Binder resin, binder solution, ceramic composition, molded body of ceramic composition, multilayer ceramic capacitor, and method for manufacturing a multilayer ceramic capacitor.

Abstract

To provide a binder resin for ceramic firing that has a good balance of elongation and strength, exhibits a high modulus of elasticity, and has a low decomposition temperature. [Solution] A binder resin for ceramic firing is provided, comprising a polyurethane resin (U) having a structure derived from a polyol (A) having an alicyclic structure and a structure derived from a polyisocyanate (B), wherein the proportion of the alicyclic structure in the polyurethane resin (U) is 8 to 35% by mass, and the proportion of ester bonds in the polyurethane resin (U) is less than 10% by mass.

Description

Technical Field

[0001] The present invention relates to a binder resin for ceramic firing. The present invention also relates to a binder solution containing such a binder resin, a ceramic composition, a molded body of the ceramic composition, a multilayer ceramic capacitor obtained by using the molded body of the ceramic composition, and a method for manufacturing a multilayer ceramic capacitor.

Background Art

[0002] Ceramic products such as multilayer ceramic capacitors are generally manufactured by the following method: after obtaining ceramic green sheets using ceramic paste containing ceramic and a binder resin, the ceramic green sheets are optionally laminated alternately with conductive layers, then degreased and further fired; or the above steps are performed simultaneously or sequentially.

[0003] As a binder resin used for producing ceramic green sheets for multilayer ceramic capacitors, butyral resin has mainly been conventionally used, but in recent years, the use of resins other than butyral resin has also been studied.

[0004] For example, Cited Document 1 describes a binder for ceramic green tape, which is characterized by being composed of a hydrophobically modified polyurethane having a structure represented by a predetermined general formula (I), having a polymer molecular weight of at least 10,000 or more. Cited Document 2 describes a binder for ceramic molding composed of a water-soluble polyurethane (C) derived from a water-soluble polyoxyalkylene polyol (A) having a number average molecular weight of 2,000 to 25,000 and an organic polyisocyanate (B), having a weight average molecular weight of 10,000 to 300,000, and having an oxyethylene unit content of at least 80% by weight. Cited Document 3 describes a binder composition for forming a dielectric layer of a multilayer ceramic capacitor, which contains an aliphatic polyester polyurethane having an alicyclic organic group in the main chain.

Prior Art Literature

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2-307861 [Patent Document 2] Japanese Patent Application Publication No. 07-069739 [Patent Document 3] Japanese Patent Publication No. 2011-241120 [Overview of the project] [Problems that the invention aims to solve]

[0006] Through diligent research by the present inventors, we have found that there is room for improvement in the binder resins described in Patent Documents 1 to 3, from the viewpoint of blocking resistance, strength of ceramic green sheets, and productivity and quality of ceramic products.

[0007] The object of the present invention is to provide a binder resin for ceramic firing that has a good balance between elongation and strength, a high modulus of elasticity, and a low decomposition temperature. [Means for solving the problem]

[0008] The inventors of the present invention arrived at this invention as a result of various studies conducted to solve the above-mentioned problems. That is, the present invention has the following configuration. [1] A polyurethane resin (U) having a structure derived from a polyol (A) having an alicyclic structure and a structure derived from a polyisocyanate (B), The proportion of alicyclic structures in the polyurethane resin (U) is 8 to 35% by mass. The proportion of ester bonds in the polyurethane resin (U) is less than 10% by mass. Binder resin for ceramic firing. [2] The binder resin according to [1], wherein the polyisocyanate (B) has an aliphatic structure. [3] The binder resin according to [1] or [2], wherein the polyisocyanate (B) has an alicyclic structure. [4] The binder resin according to any one of [1] to [3], wherein the polyol (A) having an alicyclic structure is a polycarbonate polyol. [5] The binder resin according to any one of [1] to [4], wherein the polyurethane resin (U) further comprises a structure derived from a low molecular weight aliphatic polyol (C) different from the polyol (A) having the alicyclic structure. A binder solution comprising the binder resin and solvent described in any of [6] [1] to [5]. [7] A ceramic composition for firing, comprising a binder resin and a ceramic as described in any of [1] to [5]. [8] [7] A molded body of a ceramic composition for firing, comprising the ceramic composition described above. [9] The molded body of the ceramic composition according to [8], wherein the molded body of the ceramic composition is in the form of a film or a sheet.

[10] A multilayer ceramic capacitor obtained using a molded body of the ceramic composition described in [8] or [9]. A method for manufacturing a multilayer ceramic capacitor, comprising the steps of laminating a molded body of the ceramic composition described in

[11] [8] or [9] with an electrode layer, and then firing it. [Effects of the Invention]

[0009] The present invention provides a binder resin for ceramic firing that has a good balance of elongation and strength, a high modulus of elasticity, and a low decomposition temperature. [Modes for carrying out the invention]

[0010] In this specification, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. Furthermore, the amount of each component in a composition means the total amount of multiple substances present in the composition, unless otherwise specified, if there are multiple substances corresponding to each component in the composition. In this specification, the term "process" does not only include independent processes, but also includes processes that are not clearly distinguishable from other processes, as long as their intended purpose is achieved.

[0011] [Binder resin for ceramic firing] The binder resin of the present invention comprises a polyurethane resin (U) having a structure derived from a polyol (A) having an alicyclic structure and a structure derived from a polyisocyanate (B), wherein the proportion of the alicyclic structure in the polyurethane resin (U) is 8 to 35% by mass, and the proportion of ester bonds in the polyurethane resin (U) is less than 10% by mass, and is a binder resin for ceramic firing.

[0012] <Polyurethane resin (U)> The polyurethane resin (U) used in the present invention has a structure derived from a polyol (A) having an alicyclic structure and a structure derived from a polyisocyanate (B). This polyurethane resin (U) has an alicyclic structure proportion of 8 to 35% by mass and an ester bond proportion of less than 10% by mass.

[0013] The polyurethane resin (U) or the components from which each of its constituent units are derived may be those that are known. In addition, the polyurethane resin (U) may further have structures derived from low molecular weight aliphatic polyols (C) other than polyols (A) having an alicyclic structure, or structures derived from constituent units derived from chain extenders (D).

[0014] (Alicyclic structure) In the present invention, an alicyclic structure refers to an aliphatic cyclic structure containing carbon atoms and hydrogen atoms as constituent components, and if substituents are bonded to the alicyclic structure, it refers to the ring portion excluding those substituents. In other words, an alicyclic structure refers to a substructure consisting only of the group of atoms that form the ring in the alicyclic structure (a group of atoms consisting of carbon atoms and heteroatoms) and hydrogen atoms directly bonded to the atomic chain.

[0015] The alicyclic structure in the polyurethane resin (U) may contain heteroatoms (such as oxygen), but it is preferable that it be a hydrocarbon ring structure that does not contain heteroatoms. Furthermore, the alicyclic structure in the polyurethane resin (U) may be a condensed ring, but it is preferable that it be a non-condensed ring.

[0016] Examples of the alicyclic structure in the polyurethane resin (U) include cycloalkane rings such as cyclopentane ring, cyclohexane ring and cycloheptane ring; condensed hydrocarbon rings such as norbornane ring and tricyclodecane ring. Among these, cycloalkane rings are preferable, and cyclohexane ring is more preferable.

[0017] (Polyol (A) having an alicyclic structure) As the polyol (A) having an alicyclic structure used in the present invention, known ones can be used. For example, polyol monomers having an alicyclic structure, polycarbonate polyols having an alicyclic structure, polyester polyols having an alicyclic structure, polyether polyols having an alicyclic structure, polyurethane polyols having an alicyclic structure, polyester polyamide polyols having an alicyclic structure, acrylic polyols having an alicyclic structure, etc. can be used, and these may also be used in combination.

[0018] From the viewpoint of further improving strength, the polyol (A) having an alicyclic structure is preferably a polycarbonate polyol having an alicyclic structure and / or a polyether polyol having an alicyclic structure, and particularly preferably a polycarbonate polyol having an alicyclic structure. From the viewpoint of further improving the strength of the binder resin and suppressing hydrolysis of the binder resin, it is preferable that the polyol (A) having an alicyclic structure does not substantially contain a polyester polyol having an alicyclic structure. The polyol (A) having an alicyclic structure may be used alone, or two or more kinds thereof may be used in combination

[0019] Known polyol monomers having an alicyclic structure can be used. Examples include cycloalkanedimethanols such as 1,4-cyclohexanedimethanol and 1,3-cyclohexanedimethanol; cycloalkanediols such as 1,4-cyclohexanediol, 1,3-cyclopentanediol, and 1,4-cycloheptanediol; bicycloalkanediols such as 2,7-norbornanediol; tricycloalkanedimethanols such as tricyclodecanedimethanol; heterocycloalkanediols such as isosorbide; heterocycloalkanedimethanols such as 2,5-tetrahydrofrangimethanol; and heterobicycloalkanedimethanols such as spiroglycol. Among these, cycloalkanediols are preferred.

[0020] Polycarbonate polyols having an alicyclic structure are obtained by reacting a polyol monomer containing at least one polyol monomer having the alicyclic structure with a carbonate ester or phosgene. From the viewpoint of safety and handling of reagents, polycarbonate polyols obtained by reacting a polyol monomer containing at least one polyol monomer having the alicyclic structure with a carbonate ester are preferred because they are easy to manufacture and do not produce terminal chlorinated by-products.

[0021] At least a portion of the polyol monomers constituting the polycarbonate polyol having an alicyclic structure has an alicyclic structure. The content of the alicyclic structure is preferably 1 to 55% by mass, more preferably 1 to 50% by mass, even more preferably 5 to 45% by mass, and even more preferably 10 to 40% by mass, relative to the total amount of the polycarbonate polyol. When the content of the alicyclic structure is within the above range, it is preferable in that both high strength and high elongation can be achieved.

[0022] Polycarbonate polyols having an alicyclic structure may contain polyol monomers without an alicyclic structure as constituent components, in addition to the polyol monomers having an alicyclic structure. The polyol monomers without an alicyclic structure are not particularly limited and include, for example, linear aliphatic diols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, and 1,9-nonanediol; aliphatic polyols such as 2-methyl-1,3-propanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, and 2-methyl-1,8-octanediol; trimethylolpropane and other polyhydric alcohols with three or more functions; 1,4-benzenedimethanol, 1,3-benzenedimethanol, and 1,2-benzenedimethanol. Examples include aromatic diols such as lenzendimethanol, 4,4'-naphthalenedimethanol, and 3,4'-naphthalenedimethanol; polyester polyols of hydroxycarboxylic acids and diols such as the polyester polyol of 6-hydroxycaproic acid and hexanediol; polyester polyols of dicarboxylic acids and diols such as the polyester polyol of adipic acid and hexanediol; and polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Aliphatic polyols are preferred, linear aliphatic diols are more preferred, and 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol are even more preferred.

[0023] The polyol monomers constituting the polycarbonate polyol having an alicyclic structure may be used individually or in combination of multiple types. However, at least one polyol monomer having an alicyclic structure is included.

[0024] The carbonate ester is not particularly limited, but examples include aliphatic carbonate esters such as dimethyl carbonate and diethyl carbonate; aromatic carbonate esters such as diphenyl carbonate; and cyclic carbonate esters such as ethylene carbonate. In addition, phosgene, which can produce polycarbonate polyols, can also be used. Among these, aliphatic carbonate esters are preferred, and dimethyl carbonate is more preferred, due to the ease with which polycarbonate polyols having an alicyclic structure can be produced.

[0025] Polycarbonate polyols having an alicyclic structure may contain fewer ether bonds or ester bonds in their molecules than the average number of carbonate bonds in one molecule, provided that the properties of the polycarbonate polyol are not impaired. Note that the number of carbonate bonds is not included in the number of ester bonds.

[0026] The polycarbonate polyol having an alicyclic structure preferably has a number-average molecular weight (Mn) of 400 to 5,000. When Mn is 400 or higher, the elongation tends to improve. When Mn is 5,000 or lower, the reactivity between the polycarbonate polyol having an alicyclic structure and the polyisocyanate (B) does not decrease, and problems such as the polyurethane resin manufacturing process taking a long time or the reaction not proceeding sufficiently, or the viscosity of the polycarbonate polyol becoming high and difficult to handle do not occur. The Mn of the polycarbonate polyol having an alicyclic structure is more preferably 500 to 3,500, and even more preferably 600 to 2,500. In this invention, Mn is related to the hydroxyl value and 1 These values ​​were calculated from quantitative values ​​of the composition obtained by 1H-NMR or gas chromatography after alkaline hydrolysis.

[0027] A method for producing polycarbonate polyols having an alicyclic structure from polyol monomers and carbonate esters includes, for example, adding carbonate esters and an excess number of polyols relative to the number of moles of carbonate esters to a reactor, reacting at a temperature of 160-200°C and a pressure of about 50 mmHg for 5-6 hours, and then reacting further at a pressure of a few mmHg or less at 200-220°C for several hours. In the above reaction, it is preferable to remove the by-product alcohol from the system. In this case, if the carbonate ester is removed from the system by azeotrope with the by-product alcohol, an excess amount of carbonate ester may be added. Furthermore, a catalyst such as titanium tetrabutoxide may be used in the above reaction.

[0028] Known polyester polyols having an alicyclic structure can be used. For example, a polyester polyol obtained by esterifying a polyol monomer containing at least one polyol monomer having the alicyclic structure with a polycarboxylic acid can be used.

[0029] Polyester polyols having an alicyclic structure contain polyols having an alicyclic structure as constituent components. Examples include the polyol monomers having the alicyclic structure.

[0030] Polyester polyols having an alicyclic structure may contain polyol monomers that do not have an alicyclic structure as constituent components. For example, polyols that do not have an alicyclic structure are included.

[0031] Examples of polycarboxylic acids include aliphatic polycarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid; aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid; and anhydrides of the aliphatic and aromatic polycarboxylic acids. Polycarboxylic acids may be used individually or in combination of multiple types.

[0032] Known polyether polyols having an alicyclic structure can be used. Examples include homopolymers or copolymers of isosorbide, tetrahydroflange methanol, spiroglycol, etc.

[0033] (Polyisocyanate (B)) The polyurethane resin (U) has constituent units derived from polyisocyanate (B). Known polyisocyanates (B) can be used. For example, 1,3-phenylenediisocyanate, 1,4-phenylenediisocyanate, 2,4-tolylenediisocyanate (TDI), 2,6-tolylenediisocyanate, 4,4'-diphenylmethanediisocyanate (MDI), 2,4-diphenylmethanediisocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane Aromatic isocyanate compounds such as 1,5-naphthylene diisocyanate, 4,4',4''-triphenylmethane triisocyanate, m-isocyanatophenylsulfonyl isocyanate, p-isocyanatophenylsulfonyl isocyanate; ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6, Aliphatic isocyanate compounds such as 11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl) fumarate, bis(2-isocyanatoethyl) carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexanoate; isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane Examples of alicyclic isocyanate compounds include diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), cyclohexane-1,2-diylbis(methylene)diisocyanate (hydrogenated XDI), bis(2-isocyanatoethyl)-4-diclohexene-1,2-dicarboxylate, 2,5-norbornane diisocyanate, and 2,6-norbornane diisocyanate. Polyisocyanate (B) may have part or all of its structure derivatized by isocyanuration, carbodiimide, or biuretization.

[0034] Polyisocyanate (B) is preferably aliphatic in structure from the viewpoint of achieving both high strength and high elongation, and more preferably alicyclic in structure from the viewpoint of further increasing the modulus of elasticity. Among polyisocyanates (B), aliphatic acyclic isocyanate compounds and alicyclic isocyanate compounds are preferred from the viewpoint of achieving both high strength and high elongation, alicyclic isocyanate compounds are more preferred from the viewpoint of further increasing the modulus of elasticity, and isophorone diisocyanate (IPDI) and 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI) are even more preferred from the viewpoint of improving the modulus of elasticity. Polyisocyanate (B) may be used alone or in combination of multiple types.

[0035] Polyurethane resin (U) may have a blocked isocyanate structure. A blocked isocyanate structure is a structure in which a blocking agent is attached to an isocyanate group. In polyurethane resin (U), the blocked isocyanate structure is formed by attaching a blocking agent to the isocyanate group of a structure derived from some polyisocyanates (B), and is usually located at the ends of the polyurethane resin (U).

[0036] A blocking agent is a compound that can react with an isocyanate group to convert the isocyanate group into another group, and which can be reversibly converted back to an isocyanate group by heat treatment. The heat treatment temperature is not particularly limited, but 80 to 180°C is preferred.

[0037] Examples of blocking agents include phenols such as phenol; aliphatic alcohols such as methanol; active methylene compounds such as dimethyl malonate; mercaptans such as butyl mercaptan; acid amides such as acetanilide; lactams such as ε-caprolactam; acid imides such as succinimide; oximes such as acetaldehyde oxime, acetone oxime, and methyl ethyl ketoxime; and amines such as diphenylaniline, aniline, ethyleneimine, and dimethylpyrazole. Blocking agents may be used alone or in combination of multiple types. Blocked isocyanate structures may be used alone or in combination of multiple types.

[0038] (Low molecular weight aliphatic polyol (C)) In addition to the above, the polyurethane resin (U) preferably further contains structures derived from a low molecular weight aliphatic polyol (C) different from the polyol (A) having an alicyclic structure.

[0039] Examples of low molecular weight aliphatic polyols (C) include those similar to the specific examples of aliphatic polyols in the polyol monomers that do not have an alicyclic structure as described above. Among these, linear aliphatic diols are preferred, and 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol are more preferred.

[0040] The molecular weight of the low molecular weight aliphatic polyol (C) is preferably 60 to 140, and more preferably 80 to 120.

[0041] (Chain extender (D)) The polyurethane resin (U) may have structural units derived from a chain extender (D). The chain extender (D) is a component that increases the molecular weight of the polyurethane resin (U). The chain extender (D) is a compound other than a polyol (A) having an alicyclic structure, and is a compound having two or more groups that are reactive with an isocyanate group. The low molecular weight aliphatic polyol (C) described above can act as a chain extender (D).

[0042] Known chain extenders (D) can be used. Chain extenders (D) may be used alone or in combination of multiple types. Examples of chain extenders (D) include: polyols without an alicyclic structure; polycarbonate polyols without an alicyclic structure; polyester polyols without an alicyclic structure; polyether polyols without an alicyclic structure; polyurethane polyols without an alicyclic structure; polyesteramide polyols without an alicyclic structure; acrylic polyols without an alicyclic structure; acidic group-containing polyols such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, N,N-bishydroxyethylglycine, N,N-bishydroxyethylalanine, 3,4-dihydroxybutanesulfonic acid, 3,6-dihydroxy-2-toluenesulfonic acid; and ethylenediamine. Amine compounds such as mine, 1,4-tetramethylenediamine, 2-methyl-1,5-pentanediamine, 1,4-butanediamine, 1,6-hexamethylenediamine, 1,4-hexamethylenediamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, 1,3-bis(aminomethyl)cyclohexane, xylylenediamine, piperazine, hydrazine, adipodilazide, 2,5-dimethylpiperazine, diethylenetriamine, triethylenetetramine, polyetheramine, etc.; 1,3-diamino-2-propanol, 2,2'-(ethylenebisimino)bisethanol, N-(2-hydroxyethyl)-N'-(2-aminoethyl Examples include hydroxyl group-containing polyamines such as ethylenediamine, N-(3-hydroxypropyl)ethylenediamine, 2-[bis(2-aminoethyl)amino]ethanol, 1-[2-[(2-aminoethyl)amino]ethyl]amino-2-propanol, N,N-bis(hydroxyethyl)diethylenetriamine, N1,N4-bis(hydroxyethyl)diethylenetriamine, N1-(2-hydroxypropyl)triethylenetetraamine, N4-(2-hydroxypropyl)triethylenetetraamine, N-(2-hydroxypropyl)triethylenetetraamine, 2-(2-aminoethylamino)ethanol, and water.In particular, from the viewpoint of improving elastic modulus, polyol monomers without an alicyclic structure and polycarbonate polyols without an alicyclic structure are preferred, polyol monomers without an alicyclic structure are more preferred, and aliphatic polyols without an alicyclic structure are especially preferred.

[0043] (Composition of polyurethane resin (U)) The content of each structure in the polyurethane resin (U) is preferably as follows. In this specification, the content of each structure in the polyurethane resin (U) is a value calculated based on the blending amount (charging amount). The blending amount refers to the amount of raw material components for each structure used when manufacturing the polyurethane resin (U). Since all of the components react almost completely during the manufacturing of the polyurethane resin (U), the blending amount of each component is considered to be the content of each structure in the polyurethane resin (U).

[0044] The proportion of alicyclic structures in polyurethane resin (U) is the ratio of the molecular weight of the alicyclic structure portion to the molecular weight of the polyurethane resin (U). For example, if the structure contains a cyclohexane ring, the proportion of alicyclic structures indicates the proportion of cyclohexane residues. Here, cyclohexane residues refer to the structure of the cyclohexane ring excluding substituents when substituents are attached to the cyclohexane ring. To give a specific example, if the structure contains a dicyclohexylmethane structure, the proportion of alicyclic structures indicates the total proportion of cyclohexane residues.

[0045] The proportion of alicyclic structures in the polyurethane resin (U) is 8 to 35% by mass. From the viewpoint of lowering the decomposition temperature, a proportion of alicyclic structures of 9 to 32% by mass is more preferable, and 10 to 30% by mass is particularly preferable.

[0046] The proportion of alicyclic structures derived from polyol (A) having an alicyclic structure in the polyurethane resin (U) is not particularly limited, but is preferably 3 to 40% by mass, more preferably 5 to 35% by mass, and particularly preferably 5 to 30% by mass. Similarly, the proportion of alicyclic structures derived from polyisocyanate (B) in the polyurethane resin (U) is not particularly limited, but is preferably 0 to 32% by mass, and more preferably 5 to 30% by mass. Furthermore, the proportion of alicyclic structures derived from polyol (A) having an alicyclic structure (a) to the total amount ((a) + (b)) of alicyclic structures derived from polyol (A) having an alicyclic structure in the polyurethane resin (U) is not particularly limited, but is preferably 0.15 to 0.70, more preferably 0.20 to 0.65, even more preferably 0.30 to 0.60, and particularly preferably 0.35 to 0.55. By setting the range as described above, the proportion of alicyclic structures in the polyurethane resin is satisfied, and therefore the effects of the present invention tend to be more easily exhibited.

[0047] The proportion of ester bonds in the polyurethane resin (U) is less than 10% by mass. From the viewpoint of suppressing hydrolysis, the proportion of ester bonds is more preferably less than 8% by mass, and particularly preferably less than 6% by mass.

[0048] The structure derived from the polyol (A) having an alicyclic structure is preferably present in the polyurethane resin (U) at an amount of 25 to 65% by mass, and more preferably at an amount of 35 to 55% by mass.

[0049] The polyisocyanate (B)-derived structure is preferably present in the polyurethane resin (U) at an amount of 25-70% by mass, and more preferably at an amount of 35-60% by mass. If the polyurethane resin (U) has a blocked isocyanate structure, the content of the polyisocyanate (B)-derived structure includes the content of the blocked isocyanate structure.

[0050] When the polyurethane resin (U) has a structure derived from a low molecular weight aliphatic polyol (C), its proportion is preferably 2 to 20% by mass, and more preferably 5 to 15% by mass.

[0051] When the polyurethane resin (U) has a structure derived from the chain extender (D), its proportion is preferably 50% by mass or less, and more preferably 30% by mass or less.

[0052] In polyurethane resin (U), the proportion of urethane bonds is preferably 2.0 to 15.0% by mass, more preferably 3.0 to 12.0% by mass, and particularly preferably 4.0 to 9.0% by mass, based on solid content. By setting the urethane bond content within the above range, both high strength and high elongation can be achieved.

[0053] The weight-average molecular weight (Mw) of the polyurethane resin (U) is preferably 5,000 to 10,000,000, more preferably 8,000 to 5,000,000, and particularly preferably 10,000 to 1,000,000. The weight-average molecular weight is measured by gel permeation chromatography (GPC), and a conversion value obtained from a pre-prepared calibration curve of standard polystyrene can be used. A weight-average molecular weight of 5,000 or more tends to result in an excellent balance between high strength and high elongation. A weight-average molecular weight of 10,000,000 or less tends to lower the decomposition temperature of the polyurethane resin (U).

[0054] (Method of manufacturing polyurethane resin (U)) Polyurethane resin (U) can be obtained by any method within the range in which the desired polyurethane resin (U) can be obtained. For example, it can be obtained by a manufacturing method that includes the step of mixing a polyol (A) having an alicyclic structure, a polyisocyanate (B), a catalyst, a solvent, and optionally a low molecular weight aliphatic polyol (C) or a chain extender (D), and reacting them at preferably 0 to 150°C, more preferably 20 to 100°C.

[0055] In polyurethaneization reactions, known polymerization catalysts can be used to improve the reaction rate; for example, organometallic salts such as tertiary amines, tin, or titanium are used. For more information on polymerization catalysts, please refer to pages 23-32 of "Polyurethane Resins" by Keiji Yoshida (published by Nihon Kogyo Shinbunsha, 1969).

[0056] Polyurethane formation reactions can be carried out in the presence of solvents, such as esters including ethyl acetate, butyl acetate, propyl acetate, γ-butyrolactone, γ-valerolactone, and δ-caprolactone; amides including dimethylformamide, diethylformamide, and dimethylacetamide; sulfoxides including dimethyl sulfoxide; ethers including tetrahydrofuran, dioxane, dipropylene glycol dimethyl ether, and 2-ethoxyethanol; ketones including methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone; pyrrolidones including N-methylpyrrolidone and N-ethylpyrrolidone; and aromatic hydrocarbons such as benzene and toluene.

[0057] [Binder solution] The present invention provides a binder solution containing the binder resin and solvent for ceramic firing described above.

[0058] Examples of solvents contained in the binder solution of the present invention include water, methanol, ethanol, alcohols such as 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol; and 1,2-dimethoxyethane, acetone, methyl ethyl ketone, ethyl acetate, toluene, and xylene. Among these, organic solvents that dissolve the binder resin of the present invention as described above are preferred. These solvents can also be used in combination. The boiling point of the solvent is not particularly limited, but from the viewpoint of excellent drying properties, it is preferably 150°C or lower.

[0059] The content of the binder resin of the present invention in the binder solution of the present invention is not particularly limited, but is preferably 1 to 50% by mass, and more preferably 5 to 30% by mass.

[0060] The binder solution of the present invention can be produced, for example, by mixing a solvent with the binder resin of the present invention.

[0061] [Ceramic composition for firing, and molded body thereof] The binder resin of the present invention is used for molding a ceramic composition in a manufacturing method for obtaining a target ceramic molded body by firing a molded body of a ceramic composition (e.g., a ceramic green sheet). The firing process may be divided into a degreasing process in which organic matter is removed by evaporation and thermal decomposition, and a process in which the ceramic is sintered at a higher temperature, and these two processes may be carried out simultaneously, continuously, or intermittently. In other words, the binder resin of the present invention is a binder resin for molding a ceramic composition for firing (a ceramic composition before firing). The present invention provides a ceramic composition for firing, comprising the binder resin of the present invention and a ceramic, and a molded body of the ceramic composition for firing, comprising the ceramic composition.

[0062] The binder resin of the present invention has a good balance of elongation and strength, a high modulus of elasticity, and a low decomposition temperature. Furthermore, the binder resin of the present invention has a high Tg. Therefore, the binder resin of the present invention can provide molded articles of ceramic compositions that have excellent blocking resistance, strength, and durability, and furthermore, by using the binder resin of the present invention, firing of ceramic compositions can be carried out suitably.

[0063] <Ceramic composition for firing> The ceramic composition for firing according to the present invention contains a ceramic corresponding to the ceramic molded body to be fired according to the present invention and a binder resin according to the present invention. As the ceramic contained in the ceramic composition of the present invention, known ceramics can be used depending on the application. The ceramic composition of the present invention may contain only one type of ceramic or may contain two or more types of ceramics.

[0064] The ceramics contained in the ceramic composition of the present invention are usually in particulate form. The particle size and shape can be selected according to the desired properties of the ceramic molded body after firing, the firing conditions, and so on.

[0065] For example, when the purpose is to manufacture a multilayer ceramic capacitor including a ceramic dielectric layer, the ceramic composition used for firing is a composition containing ceramic particles for forming a dielectric material such as alumina or barium titanate and the binder resin of the present invention.

[0066] The ceramic composition of the present invention may contain, in necessary amounts, additives other than the binder resin and ceramic of the present invention. Examples of additives include dispersants and plasticizers.

[0067] <Molded body of ceramic composition for firing> By molding the ceramic composition for firing according to the present invention described above, a molded body of the ceramic composition for firing according to the present invention can be obtained.

[0068] The method for manufacturing a molded article of the ceramic composition of the present invention is not particularly limited, but for example, it can be manufactured by mixing the binder resin of the present invention, the ceramic constituting the ceramic composition, a solvent, and additives used as needed to obtain a ceramic paste, then molding the ceramic paste, and removing the solvent as needed.

[0069] Solvents that can be used in the production of molded articles of the ceramic composition of the present invention include those similar to the solvent contained in the binder solution of the present invention described above.

[0070] The order in which the binder resin, ceramic, and solvent are mixed is not particularly limited, but it is preferable to first mix the binder resin and solvent to prepare a binder solution, and then mix the binder solution with the ceramic. The binder solution of the present invention described above can be suitably used in such a manufacturing method.

[0071] The ceramic paste can be manufactured using known mixing equipment such as ball mills, paint shakers, and planetary mixers.

[0072] The method for molding the ceramic paste can be one that suits the desired shape of the molded ceramic composition. The shape of the molded ceramic composition according to the present invention can be one of the desired shapes for the ceramic molded body after firing. For example, the molded ceramic composition can be in the form of a film or a sheet.

[0073] A molded article of a ceramic composition may contain a solvent, but it is preferable that it be substantially solvent-free. A molded article of a ceramic composition that is substantially solvent-free can be obtained by removing the solvent after molding the ceramic paste. The method of removing the solvent is not particularly limited, but it is preferable to dry it at a low temperature near the boiling point of the solvent used. When removing the solvent, means such as vacuum drying or forced-air drying may be used.

[0074] For example, when the purpose is to manufacture a multilayer ceramic capacitor including a ceramic dielectric layer, it is preferable to apply a ceramic paste onto a carrier film and then remove the solvent to obtain a ceramic green sheet (a molded body of a ceramic composition) for the multilayer ceramic capacitor.

[0075] [Multilayer ceramic capacitor, and method for manufacturing the same] The molded body of the ceramic composition of the present invention described above can be suitably used in the manufacture of multilayer ceramic capacitors.

[0076] Multilayer ceramic capacitors can be manufactured by laminating ceramic green sheets (molded bodies of ceramic compositions) with electrode layers and then firing them.

[0077] The electrode layer is formed by known methods. For example, the ceramic green sheet and the electrode layer can be laminated by printing a conductive paste for the electrode layer in a desired pattern onto the ceramic green sheet using screen printing or gravure printing.

[0078] The green sheet with the electrode layer formed on it is peeled from the carrier film, and the electrode layer and dielectric layer are stacked alternately. Next, the sheets are heated and pressed at around 400-500°C, and then cut to produce green chips. The obtained green chips are fired at a high temperature of 1000°C or higher, and external electrodes are formed as needed, to obtain a multilayer ceramic capacitor in which the dielectric layer and electrode layer are stacked alternately, and external electrode layers are provided at both ends. [Examples]

[0079] Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these.

[0080] [Weight-average molecular weight of polyurethane resin] The weight-average molecular weight of the polyurethane resin was measured by gel permeation chromatography (GPC), and the converted value obtained from a pre-prepared calibration curve for standard polystyrene is shown.

[0081] [Percentage of alicyclic structures in polyurethane resin] The proportion of alicyclic structures in polyurethane resin was calculated using the following formula. (Percentage of alicyclic structures in polyurethane resin [mass %]) = [(Weight of polyol with alicyclic structure added [g]) / (Amount of polyurethane resin produced [g])] × (Percentage of alicyclic structures of polyol with alicyclic structure calculated from molecular weight [mass %])) + [(Weight of polyisocyanate added [g]) / (Amount of polyurethane resin produced [g])] × (Percentage of alicyclic structures of polyisocyanate calculated from molecular weight [mass %])

[0082] The following materials were used in the examples and comparative examples. ETERNACOLL® UM90(1 / 1): Polyol with an alicyclic structure (A); Manufactured by UBE Corporation; Number average molecular weight 905.6; Hydroxyl value 123.9 mgKOH / g; Polycarbonate diol obtained by reacting a polyol mixture with a molar ratio of 1,4-cyclohexanedimethanol:1,6-hexanediol with a carbonate ester; The proportion of the alicyclic structure is 27.3% by mass (represented as "UM90(1 / 1)" in the table). ETERNACOLL (registered trademark) UH100: A polyol without an alicyclic structure; manufactured by UBE Corporation; number average molecular weight 997.3; hydroxyl value 112.5 mgKOH / g; a polycarbonate diol, a reaction product of 1,6-hexanediol and carbonate ester (represented as "UH100" in the table). 1,4-Butanediol: A polyol without an alicyclic structure; a low molecular weight aliphatic polyol (C) (represented as "BDL" in the table). Isophorone diisocyanate; polyisocyanate (B); the proportion of alicyclic structures is 35.5% by mass (represented as "IPDI" in the table).

[0083] [Example 1] Binder resin for ceramic firing (1) A polyurethane resin solution with a weight-average molecular weight of 57,500 was obtained by heating polycarbonate polyol (ETERNACOLL® UM90 (1 / 1), 51.7 g), 1,4-butanediol (10.1 g), and isophorone diisocyanate (62.1 g) in N-ethylpyrrolidone (NEP, 399 g) in the presence of dibutyltin dilaurine (1.0 g) under a nitrogen atmosphere at 80-90°C for 9.5 hours. The obtained polyurethane resin solution was applied to a glass plate and dried at 70-90°C for 5 hours to obtain a binder resin (1) for ceramic firing.

[0084] [Example 2] Binder resin for ceramic firing (2) A solution of polyurethane resin with a weight-average molecular weight of 53,500 was obtained by heating polycarbonate polyol (ETERNACOLL® UM90 (1 / 1), 52.1 g), 1,4-butanediol (10.5 g), and isophorone diisocyanate (45.1 g) in N-ethylpyrrolidone (NEP, 401 g) in the presence of dibutyltin dilaurine (0.8 g) under a nitrogen atmosphere at 80-90°C for 10 hours. The obtained polyurethane resin solution was applied to a glass plate and dried at 70-90°C for 5 hours to obtain a binder resin (2) for ceramic firing.

[0085] [Example 3] Binder resin for ceramic firing (3) A polyurethane resin solution with a weight-average molecular weight of 61100 was obtained by heating polycarbonate polyol (ETERNACOLL® UM90 (1 / 1), 52.2 g), 1,4-butanediol (10.9 g), and isophorone diisocyanate (44.3 g) in N-ethylpyrrolidone (NEP, 400 g) in the presence of dibutyltin dilaurine (0.8 g) under a nitrogen atmosphere at 80-90°C for 9.5 hours. The obtained polyurethane resin solution was applied to a glass plate and dried at 70-90°C for 5 hours to obtain a binder resin (3) for ceramic firing.

[0086] [Comparative Example 1] Binder resin for ceramic firing (4) A solution of polyurethane resin with a weight-average molecular weight of 14100 was obtained by heating polycarbonate polyol (ETERNACOLL® UH100; manufactured by UBE Corporation; number average molecular weight 997.3; hydroxyl value 112.5 mg KOH / g; reaction product of 1,6-hexanediol and carbonate ester; alicyclic content 0% by mass, 54.7 g), 1,4-butanediol (10.0 g), and isophorone diisocyanate (51.3 g) in N-ethylpyrrolidone (NEP, 402 g) in the presence of dibutyltin dilaurine (0.3 g) under a nitrogen atmosphere at 80-90°C for 5 hours. The obtained polyurethane resin solution was applied to a glass plate and dried at 70-90°C for 5 hours to obtain a binder resin (4) for ceramic firing.

[0087] The ceramic firing binder resins (1) to (4) obtained above contained structures derived from the polyol and polyisocyanate used in their production in proportions equivalent to those used, and did not contain ester bonds. Using the ceramic firing binder resins (1) to (4) obtained above, the proportion of alicyclic structures and the weight-average molecular weight were measured according to the method described above, and the following properties were measured and evaluated. The results are shown in Table 1.

[0088] [Glass transition temperature (Tg) measurement] The glass transition temperature (Tg) was obtained by analyzing dynamic viscoelastic data measured on films made by cutting the ceramic firing binder resins (1) to (4) obtained above into 5cm x 5cm pieces, using a TA Instruments "RSA-G2" under tensile mode, frequency of 1Hz, and heating rate of 3°C / min in the range of -100 to 200°C. The glass transition temperature (Tg) was defined as the intersection of the tangents before and after the inflection point of the E' (storage modulus) chart. From the viewpoint of blocking resistance, a glass transition temperature (Tg) of 40°C or higher is preferable.

[0089] [Measurement of thermal decomposition properties] The films prepared by cutting 10 mg of the ceramic firing binder resins (1) to (4) obtained above were heated from room temperature to 600°C at a heating rate of 10°C / min in an air atmosphere using a Hitachi High-Tech Science TG / DTA6300, and the thermal decomposition characteristics were evaluated by analyzing the resulting thermogravimetric curve. The 98% decomposition temperature (Td98) was defined as the temperature at which the weight on the thermogravimetric curve becomes 2% of the initial weight. A 98% decomposition temperature (Td98) of less than 530°C is preferred. The 500°C retention rate was defined as the percentage of resin remaining at 500°C on the thermogravimetric curve. A 500°C retention rate of less than 4% is preferred.

[0090] [Measurement of elastic modulus, tensile strength, and elongation at break] Test specimens were prepared by punching out the ceramic firing binder resins (1) to (4) obtained above using a Super Dumbbell® cutter (SDK-300) from Dumbbell Co., Ltd. The obtained test specimens were subjected to tensile testing using an Instron 5982 universal testing machine in accordance with JIS K 7311. The measurement conditions were 23°C, 50% humidity, a 500N load cell, and a tensile speed of 100 mm / min. The modulus of elasticity is preferably 1,000 MPa or higher, the tensile strength is preferably 50 MPa or higher, and the elongation at break is preferably 5% or higher. In this application, the modulus of elasticity in the tensile test at 23°C is simply referred to as the modulus of elasticity. From the viewpoint of blocking resistance, a modulus of elasticity of 1,000 MPa or higher is preferred. Polyurethanes with a modulus of elasticity of 1,000 MPa or higher generally have a glass transition temperature (Tg) higher than room temperature (23°C), resulting in good blocking resistance.

[0091] [Table 1]

[0092] As shown in Table 1, Examples 1 to 3 all exhibit a good balance of elongation and strength, high modulus of elasticity, and low decomposition temperature. In particular, Example 1 yielded a good binder resin for ceramic firing with a high Tg of 40°C or higher, a modulus of elasticity of 1,000 MPa or higher, a tensile strength of 50 MPa or higher, and an elongation at break of 5% or higher, while maintaining a low decomposition temperature. Furthermore, as shown in Example 2, even when the mixing ratio was changed, a good binder resin for ceramic firing was obtained with a good balance of elongation and strength, high modulus of elasticity, and a low decomposition temperature. Moreover, as shown in Example 3, even when the weight-average molecular weight was changed, a good binder resin for ceramic firing was obtained with a good balance of elongation and strength, high modulus of elasticity, and a low decomposition temperature. It can also be inferred that Examples 2 and 3 exhibit a Tg equivalent to that of Example 1.

[0093] On the other hand, Comparative Example 1 showed that when a polyol having an alicyclic structure was not included, the elastic modulus and tensile strength were inferior compared to Examples 1-3. In particular, the Tg value was extremely low compared to Example 1.

[0094] [Solubility Test] [Reference example 1] When 0.2 g of the ceramic firing binder resin (1) obtained in Example 1 was immersed in 0.8 g of toluene / ethanol = 1 / 1 (weight ratio) and left to stand at 23°C for 18 hours, it was visually confirmed that the ceramic firing binder resin (1) had completely dissolved.

[0095] [Reference example 2] Solubility was evaluated in the same manner as in Reference Example 1, except that 1,2-dimethoxyethane was used instead of toluene / ethanol = 1 / 1. It was visually confirmed that the binder resin (1) for ceramic firing was completely dissolved.

[0096] [Reference example 3] Solubility was evaluated in the same manner as in Reference Example 1, except that cyclopentanone was used instead of toluene / ethanol = 1 / 1. It was visually confirmed that the binder resin (1) for ceramic firing was completely dissolved.

[0097] In the manufacture of multilayer ceramic capacitors, the binder resin used for ceramic firing is sometimes dissolved in an organic solvent. The results from Reference Examples 1-3 show that the binder resin for ceramic firing of the present invention is readily soluble in organic solvents. Therefore, the binder resin for ceramic firing of the present invention is suitable for use in the manufacture of multilayer ceramic capacitors in terms of its solubility. [Industrial applicability]

[0098] The binder resin for ceramic firing according to the present invention has a good balance of elongation and strength, a high modulus of elasticity, and a low decomposition temperature, making it suitable for use in the manufacture of multilayer ceramic capacitors.

Claims

1. The present invention comprises a polyurethane resin (U) having a structure derived from a polyol (A) having an alicyclic structure and a structure derived from a polyisocyanate (B), The proportion of alicyclic structures in the polyurethane resin (U) is 8 to 35% by mass. The proportion of ester bonds in the polyurethane resin (U) is less than 10% by mass. Binder resin for ceramic firing.

2. The binder resin according to claim 1, wherein the polyisocyanate (B) has an aliphatic structure.

3. The binder resin according to claim 1, wherein the polyisocyanate (B) has an alicyclic structure.

4. The binder resin according to claim 1, wherein the polyol (A) having the alicyclic structure is a polycarbonate polyol.

5. The binder resin according to claim 1, wherein the polyurethane resin (U) further comprises a structure derived from a low molecular weight aliphatic polyol (C) different from the polyol (A) having the alicyclic structure.

6. A binder solution comprising the binder resin and solvent according to claim 1 or 2.

7. A ceramic composition for firing, comprising the binder resin and ceramic according to claim 1 or 2.

8. A molded body of a ceramic composition for firing, comprising the ceramic composition described in claim 7.

9. The molded body of the ceramic composition according to claim 8, wherein the molded body of the ceramic composition is in the form of a film or a sheet.

10. A multilayer ceramic capacitor obtained using a molded body of the ceramic composition described in claim 8.

11. A method for manufacturing a multilayer ceramic capacitor, comprising the steps of laminating a molded body of the ceramic composition according to claim 8 with an electrode layer, and then firing it.

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