Resin particle dispersion for paper coating

Abstract

To provide: a resin particle dispersion for paper coating, capable of obtaining a coated paper having excellent water repellency and oil resistance; a coating liquid for paper, containing the resin particle dispersion; a coated paper using the coating liquid; and a method for producing the coated paper.SOLUTION: A resin particle dispersion for paper coating comprises a resin particle that contains a polyester-based resin X, wherein: the resin particle contains a modified silicone oil; the polyester-based resin X comprises an amorphous polyester-based resin A that contains an alcohol component containing a divalent or more alcohol and a carboxylic acid component containing one or more selected from aromatic dicarboxylic acid and aliphatic dicarboxylic acid; and the dispersant is water.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, and coated paper using the coating fluid. [Background technology]

[0002] Conventionally, paper materials that can be used for paper labels, wrapping paper, paper containers, etc. that require water resistance have been made by laminating plastic films such as polyethylene and polypropylene to impart water repellency and oil resistance. 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 has been studied to provide technologies that can impart water repellency and oil resistance 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, which is provided with a moisture-proof paper having a moisture-proof composition layer formed on at least one surface of a paper support, the moisture-proof composition layer being 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, and a moisture-proof composition layer having a density of 0.1 to 10 g / m 2 The document describes a moisture-proof laminate in which a coating layer made of a crosslinked product of the above water-soluble resin is provided. Furthermore, Patent Document 2 describes a silicone paper treatment agent containing 100 parts by mass of (A) an organopolysiloxane, 100 to 100,000 parts by mass of (E) water, and 0.1 to 100 parts by mass of (F) a surfactant, further containing 50 to 1,000 parts by mass of (C) a cellulose resin in which 0.5 to 2.5 hydroxyl groups per glucose unit are etherified or esterified, and a 2% aqueous solution of the paper treatment agent has a viscosity of 2 to 100 mPa s at 20°C. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 9-268494 [Patent Document 2] Patent Publication No. 2006-144214 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the techniques of Patent Documents 1 and 2 were unable to obtain sufficient water repellency like that of paper laminated with a plastic film. Also, the techniques of Patent Documents 1 and 2 had difficulty in achieving both water repellency and oil resistance. An object of the present invention is to provide a resin particle dispersion for paper coating that can produce coated paper with excellent water repellency and oil resistance, a paper coating fluid containing the resin particle dispersion, and coated paper using the coating fluid. [Means for solving the problem]

[0006] The present inventors have found that the above-mentioned problems can be solved by forming a coating layer on the surface of a paper substrate using a resin particle dispersion in which resin particles containing a polyester-based resin including a modified silicone and an alcohol component containing a dihydric or higher alcohol, and a carboxylic acid component containing one or more selected from aromatic dicarboxylic acids and aliphatic dicarboxylic acids are dispersed in an aqueous medium.

[0007] That is, the present invention provides the following [1] to [3]. [1] A resin particle dispersion for paper coating, comprising resin particles including a polyester-based resin X, the resin particles comprising a modified silicone oil, the polyester-based resin X comprising an amorphous polyester-based resin A including an alcohol component including a dihydric or higher alcohol and a carboxylic acid component including at least one selected from an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid, and the dispersion medium being water. [2] A paper coating liquid containing the resin particle dispersion liquid described in [1] above. [3] A 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. Effect of the Invention

[0008] ADVANTAGEOUS EFFECTS OF THE PRESENT DISCLOSURE The present invention provides a resin particle dispersion for paper coating capable of producing coated paper with excellent water repellency and oil resistance, a paper coating fluid containing the resin particle dispersion, and coated paper using the coating fluid. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Resin particle dispersion for paper coating] The resin particle dispersion for paper coating of the present invention (hereinafter also simply referred to as "resin particle dispersion") is a resin particle dispersion for paper coating containing resin particles (hereinafter also simply referred to as "resin particles") including a polyester-based resin X, which contains an amorphous polyester-based resin A and has water as a dispersion medium.

[0010] In the resin particle dispersion of the present invention, deionized water, ion-exchanged water or distilled water is preferably used as the dispersion medium. The dispersion medium may further contain an organic solvent, such as aliphatic alcohols having 1 to 4 carbon atoms, such as methanol, ethanol, and 2-propanol, ketones having 3 to 8 carbon atoms, such as acetone and methyl ethyl ketone, and ethers, such as diethyl ether and tetrahydrofuran, which are water-soluble organic solvents. From the viewpoint of environmental friendliness, the water content in the dispersion 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, still more preferably 100% by mass.

[0011] According to the present invention, it is possible to obtain coated paper having excellent water repellency and oil resistance. The reason for this is not clear, but is thought to be as follows. Silicone is an organosilicon polymer known to have high water repellency and oil resistance. However, when silicone oil is simply applied to a paper substrate, it quickly penetrates the substrate, leaving an oily stain, and water repellency is not achieved. 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 terminal groups such as hydroxyl groups and carboxyl groups, making them materials with high affinity for paper. Therefore, in the present invention, silicone oil is contained in the resin particles containing polyester resin, so that it is possible to obtain a resin particle dispersion that can produce a highly hydrophobic surface.In addition, by using modified silicone oil having polar group or the like as the silicone oil used in the present invention, the molecular interaction with the resin particles containing polyester resin works, and the modified silicone oil is efficiently encapsulated in the resin particles, and it is possible to make the dispersion state suitable for coating liquid.Furthermore, in the resin particles of the present invention, since the modified silicone oil is not chemically covalently bonded with the polyester resin that forms the resin particles, the modified silicone oil has a high degree of molecular freedom, and when the modified silicone oil is applied to a paper substrate to form a coating layer, the molecules of the modified silicone oil can be oriented on the surface of the coating layer, that is, at the interface with air, so that it is considered that high water repellency and oil resistance are simultaneously expressed.

[0012] <Modified silicone oil> In the present invention, the modified silicone oil is contained in the resin particles without being chemically bonded covalently to the polyester resin that forms the resin particles described below. From the viewpoint of achieving both water repellency and oil resistance, the modified silicone oil is preferably a modified silicone having at least one group selected from an amino group, an epoxy group, an ester group, a hydroxy group and a carboxy group at a side chain, at one end or at both ends; from the viewpoint of further improving water repellency and oil resistance, it is more preferably a modified silicone having at least one group selected from an amino group, an epoxy group, an ester group and a hydroxy group at a side chain, even more preferably a modified silicone having at least one group selected from an amino group, an epoxy group and an ester group at a side chain, and still more preferably a modified silicone having an amino group at a side chain. The amino group, epoxy group, ester group, hydroxy group and carboxy group are collectively referred to as "modified groups", and a group containing a modified group and another moiety is also referred to as "modified group-containing group".

[0013] [Modified silicone having a modifying group on the side chain] The modified silicone having a modifying group on a side chain is preferably a silicone represented by the following formula (1-1): [ka] [In the formula, R 11 are each independently a hydrocarbon group having 1 to 6 carbon atoms; 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, an ester group, or a carboxy group, and * is a bonding site. [ka] [In the formula, R 11 are each independently a hydrocarbon group having 1 to 6 carbon atoms, and * is a bonding site.

[0014] The silicone terminal has the following formula (1-3): [ka] [In the formula, R 13 is a hydrocarbon group having 1 to 10 carbon atoms, and * is a bonding site.

[0015] 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. Among these, a methyl group is preferable. 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, still more preferably 2 or less, and still more preferably 1 carbon atom. R 12 Examples of the alkylene group include a methanediyl group, an ethane-1,2-diyl group, an ethane-1,1-diyl group, an n-propane-1,3-diyl group, and an n-propane-1,2-diyl group. Among these, a methanediyl group 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, still 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.

[0016] X 1 are each independently a group containing an amino group, an epoxy group, a hydroxy group, an ester group, or a carboxy group. When a is 0, X 1 may have an ether bond. That is, X 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; X 1 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 means an aliphatic hydrocarbon group having an ether bond (-O-) between carbon-carbon bonds.

[0017] 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 the above formula (1-1), a is 1 or 0, and X 1 are each independently -NH2 or -R 14 -NH-R 14 -NH2, 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 1 -R 14 -NH-R 14 More preferably, a is 1 and X is —NH2. 1 is -NH2, R 12 is more preferably an alkylene group having 1 to 10 carbon atoms. Commercially available modified silicones having amino groups on the side chains include, for example, "KF-868", "KF-865", "KF-864", "X-22-3939A", and "KF-862" (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0018] 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 the above 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 optionally containing an ether bond having 1 to 10 carbon atoms, and more preferably an aliphatic hydrocarbon group containing an epoxy group and optionally containing an ether bond having 1 to 6 carbon atoms. 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.).

[0019] When the modified silicone is a silicone having an ester group on the side chain, X 1 is a group containing an ester group. In this case, in the above formula (1-1), a is 0, and X 1is preferably a group containing an ester group. An example of a commercially available modified silicone having an ester group on the side chain is "X-22-715" (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0020] When the modified silicone is a silicone having a hydroxyl group on the side chain, X 1 is a group containing a hydroxy group. In this case, in the above formula (1-1), a is 1, and X 1 is a hydroxy group, or a is 0 and X 1 is 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, X 1 The number of hydroxy groups contained in the alkyl group is 1 or more, preferably 5 or less, more preferably 4 or less, and further preferably 2 or less. Commercially available modified silicones having hydroxy groups on the side chains include, for example, "X-22-4015" and "X-22-4039" (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0021] 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 may be preferably an aliphatic hydrocarbon group containing an ether bond having 1 to 10 carbon atoms and substituted with a carboxy group, more preferably an aliphatic hydrocarbon group containing an ether bond having 1 to 6 carbon atoms and substituted with a carboxy group. 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.).

[0022] [Modified silicone having a modifying group at one or both ends] The modified silicone having a modifying group at one or both ends is preferably a silicone represented by the following formula (2-1): [ka] [In the formula, R 21 are each independently a hydrocarbon group having 1 to 6 carbon atoms, R 22 are each independently an alkylene group having 1 to 10 carbon atoms, 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.

[0023] 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. Among these, a methyl group is preferable. R 22 The alkylene group has 10 or less carbon atoms, preferably 8 or less, more preferably 5 or less, even more preferably 4 or less, even more preferably 3 or less, and preferably 1 or more, more preferably 2 or more. R 22Examples of the alkylene group include methanediyl, ethane-1,2-diyl, ethane-1,1-diyl, n-propane-1,3-diyl, n-propane-1,2-diyl, and 2-methylethane-1,2-diyl. Among these, ethane-1,2-diyl, n-propane-1,3-diyl, and n-propane-1,2-diyl are preferred, and n-propane-1,2-diyl is 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, still 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.

[0024] The modified silicone having an amino group at one or both ends is X 2 is preferably each independently an amino group. 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, for example, "X-22-161A", "KF-8012", and "KF-8008" (all manufactured by Shin-Etsu Chemical Co., Ltd.)).

[0025] The modified silicone having an epoxy group at one or both ends is X 2are preferably each independently an epoxy group, a glycidyl group, a glycidyloxy group, or an alicyclic epoxy group. 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.)).

[0026] The modified silicone having a hydroxyl group at one or both ends is X 2 are 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 further preferably 6 or less. Examples of modified silicones having a hydroxy group at one or both ends include silicones modified with carbinol at both ends (commercially available products include, for example, "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, for example, "X-22-170BX", "X-22-170DX", "X-22-176DX", and "X-22-176GX-A" (all manufactured by Shin-Etsu Chemical Co., Ltd.)).

[0027] 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. Examples of modified silicones having a carboxy group at one or both ends include silicone modified with a carboxy group at both ends (a commercially available product is "X-22-162C" (manufactured by Shin-Etsu Chemical Co., Ltd.)) and silicone modified with a carboxy group at one end (a commercially available product is "X-22-3710" (manufactured by Shin-Etsu Chemical Co., Ltd.)).

[0028] The kinetic viscosity of the modified silicone at 25°C is preferably 20mm 2 / s or more, preferably 100 mm 2 / s or more, and more preferably 1,000 mm 2 / s or more, and preferably 20,000 mm 2 / s or less, preferably 15,000 mm 2 / s or less, and more preferably 10,000 mm 2 / s or less, and even more preferably 5,000 mm 2 / s or less, and even more preferably 2,000 mm 2 / s or less. The kinetic viscosity of the modified silicone is measured at 25° C. using a fully automatic micro dynamic 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 15,000 g / mol or less, even more preferably 10,000 g / mol or less. The functional group equivalent means the mass of the modified silicone per mole of functional group.

[0029] In the resin particle dispersion of the present invention, the content of the modified silicone oil is, from the viewpoint of improving water repellency and oil resistance, preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, still more preferably 20 parts by mass or more, and is preferably 200 parts by mass or less, more preferably 170 parts by mass or less, and even more preferably 150 parts by mass or less, relative to 100 parts by mass of the polyester resin X in the resin particles.

[0030] <Polyester resin X> In the present invention, the polyester resin X contained in the resin particles contains an amorphous polyester resin A including an alcohol component containing a dihydric or higher alcohol and a carboxylic acid component containing one or more selected from an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid. In the present invention, the polyester resin X contains the amorphous polyester resin A, and when used as a paper coating liquid, it can impart excellent water repellency and oil resistance to paper.

[0031] The crystallinity of a resin is represented by the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter (DSC), i.e., the crystallinity index defined as "softening point (°C) / maximum endothermic peak temperature (°C)". The term "crystalline resin" refers to a resin having a crystallinity index of 0.6 or more and 1.4 or less. The term "amorphous resin" refers to a resin in which no endothermic peak is observed by differential scanning calorimetry (DSC), or, if an endothermic peak is observed, the resin has a crystallinity index of less than 0.6 or more than 1.4. The maximum endothermic peak temperature refers to the temperature of the endothermic peak with the largest peak area among the endothermic peaks observed under the conditions of the measurement method described in the Examples. The crystallinity of the resin can be adjusted by the types and ratios of the raw material monomers, and the production conditions (e.g., reaction temperature, reaction time, cooling rate), etc.

[0032] [Amorphous polyester resin A] The amorphous polyester resin A is not particularly limited as long as it contains a polycondensate of an alcohol component containing a dihydric or higher alcohol and a carboxylic acid component containing at least one selected from aromatic dicarboxylic acids and aliphatic dicarboxylic acids, and examples thereof include a polyester resin made of a polycondensate of an alcohol component and a carboxylic acid component, and modified polyester resins. Examples of modified polyester resins include silicone-modified polyester resins modified with modified silicone, amorphous composite resins containing polyester resin segments and addition polymerization resin segments, urethane-modified polyester resins, and epoxy-modified polyester resins. Among these, the amorphous polyester resin A is preferably at least one selected from polyester resins, silicone-modified polyester resins, and amorphous composite resins, and more preferably a silicone-modified polyester resin.

[0033] (Alcohol content) The alcohol component constituting the amorphous polyester resin A (hereinafter, 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. The dihydric or higher alcohol includes diols and trihydric or higher polyhydric alcohols. The diol includes an aromatic diol and an aliphatic diol. The aromatic diol may, for example, be an alkylene oxide adduct of bisphenol A. In the present invention, the term "alkylene oxide adduct of bisphenol A" refers to the entire structure in which an alkylene oxide is added to 2,2-bis(4-hydroxyphenyl)propane. From the viewpoint of improving water repellency and oil resistance, the alkylene oxide adduct of bisphenol A is preferably a compound represented by the following formula (I).

[0034] [ka]

[0035] In the above formula (I), OR 1 , and R 2 Each O is an alkyleneoxy group, and from the viewpoint of improving water repellency and oil resistance, preferably, each O is independently an alkyleneoxy group having 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 2 Each O may be the same or different, but is preferably the same from the viewpoint of improving the adhesion of the coating layer to paper. The alkylene oxide adduct of bisphenol A may be used alone or in combination of two or more. From the viewpoint of improving water repellency and oil 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.

[0036] 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. As the aliphatic diol, 1,2-propanediol is preferable from the viewpoint of improving water repellency and oil resistance. Examples of the alicyclic aliphatic diol include cyclohexanediol and hydrogenated bisphenol A. Examples of the trihydric or higher polyhydric alcohol include glycerin, pentaerythritol, trimethylolpropane, sorbitol, and sorbitan.

[0037] Among these, from the viewpoint of improving water repellency and oil resistance, the alcohol component constituting the amorphous polyester resin A preferably contains either an aromatic diol or an aliphatic diol, more preferably contains either an alkylene oxide adduct of bisphenol A or 1,2-propanediol, and even more preferably contains an alkylene oxide adduct of bisphenol A. From the viewpoint of improving water repellency and oil resistance, the content of aromatic diol or aliphatic diol in the alcohol component constituting the amorphous polyester resin A is preferably 60 mol % or more, more preferably 80 mol % or more, even more preferably 90 mol % or more, still more preferably 95 mol % or more, and preferably 100 mol % or less.

[0038] (Carboxylic acid component) The carboxylic acid component constituting the amorphous 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 term "carboxylic acid component" includes not only carboxylic acids but also their anhydrides and their alkyl esters having from 1 to 3 carbon atoms. In other words, when only the name of a carboxylic acid is mentioned in this specification, it is understood that the description also includes the anhydrides and alkyl esters of the carboxylic acid having from 1 to 3 carbon atoms.

[0039] The carboxylic acid component may be used alone or in combination of two or more. Examples of the aromatic dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, etc. Among these, from the viewpoint of improving water repellency and oil resistance, the aromatic dicarboxylic acid is preferably isophthalic acid or terephthalic acid, and more preferably terephthalic acid. Examples of the aliphatic dicarboxylic acid include linear, branched, or 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 1 to 20 carbon atoms, and cyclohexanedicarboxylic acid. Specific examples of succinic acid substituted with a hydrocarbon group having 1 to 20 carbon atoms include dodecylsuccinic acid, dodecenylsuccinic acid, and octenylsuccinic acid. Among these, the aliphatic dicarboxylic acid is preferably at least one selected from fumaric acid, adipic acid, and succinic acid, from the viewpoint of improving water repellency and oil resistance.

[0040] From the viewpoint of improving water repellency and oil resistance, the total content of aromatic dicarboxylic acid and aliphatic dicarboxylic acid in the carboxylic acid component constituting the amorphous polyester resin A is preferably 60 mol % or more, more preferably 65 mol % or more, even more preferably 70 mol % or more, and preferably 100 mol % or less.

[0041] From the viewpoint of improving water repellency and oil resistance, the carboxylic acid component constituting the amorphous polyester resin A preferably contains a trivalent or higher polycarboxylic acid, and more preferably contains a trivalent or higher aromatic polycarboxylic acid. Examples of aromatic polycarboxylic acids having a valence of three or more include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, and pyromellitic acid. Among these, trimellitic acid is preferred. When the carboxylic acid component constituting the amorphous polyester resin A contains a trivalent or higher polycarboxylic acid, the content of the trivalent or higher aromatic polycarboxylic acid in the carboxylic acid component constituting the amorphous polyester resin A is, from the viewpoint of improving water repellency and oil resistance, preferably 3 mol % or more, more preferably 5 mol % or more, even more preferably 10 mol % or more, and is preferably 50 mol % or less, more preferably 40 mol % or less, even more preferably 30 mol % or less.

[0042] The equivalent ratio (COOH group / OH group) of the carboxy group (COOH group) of the carboxylic acid component to the hydroxy group (OH group) of the alcohol component constituting the amorphous polyester resin A is preferably 0.7 or more and preferably 1.2 or less.

[0043] (Components derived from modified silicone) When the amorphous polyester resin A is a silicone-modified polyester resin, the silicone-modified polyester resin preferably contains a component derived from modified silicone in addition to the alcohol component and carboxylic acid component described above, from the viewpoint of improving water repellency and oil resistance.By containing a component derived from modified silicone, the modified silicone oil is more easily encapsulated in the resin particles containing the amorphous polyester resin X, and furthermore, it is easy to make the dispersion state suitable for the coating liquid.Therefore, it is easier to further improve water repellency and oil resistance. The modified silicone-derived component may be, for example, the modified silicone having a modifying group on the side chain and the modified silicone having a modifying group on one end or both ends, as exemplified in the modified silicone oil described above. Among these, the modified silicone-derived component contained in the amorphous polyester resin A is preferably a modified silicone having a modifying group on the side chain, more preferably a modified silicone having an amino group on the side chain, from the viewpoint of improving water repellency and oil resistance.

[0044] From the viewpoint of improving water repellency and oil resistance, the content of the modified silicone-derived component in the amorphous polyester resin A is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 1.5 parts by mass or more, relative to 100 parts by mass of the total amount of the alcohol components and carboxylic acid components that constitute the amorphous polyester resin A, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less. The above amount is calculated based on the alcohol component, the carboxylic acid component, and the components derived from the modified silicone, and does not take into account the amount of water removed by condensation. In addition, when a component derived from 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 component derived from modified silicone. For example, when calculating the total amount of the alcohol component and the carboxylic acid component, the component derived from modified silicone having a hydroxy group or a carboxy group is not included in these total amounts.

[0045] (Raw material monomer for addition polymerization resin segment) When the amorphous polyester resin A is an amorphous composite resin, it is preferable that the amorphous composite resin contains a polycondensate of the above-mentioned alcohol component and carboxylic acid component as a polyester resin segment, and further contains an addition polymer of a raw material monomer containing a styrene-based compound as an addition polymerization resin segment. Examples of the styrene-based compound include unsubstituted or substituted styrene. Examples of the substituent substituted on styrene include an alkyl group having 1 to 5 carbon atoms, a halogen atom, an alkoxy group having 1 to 5 carbon atoms, a sulfonic acid group, or a salt thereof. Examples of styrene-based compounds include styrene, methylstyrene, α-methylstyrene, β-methylstyrene, tert-butylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, styrenesulfonic acid, and salts thereof. Among these, styrene is preferred. In the raw material monomers of the addition polymerization resin segment, the content of the styrene-based compound is preferably 50 mass% or more, more preferably 65 mass% or more, even more preferably 75 mass% or more, and preferably 100 mass% or less, more preferably 95 mass% or less, even more preferably 90 mass% or less, and still more preferably 85 mass% or less.

[0046] Examples of raw material monomers other than styrene-based compounds include (meth)acrylic acid esters such as alkyl (meth)acrylate, benzyl (meth)acrylate, and dimethylaminoethyl (meth)acrylate; olefins such as ethylene, propylene, and butadiene; halovinyls such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone. Among these, (meth)acrylic acid esters are preferred, and alkyl (meth)acrylates are more preferred.

[0047] The number of carbon atoms in the alkyl group in the alkyl (meth)acrylate is preferably 1 or more, more preferably 4 or more, even more preferably 6 or more, and is preferably 24 or less, more preferably 22 or less, even more preferably 20 or less. Examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, (iso)propyl (meth)acrylate, (iso or tertiary)butyl (meth)acrylate, (iso)amyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (iso)octyl (meth)acrylate, (iso)decyl (meth)acrylate, (iso)dodecyl (meth)acrylate, (iso)palmityl (meth)acrylate, (iso)stearyl (meth)acrylate, (iso)behenyl (meth)acrylate, etc. Among these, preferred are 2-ethylhexyl (meth)acrylate or stearyl (meth)acrylate, more preferred are 2-ethylhexyl (meth)acrylate, and even more preferred are 2-ethylhexyl acrylate. In addition, "(iso or tertiary)" and "(iso)" refer to both the presence and absence of these prefixes, and the absence of these prefixes indicates normal. In addition, "(meth)acrylic acid" refers to acrylic acid or methacrylic acid. In the raw material monomers of the addition polymerization resin segment, the content of alkyl (meth)acrylate is preferably 5 mass% or more, more preferably 10 mass% or more, even more preferably 15 mass% or more, and preferably 50 mass% or less, more preferably 35 mass% or less, even more preferably 25 mass% or less.

[0048] The total content of the styrene-based compound and the (meth)acrylic acid ester in the raw material monomers of the addition polymerization resin segment is preferably 80 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, and preferably 100 mass% or less, and even more preferably 100 mass%.

[0049] (Structural unit derived from bireactive monomer) When the amorphous polyester resin A is an amorphous composite resin, the amorphous polyester resin A preferably has a constitutional unit derived from a bireactive monomer bonded to a polyester resin segment and an addition polymerization resin segment via a covalent bond. The term "structural unit derived from a bireactive monomer" refers to a unit formed by reaction of a functional group and an addition polymerizable group of a bireactive monomer. An example of the addition polymerizable group is a carbon-carbon unsaturated bond (ethylenically unsaturated bond). Examples of the bireactive monomer include addition polymerizable monomers having at least one functional group selected from a hydroxyl group, a carboxyl group, an epoxy group, a primary amino group, and a secondary amino group in the molecule. Among these, from the viewpoint of reactivity, the bireactive monomer is preferably an addition polymerizable monomer having at least one functional group selected from a hydroxyl group and a carboxyl group, and more preferably an addition polymerizable monomer having a carboxyl group. Examples of the addition polymerizable monomer having a carboxy group include acrylic acid, methacrylic acid, fumaric acid, and maleic acid. Among these, from the viewpoint of reactivity in both the polycondensation reaction and the addition polymerization reaction, it is preferable to use one or more selected from acrylic acid and methacrylic acid, and more preferably acrylic acid. When the bireactive monomer is an addition polymerizable monomer having a carboxy group, the amount of the constitutional unit derived from the bireactive monomer is preferably 1 molar part or more, more preferably 3 molar parts or more, even more preferably 5 molar parts or more, and preferably 30 molar parts or less, more preferably 20 molar parts or less, even more preferably 15 molar parts or less, and still more preferably 10 molar parts or less, relative to 100 molar parts of the alcohol component of the polyester resin segment of the amorphous polyester resin A.

[0050] When the amorphous polyester resin A is an amorphous composite resin, the content of the polyester resin segment in the amorphous composite resin is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less. When the amorphous polyester resin A is an amorphous composite resin, the content of the addition polymerization resin segment in the amorphous composite resin is preferably 5 mass% or more, more preferably 10 mass% or more, even more preferably 15 mass% or more, and preferably 50 mass% or less, more preferably 40 mass% or less, even more preferably 30 mass% or less. When the amorphous polyester resin A is an amorphous composite resin, the content of the structural units derived from bireactive monomers in the amorphous composite resin is preferably 0.1 mass% or more, more preferably 0.3 mass% or more, even more preferably 0.5 mass% or more, and preferably 10 mass% or less, more preferably 5 mass% or less, even more preferably 2 mass% or less. When the amorphous polyester resin A is an amorphous composite resin, the total content of the polyester resin segment, the addition polymerization resin segment, and the structural units derived from the bireactive monomer in the amorphous composite resin is preferably 80 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, and preferably 100 mass% or less, and even more preferably 100 mass%. The above amounts are calculated based on the ratio of the amounts of raw material monomers, bireactive monomers, and radical polymerization initiator for the polyester resin segment and the addition polymerization resin segment, and are based on the mass excluding the amount of dehydration due to polycondensation in the polyester resin segment, etc. When a radical polymerization initiator is used, the mass of the radical polymerization initiator is calculated by including it in the addition polymerization resin segment.

[0051] The amorphous polyester resin A can be obtained, for example, by polycondensing an alcohol component, a carboxylic acid component, and, if necessary, a component derived from modified silicone. For example, the amorphous polyester resin A can be produced by polycondensing an alcohol component, a carboxylic acid component, and a component derived from modified silicone in an inert gas atmosphere at a temperature of 150°C to 250°C using an esterification catalyst if necessary. 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, an esterification promoter such as 3,4,5-trihydroxybenzoic acid (gallic acid), etc., and a radical polymerization inhibitor such as 4-tert-butylcatechol, etc. may be used as necessary.

[0052] In addition, when the amorphous polyester resin A is an amorphous composite resin, it may be produced, for example, by a method including a step A of polycondensing an alcohol component and a carboxylic acid component, and a step B of addition polymerizing raw material monomers of the addition polymerization resin segment and a bireactive monomer. Step B may be carried out after step A, step B may be carried out after step A, or step A and step B may be carried out simultaneously. A method is preferred in which a part of the carboxylic acid component is subjected to a polycondensation reaction in step A, and then step B is carried out, and thereafter the remainder of the carboxylic acid component is added to the polymerization system to further proceed with the polycondensation reaction in step A and the polycondensation reaction with the carboxy group of the bireactive monomer or the constituent moiety derived from the bireactive monomer.

[0053] In step A, for example, it is preferable to produce the polycondensation copolymer by polycondensing an alcohol component and a carboxylic acid component in an inert gas atmosphere at a temperature of 150° C. or higher and 250° C. or lower, using the above-mentioned esterification catalyst, esterification promoter, and radical polymerization inhibitor as necessary. Examples of the radical polymerization initiator for the addition polymerization in step B include peroxides such as dibutyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile). The amount of the radical polymerization initiator used is preferably 1 part by mass or more and 20 parts by mass or less based on 100 parts by mass of the raw material monomer of the addition polymerization resin segment. The temperature of the addition polymerization is preferably 110° C. or higher, more preferably 130° C. or higher, and preferably 230° C. or lower, more preferably 220° C. or lower, and further preferably 210° C. or lower.

[0054] From the viewpoint of improving water repellency and oil resistance, the softening point of the amorphous polyester resin A is preferably 80°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher, and from the same viewpoint, it is preferably 170°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.

[0055] From the viewpoint of improving water repellency and oil resistance, the glass transition temperature of the amorphous polyester resin A is preferably 40° C. or higher, more preferably 45° C. or higher, and even more preferably 50° C. or higher, and is preferably 80° C. or lower, more preferably 70° C. or lower, and even more preferably 65° C. or lower. The glass transition temperature is measured by using a differential scanning calorimeter, specifically, by the method described in the examples.

[0056] From the viewpoint of improving the dispersion stability of the resin particles in an aqueous medium and improving the water repellency and oil resistance, the acid value of the amorphous 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.

[0057] From the viewpoint of improving water repellency and oil resistance, the number average molecular weight of the amorphous polyester A is preferably 1,000 or more, more preferably 1,500 or more, and even more preferably 2,000 or more, and is preferably 10,000 or less, more preferably 8,000 or less, and even more preferably 5,000 or less. In addition, from the viewpoint of improving water repellency and oil resistance, the weight average molecular weight of the amorphous polyester A is preferably 5,000 or more, more preferably 10,000 or more, even more preferably 20,000 or more, and is preferably 50,000 or less, more preferably 40,000 or less, even more preferably 35,000 or less.

[0058] The amorphous polyester resin A may be used alone or in combination of two or more. The softening point, glass transition temperature, acid value, number average molecular weight and weight average molecular weight of the amorphous polyester resin A can be appropriately adjusted by 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. In addition, when two or more types of amorphous polyester resins A are used in combination, the softening point, glass transition temperature, acid value, number average molecular weight and weight average molecular weight of the mixture obtained are preferably within the above-mentioned ranges.

[0059] The polyester resin X may contain a resin other than the amorphous polyester resin A. Examples of the other resins include polyester resins other than the amorphous polyester resin A, acrylic resins such as styrene-acrylic copolymers, and polyurethane resins. Examples of polyester resins other than the amorphous polyester resin A include polyester resins formed from polycondensates of alcohol components and carboxylic acid components exemplified above as the amorphous polyester resin A, urethane-modified polyester resins, and epoxy-modified polyester resins.

[0060] From the viewpoint of improving water repellency and oil resistance, the content of the amorphous polyester resin A in the total amount of the polyester resin X is preferably 40 mass % or more, more preferably 50 mass % or more, even more preferably 60 mass % or more, still more preferably 75 mass % or more, still more preferably 85 mass % or more, still more preferably 95 mass % or more, and preferably 100 mass % or less.

[0061] In the present invention, from the viewpoint of improving water repellency and oil resistance, it is preferable that the polyester resin X is substantially water-insoluble. When the polyester resin X is water-insoluble, the coating layer formed by applying the resin particle dispersion to the paper substrate becomes water-insoluble, and the water repellency and oil resistance can be improved. Here, "substantially water-insoluble" means that when polyester resin X, which has been vacuum dried at 40° C. for 12 hours and has reached a constant weight, is dissolved to saturation in 100 g of water at 25° C., 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.

[0062] 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 metal basic compounds and non-metal basic compounds. 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 functional groups other than these amino groups. Examples of such functional groups include hydroxyl groups. 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 thereof 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.

[0063] The amount of the basic compound used is preferably 50 mol % or more, more preferably 55 mol % or more, further 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 in this case, the degree of neutralization of the polyester resin X 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)

[0064] 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. Furthermore, 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 oil resistance, the content of polyester resin X in the resin particles according to the present invention is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 35% by mass or more, still more preferably 40% by mass or more, and is preferably less than 100% by mass, more preferably 99% by mass or less, even more preferably 95% by mass or less, still more preferably 90% by mass or less, and still more preferably 85% by mass or less.

[0065] From the viewpoint of improving water repellency and oil resistance, the content of the modified silicone oil in the resin particles of the present invention is preferably 0.1 mass% or more, more preferably 1 mass% or more, even more preferably 5 mass% or more, still more preferably 10 mass% or more, and is preferably 80 mass% or less, more preferably 70 mass% or less, even more preferably 65 mass% or less, and still more preferably 60 mass% or less.

[0066] (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-based resin X and modified silicone oil in an aqueous medium. Methods for obtaining a resin particle dispersion include a method of adding a resin containing polyester-based resin X and modified silicone oil to an aqueous medium and carrying out a dispersion treatment using a disperser or the like, a method of gradually adding an aqueous medium to a solution of a resin containing polyester-based resin X and modified silicone oil to carry out phase inversion emulsification, etc. Among these, the method of carrying out phase inversion emulsification is preferred from the viewpoint of improving water repellency and oil resistance.

[0067] The phase inversion emulsification is preferably carried out by first dissolving a resin containing polyester-based resin X and a modified silicone oil in an organic solvent to obtain a solution of a resin containing polyester-based resin X and a modified silicone oil, then adding an aqueous medium to the solution to invert the phase, and then removing the organic solvent. Examples of organic solvents that dissolve resins including polyester resin X and modified silicone oils include ketone-based solvents such as dialkyl ketones having an alkyl group with 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 halogenated alkyl solvents such as dichloromethane and chloroform. Among these, from the viewpoint of dissolving resins including polyester resin X and facilitating removal from the emulsion, preferred are dialkyl ketones having an alkyl group with 1 to 3 carbon atoms, such as acetone and methyl ethyl ketone, and more preferred is methyl ethyl ketone.

[0068] When the 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 the organic solvent, or the polyester-based resin X may be mixed with the other resin. Alternatively, these resins may be simultaneously added to the organic solvent and dissolved to obtain a solution of the resin containing polyester-based resin X and modified silicone oil. The mass ratio of the organic solvent to the resin containing the 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 400 / 100 or less, even more preferably 300 / 100 or less, and still more preferably 250 / 100 or less. When the polyester resin X is a neutralized product of a basic compound, it is preferable to neutralize the polyester resin X by further adding an aqueous solution of the basic compound after obtaining a resin solution containing the polyester resin X. Examples of the basic compound include sodium hydroxide and ammonia. 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 usually carried out at a temperature equal to or lower than the boiling point of the organic solvent.

[0069] The temperature when adding an aqueous medium to a solution of a resin containing polyester-based resin X and modified silicone oil is, from the viewpoint of improving the dispersion stability of the resin particle dispersion, preferably 10° C. or higher, more preferably 20° C. or higher, even more preferably 25° C. or higher, and is preferably 80° C. or lower, 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 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. There is no restriction on the addition rate of the aqueous medium after the phase inversion and the resin particles are obtained. 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 800 parts by mass or less, and even more preferably 700 parts by mass or less.

[0070] After the phase inversion emulsification, from the viewpoint of improving the dispersion stability of the resin particle dispersion, it is preferable to remove the organic solvent from the dispersion obtained by the phase inversion emulsification. 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. When the organic solvent is removed, water is also reduced by azeotropy together with the organic solvent, so that it is preferable to add water to adjust the solid content concentration.

[0071] From the viewpoint of improving water repellency and oil 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 resin particle dispersion is measured by the method described in the Examples.

[0072] From the viewpoint of improving water repellency and oil resistance, the pH of the resin particle dispersion of the present invention at 25° C. is preferably 6.5 or more, more preferably 7.0 or more, and is preferably 9.0 or less, more preferably 8.5 or less. The pH can be measured by the method described in the Examples.

[0073] The surface tension of the resin particle dispersion of the present invention at 20° C. is preferably 50 mN / m or more, more preferably 55 mN / m or more, and is preferably 70 mN / m or less, more preferably 65 mN / m or less. The surface tension can be measured by the method described in the Examples.

[0074] 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 necessary. In addition, since surfactants have a very high affinity for water, the presence of a surfactant in the resin particle dispersion liquid results in the surfactant being contained in the coating layer formed when the resin particle dispersion liquid is applied to paper, resulting in a decrease in water repellency. Therefore, from the viewpoint of improving water repellency and oil resistance, it is preferable that the resin particle dispersion liquid of the present invention does not substantially contain a surfactant. 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. In addition, in the present invention, when producing a resin particle dispersion, the resin particles can be dispersed in an aqueous medium without using a surfactant, by using a method in which a resin containing the above-mentioned polyester-based resin X is added to an aqueous medium and a dispersion treatment is carried out using a dispersing machine or the like, or a method in which an aqueous medium is gradually added to a solution of a resin containing the polyester-based resin X to carry out phase inversion emulsification, thereby making it possible to obtain a resin particle dispersion that is substantially free of surfactant.

[0075] [Coating fluid] The resin particle dispersion of the present invention can be used as a coating liquid as it is, but various additives used in coating liquids can also be added and mixed into the resin particle dispersion as necessary. That is, the coating liquid of the present invention preferably contains the resin particle dispersion. As described 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 viewpoint of improving water repellency, it is preferable that the coating liquid of the present invention also does not substantially contain a surfactant.

[0076] [Manufacturing method of coated paper] From the viewpoint of improving water repellency and oil resistance, the method for producing coated paper of the present invention preferably comprises step 1 of coating the coating liquid on at least one side 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 chip 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 base material is not particularly limited, but from the viewpoints of handling of the coated paper and ease of coating on the paper base material, it is preferably 10 g / m 2 and preferably 200 g / m 2 Less than 150 g / m 2 More preferably, 120 g / m 2 The following is the result.

[0077] The amount of the coating liquid in step 1 is preferably 1 g / m2 in terms of solid content from the viewpoint of improving water repellency and oil resistance. 2 More preferably, 3 g / m 2 More preferably, 5 g / m 2 and preferably 30 g / m 2 Less than or equal to 25 g / m 2 More preferably, 20 g / m2 More preferably, 15 g / m or less 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.

[0078] In the present invention, from the viewpoint of improving water repellency and oil resistance, it is preferable to further include a step 2 of drying the coating liquid applied onto the paper substrate in the step 1. Examples of the drying method in step 2 include static drying, air drying, heat drying, vacuum drying, infrared drying, etc. One or more of the drying methods may be used in combination. Among these, from the viewpoint of ease of operation, at least one 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 the surface of the coating liquid on the paper substrate by bringing a heater close to it, a method of heating the surface of the paper substrate by bringing a heater into contact with the side of the paper substrate opposite to the side on which the coating liquid is applied, 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 oil 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, 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 oil resistance, and is preferably 30 minutes or less, more preferably 15 minutes or less, from the viewpoint of suppressing deformation of the paper base material due to heat and reducing energy.

[0079] [Coated paper] The coated paper of the present invention preferably has a coating layer formed by applying the aforementioned coating liquid to at least one side of a paper substrate. Since the aforementioned coating liquid contains the aforementioned resin particle dispersion, the coating layer of the coated paper of the present invention has excellent water repellency and oil resistance. The coated paper of the present invention can be produced, for example, by the above-mentioned method for producing coated paper. EXAMPLES

[0080] In the following examples, various physical properties were measured by the following methods.

[0081] [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 applying a load of 1.96 MPa with the plunger, and extruding the sample from a nozzle with a diameter of 1 mm and a length of 1 mm. The plunger descent amount 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.

[0082] [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 the 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 temperature was then increased at a rate of 10°C / min to measure the amount of heat. The peak temperature with the largest peak area among the observed endothermic peaks was taken as the maximum endothermic peak temperature. The temperature at the intersection of the extension of the baseline below the maximum endothermic peak temperature and the tangent line showing the maximum slope from the rising part of the peak to the apex of the peak was taken as the glass transition temperature.

[0083] [Crystallinity index] 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 and cooled to 0°C at a rate of 10°C / min. The sample was then left to stand for 1 minute, after which it was heated to 180°C at a rate of 10°C / min and the calorific value was measured. The temperature of the peak with the largest peak area among the observed endothermic peaks was taken as the maximum endothermic peak temperature, and the crystallinity index was calculated according to the following formula. (Crystallization index) = Softening point (℃) / Maximum endothermic peak temperature (℃) [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)].

[0084] [Number average molecular weight and weight average molecular weight of amorphous polyester resin] (1) Preparation of sample solution A polyester resin was dissolved in tetrahydrofuran to a concentration of 0.5 g / 100 mL. The solution was then filtered using a fluororesin filter "FP-200" (manufactured by Sumitomo Electric Industries, Ltd.) with a pore size of 2 μm to remove insoluble components, thereby obtaining a sample solution. (2) Molecular weight measurement Tetrahydrofuran was used as the eluent at a flow rate of 1 mL / min, and the column was stabilized in a thermostatic bath at 40°C. 100 μL of the sample solution was injected into the column for measurement. The number-average molecular weight and weight-average molecular weight of the sample were calculated based on a calibration curve that had been prepared in advance. The calibration curve was created using several types of monodisperse polystyrene (monodisperse polystyrene manufactured by Tosoh Corporation; 2.63 × 10 3 , 2.06×10 4 , 1.02×10 5 (weight average molecular weight (Mw)), monodisperse polystyrene manufactured by GL Sciences Inc.; 2.10 × 10 3 , 7.00×10 3 , 5.04×10 4 (weight average molecular weight (Mw)) as a standard sample. Measuring device: "CO-8010" (manufactured by Tosoh Corporation) Analytical column: "GMHXL" + "G3000HXL" (manufactured by Tosoh Corporation)

[0085] [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 solids concentration was calculated according to the following formula: Solid concentration (mass%) = 100-moisture (mass%)

[0086] [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 / particle size measurement system "ELSZ-2" (Otsuka Electronics Co., Ltd.) Measurement conditions: Cumulant analysis method. The particle concentration to be measured is about 5×10 -3 A dispersion diluted with water to a mass % was placed in a measurement cell, the temperature was 25° C., the number of accumulated measurements was 100, and the refractive index of water (1.333) was entered as the refractive index of the dispersion solvent.

[0087] [Surface tension of resin particle dispersion] A platinum plate was immersed in a cylindrical polyethylene container (diameter 3.6 cm × depth 1.2 cm) containing 5 g of sample adjusted to 20°C, and the static surface tension at 20°C was measured by the Wilhelmy method using a surface tensiometer (manufactured by Kyowa Interface Science Co., Ltd., "CBVP-Z").

[0088] [pH of resin particle dispersion] The pH at 25° C. was measured using a tabletop pH meter “F-71” (manufactured by Horiba, Ltd.) using a pH electrode “6337-10D” (manufactured by Horiba, Ltd.).

[0089] Production Example A1 (Production of Amorphous 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 replaced with nitrogen, and 4828g of propylene oxide (2.2) adduct of bisphenol A, 1374g of terephthalic acid, 35g of tin (II) di(2-ethylhexanoate) and 3.5g of gallic acid were added, and the mixture was heated to 235°C over 1 hour while stirring under a nitrogen atmosphere, and then maintained at 235°C for 5 hours.The pressure in the flask was then further reduced, and the mixture was maintained at 8.3kPa and reacted for 1 hour.The mixture was then returned to atmospheric pressure and cooled to 180°C, after which 480g of fumaric acid, 318g of trimellitic anhydride and 3.5g of 4-tert-butylcatechol were added, and the temperature was raised stepwise by 10°C every hour to 210°C. After maintaining the temperature at 210°C for 2 hours, the pressure in the flask was further reduced and maintained at 8.3 kPa, and the reaction was continued until the softening point reached the temperature shown in Table 1, thereby obtaining amorphous polyester A-1. Various physical properties of the resin are shown in Table 1.

[0090] Production Example A2 (Production of Amorphous Polyester Resin A-2) The inside of a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, a fractionation column into which 95 ° C. hot water was introduced, and a thermocouple was replaced with nitrogen. 2,290 g of 1,2-propanediol, 4,501 g of terephthalic acid, and 35 g of di(2-ethylhexanoate)tin (II) were added, and the temperature was raised stepwise from 180 ° C. to 230 ° C. by 10 ° C. every 2 hours while stirring under a nitrogen atmosphere. After holding at 230 ° C. for 2 hours, the pressure in the flask was further reduced, and the reaction was carried out at 8.3 kPa for 1 hour. After that, the pressure was returned to atmospheric pressure, and the mixture was cooled to 180 ° C., after which the fractionation column was removed, 210 g of fumaric acid and 3.5 g of 4-tert-butylcatechol were added, and the temperature was raised stepwise to 210 ° C. by 10 ° C. every 1 hour. After holding at 210 ° C. for 2 hours, the pressure in the flask was further reduced, and the reaction was carried out at 8.3 kPa until the softening point reached the temperature shown in Table 1, to obtain amorphous polyester A-2. Various physical properties of the resin are shown in Table 1.

[0091] Production Example A3 (Production of Amorphous Polyester Resin A-3) In a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, 3128g of propylene oxide (2.2) adduct of bisphenol A, 726g of ethylene oxide (2.2) adduct of bisphenol A, 1539g of terephthalic acid, and 158g of succinic acid were placed, and the mixture was heated to 160°C while stirring in a nitrogen atmosphere. The mixture was then kept at 160°C, and a mixture of 976g of styrene, 214g of 2-ethylhexyl acrylate, and 119g of di-tert-butyl peroxide was added dropwise to carry out a reaction. Then, 28g of tin (II) di(2-ethylhexanoate) and 2.8g of gallic acid were added, and the mixture was heated to 235°C over 8 hours, and held at 235°C for 10 hours. The pressure in the flask was then further reduced, and the reaction was carried out at 8.3kPa until the softening point shown in Table 1 was reached, to obtain amorphous polyester A-3. Various physical properties of the resin are shown in Table 1.

[0092] Production Example A4 (Production of Amorphous 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 4819 g of a propylene oxide (2.2) adduct of bisphenol A, 686 g of terephthalic acid, and modified silicone "KF-864" (amino-modified silicone, manufactured by Shin-Etsu Chemical Co., Ltd., viscosity (25 ° C): 1700 mm 2 The flask was heated stepwise from 185°C to 235°C at 10°C / hour. The flask was then held at 235°C for 3 hours, the pressure in the flask was further reduced, and the flask was held at 8.3kPa for 1 hour. The flask was then returned to atmospheric pressure and cooled to 180°C. Then, 704g of adipic acid and 582g of trimellitic anhydride were added, and the temperature was raised stepwise to 210°C at 10°C / hour. After holding at 210°C for 1 hour, the pressure in the flask was further reduced, and the reaction was continued at 8.3kPa until the softening point shown in Table 1 was reached, to obtain amorphous polyester A-4. Table 1 shows various physical properties of the resin.

[0093] [Table 1]

[0094] <Example 1> In a four-neck flask equipped with a reflux condenser, a stirrer ("Three-One Motor BL300" (Shinto Scientific Co., Ltd.)) and a thermocouple, 100 g of amorphous polyester resin A-1 as a polyester resin and 1 g of modified silicone oil O-1 as a modified silicone were placed, and mixed with 200 g of methyl ethyl ketone (MEK) at 30°C to dissolve the resin. Next, 9.1 g of a 5N aqueous sodium hydroxide solution was added, and the mixture was stirred for 60 minutes. Next, while stirring at 30°C, 600 g of ion-exchanged water was added dropwise at a rate of 20 mL / min to cause phase inversion emulsification. Thereafter, the temperature was raised to 65°C, and the pressure was gradually reduced from 80 kPa to 30 kPa to distill off methyl ethyl ketone, and further distill off some of the water. After cooling to room temperature, the mixture was filtered through a 150 mesh wire net and the solid content was adjusted to 30 mass% with ion-exchanged water to obtain a resin particle dispersion of Example 1. The properties of the obtained resin particle dispersion are shown in Table 2.

[0095] <Examples 2 to 12 and Comparative Example 1> Resin particle dispersions of Examples 2 to 12 and Comparative Example 1 were obtained in the same manner as in Example 1, except that the types and amounts of polyester resin and modified silicone oil were changed to those shown in Table 2, and the amount of sodium hydroxide aqueous solution or ammonia aqueous solution was changed to those shown in Table 2. In Comparative Example 1, no modified silicone oil was added. The properties of the obtained resin particle dispersion are shown in Table 2.

[0096] The modified silicone oils used in the examples and comparative examples shown in Table 2 are as follows. All modified silicone oils are manufactured by Shin-Etsu Chemical Co., Ltd. O-1: "KF-864", amino-modified silicone (viscosity (25℃): 1700mm 2 / s, functional group equivalent: 3800g / mol) O-2: "KF-865", amino-modified silicone (viscosity (25℃): 110mm 2 / s, functional group equivalent: 5000g / mol) O-3: "X-22-343", epoxy modified silicone (viscosity (25℃): 25mm 2 / s, functional group equivalent: 525g / mol) O-4: "X-22-715", ester modified silicone (viscosity (25℃): 14000mm 2 / s) O-5: "X-22-4015", hydroxyl group modified silicone (viscosity (25℃): 1700mm 2 / s, hydroxyl value: 30mgKOH / g)

[0097] <Preparation of coated paper> (Process 1) The resin particle dispersions obtained in Examples 1 to 12 and Comparative Example 1 were used as coating liquids, and PPC paper "J paper" (basis weight 82 g / m 2 The coating was performed using a bar coater (No. 12) on a 300-ml paper towel (manufactured by FUJIFILM Business Innovation Co., Ltd.). The coating weight is 8g / m2 in terms of solid content. 2 The coating was performed so that the result was as follows. (Process 2) The resin particle dispersion on the paper substrate was then dried for 5 minutes in a dryer at 80°C to obtain coated papers having coating layers on the paper substrate, each of which was formed using the resin particle dispersion obtained in Examples 1 to 12 and Comparative Example 1. The water repellency and oil resistance of each of the obtained coated papers were evaluated by the following methods.

[0098] [Water repellency evaluation] The water repellency was evaluated according to JAPAN TAPPI Paper and Pulp Test Method No. 68:2000. At room temperature, the coated paper was tilted at 45° and a drop of ion-exchanged water was dropped onto the coating layer of the coated paper from 10 mm above. The state of the coating layer after the water drop had passed over was observed and the water repellency was evaluated as follows: R0 to R10. A water repellency of R6 or higher indicates excellent water repellency. The results are shown in Table 2. [Water repellency] R0: A continuous mark of uniform width R2: A continuous mark with a width slightly narrower than that of a water drop R4: A continuous mark that is broken in places and clearly has a width narrower than that of a water drop. 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

[0099] [Evaluation of oil resistance] The above coated paper was placed on a horizontal table, and a drop of salad oil was dropped onto the coating layer of the coated paper from 10 mm above, and left to stand at room temperature for 1 minute. The oil drop on the sample was then wiped off, and the condition of the coated paper's surface after wiping was confirmed, and the oil resistance was evaluated according to the following criteria. If the oil resistance was judged to be L3 or higher, it was considered to have excellent oil resistance. The results are shown in Table 2. [Criteria for judging oil resistance] L5: No oil stains on the paper L4: Slight oil stains L3: Oil stains are visible, but smaller than oil droplets. L2: A stain the same size as an oil droplet is seen. L1: Stains larger than oil droplets are observed.

[0100] [Table 2]

[0101] It can be seen from Table 2 that, compared with the resin particle dispersion of Comparative Example 1, the resin particle dispersions of Examples 1 to 12 can provide coated papers having superior water repellency and oil resistance. [Industrial Applicability]

[0102] According to the present invention, it is possible to obtain coated paper having a coating layer with excellent water- and oil-repellency, 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 the paper can be used for paper labels, wrapping paper, paper containers, etc., which require water resistance.

Claims

1. A resin particle dispersion for paper coating, containing resin particles containing a polyester resin X, wherein the resin particles contain a modified silicone oil, the polyester resin X contains an amorphous polyester resin A containing an alcohol component containing a dihydric or higher alcohol and a carboxylic acid component containing at least one selected from aromatic dicarboxylic acids and aliphatic dicarboxylic acids, and the dispersion medium is water. A resin particle dispersion for paper coating.

2. The resin particle dispersion for paper coating according to claim 1, wherein the modified silicone oil is a modified silicone having at least one selected from an amino group, an epoxy group, an ester group, a hydroxy group, and a carboxy group in a side chain, one end, or both ends.

3. The kinematic viscosity of the modified silicone oil at 25°C is 20 mm ２ / s or more and 15,000 mm ２ / s or less. The resin particle dispersion for paper coating according to claim 1.

4. The resin particle dispersion for paper coating according to claim 1, wherein the content of the modified silicone oil is 1 part by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the polyester resin X in the resin particles.

5. The resin particle dispersion for paper coating according to claim 1, wherein the glass transition temperature of the amorphous polyester resin A is 40°C or higher and 80°C or lower.

6. The resin particle dispersion for paper coating according to claim 1, wherein the surface tension at 20°C is 50 mN / m or more and 65 mN / m or less.

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

8. A coated paper having a coating layer formed by coating the paper substrate on at least one side with the coating liquid according to claim 7.