Polyvinyl alcohol resin, resin composition, ceramic green sheet, and ceramic capacitor

Abstract

Provided is a polyvinyl alcohol resin with which it is possible to produce a ceramic green sheet using an aqueous solvent, with which sedimentation of an inorganic powder can be suppressed, with which a ceramic green sheet having excellent flexibility and strength can be produced, and with which a highly reliable ceramic capacitor can be produced. The present invention relates to a polyvinyl alcohol resin having an adsorption amount of 0.05-5 mg / g with respect to barium titanate.

Description

Technical Field

[0001] The present invention relates to a polyvinyl alcohol resin. Background Art

[0002] The polyvinyl alcohol resin is obtained by saponifying a polymer obtained by polymerizing a vinyl ester monomer. Conventionally, polyvinyl alcohol resins have been used in various applications such as polymerization suspending agents for vinyl chloride resins, green sheets for ceramics, dielectric sheets for thin film capacitors, polarizing films, water-soluble films, adhesives, and the like.

[0003] For example, a multilayer ceramic capacitor generally has a structure including a laminate in which dielectric layers and internal electrodes are alternately laminated, and a pair of external electrodes provided so as to sandwich the laminate. A green sheet for manufacturing a multilayer ceramic capacitor is usually manufactured through the following steps. First, a binder resin such as a poly(meth)acrylate resin is dissolved in an organic solvent to obtain a solution. After adding a plasticizer, a dispersant, etc. to this solution, an inorganic powder is added, and the mixture is uniformly mixed using a mixing device such as a bead mill or a ball mill, and after defoaming, a ceramic slurry composition having a certain viscosity is obtained. This slurry composition is cast onto a support surface such as a demolded polyethylene terephthalate film or a SUS plate using a doctor blade, a reverse roll coater, etc., and volatile components such as solvents are removed by heating etc., and the green sheet is obtained by peeling from the support. In the above method, an organic solvent is used from the viewpoint of surface tension, but from the viewpoint of environmental friendliness awareness in recent years, there is a problem that it is difficult to use, and a method using an aqueous solvent is required.

[0004] For example, in Patent Document 1, regarding a sintering slurry composition for producing a green sheet, a composition containing an inorganic powder, a polyvinyl alcohol resin, an acrylic polymer, and water is disclosed.

[0005] In addition, as the polyvinyl alcohol resin, for example, an amide-modified polyvinyl alcohol resin is disclosed in Patent Document 2, and a modified polyvinyl alcohol resin containing acrylamide monomer units is disclosed in Patent Document 3.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent No. 7185948 Gazette

[0009] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2019-065059

[0010] Patent Document 3: International Publication No. 2015 / 098978 Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] However, although conventional polyvinyl alcohol resins can be made into films using aqueous solvents, when fine inorganic powders are used, in the slurry composition prepared using an aqueous solvent, there are problems such as the inorganic powders being prone to sedimentation over time and the stability of the slurry composition over time being low. Therefore, there is a problem that when a ceramic green sheet is produced using a slurry composition that has been stored for a long time, the performance of the resulting ceramic green sheet is reduced. Accordingly, there is a need for a polyvinyl alcohol resin that can be used to produce a ceramic green sheet using an aqueous solvent, can suppress the sedimentation of inorganic powders over time, and can produce a ceramic green sheet with excellent flexibility and strength.

[0013] An object of the present invention is to provide a polyvinyl alcohol resin that can be used to produce a ceramic green sheet using an aqueous solvent, can suppress the sedimentation of inorganic powders, can produce a ceramic green sheet with excellent flexibility and strength, and can manufacture a highly reliable ceramic capacitor.

[0014] Means for Solving the Problem

[0015] The present disclosure (1) relates to a polyvinyl alcohol resin having an adsorption amount of 0.05 to 5 mg / g of the polyvinyl alcohol resin with respect to barium titanate.

[0016] The present disclosure (2) relates to the polyvinyl alcohol resin of the present disclosure (1), which has a solubility parameter of 12 or more.

[0017] The present disclosure (3) relates to the polyvinyl alcohol resin of the present disclosure (1) or (2), which has at least one functional group selected from a carboxyl group, a sulfonic acid group, a pyrrolidone ring group, an amide group, and an amino group in a side chain.

[0018] The present disclosure (4) relates to a resin composition containing a polyvinyl alcohol resin, an inorganic powder, and a plasticizer, and having an adsorption amount of 0.05 to 5 mg / g of the polyvinyl alcohol resin with respect to the inorganic powder.

[0019] The present disclosure (5) relates to the resin composition of the present disclosure (4), wherein when the average particle diameter of the inorganic powder immediately after dispersion treatment is set to A and the average particle diameter of the inorganic powder 24 hours after the dispersion treatment is set to B, A and B satisfy the following relationship.

[0020] 0.7 ≤ B / A ≤ 1.0

[0021] The present disclosure (6) relates to a ceramic green sheet made using the polyvinyl alcohol resin according to any one of the present disclosures (1) to (3), or the resin composition of the present disclosure (4) or (5).

[0022] The present disclosure (7) relates to a ceramic capacitor made using the ceramic green sheet of the present disclosure (6).

[0023] Hereinafter, the present invention will be described in detail.

[0024] The inventors of the present invention conducted in-depth research and found that by preparing a polyvinyl alcohol resin having a specified adsorption amount with respect to barium titanate, a ceramic green sheet can be produced using an aqueous solvent, sedimentation of inorganic powder can be suppressed, and a ceramic green sheet having excellent flexibility and strength can be produced. In addition, it was found that by using such a ceramic green sheet, a ceramic capacitor having high reliability can be manufactured, and thus the present invention was completed.

[0025] The adsorption amount of the above polyvinyl alcohol resin with respect to barium titanate is 0.05 to 5 mg / g.

[0026] By using the polyvinyl alcohol resin, a ceramic green sheet can be produced using an aqueous solvent, and by preparing a polyvinyl alcohol resin having a specified adsorption amount with respect to barium titanate, a ceramic green sheet having excellent flexibility and strength can be produced. In addition, due to the above characteristics, the polyvinyl alcohol resin as a dispersant is not easily detached from around the inorganic powder over time, and even when a slurry composition stored for a long time is used for production, deterioration of the flexibility and strength of the obtained ceramic green sheet can be suppressed.

[0027] The above adsorption amount with respect to barium titanate is preferably 0.1 mg / g or more, preferably 2.5 mg / g or less, more preferably 0.2 mg / g or more, and more preferably 1 mg / g or less.

[0028] The above adsorption amount with respect to barium titanate can be measured by the following method. First, weigh 1.5 g of barium titanate and 6 g of a 5 wt% aqueous solution of polyvinyl alcohol resin in a sedimentation tube, and stir for 10 minutes using an ultrasonic disperser. Then, separate the barium titanate and the aqueous solution of polyvinyl alcohol resin using a centrifuge. Collect 4 g of the supernatant of the aqueous solution of polyvinyl alcohol resin on an aluminum cup whose weight has been previously measured, and dry it to completely remove moisture. Then, measure the weight of the aluminum cup, regard the weight increase as the resin amount, assume that the reduced part of the resin is adsorbed on barium titanate, and calculate the adsorption amount. It should be noted that as the barium titanate, spherical barium titanate with an average particle size of 0.4 μm can be used.

[0029] The above adsorption amount with respect to barium titanate can be adjusted by the ratio of each structural unit of the polyvinyl alcohol resin, structures such as block property, conditions during the preparation of the polyvinyl alcohol resin, etc. More specifically, in particular, it can be adjusted by using a series of continuous tank reactors in the production process of polyvinyl ester and changing the temperature, average residence time, stirring state in each reaction tank, etc.

[0030] The solubility parameter of the above polyvinyl alcohol resin is preferably 12 or more.

[0031] If the solubility parameter is 12 or more, the interaction with the inorganic powder can be further enhanced.

[0032] The above solubility parameter is more preferably 12.3 or more, further preferably 12.6 or more, preferably 15 or less, more preferably 14 or less, and further preferably 13.5 or less.

[0033] The above solubility parameter is a value measured by the Fedors method.

[0034] The above solubility parameter can be adjusted by the type and amount of the modifying group.

[0035] The amount of residual acetyl groups in the above polyvinyl alcohol resin is preferably 0.01 mol% or more, more preferably 0.1 mol% or more, further preferably 0.5 mol% or more, still more preferably 1.0 mol% or more, preferably 30.0 mol% or less, more preferably 20.0 mol% or less, further preferably 10.0 mol% or less, and still more preferably 5.0 mol% or less. That is, the amount of residual acetyl groups is preferably 0.01 to 30.0 mol%, more preferably 0.1 to 20.0 mol%, further preferably 0.5 to 10.0 mol%, and still more preferably 1.0 to 5.0 mol%.

[0036] The amount of residual acetyl groups refers to the proportion of the structural unit having an acetyl group shown in the following formula (1) in all the structural units constituting the above polyvinyl alcohol resin.

[0037] The amount of residual acetyl groups can be measured, for example, by 1 1H-NMR. As the measuring device, for example, AVANCE400 (manufactured by Bruker Biospin) can be used.

[0038] [Chemical formula 1]

[0039]

[0040] The amount of hydroxyl groups in the above polyvinyl alcohol resin is preferably 70.0 mol% or more, more preferably 85.0 mol% or more, further preferably 90.0 mol% or more, preferably 99.5 mol% or less, more preferably 99.0 mol% or less, and further preferably 98.5 mol% or less. That is, the amount of hydroxyl groups is preferably 70.0 to 99.5 mol%, more preferably 85.0 to 99.0 mol%, and further preferably 90.0 to 98.5 mol%.

[0041] The amount of hydroxyl groups refers to the proportion of the structural unit having a hydroxyl group shown in the following formula (2) in all the structural units constituting the above polyvinyl alcohol resin.

[0042] The amount of the above-mentioned hydroxyl groups can be measured by the same method as the amount of the above-mentioned residual acetyl groups.

[0043] [Chemical formula 2]

[0044]

[0045] The saponification degree of the above-mentioned polyvinyl alcohol resin is preferably 80.0 mol% or more, more preferably 85.0 mol% or more, still more preferably 87.0 mol% or more, and particularly preferably 90.0 mol% or more. In addition, the saponification degree is preferably 99.9 mol% or less, more preferably 99.0 mol% or less, still more preferably 98.0 mol% or less, and particularly preferably 97.0 mol% or less. That is, the saponification degree is preferably 80.0 to 99.9 mol%, more preferably 85.0 to 99.0 mol%, still more preferably 87.0 to 98.0 mol%, and particularly preferably 90.0 to 97.0 mol%.

[0046] The saponification degree refers to the proportion of the amount of the above-mentioned hydroxyl groups in the above-mentioned polyvinyl alcohol resin in the total of the amount of the above-mentioned residual acetyl groups and the amount of the above-mentioned hydroxyl groups.

[0047] The saponification degree can be measured by the method according to JIS K6726-1994.

[0048] The above-mentioned polyvinyl alcohol resin preferably has at least one functional group selected from a carboxyl group, a sulfonic acid group, a pyrrolidone ring group, an amide group, and an amino group in the side chain. It should be noted that the above-mentioned carboxyl group and sulfonic acid group may be derivatives such as their salts.

[0049] By having the above structure, the effect of suppressing the sedimentation of inorganic powder can be further improved, and even when a slurry composition stored for a long time is used, a ceramic green sheet excellent in flexibility and strength can be produced.

[0050] As the structural unit having the above functional group, for example, there can be mentioned: a structural unit having a carboxyl group represented by the following formula (3-1) to (3-4), a structural unit having a sulfonic acid group represented by the following formula (4), a structural unit having a pyrrolidone ring group represented by the following formula (5), a structural unit having an amide group represented by the following formula (6), and a structural unit having an amino group represented by the following formula (7).

[0051] Among them, especially from the aspect of being able to further improve the suppression effect of deterioration over time, a structural unit having a carboxyl group represented by the following formula (3-1), a structural unit of a salt having a sulfonic acid group represented by the following formula (4), a structural unit having a pyrrolidone ring group represented by the following formula (5), and a structural unit having an amino group represented by the following formula (7) are preferred, a structural unit having a sulfonic acid group represented by the following formula (4) is more preferred, and a structural unit of a salt having a sulfonic acid group represented by the following formula (4-1) is further preferred.

[0052] [Chemical formula 3]

[0053]

[0054] In formula (3-1), R 1 and R 2 each independently represents an alkylene group having 0 to 10 carbon atoms, and X 1 and X 2 each independently represents a hydrogen atom, a metal atom, or an alkyl group having 1 to 3 carbon atoms.

[0055] In the above formula (3-1), the number of carbon atoms of the alkylene group represented by R 1 and R 2 is preferably 0 or more, preferably 5 or less, and more preferably 3 or less.

[0056] Examples of the alkylene group having 0 to 10 carbon atoms include linear alkylene groups such as a single bond, methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, octamethylene, and decamethylene; branched alkylene groups such as methylmethylene, methylethylene, 1-methylpentylene, and 1,4-dimethylbutylene; and cyclic alkylene groups such as cyclopropylidene, cyclobutylidene, and cyclohexylidene. Among them, linear alkylene groups such as a single bond, methylene, ethylene, n-propylene, and n-butylene are preferred, and a single bond, methylene, and ethylene are more preferred.

[0057] The above R 1 and R 2 may be the same or different, and are preferably different. In addition, it is preferred that at least one of them is a single bond, and more preferably one is a single bond and the other is methylene.

[0058] In the above formula (3-1), when at least one of X 1 and X 2 is a metal atom, examples of the above metal atom include a sodium atom, a lithium atom, a potassium atom, etc., and among them, a sodium atom is preferred.

[0059] In the above formula (3-1), as X 1 and X 2The alkyl group having 1 to 3 carbon atoms represented can be, for example, methyl, ethyl, propyl, etc. Among them, methyl is preferred.

[0060] The above-mentioned X 1 and X 2 can be the same or different, and are preferably the same. In addition, they are preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0061] In the above formula (3-2), R 3 represents an alkylene group having 0 to 12 carbon atoms, X 3 represents a hydrogen atom, a metal atom or an alkyl group having 1 to 3 carbon atoms, R 4 , R 5 and R 6 each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

[0062] In the above formula (3-2), as the alkylene group represented by R 3 , the same alkylene groups as those exemplified for R 1 and R 2 in the above formula (3-1) can be cited. Among them, linear alkylene groups such as a single bond, methylene, ethylene, trimethylene, and tetramethylene are preferred, and a single bond, methylene, and ethylene are more preferred, and a single bond is further preferred.

[0063] In the above formula (3-2), when X 3 is a metal atom, as the above-mentioned metal atom, the same metal atoms as those exemplified for X 1 and X 2 in the above formula (3-1) can be cited. Among them, a sodium atom is preferred.

[0064] In the above formula (3-2), when X 3 is an alkyl group having 1 to 3 carbon atoms, as the above-mentioned alkyl group, the same alkyl groups as those exemplified for X 1 and X 2 in the above formula (3-1) can be cited. Among them, methyl is preferred.

[0065] In the above formula (3-2), R 4 , R 5 and R 6 can be the same or different, and are more preferably the same. In addition, R 4 , R 5 and R 6 are preferably hydrogen atoms.

[0066] Examples of the alkyl group having 1 to 10 carbon atoms as described above include: linear alkyl groups such as methyl, ethyl, propyl, n-butyl, n-pentyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; branched alkyl groups such as isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2,2-dimethylpropyl, 1,1,3,3-tetramethylbutyl, and 2-ethylhexyl; and cycloalkyl groups such as cyclopropyl, cyclopropylmethyl, cyclobutyl, cyclopentyl, and cyclohexyl. Among them, linear alkyl groups such as methyl, ethyl, propyl, and n-butyl are preferred, and methyl and ethyl are more preferred.

[0067] In the above formula (3-3), R 7 and R 8 each independently represent an alkylene group having 0 to 10 carbon atoms, X 4 and X 5 each independently represent a hydrogen atom, a metal atom, or an alkyl group having 1 to 3 carbon atoms, and R 9 and R 10 each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.

[0068] In the above formula (3-3), examples of the alkylene group represented by R 7 and R 8 include the same alkylene groups as those exemplified for R 1 and R 2 in the above formula (3-1). Among them, linear alkylene groups such as a single bond, methylene, ethylene, trimethylene, and tetramethylene are preferred, a single bond, methylene, and ethylene are more preferred, and a single bond is further preferred.

[0069] In the above formula (3-3), when at least one of X 4 and X 5 is a metal atom, examples of the metal atom include the same metal atoms as those exemplified for X 1 and X 2 in the above formula (3-1). Among them, a sodium atom is preferred.

[0070] In the above formula (3-3), when at least one of X 4 and X 5 is an alkyl group having 1 to 3 carbon atoms, examples of the alkyl group include the same alkyl groups as those exemplified for X 1 and X 2 in the above formula (3-1). Among them, methyl is preferred.

[0071] In the above formula (3-3), examples of the alkyl group represented by R 9 and R 10 include the same alkyl groups as those exemplified for R 4 and R 5An alkyl group identical to the exemplified example.

[0072] In the above formula (3-4), R 11 represents an alkylene group having 1 to 12 carbon atoms, and X 6 , X 7 represents a hydrogen atom, a metal atom, or an alkyl group having 1 to 3 carbon atoms, and R 12 , R 13 and R 14 each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

[0073] In the above formula (3-4), as the alkylene group represented by R 11 , an alkylene group identical to the examples of R 1 and R 2 in the above formula (3-1) can be cited. Among them, linear alkylene groups such as a single bond, methylene, ethylene, trimethylene, and tetramethylene are preferred, and a single bond, methylene, and ethylene are more preferred, and a single bond is further preferred.

[0074] In the above formula (3-4), when X 6 , X 7 is a metal atom, as the above metal atom, a metal atom identical to the examples of X 1 and X 2 in the above formula (3-1) can be cited. Among them, a sodium atom is preferred.

[0075] In the above formula (3-4), when X 6 , X 7 is an alkyl group having 1 to 3 carbon atoms, as the above alkyl group, an alkyl group identical to the examples of X 1 and X 2 in the above formula (3-1) can be cited. Among them, a methyl group is preferred.

[0076] In the above formula (3-4), as the alkyl groups represented by R 12 , R 13 and R 14 , alkyl groups identical to the examples of R 4 , R 5 and R 6 in the above formula (3-2) can be cited.

[0077] [Chemical formula 4]

[0078]

[0079] In the above formula (4), R 15 and R 16Each independently represents an alkylene group having 0 to 4 carbon atoms, an amide group (-CONH-), an ester group (-COO-), or an ether group (-O-), X 8 represents a hydrogen atom, a metal atom, or an alkyl group having 1 to 3 carbon atoms.

[0080] Examples of the alkylene group having 0 to 4 carbon atoms include linear alkylene groups such as a single bond, methylene, ethylene, trimethylene, and tetramethylene; propylene groups (1-methylethylene, 2-methylethylene); butylene groups (1-ethylideneethylene, 2-ethylideneethylene); 1,2-dimethylethylene; 2,2-dimethylethylene; 1-methyltrimethylene; 2-methyltrimethylene; 3-methyltrimethylene; and other branched alkylene groups. Among them, 2,2-dimethylethylene is preferred.

[0081] In the above formula (4), as X 8 , examples include those the same as the examples exemplified for X 1 and X 2 in the above formula (3-1), and among them, a sodium atom is preferred.

[0082] As the structural unit having a sulfonic acid group, a structural unit of a salt having a sulfonic acid group represented by the following formula (4-1) is preferred.

[0083] [Chemical formula 5]

[0084]

[0085] In the above formula (4-1), R 17 represents an alkylene group having 1 to 4 carbon atoms.

[0086] Examples of the alkylene group having 1 to 4 carbon atoms include the same alkylene groups as those exemplified for R 15 and R 16 in the above formula (4), and among them, 2,2-dimethylethylene is preferred.

[0087] [Chemical formula 6]

[0088]

[0089] [Chemical formula 7]

[0090]

[0091] In the above formula (6), R 18 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

[0092] In the above formula (6), examples of the alkyl group represented by R 18 include those the same as R 4 in the above formula (3-2), R5 and R 6 an alkyl group the same as the exemplified example

[0093] [Chemical formula 8]

[0094]

[0095] In the above formula (7), R 19 represents an alkylene group having 0 to 10 carbon atoms

[0096] In the above formula (7), as the alkylene group represented by R 19 an alkylene group the same as the examples exemplified by R 1 and R 2 in the above formula (3-1) can be cited. Among them, a single bond is preferred

[0097] The content of the structural unit having the above functional group in the above polyvinyl alcohol resin (hereinafter, also referred to as the amount of the modified group) is preferably 0.01 mol% or more, more preferably 0.05 mol% or more, further preferably 1.0 mol% or more, still more preferably 2.0 mol% or more, preferably 11.0 mol% or less, more preferably 10.0 mol% or less, further preferably 8.0 mol% or less, still more preferably 5.0 mol% or less. That is, the above amount of the modified group is preferably 0.01 to 11.0 mol%, more preferably 0.05 to 10.0 mol%, further preferably 1.0 to 8.0 mol%, still more preferably 2.0 to 5.0 mol%

[0098] The amount of the modified group can be measured by the same method as the amount of the residual acetyl group

[0099] The viscosity-average degree of polymerization of the above polyvinyl alcohol resin is preferably 300 or more, more preferably 500 or more, further preferably 600 or more, still more preferably 700 or more, for example 800 or more, preferably 3500 or less, more preferably 3000 or less, further preferably 2500 or less, still more preferably 2000 or less, for example 1800 or less. That is, the above viscosity-average degree of polymerization is preferably 300 to 3500, more preferably 500 to 3000, further preferably 600 to 2500, still more preferably 700 to 2000, particularly preferably 800 to 1800

[0100] The viscosity-average degree of polymerization can be determined by measuring the viscosity of a 4% by weight aqueous solution by the method based on JIS K6726-1994

[0101] As a method for producing the above-mentioned polyvinyl alcohol resin, for example, there can be mentioned: a method in which a vinyl ester and other unsaturated monomers are copolymerized to obtain a vinyl ester copolymer, and then a saponification catalyst is added to saponify, that is, hydrolyze, the vinyl ester copolymer.

[0102] In particular, as a polymerization method for obtaining the vinyl ester copolymer, a series of continuous tank reactors are used, and adjustments are made through the temperature, average residence time, stirring state in each tank, etc., whereby a polyvinyl alcohol resin having the above-mentioned specified characteristics can be produced. In addition, in particular, in each reaction tank, by setting the ratio of the vortex volume generated at the gas-liquid interface during stirring to the weight of the reaction liquid in each reaction tank within a specified range, the ratio of the distance from the liquid surface to the stirring blade in each reaction tank to the liquid surface height within a specified range, the ratio of the stirring blade diameter to the reaction vessel diameter within a specified range, etc., a polyvinyl alcohol resin having the above-mentioned specified characteristics can be produced.

[0103] The above-mentioned vinyl ester is not particularly limited, and examples thereof include vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, etc. Among them, vinyl acetate is preferred.

[0104] As the above-mentioned other unsaturated monomers, there can be mentioned: monomers having a carbon-carbon double bond such as a vinyl group, which are monomers other than vinyl esters. For example, there can be mentioned: unsaturated acids such as monocarboxylic acids having a radically polymerizable unsaturated double bond, dicarboxylic acids having a radically polymerizable unsaturated double bond, etc., salts or esters thereof and other derivatives, olefins, (meth)acrylamides, N-vinylamides, vinyl ethers, nitriles, vinyl halides, allyl compounds, vinylsilyl compounds, compounds containing a sulfonic acid group, compounds containing an amino group, etc. Among them, unsaturated acids, their salts or esters are preferred.

[0105] As the above-mentioned monocarboxylic acid having a radically polymerizable unsaturated double bond, there can be mentioned acrylic acid, crotonic acid, methacrylic acid, oleic acid, etc.

[0106] As the above-mentioned dicarboxylic acid having a radically polymerizable unsaturated double bond, there can be mentioned methylene malonic acid, itaconic acid, 2-methylene glutaric acid, 2-methylene adipic acid, 2-methylene sebacic acid, etc.

[0107] As the above-mentioned olefins, there can be mentioned ethylene, propylene, 1-butene, isobutene, etc.

[0108] As the above-mentioned (meth)acrylamides, there can be mentioned acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, etc.

[0109] As the above-mentioned N-vinylamides, there can be mentioned N-vinylformamide, N-vinylpyrrolidone, etc.

[0110] Examples of the above vinyl ethers include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, and n-butyl vinyl ether.

[0111] Examples of the above nitriles include (meth)acrylonitrile.

[0112] Examples of the above vinyl halides include vinyl chloride and vinylidene chloride.

[0113] Examples of the above allyl compounds include allyl acetate and allyl chloride.

[0114] Examples of the above vinylsilyl compounds include vinyltrimethoxysilane.

[0115] Examples of the above compounds containing a sulfonic acid group include (meth)acrylamidopropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, etc., (meth)acrylamidoalkanesulfonic acids and their salts such as these, vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, etc., olefin sulfonic acids or their salts.

[0116] Examples of the above compounds containing an amino group include vinylamine, allylamine, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine, etc.

[0117] Among them, monomers having a radically polymerizable unsaturated double bond and functional groups such as a carboxylic acid group, a sulfonic acid group, a salt of a sulfonic acid group, a pyrrolidone ring group, an amide group, and an amino group are preferably used. Specifically, dicarboxylic acids having a radically polymerizable unsaturated double bond such as itaconic acid, monocarboxylic acids having a radically polymerizable unsaturated double bond such as acrylic acid, derivatives such as their salts or esters, compounds containing a sulfonic acid group such as (meth)acrylamidoalkanesulfonic acid and their salts, N-vinylamides such as N-vinylformamide and N-vinylpyrrolidone, compounds containing an amino group such as vinylamine and allylamine, etc. are preferably used.

[0118] Examples of the polymerization catalyst used in the polymerization include di(2-ethylhexyl) peroxydicarbonate (Trigonox EHP manufactured by TianjinMcEIT), 2,2'-azobisisobutyronitrile (AIBN), tert-butyl peroxyneodecanoate, bis(4-tert-butylcyclohexyl) peroxydicarbonate, di-n-propyl peroxydicarbonate, di-n-butyl peroxydicarbonate, dicetyl peroxydicarbonate, and di-sec-butyl peroxydicarbonate. The above polymerization catalysts can be used alone or in combination of two or more.

[0119] Examples of commercially available products of the above polymerization catalysts include KAYACARBON EH-C70, Trigonox EHP-70 (both manufactured by chemical company Akzo), etc.

[0120] As the polymerization method, a method using a series of continuous tank reactors is preferred. If the number of continuous tanks is two or more, there is no particular limitation.

[0121] Hereinafter, a method using a series of continuous tank reactors formed by connecting two tanks in series will be described.

[0122] In the above polymerization method, a vinyl ester, other unsaturated monomers, a polymerization initiator, and a solvent are continuously supplied to the first tank. There is no particular limitation on the supply method of the vinyl ester, other unsaturated monomers, and polymerization initiator, and examples include: a method of separately preparing a vinyl ester solution, other unsaturated monomer solutions, and a polymerization initiator solution and supplying them; a method of preparing a monomer solution containing a vinyl ester and other unsaturated monomers and a polymerization initiator solution and supplying them, etc.

[0123] When the supply amount of the vinyl ester supplied to the first tank is 100 parts by weight, the supply amount of other unsaturated monomers supplied to the first tank is preferably 0.001 to 5 parts by weight, more preferably 0.01 to 3 parts by weight.

[0124] In addition, when the supply amount of monomers such as vinyl ester and other unsaturated monomers supplied to the first tank is 100 parts by weight, the supply amount of the polymerization initiator supplied to the first tank is preferably 0.001 to 1 part by weight, more preferably 0.01 to 0.5 part by weight.

[0125] When the supply amount of monomers such as vinyl ester and other unsaturated monomers supplied to the first tank is 100 parts by weight, the supply amount of the solvent supplied to the first tank is preferably 5 to 80 parts by weight, more preferably 10 to 40 parts by weight.

[0126] The average residence time MRT of the components supplied to the first tank in the first tank 1 is preferably 2 to 20 hours, more preferably 5 to 15 hours. It should be noted that the above average residence time indicates the degree to which the components supplied to each reaction tank are retained in each reaction tank, and can be adjusted based on the volume of the reaction liquid in the reaction tank and the volume flow rate of the components supplied to each tank. For example, when the volume of the reaction liquid in the first tank is 180 L and the volume flow rate of the components supplied to the first tank is 5 ml / second, the average residence time is 10 hours.

[0127] The temperature T of the first tank 1 is preferably 50 to 150 °C, more preferably 70 to 120 °C.

[0128] In the first tank, it is preferred to polymerize while stirring the reaction liquid. As the stirring condition, when the vortex volume is V 1 (L) and the weight of the reaction liquid is M 1 (kg), it is preferably set to V1 / M 1 The condition is 0.009 to 0.143 (L / kg), and more preferably, the condition is set to be 0.01 to 0.1 (L / kg).

[0129] If V 1 / M 1 is 0.009 (L / kg) or more, the volatilized monomer returns to the liquid phase part and is recycled, thereby improving the reactivity. If it is 0.143 (L / kg) or less, the monomer introduced into the liquid phase part will be difficult to be released into the gas phase part again, so that the reaction can proceed uniformly.

[0130] It should be noted that the above-mentioned vortex volume refers to the volume of the vortex generated at the gas-liquid interface during stirring. The above-mentioned vortex volume can be calculated, for example, using the thermal fluid and powder analysis software "R-FLOW" (manufactured by R-flow Co., Ltd.). Specifically, it can be calculated based on the distance between the center of the stirring blade and the interface between the gas phase part and the liquid phase part during stirring. It should be noted that during stirring, pressure is generated in the liquid by the stirring blade as the stirring power, the liquid phase part becomes a positive pressure, and the gas phase part becomes a negative pressure. Therefore, the interface between the gas phase part and the liquid phase part can be confirmed as the boundary part between the positive pressure and the negative pressure.

[0131] It should be noted that in the first tank, the rotation speed of the stirring blade during stirring is preferably 10 to 500 rpm, more preferably 50 to 250 rpm, and the capacity of the first tank is preferably 0.01 to 100 m 3 , more preferably 0.05 to 50 m 3 .

[0132] In addition, in the first tank, when the distance from the liquid surface to the stirring blade is set as D 1 (m), and the liquid surface height is set as H 1 (m), D 1 / H 1 is preferably adjusted to 0.3 to 0.9 (m / m), and more preferably adjusted to 0.35 to 0.8 (m / m). It should be noted that the above-mentioned liquid surface height refers to the distance from the bottom of the reaction tank to the reaction liquid surface in the state where the reaction liquid in the reaction tank is not stirred. In addition, the distance from the above-mentioned liquid surface to the stirring blade refers to the distance from the liquid surface to the uppermost part of the stirring blade.

[0133] In the first tank, when the stirring blade diameter is set as BD 1 (m), and the inner diameter of the reaction tank is set as VD 1 , BD 1 / VD 1 is preferably set to 0.1 to 0.5 (m / m), and more preferably set to 0.15 to 0.35 (m / m).

[0134] By adopting the above stirring conditions, the reaction can be carried out uniformly.

[0135] In the above polymerization method, the polymerization liquid (1) is continuously taken out from the first tank in such a way that the amount of the reaction liquid in the first tank is fixed and continuously supplied to the second tank. In addition to the polymerization liquid (1), vinyl ester, other unsaturated monomers, polymerization initiator, etc. can also be continuously supplied.

[0136] When the supply amount of the vinyl ester supplied to the first tank is 100 parts by weight, the supply amount of the vinyl ester supplied to the second tank is preferably 0 to 50 parts by weight, more preferably 5 to 30 parts by weight.

[0137] When the supply amount of the unsaturated monomer supplied to the first tank is 100 parts by weight, the supply amount of the unsaturated monomer supplied to the second tank is preferably 50 to 200 parts by weight, more preferably 75 to 150 parts by weight.

[0138] When the supply amount of the polymerization initiator supplied to the first tank is 100 parts by weight, the supply amount of the polymerization initiator supplied to the second tank is preferably 50 to 150 parts by weight, more preferably 80 to 120 parts by weight.

[0139] When the supply amount of the solvent supplied to the first tank is 100 parts by weight, the supply amount of the solvent supplied to the second tank is preferably 50 to 150 parts by weight, more preferably 80 to 120 parts by weight.

[0140] When the supply amount of the vinyl ester supplied to the first tank and the second tank is 100 parts by weight, the supply amount of the unsaturated monomer supplied to the first tank and the second tank is preferably 1 to 50 parts by weight, more preferably 10 to 30 parts by weight.

[0141] When the supply amount of monomers such as vinyl ester and other unsaturated monomers supplied to the first tank and the second tank is 100 parts by weight, the supply amount of the polymerization initiator supplied to the first tank and the second tank is preferably 0.001 to 1 part by weight, more preferably 0.01 to 0.5 part by weight.

[0142] When the supply amount of monomers such as vinyl ester and other unsaturated monomers supplied to the first tank and the second tank is 100 parts by weight, the supply amount of the solvent supplied to the first tank and the second tank is preferably 5 to 60 parts by weight, more preferably 10 to 40 parts by weight.

[0143] The average residence time MRT of the components supplied to the second tank in the second tank 2 is preferably 1.5 to 8 hours, more preferably 2.5 to 7.5 hours.

[0144] The average residence time MRT in the second tank 2 relative to the average residence time MRT in the first tank1 The ratio (MRT 2 / MRT 1 ) is preferably 0.3 to 0.9, more preferably 0.35 to 0.7.

[0145] The temperature T of the second tank 2 is preferably 60 to 100 °C, more preferably 70 to 90 °C.

[0146] The temperature T of the second tank 2 relative to the temperature T of the first tank 1 The ratio (T 2 / T 1 ) is preferably 0.6 to 1.5, more preferably 0.9 to 1.2.

[0147] In the second tank, it is preferable to polymerize while stirring the reaction solution. As the stirring conditions, when the vortex volume is set to V 2 (L) and the weight of the reaction solution is set to M 2 (kg), it is preferably set to a condition where V 2 / M 2 becomes 0.04 to 0.18 (L / kg), and more preferably set to a condition where it becomes 0.06 to 0.15 (L / kg).

[0148] If V 2 / M 2 is 0.04 (L / kg) or more, the volatilized unsaturated monomer returns to the liquid phase part and circulates, thereby improving the reactivity. If it is 0.18 (L / kg) or less, the monomer introduced into the liquid phase part is difficult to be released into the gas phase part again. Therefore, the unsaturated monomer can react while being locally present.

[0149] It should be noted that in the second tank, the rotation speed of the stirring blade during stirring is preferably 10 to 500 rpm, more preferably 100 to 400 rpm, and the capacity of the second tank is preferably 0.01 to 100 m 3 , more preferably 1 to 50 m 3 .

[0150] In addition, in the second tank, when the distance from the liquid surface to the stirring blade is set to D 2 (m) and the liquid surface height is set to H 2 (m), D 2 / H 2 is preferably adjusted to 0.3 to 0.9 (m / m), more preferably adjusted to 0.35 to 0.6 (m / m).

[0151] In the second tank, when the diameter of the stirring blade is set to BD 2 (m) and the inner diameter of the reaction tank is set to VD 2 When, BD2 / VD 2 It is preferably set to 0.1 to 0.5 (m / m), more preferably set to 0.2 to 0.4 (m / m).

[0152] By adopting the above stirring conditions, the unsaturated monomers are locally present, and the change in properties caused by the modifying groups can be further improved.

[0153] Regarding the stirring conditions in the first tank and the stirring conditions in the second tank (vortex volume / weight of the reaction liquid), V 2 / M 2 Relative to V 1 / M 1 The ratio ([V 2 / M 2 / [V 1 / M 1 ) is preferably 0.9 to 1.5, more preferably 1.0 to 1.2.

[0154] In addition, regarding (distance from the liquid surface to the stirring blade / liquid surface height), D 2 / H 2 Relative to D 1 / H 1 The ratio ([D 2 / H 2 / [D 1 / H 1 ) is preferably 0.9 to 1.5, more preferably 1.0 to 1.2.

[0155] Furthermore, regarding (stirring blade diameter / inner diameter of the reaction tank), BD 2 / VD 2 Relative to BD 1 / VD 1 The ratio ([BD 2 / VD 2 / [BD 1 / VD 1 ) is preferably 0.9 to 1.5, more preferably 1.0 to 1.2.

[0156] In the above polymerization method, the polymerization liquid (2) is continuously taken out from the second tank in such a way that the amount of the reaction liquid in the second tank is made constant. Thus, a vinyl ester copolymer can be obtained.

[0157] In addition, by adding a saponification catalyst to the obtained vinyl ester and performing saponification, a polyvinyl alcohol resin having specified physical properties can be obtained.

[0158] In particular, by using the vinyl ester copolymer obtained by the method that satisfies the reaction conditions in the above first tank and second tank, a polyvinyl alcohol resin having specified physical properties can be obtained.

[0159] As the saponification catalyst used in the above saponification, for example, alkaline catalysts such as sodium hydroxide, potassium hydroxide, sodium alkoxide, and sodium carbonate, and acidic catalysts such as sulfuric acid, phosphoric acid, and hydrochloric acid can be cited. Among them, from the aspect of being able to accelerate the saponification rate and improve productivity, alkaline catalysts are preferred, and sodium hydroxide is particularly preferred.

[0160] The addition amount of the above saponification catalyst is preferably 1.4 to 30 parts by weight, more preferably 2 to 25 parts by weight, based on 100 parts by weight of the vinyl ester copolymer.

[0161] In addition, the addition amount of the above saponification catalyst relative to the vinyl ester copolymer, the caustic molar ratio (CMR, the molar ratio of the base to the acetyl group on PVAc) is preferably 0.01 to 0.8, more preferably 0.03 to 0.6.

[0162] The method of adding the above saponification catalyst is not particularly limited, and it can be added all at once at the initial stage of the saponification reaction, or a part can be added at the initial stage of the saponification reaction, and the remaining part can be added additionally during the polymerization reaction.

[0163] The reaction temperature during the above saponification is preferably 15 to 80 °C, more preferably 20 to 60 °C.

[0164] In addition, the reaction time during the above saponification is preferably 0.4 to 5 hours, more preferably 0.5 to 4 hours.

[0165] In addition, the remaining saponification catalyst can be neutralized according to the need for the saponification degree. As the neutralizing agent used, for example, organic acids such as acetic acid and lactic acid can be cited.

[0166] The adsorption amount of the polyvinyl alcohol resin obtained by the above method with respect to barium titanate satisfies a specified range.

[0167] By adopting the above method, a polyvinyl alcohol resin with high polarity can be obtained. By using such a polyvinyl alcohol resin, it is possible to suppress the polyvinyl alcohol resin as a dispersant from detaching from around the inorganic powder over time, and when preparing a slurry composition, it is possible to suppress the sedimentation of the inorganic powder. As a result, even when using a slurry composition stored for a long time, it is possible to prevent the strength deterioration of the obtained green ceramic sheet, and a highly reliable ceramic capacitor can be manufactured. In addition, it is considered that especially by adopting the above method in the production of a polyvinyl alcohol resin having a specific modifying group, the modifying group undergoes blockification, and a polyvinyl alcohol resin having a structure with extremely high polarity locally is formed. As a result, it is possible to adsorb on the surface of the inorganic powder through the highly polar part and prevent the aggregation of other inorganic powders through the low polar part. Thus, more excellent properties can be exhibited.

[0168] The above-mentioned polyvinyl alcohol resin is soluble in aqueous solvents, so aqueous solvents can be used to produce green ceramic sheets. Therefore, there is no need to use organic solvents that have a large environmental impact. In addition, by using the above-mentioned polyvinyl alcohol resin, green ceramic sheets with high flexibility and strength can be produced, so they can be suitably used as materials for ceramic capacitors.

[0169] In addition, the above-mentioned polyvinyl alcohol resin has excellent solubility. For example, in addition to being suitable as a material for green ceramic sheets, it can also be suitably used as a packaging material for storing various substances such as pesticides, pharmaceuticals, dyes, detergents, fertilizers, cosmetics, and sanitary products. In addition, it can be suitably used for applications such as viscosity regulators for aqueous solutions, gas barrier coatings, suspending agents, emulsifiers, polarizing plates, water-soluble films, and dispersants.

[0170] In addition, a resin composition containing a polyvinyl alcohol resin, an inorganic powder, and a plasticizer, wherein the adsorption amount of the above-mentioned polyvinyl alcohol resin with respect to the above-mentioned inorganic powder is 0.05 to 5 mg / g, is also one of the present inventions.

[0171] For example, in the case of containing an inorganic powder, green ceramic sheets with excellent flexibility and strength can be produced.

[0172] As the above-mentioned polyvinyl alcohol resin, the above-mentioned polyvinyl alcohol resin can be used. Thus, green ceramic sheets can be produced using aqueous solvents, green ceramic sheets with excellent flexibility and strength can be produced, and highly reliable ceramic capacitors can be manufactured.

[0173] Examples of the above-mentioned inorganic powder include: alumina, zirconia, aluminum silicate, titanium oxide, zinc oxide, barium titanate, magnesium oxide, sialon, spinel ferrite (original text: スピネムルライト), silicon carbide, silicon nitride, aluminum nitride, etc. They can be used alone or in combination of two or more.

[0174] The adsorption amount of the above-mentioned polyvinyl alcohol resin with respect to the above-mentioned inorganic powder is 0.05 to 5 mg / g.

[0175] By setting it within the above range, for example, in the case of using an inorganic powder, green ceramic sheets can be produced using aqueous solvents, the deterioration of the flexibility and strength of the green ceramic sheets over time can be suppressed, and highly reliable ceramic capacitors can be manufactured.

[0176] The adsorption amount of the above-mentioned polyvinyl alcohol resin is preferably 0.1 mg / g or more, preferably 2.5 mg / g or less, more preferably 0.2 mg / g or more, and more preferably 1.0 mg / g or less.

[0177] It should be noted that the above adsorption amount can be measured by the same method as the adsorption amount with respect to barium titanate.

[0178] The content of the inorganic powder in the above resin composition is preferably 15% by weight or more, preferably 70% by weight or less, more preferably 25% by weight or more, and more preferably 60% by weight or less.

[0179] Examples of the plasticizer include: phthalic acid diesters such as dioctyl phthalate (DOP) and dibutyl phthalate (DBP), adipic acid diesters such as dioctyl adipate, alkylene glycol diesters such as triethylene glycol-di-2-ethylhexanoate, tetraethylene glycol-di-2-ethylhexanoate, triethylene glycol-di-2-ethylbutyrate, tetraethylene glycol-di-2-ethylbutyrate, tetraethylene glycol-di-heptanoate, and triethylene glycol-di-heptanoate.

[0180] With respect to 100 parts by weight of the above polyvinyl alcohol resin, the content of the plasticizer in the above resin composition is preferably 5 parts by weight or more, preferably 50 parts by weight or less, more preferably 10 parts by weight or more, and more preferably 40 parts by weight or less.

[0181] In the above resin composition, when the average particle diameter of the inorganic powder immediately after the dispersion treatment is defined as A and the average particle diameter of the inorganic powder 24 hours after the dispersion treatment is defined as B, A and B preferably satisfy the following relationship.

[0182] 0.7 ≤ B / A ≤ 1.0

[0183] By satisfying the above relationship, the dispersion state will not deteriorate even after a long time, and a green sheet with excellent uniformity can be obtained.

[0184] The above B / A is more preferably 0.8 or more. There is no particular limitation on the upper limit, and the less the change over time, the more preferable.

[0185] It should be noted that examples of the above dispersion treatment include: a method of mixing an inorganic powder such as barium titanate, a polyvinyl alcohol resin, water, a plasticizer, a dispersant, etc., and stirring and dispersing them using a bead mill. In addition, as the conditions during stirring, for example, a method of treating at 1500 rpm for 90 minutes can be used. In addition, for example, a method of mixing 10 parts by weight of a polyvinyl alcohol resin and 200 parts by weight of water with respect to 100 parts by weight of the inorganic powder can be used.

[0186] In addition, the average particle diameter immediately after the dispersion treatment refers to the average particle diameter measured 5 minutes after the dispersion treatment.

[0187] The above average particle diameter can be measured using a laser diffraction particle size distribution analyzer, for example.

[0188] As a method for producing the above resin composition, for example, the following method can be cited: the above polyvinyl alcohol resin is produced by the above method, and the obtained polyvinyl alcohol resin, inorganic powder, plasticizer, and additives added as needed are mixed using various mixers such as a three-roll mill, ball mill, and bead mill.

[0189] In the above resin composition, for example, in the case of using an inorganic powder, an aqueous solvent is added to the above resin composition, coated, and dried to produce a green ceramic sheet.

[0190] In addition, an inorganic powder, an aqueous solvent, and other additives are added to the above polyvinyl alcohol resin, coated, and dried, whereby a green ceramic sheet can be produced.

[0191] As a coating method, for example, methods such as a roll coater, a die coater, and a curtain coater can be cited. It should be noted that for other specific methods, conventionally known methods can be used.

[0192] By using the above polyvinyl alcohol resin and the above resin composition, a green ceramic sheet can be produced.

[0193] Such a green ceramic sheet is also one of the present inventions.

[0194] In addition, the above green ceramic sheet can be used to manufacture ceramic electronic components.

[0195] For example, by performing a step of coating a paste for an electrode layer on the surface of a green ceramic sheet, and a step of degreasing and firing a laminate obtained by laminating and thermocompression bonding the green ceramic sheets formed with electrode layers, ceramic electronic components can be manufactured.

[0196] The above ceramic electronic components are not particularly limited, and examples include: ceramic capacitors, ceramic inductors, capacitors, piezoelectric actuators, multilayer varistors, multilayer thermistors, EMI filters, aluminum nitride multilayer substrates, alumina multilayer substrates, etc.

[0197] In the manufacturing method of the above ceramic electronic components, after producing the above green ceramic sheet formed with an electrode layer, green ceramic sheets formed with electrode layers produced in the same manner are laminated and thermocompression bonded to obtain a laminate, and the laminate is degreased and fired, whereby a multilayer ceramic electronic component that solves problems such as sheet attack and cracks is obtained.

[0198] It should be noted that the above thermocompression bonding step and the steps of degreasing and firing the laminate are not particularly limited, and conventionally known methods can be used.

[0199] A ceramic capacitor using the above green ceramic sheet is also one of the present inventions.

[0200] Advantages of the Invention

[0201] According to the present invention, it is possible to provide a polyvinyl alcohol resin that can be used to produce a green sheet of ceramics using an aqueous solvent, can suppress the sedimentation of inorganic powder, produce a green sheet of ceramics with excellent flexibility and strength, and can manufacture a ceramic capacitor with high reliability. Detailed Description of the Invention

[0202] Hereinafter, examples will be given to describe the present invention in more detail, but the present invention is not limited to these examples.

[0203] (Example 1)

[0204] (Production of Polyvinyl Acetate)

[0205] A series continuous tank reactor in which a glass-lined reaction vessel with an internal volume of 300 L (first tank) and a glass-lined reaction vessel with an internal volume of 300 L (second tank) are connected in series via a metering pump is used.

[0206] Prepare a methanol solution of vinyl acetate and vinylamine (monomer solution (1)). In addition, prepare a methanol solution of 2,2'-azobisisobutyronitrile (initiator solution (1)).

[0207] The monomer solution (1) and the initiator solution (1) are respectively adjusted using a metering pump in the form of a separate supply line and continuously supplied to the first tank in such a manner that, with respect to 100 parts by weight of vinyl acetate, vinylamine is 2 parts by weight, the polymerization initiator is 0.01 part by weight, and the solvent is 30 parts by weight. While maintaining the internal temperature at 80°C, the polymerization is carried out with an average residence time of 10 hours while stirring in such a manner that the ratio of the vortex volume V 1 (L) of the reaction liquid (monomer solution (1) and initiator solution (1)) in the first tank to the weight M 1 (kg) (V 1 / M 1 ) becomes 0.07 (L / kg), and the polymerization liquid (1) is continuously withdrawn from the first tank and supplied to the second tank in such a manner that the reaction liquid volume in the first tank is fixed at 180 kg. It should be noted that the distance D 1 from the liquid surface to the stirring blade and the liquid surface height H 1 are adjusted in such a manner that the ratio (D 1 / H 1 ) becomes 0.5 (m / m). In addition, the ratio of the stirring blade diameter BD 1 to the inner diameter VD 1 of the reaction vessel (BD 1 / VD 1 ) is 0.3 (m / m).

[0208] Except for the polymerization liquid (1) from the first tank, a methanol solution of vinyl acetate and vinylamine (monomer solution (2)) and a methanol solution of 2,2'-azobisisobutyronitrile (initiator solution (2)) are adjusted such that, with respect to 100 parts by weight of vinyl acetate supplied to the first tank, the vinyl acetate supplied to the second tank is 30 parts by weight, the vinylamine is 20 parts by weight, the polymerization initiator is 0.01 part by weight, and the solvent is 50 parts by weight, and are continuously supplied to the second tank. While maintaining the internal temperature at 80 °C, the vortex volume V 2 (L) generated at the gas-liquid interface by stirring and the weight M 2 (kg) of the reaction liquid (polymerization liquid (1), monomer solution (2), and initiator solution (2)) in the second tank 2 ratio (V 2 / M 2 ) becomes 0.07 (L / kg), and stirring is carried out while polymerizing with an average residence time of 5 hours so that the amount of the reaction liquid in the second tank is fixed at 150 kg, and the polymerization liquid (2) is continuously withdrawn from the second tank. It should be noted that the distance D 2 from the liquid surface to the stirring blade and the liquid surface height H 2 ratio (D 2 / H 2 ) is adjusted to be 0.6 (m / m) by adjusting the height of the stirring blade. In addition, the ratio of the stirring blade diameter BD 2 to the inner diameter VD 2 of the reaction vessel (BD 2 / VD

[0209] Methanol vapor is introduced into the polymerization liquid (2) withdrawn from the second tank to remove unreacted monomers, and a methanol solution of polyvinyl acetate (PVAc-1) is obtained.

[0210] (Production of polyvinyl alcohol resin)

[0211] For the obtained PVAc-1, methanol is added to make the concentration 35% by weight to prepare a PVAc solution. For this PVAc solution, sodium hydroxide as a saponification catalyst is added such that the caustic molar ratio (CMR, molar ratio of base to acetyl group on PVAc) becomes 0.02, and saponification is carried out while maintaining at 40 °C for 3 hours. The solidified polymer is pulverized in a pulverizer, washed with methanol, and dried in an oven to obtain a polyvinyl alcohol resin (1) having a structural unit with an amino group represented by the following formula (7-1).

[0212] [Chemical formula 9]

[0213]

[0214] (Example 2)

[0215] In the first tank, adjustment was made such that the amount of vinylamine was 20 parts by weight, the polymerization initiator was 0.005 parts by weight, and the solvent was 15 parts by weight with respect to 100 parts by weight of vinyl acetate. Further, in the second tank, adjustment was made such that the amount of vinyl acetate supplied to the second tank was 30 parts by weight, the vinylamine was 40 parts by weight, the polymerization initiator was 0.01 parts by weight, and the solvent was 50 parts by weight with respect to 100 parts by weight of vinyl acetate supplied to the first tank. In addition, as shown in Table 1, the temperature, V 1 / M 1 、D 1 / H 1 、BD 1 / VD 1 、average residence time, the temperature in the second tank, V 2 / M 2 、D 2 / H 2 、BD 2 / VD 2 、average residence time, the addition amount of the saponification catalyst, and the saponification reaction time were changed. Other than this, the operation was the same as in Example 1, and a polyvinyl alcohol resin (2) was obtained.

[0216] (Example 3)

[0217] 2-Acrylamido-2-methylpropanesulfonic acid sodium salt (AMPS) was used in place of vinylamine. Further, in the first tank, adjustment was made such that the amount of AMPS was 3 parts by weight with respect to 100 parts by weight of vinyl acetate. Other than the above, the operation was the same as in Example 1, and a polyvinyl alcohol resin (3) having a structural unit with a sulfonic acid group represented by the following formula (4-1-1) was obtained.

[0218] [Chemical formula 10]

[0219]

[0220] (Example 4)

[0221] N-Vinylpyrrolidone was used in place of vinylamine. Further, in the first tank, adjustment was made such that the amount of N-vinylpyrrolidone was 3 parts by weight with respect to 100 parts by weight of vinyl acetate. Other than the above, the operation was the same as in Example 1, and a polyvinyl alcohol resin (4) having a structural unit with a pyrrolidone ring group represented by the following formula (5) was obtained.

[0222] [Chemical formula 11]

[0223]

[0224] (Example 5)

[0225] Use itaconic acid in place of vinylamine. Additionally, in the first tank, adjust it so that the amount of itaconic acid is 3 parts by weight relative to 100 parts by weight of vinyl acetate. Furthermore, as shown in Table 1, change the temperature in the first tank, V 1 / M 1 、D 1 / H 1 、BD 1 / VD 1 、average residence time, the temperature in the second tank, V 2 / M 2 、D 2 / H 2 、BD 2 / VD 2 、average residence time, the addition amount of the saponification catalyst, and the saponification reaction time. Other than that, a polyvinyl alcohol resin (5) having a structural unit with a carboxyl group represented by the following formula (3-1-1) was obtained.

[0226] [Chemical formula 12]

[0227]

[0228] (Example 6)

[0229] Use itaconic acid in place of vinylamine, and make the temperature in the first tank, V 1 / M 1 、D 1 / H 1 、BD 1 / VD 1 、average residence time, the temperature in the second tank, V 2 / M 2 、D 2 / H 2 、BD 2 / VD 2 、average residence time as shown in Table 1. Other than that, operate in the same manner as in Example 1 to produce polyvinyl acetate (PVAc-6).

[0230] In addition, without adding vinylamine, make the temperature in the first tank, V 1 / M 1 、D 1 / H 1 、BD 1 / VD 1 、average residence time, the temperature in the second tank, V 2 / M 2 、D 2 / H2 and BD 2 / VD 2 The average residence time is shown in Table 1. Other than that, the operation was the same as in Example 1, and polyvinyl acetate (PVAc-7) was produced.

[0231] In the production of the polyvinyl alcohol resin, a PVAc solution was prepared such that the weight ratio of PVAc-6 and PVAc-7 became 50:50. Other than that, the operation was the same as in Example 1, and polyvinyl alcohol resin (6) was obtained.

[0232] (Examples 7 to 35)

[0233] As shown in Tables 1 and 2, the types of other unsaturated monomers, the temperature in the first tank, V 1 / M 1 and D 1 / H 1 and BD 1 / VD 1 the average residence time, the temperature in the second tank, V 2 / M 2 and D 2 / H 2 and BD 2 / VD 2 the average residence time, the addition amount of the saponification catalyst, and the saponification reaction time were changed. Other than that, the operation was the same as in Example 1, and polyvinyl alcohol resin was produced.

[0234] (Comparative Examples 1 to 3)

[0235] As shown in Table 3, the types of other unsaturated monomers, the temperature in the first tank, V 1 / M 1 and D 1 / H 1 and BD 1 / VD 1 the average residence time, the temperature in the second tank, V 2 / M 2 and D 2 / H 2 and BD 2 / VD 2 the average residence time, the addition amount of the saponification catalyst, and the saponification reaction time were changed. Other than that, the operation was the same as in Example 1, and polyvinyl alcohol resin was produced.

[0236] (Comparative Example 4)

[0237] As the polyvinyl alcohol resin, Mowital B75H (polyvinyl butyral resin) manufactured by Kuraray Co., Ltd. was used.

[0238] (Comparative Example 5)

[0239] In the first tank, adjustment was made such that the amount of vinylamine was 80 parts by weight, the polymerization initiator was 0.005 parts by weight, and the solvent was 10 parts by weight with respect to 100 parts by weight of vinyl acetate. Further, in the second tank, adjustment was made such that the amount of vinyl acetate supplied to the second tank was 70 parts by weight, the vinylamine was 40 parts by weight, the polymerization initiator was 0.01 parts by weight, and the solvent was 30 parts by weight with respect to 100 parts by weight of vinyl acetate supplied to the first tank. In addition, as shown in Table 3, the temperature in the first tank, V 1 / M 1 、D 1 / H 1 、BD 1 / VD 1 、the average residence time, the temperature in the second tank, V 2 / M 2 、D 2 / H 2 、BD 2 / VD 2 、the average residence time, the addition amount of the saponification catalyst, and the saponification reaction time were changed. Other than this, the operation was carried out in the same manner as in Example 1 to obtain a polyvinyl alcohol resin (31).

[0240] (Comparative Examples 6 to 28)

[0241] As shown in Tables 3 and 4, the types of other unsaturated monomers, the temperature in the first tank, V 1 / M 1 、D 1 / H 1 、BD 1 / VD 1 、the average residence time, the temperature in the second tank, V 2 / M 2 、D 2 / H 2 、BD 2 / VD 2 、the average residence time, the addition amount of the saponification catalyst, and the saponification reaction time were changed. Other than this, the operation was carried out in the same manner as in Example 1 to produce a polyvinyl alcohol resin.

[0242] (Evaluation)

[0243] The polyvinyl alcohol resins obtained in the examples and comparative examples were evaluated as follows. The results are shown in Tables 5 to 12.

[0244] (1) Amount of hydroxyl groups, amount of residual acetyl groups, amount of modified groups

[0245] The obtained polyvinyl alcohol resin was dissolved in heavy water so that the concentration became 1 wt%, and1 The amounts of hydroxyl groups, residual acetyl groups, and modified groups were determined by \(^{1}H-NMR\).

[0246] (2)Viscosity-average degree of polymerization

[0247] A 4 wt% aqueous solution of the obtained polyvinyl alcohol resin was prepared, and the viscosity-average degree of polymerization was measured by the method according to JIS K6726-1994.

[0248] (3)Adsorption amount

[0249] In a glass centrifuge tube, 6 g of a 5 wt% aqueous solution of the obtained polyvinyl alcohol resin was added relative to 1.5 g of barium titanate (BT-04 manufactured by Sakai Chemical Industry Co., Ltd., average particle size 0.4 μm). It should be noted that BT-04 is a true spherical high-purity perovskite compound manufactured by the hydrothermal method. Then, the upper part of the glass centrifuge tube was fixed and sealed with plastic tape. The glass centrifuge tube was fixed to an ultrasonic disperser (VS-100III, a 3-frequency ultrasonic cleaner manufactured by AS ONE Corporation) with plastic tape and stirred for 10 minutes under the condition of a frequency of 100 kHz. Then, it was treated at 10000 rpm for 5 minutes using a centrifuge (CN-2200, a digital centrifuge manufactured by Leona Corporation).

[0250] The aluminum cup was heated with an infrared dryer for 30 minutes, cooled in a desiccator, and then the weight of the aluminum cup was measured. 4 g of the supernatant in the glass centrifuge tube was weighed into the aluminum cup. Then, the solvent was thoroughly removed using an infrared dryer and further dried in a vacuum dryer for 2 hours. The aluminum cup was cooled and weighed, and the weight of the polyvinyl alcohol resin contained in the supernatant part was determined. The reduction amount of the polyvinyl alcohol resin was calculated based on the initial concentration (5 wt%) and the concentration of the supernatant part. The reduced amount was taken as the amount adsorbed on barium titanate, and the adsorption amount relative to barium titanate was determined.

[0251] (4)Dispersibility maintenance rate B / A

[0252] To 10 parts by weight of the obtained polyvinyl alcohol resin, 3 parts by weight of glycerol as a plasticizer and 40 parts by weight of water were added, and they were dissolved under the conditions of 100 °C for 1 hour to obtain an aqueous polyvinyl alcohol resin solution. Further, 100 parts by weight of barium titanate (BT-04 manufactured by Sakai Chemical Industry Co., Ltd.) as an inorganic powder, 160 parts by weight of water, 2 parts by weight of A6001 manufactured by Toagosei Co., Ltd. as a dispersant and 100 parts by weight of zirconia beads with a diameter of 1 mm were stirred and dispersed together using a bead mill (EasyNano manufactured by AIMEX Co., Ltd.) at 1500 rpm for 20 minutes. Then, the entire amount of the previously obtained aqueous polyvinyl alcohol resin solution was added, and after stirring and dispersing at 1500 rpm for 90 minutes, the zirconia beads were removed by filtration to obtain a slurry composition. For the obtained slurry composition, the average particle diameter A of the inorganic powder after 5 minutes of dispersion treatment was measured using a laser diffraction particle size distribution analyzer (LA-910 manufactured by Horiba, Ltd.). In addition, the average particle diameter B of the inorganic powder 24 hours after the start of dispersion treatment was measured in the same manner, and the dispersion maintenance rate B / A was calculated.

[0253] (5) Solubility parameter

[0254] The solubility parameter was determined using the value measured by the Fedors method.

[0255] (6) Aqueous solvent solubility

[0256] 10 g of the polyvinyl alcohol resin of the examples and comparative examples was added to 90 g of water, and after stirring at 100 °C and a rotation speed of 60 rpm for 1 hour, the evaluation was carried out according to the following criteria.

[0257] 〇: All powders were visually observed to dissolve.

[0258] ×: Solid components remaining undissolved in the aqueous solution were visually confirmed.

[0259] (7) Sedimentation evaluation, breaking strength, breaking strength retention rate, elongation at break, elongation at break retention rate

[0260] To 10 parts by weight of the obtained polyvinyl alcohol resin, 3 parts by weight of glycerol as a plasticizer and 40 parts by weight of water were added, and they were dissolved under the conditions of 100 °C for 1 hour to obtain an aqueous polyvinyl alcohol resin solution. Further, 100 parts by weight of barium titanate (BT-04 manufactured by Sakai Chemical Industry Co., Ltd.) as an inorganic powder, 160 parts by weight of water, 2 parts by weight of "A6001" manufactured by Toagosei Co., Ltd. as a dispersant, and 100 parts by weight of zirconia beads with a diameter of 1 mm were stirred and dispersed together using a bead mill (EasyNano manufactured by AIMEX Co., Ltd.) at 1500 rpm for 20 minutes. Then, the entire amount of the previously obtained aqueous polyvinyl alcohol resin solution was added, and after stirring and dispersing at 1500 rpm for 90 minutes, the zirconia beads were removed by filtration to obtain a resin composition for green ceramic sheets.

[0261] The obtained resin composition for green ceramic sheets was put into a sample bottle, covered with a lid and sealed, and then left standing at 25 °C, and the sedimentation situation after 72 hours was confirmed and evaluated according to the following criteria.

[0262] A: No sedimentation was visually confirmed.

[0263] B: A little sedimentation was confirmed, but a transparent water layer could be visually confirmed above half the height of the liquid surface.

[0264] C: It was visually confirmed that the entire inorganic powder layer sank below half the height of the liquid surface.

[0265] In addition, the obtained resin composition for green ceramic sheets was coated on a demolded polyethylene terephthalate (PET) film so that the dried film thickness became 20 μm, and then dried to produce a green ceramic sheet.

[0266] Samples with a size of 20 mm in width and 100 mm in length were cut out from the obtained green ceramic sheets. For the obtained samples, a tensile test was carried out using a Tensilon tensile testing machine (Autograph AGS-X 500N manufactured by Shimadzu Corporation) under the conditions of 25 °C and a tensile speed of 510 mm / sec, and the breaking strength (MPa) and elongation at break (%) were measured.

[0267] In addition, using the resin composition for green ceramic sheets after standing for 24 hours in the same way, green ceramic sheets were produced, and thus the retention rates of breaking strength and elongation at break over time were measured.

[0268] In addition, ferrite powder (FRX-959 manufactured by Toda Kogyo Corporation) was used instead of barium titanate, and the sedimentation evaluation was carried out in the same way. In addition, the breaking strength, elongation at break, retention rate of breaking strength, and retention rate of elongation at break were measured.

[0269] It should be noted that for Comparative Example 4, since the resin is insoluble in water, it is in a state where the resin powder is dispersed in water, so the above evaluation cannot be carried out.

[0270] [Table 1]

[0271]

[0272] [Table 2]

[0273]

[0274] [Table 3]

[0275]

[0276] [Table 4]

[0277]

[0278] [Table 5]

[0279]

[0280] [Table 6]

[0281]

[0282] [Table 7]

[0283]

[0284] [Table 8]

[0285]

[0286] [Table 9]

[0287]

[0288] [Table 10]

[0289]

[0290] [Table 11]

[0291]

[0292] [Table 12]

[0293]

[0294] Industrial Applicability

[0295] According to the present invention, it is possible to provide a polyvinyl alcohol resin which can produce a green ceramic sheet using an aqueous solvent, can suppress the sedimentation of inorganic powder, produce a green ceramic sheet with excellent flexibility and strength, and can manufacture a ceramic capacitor with high reliability.

Claims

1. A polyvinyl alcohol resin, wherein the amount of the polyvinyl alcohol resin adsorbed to barium titanate is 0.05 mg / g to 5 mg / g. 2 . The polyvinyl alcohol resin according to claim 1 , which has a solubility parameter of 12 or more. 3 . The polyvinyl alcohol resin according to claim 1 , which has at least one functional group selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a pyrrolidone ring group, an amide group and an amino group in a side chain.

4. A resin composition comprising a polyvinyl alcohol resin, an inorganic powder and a plasticizer, The adsorption amount of the polyvinyl alcohol resin relative to the inorganic powder is 0.05 mg / g to 5 mg / g.

5. The resin composition according to claim 4, wherein When the average particle size of the inorganic powder immediately after the dispersion treatment is defined as A and the average particle size of the inorganic powder 24 hours after the dispersion treatment is defined as B, A and B satisfy the following relationship: 0.7≤B / A≤1.

0. 6 . A ceramic green sheet, comprising the polyvinyl alcohol resin according to claim 1 , or the resin composition according to claim 4 .

7. A ceramic capacitor formed by using the ceramic green sheet according to claim 6.

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