Paper coating agent

Abstract

To provide a paper coating agent containing resin particles that, when applied to paper, can impart water repellency and oil resistance to the paper, a manufacturing method for the paper coating agent, and coated paper obtained using the paper coating agent.SOLUTION: A paper coating agent comprises resin particles containing a polyester resin and a compound represented by general formula (1), wherein the polyester resin is at least one selected from a polyester resin (A), which is a polycondensate of raw material monomer components comprising an alcohol component and a carboxylic acid component containing succinic acid substituted with a hydrocarbon group having 8 to 20 carbon atoms, and a polyester composite resin (B) comprising a polyester resin segment being a reaction product of raw material monomer components containing an alcohol component and a carboxylic acid component, an addition polymer resin segment, and structural units derived from a bifunctional monomer that bonds these segments via covalent bonds.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Conventionally, paper materials that can be used for paper labels, wrapping paper, paper containers, and the like that require resistance to water and oil have been laminated with plastic films such as polyethylene or polypropylene to impart water resistance or water repellency and oil resistance or oil 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 oil resistance and water repellency as an alternative to lamination.

[0003] For example, Patent Document 1 describes a water- and oil-repellent composition that contains an organopolysiloxane having a specific structure and viscosity, a cellulose-based resin, a carboxylic acid or a salt thereof, water, and a surfactant, and describes that a treatment agent containing this water- and oil-repellent composition can be used to impart water and oil repellency to a paper substrate. Patent Document 2 describes wax-coated paper obtained by applying and drying a mixture of wax, a water-soluble polymeric substance, and silicone oil, and describes that the wax-coated paper has excellent water repellency. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-257159 [Patent Document 2] Japanese Patent Application Publication No. 9-310297 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, treatment with a fluorine-based paper coating agent is known as a technology for imparting water repellency and oil resistance to paper as an alternative to laminating plastic films. However, from the perspectives of safety and environmental considerations, paper coating agents made from non-fluorine-based materials are desired. Silicone is known as a non-fluorine-based material that exhibits water repellency and oil resistance, and both unmodified silicone and modified silicone modified with some functional group are used as silicones. However, the paper substrate treated with a treatment agent containing a water- and oil-repellent composition using unmodified silicone as described in Patent Document 1 and the wax-coated paper described in Patent Document 2 still have room for improvement in water repellency and oil resistance. Also known is a technology for imparting water repellency and oil resistance to paper substrates by using modified silicone with functional groups such as amino groups. However, the production of modified silicone requires the prior copolymerization of special monomers with functional groups, which complicates the production process by requiring the use of special monomers and subsequent purification, resulting in higher costs compared to unmodified silicone. The present invention relates to a paper coating agent containing resin particles for use on paper to solve these problems. [Means for solving the problem]

[0006] The inventors focused on providing a coating layer that prevents contact between paper and water and oil, and discovered that the above-mentioned problem can be solved by using a paper coating agent for forming the coating layer that contains resin particles containing a polyester-based resin, and the resin particles contain a polyester-based resin having a specific structure and a substantially unmodified silicone oil.

[0007] That is, the present invention provides the following [1] to [3]. [1] A paper coating agent containing resin particles containing a polyester resin and a compound represented by the following general formula (1): The polyester resin is A polyester resin (A) which is a polycondensate of raw material monomer components including a divalent or higher alcohol component and a divalent or higher carboxylic acid component including succinic acid substituted with a hydrocarbon group having from 8 to 20 carbon atoms; and a polyester composite resin (B) comprising: a polyester resin segment which is a reaction product of raw material monomer components containing a divalent or higher alcohol component and a divalent or higher carboxylic acid component; an addition-polymerized resin segment; and a structural unit derived from a bireactive monomer which bonds the polyester resin segment and the addition-polymerized resin segment via a covalent bond; The paper coating agent is at least one selected from the following: [ka] (In general formula (1), R 1 and R 2 are each independently a hydrocarbon group having 1 to 6 carbon atoms, X is a hydrocarbon group having 1 to 6 carbon atoms or a monovalent group represented by the following general formula (2), and a plurality of R 1 , R 2 , and X may be the same or different, and m is a positive integer. [ka] (In general formula (2), R 3 and R 4 are each independently a hydrocarbon group having 1 to 6 carbon atoms, and a plurality of R 3 and R 4 may be the same or different, n is a positive integer, and * indicates the bonding position to the silicon atom. [2] A method for producing the paper coating agent according to [1] above, comprising the following steps 1 to 4 in this order: Step 1: Dissolving the polyester resin and the compound represented by general formula (1) in an organic solvent Step 2: Adding a basic compound to neutralize the polyester resin Step 3: A step of adding an aqueous medium to emulsify the polyester resin and the compound represented by general formula (1) by phase inversion. Step 4: Distilling off the organic solvent [3] A coated paper having a coating layer containing a polyester resin and a compound represented by general formula (1) on at least one surface of a paper substrate, The polyester resin is A polyester resin (A) which is a polycondensate of raw material monomer components including a divalent or higher alcohol component and a divalent or higher carboxylic acid component including succinic acid substituted with a hydrocarbon group having from 8 to 20 carbon atoms; and a polyester composite resin (B) comprising: a polyester resin segment which is a reaction product of raw material monomer components containing a divalent or higher alcohol component and a divalent or higher carboxylic acid component; an addition-polymerized resin segment; and a structural unit derived from a bireactive monomer which bonds the polyester resin segment and the addition-polymerized resin segment via a covalent bond; Coated paper, which is at least one type selected from the following: [ka] (In general formula (1), R 1 and R 2 are each independently a hydrocarbon group having 1 to 6 carbon atoms, X is a hydrocarbon group having 1 to 6 carbon atoms or a monovalent group represented by the following general formula (2), and a plurality of R 1 , R 2 , and X may be the same or different, and m is a positive integer. [ka] (In general formula (2), R 3 and R 4 are each independently a hydrocarbon group having 1 to 6 carbon atoms, and a plurality of R 3 and R 4 may be the same or different, n is a positive integer, and * indicates the bonding position to the silicon atom. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a paper coating agent containing resin particles that can impart water repellency and oil resistance to paper by coating the paper, a method for producing the paper coating agent, and coated paper using the paper coating agent. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Paper coating agent] The paper coating agent of the present invention is a paper coating agent containing a polyester resin and resin particles containing a compound represented by general formula (1) as a substantially unmodified silicone oil, wherein the polyester resin is at least one selected from the group consisting of polyester resin (A) which is a polycondensation product of raw material monomer components containing a divalent or higher alcohol component and a divalent or higher carboxylic acid component including succinic acid substituted with a hydrocarbon group having from 8 to 20 carbon atoms, and polyester composite resin (B) which contains a polyester resin segment which is a reaction product of raw material monomer components containing a divalent or higher alcohol component and a divalent or higher carboxylic acid component, an addition polymerization resin segment, and a bireactive monomer-derived structural unit which bonds the polyester resin segment and the addition polymerization resin segment via a covalent bond.

[0010] According to the present invention, coated paper having excellent water repellency and oil resistance can be obtained. The reason for this is not clear, but is thought to be as follows. Polyester resins have many ester bonds in their structure, and because they contain terminal hydroxyl and carboxyl groups, they are highly polar polymers and therefore have a high affinity for paper. Treating paper with polyester resin particles made from such polyester resins can impart various functions, but their high polarity makes it difficult to simultaneously impart water repellency and oil resistance. On the other hand, silicone oil is a low-polarity polymer, so it is thought that it can impart water repellency and oil resistance, but because it is a liquid at room temperature, simply treating paper with it will not allow the silicone oil itself to penetrate into the paper, making it impossible to impart water repellency or oil resistance. Unmodified silicone oil in particular has a significant tendency to penetrate into the paper. In contrast, the paper coating agent of the present invention contains resin particles containing a polyester resin and a silicone oil compound represented by general formula (1). By applying the coating to a paper substrate, the paper is believed to simultaneously impart water repellency and oil resistance to the paper due to the effects of the high-polarity polyester resin and the low-polarity compound represented by general formula (1). The polyester resin is at least one selected from polyester resins containing succinic acid-derived structural units substituted with hydrocarbon groups having 8 to 20 carbon atoms and polyester resins containing addition polymerization resin segments, resulting in a structure with a high-polarity polyester main chain and low-polarity side chains. As a result, the low-polarity compound represented by general formula (1) can be stably incorporated into the polyester resin particles. Furthermore, the high-polarity polyester main chain interacts strongly with the surface of the paper substrate, and the low-polarity side chains have a high affinity with the compound represented by general formula (1). This allows the compound represented by general formula (1), the polyester resin, and the paper substrate to bond together, resulting in excellent water repellency and oil resistance.

[0011] The definitions of various terms used in this specification are shown below. The crystallinity of a resin is expressed 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 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 raw material monomers, and production conditions (e.g., reaction temperature, reaction time, cooling rate), etc. 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. The term "carboxylic acid component" includes not only carboxylic acids but also their anhydrides and alkyl esters having 1 to 3 carbon atoms. In other words, in this specification, when only the name of a carboxylic acid is mentioned, it is understood that the mention also includes the anhydrides and alkyl esters having 1 to 3 carbon atoms of the carboxylic acid. "Modified silicone" means a silicone having a reactive functional group, and the reactive functional group contains a hydrogen atom. "Unmodified silicone" means a silicone having no reactive functional group.

[0012] <Polyester resin> The polyester resin is at least one selected from a polyester resin (A) which is a polycondensation product of raw material monomer components including a divalent or higher alcohol component and a divalent or higher carboxylic acid component including succinic acid substituted with a hydrocarbon group having from 8 to 20 carbon atoms, and a polyester composite resin (B) which includes a polyester resin segment which is a reaction product of raw material monomer components including a divalent or higher alcohol component and a divalent or higher carboxylic acid component, an addition polymerization resin segment, and a bireactive monomer-derived structural unit which bonds the polyester resin segment and the addition polymerization resin segment via a covalent bond. The polyester resin may be a crystalline polyester resin or an amorphous polyester resin, and is preferably an amorphous polyester resin.

[0013] [Polyester resin (A)] The polyester resin (A) is a polycondensate of raw material monomer components including a divalent or higher alcohol component and a divalent or higher carboxylic acid component including succinic acid substituted with a hydrocarbon group having 8 to 20 carbon atoms.

[0014] (alcohol content) The alcohol component contains a dihydric or higher alcohol from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper. 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. Examples of diols include aromatic diols, aliphatic diols, and alicyclic diols.

[0015] An example of an aromatic diol is an alkylene oxide adduct of bisphenol A. From the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the alkylene oxide adduct of bisphenol A is preferably a compound represented by the following formula (I):

[0016] [ka]

[0017] In the above formula (I), OR 1 , and R 2 Each O is an alkyleneoxy group, preferably each independently an alkyleneoxy group having 1 to 4 carbon atoms, more preferably an ethyleneoxy group or a propyleneoxy group. x and y correspond to the number of moles of alkylene oxide added. The average value of the sum of x and y is preferably 2 or more, preferably 7 or less, more preferably 5 or less, and even more preferably 3 or less. x ORs 1 and y R 2 O may be the same or different, but is preferably the same. The alkylene oxide adduct of bisphenol A may be used alone or in combination of two or more. 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.

[0018] When the alcohol component contains an alkylene oxide adduct of bisphenol A, the content of the alkylene oxide adduct of bisphenol A in the alcohol component 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, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, and is preferably 100 mol% or less, more preferably 100 mol%.

[0019] Examples of 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. The aliphatic diol is preferably 1,2-propanediol.

[0020] When the alcohol component contains an aliphatic diol, the content of the aliphatic diol in the alcohol component 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, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper.

[0021] Examples of the alicyclic diol include cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A. Examples of trihydric or higher polyhydric alcohols include glycerin, pentaerythritol, trimethylolpropane, sorbitol, and sorbitan. The other alcohols may be used alone or in combination of two or more.

[0022] 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 is preferably 0.7 or more, more preferably 0.8 or more, and is preferably 1.3 or less, more preferably 1.2 or less.

[0023] (carboxylic acid component) The carboxylic acid component includes succinic acid substituted with a hydrocarbon group having from 8 to 20 carbon atoms. Examples of succinic acid substituted with a hydrocarbon group having from 8 to 20 carbon atoms include alkylsuccinic acids substituted with alkyl groups having from 8 to 20 carbon atoms and alkenylsuccinic acids having alkenyl groups having from 8 to 20 carbon atoms. Of these, dodecenylsuccinic acid and octenylsuccinic acid are preferred, and dodecenylsuccinic acid is more preferred.

[0024] The content of succinic acid substituted with a hydrocarbon group having from 8 to 20 carbon atoms in the carboxylic acid component is preferably 10 mol% or more, more preferably 15 mol% or more, even more preferably 18 mol% or more, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, and is preferably 50 mol% or less, more preferably 47 mol% or less, even more preferably 45 mol% or less.

[0025] Furthermore, the content of succinic acid substituted with a hydrocarbon group having 8 to 20 carbon atoms in the carboxylic acid component is preferably 20% by mass or more, more preferably 23% by mass or more, even more preferably 25% by mass or more, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, and is preferably 60% by mass or less, more preferably 57% by mass or less, even more preferably 55% by mass or less.

[0026] The carboxylic acid component preferably contains a carboxylic acid in addition to succinic acid substituted with a hydrocarbon group having from 8 to 20 carbon atoms. Examples of the other carboxylic acid component include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and trivalent or higher polycarboxylic acids. One type of the other carboxylic acid component may be used alone, or two or more types may be used in combination. Examples of aromatic dicarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, etc. Among these, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the aromatic dicarboxylic acid is preferably isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, or 1,4-naphthalenedicarboxylic acid, more preferably terephthalic acid and 2,6-naphthalenedicarboxylic acid. Examples of aliphatic dicarboxylic acids include fumaric acid, adipic acid, sebacic acid, maleic acid, azelaic acid, succinic acid, cyclohexanedicarboxylic acid, etc. Among these, the aliphatic dicarboxylic acid is preferably fumaric acid, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper. Examples of alicyclic aliphatic dicarboxylic acids include cyclohexanedicarboxylic acid.

[0027] The total content of aromatic dicarboxylic acids and aliphatic dicarboxylic acids, excluding succinic acid substituted with a hydrocarbon group having from 8 to 20 carbon atoms, in the carboxylic acid component is preferably at least 40 mol%, more preferably at least 43 mol%, even more preferably at least 45 mol%, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, and is preferably at most 90 mol%, more preferably at most 85 mol%, even more preferably at most 82 mol%.

[0028] Examples of trivalent or higher polycarboxylic acids include trivalent or higher aromatic polycarboxylic acids. Examples of trivalent or higher aromatic polycarboxylic acids include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, and aconitic acid. Of these, trimellitic acid is preferred as the trivalent or higher polycarboxylic acid, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper.

[0029] From the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the content of trivalent or higher polycarboxylic acids in the carboxylic acid component is preferably 0 mol% or more, more preferably 5 mol% or more, even more preferably 7 mol% or more, and is preferably 15 mol% or less, more preferably 13 mol% or less, even more preferably 11 mol% or less.

[0030] [Polyester-based composite resin (B)] The polyester composite resin (B) comprises a polyester resin segment, which is a reaction product of raw material monomer components containing a divalent or higher alcohol component and a divalent or higher carboxylic acid component, an addition polymerization resin segment, and a bireactive monomer-derived structural unit that bonds the polyester resin segment and the addition polymerization resin segment via a covalent bond.

[0031] (alcohol content) Examples of the alcohol component contained in the raw material monomer component of the polyester resin segment of the polyester composite resin (B) include the same alcohols as those of the polyester resin (A). Among these, the alcohol is preferably at least one selected from a propylene oxide adduct of bisphenol A and an ethylene oxide adduct of bisphenol A.

[0032] From the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the content of the alkylene oxide adduct of bisphenol A in the alcohol component 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 is preferably 100 mol% or less, more preferably 100 mol%.

[0033] (carboxylic acid component) Examples of the carboxylic acid component contained in the raw material monomer component of the polyester resin segment of the polyester composite resin (B) include succinic acid substituted with a hydrocarbon group having 8 to 20 carbon atoms in the polyester resin (A) and carboxylic acids similar to the other carboxylic acid components. Among these, a combination of an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid containing succinic acid substituted with a hydrocarbon group having 8 to 20 carbon atoms is preferred. From the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the aromatic dicarboxylic acid is preferably isophthalic acid or terephthalic acid, more preferably terephthalic acid. Furthermore, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the aliphatic dicarboxylic acid is preferably one or more selected from succinic acid and fumaric acid substituted with a hydrocarbon group having from 8 to 20 carbon atoms, more preferably one or more selected from dodecenylsuccinic acid and fumaric acid.

[0034] From the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the content of aromatic dicarboxylic acid in the carboxylic acid component is preferably 60 mol% or more, more preferably 63 mol% or more, even more preferably 65 mol% or more, and is preferably 90 mol% or less, more preferably 85 mol% or less, even more preferably 82 mol% or less.

[0035] From the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the content of aliphatic dicarboxylic acids in the carboxylic acid component is preferably 10 mol% or more, more preferably 15 mol% or more, even more preferably 18 mol% or more, and is preferably 40 mol% or less, more preferably 37 mol% or less, even more preferably 35 mol% or less.

[0036] (raw material monomer for addition polymerization resin segment) Examples of raw material monomers for the addition polymerization segment of the polyester composite resin (B) include styrene compounds. The term "styrene compound" refers to unsubstituted or substituted styrene. Examples of the substituent substituted on styrene include alkyl groups having 1 to 5 carbon atoms, halogen atoms, and alkoxy groups having 1 to 5 carbon atoms. Examples of styrene compounds include styrene, methylstyrene, α-methylstyrene, β-methylstyrene, tert-butylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, etc. Among these, styrene is preferred. The content of the styrene-based compound in the raw material monomers of the addition polymerization resin segment is preferably 50% by mass or more, more preferably 65% ​​by mass or more, even more preferably 75% 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.

[0037] 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; halovinyl compounds 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.

[0038] The number of carbon atoms in the alkyl group in the alkyl (meth)acrylate is preferably 6 or more, more preferably 8 or more, even more preferably 10 or more, and preferably 24 or less, more preferably 22 or less, even more preferably 20 or less. Examples of alkyl (meth)acrylates include 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, stearyl (meth)acrylate is preferred, and stearyl methacrylate is more preferred. In addition, "(iso)" refers 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.

[0039] The content of alkyl (meth)acrylate in the raw material monomers of the addition polymerization resin segment is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and preferably 50% by mass or less, more preferably 35% by mass or less, even more preferably 25% by mass or less.

[0040] The total content of the styrene compound and the (meth)acrylic acid ester in the raw material monomers of the addition polymerization resin segment is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and preferably 100% by mass or less, and even more preferably 100% by mass.

[0041] The polyester composite resin (B) preferably has a constitutional unit derived from a bireactive monomer bonded via a covalent bond to a polyester resin segment and an addition polymerized resin segment. 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 addition-polymerizable monomers having a carboxy group include acrylic acid, methacrylic acid, fumaric acid, and maleic acid. Among these, from the viewpoint of reactivity in both polycondensation reactions and addition polymerization reactions, one or more selected from acrylic acid and methacrylic acid is preferred, and acrylic acid is more preferred. When the bireactive monomer is an addition-polymerizable monomer having a carboxy group, the amount of the structural unit derived from the bireactive monomer is preferably 1 molar part or more, more preferably 3 molar parts or more, and preferably 15 molar parts or less, more preferably 12 molar parts or less, per 100 molar parts of the alcohol component of the polyester resin segment of the polyester composite resin (B).

[0042] The content of the polyester resin segment in the polyester composite resin (B) is preferably 50% by mass or more, more preferably 55% by mass or more, even more preferably 58% by mass or more, and preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 82% by mass or less. The content of the addition polymerization resin segment in the polyester composite resin (B) is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 18% by mass or more, and preferably 50% by mass or less, more preferably 45% by mass or less, even more preferably 42% by mass or less. The content of the bireactive monomer-derived structural units in the polyester composite resin (B) is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, and is preferably 2% by mass or less, more preferably 1.5% by mass or less, even more preferably 1% by mass or less. The total content of the polyester resin segment, the addition polymerization resin segment, and the bireactive monomer-derived structural unit in the polyester composite resin (B) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and preferably 100% by mass or less, and even more preferably 100% by 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 addition polymerization resin segment, and are based on the mass excluding the amount of water produced by 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.

[0043] The paper coating agent of the present invention may contain other resins in addition to the polyester resin.

[0044] [Method for producing polyester resin] When the polyester-based resin is polyester-based resin (A), polyester-based resin (A) can be obtained by polycondensation of raw material monomer components including a divalent or higher alcohol component and a divalent or higher carboxylic acid component including succinic acid substituted with a hydrocarbon group having 8 to 20 carbon atoms. For example, it can be produced by polycondensing raw material monomer components in an inert gas atmosphere at a temperature of 120° C. or higher and 250° C. or lower, if necessary, using an esterification catalyst. 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.

[0045] When the polyester-based resin is a polyester-based composite resin (B), the polyester-based composite resin (B) 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 an addition-polymerized 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 preferred method is to subject a part of the carboxylic acid component to a polycondensation reaction in step A, then carry out step B, and then add the remainder of the carboxylic acid component to the polymerization system to further promote the polycondensation reaction of step A and the polycondensation reaction with the carboxy group of the bireactive monomer or the constituent moiety derived from the bireactive monomer.

[0046] In step A, for example, the polyol can be produced by polycondensing an alcohol component and a carboxylic acid component in an inert gas atmosphere at a temperature of 120°C or higher and 250°C or lower, using the above-mentioned esterification catalyst, esterification co-catalyst, and radical polymerization inhibitor as necessary.

[0047] Examples of the radical polymerization initiator for the addition polymerization in step B include peroxides such as dibutyl peroxide, 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 10 parts by mass or less with respect to 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.

[0048] (Physical properties of polyester resin) From the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the softening point of the polyester resin is preferably 80°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and is preferably 140°C or lower, more preferably 130°C or lower, even more preferably 120°C or lower.

[0049] From the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the glass transition temperature of the polyester resin is preferably 45°C or higher, more preferably 50°C or higher, and preferably 80°C or lower, more preferably 75°C or lower, even more preferably 70°C or lower, and even more preferably 60°C or lower.

[0050] From the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the acid value of the polyester resin is preferably 3 mgKOH / g or more, more preferably 5 mgKOH / g or more, even more preferably 10 mgKOH / g or more, and is preferably 40 mgKOH / g or less, more preferably 30 mgKOH / g or less.

[0051] The polyester resins may be used alone or in combination of two or more. The softening point, glass transition temperature, and acid value of the polyester resin 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 polyester resins are used in combination, the softening point, glass transition temperature and acid value of the resulting mixture are preferably within the above-mentioned ranges.

[0052] In the present invention, the polyester resin is preferably water-insoluble from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper. When the polyester resin is water-insoluble, the coating layer formed by applying the paper coating agent to the paper substrate becomes more water-insoluble, thereby enabling further improvements in water repellency and oil resistance. Here, "water-insoluble" means that when a polyester resin that has been vacuum dried at 40°C for 12 hours and has 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 the polyester resin contains acid groups, the amount of dissolution is the amount of dissolution when 100 mol % of the acid groups of the polyester resin are neutralized with sodium hydroxide.

[0053] When the polyester resin contains an acid group, the polyester resin 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.

[0054] <Compound represented by general formula (1)> The compound represented by general formula (1) is an unmodified silicone oil. The compound represented by general formula (1) may be used alone or in combination of two or more.

[0055] [ka]

[0056] In general formula (1), R 1 and R 2 are each independently a hydrocarbon group having 1 to 6 carbon atoms, X is a hydrocarbon group having 1 to 6 carbon atoms or a monovalent group represented by the following general formula (2), and a plurality of R 1 , R 2 , and X may be the same or different, and m is a positive integer.

[0057] [ka]

[0058] In general formula (2), R 3 and R 4 are each independently a hydrocarbon group having 1 to 6 carbon atoms, and a plurality of R 3 and R 4 may be the same or different, n is a positive integer, and * indicates the bonding position to the silicon atom.

[0059] In general formula (1), R 1 , R 2 and the hydrocarbon group having 1 to 6 carbon atoms as X includes an alkyl group and an aromatic group, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, a t-butyl group, an isobutyl group, an n-pentyl group, an isopentyl group, an n-hexyl group, and a phenyl group. In general formula (1), from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, R 1 and R 2and are preferably both methyl groups. In general formula (1), from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, X is preferably a hydrocarbon group having 1 to 6 carbon atoms, more preferably a methyl group or a phenyl group.

[0060] In general formula (1), m is preferably 5 or more, more preferably 20 or more, and even more preferably 50 or more, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, and is preferably 3,000 or less, more preferably 2,000 or less, and even more preferably 1,500 or less.

[0061] In general formula (2), R 3 and R 4 The hydrocarbon group having 1 to 6 carbon atoms as R 1 , R 2 and the same groups as the hydrocarbon group having 1 to 6 carbon atoms as X, and preferably both are methyl groups.

[0062] In general formula (2), n is preferably 3 or more, more preferably 10 or more, even more preferably 50 or more, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, and is preferably 1,000 or less, more preferably 800 or less, even more preferably 650 or less.

[0063] The viscosity of the compound represented by general formula (1) is preferably 200 mm from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper. 2 / s or more, preferably 300 mm 2 / s or more, more preferably 400 mm 2 / s or more, and from the viewpoint of manufacturability, it is preferably 20,000 mm 2 / s or less, preferably 15,000 mm 2 / s or less, more preferably 12,000 mm 2 / s or less. The surface tension of the compound represented by general formula (1) is preferably 15 mN / m or more, more preferably 18 mN / m or more, and preferably 25 mN / m or less, more preferably 23 mN / m or less.

[0064] In the paper coating agent of the present invention, the mass ratio of the compound represented by general formula (1) to the polyester resin in the resin particles (compound represented by general formula (1) / polyester resin) is preferably 15 / 85 or more, more preferably 18 / 82 or more, even more preferably 20 / 80 or more, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, and is preferably 35 / 65 or less, more preferably 30 / 70 or more, even more preferably 28 / 72 or more.

[0065] In the paper coating agent of the present invention, the resin particles 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.

[0066] [Manufacturing of paper coating agents] The resin particles contained in the paper coating agent of the present invention are preferably produced by a method of dispersing a polyester resin and a compound represented by general formula (1) in an aqueous medium. Methods for obtaining an aqueous dispersion of resin particles include adding the polyester resin and the compound represented by general formula (1) to an aqueous medium and dispersing them using a disperser or the like, and gradually adding an aqueous medium to a solution containing the polyester resin and the compound represented by general formula (1) to perform phase inversion emulsification. Among these, a method of performing phase inversion emulsification is preferred. A preferred phase inversion emulsification method involves first dissolving the polyester resin and the compound represented by general formula (1) in an organic solvent to obtain a solution of the polyester resin and the compound represented by general formula (1), then adding an aqueous medium to the solution to perform phase inversion emulsification, and then removing the organic solvent.

[0067] That is, the method for producing a paper coating agent of the present invention preferably comprises the following steps 1 to 4 in this order. Step 1: Dissolving a polyester resin and a compound represented by general formula (1) in an organic solvent Step 2: Adding a basic compound to neutralize the polyester resin Step 3: A step of adding an aqueous medium and subjecting the polyester resin and the compound represented by general formula (1) to phase inversion emulsification. Step 4: Distilling off the organic solvent

[0068] [Process 1] Step 1 is a step of dissolving a polyester resin and a compound represented by general formula (1) in an organic solvent. Examples of organic solvents that can dissolve the polyester resin and the compound represented by general formula (1) 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 alkyl halide solvents such as dichloromethane and chloroform. Among these, from the viewpoint of dissolving the polyester resin and the compound represented by general formula (1) 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.

[0069] Either the polyester resin or the compound represented by general formula (1) may be dissolved in an organic solvent first, or both may be dissolved in an organic solvent simultaneously. When the polyester resin contains multiple types of polyester resins, the multiple types of polyester resins may be mixed in advance before being dissolved in an organic solvent.

[0070] The mass ratio of the organic solvent to the total mass of the polyester resin and the compound represented by general formula (1) [organic solvent / total mass of the polyester resin and the compound represented by general formula (1)] is preferably 50 / 100 or more, more preferably 100 / 100 or more, even more preferably 150 / 100 or more, from the viewpoint of dissolving the polyester resin and the compound represented by general formula (1) and facilitating phase transfer to the aqueous medium, and from the viewpoint of further improving the dispersion stability of the resin particles in the aqueous medium, and is preferably 500 / 100 or less, more preferably 400 / 100 or less, even more preferably 300 / 100 or less.

[0071] [Process 2] Step 2 is a step of adding a basic compound to neutralize the polyester resin. Specifically, after obtaining a solution of the polyester resin and the compound represented by general formula (1) in step 1, an aqueous solution of a basic compound is added to neutralize the solution. The addition of the aqueous solution of the basic compound is usually carried out at a temperature equal to or lower than the boiling point of the organic solvent.

[0072] The basic compound includes a metal basic compound and a non-metal basic compound. The basic compounds may be used alone or in combination of two or more. 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.

[0073] The amount of the basic compound used is preferably 45 mol % or more, more preferably 50 mol % or more, and even more preferably 55 mol % or more, and preferably 100 mol % or less, based on the acid value of the polyester resin. The equivalent amount of the basic compound used can be calculated by the following calculation 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, and the degree of neutralization of the polyester resin 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 (mg KOH / g) × mass of polyester resin (g)] / (56.1 × 1000 (mg KOH / mol))]} × 100 (1)

[0074] [Step 3] Step 3 is a step in which an aqueous medium is added to emulsify the neutralized polyester resin and the compound represented by general formula (1) by phase inversion. In the present invention, the term "aqueous system" means that water accounts for the largest proportion of the medium. As the water in the aqueous medium, deionized 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.

[0075] The temperature of the solution of the polyester resin and the compound represented by general formula (1) when adding the aqueous medium is preferably 10°C or higher, more preferably 20°C or higher, and preferably 75°C or lower, more preferably 65°C or lower, from the viewpoint of improving the dispersion stability of the resin particles in the aqueous medium. From the viewpoint of improving the dispersion stability of the resin particles in the aqueous medium, 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 20 parts by mass or less, more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, based on 100 parts by mass of the total mass of the polyester resin constituting the resin particles and the compound represented by general formula (1), until the completion of phase inversion. There is no limitation on the addition rate of the aqueous medium after the phase inversion and the production of the resin particles.

[0076] [Step 4] Step 4 is a step of distilling off the organic solvent. After the phase inversion emulsification in step 3, it is preferable to remove the organic solvent from the aqueous dispersion of the resin particles obtained by the phase inversion emulsification, from the viewpoint of improving the dispersion stability of the resin particles in the aqueous medium. The method for removing the organic solvent is not particularly limited, and any method can be used. The obtained aqueous dispersion of resin particles 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.

[0077] From the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the solids concentration of the aqueous dispersion of resin particles of the present invention is preferably 10% by mass or more, more preferably 15% 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 aqueous dispersion is measured by the method described in the examples.

[0078] The volume median particle diameter (D 50From the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the volume median particle diameter (D) is 0.08 μm or more, and preferably 0.50 μm or less, more preferably 0.35 μm or less, even more preferably 0.30 μm or less, and even more preferably 0.25 μm or less. 50 ) is measured by the method described in the Examples.

[0079] The aqueous dispersion of resin particles can be used as the paper coating agent of the present invention as is. That is, the paper coating agent of the present invention may be a paper coating agent in which resin particles are dispersed in an aqueous medium. Various additives used in paper coating agents can be added and mixed into the aqueous dispersion as needed. Such additives include organic solvents, moisturizers, wetting agents, penetrating agents, viscosity modifiers, antifoaming agents, preservatives, antifungal agents, rust inhibitors, pH adjusters, antioxidants, and ultraviolet absorbers.

[0080] From the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, the paper coating agent of the present invention preferably contains substantially no surfactant. If the paper coating agent contains substantially no surfactant, the coating layer formed by applying the paper coating agent to a paper substrate will have a low affinity for water, thereby improving water repellency. 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. For example, even if the paper coating agent of the present invention contains a surfactant, the content of the surfactant is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, and even more preferably 0.001% by mass or less. Furthermore, in the present invention, when producing an aqueous dispersion of resin particles, a method is used in which an aqueous medium is gradually added to a solution of the above-mentioned polyester resin and the compound represented by general formula (1) to perform phase inversion emulsification, whereby the compound represented by general formula (1) can be dispersed in an aqueous medium without using a surfactant, and a paper coating agent that is substantially free of surfactants can be obtained.

[0081] [Coated paper] The coated paper of the present invention has a coating layer containing a polyester resin and a compound represented by general formula (1) on at least one surface of a paper substrate.

[0082] <Paper base material> Examples of paper substrates 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 More preferably, 30 g / m 2 More preferably, 50 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.

[0083] <Polyester resin> The polyester resin contained in the coating layer is at least one selected from the polyester resin (A) and the polyester composite resin (B). The polyester resin may also contain other polyester resins. Examples of other polyester resins that can be used include the polyester resins listed above for the paper coating agent.

[0084] <Compound represented by general formula (1)> As the compound represented by general formula (1) contained in the coating layer, the compound represented by general formula (1) above can be used, and the preferred examples are also the same.

[0085] [Manufacturing method of coated paper] The method for producing coated paper includes step I of applying the paper coating agent to at least one side of a paper substrate to form a coating layer, and step II of drying the coating layer on the paper substrate coated in step I. As the paper substrate, the paper substrates listed above for the paper coating agent can be used, and the preferred examples are also the same.

[0086] [Process I] Step I is a step of applying a paper coating agent to at least one surface of a paper substrate to form a coating liquid layer. The amount of the paper coating agent applied in step I is preferably 1 g / m2 in terms of solid content, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper. 2 More preferably, 3 g / m 2 More preferably, 5 g / m 2 More preferably, 10 g / m 2 and preferably 30 g / m 2 Less than 25 g / m 2 More preferably 20 g / m or less 2 Below are the results. The method for applying the paper coating agent to the paper substrate in step I 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.

[0087] [Process II] Step II is a step of drying the layer of coating liquid on the paper substrate coated in Step I. Examples of the drying method in Step II 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 by applying warm air to the surface of the coating liquid layer on the paper substrate, a method of heating by bringing a heater close to the surface of the coating liquid layer 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 layer has been formed, and a method of heating by steam curing using high-temperature steam at normal or high pressure. 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, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, and is preferably 200°C or lower, more preferably 150°C or lower, and even more preferably 130°C or lower, from the viewpoint of suppressing deformation of the paper base material due to heat and reducing energy consumption. The drying time is preferably 3 minutes or more, more preferably 5 minutes or more, from the viewpoint of improving the water repellency and oil resistance of the resulting coated paper, and is preferably 30 minutes or less, more preferably 15 minutes or less, from the viewpoint of suppressing deformation of the paper base due to heat and reducing energy consumption. [Example]

[0088] In the following examples, various physical properties were measured by the following methods. In the following examples, room temperature refers to 20 to 25°C.

[0089] [Resin softening point] Using a flow tester "CFT-500EX" (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 extruded from a nozzle 1 mm in diameter and 1 mm in length. The plunger length 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.

[0090] [Crystallinity index] Using a differential scanning calorimeter "Q-20" (TA Instruments Japan), 0.01-0.02 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 endothermic peak with the largest area was defined as the endothermic maximum peak temperature (1), and the crystallinity index was calculated by (softening point (°C)) / (endothermic maximum peak temperature (1) (°C)).

[0091] [Glass transition temperature of resin] Using a differential scanning calorimeter "Q-20" (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 endothermic peak area was designated the maximum endothermic peak temperature (2). For amorphous resins, if a peak was observed, the peak temperature was used. If a step was observed without a peak, the glass transition temperature was determined as the temperature at the intersection of the tangent line showing the maximum slope of the curve at the step and the extension of the baseline on the low-temperature side of the step.

[0092] [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)].

[0093] [Volume median particle size of resin particles (D 50 )] The volume median particle size (D 50 ) was measured. (1) Measuring device: Laser diffraction / scattering particle size distribution measuring device "LA-960V2" (manufactured by Horiba, Ltd.) (2) Measurement conditions: A flow cell is used as the measurement cell, deionized water is used as the dispersion medium, and the measurement sample is added so that the absorbance is within the appropriate range. 50 ) was measured.

[0094] [Solid content concentration of aqueous dispersion of resin particles] Using a heat-drying moisture meter "MX-50" (manufactured by A&D Co., Ltd.), 5 g of the measurement sample was dried at a drying temperature of 150°C, in standard measurement mode, with a standard heating pattern and ACCURACY: LO, 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%)

[0095] [Production of polyester resin] Production Example 1 (Production of Polyester Resin A-1) The inside of a four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 3183 g of propylene oxide (2.2) adduct of bisphenol A, 1267 g of ethylene oxide (2.2) adduct of bisphenol A, 971 g of terephthalic acid, 1330 g of dodecenylsuccinic anhydride, 35 g of tin (II) di(2-ethylhexanoate), and 0.7 g of gallic acid were added. Under a nitrogen atmosphere, the temperature was raised to 235 ° C. with stirring, and after 8 hours, the pressure in the flask was further reduced and maintained at 8.3 kPa for 1 hour. After returning to atmospheric pressure, the flask was cooled to 210 ° C., and 249 g of trimellitic anhydride was added. After 1 hour at 210 ° C., the pressure in the flask was further reduced and maintained at 8.3 kPa, and the reaction was continued until the softening point shown in Table 1 was reached, to obtain polyester resin A-1. The physical properties of the obtained polyester resin A-1 are shown in Table 1.

[0096] Production Example 2 (Production of Polyester Resin B-1) A four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was purged with nitrogen. 2947 g of propylene oxide (2.2) adduct of bisphenol A, 880 g of terephthalic acid, 35 g of tin(II) di(2-ethylhexanoate), and 0.7 g of gallic acid were added. The mixture was heated to 235°C under a nitrogen atmosphere with stirring. After maintaining the temperature at 235°C for 5 hours, the pressure inside the flask was reduced and maintained at 8 kPa for 1 hour. The mixture was then returned to atmospheric pressure, cooled to 160°C, and, while maintaining the temperature at 160°C, a mixture of 2009 g of styrene, 502 g of stearyl methacrylate, 61 g of acrylic acid, and 101 g of dibutyl peroxide was added dropwise over 3 hours. After maintaining the temperature at 160°C for 30 minutes, the mixture was heated to 200°C. The pressure inside the flask was further reduced and maintained at 8 kPa for 1 hour. The pressure was then returned to atmospheric pressure, cooled to 190°C, 313 g of fumaric acid and 3.5 g of 4-tert-butylcatechol were added, and the temperature was raised to 210°C over 2 hours and maintained at 210°C for 1 hour. After that, the pressure in the flask was further reduced and maintained at 8.3 kPa, and the reaction was carried out until the softening point shown in Table 1 was reached, yielding Polyester Resin B-1. The physical properties of the obtained Polyester Resin B-1 are shown in Table 1.

[0097] Production Example 3 (Production of Polyester Resin A-2) A four-neck flask equipped with a nitrogen inlet tube, dehydration tube, stirrer, and thermocouple was purged with nitrogen. 1,895 g of 1,2-propanediol, 2,277 g of terephthalic acid, 913 g of dimethyl 2,6-naphthalenedicarboxylate, 35 g of tin(II) di(2-ethylhexanoate), and 0.7 g of gallic acid were added. Under a nitrogen atmosphere, the mixture was heated to 180°C with stirring, held for 1 hour, and then heated to 220°C over 8 hours. After holding at 220°C for 1 hour, the pressure inside the flask was further reduced and held at 8.3 kPa for 1 hour. After returning to atmospheric pressure, 1,915 g of dodecenylsuccinic anhydride was added, and the mixture was held at 220°C for 2 hours. The pressure inside the flask was then further reduced and held at 8.3 kPa, and the reaction proceeded until the softening point reached the value shown in Table 1, yielding Polyester Resin A-2. The physical properties of the resulting Polyester Resin A-2 are shown in Table 1.

[0098] Production Example 4 (Production of Polyester Resin B-2) 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 2585 g of a propylene oxide (2.2) adduct of bisphenol A, 1029 g of an ethylene oxide (2.2) adduct of bisphenol A, 1401 g of terephthalic acid, 35 g of tin(II) di(2-ethylhexanoate), and 0.7 g of gallic acid were added. The mixture was heated to 235°C under a nitrogen atmosphere with stirring. After maintaining the temperature at 235°C for 8 hours, the pressure inside the flask was reduced and maintained at 8 kPa for 1 hour. The pressure was then returned to atmospheric pressure and cooled to 160°C. While maintaining the temperature at 160°C, a mixture of 1009 g of styrene, 252 g of stearyl methacrylate, 46 g of acrylic acid, and 51 g of dibutyl peroxide was added dropwise over 1 hour. The temperature was then maintained at 160°C for 30 minutes, after which it was raised to 200°C, the pressure inside the flask was further reduced, and the mixture was maintained at 8 kPa for 1 hour. The pressure was then returned to atmospheric pressure, cooled to 220°C, 540 g of dodecenylsuccinic anhydride was added, and the mixture was maintained at 220°C for 1 hour. The pressure inside the flask was then further reduced, and the mixture was maintained at 8.3 kPa, and the reaction was continued until the softening point shown in Table 1 was reached, yielding polyester resin B-2. The physical properties of the resulting polyester resin B-2 are shown in Table 1.

[0099] Production Example 5 (Production of Polyester Resin B'-1) The inside of a four-neck flask equipped with a nitrogen inlet tube, dehydration tube, stirrer, and thermocouple was replaced 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 14 g of tin 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 and reacted until the softening point listed in Table 1 was reached, yielding polyester resin B'-1. The physical properties of the resulting polyester resin B'-1 are shown in Table 1.

[0100] Production Example 6 (Production of Polyester Resin A'-1) A four-neck flask equipped with a nitrogen inlet tube, dehydration tube, stirrer, and thermocouple was purged with nitrogen. 3546 g of propylene oxide (2.2) adduct of bisphenol A, 1411 g of ethylene oxide (2.2) adduct of bisphenol A, 1081 g of terephthalic acid, 683 g of succinic acid, 35 g of tin(II) di(2-ethylhexanoate), and 0.7 g of gallic acid were added. Under a nitrogen atmosphere, the mixture was heated to 235°C with stirring and maintained for 8 hours. The pressure inside the flask was then reduced to 8.3 kPa and maintained for 1 hour. After returning to atmospheric pressure, the mixture was cooled to 210°C, and 278 g of trimellitic anhydride was added. The mixture was then maintained at 210°C for 1 hour. The pressure inside the flask was then reduced to 8.3 kPa and the reaction was continued until the softening point reached the value shown in Table 1, yielding polyester resin A'-1. The physical properties of the resulting polyester resin A'-1 are shown in Table 1.

[0101] [Table 1]

[0102] [Manufacturing of paper coating agents] Example 1-1 (Production of Paper Coating Agent X-1) A 2 L four-neck flask equipped with a reflux condenser, a stirrer, and a thermocouple was charged with 150 g of polyester resin A-1 as a polyester resin and 50 g of compound S1 (KF-96A-3000CS, manufactured by Shin-Etsu Chemical Co., Ltd.) represented by general formula (1), and mixed with 400 g of methyl ethyl ketone at room temperature. The mixture was then heated to 65° C. and dissolved. The mixture was then cooled to room temperature, and a 5 mass % aqueous sodium hydroxide solution was added at room temperature to achieve a degree of neutralization of 65 mol % relative to the acid value of amorphous polyester resin A-1, and the mixture was stirred for 60 minutes. Next, 600 g of deionized water was added dropwise at a rate of 10 mL / min under stirring at room temperature to cause phase inversion emulsification. The temperature was then raised to 65°C, and while maintaining the temperature at 65°C, the pressure was gradually reduced from 80 kPa to 30 kPa to distill off the methyl ethyl ketone, and then some of the water was distilled off. After cooling to room temperature, the mixture was filtered through a 150-mesh wire screen and the solids concentration was adjusted to 30 mass% with deionized water to obtain paper coating agent X-1 as a resin particle dispersion. The volume median particle diameter (D 50 ) are shown in Table 2.

[0103] Examples 1-2 to 1-7 (Production of Paper Coating Agents X-2 to X-7) Paper coating agents X-2 to X-7 were obtained as resin particle dispersions in the same manner as in Example 1-1, except that the types of polyester resin and compound represented by general formula (1) in Example 1-1 were changed to those shown in Table 2. The volume median particle diameter (D 50 ) are shown in Table 2.

[0104] Comparative Example 1-1 (Production of Paper Coating Agent X-11) A 2-liter four-neck flask equipped with a reflux condenser, a stirrer, and a thermocouple was charged with 200 g of polyester resin A-2 as a polyester resin, and mixed with 400 g of methyl ethyl ketone at room temperature, and the mixture was dissolved by heating to 65° C. Next, the mixture was cooled to room temperature, and a 5% by mass aqueous solution of sodium hydroxide was added at room temperature so as to achieve a degree of neutralization of 65 mol% relative to the acid value of amorphous polyester resin A-2, and the mixture was stirred for 60 minutes. Next, 600 g of deionized water was added dropwise at a rate of 10 mL / min under stirring at room temperature to cause phase inversion emulsification. The temperature was then raised to 65°C, and while maintaining the temperature at 65°C, the pressure was gradually reduced from 80 kPa to 30 kPa to distill off methyl ethyl ketone, and then some of the water was distilled off. After cooling to room temperature, the mixture was filtered through a 150-mesh wire screen and the solids concentration was adjusted to 30 mass% with deionized water to obtain paper coating agent X-11 as a resin particle dispersion. The volume median particle diameter (D 50 ) are shown in Table 2.

[0105] Comparative Examples 1-2 and 1-3 (Production of Paper Coating Agents X-12 and X-13) Paper coating agents X-12 and X-13 were obtained in the same manner as in Example 1-1, except that the polyester resin in Example 1-1 was changed to the polyester resin shown in Table 2. When the dispersion was produced and cooled to room temperature, compound S1 represented by general formula (1) was seen floating on the surface of the dispersion in the paper coating agent, and when the dispersion was subsequently filtered through a 150-mesh wire net, residual silicone oil was seen on the wire net.

[0106] The compounds S1 to S4 represented by the general formula (1) used in Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-3 are as follows. S1: Dimethyl silicone oil "KF-96A-3000CS" (in general formula (1), R 1 =R 2 =X=methyl group, viscosity=3000mm 2 / s, surface tension = 21.3 mN / m, manufactured by Shin-Etsu Chemical Co., Ltd.) S2: Dimethyl silicone oil "KF-96A-500CS" (in general formula (1), R 1 =R 2 =X=methyl group, viscosity=500mm 2 / s, surface tension = 21.1 mN / m, manufactured by Shin-Etsu Chemical Co., Ltd.) S3: Dimethyl silicone oil "KF-96A-10000CS" (in general formula (1), R 1 =R 2 = X = methyl group, viscosity = 10000mm 2 / s, surface tension = 21.3 mN / m, manufactured by Shin-Etsu Chemical Co., Ltd.) S4: Methylphenyl silicone oil "KF-50-1000CS" (in general formula (1), R 1 =R 2 = methyl group, X = methyl group and phenyl group, viscosity = 1000 mm 2 / s, surface tension = 22.6 mN / m, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0107] [Table 2]

[0108] Example 2-1 (Production of Coated Paper 1) (Process 1) The paper base material was PPC paper "J paper" (basis weight 82 g / m 2 Paper coating agent X-1 was applied to a paper substrate (manufactured by Fujifilm Business Innovation Co., Ltd.) using a bar coater (No. 20) to form a coating liquid layer. The paper coating agent X-1 was applied to the paper substrate at a coating amount of 17 g / m2 in terms of solid content. 2 It was done so that it would be like this. (Process 2) The paper coating layer on the paper substrate was then dried for 5 minutes in a dryer at 110°C to obtain a coated paper having a coating layer on the paper substrate. The water repellency and oil resistance of the obtained coated paper were evaluated.

[0109] [Water repellency evaluation] Water repellency was evaluated in accordance with JAPAN TAPPI Paper and Pulp Test Method No. 68:2000. At room temperature, coated paper was tilted at a 45° angle, and a droplet of deionized 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 a water repellency rating of R0 to R10 was determined. R10 represents the highest water repellency rating, and R0 represents the lowest. The results are shown in Table 3. [Water repellency] R10: Completely rolls down R9: Small spherical droplets scattered here and there R8: More than 1 / 4 of the mark is made up of scattered spherical droplets R7: 1 / 4 of the mark is wetted by elongated water droplets R6: Half of the mark is wet R4: A continuous mark that is broken in places and clearly shows a width narrower than that of a water droplet R2: A continuous mark with a width slightly narrower than that of a water droplet R0: Continuous marks of uniform width

[0110] [Evaluation of oil resistance] Coated paper was placed on a horizontal table, and a drop of castor oil was dropped from 10 mm above the coated paper and allowed to stand for 1 minute. The oil drop was then wiped off, and the condition of the paper after wiping was checked. The oil resistance was evaluated using the following criteria: L5 was rated as the highest oil resistance, and L1 was rated as the lowest. The results are shown in Table 3. 〔Judgment criteria〕 L5: No oil stains are visible on the paper. L4: Slight oil stains are visible. L3: Oil stains are visible but smaller than oil droplets. L2: A stain the same size as an oil droplet is observed. L1: Stains larger than oil droplets are observed.

[0111] Examples 2-2 to 2-7 and Comparative Examples 2-1 to 2-3 Coated paper was obtained in the same manner as in Example 2-1, except that the paper coating agent in Example 2-1 was changed to the paper coating agent shown in Table 3. The water repellency and oil resistance of the obtained coated paper are shown in Table 3.

[0112] [Table 3]

[0113] Table 3 shows that the coated papers produced in the Examples have superior water repellency and oil resistance compared to the coated papers produced in the Comparative Examples. [Industrial Applicability]

[0114] According to the present invention, coated paper having a coating layer with excellent water repellency and oil resistance can be obtained, and can be used for paper labels, packaging paper, paper containers, etc. that require resistance to water and oil.

Claims

1. A paper coating agent containing resin particles containing a polyester resin and a compound represented by the following general formula (1): The polyester resin is A polyester resin (A) which is a polycondensate of raw material monomer components including a divalent or higher alcohol component and a divalent or higher carboxylic acid component including succinic acid substituted with a hydrocarbon group having from 8 to 20 carbon atoms; and a polyester composite resin (B) comprising: a polyester resin segment which is a reaction product of raw material monomer components containing a divalent or higher alcohol component and a divalent or higher carboxylic acid component; an addition-polymerized resin segment; and a structural unit derived from a bireactive monomer which bonds the polyester resin segment and the addition-polymerized resin segment via a covalent bond; The paper coating agent is at least one selected from the following: 【Chemistry 1】 (In general formula (1), R １ and R ２ are each independently a hydrocarbon group having 1 to 6 carbon atoms, X is a hydrocarbon group having 1 to 6 carbon atoms or a monovalent group represented by the following general formula (2), and a plurality of R １ , R ２ , and X may be the same or different, and m is a positive integer. 【Chemistry 2】 (In general formula (2), R ３ and R ４ are each independently a hydrocarbon group having 1 to 6 carbon atoms, and a plurality of R ３ and R ４ may be the same or different, n is a positive integer, and * indicates the bonding position to the silicon atom.

2. 2. The paper coating agent according to claim 1, wherein the polyester-based resin comprises the polyester-based resin (A), and the content of succinic acid substituted with a hydrocarbon group having 8 to 20 carbon atoms in the carboxylic acid component is 10 mol % to 50 mol %.

3. 2. The paper coating agent according to claim 1, wherein the polyester-based resin comprises the polyester-based composite resin (B), and the content of the addition polymerization resin segment in the polyester-based composite resin (B) is 10% by mass or more and 50% by mass or less.

4. 2. The paper coating agent according to claim 1, wherein in the general formula (1), X is a hydrocarbon group having 1 to 6 carbon atoms.

5. 5. The paper coating agent according to claim 4, wherein in the general formula (1), X is a methyl group or a phenyl group.

6. The viscosity of the compound represented by the general formula (1) is 200 mm ２ / s or more 20,000mm ２ 2. The paper coating agent according to claim 1, wherein the viscosity is 1 / s or less.

7. 7. A method for producing a paper coating agent according to claim 1, comprising the following steps 1 to 4 in this order: Step 1: Dissolving the polyester resin and the compound represented by general formula (1) in an organic solvent Step 2: Adding a basic compound to neutralize the polyester resin Step 3: A step of adding an aqueous medium to emulsify the polyester resin and the compound represented by general formula (1) by phase inversion. Step 4: Distilling off the organic solvent

8. A coated paper having a coating layer containing a polyester resin and a compound represented by general formula (1) on at least one surface of a paper substrate, The polyester resin is A polyester resin (A) which is a polycondensate of raw material monomer components including a divalent or higher alcohol component and a divalent or higher carboxylic acid component including succinic acid substituted with a hydrocarbon group having from 8 to 20 carbon atoms; and a polyester composite resin (B) comprising: a polyester resin segment which is a reaction product of raw material monomer components containing a divalent or higher alcohol component and a divalent or higher carboxylic acid component; an addition-polymerized resin segment; and a structural unit derived from a bireactive monomer which bonds the polyester resin segment and the addition-polymerized resin segment via a covalent bond; Coated paper, which is at least one selected from the following: 【Transformation 3】 (In general formula (1), R １ and R ２ are each independently a hydrocarbon group having 1 to 6 carbon atoms, X is a hydrocarbon group having 1 to 6 carbon atoms or a monovalent group represented by the following general formula (2), and a plurality of R １ , R ２ , and X may be the same or different, and m is a positive integer. 【Chemistry 4】 (In general formula (2), R ３ and R ４ are each independently a hydrocarbon group having 1 to 6 carbon atoms, and a plurality of R ３ and R ４ may be the same or different, n is a positive integer, and * indicates the bonding position to the silicon atom.

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