Resin composition for baking and sheet for baking

Abstract

Provided is a resin composition for baking, said composition making it possible to obtain a sheet having excellent baking properties and bending strength. The present invention makes it possible to provide a resin composition for baking, said composition containing polylactic acid (A) and a plasticizer (B) having an SP value of 9.6 (cal) / cm 3)1 / 2 or more.

Description

Resin composition for baking and sheet for baking

[0001] Inorganic particle-containing resin compositions for firing (pastes or slurries) used in the production of internal electrodes (for example, MLCCs (Multilayer Ceramic Capacitors)) often contain ethyl cellulose (EC) or polyvinyl butyral (PVB) as binders.

[0002] Patent Document 1 discloses an invention relating to a dry film for an internal electrode of a multilayer ceramic capacitor, which is formed from a composition containing a conductive powder and an organic binder resin, and discloses that the binder resin contains ethyl cellulose and polyvinyl butyral. Patent Document 2 also discloses a paste composition containing an inorganic substance, a binder resin, and a solvent, wherein the binder resin is at least one (co)polymer selected from a homopolymer of lactic acid and a copolymer of lactic acid and a copolymerizable monomer.

[0003] JP 2019-121744 JP 9-142938 JP

[0004] However, conventional pastes, such as ethyl cellulose and polyvinyl butyral, have a high residual carbon content after firing and poor firing properties. Furthermore, firing at high temperatures can cause thermal stress on the resin substrate, leading to an increase in defects such as deformation. Furthermore, pastes that can be fired at low temperatures are needed because they are sometimes used in combination with resin substrates with low heat resistance. Furthermore, ceramic structures, such as multilayer ceramic capacitors, are manufactured using processes such as laminating sheets and cutting the laminated sheets. However, if the bending strength of the film or sheet formed from the resin composition for firing is low, cracks may occur in the laminate or structure during processing and / or after firing, or handling may be impaired.

[0005] The present invention has been made in view of the above circumstances, and provides a resin composition for baking that can give a sheet having excellent baking properties and bending strength.

[0006] According to the present invention, polylactic acid (A) and a polymer having an SP value of 9.6 (cal / cm ３ ) １／２ A resin composition for baking containing the above-mentioned plasticizer (B) is provided.

[0007] The present inventors have conducted extensive research and have found that by combining polylactic acid with a plasticizer having a specific SP value, a resin composition for baking can be obtained that can produce a sheet with excellent baking properties and bending strength, leading to the completion of the present invention.

[0008] Various embodiments of the present invention are exemplified below. The embodiments shown below can be combined with each other. [1] Polylactic acid (A) and a polymer having an SP value of 9.6 (cal / cm ３ ) １／２ and a plasticizer (B). [2] The resin composition for baking according to [1], wherein the polylactic acid (A) comprises at least one selected from polylactic acid (A1) and polylactic acid (A2), and the polylactic acid (A1) has a D-form component content of 55 to 88 mass% relative to 100 mass% of the total of the L-form and D-form components contained in the polylactic acid (A1), and the polylactic acid (A2) has an L-form component content of 55 to 88 mass% relative to 100 mass% of the total of the L-form and D-form components contained in the polylactic acid (A2). [3] The resin composition for baking according to [1] or [2], wherein the polylactic acid (A) has a weight-average molecular weight Mw of 30,000 to 500,000. [4] The resin composition for baking according to any one of [1] to [3], wherein the plasticizer (B) comprises at least one selected from the group consisting of hydroxycarboxylic acid esters, polyhydric alcohol esters, fatty acid esters, phthalic acid esters, acrylic resins having a number average molecular weight of 500 to 20,000, and polyesters having a number average molecular weight of 500 to 20,000. [5] The resin composition for baking according to any one of [1] to [4], further comprising inorganic particles and a solvent. [6] A sheet for baking comprising the resin composition for baking according to any one of [1] to [5].

[0009] The resin composition for baking according to the present invention can produce a sheet with excellent baking properties and bending strength. Furthermore, a sheet for baking containing the resin composition for baking according to the present invention has excellent baking properties and bending strength. Therefore, the sheet for baking according to the present invention can sufficiently reduce residual carbon after baking by baking at a low temperature, thereby reducing defects that may occur when baking at a high temperature. It can also be combined with materials with low heat resistance to produce laminates, etc. Furthermore, films and sheets containing the resin composition for baking according to the present invention have excellent bending strength, which reduces the occurrence of cracks during the sheet lamination process, the cutting process of the laminated sheet, etc., and provides excellent handleability. The sheet for baking according to one embodiment of the present invention can be used in ceramic structures such as MLCCs (multilayer ceramic capacitors).

[0010] The present invention will be described in detail below by illustrating embodiments of the present invention. The present invention is not limited by these descriptions. The features of the embodiments of the present invention described below can be combined with each other. Furthermore, each feature can be an invention independently.

[0011] 1. Resin composition for baking The resin composition according to the present invention comprises polylactic acid (A) and a cellulose ester having an SP value of 9.6 (cal / cm ３ ) １／２ The plasticizer (B) is also included.

[0012] 1.1 Polylactic acid (A) The polylactic acid (A) according to the present invention is a polymer containing a component derived from lactic acid. The polylactic acid (A) according to the present invention contains at least one of an L-component represented by the following formula (1) and a D-component represented by the following formula (2). The L-component is a component derived from L-lactic acid, and the D-component is a component derived from D-lactic acid.

[0013]

[0014]

[0015] The polylactic acid (A) according to one embodiment of the present invention preferably contains an L-component and a D-component. By containing the L-component and the D-component, the crystallinity of the polylactic acid can be prevented from becoming too high, and the bending strength can be further improved.

[0016] The polylactic acid (A) according to one embodiment of the present invention can be a polymer primarily composed of L- and / or D-form components, and may contain components derived from other monomers as necessary, provided that the effects of the present invention are not impaired. The polylactic acid (A) according to one embodiment of the present invention may contain, for example, 0, 5, 10, 15, or 20% by mass of components other than the components derived from lactic acid (L- and D-form components) when the polylactic acid (A) is taken as 100% by mass, or may contain components within a range between any two of the values ​​exemplified here. The polylactic acid (A) according to the present invention may also be composed solely of components derived from lactic acid, i.e., L- and D-form components.

[0017] The polylactic acid (A) according to the present invention preferably contains at least one selected from polylactic acid (A1) and polylactic acid (A2). The polylactic acid (A1) may be a polylactic acid having a D-form component content of 55 to 88% by mass relative to 100% by mass of the total of the L- and D-form components contained in the polylactic acid (A1). The D-form component content relative to 100% by mass of the total of the L- and D-form components in the polylactic acid (A1) may be, for example, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, or 88% by mass, and may fall within a range between any two of the values ​​exemplified here. The polylactic acid (A2) may have an L-component content of 55 to 88% by mass relative to 100% by mass of the total of the L-components and D-components contained in the polylactic acid (A2). The L-component content relative to 100% by mass of the total of the L-components and D-components in the polylactic acid (A2) is, for example, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, or 88% by mass, and may be within a range between any two of the values ​​exemplified here.

[0018] By including at least one selected from polylactic acid (A1) and polylactic acid (A2), the mechanical properties of the resulting baking sheet can be further improved. Although the mechanism is unclear, it is speculated that polylactic acid (A1) and polylactic acid (A2) have a relatively high content of either the D-form component or the L-form component, and therefore have high crystallinity and can further improve tensile strength. Furthermore, by including at least a small amount of either the L-form component or the D-form component, polylactic acid (A1) and polylactic acid (A2) do not become too crystalline and also have amorphous properties, which is thought to maintain flexibility. From the above, it is speculated that it is more preferable for polylactic acid to be biased toward either the L-form component or the D-form component, and to have a certain amount of the other component.

[0019] The contents of the L- and D-form components can be calculated from the mass ratio of the L- and D-form components in the raw materials constituting the polylactic acid (A). The L- and D-lactic acid ratios can be analyzed by pyrolysis GC / MS. The L- and D-lactic acid ratios can be controlled by adjusting the mass ratio of L- and D-lactic acid used as raw materials in the polymerization of polylactic acid.

[0020] The polylactic acid (A) according to one embodiment of the present invention preferably has a weight-average molecular weight of 30,000 to 500,000. The weight-average molecular weight may be, for example, 30,000, 40,000, 50,000, 100,000, 150,000, 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, or 500,000, or may be within a range between any two of the values ​​exemplified here. By setting the weight-average molecular weight within the above range, a polylactic acid having an excellent balance between solvent solubility and the viscosity of the resin composition is likely to be obtained.

[0021] The polylactic acid (A) according to one embodiment of the present invention may have a molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of 1.5 to 2.7. The molecular weight distribution may be, for example, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, or 2.7, or may be within a range between any two of the values ​​exemplified here.

[0022] The weight-average molecular weight and molecular weight distribution can be determined by GPC, specifically, under the conditions described in the Examples. The weight-average molecular weight and molecular weight distribution can be controlled by adjusting the polymerization conditions during polylactic acid polymerization.

[0023] The structure of the polylactic acid (A) according to the present invention is not particularly limited, but it can be a random copolymer.

[0024] 1.2. Production Method of Polylactic Acid (A) The production method of polylactic acid (A) according to the present invention is not particularly limited, but it can be produced, for example, by the following method. Polylactic acid (A) according to one embodiment of the present invention can be obtained by a production method including a step of polymerizing a raw material containing lactide, which is a cyclic dimer. Examples of lactides that can be contained in the raw material include meso-lactide, L-lactide, and D-lactide. The raw material preferably contains at least two selected from meso-lactide, L-lactide, and D-lactide, and can contain meso-lactide and L-lactide, meso-lactide and D-lactide, or meso-lactide, L-lactide, and D-lactide. The raw material preferably contains an L-component and a D-component. Furthermore, when the total of meso-lactide, L-lactide, and D-lactide contained in the raw material is taken as 100% by mass, the raw material preferably contains 55 to 88% by mass of L-components in total, or 55 to 88% by mass of D-components in total. The raw material may contain, for example, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, or 88% by mass of L-components in total, or may be within a range between any two of the values ​​exemplified here. The raw material may have a total D-form component content of, for example, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, or 88% by mass, and may be within a range between any two of the values ​​exemplified here. When the contents of L-form components and D-form components are calculated from the mass ratio of L-form components to D-form components in the raw materials constituting polylactic acid (A), meso-lactide can be counted as 50% by mass of L-form components and 50% by mass of D-form components, out of 100% by mass of the mass.

[0025] A catalyst can be used for the polymerization of polylactic acid (A), and examples of the catalyst include organic tin compounds such as tin lactate, tin tartrate, tin dicaprylate, tin dilaurate, tin dipaltimate, tin distearate, tin dioleate, tin α-naphthenate, tin β-naphthenate, and tin octoate; tin powder; zinc powder, zinc halide, zinc oxide, organic zinc compounds; titanium compounds such as tetrapropyl titanate; zirconium compounds such as zirconium isopropoxide; and antimony compounds such as antimony trioxide. The amount of catalyst added can be 0.001 to 5 parts by mass, or 0.005 to 3 parts by mass, per 100 parts by mass of the total of the raw materials, lactic acid, lactide, etc.

[0026] The polymerization of polylactic acid (A) can be carried out under an inert gas atmosphere such as nitrogen gas. The polymerization temperature can be, for example, 150 to 210° C., or 160 to 200° C. The polymerization time can be, for example, 1 to 10 hours, or 4 to 8 hours.

[0027] The weight average molecular weight and molecular weight distribution of polylactic acid can be adjusted by adjusting the type and amount of catalyst added, as well as polymerization conditions such as polymerization temperature and time.

[0028] 1.3 Plasticizer The resin composition for baking according to the present invention has an SP value of 9.6 (cal / cm ３ ) １／２ The SP value of the plasticizer (B) is 9.6 to 15.0 (cal / cm ３ ) １／２ For example, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11.0, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5, 15.0 (cal / cm ３ ) １／２and may be within a range between any two of the values ​​exemplified herein. The SP value can be the solubility parameter calculated by the Fedors method, and is calculated based on the molecular structure (atomic group) and its number. The method for calculating the SP value using the Fedors method can be, for example, based on the value calculated by formula (28) described on page 153 of Polymer Engineering and Science, February 1974, Vol. 14, No. 2, pp. 147-154, page 152 (Table. 5) using the values ​​(heat of vaporization and molar volume at 25°C of the atom or functional group). The SP value can be the solubility parameter at 25°C. By combining polylactic acid with a plasticizer having an SP value within the above numerical range, a structure in which both are appropriately dispersed can be formed, and it is believed that a resin composition for baking can be obtained that can produce a sheet with excellent baking properties and bending strength.

[0029] In the present invention, the plasticizer is a compound added to impart flexibility to the resin composition to be baked. The plasticizer is not particularly limited as long as the SP value satisfies the above-mentioned requirements, but may include at least one selected from the group consisting of hydroxycarboxylic acid esters, polyhydric alcohol esters, fatty acid esters, phthalic acid esters, acrylic resins having a number-average molecular weight of 500 to 20,000, and polyesters having a number-average molecular weight of 500 to 20,000.

[0030] Examples of hydroxycarboxylic acid esters include triethyl citrate, tributyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate; examples of polyhydric alcohol esters include triacetin, diacetin, and tributyrin; examples of phthalic acid esters include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, and diheptyl phthalate; and examples of fatty acid esters (e.g., fatty acid esters other than those listed above) include dimethyl adipate, and at least one selected from the group consisting of these may be included. Among these, those having a molecular weight of 100 to 500 may be used. The molecular weight may be, for example, 100, 150, 200, 250, 300, 350, 400, 450, or 500, and may be within a range between any two of the values ​​exemplified here.

[0031] The acrylic resin having a number average molecular weight of 500 to 20,000 is not particularly limited as long as the number average molecular weight and SP value satisfy the above requirements and the polymer has structural units derived from a monomer having (meth)acrylic acid and / or a (meth)acrylic acid ester. The number average molecular weight of the acrylic resin having a number average molecular weight of 500 to 20,000 is, for example, 500, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, or 20000, and may be within a range between any two of the values ​​exemplified here.

[0032] The acrylic resin having a number-average molecular weight of 500 to 20,000 preferably has structural units derived from a monomer having a carboxy group. The monomer having a carboxy group includes a compound obtained by ring-opening an acid anhydride group-containing monomer through hydrolysis. Alternatively, the acrylic resin having a number-average molecular weight of 500 to 20,000 may be prepared by producing an acrylic resin having a carboxy group and then adding, for example, an epoxy resin to the carboxy group of the acrylic resin having a carboxy group.

[0033] Examples of the monomer having a carboxy group include carboxy group-containing monomers other than carboxy group-containing (meth)acrylates, such as (meth)acrylic acid, itaconic acid, crotonic acid, maleic acid, and fumaric acid; and carboxy group-containing (meth)acrylates, such as β-carboxyethyl (meth)acrylate, 5-carboxypentyl (meth)acrylate, succinic acid mono(meth)acryloyloxyethyl ester, ω-carboxypolycaprolactone mono(meth)acrylate, and p-carboxybenzyl (meth)acrylate.

[0034] Examples of acid anhydride group-containing monomers include maleic anhydride, dodecenylsuccinic anhydride, chlorendic anhydride, sebacic anhydride, phthalic anhydride, pyromellitic anhydride, trimellitic anhydride, cyclopentane tetracarboxylic acid dihydrate, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetramethylene maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, 5-(2,5-dioxotetrahydroxyfuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, and methylnadic anhydride. Among these, (meth)acrylic acid is preferred.

[0035] The acrylic resin having a number average molecular weight of 500 to 20,000 preferably has a structure derived from a monomer having a carboxy group in an amount of 0.8 to 15% by mass, and more preferably 1 to 10% by mass, based on 100% by mass of the acrylic resin.

[0036] Examples of (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and n-octyl (meth)acrylate. alkyl(meth)acrylates such as octyl(meth)acrylate, iso-octyl(meth)acrylate, nonyl(meth)acrylate, iso-nonyl(meth)acrylate, decyl(meth)acrylate, iso-decyl(meth)acrylate, undeca(meth)acrylate, lauryl(meth)acrylate, oleyl(meth)acrylate, n-stearyl(meth)acrylate, and iso-stearyl(meth)acrylate, particularly alkyl(meth)acrylates having an alkyl group having 1 to 20 carbon atoms; (meth)acrylates containing an alicyclic hydrocarbon group or an aromatic hydrocarbon group, such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, and phenoxyethyl (meth)acrylate; alkoxyalkyl (meth)acrylates, such as methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate; Alkoxypolyalkylene glycol mono(meth)acrylates such as methoxydiethylene glycol mono(meth)acrylate, methoxydipropylene glycol mono(meth)acrylate, ethoxytriethylene glycol mono(meth)acrylate, ethoxydiethylene glycol mono(meth)acrylate, and methoxytriethylene glycol mono(meth)acrylate; N,N-dialkylaminoalkyl (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate and N,N-diethylaminoethyl (meth)acrylate;Hydroxy group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate;

[0037] The acrylic resin having a number average molecular weight of 500 to 20,000 preferably contains 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more of a structure derived from a (meth)acrylic acid ester, based on 100% by mass of the acrylic resin.

[0038] The acrylic resin having a number average molecular weight of 500 to 20,000 may have structural units derived from a monomer having a carboxy group and a monomer other than a (meth)acrylic acid ester (at least one selected from a cyano group-containing monomer, a nitrogen-containing heterocycle-containing monomer, a styrene-based monomer, and a vinyl ether-based monomer). In the acrylic resin having a number average molecular weight of 500 to 20,000, the proportion of structural units derived from other monomers relative to 100% by mass of the acrylic resin having a number average molecular weight of 500 to 20,000 can be 20% by mass or less, and preferably 10% by mass or less.

[0039] The polyester having a number-average molecular weight of 500 to 20,000 is not particularly limited as long as the number-average molecular weight and SP value satisfy the above requirements. The polyester can be a polymer having a structure derived from a polycarboxylic acid and a polyol. The number-average molecular weight of the polyester having a number-average molecular weight of 500 to 20,000 is, for example, 500, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, or 20000, and may be within a range between any two of the values ​​exemplified here.

[0040] The polyester having a number average molecular weight of 500 to 20,000 preferably has a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyol. For example, the polyester may be obtained by capping at least one reactive molecular end of the polyester with a reactive molecular end-capping agent. For example, such a polyester resin may be obtained by capping the reactive molecular end of a polyester having at least one of a carboxyl end derived from a polycarboxylic acid and a hydroxyl end derived from a polyol with a reactive molecular end-capping agent.

[0041] <Polycarboxylic Acid> Examples of the structural unit derived from the polycarboxylic acid include a structural unit derived from a dicarboxylic acid and a structural unit derived from a trivalent or higher polycarboxylic acid. The polycarboxylic acid may be used alone or in combination of two or more kinds.

[0042] Among the structural units derived from polycarboxylic acids, it is preferable to include structural units derived from aromatic polycarboxylic acids, and examples of structural units derived from aromatic dicarboxylic acids include structural units derived from phthalic acids, isophthalic acids, 1,8-naphthalenedicarboxylic acids, 2,3-naphthalenedicarboxylic acids, and 2,7-naphthalenedicarboxylic acids. Of these, structural units derived from isophthalic acids are particularly preferable in terms of reactivity.

[0043] The content of the structural units derived from aromatic polycarboxylic acids is preferably 0.1 to 100 mol %, more preferably 1 to 80 mol %, even more preferably 3 to 70 mol %, and particularly preferably 5 to 60 mol %, based on the total structural units derived from polycarboxylic acids.

[0044] Furthermore, as the structural unit derived from the polyvalent carboxylic acid, it is preferable to contain a structural unit derived from an aliphatic dicarboxylic acid having 4 or more carbon atoms (including the carbon atom in the carboxy group), and among these, it is more preferable to contain a structural unit derived from an aliphatic dicarboxylic acid having 6 to 12 carbon atoms (including the carbon atom in the carboxy group), and it is particularly preferable to contain a structural unit derived from an adipic acid, a sebacic acid, or an azelaic acid.

[0045] The content of structural units derived from aliphatic dicarboxylic acids having 4 or more carbon atoms is preferably 10 to 100 mol %, more preferably 20 to 95 mol %, even more preferably 30 to 90 mol %, and particularly preferably 40 to 80 mol %, based on the total structural units derived from polycarboxylic acids.

[0046] In the present invention, it is also preferable that the structural units derived from polycarboxylic acids include structural units derived from aromatic dicarboxylic acids and structural units derived from aliphatic dicarboxylic acids having 4 or more carbon atoms. In this case, the content ratio (molar ratio) of the structural units derived from aromatic dicarboxylic acids to the structural units derived from aliphatic dicarboxylic acids having 4 or more carbon atoms is preferably 1 / 99 to 99 / 1, more preferably 5 / 95 to 90 / 10, even more preferably 20 / 80 to 80 / 20, and particularly preferably 30 / 70 to 70 / 30.

[0047] Furthermore, structural units derived from trivalent or higher polyvalent carboxylic acids can also be used, and among these, trimellitic acids are preferably used.

[0048] The content of structural units derived from trivalent or higher polycarboxylic acids is preferably 10 mol % or less, more preferably 5 mol % or less, particularly preferably 3 mol % or less, and most preferably 1 mol % or less, based on the total amount of polycarboxylic acids. If the content is too high, gelation tends to occur during production of the polyester resin, or the acid value tends to increase.

[0049] <Polyol> The structural unit derived from the polyol may contain a structural unit derived from an aliphatic diol having a linear structure, preferably a structural unit derived from an aliphatic diol having a linear structure having 2 to 18 carbon atoms, and more preferably a structural unit derived from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, or 1,6-hexanediol.

[0050] The content of the structural units derived from a linear aliphatic diol is preferably 1 to 80 mol %, more preferably 3 to 60 mol %, even more preferably 5 to 40 mol %, and particularly preferably 10 to 30 mol %, based on the total structural units derived from the polyol.

[0051] Among the structural units derived from the polyols, it is preferable to contain a structural unit derived from a diol having a hydrocarbon group in the side chain, since this can disrupt crystallinity. Among the structural units derived from diols having a hydrocarbon group, it is preferable to contain a structural unit derived from an aliphatic diol having a branched structure, and it is particularly preferable to contain a structural unit derived from 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), or 3-methyl-1,5-pentanediol.

[0052] The content of the structural units derived from the diol having a hydrocarbon group in the side chain is preferably 5 to 100 mol %, more preferably 15 to 100 mol %, even more preferably 30 to 100 mol %, particularly preferably 45 to 100 mol %, and most preferably 60 to 100 mol %, based on the total structural units derived from the polyol.

[0053] Furthermore, the polyol-derived structural units may contain structural units derived from a trivalent or higher polyol. The content of the structural units derived from a trivalent or higher polyol is preferably 10 mol % or less, more preferably 5 mol % or less, particularly preferably 3 mol % or less, and most preferably 1 mol % or less, based on the total structural units derived from the polyol.

[0054] <Structural Units Derived from Reactive Molecular End-Capping Agents> The reactive molecular end-capping agent may contain a functional group reactive with at least one reactive group, i.e., a carboxyl end derived from a polycarboxylic acid and a hydroxyl end derived from a polyol, and this reactive group reacts with the functional group of the reactive molecular end-capping agent to block the reactive group at the end. Examples of reactive molecular end-capping agents include isocyanate group-containing compounds, carbodiimide group-containing compounds, epoxy group-containing compounds, oxazoline group-containing compounds, carboxyl group-containing compounds, and hydroxyl group-containing compounds. These may be used alone or in combination of two or more.

[0055] 1.4 Other Components The resin composition for baking according to one embodiment of the present invention may include at least one of inorganic particles and a solvent, and may include inorganic particles and a solvent.

[0056] As the inorganic particles, known powders can be used depending on the application, such as gold, silver, copper, nickel, palladium, ITO (Indium Tin Oxide), alumina, zirconia, titanium oxide, barium titanate, aluminum nitride, silicon nitride, boron nitride, various glass powders, inorganic phosphors, graphite powder, solder powder, etc., which can be used alone or in combination of two or more.

[0057] For example, when the resin composition for baking according to one embodiment of the present invention is used as a paste for baking for forming a wiring pattern to be used in printing by screen printing or the like, the inorganic particles may be silver, copper, nickel, or the like, and it is preferable to use nickel.

[0058] For example, when the resin composition for firing according to one embodiment of the present invention is used as a paste for forming an insulating pattern or a slurry for forming a sheet for firing, the inorganic particles can be at least one selected from the group consisting of alumina, zirconia, titanium oxide, barium titanate, aluminum nitride, silicon nitride, boron nitride, and various glass powders.

[0059] The solvent that may be contained in the resin composition for baking according to one embodiment of the present invention is not particularly limited, and known solvents can be used. The solvent preferably has excellent compatibility with the polylactic acid (A) according to the present invention. For example, when a polylactic acid solution containing 10% by mass of the polylactic acid (A) according to the present invention and 90% by mass of the solvent is prepared, it is preferable that no visible residue remains. The boiling point of the solvent is preferably 150 to 300°C, more preferably 200 to 290°C, and even more preferably 220 to 280°C. Examples of the solvent include alcohol-based solvents and ester-based solvents.

[0060] Examples of alcohol-based solvents include cycloalkanols such as cyclohexanol, terpineol (including α-, β-, and γ-isomers, or any mixture thereof), terpene alcohols (e.g., monoterpene alcohols) such as dihydroterpineol, dihydroterpineol, myrtenol, sobrerol, menthol, carveol, perillyl alcohol, pinocarveol, sobrerol, verbenol, dipropylene glycol, and butyl carbitol.

[0061] Examples of ester-based solvents include butyl carbitol acetate (BCA), dihydroterpinyl acetate (DHTA), butyl glycol acetate (BMGAC), diethylene glycol alkyl ether acetate (here, examples of alkyl include ethyl, propyl, n-butyl, etc.; the same applies below), acetates such as ethylene glycol alkyl ether acetate, ethylene glycol diacetate, and propylene glycol alkyl ether acetate, 2,2,4-trimethylpentane-1,3-diol mono-iso-butyrate, 2,2,4-trimethylpentane-1,3-diol mono-iso-butyrate ether, dipropylene glycol monomethyl ether, diethylene glycol alkyl ether, ethylene glycol alkyl ether, and dipropylene glycol alkyl ether.

[0062] Among the above, the solvent preferably contains at least one of ester-based solvents, more preferably at least one of butyl carbitol acetate (BCA), butyl glycol acetate (BMGAC), dihydroterpineol acetate (DHTA), terpineol, and dihydroterpineol, and even more preferably butyl carbitol acetate (BCA).

[0063] The resin composition for baking according to one embodiment of the present invention may contain other additives as needed, as long as the effects of the present invention are not impaired. Examples of other additives include dispersants, surfactants, antioxidants, flame retardants, lubricants, and mold release agents.

[0064] 1.5 Uses of the Resin Composition for Sintering and Amounts of Each Component The resin composition for sintering according to one embodiment of the present invention can be used as a binder composition for preparing a paste for sintering. The resin composition for sintering according to one embodiment of the present invention can be used as a binder composition for preparing a slurry for forming a sheet for sintering. The resin composition for sintering according to one embodiment of the present invention can be used as a paste for sintering. The resin composition for sintering according to one embodiment of the present invention can be used to form wiring for a multilayer ceramic capacitor (MLCC), for example, for an internal electrode of an MLCC. As an example, the resin composition for sintering according to one embodiment of the present invention can be used for an internal electrode containing nickel as inorganic particles. The resin composition for sintering according to one embodiment of the present invention can also be used as a slurry for sintering to form a sheet for sintering. The resin composition for sintering according to one embodiment of the present invention can be used to form a green sheet for a multilayer ceramic capacitor (MLCC). As an example, the resin composition for sintering according to one embodiment of the present invention can be used for a green sheet containing ceramic as inorganic particles to be laminated by pressure bonding.

[0065] The resin composition for baking according to one embodiment of the present invention may contain polylactic acid (A) as a binder, or may contain a binder other than polylactic acid (A). Examples of binders that the resin composition for baking according to one embodiment of the present invention may contain in addition to polylactic acid (A) include ethyl cellulose and polyvinyl butyral. The resin composition for baking according to one embodiment of the present invention preferably contains 50% by mass or more of polylactic acid (A), preferably 80% by mass or more, and more preferably 90% by mass or more, of the polylactic acid (A) when the binder contained in the resin composition for baking is taken as 100% by mass. The content of polylactic acid (A) when the binder is taken as 100% by mass may be, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100% by mass, and may be within a range between any two of the values ​​exemplified here. The resin composition for baking according to one embodiment of the present invention may also contain only polylactic acid (A) as the binder.

[0066] The resin composition for baking according to one embodiment of the present invention may contain 0.1 to 20% by mass of a binder and 0.05 to 20% by mass of polylactic acid (A) when the resin composition for baking is taken as 100% by mass. The content of polylactic acid (A) when the resin composition for baking is taken as 100% by mass is, for example, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20% by mass, and may be within a range between any two of the values ​​exemplified here.

[0067] The resin composition for baking according to one embodiment of the present invention has an SP value of 9.6 (cal / cm ３ ) １／２ The plasticizer (B) is contained, and the SP value is 9.6 (cal / cm ３ ) １／２ The resin composition for baking according to one embodiment of the present invention may contain a plasticizer (B) other than the above-mentioned plasticizer (B). ３ ) １／２ Other plasticizers that may be contained in addition to the plasticizer (B) include dioctyl phthalate (DOP), butyl oleate, dioctyl adipate, etc. The resin composition for baking according to one embodiment of the present invention has an SP value of 9.6 (cal / cm) when the plasticizer contained in the resin composition for baking is taken as 100% by mass. ３ ) １／２ The plasticizer (B) is preferably contained in an amount of 50% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The SP value when the plasticizer is taken as 100% by mass is 9.6 (cal / cm ３ ) １／２ The content of the plasticizer (B) is, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100% by mass, and may be within a range between any two of the values ​​exemplified here. The resin composition for baking according to one embodiment of the present invention contains a plasticizer having an SP value of 9.6 (cal / cm ３ ) １／２ The plasticizer (B) may be contained alone.

[0068] A resin composition for baking according to one embodiment of the present invention may contain 0.2 to 40 parts by mass of a plasticizer when the polylactic acid (A) contained in the resin composition for baking is taken as 100 parts by mass. The content of the plasticizer is, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, or 40 parts by mass, and may be within a range between any two of the numerical values ​​exemplified here. A resin composition for baking according to one embodiment of the present invention has an SP value of 9.6 (cal / cm) when the polylactic acid (A) contained in the resin composition for baking is taken as 100 parts by mass. ３ ) １／２ The resin composition for baking may contain 0.1 to 40 parts by mass of the above plasticizer (B). The content of polylactic acid (A) when the resin composition for baking is taken as 100% by mass is, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, or 40 parts by mass, and may be within a range between any two of the values ​​exemplified here.

[0069] When the resin composition for baking according to one embodiment of the present invention contains a solvent, the resin composition for baking may contain 200 to 2000 parts by mass of the solvent per 100 parts by mass of the polylactic acid (A) contained in the resin composition for baking. The solvent content may be, for example, 200, 400, 600, 800, 1000, 1200, 1400, 1600, 1800, or 2000 parts by mass, or may be within a range between any two of the values ​​exemplified here.

[0070] When the resin composition for baking according to one embodiment of the present invention contains inorganic particles, the resin composition for baking may contain 200 to 2,000 parts by mass of inorganic particles per 100 parts by mass of polylactic acid (A) contained in the resin composition for baking. The content of the inorganic particles may be, for example, 200, 400, 600, 800, 1,000, 1,200, 1,400, 1,600, 1,800, or 2,000 parts by mass, or may be within a range between any two of the values ​​exemplified here.

[0071] 1.6 Properties of the Resin Composition for Baking The resin composition for baking according to one embodiment of the present invention is prepared by applying the resin composition for baking onto a film using a doctor blade and drying at 80°C for 5 minutes to obtain a sheet having a thickness of 30 µm, and the sheet has a tensile strength of 5 N / mm ２ The tensile strength is preferably 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 N / mm ２ and may be within a range between any two of the numerical values ​​exemplified here. By setting the strength within the above range, for example, defects such as lamination slippage are less likely to occur in the sheet lamination process during internal electrode production, and a sheet with excellent processability in the cutting process can be obtained. Specifically, the tensile strength of the sheet can be determined by the method described in the examples. As an example, it can be evaluated using a resin composition containing polylactic acid, a plasticizer, and a solvent but not containing inorganic particles.

[0072] In one embodiment of the present invention, the resin composition for baking is applied to a film using a doctor blade and dried at 80°C for 5 minutes to obtain a 30 μm-thick sheet having an elongation of 5% or more. The elongation may be, for example, 5, 10, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1000%, or may be within a range between any two of the values ​​exemplified herein. By achieving an elongation within the above range, for example, defects such as lamination slippage during the sheet lamination process in the manufacture of internal electrodes are less likely to occur, and a sheet with excellent processability during the cutting process can be obtained. Specifically, the elongation of the sheet can be determined by the method described in the examples. For example, it can be evaluated using a resin composition containing polylactic acid, a plasticizer, and a solvent, but not containing inorganic particles.

[0073] The resin composition for baking according to one embodiment of the present invention is prepared by applying the resin composition for baking onto a film using a doctor blade, drying at 80°C for 5 minutes, and then bending the resulting 30 μm-thick sheet at 180°. When the sheet is bent at the same position two or more times, preferably five or more times, no cracks or breaks occur, and even more preferably ten or more times no cracks or breaks occur. The bending strength of the sheet can be determined specifically by the method described in the examples. As an example, it can be evaluated using a resin composition containing polylactic acid, a plasticizer, and a solvent, but not containing inorganic particles.

[0074] A method for producing a resin composition for baking according to one embodiment of the present invention can include a mixing step of mixing polylactic acid, a plasticizer, and other necessary materials in a known mixing device such as a mixer, blender, or roll to obtain a resin composition for baking.

[0075] 2. Firing Sheet and Ceramic Structure A firing sheet according to one embodiment of the present invention comprises the firing resin composition. The firing sheet includes a coating film and a wiring pattern formed from the paste, as well as a green sheet formed from the slurry. The firing sheet according to one embodiment of the present invention can have the tensile strength, elongation, and bending strength described above. Because the firing sheet according to one embodiment of the present invention has excellent sinterability, it can be fired at a low temperature to sufficiently reduce residual oxygen after firing, thereby reducing defects that may occur when firing at a high temperature. It can also be combined with materials with low heat resistance to produce laminates, ceramic structures, and the like. Furthermore, the firing sheet according to the present invention has excellent bending strength, which reduces the occurrence of cracks during processes such as stacking sheets and cutting laminated sheets, resulting in excellent handleability. The firing sheet according to one embodiment of the present invention can be used in ceramic structures, such as MLCCs (multilayer ceramic capacitors).

[0076] A method for producing a firing sheet according to one embodiment of the present invention can include a coating film formation step using a known method such as a doctor blade method or a screen printing method, and a drying step. A method for producing a ceramic structure according to one embodiment of the present invention can include a lamination step. In the lamination step, two or more sheets including the firing sheet can be laminated and pressure-bonded. A method for producing a ceramic structure according to one embodiment of the present invention can also include a degreasing step in which resins and plasticizers in the firing sheet are decomposed by heat treatment, and a firing step in which inorganic particles such as ceramics are sintered by heat treatment. According to one embodiment of the present invention, residual carbon can be sufficiently reduced, for example, at a degreasing temperature of 300°C or less.

[0077] The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited to these examples.

[0078] (Production Example 1) A reactor equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube was charged with 40 parts by mass of meso-lactide, 60 parts by mass of D-lactide, and 0.5 parts by mass of tin octoate, and the temperature was raised to 180°C while introducing nitrogen gas, and a polymerization reaction was carried out for 6 hours to obtain polylactic acid (A)-1 having a weight average molecular weight (Mw) of 50,000 and a molecular weight distribution (Mw / Mn) of 2.1. The proportions of constitutional units derived from the L-form component and the D-form component in the obtained polylactic acid (A)-1 were calculated from the proportions of the raw materials charged.

[0079] (Production Examples 2 to 7) Polylactic acids (A)-2 to (A)-7 were produced in the same manner as in Production Example 1, except that the types and / or amounts of raw materials were changed as shown in Table 1. In Production Examples 3 and 4, the amount of tin octoate used was 0.01 parts by mass.

[0080] (Production Example 8) 62.1 parts of 2-ethylhexyl acrylate, 2.5 parts of acrylic acid, and 4.3 parts of β-mercaptopropionic acid were added to a flask equipped with a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser. The contents were stirred for 30 minutes while introducing nitrogen gas into the flask to replace the atmosphere with nitrogen, and the contents of the flask were then heated to 60°C. Next, while maintaining the contents of the flask at 60°C, 0.06 parts of azobisisobutyronitrile was added to initiate the reaction. Thereafter, 0.06 parts of azobisisobutyronitrile was added six times every hour to allow the reaction to proceed, followed by a reaction at 100°C to 125°C for 3 hours. The volatile components in the product were removed by distillation under reduced pressure to obtain a carboxyl group-containing acrylic polymer. Next, 31.1 parts of bisphenol A epoxy resin ("jER828" manufactured by Mitsubishi Chemical Corporation) and an appropriate amount of epoxy curing catalyst (triphenylphosphine, "Hokuko TPP" manufactured by Hokko Chemical Industry Co., Ltd.) were charged into the flask and stirred at 110°C for 8 hours. The mixture was then cooled to room temperature to obtain an acrylic polymer. The acrylic polymer had an SP value of 10.2, an Mw of 5,800, and an Mn of 3,300.

[0081] <Weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn)> The Mw and Mn of polylactic acid were measured under the following conditions: Measurement device: HLC-8120GPC (manufactured by Tosoh Corporation) GPC column configuration: the following five columns in series (all manufactured by Tosoh Corporation) (1) TSK-GEL G7000HXL (2) TSK-GEL GMHXL (3) TSK-GEL GMHXL (4) TSK-GEL G2500HXL Sample concentration: 1.5 mg / cm ３ Mobile phase solvent: tetrahydrofuran Flow rate: 1 ml / min Column temperature: 40°C

[0082]

[0083] Example 1 10 parts by mass of polylactic acid (A)-1, 1 part by mass of acetyl tributyl citrate (ATBC), and 90 parts by mass of butyl carbitol acetate (BCA) were placed in a sealed container and stirred at 2000 rpm for 20 minutes using a planetary mixer "Awatori Rentaro" manufactured by THINKY, to obtain Resin Composition 1.

[0084] (Examples 2 to 14, Comparative Examples 1 and 2, Reference Example 1) Resin compositions according to Examples 2 to 14, Comparative Examples 1 and 2, and Reference Example 1 were obtained in the same manner as in Example 1, except that the components to be blended were changed as shown in Table 2. The ethyl cellulose used in Reference Example 1 was STD-type Ethocel (manufactured by Nisshin Chemical Industry Co., Ltd.).

[0085] The plasticizers used in the examples and comparative examples and their SP values ​​are as follows: Triacetin: SP value 10.2 (cal / cm ３ ) １／２ ATBC (acetyl tributyl citrate): SP value 9.8 (cal / cm ３ ) １／２ Triethyl citrate: SP value 11.5 (cal / cm ３ ) １／２ Acrylic resin (acrylic polymer prepared in Production Example 8): SP value 10.2 (cal / cm ３ ) １／２ DOP (dioctyl phthalate): SP value 9.5 (cal / cm ３ ) １／２

[0086] <Bakeability> The polylactic acid or ethyl cellulose of the Examples and Comparative Examples was baked (TG-DTA) at 300°C for 1 hour in a nitrogen atmosphere, and the presence or absence of residual carbon was visually confirmed, and the bakeability of the polymer was evaluated according to the following criteria. Apparatus name: Hitachi High-Tech Science STA7220 Atmosphere: N ２ 200 mL / min Temperature conditions: 40°C → 300°C Heating rate = 10°C / min Sample container: Aluminum open cell (Evaluation criteria) ◯: No carbon residue ×: Carbon residue

[0087] <Tensile Strength and Elongation> The resin compositions obtained in the Examples and Comparative Examples were coated on a polyethylene terephthalate (PET) film using a doctor blade and dried at 80°C for 5 minutes to form a layer with a thickness of 30 µm. The obtained layer was peeled from the PET film and punched into a dumbbell No. 3 shape. A tensile test was carried out at a pulling rate of 60 mm / min to measure tensile strength and elongation. The tensile strength refers to the strength at which the dumbbell test piece broke, and the elongation refers to the elongation until the dumbbell test piece broke.

[0088] <Bending strength> The compositions obtained in the examples and comparative examples were coated on a PET film using a doctor blade and dried at 80°C for 5 minutes to form a layer with a thickness of 30 μm. The obtained layer was peeled from the PET film and folded 180°, and the folding strength was evaluated according to the following criteria. The folding strength evaluation test was carried out by folding the same part 1 to 10 times or more. ◯: No cracks or breaks occurred even after folding 10 times or more △: Cracks or breaks occurred after folding 2 to 9 times ×: Cracks or breaks occurred after folding once

[0089]

Claims

Polylactic acid (A) and an SP value of 9.6 (cal / cm ３ ) １／２ A resin composition for baking, comprising the above plasticizer (B). 　 the polylactic acid (A) comprises at least one selected from polylactic acid (A1) and polylactic acid (A2), The polylactic acid (A1) has a D-form component content of 55 to 88 mass% relative to 100 mass% in total of the L-form component and the D-form component contained in the polylactic acid (A1), 2. The resin composition for baking according to claim 1, wherein the polylactic acid (A2) has an L-form component content of 55 to 88 mass% relative to a total of 100 mass% of the L-form component and the D-form component contained in the polylactic acid (A2).

3. The resin composition for baking according to claim 1, wherein the weight average molecular weight Mw of the polylactic acid (A) is 30,000 to 500,000. 　 The resin composition for baking according to claim 1 or 2, wherein the plasticizer (B) comprises at least one selected from the group consisting of hydroxycarboxylic acid esters, polyhydric alcohol esters, fatty acid esters, phthalic acid esters, acrylic resins having a number average molecular weight of 500 to 20,000, and polyesters having a number average molecular weight of 500 to 20,000. 　 The resin composition for baking according to claim 1 or 2, further comprising inorganic particles and a solvent. 　 A sheet for baking, comprising the resin composition for baking according to claim 1 or 2.

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