Polyvinyl acetal resin

Abstract

The present invention provides: a polyvinyl acetal resin with which it is possible to achieve a ceramic green sheet that has excellent adhesion and high strength over a wide temperature range; a slurry composition for ceramic green sheets, the slurry composition using the polyvinyl acetal resin; a ceramic green sheet; and a multilayer ceramic capacitor. The present invention provides a polyvinyl acetal resin which has a tanδ peak top temperature of 35°C to 80°C inclusive and a half-value width of the tanδ peak of 10.1°C to 30°C inclusive as determined by dynamic viscoelasticity measurement at 1 Hz.

Description

Polyvinyl acetal resin

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

[0002] In recent years, electronic components mounted in various electronic devices have become increasingly miniaturized and multilayered, resulting in widespread use of multilayer electronic components such as multilayer circuit boards, laminated coils, and multilayer ceramic capacitors. Multilayer ceramic capacitors, among others, are generally manufactured through the following process. First, a plasticizer, dispersant, etc. are added to a solution of a binder resin, such as polyvinyl butyral resin or poly(meth)acrylate resin, dissolved in an organic solvent. Then, ceramic raw material powder is added and uniformly mixed using a mixing device such as a bead mill or ball mill. After degassing, a ceramic slurry composition with a constant viscosity is obtained. This slurry composition is cast onto a support surface, such as a release-treated polyethylene terephthalate film or SUS plate, using a doctor blade or reverse roll coater. The resulting ceramic green sheets are then heated to remove volatiles such as the solvent, and the sheets are peeled off from the support to obtain ceramic green sheets. Next, multiple sheets of the resulting ceramic green sheets, each coated with a conductive paste for internal electrodes by screen printing, are stacked alternately and then heated and pressed together to form a laminate. Thereafter, the laminate is subjected to a process of thermally decomposing and removing binder resin components and the like contained in the laminate, a so-called degreasing process, and then 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. Also, Patent Document 2 describes a polyvinyl acetal resin having a predetermined degree of polymerization, vinyl ester unit content, and degree of acetalization, and having specific structural units.

[0004] JP 2011-236304 A International Publication No. 2012 / 023517

[0005] On the other hand, in order to increase the capacitance and miniaturization of multilayer ceramic capacitors, further thinning of ceramic green sheets is also required. To meet such demands, it is necessary to reduce structural defects by improving the organic binder. However, even the polyvinyl acetal resins described in Patent Documents 1 and 2 have a problem of increasing structural defects due to insufficient adhesion and strength, particularly over a wide temperature range from low temperatures.

[0006] The present invention aims to provide a polyvinyl acetal resin that can provide a ceramic green sheet having excellent adhesion and high strength over a wide temperature range, a slurry composition for a ceramic green sheet that uses the polyvinyl acetal resin, a ceramic green sheet, and a multilayer ceramic capacitor.

[0007] Disclosure 1 is a polyvinyl acetal resin having a tan δ peak top temperature of 35°C or higher and 80°C or lower, and a tan δ peak full width at half maximum of 10.1°C or higher and 30°C or lower, in dynamic viscoelasticity measurement at 1 Hz. Disclosure 2 is the polyvinyl acetal resin according to Disclosure 1, which has a structural unit having an alkylene oxide group. Disclosure 3 is the polyvinyl acetal resin according to Disclosure 2, which includes a polyvinyl acetal having a structural unit having an alkylene oxide group and a polyvinyl acetal having no alkylene oxide group. Disclosure 4 is the polyvinyl acetal resin according to Disclosure 2 or 3, in which the alkylene oxide group has 2 or more and 200 or less carbon atoms. Disclosure 5 is the polyvinyl acetal resin according to any one of Disclosures 2 to 4, in which the alkylene oxide group has 2 or more and 100 or less repeating units. Disclosure 6 is the polyvinyl acetal resin according to any one of Disclosures 2 to 5, wherein the alkylene oxide group is at least one selected from the group consisting of an oxyethylene group and an oxypropylene group. Disclosure 7 is the polyvinyl acetal resin according to any one of Disclosures 2 to 6, wherein the content of the structural unit having an alkylene oxide group relative to the entire polyvinyl acetal resin is 0.1 mol% to 5 mol%. Disclosure 8 is the polyvinyl acetal resin according to any one of Disclosures 2 to 7, comprising a structural unit having an acetal group, a structural unit having an acetyl group, a structural unit having a hydroxyl group, and a structural unit having the alkylene oxide group. Disclosure 9 is the polyvinyl acetal resin according to any one of Disclosures 1 to 8, wherein the content of the structural unit having a hydroxyl group relative to the entire polyvinyl acetal resin is 23 mol% to 40 mol%. Disclosure 10 is a slurry composition for a ceramic green sheet, comprising the polyvinyl acetal resin according to any one of Disclosures 1 to 9, an organic solvent, and a ceramic powder. Disclosure 11 is a ceramic green sheet obtained using the ceramic green sheet slurry composition according to Disclosure 10. Disclosure 12 is a multilayer ceramic capacitor obtained using the ceramic green sheet according to Disclosure 11. The present invention will be described in detail below.

[0008] As a result of extensive investigations, the present inventors have found that by setting the peak top temperature and peak half width of tan δ within predetermined ranges, it is possible to obtain a polyvinyl acetal resin that can provide a ceramic green sheet with excellent adhesion and high strength over a wide temperature range, and a slurry composition for a ceramic green sheet that uses the polyvinyl acetal resin, a ceramic green sheet, and a multilayer ceramic capacitor, and have thus completed the present invention.

[0009] The polyvinyl acetal resin of the present invention has a tan δ peak top temperature of 35°C or higher and 80°C or lower in dynamic viscoelasticity measurement at 1 Hz. By setting the temperature to 35°C or higher, sheet strength under normal room temperature conditions can be maintained, and by setting the temperature to 80°C or lower, adhesion at low temperatures can be maintained. The preferred lower limit of the tan δ peak top temperature is 40°C, more preferably 45°C, even more preferably 50°C, still more preferably 55°C, and preferably 79°C, more preferably 75°C, even more preferably 70°C, and still more preferably 60°C. The tan δ peak top temperature is the temperature value at the peak top of tan δ when dynamic viscoelasticity is measured using, for example, a DMA (manufactured by IT Measurement Co., Ltd.) under conditions of a temperature range of 30°C to 150°C, a heating rate of 6°C / min, and a frequency of 1 Hz.

[0010] The polyvinyl acetal resin of the present invention has a tan δ peak half width of 10.1°C or more and 30°C or less in dynamic viscoelasticity measurement at 1 Hz. By setting the temperature to 10.1°C or more, adhesion can be maintained at lower temperatures, and by setting the temperature to 30°C or less, sheet strength can be maintained at low temperatures. The preferred lower limit of the tan δ peak half width is 10.3°C, more preferably 10.5°C, even more preferably 11°C, still more preferably 11.5°C, and preferably 29°C, more preferably 28°C, even more preferably 27°C, and still more preferably 25°C. The tan δ peak half width is the half width of the tan δ peak when dynamic viscoelasticity is measured, for example, using a DMA (manufactured by IT Measurement Co., Ltd.) under conditions of a temperature range of 30°C to 150°C, a heating rate of 6°C / min, and a frequency of 1 Hz. The half-width refers to the peak width at half the height (50%) of the observed peak. If the peak shape is inclined and it is difficult to measure the half-width, the half-width is measured after performing baseline correction using the value of the peak top ±30°C.

[0011] The polyvinyl acetal resin of the present invention is subjected to dynamic viscoelasticity measurement under conditions of a temperature range of 30°C to 150°C, a heating rate of 6°C / min, and a frequency of 1 Hz, followed by baseline correction, to obtain a peak curve of tan δ shown in Figure 1, from which the peak top temperature and peak half-width of tan δ can be determined. Note that, when the above dynamic viscoelasticity measurement is performed on a polyvinyl acetal resin, a single peak is usually obtained, and therefore, in the present invention, it is preferable not to include cases in which multiple peaks are detected.

[0012] The polyvinyl acetal resin of the present invention preferably has a storage modulus E' at 60°C of 500,000 Pa or more. By setting the storage modulus E' at 500,000 Pa or more, sheet strength at high temperatures can be maintained. A more preferred lower limit of the storage modulus E' at 60°C is 1,000,000 Pa, and a preferred upper limit is 2,000,000,000 Pa. The storage modulus E' at 60°C is a measured value of the storage modulus E' at 60°C when measured, for example, using a DMA (manufactured by IT Measurement Co., Ltd.) under conditions of a temperature range of 30°C to 150°C, a heating rate of 6°C / min, and a frequency of 1 Hz.

[0013] The tan δ peak-top temperature, peak half-width, and storage modulus E' at 60°C can be adjusted by, for example, appropriately setting the modified species, degree of saponification, and aldehyde species of the raw polyvinyl alcohol resin, the conditions of the acetalization reaction, the amount of acetal groups, the amount of hydroxyl groups, the amount of acetyl groups, and the content of structural units having alkylene oxide groups in the polyvinyl acetal resin. When a modified polyvinyl alcohol resin is used as the raw polyvinyl alcohol resin, the tan δ peak-top temperature, peak half-width, and storage modulus E' at 60°C can be adjusted by mixing an unmodified polyvinyl alcohol resin with a modified polyvinyl alcohol resin or by changing the ratio of the modified polyvinyl alcohol resins. In particular, it is preferable to use an alkylene oxide-modified polyvinyl alcohol resin as the modified polyvinyl alcohol resin. In the present invention, when a mixture of multiple polyvinyl alcohol resins is used as the raw polyvinyl alcohol resin, the resin obtained after the acetalization reaction is referred to as a "polyvinyl acetal resin." For example, when a raw material containing a mixture of an unmodified polyvinyl alcohol resin and a modified polyvinyl alcohol resin is acetalized, a polyvinyl acetal resin is obtained. The polyvinyl acetal resin thus obtained is a polyvinyl acetal resin containing a modified polyvinyl acetal and an unmodified polyvinyl acetal.

[0014] The polyvinyl acetal resin of the present invention preferably contains a polyvinyl acetal having a structural unit having an alkylene oxide group and a polyvinyl acetal having no alkylene oxide group. １ This can be confirmed by combining composition analysis by H-NMR.

[0015] The polyvinyl acetal resin of the present invention usually has a structural unit having a hydroxyl group represented by the following formula (1), a structural unit having an acetyl group represented by the following formula (2), and a structural unit having an acetal group represented by the following formula (3).

[0016]

[0017] In the above formula (3), R １ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.

[0018] Examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl 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, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, an eicosyl group, etc. Of these, a methyl group, an ethyl group, and a propyl group are preferred.

[0019] In the polyvinyl acetal resin of the present invention, the content of the structural unit having an acetal group represented by the above formula (3) relative to the entire polyvinyl acetal resin (hereinafter also referred to as "acetal group amount") is preferably 60 mol% at the lower limit and 75 mol% at the upper limit. When the acetal group amount is 60 mol% or more, the solubility in organic solvents can be improved. When the acetal group amount is 75 mol% or less, the polyvinyl acetal resin can have excellent adhesion. The acetal group amount is more preferably 63 mol% at the lower limit and 75 mol% at the upper limit. The acetal group amount is １The amount of acetal groups can be measured by H-NMR. Since the acetal groups of the polyvinyl acetal resin are obtained by acetalizing two hydroxyl groups of polyvinyl alcohol, the amount of acetal groups is calculated by counting the two acetalized hydroxyl groups.

[0020] In the polyvinyl acetal resin of the present invention, R １ When R in formula (3) has a methyl group, the content of this structural unit relative to the entire polyvinyl acetal resin (hereinafter also referred to as "acetoacetal group amount") preferably has a lower limit of 1 mol % and an upper limit of 75 mol %. The lower limit of the acetoacetal group amount is more preferably 10 mol % and an upper limit of 60 mol %. In addition, in the polyvinyl acetal resin of the present invention, １ When R in formula (3) has an n-propyl group, the content of this structural unit relative to the entire polyvinyl acetal resin (hereinafter also referred to as "butyral group amount") preferably has a lower limit of 1 mol % and an upper limit of 75 mol %. The butyral group amount is more preferably 10 mol % and an upper limit of 60 mol %. In the polyvinyl acetal resin of the present invention, １ When the methyl group and the n-propyl group are both contained, the ratio of the amount of the acetoacetal groups to the amount of the butyral groups [acetoacetal group amount / butyral group amount, also referred to as acetoacetal / butyl ratio] is preferably 0.06 or more and 850 or less.

[0021] 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 (2) relative to the entire polyvinyl acetal resin (hereinafter also referred to as the "acetyl group amount") is preferably 0.1 mol% at the lower limit and 15 mol% at the upper limit. When the acetyl group amount is 0.1 mol% or more, it is possible to suppress 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. When the acetyl group amount is 15 mol% or less, it is possible to improve the handleability without excessively increasing the flexibility of the polyvinyl acetal resin. The acetyl group amount is more preferably 0.3 mol% at the lower limit and 12 mol% at the upper limit. The acetyl group amount is １ It can be measured by H-NMR.

[0022] In the polyvinyl acetal resin of the present invention, the content of the structural unit having a hydroxyl group represented by the general formula (1) (hereinafter also referred to as the "hydroxyl group amount") relative to the entire polyvinyl acetal resin is preferably 23 mol% in lower limit and 40 mol% in upper limit. When the hydroxyl group amount is 23 mol% or more, the polyvinyl acetal resin can have high toughness. When the hydroxyl group amount is 40 mol% or less, the solubility in organic solvents can be sufficiently improved. The hydroxyl group amount is more preferably 23 mol% in lower limit and 36 mol% in upper limit. The hydroxyl group amount is １ It can be measured by H-NMR.

[0023] The polyvinyl acetal resin may contain, in addition to the structural units of the formulae (1), (2), and (3), a structural unit having a carboxyl group, a structural unit having a functional group such as a sulfonic acid group, an alkylene oxide group, or an amide group, or an ethylene unit. The polyvinyl acetal resin preferably contains a structural unit having an acetal group, a structural unit having an acetyl group, a structural unit having a hydroxyl group, and a structural unit having an alkylene oxide group.

[0024] The polyvinyl acetal resin of the present invention preferably has a structural unit having an alkylene oxide group.

[0025] The alkylene oxide group includes a structure represented by the following formula (4).

[0026]

[0027] In formula (4), A １ O is an oxyalkylene group having 2 to 6 carbon atoms, and m is the average number of repetitions, which is 10 to 200. ２ is an alkyl group having 1 to 8 carbon atoms or a hydrogen atom. The oxyalkylene group may be one type alone or two or more types may be mixed. * indicates the bonding position to other groups.

[0028] Above A １ The oxyalkylene group in O is preferably an oxyalkylene group having 2 to 6 carbon atoms, more preferably an oxyalkylene group having 2 to 4 carbon atoms, and even more preferably an oxyalkylene group having 2 or 3 carbon atoms. The alkylene group in the oxyalkylene group may be linear or may have a branched structure. Examples of the oxyalkylene group include an oxyethylene group, an oxypropylene group, or an oxybutylene group, and preferred are an oxyethylene group and an oxypropylene group. One type of oxyalkylene group may be used alone, or two or more types may be used in combination.

[0029] The oxyalkylene group in the alkylene oxide group preferably contains at least one of an oxyethylene group and an oxypropylene group, and also preferably contains both an oxyethylene group and an oxypropylene group. When the alkylene oxide group contains an oxyethylene group (EO) and an oxypropylene group (PO), the ratio of the oxypropylene group to the oxyethylene group (PO / EO) is preferably 1 / 49 or more and 49 / 1 or less, more preferably 1 / 9 or more and 9 / 1 or less, and even more preferably 2 / 8 or more and 8 / 2 or less, in terms of molar ratio.

[0030] The above R ２ The alkyl group in R may be linear or may have a branched structure. ２Examples of the alkyl group in the above R include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, branched butyl groups such as an n-butyl group, an s-butyl group, and a t-butyl group, an n-pentyl group, a branched pentyl group, an n-hexyl group, a branched hexyl group, branched heptyl groups such as an n-heptyl group, an isoheptyl group, and a 3-heptyl group, and branched octyl groups such as an n-octyl group, an isooctyl group, and a 2-ethylhexyl group. ２ may be either an alkyl group or a hydrogen atom. The alkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms.

[0031] The alkylene oxide group is preferably linked to the main chain via a linking group. Examples of the linking group include a single bond, an alkylene group having 1 to 10 carbon atoms, a carbonyl group, an ether bond (-O-), an ester bond (-COO-), an amide bond (-CONR-: R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms), and a hydrocarbon group which may have at least one of these bonds. The number of carbon atoms in the linking group is not particularly limited, but is preferably 10 or less, and more preferably 4 or less. The linking group does not need to have a carbon atom, as long as the linking group has 0 or more carbon atoms. Furthermore, R in -CONR- is preferably a hydrogen atom. Furthermore, the number of carbon atoms in the hydrocarbon group in the linking group is preferably 1 to 10, and more preferably 1 to 4.

[0032] The alkylene oxide group may be a single bond, an alkylene group having 1 to 10 carbon atoms, an ether bond, or a —CH ２ It is particularly preferable that the bond is formed via either -CH or -O. By forming the bond via such a linking group, the polarity of the side chain does not change significantly and the solvent solubility is not significantly affected. ２ In the case of O-, the oxygen atom may be bonded to the alkylene oxide group. ３ means.

[0033] The structural unit having an alkylene oxide group preferably has a structural unit represented by the following formula (5), and particularly preferably a structural unit represented by the following formula (6) or a structural unit represented by the following formula (7).

[0034]

[0035]

[0036] In formula (5), A １ O, R ２ , m are the same as above. ３ R in formula (5) may be a single bond, an ether bond (—O—), an ester bond (—COO—), an amide bond (—CONR—: R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms), or a hydrocarbon group which may have at least one of these bonds. ３ The number of carbon atoms in the R is preferably 0 to 10, and more preferably 0 to 4. ３ Among the above, A is preferably an ether bond (—O—) or a hydrocarbon group having at least an ether bond. １ O, R ２ , m are the same as above. １ O, R ２ , m are as described above, and therefore the explanation thereof will be omitted.

[0037] The alkylene oxide group preferably has a number of repeating units (average repeat number m) of 2 or more and 100 or less, more preferably 2 or more and 90 or less. When the alkylene oxide group contains either an oxyethylene group or an oxypropylene group, m is preferably 2 to 75, more preferably 2 to 50. When the alkylene oxide group contains an oxyethylene group and an oxypropylene group, m is preferably 2 to 75, more preferably 2 to 50.

[0038] The alkylene oxide group preferably has a carbon number (total carbon number) of 2 or more and 200 or less, more preferably 2 or more and 180 or less, and even more preferably 2 or more and 100 or less. In the case of the structure shown in formula (4) above, the carbon number means the total carbon number of formula (4) including the linking group, and in the case of the structures of formulas (5) to (7) above, the carbon number means the total carbon number of the main chain portion [—CH ２ This means the number of carbon atoms other than the —CH—.

[0039] The content of the alkylene oxide group-containing structural unit in the polyvinyl acetal resin of the present invention relative to the entire polyvinyl acetal resin is preferably 0.1 mol% or more and 5 mol% or less. When the content of the alkylene oxide group-containing structural unit is 0.1 mol% or more, adhesion can be imparted over a wide temperature range. When the content of the alkylene oxide group-containing structural unit is 5 mol% or less, high sheet strength can be maintained around room temperature. The content of the alkylene oxide group-containing structural unit is more preferably 0.2 mol% or more, even more preferably 0.5 mol% or more, more preferably 4.5 mol% or less, and even more preferably 4.0 mol% or less. The content of the alkylene oxide group-containing structural unit is １ It can be measured by H-NMR.

[0040] Examples of the structural unit having a carboxyl group include a structural unit represented by the following formula (b-1), a structural unit represented by the following formula (b-2), and a structural unit represented by the following formula (b-3).

[0041]

[0042] In the above formula (b-1), R １ｂ and R ２ｂ each independently represents an alkylene group having 0 to 10 carbon atoms; X １ｂ and X ２ｂ each independently represents a hydrogen atom, a metal atom, or a methyl group.

[0043] In the above formula (b-1), R １ｂ and R ｂ２The lower limit of the number of carbon atoms in the alkylene group represented by the formula (I) is preferably 0, the upper limit is preferably 5, the lower limit is more preferably 1, and the upper limit is more preferably 3. １ｂ and R ２ｂ may be the same or different, but are preferably different. It is also preferable that at least one of them is a single bond.

[0044] Examples of the alkylene group having 0 to 10 carbon atoms include a single bond, a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, an octamethylene group, a decamethylene group, and other linear alkylene groups, a methylmethylene group, a methylethylene group, a 1-methylpentylene group, a 1,4-dimethylbutylene group, and other branched alkylene groups, and a cyclopropylene group, a cyclobutylene group, a cyclohexylene group, and other cyclic alkylene groups. Of these, a single bond, a methylene group, an ethylene group, an n-propylene group, an n-butylene group, and other linear alkylene groups are preferred, and a single bond, a methylene group, and an ethylene group are more preferred.

[0045] In the above formula (b-1), X １ｂ and X ２ｂ When at least one of the groups is a metal atom, examples of the metal atom include a sodium atom, a lithium atom, a potassium atom, etc. Among these, a sodium atom is preferred.

[0046] The structural unit represented by the above formula (b-1) is preferably derived from an α-dicarboxy monomer. Examples of the α-dicarboxy monomer include dicarboxylic acids having a radically polymerizable unsaturated double bond, such as methylenemalonic acid, itaconic acid, 2-methyleneglutaric acid, 2-methyleneadipic acid, and 2-methylenesebacic acid, as well as metal salts and methyl esters thereof. Of these, itaconic acid, metal salts, and methyl esters thereof are preferably used. In this specification, the term "α-dicarboxy monomer" refers to a monomer having two carboxyl groups at the α-carbon position.

[0047] In the above formula (b-2), R ３ｂ , R ４ｂ and R ５ｂeach independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms; R ６ｂ represents an alkylene group having 0 to 10 carbon atoms; X ３ｂ represents a hydrogen atom, a metal atom or a methyl group.

[0048] In the above formula (b-2), R ３ｂ , R ４ｂ and R ５ｂ The lower limit of the number of carbon atoms in the alkyl group represented by the formula (I) is preferably 1, the upper limit is preferably 5, and the upper limit is more preferably 3.

[0049] R ３ｂ , R ４ｂ , R ５ｂ may be the same or different, but are preferably the same. ３ｂ , R ４ｂ and R ５ｂ is preferably a hydrogen atom.

[0050] Examples of the alkyl group having 1 to 10 carbon atoms include linear alkyl groups such as methyl, ethyl, propyl, n-butyl, n-pentyl, n-heptyl, n-octyl, n-nonyl, and n-decyl, branched alkyl groups such as isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2,2-dimethylpropyl, 1,1,3,3-tetramethylbutyl, and 2-ethylhexyl, and cycloalkyl groups such as cyclopropyl, cyclopropylmethyl, cyclobutyl, cyclopentyl, and cyclohexyl. Of these, linear alkyl groups such as methyl, ethyl, propyl, and n-butyl are preferred, with methyl and ethyl being more preferred.

[0051] R in the above formula (b-2) ６ｂ As the group, R in the above formula (b-1) １ｂ and R ２ｂ Among these, a single bond, a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, or other linear alkylene group is preferred, a single bond, a methylene group, or an ethylene group is more preferred, and a single bond is still more preferred.

[0052] In the above formula (b-2), X ３ｂWhen is a metal atom, examples of the metal atom include a sodium atom, a lithium atom, a potassium atom, etc. Among these, a sodium atom is preferred.

[0053] The structural unit represented by formula (b-2) is preferably derived from a monocarboxy monomer. Examples of the monocarboxy monomer include monocarboxylic acids having a radically polymerizable unsaturated double bond, such as acrylic acid, crotonic acid, methacrylic acid, and oleic acid, as well as metal salts and methyl esters thereof. Among these, crotonic acid, metal salts, and methyl esters thereof are preferably used.

[0054] In the above formula (b-3), R ７ｂ and R ９ｂ each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms; R ８ｂ and R １０ｂ represents an alkylene group having 0 to 10 carbon atoms; X ４ｂ and X ５ｂ represents a hydrogen atom, a metal atom or a methyl group.

[0055] In the above formula (b-3), R ７ｂ and R ９ｂ The lower limit of the number of carbon atoms in the alkyl group represented by the formula (I) is preferably 1, the upper limit is preferably 5, and the upper limit is more preferably 3.

[0056] The above R ７ｂ and R ９ｂ may be the same or different, but it is more preferable that they are the same.

[0057] R in the above formula (b-3) ７ｂ and R ９ｂ As the group, R in the above formula (b-2) ３ｂ , R ４ｂ and R ５ｂ Among them, a hydrogen atom is preferred.

[0058] R in the above formula (b-3) ８ｂ and R １０ｂ As the group, R in the above formula (b-1) １ｂ and R ２ｂAmong these, a single bond, a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, or other linear alkylene group is preferred, a single bond, a methylene group, or an ethylene group is more preferred, and a single bond is still more preferred.

[0059] In the above formula (b-3), X ４ｂ and X ５ｂ When is a metal atom, examples of the metal atom include a sodium atom, a lithium atom, a potassium atom, etc. Among these, a sodium atom is preferred.

[0060] The content of the carboxyl group-containing structural unit in the polyvinyl acetal resin relative to the entire polyvinyl acetal resin is preferably 0.1 mol% or more and 5.0 mol% or less. The content of the carboxyl group-containing structural unit is more preferably 0.5 mol% or more and more preferably 1.0 mol% or less. The content of the carboxyl group-containing structural unit is １ It can be measured by H-NMR.

[0061] Examples of the structural unit having a sulfonic acid group include a structural unit represented by the following formula (c).

[0062]

[0063] In formula (c), R １ｃ represents an alkylene group having 0 to 10 carbon atoms; X １ｃ represents a hydrogen atom, a metal atom or a methyl group.

[0064] R in the above formula (c) １ｃ As the group, R in the above formula (b-1) １ｂ and R ２ｂ Among these, a single bond, a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, or other linear alkylene group is preferred, a single bond, a methylene group, or an ethylene group is more preferred, and a single bond or a methylene group is even more preferred.

[0065] In the above formula (c), X １ｃWhen is a metal atom, examples of the metal atom include a sodium atom, a lithium atom, a potassium atom, etc. Among these, a sodium atom is preferred.

[0066] Examples of the structural unit having an amide group include a structural unit represented by the following formula (f).

[0067]

[0068] In the above formula (f), R １ｆ represents an alkyl group having 1 to 10 carbon atoms.

[0069] R in the above formula (f) １ｆ As the group, R in the above formula (b-2) ３ｂ , R ４ｂ and R ５ｂ Among them, a hydrogen atom, a methyl group, an ethyl group, a propyl group, an n-butyl group and other linear alkyl groups are preferred, and a hydrogen atom, a methyl group, and an ethyl group are more preferred.

[0070] The ethylene unit may be a structural unit represented by the following formula (g).

[0071]

[0072] In the polyvinyl acetal resin, the content of the ethylene units relative to the entire polyvinyl acetal resin (hereinafter also referred to as "ethylene content") is preferably 0.1 mol% or more, more preferably 3 mol% or more, and is preferably 20 mol% or less, more preferably 10 mol% or less. １ It can be measured by H-NMR.

[0073] In this specification, the ethylene content of a polyvinyl acetal resin means the apparent ethylene content of the entire polyvinyl acetal resin. That is, for example, when a polyvinyl acetal resin contains multiple resins having different ethylene contents, the ethylene content of the polyvinyl acetal resin can be determined by multiplying the ethylene content of each resin by the content ratio of that resin and adding up the resulting values.

[0074] In the polyvinyl acetal resin of the present invention, the content of structural units having functional groups other than the structural units of the above formulae (1), (2), and (3) and structural units having an alkylene oxide group relative to the entire polyvinyl acetal resin is preferably 0 mol % or more, more preferably 0.1 mol % or more, and even more preferably 0.5 mol % or more, and is preferably 5 mol % or less, and more preferably 3 mol % or less. １ It can be measured by H-NMR.

[0075] The polyvinyl acetal resin of the present invention has an average degree of polymerization of preferably 100 (lower limit) and more preferably 200 (lower limit). From the viewpoints of solubility in organic solvents and dissolution viscosity, the average degree of polymerization is preferably 5000 (upper limit) and more preferably 4500 (upper limit). The average degree of polymerization of the polyvinyl acetal resin is the same as that of the raw material polyvinyl alcohol. When the raw material polyvinyl alcohol is composed of two or more polyvinyl alcohols with different average degrees of polymerization, the average degree of polymerization can be calculated from the blended average degree of polymerization of the polyvinyl alcohols (average degree of polymerization determined by dividing the blend ratio proportionally). The average degree of polymerization can be measured in accordance with JIS K 6726.

[0076] The Z-average molecular weight Mz of the polyvinyl acetal resin of the present invention is preferably 2,000,000 or less. By setting the Mz within this range, good solvent solubility is achieved. The Mz is more preferably 100,000 or more, even more preferably 200,000 or more, more preferably 1,800,000 or less, and even more preferably 1,500,000 or less. The Mz can be measured by gel permeation chromatography (GPC) using N-methylpyrrolidone as a solvent and an appropriate standard (e.g., polystyrene standard).

[0077] The shape of the polyvinyl acetal resin of the present invention is not particularly limited, and examples thereof include particle, plate, and liquid shapes, with particle shape being preferred. When the polyvinyl acetal resin of the present invention is in particle shape, the average particle diameter is preferably 10 μm or more and preferably 1000 μm or less. By setting the average particle diameter within the above range, high dispersibility can be obtained. The average particle diameter is more preferably 50 μm or more and more preferably 500 μm or less. The average particle diameter refers to the secondary particle diameter and can be measured, for example, using a laser diffraction particle size analyzer (Malvern Panalytical, Mastersizer 3000).

[0078] The polyvinyl acetal resin of the present invention can usually be produced by acetalizing a polyvinyl alcohol resin. In particular, methods for producing the polyvinyl acetal resin include mixing a polyvinyl alcohol resin having a structural unit containing an alkylene oxide group with a polyvinyl alcohol resin not having a structural unit containing an alkylene oxide group, followed by acetalization. Another method includes preparing a polyvinyl alcohol resin having a structural unit containing an alkylene oxide group, followed by acetalization. Furthermore, when mixing a polyvinyl alcohol resin having a structural unit containing an alkylene oxide group with a polyvinyl alcohol resin not having a structural unit containing an alkylene oxide group, the mixing ratio of the polyvinyl alcohol resin having a structural unit containing an alkylene oxide group to the polyvinyl alcohol resin not having a structural unit containing an alkylene oxide group is preferably 1 / 49 to 49 / 1.

[0079] Examples of methods for preparing polyvinyl alcohol resins having structural units containing alkylene oxide groups include copolymerizing an alkylene oxide group-containing monomer with a vinyl ester such as vinyl acetate, followed by adding an acid or alkali to an alcohol solution of the resulting copolymer for saponification. More specifically, examples include copolymerizing a hydroxyalkyl vinyl ether containing an oxyalkylene group with vinyl acetate, followed by adding an acid or alkali to an alcohol solution of the resulting copolymer for saponification. In addition to the hydroxyalkyl vinyl ethers, poly(alkylene glycol) vinyl ethers such as dialkylene glycol vinyl ethers and trialkylene glycol monovinyl ethers may also be used. Examples of methods for adding the moiety represented by formula (4) include changing the type of alkyl vinyl ether.

[0080] The polyvinyl alcohol having a structural unit having an alkylene oxide group preferably has a saponification degree of 80.0 to 99.9 mol%. By setting the saponification degree within this range, it is possible to achieve both flexibility and solvent resistance. The lower limit of the saponification degree is more preferably 85.0 mol%, even more preferably 88.0 mol%, and the upper limit is more preferably 99.8 mol%, even more preferably 99.7 mol%, and particularly preferably 99.5 mol%.

[0081] The polyvinyl alcohol resin can be, 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. The polyvinyl alcohol resin can be fully saponified, but it 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; it can also be a partially saponified polyvinyl alcohol resin. Furthermore, the polyvinyl alcohol resin can also be 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. Examples of the polyvinyl acetate resin include ethylene-vinyl acetate copolymers.

[0082] The polyvinyl alcohol resin preferably has a degree of saponification of 80.0 to 99.9 mol%, with the lower limit of the degree of saponification being more preferably 85.0 mol%, still more preferably 88.0 mol%, and the upper limit being more preferably 99.8 mol%, still more preferably 99.7 mol%, and particularly preferably 99.5 mol%.

[0083] The acetalization is preferably carried out in an aqueous solvent, a mixed solvent of water and a water-compatible organic solvent, or an organic solvent. Examples of the water-compatible organic solvent include alcohol-based organic solvents. 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-based 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 solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methylcyclohexanone, benzophenone, and acetophenone. Examples of the lower paraffin solvents include hexane, pentane, octane, cyclohexane, and decane. Examples of the ether solvents include diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol diethyl ether. Examples of the amide solvents include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and acetanilide. Examples of the amine solvents 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.

[0084] 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.

[0085] Examples of the aldehyde used in the acetalization include aldehydes having a chain aliphatic group, a cyclic aliphatic group, or an aromatic group having 1 to 10 carbon atoms. Conventionally known aldehydes can be used as these aldehydes. The aldehyde used in the acetalization reaction is not particularly limited, and examples 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 these, preferred aldehydes are formaldehyde, acetaldehyde, butylaldehyde, 2-ethylhexylaldehyde, and n-nonylaldehyde, which have excellent acetalization reactivity and can provide a sufficient internal plasticizing effect to the resulting resin, thereby imparting good flexibility. Furthermore, formaldehyde, acetaldehyde, and butylaldehyde are more preferred because they can provide an adhesive composition that is particularly excellent in impact resistance and adhesion to metals.

[0086] The amount of aldehyde added can be appropriately set depending on the amount of acetal groups in the target polyvinyl acetal resin. In particular, an amount of aldehyde added relative to 100 mol% of polyvinyl alcohol of preferably 55 mol% to 95 mol%, more preferably 60 mol% to 90 mol%, is preferred because this allows the acetalization reaction to proceed efficiently and facilitates the removal of unreacted aldehyde. That is, the amount of aldehyde added is preferably 55 to 95 mol%, more preferably 60 to 90 mol%. Furthermore, the temperature at which the aldehyde is added (aldehyde introduction temperature) is preferably 0°C or higher, more preferably 10°C or higher, and preferably 55°C or lower, and even more preferably 50°C or lower. That is, the aldehyde introduction temperature is preferably 0 to 55°C, more preferably 10 to 50°C.

[0087] In the acetalization reaction, it is preferable to carry out a hydrolysis step using hydrochloric acid or a saponification step using sodium hydroxide before the acetalization reaction, with hydrolysis using hydrochloric acid being particularly preferred. For example, the hydrolysis step using hydrochloric acid involves dissolving polyvinyl alcohol in water with heating, adding hydrochloric acid, and then heating and stirring for a certain period of time to hydrolyze the acetyl groups contained in the polyvinyl alcohol to hydroxyl groups. The hydrolysis temperature, hydrolysis time, and amount of hydrochloric acid can be adjusted appropriately depending on the degree of saponification of the starting polyvinyl alcohol and the target degree of saponification after hydrolysis. The hydrolysis temperature is preferably 50°C or higher and 90°C or lower. The hydrolysis time is preferably 30 minutes or higher and 10 hours or lower. That is, the hydrolysis time is preferably 30 minutes to 10 hours. The amount of hydrochloric acid is preferably 10 parts by weight or higher and 250 parts by weight or lower per 100 parts by weight of polyvinyl alcohol. That is, the amount of hydrochloric acid is preferably 10 to 250 parts by weight per 100 parts by weight of polyvinyl alcohol.

[0088] The acetalization reaction is preferably carried out after the polyvinyl alcohol is heated and dissolved and cooled. The dissolution temperature when the polyvinyl alcohol is heated and dissolved is preferably 80°C or higher, more preferably 90°C or higher, and preferably 99°C or lower. The dissolution time is preferably 1 to 8 hours. Furthermore, the cooling temperature is preferably 50 to 0°C. The acetalization reaction is preferably carried out by adding an aldehyde at a predetermined temperature and then maintaining the temperature for a certain period of time. The maintenance time for the acetalization reaction is preferably 0.1 to 7 hours, more preferably 0.5 to 5 hours. That is, the maintenance time is preferably 0.1 to 7 hours, more preferably 0.5 to 5 hours. The maintenance temperature for the acetalization reaction is preferably -5 to 50°C, more preferably 5 to 40°C. That is, the maintenance temperature is preferably -5 to 50°C, more preferably 5 to 40°C.

[0089] The acetalization reaction may be carried out by adding an aldehyde at a predetermined temperature, followed by lowering the temperature at a predetermined rate, or by raising the temperature at a predetermined rate, and then maintaining the predetermined temperature for a certain period of time. The temperature lowering or heating time in the acetalization reaction is preferably 30 minutes or more and 600 minutes or less, more preferably 60 minutes or more and 500 minutes or less, and even more preferably 120 minutes or more and 400 minutes or less. That is, the temperature lowering or heating time is preferably 30 to 600 minutes, more preferably 60 to 500 minutes, and even more preferably 120 to 400 minutes. The temperature lowering or heating rate is preferably 0.1°C / min or more and 2°C / min or less. That is, the temperature lowering or heating rate is preferably 0.1 to 2°C / min. When a step of maintaining the predetermined temperature for a certain period of time (aging step) is carried out after the temperature lowering or heating, the maintaining temperature is preferably 20 to 70°C, and the maintaining time is preferably 1 to 8 hours. Regarding the neutralization after the acetalization reaction, it is preferable to use a method in which the reaction solution used in the acetalization reaction is not separated, but a neutralizing agent is directly added (continuous neutralization method).

[0090] A slurry composition for ceramic green sheets can be prepared by mixing the polyvinyl acetal resin of the present invention with an organic solvent and ceramic powder.

[0091] 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.

[0092] The content of the organic solvent in the ceramic green sheet slurry composition 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. For this reason, the content of the organic solvent is preferably 20% by weight or more and 80% by weight or less. In other words, the content of the organic solvent is preferably 20 to 80% by weight.

[0093] Examples of the ceramic powder include powders of metal or nonmetal oxides or non-oxides used in ceramic production. These powders may be single compositions, compounds, or mixtures. The constituent elements of the metal oxides or non-oxides, both cations and anions, may be single elements or multiple elements, and may further contain additives added to improve the properties of the oxides or non-oxides. Specific examples include oxides, carbides, nitrides, borides, sulfides, etc. of Li, K, Mg, B, Al, Si, Cu, Ca, Sr, Ba, Zn, Cd, Ga, In, Y, lanthanides, actinides, Ti, Zr, Hf, Bi, V, Nb, Ta, W, Mn, Fe, Co, Ni, etc. Specific examples of oxide powders containing multiple metal elements, commonly referred to as double oxides, can be classified based on their crystal structure, such as NaNbO, which has a perovskite structure. ３ , SrZrO ３ , PbZrO ３ , SrTiO ３ , BaZrO ３ , PbTiO ３ , BaTiO ３ Examples of materials that have a spinel structure include MgAl ２ O ４ , ZnAl ２ O ４ , CoAl ２ O ４ , NiAl ２ O4, MgFe ２ O ４ Examples of materials with an ilmenite structure include MgTiO ３ , MnTiO ３ , FeTiO ３ Examples of materials that have a garnet structure include GdGa ５ O １２ , Y ６ Fe ５ O １２ Among these, the modified polyvinyl acetal resin of the present invention is BaTiO ３ It exhibits high properties compared to ceramic green sheets mixed with powder.

[0094] The ceramic green sheet slurry composition may contain a plasticizer. Addition of a plasticizer can significantly improve the mechanical strength and flexibility of the resulting ceramic green sheet. Examples of the plasticizer include phthalate 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.

[0095] 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.

[0096] In the slurry 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 40 parts by weight at the upper limit, more preferably 30 parts by weight at the upper limit. That is, the content of the plasticizer is preferably 7 to 40 parts by weight, more preferably 8.5 to 30 parts by weight.

[0097] The slurry composition for a ceramic green sheet 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.

[0098] The slurry composition for a ceramic green sheet may contain, as needed, a dispersant, an antioxidant, an ultraviolet absorber, a surfactant, a filler, a release agent, and the like, and in some cases, a small amount of other resin such as an acrylic resin or a urethane resin may be added.

[0099] The method for producing the slurry composition for ceramic green sheets 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.

[0100] A ceramic green sheet is obtained by applying the above-mentioned slurry composition for a ceramic green sheet and then heating and drying it. A ceramic green sheet obtained using the slurry composition for a ceramic green sheet of the present invention also constitutes one aspect of the present invention. A ceramic electronic component can be manufactured using the above-mentioned ceramic green sheet. For example, a ceramic electronic component can be manufactured by carrying out a step of applying an electrode layer paste to the surface of a ceramic green sheet, and a step of stacking the ceramic green sheets on which the electrode layers have been formed, thermocompressing the stack, and then degreasing and firing the resulting laminate.

[0101] 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.

[0102] 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. A multilayer ceramic capacitor obtained using such a ceramic green sheet of the present invention also constitutes one aspect of the present invention.

[0103] The method for producing the ceramic electronic component includes a step of applying an electrode layer paste to the surface of the ceramic green sheet. The electrode layer paste can be obtained by dissolving, for example, a polyvinyl acetal resin, ethyl cellulose, or acrylic resin as a binder resin in an organic solvent and dispersing a conductive powder or the like. These resins may be used alone or in combination. An electrode layer paste containing a polyvinyl acetal resin is preferred because it exhibits excellent adhesion to the ceramic green sheet during the thermocompression bonding step.

[0104] In the method for producing a ceramic electronic component, the ceramic green sheets having electrode layers formed thereon are prepared as described above, and then ceramic green sheets having electrode layers formed thereon that are prepared in the same manner are stacked and thermocompression-bonded 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. Note that the thermocompression-bonding step and the steps of degreasing and firing the laminate are not particularly limited, and conventionally known methods can be used.

[0105] The present invention provides a polyvinyl acetal resin capable of producing a ceramic green sheet having excellent adhesion and high strength over a wide temperature range, a ceramic green sheet slurry composition using the polyvinyl acetal resin, a ceramic green sheet, and a multilayer ceramic capacitor. The present invention also provides a polyvinyl acetal resin having excellent storage stability and high sheet attack resistance, and a ceramic green sheet slurry using the polyvinyl acetal resin.

[0106] 1 shows a peak curve of tan δ when dynamic viscoelasticity of the polyvinyl acetal resin of the present invention is measured under conditions of a temperature range of 30° C. to 150° C., a heating rate of 6° C. / min, and a frequency of 1 Hz.

[0107] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Details of the raw material PVA used in the examples and comparative examples are shown in Table 1.

[0108] (Example 1) (Preparation of alkylene oxide-modified polyvinyl acetal resin) As a raw material PVA, a structural unit represented by formula (5) (in formula (5), A １ O is an oxyethylene group (EO), R ２ is a hydrogen atom, R ３ The alkylene oxide-modified polyvinyl alcohol resin (AO-modified PVA-1, average degree of polymerization 600, degree of saponification 99.0 mol%) having m=(a)=(a)=(a)=(b)=(c) / (d) is a single bond and m=(c)=(d)=(c)=(a)=(b) / (d) is 9.5) was used. The unmodified polyvinyl alcohol (unmodified PVA-1, average degree of polymerization 1700, degree of saponification 99.0 mol%) and the unmodified polyvinyl alcohol (unmodified PVA-2, average degree of polymerization 3300, degree of saponification 99.0 mol%) were used. When two or more raw material PVAs with different average degrees of polymerization were used, the blend average degree of polymerization was calculated by multiplying the content ratio by each degree of polymerization, and this was used as the degree of polymerization. Details of the raw material PVAs used in each example and comparative example are shown in Table 1. 90 g (30 parts by weight) of AO-modified PVA-1, 75 g (25 parts by weight) of unmodified PVA-1, and 135 g (45 parts by weight) of unmodified PVA-2 were added to 2800 g of pure water and stirred at 90°C for 2 hours to dissolve. This solution was cooled to 40°C, and 300 g of 35 wt% hydrochloric acid and 160 g of n-butyl aldehyde were added to carry out an acetalization reaction for 1 hour to precipitate the reaction product. The solution was then cooled to 30°C over 60 minutes (cooling rate: 0.167°C / min) and held at 30°C for 4 hours to complete the reaction. Without separating the reaction solution, sodium bicarbonate was directly added as a neutralizing agent to neutralize it, followed by washing with water and drying in the usual manner to obtain an alkylene oxide-modified polyvinyl acetal resin. Ion-exchanged water was used for dissolution and washing. The obtained alkylene oxide-modified polyvinyl acetal resin was analyzed using an AV400 spectrometer (manufactured by Bruker). １ The amount of acetal groups, the amount of acetyl groups, the amount of hydroxyl groups, and the amount of alkylene oxide groups (content of structural units having alkylene oxide groups, amount of AO modification) were measured by H-NMR. ６ The solution was dissolved in water to a concentration of 1.6% by weight to prepare a measurement solution. １H-NMR measurement was carried out at 80° C. Furthermore, the average particle size (secondary particle size) of the obtained alkylene oxide-modified polyvinyl acetal resin was measured using a laser diffraction particle size measuring device (Malvern Panalytical, Mastersizer 3000) and found to be 215 μm.

[0109] Example 2: AO-modified PVA-1 and unmodified polyvinyl alcohol (unmodified PVA-3, average degree of polymerization 2400, degree of saponification 99.0 mol%) were used as raw material PVA. An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 2800 g of pure water was added to 150 g (50 parts by weight) of AO-modified PVA-1 and 150 g (50 parts by weight) of unmodified PVA-3, and the mixture was stirred at 90°C for 2 hours to dissolve.

[0110] Example 3 An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 180 g (60 parts by weight) of the AO-modified PVA-1 and 120 g (40 parts by weight) of the unmodified PVA-3 were dissolved in 2,800 g of pure water by stirring at 90°C for 2 hours.

[0111] Example 4 An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 120 g (40 parts by weight) of the AO-modified PVA-1 and 180 g (60 parts by weight) of the unmodified PVA-2 were added to 2,800 g of pure water and stirred at 90°C for 2 hours to dissolve the mixture.

[0112] Example 5: AO-modified PVA-1 and unmodified polyvinyl alcohol (unmodified PVA-4, average degree of polymerization: 500, degree of saponification: 99.0 mol%) were used as raw material PVA. An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 2800 g of pure water was added to 150 g (50 parts by weight) of AO-modified PVA-1 and 150 g (50 parts by weight) of unmodified PVA-4, and the mixture was stirred at 90°C for 2 hours to dissolve.

[0113] Comparative Example 1 An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 300 g (100 parts by weight) of AO-modified PVA-1 was used as the raw material PVA, and 2,800 g of pure water was added, followed by stirring at 90°C for 2 hours to dissolve the AO-modified PVA-1.

[0114] Comparative Example 2 An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that unmodified PVA-1 was used as the raw material PVA, and 2,800 g of pure water was added to 300 g (100 parts by weight) of unmodified PVA-1, and the mixture was stirred at 90°C for 2 hours to dissolve the unmodified PVA-1.

[0115] Comparative Example 3 Unmodified PVA-4 was used as the raw material PVA. 2800 g of pure water was added to 300 g (100 parts by weight) of unmodified PVA-4, and the mixture was stirred at 90°C for 2 hours to dissolve the unmodified PVA-4. This solution was cooled to 40°C, and 300 g of 35 wt% hydrochloric acid, 150 g of acetaldehyde, and 10 g of n-butylaldehyde were added to carry out an acetalization reaction, resulting in the precipitation of a reaction product. The mixture was then maintained at 30°C for 4 hours to complete the reaction, and neutralized, washed, and dried by conventional methods to obtain an alkylene oxide-modified polyvinyl acetal resin. Ion-exchanged water was used for dissolution and washing.

[0116] Comparative Example 4 An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that unmodified polyvinyl alcohol (unmodified PVA-5, average degree of polymerization 1700, degree of saponification 88.0 mol%) was used as the raw material PVA. 2800 g of pure water was added to 300 g (100 parts by weight) of unmodified PVA-5 and the mixture was stirred at 90°C for 2 hours to dissolve.

[0117] Example 6: AO-modified PVA-1 and unmodified polyvinyl alcohol (unmodified PVA-6, average degree of polymerization: 4000, degree of saponification: 99.0 mol%) were used as raw material PVA. An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 60 g (20 parts by weight) of AO-modified PVA-1 and 240 g (80 parts by weight) of unmodified PVA-6 were added to 2800 g of pure water and stirred at 90°C for 2 hours to dissolve.

[0118] Example 7 An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 240 g (80 parts by weight) of the AO-modified PVA-1 and 60 g (20 parts by weight) of the unmodified PVA-6 were dissolved in 2,800 g of pure water by stirring at 90°C for 2 hours.

[0119] Example 8: AO-modified PVA-1 and unmodified PVA-3 were used as the raw material PVA. 2800 g of pure water was added to 150 g (50 parts by weight) of AO-modified PVA-1 and 150 g (50 parts by weight) of unmodified PVA-3, and the mixture was stirred at 90°C for 2 hours to dissolve. The resulting solution was cooled to 40°C, and 300 g of 35 wt% hydrochloric acid, 80 g of acetaldehyde, and 80 g of n-butylaldehyde were added to the solution to carry out an acetalization reaction. An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that the reaction product was precipitated. The ratio of the amount of butyral groups to the amount of acetoacetal groups in the alkylene oxide-modified polyvinyl acetal resin [acetoacetal group amount / butyral group amount] is shown in Table 2 as the "acetoacetal / butyl ratio."

[0120] Example 9: AO-modified PVA-1 and unmodified PVA-3 were used as the raw material PVA. 2,800 g of pure water was added to 150 g (50 parts by weight) of AO-modified PVA-1 and 150 g (50 parts by weight) of unmodified PVA-3, and the mixture was dissolved by stirring at 90°C for 2 hours. The resulting solution was cooled to 40°C, and 300 g of 35 wt% hydrochloric acid and 135 g of n-butylaldehyde were added to carry out an acetalization reaction. An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that the reaction product was precipitated.

[0121] (Example 10) As a raw material PVA, a structural unit represented by formula (5) (in formula (5), A １ O is an oxyethylene group (EO), R ２ is a hydrogen atom, R ３An alkylene oxide-modified polyvinyl alcohol resin (AO-modified PVA-2, average degree of polymerization 1,300, degree of saponification 99.0 mol%) having m=34.5 (wherein m is a single bond) and m=34.5) and unmodified PVA-3 were used. An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 2,800 g of pure water was added to 150 g (50 parts by weight) of AO-modified PVA-2 and 150 g (50 parts by weight) of unmodified PVA-3, and the mixture was stirred at 90°C for 2 hours to dissolve.

[0122] (Example 11) As a raw material PVA, a structural unit represented by formula (6) (in formula (6), A １ O is an oxyethylene group (EO), R ２ is a hydrogen atom, R ３ An alkylene oxide-modified polyvinyl alcohol resin (AO-modified PVA-3, average degree of polymerization 800, degree of saponification 99.0 mol%) having m=49.5 (wherein m is a single bond) and m=49.5 (wherein m is a single bond and m is 49.5) and unmodified PVA-3 were used. An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 2800 g of pure water was added to 150 g (50 parts by weight) of the AO-modified PVA-3 and 150 g (50 parts by weight) of the unmodified PVA-3, and the mixture was stirred at 90°C for 2 hours to dissolve.

[0123] (Example 12) As a raw material PVA, a structural unit represented by formula (6) (in formula (6), A １ O is an oxyethylene group (EO), R ２ is a hydrogen atom, R ３ An alkylene oxide-modified polyvinyl alcohol resin (AO-modified PVA-4, average degree of polymerization 600, degree of saponification 99.0 mol%) having m=4.5 (wherein m is a single bond) and unmodified PVA-3 were used. An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 2800 g of pure water was added to 150 g (50 parts by weight) of the AO-modified PVA-4 and 150 g (50 parts by weight) of the unmodified PVA-3, and the mixture was stirred at 90°C for 2 hours to dissolve.

[0124] (Example 13) As a raw material PVA, a structural unit represented by formula (5) (in formula (5), A １ O is an oxyethylene group (EO) and an oxypropylene group (PO) [PO / EO ratio = 1 / 1], R ２ is a hydrogen atom, R３ An alkylene oxide-modified polyvinyl alcohol resin (AO-modified PVA-5, average degree of polymerization 1,300, degree of saponification 99.0 mol%) having a hydroxy group of 1,200 and a hydroxy group of 1,200 (wherein m is a single bond and m is 49.5) and unmodified PVA-3 were used. An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 2,800 g of pure water was added to 150 g (50 parts by weight) of the AO-modified PVA-5 and 150 g (50 parts by weight) of the unmodified PVA-3, and the mixture was stirred at 90°C for 2 hours to dissolve.

[0125] Comparative Example 5 Unmodified PVA-3 was used as the raw material PVA. 2800 g of pure water was added to 300 g (100 parts by weight) of unmodified PVA-3, and the mixture was stirred at 90°C for 2 hours to dissolve the unmodified PVA-3. This solution was cooled to 40°C, and 300 g of 35 wt% hydrochloric acid, 80 g of acetaldehyde, and 80 g of n-butylaldehyde were added to carry out an acetalization reaction, resulting in the precipitation of a reaction product. The mixture was then maintained at 30°C for 4 hours to complete the reaction, and neutralized, washed, and dried by conventional methods to obtain an alkylene oxide-modified polyvinyl acetal resin. Ion-exchanged water was used for dissolution and washing.

[0126] Comparative Example 6 An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 3 g (1 part by weight) of the AO-modified PVA-1 and 297 g (99 parts by weight) of the unmodified PVA-1 were added to 2,800 g of pure water and stirred at 90°C for 2 hours to dissolve the mixture.

[0127] Comparative Example 7 An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 300 g (100 parts by weight) of AO-modified PVA-2 was used as the raw material PVA, and 2,800 g of pure water was added, followed by stirring at 90°C for 2 hours to dissolve the AO-modified PVA-2.

[0128] Comparative Example 8 An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 300 g (100 parts by weight) of AO-modified PVA-3 was used as the raw material PVA, and 2,800 g of pure water was added, followed by stirring at 90°C for 2 hours to dissolve the AO-modified PVA-3.

[0129] Comparative Example 9 An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 300 g (100 parts by weight) of AO-modified PVA-4 was used as the raw material PVA, and 2,800 g of pure water was added, followed by stirring at 90°C for 2 hours to dissolve the AO-modified PVA-4.

[0130] Comparative Example 10: An alkylene oxide-modified polyvinyl acetal resin was obtained in the same manner as in Example 1, except that 300 g (100 parts by weight) of AO-modified PVA-5 was used as the raw material PVA, and 2,800 g of pure water was added, followed by stirring at 90°C for 2 hours to dissolve the AO-modified PVA-5.

[0131] (Evaluation) The polyvinyl acetal resins obtained in the examples and comparative examples were evaluated as follows. The results are shown in Table 2.

[0132] (1) Evaluation of Polyvinyl Acetal Resin (1-1) Tan δ Evaluation The obtained polyvinyl acetal resin was coated onto a release-treated PET film using a coater so that the thickness after drying would be approximately 5 to 20 μm, and then heated and dried at 70°C for 180 minutes to produce a transparent resin sheet. The obtained resin sheet was cut into 0.5 cm x 3.0 cm specimens, and then the dynamic viscoelasticity was measured using a DMA (manufactured by IT Measurement Co., Ltd.) under the following conditions. The peak top temperature and half-width of the obtained tan δ (loss tangent) were measured. In addition, the storage modulus E' at 60°C was measured from the dynamic viscoelasticity measured under the following conditions. (Measurement Conditions) Measurement Mode: Tensile Mode Forced Vibration Frequency: 1 Hz Temperature Range: 30°C to 150°C Heating Rate: 6°C / min Grip Length: 2.0 cm Strain: 0.08%

[0133] (1-2) Measurement of Z-average molecular weight 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 apparatus GPC-101 (manufactured by Shodex Corporation), NMP as the mobile phase, a differential refractive index detector RI-715 (manufactured by Shodex Corporation) as the detector, and an LF-804 (manufactured by Shodex Corporation) as the column. The obtained measurement results were calibrated using a molecular weight calibration curve prepared using monodisperse polystyrene standard samples to obtain the Z-average molecular weight (NMP).

[0134] (2) Performance Evaluation (2-1) Tensile Strength Measurement The obtained polyvinyl acetal resin was applied to a release-treated PET film using a coater so that the thickness after drying was approximately 5 to 20 μm, and then heated and dried at 70 ° C. for 180 minutes to produce a transparent resin sheet. The obtained resin sheet was measured for breaking stress (MPa) in accordance with JIS K 7113 using a tensile tester (Shimadzu Corporation, AUTOGRAPH AGS-J) at a 30 ° C. environment and a tensile speed of 20 mm / min. The obtained breaking stress was evaluated according to the following criteria.

[0135] AA: Breaking stress is greater than 75 MPa. A: Breaking stress is greater than 50 MPa and less than 75 MPa. B: Breaking stress is greater than 25 MPa and less than 50 MPa. C: Breaking stress is less than 25 MPa.

[0136] (2-2) Adhesion Evaluation The obtained polyvinyl acetal resin was applied to a release-treated PET film using a coater so that the thickness after drying would be approximately 5 to 20 μm, and then heated and dried at 70 ° C for 180 minutes to produce a transparent resin sheet. The obtained resin sheet was cut into 1.0 cm x 1.0 cm to prepare a test piece, and then the tack force (peak value) was measured using a tack tester (manufactured by RHESCA) under the following conditions. The obtained peak value was evaluated according to the following criteria (when the measurement temperature was 50 ° C, 60 ° C, and 70 ° C). (Measurement conditions) Pressing speed: 5.0 mm / s Pressing load: 98 gf, 0.05 MPa Pressing holding time: 10 s Pulling speed: 5.0 mm / s Measurement temperature: 50, 60, 70 ° C

[0137] When the measurement temperature is 50°C, AA: Peak value is over 30 gf. A: Peak value is over 20 gf and 30 gf or less. B: Peak value is over 16 gf and 20 gf or less. C: Peak value is 16 gf or less.

[0138] When the measurement temperature is 60°C, AA: Peak value is over 50 gf. A: Peak value is over 30 gf and 50 gf or less. B: Peak value is over 17 gf and 30 gf or less. C: Peak value is 17 gf or less.

[0139] When the measurement temperature is 70°C, AA: Peak value is over 100 gf. A: Peak value is over 50 gf and 100 gf or less. B: Peak value is over 25 gf and 50 gf or less. C: Peak value is 25 gf or less.

[0140] (2-3) Evaluation of storage stability (granulation rate) The obtained polyvinyl acetal resin was again immersed in water for 8 hours and then stored in a dryer at 35°C for 48 hours. The resin was removed from the dryer, and the granulated product was sorted using a 5-mesh sieve and weighed. The granulation rate was calculated from the change in weight before and after sorting and evaluated according to the following criteria. A lower granulation rate indicates better storage stability.

[0141] AA: Granulation rate is 30% or less. A: Granulation rate is more than 30% and less than 40%. B: Granulation rate is more than 40% and less than 50%. C: Granulation rate is more than 50%.

[0142]

[0143]

[0144] According to the present invention, it is possible to provide a polyvinyl acetal resin that can provide a ceramic green sheet that has excellent adhesion and high strength over a wide temperature range, a slurry composition for a ceramic green sheet that uses the polyvinyl acetal resin, a ceramic green sheet, and a multilayer ceramic capacitor.

Claims

1. A polyvinyl acetal resin having a tan δ peak top temperature of 35°C or higher and 80°C or lower, and a tan δ peak half-width of 10.1°C or higher and 30°C or lower, in dynamic viscoelasticity measurement at 1 Hz.

2. The polyvinyl acetal resin according to claim 1, which has a structural unit having an alkylene oxide group.

3. The polyvinyl acetal resin according to claim 2, which comprises a polyvinyl acetal having a structural unit having an alkylene oxide group and a polyvinyl acetal having no alkylene oxide group.

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

5. The polyvinyl acetal resin according to any one of claims 2 to 4, wherein the alkylene oxide group has a repeating unit number of 2 or more and 100 or less.

6. The polyvinyl acetal resin according to any one of claims 2 to 5, wherein the alkylene oxide group is at least one selected from the group consisting of an oxyethylene group and an oxypropylene group.

7. The polyvinyl acetal resin according to any one of claims 2 to 6, wherein the content of the structural unit having an alkylene oxide group relative to the entire polyvinyl acetal resin is from 0.1 mol % to 5 mol %.

8. The polyvinyl acetal resin according to any one of claims 2 to 7, comprising a structural unit having an acetal group, a structural unit having an acetyl group, a structural unit having a hydroxyl group, and a structural unit having the alkylene oxide group.

9. The polyvinyl acetal resin according to any one of claims 1 to 8, wherein the content of the structural unit having a hydroxyl group relative to the entire polyvinyl acetal resin is from 23 mol % to 40 mol %.

10. A slurry composition for ceramic green sheets, comprising the polyvinyl acetal resin according to any one of claims 1 to 9, an organic solvent, and ceramic powder.

11. A ceramic green sheet obtained by using the slurry composition for a ceramic green sheet according to claim 10.

12. A multilayer ceramic capacitor obtained by using the ceramic green sheet according to claim 11.

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