Polyvinyl acetal resin

Abstract

To provide a polyvinyl acetal resin capable of obtaining a ceramic green sheet having high mechanical strength and excellent sheet attack resistance and preparing a highly reliable laminated ceramic capacitor and to provide a ceramic green sheet slurry, a ceramic green sheet and a laminated ceramic capacitor using the polyvinyl acetal resin.SOLUTION: There is provided a polyvinyl acetal resin in which the molecular weight relationship ratio calculated from the following expression (1) using the z average molecular weight Mz (THF) and the weight average molecular weight Mw (THF) obtained using THF in the mobile phase and the weight average molecular weight Mw (NMP) obtained using NMP in the mobile phase in GPC measurement using a differential refractive index detector is 0.9 or more and 1.6 or less and the weight average molecular weight Mw (THF) is 200000 or more and 500000 or less. [Mz(THF)-Mw(THF)] / Mw(NMP) (1)SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] BACKGROUND ART In recent years, electronic components mounted in various electronic devices have become increasingly smaller and more laminated, and multilayer electronic components such as multilayer circuit boards, multilayer coils, and multilayer ceramic capacitors are widely used. Among these, multilayer ceramic capacitors are generally manufactured through the following process. First, a plasticizer, dispersant, etc. are added to a solution prepared by dissolving a binder resin such as polyvinyl butyral resin or poly(meth)acrylic ester resin in an organic solvent, followed by the addition of a ceramic raw material powder and uniform mixing using a mixing device such as a bead mill or ball mill to obtain a ceramic slurry composition with a certain viscosity after degassing. This slurry composition is then cast onto a support surface such as a release-treated polyethylene terephthalate film or SUS plate using a doctor blade, reverse roll coater, etc., and the volatile components such as the solvent are removed by heating or other methods, after which the sheet is peeled off from the support to obtain a ceramic green sheet. Next, a conductive paste that will become the internal electrodes is applied to the obtained ceramic green sheets by screen printing, and multiple sheets are stacked alternately and heated and pressed to form a laminate. After that, a process to thermally decompose and remove binder resin components and the like contained in the laminate, known as a degreasing process, is performed, and external electrodes are sintered onto the end faces of the ceramic sintered body obtained by firing, to obtain a multilayer ceramic capacitor.

[0003] For example, Patent Document 1 describes a polyvinyl acetal resin suitable as a ceramic binder, which has a predetermined degree of polymerization, vinyl ester unit content, and degree of acetalization, and in which the molar ratio of the portion acetalized with acetaldehyde to the portion acetalized with butylaldehyde is within a predetermined range. Furthermore, Patent Document 2 describes a polyvinyl acetal resin having a predetermined degree of polymerization, a vinyl ester unit content, a degree of acetalization, and specific structural units. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-236304 [Patent Document 2] International Publication No. 2012 / 023517 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, in recent years, with the trend toward multifunctionality and miniaturization of electronic devices, multilayer ceramic capacitors are being demanded to have larger capacitance and smaller size, and ceramic green sheets are also being demanded to be thinner. However, when conventional polyvinyl acetal resins are used, the strength of the resulting ceramic green sheets is insufficient, and cracks occur during cutting and molding. There is also the problem of sheet attack, which occurs when the binder in the dielectric layer elutes into the electrode layer.

[0006] The present invention aims to provide a polyvinyl acetal resin that can produce ceramic green sheets having high mechanical strength and excellent sheet attack resistance, and that can be used to fabricate highly reliable multilayer ceramic capacitors; and to provide a ceramic green sheet slurry, a ceramic green sheet, and a multilayer ceramic capacitor that use the polyvinyl acetal resin. [Means for solving the problem]

[0007] The present disclosure 1 provides a polymer having a molecular weight ratio calculated from the following formula (1) using the z-average molecular weight Mz(THF) and weight-average molecular weight Mw(THF) obtained using THF as a mobile phase and the weight-average molecular weight Mw(NMP) obtained using NMP as a mobile phase in a GPC measurement using a differential refractive index detector, of 1.8 or less, and 13 The polyvinyl acetal resin has a ratio of the peak integral value of the methylene C atom shown in (a)' of the diad represented by the following formula (a) to the sum of the peak integral values ​​of the methylene C atoms shown in (b)' and (c)' of the diad represented by the following formula (b) and formula (c), as obtained by C-NMR (nuclear magnetic resonance) measurement, of 0.29 to 0.37. [Mz(THF)-Mw(THF)] / Mw(NMP) (1) [ka] In formula (b) and formula (c), R is each independently hydrogen or a hydrocarbon group having 1 to 20 carbon atoms. Disclosure 2 is the polyvinyl acetal resin according to Disclosure 1, in which the amount of hydroxyl groups is 28 mol % or more and 35 mol % or less. Disclosure 3 is the polyvinyl acetal resin according to Disclosure 1 or 2, which has a weight average molecular weight Mw(THF) of 200,000 or more and 500,000 or less. Disclosure 4 is the polyvinyl acetal resin according to Disclosure 1 or 2, which has a weight average molecular weight Mw(NMP) of 270,000 or more. The present disclosure 5 is a slurry for a ceramic green sheet, which contains the polyvinyl acetal resin according to the present disclosure 1 or 2, an organic solvent, and ceramic powder. The sixth aspect of the present disclosure is a ceramic green sheet obtained by using the slurry for the ceramic green sheet according to the fifth aspect of the present disclosure. Disclosure 7 is a multilayer ceramic capacitor obtained using the ceramic green sheet according to Disclosure 6. The present invention will be described in detail below.

[0008] As a result of extensive investigation, the present inventors have found that the weight average molecular weight and z average molecular weight measured by changing the solvent satisfy a predetermined relationship, and 13 The present inventors have found that polyvinyl acetal resins in which the ratio of the peak integral value of the methylene C atom shown in (a)' of the diad represented by the above formula (a) to the sum of the peak integral values ​​of the methylene C atoms shown in (b)' and (c)' of the diads represented by the above formula (b) and formula (c) is within a predetermined range (the ratio of the peak integral value of the diad consisting of two consecutive structural units having a hydroxyl group), as measured by C-NMR, can give ceramic green sheets with high mechanical strength and excellent sheet attack resistance, and can produce multilayer ceramic capacitors with excellent reliability, thereby completing the present invention.

[0009] The polyvinyl acetal resin of the present invention has a molecular weight ratio of 1.8 or less, calculated from the following formula (1) using the z-average molecular weight Mz(THF) and weight-average molecular weight Mw(THF) obtained using THF as a mobile phase and the weight-average molecular weight Mw(NMP) obtained using NMP as a mobile phase in GPC measurement using a differential refractive index detector: [Mz(THF)-Mw(THF)] / Mw(NMP) (1) By adjusting the thickness within the above range, the mechanical strength (particularly the breaking strain) of the resulting ceramic green sheet can be increased. The molecular weight ratio is preferably 1.7 or less, more preferably 1.6 or less, and is preferably 0.01 or more, more preferably 0.05 or more. In the present invention, the molecular weight relationship ratio is an index of intermolecular association. The molecular weight relationship ratio can be calculated by measuring the z-average molecular weight Mz(THF) and the weight-average molecular weight Mw(THF) by gel permeation chromatography (GPC) using tetrahydrofuran as the mobile phase and a differential refractive index detector as the detector, then measuring the weight-average molecular weight Mw(NMP) by GPC using N-methylpyrrolidone as the mobile phase and a differential refractive index detector as the detector, and calculating [Mz(THF)-Mw(THF)] / Mw(NMP).

[0010] The z-average molecular weight Mz(THF) of the polyvinyl acetal resin of the present invention is preferably 300,000 or more and 2,000,000 or less. By setting it within this range, the sheet attack resistance of the obtained ceramic green sheet can be maintained. The Mz(THF) is more preferably 400,000 or more and more preferably 1,200,000 or less.

[0011] The z-average molecular weight Mz(NMP) of the polyvinyl acetal resin of the present invention is preferably 300,000 or more and 1,000,000 or less. By setting it within this range, the sheet attack resistance of the obtained ceramic green sheet can be maintained. The Mz(NMP) is more preferably 400,000 or more and more preferably 600,000 or less.

[0012] The weight-average molecular weight Mw(THF) of the polyvinyl acetal resin of the present invention is preferably 200,000 or more and 500,000 or less. By setting it within this range, the elongation of the obtained ceramic green sheet can be maintained. The Mw(THF) is more preferably 220,000 or more and more preferably 400,000 or less.

[0013] The weight-average molecular weight Mw(NMP) of the polyvinyl acetal resin of the present invention is preferably 270,000 or more and 400,000 or less. By setting it within this range, the elongation of the obtained ceramic green sheet can be maintained. The Mw(NMP) is more preferably 275,000 or more and more preferably 300,000 or less.

[0014] The number-average molecular weight Mn(THF) of the polyvinyl acetal resin of the present invention is preferably 50,000 or more and 200,000 or less. By setting it within this range, the strength of the obtained ceramic green sheet can be maintained. The Mw(THF) is more preferably 75,000 or more and more preferably 200,000 or less.

[0015] The number average molecular weight Mn(NMP) of the polyvinyl acetal resin of the present invention is preferably 50,000 or more and 200,000 or less. By setting it within this range, the strength of the obtained ceramic green sheet can be maintained. The Mw(NMP) is more preferably 75,000 or more and more preferably 200,000 or less.

[0016] The molecular weight relationship ratio can be adjusted, for example, by changing the average degree of polymerization and degree of saponification of the raw material polyvinyl alcohol resin, and the temperature and time conditions of the acetalization reaction, and by appropriately setting the amount of acetal groups, hydroxyl groups, acetyl groups, etc. of the polyvinyl acetal resin. In particular, the molecular weight relationship ratio can be adjusted by changing the temperature drop temperature, temperature drop time, temperature drop rate, aldehyde introduction temperature (introduction temperature), reaction temperature, reaction time, temperature rise time after the reaction step, temperature rise rate, holding (aging) temperature, and holding (aging) time during the acetalization reaction described below.

[0017] The polyvinyl acetal resin of the present invention is 13The ratio of the peak integral value of diads consisting of two consecutive hydroxyl group-containing structural units measured by C-NMR is 0.29 or more and 0.37 or less. By setting it in this range, sheet attack resistance can be improved. The ratio of the peak integral value of diads consisting of two consecutive hydroxyl group-containing structural units has a preferred lower limit of 0.30, a more preferred lower limit of 0.31, and a preferred upper limit of 0.365, an even more preferred upper limit of 0.36. If the ratio is equal to or greater than the lower limit, the hydrogen bonding properties due to the hydroxyl groups are improved, and a ceramic green sheet produced using the polyvinyl acetal resin of the present invention can have low solubility in organic solvents, resulting in good sheet attack resistance. If the ratio is equal to or less than the upper limit, the solubility of the polyvinyl acetal resin in organic solvents is not too low, resulting in good handleability, such as in solution preparation.

[0018] The ratio of the peak integral value of the diad, which is a chain consisting of structural units having two hydroxyl groups, is The ratio of the sum of the peak integral values ​​of the methylene C atoms shown in (a)' of the diad represented by the following formula (a) to the sum of the peak integral values ​​of the methylene C atoms shown in (b)' and (c)' of the diad represented by the following formula (b) and formula (c), 13 It can be measured by C-NMR.

[0019] 13 Obtained by C-NMR (nuclear magnetic resonance) measurement 13 In a C-NMR spectrum, the sum of the peak integral values ​​of the methylene C atoms shown in (b)' and (c)' of the diads represented by the following formulas (b) and (c) can be calculated by the sum of these values, i.e., [I(b)' + I(c)'], where I(b)' is the peak integral value to which the methylene C atom shown in (b)' of the diad represented by the following formula (b) belongs, and I(c)' is the peak integral value to which the methylene C atom shown in (c)' of the diad represented by the following formula (c) belongs.

[0020] [ka] In formula (b) and formula (c), R is each independently hydrogen or a hydrocarbon group having 1 to 20 carbon atoms.

[0021] 13 Obtained by C-NMR (nuclear magnetic resonance) measurement 13 In the C-NMR spectrum, the peak integral value of the methylene C atom shown in (a)' of the diad represented by the above formula (a) can be determined from the peak integral value [I(a)'] to which the methylene C atom shown in (a)' of the diad represented by the above formula (a) belongs.

[0022] 13 In the C-NMR spectrum, I(a)' is the peak integral value in the range of 44.6 to 46.0 ppm, and I(b)'+I(c)' is the peak integral value in the range of 42.9 to 44.6 ppm.

[0023] Regarding the polyvinyl acetal resin of the present invention, 13 Obtained by C-NMR (nuclear magnetic resonance) measurement 13 An example of a C-NMR spectrum (partially enlarged) is shown in Figure 1. 13 The peaks (a)', (b)', and (c)' shown in the C-NMR spectrum are the peaks assigned to the methylene C atoms shown in (a)', (b)', and (c)' of the diads represented by the above formulae (a), (b), and (c), respectively.

[0024] The ratio of the peak integral value of the diads consisting of two chains of structural units having a hydroxyl group can be adjusted, for example, by changing the average degree of polymerization and degree of saponification of the raw material polyvinyl alcohol resin, and the temperature and time conditions of the acetalization reaction, and by appropriately setting the amount of acetal groups, hydroxyl groups, acetyl groups, etc. of the polyvinyl acetal resin. In particular, the ratio of the peak integral value of the diads consisting of two chains of structural units having the above-mentioned hydroxyl group can be adjusted by changing the temperature drop temperature, temperature drop time, temperature drop rate, aldehyde introduction temperature (introduction temperature), reaction temperature, reaction time, temperature rise time after the reaction step, temperature rise rate, holding (aging) temperature, and holding (aging) time during the acetalization reaction described below.

[0025] The polyvinyl acetal resin of the present invention preferably has a solution viscosity of 60 mPa s or more and 600 mPa s or less when a 5 mass % solution dissolved in a 1:1 mixed solvent of ethanol and toluene is measured using a Brookfield viscometer at a solution temperature of 20°C. In order to improve the tensile strength, the viscosity is more preferably 65 mPa·s or more, and even more preferably 70 mPa·s or more. In order to improve the viscosity stability of the ceramic slurry composition, the viscosity is more preferably 300 mPa·s or less, and even more preferably 150 mPa·s or less. The B-type viscometer may be, for example, a TVB-10 viscometer manufactured by Toki Sangyo Co., Ltd. The rotor and rotation speed during viscosity measurement are preferably adjusted appropriately depending on the viscosity of the solution, and for example, measurements are preferably performed using spindles No. M1 to M4 at a rotation speed in the range of 0.3 to 100 rpm.

[0026] The viscosity can be adjusted, for example, by changing the average degree of polymerization and degree of saponification of the raw material polyvinyl alcohol resin, and the temperature and time conditions of the acetalization reaction, and by appropriately setting the amount of acetal groups, hydroxyl groups, acetyl groups, etc. of the polyvinyl acetal resin.

[0027] The polyvinyl acetal resin of the present invention preferably has a structural unit having an acetal group represented by the following formula (3), a structural unit having a hydroxyl group represented by the following formula (4), and a structural unit having an acetyl group represented by the following formula (5).

[0028] [ka] In the above formula (3), R 1 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.

[0029] In the above formula (3), R 1When is an alkyl group having 1 to 20 carbon atoms, examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, an octadecyl group, etc. Of these, a methyl group and an n-propyl group are preferred.

[0030] In the polyvinyl acetal resin of the present invention, the content of the structural unit having the acetal group represented by the above formula (3) (hereinafter also referred to as "acetal group amount") is preferably 50 mol % in lower limit and 83 mol % in upper limit. When the amount of acetal groups is 50 mol % or more, the solubility in organic solvents can be improved, and when the amount of acetal groups is 83 mol % or less, the polyvinyl acetal resin can have excellent tensile strength. The acetal group amount has a more preferred lower limit of 55 mol % and a more preferred upper limit of 80 mol %. That is, the acetal group amount is preferably 50 to 83 mol %, and more preferably 55 to 80 mol %. The amount of acetal groups is, for example, 1 It can be measured by H-NMR. Regarding the method for calculating the amount of acetal groups, since the acetal groups of the polyvinyl acetal resin are obtained by acetalizing two hydroxyl groups of polyvinyl alcohol, the method of counting the two acetalized hydroxyl groups is adopted.

[0031] In the polyvinyl acetal resin of the present invention, the content of the structural unit having a hydroxyl group represented by the above general formula (4) (hereinafter also referred to as "hydroxyl group amount") is preferably 28 mol % in lower limit and 35 mol % in upper limit. When the amount of hydroxyl groups is 28 mol % or more, the polyvinyl acetal resin can have high toughness, and when the amount of hydroxyl groups is 35 mol % or less, the solubility in organic solvents can be sufficiently improved. The lower limit of the hydroxyl group amount is more preferably 29 mol % and the upper limit is more preferably 34 mol %. That is, the hydroxyl group amount is preferably 28 to 35 mol %, and more preferably 29 to 34 mol %. The amount of hydroxyl groups is, for example, 1 It can be measured by H-NMR.

[0032] In the polyvinyl acetal resin of the present invention, the content of the structural unit having an acetyl group represented by the above general formula (5) (hereinafter also referred to as "acetyl group amount") is preferably 0.1 mol % in lower limit and 22.0 mol % in upper limit. When the acetyl group content is 0.1 mol% or more, the increase in viscosity of the slurry composition for ceramic green sheets due to intramolecular and intermolecular hydrogen bonding of hydroxyl groups in the polyvinyl acetal resin can be suppressed.When the acetyl group content is 22.0 mol% or less, the flexibility of the polyvinyl acetal resin is not excessively increased, and handling properties can be improved. The lower limit of the acetyl group amount is more preferably 0.5 mol % and the upper limit is more preferably 15.0 mol %. That is, the acetyl group amount is preferably 0.1 to 22.0 mol %, and more preferably 0.5 to 15 mol %. The amount of acetyl groups is, for example, 1 It can be measured by H-NMR.

[0033] From the viewpoint of maintaining mechanical strength when producing a thin film ceramic green sheet, the polyvinyl acetal resin of the present invention has an average degree of polymerization whose lower limit is preferably 500, more preferably 600, and whose upper limit is preferably 10,000, more preferably 9,000, from the viewpoint of solubility in organic solvents and dissolution viscosity. That is, the average degree of polymerization is preferably 500 to 10,000, more preferably 600 to 9,000. The average degree of polymerization of the polyvinyl acetal resin is the same as that of the raw material polyvinyl alcohol, and can be measured in accordance with JIS K 6726.

[0034] The polyvinyl acetal resin of the present invention can usually be produced by acetalizing a polyvinyl alcohol resin.

[0035] As the polyvinyl alcohol resin, for example, a conventionally known polyvinyl alcohol resin such as a resin produced by saponifying a polyvinyl acetate resin with an alkali, an acid, aqueous ammonia, or the like can be used. The polyvinyl alcohol resin may be fully saponified, but does not need to be fully saponified as long as it has at least one unit having two consecutive hydroxyl groups at the meso and racemo positions at at least one location on the main chain, and may be a partially saponified polyvinyl alcohol resin. Furthermore, as the polyvinyl alcohol resin, a copolymer of vinyl alcohol and a monomer copolymerizable with vinyl alcohol, such as an ethylene-vinyl alcohol copolymer resin or a partially saponified ethylene-vinyl alcohol copolymer resin, may also be used. The polyvinyl acetate resin may be, for example, an ethylene-vinyl acetate copolymer.

[0036] The polyvinyl alcohol resin preferably has a degree of saponification of 75 mol % or more. The saponification degree is more preferably 76 mol % or more and 99.4 mol % or less, and even more preferably 78 mol % or more and 98 mol % or less. That is, the saponification degree is preferably 76 to 99.4 mol %, and more preferably 78 to 98 mol %. By using the polyvinyl alcohol resin, the Mz can be set within a predetermined range.

[0037] The acetalization is preferably carried out in a water solvent, a mixed solvent of water and an organic solvent compatible with water, or an organic solvent. As the organic solvent that is compatible with water, for example, an alcohol-based organic solvent can be used. Examples of the organic solvent include alcohol-based organic solvents, aromatic organic solvents, aliphatic ester-based solvents, ketone-based solvents, lower paraffin-based solvents, ether-based solvents, amide-based solvents, and amine-based solvents. Examples of the alcohol-based organic solvent include methanol, ethanol, n-propanol, isopropanol, n-butanol, and tert-butanol. Examples of the aromatic organic solvent include xylene, toluene, ethylbenzene, and methyl benzoate. 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. Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methylcyclohexanone, benzophenone, and acetophenone. Examples of the lower paraffin solvent include hexane, pentane, octane, cyclohexane, and decane. Examples of the ether solvent include diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol diethyl ether. Examples of the amide solvent include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and acetanilide. 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. These solvents can be used alone or in combination of two or more. Among these, ethanol, n-propanol, isopropanol, and tetrahydrofuran are particularly preferred from the viewpoints of solubility in the resin and ease of purification.

[0038] The acetalization is preferably carried out in the presence of an acid catalyst. 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 paratoluenesulfonic acid. These acid catalysts may be used alone or in combination of two or more compounds. Among these, hydrochloric acid, nitric acid, and sulfuric acid are preferred, and hydrochloric acid is particularly preferred.

[0039] The aldehyde used in the acetalization reaction includes aldehydes having a chain aliphatic group, a cyclic aliphatic group, or an aromatic group having 1 to 10 carbon atoms. Any known aldehyde can be used as this aldehyde. The aldehyde used in the acetalization reaction is not particularly limited, and examples thereof include aliphatic aldehydes and aromatic aldehydes. Examples of the aliphatic aldehyde include formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, n-hexylaldehyde, 2-ethylbutyraldehyde, 2-ethylhexylaldehyde, n-heptylaldehyde, n-octylaldehyde, n-nonylaldehyde, n-decylaldehyde, and amylaldehyde. Examples of the aromatic aldehyde include benzaldehyde, cinnamaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, and β-phenylpropionaldehyde. These aldehydes may be used alone or in combination of two or more. Among them, formaldehyde, acetaldehyde, butylaldehyde, 2-ethylhexylaldehyde, and n-nonylaldehyde are preferred as aldehydes, as they have excellent acetalization reactivity, bring about a sufficient internal plasticizing effect in the resulting resin, and as a result, can impart good flexibility. Furthermore, formaldehyde, acetaldehyde, and butylaldehyde are more preferred, as they can provide an adhesive composition that is particularly excellent in impact resistance and adhesion to metals.

[0040] The amount of the aldehyde to be added can be appropriately determined depending on the amount of acetal groups in the target polyvinyl acetal resin. In particular, it is preferable to add the aldehyde in an amount of 50 mol % to 95 mol % and more preferably 55 mol % to 90 mol % relative to 100 mol % of polyvinyl alcohol, because this allows the acetalization reaction to proceed efficiently and makes it easy to remove unreacted aldehyde.

[0041] In the acetalization reaction, it is preferable to lower the temperature to a predetermined temperature or lower before adding the aldehyde (temperature lowering step), then raise the temperature to a predetermined temperature, add the aldehyde and carry out the reaction (reaction step), and then raise the temperature and maintain it at the predetermined temperature (aging step). The temperature in the temperature-lowering step (lowering temperature) is preferably 0° C. or higher and 50° C. or lower, and more preferably 5° C. or higher and 40° C. or lower. The temperature is preferably lowered by 1° C. or higher and 30° C. or lower, and more preferably by 5° C. or higher and 20° C. or lower, relative to the reaction temperature. The time required to reach the above-mentioned temperature (temperature-lowering time) is preferably 1 minute or more and 240 minutes or less, and more preferably 180 minutes or less. The rate of temperature drop until the temperature reaches the above-mentioned temperature is preferably 0.05°C / min or more and 1.5°C / min or less.

[0042] The temperature when the aldehyde is added and the reaction temperature in the reaction step are preferably 10°C or higher and 50°C or lower, and more preferably 20°C or higher and 40°C or lower. The reaction time in the reaction step is preferably 10 minutes or more and 120 minutes or less, and more preferably 20 minutes or more and 90 minutes or less. By carrying out the temperature lowering step and the reaction step, the THFMz-NMPMz can be adjusted to a predetermined range.

[0043] The temperature rise time after the reaction step is preferably 30 minutes or more and 500 minutes or less, and more preferably 60 minutes or more and 400 minutes or less. The temperature rise rate up to the aging step is preferably 0.1° C. / min or more and 2° C. / min or less.

[0044] The retention time in the aging step is preferably 0.5 hours or more and 6 hours or less, and more preferably 1 hour or more and 5 hours or less. The temperature maintained in the aging step is preferably 50°C or higher and 80°C or lower, and more preferably 55°C or higher and 75°C or lower. By using the above-mentioned holding time and holding temperature, the ratio of the peak integral value of the diads consisting of two consecutive chains of structural units having a hydroxyl group can be kept within a predetermined range.

[0045] By containing the polyvinyl acetal resin of the present invention and a plasticizer, a resin composition for a ceramic green sheet can be obtained. The resin composition for a ceramic green sheet may contain components such as an antioxidant, a surfactant, an ultraviolet absorber, and an antifoaming agent, as long as the effects of the present invention are not impaired.

[0046] As a method for producing the resin composition for a ceramic green sheet, for example, a plasticizer and other additives that are added as needed can be added to a polyvinyl acetal resin obtained by acetalizing a polyvinyl alcohol resin with an aldehyde, and then mixed to obtain a resin composition for a ceramic green sheet.

[0047] The resin composition for a ceramic green sheet contains a plasticizer, and the addition of the plasticizer can significantly improve the mechanical strength and flexibility of the resulting ceramic green sheet. Examples of the plasticizer include phthalic acid diesters such as dioctyl phthalate (DOP) and dibutyl phthalate (DBP), adipic acid 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.

[0048] In the resin composition for a ceramic green sheet, the content of the plasticizer relative to 100 parts by weight of the polyvinyl acetal resin is preferably 7 parts by weight at the lower limit, more preferably 8.5 parts by weight at the lower limit, and preferably 18 parts by weight at the upper limit, more preferably 13.5 parts by weight at the upper limit.

[0049] A slurry for ceramic green sheets can be prepared by mixing the polyvinyl acetal resin of the present invention with an organic solvent and ceramic powder.

[0050] The organic solvent is not particularly limited as long as it can dissolve the polyvinyl acetal resin, and examples thereof include ketones such as acetone, methyl ethyl ketone, dipropyl ketone, and diisobutyl ketone. Other examples include alcohols such as methanol, ethanol, isopropanol, and butanol, and aromatic hydrocarbons such as toluene and xylene. Further examples include esters such as methyl propionate, ethyl propionate, butyl propionate, methyl butanoate, ethyl butanoate, butyl butanoate, methyl pentanoate, ethyl pentanoate, butyl pentanoate, methyl hexanoate, ethyl hexanoate, butyl hexanoate, 2-ethylhexyl acetate, and 2-ethylhexyl butyrate. Other 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 in terms of coating and drying properties, with a mixed solvent of ethanol and toluene and a mixed solvent of methyl ethyl ketone and toluene being more preferred.

[0051] The content of the organic solvent in the ceramic green sheet slurry is determined depending on the type of polyvinyl acetal resin used and is not particularly limited. However, if the content is too low, the solubility required for kneading is difficult to achieve. On the other hand, if the content is too high, the viscosity of the ceramic green sheet slurry composition becomes too low, which can result in poor handling when producing ceramic green sheets. Therefore, the content of the organic solvent is preferably 20% by weight or more and 80% by weight or less.

[0052] The ceramic powders include metal or nonmetal oxide or non-oxide powders used in ceramic production. These powders may be single compositions, compounds, or mixtures. The constituent elements of the metal oxide or non-oxide, both cations and anions, may be single elements or multiple elements, and may further contain additives to improve the properties of the oxide or non-oxide. Specific examples include oxides, carbides, nitrides, borides, and sulfides of elements such as 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, and Ni. Furthermore, when specific oxide powders containing multiple metal elements, commonly called double oxides, are classified based on their crystal structure, those with a perovskite structure include NaNbO3, SrZrO3, PbZrO3, SrTiO3, BaZrO3, PbTiO3, BaTiO3, etc. Those with a spinel structure include MgAl2O4, ZnAl2O4, CoAl2O4, NiAl2O4, MgFe2O4, etc. Those with an ilmenite structure include MgTiO3, MnTiO3, FeTiO3, etc. Those with a garnet structure include GdGa5O 12 , Y6Fe5O 12 Among these, the modified polyvinyl acetal resin of the present invention exhibits excellent properties when mixed with BaTiO3 powder to form a ceramic green sheet.

[0053] The average particle size of the ceramic powder is not particularly limited, but for example, for producing a thin ceramic green sheet (thickness of 5 μm or less), it is preferably 0.5 μm or less.

[0054] The ceramic green sheet slurry may contain other polyvinyl acetal resins other than the polyvinyl acetal resin of the present invention, as well as other resins such as acrylic resins and ethyl cellulose, within the range that does not impair the effects of the present invention. In such cases, the content of the polyvinyl acetal resin of the present invention relative to the total binder resins is preferably 50% by weight or more.

[0055] If necessary, a dispersant, an antioxidant, an ultraviolet absorber, a surfactant, a filler, etc. may be added appropriately to the above-mentioned slurry for the ceramic green sheet, and in some cases, a small amount of other resin such as an acrylic resin or a urethane resin may also be added.

[0056] The method for producing the slurry for the ceramic green sheet is not particularly limited, and examples thereof include a method in which the polyvinyl acetal resin of the present invention, an organic solvent, a ceramic powder, and various additives to be added as needed are mixed using various mixers such as a ball mill, a blender mill, and a three-roll mill.

[0057] After the slurry for the ceramic green sheet is applied, the slurry is heated and dried to obtain a ceramic green sheet. The ceramic green sheets can be used to manufacture ceramic electronic components, for example, by carrying out a step of applying an electrode layer paste to the surfaces of the ceramic green sheets, and a step of stacking the ceramic green sheets on which the electrode layers have been formed, and then heat-pressing and bonding the stacked body, and then degreasing and firing the resulting laminate.

[0058] The method for applying the slurry for the ceramic green sheet is not particularly limited, and examples thereof include methods using a roll coater, a die coater, a curtain coater, etc. As for other specific methods, conventionally known methods can be used.

[0059] The ceramic electronic component is not particularly limited, and examples thereof include a multilayer ceramic capacitor, a multilayer ceramic inductor, a capacitor, a piezoelectric actuator, a multilayer varistor, a multilayer thermistor, an EMI filter, an aluminum nitride multilayer substrate, an alumina multilayer substrate, etc. Such a multilayer ceramic capacitor also constitutes part of the present invention.

[0060] The method for producing a ceramic electronic component includes a step of applying a paste for electrode layers to the surfaces of the ceramic green sheets. The electrode layer paste can be obtained by dissolving, for example, polyvinyl acetal resin, ethyl cellulose, acrylic resin, or the like as a binder resin in an organic solvent and dispersing conductive powder, etc. These resins may be used alone or in combination of two or more. An electrode layer paste containing a polyvinyl acetal resin is preferred because it exhibits excellent adhesion to the ceramic green sheet in the thermocompression bonding process.

[0061] In the method for producing a ceramic electronic component, the ceramic green sheets having electrode layers formed thereon are produced as described above, and then ceramic green sheets having electrode layers formed thereon that are produced in the same manner are stacked and heated and pressed together to obtain a laminate, which is then degreased and fired, thereby obtaining a multilayer ceramic electronic component that solves problems such as sheet attack and cracking. The above-mentioned thermocompression bonding step and the steps of degreasing and firing the laminate are not particularly limited, and conventionally known methods can be used. [Effects of the Invention]

[0062] According to the present invention, it is possible to provide a polyvinyl acetal resin that can produce a ceramic green sheet having high mechanical strength and excellent sheet attack resistance, and that can produce a highly reliable multilayer ceramic capacitor, as well as a ceramic green sheet slurry, a ceramic green sheet, and a multilayer ceramic capacitor that use the polyvinyl acetal resin. Furthermore, by using the polyvinyl acetal resin of the present invention, the dispersibility and dispersion stability of ceramic powder can be significantly improved. [Brief explanation of the drawings]

[0063] [Figure 1] FIG. 1 is a diagram (partially enlarged) showing an example of a 13C-NMR (nuclear magnetic resonance) spectrum obtained by 13C-NMR measurement of the polyvinyl acetal resin of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0064] The present invention will be explained in more detail below by way of examples, but the present invention is not limited to these examples.

[0065] Example 1 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average polymerization degree 1700, saponification degree 99.1 mol%) and dissolved by stirring at 90°C for approximately 2 hours. This solution was cooled to 10°C over 120 minutes, then heated to 20°C, and 220 g of hydrochloric acid with a concentration of 35 wt% and 180 g of n-butylaldehyde were added thereto. After that, the mixture was kept at 20°C for 1 hour to carry out an acetalization reaction (reaction step), and then the temperature was raised to 55°C over 150 minutes and kept at 55°C for 3 hours (aging step) to complete the reaction.The mixture was then neutralized, washed with water, and dried in the usual manner to obtain a white powder of polyvinyl acetal resin.

[0066] Example 2 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average polymerization degree 1700, saponification degree 99.0 mol%) and dissolved by stirring at 90°C for approximately 2 hours. After cooling this solution to 5°C over 150 minutes, the temperature was raised to 20°C, and 220 g of hydrochloric acid with a concentration of 35 wt% and 180 g of n-butylaldehyde were added thereto. After that, the mixture was kept at 20°C for 1 hour to carry out an acetalization reaction (reaction step), and then the temperature was raised to 55°C over 150 minutes and kept at 55°C for 3 hours (aging step) to complete the reaction.The mixture was then neutralized, washed with water, and dried in the usual manner to obtain a white powder of polyvinyl acetal resin.

[0067] Example 3 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average polymerization degree 1700, saponification degree 99.2 mol%) and dissolved by stirring at 90°C for approximately 2 hours. After cooling this solution to 20°C over 90 minutes, it was heated to 30°C, and 220 g of hydrochloric acid with a concentration of 35 wt% and 180 g of n-butylaldehyde were added thereto. Thereafter, the mixture was maintained at 30°C for 0.5 hours to carry out an acetalization reaction (reaction step), and then the temperature was raised to 55°C over 150 minutes and maintained at 55°C for 3 hours (aging step) to complete the reaction. The mixture was then neutralized, washed with water, and dried in the usual manner to obtain a white powder of polyvinyl acetal resin.

[0068] Example 4 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average polymerization degree 1700, saponification degree 99.2 mol%) and dissolved by stirring at 90°C for approximately 2 hours. After cooling this solution to 20°C over 90 minutes, it was heated to 30°C, and 220 g of hydrochloric acid with a concentration of 35 wt% and 180 g of n-butylaldehyde were added thereto. Thereafter, the mixture was maintained at 30°C for 0.5 hours to carry out an acetalization reaction (reaction step), and then the temperature was raised to 60°C over 180 minutes and maintained at 60°C for 3 hours (aging step) to complete the reaction. The mixture was then neutralized, washed with water, and dried in the usual manner to obtain a white powder of polyvinyl acetal resin.

[0069] Example 5 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average polymerization degree 1700, saponification degree 99.2 mol%) and dissolved by stirring at 90°C for approximately 2 hours. After cooling this solution to 20°C over 90 minutes, it was heated to 30°C, and 220 g of hydrochloric acid with a concentration of 35 wt% and 180 g of n-butylaldehyde were added thereto. Thereafter, the mixture was maintained at 30°C for 0.5 hours to carry out an acetalization reaction (reaction step), and then the temperature was raised to 55°C over 150 minutes and maintained at 55°C for 3 hours (aging step) to complete the reaction. The mixture was then neutralized, washed with water, and dried in the usual manner to obtain a white powder of polyvinyl acetal resin.

[0070] Example 6 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average polymerization degree 1700, saponification degree 99.1 mol%) and dissolved by stirring at 90°C for approximately 2 hours. After cooling this solution to 20°C over 90 minutes, the temperature was raised to 40°C, and 220 g of hydrochloric acid with a concentration of 35 wt% and 180 g of n-butylaldehyde were added thereto. Thereafter, the mixture was maintained at 40°C for 0.5 hours to carry out an acetalization reaction (reaction step), and then the temperature was raised to 55°C over 150 minutes and maintained at 55°C for 3 hours (aging step) to complete the reaction. The mixture was then neutralized, washed with water, and dried in the usual manner to obtain a white powder of polyvinyl acetal resin.

[0071] Example 7 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average polymerization degree 1700, saponification degree 99.1 mol%) and dissolved by stirring at 90°C for approximately 2 hours. After cooling this solution to 20°C over 90 minutes, the temperature was raised to 40°C, and 220 g of hydrochloric acid with a concentration of 35 wt% and 180 g of n-butylaldehyde were added thereto. Thereafter, the mixture was maintained at 40°C for 0.5 hours to carry out an acetalization reaction (reaction step), and then the temperature was raised to 70°C over 240 minutes and maintained at 70°C for 0.5 hours (aging step) to complete the reaction. The mixture was then neutralized, washed with water, and dried in the usual manner to obtain a white powder of polyvinyl acetal resin.

[0072] (Comparative Example 1) 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average polymerization degree 1700, saponification degree 99.4 mol%) and dissolved by stirring at 90°C for approximately 2 hours. This solution was cooled to 20°C over 90 minutes, and 220 g of hydrochloric acid with a concentration of 35 wt% and 180 g of n-butylaldehyde were added thereto. After that, the mixture was kept at 20°C for 1 hour to carry out an acetalization reaction (reaction step), and then the temperature was raised to 55°C over 150 minutes and kept at 55°C for 3 hours (aging step) to complete the reaction.The mixture was then neutralized, washed with water, and dried in the usual manner to obtain a white powder of polyvinyl acetal resin.

[0073] (Comparative Example 2) 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average polymerization degree 1700, saponification degree 99.4 mol%) and dissolved by stirring at 90°C for approximately 2 hours. This solution was cooled to 20°C over 90 minutes, and 180 g of hydrochloric acid with a concentration of 35 wt% and 220 g of n-butylaldehyde were added thereto. Thereafter, the mixture was maintained at 20°C for 1 hour to carry out an acetalization reaction (reaction step), and then the temperature was raised to 30°C over 60 minutes and maintained at 30°C for 3 hours (aging step) to complete the reaction. The mixture was then neutralized, washed with water, and dried in the usual manner to obtain a white powder of polyvinyl acetal resin.

[0074] (Comparative Example 3) 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average polymerization degree 1700, saponification degree 99.1 mol%) and dissolved by stirring at 90°C for approximately 2 hours. This solution was cooled to 30°C over 60 minutes, and 220 g of hydrochloric acid with a concentration of 35 wt% and 180 g of n-butylaldehyde were added thereto. Thereafter, the mixture was kept at 30°C for 0.5 hours to carry out an acetalization reaction (reaction step), and then kept at 30°C for 3 hours (aging step) to complete the reaction. The mixture was then neutralized, washed with water, and dried in a conventional manner to obtain a white powder of polyvinyl acetal resin.

[0075] Comparative Example 4 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average polymerization degree 1700, saponification degree 99.2 mol%) and dissolved by stirring at 90°C for approximately 2 hours. This solution was cooled to 10°C over 120 minutes, then heated to 20°C, and 220 g of 35 wt% hydrochloric acid and 180 g of n-butylaldehyde were added thereto. Thereafter, the mixture was maintained at 20°C for 1 hour to carry out an acetalization reaction (reaction step), and then the temperature was raised to 60°C over 180 minutes and maintained at 60°C for 6 hours (aging step) to complete the reaction. The mixture was then neutralized, washed with water, and dried in the usual manner to obtain a white powder of polyvinyl acetal resin.

[0076] (evaluation) The polyvinyl acetal resins obtained in the examples and comparative examples were evaluated as follows, and the results are shown in Table 1.

[0077] (1) Evaluation of polyvinyl acetal resin (1-1) Amount of acetal groups, amount of hydroxyl groups, amount of acetyl groups The obtained polyvinyl acetal resin was analyzed using an AV400 spectrometer (manufactured by Bruker). 1 H-NMR measurement was carried out, and the amounts of acetal groups, hydroxyl groups, and acetyl groups were calculated. The obtained polyvinyl acetal resin was dissolved in DMSO-D6 to a concentration of 1.6% by weight to prepare a measurement solution. 1 H-NMR measurements were carried out at 80°C.

[0078] (1-2) Measurement of weight-average molecular weight and z-average molecular weight The resulting polyvinyl acetal resin was dissolved in tetrahydrofuran (THF) at a concentration of 0.2 wt% and passed through a 0.45 μm PTFE filter. The resulting solution was analyzed using a GPC system (HLC-8420, Tosoh Corporation) with a THF mobile phase, a Bryce-type double-pass refractive index detector (Tosoh Corporation), and a TSKgel Super HZM-H column (Tosoh Corporation) at a flow rate of 0.35 mL / min. The results were calibrated using a molecular weight calibration curve prepared using monodisperse polystyrene standards to obtain the z-average molecular weight Mz (THF) and the weight-average molecular weight Mw (THF). Similarly, the obtained polyvinyl acetal resin was dissolved in N-methylpyrrolidone (NMP) at a concentration of 0.2 wt%, passed through a PTFE filter with a pore size of 0.45 μm, and measured at a flow rate of 0.5 mL / min using a GPC-101 (Shodex) GPC apparatus, NMP as the mobile phase, a differential refractive index detector RI-715 (Shodex) as the detector, and an LF-804 (Shodex) column. The measurement results were calibrated using a molecular weight calibration curve prepared using monodisperse polystyrene standards to obtain the weight-average molecular weight Mw (NMP). From the obtained Mz(THF), Mw(THF) and Mw(NMP), [Mz(THF)-Mw(THF)] / Mw(NMP) was calculated as the molecular weight ratio.

[0079] (1-3) Proportion of peak integral values ​​of diads consisting of two consecutive hydroxyl group-containing structural units in polyvinyl acetal resin (proportion of di-sequence hydroxyl group structural units) The obtained polyvinyl acetal resin was analyzed using an AVANCE600 spectrometer and CryoProbe (manufactured by Bruker). 13 The proportion of the peak integral value of the diad consisting of two consecutive hydroxyl group-containing structural units in the polyvinyl acetal resin was measured by C-NMR measurement. The details of the peak integral value measurement are as described above. The obtained polyvinyl acetal resin was dissolved in DMSO-D6 to a concentration of 12% by weight, and a relaxation reagent (chromium (III) acetylacetate) was added to prepare a measurement solution. 13 C-NMR measurements were performed at 80°C in power gated 1H decoupling mode.

[0080] (2) Evaluation of polyvinyl acetal resin sheet 10.0 parts by weight of the obtained polyvinyl acetal resin and 45 parts by weight of an ethanol / toluene mixed solvent (weight ratio 1:1) were added and dissolved with stirring to obtain a polyvinyl acetal resin composition. The obtained polyvinyl acetal resin composition was applied to a release-treated PET film using a coater so that the thickness after drying would be 20 μm, and then the film was dried by heating to prepare a polyvinyl acetal resin sheet.

[0081] (2-1) Sheet attack resistance evaluation (solvent elution) The obtained polyvinyl acetal resin sheet was cut into a 1.5 cm x 10 cm square and accurately weighed. The test piece was then immersed in 10 ml of dihydroterpineol acetate at 23°C for 1 minute. The test piece was then removed and dried at 150°C for 6 hours to completely evaporate the solvent. After removing from the dryer, the specimen was left at room temperature for 1 hour and then weighed. The amount of resin eluted was calculated from the change in weight before and after the test, and the elution rate was calculated from the ratio of this elution amount to the weight of the specimen before the test, and evaluated according to the following criteria. Note that a higher elution rate indicates better sheet attack resistance.

[0082] A: Dissolution rate is 4.3% or less B: Dissolution rate is over 4.3% and 4.8% or less C: Dissolution rate is over 4.8%

[0083] (3) Evaluation of ceramic green sheets (Preparation of inorganic dispersion) One part by weight of polyvinyl acetal resin (BL-1, manufactured by Sekisui Chemical Co., Ltd.) was added to a mixed solvent of 20 parts by weight of toluene and 20 parts by weight of ethanol and dissolved by stirring. Next, 100 parts by weight of barium titanate powder (BT01, manufactured by Sakai Chemical Industry Co., Ltd.) was added to the resulting solution and stirred for 180 minutes in a bead mill (Ready Mill, manufactured by Imex Co., Ltd.) to prepare an inorganic dispersion.

[0084] (Preparation of resin solution) 8 parts by weight of the obtained polyvinyl acetal resin and 2 parts by weight of DOP were added to a mixed solvent of 45 parts by weight of ethanol and 45 parts by weight of toluene, and the mixture was stirred and dissolved to prepare a resin solution.

[0085] (Preparation of ceramic green sheets) The resin solution was added to the obtained inorganic dispersion and stirred for 90 minutes in a bead mill to obtain a composition for ceramic green sheets. The obtained ceramic green sheet composition was applied to a release-treated PET film using a coater so that the thickness after drying would be 20 μm, and then heated and dried to prepare a ceramic green sheet.

[0086] (3-1) Breaking strain The obtained ceramic green sheet was made into a test piece in the shape of a dumbbell No. 1 (based on JIS K 6771), and pulled at a tension speed of 500% / min using a tensile testing machine (Shimadzu Corporation, AUTOGRAPH AGS-J) to measure the breaking tensile strength (kg / cm) at a measurement temperature of 20°C. 2 ) was measured. A stress σ (MPa)-strain ε (%) curve was calculated from the obtained values. Note that 500% / min means a speed at which the test piece is moved a distance five times the distance between the chucks in one minute. The breaking strain was calculated from the obtained stress-strain curve and evaluated according to the following criteria. A: 20% or more B: 17% or more but less than 20% C: Less than 17%

[0087] [Table 1] [Industrial Applicability]

[0088] According to the present invention, it is possible to provide a polyvinyl acetal resin that can produce a ceramic green sheet having high mechanical strength and excellent sheet attack resistance, and that can produce a highly reliable multilayer ceramic capacitor, as well as a ceramic green sheet slurry, a ceramic green sheet, and a multilayer ceramic capacitor that use the polyvinyl acetal resin.

Claims

1. In GPC measurement using a differential refractive index detector, the molecular weight ratio calculated from the following formula (1) using the z-average molecular weight Mz(THF) and weight-average molecular weight Mw(THF) obtained using THF as a mobile phase and the weight-average molecular weight Mw(NMP) obtained using NMP as a mobile phase is 1.8 or less, and １３ A polyvinyl acetal resin, in which the ratio of the peak integral value of the methylene C atom shown in (a)' of a diad represented by the following formula (a) to the sum of the peak integral values ​​of the methylene C atoms shown in (b)' and (c)' of a diad represented by the following formula (b) and formula (c) is 0.29 or more and 0.37 or less, as obtained by C-NMR (nuclear magnetic resonance) measurement. [Mz(THF)-Mw(THF)] / Mw(NMP) (1) 【Chemistry 1】 In formula (b) and formula (c), R is each independently hydrogen or a hydrocarbon group having 1 to 20 carbon atoms.

2. 2. The polyvinyl acetal resin according to claim 1, wherein the amount of hydroxyl groups is from 28 mol % to 35 mol %.

3. 3. The polyvinyl acetal resin according to claim 1, which has a weight average molecular weight Mw(THF) of 200,000 or more and 500,000 or less.

4. 3. The polyvinyl acetal resin according to claim 1 or 2, which has a weight average molecular weight Mw(NMP) of 270,000 or more.

5. A slurry for a ceramic green sheet, comprising the polyvinyl acetal resin according to claim 1 or 2, an organic solvent, and ceramic powder.

6. A ceramic green sheet obtained by using the slurry for ceramic green sheet according to claim 5.

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

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