Coating liquid, coated product, molded body and release paper

Abstract

To provide a coating liquid excellent in air permeability, silicone curability, and adhesion to a substrate.SOLUTION: The coating liquid contains a modified vinyl alcohol-based polymer having a group represented by the following formula (1). In the formula (1), R1 represents a C1-8 alkyl group, an alkoxy group having a C1-8 alkyl group, a hydroxyl group, or a group represented by -OM; M represents an alkali metal or an alkaline earth metal; R2 represents a group containing a siloxane structure; n represents an integer of 1-3; when there are a plurality of R1's, the plurality of R1's may be the same or different; and when there are a plurality of R2's, the plurality of R2's may be the same or different.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a coating liquid, a coated article, a molded body, and a release paper. [Background technology]

[0002] Vinyl alcohol polymers (hereinafter sometimes abbreviated as "PVA") are unique synthetic polymers that are hydrophilic and crystalline, and are used in the paper industry as paper strength agents, dispersants for fluorescent white pigments, and binders for inorganic substances (calcium carbonate, clay, silica, etc.). In addition, because PVA has excellent film-forming properties, coating it on paper can impart barrier properties against gases and oil resistance.

[0003] PVA-coated paper is sometimes used as barrier paper, and a typical example of barrier paper is release paper base paper. Release paper base paper is typically produced by coating the surface of a cellulose substrate with PVA. Release paper is then obtained by forming a release layer (silicone layer) on the surface of this release paper base paper. The PVA in release paper acts as a filler, preventing the penetration of expensive silicone or platinum into the substrate. Recently, there has been a demand for release paper base paper that not only has this filler property but also accelerates the curing of the silicone in the release layer and improves the adhesion between the PVA layer and the silicone layer.

[0004] Patent Document 1 describes a release paper base paper coated with PVA having a silyl group that meets specific conditions. Patent Document 2 describes PVA in which a double bond has been introduced into the side chain by an acetalization reaction. However, these documents do not disclose a coating liquid that is excellent in air permeability, silicone curability, and adhesion to the substrate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-194672 [Patent Document 2] Special Publication No. 2013-531136 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to provide a coating fluid that is excellent in air permeability, silicone curability, and adhesion to a substrate, and a coated product, a molded article, and a release paper obtained by applying the coating fluid to a substrate. [Means for solving the problem]

[0007] As a result of extensive investigations, the present inventors have found that the above problems can be solved by preparing a coating liquid containing a modified vinyl alcohol polymer having a specific group, and have thus completed the present invention.

[0008] That is, the present invention includes the following disclosed embodiments. [1] A coating solution containing a modified vinyl alcohol polymer having a group represented by the following formula (1): [ka] In the above formula (1), R 1 is an alkyl group having 1 to 8 carbon atoms, an alkoxy group having an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OM. M is an alkali metal or an alkaline earth metal. R 2 is a group containing a siloxane structure. n is an integer of 1 to 3. R 1 If there are multiple, multiple R 1 may be the same or different. 2 If there are multiple, multiple R 2 may be the same or different. [2] R in the above modified vinyl alcohol polymer 2 A coating liquid [1], wherein [ka] In the above formula (2), a plurality of R 3are each independently an alkyl group having 1 to 20 carbon atoms, an alkoxy group having an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a phenyl group, a benzyl group, a halogenated alkyl group having 1 to 8 carbon atoms, a halogenated phenyl group, an aminoalkyl group having 1 to 8 carbon atoms, a mercaptoalkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OQ. Q is an alkali metal or an alkaline earth metal. [3] The coating solution according to [1] or [2], wherein the content of the siloxane structure relative to the total monomer units of the modified vinyl alcohol polymer is 0.001 mol % or more; [4] The coating solution according to any one of [1] to [3], wherein the content of the siloxane structure relative to all monomer units derived from silyl group-containing monomers in the modified vinyl alcohol polymer is 50 mol % or more; [5] The coating solution according to any one of [1] to [4], wherein the viscosity-average degree of polymerization of the modified vinyl alcohol polymer is 500 or more and 5,000 or less, and the degree of saponification is 70 mol % or more and 99.9 mol % or less; [6] The coating solution according to any one of [1] to [5], wherein the insoluble content of the modified vinyl alcohol polymer in the coating solution is 1000 ppm or less; [7] A coating solution containing a modified vinyl alcohol polymer having a monomer unit derived from a silyl group-containing monomer and modified with a silane coupling agent; [8] The coating solution according to [7], wherein the amount of modification with the silane coupling agent relative to the total monomer units of the modified vinyl alcohol polymer is 0.001 mol % or more; [9] The coating solution according to [7] or [8], wherein the amount of modification with the silane coupling agent relative to all monomer units derived from silyl group-containing monomers in the modified vinyl alcohol polymer is 50 mol % or more;

[10] A coated product obtained by applying the coating liquid according to any one of [1] to [9] to a substrate.

[11] A molded article having a layer containing a modified vinyl alcohol polymer having a group represented by the following formula (1): [ka] In the above formula (1), R 1is an alkyl group having 1 to 8 carbon atoms, an alkoxy group having an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OM. M is an alkali metal or an alkaline earth metal. R 2 is a group containing a siloxane structure. n is an integer of 1 to 3. R 1 If there are multiple, multiple R 1 may be the same or different. 2 If there are multiple, multiple R 2 may be the same or different.

[12] A release paper comprising a substrate, a silicone filling layer, and a release layer, wherein the silicone filling layer contains a modified vinyl alcohol polymer having a group represented by the following formula (1): [ka] In the above formula (1), R 1 is an alkyl group having 1 to 8 carbon atoms, an alkoxy group having an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OM. M is an alkali metal or an alkaline earth metal. R 2 is a group containing a siloxane structure. n is an integer of 1 to 3. R 1 If there are multiple, multiple R 1 may be the same or different. 2 If there are multiple, multiple R 2 may be the same or different.

[13] The release paper of

[12] , wherein the release layer contains addition silicone and platinum, and the amount of platinum blended per 100 parts by weight of the addition silicone is 0.001 to 0.05 parts by weight. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a coating liquid that, when applied to a release paper base paper, provides excellent silicone sealing properties, promotes the curing of the silicone in the release layer, and improves the adhesion between the substrate and the release layer, as well as a release paper base paper using the same. Furthermore, according to the present disclosure, it is possible to provide a release paper obtained using the release paper base paper. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Modified vinyl alcohol polymer> Vinyl alcohol polymer (PVA) is a polymer containing vinyl alcohol units as monomer units. PVA is obtained by saponifying a vinyl ester polymer obtained by polymerizing vinyl ester monomers, which are raw material monomers for PVA. After saponification, the PVA may contain vinyl ester units in addition to vinyl alcohol units.

[0011] Furthermore, PVA can be obtained by saponifying a copolymer obtained by copolymerizing a vinyl ester monomer, which is the raw material monomer, with other monomers to obtain PVA containing monomer units other than vinyl alcohol units and vinyl ester units, or by reacting a specific chemical species with PVA during or after saponification to obtain PVA with specific functional groups. In this disclosure, such PVA is referred to as a "modified vinyl alcohol polymer (modified PVA)," and a monomer other than a vinyl ester monomer, which is a raw material monomer for PVA containing monomer units other than vinyl alcohol units and vinyl ester units, may be referred to as a "modified species." In this disclosure, a (modified) vinyl ester polymer before saponification of the (modified) PVA may be referred to as a "precursor" of the (modified) PVA. Here, a "modified vinyl ester polymer" refers to a vinyl ester polymer containing monomer units other than vinyl ester units.

[0012] The coating fluid of the present disclosure contains a modified PVA having a constitutional unit represented by the following formula (1).

[0013] [ka] Here, in the above formula (1), R 1 is an alkyl group having 1 to 8 carbon atoms, an alkoxy group having an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OM. M is an alkali metal or an alkaline earth metal. R 2 is a group containing a siloxane structure. n is an integer of 1 to 3. R 1If there are multiple, multiple R 1 may be the same or different. 2 If there are multiple, multiple R 2 may be the same or different.

[0014] The presence of the group represented by formula (1) in the modified PVA improves the water solubility of the modified PVA. Although the reason for this is not entirely clear, it is presumed that the presence of the group represented by formula (1) in the modified PVA increases the bulkiness around the highly reactive sites containing silicon atoms (e.g., silanol sites), thereby appropriately weakening the interaction between the highly reactive sites containing silicon atoms in the modified PVA and the vinyl alcohol sites.

[0015] In the present disclosure, the term "siloxane structure" refers to a structure (-O-Si-) formed by bonding one oxygen atom and one silicon atom. The siloxane structure may also be referred to as a siloxane bond. The type of atom to which three of the four bonds of one silicon atom that constitute one siloxane structure are bonded, which are not bonded to the oxygen atoms that constitute the siloxane structure, is not particularly limited. The type of atom to which one of the two bonds of one oxygen atom that constitutes one siloxane structure that is not bonded to the silicon atom that constitutes the siloxane structure is bonded is also not particularly limited. However, it is preferable that one of the two bonds of one oxygen atom that constitutes one siloxane structure that is not bonded to the silicon atom that constitutes the siloxane structure is also bonded to another silicon atom. The other silicon atom is preferably the silicon atom represented by Si in formula (1).

[0016] R 1 Examples of the alkyl group having 1 to 8 carbon atoms represented by the formula include a methyl group, an ethyl group, a propyl group, a butyl group, etc. The alkyl group preferably has 1 to 4 carbon atoms, and more preferably 1 or 2 carbon atoms. R 1Examples of the alkoxy group having an alkyl group having 1 to 8 carbon atoms represented by the formula (I) include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, etc. The number of carbon atoms in the alkyl group of this alkoxy group is preferably 1 to 4, and more preferably 1 or 2. Alkali metals represented by M include sodium, potassium, etc. Alkaline earth metals represented by M include magnesium, calcium, etc.

[0017] When n in formula (1) is 1 or 2, one or two R 1 Preferably, R contains an alkoxy group having an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OM. 1 is preferably an alkoxy group having an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OM.

[0018] R in Equation (1) 2 The group represented by the formula (a group containing a siloxane structure) is preferably a group in which an oxygen atom constituting the siloxane structure is bonded to a silicon atom represented by Si in formula (1), and more preferably a group represented by the following formula (2): 2 The group represented by the formula (I) may also be a group containing multiple siloxane structures (for example, polysiloxane chains).

[0019] [ka]

[0020] In the above formula (2), a plurality of R 3 are each independently an alkyl group having 1 to 20 carbon atoms, an alkoxy group having an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a phenyl group, a benzyl group, a halogenated alkyl group having 1 to 8 carbon atoms, a halogenated phenyl group, an aminoalkyl group having 1 to 8 carbon atoms, a mercaptoalkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OQ. Q is an alkali metal or an alkaline earth metal.

[0021] R3 Examples of the alkyl group having 1 to 20 carbon atoms represented by the formula: 1 Examples of the alkyl group having 1 to 8 carbon atoms represented by R 3 The alkyl group represented by the following formula (I) preferably has 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms. R 3 As the alkoxy group having an alkyl group having 1 to 8 carbon atoms represented by the formula: 1 Examples of the alkoxy group having an alkyl group having 1 to 8 carbon atoms represented by the formula: 3 The alkyl group of the alkoxy group represented by the following formula (I) preferably has 1 to 4 carbon atoms, and more preferably 1 or 2 carbon atoms. R 3 Examples of the alkenyl group having 2 to 5 carbon atoms represented by R include a vinyl group, an allyl group, and a 2-methylallyl group. 3 The alkenyl group represented by the following formula preferably has 2 to 4 carbon atoms, more preferably 2 carbon atoms. R 3 Examples of the halogen contained in the halogenated alkyl group having 1 to 8 carbon atoms and the halogenated phenyl group represented by the formula (I) include fluorine, chlorine, and bromine. R 3 Examples of the aminoalkyl group having 1 to 8 carbon atoms represented by the formula (R) include an aminomethyl group, a 2-aminoethyl group, and a 3-aminopropyl group. 3 The aminoalkyl group represented by the following formula preferably has 1 to 4 carbon atoms. R 3 Examples of the mercaptoalkyl group having 1 to 8 carbon atoms and represented by the formula (R) include a mercaptomethyl group, a 2-mercaptoethyl group, and a 3-mercaptopropyl group. 3 The mercaptoalkyl group represented by the following formula preferably has 1 to 4 carbon atoms. Alkali metals represented by Q include sodium, potassium, etc. Alkaline earth metals represented by Q include magnesium, calcium, etc.

[0022] The three R in Equation (2) 3Preferably, the three R in formula (2) contain an alkoxy group. 3 The number of alkoxy groups in the formula (2) is preferably 1 or 2. From the viewpoint of viscosity stability, the number of the three R 3 The number of alkoxy groups in the formula (2) is preferably 1. From the viewpoint of the water resistance of the film, 3 The number of alkoxy groups therein is preferably 2.

[0023] In formula (1), n ​​is preferably 1 or 2, and more preferably 1.

[0024] The lower limit of the content of the group represented by formula (1) relative to all monomer units in the modified PVA is preferably 0.001 mol%, more preferably 0.005 mol%, even more preferably 0.01 mol%, even more preferably 0.05 mol%, even more preferably 0.10 mol%, and in some cases particularly preferably 0.16 mol%. The upper limit of the content of the group represented by formula (1) relative to all monomer units is not particularly limited, but may be, for example, 0.30 mol% or 0.25 mol%. Furthermore, the content of the group represented by formula (1) relative to all monomer units in the modified PVA is preferably 0.001 mol% to 0.30 mol%, more preferably 0.005 mol% to 0.30 mol%, even more preferably 0.01 mol% to 0.30 mol%, even more preferably 0.05 mol% to 0.30 mol%, even more preferably 0.10 mol% to 0.30 mol%, and particularly preferably 0.16 mol% to 0.25 mol%. Furthermore, in one embodiment of the modified PVA described below, for example, the content of the group represented by formula (1) may be the same as the amount of silyl group modification. That is, for example, all of the monomer units derived from the silyl group-containing modified species introduced into the modified PVA may have the group represented by formula (1).

[0025] In the present disclosure, the term "monomer unit" refers to the smallest repeating unit derived from a monomer and having a portion including a main chain. One monomer unit may be formed from only one monomer, or may be formed from one monomer and one or more other compounds (for example, a silane coupling agent, etc., as described below).

[0026] The lower limit of the content of the siloxane structure (-O-Si-) relative to all monomer units in the modified PVA is preferably 0.001 mol%, more preferably 0.005 mol%, even more preferably 0.01 mol%, even more preferably 0.05 mol%, even more preferably 0.10 mol%, and in some cases particularly preferably 0.16 mol%. The upper limit of the content of the siloxane structure relative to all monomer units is not particularly limited, but may be, for example, 0.30 mol% or 0.25 mol%. Furthermore, the content of the siloxane structure (—O—Si—) relative to all monomer units in the modified PVA is preferably 0.001 mol % or more and 0.30 mol % or less, more preferably 0.005 mol % or more and 0.30 mol % or less, even more preferably 0.01 mol % or more and 0.30 mol % or less, even more preferably 0.05 mol % or more and 0.30 mol % or less, still more preferably 0.10 mol % or more and 0.30 mol % or less, and in some cases 0.16 mol % or more and 0.25 mol % or less is particularly preferred.

[0027] The lower limit of the content of the group represented by formula (2) relative to all monomer units in the modified PVA is preferably 0.001 mol%, more preferably 0.005 mol%, even more preferably 0.01 mol%, even more preferably 0.05 mol%, even more preferably 0.10 mol%, and in some cases particularly preferably 0.16 mol%. The upper limit of the content of the group represented by formula (2) relative to all monomer units is not particularly limited, but may be, for example, 0.30 mol% or 0.25 mol%. The content of the group represented by formula (2) relative to the total monomer units in the modified PVA is preferably 0.001 mol% or more and 0.30 mol% or less, more preferably 0.005 mol% or more and 0.30 mol% or less, even more preferably 0.01 mol% or more and 0.30 mol% or less, even more preferably 0.05 mol% or more and 0.30 mol% or less, even more preferably 0.10 mol% or more and 0.30 mol% or less, and in some cases, particularly preferably 0.16 mol% or more and 0.25 mol% or less. 2 is a group represented by the above formula (2), the content of the group represented by the above formula (2) is usually equal to the content of the siloxane structure, unless other modifications have been made.

[0028] The group or siloxane structure represented by formula (1) in the modified PVA is, for example, 1 For example, in the case of a modified PVA obtained by saponifying a copolymer of vinyl acetate and vinyltrimethoxysilane in the presence of methyltrimethoxysilane, which is one embodiment of the modified PVA of the present disclosure as described below, 1 The siloxane structure can be confirmed from the structure derived from methyltrimethoxysilane in the modified PVA measured by H-NMR. An example of a specific measurement method in this case is as follows. The modified PVA is dissolved in DO and a sample is subjected to NMR at 400 MHz. 1When measured by H-NMR at room temperature, the peak derived from the methine group of the vinyl alcohol unit is at 3.3 to 4.2 ppm (integral value α), and the peak derived from the methyl group in the structure derived from methyltrimethoxysilane is at around -0.5 to 0.5 ppm (integral value β). From the integral values ​​α and β, the content of the structure derived from methyltrimethoxysilane, i.e., the siloxane structure, relative to the total monomer units can be calculated using the following formula (I): Siloxane structure (structure derived from methyltrimethoxysilane) content (mol%) ={(β / 3) / (α+β / 3)}×100 ···(I) The content determined by the above method is equal to the content of Si-O-Si structures. In the case of modified PVAs obtained by saponifying a copolymer of vinyl acetate and vinyltrimethoxysilane in the presence of methyltrimethoxysilane, the content of siloxane structures relative to all monomer units determined by the above method is equal to the content of the group represented by formula (2) relative to all monomer units. Furthermore, in the case of modified PVAs obtained by saponifying a copolymer of vinyl acetate and vinyltrimethoxysilane in the presence of methyltrimethoxysilane, it is considered difficult for two or more methyltrimethoxysilanes to react with one monomer unit derived from vinyltrimethoxysilane due to steric hindrance and other factors. In other words, n in the above formula (1) is usually considered to be 1. Therefore, the content of siloxane structures relative to all monomer units determined by the above method is considered to be substantially equal to the content of the group represented by formula (1) relative to all monomer units.

[0029] The modified PVA of the present disclosure generally has a monomer unit having a group represented by the above formula (1). Examples of the monomer unit having a group represented by the above formula (1) include a monomer unit represented by the following formula (3):

[0030] [ka]

[0031] In formula (3), R 4 is a hydrogen atom or a methyl group. 5R is a single bond or a divalent linking group. 6 is a group represented by the above formula (1).

[0032] R 5 Examples of the divalent linking group represented by the formula include -(CH2) m -(m is an integer of 1 to 4), -CONR 7 -(CH2) q -(R 7 is a hydrogen atom or a methyl group. q is an integer of 0 to 4.) and the like. In addition, the divalent linking group is the above-mentioned -(CH2) m -and above-CONR 7 -(CH2) q -, -O-, -NR 8 -(R 8 is a hydrogen atom or a methyl group.

[0033] A preferred embodiment of the modified PVA in the present disclosure is a modified PVA obtained by copolymerizing a monomer having a silyl group (hereinafter also referred to as a "silyl group-containing monomer" or a "silyl group-containing modified species") with a vinyl ester monomer, and saponifying the resulting modified vinyl ester polymer (hereinafter also referred to as a "silyl group-modified vinyl ester polymer") in the presence of a silane coupling agent to introduce a group represented by formula (1) into the side chain of the PVA. In other words, a modified PVA having monomer units derived from a silyl group-containing monomer and modified with a silane coupling agent is also one embodiment of the modified PVA in the present disclosure.

[0034] In the present disclosure, the term "silyl group" refers to a group represented by -SiH3 and a group in which one or more of the three hydrogen atoms of the group represented by -SiH3 have been substituted with other atoms or substituents. From the standpoint of reactivity, the silyl group is preferably one having a hydroxyl group or one having a group (such as an alkoxy group) that reveals a hydroxyl group upon hydrolysis or the like.

[0035] The lower limit of the modification amount of the silane coupling agent relative to the total monomer units in the modified PVA is preferably 0.001 mol%, more preferably 0.005 mol%, even more preferably 0.01 mol%, even more preferably 0.05 mol%, even more preferably 0.10 mol%, and sometimes particularly preferably 0.16 mol%. The upper limit of the modification amount of the silane coupling agent relative to the total monomer units in the modified PVA is not particularly limited, but may be, for example, 0.30 mol% or 0.25 mol%. Furthermore, the amount of modification by the silane coupling agent relative to all monomer units in the modified PVA is preferably 0.001 mol% or more and 0.30 mol% or less, more preferably 0.005 mol% or more and 0.30 mol% or less, even more preferably 0.01 mol% or more and 0.30 mol% or less, even more preferably 0.05 mol% or more and 0.30 mol% or less, still more preferably 0.10 mol% or more and 0.30 mol% or less, and in some cases 0.16 mol% or more and 0.25 mol% or less is particularly preferred.

[0036] The modification amount of the silane coupling agent is the amount of silane coupling agent bonded. Specifically, the modification amount of the silane coupling agent relative to the total monomer units in the modified PVA is the number of structures derived from the silane coupling agent relative to the total number of monomer units in the modified PVA. For example, in the case of the modified PVA obtained by saponifying the above-mentioned copolymer of vinyl acetate and vinyltrimethoxysilane in the presence of methyltrimethoxysilane, when one methyltrimethoxysilane, which is a silane coupling agent, is bonded, one structure derived from methyltrimethoxysilane is formed. Therefore, the content (mol%) of siloxane structures (structures derived from methyltrimethoxysilane) relative to the total monomer units calculated by the above formula (I) is equal to the modification amount (mol%) of the silane coupling agent relative to the total monomer units.

[0037] The lower limit of the silyl group modification amount in the modified PVA is preferably 0.05 mol%, more preferably 0.08 mol%, and even more preferably 0.1 mol% in some cases. The upper limit of the silyl group modification amount is preferably 1.0 mol%, more preferably 0.8 mol%, and even more preferably 0.5 mol% in some cases. The silyl group modification amount in the modified PVA is preferably 0.05 mol% to 1.0 mol%, more preferably 0.08 mol% to 0.8 mol%, and even more preferably 0.1 mol% to 0.5 mol% in some cases. When the silyl group modification amount is within the above range, the effect of the silyl group tends to be more effectively exhibited, and the water solubility of the resulting modified PVA tends to be better. Note that the silyl group modification amount of the modified PVA in the present disclosure refers to the content of all monomer units derived from silyl group-containing monomers (silyl group-containing modified species) relative to the total monomer units in the modified PVA.

[0038] All monomer units derived from silyl group-containing monomers include both monomer units derived from silyl group-containing monomers that are not modified with a silane coupling agent, and monomer units derived from silyl group-containing monomers that are modified with a silane coupling agent. That is, a monomer unit having a group represented by the above formula (1) is also one of the monomer units derived from silyl group-containing monomers. In addition, monomer units derived from silyl group-containing monomers also include those that have been modified by methods other than modification with a silane coupling agent, such as hydrolysis.

[0039] The amount of silyl group modification of the modified PVA is, for example, 1 For example, the silyl group-modified vinyl ester polymer, which is a precursor of the modified PVA, can be obtained by H-NMR. 1 By measuring with H-NMR, it is possible to determine the amount of silyl group modification of the modified PVA. For example, in the case of a modified PVA using vinyltrimethoxysilane as a silyl group-containing modified species, the silyl group-modified vinyl ester polymer, which is the precursor of the modified PVA, is 1The amount of silyl group modification may be determined by H-NMR. In this case, an example of a specific measurement method is as follows. The sample silyl group-modified vinyl ester polymer is purified by reprecipitation three or more times using a mixed solution of n-hexane and acetone, and then dried under reduced pressure at 80°C for three days to prepare a modified vinyl ester polymer for analysis. Next, the modified vinyl ester polymer for analysis is dissolved in DMSO-d6 and dried at 20°C. 1 H-NMR (400 MHz) is measured. The amount of silyl group modification can be calculated using the measured peak (integral value A: 4.5 to 5.2 ppm) derived from the main chain methine proton of the vinyl ester unit and the peak (integral value B: 3.4 to 3.6 ppm) derived from the methyl proton of the silyl group (trimethoxysilyl group) according to the following formula (II). Silyl group modification amount (mol%) ={(B / 9) / (A+B / 9)}×100 (II)

[0040] The lower limit of the content of the group represented by the above formula (1), the group represented by the above formula (2), or the siloxane structure relative to all monomer units derived from silyl group-containing monomers in the modified PVA may be, for example, 40 mol%, preferably 50 mol%, more preferably 60 mol%.Similarly, the lower limit of the amount of modification with a silane coupling agent relative to all monomer units derived from silyl group-containing monomers in the modified PVA may be, for example, 40 mol%, preferably 50 mol%, more preferably 60 mol%.In such cases, since a large proportion of the monomer units derived from silyl group-containing monomers are modified with a silane coupling agent, the effect of the silane coupling agent modification can be particularly fully exerted. The upper limit of the content of the group represented by the above formula (1), the group represented by the above formula (2) or the siloxane structure relative to all the monomer units derived from the silyl group-containing monomer in the modified PVA, and the upper limit of the modification amount of the silane coupling agent relative to all the monomer units derived from the silyl group-containing monomer in the modified PVA may be, for example, 100 mol%. However, since multiple silane coupling agents may react with the monomer units derived from the silyl group-containing monomer in the modified PVA, the content of the group represented by the above formula (2) or the siloxane structure relative to all the monomer units derived from the silyl group-containing monomer in the modified PVA, and the modification amount of the silane coupling agent relative to all the monomer units derived from the silyl group-containing monomer in the modified PVA may exceed 100 mol%. The content of the group represented by the formula (1), the group represented by the formula (2), or the siloxane structure relative to all monomer units derived from silyl group-containing monomers in the modified PVA is preferably 50 mol% to 100 mol%, more preferably 60 mol% to 80 mol%. Similarly, the amount of modification with a silane coupling agent relative to all monomer units derived from silyl group-containing monomers in the modified PVA is preferably 50 mol% to 100 mol%, more preferably 60 mol% to 80 mol%.

[0041] The modified PVA of the present disclosure may contain, in addition to monomer units derived from vinyl ester monomers (vinyl alcohol units and vinyl ester units) and monomer units derived from silyl group-containing monomers, monomer units derived from other monomers. For example, a modified PVA according to a preferred embodiment of the present disclosure contains ethylene units. The content of ethylene units (ethylene modification amount) relative to the total monomer units of the modified PVA is preferably less than 20 mol%, and in some cases, less than 10 mol% is more preferable. When the ethylene modification amount is within the above range, the water solubility of the modified PVA may be improved. The lower limit of the content of ethylene units (ethylene modification amount) relative to the total monomer units of the modified PVA may be, for example, 0.1 mol% or 1 mol%. When the ethylene modification amount is equal to or greater than the above lower limit, the water resistance of the resulting film can be further improved.

[0042] When the modified PVA contains ethylene units, the amount of ethylene modification is, for example, 1 For example, in the same manner as the amount of silyl group modification described above, the amount of silyl group modification can be determined by using a modified vinyl ester polymer, which is a precursor of the modified PVA. 1 The amount of ethylene modification in modified PVA can be determined by measuring with H-NMR.

[0043] The lower limit of the proportion of vinyl alcohol units to all monomer units in the modified PVA of the present disclosure is preferably 35 mol%, more preferably 50 mol%, even more preferably 70 mol%, even more preferably 80 mol%, and in some cases particularly preferably 90 mol%, while the upper limit of the proportion of vinyl alcohol units is preferably 99.95 mol%.

[0044] The upper limit of the content of the vinyl ester monomer-derived monomer units, the silyl group-containing monomer-derived monomer units, and the monomer units other than the ethylene unit relative to the total monomer units in the modified PVA of the present disclosure is preferably 10 mol %, and in some cases, more preferably 1 mol % or 0.1 mol %, which can more fully exhibit the effects of the silyl group modification.

[0045] The lower limit of the viscosity-average degree of polymerization of the modified PVA is preferably 100, more preferably 200, even more preferably 500, even more preferably 1,000, and sometimes even more preferably 2,000. The upper limit of the viscosity-average degree of polymerization of the modified PVA is preferably 5,000, more preferably 4,000, and sometimes even more preferably 3,000. The viscosity-average degree of polymerization of the modified PVA is preferably 100 or more and 5,000 or less, more preferably 500 or more and 5,000 or less, and sometimes even more preferably 1,000 or more and 3,000 or less. Having a viscosity-average degree of polymerization within the above range tends to facilitate production. The viscosity-average degree of polymerization is a value obtained by measurement in accordance with JIS K 6726:1994. Specifically, when the degree of saponification of the modified PVA is less than 99.5 mol%, the viscosity-average degree of polymerization can be calculated by the following formula using the intrinsic viscosity [η] (liters / g) of the modified PVA saponified to a degree of saponification of 99.5 mol% or more, measured in water at 30°C. P = ([η] × 10 4 / 8.29) (1 / 0.62)

[0046] The lower limit of the saponification degree of the modified PVA is preferably 30 mol%, more preferably 65 mol%, even more preferably 70 mol%, even more preferably 80 mol%, even more preferably 85 mol%, and sometimes particularly preferably 90 mol%. Meanwhile, the upper limit of the saponification degree of the modified PVA is preferably 99.9 mol%, more preferably 99.0 mol%, and sometimes even more preferably 98.5 mol%. The saponification degree of the modified PVA is preferably 30 mol% to 99.9 mol%, more preferably 65 mol% to 99.9 mol%, even more preferably 70 mol% to 99.9 mol%, even more preferably 80 mol% to 99.0 mol%, even more preferably 85 mol% to 99.0 mol%, and sometimes particularly preferably 90.0 mol% to 98.5 mol%. By setting the saponification degree of the modified PVA within the above range, the effect of improving water solubility can be further enhanced, and the modified PVA tends to be produced more stably industrially. The degree of saponification of the modified PVA is measured by the method described in JIS K 6726:1994.

[0047] <Method of producing modified vinyl alcohol polymer> The method for producing the modified PVA of the present disclosure preferably includes a step of saponifying a modified vinyl ester polymer having a silyl group in the presence of a silane coupling agent.

[0048] Furthermore, a preferred embodiment of the method for producing a modified PVA of the present disclosure includes a step (polymerization step) of copolymerizing a silyl group-containing monomer (silyl group-containing modified species) with a vinyl ester monomer to obtain a silyl group-modified vinyl ester polymer, and a step (saponification step) of saponifying the silyl group-modified vinyl ester polymer (silyl group-containing modified vinyl ester polymer) in the presence of a silane coupling agent. For example, by saponifying the silyl group-modified vinyl ester polymer in the presence of a silane coupling agent as described above, a siloxane structure can be introduced into the resulting modified PVA, thereby obtaining a modified PVA having a group represented by formula (1). The silyl group-containing modified species and the silane coupling agent may be the same or different chemical species.

[0049] [Polymerization process] The modified vinyl ester polymer, which serves as a precursor to the modified PVA of the present disclosure, can be produced by polymerizing a vinyl ester monomer with a silyl group-containing monomer or other monomers using a conventionally known method such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, or dispersion polymerization. To enhance the effects of the present disclosure, a solution polymerization method in which polymerization is carried out using a lower alcohol is preferred. While the lower alcohol is not particularly limited, alcohols having 3 or fewer carbon atoms, such as methanol, ethanol, propanol, and isopropanol, are preferred, with methanol being more preferred. The polymerization procedure can be performed using any of a batch method, semi-batch method, and continuous method.

[0050] Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, vinyl caproate, vinyl caprylate, vinyl laurate, vinyl palmitate, vinyl stearate, vinyl oleate, and vinyl benzoate. Of these, vinyl acetate is preferred.

[0051] The silyl group-containing monomer (silyl group-containing modified species) preferably has a structure represented by the following formula (4).

[0052] [ka]

[0053] In equation (4), where R 11 is a functional group having a polymerizable multiple bond. 12 and R 13 are each independently an alkyl group having 1 to 8 carbon atoms, an alkoxy group having an alkyl group having 1 to 8 carbon atoms, or an acetoxy group. 14 is an alkyl group having 1 to 8 carbon atoms, an aromatic hydrocarbon group, or an acetyl group.

[0054] R 11The functional group having a polymerizable multiple bond represented by the formula (I) is preferably a group having a carbon-carbon unsaturated double bond, and examples thereof include a vinyl group, an allyl group, a styryl group, and a (meth)acrylalkyl group.

[0055] R 12 and R 13 As the alkyl group, an alkoxy group having an alkyl group of 1 to 8 carbon atoms is preferred, and an alkoxy group having an alkyl group of 1 to 4 carbon atoms, or even 1 or 2 carbon atoms, is more preferred.

[0056] R 14 Examples of the aromatic hydrocarbon group represented by R include a phenyl group, a tolyl group, and a naphthyl group, and a phenyl group is preferred. 14 As the alkyl group, an alkyl group having 1 to 8 carbon atoms is preferred, and an alkyl group having 1 to 4 carbon atoms, and further an alkyl group having 1 or 2 carbon atoms is more preferred.

[0057] Examples of silyl group-containing monomers (silyl group-containing modified species) include vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, allyltrimethoxysilane, allylmethyldimethoxysilane, allyldimethylmethoxysilane, allyltriethoxysilane, allylmethyldiethoxysilane, allyldimethylethoxysilane, vinyltris(β-methoxyethoxy)silane, vinylisobutyldimethoxysilane, and vinylethyl Dimethoxysilane, vinyl methoxydibutoxysilane, vinyl dimethoxybutoxysilane, vinyl tributoxysilane, vinyl methoxydihexyloxysilane, vinyl dimethoxyhexyloxysilane, vinyl trihexyloxysilane, vinyl methoxydioctyloxysilane, vinyl dimethoxyoctyloxysilane, vinyl trioctyloxysilane, vinyl methoxydilauryloxysilane, vinyl dimethoxylauryloxysilane, vinyl methoxydioleyloxysilane, vinyl dimethoxyoleyloxysilane, 3-(meth)acrylamide-propyl Trimethoxysilane, 3-(meth)acrylamido-propyltriethoxysilane, 3-(meth)acrylamido-propyltri(β-methoxyethoxy)silane, 2-(meth)acrylamido-ethyltrimethoxysilane, 1-(meth)acrylamido-methyltrimethoxysilane, 2-(meth)acrylamido-2-methylpropyltrimethoxysilane, 2-(meth)acrylamido-isopropyltrimethoxysilane, N-(2-(meth)acrylamido-ethyl)-aminopropyltrimethoxysilane, (3-(meth)acrylamido-propyl N-(2-(meth)acrylamide-ethyl)-oxypropyltrimethoxysilane, 3-(meth)acrylamide-propyltriacetoxysilane, 2-(meth)acrylamide-ethyltriacetoxysilane, 4-(meth)acrylamide-butyltriacetoxysilane, 3-(meth)acrylamide-propyltripropionyloxysilane, 2-(meth)acrylamide-2-methylpropyltriacetoxysilane, N-(2-(meth)acrylamide-ethyl)-aminopropyltriacetoxysilane, 3-(meth)acrylamide-propylisobutyldimethoxysilaneExamples include 2-(meth)acrylamide-ethyldimethylmethoxysilane, 3-(meth)acrylamide-propylmethyldiacetoxysilane, 2-(meth)acrylamide-2-methylpropylhydrogendimethoxysilane, 3-(N-methyl-(meth)acrylamide)-propyltrimethoxysilane, 2-(N-ethyl-(meth)acrylamide)-ethyltriacetoxysilane, and styryltrimethoxysilane. Among these, vinyltrimethoxysilane is preferred because it can be easily produced industrially and is available at low cost.

[0058] In addition, when the silyl group-containing monomer has an acyloxy group such as an acetoxy group (for example, R 12 or R 13 is an acetoxy group, and R 14 is an acetyl group), a monomer unit having a hydroxyl group or the like is usually formed by hydrolysis. The hydroxyl group may be in the form of a salt. However, a monomer unit in the form of an acyloxy group such as an acetoxy group may also be present in the modified PVA.

[0059] In the modified PVA of the present disclosure, other monomers besides the vinyl ester monomer and the silyl group-containing monomer may be copolymerized within the scope of the present disclosure. Examples of other monomers include α-olefins such as ethylene, propylene, n-butene, and isobutylene; (meth)acrylic acid and its salts; (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate; (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, diacetone(meth)acrylamide, (meth)acrylamidopropanesulfonic ... Examples of suitable compounds include acrylamide compounds such as amidopropyldimethylamine and its salts or quaternary salts, N-methylol(meth)acrylamide and its derivatives; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene halides such as vinylidene chloride and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and fumaric acid and their salts or esters; and isopropenyl acetate. These compounds may be used alone or in combination. The amount of copolymerization of other monomers (the amount of modification of other monomers) is preferably 10 mol% or less. In this disclosure, "(meth)acrylic" collectively refers to methacrylic and acrylic.

[0060] The polymerization initiator used in the polymerization can be selected from known initiators (e.g., azo initiators, peroxide initiators, redox initiators, etc.). Examples of azo initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). Examples of peroxide initiators include percarbonate compounds such as di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and diethoxyethyl peroxydicarbonate; perester compounds such as t-butyl peroxyneodecanate, α-cumyl peroxyneodecanate, and t-butyl peroxydecanate; acetylcyclohexylsulfonyl peroxide; and 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate. These initiators may be combined with potassium persulfate, ammonium persulfate, hydrogen peroxide, or the like to form an initiator. Examples of redox initiators include initiators that combine the above-mentioned peroxides with reducing agents such as sodium hydrogen sulfite, sodium hydrogen carbonate, tartaric acid, L-ascorbic acid, and Rongalite. When copolymerization is performed at high temperatures, coloration due to decomposition of the vinyl ester monomer may occur. In this case, to prevent coloration, an antioxidant such as tartaric acid may be added to the polymerization system in an amount of approximately 1 to 100 ppm relative to the vinyl ester monomer.

[0061] The polymerization temperature is not particularly limited, and is preferably 0 to 180°C, more preferably 20 to 160°C, and even more preferably 30 to 150°C. When polymerization is performed at a temperature below the boiling point of the solvent used in the polymerization step, either reduced-pressure boiling polymerization, in which polymerization is performed while boiling the solvent under reduced pressure, or atmospheric non-boiling polymerization, in which polymerization is performed under conditions where the solvent is not boiled under atmospheric pressure, can be selected. Furthermore, when polymerization is performed at a temperature above the boiling point of the solvent used in the polymerization step, either pressurized non-boiling polymerization, in which polymerization is performed under conditions where the solvent is not boiled under pressure, or pressurized boiling polymerization, in which polymerization is performed while boiling the solvent under pressure, can be selected.

[0062] When the modified PVA according to one embodiment of the present disclosure contains ethylene units, i.e., is an ethylene-modified PVA, its production method preferably involves copolymerizing ethylene under pressure in the presence of a vinyl ester monomer and a silyl group-containing monomer. The ethylene pressure in the polymerization reactor is not particularly limited, but is preferably 0.01 to 2.0 MPa, more preferably 0.05 to 1.0 MPa, and in some cases even more preferably 0.1 to 0.65 MPa. The polymerization rate of the vinyl ester monomer at the outlet of the polymerization reactor is not particularly limited, but is preferably 5 to 90%, and in some cases even more preferably 15 to 85%.

[0063] [Saponification process] A preferred embodiment of the modified PVA of the present disclosure is obtained by saponifying a silyl-modified vinyl ester copolymer obtained by copolymerizing a vinyl ester monomer and a silyl-group-containing monomer in the presence of a silane coupling agent. Examples of methods for the saponification reaction include alcoholysis or hydrolysis using a basic catalyst such as sodium hydroxide, potassium hydroxide, or sodium methoxide, or an acidic catalyst such as p-toluenesulfonic acid. Examples of solvents that can be used in this reaction include alcohols such as methanol and ethanol; esters such as methyl acetate and ethyl acetate; ketones such as acetone-methyl ethyl ketone; and aromatic hydrocarbons such as benzene and toluene. These solvents can be used alone or in combination. Among these, saponification using methanol or a mixed solution of methanol and methyl acetate as the solvent and sodium hydroxide as the catalyst is preferred for its simplicity and convenience.

[0064] The silane coupling agent is a chemical species capable of introducing a group represented by the above formula (1). The silane coupling agent may be, for example, a silyl group-containing modified species (silyl group-containing monomer) having a structure represented by the above formula (4), a silane coupling agent having a structure represented by the following formula (5), or a mixture thereof.

[0065] [ka]

[0066] In formula (5), multiple R 3 is R in Equation (2). 3 It is synonymous with R. 15 is an alkoxy group having an alkyl group having 1 to 5 carbon atoms, or a hydroxyl group.

[0067] R in equation (5) 3 Specific and preferred embodiments of the formula (2) are 3 The specific and preferred embodiments are the same as those of R. 15 As the alkyl group, an alkoxy group is preferred, and an alkoxy group having an alkyl group having 1 or 2 carbon atoms is more preferred.

[0068] Examples of the silane coupling agent include trimethylsilanol, methoxytrimethylsilane, dimethyldimethoxysilane, methyltrimethoxysilane, ethoxytrimethylsilane, diethoxydimethylsilane, triethoxymethylsilane, tetraethoxysilane, propoxytrimethylsilane, dipropoxydimethylsilane, tripropoxymethylsilane, tetrapropoxysilane, isopropoxytrimethylsilane, diisopropoxydimethylsilane, triisopropoxymethylsilane, tetraisopropoxysilane, butoxytrimethylsilane, dibutoxytrimethylsilane, and methylbutoxysilane. tert-butyloxydimethylsilane, tributoxymethylsilane, tetrabutoxysilane, isobutoxytrimethylsilane, diisobutoxydimethylsilane, triisobutoxymethylsilane, tetraisobutoxysilane, tert-butyloxytrimethylsilane, ditert-butyloxydimethylsilane, tritert-butyloxymethylsilane, tetratert-butyloxysilane, phenoxytrimethylsilane, diphenoxydimethylsilane, triphenoxymethylsilane, tetraphenoxysilane, methoxytriethylsilane, dimethoxydiethylsilane, thiazolinone ... Trimethoxyethylsilane, ethoxytriethylsilane, diethoxydiethylsilane, triethoxyethylsilane, methoxytripropylsilane, dimethoxydipropylsilane, trimethoxypropylsilane, ethoxytripropylsilane, diethoxydipropylsilane, triethoxypropylsilane, trimethoxybutylsilane, trimethoxyheptylsilane, trimethoxyhexylsilane, trimethoxyoctylsilane, trimethoxydecylsilane, trimethoxydodecylsilane, trimethoxytetradecylsilane, trimethoxyoctadecylsilane , trimethoxyphenylsilane, trimethoxybenzylsilane, triethoxybutylsilane, triethoxyheptylsilane, triethoxyhexylsilane, triethoxyoctylsilane, triethoxydecylsilane, triethoxydodecylsilane, triethoxytetradecylsilane, triethoxyoctadecylsilane, phenyltriethoxysilane, triethoxybenzylsilane, mercaptomethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-bromopropyltrimethoxysilane,Examples of suitable silanes include 3-aminopropyltrimethoxysilane, mercaptomethyltriethoxysilane, 3-mercaptopropyltriethoxysilane, 3-chloropropyltriethoxysilane, 3-bromopropyltriethoxysilane, 3-aminopropyltriethoxysilane, and vinyltrimethoxysilane. Among these, methoxytrimethylsilane, dimethoxydimethylsilane, methyltrimethoxysilane, ethoxytrimethylsilane, diethoxydimethylsilane, triethoxymethylsilane, and vinyltrimethoxysilane are preferred.

[0069] <Coating fluid> As described above, the coating liquid of the present disclosure contains the modified PVA. The coating liquid of the present disclosure is preferably a coating liquid for a paper substrate or a film substrate, and may be a coating liquid used in producing release paper or a release film.

[0070] The upper limit of the insoluble content of the modified PVA in the coating solution is preferably 1000 ppm, more preferably 500 ppm, even more preferably 200 ppm, even more preferably 100 ppm, particularly preferably 70 ppm, more particularly preferably 50 ppm, and in some cases even particularly preferably 10 ppm. The lower limit of the insoluble content of the modified PVA in the coating solution is preferably 0 ppm, and may be 1 ppm. The insoluble content of the modified PVA in the coating solution in the present disclosure refers to the weight ratio of components derived from the modified PVA that remain dissolved in the coating solution, and is specifically measured by the following method.

[0071] The coating liquid is passed through a metal filter with a mesh size of 63 μm, and the filter is then washed with warm water at 90°C to obtain the solid modified PVA that remains undissolved in the coating liquid. The ratio of the weight of the undissolved solid modified PVA to the weight of the modified PVA contained in the coating liquid before filtration is calculated, and this is regarded as the insoluble portion of modified PVA in the coating liquid.

[0072] The lower limit of the concentration of the modified PVA in the coating solution is preferably 2% by mass, and sometimes more preferably 5% by mass. The upper limit of the concentration of the modified PVA in the coating solution is preferably 30% by mass, and sometimes more preferably 25% by mass. When the concentration of the modified PVA in the coating solution is within the above range, coating efficiency is further improved and high-speed coating properties are superior.

[0073] The coating solution of the present disclosure is preferably an aqueous solution containing modified PVA. In this case, the aqueous solution may contain a small amount of organic solvent or a small amount of water-insoluble organic or inorganic particles. The concentration of modified PVA in the aqueous solution is preferably 1% by mass or more and 30% by mass or less.

[0074] The method for producing the coating solution of the present disclosure is not particularly limited. For example, the coating solution can be obtained by dissolving particles of modified PVA in water.

[0075] The coating liquid may contain components other than the vinyl alcohol polymer of the present disclosure, provided that the effects of the present disclosure are not impaired. Examples of such components include aqueous dispersible resins such as SBR latex, NBR latex, vinyl acetate emulsions, ethylene / vinyl acetate copolymer emulsions, (meth)acrylic ester emulsions, and vinyl chloride emulsions; raw starches obtained from wheat, corn, rice, potato, sweet potato, tapioca, sago palm, and the like; raw starch degradation products such as oxidized starch and dextrin; starch derivatives such as etherified starch, esterified starch, and cationized starch; cellulose derivatives such as methylcellulose, hydroxyethylcellulose, and carboxymethylcellulose (CMC); monosaccharides such as glucose, fructose, isomerized sugar, and xylose; maltose and lactose. Examples of suitable coating materials include disaccharides such as sucrose, trehalose, palatinose, reduced maltose, reduced palatinose, and reduced lactose; oligosaccharides such as starch syrup, isomaltooligosaccharides, fructooligosaccharides, lactose oligosaccharides, soybean oligosaccharides, xylooligosaccharides, coupling sugars, and cyclodextrin compounds; polysaccharides such as pullulan, pectin, agar, konjac mannan, polydextrose, and xanthan gum; albumin, gelatin, casein, gum arabic, polyamide resins, melamine resins, poly(meth)acrylamide, polyvinylpyrrolidone, sodium poly(meth)acrylate, anion-modified PVA, sodium alginate, and water-soluble polyesters. The content of these components in the coating liquid is typically 10% by mass or less.

[0076] The coating liquid may contain a pigment to the extent that the effects of the present disclosure are not impaired. Examples of pigments include inorganic pigments (clay, kaolin, aluminum hydroxide, calcium carbonate, talc, etc.) and organic pigments (plastic pigments, etc.) commonly used in the field of coated paper manufacturing. The content of these pigment components in the coating liquid is preferably 50% by mass or less.

[0077] <Coated materials> A preferred embodiment of the present disclosure is a coated product obtained by coating the surface of a substrate with the coating liquid. The substrate is preferably a paper substrate or a film substrate. The method for producing the coated product is not particularly limited, and may be, for example, a production method including a step of applying the coating liquid to the substrate and a step of drying the substrate after coating.

[0078] The paper base material can be any known paper or synthetic paper obtained by papermaking from chemical pulps such as hardwood kraft pulp and softwood kraft pulp, or mechanical pulps such as groundwood (GP), refiner ground pulp (RGP), and thermomechanical pulp (TMP). The paper base material can also be wood-free paper, medium-quality paper, alkaline paper, glassine paper, semi-glassine paper, or paperboard or white paperboard used for corrugated cardboard, building materials, white cardboard, chipboard, etc. The paper base material may contain organic and inorganic pigments, as well as papermaking aids such as paper strength agents, sizing agents, and retention aids. The paper base material may also be subjected to various surface treatments.

[0079] The film substrate is preferably a film substrate made of a thermoplastic resin. Examples of the polymeric resin include polyolefin, polyester, and polyamide.

[0080] Examples of coating equipment include a two-roll size press, gate roll size press, metering size press, air knife coater, bar coater, roll coater, and blade coater. The coating speed is preferably 100 to 2,000 m / min. Furthermore, the coating speed is more preferably 300 m / min or more, and sometimes even more preferably 1,800 m / min or less. By keeping the coating speed within this range, production efficiency can be further improved and uniform coating becomes easier. The coating amount can be selected arbitrarily depending on the properties of the paper, but is preferably 0.05 to 10 g / m per side of the paper. 2 The degree is suitable.

[0081] Drying after coating can be carried out using, for example, hot air, infrared rays, a heating cylinder, or a combination of these. The dried coated product can be further improved in barrier properties by conditioning and calendering. The moisture conditioning conditions are preferably such that the moisture content in the paper is 5 to 20% by mass. Furthermore, the calendering conditions are preferably such that the roll temperature is room temperature to 200°C and the roll linear pressure is 20 to 350 kg / cm.

[0082] The lower limit of the air permeability of the coated material is preferably 400 seconds, more preferably 2,000 seconds, even more preferably 5,000 seconds, even more preferably 7,000 seconds, and sometimes particularly preferably 10,000 seconds. The upper limit of the air permeability of the coated material is not particularly limited, but may be 20,000 seconds.

[0083] The type of substrate in the coated product is not particularly limited, and examples include release paper base paper, barrier paper, greaseproof paper, wrapping paper, paperboard, polyethylene-based release film, polypropylene-based release film, and polyester-based release film. Among these, a preferred embodiment of the present disclosure is a release paper base paper obtained by coating the surface of a paper substrate with the above-mentioned coating liquid. A release layer (peeling layer) may be formed on the surface of the release paper base paper. When forming the release layer, solvent-based silicones or non-solvent-based (emulsion-based, oligomer-based) silicones are preferably used. In this case, since solvent-based silicones contain solvents (such as toluene), the release paper base paper of the present disclosure preferably has barrier properties against solvents. Furthermore, since water resistance may be required when non-solvent-based silicones are used, the release paper base paper of the present disclosure preferably has water resistance. In the present disclosure, a release paper having the release paper base paper and a release layer formed on the surface of the release paper base paper is also a preferred embodiment. <Molded body>

[0084] One embodiment of the present disclosure is a molded article having a layer containing the modified PVA.

[0085] The molded body is not particularly limited, and may be, for example, a shaped object having a three-dimensional shape or a sheet-like object. The material constituting the molded body is not particularly limited, and examples thereof include metal, ceramics, glass, resin, concrete, etc. Examples of metals include iron, steel, aluminum, stainless steel, gold, silver, copper, etc. The molded body may also be the above-mentioned substrate, and preferred substrates are paper substrates and film substrates.

[0086] The layer containing the modified PVA in the molded article may be a coating film formed by applying the above-mentioned coating liquid to the molded article.

[0087] <Release paper> One embodiment of the present disclosure is a release paper, which includes a substrate, a silicone filling layer, and a release layer, and the silicone filling layer contains the above-mentioned modified PVA. The release paper preferably includes the substrate, the silicone filling layer, and the release layer laminated in this order.

[0088] The release layer preferably contains addition silicone and platinum, and the amount of platinum is preferably 0.001 to 0.05 parts by weight per 100 parts by weight of addition silicone. This can further improve the curing properties of the addition silicone in the release layer. Furthermore, since the curing rate of the addition silicone can be accelerated, the time required for the silicone curing process can be shortened, or the amount of platinum used can be reduced, which is expected to reduce production costs.

[0089] The substrate of the release paper may be, for example, the substrates described above, and a paper substrate or a film substrate is preferably used. In the present disclosure, a release paper comprising a substrate, a silicone sealing layer, and a release layer may be referred to as a "release paper" even if, for example, the substrate consists only of a film substrate.

[0090] The present disclosure includes embodiments in which the above configurations are combined in various ways within the scope of the technical idea of ​​the present disclosure, as long as the effects of the present invention are achieved. [Example]

[0091] The present disclosure will be described in more detail below using examples. In the following, "parts" and "%" refer to mass standards unless otherwise specified.

[0092] [Viscosity average degree of polymerization] The viscosity average degree of polymerization of the raw material PVA or modified PVA was measured in accordance with JIS K 6726:1994.

[0093] [Saponification degree] The degree of saponification (mol %) of PVA (raw PVA or modified PVA) was determined by the method described in JIS K 6726:1994.

[0094] [Amount of silyl group modification in modified PVA] The amount of silyl group modification (mol%) of the modified PVA is 1 The carbon content was determined using H-NMR.

[0095] [Siloxane structure content of modified PVA] The content (mol%) of the siloxane structure in the modified PVA is: 1 The carbon content was determined using H-NMR.

[0096] [Insoluble matter] The insoluble content of modified PVA was measured as follows. A 500 mL flask equipped with a stirrer and reflux condenser was placed in a water bath set at 20°C. 285 g of distilled water was added to the flask, and stirring at 300 rpm was initiated. 15 g of modified PVA particles was weighed and gradually added to the flask. After the entire amount (15 g) of modified PVA particles was added, the temperature of the water bath was increased to 90°C over 30 minutes to dissolve the modified PVA particles, yielding a modified PVA solution. After the water bath temperature reached 90°C, dissolution was continued for an additional 60 minutes while stirring at 300 rpm. The modified PVA solution was then used to filter the remaining undissolved modified PVA particles (undissolved particles) through a metal filter with 63 μm mesh. The filter was then thoroughly washed with warm water at 90°C to remove the modified PVA solution adhering to the filter, leaving only the undissolved particles on the filter. The filter was then dried in a heated dryer at 120°C for 1 hour. The weight of the filter after drying was compared with the weight of the filter before filtration to calculate the weight of undissolved particles. The ratio of the weight of undissolved particles to the weight of modified PVA (15 g) initially added to the water was taken as the insoluble content (%). <Production Example 1> [Production of modified PVA1] A 3 L reactor equipped with a stirrer, reflux condenser, nitrogen inlet, comonomer inlet, and initiator inlet was charged with 850 g of vinyl acetate, 150 g of methanol, and 1.6 g of vinyltrimethoxysilane (a silyl group-containing modified species). The system was then purged with nitrogen for 30 minutes while bubbling with nitrogen. A 10% comonomer solution was prepared as a delay solution by dissolving vinyltrimethoxysilane in methanol, and the atmosphere was purged with nitrogen by bubbling with nitrogen gas. The reactor was heated, and when the internal temperature reached 60°C, 0.2 g of 2,2'-azobisisobutyronitrile (AIBN) was added to initiate polymerization. The delay solution was added dropwise to maintain a constant monomer composition (ratio of vinyl acetate to vinyltrimethoxysilane) in the polymerization solution. After 3 hours of polymerization at 60°C, 0.4 g of hydroquinone was added and the polymerization was terminated by cooling. The total amount of comonomer (silyl group-containing modified species) added until the polymerization was terminated was 2.6 g. The solids concentration at the time of polymerization termination was 24.8%, and the polymerization rate was 30%. Subsequently, unreacted vinyl acetate monomer was removed at 50 °C under reduced pressure with occasional addition of methanol to obtain a methanol solution of silyl-modified vinyl ester polymer (concentration 35%). Further, 571.4 g of a methanol solution of silyl-modified vinyl ester polymer (200.0 g of silyl-modified vinyl ester polymer in the solution) was prepared by adding methanol to the above mixture. 3.17 g of methyltrimethoxysilane was added as a silane coupling agent and mixed well. 27.9 g of an alkaline solution (10% methanol solution of sodium hydroxide) was added to the mixture to perform saponification (saponification solution silyl-modified vinyl ester polymer concentration 25%, molar ratio of silane coupling agent to vinyl acetate units 1.0 mol%, molar ratio of sodium hydroxide 3.0 mol%). A gel-like substance formed approximately one minute after the addition of the alkaline solution. This was crushed in a grinder and left at 40°C for one hour to allow saponification to proceed. 500 g of methyl acetate was then added to neutralize the remaining alkali. After confirming completion of neutralization using a phenolphthalein indicator, the solution was filtered to obtain a white solid. 2,000 g of methanol was added to this and the solid was left to wash at room temperature for three hours. This washing procedure was repeated three times, and the resulting white solid was centrifuged and left to dry at 65°C for two days to obtain modified PVA1.The viscosity average degree of polymerization of the modified PVA1 was 2,500, the degree of saponification was 98.5 mol %, the amount of silyl group modification was 0.30 mol %, and the content of siloxane structure was 0.20 mol %.

[0097] <Production Examples 2 to 7> [Production of modified PVA 2 to 7] Modified PVAs 2 to 7 were produced in the same manner as in Production Example 1, except that the polymerization conditions and saponification conditions were changed as shown in Table 1.

[0098] [Table 1]

[0099] [Examples 1 to 6, Comparative Example 1] Modified PVAs 1 to 7 obtained in Production Examples 1 to 7 were used to prepare base papers for release paper by the following method, and evaluated.

[0100] [Preparation of release paper base paper] A 6% by mass aqueous solution of modified PVA was prepared as a coating solution. This coating solution was applied to glassine paper with an air permeability of 100 seconds using a wire bar to a coating weight of approximately 2.0 g / m2 (dry mass). 2 After coating, the coated paper was dried at 100°C for 5 minutes to obtain coated paper. The obtained coated paper was then calendered at 70°C and 400 kg / cm 2 A release paper base paper was obtained by treating the base paper twice with the above-mentioned coating liquid. This release paper base paper had a coating layer derived from the above-mentioned coating liquid, i.e., a silicone sealing layer, formed on it.

[0101] [Air permeability evaluation of release paper base paper] The air permeability (seconds) of the release paper base paper was measured using an Oken air permeability tester in accordance with JIS P 8117 (2009), and this air permeability was used as an index of the sealing ability of the silicone in the release paper base paper. The higher the air permeability, the better the sealing ability of the silicone tends to be. The results are shown in Table 2.

[0102] [Evaluation of silicone curing properties] Using LTC1056L manufactured by Dow Corning Toray Co., Ltd. as the addition type silicone and SRX212 as the platinum catalyst, a solution was mixed so that the ratio of addition type silicone to platinum was 100 / 0.007, and the solution was applied to the silicone sealing layer of the obtained release paper base paper at a coating solid content of 2.0 g / m 2 The silicone layer was coated using a blade coater so that the silicone layer was cured. This resulted in the formation of a silicone layer on the release paper base. The silicone layer was then heat-treated at 110°C and the time until the silicone cured was measured. Here, the time until the silicone cured refers to the time (seconds) required for the silicone layer to no longer peel off when the silicone layer was rubbed vigorously with a finger 10 times at specified time intervals. The results are shown in Table 2.

[0103] [Evaluation of adhesion of release layer] Using LTC1056L manufactured by Dow Corning Toray Co., Ltd. as the addition type silicone and SRX212 as the platinum catalyst, a solution was mixed so that the ratio of addition type silicone to platinum was 100 / 0.009, and the solution was applied to the silicone filling layer on the obtained release paper base paper at a coating solid content of 2.0 g / m 2 The resulting base paper was coated with a blade coater so that the silicone layer was coated, and then heat-treated at 110°C for 90 seconds to obtain a release paper with a release layer (silicone layer) formed on the base paper. The resulting release paper was evaluated according to the following criteria. The results are shown in Table 2. A + After leaving the sample for one week under conditions of 40°C and 90% RH, the release layer was rubbed hard with a finger. As a result, the release layer did not peel off. After leaving the sample for another week under the same conditions, the release layer was rubbed hard with a finger. As a result, the release layer did not peel off. A: After leaving the sample for one week under the conditions of 40°C and 90% RH, the release layer was rubbed strongly with a finger. As a result, the release layer did not peel off. However, after leaving the sample for another week under the same conditions, the release layer peeled off when rubbed strongly with a finger. B: After leaving the sample for one week under conditions of 40°C and 90% RH, the release layer was rubbed strongly with a finger, resulting in the release layer peeling off. C: After leaving the sample for one week under conditions of 40°C and 90% RH, the release layer was lightly rubbed with a finger, resulting in the release layer peeling off.

[0104] [Table 2]

[0105] The coating liquids of the Examples were excellent in silicone curability and adhesion, whereas Comparative Example 1 contained a large amount of insoluble modified PVA and could not prepare a coating liquid. [Industrial Applicability]

[0106] The coating liquid using the modified PVA of the present disclosure is useful for, for example, release paper base paper and release paper.

Claims

1. A coating liquid containing a modified vinyl alcohol polymer having a group represented by the following formula (1): 【Chemical 1】 In the above formula (1), R 1 is an alkyl group having 1 to 8 carbon atoms, an alkoxy group having an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OM. M is an alkali metal or an alkaline earth metal. R 2 is a group represented by the following formula (2), and n is an integer of 1 to 3. 1 If there are multiple R 1 may be the same or different. 2 If there are multiple R 2 may be the same or different. 【Chemistry 2】 In the above formula (2), the multiple R3s are each independently an alkyl group having 1 to 20 carbon atoms, an alkoxy group having an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a phenyl group, a benzyl group, a halogenated alkyl group having 1 to 8 carbon atoms, a halogenated phenyl group, an aminoalkyl group having 1 to 8 carbon atoms, a mercaptoalkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OQ, where Q is an alkali metal or an alkaline earth metal.

2. 2. The coating fluid according to claim 1, wherein the content of the group represented by formula (2) relative to all monomer units of the modified vinyl alcohol polymer is 0.001 mol % or more.

3. 3. The coating fluid according to claim 1, wherein the content of the group represented by formula (2) relative to all monomer units derived from the silyl group-containing monomer in the modified vinyl alcohol polymer is 50 mol % or more.

4. The coating fluid according to any one of claims 1 to 3, wherein the modified vinyl alcohol polymer has a viscosity average degree of polymerization of 500 or more and 5,000 or less and a degree of saponification of 70 mol% or more and 99.9 mol% or less.

5. 5. The coating fluid according to claim 1, wherein the insoluble content of the modified vinyl alcohol polymer in the coating fluid is 1000 ppm or less.

6. A coated product obtained by applying the coating liquid according to any one of claims 1 to 5 to a substrate.

7. A molded article comprising a layer containing a modified vinyl alcohol polymer having a group represented by the following formula (1): 【Chemistry 3】 In the above formula (1), R 1 is an alkyl group having 1 to 8 carbon atoms, an alkoxy group having an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OM. M is an alkali metal or an alkaline earth metal. R 2 is a group represented by the following formula (2), and n is an integer of 1 to 3. 1 If there are multiple R 1 may be the same or different. 2 If there are multiple R 2 may be the same or different. 【Chemistry 4】 In the above formula (2), the multiple R3s are each independently an alkyl group having 1 to 20 carbon atoms, an alkoxy group having an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a phenyl group, a benzyl group, a halogenated alkyl group having 1 to 8 carbon atoms, a halogenated phenyl group, an aminoalkyl group having 1 to 8 carbon atoms, a mercaptoalkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OQ, where Q is an alkali metal or an alkaline earth metal.

8. A release paper comprising a substrate, a silicone filling layer, and a release layer, wherein the silicone filling layer contains a modified vinyl alcohol polymer having a group represented by the following formula (1): 【Chemistry 5】 In the above formula (1), R 1 is an alkyl group having 1 to 8 carbon atoms, an alkoxy group having an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OM. M is an alkali metal or an alkaline earth metal. R 2 is a group represented by the following formula (2), and n is an integer of 1 to 3. 1 If there are multiple R 1 may be the same or different. 2 If there are multiple R 2 may be the same or different. 【Chemistry 6】 In the above formula (2), the multiple R3s are each independently an alkyl group having 1 to 20 carbon atoms, an alkoxy group having an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a phenyl group, a benzyl group, a halogenated alkyl group having 1 to 8 carbon atoms, a halogenated phenyl group, an aminoalkyl group having 1 to 8 carbon atoms, a mercaptoalkyl group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -OQ, where Q is an alkali metal or an alkaline earth metal.

9. 9. The release paper according to claim 8, wherein the release layer contains addition type silicone and platinum, and the amount of platinum blended is 0.001 to 0.05 parts by weight per 100 parts by weight of the addition type silicone.

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