PVA is preferably 65 mol%, more preferably 70 mol%, even more preferably 75 mol%, and even more preferably 80 mol%. Furthermore, the lower limit of the degree of saponification of the PVA may be even more preferably 82 mol%, 90 mol%, or 92 mol%. When the degree of saponification of PVA is equal to or higher than the above lower limit, the solubility of the PVA in water is improved, the uniformity of the film surface coated with the aqueous solution is improved, the filling property of silicone is improved, and Adhesive strength is further increased. On the other hand, the upper limit of the degree of saponification of the PVA is not particularly limited and may be 100 mol%, but for example, 99.99 mol% is preferable, 99.5 mol% is more preferable, and 99 mol% is still more preferable. In some cases. Furthermore, the upper limit of the degree of saponification may be even more preferably 98 mol% or 96 mol%. When the degree of saponification of the PVA is less than or equal to the upper limit, the production of PVA becomes easy. In addition, since the degree of saponification of the PVA is within the above range, when the PVA is used as a dispersant for emulsion polymerization, the surfactant performance is optimized, and various performances of the resulting aqueous emulsion ( It has fewer coarse particles, has excellent storage stability, has appropriate water resistance, etc.). The degree of saponification is a value measured by the method described in JIS K6726:1994.

The carbonyl group (-C(=O)-) that the PVA has is a divalent group in which two bonds are both bonded to a carbon atom. That is, -C(=O)- in the formyl group (-C(=O)H) is not included in the carbonyl group possessed by the PVA. The PVA preferably has a structure represented by the following formula (1) containing a carbonyl group.

In formula (1), m is an integer from 1 to 11. m is preferably an integer from 2 to 9, and may preferably be an integer from 3 to 7.

The content of carbonyl groups relative to the total content of vinyl alcohol units and vinyl ester units in the PVA is not particularly limited, but the lower limit is, for example, preferably 0.001 mol%, more preferably 0.005 mol%, 0. .008 mol% is more preferred, and 0.01 mol%, 0.03 mol% or 0.05 mol% may be even more preferred. The upper limit of the carbonyl group content in the PVA is preferably 5 mol%, more preferably 3 mol%, even more preferably 1 mol%, and even more preferably 0.3 mol% or 0.1 mol%. There is also. The upper limit of the carbonyl group content in the PVA may be 0.05 mol% when the PVA is used as a dispersant for emulsion polymerization. When the content of carbonyl groups in the PVA is within the above range, various performances are improved when the aqueous solution is used, for example, as a coating agent or adhesive. Further, when the content of carbonyl groups in the PVA is within the above range, various performances when the PVA is used as a dispersant for emulsion polymerization are also improved. The content of the carbonyl group is a value determined by the method described in Examples described later.

The formyl group that the PVA has is a monovalent group represented by -C(=O)H.

The content of formyl groups relative to the total content of vinyl alcohol units and vinyl ester units in the PVA is not particularly limited, but the lower limit is preferably, for example, 0.01 mol%, more preferably 0.03 mol%, 0. .05 mol% is more preferred, and 0.07 mol% or 0.1 mol% may be even more preferred. The upper limit of the formyl group content in the PVA is, for example, preferably 5 mol%, more preferably 3 mol%, even more preferably 2 mol%, and 1 mol%, 0.8 mol% or 0.5 mol%. In some cases, it may be even more preferable. When the formyl group content in the PVA is within the above range, various performances are improved when the aqueous solution is used as a coating agent, adhesive, etc., for example. Further, when the content of formyl groups in the PVA is within the above range, various performances when the PVA is used as a dispersant for emulsion polymerization are also improved. The content of the formyl group is a value determined by the method described in Examples described later.

The alkenyl group that the PVA has is a monovalent group obtained by removing any one hydrogen atom from an alkene. The number of carbon atoms in the alkenyl group is preferably 2 to 13, more preferably 3 to 12, even more preferably 4 to 11, and even more preferably 5 to 9. The alkenyl group may be linear or have a branched structure, but is preferably linear. Preferably, the alkenyl group is located at the end of the polymer chain.

The alkenyl group that the PVA has preferably has a carbon-carbon double bond at the end (tip). That is, the PVA preferably has a vinyl group at the end (tip). The alkenyl group that the PVA has is more preferably a group represented by the following formula (5).

In formula (5), n is an integer from 1 to 11. n is preferably an integer of 2 to 9, more preferably an integer of 3 to 7.

The content of alkenyl groups relative to the total content of vinyl alcohol units and vinyl ester units in the PVA is not particularly limited, but the lower limit is, for example, preferably 0.005 mol%, more preferably 0.01 mol%, 0. .02 mol% is more preferred, and 0.003 mol% or 0.04 mol% may be even more preferred. The upper limit of the alkenyl group content in the PVA is, for example, preferably 5 mol%, more preferably 3 mol%, even more preferably 1 mol%, 0.5 mol%, 0.3 mol%, or 0.2 mol%. % may be even more preferable. When the content of alkenyl groups in the PVA is within the above range, various performances are improved when the aqueous solution is used as a coating agent, adhesive, etc., for example. Further, when the content of alkenyl groups in the PVA is within the above range, various performances when the PVA is used as a dispersant for emulsion polymerization are also improved. The content of the alkenyl group is a value determined by the method described in the Examples below. The preferred content range of vinyl groups relative to the total content of vinyl alcohol units and vinyl ester units in the PVA is the same as the preferred content range of alkenyl groups.

The PVA preferably has a terminal group derived from an aliphatic unsaturated aldehyde or a structural unit derived from an aliphatic unsaturated aldehyde. The number of carbon atoms in the aliphatic unsaturated aldehyde is preferably 3 to 14, more preferably 4 to 12, and even more preferably 6 to 10.

The aliphatic unsaturated aldehyde preferably has a carbon-carbon double bond, and more preferably has a carbon-carbon double bond at the terminal (tip). That is, the aliphatic unsaturated aldehyde preferably contains a vinyl group. The aliphatic unsaturated aldehyde having a carbon-carbon double bond is an alkenyl group having a methylene group at the end on the carbonyl group side, that is, a group represented by R-CH ₂ - (R is an alkenyl group). Preference is given to aliphatic unsaturated aldehydes having . In other words, the aliphatic unsaturated aldehyde is preferably an aliphatic unsaturated aldehyde other than α,β-unsaturated aldehyde. By using an aliphatic unsaturated aldehyde having the above structure, the reactivity during polymerization is improved, and PVA into which a sufficient amount of functional groups (carbonyl groups, etc.) are introduced can be effectively obtained.

The aliphatic unsaturated aldehyde is preferably a compound represented by the following formula (6).

In formula (6), p is an integer from 1 to 11. p is preferably an integer of 2 to 9, more preferably an integer of 3 to 7.

The aliphatic unsaturated aldehydes include 2-propenal, 3-butenal, 4-pentenal, 5-hexenal, 3-methyl-5-hexanal, 6-heptenal, 6-octenal, 7-octenal, 7-methyl-7 -octenal, 3,7-dimethyl-7-octenal, 8-nonenal, 9-decenal, 10-undecenal, 11-dodecenal and the like.

Examples of the terminal group derived from an aliphatic unsaturated aldehyde that the PVA preferably has include a group represented by the following formula (2).

In formula (2), R ¹ is an alkenyl group.

The number of carbon atoms in the alkenyl group represented by R ¹ in formula (2) is preferably 2 to 13, more preferably 3 to 12, even more preferably 4 to 11, and even more preferably 5 to 9. The alkenyl group represented by R ¹ may be linear or have a branched structure, but is preferably linear. The alkenyl group represented by R ¹ is preferably a group having a methylene group at the end on the carbonyl group side (a group represented by R-CH ₂ - (R is an alkenyl group)); A group having a carbon-carbon double bond is more preferable, and a group represented by the above formula (5) may be even more preferable. The terminal group represented by formula (2) is usually formed when an aliphatic unsaturated aldehyde acts as a chain transfer agent.

The structural unit derived from an aliphatic unsaturated aldehyde that the PVA preferably has includes a structural unit represented by the following formula (3) or (4).

In formulas (3) and (4), R ² to R ⁷ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. q is an integer from 1 to 11. r is an integer from 1 to 11.

R ² to R ⁴ in formula (3) are preferably hydrogen atoms. q is preferably an integer of 2 to 9, more preferably an integer of 3 to 7. The structural unit represented by formula (3) is usually formed when an aliphatic unsaturated aldehyde acts as a monomer and is introduced into a polymer chain.

R ⁵ to R ⁷ in formula (4) are preferably hydrogen atoms. r is preferably an integer of 2 to 9, more preferably an integer of 3 to 7. The structural unit represented by formula (4) is usually formed when the formyl group in the structural unit represented by formula (3) further acts as a chain transfer agent.

Preferably, the PVA has tertiary carbon atoms (carbon atoms directly bonded to three carbon atoms). Further, the PVA preferably has a structural unit containing a tertiary carbon atom. In such a case, that is, when the PVA has a branched structure, various performances are improved when the aqueous solution is used, for example, as a coating agent or adhesive. Moreover, when the PVA has a branched structure, various performances are also improved when the PVA is used as a dispersant for emulsion polymerization. For example, when the PVA has a structural unit represented by the above formula (3) or (4) and R ² to R ⁷ are hydrogen atoms, the PVA has a tertiary carbon atom.

The PVA may have structural units other than the structural units derived from vinyl esters (vinyl alcohol units and vinyl ester units) and the structural units derived from aliphatic unsaturated aldehydes. Monomers providing other structural units include α-olefins such as ethylene, propylene, 1-butene, isobutene, and 1-hexene; acrylic acid, methacrylic acid; acrylic acid esters such as methyl acrylate and ethyl acrylate; ; Methacrylic acid esters such as methyl methacrylate and ethyl methacrylate; Acrylamide derivatives such as N-methylacrylamide, N-ethylacrylamide, and 2-acrylamido-2-methylpropanesulfonic acid; N-methylmethacrylamide, N-ethylmethacrylamide Methacrylamide derivatives such as maleic acid; maleic esters such as monomethyl maleate and dimethyl maleate; fumaric acid; fumaric acid esters such as monomethyl fumarate and dimethyl fumarate; itaconic acid; 3,4-diacetoxy-1-butene Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether; Hydroxy group-containing vinyl ethers such as ethylene glycol vinyl ether, 1,3-propanediol vinyl ether, 1,4-butanediol vinyl ether; Allyl Acetate; Allyl ether such as propyl allyl ether, butyl allyl ether, hexyl allyl ether; Monomer having an oxyalkylene group; Isopropenyl acetate; 3-buten-1-ol, 4-penten-1-ol, 5-hexene Hydroxy group-containing α-olefins such as -1-ol, 7-octen-1-ol, 9-decen-1-ol, 3-methyl-3-buten-1-ol; vinyltrimethoxysilane, vinylmethyldimethoxysilane , vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, 3-(meth)acrylamidopropyltrimethoxysilane, 3-(meth)acrylamidopropyltriethoxysilane, etc. Examples include mercury, etc.

The proportion of the other structural units in all structural units in the PVA may be preferably 20 mol% or less, more preferably less than 20 mol%, 10 mol% or less, 5 mol% or 1 mol%. may be even more preferable. On the other hand, the proportion of the other structural units may be, for example, 0.1 mol% or more, or 1 mol% or more. The proportion of ethylene units in all structural units in the PVA may be preferably less than 20 mol%, and may be more preferably 10 mol% or less, 5 mol% or 1 mol%. On the other hand, the proportion of the ethylene units may be, for example, 0 mol% or more, or 1 mol% or more.

The lower limit of the viscosity average degree of polymerization of the PVA is not particularly limited, and may be, for example, 50 or 100, but is preferably 200, more preferably 300, even more preferably 400, and even more preferably 500. When the viscosity average degree of polymerization is at least the above-mentioned lower limit, the protective colloid properties are enhanced, and various performances are enhanced when the PVA is used, for example, as a dispersant for emulsion polymerization. From the viewpoint of sealing properties of silicone when an aqueous solution is used as a coating agent and from the viewpoint of adhesive strength when used as an adhesive, it is particularly preferable that the viscosity average degree of polymerization of the PVA is 1,000 or more. There is also. On the other hand, the upper limit of this viscosity average degree of polymerization is not particularly limited, but is preferably, for example, 5,000, more preferably 3,000, and even more preferably 2,000 or 1,500. Further, in cases where the PVA is used as a dispersant for suspension polymerization, the upper limit of the viscosity average degree of polymerization may be 1,000. When the viscosity average degree of polymerization is below the upper limit, the surface active performance is increased, and various performances when used as a dispersant for emulsion polymerization, for example, are improved. The viscosity average degree of polymerization is a value measured according to JIS K6726:1994. That is, after PVA is resaponified to a degree of saponification of 99.5 mol% or higher and purified, it can be determined from the intrinsic viscosity [η] (unit: liter/g) measured in water at 30°C using the following formula. .
Viscosity average degree of polymerization = ([η]×10 ⁴ /8.29) ^(1/0.62)

The water-insoluble content of the PVA is preferably 1000 ppm or less. The upper limit of this water-insoluble content is preferably 500 ppm, more preferably 200 ppm, and even more preferably 100 ppm, 70 ppm, 50 ppm, or 10 ppm. Further, the lower limit of the water-insoluble content of PVA may be 0 ppm or 1 ppm. Here, the water-insoluble content is the mass ratio of components that remain dissolved after PVA is added to water at a concentration of 5% by mass and stirred at 90°C for 60 minutes. Specifically, it is measured by the following method. be done.

That is, a 500 mL flask equipped with a stirrer and a reflux condenser is prepared in a water bath set at 20° C., 285 g of distilled water is poured into the flask, and stirring is started at 300 rpm. Weigh out 15 g of PVA and gradually add the PVA into the flask. After adding the entire amount (15 g) of PVA, the temperature of the water bath is raised to 90° C. over 30 minutes to dissolve PVA and obtain a PVA solution. After the water bath temperature reaches 90° C., dissolution is continued with stirring at 300 rpm for an additional 60 minutes. Thereafter, using the PVA solution, undissolved and residual PVA solids (hereinafter sometimes referred to as "insoluble solids" or "insoluble particles") are filtered through a metal filter with an opening of 63 μm. Next, the filter is washed with warm water at 90°C to remove the PVA solution adhering to the filter, leaving only undissolved solids on the filter, and then the filter is dried in a heated dryer at 120°C for 1 hour. The mass of the filter after drying is compared with the mass of the filter before being used for filtration, and the mass of the undissolved solids is calculated. The ratio of the mass of the undissolved solid to the mass of PVA (15 g) initially added to the water is defined as the water-insoluble content.

The isolated PVA may contain trace components such as sodium atoms (Na). For example, sodium atoms may interact with PVA in the form of sodium ions, or may be mixed with PVA in the form of sodium salts. Note that in this specification, products containing such trace components may also be simply referred to as PVA. The upper limit of the Na content in PVA is preferably 8% by mass, more preferably 5% by mass, even more preferably 1% by mass, even more preferably 0.6% by mass, and particularly preferably 0.3% by mass. The lower limit of the Na content in PVA is not particularly limited, and may be 0% by mass, 0.01% by mass, or 0.1% by mass. In addition, the sodium Na content in PVA is measured by the method described in Examples described later.

The aqueous solution may contain sodium atoms. The sodium atom may be present in the form of a sodium ion or a sodium salt. The upper limit of the sodium atom (Na) content relative to the solid content in the aqueous solution is preferably 8% by mass, more preferably 5% by mass, even more preferably 1% by mass, and 0.6% by mass. It is even more preferable that the amount is 0.3% by mass, and in some cases it is particularly preferable that the amount is 0.3% by mass. The lower limit of the Na content relative to the solid content is not particularly limited, and may be 0% by mass, 0.01% by mass, or 0.1% by mass.

<Aqueous solution according to second form>
The aqueous solution according to the second embodiment of the present invention contains PVA having a group represented by the following formula (2) at the end of a polymer chain and water. The aqueous solution itself or coated paper produced using the aqueous solution has storage stability, coating properties, air permeation resistance, silicone curability, adhesion between the release layer and the base material, initial adhesion, and water resistance. Excellent adhesion. In the aqueous solution according to the second embodiment of the present invention, preferred forms such as the concentration of PVA, the amount of insoluble matter, other components, and uses are the same as those of the aqueous solution according to the first embodiment of the present invention. .

In the PVA, R ¹ in formula (2) is an alkenyl group. The specific form and preferred form of the group (terminal group) represented by the formula (2) are as described above. As described above, the group represented by the formula (2) forms a polymer chain when the vinyl ester is polymerized in the presence of an aliphatic unsaturated aldehyde and the aliphatic unsaturated aldehyde acts as a chain transfer agent. introduced at the end of the The PVA may consist of only one type of PVA, or may be a mixture of two or more types of PVA. The specific form and preferred form of PVA contained in the aqueous solution according to the second embodiment of the present invention do not necessarily require "having a carbonyl group, a formyl group, and an alkenyl group in the same or different molecules." The specific form and preferred form of PVA contained in the aqueous solution according to the first embodiment of the present invention described above are the same.

The PVA may have a carbon-carbon double bond in addition to the alkenyl group, and in particular has a structure represented by -CO-(CH=CH) _p - (p is an integer of 1 to 5). is preferred. Such a structure is introduced, for example, by heat treating PVA.

<Method for producing vinyl alcohol polymer>
The PVA of the present disclosure is produced by a step of polymerizing a vinyl ester in the presence of an aliphatic unsaturated aldehyde (step A) and a step of saponifying the obtained vinyl ester polymer (step B).

(Process A)
In step A, vinyl ester is polymerized in the presence of an aliphatic unsaturated aldehyde to obtain a vinyl ester polymer. Examples of methods for polymerizing vinyl esters include known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Among these methods, bulk polymerization without a solvent and solution polymerization using a solvent such as alcohol are preferred. The alcohol is preferably an alcohol having 3 or less carbon atoms, more preferably methanol, ethanol, n-propanol and isopropanol, and even more preferably methanol. In carrying out the polymerization reaction by these methods, either a batch method or a continuous method can be adopted as the reaction method. There is no particular restriction on the polymerization temperature during the polymerization reaction, but a range of 5°C or higher and 200°C or lower is suitable.

Examples of the vinyl ester include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, and the like. Among them, vinyl acetate is preferred.

Examples of the polymerization initiator used in the polymerization reaction include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4- Known polymerization initiators such as azo initiators such as methoxy-2,4-dimethylvaleronitrile; organic peroxide initiators such as benzoyl peroxide, n-propyl peroxycarbonate, and diisopropyl peroxydicarbonate are used. Can be mentioned. The amount of the polymerization initiator used is preferably, for example, 0.01 to 5% by mass based on the vinyl ester used.

Specific examples and preferred examples of the aliphatic unsaturated aldehyde present during the polymerization of vinyl ester are as described above. One type or two or more types of aliphatic unsaturated aldehydes can be used. The amount of the aliphatic unsaturated aldehyde used is preferably 0.1 to 10% by mass based on the vinyl ester, for example. During polymerization of the vinyl ester, chain transfer agents other than the aliphatic unsaturated aldehyde may be present. Other chain transfer agents include aliphatic saturated aldehydes such as acetaldehyde, propionaldehyde, butyraldehyde, 1-pentanal, 1-hexanal, 1-octanal, 1-nonanal, and 1-decanal; ketones such as acetone and methyl ethyl ketone; Examples include mercaptans such as -hydroxyethanethiol and 3-mercaptopropionic acid; thiocarboxylic acids such as thioacetic acid; and halogenated hydrocarbons such as trichloroethylene and perchlorethylene.

When polymerizing the vinyl ester, further copolymerizable monomers can be copolymerized within a range that does not impair the spirit of the present invention. Examples of such copolymerizable monomers include those mentioned above as monomers providing other structural units.

(Process B)
In step B, the vinyl ester polymer obtained in step A is saponified, for example, in an alcohol solution using an alkali catalyst or an acid catalyst to obtain PVA. For the saponification reaction of vinyl ester polymers, conventionally known basic catalysts such as sodium hydroxide, potassium hydroxide, sodium methoxide, etc., or acidic catalysts such as p-toluenesulfonic acid are used. Hydrolysis reaction can be applied. Examples of the solvent used in the saponification reaction include alcohols such as methanol and ethanol; esters such as methyl acetate and ethyl acetate; ketones such as acetone and methyl ethyl ketone; and aromatic hydrocarbons such as benzene and toluene. These can be used alone or in combination of two or more. Among these, it is convenient and preferable to perform the saponification reaction in the presence of sodium hydroxide, which is a basic catalyst, using methanol or a mixed solution of methanol and methyl acetate as a solvent. Saponification can be carried out using a belt reactor, kneader reactor, tower reactor, or the like.

By going through step B, a resin solid containing PVA is obtained. The manufacturing method further includes, as steps after step B, a step of washing the resin solid material containing PVA, a step of drying the resin solid material containing PVA, a step of heat treating the resin solid material containing PVA, etc. Good too.

<Coating agent>
One embodiment of the present invention is a coating agent containing the aqueous solution described above. The aqueous solution contained in the coating agent may be the aqueous solution according to the first form described above, the aqueous solution according to the second form, or both. There are no particular restrictions on the use of the coating agent, but for example, it may be a coating agent for paper base materials or film base materials, or a coating agent used when manufacturing release paper or release films.

The coating agent may contain an organic solvent, and may contain water-insoluble organic particles, inorganic particles, etc.

Although there is no particular restriction on the lower limit of the concentration of PVA contained in the coating agent, for example, 1% by mass is preferred, 2% by mass is more preferred, and 4% by mass may be even more preferred. Further, there is no particular restriction on the upper limit of the concentration of PVA contained in the coating agent, but for example, 30% by mass is preferable, and 25% by weight may be more preferable. When the concentration of PVA in the coating agent is within the above range, coating efficiency is further improved and high-speed coating properties are more excellent.

The upper limit of the insoluble content in the coating agent is preferably 1,000 ppm, more preferably 500 ppm, even more preferably 200 ppm, even more preferably 100 ppm, particularly preferably 70 ppm, more particularly preferably 50 ppm, and even more particularly preferably 10 ppm. . Further, the lower limit of the insoluble content in the coating agent is preferably 0 ppm, and may be 1 ppm. Note that the insoluble content in the coating agent is the mass ratio of the component remaining dissolved in the coating agent to the total amount of PVA contained in the coating agent, and is specifically measured by the following method.

The coating agent is passed through a metal filter with an opening of 63 μm, and the filter is further washed with warm water at 90°C to obtain the solids remaining undissolved in the coating agent, and to remove the PVA contained in the coating agent before filtration. The ratio of the mass of undissolved solids to the mass is calculated, and this is taken as the undissolved content in the coating agent.

The method for producing the coating agent is not particularly limited. For example, a coating agent can be obtained by dissolving PVA particles in a solvent such as water.

The coating agent may contain other components other than the above-mentioned PVA and solvent as long as the effects of the present invention are not impaired. Other ingredients include water-based dispersible resins such as SBR, NBR, polyvinyl acetate, ethylene vinyl acetate copolymer, poly(meth)acrylic ester, and polyvinyl chloride; wheat, corn, rice, potato, cane, and tapioca. , raw starch obtained from sago palm, etc.; raw starch decomposition products such as oxidized starch and dextrin; starch derivatives such as etherified starch, esterified starch, and cationized starch; cellulose such as methylcellulose, hydroxyethylcellulose, and carboxymethylcellulose (CMC) Derivatives: Monosaccharides such as glucose, fructose, isomerized sugar, and xylose; Disaccharides such as maltose, lactose, sucrose, trehalose, palatinose, reduced maltose, reduced palatinose, and reduced lactose; Starch syrup, isomaltooligosaccharides, fructooligosaccharides, and lactose oligosaccharides Oligosaccharides such as sugars, soy oligosaccharides, xylooligosaccharides, coupling sugars, and cyclodextrin compounds; Polysaccharides such as pullulan, pectin, agar, konjac mannan, polydextrose, and xanthan gum; Albumin, gelatin, casein, gum arabic, and polyamide resins , melamine resin, poly(meth)acrylamide, polyvinylpyrrolidone, sodium poly(meth)acrylate, anion-modified PVA, sodium alginate, water-soluble polyester, and the like. The content of these components (water-soluble resin and water-dispersible resin) in the coating agent is preferably 10% by mass or less.

The coating agent may contain a pigment to the extent that the effects of the present invention are not impaired. Examples of pigments include inorganic pigments (clay, kaolin, aluminum hydroxide, calcium carbonate, talc, etc.) and organic pigments (plastic pigments, etc.) that are generally used in the field of coated paper manufacturing. The content of these pigment components in the coating liquid is preferably 50% by mass or less.

The substrate to which the coating agent of the present invention is applied is not particularly limited, and examples thereof include paper, film, and the like. Among these, the substrate to which the coating agent of the present invention is applied is preferably paper.

<Paper processing agent>
One embodiment of the present invention is a paper processing agent containing the aqueous solution described above. The paper processing agent can be used, for example, by coating it on paper as a base material. When using a paper processing agent by coating it on paper as a base material, this form of paper processing agent is an example of a coating agent. Furthermore, in paper processing, the paper processing agent can also be used as a paper adhesive or the like.

The paper used for the base material may be made from chemical pulp such as hardwood kraft pulp or softwood kraft pulp, or mechanical pulp such as GP (ground wood pulp), RGP (refiner ground pulp), or TMP (thermomechanical pulp). Any known paper or synthetic paper can be used. In addition, as paper, wood-free paper, medium-quality paper, alkaline paper, glassine paper, semi-glassine paper, etc. can be used, and paperboard and white paperboard used for cardboard, building materials, white balls, chipboard, etc. etc. can also be used. Note that the paper may contain papermaking auxiliary chemicals such as organic or inorganic pigments, paper strength enhancers, sizing agents, and retention improvers. Further, the paper may be subjected to various surface treatments.

A preferred embodiment of the present invention is a release paper base paper obtained by coating paper with the paper processing agent. When forming a release layer on this release paper base paper, the coating agent plays the role of a filler. In other words, the release paper base paper obtained by applying the coating agent to paper has a sealing layer formed on the base material. Although the method for producing the release paper base paper is not particularly limited, a method including a step of applying a coating agent to a base material and a step of drying the base material after coating is preferred. The paper mentioned above can be used.

Coating of the paper finishing agent of the present invention can be carried out using general coated paper equipment, such as a blade coater, air knife coater, transfer roll coater, rod metaling size press coater, curtain coater, wire bar coater, etc. The coating liquid can be applied to the paper base material in one layer or in multiple layers using an on-machine coater or an off-machine coater equipped with a coating device such as a coater. Further, as a drying method after coating, various heating drying methods such as hot air heating, gas heater heating, infrared heater heating, etc. can be appropriately employed. The coating amount is preferably 0.3 to 5.0 g/m ² in terms of dry mass. When the coating amount is 0.3 g/m ² or more, the sealing effect of silicone is improved. The coating amount is more preferably 0.5 g/m ² or more. On the other hand, when the coating amount is 5.0 g/m ² or less, the reduction in surface area due to the sealing layer can be suppressed, and the adhesion with the silicone layer can be further improved. The coating amount is more preferably 3.0 g/m ² or less.

As a method for determining the sealing effect of the sealing layer, the air permeability measured using an Oken smoothness air permeability tester according to JIS P8117:2009 can be used. The air permeability is preferably 1,000 sec or more, more preferably 5,000 sec or more, even more preferably 10,000 sec or more, and particularly preferably 50,000 sec or more. When the air permeability is within the above range, the sealing effect is better. Note that the smaller the value of air permeability (seconds; sec), the higher the air permeation rate.

In order to enhance the sealing effect, a paper finishing agent may be dried after being applied and smoothing treatment may be performed as long as the effect is not impaired. As the smoothing treatment, a super calender, a gross calender, a multi-nip calender, a soft calender, a belt nip calender, etc. are suitably employed.

Further, a release paper comprising the above-mentioned release paper base paper and a release layer formed on the surface of the release paper base paper is also a preferred embodiment of the present invention. At this time, it is preferable that the release layer contains an addition type silicone and platinum, and contains 0.001 parts by mass or more and 0.05 parts by mass or less of platinum based on 100 parts by mass of the addition type silicone. When the amount of platinum is within this range, a release paper with excellent curability can be obtained. The content of platinum is preferably 0.002 parts by mass or more, and more preferably 0.004 parts by mass or more. Further, the amount of platinum blended is preferably 0.03 parts by mass or less, and more preferably 0.02 parts by mass or less.

Addition-type silicones are organopolysiloxanes containing at least two carbon-carbon double bonds in one molecule that are reactive with SiH groups, and organohydrogen polysiloxanes containing at least two SiH groups in one molecule. may be obtained by a hydrosilylation reaction in the presence of a platinum catalyst.

Organopolysiloxanes containing at least two carbon-carbon double bonds in one molecule that are reactive with SiH groups include vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, isobutenyl groups, hexenyl groups, etc. Preferably, the organopolysiloxane contains at least two carbon-carbon double bonds in one molecule. The organopolysiloxane is exemplified by one in which the main chain is a repeating unit of diorganosiloxane and the terminal end is a triorganosiloxane structure, and may have a branched or cyclic structure. Examples of the organo group bonded to silicon at the terminal or in the repeating unit include a methyl group, an ethyl group, and a phenyl group. A specific example is methylphenylpolysiloxane having vinyl groups at both ends.

An organohydrogenpolysiloxane containing at least two SiH groups in one molecule is an organopolysiloxane containing two or more SiH groups at the terminal and/or in the repeating structure. The organopolysiloxane is exemplified by one in which the main chain is a repeating unit of diorganosiloxane and the terminal end is a triorganosiloxane structure, and may have a branched or cyclic structure. Examples of the organo group bonded to silicon at the terminal or in the repeating unit include a methyl group, ethyl group, octyl group, and phenyl group, in which two or more of these groups are substituted with hydrogen.

The addition-type silicone is appropriately selected from solvent-type, solvent-free type, and emulsion-type, but solvent-free addition-type silicone is preferably employed from the viewpoint of environmental load reduction and coatability. These silicones do not necessarily need to be used alone, and two or more types can be mixed and used as necessary.

A platinum catalyst is usually used to cure silicone, but the type of platinum catalyst used in the present invention is not particularly limited. Those that cure addition type silicone through a hydrosilylation reaction are preferably used. Platinum catalysts do not necessarily need to be used alone, and two or more types can be used in combination as necessary. The blended amount of platinum can be determined by quantifying platinum in the platinum catalyst using an ICP emission spectrometer or the like.

The release layer of the release paper may also contain other components other than addition-type silicone and platinum to the extent that the effects of the present invention are not impaired. The amount of other components to be blended is usually 30 parts by mass or less based on 100 parts by mass of the total amount of the release layer. Other components include, for example, viscosity modifiers, adhesion improvers, antifoaming agents, plasticizers, waterproofing agents, preservatives, antioxidants, penetrants, surfactants, inorganic pigments, organic pigments, fillers, Examples include starch and its derivatives, cellulose and its derivatives, sugars, latex, and the like.

The method for producing the release paper is not particularly limited, but after applying a coating agent onto the base material and forming a sealing layer, the amount of platinum blended in the release layer is 0.001 to 0.000 parts by weight based on 100 parts by mass of the addition type silicone. A method is adopted in which a coating solution containing a platinum catalyst prepared to have a concentration of 0.5 parts by mass is applied onto the sealing layer to form a release layer. The coating amount of the platinum catalyst-containing coating solution that forms the release layer is not particularly limited, but from the viewpoint of better release properties, the solid content is preferably 0.1 to 5 g/m ² . The coating amount is more preferably 0.3 g/m ² or more in terms of solid content. When the coating amount is within the above range, the adhesion between the sealing layer and the release layer containing addition type silicone and platinum is improved. The coating amount is more preferably 3 g/m ² or less in terms of solid content. Various coating methods can be used, but blade coaters, air knife coaters, bar coaters, etc. are suitable.

<Adhesive>
One embodiment of the present invention is an adhesive containing the aqueous solution described above. The adhesive may also contain other additives and the like.

The concentration range of PVA contained in the adhesive is not particularly limited, but from the viewpoint of applicability, adhesiveness, strength of the bonded part, water resistance, etc., it is preferably, for example, 0.5% by mass or more and 30% by mass or less, and 1% by mass or less. More preferably % by mass or more and 20% by mass or less.

The adhesive according to a preferred embodiment of the present invention has excellent initial adhesive properties. Although the mechanism is not clear, the alkenyl group of PVA in the adhesive acts more effectively as a hydrophobic group, forming a pseudo-association in water due to hydrophobic group interaction, increasing the viscosity and reducing the initial adhesive strength. It is thought that this may occur. However, the adhesive of the present invention is not limited to one that exhibits this mechanism.

In addition to the PVA aqueous solution, the adhesive can contain a polymer in an emulsion state and a filler. Furthermore, the adhesive may contain other additives. Other additives include metal salts of phosphoric acid compounds such as sodium polyphosphate and sodium hexametaphosphate, and inorganic dispersants such as water glass; polyacrylic acid and its salts, sodium alginate, and α-olefin maleic anhydride. Anionic polymer compounds such as copolymers and their metal salts; nonionic surfactants such as polyethylene oxide, ethylene oxide adducts of higher alcohols, copolymers of ethylene oxide and propylene oxide; carboxymethyl cellulose, methyl cellulose, etc. Cellulose derivatives; other examples include antifoaming agents, preservatives, antifungal agents, coloring pigments, deodorants, fragrances, and the like.

By containing a polymer in an emulsion state, the adhesive can improve adhesiveness and reduce the load during drying due to increased solid content. The polymer contained in the emulsion state (hereinafter also referred to as a polymer emulsion) is not particularly limited, but at least one type of monomer selected from the group consisting of ethylenically unsaturated monomers and diene monomers. Polymers (including copolymers) obtained from polymers are preferred.

Examples of the ethylenically unsaturated monomer include olefins such as ethylene, propylene, and isoptylene, vinyl esters such as vinyl acetate, (meth)acrylic esters such as methyl acrylate, ethyl acrylate, and butyl acrylate, and styrene. can be mentioned.

Further, examples of the diene monomer include butadiene, isoprene, chloroprene, and the like.

Specific examples of such polymer emulsions include vinyl acetate polymer, vinyl acetate-ethylene copolymer, vinyl acetate-vinyl versatate copolymer, vinyl acetate-(meth)acrylate copolymer, etc. vinyl acetate emulsions; (meth)acrylate emulsions such as methyl methacrylate/n-butyl acrylate copolymers; styrene emulsions; styrene-butadiene copolymers, methyl methacrylate-butadiene copolymers, etc. Examples include butadiene emulsions.

Among these, vinyl acetate-based emulsion particles or (meth)acrylic acid ester-based emulsion particles are preferred from the viewpoint of the initial adhesion and storage stability of the adhesive.

By containing the emulsion particles of the polymer together with a dispersion stabilizer, the stability of the emulsion state can be improved. As the dispersion stabilizer, vinyl alcohol polymers, water-soluble cellulose derivatives such as hydroxyethyl cellulose, various surfactants, etc. can be used, and vinyl alcohol polymers are preferred among them.

The upper limit of the content of these emulsions (polymer emulsion particles and dispersion stabilizer) is not particularly limited, but for example, it is usually preferably 1,000 parts by mass or less, and 700 parts by mass based on solid content based on 100 parts by mass of PVA. The following is more preferable, and 500 parts by mass or less is even more preferable. On the other hand, the lower limit of the content is not particularly limited, but for example, it can be used in an amount of 100 parts by mass or more.

By further containing a filler, the adhesive can reduce the load during drying due to an increase in solid content, and improve the strength and hardness after bonding.

Examples of fillers include clays such as kaolinite, halosilane, pyroferrite, and sericite, and inorganic fillers such as heavy, light, or surface-treated calcium carbonate, aluminum hydroxide, aluminum oxide, gypsum, talc, and titanium oxide. ; Examples include organic fillers such as starch, oxidized starch, wheat flour, and wood flour. Among these, various clays and various starches can be suitably used.

The upper limit of the filler content is not particularly limited, but for example, based on solid content, it is preferably 1,000 parts by mass or less, more preferably 500 parts by mass or less, 400 parts by mass or less and 50 parts by mass or more. may be even more preferable. When the content of the filler is within the above range, sedimentation of the filler during storage is suppressed, and storage stability tends to be improved.

The method for preparing the adhesive is not particularly limited, and any known method can be used. For example, a slurry liquid can be prepared by adding a mixture of PVA and other additives such as fillers into water while stirring, or by sequentially adding various additives, fillers, and PVA into water while stirring. After that, a method such as heating and dissolving can be mentioned. As a heating method at this time, a known heating method such as a heating method in which steam is directly blown into the slurry liquid or an indirect heating method using a jacket can be adopted. This preparation may be carried out either batchwise or continuously.

The adhesive according to a preferred embodiment of the present invention has excellent storage stability such as viscosity stability and sedimentation stability in addition to water solubility and initial adhesiveness. Further, by adjusting the amount of PVA contained, the water resistance after adhesion can also be improved. Therefore, the adhesive is a paper adhesive used in the production or use of corrugated paper, paper bags, paper boxes, paper tubes, wallpaper, etc. Suitable for use as a woodworking adhesive. It can also be used to adhere to fibers such as cloth and non-woven fabrics, cement molded products such as concrete, various plastics, aluminum foil, etc. Note that the uses of the adhesive of the present invention are not limited to these.

The viscosity of the adhesive can be arbitrarily selected depending on the application. When high-speed coating properties are intended, the viscosity at the bonding temperature is preferably B-type viscosity of 100 to 10,000 mPa·s.

<Dispersant for emulsion polymerization according to the first form>
The dispersant for emulsion polymerization according to the first aspect of the present invention is a dispersant for emulsion polymerization that contains PVA having a carbonyl group, a formyl group, and an alkenyl group in the same or different molecules. By using the dispersant for emulsion polymerization, it is possible to synthesize an aqueous emulsion that has excellent mechanical stability, produces little aggregates, and can produce coated paper, etc. that has excellent oil resistance. I can do it. The dispersant for emulsion polymerization contains ethylenically unsaturated monomers, especially olefin monomers, vinyl ester monomers, (meth)acrylic acid ester monomers, acrylamide monomers, and styrene monomers. It can be suitably used as a dispersant for emulsion polymerization of at least one monomer selected from monomers, diene monomers, and halogenated vinyl monomers. The dispersant for emulsion polymerization can also be used as a dispersant for emulsion polymerization of diene monomers. The specific form and preferred form of PVA used in the dispersant for emulsion polymerization of this embodiment are the same as the specific form and preferred form of PVA contained in the aqueous solution according to the first embodiment of the present invention described above. The method for producing PVA is also as described above.

The dispersant for emulsion polymerization may consist only of the PVA, or may further contain other components. Other components include conventionally known dispersants for emulsion polymerization and the like. The lower limit of the content of PVA in the dispersant for emulsion polymerization is preferably 70% by mass, more preferably 80% by mass, even more preferably 90% by mass, and more preferably 95% by mass, 99% by mass or 99.9% by mass. In some cases, it may be even more preferable. The upper limit of the content of PVA in the dispersant for emulsion polymerization may be 100% by mass, 99.9% by mass, 99% by mass, or 95% by mass.

<Dispersant for emulsion polymerization according to second form>
The dispersant for emulsion polymerization according to the second embodiment of the present invention is a dispersant for emulsion polymerization that contains PVA having a group represented by the following formula (2) at the end of the polymer chain. By using the dispersant for emulsion polymerization, it is possible to synthesize an aqueous emulsion that has excellent mechanical stability, produces little aggregates, and can produce coated paper, etc. that has excellent oil resistance. I can do it.

In formula (2), R ¹ is an alkenyl group. The specific form and preferred form of the group (terminal group) represented by the formula (2) are as described above. As described above, the group represented by the formula (2) forms a polymer chain when the vinyl ester is polymerized in the presence of an aliphatic unsaturated aldehyde and the aliphatic unsaturated aldehyde acts as a chain transfer agent. introduced at the end of the The PVA may consist of only one type of PVA, or may be a mixture of two or more types of PVA. The specific form and preferred form used for the dispersant for emulsion polymerization of this form are based on the above-mentioned form, except that it does not necessarily "have a carbonyl group, a formyl group, and an alkenyl group in the same or different molecules." The specific form and preferred form of PVA contained in the aqueous solution according to the first embodiment of the invention are the same. The method for producing PVA is also as described above.

The uses, components, etc. of the dispersant for emulsion polymerization according to the second embodiment of the present invention are the same as those of the dispersant for emulsion polymerization according to the first embodiment of the present invention.

<Aqueous emulsion>
One embodiment of the present invention provides an aqueous polymer containing a structural unit derived from at least one selected from the group consisting of an ethylenically unsaturated monomer and a diene monomer, and the dispersant for emulsion polymerization. It is an emulsion. A polymer containing a structural unit derived from at least one selected from the group consisting of ethylenically unsaturated monomers and diene monomers is a dispersoid of an aqueous emulsion. The dispersion medium of the aqueous emulsion contains water. The dispersion medium of the aqueous emulsion may be water. The aqueous emulsion may further contain components other than the polymer and dispersion medium. The pH of the aqueous emulsion is preferably 5 or more and 6 or less from the viewpoint of stability.

Furthermore, the aqueous emulsion may contain a dispersion stabilizer other than the above-mentioned dispersant for emulsion polymerization. Surfactants are preferably used as the dispersion stabilizer. The surfactant is not particularly limited, and includes, for example, anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, and polymeric compounds having surface activity (polymeric surfactants). ) can be used. Examples of anionic surfactants include alkylnaphthalene sulfonates, dialkyl sulfosuccinates, alkyldiphenyl ether sulfonates, naphthalene sulfonic acid-formalin condensates, polyoxyethylene alkyl ether sulfate salts, and polyoxyethylene alkyl phenyl ether sulfates. Examples include ester salts. Examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts such as lauryltrimethylammonium chloride, and distearyldimethylammonium chloride. Examples of nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid monoglyceride, polyethylene glycol fatty acid ester, polyoxyethylene alkyl amine, etc. . Examples of amphoteric surfactants include alkyl betaines, amine oxides, and imidazolium betaines. Basically, the polymeric surfactant may be one having a hydrophilic group and a hydrophobic group in the molecule, such as various carboxylic acid type polymeric surfactants, oxyethylene-oxypropylene block polymer (Pluronic (registered trademark) type surfactant), PVA other than the above-mentioned PVA, and cellulose derivatives such as hydroxyethyl cellulose. Among these, dialkyl sulfosuccinate, alkyldiphenyl ether sulfonate, polyoxyethylene alkyl ether sulfate, lauryl trimethyl ammonium chloride, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, other PVA, hydroxyethyl cellulose, etc. Preferably used.

Examples of one or more monomers selected from ethylenically unsaturated monomers and diene monomers include olefinic monomers such as ethylene, propylene, and isobutylene; vinyl chloride, vinyl fluoride, vinylidene chloride, Halogenated olefin monomers such as vinylidene fluoride; Vinyl ester monomers such as vinyl formate, vinyl acetate, vinyl propionate, and vinyl versatate; (meth)acrylic acid, methyl (meth)acrylate, ( (meth)acrylic acid ester monomers such as ethyl meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, etc. ;(meth)acrylic acid dimethylaminoethyl, and their quaternized products, (meth)acrylamide, N-methylol(meth)acrylamide, N,N-dimethyl(meth)acrylamide, (meth)acrylamide-2-methylpropanesulfone (meth)acrylamide monomers such as acids and their sodium salts; styrene monomers such as styrene, α-methylstyrene, p-styrenesulfonic acid and their sodium and potassium salts; butadiene, isoprene, chloroprene, etc. Diene monomers such as N-vinylpyrrolidone and the like. In addition, in this specification, "(meth)acrylic" means acrylic and methacryl.

Among ethylenically unsaturated monomers and diene monomers, from the group consisting of vinyl ester monomers, (meth)acrylate monomers, styrene monomers, and diene monomers. At least one selected type is preferred.

Furthermore, it is preferable to use a (meth)acrylic acid ester monomer, a styrene monomer, and a mixture of two or more of these monomers. It may contain a monomer as a minor component (for example, 0 to 40% by mass). The monomers constituting the (meth)acrylic acid ester polymer include acrylic acid alkyl esters having an alkyl group having 1 to 8 carbon atoms, methacrylic acid alkyl esters having an alkyl group having 1 to 8 carbon atoms, or these. Mixtures are more preferred.

<Method for producing aqueous emulsion>
One embodiment of the present invention includes a step of emulsion polymerizing at least one monomer selected from the group consisting of ethylenically unsaturated monomers and diene monomers in the presence of the emulsion polymerization dispersant. A method for producing an aqueous emulsion, including: The aqueous emulsion thus obtained has a low content of aggregates containing coarse particles and has excellent mechanical stability.

In the above manufacturing method, when the dispersant for emulsion polymerization is charged into the polymerization system, there are no particular restrictions on the method of charging or adding. Examples include a method in which the dispersant for emulsion polymerization is added to the polymerization system all at once at the initial stage, and a method in which it is added continuously during the polymerization. Among these, from the viewpoint of increasing the grafting rate of PVA to the emulsion dispersoid, a method in which a dispersant for emulsion polymerization is initially added to the polymerization system all at once is preferred.

The amount of the dispersant for emulsion polymerization used during emulsion polymerization is preferably 100 parts by mass of at least one monomer selected from the group consisting of ethylenically unsaturated monomers and diene monomers. It may be 0.2 to 40 parts by weight, more preferably 0.3 to 20 parts by weight, even more preferably 0.5 to 15 parts by weight. By using the amount of the dispersant for emulsion polymerization within the above range, aggregation of dispersoid particles in the aqueous emulsion is further suppressed, polymerization stability is improved, and the viscosity of the polymerization system is suppressed from becoming too high. Polymerization can proceed more uniformly, and the heat of polymerization tends to be removed better.

In emulsion polymerization using a dispersant for emulsion polymerization, a water-soluble single initiator or a water-soluble redox initiator commonly used in emulsion polymerization is used as the polymerization initiator. For example, sole initiators include hydrogen peroxide, persulfates (potassium, sodium or ammonium salts), and the like. Examples of the redox initiator include a combination of a peroxide and a metal ion, and a combination of a peroxide, a metal ion, and a reducing substance. The peroxides include hydrogen peroxide, hydroxy peroxides such as cumene hydroxy peroxide and t-butyl hydroxy peroxide, persulfates (potassium, sodium or ammonium salts), t-butyl peracetate, peracid esters ( t-butyl perbenzoate). Examples of the metal ions include metal ions that can undergo one-electron transfer, such as Fe ²⁺ , Cr ²⁺ , V ²⁺ , Co ²⁺ , Ti ³⁺ , and Cu ⁺ . Examples of the reducing substance include sodium hydrogen sulfite, sodium hydrogen carbonate, tartaric acid, Rongalit, 1-ethyl-ascorbic acid, and ascorbic acid.

The dispersion medium in emulsion polymerization is preferably an aqueous medium containing water as a main component. The aqueous medium containing water as a main component may contain a water-soluble organic solvent (alcohols, ketones, etc.) that is soluble in water in any proportion. Here, the term "aqueous medium containing water as a main component" refers to a dispersion medium containing 50% by mass or more of water. From the viewpoint of cost and environmental impact, the dispersion medium is preferably an aqueous medium containing 90% by mass or more of water, and more preferably water.

During emulsion polymerization, other protective colloids such as polyacrylic acid or polymethacrylic acid and its salts; polyvinyl alkyl ether; co-existence of vinyl acetate with acrylic acid, methacrylic acid, or maleic anhydride may be used to the extent that the effects of the present invention are not impaired. Polymers and their saponified products; Lower alkyl vinyl ether-maleic anhydride copolymers; Cellulose derivatives such as alkyl cellulose, hydroxyalkyl cellulose, alkyl hydroxy alkyl cellulose, and carboxymethyl cellulose; Starch derivatives such as alkyl starch, carboxymethyl starch, and oxidized starch ; gum arabic, gum tragacanth; polyalkylene glycol, etc. may be added during or after polymerization to impart desired properties to the emulsion. In addition, auxiliary agents conventionally used in emulsion polymerization, such as liquid regulators, monohydric or polyhydric alcohols, plasticizers, and antifoaming agents, may be used during or after the polymerization.

<Laminated body>
One embodiment of the present invention is a laminate comprising a base material and a layer formed from the aqueous emulsion. The layer formed from the aqueous emulsion may be a layer formed by drying the aqueous emulsion. The laminate may include a base material and a layer formed from a coating agent containing the aqueous emulsion.

Another embodiment of the present invention is a laminate including a base material and a layer containing the emulsion polymerization dispersant. The layer formed from the aqueous emulsion described above is an example of a layer containing a dispersant for emulsion polymerization.

A preferred embodiment of the laminate is a coated paper in which a coating agent containing the aqueous emulsion is applied to paper as a base material. The coating agent may be the aqueous emulsion described above. As the base paper used for the coated paper, chemical pulp such as hardwood kraft pulp and softwood kraft pulp, mechanical pulp such as GP (ground wood pulp), RGP (refiner ground pulp), TMP (thermomechanical pulp), etc. Known paper obtained by papermaking or synthetic paper can be used. In addition, the paper may include wood-free paper, medium-quality paper, alkaline paper, glassine paper, semi-glassine paper, paperboard, white paperboard, etc. used for cardboard, building materials, manila balls, white balls, chipboards, etc. Can be used. The basis weight of the front paper is not particularly limited and may be adjusted depending on the use, but it is usually 10 to 500 g/m ² or less, preferably 40 to 200 g/m ² . Note that the paper used for the coated paper may contain organic or inorganic pigments and papermaking auxiliary chemicals such as paper strength enhancers, sizing agents, and retention improvers. Further, the paper used for the coated paper may be subjected to various surface treatments.

The coating amount of the coating agent can be arbitrarily selected depending on the properties of the paper to be coated, but it is usually preferably about 0.1 to 30 g/m ² in terms of solid content. The coating agent may be applied to the surface of the paper, or may be impregnated into the paper. In the former case, the coating agent may be applied to one side or both sides of the paper.

Methods for applying the coating agent to paper include transfer methods such as a shim sizer and gate roll coater, and impregnation methods such as a size press. The transfer method is preferable since the coating layer is more easily formed. On the other hand, since the coating agent tends to form a film, even when the impregnation method is adopted, the penetration of the coating agent into the inside of the paper is suppressed, and a coating layer is efficiently formed near the surface. Therefore, the amount of coating is reduced, drying becomes easier, and costs are reduced. The temperature of the coating agent during application is usually room temperature to 100°C.

The paper coated with the coating agent solution can be dried by a known method, such as hot air, infrared rays, a heating cylinder, or a combination thereof. The drying temperature is usually room temperature to 120°C. Barrier properties can be further improved by subjecting the dried coated paper to humidity control and calender treatment. The calendering conditions are usually a roll temperature of room temperature to 100°C and a roll linear pressure of 20 to 300 kg/cm.

The coated paper may have a layer other than a layer formed from an aqueous emulsion or a layer containing a dispersant for emulsion polymerization.

Coated paper is also used as special paper such as release base paper, oil-resistant paper, thermal paper, ink-jet paper, pressure-sensitive paper, gas barrier paper, and other barrier papers, and among them, it is suitably used as release base paper and oil-resistant paper.

The present invention will be specifically explained with reference to the following examples, but the present invention is not limited to these examples in any way. In addition, each measurement method in the following examples and comparative examples is shown below.

[Viscosity average degree of polymerization of PVA]
The viscosity average degree of polymerization of PVA was measured according to JIS K6726:1994. Specifically, when the saponification degree of PVA was less than 99.5 mol%, it was saponified until the saponification degree became 99.5 mol% or more, and the obtained PVA was measured in water at 30 ° C. The viscosity average degree of polymerization was determined by the following formula using the intrinsic viscosity [η] (liter/g).
Viscosity average degree of polymerization = ([η]×10 ⁴ /8.29) ^(1/0.62)

[Saponification degree of PVA]
The degree of saponification of PVA was determined by the method described in JIS K6726:1994.

[Content of carbonyl group in PVA]
¹ H-NMR measurement was performed to calculate the carbonyl group content of PVA. The sample was subjected to Soxhlet cleaning with methyl acetate for 10 hours and vacuum dried at 40° C. for 16 hours to remove impurities before being subjected to measurement. Using a sample prepared as a 1% by mass DMSO-d ₆ solution (0.03% by mass tetramethylsilane was added as an internal standard), measurement was performed at 400 MHz (80° C., 256 times in total). Among the methine groups in the main chain of PVA, the peak of CH connected to OH groups appears at 3.8 to 4.0 ppm (integral value [M]), and the peak of CH connected to OAc groups appears at 4.2 to 4.0 ppm. Appears at .6 ppm (integral value [N]). Furthermore, the peak of the methylene group adjacent to the formyl group and carbonyl group appears at 2.3 to 2.5 ppm (integral value [O]). Furthermore, the peak of protons constituting the formyl group appears at 9.5 to 10.0 ppm (integral value [P]). The content of carbonyl groups in PVA was calculated from the following formula as a value for structural units derived from vinyl alcohol monomers (vinyl alcohol units and vinyl ester units).
Carbonyl group content (mol%) = [{([O]/2)-[P]}/([M]+[N])]×100

[PVA alkenyl group content]
¹ H-NMR measurement was performed to calculate the content of alkenyl groups (vinyl groups) in PVA. The sample was subjected to Soxhlet cleaning with methyl acetate for 10 hours and vacuum dried at 40° C. for 16 hours to remove impurities before being subjected to measurement. Using a sample prepared as a 1% by mass DMSO-d ₆ solution (0.03% by mass tetramethylsilane was added as an internal standard), measurement was performed at 400 MHz (80° C., 256 times in total). Among the methine groups in the main chain of PVA, the peak of CH to which an OH group is connected appears at 3.8 to 4.0 ppm (integral value [M]), and the peak to CH to which an OAc group is connected appears at 4.2 to 4. Appears at .6 ppm (integral value [N]). In addition, the peak of one proton constituting the vinyl group in the alkenyl group (H at the 1st position in the ethenyl group; CH ₂ = C "H" -) is 5.7 to 6.0 ppm (integral value [Q]). appear. The content of alkenyl groups in PVA was determined from the following formula as a value for structural units derived from vinyl alcohol monomers (vinyl alcohol units and vinyl ester units).
Alkenyl group content (mol%) = {[Q]/([M]+[N])}×100

[Content of formyl group in PVA]
¹ H-NMR measurement was performed to calculate the formyl group content of PVA. The sample was subjected to Soxhlet cleaning with methyl acetate for 10 hours and vacuum dried at 40° C. for 16 hours to remove impurities before being subjected to measurement. Using a sample prepared as a 1% by mass DMSO-d ₆ solution (0.03% by mass tetramethylsilane was added as an internal standard), measurement was performed at 400 MHz (80° C., 256 times in total). Among the methine groups in the main chain of PVA, the peak of CH connected to OH groups appears at 3.8 to 4.0 ppm (integral value [M]), and the peak of CH connected to OAc groups appears at 4.2 to 4.0 ppm. Appears at .6 ppm (integral value [N]). The peak of protons constituting the formyl group appears at 9.5 to 10.0 ppm (integral value [P]). The formyl group content of PVA was determined from the following formula as a value for structural units derived from vinyl alcohol monomers (vinyl alcohol units and vinyl ester units).
Formyl group content (mol%) = {[P]/([M]+[N])}×100

[Measurement of Na content]
The Na content was measured by atomic absorption measurement as follows. After carbonizing 1.0 parts by mass of PVA at 650°C, 2.0 parts by mass of hydrochloric acid was added and heated at 150°C for 3 minutes. It was dissolved in ion-exchanged water to create a 50 mL aqueous solution. The atomic absorption of the aqueous solution was measured, and the Na content was calculated using a separately prepared calibration curve.

[Water-insoluble matter]
The water-insoluble content of PVA was measured as follows. A 500 mL flask equipped with a stirrer and a reflux condenser was prepared in a water bath set at 20° C., 285 g of distilled water was put into the flask, and stirring was started at 300 rpm. 15 g of PVA particles were weighed and gradually introduced into the flask. After adding the entire amount (15 g) of PVA particles, the temperature of the water bath was raised to 90° C. over 30 minutes to dissolve the PVA particles, thereby obtaining a PVA solution. After the temperature of the water bath reached 90° C., dissolution was continued with stirring at 300 rpm for an additional 60 minutes. Thereafter, using the PVA solution, remaining undissolved PVA particles (undissolved particles) were filtered through a metal filter with an opening of 63 μm. Next, the filter was thoroughly washed with warm water at 90°C to remove the PVA solution adhering to the filter, leaving only undissolved particles on the filter, and then the filter was dried in a heated dryer at 120°C for 1 hour. The mass of the filter after drying was compared with the mass of the filter before being used for filtration, and the mass of undissolved particles was calculated. The ratio of the mass of undissolved particles to the mass of PVA (15 g) initially added to water was defined as the water-insoluble content (ppm).

[Production Example A1] (Production of PVA-A1)
1,600 parts by mass of vinyl acetate and 16.0 parts by mass of 7-octenal were charged into a reactor equipped with a stirrer, a reflux condenser, a nitrogen introduction pipe, and an addition port for a polymerization initiator, and the system was heated for 30 minutes while bubbling nitrogen. was replaced with nitrogen. The temperature of the reactor was started to rise, and when the internal temperature reached 70°C, 0.28 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added to start polymerization. After polymerizing at 70° C. for 4 hours, the polymerization was stopped by cooling. The solid content concentration at the time of termination of polymerization was 39.7% by mass, and the polymerization rate was 40%. Subsequently, unreacted monomers were removed at 30° C. under reduced pressure while occasionally adding methanol to obtain a methanol solution (concentration 35.2% by mass) of a vinyl ester polymer. Next, 116.8 parts by mass of a methanol solution of a vinyl ester polymer prepared by further adding methanol to this methanol solution (30 parts by mass of the polymer in the solution) was added with 2 parts of a 10% by mass methanol solution of sodium hydroxide. .1 part by mass and 1.2 parts by mass of ion-exchanged water were added, and saponification was carried out at 40°C. molar ratio of sodium hydroxide to vinyl acetate units in the polymer (0.015). Approximately 10 minutes after the addition of the methanol solution of sodium hydroxide, a gel-like substance was formed, so this was pulverized using a pulverizer and left at 40° C. for 1 hour to advance saponification. Thereafter, 120 parts by mass of methanol was added, and the mixture was allowed to stand at 40° C. for 30 minutes for washing. After repeating this washing operation twice, the white solid obtained by removing the liquid was vacuum dried at 40° C. for 16 hours to obtain PVA (PVA-A1). The analysis results of PVA-A1 are shown in Table 2.

[Production Examples A2, A3, A5, A6] (Production of PVA-A2, A3, A5, A6)
Amount of vinyl acetate charged, amount of methanol used, type and amount of monomer (a) used during polymerization, polymerization conditions such as polymerization temperature, concentration of vinyl ester polymer during saponification, relative to vinyl acetate units. Each PVA of Production Examples A2, A3, A5, and A6 (PVA-A2, A3, A5, A6) were manufactured. Production Example A6 was produced using monomer (b) as well as monomer (a) as shown in Table 1. Table 2 shows the analysis results of PVA-A2, A3, A5, and A6.

[Production Example A4] (Production of PVA-A4)
1,600 parts by mass of vinyl acetate, 5.0 parts by mass of 7-octenal, and 200 parts by mass of methanol were charged into a reactor equipped with a stirrer, a reflux condenser, a nitrogen introduction pipe, and an addition port for a polymerization initiator, and nitrogen bubbling was carried out. The inside of the system was replaced with nitrogen for 30 minutes. The temperature of the reactor was started to rise, and when the internal temperature reached 60°C, 0.1 part by mass of 2,2'-azobisisobutyronitrile (AIBN) was added to start polymerization. After polymerizing at 60° C. for 4 hours, the polymerization was stopped by cooling. The solid content concentration at the time of termination of polymerization was 26.7% by mass, and the polymerization rate was 30%. Subsequently, unreacted monomers were removed at 30° C. under reduced pressure while occasionally adding methanol to obtain a methanol solution (concentration 30.2% by mass) of a vinyl ester polymer. Next, 117.7 parts by mass of a methanol solution of a vinyl ester polymer prepared by further adding methanol to this methanol solution (30 parts by mass of the polymer in the solution) was added with 1 part by mass of a 10% by mass methanol solution of sodium hydroxide. .3 parts by mass and 1.2 parts by mass of ion-exchanged water were added, and saponification was carried out at 40°C. molar ratio of sodium hydroxide to vinyl acetate units in the polymer (0.009). Approximately 10 minutes after the addition of the methanol solution of sodium hydroxide, a gel-like substance was formed, so this was pulverized using a pulverizer and left at 40° C. for 1 hour to advance saponification. Thereafter, 120 parts by mass of methanol was added, and the mixture was allowed to stand at 40° C. for 30 minutes for washing. After repeating this washing operation twice, the white solid obtained by removing liquid was vacuum dried at 40° C. for 16 hours to obtain PVA (PVA-A4). The analysis results of PVA-A4 are shown in Table 2.

[Production Example A7] (Production of PVA-A7)
Monomer (a) is not used, amount of vinyl acetate charged, amount of methanol used, polymerization conditions such as polymerization temperature, concentration of vinyl ester polymer during saponification, mole of sodium hydroxide per vinyl acetate unit. PVA (PVA-A7) was produced in the same manner as Production Example A4, except that the saponification conditions such as ratio were changed as shown in Table 1. The analysis results of PVA-A7 are shown in Table 2.

[Production Example A8] (Production of PVA-A8)
Table 1 shows the amount of vinyl acetate charged, the amount of methanol used, polymerization conditions such as polymerization temperature, the concentration of vinyl ester polymer during saponification, and the saponification conditions such as the molar ratio of sodium hydroxide to vinyl acetate units. Raw material PVA (c) was produced in the same manner as Production Example A7 except for the following changes. Subsequently, 80 parts by mass of raw material PVA (c) was dissolved in 1 L of water at 95°C. It was then reacted with 0.5 parts by weight of 10-undecenal at 90° C. for 1 hour under acidic conditions (pH=1.5 in sulfuric acid). At the end of the reaction, the pH was adjusted to 7 using sodium hydroxide. The reaction solution was dried to obtain PVA (PVA-A8). The analysis results of PVA-A8 are shown in Table 2.

[Production Example A9] (Production of PVA-A9)
Using raw material PVA (c) produced in the same manner as Production Example A8, 20 parts by mass of raw material PVA (c) was dissolved in 400 mL of N-methylpyrrolidone at 120°C. The solution was then cooled to room temperature while stirring. Subsequently, 0.3 parts by mass of 10-undecenoyl chloride dissolved in 10 mL of N-methylpyrrolidone was added in a nitrogen atmosphere. After 15 minutes, 3.5 parts by mass of pyridine and 0.5 parts by mass of dimethylaminopyridine were added and reacted at room temperature for 48 hours. The reaction solution was added dropwise to acetone, and the precipitate was collected. Further, reprecipitation purification was performed using water/acetone, and the collected precipitate was vacuum-dried for 8 hours to obtain PVA (PVA-A9). The analysis results of PVA-A9 are shown in Table 2.

[Production Example A10] (Production of PVA-A10)
Using the raw material PVA (c) produced in the same manner as in Production Example A8, a solution was prepared by dissolving 6 parts by mass of itaconic acid and 0.3 parts by mass of propyl gallate in 150 parts by mass of methanol, and the raw material PVA (c) was dissolved in 150 parts by mass of methanol. c) 100 parts by mass was added to cause swelling, and then methanol was removed under reduced pressure. Thereafter, the obtained mixed powder was heat treated at a temperature of 105° C. for 4 hours to obtain PVA (PVA-A10). The analysis results of PVA-A10 are shown in Table 2.

[Production Example A11] (Production of PVA-A11)
1000 parts by mass of vinyl acetate, 600 parts by mass of methanol, and 8.8 parts by mass of arylidene diacetate were placed in a reactor equipped with a stirrer, a reflux condenser, a nitrogen introduction pipe, a chain transfer agent dropping port, and a polymerization initiator addition port. After charging, the inside of the system was replaced with nitrogen for 30 minutes while bubbling nitrogen. The temperature of the reactor was started to rise, and when the internal temperature reached 60°C, 3.8 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added to start polymerization. A methanol solution of arylidene diacetate (concentration 50% by mass) was added dropwise to the reactor. It was added dropwise while keeping the composition ratio with vinyl acetate in the polymerization solution constant (total amount dropped: 15.2 parts by mass), and after polymerization was performed at 60° C. for 10 hours, the polymerization was stopped by cooling. The solid content concentration at the time of termination of polymerization was 49.0% by mass, and the polymerization rate was 80%. Next, Production Example 1 was repeated, except that the saponification conditions such as the concentration of the vinyl ester polymer during saponification and the molar ratio of sodium hydroxide to vinyl acetate units were changed as shown in Table 1. PVA (PVA-A11) was obtained by a similar method. The analysis results of PVA-A11 are shown in Table 2.

[Example A1] (Preparation of aqueous solution)
PVA-A1 obtained in Production Example A1 was poured into stirring water, heated to 95°C, and dissolved in water to give a concentration of 6% by mass (1560 parts by mass of water per 100 parts by mass of PVA). An aqueous solution was prepared.

Using the aqueous solution prepared above as a coating agent, a release paper base paper was prepared in the following manner. The stability of the coating agent (aqueous solution), coating unevenness of the release paper base paper, air permeability (air permeation resistance), silicone curability, and adhesion of the release layer were evaluated using the following methods. The results are shown in Table 3.

(Aqueous solution stability)
The state of the aqueous solution after being left at 40° C. for 7 days was observed, and the change in state before and after storage was evaluated using the following index. If it was A to B, it was judged that the storage stability was excellent.
A: No separation or sedimentation B: Slight separation or sedimentation, but fluidity C: Separation or sedimentation observed. or no liquidity

(Manufacture of release paper base paper)
The coating agent was applied to glassine paper with an air permeability of 100 sec using a wire bar so that the coating amount was about 0.7 g/m ² in terms of dry mass. After coating, coated paper was obtained by drying at 100° C. for 5 minutes. The obtained coated paper was treated twice in a supercalender at 70° C. and 400 kg/cm ² to obtain a release paper base paper.

(Evaluation of coating unevenness)
The release paper base paper was cut into pieces 1 cm long and 2 cm wide, one drop of a 1/200 normal iodine aqueous solution was added, and the surface of the coated paper was observed. The areas on the coated surface that are coated with the coating liquid are dyed bluish-purple, and the areas that are not coated with the coating liquid are dyed reddish-purple. Based on this difference, coating unevenness was determined based on the following criteria. If it was A to B, it was judged that the coating properties were excellent.
A: Uniform B: Partially uneven C: Overall uneven

(Measurement of air permeability)
The air permeability of the release paper base paper was measured using an Oken type smoothness air permeability tester according to JIS P8117, and evaluated using the following index. If it was A to B, it was judged that the resistance to air permeation was excellent.
A: 50,000 seconds or more B: 1,000 seconds or more and less than 50,000 seconds C: Less than 1,000 seconds

(Evaluation of silicone curability)
Using LTC1056L manufactured by Dow Corning Toray as the addition type silicone and SRX212 as the platinum catalyst, a coating liquid was mixed so that the ratio of addition type silicone and platinum was 100/0.007, and the resulting release paper It was coated onto base paper using a blade coater so that the coating solid content was 1.5 g/m ² . In this way, a silicone layer was formed on the release paper base paper. Then, the time required for the silicone to harden after heat treatment at 110° C. was measured and evaluated using the following index. Here, the time it takes for the silicone to harden refers to the time (seconds) required until the silicone layer does not peel off at all when the silicone layer is strongly rubbed with a finger 10 times at predetermined time intervals. If it was A to B, it was judged that the silicone curability was excellent.
A: Less than 60 seconds B: 60 seconds or more and less than 120 seconds C: 120 seconds or more

(Evaluation of adhesion of release layer)
A coating solution containing LTC1056L manufactured by Dow Corning Toray Co., Ltd. as the addition type silicone and SRX212 as the platinum catalyst was mixed on the release paper base paper so that the ratio of addition type silicone and platinum was 100/0.009. , Coating was carried out on the obtained release paper base paper using a blade coater so that the coating solid content was 1.5 g/m ² , and heat-treated at 110°C for 90 seconds to form a release layer (silicone layer) on the release paper base paper. A release paper on which was formed was obtained. The obtained release paper was evaluated using the following indicators. If it was A to B, it was judged that the adhesion was excellent.
A: After being left for one week at 40° C. and 90% RH, the silicone layer was rubbed strongly with a finger. As a result, the silicone layer did not peel off. After standing for another week under the same conditions, the silicone layer was rubbed vigorously with a finger. As a result, the silicone layer did not peel off.
B: After being left for one week at 40° C. and 90% RH, the silicone layer was strongly rubbed with a finger. As a result, the silicone layer did not peel off. However, under the same conditions, after being left for another week, the silicone layer peeled off when rubbed forcefully with a finger.
C: After being left for one week at 40° C. and 90% RH, the silicone layer was rubbed strongly with a finger. As a result, the silicone layer peeled off.

[Examples A2 to A6, Comparative Examples A1 to A4]
An aqueous solution (coating agent) was prepared and a release paper base paper was prepared in the same manner as in Example A1 except that the type of PVA was changed as shown in Table 3. The aqueous solution stability of the obtained aqueous solution (coating agent), coating unevenness of the release paper base paper, air permeability, silicone curability and adhesion were evaluated in the same manner as in Example A1. The results are shown in Table 3.

As shown in Table 3, coating agents containing aqueous solutions of vinyl alcohol polymers having carbonyl groups, formyl groups, and alkenyl groups in the same or different molecules have excellent aqueous solution stability and It can be seen that there are few manufacturing irregularities. Furthermore, it can be seen that the obtained release paper base paper has high air permeability, good silicone curability, and good adhesion of the release layer (Examples A1 to A6). In particular, when the carbonyl group content of PVA is 0.05 mol% or more, the alkenyl group content is 0.04 mol% or more, and the formyl group content is 0.1 mol% or more, silicone curability and peelability The layer adhesion was particularly excellent (Examples A1 to A3, A5, and A6). On the other hand, when PVA-A7 having no carbonyl group, alkenyl group, or formyl group was used, the silicone curability and the adhesion of the release layer were significantly inferior (Comparative Example A1). Furthermore, when PVA having only alkenyl groups was used, the aqueous solution stability was poor, and the silicone curability and release layer adhesion were also insufficient (Comparative Examples A2 to A4).

[Example A7] (Preparation of adhesive)
PVA-A1 obtained in Production Example A1 was poured into stirring water, heated to 95°C, and dissolved in the water to form an aqueous solution with a concentration of 15% by mass (567 parts by mass of water per 100 parts by mass of PVA). was prepared and used as an adhesive. Initial adhesion and water-resistant adhesion were evaluated using the following methods.

(Initial adhesion)
In an atmosphere of 20° C. and 65% RH, the adhesive was applied to No. 1 kraft paper. After coating with a wire bar No. 6, kraft paper was further laminated on top of the coating, and then pressed three times with a hand roll. Then, the time from completion of pressing to when the kraft paper became completely torn without peeling off when peeled off by hand was measured and evaluated according to the following criteria. If it was A to B, it was judged that the initial adhesion was excellent. The results are shown in Table 4.
A: The kraft paper was completely torn in less than 3 seconds B: The kraft paper was completely torn in 3 seconds or more but less than 5 seconds C: The kraft paper was completely torn in 5 seconds or more but less than 10 seconds D: 10 seconds or more The kraft paper was completely torn.

(Water resistant adhesion)
In an atmosphere of 20° C. and 65% RH, the adhesive was applied to No. 1 kraft paper. After coating with a wire bar No. 6, kraft paper was further laminated on top of the coating, and then pressed three times with a hand roll. This kraft paper was dried at 100°C for 5 minutes, then cured for 24 hours in an atmosphere of 20°C and 65% RH, and then immersed in water at 30°C for 30 seconds. After gently wiping off the moisture from the water-containing kraft paper using filter paper, the 180°C peel strength of the adhesive layer was measured using an autograph and evaluated using the following index. If it was A to B, it was judged that the water resistant adhesiveness was excellent. The results are shown in Table 4.
A: Craft paper debris B: 1kg/ ^cm2 or more C: Less than 1kg/ ^cm2

[Examples A8 to A12, Comparative Examples A5 and A6]
An adhesive was produced in the same manner as in Example A7, except that the type of PVA was changed to the contents shown in Table 4. The initial adhesion and water-resistant adhesion of the resulting adhesive were evaluated in the same manner as in Example A7. The results are shown in Table 4.

As shown in Table 4, adhesives containing aqueous solutions of vinyl alcohol polymers having carbonyl, formyl, and alkenyl groups in the same or different molecules had good initial adhesion and water-resistant adhesion. (Examples A7 to A12). In particular, the saponification degree of PVA is 75 mol% or more, the carbonyl group content is 0.05 mol% or more, the alkenyl group content is 0.04 mol% or more, and the formyl group content is 0.1 mol%. In the above cases, the water-resistant adhesion was particularly excellent (Examples A7, A8, A11, A12). On the other hand, when PVA-A7 having no carbonyl group, alkenyl group, or formyl group was used, initial adhesion and water-resistant adhesion were significantly inferior (Comparative Example A5). Furthermore, when PVA-A11 having only formyl groups was used, the initial adhesion was poor (Comparative Example A6).

[Production Example B1] (Production of PVA-B1)
1,600 parts by mass of vinyl acetate and 35.0 parts by mass of 7-octenal were charged into a reactor equipped with a stirrer, a reflux condenser, a nitrogen introduction pipe, and an addition port for a polymerization initiator, and the system was heated for 30 minutes while bubbling nitrogen. was replaced with nitrogen. Raising the temperature of the reactor was started, and when the internal temperature reached 60°C, 2.4 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added to start polymerization. After polymerizing at 60° C. for 3 hours, the polymerization was stopped by cooling. The solid content concentration at the time of termination of polymerization was 44.3% by mass, and the polymerization rate was 45%. Subsequently, unreacted monomers were removed at 30° C. under reduced pressure while occasionally adding methanol to obtain a methanol solution (concentration 38.2% by mass) of a vinyl ester polymer. Next, 191.3 parts by mass of a methanol solution of a vinyl ester polymer prepared by further adding methanol to this methanol solution (60 parts by mass of the polymer in the solution) was added with 6 parts by mass of a 5% by mass methanol solution of sodium hydroxide. .8 parts by mass and 1.84 parts by mass of ion-exchanged water were added, and saponification was carried out at 40°C. molar ratio of sodium hydroxide to vinyl acetate units in the polymer (0.012). Approximately 10 minutes after the addition of the methanol solution of sodium hydroxide, a gel-like substance was formed, so this was pulverized using a pulverizer and left at 40° C. for 1 hour to advance saponification. Thereafter, 200 parts by mass of methanol was added, and the mixture was allowed to stand at 40° C. for 30 minutes for washing. After repeating this washing operation twice, the white solid obtained by removing the liquid was vacuum dried at 40° C. for 16 hours to obtain PVA (PVA-B1). Table 6 shows the physical properties of PVA-B1.

[Production Examples B2 to B9] (Production of PVA-B2 to PVA-B9)
The table shows the polymerization conditions such as the amount of vinyl acetate charged, the type and amount of aldehyde used during polymerization, the concentration of vinyl ester polymer during saponification, and the saponification conditions such as the molar ratio of sodium hydroxide to vinyl acetate units. PVA (PVA-B2 to PVA-B7) was produced in the same manner as in the production of PVA-B1, except for the changes described in 5. PVA-B4 was prepared using aldehyde (a) along with chain transfer agent (b) as described in Table 5. Regarding PVA-B8, methanol was used during polymerization, aldehyde (a) was not used, polymerization conditions such as the amount of vinyl acetate charged, the concentration of vinyl ester polymer during saponification, and water relative to vinyl acetate units. It was produced in the same manner as in the production of PVA-B1, except that the saponification conditions such as the molar ratio of sodium oxide were changed as shown in Table 5. Regarding PVA-B9, methanol was used during polymerization, aldehyde (a) was not used, a chain transfer agent (b) was used, polymerization conditions such as the amount of vinyl acetate charged, and vinyl ester type during saponification. It was produced in the same manner as in the production of PVA-B1, except that the saponification conditions such as the concentration of the polymer and the molar ratio of sodium hydroxide to vinyl acetate units were changed as shown in Table 5. Table 6 shows the physical properties of each PVA.

[Example B1] (Production of Em-1)
In a 1-liter glass container equipped with a reflux condenser, dropping funnel, thermometer, and nitrogen inlet, 20 g of PVA (PVA-B1) was heated and dissolved in 275.0 g of ion-exchanged water, and the solution was diluted with dilute sulfuric acid to pH = 3.5. Adjusted to. After heating the prepared PVA aqueous solution to 75° C. while stirring at 200 rpm, 22 g of an ammonium persulfate aqueous solution with a concentration of 5% by mass and 6.1 g of a sodium hydrogen carbonate aqueous solution with a concentration of 1% by mass were added. A mixture of 100 g of methyl methacrylate, 100 g of 2-ethylhexyl acrylate, and 1.0 g of t-dodecylmercaptan was added continuously over 3 hours. The polymerization temperature was maintained at 80° C. to complete the polymerization, and a reaction product with a solid content concentration of 39.8% by mass was obtained. This reaction product was adjusted to pH=5.2 with aqueous ammonia to obtain an aqueous emulsion (Em-1). Regarding the aqueous emulsion (Em-1), the amount of aggregates produced and mechanical stability were evaluated using the following methods. The results are shown in Table 7.

(Amount of aggregates produced (filtration residue))
500 g of the aqueous emulsion was filtered through a 60 mesh standard sieve in accordance with JIS K8801, and the filtered residue was weighed and evaluated as follows. If it was A to C, it was judged that the generation of aggregates was small.
A: The filtration residue is less than 1.0% by mass. B: The filtration residue is 1.0% by mass or more and less than 2.5% by mass. C: The filtration residue is 2.5% by mass or more and 5.0% by mass. % D: The filtration residue is 5.0% by mass or more, making filtration difficult

(Mechanical stability (solidification rate))
Using a Maron-type mechanical stability measuring device, 50 g of the aqueous emulsion was stirred for 10 minutes at a load of 20 kg and 1000 rpm in accordance with JIS K6828, and then filtered through an 80-mesh wire mesh to remove the coagulated material on the wire mesh. The dry mass (g) of the sample was measured, and the coagulation rate (%) was determined using the following formula, which was used as an index of mechanical stability. The smaller the coagulation rate value, the better the stability. If the coagulation rate was 0.4% or less, it was judged that the mechanical stability was excellent.
Coagulation rate (%) = [dry mass of coagulum/(50 x solid content concentration of aqueous emulsion/100)] x 100

(Manufacture of coated paper for oil-resistant paper)
The aqueous emulsion was used as a coating agent, and this coating agent was applied by hand to PPC (Plain Paper Copier) paper (high quality paper) having a basis weight of 70 gsm using a wire bar. Next, using a cylinder type rotary dryer, drying was performed at 105° C. for 5 minutes to produce coated paper. This coated paper is a laminate including PPC paper as a base material and a layer containing an aqueous emulsion. The coating amount of the coating agent in terms of solid content was 5.0 gsm (one side). The resulting coated paper was conditioned at 20° C. and 65% RH for 72 hours. The oil resistance of the coated paper after humidity conditioning was evaluated by the following KIT test. The results are shown in Table 7.

(Oil resistance evaluation: KIT test)
Regarding coated paper, TAPPI No. A KIT test was conducted on the flat surface of the coated surface based on T559cm-02. Evaluation was performed visually. Note that the KIT value of commercially available oil-resistant paper using fluororesin is usually 5th grade or higher, and the oil resistance that does not pose a problem in general use is 5th grade or higher. Therefore, it was determined that coated paper has excellent oil resistance if it has an oil resistance of grade 5 or higher. In applications where higher oil resistance is required, grade 7 or higher is preferred, and grade 10 or higher is more preferred.

[Example B2] (Manufacture of Em-2)
An aqueous emulsion (Em-2) and coated paper were prepared and evaluated in the same manner as in Example B1, except that the mass ratio of methyl methacrylate and 2-ethylhexyl acrylate was changed as shown in Table 7. The results are shown in Table 7.

[Example B3] (Manufacture of Em-3)
An aqueous emulsion (Em-3) and coated paper were prepared in the same manner as in Example B1, except that methyl methacrylate, 2-ethylhexyl acrylate, and styrene were used as monomers in the mass ratios listed in Table 7. ,evaluated. The results are shown in Table 7.

[Examples B4 to B8, Comparative Examples B1 to B3] (Production of Em-4 to Em-11)
As shown in Table 7, aqueous emulsions (Em-4 to Em-11) were prepared in the same manner as in Example B1, except that PVA-B2 to PVA-B9 were used instead of PVA in Example B1 (PVA-B1). And each coated paper was produced and evaluated. The results are shown in Table 7.

As shown in Table 7, etc., aqueous emulsions obtained using dispersants containing vinyl alcohol polymers having carbonyl groups, formyl groups, and alkenyl groups in the same or different molecules are free from the formation of aggregates. It also had excellent mechanical stability. Furthermore, coated papers produced using these aqueous emulsions as coating agents also had excellent oil resistance.

The aqueous solution containing PVA of the present invention is suitable for coating agents, adhesives, paper processing agents, and the like. The emulsion polymerization dispersant of the present invention is suitable for producing an aqueous emulsion. The aqueous emulsion is suitably used for various adhesives, paint bases, various binders for impregnated paper and nonwoven products, and various coating agents.

Claims

An aqueous solution containing a vinyl alcohol polymer having a carbonyl group, a formyl group, and an alkenyl group in the same or different molecules.
The aqueous solution according to claim 1, wherein the vinyl alcohol polymer has a structure represented by the following formula (1) containing the carbonyl group.

In formula (1), m is an integer from 1 to 11.
An aqueous solution containing a vinyl alcohol polymer having a group represented by the following formula (2) at the end of a polymer chain.

In formula (2), R 1 is an alkenyl group.
The aqueous solution according to claim 3, wherein the alkenyl group represented by R 1 in the formula (2) has a methylene group at the end on the carbonyl group side.
The aqueous solution according to any one of claims 1 to 4, wherein the vinyl alcohol polymer has a tertiary carbon atom.
The aqueous solution according to any one of claims 1 to 5, wherein the vinyl alcohol polymer has a structural unit derived from an aliphatic unsaturated aldehyde.
The aqueous solution according to claim 6, wherein the aliphatic unsaturated aldehyde has 3 to 14 carbon atoms.
The aqueous solution according to claim 6 or 7, wherein the aliphatic unsaturated aldehyde has a carbon-carbon double bond at its terminal.
The aqueous solution according to any one of claims 1 to 8, wherein the concentration of the vinyl alcohol polymer is 0.5% by mass or more and 30% by mass or less.
A coating agent comprising the aqueous solution according to any one of claims 1 to 9.
An adhesive comprising the aqueous solution according to any one of claims 1 to 9.
A paper processing agent comprising the aqueous solution according to any one of claims 1 to 9.
A dispersant for emulsion polymerization containing a vinyl alcohol polymer having a carbonyl group, a formyl group, and an alkenyl group in the same or different molecules.
The dispersant for emulsion polymerization according to claim 13, wherein the vinyl alcohol polymer has a structure represented by the following formula (1) containing the carbonyl group.

In formula (1), m is an integer from 1 to 11.
A dispersant for emulsion polymerization, comprising a vinyl alcohol polymer having a group represented by the following formula (2) at the end of a polymer chain.

In formula (2), R 1 is an alkenyl group.
The dispersant for emulsion polymerization according to claim 15, wherein the alkenyl group represented by R 1 in the formula (2) has a methylene group at the end on the carbonyl group side.
The dispersant for emulsion polymerization according to any one of claims 13 to 16, wherein the vinyl alcohol polymer has a tertiary carbon atom.
The dispersant for emulsion polymerization according to any one of claims 13 to 17, wherein the vinyl alcohol polymer has a structural unit derived from an aliphatic unsaturated aldehyde.
The dispersant for emulsion polymerization according to claim 18, wherein the aliphatic unsaturated aldehyde has 3 to 14 carbon atoms.
The dispersant for emulsion polymerization according to claim 18 or 19, wherein the aliphatic unsaturated aldehyde has a carbon-carbon double bond at the end.
The dispersant for emulsion polymerization according to any one of claims 13 to 20, wherein the vinyl alcohol polymer has a saponification degree of 80 mol% or more.
A polymer containing a structural unit derived from at least one selected from the group consisting of ethylenically unsaturated monomers and diene monomers, and the dispersant for emulsion polymerization according to any one of claims 13 to 21. Aqueous emulsions containing.
The aqueous emulsion according to claim 22, wherein the ethylenically unsaturated monomer is at least one selected from the group consisting of styrene monomers, acrylic ester monomers, and methacrylic ester monomers. .
A laminate comprising a base material and a layer formed from the aqueous emulsion according to claim 22 or 23.
The laminate according to claim 24, wherein the base material is paper.
A laminate comprising a base material and a layer containing the emulsion polymerization dispersant according to any one of claims 13 to 21.
Emulsifying at least one monomer selected from the group consisting of ethylenically unsaturated monomers and diene monomers in the presence of the dispersant for emulsion polymerization according to any one of claims 13 to 21. A method for producing an aqueous emulsion, including a step of polymerizing.
28. The ethylenically unsaturated monomer is at least one monomer selected from the group consisting of styrene monomers, acrylic ester monomers, and methacrylic ester monomers. A method for producing an aqueous emulsion.