Resin particle dispersion for paper coating

Abstract

To provide a resin particle dispersion for paper coating capable of obtaining coated paper excellent in water repellency and water resistance, a coating liquid for paper containing the resin particle dispersion, coated paper using the coating liquid, and a method for producing the coated paper.SOLUTION: A resin particle dispersion for paper coating contains resin particles containing a polyester-based resin X, wherein the polyester-based resin X contains a silicone-modified polyester resin A that is a reaction product of an alcohol component containing a dihydric or higher hydric alcohol, a carboxylic acid component containing one or more selected from an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid, and a modified silicone having an amino group, an epoxy group, a hydroxy group, or a carboxy group in a side chain, at one terminal, or at both terminals. There are provided a resin particle dispersion for paper coating, a coating liquid for paper containing the resin particle dispersion, coated paper using the coating liquid, and a method for producing the coated paper.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin particle dispersion for paper coating, a paper coating fluid containing the resin particle dispersion, coated paper using the coating fluid, and a method for producing the coated paper. [Background technology]

[0002] Conventionally, paper materials that can be used for paper labels, packaging paper, paper containers, and the like that require water resistance have been those laminated with plastic films such as polyethylene film or polypropylene to impart water resistance or water repellency. However, paper laminated with plastic films is difficult to recycle. Therefore, with the recent increase in environmental awareness, there has been a demand for and investigation of technologies that can impart water resistance or water repellency as an alternative to lamination.

[0003] For example, Patent Document 1 discloses a moisture-proof laminate having high moisture-proof properties and capable of being recycled as waste paper, in which a moisture-proof composition layer made of a tabular pigment having an aspect ratio of 5 or more and an average particle size of 5 to 50 μm and a synthetic resin is formed on at least one surface of a paper support, and 0.1 to 10 g / m is applied to the moisture-proof composition layer. 2 The document describes a moisture-proof laminate in which a coating layer made of a crosslinked product of the water-soluble resin is provided. Patent Document 2 describes a water-soluble functional compound having a structure in which a secondary amino group of a branched polyethyleneimine, or both a primary and a secondary amino group, and an epoxy-modified silicone at one end are grafted, with the aim of providing a functional compound that can impart functions such as water resistance and water repellency. Patent Document 3 describes a paper coating agent that is environmentally friendly, water-resistant, and oil-resistant, and that contains a copolymer emulsion in which a silicone polymer containing a repeating unit represented by a specific chemical formula and an acrylic polymer containing a repeating unit represented by a specific chemical formula are copolymerized, and the weight-average molecular weight of particles contained in the copolymer emulsion is within a specific range, and a polyvinyl alcohol colloidal aqueous solution that has been gelatinized so that it can be mixed with the copolymer emulsion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-268494 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-178895 [Patent Document 3] Special Publication No. 2019-522741 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the techniques of Patent Documents 1 to 3 have not been able to achieve sufficient water repellency and water resistance like paper laminated with a plastic film. An object of the present invention is to provide a resin particle dispersion for paper coating that can provide coated paper with excellent water repellency and water resistance, a paper coating fluid containing the resin particle dispersion, coated paper using the coating fluid, and a method for producing the coated paper. [Means for solving the problem]

[0006] The inventors believed that it would be effective to have a water-repellent and water-resistant material on the surface of a paper substrate, and discovered that the above-mentioned problem could be solved by forming a coating layer on the surface of a paper substrate using a resin particle dispersion in which a resin component containing a silicone-modified polyester resin containing silicone in its structure is dispersed in an aqueous medium.

[0007] That is, the present invention provides the following [1] to [4]. [1] A resin particle dispersion for paper coating containing resin particles containing a polyester-based resin X, The polyester resin X contains a silicone-modified polyester resin A, which is a reaction product of an alcohol component containing a dihydric or higher alcohol, a carboxylic acid component containing at least one selected from aromatic dicarboxylic acids and aliphatic dicarboxylic acids, and a modified silicone having an amino group, an epoxy group, a hydroxy group, or a carboxy group at a side chain, one end, or both ends. [2] A paper coating liquid containing the resin particle dispersion liquid described in [1] above. [3] Coated paper having a coating layer formed by applying the coating liquid described in [2] above to at least one side of a paper substrate. [4] A method for producing coated paper, comprising step 1 of applying the coating liquid described in [2] above to at least one side of a paper substrate, and step 2 of drying the coating liquid on the paper substrate coated in step 1. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a resin particle dispersion for paper coating that can produce coated paper with excellent water repellency and water resistance, a paper coating fluid containing the resin particle dispersion, coated paper using the coating fluid, and a method for producing the coated paper. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Resin particle dispersion for paper coating] The resin particle dispersion for paper coating of the present invention (hereinafter simply referred to as "resin particle dispersion") is a resin particle dispersion for paper coating containing resin particles (hereinafter simply referred to as "resin particles") that contain a polyester-based resin X, and the polyester-based resin X contains a silicone-modified polyester resin A that is a reaction product of an alcohol component containing a dihydric or higher alcohol, a carboxylic acid component containing at least one selected from aromatic dicarboxylic acids and aliphatic dicarboxylic acids, and a modified silicone having an amino group, an epoxy group, a hydroxy group, or a carboxy group at a side chain, one end, or both ends.

[0010] In the present invention, the term "carboxylic acid component" includes not only carboxylic acids but also their anhydrides and alkyl esters having from 1 to 3 carbon atoms. In other words, when the name of a carboxylic acid is mentioned in this specification, it is understood that the mention also includes the anhydrides and alkyl esters having from 1 to 3 carbon atoms of the carboxylic acid.

[0011] The resin particle dispersion of the present invention is preferably one in which resin particles are dispersed in an aqueous medium. Here, "aqueous" means that water accounts for the largest proportion of the medium. As the water for the aqueous medium, deionized water, ion-exchanged water or distilled water is preferably used. The aqueous medium may further contain an organic solvent, such as aliphatic alcohols having from 1 to 4 carbon atoms, such as methanol, ethanol, and 2-propanol; ketones having from 3 to 8 carbon atoms, such as acetone and methyl ethyl ketone; and ethers, such as diethyl ether and tetrahydrofuran. From the viewpoint of environmental friendliness, the water content in the aqueous medium is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and preferably 100% by mass or less, even more preferably 100% by mass.

[0012] According to the present invention, coated paper with excellent water repellency and water resistance can be obtained. The reason for this is not clear, but is thought to be as follows. Silicone is an organosilicon polymer known for its high water repellency. However, simply applying silicone oil to a paper substrate generally results in rapid penetration into the substrate, leaving an oily stain, and the resulting paper is not water repellent. On the other hand, polyester resins obtained by polycondensation of alcohol components and carboxylic acid components have highly polar ester bonds in their polymer backbone and numerous terminal groups such as hydroxyl groups and carboxyl groups, making them highly compatible with paper. Therefore, in the present invention, a silicone structure is introduced into a polyester resin using a reaction product of an alcohol component, a carboxylic acid component, and a modified silicone having an amino group, an epoxy group, a hydroxy group, or a carboxy group on a side chain, one end, or both ends, to use a resin having a moiety with high affinity for paper and a moiety capable of imparting water repellency to paper in the polymer skeleton. A dispersion of resin particles containing such a resin is then used as a coating liquid to coat a paper substrate to produce paper. This allows for the formation of a coating layer on the surface of the paper substrate in which the polyester resin moieties are oriented at the interface with the paper substrate and the silicone moieties are oriented at the surface of the coating layer, i.e., the interface with air, thereby achieving water repellency and water resistance.

[0013] <Polyester Resin X> In the present invention, the polyester resin X contained in the resin particles contains a silicone-modified polyester resin A (hereinafter also simply referred to as "modified polyester resin A"). The modified polyester resin A is a reaction product of an alcohol component containing a dihydric or higher alcohol, a carboxylic acid component containing at least one selected from aromatic dicarboxylic acids and aliphatic dicarboxylic acids, and a modified silicone having an amino group, an epoxy group, a hydroxy group, or a carboxy group at a side chain, one end, or both ends.

[0014] [Silicone-modified polyester resin A] (alcohol content) The alcohol component constituting the modified polyester resin A (hereinafter, also simply referred to as "alcohol component") contains a dihydric or higher alcohol. The alcohol component may be used alone or in combination of two or more. Examples of dihydric or higher alcohols include diols and trihydric or higher polyhydric alcohols. The diol includes an aromatic diol and an aliphatic diol. Examples of aromatic diols include alkylene oxide adducts of bisphenol A. In the present invention, the term "alkylene oxide adduct of bisphenol A" refers to the entire structure in which alkylene oxide is added to 2,2-bis(4-hydroxyphenyl)propane. From the viewpoint of improving water repellency and water resistance, the alkylene oxide adduct of bisphenol A is preferably a compound represented by the following general formula (I).

[0015] [ka]

[0016] In the general formula (I), OR 1 , and R 2 Each O is an alkyleneoxy group, and from the viewpoint of improving water repellency and water resistance, preferably, each O is independently an alkyleneoxy group having from 1 to 4 carbon atoms, more preferably, an ethyleneoxy group or a propyleneoxy group, and even more preferably, a propyleneoxy group. x and y correspond to the number of moles of alkylene oxide added. Furthermore, from the viewpoint of reactivity with the carboxylic acid component, the average value of the sum of x and y is preferably 2 or more. From the same viewpoint, the average value of the sum of x and y is preferably 7 or less, more preferably 5 or less, and even more preferably 3 or less. x ORs 1 and y R 2The O's may be the same or different, but are preferably the same from the viewpoint of improving the adhesion of the coating layer to paper. The alkylene oxide adducts of bisphenol A may be used alone or in combination of two or more. From the viewpoint of improving water repellency and water resistance, the alkylene oxide adduct of bisphenol A is preferably at least one selected from a propylene oxide adduct of bisphenol A and an ethylene oxide adduct of bisphenol A, more preferably a propylene oxide adduct of bisphenol A.

[0017] Examples of the aliphatic diol include linear or branched aliphatic diols having 2 to 20 carbon atoms, and alicyclic aliphatic diols. Examples of linear or branched aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, and 3,3-dimethyl-1,2-butanediol. Examples of the alicyclic aliphatic diol include cyclohexanediol and hydrogenated bisphenol A. Examples of trihydric or higher polyhydric alcohols include glycerin, pentaerythritol, trimethylolpropane, sorbitol, and sorbitan.

[0018] Among these, the alcohol component constituting the modified polyester resin A preferably contains an aromatic diol, and more preferably contains an alkylene oxide adduct of bisphenol A, from the viewpoint of improving water repellency and water resistance. From the viewpoint of improving water repellency and water resistance, the content of aromatic diol in the alcohol component constituting modified polyester resin A is preferably 60 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more, and preferably 100 mol% or less.

[0019] (carboxylic acid component) The carboxylic acid component constituting the modified polyester resin A (hereinafter also simply referred to as "carboxylic acid component") contains at least one selected from aromatic dicarboxylic acids and aliphatic dicarboxylic acids. The carboxylic acid component may be used alone or in combination of two or more. Examples of aromatic dicarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, etc. Among these, from the viewpoint of improving water repellency and water resistance, the aromatic dicarboxylic acid is preferably isophthalic acid or terephthalic acid, and more preferably terephthalic acid. Examples of aliphatic dicarboxylic acids include straight-chain, branched-chain, and alicyclic aliphatic dicarboxylic acids such as fumaric acid, adipic acid, sebacic acid, maleic acid, azelaic acid, succinic acid, succinic acid substituted with a hydrocarbon group having from 1 to 20 carbon atoms, and cyclohexanedicarboxylic acid. Specific examples of succinic acid substituted with a hydrocarbon group having from 1 to 20 carbon atoms include dodecylsuccinic acid, dodecenylsuccinic acid, and octenylsuccinic acid. Of these, the aliphatic dicarboxylic acid is preferably fumaric acid from the viewpoint of improving water repellency and water resistance.

[0020] From the viewpoint of improving water repellency and water resistance, the total content of aromatic dicarboxylic acid and aliphatic dicarboxylic acid in the carboxylic acid component constituting the modified polyester resin A is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and preferably 100 mol% or less.

[0021] From the viewpoint of improving water repellency and water resistance, the carboxylic acid component constituting the modified polyester resin A preferably contains an aromatic dicarboxylic acid, more preferably contains one or more selected from isophthalic acid and terephthalic acid, and even more preferably contains terephthalic acid. From the viewpoint of improving water repellency and water resistance, the content of aromatic dicarboxylic acid in the carboxylic acid component constituting the modified polyester resin A is preferably 45 mol% or more, more preferably 50 mol% or more, even more preferably 55 mol% or more, and is preferably 100 mol% or less, more preferably 90 mol% or less, even more preferably 80 mol% or less, and even more preferably 70 mol% or less.

[0022] The carboxylic acid component constituting the modified polyester resin A preferably contains a trivalent or higher polycarboxylic acid, more preferably a trivalent or higher aromatic polycarboxylic acid, from the viewpoint of improving water repellency and water resistance. Examples of aromatic polycarboxylic acids having a valence of three or more include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, and pyromellitic acid. Of these, trimellitic acid is preferred. From the viewpoint of improving water repellency and water resistance, the content of the trivalent or higher aromatic polycarboxylic acid in the carboxylic acid component constituting the modified polyester resin A is preferably 3 mol% or more, more preferably 5 mol% or more, even more preferably 7 mol% or more, still more preferably 10 mol% or more, and is preferably 35 mol% or less, more preferably 25 mol% or less, even more preferably 20 mol% or less, and still more preferably 15 mol% or less.

[0023] The equivalent ratio (COOH groups / OH groups) of the carboxyl groups (COOH groups) of the carboxylic acid component to the hydroxyl groups (OH groups) of the alcohol component constituting the modified polyester resin A is preferably 0.65 or more, more preferably 0.75 or more, and preferably 1.2 or less.

[0024] (Modified silicone) The modified silicone has an amino group, an epoxy group, a hydroxy group, or a carboxy group on a side chain, at one end, or at both ends. The amino group, epoxy group, hydroxy group, and carboxy group are collectively referred to as "reactive groups," and a group containing a reactive group and another moiety is also referred to as "reactive group-containing group."

[0025] [Modified silicone having reactive groups on the side chains] The modified silicone having a reactive group on the side chain is preferably a silicone represented by the formula (1-1): [ka] [In the formula, R 11 are each independently a hydrocarbon group having 1 to 6 carbon atoms, and R 12 are each independently an alkylene group having 1 to 10 carbon atoms, a is 1 or 0, and X 1 are each independently a group containing an amino group, an epoxy group, a hydroxy group, or a carboxy group, and * is a bonding site.] and a repeating unit represented by formula (1-2): [ka] [In the formula, R 11 are each independently a hydrocarbon group having 1 to 6 carbon atoms, and * is a bonding site.

[0026] The silicone terminal has the formula (1-3): [ka] [In the formula, R 13 is a hydrocarbon group having 1 to 10 carbon atoms, and * is a bonding site.

[0027] R 11 The hydrocarbon group has 6 or less carbon atoms, preferably 4 or less, more preferably 3 or less, even more preferably 2 or less, and still more preferably 1 carbon atom. R 11Examples of the hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, a pentyl group, and a phenyl group. Of these, a methyl group is preferred. R 12 The alkylene group has 10 or less, preferably 8 or less, more preferably 5 or less, even more preferably 4 or less, still more preferably 3 or less, even more preferably 2 or less, and still more preferably 1 carbon atom. R 12 Examples of the alkylene group include methanediyl, ethane-1,2-diyl, ethane-1,1-diyl, n-propane-1,3-diyl, n-propane-1,2-diyl, 1,4-n-butyl, 1,2-tert-butyl, and 1,5-pentyl. Of these, methanediyl is preferred. R 13 The hydrocarbon group has 10 or less, preferably 8 or less, more preferably 6 or less, even more preferably 4 or less, still more preferably 3 or less, even more preferably 2 or less, and still more preferably 1 carbon atom. R 13 Examples of the hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, a pentyl group, and a benzyl group.

[0028] X 1 are each independently a group containing an amino group, an epoxy group, a hydroxy group, or a carboxy group, and X is a reactive group or a group containing a reactive group. In formula (1-1), when a is 1, X 1 is a reactive group, and when a is 0, X 1 is a reactive group-containing group. When a is 0, X 1 may have an ether bond, or may be a hydrocarbon group in which some methylene groups are substituted with ether bonds and one or more reactive groups are substituted thereon. 1 may be an aliphatic hydrocarbon group substituted with one or more amino groups, epoxy groups, hydroxy groups, or carboxy groups, which may contain an ether bond; X1 The total number of carbon atoms is preferably 10 or less, more preferably 9 or less, and is preferably 1 or more, more preferably 2 or more. The aliphatic hydrocarbon group containing an ether bond refers to an aliphatic hydrocarbon group having an ether bond (—O—) between carbon-carbon bonds.

[0029] When the modified silicone is a silicone having an amino group on the side chain, X 1 is a group containing an amino group. In this case, in formula (1-1), a is 1 or 0, and X 1 are each independently -NH or -R 14 -NH-R 14 -NH2 and R 14 are each independently preferably an alkylene group having 1 to 5 carbon atoms, and when a is 1, X 1 is -NH2, and when a is 0, X is -R 14 -NH-R 14 More preferably, a is 1 and X is —NH2. 1 is -NH2 and R 12 is more preferably an alkylene group having 1 to 10 carbon atoms.

[0030] When the modified silicone is a silicone having an epoxy group on the side chain, X 1 is a group containing an epoxy group. In this case, in formula (1-1), a is 1, and X 1 is an epoxy group, or a is 0, and X 1 However, it is preferably an aliphatic hydrocarbon group containing an epoxy group and having 1 to 10 carbon atoms and optionally containing an ether bond, and more preferably an aliphatic hydrocarbon group containing an epoxy group and having 1 to 6 carbon atoms and optionally containing an ether bond.

[0031] When the modified silicone is a silicone having a hydroxy group on the side chain, X 1 is a group containing a hydroxy group. In this case, in formula (1-1), a is 1, and X 1 is a hydroxy group, or a is 0 and X 1is preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms and optionally containing an ether bond, substituted with a hydroxy group, more preferably an aliphatic hydrocarbon group having 1 to 6 carbon atoms and optionally containing an ether bond, substituted with a hydroxy group, and X 1 The number of hydroxy groups contained in is 1 or more, preferably 5 or less, more preferably 4 or less, and even more preferably 2 or less.

[0032] When the modified silicone is a silicone having a carboxyl group on the side chain, X 1 is a group containing a carboxy group. If a is 1, then X 1 is preferably a carboxy group, and in this case, R 12 is preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 5 carbon atoms, and even more preferably an alkylene group having 1 to 3 carbon atoms. If a is 0, then X 1 is preferably an aliphatic hydrocarbon group containing an ether bond and having 1 to 10 carbon atoms and substituted with a carboxy group, more preferably an aliphatic hydrocarbon group containing an ether bond and having 1 to 6 carbon atoms and substituted with a carboxy group.

[0033] When the modified silicone is one or more selected from silicones having an amino group on the side chain, silicones having an epoxy group on the side chain, silicones having a hydroxy group on the side chain, and silicones having a carboxy group on the side chain, *-(R 12 ) a -X 1 Examples of the group represented by the formula include the following substituents. [ka]

[0034] Commercially available modified silicones having amino groups on the side chains include, for example, "KF-868," "KF-865," "KF-864," and "X-22-3939A" (manufactured by Shin-Etsu Chemical Co., Ltd.). Commercially available modified silicones having epoxy groups on the side chains include, for example, "KF-101," "KF-1001," and "X-22-343" (manufactured by Shin-Etsu Chemical Co., Ltd.). An example of a commercially available modified silicone having a hydroxy group on the side chain is "X-22-4039" (manufactured by Shin-Etsu Chemical Co., Ltd.). An example of a commercially available modified silicone having a carboxy group on the side chain is "X-22-3701E" (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0035] [Modified silicone having a reactive group at one or both ends] The modified silicone having a reactive group at one or both ends is preferably a silicone represented by the formula (2-1): [ka] [In the formula, R 21 are each independently a hydrocarbon group having 1 to 6 carbon atoms, and R 22 are each independently an alkylene group having 1 to 10 carbon atoms, and R 23 are each independently a hydrocarbon group having 1 to 10 carbon atoms, 2 are each independently an amino group, an epoxy group, a glycidyl group, a glycidyloxy group, an alicyclic epoxy group, a hydroxy group, a hydroxyalkyloxy group, a carboxy group, or a carboxyalkyloxy group, s is an integer of 1 or more and 3 or less, t is an integer of 0 or more and 3 or less, and n is an integer of 5 or more and 300 or less.

[0036] R 21 The hydrocarbon group has 6 or less carbon atoms, preferably 5 or less, more preferably 4 or less, even more preferably 3 or less, still more preferably 2 or less, and even more preferably 1 carbon atom. R 21 Examples of the hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, a pentyl group, and a phenyl group. Of these, a methyl group is preferred. R 22The alkylene group has 10 or less carbon atoms, preferably 8 or less, more preferably 5 or less, even more preferably 4 or less, and even more preferably 3 or less carbon atoms, and preferably 1 or more, more preferably 2 or more. R 22 Examples of the alkylene group include methanediyl, ethane-1,2-diyl, ethane-1,1-diyl, n-propane-1,3-diyl, n-propane-1,2-diyl, 2-methylethane-1,2-diyl, 1,4-n-butyl, 1,2-tert-butyl, and 1,5-pentyl. Among these, ethane-1,2-diyl, n-propane-1,3-diyl, and n-propane-1,2-diyl are preferred, with n-propane-1,2-diyl being more preferred. R 23 The hydrocarbon group has 10 or less, preferably 8 or less, more preferably 6 or less, even more preferably 4 or less, still more preferably 3 or less, even more preferably 2 or less, and still more preferably 1 carbon atom. R 23 Examples of the hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, a pentyl group, and a benzyl group. X 2 is a group containing an amino group, an epoxy group, a hydroxy group, or a carboxy group. s is 3 or less, preferably 2 or less, and more preferably 1. t is 3 or less, preferably 2 or less, and more preferably 0 or 1. n is 300 or less, preferably 200 or less, more preferably 100 or less, and even more preferably 50 or less, and is 5 or more, preferably 8 or more, and more preferably 10 or more.

[0037] The modified silicone having an amino group at one or both ends includes X 2 are preferably each independently an amino group. R 22 X 2 Examples of the group represented by the formula include the following substituents. 22 X2 is preferably the substituent 2a-1 or the substituent 2a-2, more preferably the substituent 2a-1. * is a bonding site with Si. [ka]

[0038] Examples of modified silicones having amino groups at one or both ends include silicones modified with amino groups at both ends (commercially available products include "X-22-161A," "KF-8012," and "KF-8008" (all manufactured by Shin-Etsu Chemical Co., Ltd.)).

[0039] The modified silicone having an epoxy group at one or both ends includes X 2 are preferably each independently an epoxy group, a glycidyl group, a glycidyloxy group, or an alicyclic epoxy group. R 22 X 2 Examples of the group represented by the formula include the following substituents 2b-1 to 2b-3. 22 X 2 The group represented by the following formula is preferably the substituent 2b-1. * is a bonding site with Si. [ka]

[0040] Examples of modified silicones having epoxy groups at one or both ends include silicones modified with epoxy groups at both ends (commercially available products include "KF-105," "X-22-163A," "X-22-163B," "X-22-163C," "X-22-169AS," and "X-22-169B" (all manufactured by Shin-Etsu Chemical Co., Ltd.)), and silicones modified with epoxy groups at one end (commercially available products include "X-22-173BX" and "X-22-173DX" (all manufactured by Shin-Etsu Chemical Co., Ltd.)).

[0041] The modified silicone having a hydroxy group at one or both ends is X 2are each independently a hydroxy group or a hydroxyalkyloxy group. The hydroxyalkyloxy group may have a plurality of hydroxy groups. The number of carbon atoms in the hydroxyalkyl group is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. R 22 X 2 Examples of the group represented by the formula include the following substituents. 22 X 2 is preferably the substituent 2c-1 or the substituent 2c-2, more preferably the substituent 2c-1. * is a bonding site with Si. [ka]

[0042] Examples of modified silicones having hydroxy groups at one or both ends include silicones modified with carbinol at both ends (commercially available products include KF-6000, KF-6001, KF-6002, and KF-6003, all manufactured by Shin-Etsu Chemical Co., Ltd.)) and silicones modified with carbinol at one end (commercially available products include X-22-170BX, X-22-170DX, X-22-176DX, and X-22-176GX-A, all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0043] The modified silicone having a carboxyl group at one or both ends is X 2 are preferably each independently a carboxy group or a carboxyalkyloxy group. The carboxyalkyloxy group may have a plurality of carboxy groups. R 22 X 2 Examples of the group represented by the formula include the following substituent 2d-1: * is a bonding site with Si. [ka]

[0044] Examples of modified silicones having carboxy groups at one or both ends include silicone modified with carboxy groups at both ends (commercially available products include "X-22-162C" (manufactured by Shin-Etsu Chemical Co., Ltd.)) and silicone modified with carboxy groups at one end (commercially available products include "X-22-3710" (manufactured by Shin-Etsu Chemical Co., Ltd.)).

[0045] Among these, from the viewpoint of reactivity with the alcohol component or carboxylic acid component and improving water repellency and water resistance, the modified silicone preferably has an amino group, an epoxy group, a hydroxy group, or a carboxy group in the side chain, and more preferably has an amino group or an epoxy group in the side chain.

[0046] The kinematic viscosity of the modified silicone is preferably 10 mm at 25°C. 2 / s or more, preferably 15 mm 2 / s or more, more preferably 20 mm 2 / s or more, and preferably 20,000 mm 2 / s or less, preferably 10,000 mm 2 / s or less, more preferably 5,000 mm 2 / s or less, and even more preferably 2,000 mm 2 / s or less, and even more preferably 1,000 mm 2 / s or less, and even more preferably 500 mm 2 / s or less, and even more preferably 400 mm 2 / s or less, and even more preferably 300 mm 2 / s or less. The kinematic viscosity of the modified silicone is measured at 25°C using a fully automatic micro kinematic viscometer (manufactured by Viscotec Co., Ltd.). The functional group equivalent of the modified silicone is preferably 500 g / mol or more, more preferably 1,000 g / mol or more, even more preferably 2,000 g / mol or more, and preferably 20,000 g / mol or less, more preferably 10,000 g / mol or less, even more preferably 7,000 g / mol or less. The functional group equivalent means the mass of the modified silicone per mole of functional group.

[0047] The content of the modified silicone in the modified polyester resin A is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 2 parts by mass or more, still more preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more, relative to 100 parts by mass of the total amount of the alcohol components and carboxylic acid components that make up the modified polyester resin A, and is preferably 10 parts by mass or less, more preferably 7 parts by mass or less. The above amounts are calculated based on the alcohol component, carboxylic acid component, and modified silicone, and do not take into account the amount of water removed by condensation. When the modified silicone has a hydroxy group or a carboxy group, it can also be understood as an alcohol component or a carboxylic acid component, but when a compound having a hydroxy group or a carboxy group contains a silicone skeleton, it is considered to be a modified silicone. For example, when calculating the total amount of the alcohol component and the carboxylic acid component, the modified silicone having a hydroxy group or a carboxy group is not included in this total amount.

[0048] The modified polyester resin A can be obtained by polycondensation of an alcohol component, a carboxylic acid component, and a modified silicone. For example, it can be produced by polycondensing the alcohol component, the carboxylic acid component, and the modified silicone in an inert gas atmosphere, optionally using an esterification catalyst, at a temperature of 120°C or higher and 250°C or lower. Examples of the esterification catalyst include tin compounds such as tin(II) di(2-ethylhexanoate) and dibutyltin oxide; titanium compounds such as titanium diisopropylate bistriethanolamine; etc. Furthermore, if necessary, an esterification promoter such as 3,4,5-trihydroxybenzoic acid (gallic acid); or a radical polymerization inhibitor such as 4-tert-butylcatechol may be used.

[0049] The softening point of the modified polyester resin A is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher, from the viewpoint of improving water repellency and water resistance, and from the same viewpoint, is preferably 165°C or lower, more preferably 150°C or lower, and even more preferably 130°C or lower. The softening point is measured by the method described in the examples.

[0050] From the viewpoint of improving water repellency and water resistance, the glass transition temperature of the modified polyester resin A is preferably 35°C or higher, more preferably 40°C or higher, even more preferably 45°C or higher, and even more preferably 50°C or higher, and is preferably 85°C or lower, more preferably 80°C or lower, and even more preferably 75°C or lower. The glass transition temperature is measured using a differential scanning calorimeter, specifically by the method described in the examples.

[0051] From the viewpoint of improving the dispersion stability of resin particles in an aqueous medium and improving water repellency and water resistance, the acid value of the modified polyester resin A is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, even more preferably 15 mgKOH / g or more, and is preferably 40 mgKOH / g or less, more preferably 37 mgKOH / g or less, even more preferably 35 mgKOH / g or less. The acid value is measured by the method described in the Examples.

[0052] The modified polyester resin A may be used alone or in combination of two or more. The softening point, glass transition temperature, and acid value of the modified polyester resin A can be appropriately adjusted by adjusting the types and amounts of raw material monomers used, as well as production conditions such as reaction temperature, reaction time, and cooling rate, and these values ​​can be determined by the methods described in the examples. When two or more types of modified polyester resin A are used in combination, the softening point, glass transition temperature and acid value of the resulting mixture are preferably within the above-mentioned ranges.

[0053] The polyester resin X may contain a resin other than the modified polyester resin A. Examples of other resins include polyester resins other than modified polyester resin A, acrylic resins such as styrene-acrylic copolymers, and polyurethane resins. Examples of polyester resins other than modified polyester resin A include polyester resins composed of polycondensates of alcohol components and carboxylic acid components, as exemplified above for modified polyester resin A, composite resins containing polyester resin segments and vinyl resin segments, urethane-modified polyester resins, and epoxy-modified polyester resins.

[0054] From the viewpoint of improving water repellency and water resistance, the content of modified polyester resin A in the total amount of polyester resin X is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, still more preferably 75% by mass or more, still more preferably 85% by mass or more, still more preferably 95% by mass or more, and preferably 100% by mass or less.

[0055] In the present invention, the polyester resin X is preferably substantially water-insoluble from the viewpoint of improving water repellency and water resistance. When the polyester resin X is water-insoluble, the coating layer formed by applying the resin particle dispersion to a paper substrate becomes water-insoluble, thereby improving water repellency and water resistance. Here, "substantially water-insoluble" means that when polyester resin X, which has been vacuum dried at 40°C for 12 hours and reached a constant weight, is dissolved in 100 g of water at 25°C until saturated, the amount of dissolution is 1 g or less. When polyester resin X contains acid groups, the amount of dissolution is the amount of dissolution when 100 mol % of the acid groups of polyester resin X are neutralized with sodium hydroxide.

[0056] In the present invention, when the polyester resin X contains an acid group, the polyester resin X is preferably a product neutralized with a basic compound, from the viewpoint of improving the dispersion stability of the resin particles in an aqueous medium. The basic compound includes a metal basic compound and a non-metal basic compound. Examples of the metal basic compound include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide. Examples of the non-metallic basic compound include ammonia and organic amine compounds. The organic amine compound contains at least one primary amino group, secondary amino group, or tertiary amino group. The organic amine compound may contain a functional group other than these amino groups. Examples of such functional groups include a hydroxyl group. Examples of the organic amine compound include primary, secondary, or tertiary aliphatic amines, and amino alcohols having at least one amino group and at least one hydroxy group, and specific examples include trimethylamine, ethylamine, diethylamine, triethylamine, and triethanolamine. The basic compounds can be used alone or in combination of two or more. Among these, the basic compound is preferably at least one selected from metal basic compounds and non-metal basic compounds.

[0057] The amount of the basic compound used is preferably 50 mol % or more, more preferably 55 mol % or more, even more preferably 60 mol % or more, and preferably 100 mol % or less. The equivalent amount of the basic compound used can be calculated by the following formula (1): When the equivalent amount of the basic compound used is 100 mol % or less, it is synonymous with the degree of neutralization, and when the equivalent amount of the basic compound used in the following formula exceeds 100 mol %, it means that the basic compound is in excess of the acid groups of the polyester resin X, and the degree of neutralization of the polyester resin X in this case is considered to be 100 mol %. Equivalent amount of basic compound used (mol %) = {[mass of basic compound added (g) / equivalent amount of basic compound (g / mol)] / [[acid value of polyester resin X (mg KOH / g) × mass of polyester resin X (g)] / (56.1 × 1000 (mg KOH / mol))]} × 100 (1)

[0058] Furthermore, the resin particles according to the present invention may contain resins other than the polyester resin X, such as styrene-acrylic copolymers, epoxy resins, polycarbonates, polyurethanes, etc., within the scope of not impairing the effects of the present invention. The resin particles according to the present invention may contain optional components such as reinforcing fillers, such as fibrous substances, and additives, such as antioxidants, within the scope of not impairing the effects of the present invention. From the viewpoint of improving water repellency and water resistance, the content of polyester resin X in the resin particles according to the present invention is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and preferably 100% by mass or less.

[0059] (Production of Resin Particle Dispersion) The resin particle dispersion of the present invention is preferably produced by a method of dispersing a resin containing polyester resin X in an aqueous medium. Examples of methods for obtaining a resin particle dispersion include a method in which a resin containing polyester-based resin X is added to an aqueous medium and then subjected to a dispersion treatment using a disperser or the like, and a method in which an aqueous medium is gradually added to a solution of a resin containing polyester-based resin X and then subjected to phase inversion emulsification. Of these, the phase inversion emulsification method is preferred from the viewpoint of improving water repellency and water resistance.

[0060] A preferred phase inversion emulsification method is to first dissolve a resin containing polyester resin X in an organic solvent to obtain a solution of a resin containing polyester resin X, then add an aqueous medium to the solution to cause phase inversion, and then remove the organic solvent. Examples of organic solvents for dissolving resins including polyester resin X include ketone-based solvents such as dialkyl ketones having an alkyl group of 1 to 3 carbon atoms, such as acetone and methyl ethyl ketone; ether-based solvents such as dibutyl ether and tetrahydrofuran; ester-based solvents such as ethyl acetate and isopropyl acetate; and alkyl halide solvents such as dichloromethane and chloroform. Among these, from the viewpoint of dissolving resins including polyester resin X and facilitating their removal from emulsions, preferred are dialkyl ketones having an alkyl group of 1 to 3 carbon atoms, such as acetone and methyl ethyl ketone, and more preferred is methyl ethyl ketone. When a resin containing polyester-based resin X contains multiple types of polyester-based resins X or resins other than polyester-based resin X, the multiple types of polyester-based resins X may be mixed in advance before dissolving in an organic solvent, or the polyester-based resin X may be mixed with the other resin. Alternatively, these resins may be simultaneously added to an organic solvent and dissolved therein to obtain a solution of a resin containing polyester-based resin X. The mass ratio of the organic solvent to the resin containing polyester resin X [organic solvent / resin] is preferably 30 / 100 or more, more preferably 50 / 100 or more, even more preferably 70 / 100 or more, from the viewpoint of dissolving the resin and facilitating phase transfer to the aqueous medium, and from the viewpoint of further improving the dispersion stability of the resin particle dispersion, and is preferably 500 / 100 or less, more preferably 300 / 100 or less, even more preferably 200 / 100 or less, and still more preferably 150 / 100 or less. When the polyester resin X is a neutralized product with a basic compound, it is preferable to obtain a resin solution containing the polyester resin X, and then add an aqueous solution of the basic compound to the solution to neutralize it. The dissolution of the resin containing the polyester resin X in the organic solvent and the subsequent addition of the aqueous solution of the basic compound are generally carried out at a temperature not higher than the boiling point of the organic solvent.

[0061] The temperature when adding the aqueous medium to the resin solution containing the polyester resin X is preferably 10°C or higher, more preferably 20°C or higher, and even more preferably 25°C or higher, from the viewpoint of improving the dispersion stability of the resin particle dispersion, and is preferably 80°C or lower, and more preferably 75°C or lower. From the viewpoint of improving the dispersion stability of the resin particle dispersion, the addition rate of the aqueous medium is preferably 0.5 parts by mass / min or more, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, and is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 30 parts by mass or less, relative to 100 parts by mass of the resin component constituting the resin particles, until the phase inversion is completed, and is not particularly limited. After the phase inversion and the resin particles are obtained, there is no limitation on the addition rate of the aqueous medium. From the viewpoint of improving the productivity of the resin particle dispersion, the amount of the aqueous medium added is preferably 50 parts by mass or more, more preferably 100 parts by mass or more, and even more preferably 200 parts by mass or more, relative to 100 parts by mass of the resin component constituting the resin particles, and is preferably 900 parts by mass or less, more preferably 500 parts by mass or less, and even more preferably 400 parts by mass or less.

[0062] After the phase inversion emulsification, it is preferable to remove the organic solvent from the dispersion obtained by the phase inversion emulsification, from the viewpoint of improving the dispersion stability of the resin particle dispersion. The method for removing the organic solvent is not particularly limited, and any method can be used. The obtained resin particle dispersion is preferably filtered through a wire mesh or the like to remove coarse particles, etc. Furthermore, when the organic solvent is removed, water is also reduced azeotropically together with the organic solvent, so it is preferable to add water to adjust the solid content concentration.

[0063] From the viewpoint of improving water repellency and water resistance, the solid content concentration of the resin particle dispersion of the present invention is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and is preferably 50% by mass or less, more preferably 45% by mass or less, even more preferably 40% by mass or less. The solid content concentration of the dispersion is measured by the method described in the examples.

[0064] From the viewpoint of improving water repellency and water resistance, the volume average particle diameter Dv of the resin particles in the resin particle dispersion of the present invention is preferably 20 nm or more, more preferably 40 nm or more, even more preferably 60 nm or more, still more preferably 80 nm or more, and is preferably 500 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, and still more preferably 150 nm or less. The volume average particle diameter Dv is measured by the method described in the Examples.

[0065] The resin particle dispersion of the present invention may contain various additives, such as organic solvents, moisturizers, wetting agents, penetrants, viscosity adjusters, antifoaming agents, preservatives, antifungal agents, rust inhibitors, pH adjusters, antioxidants, ultraviolet absorbers, and surfactants, as needed. Since surfactants have a very high affinity for water, the presence of surfactants in the resin particle dispersion will result in the surfactant being contained in the coating layer formed when the resin particle dispersion is applied to paper, resulting in a decrease in water repellency. Therefore, from the viewpoint of improving water repellency and water resistance, it is preferable that the resin particle dispersion of the present invention is substantially free of surfactants. Here, "substantially free" means that no surfactant is intentionally added, and does not exclude the presence of a small amount of surfactant as an impurity. Furthermore, in the present invention, when producing a resin particle dispersion, the resin particles can be dispersed in an aqueous medium without using a surfactant, and a resin particle dispersion that is substantially free of surfactants can be obtained by using a method in which a resin containing the aforementioned polyester-based resin X is added to an aqueous medium and a dispersion treatment is carried out using a disperser or the like, or a method in which an aqueous medium is gradually added to a solution of a resin containing polyester-based resin X and phase inversion emulsification is carried out.

[0066] [Coating fluid] The resin particle dispersion can be used as a coating liquid as it is, but various additives used in coating liquids can also be added to and mixed with the resin particle dispersion as needed. That is, the coating liquid of the present invention preferably contains the resin particle dispersion. As mentioned above, surfactants have a very high affinity for water, and therefore, if a surfactant is present in the coating liquid, it will also be contained in the coating layer formed when the coating liquid is applied to a paper substrate, resulting in a decrease in water repellency. Therefore, from the perspective of improving water repellency, it is preferable that the coating liquid of the present invention also contains substantially no surfactant.

[0067] [Manufacturing method of coated paper] From the viewpoint of improving water repellency and water resistance, the method for producing coated paper of the present invention preferably includes step 1 of coating the coating liquid on at least one surface of a paper substrate. This makes it possible to obtain coated paper having a coating layer formed by applying the coating liquid to at least one side of the paper substrate. Examples of the paper substrate include uncoated paper such as fine paper, medium-quality paper, and wood-burning paper; coated paper such as art paper, coated paper, and matte-coated paper; information paper such as PPC paper; packaging paper such as kraft paper; cardboard base paper; and paperboard such as paper container board. The basis weight of the paper substrate is not particularly limited, but from the viewpoint of the handling of the coated paper and the ease of coating on the paper substrate, it is preferably 10 g / m 2 and preferably 200 g / m 2 or less, more preferably 150 g / m 2 More preferably, 120 g / m or less 2 The following is the result.

[0068] The amount of coating of the coating liquid in step 1 is preferably 1 g / m in terms of solid content from the viewpoint of improving water repellency and water resistance. 2 More preferably, 3 g / m 2 More preferably, 5 g / m 2 and preferably 30 g / m 2 Less than 25 g / m 2 More preferably 20 g / m or less 2 or less, even more preferably 15 g / m 2 Below are the results. The method for applying the coating liquid to the paper substrate in step 1 is not particularly limited, and examples include methods using a roll coater, gravure coater, die coater, curtain coater, spray coater, blade coater, wire bar coater, bar coater, rod bar coater, impregnation coater, cast coater, air knife coater, reverse coater, lip coater, kiss coater, etc.

[0069] In the present invention, from the viewpoint of improving water repellency and water resistance, it is preferable to further include step 2 of drying the coating liquid applied onto the paper substrate in step 1. Examples of the drying method in step 2 include static drying, air drying, heat drying, vacuum drying, and infrared drying. One or more drying methods may be used in combination. Among these, from the viewpoint of ease of operation, at least one method selected from air drying and heat drying is preferred, and heat drying is more preferred. Examples of heat drying include a method of heating the surface of the coating liquid on the paper substrate by applying hot air to it, a method of heating by bringing a heater close to the surface of the coating liquid on the paper substrate, a method of heating by bringing a heater into contact with the surface of the paper substrate opposite to the surface on which the coating liquid is coated, and a method of heating by steam curing using high-temperature steam at normal or high pressure. From the viewpoint of improving water repellency and water resistance, the drying temperature is preferably 30°C or higher, more preferably 40°C or higher, even more preferably 50°C or higher, even more preferably 70°C or higher, and even more preferably 90°C or higher, and from the viewpoint of suppressing deformation of the paper base material due to heat and reducing energy consumption, the drying temperature is preferably 200°C or lower, more preferably 150°C or lower, and even more preferably 110°C or lower. The drying time is preferably 3 minutes or more, more preferably 5 minutes or more, from the viewpoint of improving water repellency and water resistance, and is preferably 30 minutes or less, more preferably 15 minutes or less, from the viewpoint of suppressing deformation of the paper substrate due to heat and reducing energy consumption. [Example]

[0070] In the following examples, various physical properties were measured by the following methods.

[0071] [Resin softening point] Using a flow tester "CFT-500D" (Shimadzu Corporation), 1 g of sample was heated at a temperature increase rate of 6°C / min, while a load of 1.96 MPa was applied by the plunger, and the sample was extruded from a nozzle 1 mm in diameter and 1 mm in length. The plunger depression distance of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was taken as the softening point.

[0072] [Glass transition temperature of resin] Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of sample was weighed into an aluminum pan, heated to 200 °C, and cooled to 0 °C at a rate of 10 °C / min to prepare a sample for measurement. The sample was then heated at a rate of 10 °C / min, and the calorific value was measured. The peak temperature with the largest peak area among the observed endothermic peaks was defined as the endothermic maximum peak temperature. The glass transition temperature was determined as the temperature at the intersection of an extension of the baseline below the endothermic maximum peak temperature and a tangent line showing the maximum slope from the rising part of the peak to the peak apex.

[0073] [Acid value of resin] Measurement was performed according to the neutralization titration method described in JIS K0070: 1992. However, in this method, the measurement solvent was changed from a mixed solvent of ethanol and ether to a mixed solvent of acetone and toluene [acetone:toluene = 1:1 (volume ratio)].

[0074] [Volume average particle size of resin particles (Dv)] The volume average particle diameter Dv was measured using the following measuring device and under the following measuring conditions. Measurement equipment: Zeta potential and particle size measurement system "ELSZ-2" (Otsuka Electronics Co., Ltd.) Measurement conditions: Cumulant analysis. The particle concentration to be measured is approximately 5 × 10 -3 The dispersion diluted with water to a mass % was placed in a measurement cell, and the temperature was 25°C, the number of accumulations was 100, and the refractive index of water (1.333) was entered as the refractive index of the dispersion solvent.

[0075] [Solid content concentration of resin particle dispersion] Using an infrared moisture meter "FD-230" (Kett Electric Laboratory Co., Ltd.), 5 g of the measurement sample was dried at a drying temperature of 150°C and measurement mode 96 (monitoring time 2.5 minutes / fluctuation range 0.05%), and the moisture content (mass%) of the dispersion was measured. The solid content was calculated according to the following formula. Solid concentration (mass%) = 100-moisture (mass%)

[0076] Production Example A1 (Production of Silicone-Modified Polyester Resin A-1) The inside of a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was purged with nitrogen, and a mixture of 5206 g of a propylene oxide (2.2) adduct of bisphenol A, 1794 g of fumaric acid, 3.5 g of tert-butylcatechol, and side-chain amino-modified silicone "KF-864" (manufactured by Shin-Etsu Chemical Co., Ltd., viscosity (25°C): 1,700 mm 2 350 g of (2-ethylhexanoate / s, functional group equivalent: 3,800 g / mol) and 18 g of tin(II) di(2-ethylhexanoate) were added, and the mixture was heated to 210°C over 5 hours with stirring under a nitrogen atmosphere, held at 210°C for 2 hours, and then held at 8.3 kPa to react until the softening point reached the temperature shown in Table 1, yielding silicone-modified polyester resin A-1. The physical properties of the resin are shown in Table 1.

[0077] Production Example A2 (Production of Silicone-Modified Polyester Resin A-2) In Production Example A1, the side chain amino-modified silicone "KF-864" was replaced with the modified silicone "KF-865" (manufactured by Shin-Etsu Chemical Co., Ltd., viscosity (25°C): 110 mm 2 Silicone-modified polyester resin A-2 was obtained in the same manner as in Production Example A1, except that a silicone-modified polyester resin A-2 (functional group equivalent: 5,000 g / mol) was used instead. The physical properties of the resin are shown in Table 1.

[0078] Production Example A3 (Production of Silicone-Modified Polyester Resin A-3) The inside of a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was purged with nitrogen, and 3475 g of a propylene oxide (2.2) adduct of bisphenol A, 1383 g of an ethylene oxide (2.2) adduct of bisphenol A, 1648 g of terephthalic acid, side-chain epoxy-modified silicone "KF-1001" (manufactured by Shin-Etsu Chemical Co., Ltd., viscosity (25 °C): 17,000 mm 2 350 g of tin(II) di(2-ethylhexanoate) (s, functional group equivalent: 3,500 g / mol), 35 g of tin(II) di(2-ethylhexanoate), and 0.7 g of gallic acid were added under a nitrogen atmosphere with stirring. The mixture was heated to 235°C and held for 8 hours, after which the pressure in the flask was reduced to 8.3 kPa and held for 1 hour. The mixture was then returned to atmospheric pressure and cooled to 190°C. 494 g of fumaric acid and 3.5 g of tert-butylcatechol were added. The mixture was heated to 210°C over 2 hours and held at 210°C for 1 hour. The pressure in the flask was then reduced to 8.3 kPa and the reaction was continued until the softening point reached the temperature shown in Table 1, yielding silicone-modified polyester resin A-3. The various physical properties of the resin are shown in Table 1.

[0079] Production Example A4 (Production of Silicone-Modified Polyester Resin A-4) The inside of a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 5518 g of a propylene oxide (2.2) adduct of bisphenol A, 1570 g of terephthalic acid, 400 g of side-chain amino-modified silicone "KF-864" (manufactured by Shin-Etsu Chemical Co., Ltd.), 40 g of tin (II) di(2-ethylhexanoate), and 2.0 g of gallic acid were added. The mixture was heated to 235°C with stirring under a nitrogen atmosphere and maintained at this temperature for 8 hours, after which the pressure inside the flask was further reduced and maintained at 8.3 kPa for 1 hour. The pressure was then returned to atmospheric pressure, cooled to 190°C, and 549g of fumaric acid, 4.0g of tert-butylcatechol, and 363g of trimellitic anhydride were added, and the temperature was raised to 210°C over 2 hours and held at 210°C for 1 hour. After that, the pressure in the flask was further reduced and held at 8.3kPa, and the reaction was carried out until the softening point reached the temperature shown in Table 1, yielding silicone-modified polyester resin A-4. The physical properties of the resin are shown in Table 1.

[0080] Production Example A5 (Production of Silicone-Modified Polyester Resin A-5) Silicone-modified polyester resin A-5 was obtained in the same manner as in Production Example A4, except that the amount of side-chain amino-modified silicone "KF-864" (manufactured by Shin-Etsu Chemical Co., Ltd.) was changed to 240 g. The physical properties of the resin are shown in Table 1.

[0081] Production Example A6 (Production of Silicone-Modified Polyester Resin A-6) The inside of a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 2292 g of 1,2-propanediol, 4008 g of terephthalic acid, 350 g of side-chain amino-modified silicone "KF-865" (Shin-Etsu Chemical Co., Ltd.), 35 g of tin(II) di(2-ethylhexanoate), and 0.7 g of gallic acid were added. The mixture was heated to 180°C with stirring under a nitrogen atmosphere and maintained at this temperature for 1 hour, and then heated to 210°C over 6 hours. After maintaining the temperature at 210°C for 2 hours, the pressure inside the flask was further reduced and maintained at 8.3 kPa for 1 hour. The pressure was then returned to atmospheric pressure, cooled to 180°C, 700g of fumaric acid and 3.5g of tert-butylcatechol were added, and the temperature was raised to 210°C over 3 hours and maintained at 210°C for 1 hour. After that, the pressure inside the flask was further reduced and maintained at 8.3kPa, and the reaction was continued until the softening point reached the temperature shown in Table 1, yielding silicone-modified polyester resin A-6. The physical properties of the resin are shown in Table 1.

[0082] Production Example A7 (Production of Polyester Resin A-7) A four-neck flask equipped with a nitrogen inlet tube, dehydration tube, stirrer, and thermocouple was purged with nitrogen, and 5206 g of propylene oxide (2.2) adduct of bisphenol A, 1794 g of fumaric acid, 3.5 g of tert-butylcatechol, and 18 g of tin(II) di(2-ethylhexanoate) were added. The mixture was heated to 210°C over 5 hours with stirring under a nitrogen atmosphere, held at 210°C for 2 hours, and then held at 8.3 kPa until the softening point reached the temperature shown in Table 1, yielding polyester resin A-7. The physical properties of the resin are shown in Table 1.

[0083] [Table 1]

[0084] Production Example D1 (Production of Water-Based Dispersion D-1 of Resin Particles) 300 g of silicone-modified polyester resin A-1 as polyester resin X was placed in a four-neck flask equipped with a reflux condenser, a stirrer "Three-One Motor BL300" (manufactured by Shinto Scientific Co., Ltd.), and a thermocouple, and mixed with 300 g of methyl ethyl ketone (hereinafter referred to as "MEK") at 30°C to dissolve the resin. Next, a 5% by mass aqueous solution of sodium hydroxide was added so that the degree of neutralization was 65 mol% relative to the acid value of polyester A-1, and the mixture was stirred for 60 minutes. Next, 800 g of deionized water was added dropwise at a rate of 13.3 mL / min at 30°C while stirring, resulting in phase inversion emulsification. The temperature was then raised to 65°C, and the pressure was gradually reduced from 80 kPa to 30 kPa while distilling off the MEK, and then some of the water. After cooling to room temperature, the mixture was filtered through a 150-mesh wire screen, and the solids concentration was adjusted to 30% by mass with deionized water to obtain an aqueous dispersion of resin particles D-1. The volume-average particle diameter Dv of the resin particles in the resulting dispersion is shown in Table 2.

[0085] Production Examples D2 to D8 (Production of Aqueous Dispersions D-2 to D-8 of Resin Particles) Aqueous dispersions of resin particles were obtained in the same manner as in Production Example D1, except that the type of polyester resin X in Production Example D1 was changed to one shown in Table 2. The volume average particle diameter Dv of the resin particles in the obtained dispersions is shown in Table 2.

[0086] [Table 2]

[0087] Examples 1 to 7 and Comparative Example 1 (Process 1) The aqueous dispersion of resin particles obtained as a coating liquid was applied to PPC paper "J paper" (basis weight 82 g / m) as a paper substrate. 2 The coating was carried out on a coating machine (manufactured by Fujifilm Business Innovation Co., Ltd.) using a bar coater (No. 12). The coating amount is 8g / m2 as solid content. 2 The coating was carried out so that the result was as follows. (Process 2) The aqueous dispersion of resin particles on the paper substrate was then dried for 5 minutes in a dryer at 80°C to obtain coated papers with a coating layer on the paper substrate. The water repellency and water resistance of each of the obtained coated papers were evaluated using the following methods. [Water repellency evaluation] Water repellency was evaluated in accordance with JAPAN TAPPI Paper and Pulp Testing Method No. 68:2000. At room temperature, coated paper was tilted at a 45° angle, and a droplet of ion-exchanged water was dropped from 10 mm above the coated paper. The state of the coated paper after the droplet had passed over it was observed and the water repellency rating was determined as R0 to R10. A water repellency rating of R6 or higher indicates excellent water repellency. In addition, as Reference Example 1, PPC paper "J paper" (basis weight 82 g / m 2 The water repellency of the film (manufactured by Fujifilm Business Innovation Co., Ltd.) was also evaluated. The results are shown in Table 3. [Water repellency] R0: Continuous marks of uniform width R2: A continuous mark with a width slightly narrower than that of a water droplet R4: A continuous mark that is broken in places and clearly shows a width narrower than that of a water droplet R6: Half of the mark is wet R7: 1 / 4 of the mark is wetted by elongated water droplets R8: More than 1 / 4 of the mark is made up of scattered spherical droplets R9: Small spherical droplets scattered here and there R10: Completely rolls down

[0088] [Water resistance evaluation] The coated paper was placed on a horizontal table, and a droplet of ion-exchanged water was dropped from 10 mm above the coated paper and allowed to stand for 1 minute. The water droplets were then wiped off, and the condition of the paper after wiping was checked and evaluated based on the following criteria: In addition, as Reference Example 1, PPC paper "J paper" (basis weight 82 g / m 2 The water resistance of the FUJIFILM Business Innovation Co., Ltd. (manufactured by Fujifilm Business Innovation Co., Ltd.) was also evaluated. The results are shown in Table 3. 〔Judgment criteria〕 L5: No water stains are visible on the paper. L4: Slight water stains are visible. L3: Water stains are visible, but the stains are smaller than water droplets. L2: Stains the same size as water droplets are visible. L1: Stains larger than water droplets are observed.

[0089] [Table 3]

[0090] From Table 3, it can be seen that in Examples 1 to 7, coated papers superior in water repellency and water resistance compared to Comparative Example 1 can be obtained. [Industrial Applicability]

[0091] According to the present invention, it is possible to obtain coated paper having a coating layer with excellent water repellency and water resistance, and since the amount of resin used can be reduced compared to paper laminated with a plastic film, it is possible to obtain coated paper with high environmental friendliness, and it can be used for paper labels, packaging paper, paper containers, etc. that require water resistance.

Claims

1. A resin particle dispersion for paper coating containing resin particles including a polyester-based resin X, The polyester-based resin X contains a silicone-modified polyester resin A which is a reaction product of an alcohol component containing a dihydric or higher alcohol, a carboxylic acid component containing at least one selected from aromatic dicarboxylic acids and aliphatic dicarboxylic acids, and a modified silicone having an amino group, an epoxy group, a hydroxy group, or a carboxy group at a side chain, one end, or both ends.

2. 2. The resin particle dispersion for paper coating according to claim 1, wherein the functional group equivalent of the modified silicone is 500 g / mol or more and 20,000 g / mol or less.

3. 3. The resin particle dispersion for paper coating according to claim 1, wherein the content of the modified silicone in the silicone-modified polyester resin A is 0.5 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component constituting the modified polyester resin A.

4. 4. The resin particle dispersion for paper coating according to claim 1, wherein the silicone-modified polyester resin A has a glass transition temperature of 40° C. or higher and 80° C. or lower.

5. The resin particle dispersion for paper coating according to any one of claims 1 to 4, which is substantially free of a surfactant.

6. A paper coating liquid comprising the resin particle dispersion according to any one of claims 1 to 5.

7. A coated paper having a coating layer formed by applying the coating liquid according to claim 6 to at least one surface of a paper substrate.

8. A method for producing coated paper, comprising step 1 of applying the coating liquid according to claim 6 to at least one surface of a paper substrate, and step 2 of drying the coating liquid on the paper substrate coated in step 1.

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