JP5931670B2 - Coating agent, coated product obtained by applying this coating agent, and method for producing the same - Google Patents

Description

  The present invention relates to a coating agent containing a vinyl alcohol polymer, a coated product obtained by applying the coating agent, and a method for producing the same.

  A vinyl alcohol polymer represented by polyvinyl alcohol (hereinafter sometimes abbreviated as “PVA”) is known as a water-soluble synthetic polymer, and is a raw material for vinylon which is a synthetic fiber, a paper processing agent. It is widely used for fiber processing agents, adhesives, stabilizers for emulsion polymerization and suspension polymerization, inorganic binders, films and the like. In particular, PVA is superior in strength properties and film-forming properties compared to other water-soluble synthetic polymers, and a coating agent (clear coating agent) for improving the surface properties of a substrate such as paper by utilizing these properties. And as a binder in pigment coating).

  In order to further enhance the properties of such PVA, PVA with various modifications has been developed. As one of the modified PVA, silyl group-containing PVA can be mentioned. This silyl group-containing PVA has high water resistance and high binder strength against inorganic substances. However, the silyl group-containing PVA is (a) difficult to dissolve unless an alkali or acid such as sodium hydroxide is added when preparing an aqueous solution, and (b) the viscosity stability of the prepared aqueous solution is low. When the film containing the inorganic substance is formed, it is difficult to satisfy both the water resistance of the obtained film and the binder strength against the inorganic substance at the same time.

  Therefore, water solubility and the like are improved by setting the product (P × S) of the viscosity average degree of polymerization (P) and the content of the monomer unit having a silyl group (S: mol%) within a certain range. Proposed silyl group-containing PVA (see JP-A-2004-43644) and coating agents containing such silyl group-containing PVA (see JP-A-2005-194437) have been proposed. However, in these silyl group-containing PVA, the upper limit of the product (P × S) is 370, and the content of the monomer unit having a silyl group is increased to enhance the characteristics as the silyl group-containing PVA. And the trade-off relationship between improving water solubility and the like has not been resolved. That is, as described in paragraph 0009 of JP 2004-43644 A, when the product (P × S) is 370 or more, an alkali or an acid is added when preparing an aqueous solution of silyl group-containing PVA. Otherwise, there is a disadvantage in handling that it may not be dissolved. That is, it cannot be said that the silyl group-containing PVA sufficiently solves the above-mentioned disadvantages.

  Furthermore, the obtained film may require high surface strength and sealability, and development of a coating agent that satisfies these characteristics is required.

JP 2004-43644 A JP 2005-194437 A

  The present invention has been made based on the above-mentioned circumstances, and can obtain a film having high water resistance, binder strength against inorganic substances, surface strength and high sealability, and sufficient handleability and viscosity stability. It is an object of the present invention to provide a coating agent, a coated product obtained by applying the coating agent, and a method for producing the same.

The invention made to solve the above problems is
It is a coating agent containing a PVA containing a monomer unit having a group represented by the following formula (1) and satisfying the following formula (I).

The formula (1), ^{R 1} is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ² is a group represented by an alkoxyl group, an acyloxyl group, or OM. M is a hydrogen atom, an alkali metal or an ammonium group. R ³ and R ⁴ are each independently a hydrogen atom or an alkyl group. The hydrogen atom which the alkyl group, alkoxyl group, and acyloxyl group represented by R ^{1 to} R ⁴ have may be substituted with a substituent containing an oxygen atom or a nitrogen atom. m is an integer of 0-2. n is an integer of 3 or more. When a plurality of R ^{1 to} R ⁴ are present, each of the plurality of R ^{1 to} R ⁴ independently satisfies the above definition.

370 ≦ P × S ≦ 6,000 (I)
P: Viscosity average degree of polymerization S: Content of the monomer unit (mol%)

  The PVA contained in the coating agent includes a monomer unit having a group represented by the above formula (1), and has a structure in which a silyl group is connected to a main chain via an alkylene group having 3 or more carbon atoms. Have. For this reason, even if it raises the modification | denaturation amount of the silyl group of PVA contained, since the water solubility is high in a neutral area | region, the coating agent has good handleability and the fall of viscosity stability is suppressed. Moreover, according to the coating agent, since the product (P × S) of the viscosity average polymerization degree (P) of the contained PVA and the content (S) of the monomer unit is in the above range, the silyl group modification The amount can be increased, and a film having high water resistance, binder strength, surface strength, sealability and the like can be obtained.

It is preferable that the PVA further satisfies the following formulas (II) and (III).
200 ≦ P ≦ 4,000 (II)
0.1 ≦ S ≦ 10 (III)
P: Viscosity average degree of polymerization S: Content of the monomer unit (mol%)

  Thus, by setting the viscosity average degree of polymerization (P) of the PVA and the content (S) of the monomer unit in the above ranges, water solubility and viscosity stability are improved, and water resistance of the resulting film, binder The strength, surface strength and sealing ability can be further increased.

  N in the above formula (1) is preferably an integer of 6 or more and 20 or less. By setting n within the above range, the content of the crosslinking agent used in combination with the PVA can be reduced, and even when the crosslinking agent is not used, the water resistance and binder performance of the resulting film are fully exhibited. can do.

  The monomer unit is preferably represented by the following formula (2).

In said formula (2), the definition of R < ¹ > -R < ⁴ >, m, and n is the same as that of said formula (1). X is a direct bond, a divalent hydrocarbon group, or a divalent organic group containing an oxygen atom or a nitrogen atom. R ⁵ is a hydrogen atom or a methyl group.

  When the monomer unit has a structure represented by the formula (2), various performances of the coating agent can be further enhanced.

X in the above formula (2) represents —CO—NR ⁶ — * (R ⁶ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. * Represents a group represented by the above formula (1) and It is preferable that it is represented by the following. Thus, when the monomer unit has an amide structure at a position away from the silyl group, water solubility and viscosity stability can be further improved while maintaining the performance derived from the silyl group.

  X in the above formula (2) is represented by —CO—NH— * (* represents a bonding site with the group represented by the above formula (1)), and n is an integer of 12 or less. Good. By making the monomer unit into such a structure, the water solubility and viscosity stability of the PVA can be increased, and various properties of the film obtained by the coating agent can be enhanced. It can be done easily.

  The PVA including a monomer unit having a group represented by the above formula (2) saponifies a copolymer of an unsaturated monomer represented by the following formula (3) and a vinyl ester monomer. It is good that it is obtained by doing. By using PVA obtained by such a method, various characteristics of the coating agent can be more suitably exhibited.

In the above formula (3), the definitions of R ^{1 to} R ⁵ , X, m and n are the same as those in the above formula (2).

  The coated product of the present invention is a coated product obtained by coating the surface of the substrate with the coating agent. The coated material has a film that exhibits excellent water resistance, binder strength against inorganic materials, surface strength, and sealability. Moreover, the manufacturing method of the coated material of this invention has the process of coating the said coating agent on the base-material surface. The coated product can be easily obtained by the production method.

  As described above, the coating agent of the present invention has sufficient handleability and viscosity stability, and can obtain a film having high water resistance, binder strength against inorganic substances, surface strength, and sealability. In addition, the coated product of the present invention has a film showing excellent water resistance, binder strength against inorganic materials, surface strength and sealability, and the production method of the present invention can easily obtain the coated product. .

  Hereinafter, embodiments of the coating agent, the coated product, and the production method thereof of the present invention will be described in detail.

<Coating agent>
The coating agent of the present invention contains PVA described in detail below.

<PVA>
The PVA includes a monomer unit having a group represented by the formula (1). That is, the PVA is a copolymer containing a monomer unit having a group represented by the formula (1) and a vinyl alcohol unit (—CH ₂ —CHOH—), and further another monomer unit. You may have.

The formula (1), ^{R 1} is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group.

R ² is a group represented by an alkoxyl group, an acyloxyl group, or OM. M is a hydrogen atom, an alkali metal, or an ammonium group ( ⁺ NH ₄ ). Examples of the alkoxyl group include a methoxy group and an ethoxy group. Examples of the acyloxyl group include an acetoxy group and a propionyloxy group. Examples of the alkali metal include sodium and potassium. Among these groups represented by R ² , an alkoxyl group or a group represented by OM is preferable, and an alkoxyl group having 1 to 5 carbon atoms and a group represented by OM in which M is hydrogen or an alkali metal are more preferable. A methoxy group, an ethoxy group, and a group represented by OM in which M is sodium or potassium are more preferable.

R ³ and R ⁴ are each independently a hydrogen atom or an alkyl group. Examples of the alkyl group include the above-described alkyl groups having 1 to 5 carbon atoms. R ³ and R ⁴ are preferably a hydrogen atom or a methyl group.

The hydrogen atom which the alkyl group, alkoxyl group, and acyloxyl group represented by R ^{1 to} R ⁴ have may be substituted with a substituent containing an oxygen atom or a nitrogen atom. Examples of the substituent containing an oxygen atom include an alkoxyl group and an acyloxyl group. In addition, examples of the substituent containing a nitrogen atom include an amino group and a cyano group.

In ^the case where R 1 to R ⁴ is present in plural, each ^R 1 to R ⁴ that there are two or more, independently meets the above definition.

m is an integer of 0 to 2, and 0 is preferable. When m is 0, that is, the monomer unit has three R ² groups, the effect of modification can be further enhanced.

n is an integer of 3 or more. The upper limit of n is not particularly limited, but is, for example, 20 and is preferably 12. The PVA has a structure in which n in the formula (1) is 3 or more, that is, the silyl group is connected to the main chain via an alkylene group having 3 or more carbon atoms, so that the amount of modification of the silyl group Even if it raises, the fall of water solubility and viscosity stability is suppressed. The reason why such an effect appears is not sufficiently elucidated. For example, a hydrophobic alkylene group having 3 or more carbon atoms reduces the hydrolysis rate of Si—R ² in an aqueous solution, thereby causing a reaction. This is presumed to inhibit Further, n is more preferably an integer of 6 or more. By setting n in such a range, the content of the crosslinking agent usually used in combination with the above PVA can be reduced, and even when no crosslinking agent is used, the water resistance and binder performance of the resulting film are obtained. Can be fully demonstrated.

  The specific structure of the monomer unit is not particularly limited as long as it has a group represented by the above formula (1), but is preferably represented by the above formula (2).

In said formula (2), the definition of R < ¹ > -R < ⁴ >, m, and n is the same as that of said formula (1). The same applies to these preferred groups or numerical ranges.

  X is a direct bond, a divalent hydrocarbon group, or a divalent organic group containing an oxygen atom or a nitrogen atom. When the monomer unit has a structure represented by the above formula (2), various performances such as water solubility and viscosity stability, water resistance of the resulting film and binder performance can be further enhanced.

  Examples of the divalent hydrocarbon group include a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms and a divalent aromatic hydrocarbon group having 6 to 10 carbon atoms. Examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include a methylene group, an ethylene group, and a propylene group. Examples of the divalent aromatic hydrocarbon group having 6 to 10 carbon atoms include a phenylene group. Examples of the divalent organic group containing an oxygen atom include an ether group, an ester group, a carbonyl group, an amide group, and a group in which these groups are connected to a divalent hydrocarbon group. Examples of the divalent organic group containing a nitrogen atom include an imino group, an amide group, and a group in which these groups are connected to a divalent hydrocarbon group.

Among the groups represented by X, a divalent organic group containing an oxygen atom or a nitrogen atom is preferable, a group containing an amide group is more preferable, and —CO—NR ⁶ — * (R ⁶ is a hydrogen atom or a carbon atom) It is an alkyl group having 1 to 5 atoms. * Is more preferably a group represented by the bonding site with the group represented by the above formula (1). In this way, the monomer unit has a polar structure, preferably an amide structure, at a position away from the silyl group, so that the performance derived from the silyl group is maintained and the water solubility and viscosity stability are further improved. Can do. As the above R ^6, or more increase the above functions, in that it enables to easily perform production of the PVA, a hydrogen atom is preferable.

R ⁵ is a hydrogen atom or a methyl group.

  As said monomer unit, what is represented by following formula (4) is still more preferable.

In the above formula (4), the definitions of R ¹ , R ² , R ⁵ , X and m are the same as in the above formula (2). The same applies to these preferred groups or numerical ranges.

In the above formula (4), R ³ ′ and R ⁴ ′ are each independently a hydrogen atom or an alkyl group. Examples of the alkyl group include the above-described alkyl groups having 1 to 5 carbon atoms. R ³ ′ and R ⁴ ′ are preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom. The hydrogen atom contained in the alkyl group represented by R ³ ′ and R ⁴ ′ may be substituted with a substituent containing an oxygen atom or a nitrogen atom. Examples of the substituent containing an oxygen atom include an alkoxyl group and an acyloxyl group. In addition, examples of the substituent containing a nitrogen atom include an amino group and a cyano group. When there are a plurality of R ³ ′ and R ⁴ ′, a plurality of R ³ ′ and R ⁴ ′ satisfy the above definition independently.

  In the above formula (4), n ′ is an integer of 1 or more. The upper limit of n is not particularly limited, but is 18 for example and 10 is preferable.

When the monomer unit is represented by the above formula (4), various functions of the coating agent can be expressed more effectively. The reason for this is not clear, but it is presumed that the above-described function of reducing the hydrolysis rate of Si—R ² and inhibiting the reaction in the aqueous solution is more effectively exhibited.

The PVA satisfies the following formula (I).
370 ≦ P × S ≦ 6,000 (I)
P: Viscosity average degree of polymerization S: Content of the monomer unit (mol%)

The viscosity average degree of polymerization (P) is measured according to JIS-K6726. That is, when the saponification degree of the PVA is less than 99.5 mol%, the saponification degree is re-saponified to 99.5 mol% or more, and after purification, the intrinsic viscosity [η] measured in water at 30 ° C. (unit: (Deciliter / g) can be obtained by the following equation.
P = ([η] × 1000 / 8.29) ^{(1 / 0.62)}

The content of the monomer unit (S: mol%) can be obtained from proton NMR of the vinyl ester polymer before saponification. Here, when the proton NMR of the vinyl ester polymer before saponification is measured, the vinyl ester polymer is purified by reprecipitation with hexane-acetone, and the monomer having an unreacted silyl group is contained in the polymer. The body is sufficiently removed and then dried at 90 ° C. under reduced pressure for 2 days, and then dissolved in CDCl ₃ solvent for analysis.

The product (P × S) of the viscosity average degree of polymerization (P) and the content (S) of the monomer units corresponds to the number (average value) of the monomer units per 100 molecules. When this product (P × S) is less than the above lower limit, various properties derived from silyl groups such as water resistance and binder performance of a film obtained from the coating agent cannot be sufficiently exhibited. On the contrary, when this product (P × S) exceeds the above upper limit, water solubility and viscosity stability are lowered. The product (P × S) preferably satisfies the following formula (I ′), and more preferably satisfies the following formula (I ″).
400 ≦ P × S ≦ 3,000 (I ′)
500 ≦ P × S ≦ 2,000 (I ″)

The PVA preferably further satisfies the following formulas (II) and (III).
200 ≦ P ≦ 4,000 (II)
0.1 ≦ S ≦ 10 (III)
P: Viscosity average degree of polymerization S: Content of the monomer unit (mol%)

  Thus, by setting the viscosity average degree of polymerization (P) and the content (S) of the monomer unit in the above ranges, water solubility and viscosity stability, and water resistance, binder performance, and surface strength of the resulting film are obtained. In addition, the sealing property and the like can be improved.

Furthermore, in the viscosity average polymerization degree (P), it is more preferable to satisfy the following formula (II ′), and it is more preferable to satisfy the following formula (II ″).
500 ≦ P ≦ 3,000 (II ′)
1,000 ≦ P ≦ 2,400 (II ″)

  When the viscosity average degree of polymerization (P) is less than the lower limit, the water resistance, binder performance, etc. of the resulting film may be lowered. Conversely, when the viscosity average degree of polymerization (P) exceeds the above upper limit, water solubility, viscosity stability, etc. may be reduced.

Moreover, in the content rate of the said monomer unit, it is more preferable to satisfy | fill following formula (III '), and it is still more preferable to satisfy | fill following formula (III'').
0.25 ≦ S ≦ 6 (III ′)
0.5 ≦ S ≦ 5 (III ″)

  When the content rate (S) of the monomer unit is less than the lower limit, the water resistance, binder performance, and the like of the resulting film may be deteriorated. Conversely, when the monomer unit content (S) exceeds the above upper limit, water solubility, viscosity stability, and the like may decrease.

  Although there is no restriction | limiting in particular as the saponification degree of the said PVA, 80 mol% or more is preferable, 90 mol% or more is more preferable, 95 mol% or more is more preferable, 97 mol% or more is especially preferable. When the saponification degree of the PVA is less than the lower limit, the water resistance and the like of the resulting film may be lowered. The upper limit of the saponification degree of the PVA is not particularly limited, but is 99.9 mol%, for example, in consideration of productivity. Here, the saponification degree of PVA says the value measured according to the method of JIS-K6726.

<Method for producing PVA>
Although it does not specifically limit as a manufacturing method of the said PVA, For example, a copolymer obtained by copolymerizing a vinyl ester monomer and the monomer which has group represented by the said Formula (1) ( It can be obtained by saponifying a vinyl ester polymer).

  Examples of the vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, etc. Among these, vinyl acetate is preferable.

  In addition, for the purpose of adjusting the viscosity average polymerization degree (P) of the obtained PVA at the time of copolymerization of the monomer having a group represented by the above formula (1) and a vinyl ester monomer, Polymerization may be carried out in the presence of a chain transfer agent as long as the gist of the present invention is not impaired. Examples of the chain transfer agent include aldehydes such as acetaldehyde and propionaldehyde; ketones such as acetone and methyl ethyl ketone; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-hydroxyethanethiol, n-dodecanethiol, Mercaptans such as mercaptoacetic acid and 3-mercaptopropionic acid; and halogens such as tetrachloromethane, bromotrichloromethane, trichloroethylene and perchloroethylene.

  As a monomer which has group represented by the said Formula (1), the compound represented by the said Formula (3) can be mentioned, for example. By using the compound represented by the formula (3), finally, a PVA containing a monomer unit having a group represented by the formula (2) can be easily obtained.

In the above formula (3), the definitions of R ^{1 to} R ⁵ , X, m and n are the same as those in the above formula (2). The same applies to these preferred groups or numerical ranges.

  Examples of the compound represented by the above formula (3) include 3- (meth) acrylamidopropyltrimethoxysilane, 4- (meth) acrylamidobutyltrimethoxysilane, 8- (meth) acrylamideoctyltrimethoxysilane, and 6- (meta ) Acrylamide hexyltrimethoxysilane, 12- (meth) acrylamide dodecyltrimethoxysilane, 18- (meth) acrylamide octadecyltrimethoxysilane, 3- (meth) acrylamidepropyltriethoxysilane, 3- (meth) acrylamidopropyltributoxysilane , 3- (meth) acrylamidopropylmethyldimethoxysilane, 3- (meth) acrylamidopropyldimethylmethoxysilane, 3- (meth) acrylamide-3-methylbutyltrimethoxysilane, 4- (meth) Acrylamide-4-methylbutyltrimethoxysilane, 4- (meth) acrylamide-3-methylbutyltrimethoxysilane, 5- (meth) acrylamide-5-methylhexyltrimethoxysilane, 4-pentenyltrimethoxysilane, 5-to Examples include xenyl trimethoxysilane.

  Examples of the method for copolymerizing the vinyl ester monomer and the monomer having the group represented by the formula (1) include a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. A well-known method is mentioned. In particular, when the polymerization temperature is lower than 30 ° C., an emulsion polymerization method is preferable, and when the polymerization temperature is 30 ° C. or higher, a bulk polymerization method performed without solvent or a solution polymerization method performed using a solvent such as alcohol is used. Usually adopted.

  In the case of the emulsion polymerization method, examples of the solvent include water, and lower alcohols such as methanol and ethanol may be used in combination. Moreover, a well-known emulsifier can be used as an emulsifier. As an initiator for copolymerization, a redox initiator using iron ions, an oxidizing agent and a reducing agent in combination is preferably used for controlling the polymerization. In the case of the bulk polymerization method or the solution polymerization method, the reaction can be carried out by either a batch method or a continuous method in carrying out the copolymerization reaction. When the copolymerization reaction is carried out using the solution polymerization method, examples of the alcohol used as the solvent include lower alcohols such as methanol, ethanol, and propanol. Examples of the initiator used for the copolymerization reaction in this case include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 1,1′-azobis ( Azo initiators such as cyclohexane-1-carbonitrile) and 2,2′-azobis (N-butyl-2-methylpropionamide); peroxide initiators such as benzoyl peroxide and n-propyl peroxycarbonate And known initiators such as Although there is no restriction | limiting in particular about the polymerization temperature at the time of performing a copolymerization reaction, The range of 5 to 50 degreeC is suitable.

  In the case of this copolymerization reaction, a copolymerizable monomer can be copolymerized as necessary as long as the gist of the present invention is not impaired. Examples of such monomers include α-olefins such as ethylene, propylene, 1-butene, isobutene, and 1-hexene; carboxylic acids such as fumaric acid, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride, or the like Derivatives; (meth) acrylic acid or salts thereof or esters; acrylamide derivatives such as acrylamide, N-methylacrylamide, N-ethylacrylamide; methacrylamide derivatives such as methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether; ethylene glycol vinyl ether, 1,3-propanediol vinyl ether, 1, -Hydroxy group-containing vinyl ethers such as butanediol vinyl ether; allyl acetate; allyl ethers such as propyl allyl ether, butyl allyl ether, hexyl allyl ether; monomers having an oxyalkylene group; isopropenyl acetate; 3-butene-1 Hydroxy groups such as -ol, 4-penten-1-ol, 5-hexen-1-ol, 7-octen-1-ol, 9-decen-1-ol, 3-methyl-3-buten-1-ol Containing α-olefins; Monomers having sulfonic acid groups such as ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid; vinyloxyethyltrimethylammonium chloride, vinyloxybutyl Trimethylammonium chloride Vinyloxyethyldimethylamine, vinyloxymethyldiethylamine, N-acrylamidomethyltrimethylammonium chloride, N-acrylamidoethyltrimethylammonium chloride, N-acrylamidodimethylamine, allyltrimethylammonium chloride, methallyltrimethylammonium chloride, dimethylallylamine, allylethylamine, etc. And a monomer having a cationic group. The amount of these monomers used varies depending on the purpose and application of use, but is usually 20 mol% or less, preferably 10 mol, based on all monomers used for copolymerization. % Or less.

  The vinyl ester polymer obtained by the copolymerization is then saponified in a solvent according to a known method and led to PVA.

  As the catalyst for the saponification reaction, an alkaline substance is usually used, and examples thereof include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, and alkali metal alkoxides such as sodium methoxide. The amount of the alkaline substance used is preferably in the range of 0.004 to 0.5 in terms of a molar ratio based on the vinyl ester monomer unit in the vinyl ester polymer. More preferably, it is in the range of 0.05. Further, this catalyst may be added all at once in the early stage of the saponification reaction, or a part thereof may be added in the early stage of the saponification reaction, and the rest may be added in the middle of the saponification reaction.

  Examples of the solvent that can be used for the saponification reaction include methanol, methyl acetate, dimethyl sulfoxide, diethyl sulfoxide, dimethylformamide, and the like. Of these solvents, methanol is preferred. Further, in the use of methanol, the water content in methanol is preferably adjusted to 0.001 to 1% by mass, more preferably 0.003 to 0.9% by mass, and particularly preferably 0.005 to 0.8% by mass. It is good to be.

  The saponification reaction is preferably performed at a temperature of 5 to 80 ° C, more preferably 20 to 70 ° C. The time required for the saponification reaction is preferably 5 minutes to 10 hours, more preferably 10 minutes to 5 hours. The saponification reaction can be carried out by either a batch method or a continuous method. If necessary, the remaining saponification catalyst may be neutralized after completion of the saponification reaction. Examples of usable neutralizing agents include organic acids such as acetic acid and lactic acid, and ester compounds such as methyl acetate. Can do.

  The PVA obtained by the saponification reaction can be washed as necessary. Examples of the cleaning liquid used in this cleaning include lower alcohols such as methanol, lower fatty acid esters such as methyl acetate, and mixtures thereof. A small amount of water, alkali, acid, or the like may be added to these cleaning liquids.

  Although it does not specifically limit as a content rate of the said PVA in the said coating agent, 4 mass% or more and 20 mass% or less are preferable. According to the coating agent, since the concentration can be made relatively high in this way, the strength and water resistance of the resulting film can be effectively increased.

<Other ingredients>
The coating agent is usually an aqueous solution of the above PVA. However, it may be a solution using another solvent. The coating agent
Other solvents such as alcohols such as ethanol, ethers such as diethyl ether;
Alkali such as sodium hydroxide and ammonia;
Acids such as hydrochloric acid and acetic acid;
Albumin, gelatin, casein, starch, cationized starch, gum arabic, polyamide resin, melamine resin, poly (meth) acrylamide, polyvinylpyrrolidone, poly (meth) acrylate sodium, anion-modified PVA, sodium alginate, water-soluble polyester, and Water-soluble resins such as cellulose derivatives such as methylcellulose, hydroxyethylcellulose, and carboxymethylcellulose (CMC);
Water-dispersible resins such as SBR, NBR, vinyl acetate resins such as ethylene-vinyl acetate copolymer, (meth) acrylic acid ester resins, vinyl chloride resins;
Inorganic particles such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, precipitated silica, gelled silica, colloidal silica, aluminum oxide, aluminum hydroxide;
Glyoxal, aldehyde compounds such as glutaraldehyde, zirconium compounds such as ammonium zirconium carbonate, titanium compounds such as titanium lactate, epoxy compounds such as polyamidoamine epichlorohydrin, and cross-linking agents such as polyoxazoline;
Etc. may be included.

  Although it does not specifically limit as pH of the said coating agent, It is preferable to set it as 4-8. Since the PVA used in the coating agent is excellent in solubility in water, a uniform aqueous solution can be obtained without particularly adding an alkali or acid such as sodium hydroxide to water, and the handling property is excellent. Moreover, according to the coating agent, sufficient viscosity stability can be exhibited even in a neutral region.

  Specifically, the coating agent is a fiber processing agent, a glass fiber coating agent, a metal or glass surface coating agent, a coating agent such as an antifogging agent, a hydrophilicity imparting agent to a hydrophobic resin, a clear coating agent, White or colored coating agents containing pigments, other coating agents for forming ink receiving layers in ink jet recording materials, coating agents for forming overcoat layers and heat generating layers in heat sensitive recording materials, release paper It can be used as a coating agent for forming a coating layer on a base paper.

<Coated product and production method thereof>
The coated product of the present invention is a coated product obtained by coating the surface of the substrate with the coating agent. The coated material has a film that exhibits excellent water resistance, binder strength against inorganic materials, surface strength, and sealability. Moreover, the manufacturing method of the coated material of this invention has the process of coating the said coating agent on the base-material surface. The coated product can be easily obtained by the production method. After the coating agent is applied to the substrate, drying is usually performed.

  Although it does not specifically limit as said base material, Paper (including synthetic paper), cloth, a wooden board, a metal plate, a film, etc. can be mentioned. Among these, paper is preferable from the viewpoint of allowing the coating agent to penetrate into the base paper and improving water resistance and the like.

  The coating method is not particularly limited, and a known method such as a size press, an air knife coater, a roll coater, a bar coater, a blade coater, a curtain coater, or a cast coater can be employed.

  The coated product usually has a base material and a coating layer (film) formed by coating the coating agent on at least one surface of the base material. Another layer may be formed between or on the surface of the coating layer. However, in order to suitably exhibit excellent water resistance and the like of the coated product, it is preferable that the coating layer is formed on the outermost surface.

  Specifically, the coated product can be used as so-called coated paper such as art paper, coated paper, cast paper, heat-sensitive recording material, inkjet recording material, release paper base paper, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. In the following examples and comparative examples, unless otherwise specified, parts and% represent parts by mass and mass%, respectively.

In addition, the monomer (monomer A) which has the silyl group used by the Example and the comparative example is as follows.
MAmPTMS: 3-methacrylamideamidopropyltrimethoxysilane MAmPTES: 3-methacrylamideamidopropyltriethoxysilane MAmBTMS: 4-methacrylamidobutyltrimethoxysilane MAmOTMS: 8-methacrylamidooctyltrimethoxysilane MAmDDTMS: 12-methacrylamidododecyltrimethoxysilane MAmODTMS: 18-methacrylamidooctadecyltrimethoxysilane AMBTMS: 3-acrylamido-3-methylbutyltrimethoxysilane 4-PTMS: 4-pentenyltrimethoxysilane VMS: vinyltrimethoxysilane MAMTMTS: methacrylamidomethyltrimethoxysilane AMPTMS: 2 -Acrylamide-2-methylpropyltrimethoxysilane

[Synthesis of silyl group-containing PVA]
PVA is produced by the following method, the degree of saponification, the content of monomer units having a group represented by the above formula (1) (S) (in some examples, monomer units having a silyl group) Content) and viscosity average degree of polymerization (P). Moreover, according to the following evaluation methods, the performance of the film and the performance of the coated product were evaluated.

[Analysis method of PVA]
Analysis of PVA was performed according to the method described in JIS-K6726 unless otherwise specified.

[Synthesis Example 1] Production of PVA1 Into a 6 L separable flask equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, a comonomer dropping port and an initiator addition port, 1,500 g of vinyl acetate, 500 g of methanol, the above formula (1 ) MAmPTMS 1.87 g as a monomer (monomer A) having a group represented by) was charged, and the inside of the system was purged with nitrogen for 30 minutes while carrying out nitrogen bubbling. Further, a comonomer solution having a concentration of 8% was prepared by dissolving MAmPTMS in methanol as a delay solution, and nitrogen substitution was performed by bubbling nitrogen gas. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., 0.8 g of 2,2′-azobisisobutyronitrile (AIBN) was added to initiate polymerization. The delay solution was added dropwise to polymerize the monomer composition (ratio of vinyl acetate and monomer A (MAmPTMS)) in the polymerization solution at a constant rate for 2.7 hours at 60 ° C. and then cooled to stop the polymerization. . The total amount of comonomer solution (sequentially added solution) added until the polymerization was stopped was 99 g. Further, the solid content concentration when the polymerization was stopped was 29.0%. Subsequently, an unreacted vinyl acetate monomer is removed while sometimes adding methanol under reduced pressure at 30 ° C., and a methanol solution containing 40% of polyvinyl acetate (PVAc) having a group represented by the above formula (1) Got. Furthermore, a methanol solution containing 10% by mass of methanol and sodium hydroxide was added so that the molar ratio of sodium hydroxide to the vinyl acetate unit in PVAc was 0.04 and the solid content concentration of PVAc was 30% by mass. In this order, with stirring, the saponification reaction was started at 40 ° C. A gel was formed in about 5 minutes after the addition of the alkaline solution. This gel-like material was pulverized with a pulverizer and allowed to stand at 40 ° C. for 1 hour to allow saponification to proceed. Then, methyl acetate was added to neutralize the remaining alkali. After confirming the completion of neutralization using a phenolphthalein indicator, the mixture was filtered to obtain a white solid. Methanol was added thereto, and the mixture was allowed to wash at room temperature for 3 hours. After repeating the above washing operation three times, the white solid obtained by centrifugal drainage was left in a dryer at 65 ° C. for 2 days to obtain PVA1 having a group represented by the above formula (1). PVA1 had a viscosity average polymerization degree (P) of 1,700 and a saponification degree of 98.6 mol%.

The content of the monomer unit having the group represented by the above formula (1) of the obtained PVA1 (content of the monomer unit having a silyl group) is the proton NMR of PVAc which is a precursor of this PVA. I asked for it. Specifically, after reprecipitation purification of the obtained PVAc was sufficiently performed three times or more with n-hexane / acetone, drying was performed under reduced pressure at 50 ° C. for 2 days to prepare a PVAc for analysis. This PVAc was dissolved in CDCl ₃ and measured at room temperature using 500 MHz proton NMR (JEOL GX-500). From the peak α (4.7 to 5.2 ppm) derived from the main chain methine of the vinyl acetate unit and the peak β (3.4 to 3.8 ppm) derived from the methyl of the methoxy group of the monomer A unit, the following formula is obtained. The content (S) of the monomer unit having a group represented by the above formula (1) was calculated. In PVA1, the content (S) was 0.5 mol%. The results of analyzing the obtained PVA are shown in Table 1.
Content S (mol%) of the monomer unit having a group represented by the formula (1)
= {(Peak area of β / 9) / (peak area of α + (peak area of β / 9))} × 100

[Synthesis Examples 2-31 and Comparative Synthesis Examples 1-22] Production of PVA2-PVA53 Polymerization conditions such as the amount of vinyl acetate and methanol, the type and addition amount of monomer A, the concentration of PVAc during saponification, and the vinyl acetate unit PVA2 to PVA53 were obtained in the same manner as in Synthesis Example 1 except that the saponification conditions such as the molar ratio of sodium hydroxide were changed as shown in Tables 1 and 2. Tables 1 and 2 show the results of analysis for each obtained PVA.

[Examples 1-33 and Comparative Examples 1-24] Preparation of PVA aqueous solution (coating agent) About PVA1-PVA53, PVA aqueous solution (coating agent) was prepared so that it might become a predetermined density | concentration and pH. The viscosity stability of the PVA aqueous solution, the water resistance of the film, the water resistance of the film containing an inorganic substance, and the binder strength between the PVA and the inorganic substance were evaluated by the following evaluation methods. Table 3 shows the type of PVA used, the pH of the aqueous solution, and the evaluation results.

[Viscosity stability of PVA aqueous solution]
An 8% PVA aqueous solution was prepared and allowed to stand in a 20 ° C. constant temperature bath, and the viscosity immediately after the temperature of the PVA aqueous solution reached 20 ° C. and the viscosity after 7 days were measured. A value obtained by dividing the viscosity after 7 days by the viscosity immediately after the temperature of the PVA aqueous solution reached 20 ° C. (viscosity after 7 days / viscosity immediately after) was determined and determined according to the following criteria.
A: Less than 2.5 times B: 2.5 times or more and less than 3.0 times C: 3.0 times or more and less than 5.0 times D: Although 5.0 times or more, the PVA aqueous solution is not gelled.
E: The PVA aqueous solution loses fluidity and gels.

[Water resistance of film]
A 4% PVA aqueous solution was prepared and cast at 20 ° C. to obtain a film having a thickness of 40 μm. The obtained film was cut into a size of 10 cm in length and 10 cm in width to prepare a test piece. After this test piece was immersed in distilled water at 20 ° C. for 24 hours, it was taken out (collected), the water adhering to the surface was wiped off with gauze, and the mass at the time of water swelling was measured. The test piece whose weight during water swelling was measured was dried at 105 ° C. for 16 hours, and then the weight during drying was measured. Here, a value obtained by dividing the mass at the time of water swelling by the mass at the time of drying was obtained, and this was taken as the degree of swelling (times), and was judged according to the following criteria.
S: Less than 3.0 times A: 3.0 times or more and less than 5.0 times B: 5.0 times or more and less than 8.0 times C: 8.0 times or more and less than 10.0 times D: 10.0 times or more E: The immersed test piece cannot be collected.

[Water resistance of coatings containing inorganic substances]
A 20% aqueous dispersion of colloidal silica (manufactured by Nissan Chemical Industries: Snowtex ST-O) was prepared so that a 4% PVA aqueous solution was prepared and the mass ratio based on the solid content of PVA / colloidal silica was 100/10. After the addition, it was cast at 20 ° C. to obtain a film having a thickness of 40 μm. The obtained film was cut into a size of 10 cm in length and 10 cm in width to prepare a test piece. After this test piece was immersed in distilled water at 20 ° C. for 24 hours, it was taken out (collected), the water adhering to the surface was wiped off with gauze, and the mass at the time of water swelling was measured. The test piece whose weight during water swelling was measured was dried at 105 ° C. for 16 hours, and then the weight during drying was measured. Here, a value obtained by dividing the mass at the time of water swelling by the mass at the time of drying was obtained, and this was taken as the degree of swelling (times), and was judged according to the following criteria.
A: Less than 3.0 times B: 3.0 times or more and less than 5.0 times C: 5.0 times or more and less than 8.0 times D: 8.0 times or more and less than 10.0 times E: 10.0 times or more Or a soaked specimen cannot be recovered.

[Binder strength of PVA and inorganic substances]
Silica (manufactured by Mizusawa Chemical Co., Ltd .: Mizukasil P78D) and 0.2% of a dispersant (manufactured by Toagosei Chemical Industry Co., Ltd .: Aron T40) are dispersed in water with a homomixer, and a 20% aqueous dispersion of silica. Was prepared. To this silica aqueous dispersion, an aqueous PVA solution adjusted to 8% is added so that the mass ratio based on the solid content of silica / PVA is 100/20, and the above-mentioned silica and PVA are added by adding a necessary amount of water. A silica-dispersed PVA aqueous solution with a total concentration of 15% was obtained.
The obtained silica-dispersed PVA aqueous solution was applied to the surface of the fine paper with a basis weight of 60 g / m ² using a wire bar. Thereafter, the quality paper was dried at 100 ° C. for 3 minutes using a hot air dryer to obtain a sample for evaluation. The coating amount on high-quality paper (sample for evaluation) after drying was 11 g / m ² .
About the sample for evaluation, using an IGT print aptitude tester (manufactured by Kumagai Riki Kogyo Co., Ltd.), the measurement was performed at a printing pressure of 50 kg / cm ² , and the printing speed (cm / cm) when the surface of the evaluation sample was peeled off. sec) was used as the binder strength between PVA and inorganic matter, and the binder strength was evaluated according to the following criteria. In the measurement using an IGT printability tester, IGT pick oil M (manufactured by Dainippon Ink & Chemicals, Inc.) was used and a spring drive B mechanism was adopted.
A: 260 cm / sec or more B: 220 cm / sec or more and less than 260 cm / sec C: 180 cm / sec or more and less than 220 cm / sec D: 140 cm / sec or more and less than 180 cm / sec E: Less than 140 cm / sec

  As Table 3 shows, PVA (PVA1-31) obtained by the synthesis examples 1-31 has sufficient water solubility and viscosity stability, and the water resistance and binder performance (binder power of the obtained film | membrane) ) Is also excellent. Here, if the viscosity stability is D or more, it is considered that the viscosity stability is practically sufficient, the other three items are C or more, and at least one item is B. And Furthermore, the viscosity average degree of polymerization (P) of PVA, the degree of saponification, the structure of the monomer unit, the content (S), the product of the viscosity average degree of polymerization (P) and the content (S) (P × S), and an aqueous solution The aqueous solutions of Examples 1, 7, 9, 12, 14, 17-19, 23, 27-30, 32, and 33, which specified the pH of the film, had viscosity stability and water resistance and binder performance ( (Binder strength) is particularly excellent (viscosity stability is evaluated as C or more, and among other 3 items, 2 or more items are A or more, and others are B) For example, in the aqueous solutions of Examples 2, 3, 6, 8, 10, 11, 13, 15, 16, 20, 22 and 26, the viscosity stability and the water resistance of the obtained film may slightly decrease. I understand. This is due to a decrease in the viscosity average degree of polymerization (P) and saponification degree, and a product (P × S) of the viscosity average degree of polymerization (P) and the content rate (S) being small or large. Further, in Examples 4 and 5, it can be seen that the water resistance and binder strength of the film are lowered because the pH of the aqueous solution is acidic or alkaline. In Example 31, since the alkylene group connecting the silyl group and the main chain has a long carbon atom number of 18, the hydrophobic group interaction becomes too strong, and the viscosity stability is considered to be lowered.

On the other hand, when PVA does not satisfy the prescribed requirements (Comparative Examples 1 to 24), it can be seen that the water solubility and viscosity stability, the water resistance performance of the coating and the binder performance (binder power) are reduced. In addition, when Example 1 (PVA1) is compared with Comparative Example 14 (PVA43) and Comparative Example 16 (PVA45), the pH of the aqueous solution, the viscosity average degree of polymerization (P), the degree of saponification, and the content (S ) Is almost the same value, it can be seen that the water resistance and binder strength of the film are good in Example 1, and the viscosity stability is good in Example 1. The reason for this is not fully elucidated. However, in PVA1 of Example 1, due to the presence of an alkylene group having 3 or more carbon atoms connecting the main chain and the silyl group, (1) the mobility of the silyl group is increased. High, excellent in water resistance and binder strength of the film. (2) In addition, in aqueous solution, the alkylene group reduces the rate of hydrolysis of Si—R ² or inhibits the reaction, so that the viscosity stability is improved. it is conceivable that.

[Example 34] Manufacture of coated paper A coated paper (coated product) was manufactured by the following method, and the surface strength and air permeability resistance (measured as an index of sealing properties) of the prepared coated paper were measured. , And may be abbreviated as “air permeability”) and water resistance.

Basis weight: 60 g / m ² high-quality paper (base material) and 4% concentration of the above PVA1 aqueous solution (coating agent) by hand coating using a Mayer bar so that the coating amount is 0.5 g / m ^2. Worked. Then, after drying using a hot air dryer at 110 ° C. for 1 minute, the humidity is adjusted at 20 ° C. and 65% RH for 72 hours, and super calender treatment is performed under the conditions of 150 ° C., 250 Kg / cm, 10 m / min. The coated paper of Example 34 was obtained. About the obtained coated paper, the surface strength measurement, the air permeability test, and the water resistance test were implemented by the method shown below.

[Surface strength]
About the obtained coated paper, the surface strength was measured based on JIS-P8129 using the IGT printing aptitude test machine (made by Kumagai Riki Kogyo). That is, measurement is performed at a printing pressure of 25 kg / cm ^2, and the surface strength is determined by the printing speed (cm / sec) when the surface of the coated paper is peeled off. The surface strength of the surface was evaluated. In the measurement using an IGT printability tester, IGT pick oil M (manufactured by Dainippon Ink & Chemicals, Inc.) was used and a spring drive B mechanism was adopted.
A: 260 cm / sec or more B: 220 cm / sec or more and less than 260 cm / sec C: 180 cm / sec or more and less than 220 cm / sec D: 120 cm / sec or more and less than 180 cm / sec E: Less than 120 cm / sec

[Air permeability (seamability)]
It measured using the Oken type | formula lubricity air permeability tester according to JIS-P8117, and evaluated according to the following references | standards.
A: 100,000 seconds or more B: 50,000 seconds or more, less than 100,000 seconds C: 30,000 seconds or more, less than 50,000 seconds D: 10,000 seconds or more, less than 30,000 seconds E: 10,000 Less than 000 seconds

[Water resistance (wet lab test)]
After 1 ml of 20 ° C. ion-exchanged water was dropped on the coated surface of the coated paper, the portion was rubbed with a fingertip, and the number of times the fingertip was felt was measured and judged according to the following criteria.
S: 120 times or more A: 100 times or more, less than 120 times B: 50 times or more, less than 100 times C: 30 times or more, less than 50 times D: 10 times or more, less than 30 times E: Less than 10 times

[Examples 35-54 and Comparative Examples 25-37]
A coated paper was produced in the same manner as in Example 34 except that PVA shown in Table 4 was used instead of PVA1 used in Example 34. The surface strength, air permeability and water resistance of the obtained coated paper were evaluated. The results are also shown in Table 4.

  As shown in Table 4, it can be seen that the coated papers produced with the coating agents of Examples 34 to 54 have good surface strength, air permeability (sealing property) and water resistance of the coated paper. Here, it is assumed that each evaluation item is C or higher, and that two or more of the three items are B or higher. Furthermore, PVA viscosity average polymerization degree (P), saponification degree, monomer unit structure, content rate (S), and product of viscosity average polymerization degree (P) and content rate (S) (P × S) are specified. The coating agents of Examples 34 to 41, 46, 48, 49, 50, 51, 53 and 54 are particularly excellent in the surface strength, air permeability (sealing property) and water resistance of the coated paper. In addition, it turns out that the surface strength, the air permeability (sealing property), and water resistance of the coating agents of Examples 42 to 45, 47, and 52 are slightly lowered. This is thought to be due to a decrease in the viscosity average polymerization degree (P) and saponification degree, and the difference in the structure of the monomer units.

  On the other hand, when PVA does not satisfy the prescribed requirements (Comparative Examples 25 to 37), it can be seen that the surface strength, air permeability (sealing property) and water resistance of the coated paper are lowered. This is considered to be due to the difference in the structure of the monomer units and the product (P × S) of the viscosity average polymerization degree (P) and the content rate (S) being small or large.

  As described above, the coating agent of the present invention can be suitably used, for example, when producing coated paper.

Claims (8)

The coating agent containing the vinyl alcohol polymer which contains the monomer unit which has group represented by following formula (1), and satisfy | fills following formula (I).

(In Formula (1), R ¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ² is an alkoxyl group, an acyloxyl group, or a group represented by OM. M is a hydrogen atom. R ³ and R ⁴ each independently represents a hydrogen atom or an alkyl group, and a hydrogen atom possessed by an alkyl group, an alkoxyl group, or an acyloxyl group represented by R ^{1 to} R ^4. May be substituted with a substituent containing an oxygen atom or a nitrogen atom, m is an integer of 0 to 2, n is an integer of 6 to 20 , and R ^{1 to} R ⁴ are each In the case where a plurality of R ^{1 to} R ⁴ are present, each of R ^{1 to} R ⁴ independently satisfies the above definition.)
370 ≦ P × S ≦ 6,000 (I)
P: Viscosity average degree of polymerization S: Content of the monomer unit (mol%) The coating agent according to claim 1, wherein the vinyl alcohol polymer further satisfies the following formulas (II) and (III).
200 ≦ P ≦ 4,000 (II)
0.1 ≦ S ≦ 10 (III)
P: Viscosity average degree of polymerization S: Content of the monomer unit (mol%) The coating agent according to claim 1 or 2 , wherein the monomer unit is represented by the following formula (2).

(In formula (2), the definitions of R ^{1 to} R ⁴ , m and n are the same as those in formula (1). X represents a direct bond, a divalent hydrocarbon group, an oxygen atom or a nitrogen atom 2. R ⁵ is a hydrogen atom or a methyl group.) X in the above formula (2) is —CO—NR ⁶ — * (R ⁶ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. * Is a group represented by the above formula (1); The coating agent according to claim 3 , which is represented by: X in the above formula (2) is represented by —CO—NH— * (* represents a bonding site with the group represented by the above formula (1)), and n is an integer of 12 or less. Item 4. The coating agent according to Item 3 . Billing the vinyl alcohol polymer is from claim 3 is obtained by saponifying a copolymer of an unsaturated monomer and a vinyl ester monomer represented by the following formula (3) Item 6. The coating agent according to any one of Items 5 .

(In formula (3), definitions of R ^{1 to} R ⁵ , X, m and n are the same as in formula (2).) A coated product obtained by coating the surface of the substrate with the coating agent according to any one of claims 1 to 6 . The manufacturing method of the coated material which has the process of applying the coating agent of any one of Claim 1 to 6 to the base-material surface.