Polyvinyl acetal resin

Abstract

To provide a polyvinyl acetal resin which enables production of a ceramic green sheet having high mechanical strength and suitable surface roughness, and enables manufacture of a laminated ceramic capacitor having excellent reliability, a slurry for a ceramic green sheet, a ceramic green sheet, and a laminated ceramic capacitor.SOLUTION: There is provided a polyvinyl acetal resin, in which in GPC measurement using a differential refractive index detector, a hydroxyl group amount conversion wave number width calculated based on a peak within a range of 3,050 to 3,750 cm-1 in an IR absorption spectrum measured by an infrared spectrophotometer, in which a z average molecular weight (THFMz) obtained using THF as a moving phase, and a z average molecular weight (NMPMz) obtained using NMP as a moving phase satisfy the following expression (1), is within a predetermined range. Expression (1): THFMz-NMPMz<470,000.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, vinyl ester unit content, 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 the polyvinyl acetal resins described in Patent Documents 1 and 2 are used, there is a problem that the strength of the resulting ceramic green sheet is insufficient. Another problem is that the surface roughness of the resulting ceramic green sheets decreases.

[0006] An object of the present invention is to provide a polyvinyl acetal resin that can produce ceramic green sheets having high mechanical strength and suitable surface roughness, 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 relates to a polymer having a z-average molecular weight (THFMz) obtained by using THF as a mobile phase in GPC measurement with a differential refractive index detector and a z-average molecular weight (NMPMz) obtained by using NMP as a mobile phase, which satisfies the following formula (1), and in an IR absorption spectrum measured with an infrared spectrophotometer, the z-average molecular weight (Z-average molecular weight) satisfies the following formula (1): -1 When the minimum transmittance of the peak within the range is X (%), among the wave numbers showing transmittance a (%) that satisfies [100-(100-X) / 2], the wave number on the low wave number side is A and the wave number on the high wave number side is B. 1 The polyvinyl acetal resin has a hydroxyl group amount converted wave number width of 8.3 to 9.4, which is calculated using the amount of hydroxyl groups measured by 1 H-NMR and calculated by the following formula (2): THFMz-NMPMz<470000 (1) Hydroxyl group amount equivalent wavenumber width (cm -1 / mol%) = [(BA) / hydroxyl group content] (2) In the present disclosure 2, the A is 3275 cm -1 Above, 3305cm -1 The polyvinyl acetal resin according to the present disclosure is as follows: Disclosure 3 relates to the above A, B and 1 The polyvinyl acetal resin according to Disclosure 1 or 2 has a hydroxyl group-acetal group amount converted wavenumber width of 0.120 to 0.135, calculated by the following formula (3) using the hydroxyl group amount and acetal group amount measured by H-NMR: Hydroxyl group acetal group amount converted wave number width (cm -1 / mol% / mol%) = [(BA) / amount of hydroxyl groups / amount of acetal groups] (3) Disclosure 4 is a polyvinyl acetal resin according to any one of Disclosures 1 to 3, wherein a 5% by mass solution of the polyvinyl acetal resin in a 1:1 mixed solvent of ethanol and toluene has a solution viscosity of 64 mPa s or more and 2000 mPa s or less, as measured using a Brookfield viscometer at a solution temperature of 20°C. Disclosure 5 of the present invention is the polyvinyl acetal resin according to any one of Disclosures 1 to 4 of the present invention, wherein the amount of hydroxyl groups is 18 mol % or more and 40 mol % or less. Disclosure 6 of the present invention is the polyvinyl acetal resin according to any one of Disclosures 1 to 5 of the present invention, wherein the amount of acetyl groups is 0.1 mol % or more and 20 mol % or less. Disclosure 7 is a slurry for a ceramic green sheet, containing the polyvinyl acetal resin according to any one of Disclosures 1 to 6, an organic solvent, and ceramic powder. The eighth aspect of the present disclosure is a ceramic green sheet obtained by using the slurry for the ceramic green sheet according to the seventh aspect of the present disclosure. Disclosure 9 is a multilayer ceramic capacitor obtained using the ceramic green sheet according to Disclosure 8. The present invention will be described in detail below.

[0008] As a result of extensive research, the present inventors have found that the z-average molecular weight measured by changing the solvent of the mobile phase satisfies a predetermined relationship, and the IR absorption spectrum measured by an infrared spectrophotometer has a peak at 3050 to 3750 cm -1 The inventors have found that a polyvinyl acetal resin having a peak wavenumber width within a predetermined range has high mechanical strength, can provide a ceramic green sheet with a suitable surface roughness, and can fabricate a multilayer ceramic capacitor with excellent reliability, and have completed the present invention.

[0009] The polyvinyl acetal resin of the present invention has a z-average molecular weight (THFMz) obtained by using THF as a mobile phase in GPC measurement with a differential refractive index detector, and a z-average molecular weight (NMPMz) obtained by using NMP as a mobile phase, which satisfy the following formula (1): -1 When the minimum transmittance of the peak within the range is X (%), among the wave numbers showing transmittance a (%) that satisfies [100-(100-X) / 2], the wave number on the low wave number side is A and the wave number on the high wave number side is B. 1The hydroxyl group amount converted wave number width calculated by the following formula (2) using the amount of hydroxyl groups measured by 1 H-NMR is 8.3 to 9.4. THFMz-NMPMz<470000 (1) Hydroxyl group amount equivalent wavenumber width (cm -1 / mol%) = [(BA) / hydroxyl group content] (2) By using such a polyvinyl acetal resin, it is possible to obtain a ceramic green sheet having high strength and suitable surface roughness.

[0010] The polyvinyl acetal resin of the present invention has a z-average molecular weight (THFMz) and a z-average molecular weight (NMPMz) that satisfy the above formula (1) when measured by GPC using a differential refractive index detector. By ensuring that the z-average molecular weight falls within the above range, the variation in molecular weight can be narrowed, thereby reducing the surface roughness of the ceramic green sheet. The THFMz-NMPMz is preferably 100 or more, more preferably 1000 or more, and is preferably less than 470,000, more preferably less than 450,000. In the present invention, THFMz-NMPMz serves as an index of the narrowness of the variation in apparent molecular weight due to hydrogen bonding. The above-mentioned THFMz-NMPMz can be calculated by measuring the z-average molecular weight (THFMz) obtained by gel permeation chromatography (GPC) measurement using tetrahydrofuran as the mobile phase and solvent and a refractive index detector as the detector, using THF as the mobile phase, and then measuring the z-average molecular weight (NMPMz) obtained by GPC measurement using N-methylpyrrolidone as the mobile phase and solvent and a refractive index detector as the detector, using NMP as the mobile phase, and calculating THFMz-NMPMz. The column used for measuring the THFMz may be TSKgel SuperHZM-H (manufactured by Tosoh Corporation), and the column used for measuring the NMPMz may be LF-804 (manufactured by Shodex Corporation).

[0011] The polyvinyl acetal resin of the present invention preferably has a z-average molecular weight (THFMz) obtained using THF as a mobile phase of 300,000 or more and 2,000,000 or less. By setting the THFMz within this range, it is possible to suppress variations in strength of ceramic green sheets. The THFMz is more preferably 400,000 or more and more preferably 1,200,000 or less.

[0012] The polyvinyl acetal resin of the present invention preferably has a z-average molecular weight (NMPMz) obtained using NMP as a mobile phase of 300,000 or more and 1,500,000 or less. By setting the NMPMz within this range, variation in the ceramic green sheet can be suppressed. The NMPMz is more preferably 400,000 or more and more preferably 1,000,000 or less.

[0013] The THFMz-NMPMz can be adjusted by, for example, 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 THFMz-NMPMz can be adjusted by changing the cooling temperature, cooling time, reaction temperature, reaction time, holding (aging) temperature, and holding (aging) time during the acetalization reaction described below, and particularly by changing the reaction temperature, reaction time, cooling temperature, and cooling time.

[0014] The polyvinyl acetal resin of the present invention has an IR absorption spectrum measured by an infrared spectrophotometer, which has a wave number of 3050 to 3750 cm -1 When the minimum transmittance of the peak within the range is X (%), among the wave numbers showing transmittance a (%) that satisfies [100-(100-X) / 2], the wave number on the low wave number side is A and the wave number on the high wave number side is B. 1 The hydroxyl group amount converted wave number width calculated by the above formula (2) using the hydroxyl group amount measured by 1 H-NMR is 8.3 to 9.4. By setting the content within the above range, the strength of the ceramic green sheet can be improved. The lower limit of the wavenumber width is preferably 8.3, more preferably 8.35, and the upper limit is preferably 9.4, more preferably 9.35. In the present invention, the wavenumber width serves as an index of the amount of hydrogen bonding between resins. The IR absorption spectrum can be measured by a transmission method using a Fourier transform infrared spectrophotometer (such as HORIBA's "FT-720" or JASCO's "FT / IR-4000") at 20°C.

[0015] The polyvinyl acetal resin of the present invention is 1 The hydroxyl group-acetal group amount converted wave number width calculated by the above formula (3) using the hydroxyl group amount and acetal amount measured by H-NMR is preferably 0.120 to 0.135. By setting the content within the above range, the strength of the ceramic green sheet can be improved. The lower limit of the hydroxyl group-acetal group amount converted wave number width is more preferably 0.122, even more preferably 0.123, and the upper limit is more preferably 0.134, even more preferably 0.133.

[0016] In the analysis of polyvinyl acetal resin using the above infrared spectrophotometer, the spectrum originating from the stretching vibration of the CH bond of polyvinyl acetal resin was observed at 2980 cm -1 The above peak analysis firstly revealed that the minimum transmittance of the peak due to the stretching vibration of the C-H bond is around 2500 cm -1 and 3050cm -1 The film thickness of the measurement sample is adjusted so that it is 20% of the baseline when the line connecting the lines is connected. -1 A baseline is drawn for the peaks that appear within this range, and the data is corrected so that the transmittance at both ends of the peak is 100%.

[0017] An example of the IR absorption spectrum of the polyvinyl acetal resin of the present invention measured with an infrared spectrophotometer at 20° C. is shown in Fig. 1. In Fig. 1, the vertical axis represents transmittance and the horizontal axis represents wavenumber. In the IR absorption spectrum shown in Figure 1, the minimum transmittance X is 65.7%. The transmittance a that satisfies [100-(100-X) / 2] is 82.85%, and the wavenumber A on the low wavenumber side is 3297 cm -1 , the wave number B on the high wave number side is 3557 cm -1 In the above case, if the amount of hydroxyl groups is 30 mol%, the wavenumber width converted to the amount of hydroxyl groups [(BA) / amount of hydroxyl groups] is 8.67 (cm -1 / mol%). The above wave number A is 3275 cm -1 More than 3280cm is preferable. -1 More than 3305cm is preferable. -1 Preferably below 3300cm -1 The following is preferred: The wave number B is 3530 cm -1 More than 3550cm is preferable. -1 More than 3600cm is preferable. -1 The following is preferable: 3580cm -1 The following is preferred: The transmittance a is preferably 80% or more and 85% or less.

[0018] The wavenumber width 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. The wavenumber width can be adjusted by changing the cooling temperature, cooling time, cooling rate, temperature rise rate, reaction temperature, reaction time, holding (aging) temperature, and holding (aging) time during the acetalization reaction described below, and in particular by changing the cooling temperature and cooling time.

[0019] The polyvinyl acetal resin of the present invention preferably has a solution viscosity of 64 mPa s or more and 2000 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. The viscosity is more preferably 64 mPa·s or more, and even more preferably 65 mPa·s or more, from the viewpoint of improving the tensile strength. The viscosity is more preferably 2000 mPa·s or less, and even more preferably 1800 mPa·s or less, from the viewpoint of improving the viscosity stability of the ceramic slurry composition. 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.

[0020] 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.

[0021] The polyvinyl acetal resin of the present invention preferably has a structural unit having an acetal group represented by the following formula (4), a structural unit having a hydroxyl group represented by the following formula (5), and a structural unit having an acetyl group represented by the following formula (6).

[0022] [ka] In the above formula (4), R 1 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.

[0023] In the above formula (4), 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.

[0024] In the polyvinyl acetal resin of the present invention, the content of the structural unit having the acetal group represented by the above formula (4) (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 %. By setting the hydroxyl group amount within the above range, the wave number width calculated by converting the amount of hydroxyl groups into the amount of acetal groups can be set within a predetermined range. 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.

[0025] 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 (5) (hereinafter also referred to as "hydroxyl group amount") is preferably 18 mol % in lower limit and 40 mol % in upper limit. When the amount of hydroxyl groups is 18 mol % or more, the polyvinyl acetal resin can have high toughness, and when the amount of hydroxyl groups is 40 mol % or less, the solubility in organic solvents can be sufficiently improved. The lower limit of the hydroxyl group amount is more preferably 22 mol % and the upper limit is more preferably 38 mol %. That is, the hydroxyl group amount is preferably 18 to 40 mol %, and more preferably 22 to 38 mol %. By setting the hydroxyl group amount within the above range, the hydroxyl group amount converted wave number width and the hydroxyl group amount converted wave number width of the acetal group amount can be set within a predetermined range. The amount of hydroxyl groups is, for example, 1 It can be measured by H-NMR.

[0026] 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 (6) (hereinafter also referred to as "acetyl group amount") is preferably 0.1 mol % in lower limit and 20.0 mol % in upper limit. When the acetyl group content is 0.1 mol% or more, the increase in viscosity of the slurry composition for a ceramic green sheet due to intramolecular and intermolecular hydrogen bonding of hydroxyl groups in the polyvinyl acetal resin can be suppressed.When the acetyl group content is 20.0 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 18.0 mol %. That is, the acetyl group amount is preferably 0.1 to 20.0 mol %, and more preferably 0.5 to 18.0 mol %. The amount of acetyl groups is, for example, 1 It can be measured by H-NMR.

[0027] 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.

[0028] The polyvinyl acetal resin of the present invention can usually be produced by acetalizing a polyvinyl alcohol resin.

[0029] 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.

[0030] 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 99.9 mol % or less, and even more preferably 78 mol % or more and 99.5 mol % or less. That is, the saponification degree is preferably 76 to 99.9 mol %, and more preferably 78 to 99.5 mol %.

[0031] 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 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] The acetalization reaction is preferably carried out by lowering the temperature to a predetermined temperature and maintaining it thereat (cooling step), and then raising the temperature to a predetermined temperature and maintaining it thereat (reaction step). The cooling time in the cooling step is preferably 30 minutes or more and 5 hours or less, and more preferably 1 hour or more and 3 hours or less. The cooling temperature in the cooling step is preferably 8°C or higher and 20°C or lower, and more preferably 10°C or higher and 17°C or lower. Furthermore, the cooling rate is preferably 0.2°C / min or more and 3°C / min or less, and more preferably 0.5°C / min or more and 2°C / min or less. By setting the cooling time and cooling temperature as described above, the wave number width can be set within a predetermined range.

[0036] The reaction time in the reaction step is preferably 1 hour or more and 12 hours or less, and more preferably 2 hours or more and 6 hours or less. The reaction temperature in the above reaction step is preferably 47°C or higher and 58°C or lower, and more preferably 50°C or higher and 55°C or lower. The temperature rise rate is preferably 0.05° C. / min or more and 1.5° C. / min or less, and more preferably 0.1° C. / min or more and 1° C. / min or less. By setting the reaction time and reaction temperature as described above, the THFMz-NMPMz can be adjusted to fall within a predetermined range.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] The method for applying the slurry composition for a 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.

[0051] 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.

[0052] 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.

[0053] 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]

[0054] According to the present invention, it is possible to obtain a ceramic green sheet having high mechanical strength and suitable surface roughness, and it is possible to provide a polyvinyl acetal resin, a slurry for a ceramic green sheet, a ceramic green sheet, and a multilayer ceramic capacitor that can produce a highly reliable multilayer ceramic capacitor. [Brief explanation of the drawings]

[0055] [Figure 1] 1 is an example of an IR absorption spectrum obtained by measuring the IR absorption spectrum of a polyvinyl acetal resin of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0056] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0057] Example 1 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average degree of polymerization 1700, degree of saponification 99.1 mol%) and dissolved by stirring at 90°C for approximately 2 hours. The solution was cooled at 1°C / min and maintained at 17°C for 1 hour. The temperature was then raised again to 50°C at 0.5°C / min, and 220 g of 35 wt% hydrochloric acid and 180 g of n-butylaldehyde were added thereto and maintained for 6 hours to carry out an acetalization reaction [reaction step]. The mixture was then neutralized, washed with water, and dried by conventional methods to obtain a white powder of polyvinyl acetal resin.

[0058] (Preparation of ceramic green sheets) 2 parts by weight of the obtained polyvinyl acetal resin and 2 parts by weight of dioctyl phthalate (DOP) were added to 96 parts by weight of an ethanol / toluene mixed solvent (weight ratio 1:1), and dissolved with stirring to prepare a resin solution. Furthermore, 3 parts by weight of polyvinyl acetal resin "BL-1" (manufactured by Sekisui Chemical Co., Ltd.) was added to 40 parts by weight of an ethanol / toluene mixed solvent (weight ratio 1:1) and dissolved by stirring. Next, 100 parts by weight of barium titanate powder (BT01, manufactured by Sakai Chemical Industry Co., Ltd.) was added and stirred for 180 minutes in a bead mill (Ready Mill manufactured by Imex Co., Ltd.) to prepare an inorganic dispersion. The resulting inorganic dispersion was mixed with 100 parts by weight of the resin solution and stirred in a bead mill to obtain a slurry composition. Sampling was performed every 5 minutes during stirring, and 0.1 parts by weight of the resulting slurry composition was added to 10 parts by weight of an ethanol / toluene mixed solvent (1:1 by weight ratio) and stirred in an ultrasonic disperser (US-303, manufactured by SND Corporation) to prepare a dispersion evaluation solution. Particle size distribution was measured using a laser diffraction particle size analyzer (LA-910, manufactured by Horiba, Ltd.), and stirring was stopped when the D50 value of the particle size distribution reached 1.0 μm. The obtained slurry 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.

[0059] Example 2 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average degree of polymerization 1700, degree of saponification 99.2 mol%) and dissolved by stirring at 90°C for approximately 2 hours. The solution was cooled at 1°C / min and then maintained at 10°C for 1 hour. The temperature was then raised again to 50°C at 0.5°C / min, and 220 g of 35 wt% hydrochloric acid and 180 g of n-butylaldehyde were added thereto and maintained for 6 hours to carry out an acetalization reaction [reaction step]. The mixture was then neutralized, washed with water, and dried using standard methods to obtain a white powder of polyvinyl acetal resin. Ceramic green sheets were produced in the same manner as in Example 1, except that the obtained polyvinyl acetal resin was used.

[0060] Example 3 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average degree of polymerization 1700, degree of saponification 99.2 mol%) and dissolved by stirring at 90°C for approximately 2 hours. The solution was cooled at 1°C / min and then maintained at 10°C for 1 hour. The temperature was then raised again to 55°C at 0.5°C / min, and 220 g of 35 wt% hydrochloric acid and 180 g of n-butylaldehyde were added thereto and maintained for 6 hours to carry out an acetalization reaction [reaction step]. The mixture was then neutralized, washed with water, and dried by conventional methods to obtain a white powder of polyvinyl acetal resin. Ceramic green sheets were produced in the same manner as in Example 1, except that the obtained polyvinyl acetal resin was used.

[0061] Example 4 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average degree of polymerization 1700, degree of saponification 99.2 mol%) and dissolved by stirring at 90°C for approximately 2 hours. The solution was cooled at 1°C / min and maintained at 17°C for 1 hour. The temperature was then raised again to 55°C at 0.5°C / min, and 220 g of 35 wt% hydrochloric acid and 180 g of n-butylaldehyde were added thereto and maintained for 6 hours to carry out an acetalization reaction [reaction step]. The mixture was then neutralized, washed with water, and dried by conventional methods to obtain a white powder of polyvinyl acetal resin. Ceramic green sheets were produced in the same manner as in Example 1, except that the obtained polyvinyl acetal resin was used.

[0062] Example 5 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average degree of polymerization 1700, degree of saponification 99.4 mol%) and dissolved by stirring at 90°C for approximately 2 hours. This solution was cooled at 1°C / min and maintained at 17°C for 3 hours. The temperature was then raised again to 50°C at 0.5°C / min, and 220 g of 35 wt% hydrochloric acid and 180 g of n-butylaldehyde were added thereto and maintained for 6 hours to carry out an acetalization reaction [reaction step]. The mixture was then neutralized, washed with water, and dried by conventional methods to obtain a white powder of polyvinyl acetal resin. Ceramic green sheets were produced in the same manner as in Example 1, except that the obtained polyvinyl acetal resin was used.

[0063] Example 6 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average degree of polymerization 1700, degree of saponification 99.1 mol%) and dissolved by stirring at 90°C for approximately 2 hours. The solution was cooled at 1°C / min and then maintained at 10°C for 1 hour. The temperature was then raised again to 50°C at 0.5°C / min, and 220 g of 35 wt% hydrochloric acid and 180 g of n-butylaldehyde were added thereto and maintained for 3 hours to carry out an acetalization reaction [reaction step]. The mixture was then neutralized, washed with water, and dried using standard methods to obtain a white powder of polyvinyl acetal resin. Ceramic green sheets were produced in the same manner as in Example 1, except that the obtained polyvinyl acetal resin was used.

[0064] (Comparative Example 1) 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average degree of polymerization 1700, degree of saponification 99.1 mol%) and dissolved by stirring at 90°C for approximately 2 hours. This solution was not cooled below the reaction temperature but was cooled to 50°C. Next, 220 g of hydrochloric acid with a concentration of 35 wt% and 180 g of n-butyl aldehyde were added to the solution and maintained for 6 hours to carry out an acetalization reaction [reaction step]. Thereafter, the solution was neutralized, washed with water, and dried by conventional methods to obtain a white powder of polyvinyl acetal resin. Ceramic green sheets were produced in the same manner as in Example 1, except that the obtained polyvinyl acetal resin was used.

[0065] (Comparative Example 2) 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average degree of polymerization 1700, saponification degree 99.4 mol%) and dissolved by stirring at 90°C for approximately 2 hours. The solution was cooled at 1°C / min and maintained at 23°C for 1 hour. The temperature was then raised again to 55°C at 0.5°C / min, and 220 g of 35 wt% hydrochloric acid and 180 g of n-butylaldehyde were added thereto and maintained for 6 hours to carry out an acetalization reaction [reaction step]. The mixture was then neutralized, washed with water, and dried by conventional methods to obtain a white powder of polyvinyl acetal resin. Ceramic green sheets were produced in the same manner as in Example 1, except that the obtained polyvinyl acetal resin was used.

[0066] (Comparative Example 3) 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average degree of polymerization 1700, degree of saponification 99.0 mol%) and dissolved by stirring at 90°C for approximately 2 hours. The solution was cooled at 1°C / min and maintained at 17°C for 1 hour. The temperature was then raised again to 40°C at 0.5°C / min, and 220 g of 35 wt% hydrochloric acid and 180 g of n-butylaldehyde were added thereto and maintained for 6 hours to carry out an acetalization reaction [reaction step]. The mixture was then neutralized, washed with water, and dried by conventional methods to obtain a white powder of polyvinyl acetal resin. Ceramic green sheets were produced in the same manner as in Example 1, except that the obtained polyvinyl acetal resin was used.

[0067] Comparative Example 4 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average degree of polymerization 1700, degree of saponification 99.2 mol%) and dissolved by stirring at 90°C for approximately 2 hours. The solution was cooled at 1°C / min and then maintained at 5°C for 1 hour. The temperature was then raised again to 50°C at 0.5°C / min, and 220 g of 35 wt% hydrochloric acid and 180 g of n-butylaldehyde were added thereto and maintained for 6 hours to carry out an acetalization reaction [reaction step]. The mixture was then neutralized, washed with water, and dried by conventional methods to obtain a white powder of polyvinyl acetal resin. Ceramic green sheets were produced in the same manner as in Example 1, except that the obtained polyvinyl acetal resin was used.

[0068] (Comparative Example 5) 3000 g of pure water was added to 300 g of polyvinyl alcohol resin (average degree of polymerization 1700, degree of saponification 99.1 mol%) and dissolved by stirring at 90°C for approximately 2 hours. This solution was cooled at 1°C / min and maintained at 10°C for 1 hour. The temperature was then raised again to 65°C at 0.5°C / min, and 220 g of 35 wt% hydrochloric acid and 180 g of n-butylaldehyde were added and maintained for 6 hours to carry out an acetalization reaction [reaction step]. The mixture was then neutralized, washed with water, and dried using standard methods to obtain a white powder of polyvinyl acetal resin. Ceramic green sheets were produced in the same manner as in Example 1, except that the obtained polyvinyl acetal resin was used.

[0069] (evaluation) The polyvinyl acetal resins and ceramic green sheets obtained in the examples and comparative examples were evaluated as follows, and the results are shown in Table 1.

[0070] (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.

[0071] (1-2)z average molecular weight (THFMz, NMPMz) measurement The resulting polyvinyl acetal resin was dissolved in tetrahydrofuran (THF) at a concentration of 0.2 wt% and passed through a 0.45 μm pore size PTFE filter. The resulting solution was analyzed using a GPC system HLC-8220 (Tosoh Corporation) with a THF mobile phase, a Bryce-type double-pass refractive index detector (Tosoh Corporation), and a TSKgel Super HZM-H (Tosoh Corporation) column 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 (THFMz). 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 using a GPC apparatus GPC-101 (Shodex Corporation) with NMP as the mobile phase, a differential refractive index detector RI-715 (Shodex Corporation) as the detector, and an LF-804 (Shodex Corporation) as the column at a flow rate of 0.5 mL / min. The measurement results were calibrated using a molecular weight calibration curve prepared using monodisperse polystyrene standards to obtain the z-average molecular weight NMPMz. From the obtained THFMz and NMPMz, "THFMz-NMPMz" was calculated.

[0072] (1-3) IR absorption spectrum The obtained polyvinyl acetal resin was dissolved in a 1:1 ethanol / toluene mixed solution by weight, and then coated onto a PET film. -1 The film thickness of the measurement sample was adjusted so that the minimum transmittance of the peak appearing around 20% was 20%, and a polyvinyl acetal resin sheet was obtained. The IR absorption spectrum of the obtained polyvinyl acetal resin sheet was measured using an infrared spectrophotometer (HORIBA, FT-720) at 20°C. The measurement results showed that the IR absorption spectrum was measured at wavenumbers of 3050 to 3750 cm. -1 A baseline was drawn for the peaks that appeared within this range, and peak analysis was performed on the data corrected so that the transmittance at both ends of the peak was 100%, and the minimum transmittance X, transmittance a, and peak wavenumbers A and B were measured. 1 Using the amount of hydroxyl groups determined by H-NMR measurement, the hydroxyl group amount converted wavenumber width (cm -1 / mol%) = [(BA) / amount of hydroxyl groups] was calculated. Also, 1 The acetal group amount determined by H-NMR measurement was used to calculate the hydroxyl group-acetal group amount converted wavenumber width (cm -1 / mol%) = [(BA) / amount of hydroxyl groups / amount of acetal groups] was calculated.

[0073] (1-4) Viscosity measurement The obtained polyvinyl acetal resin was dissolved in a 1:1 ethanol / toluene mixed solution to a concentration of 5% by mass to prepare a viscosity measurement sample. The viscosity of the obtained viscosity measurement sample was measured using a B-type viscometer at a solution temperature of 20°C. The B-type viscometer used was a TVB-10 viscometer (manufactured by Toki Sangyo Co., Ltd.), and measurements were carried out with the following rotation speeds and rotors: Examples 1 to 6, Comparative Examples 1 to 5: Rotation speed 30 rpm, SPINDLE No. M1

[0074] (2) Evaluation of ceramic green sheets (2-1) Tensile modulus The tensile modulus (MPa) of the obtained ceramic green sheets was measured in accordance with JIS K 7113 using a tensile tester (AUTOGRAPH AGS-J, manufactured by Shimadzu Corporation) at a tension speed of 20 mm / min, and evaluated according to the following criteria. A: Tensile modulus of elasticity 1150 MPa or more B: Tensile modulus of elasticity is 1090 MPa or more and less than 1150 MPa C: Tensile modulus less than 1090 MPa

[0075] (2-2) Surface roughness The ten-point average roughness (Rz) of the obtained ceramic green sheets was measured in accordance with JIS B 0601 (1994) and evaluated according to the following criteria. A: Rz is 0.27 μm or less B: Rz is over 0.27 μm and 0.37 μm or less C: Rz is over 0.37 μm

[0076] [Table 1] [Industrial Applicability]

[0077] According to the present invention, it is possible to obtain a ceramic green sheet having high mechanical strength and suitable surface roughness, and it is possible to provide a polyvinyl acetal resin, a slurry for a ceramic green sheet, a ceramic green sheet, and a multilayer ceramic capacitor that can produce a highly reliable multilayer ceramic capacitor.

Claims

1. In GPC measurement using a differential refractive index detector, the z-average molecular weight (THFMz) obtained using THF as a mobile phase and the z-average molecular weight (NMPMz) obtained using NMP as a mobile phase satisfy the following formula (1), and In the IR absorption spectrum measured by an infrared spectrophotometer, the wave number is 3050 to 3750 cm －１ When the minimum transmittance of the peak within the range is X (%), among the wave numbers showing transmittance a (%) that satisfies [100-(100-X) / 2], the wave number on the low wave number side is A and the wave number on the high wave number side is B. １ A polyvinyl acetal resin having a hydroxyl group amount converted wavenumber width of 8.3 to 9.4, calculated by the following formula (2) using the amount of hydroxyl groups measured by H-NMR: THFMz-NMPMz<470000 (1) Hydroxyl group amount equivalent wavenumber width (cm －１ / mol%) = [(B - A) / amount of hydroxyl groups] (2)

2. The above A is 3275 cm －１ Above, 3305cm －１ The polyvinyl acetal resin according to claim 1, wherein:

3. The above A, B and １ 3. The polyvinyl acetal resin according to claim 1, wherein the hydroxyl group-acetal group amount converted wavenumber width calculated by the following formula (3) using the hydroxyl group amount and the acetal group amount measured by H-NMR is 0.120 to 0.135: Hydroxyl group acetal group amount converted wavenumber width (cm －１ / mol% / mol%) = [(B - A) / amount of hydroxyl groups / amount of acetal groups] (3)

4. 3. The polyvinyl acetal resin according to claim 1, wherein a 5 mass% solution of the polyvinyl acetal resin in a 1:1 mixed solvent of ethanol and toluene has a solution viscosity of 64 mPa s or more and 2,000 mPa s or less, as measured using a Brookfield viscometer at a solution temperature of 20°C.

5. 3. The polyvinyl acetal resin according to claim 1, wherein the amount of hydroxyl groups is 18 mol % or more and 40 mol % or less.

6. The polyvinyl acetal resin according to claim 1 or 2, wherein the amount of acetyl groups is 0.1 mol % or more and 20 mol % or less.

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

8. A ceramic green sheet obtained by using the slurry for ceramic green sheet according to claim 7.

9. A multilayer ceramic capacitor obtained by using the ceramic green sheet according to claim 8.

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