Polyvinyl acetal resin

Abstract

The present invention provides: a polyvinyl acetal resin which has excellent adhesion over a wide temperature range and is capable of obtaining a high-strength ceramic green sheet; a slurry composition for a ceramic green sheet, which uses the polyvinyl acetal resin; ceramic green sheets; and a laminated ceramic capacitor. The present invention relates to a polyvinyl acetal resin having a tan [delta] peak top temperature of 35 DEG C to 80 DEG C (inclusive) and a tan [delta] peak half-value width of 10.1 DEG C to 30 DEG C (inclusive) in a dynamic viscoelasticity measurement at 1 Hz.

Description

Technical Field

[0001] The present invention relates to a polyvinyl acetal resin, a slurry composition for a ceramic green sheet, a ceramic green sheet, and a laminated ceramic capacitor. Background Art

[0002] In recent years, electronic components installed in various electronic devices have been miniaturized and laminated, and laminated electronic components such as multilayer circuit boards, laminated coils, and laminated ceramic capacitors have been widely used.

[0003] Among them, multilayer ceramic capacitors are generally manufactured through the following steps.

[0004] First, a binder resin such as polyvinyl butyral resin or poly(meth)acrylate resin is dissolved in an organic solvent. A plasticizer, dispersant, and other agents are added to the resulting solution. Ceramic raw material powder is then added and uniformly mixed using a mixing device such as a bead mill or ball mill. After degassing, a ceramic slurry composition with a certain viscosity is obtained. This slurry composition is then cast onto a release-treated support such as polyethylene terephthalate film or SUS board using a doctor blade or reverse roll coater. Volatile components such as the solvent are then removed by heating, and the slurry is then peeled from the support to produce a ceramic green sheet.

[0005] Next, a conductive paste, which will become the internal electrodes, is applied to the resulting ceramic green sheets by screen printing. Multiple sheets are alternately stacked and heat-pressed to form a laminate. A degreasing process, known as a degreasing process, is then performed to remove the binder resin components contained in the laminate by thermal decomposition. External electrodes are then sintered onto the end faces of the resulting sintered ceramic body, resulting in a laminated ceramic capacitor.

[0006] For example, Patent Document 1 describes a polyvinyl acetal resin suitable as a ceramic binder, which has a predetermined degree of polymerization, a content of vinyl ester units, and a degree of acetalization, and a molar ratio of a portion acetalized with acetaldehyde to a portion acetalized with butyraldehyde within a predetermined range.

[0007] Patent Document 2 describes a polyvinyl acetal resin having a predetermined degree of polymerization, content of vinyl ester units, and degree of acetalization, and having specific structural units.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-236304

[0011] Patent Document 2: International Publication No. 2012 / 023517 Summary of the Invention

[0012] Problems to be solved by the invention

[0013] Meanwhile, the demand for thinner ceramic green sheets is increasing as multilayer ceramic capacitors achieve higher capacitance and smaller sizes. To meet these demands, improvements in organic binders are needed to reduce structural defects. However, even the polyvinyl acetal resins described in Patent Documents 1 and 2 suffer from increased structural defects due to insufficient adhesion and strength over a wide temperature range, particularly from low temperatures.

[0014] An object of the present invention is to provide a polyvinyl acetal resin having excellent adhesion over a wide temperature range and capable of producing a high-strength ceramic green sheet; a slurry composition for a ceramic green sheet using the polyvinyl acetal resin; a ceramic green sheet; and a multilayer ceramic capacitor.

[0015] Means for solving problems

[0016] The present disclosure 1 relates to a polyvinyl acetal resin having a tan δ peak top temperature of 35° C. to 80° C. and a tan δ peak half-value width of 10.1° C. to 30° C. in a dynamic viscoelasticity measurement at 1 Hz.

[0017] This disclosure 2 relates to the polyvinyl acetal resin described in this disclosure 1, which has a structural unit having an alkylene oxide group.

[0018] This disclosure 3 relates to the polyvinyl acetal resin described in this disclosure 2, which includes a polyvinyl acetal having a structural unit having an alkylene oxide group and a polyvinyl acetal not having an alkylene oxide group.

[0019] Present Disclosure 4 relates to the polyvinyl acetal resin described in Present Disclosure 2 or 3, wherein the number of carbon atoms in the alkylene oxide group is 2 or more and 200 or less.

[0020] Present Disclosure 5 relates to the polyvinyl acetal resin described in any one of Present Disclosures 2 to 4, wherein the number of repeating units of the alkylene oxide group is 2 or more and 100 or less.

[0021] Present Disclosure 6 relates to the polyvinyl acetal resin described in any one of Present Disclosures 2 to 5, wherein the alkylene oxide group is at least one selected from the group consisting of ethylene oxide and propylene oxide.

[0022] Present Disclosure 7 relates to the polyvinyl acetal resin according to any one of Present Disclosures 2 to 6, wherein the content of the structural unit having an alkylene oxide is 0.1 mol % or more and 5 mol % or less based on the entire polyvinyl acetal resin.

[0023] Present Disclosure 8 relates to the polyvinyl acetal resin described in any one of Present Disclosures 2 to 7, which contains a structural unit having an acetal group, a structural unit having an acetyl group, a structural unit having a hydroxyl group, and a structural unit having an alkylene oxide group.

[0024] Present Disclosure 9 relates to the polyvinyl acetal resin described in any one of Present Disclosures 1 to 8, wherein the content of the structural unit having a hydroxyl group is 23 mol % or more and 40 mol % or less based on the entire polyvinyl acetal resin.

[0025] Present Disclosure 10 relates to a slurry composition for ceramic green sheets, comprising the polyvinyl acetal resin described in any one of Present Disclosures 1 to 9, an organic solvent, and ceramic powder.

[0026] This disclosure 11 relates to a ceramic green sheet produced using the slurry composition for ceramic green sheets described in this disclosure 10.

[0027] Present Disclosure 12 relates to a multilayer ceramic capacitor obtained by using the ceramic green sheet described in Present Disclosure 11.

[0028] Hereinafter, the present invention will be described in detail.

[0029] The present inventors conducted intensive research and found that by controlling the peak top temperature and peak half-value width of tan δ within predetermined ranges, it is possible to obtain a polyvinyl acetal resin having excellent adhesion over a wide temperature range and capable of producing a high-strength ceramic green sheet, a slurry composition for a ceramic green sheet using the polyvinyl acetal resin, a ceramic green sheet, and a multilayer ceramic capacitor, thereby completing the present invention.

[0030] The polyvinyl acetal resin of the present invention has a tan δ peak top temperature of 35°C or higher and 80°C or lower in a 1 Hz dynamic viscoelasticity measurement. Setting the temperature at 35°C or higher generally maintains sheet strength at room temperature, while setting the temperature at 80°C or lower allows for adhesion at low temperatures. The preferred lower limit for the tan δ peak top temperature is 40°C, more preferably 45°C, even more preferably 50°C, and even more preferably 55°C. The preferred upper limit is 79°C, more preferably 75°C, even more preferably 70°C, and even more preferably 60°C.

[0031] The tan δ peak top temperature is, for example, the temperature value at the tan δ peak top when dynamic viscoelasticity is measured using DMA (manufactured by IT Instruments Co., Ltd.) within a temperature range of 30° C. to 150° C., a heating rate of 6° C. / min, and a frequency of 1 Hz.

[0032] In a 1 Hz dynamic viscoelasticity measurement, the polyvinyl acetal resin of the present invention has a tan δ peak half-value width of 10.1°C or higher and 30°C or lower. A peak half-value width of 10.1°C or higher allows for adhesion at lower temperatures, while a peak half-value width of 30°C or lower allows for sheet strength at low temperatures. The preferred lower limit of the tan δ peak half-value width is 10.3°C, more preferably 10.5°C, even more preferably 11°C, and even more preferably 11.5°C. The preferred upper limit is 29°C, more preferably 28°C, even more preferably 27°C, and even more preferably 25°C.

[0033] The tan δ peak half-value width is, for example, the half-value width of the tan δ peak when dynamic viscoelasticity measurements are performed using DMA (manufactured by IT Measurement Co., Ltd.) within a temperature range of 30°C to 150°C, a heating rate of 6°C / minute, and a frequency of 1 Hz. The half-value width refers to the peak width at a height position of 1 / 2 (50%) of the observed peak. If the peak shape is tilted and measurement of the half-value width is difficult, the half-value width is measured after baseline correction using the value ±30°C from the peak top.

[0034] The dynamic viscoelasticity of the polyvinyl acetal resin of the present invention was measured under the conditions of a temperature range of 30°C to 150°C, a heating rate of 6°C / min, and a frequency of 1 Hz, and baseline correction was performed to obtain the following: Figure 1 The peak curve of tan δ shown in FIG. 1 can be used to determine the peak top temperature and peak half-value width of tan δ based on the peak curve.

[0035] In general, when the dynamic viscoelasticity measurement is performed on a polyvinyl acetal resin, a single peak is obtained. Therefore, in the present invention, it is preferable not to detect a plurality of peaks.

[0036] The storage modulus E' of the polyvinyl acetal resin of the present invention at 60°C is preferably 500,000 Pa or more. By setting it to 500,000 Pa or more, the sheet strength at high temperatures can be maintained.

[0037] The more preferred lower limit of the storage modulus E' at 60°C is 1,000,000 Pa, and the preferred upper limit is 2,000,000,000 Pa.

[0038] The storage elastic modulus E' at 60°C is, for example, a value measured using DMA (manufactured by IT Measurement Co., Ltd.) in a temperature range of 30°C to 150°C, a heating rate of 6°C / min, and a frequency of 1 Hz.

[0039] The peak top temperature of tan δ, the peak half-value width, and the storage modulus E' at 60°C can be adjusted by, for example, appropriately setting the modification type of the raw material polyvinyl alcohol resin, the saponification degree, the aldehyde type, the conditions for the acetalization reaction, the acetal group content, the hydroxyl group content, the acetyl group content, and the content of the structural unit having an alkylene oxide group in the polyvinyl acetal resin.

[0040] When a modified polyvinyl alcohol resin is used as the raw material polyvinyl alcohol resin, the peak top temperature of tan δ, the peak half-value width, and the storage modulus E' at 60° C. can be adjusted by mixing an unmodified polyvinyl alcohol resin and a modified polyvinyl alcohol resin, or by varying the ratio of the modified polyvinyl alcohol resin. In particular, an alkylene oxide-modified polyvinyl alcohol resin is preferably used as the modified polyvinyl alcohol resin.

[0041] It should be noted that in the present invention, when a mixture of multiple polyvinyl alcohol resins is used as the raw material polyvinyl alcohol resin, the product obtained after the acetalization reaction is described as "polyvinyl acetal resin." For example, when a raw material containing an unmodified polyvinyl alcohol resin and a modified polyvinyl alcohol resin is acetalized, a polyvinyl acetal resin can be obtained. The polyvinyl acetal resin obtained in this manner is a polyvinyl acetal resin containing modified polyvinyl acetal and unmodified polyvinyl acetal.

[0042] The polyvinyl acetal resin of the present invention preferably contains: a polyvinyl acetal having a structural unit having an alkylene oxide, and a polyvinyl acetal not having an alkylene oxide. The above can be separated by high performance liquid chromatography (HPLC) and by using 1 The composition analysis was combined with H-NMR for confirmation.

[0043] The polyvinyl acetal resin of the present invention generally has a structural unit having a hydroxyl group represented by the following formula (1), a structural unit having an acetyl group represented by the following formula (2), and a structural unit having an acetal group represented by the following formula (3).

[0044] [Chemical Formula 1]

[0045]

[0046] In the above formula (3), R 1 It represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.

[0047] Examples of the alkyl group having 1 to 20 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl. Among them, methyl, ethyl, and propyl are preferred.

[0048] In the polyvinyl acetal resin of the present invention, the lower limit of the content of the structural unit having an acetal group represented by the above formula (3) with respect to the whole polyvinyl acetal resin (hereinafter, also referred to as "acetal group amount") is preferably 60 mol%, and the upper limit is preferably 75 mol%.

[0049] If the above acetal group amount is 60 mol% or more, the solubility in an organic solvent can be improved. If the above acetal group amount is 75 mol% or less, a polyvinyl acetal resin with excellent adhesiveness can be produced.

[0050] The more preferable lower limit of the above acetal group amount is 63 mol%, and the more preferable upper limit is 75 mol%.

[0051] The above acetal group amount can be measured by 1 1H-NMR.

[0052] It should be noted that, regarding the calculation method of the acetal group amount, since the acetal group of the polyvinyl acetal resin is obtained by acetalizing two hydroxyl groups of polyvinyl alcohol, a method of counting the two acetalized hydroxyl groups is adopted.

[0053] In the polyvinyl acetal resin of the present invention, when R in the above formula (3) 1 has a methyl group, the lower limit of the content of this structural unit with respect to the whole polyvinyl acetal resin (hereinafter, also referred to as "acetal group (Japanese original text: acetoacetal group) amount") is preferably 1 mol%, and the upper limit is preferably 75 mol%. The more preferable lower limit of the above acetal group amount is 10 mol%, and the more preferable upper limit is 60 mol%.

[0054] In addition, in the polyvinyl acetal resin of the present invention, when R in the above formula (3) 1 has a n-propyl group, the lower limit of the content of this structural unit with respect to the whole polyvinyl acetal resin (hereinafter, also referred to as "butyraldehyde group amount") is preferably 1 mol%, and the upper limit is preferably 75 mol%. The more preferable lower limit of the above butyraldehyde group amount is 10 mol%, and the more preferable upper limit is 60 mol%.

[0055] In the polyvinyl acetal resin of the present invention, when R in the above formula (3) 1 has both a methyl group and a n-propyl group, the ratio of the above acetal group amount to the above butyraldehyde group amount [also referred to as acetal group amount / butyraldehyde group amount, aceto / butyl ratio (Japanese original text: aceto / butyl ratio)] is preferably 0.06 or more and 850 or less.

[0056] In the polyvinyl acetal resin of the present invention, the content of the structural unit having an acetyl group represented by the general formula (2) relative to the entire polyvinyl acetal resin (hereinafter also referred to as "acetyl group content") is preferably 0.1 mol % at the lower limit and 15 mol % at the upper limit.

[0057] When the acetyl group content is 0.1 mol% or more, the viscosity of the ceramic green sheet slurry composition can be suppressed due to intramolecular and intermolecular hydrogen bonding of hydroxyl groups in the polyvinyl acetal resin. When the acetyl group content is 15 mol% or less, the flexibility of the polyvinyl acetal resin is not excessively increased, thereby improving handling properties.

[0058] A more preferred lower limit of the amount of acetyl groups is 0.3 mol %, and a more preferred upper limit is 12 mol %.

[0059] The above acetyl group amount can be 1 The measurement was performed by H-NMR.

[0060] In the polyvinyl acetal resin of the present invention, the content of the structural unit having a hydroxyl group represented by the general formula (1) relative to the entire polyvinyl acetal resin (hereinafter also referred to as "hydroxyl group content") is preferably 23 mol % at the lower limit and 40 mol % at the upper limit.

[0061] If the hydroxyl group content is 23 mol % or more, a polyvinyl acetal resin having high toughness can be obtained. If the hydroxyl group content is 40 mol % or less, the solubility in organic solvents can be sufficiently improved.

[0062] A more preferred lower limit of the amount of hydroxyl groups is 23 mol %, and a more preferred upper limit is 36 mol %.

[0063] The above hydroxyl amount can be 1 The measurement was performed by H-NMR.

[0064] The polyvinyl acetal resin may further have, in addition to the structural units of the above formulae (1), (2), and (3), a structural unit having a carboxyl group, a structural unit having a functional group such as a sulfonic acid group, an alkylene oxide group, or an amide group, and an ethylene unit.

[0065] Furthermore, the polyvinyl acetal resin preferably contains a structural unit having an acetal group, a structural unit having an acetyl group, a structural unit having a hydroxyl group, and a structural unit having an alkylene oxide group.

[0066] The polyvinyl acetal resin of the present invention preferably includes a structural unit having an alkylene oxide group.

[0067] Examples of the alkylene oxide group include a structure represented by the following formula (4).

[0068] [Chemical Formula 2]

[0069]

[0070] In formula (4), A 1 O is an oxyalkylene group having 2 to 6 carbon atoms, and m is an average number of repetitions, which is 10 to 200. 2 It is an alkyl group having 1 to 8 carbon atoms or a hydrogen atom. The oxyalkylene group may be a single type or a mixture of two or more types. * represents a bonding position to another group.

[0071] A 1 The oxyalkylene group in O is preferably an oxyalkylene group having 2 to 6 carbon atoms, more preferably an oxyalkylene group having 2 to 4 carbon atoms, and still more preferably an oxyalkylene group having 2 or 3 carbon atoms.

[0072] The alkylene group in the oxyalkylene group may be a straight chain or a branched structure. Examples of the oxyalkylene group include oxyethylene, oxypropylene, and oxybutylene, with oxyethylene and oxypropylene being preferred. One oxyalkylene group may be used alone or in combination of two or more.

[0073] The oxyalkylene group in the alkylene oxide group preferably contains at least one of an oxyethylene group and an oxypropylene group, and also preferably contains both an oxyethylene group and an oxypropylene group.

[0074] Furthermore, when the alkylene oxide group contains an ethylene oxide (EO) and a propylene oxide (PO), the molar ratio of the propylene oxide to the ethylene oxide (PO / EO) is preferably 1 / 49 or more and 49 / 1 or less, more preferably 1 / 9 or more and 9 / 1 or less, and even more preferably 2 / 8 or more and 8 / 2 or less.

[0075] The above R 2 The alkyl group in R can be a straight chain or a branched structure. 2 The alkyl group in includes: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl and other branched butyl groups, n-pentyl, branched pentyl, n-hexyl, branched hexyl, n-heptyl, isoheptyl, 3-heptyl and other branched heptyl groups, n-octyl, isooctyl, 2-ethylhexyl and other branched octyl groups, etc. The above R 2 The alkyl group may be any of an alkyl group and a hydrogen atom. The alkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms.

[0076] The above-mentioned alkylene oxide group is preferably connected to the main chain via a linking group.

[0077] Examples of the linking group include a single bond, an alkylene group having 1 to 10 carbon atoms, a carbonyl group, an ether bond (-O-), an ester bond (-COO-), an amide bond (-CONR-: R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms), and a hydrocarbon group which may have at least any one of these bonds.

[0078] The number of carbon atoms in the linking group is not particularly limited, but is preferably 10 or less, more preferably 4 or less. Furthermore, the linking group does not need to have carbon atoms; it may be 0 or more. Furthermore, R in -CONR- is preferably a hydrogen atom. Furthermore, the hydrocarbon group in the linking group preferably has 1 to 10 carbon atoms, more preferably 1 to 4 carbon atoms.

[0079] The alkylene oxide group is particularly preferably bonded via a single bond, an alkylene group having 1 to 10 carbon atoms, an ether bond, or -CH2O-. Bonding via such a linking group prevents significant changes in the polarity of the side chain and does not significantly affect solvent solubility. It should be noted that the oxygen atom in -CH2O- may be bonded to the alkylene oxide group.

[0080] It should be noted that, in the case of the structure of the following formula (5), the above-mentioned linking group refers to R 3 .

[0081] The structural unit having an alkylene oxide group preferably has a structural unit represented by the following formula (5), and particularly preferably a structural unit represented by the following formula (6) or a structural unit represented by the following formula (7).

[0082] [Chemical Formula 3]

[0083]

[0084] [Chemical Formula 4]

[0085]

[0086] In formula (5), A 1 O、R 2 , m are the same as above.

[0087] The above R 3 Examples thereof include a single bond, an ether bond (—O—), an ester bond (—COO—), an amide bond (—CONR—: R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms), and a hydrocarbon group which may have at least one of these bonds.

[0088] R in formula (5) 3 The number of carbon atoms in is preferably 0 to 10, more preferably 0 to 4. 3 An ether bond (—O—) or a hydrocarbon group having at least an ether bond is preferred.

[0089] In formulas (6) and (7), A 1 O、R 2 , m are the same as above.

[0090] It should be noted that A in formulas (5), (6), and (7) 1 O、R 2 , m are as described above, so their description is omitted.

[0091] The number of repeating units of the alkylene oxide group (average repeating number m) is preferably 2 or more and 100 or less, and more preferably 2 or more and 90 or less.

[0092] When the alkylene oxide group includes either an oxyethylene group or an oxypropylene group, m is preferably 2 to 75, more preferably 2 to 50. When the alkylene oxide group includes both an oxyethylene group and an oxypropylene group, m is preferably 2 to 75, more preferably 2 to 50.

[0093] The number of carbon atoms (total number of carbon atoms) of the alkylene oxide group is preferably 2 or more and 200 or less, more preferably 2 or more and 180 or less, and even more preferably 2 or more and 100 or less.

[0094] It should be noted that, in the case of the structure represented by the above formula (4), the above number of carbon atoms refers to the number of carbon atoms in the entire formula (4) including the linking group, and in the case of the structures represented by the above formulas (5) to (7), the above number of carbon atoms refers to the number of carbon atoms in the portion other than the main chain portion [-CH2-CH-].

[0095] In the polyvinyl acetal resin of the present invention, the content of the structural units having an alkylene oxide group is preferably 0.1 mol% or more and 5 mol% or less relative to the total polyvinyl acetal resin. If the content of the structural units having an alkylene oxide group is 0.1 mol% or more, adhesion can be imparted over a wide temperature range. If the content of the structural units having an alkylene oxide group is 5 mol% or less, high sheet strength can be maintained near room temperature.

[0096] The content of the structural unit having an alkylene oxide group is more preferably 0.2 mol % or more, further preferably 0.5 mol % or more, more preferably 4.5 mol % or less, further preferably 4.0 mol % or less.

[0097] The content of the structural unit having an alkylene oxide can be determined by 1 The measurement was performed by H-NMR.

[0098] Examples of the structural unit having a carboxyl group include a structural unit represented by the following formula (b-1), a structural unit represented by the following formula (b-2), and a structural unit represented by the following formula (b-3).

[0099] [Chemical Formula 5]

[0100]

[0101] In the above formula (b-1), R 1b and R 2b Each independently represents an alkylene group having 0 to 10 carbon atoms, X 1b and X 2b Each independently represents a hydrogen atom, a metal atom or a methyl group.

[0102] In the above formula (b-1), R 1b and R b2 The preferred lower limit of the number of carbon atoms in the alkylene group is 0, the preferred upper limit is 5, the more preferred lower limit is 1, and the more preferred upper limit is 3.

[0103] The above R 1b and R 2b They may be the same or different, but are preferably different. In addition, it is preferred that at least one of them is a single bond.

[0104] 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 cyclopropylene, cyclobutylene, and cyclohexylene. Among these, linear alkylene groups such as a single bond, methylene, ethylene, n-propylene, and n-butylene are preferred, and single bonds, methylene, and ethylene are more preferred.

[0105] In the above formula (b-1), X 1b and X 2b When at least any one of the is a metal atom, examples of the metal atom include a sodium atom, a lithium atom, and a potassium atom. Among them, a sodium atom is preferred.

[0106] The structural unit represented by formula (b-1) is preferably a structural unit derived from an α-dicarboxyl monomer. Examples of α-dicarboxyl monomers include dicarboxylic acids having a free-radically polymerizable unsaturated double bond, such as methylenemalonic acid, itaconic acid, 2-methyleneglutaric acid, 2-methyleneadipic acid, and 2-methylenedecanedioic acid, and their metal salts or methyl esters. Among these, itaconic acid, its metal salts, or its methyl ester are preferably used.

[0107] In addition, in this specification, an α-dicarboxyl monomer means a monomer having two carboxyl groups at the α-position carbon.

[0108] In the above formula (b-2), R 3b 、R 4b and R 5b Each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R 6b represents an alkylene group having 0 to 10 carbon atoms, X 3b represents a hydrogen atom, a metal atom or a methyl group.

[0109] In the above formula (b-2), R 3b 、R 4b and R 5b The preferred lower limit of the number of carbon atoms in the alkyl group is 1, the preferred upper limit is 5, and the more preferred upper limit is 3.

[0110] R 3b 、R 4b 、R 5b They may be the same or different, but are more preferably the same. 3b 、R 4b and R 5b Preferred is a hydrogen atom.

[0111] Examples of the alkyl group having 1 to 10 carbon atoms 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 these, linear alkyl groups such as methyl, ethyl, propyl, and n-butyl are preferred, and methyl and ethyl are more preferred.

[0112] As R in the above formula (b-2) 6b , which is the same as R in the above formula (b-1) 1b and R 2b The same groups as those exemplified above are preferred, among which single bonds, methylene, ethylene, trimethylene, tetramethylene and other linear alkylene groups are preferred, single bonds, methylene, ethylene are more preferred, and single bonds are further preferred.

[0113] In the above formula (b-2), X 3b In the case of a metal atom, examples of the metal atom include a sodium atom, a lithium atom, a potassium atom, etc. Among them, a sodium atom is preferred.

[0114] The structural unit represented by formula (b-2) is preferably derived from a monocarboxyl monomer. Examples of monocarboxyl monomers include monocarboxylic acids having a free-radically polymerizable unsaturated double bond, such as acrylic acid, crotonic acid, methacrylic acid, and oleic acid, and their metal salts or methyl esters. Among these, crotonic acid, its metal salts, or its methyl ester are preferably used.

[0115] In the above formula (b-3), R 7b and R 9b Each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R 8b and R 10b represents an alkylene group having 0 to 10 carbon atoms, X 4b and X 5b represents a hydrogen atom, a metal atom or a methyl group.

[0116] In the above formula (b-3), R 7b and R 9b The preferred lower limit of the number of carbon atoms in the alkyl group is 1, the preferred upper limit is 5, and the more preferred upper limit is 3.

[0117] The above R 7b and R 9b They may be the same or different, and are more preferably the same.

[0118] As R in the above formula (b-3) 7b and R 9b , which is the same as R in the above formula (b-2) 3b 、R 4b and R 5b The groups are the same as those exemplified above, and among them, a hydrogen atom is preferred.

[0119] As R in the above formula (b-3) 8b and R 10b , which is the same as R in the above formula (b-1) 1b and R 2b The same groups as those exemplified above are preferred, among which single bonds, methylene, ethylene, trimethylene, tetramethylene and other linear alkylene groups are preferred, single bonds, methylene, ethylene are more preferred, and single bonds are further preferred.

[0120] In the above formula (b-3), X 4b and X 5b In the case of a metal atom, examples of the metal atom include a sodium atom, a lithium atom, a potassium atom, etc. Among them, a sodium atom is preferred.

[0121] In the polyvinyl acetal resin, the content of the structural unit having a carboxyl group is preferably 0.1 mol % or more and 5.0 mol % or less relative to the total polyvinyl acetal resin, more preferably 0.5 mol % or more and more preferably 1.0 mol % or less.

[0122] The content of the structural unit having a carboxyl group can be determined by 1 The measurement was performed by H-NMR.

[0123] Examples of the structural unit having a sulfonic acid group include a structural unit represented by the following formula (c).

[0124] [Chemical Formula 6]

[0125]

[0126] In formula (c), R 1c represents an alkylene group having 0 to 10 carbon atoms, X 1c represents a hydrogen atom, a metal atom or a methyl group.

[0127] As R in the above formula (c) 1c , which is the same as R in the above formula (b-1) 1b and R 2b The same groups as those exemplified above are preferred, among which a single bond, a methylene group, an ethylene group, a trimethylene group, a tetramethylene group and the like are preferred, a single bond, a methylene group and an ethylene group are more preferred, and a single bond and a methylene group are further preferred.

[0128] In the above formula (c), X 1c In the case of a metal atom, examples of the metal atom include a sodium atom, a lithium atom, a potassium atom, etc. Among them, a sodium atom is preferred.

[0129] Examples of the structural unit having an amide group include a structural unit represented by the following formula (f).

[0130] [Chemical Formula 7]

[0131]

[0132] In the above formula (f), R 1f It represents an alkyl group having 1 to 10 carbon atoms.

[0133] As R in the above formula (f) 1f , which is the same as R in the above formula (b-2) 3b 、R 4b and R 5b The same groups as those exemplified above are preferred, among which a hydrogen atom, a methyl group, an ethyl group, a propyl group, a straight-chain alkyl group such as an n-butyl group is preferred, and a hydrogen atom, a methyl group, and an ethyl group are more preferred.

[0134] As the above-mentioned ethylene unit, a structural unit represented by the following formula (g) can be cited.

[0135] [Chemical formula 8]

[0136]

[0137] In the above-mentioned polyvinyl acetal resin, the content of the above-mentioned ethylene unit relative to the whole polyvinyl acetal resin (hereinafter, also referred to as "ethylene content") is preferably 0.1 mol% or more, more preferably 3 mol% or more, preferably 20 mol% or less, and more preferably 10 mol% or less. The above-mentioned ethylene content can be measured by, for example, 1 1H-NMR.

[0138] In addition, in this specification, the ethylene content of the polyvinyl acetal resin refers to the apparent ethylene content of the whole polyvinyl acetal resin. That is, for example, when the polyvinyl acetal resin contains a plurality of resins having different ethylene contents, the ethylene content of the polyvinyl acetal resin is obtained by summing up the values obtained by multiplying the ethylene content of each resin by the content ratio of the resin.

[0139] In the polyvinyl acetal resin of the present invention, the content of the structural units of the above formulas (1), (2), and (3) and the structural units having functional groups other than the structural units having epoxyalkyl groups relative to the whole polyvinyl acetal resin is preferably 0 mol% or more, more preferably 0.1 mol% or more, further preferably 0.5 mol% or more, preferably 5 mol% or less, and more preferably 3 mol% or less.

[0140] The content of the above-mentioned structural units having functional groups can be measured by 1 1H-NMR.

[0141] The lower limit of the preferred average degree of polymerization of the polyvinyl acetal resin of the present invention is 100, and the more preferred lower limit is 200. In addition, from the viewpoints of solubility and dissolution viscosity in an organic solvent, the upper limit is preferably 5000, and the more preferred upper limit is 4500.

[0142] It should be noted that the average degree of polymerization of the above-mentioned polyvinyl acetal resin is the same as that of the raw material polyvinyl alcohol. It should be noted that when the raw material polyvinyl alcohol contains two or more kinds of polyvinyl alcohols having different average degrees of polymerization, it can be calculated based on the mixed average degree of polymerization of the polyvinyl alcohol (the average degree of polymerization obtained by distributive calculation (Japanese original text: 案分) according to the mixing ratio). In addition, the above-mentioned average degree of polymerization can be measured according to JIS K 6726.

[0143] The polyvinyl acetal resin of the present invention preferably has a Z average molecular weight Mz of 2,000,000 or less. By setting it within the above range, solvent solubility is improved.

[0144] The Mz is more preferably 100,000 or more, further preferably 200,000 or more, more preferably 1,800,000 or less, further preferably 1,500,000 or less.

[0145] The Mz can be measured by gel permeation chromatography (GPC) using N-methylpyrrolidone as a solvent and using appropriate standards (eg, polystyrene standards).

[0146] The shape of the polyvinyl acetal resin of the present invention is not particularly limited, and may be a particle shape, a plate shape, a liquid shape, or the like. Among them, a particle shape is preferred.

[0147] When the polyvinyl acetal resin of the present invention is in the form of particles, the average particle size is preferably 10 μm or more and preferably 1000 μm or less. By setting the particle size within the above range, high dispersibility can be obtained.

[0148] The average particle size is more preferably 50 μm or larger, and more preferably 500 μm or smaller.

[0149] The average particle size refers to a secondary particle size, and can be measured using, for example, a laser diffraction particle size analyzer (Mastersizer 3000, manufactured by Malvern Panalytical).

[0150] The polyvinyl acetal resin of the present invention can generally be produced by acetalizing a polyvinyl alcohol resin.

[0151] In particular, methods for producing the polyvinyl acetal resin include a method of mixing the polyvinyl alcohol resin having a structural unit containing an alkylene oxide group with the polyvinyl alcohol resin not having a structural unit containing an alkylene oxide group, followed by acetalization. Alternatively, methods include preparing the polyvinyl alcohol resin having a structural unit containing an alkylene oxide group and then acetalizing the mixture.

[0152] In addition, when the above-mentioned polyvinyl alcohol resin having a structural unit containing an alkylene oxide is mixed with the above-mentioned polyvinyl alcohol resin not having a structural unit containing an alkylene oxide, the mixing ratio of the two is preferably 1 / 49 to 49 / 1 for the polyvinyl alcohol resin having a structural unit containing an alkylene oxide: the polyvinyl alcohol resin not having a structural unit containing an alkylene oxide.

[0153] Examples of methods for producing the polyvinyl alcohol resin having structural units containing an alkylene oxide group include copolymerizing an alkylene oxide-containing monomer with a vinyl ester such as vinyl acetate, followed by saponification by adding an acid or base to an alcohol solution of the resulting copolymer. More specifically, examples include copolymerizing an alkylene oxide-containing hydroxyalkyl vinyl ether with vinyl acetate, followed by saponification by adding an acid or base to an alcohol solution of the resulting copolymer. In addition to the aforementioned hydroxyalkyl vinyl ethers, poly(alkylene glycol) vinyl ethers such as dialkylene glycol vinyl ether and trialkylene glycol monovinyl ether may also be used.

[0154] In addition, examples of a method for adding the moiety represented by the above formula (4) include a method of changing the type of the above alkyl vinyl ether.

[0155] The polyvinyl alcohol having a structural unit containing an alkylene oxide preferably has a saponification degree of 80.0 to 99.9 mol%. By setting it within this range, both the obtained flexibility and solvent resistance can be achieved. A more preferred lower limit of the saponification degree is 85.0 mol%, an even more preferred lower limit is 88.0 mol%, a more preferred upper limit is 99.8 mol%, an even more preferred upper limit is 99.7 mol%, and a particularly preferred upper limit is 99.5 mol%.

[0156] As the polyvinyl alcohol resin, for example, a conventionally known polyvinyl alcohol resin such as a resin produced by saponifying a polyvinyl acetate-based resin with an alkali, an acid, or aqueous ammonia can be used.

[0157] The polyvinyl alcohol resin may be fully saponified, but may be partially saponified if it contains at least one unit having a dilinked hydroxyl group (Japanese: 2-linked hydrocarbyl group) at the meso or racemic position at at least one position in the main chain. Furthermore, copolymers of vinyl alcohol with monomers copolymerizable with vinyl alcohol, such as ethylene-vinyl alcohol copolymer resins and partially saponified ethylene-vinyl alcohol copolymer resins, may also be used as the polyvinyl alcohol resin.

[0158] Examples of the polyvinyl acetate-based resin include ethylene-vinyl acetate copolymers.

[0159] The polyvinyl alcohol resin preferably has a saponification degree of 80.0 to 99.9 mol %. The more preferred lower limit of the saponification degree is 85.0 mol %, an even more preferred lower limit is 88.0 mol %, an even more preferred upper limit is 99.8 mol %, an even more preferred upper limit is 99.7 mol %, and an especially preferred upper limit is 99.5 mol %.

[0160] The acetalization is preferably carried out in an aqueous solvent, a mixed solvent of water and an organic solvent compatible with water, or an organic solvent.

[0161] As the organic solvent compatible with water, for example, an alcohol-based organic solvent can be used.

[0162] Examples of the organic solvent include alcohol-based organic solvents, aromatic organic solvents, aliphatic ester-based solvents, ketone-based solvents, lower alkane-based solvents, ether-based solvents, amide-based solvents, and amine-based solvents.

[0163] Examples of the alcohol-based organic solvent include methanol, ethanol, n-propanol, isopropanol, n-butanol, and tert-butanol.

[0164] Examples of the aromatic organic solvent include xylene, toluene, ethylbenzene, and methyl benzoate.

[0165] Examples of the aliphatic ester solvent include methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, methyl acetoacetate, and ethyl acetoacetate.

[0166] Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methylcyclohexanone, benzophenone, and acetophenone.

[0167] Examples of the lower alkane solvent include hexane, pentane, octane, cyclohexane, and decane.

[0168] Examples of the ether solvent include diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol diethyl ether.

[0169] Examples of the amide solvent include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and acetanilide.

[0170] Examples of the amine solvent include ammonia, trimethylamine, triethylamine, n-butylamine, di-n-butylamine, tri-n-butylamine, aniline, N-methylaniline, N,N-dimethylaniline, and pyridine.

[0171] These solvents may be used as a single component (Japanese original text: monomer) or as a mixture of two or more. Among these solvents, ethanol, n-propanol, isopropanol, and tetrahydrofuran are particularly preferred from the viewpoint of solubility in the resin and ease of purification.

[0172] The acetalization is preferably carried out in the presence of an acid catalyst.

[0173] The acid catalyst is not particularly limited, and examples thereof include mineral acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid; carboxylic acids such as formic acid, acetic acid, and propionic acid; and sulfonic acids such as methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid. These acid catalysts may be used alone or in combination of two or more. Among these, hydrochloric acid, nitric acid, and sulfuric acid are preferred, with hydrochloric acid being particularly preferred.

[0174] Examples of the aldehyde used in the acetalization reaction include aldehydes having a chain aliphatic group, a cyclic aliphatic group, or an aromatic group having 1 to 10 carbon atoms. Conventionally known aldehydes can be used as these aldehydes. The aldehyde used in the acetalization reaction is not particularly limited, and examples thereof include aliphatic aldehydes and aromatic aldehydes.

[0175] Examples of the aliphatic aldehydes include formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, n-hexanal, 2-ethylbutyraldehyde, 2-ethylhexanal, n-heptylaldehyde, n-octanal, n-nonylaldehyde, n-decanal, and valeraldehyde.

[0176] Examples of the aromatic aldehyde include benzaldehyde, cinnamaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, and β-phenylpropionaldehyde.

[0177] These aldehydes may be used alone or in combination of two or more. Among these aldehydes, formaldehyde, acetaldehyde, butyraldehyde, 2-ethylhexanal, and n-nonanal are preferred, as they exhibit excellent acetalization reactivity, can provide a sufficient internal plasticizing effect on the resulting resin, and can consequently impart good flexibility. Furthermore, formaldehyde, acetaldehyde, and butyraldehyde are more preferred, as they can produce an adhesive composition with particularly excellent impact resistance and adhesion to metals.

[0178] The amount of the aldehyde added can be appropriately set depending on the desired acetal group content of the polyvinyl acetal resin. In particular, a range of preferably 55 mol% to 95 mol%, and more preferably 60 mol% to 90 mol%, relative to 100 mol% of the polyvinyl alcohol, is preferred because the acetalization reaction proceeds efficiently and unreacted aldehyde is easily removed. Specifically, the amount of the aldehyde added is preferably 55 to 95 mol%, and more preferably 60 to 90 mol%.

[0179] The temperature when adding the aldehyde (aldehyde charging temperature) is preferably 0°C or higher, more preferably 10°C or higher, and preferably 55°C or lower, more preferably 50°C or lower. In other words, the aldehyde charging temperature is preferably 0-55°C, more preferably 10-50°C.

[0180] During the acetalization reaction, a hydrolysis step using hydrochloric acid or a saponification step using sodium hydroxide is preferably performed before the acetalization reaction. Hydrolysis using hydrochloric acid is preferred. For example, the hydrolysis step using hydrochloric acid involves heating and dissolving polyvinyl alcohol in water, then adding hydrochloric acid and heating and stirring for a predetermined period of time to hydrolyze the acetyl groups contained in the polyvinyl alcohol into hydroxyl groups. The hydrolysis temperature, hydrolysis time, and amount of hydrochloric acid can be adjusted appropriately based on the saponification degree of the starting polyvinyl alcohol and the target saponification degree after hydrolysis.

[0181] The hydrolysis temperature is preferably 50°C or higher and preferably 90°C or lower. The hydrolysis time is preferably 30 minutes or longer and preferably 10 hours or shorter. Specifically, the hydrolysis time is preferably 30 minutes to 10 hours. The amount of hydrochloric acid is preferably 10 parts by weight or higher and preferably 250 parts by weight or lower per 100 parts by weight of polyvinyl alcohol. Specifically, the amount of hydrochloric acid is preferably 10 to 250 parts by weight per 100 parts by weight of polyvinyl alcohol.

[0182] The acetalization reaction is preferably carried out after heating and dissolving the polyvinyl alcohol and then cooling. The temperature for heating and dissolving the polyvinyl alcohol is preferably 80°C or higher, more preferably 90°C or higher, and preferably 99°C or lower. The dissolution time is preferably 1 to 8 hours. The cooling temperature is preferably 50 to 0°C.

[0183] In the acetalization reaction, it is preferred that the aldehyde be added at a predetermined temperature and then maintained at the predetermined temperature for a predetermined period of time.

[0184] The holding time in the acetalization reaction is preferably 0.1 to 7 hours, more preferably 0.5 to 5 hours. That is, the holding time is preferably 0.1 to 7 hours, more preferably 0.5 to 5 hours.

[0185] The holding temperature in the acetalization reaction is preferably -5°C to 50°C, more preferably 5°C to 40°C. That is, the holding temperature is preferably -5 to 50°C, more preferably 5 to 40°C.

[0186] The acetalization reaction can be carried out by adding aldehyde at a predetermined temperature and then cooling the temperature at a predetermined cooling rate, or by heating the temperature at a predetermined heating rate and then maintaining the temperature at a predetermined temperature for a predetermined period of time.

[0187] The temperature drop time or temperature rise time in the acetalization reaction is preferably 30 minutes to 600 minutes, more preferably 60 minutes to 500 minutes, and even more preferably 120 minutes to 400 minutes. Specifically, the temperature drop time or temperature rise time is preferably 30 to 600 minutes, more preferably 60 to 500 minutes, and even more preferably 120 to 400 minutes.

[0188] The temperature drop rate or temperature increase rate is preferably 0.1° C. / minute or higher and 2° C. / minute or lower. In other words, the temperature drop rate or temperature increase rate is preferably 0.1 to 2° C. / minute.

[0189] When the step of maintaining the mixture at a predetermined temperature for a predetermined time (aging step) is performed after the temperature decrease or increase, the maintaining temperature is preferably 20 to 70° C., and the maintaining time is preferably 1 to 8 hours.

[0190] In addition, regarding the neutralization after the acetalization reaction, it is preferable to use a method (continuous neutralization method) in which a neutralizing agent is directly added without isolating the reaction solution used in the acetalization reaction.

[0191] A slurry composition for ceramic green sheets can be prepared by mixing an organic solvent and ceramic powder with the polyvinyl acetal resin of the present invention.

[0192] The organic solvent is not particularly limited. For example, any solvent capable of dissolving the polyvinyl acetal resin is not particularly limited. Examples include ketones such as acetone, methyl ethyl ketone, dipropyl ketone, and diisobutyl ketone. Examples include alcohols such as methanol, ethanol, isopropyl alcohol, and butanol, and aromatic hydrocarbons such as toluene and xylene. Examples include esters such as methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, methyl valerate, ethyl valerate, butyl valerate, methyl hexanoate, ethyl hexanoate, butyl hexanoate, 2-ethylhexyl acetate, and 2-ethylhexyl butyrate. Examples include methyl cellosolve, ethyl cellosolve, butyl cellosolve, terpineol, dihydroterpineol, butyl cellosolve acetate, butyl carbitol acetate, terpineol acetate, and dihydroterpineol acetate. In particular, alcohols, ketones, aromatic hydrocarbons, and mixed solvents thereof are preferred from the viewpoint of coating properties and drying properties. Among them, mixed solvents of ethanol and toluene and mixed solvents of methyl ethyl ketone and toluene are more preferred.

[0193] The content of the organic solvent in the ceramic green sheet slurry composition is set according to the type of polyvinyl acetal resin used, etc., and is not particularly limited. If it is too little, it is difficult to exert the solubility required for kneading. In addition, if it is too much, the viscosity of the ceramic green sheet slurry composition sometimes becomes too low, and the handling properties during the production of ceramic green sheets deteriorate. Therefore, the content of the organic solvent is preferably 20% by weight or more and 80% by weight or less. That is, the content of the organic solvent is preferably 20 to 80% by weight.

[0194] As the above-mentioned ceramic powder, the powder of the oxide or non-oxide of the metal or non-metal used in the manufacture of ceramics can be mentioned. In addition, the composition of these powders can be a single composition, and the powder in the compound state can also be used alone or in combination. It should be noted that, with regard to the constituent elements of the oxide or non-oxide of the metal, the cation or anion can be formed by a single element, can also be formed by multiple elements, and can also include additives added to improve the properties of the oxide or non-oxide. Specifically, the oxides, carbides, nitrides, borides, sulfides, etc. of Li, K, Mg, B, Al, Si, Cu, Ca, Sr, Ba, Zn, Cd, Ga, In, Y, lanthanides, actinides, Ti, Zr, Hf, Bi, V, Nb, Ta, W, Mn, Fe, Co, Ni, etc. can be mentioned.

[0195] Furthermore, if specific substances of oxide powders containing multiple metal elements, generally referred to as composite oxides, are classified according to their crystal structures, substances having a perovskite structure include NaNbO3, SrZrO3, PbZrO3, SrTiO3, BaZrO3, PbTiO3, and BaTiO3. Substances having a spinel structure include MgAl2O4, ZnAl2O4, CoAl2O4, NiAl2O4, and MgFe2O4. Substances having an ilmenite structure include MgTiO3, MnTiO3, and FeTiO3. Substances having a garnet structure include GdGa5O4, and others. 12 、Y6Fe5O 12 Among them, the modified polyvinyl acetal resin of the present application exhibits high properties relative to the ceramic green sheet obtained by mixing it with BaTiO3 powder.

[0196] The slurry composition for ceramic green sheets may contain a plasticizer. By adding a plasticizer, the mechanical strength and flexibility of the resulting ceramic green sheets can be significantly improved.

[0197] Examples of the plasticizer include phthalic acid diesters such as dioctyl phthalate (DOP) and dibutyl phthalate (DBP), adipate diesters such as dioctyl adipate, and 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.

[0198] The average particle size of the ceramic powder is not particularly limited, but is preferably 0.5 μm or less for, for example, production of thin-layer ceramic green sheets (thickness 5 μm or less).

[0199] In the slurry composition for ceramic green sheets, the plasticizer content is preferably in the range of 7 parts by weight, more preferably 8.5 parts by weight, per 100 parts by weight of the polyvinyl acetal resin. The plasticizer content is preferably in the range of 40 parts by weight, more preferably 30 parts by weight. Specifically, the plasticizer content is preferably in the range of 7 to 40 parts by weight, more preferably 8.5 to 30 parts by weight.

[0200] The ceramic green sheet slurry composition may contain other resins, such as a polyvinyl acetal resin, an acrylic resin, and ethyl cellulose, in addition to the polyvinyl acetal resin of the present invention, within a range that does not impair the effects of the present invention. In this case, the content of the polyvinyl acetal resin of the present invention is preferably 50% by weight or more relative to the total binder resin.

[0201] The slurry composition for ceramic green sheets may be appropriately added with dispersants, antioxidants, ultraviolet absorbers, surfactants, fillers, release agents, etc. as needed. Other resins such as acrylic resins and urethane resins may also be added in small amounts as needed.

[0202] The method for producing the slurry composition for ceramic green sheets is not particularly limited. Examples thereof include a method of mixing the polyvinyl acetal resin of the present invention, an organic solvent, ceramic powder, and various additives as needed using various mixers such as a ball mill, a mixing mill, and a three-roll mill.

[0203] After the slurry composition for ceramic green sheets is applied, it is dried by heating to obtain ceramic green sheets. A ceramic green sheet formed using the slurry composition for ceramic green sheets of the present invention is also one aspect of the present invention.

[0204] Ceramic electronic components can be manufactured using the above-described ceramic green sheets. For example, the ceramic electronic components can be manufactured by applying an electrode layer paste to the surface of the ceramic green sheets, and then degreasing and firing the resulting stack of ceramic green sheets with the electrode layers formed thereon.

[0205] The method for applying the slurry composition for ceramic green sheets is not particularly limited, and examples thereof include methods using a roll coater, a die coater, a curtain coater, etc. Regarding other specific methods, conventionally known methods can be used.

[0206] The ceramic electronic components are not particularly limited, and examples thereof include multilayer ceramic capacitors, multilayer ceramic inductors, capacitors, piezoelectric actuators, multilayer varistors, multilayer thermistors, EMI filters, aluminum nitride multilayer substrates, and alumina multilayer substrates. A multilayer ceramic capacitor obtained using the ceramic green sheet of the present invention is also an aspect of the present invention.

[0207] In the method for producing a ceramic electronic component, a step of applying an electrode layer paste to the surface of the ceramic green sheet is performed.

[0208] The electrode layer paste can be obtained, for example, by dissolving a binder resin such as polyvinyl acetal resin, ethyl cellulose, or acrylic resin in an organic solvent and dispersing a conductive powder. These resins can be used alone or in combination of two or more. Electrode layer pastes containing polyvinyl acetal resin are preferred because they exhibit excellent adhesion to ceramic green sheets during the hot pressing step.

[0209] In the above-mentioned method for manufacturing ceramic electronic components, after the above-mentioned ceramic green sheets with electrode layers are produced, the laminated body obtained by stacking and heat-pressing the ceramic green sheets with electrode layers produced in the same manner is degreased and fired, thereby obtaining a laminated ceramic electronic component that solves problems such as sheet erosion (Japanese original: シートアタック) and cracking.

[0210] Note that the heat-compression bonding step and the steps of degreasing and firing the laminate are not particularly limited, and conventionally known methods can be used.

[0211] Effects of the Invention

[0212] The present invention provides a polyvinyl acetal resin having excellent adhesion over a wide temperature range and capable of producing a high-strength ceramic green sheet; a slurry composition for a ceramic green sheet using the polyvinyl acetal resin; a ceramic green sheet; and a multilayer ceramic capacitor.

[0213] Furthermore, the present invention can provide a polyvinyl acetal resin having excellent storage stability and high sheet corrosion resistance, as well as a slurry for ceramic green sheets and a ceramic green sheet using the polyvinyl acetal resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0214] Figure 1 This is a peak curve of tan δ when the dynamic viscoelasticity of the polyvinyl acetal resin of the present invention is measured under the conditions of a temperature range of 30° C. to 150° C., a heating rate of 6° C. / min, and a frequency of 1 Hz. DETAILED DESCRIPTION

[0215] The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples. The details of the raw material PVA used in the Examples and Comparative Examples are shown in Table 1.

[0216] (Example 1)

[0217] (Preparation of alkylene oxide-modified polyvinyl acetal resin)

[0218] As the raw material PVA, a structural unit represented by formula (5) is used (where A 1 O is ethylene oxide (EO), R 2 is a hydrogen atom, R 3 The following materials were used: an alkylene oxide-modified polyvinyl alcohol resin (AO-modified PVA-1, average degree of polymerization 600, degree of saponification 99.0 mol %) (where m is a single bond and m is 9.5), an unmodified polyvinyl alcohol (unmodified PVA-1, average degree of polymerization 1700, degree of saponification 99.0 mol %), and an unmodified polyvinyl alcohol (unmodified PVA-2, average degree of polymerization 3300, degree of saponification 99.0 mol %). It should be noted that when two or more raw material PVAs with different average degrees of polymerization were used, the average degree of polymerization calculated by multiplying the content ratio by the respective degrees of polymerization was used as the polymerization degree.

[0219] Table 1 shows the details of the raw material PVA used in each example and comparative example.

[0220] 2800 g of pure water was added to 90 g (30 parts by weight) of AO-modified PVA-1, 75 g (25 parts by weight) of unmodified PVA-1, and 135 g (45 parts by weight) of unmodified PVA-2. The mixture was stirred at 90°C for 2 hours to dissolve the mixture. The solution was cooled to 40°C, and 300 g of 35% by weight hydrochloric acid and 160 g of n-butyraldehyde were added. An acetalization reaction was carried out for 1 hour to precipitate the reaction product. The mixture was then cooled to 30°C over 60 minutes (at a cooling rate of 0.167°C / minute) and maintained at 30°C for 4 hours to complete the reaction. Sodium bicarbonate was added as a neutralizing agent without separation, and the mixture was then washed and dried using conventional methods to obtain an alkylene oxide-modified polyvinyl acetal resin. Ion-exchanged water was used for dissolution and washing.

[0221] The obtained alkylene oxide-modified polyvinyl acetal resin was analyzed using an AV400 spectrometer (manufactured by Bruker). 1 H-NMR was used to measure the amount of acetal groups, acetyl groups, hydroxyl groups, and alkylene oxide groups (content of structural units containing alkylene oxide, AO modification amount). It should be noted that the obtained alkylene oxide-modified polyvinyl acetal resin was dissolved in DMSO-D6 to a concentration of 1.6 wt % to prepare a measurement solution. 1 H-NMR measurement was performed at 80°C.

[0222] Furthermore, the average particle size (secondary particle size) of the obtained alkylene oxide-modified polyvinyl acetal resin was measured using a laser diffraction particle size analyzer (Mastersizer 3000, manufactured by Malvern Panalytical) and found to be 215 μm.

[0223] (Example 2)

[0224] AO-modified PVA-1 and unmodified polyvinyl alcohol (unmodified PVA-3, average degree of polymerization 2400, degree of saponification 99.0 mol %) were used as the PVA raw materials. 2800 g of pure water was added to 150 g (50 parts by weight) of AO-modified PVA-1 and 150 g (50 parts by weight) of unmodified PVA-3, and the mixture was stirred at 90°C for 2 hours to dissolve. An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1.

[0225] (Example 3)

[0226] As raw material PVA, AO-modified PVA-1 and unmodified PVA-3 were used.

[0227] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 180 g (60 parts by weight) of AO-modified PVA-1 and 120 g (40 parts by weight) of unmodified PVA-3 and the mixture was stirred at 90° C. for 2 hours for dissolution.

[0228] (Example 4)

[0229] As raw material PVA, AO-modified PVA-1 and unmodified PVA-2 were used.

[0230] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 120 g (40 parts by weight) of AO-modified PVA-1 and 180 g (60 parts by weight) of unmodified PVA-2 and the mixture was stirred at 90°C for 2 hours for dissolution.

[0231] (Example 5)

[0232] As raw material PVA, AO-modified PVA-1 and unmodified polyvinyl alcohol (unmodified PVA-4, average polymerization degree 500, saponification degree 99.0 mol %) were used.

[0233] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 150 g (50 parts by weight) of AO-modified PVA-1 and 150 g (50 parts by weight) of unmodified PVA-4 and the mixture was stirred at 90°C for 2 hours for dissolution.

[0234] (Comparative Example 1)

[0235] As the raw material PVA, AO-modified PVA-1 was used.

[0236] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 300 g (100 parts by weight) of AO-modified PVA-1 and the mixture was stirred at 90° C. for 2 hours for dissolution.

[0237] (Comparative Example 2)

[0238] As the raw material PVA, unmodified PVA-1 was used.

[0239] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 300 g (100 parts by weight) of unmodified PVA-1 and the mixture was stirred at 90° C. for 2 hours for dissolution.

[0240] (Comparative Example 3)

[0241] As the raw material PVA, unmodified PVA-4 was used.

[0242] 2800 g of pure water was added to 300 g (100 parts by weight) of unmodified PVA-4 and stirred at 90°C for 2 hours to dissolve it. The solution was cooled to 40°C, and 300 g of 35% by weight hydrochloric acid, 150 g of acetaldehyde, and 10 g of n-butyraldehyde were added to carry out an acetalization reaction, resulting in precipitation of the reaction product. The reaction was then maintained at 30°C for 4 hours to complete the reaction. The mixture was then neutralized, washed with water, and dried using conventional methods to obtain an alkylene oxide-modified polyvinyl acetal resin. Ion-exchanged water was used for dissolution and washing.

[0243] (Comparative Example 4)

[0244] As the raw material PVA, unmodified polyvinyl alcohol (unmodified PVA-5, average degree of polymerization 1700, degree of saponification 88.0 mol %) was used.

[0245] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 300 g (100 parts by weight) of unmodified PVA-5 and the mixture was stirred at 90° C. for 2 hours for dissolution.

[0246] (Example 6)

[0247] As raw material PVA, AO-modified PVA-1 and unmodified polyvinyl alcohol (unmodified PVA-6, average polymerization degree 4000, saponification degree 99.0 mol %) were used.

[0248] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 60 g (20 parts by weight) of AO-modified PVA-1 and 240 g (80 parts by weight) of unmodified PVA-6 and the mixture was stirred at 90°C for 2 hours for dissolution.

[0249] (Example 7)

[0250] As raw material PVA, AO-modified PVA-1 and unmodified PVA-6 were used.

[0251] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 240 g (80 parts by weight) of AO-modified PVA-1 and 60 g (20 parts by weight) of unmodified PVA-6 and the mixture was stirred at 90°C for 2 hours for dissolution.

[0252] (Example 8)

[0253] As raw material PVA, AO-modified PVA-1 and unmodified PVA-3 were used.

[0254] To 150 g (50 parts by weight) of AO-modified PVA-1 and 150 g (50 parts by weight) of unmodified PVA-3, 2800 g of pure water was added and dissolved by stirring at 90°C for 2 hours. The solution was cooled to 40°C, and 300 g of 35% by weight hydrochloric acid, 80 g of acetaldehyde, and 80 g of n-butyraldehyde were added to carry out an acetalization reaction, thereby precipitating the reaction product. An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that the above procedures were repeated.

[0255] In addition, the ratio of the amount of butyral groups to the amount of acetal groups in the alkylene oxide-modified polyvinyl acetal resin [amount of acetal groups / amount of butyral groups] is described in Table 2 as "acetal / butyl ratio".

[0256] (Example 9)

[0257] As raw material PVA, AO-modified PVA-1 and unmodified PVA-3 were used.

[0258] To 150 g (50 parts by weight) of AO-modified PVA-1 and 150 g (50 parts by weight) of unmodified PVA-3, 2800 g of pure water was added and dissolved by stirring at 90°C for 2 hours. The solution was cooled to 40°C, and 300 g of 35% by weight hydrochloric acid and 135 g of n-butyraldehyde were added to carry out an acetalization reaction, thereby precipitating the reaction product. An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that the above procedures were repeated.

[0259] (Example 10)

[0260] As the raw material PVA, a structural unit represented by formula (5) is used (where A 1 O is ethylene oxide (EO), R 2 is a hydrogen atom, R 3is a single bond, m is 34.5) alkylene oxide-modified polyvinyl alcohol resin (AO-modified PVA-2, average polymerization degree 1300, saponification degree 99.0 mol %) and unmodified PVA-3.

[0261] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 150 g (50 parts by weight) of AO-modified PVA-2 and 150 g (50 parts by weight) of unmodified PVA-3 and the mixture was stirred at 90°C for 2 hours for dissolution.

[0262] (Example 11)

[0263] As the raw material PVA, a structural unit represented by formula (6) is used (where A 1 O is ethylene oxide (EO), R 2 is a hydrogen atom, R 3 is a single bond, m is 49.5) alkylene oxide-modified polyvinyl alcohol resin (AO-modified PVA-3, average polymerization degree 800, saponification degree 99.0 mol %) and unmodified PVA-3.

[0264] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 150 g (50 parts by weight) of AO-modified PVA-3 and 150 g (50 parts by weight) of unmodified PVA-3 and the mixture was stirred at 90° C. for 2 hours for dissolution.

[0265] (Example 12)

[0266] As the raw material PVA, a structural unit represented by formula (6) is used (where A 1 O is ethylene oxide (EO), R 2 is a hydrogen atom, R 3 is a single bond, m is 4.5) alkylene oxide-modified polyvinyl alcohol resin (AO-modified PVA-4, average polymerization degree 600, saponification degree 99.0 mol %) and unmodified PVA-3.

[0267] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 150 g (50 parts by weight) of AO-modified PVA-4 and 150 g (50 parts by weight) of unmodified PVA-3 and the mixture was stirred at 90° C. for 2 hours for dissolution.

[0268] (Example 13)

[0269] As the raw material PVA, a structural unit represented by formula (5) is used (where A 1 O is ethylene oxide (EO) and propylene oxide (PO) [PO / EO ratio = 1 / 1], R2 is a hydrogen atom, R 3 is a single bond, m is 49.5) alkylene oxide-modified polyvinyl alcohol resin (AO-modified PVA-5, average polymerization degree 1300, saponification degree 99.0 mol %) and unmodified PVA-3.

[0270] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 150 g (50 parts by weight) of AO-modified PVA-5 and 150 g (50 parts by weight) of unmodified PVA-3 and the mixture was stirred at 90°C for 2 hours for dissolution.

[0271] (Comparative Example 5)

[0272] As the raw material PVA, unmodified PVA-3 was used.

[0273] To 300 g (100 parts by weight) of unmodified PVA-3, 2800 g of pure water was added and dissolved by stirring at 90°C for 2 hours. The solution was cooled to 40°C, and 300 g of 35% by weight hydrochloric acid, 80 g of acetaldehyde, and 80 g of n-butyraldehyde were added to initiate an acetalization reaction, resulting in precipitation of the reaction product. The reaction was then maintained at 30°C for 4 hours to complete the reaction. The mixture was then neutralized, washed with water, and dried using conventional methods to obtain an alkylene oxide-modified polyvinyl acetal resin. Ion-exchanged water was used for dissolution and washing.

[0274] (Comparative Example 6)

[0275] As the raw material PVA, AO-modified PVA-1 and unmodified PVA-1 were used.

[0276] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 3 g (1 part by weight) of AO-modified PVA-1 and 297 g (99 parts by weight) of unmodified PVA-1 and the mixture was stirred at 90° C. for 2 hours for dissolution.

[0277] (Comparative Example 7)

[0278] As the raw material PVA, AO-modified PVA-2 was used.

[0279] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 300 g (100 parts by weight) of AO-modified PVA-2 and the mixture was stirred at 90° C. for 2 hours for dissolution.

[0280] (Comparative Example 8)

[0281] As the raw material PVA, AO-modified PVA-3 was used.

[0282] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 300 g (100 parts by weight) of AO-modified PVA-3 and the mixture was stirred at 90° C. for 2 hours for dissolution.

[0283] (Comparative Example 9)

[0284] As the raw material PVA, AO-modified PVA-4 was used.

[0285] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 300 g (100 parts by weight) of AO-modified PVA-4 and the mixture was stirred at 90° C. for 2 hours for dissolution.

[0286] (Comparative Example 10)

[0287] As the raw material PVA, AO-modified PVA-5 was used.

[0288] An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1 except that 2800 g of pure water was added to 300 g (100 parts by weight) of AO-modified PVA-5 and the mixture was stirred at 90° C. for 2 hours for dissolution.

[0289] (evaluate)

[0290] The following evaluations were performed on the polyvinyl acetal resins obtained in Examples and Comparative Examples. The results are shown in Table 2.

[0291] (1) Evaluation of polyvinyl acetal resin

[0292] (1-1) Tanδ evaluation

[0293] The obtained polyvinyl acetal resin was applied onto a release-treated PET film using a coater so as to have a thickness of about 5 to 20 μm after drying, and then heated and dried at 70° C. for 180 minutes to produce a transparent resin sheet.

[0294] The obtained resin sheet was cut into 0.5 cm×3.0 cm test pieces to prepare the test pieces, and the dynamic viscoelasticity was measured using DMA (manufactured by IT Measurement Co., Ltd.) under the following conditions. The obtained tan δ (loss tangent) was measured for the peak top temperature and half-value width.

[0295] In addition, the storage modulus E' at 60°C was measured from the dynamic viscoelasticity measured under the following conditions.

[0296] (Measurement conditions)

[0297] Measurement mode: Tensile mode

[0298] Forced vibration frequency: 1Hz

[0299] Temperature range: 30℃~150℃

[0300] Heating rate: 6℃ / min

[0301] Length between fixtures: 2.0cm

[0302] Strain: 0.08%

[0303] (1-2) Z-average molecular weight determination

[0304] The obtained polyvinyl acetal resin was dissolved in N-methylpyrrolidone (NMP) at a concentration of 0.2% by weight and passed through a PTFE filter with a pore size of 0.45 μm. GPC was performed using a GPC-101 (Shodex Corporation) apparatus, NMP as the mobile phase, an RI-715 differential refractive index detector (Shodex Corporation) as the detector, and an LF-804 (Shodex Corporation) column. Measurements were performed at a flow rate of 0.5 mL / min. The obtained measurement results were calibrated using a molecular weight calibration curve prepared using monodisperse polystyrene standard samples to obtain the Z-average molecular weight (NMP).

[0305] (2) Performance evaluation

[0306] (2-1) Tensile strength measurement

[0307] The obtained polyvinyl acetal resin was applied onto a release-treated PET film using a coater so as to have a thickness of about 5 to 20 μm after drying, and then heated and dried at 70° C. for 180 minutes to produce a transparent resin sheet.

[0308] The resulting resin sheet was measured for breaking stress (MPa) in accordance with JIS K 7113 using a tensile testing machine (Autograph AGS-J, manufactured by Shimadzu Corporation) at 30°C and a tensile speed of 20 mm / min. The resulting breaking stress was evaluated according to the following criteria.

[0309] AA: fracture stress exceeds 75MPa

[0310] A: Breaking stress is more than 50 MPa and less than 75 MPa

[0311] B: Breaking stress exceeds 25 MPa and is 50 MPa or less

[0312] C: Breaking stress is 25 MPa or less

[0313] (2-2) Adhesion evaluation

[0314] The obtained polyvinyl acetal resin was applied onto a release-treated PET film using a coater so as to have a thickness of about 5 to 20 μm after drying, and then heated and dried at 70° C. for 180 minutes to produce a transparent resin sheet.

[0315] The resulting resin sheet was cut into 1.0 cm x 1.0 cm test pieces to prepare them. The initial tack (peak value) was measured using a tack tester (manufactured by RHESCA) under the following conditions. The peak values ​​were evaluated according to the following criteria (measurement temperatures of 50°C, 60°C, and 70°C).

[0316] (Measurement conditions)

[0317] Pressing speed: 5.0mm / s

[0318] Compression load: 98gf, 0.05MPa

[0319] Press and hold time: 10s

[0320] Pulling speed: 5.0mm / s

[0321] Measuring temperature: 50, 60, 70°C

[0322] When the measurement temperature is 50°C

[0323] AA: Peak value exceeds 30gf

[0324] A: Peak value exceeds 20gf and is below 30gf

[0325] B: Peak value exceeds 16gf and is less than 20gf

[0326] C: Peak value is less than 16gf

[0327] When the measurement temperature is 60°C

[0328] AA: Peak value exceeds 50gf

[0329] A: Peak value exceeds 30gf and is less than 50gf

[0330] B: Peak value exceeds 17gf and is less than 30gf

[0331] C: Peak value is 17gf or less

[0332] When the measurement temperature is 70℃

[0333] AA: Peak value exceeds 100gf

[0334] A: Peak value exceeds 50gf and is less than 100gf

[0335] B: Peak value exceeds 25gf and is less than 50gf

[0336] C: Peak value is less than 25gf

[0337] (2-3) Storage stability evaluation (granulation rate)

[0338] The obtained polyvinyl acetal resin was immersed in water again for 8 hours, and then stored in a desiccator at 35° C. for 48 hours.

[0339] The resin was removed from the dryer and the granulated product was sorted using a 5-mesh sieve and weighed. The granulation rate was calculated based on the weight change before and after sorting and evaluated according to the following criteria. It should be noted that a lower granulation rate indicates better storage stability.

[0340] AA: Granulation rate is less than 30%

[0341] A: Granulation rate is more than 30% and less than 40%

[0342] B: Granulation rate is more than 40% and less than 50%

[0343] C: Granulation rate exceeds 50%

[0344] [Table 1]

[0345]

[0346] [Table 2]

[0347]

[0348] Industrial applicability

[0349] The present invention provides a polyvinyl acetal resin having excellent adhesion over a wide temperature range and capable of producing a high-strength ceramic green sheet; a slurry composition for a ceramic green sheet using the polyvinyl acetal resin; a ceramic green sheet; and a multilayer ceramic capacitor.

Claims

A polyvinyl acetal resin having a tan δ peak top temperature of 35° C. to 80° C. and a tan δ peak half value width of 10.1° C. to 30° C. in a dynamic viscoelasticity measurement at 1 Hz. The polyvinyl acetal resin according to claim 1 , comprising a structural unit having an alkylene oxide group. The polyvinyl acetal resin according to claim 2 , comprising: a polyvinyl acetal having a structural unit having an alkylene oxide group; and a polyvinyl acetal not having an alkylene oxide group.

4. The polyvinyl acetal resin according to claim 2 or 3, wherein The number of carbon atoms in the alkylene oxide group is 2 or more and 200 or less.

5. The polyvinyl acetal resin according to any one of claims 2 to 4, wherein The number of repeating units of the alkylene oxide group is 2 or more and 100 or less. The polyvinyl acetal resin according to any one of claims 2 to 5, wherein The alkylene oxide group is at least one selected from the group consisting of ethylene oxide and propylene oxide.

7. The polyvinyl acetal resin according to any one of claims 2 to 6, wherein The content of the structural unit having an alkylene oxide is 0.1 mol % or more and 5 mol % or less based on the entire polyvinyl acetal resin. The polyvinyl acetal resin according to any one of claims 2 to 7, comprising a structural unit having an acetal group, a structural unit having an acetyl group, a structural unit having a hydroxyl group, and the structural unit having an alkylene oxide group.

9. The polyvinyl acetal resin according to any one of claims 1 to 8, wherein The content of the structural unit having a hydroxyl group is 23 mol % or more and 40 mol % or less based on the entire polyvinyl acetal resin. 10 . A slurry composition for ceramic green sheets, comprising the polyvinyl acetal resin according to claim 1 , an organic solvent, and ceramic powder. 11 . A ceramic green sheet produced using the slurry composition for ceramic green sheets according to claim 10 . 12 . A multilayer ceramic capacitor obtained by using the ceramic green sheet according to claim 11 .

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