JPH11106267A - Binder for forming ceramic and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a binder for forming ceramic, having good drying property and hygroscopic property, enabling formation of thin film of green sheet in formed product of ceramics, having high strength of green sheet, free from warping or crack of sheet and having good releasing property from a substrate film used in sheet preparation and free from occurrence of crack in sintering. SOLUTION: This binder for forming ceramic consists essentially of an acrylic water-dispersible copolymer resin obtained by subjecting a radical polymerizable monomer mixture containing 5-40 pts.wt. (meth)acrylonitrile, 5-90 pts.wt. (meth) acrylate and 0.01-20 pts.wt. unsaturated carboxylic acid to emulsion polymerization or suspension polymerization in the presence of a water-soluble or water- dispersible polymer. The copolymer resin has preferably a heterogeneous layer structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous binder resin used as a binder in forming ceramics and a method for producing the same.

[0002]

2. Description of the Related Art In order to manufacture molded articles before sintering of ceramics, for example, a sheet of barium titanate used as a multilayer capacitor and a sheet of alumina used as a substrate of an electric circuit, a fine powder of ceramics is formed using a resin binder. Then, it is formed into a predetermined shape, formed into a green sheet, and then fired.

[0003] As the above-mentioned binder, a solution-type binder in which a resin such as polyvinyl butyral is dissolved in an organic solvent has been conventionally used. However, as a problem based on the use of the organic solvent is pointed out, an aqueous solvent is used. Resins, for example, aqueous resins such as polyvinyl alcohol, polyvinyl acetate emulsion, water-soluble polyurethane resin, and acrylic resin emulsion have come to be used. The following are known as such aqueous resins.

(A) A combination of a water-soluble polyurethane resin and an acrylic resin (Japanese Patent Laid-Open No.
8-190867). (B) using a copolymer of an acrylate ester and a carboxyl group-containing monomer (JP-A-59-12115)
No. 2, JP-A-60-122768, JP-A-60-122768
122767). (C) those using a copolymer containing an ester of an alkoxy (poly) ethylene glycol and an unsaturated carboxylic acid as essential components (JP-A-60-122770,
JP-A-60-155567). (D) A polymer obtained by neutralizing a polymer obtained by reacting a copolymer having a carboxyl group with an alkyleneimine with an acidic reagent (JP-A-1-226762). (E) Aqueous (meth) acrylic resin using a binder having improved dispersibility of ceramic slurry and redispersibility of molded article in water (Japanese Patent Laid-Open No. 1-2869)
No. 55).

[0005]

However, the above-mentioned water-soluble or water-dispersible resin binder causes the dried ceramic green sheet (sheet before sintering) to warp or crack, and cracks occur during sintering. And the need to use a plasticizer to adjust the physical properties of the dried ceramic green sheet, etc., and in addition to the above, especially in the case of a water-soluble resin, the drying property of the molded sheet,
Hygroscopicity is a problem. When an emulsion resin having a large particle size, such as a polyvinyl acetate emulsion, is used as a binder, the particle size of the emulsion resin is larger than that of ceramic fine particles, and thus there is a limit to the thinning of a sheet recently required. Further, JP-A-1-28695
According to the technology described in Japanese Patent Application Publication No. 5 (1993) -205, the above-mentioned problems of dryness and hygroscopicity can be solved and the sheet can be made thinner. There are problems such as cracking, cracking, insufficient releasability from a base film used for producing a green sheet, and cracking during sintering.

According to the present invention, sufficient strength and elongation of a sheet can be obtained without using a plasticizer even in thinning, and the sheet has good releasability from a base sheet, and warping and cracking of the sheet can be prevented. A water-based ceramic molding binder which does not generate and has the function of preventing the generation of cracks during sintering, and a method for producing the same.

[0007]

According to the present invention, there is provided a ceramic molding binder comprising: (b) 5 to 40 parts by weight of (meth) acrylonitrile (c) (meth) acrylate in the presence of an aqueous polymer (a) 5 to 95 parts by weight (d) unsaturated carboxylic acid 0.01 to 20
It is characterized by containing an acrylic water-dispersed copolymer resin obtained by emulsion polymerization or suspension polymerization of a radical polymerizable monomer containing parts by weight as a main component.

As a result of repeated experiments, the inventor has found that a ceramic sheet formed by using a polymer having the above-described monomer composition as a binder can obtain a thin film sheet having sufficient sheet strength. The present inventors have found that the releasability of the sheet from the substrate film is good, the sheet does not warp or crack, and the occurrence of cracks during sintering is small, and the present invention has been completed.

(Meth) acrylonitrile means containing one or both of acrylonitrile and methacrylonitrile, and (meth) acrylic ester contains at least one ester selected from acrylic esters and methacrylic esters. Means that.

[0010] The component (b) (meth) acrylonitrile is copolymerized with the alkyl ester having a relatively large number of carbon atoms in the component (c) to impart the strength, flexibility and good decomposability of the binder. Has an action.
If the component (b) is less than 5 parts by weight, the sheet strength is weak and the elongation is reduced. If it exceeds 40 parts by weight, the green sheet becomes too hard and the decomposability of the binder during ceramic sintering decreases. In particular, when a (meth) acrylic acid ester having a long-chain alkyl group is used, the glass transition temperature of the copolymer is lowered and the resin is given flexibility, so that a plasticizer is used to adjust the physical properties of the binder resin. The advantage is that it does not need to be used. The component (b) is particularly preferably in the range of 10 to 30 parts by weight, since a binder having a good balance of hardness, strength and degradability of the green sheet can be obtained.

The (meth) acrylic ester of the component (c) has a function of imparting rigidity to the binder resin of the present invention according to the type selected, and has a property of being excellent in decomposability during green sheet sintering. Demonstrate. (C) component is 5
In the case of less than parts by weight, other monomer components increase relatively, and the properties of the binder resin cannot be sufficiently adjusted,
Degradability also decreases. When the amount is more than 95 parts by weight, there is a problem that the sheet strength is reduced. The component (c) is more preferably in the range of 20 to 90 parts by weight, and the most preferable characteristics are obtained in the range of 50 to 90 parts by weight.

The unsaturated carboxylic acid as the component (d) has a function of mainly stabilizing the particles of the aqueous dispersion resin as the binder resin of the present invention. When the amount of the component (d) is less than 0.01 part by weight, the stability of the particles is not sufficient, so that the stability of the water-dispersed resin particles is lost when the ceramic slurry is blended, and the particles are aggregated to produce a uniform sheet. Becomes difficult. If the amount is more than 20 parts by weight, the cohesive strength and hydrophilicity of the resin become too large, causing the sheet to be warped or cracked, and also causes problems in drying properties and moisture absorption. The component (d) is particularly preferably in the range of 0.5 to 10 parts by weight, and good binder characteristics can be obtained.

The water-based polymer (a) in the present invention means a water-soluble or water-dispersible polymer. In particular, this water-based polymer preferably has a crosslinkable functional group capable of causing a crosslinking reaction. . As a result of the strength of the binder resin itself being improved by the crosslinking of the binder polymer with such a crosslinkable functional group, the effect of improving the physical properties, particularly the strength, of the green sheet is obtained.

The above-mentioned aqueous polymer (a) has an important effect in the production of the aqueous dispersion of the binder resin of the present invention and in the storage state after the production, and also has an important effect on the stability of the system, and is used as an initiator or a dispersion medium such as water. It also has the effect of reducing impurities such as metal ions and sulfate ions that affect the electrical properties of ceramic products.

The acrylic water-dispersed copolymer resin as the ceramic molding binder according to claim 1 or 2 is preferably a particle having a hetero-layer structure,
The first resin forming the inner layer of the particles has a glass transition temperature of −50 to 20 ° C., and the second resin formed as the outer layer of the first resin has a glass transition temperature of 0 to 50 ° C.
It is preferred that the That is, the ceramic molding binder resin of the present invention comprises an outer layer made of a relatively rigid second resin, an inner layer made of a relatively soft first resin, and a layer of a highly hydrophilic aqueous polymer resin surrounding the outer layer. It is preferable that it is comprised.

When the particles of ceramics are bonded by using such a resin having a different layer structure as a binder,
When stress is applied to the obtained ceramic green sheet from the outside, the stress is relieved, and an excellent effect of preventing warpage and cracking of the green sheet is obtained as compared with a case where a binder having a single structure is used. .

When the glass transition temperature of the first resin is 20 ° C. or higher, the resin becomes a glassy state at around room temperature, the flexibility of the binder is reduced, and the green sheet is likely to be warped or cracked. On the other hand, when the glass transition temperature of the second resin is 0 ° C. or lower, the green sheet becomes too flexible, and the releasability from the base film becomes poor. On the other hand, when the temperature is 50 ° C. or higher, the film forming property of the aqueous dispersion becomes poor, and it is difficult to obtain a uniform green sheet.

A green sheet using an aqueous dispersion of particles having the above structure as a binder does not warp or crack, and hardly cracks during sintering.
Also, the releasability of the green sheet and the base film becomes excellent. It is considered that such an effect can be obtained by providing a layer of the second resin having a high glass transition temperature around the flexible first resin having a low glass transition temperature.

The particle size of the acrylic water-dispersed copolymer resin in the present invention is preferably from 0.05 to 1 μm. A problem arises in sex. On the other hand, if it is 1 μm or more, the particle diameter becomes large, so that it is difficult to reduce the thickness of the ceramic sheet. The production of such an acrylic water-dispersed copolymer resin having an average particle diameter of about 1 μm or less is preferably emulsion polymerization.

In the particles having a different layer structure according to the third aspect, the second resin constituting the outer layer is preferably a resin having a short-chain alkyl ester as a main component among (meth) acrylates. Yes, glass transition temperature is 0-50
C resin is easily formed. The second resin contains at least a monomer having a hydrophilic functional group and a monomer having a reactive functional group in addition to the above-mentioned (c) component, which is a relatively short-chain alkyl (meth) acrylate. It is preferably a polymerized one, and a part of the monomer (d) is used.

The first resin constituting the inner layer is (b)
(Meth) acrylonitrile and (meth) component (c)
Among the acrylates, it is preferable to use a resin having a relatively long-chain alkyl (meth) acrylate as a main component, and a resin having a glass transition temperature of −50 to 20 ° C. is easily formed. . Like the second resin, the first resin is preferably a copolymer of at least a monomer having a hydrophilic functional group and a monomer having a crosslinkable functional group, and is preferably a monomer having a hydrophilic functional group. As the body, a part of the monomer (d) is used.

The component (c) (meth) acrylate used as the first resin component is preferably a relatively long-chain alkyl group ester as described above.
When used as the second resin component, an ester of a relatively short-chain alkyl group is preferable, but a short-chain alkyl ester may be partially used in the first resin component,
Part of the ester of a long-chain alkyl group may be used as the resin component.

The present invention also relates to a method for producing a binder for forming a ceramic containing an acrylic water-dispersed copolymer resin comprising particles having a different layer structure, wherein the production method comprises a water-soluble or water-dispersible polymer ( (b) using a radical polymerization initiator in the presence of (a), (b) (meth) acrylonitrile and (c) component (meth) acrylate, a relatively long-chain alkyl (meth) acrylate Is formed by polymerizing a monomer containing as a main component an outer layer to form a second resin, and then (c) polymerizing a monomer containing a (meth) acrylate ester as a main component to form an inner layer. 1 resin.

The acrylic water-dispersed copolymer resin produced by the above-described production method is presumed to constitute the above-mentioned particles having a different layer structure from the properties and the effect as a binder.

In the above-mentioned production method, it is preferable to use a compound containing no metal ion as the radical polymerization initiator. When metal ions that do not volatilize by heating remain when firing the green sheet of ceramics to produce the target product, the electrical characteristics of the sheet, which is a fired product of ceramics, are reduced when used for electrical products such as capacitor parts. May be impaired.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The raw materials used in the present invention are as follows. As the water-based polymer (a), a polymer material having many functional groups such as a hydrophilic carboxyl group and a hydroxyl group in a molecule is used. Specifically, methyl cellulose,
Cellulose derivatives such as hydroxyethylcellulose and carboxymethylcellulose, and compounds forming protective colloids such as water-soluble polyurethane resin, water-soluble acrylic resin, polyvinylpyrrolidone-based resin, polyvinyl alcohol and starch can be used.
More than one species may be used in combination.

Particularly, as the aqueous polymer having a crosslinkable functional group as described in claim 2, a polymer obtained by copolymerizing a monomer having a reactive functional group is preferable. The acrylic resin or the acrylic resin emulsion, that is, the water-based acrylic resin, can be exemplified as a preferable example.

The above-mentioned water-based acrylic resin can be obtained by copolymerizing a hydrophilic monomer, a monomer having a crosslinkable functional group and, if necessary, other monomers. A crosslinkable functional group is a functional group that forms a crosslink between polymer molecules by reacting at room temperature or under heating, and includes a hydrolyzable silyl group and a glycidyl group. Is preferably a hydrolyzable silyl group, particularly an alkoxysilyl group.

As the (meth) acrylate (c), acrylates such as alkyl acrylates and methacrylates such as alkyl methacrylates can be used. Among these (meth) acrylic acid esters, a compound that is preferably used to form the first resin together with (meth) acrylonitrile is a relatively long-chain alkyl ester having about 4 or more carbon atoms. Yes, specifically, n-butyl acrylate, 2-ethylhexyl acrylate, isobutyl acrylate,
Examples thereof include n-butyl methacrylate, isobutyl methacrylate, lauryl methacrylate, and stearyl methacrylate.

The compound which can be used for forming the second resin is a relatively short-chain alkyl ester having about 3 carbon atoms or less, and specifically, methyl acrylate, ethyl acrylate, n- or iso- -Propyl acrylate, methyl methacrylate, ethyl methacrylate, n- or iso-propyl methacrylate and monomers having a functional group added thereto.

In the present invention, other monomers may be copolymerized in addition to the monomers (b) and (c). Particularly, the second resin forming the outer layer having a high glass transition temperature may be used. Examples of the monomer to be used include styrene-based monomers such as styrene, α-methylstyrene and vinyltoluene, vinyl halides such as vinyl chloride, and vinylidene halides such as vinylidene chloride. Further, two or more monomers can be selected and used in combination.

A first method for forming an inner layer having a low glass transition temperature
Examples of the monomer used as a raw material for the resin include, in addition to the above-mentioned (meth) acrylic acid ester having a relatively long-chain alkyl group, vinyl monomers such as vinyl alcohol derivatives such as vinyl acetate, and butadiene. And conjugated diene monomers such as isoprene and chloroprene.

As the unsaturated carboxylic acid component (d) used in the present invention, a compound having a carboxyl group and having a radically polymerizable unsaturated bond can be used without any particular limitation. Specific examples include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, and itaconic acid.

Other hydrophilic monomers can be used together with the above unsaturated carboxylic acids. For example, monomers having a hydroxyl group, polyoxyethylene group, etc. can be used. Examples include vinyl esters, hydroxyl group-containing vinyl ethers, hydroxyl group-containing acrylic or methacrylic esters. Specific examples include hydroxyalkyl vinyl ethers, hydroxyalkyl vinyl esters, hydroxyalkyl (meth) acrylates, hydroxyalkyl (meth) acrylates, and other hydroxyalkyl acrylates, hydroxyalkyl methacrylates, glycidyl methacrylate, methoxydiethylene methacrylate, and methoxydiethylene. It is preferable to use methacrylate, methoxypolyethylene glycol methacrylate, or the like. Further, a monomer having a sulfonate group, acrylamide, vinylpyrrolidone and the like can be used.

The above-mentioned monomer having a carboxyl group or another hydrophilic functional group can be used as a raw material when synthesizing the aqueous polymer (a).

In addition to the above monomers, it is also desirable to use a bifunctional or higher functional monomer for controlling the physical properties of the binder resin. Examples of such a monomer include divinylbenzene, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, allyl methacrylate, diallyl phthalate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triallyl isocyanurate and the like.

Incidentally, any of the monomers exemplified above is
If the properties required by copolymerization, particularly the glass transition temperature, are satisfied, it can be used for both the first resin and the second resin. Also, it can be used as a monomer constituting a polymer using a vinyl monomer such as an aqueous acrylic resin used as the aqueous polymer (a).

Specific examples of the monomer having an alkoxysilyl group exemplified as a reactive silicon group as a crosslinkable functional group include vinyltrichlorosilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (2- (Methoxyethoxy) silane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltris (2-methoxyethoxy) silane, vinyltriacetoxysilane, 3-acryloxypropyltrimethoxysilane, allyltriethoxysilane, allyltrimethoxy Silane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, vinylmethyldiacetoxysilane, 3-methylacryloxypropylmethyl-diethoxysilane, 3-acryloxypropyldimethylmethoxysilane It can exemplified down like may be used alone, or may be used in combination of two or more.

Glycidyl acrylate and glycidyl methacrylate are typical examples of the monomer having a glycidyl group.

The above-mentioned monomer having a crosslinkable functional group is also the first monomer.
, The second resin and the component constituting the water-based polymer (a). Crosslinkable functional groups are primary
When applied to the second resin and the second resin, it mainly contributes to the bonding between the inner layer and the outer layer, and as a result, the effect of increasing the strength of the binder resin is exhibited. Further, when applied to the aqueous polymer (a) or the second resin, it mainly contributes to the bonding between the binder particles, and as a result, has the effect of improving the strength of the green sheet.

As the initiator for initiating the polymerization of the above-mentioned monomer, a well-known initiator can be used, but as described in claim 5, it remains as ions in the ceramic molded article even after firing, Initiators containing metal ions and sulfate ions that affect electrical properties are not preferred. Examples of suitable initiators in the present invention include azo initiators such as azobisisobutyronitrile, benzoyl peroxide, ME
Peroxide initiators such as K peroxide and t-butyl hydroperoxide can be exemplified.

In order to ensure the polymerization conversion and polymerization stability, there is no problem in using ammonium persulfate or the like to such an extent that there is no problem if it remains in the ceramic product. Further, it is particularly preferable to use a reducing agent such as L-ascorbic acid or erythorbic acid to reduce the amount of the initiator used.

The above-mentioned polymerization initiator can be applied to both the polymerization of the first resin and the polymerization of the second resin, and it is also preferable to use the polymerization initiator for producing the aqueous polymer (a) used as a protective colloid.

It is also preferable to use an emulsifier in combination to emulsify the above-mentioned monomers. As such an emulsifier, a known surfactant can be used. Among the emulsifiers, use of a nonionic emulsifier is particularly preferable because of its excellent stability. It is also preferable to use a small amount of an anionic surfactant or a reactive surfactant in consideration of the polymerizability.

The acrylic water-dispersed copolymer resin constituting the binder of the present invention is preferably of a so-called soap-free type, and such a soap-free water-dispersed resin is produced using a reactive surfactant. . In the present invention, reactive surfactants known to those skilled in the art can be used without any particular limitation. Examples of commercially available reactive surfactants include latemul (manufactured by Kao) and eleminol (manufactured by Sanyo Chemical Industries). And a series of products such as Aqualon (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), all of which can be used.

The acrylic water-dispersed copolymer resin of the present invention is synthesized by a method well known to those skilled in the art. The following is an example of a method for producing an acrylic water-dispersed copolymer resin having a different layer structure, which is particularly preferred in the present invention. First, a water-soluble polymer and a monomer previously emulsified with a surfactant are added to water to which a necessary surfactant has been added. A step-forming polymerization is performed to produce a polymer that forms an inner layer. Next, the emulsified polymer and the initiator are added to carry out the second-stage polymerization to form the resin constituting the outer layer, whereby a water dispersion of the resin having a hetero-layer structure is obtained.

The method for preparing a ceramic green sheet using the ceramic molding binder of the present invention is a method well known to those skilled in the art. In general, a liquid containing a binder resin and a fine powder of a ceramic to be molded are mixed and uniformly dispersed by a dispersing device such as a ball mill or an ultrasonic disperser to form a slurry. After the obtained ceramic slurry is defoamed, It is formed by forming into a sheet shape on a base film using a doctor blade or the like and drying.

[0048]

Embodiments of the present invention will be described below. In this example, a production example of an aqueous dispersion having a hetero-layer structure which is particularly preferable in the present invention will be described. (1) Preparation of Aqueous Copolymer Component Using raw materials having the composition shown in Table 1, polymerization was carried out in an organic solvent soluble in water, and after removing the organic solvent, the mixture was neutralized with an alkali. To obtain an aqueous polymer solution having a solid content of 25% by weight. This aqueous liquid is an aqueous solution or an aqueous dispersion, and is hereinafter referred to as an aqueous copolymer component (A).

[0049]

[Table 1]

(2) Synthesis of Acrylic Aqueous Dispersion Copolymer Resin [Example] Acrylonitrile (AN), methyl methacrylate (MMA), methyl acrylate (MA), n-
Using butyl acrylate (BA), acrylic acid (AA), diallyl phthalate (DAP), triallyl isocyanurate (TAIC), and γ-methacryloxypropyltrimethoxysilane as an alkoxysilyl group-containing monomer as raw materials, Monomer emulsion composition B (B1 to B6), monomer emulsion composition C (C1 to
C6) was prepared and polymerized by the method described below. The monomer emulsion (B) is polymerized by a first-stage polymerization reaction to form an inner layer (core), and the monomer emulsion (C) is polymerized by a second-stage polymerization reaction to form an outer layer (shell). To form The monomer emulsion composition B and the monomer emulsion composition C are:
The monomers were mixed and emulsified at the ratios shown in Tables 2 and 3 to obtain monomer emulsions (B) and (C). Monomer emulsion (B)
Has a monomer concentration of 69% by weight and is a monomer emulsion (C)
Had a monomer concentration of 69% by weight.

[0051]

[Table 2]

[0052]

[Table 3]

(4) Preparation of Aqueous Resin Dispersion In a reaction vessel equipped with a stirrer, a nitrogen inlet tube, and a thermometer, 140 g of the aqueous polymer component (A), 14 g of a polyoxyethylene nonylphenyl ether emulsifier, and 1500 g of distilled water
And the atmosphere is replaced with nitrogen. While heating the reaction vessel to increase the temperature, 5% of the total amount of the monomer emulsion (B) was added dropwise at 60 ° C., and an aqueous solution of ammonium persulfate (APS) (3.5 g APS / 420 g distilled at 65 ° C.) 84.7g of water)
(20%), and the internal temperature of the reaction vessel is raised to 75 ° C. to carry out an initial reaction. It was visually confirmed that the initial polymerization reaction was completed, and after 20 minutes, the remaining amount (95%) of the monomer emulsion (B) was added for 1 hour and 30 minutes to 338.8 g (80%) of the aqueous ammonium persulfate solution. %) Over 5 hours and 20 minutes to carry out polymerization. In the above polymerization reaction, a first resin to be an inner layer is formed.

One hour after the completion of the dropping of the first-stage monomer emulsion (B), the entire amount of the monomer emulsion (C) is dropped over 2 hours. After the completion of the dropwise addition, the completion reaction is carried out for 1 hour while maintaining the liquid temperature at 75 ° C. Thus, the second resin constituting the outer layer is formed. Then the liquid temperature is 40 ℃
The solution is cooled until the temperature becomes below, and the pH of the solution is adjusted to 7 by adding 25% aqueous ammonia. The results of measurement of the solid content concentration, viscosity and pH of the obtained acrylic water-dispersed copolymer resin are shown in the lower part of the dispersion in Tables 2 and 3.

Comparative Example Table 4 shows the composition of the monomer emulsion used as a comparative example. The preparation of the resin aqueous dispersion was performed in the same manner as in the above-described example. Comparative Examples 1 and 2 did not use the aqueous copolymer component (A), and produced a resin aqueous dispersion by only the first-stage reaction. In Comparative Example 3, A5 was used as the aqueous copolymer component (A), and a resin aqueous dispersion was produced only by the first-stage reaction. It is considered that the resin aqueous dispersion produced by only the first-stage reaction is not naturally a resin having a so-called core-shell structure.

[0056]

[Table 4]

(5) Preparation of Ceramic Green Sheet Barium titanate BT-50 which is a ceramic powder
91.4 distilled water in 100 parts by weight (manufactured by Sakai Chemical Industry Co., Ltd.)
Parts by weight of the acrylic water-dispersed copolymer resin 2
8.6 parts by weight (ceramics / resin = 100/10, solid content in the slurry was 50% by weight) was added and uniformly mixed by a dispersing apparatus. When the dispersibility was poor, a dispersant was further added and the dispersion was continued. The resulting slurry is degassed under vacuum, cast on a substrate (such as polypropylene, PET, etc.) to a size of 2 × 7 (dm), and dried in an equilibrated 50 ° C. oven for 20 hours. A green sheet having a thickness of 0.2 mm was prepared.

(6) Evaluation Evaluation of Dispersibility The dispersibility of the slurry in the above-described green sheet preparation step was visually evaluated. A sample having good dispersibility and uniform slurry was indicated by ○, and a sample having insufficient dispersibility and nonuniformity was indicated by ×. Evaluation of Sheet State The surface state of the ceramic green sheet was visually observed, and those having a uniform and smooth surface were indicated by "O", and those having a non-smooth surface were indicated by "X". Evaluation of Green Sheet Peelability Using a 2 × 7 (dm) green sheet, a 90 ° peel strength was measured by a tensile tester. The measurement conditions were a temperature of 20 ° C. and a crosshead speed of 50 mm / min. The distance between the chucks was 20 mm. Measurement of strength and elongation of green sheet 1 prepared from the above 2 × 7 (dm) green sheet
Using a sample of × 7 (dm), the strength and elongation of the green sheet were measured by a tensile tester. Measurement conditions are temperature 20
° C, the crosshead speed is 5 mm / min. The distance between the chucks was 20 mm.

(7) Results The results of the above evaluations are shown in Table 5.

[0060]

[Table 5]

As described above, the slurry using the acrylic water-dispersed copolymer resin of the present invention has good dispersibility, the obtained green sheet has good releasability, and the green sheet strength and elongation are low. It is clear that both are excellent.

Claims (4)

[Claims] (1) In the presence of an aqueous polymer (a), (b) 5 to 40 parts by weight of (meth) acrylonitrile (c) 5 to 95 parts by weight of (meth) acrylate (d) unsaturated carboxylic acid 0 .01-20
A ceramic molding binder containing an acrylic water-dispersed copolymer resin obtained by emulsion polymerization or suspension polymerization of a radical polymerizable monomer containing a weight part. 2. The ceramic molding binder according to claim 1, wherein the aqueous polymer (a) has a crosslinkable functional group. 3. The acrylic water-dispersed copolymer resin is a particle having a hetero-layer structure, and a first resin forming an inner layer of the particle has a glass transition temperature of −50 to 20 ° C.,
3. The ceramic molding binder according to claim 1, wherein the second resin formed as an outer layer of the first resin has a glass transition temperature of 0 to 50 ° C. 4. 4. A method for producing a binder for ceramics molding containing an acrylic water-dispersed copolymer resin comprising particles having a different layer structure, wherein a radical polymerization initiator is used in the presence of an aqueous polymer (a). Then, (b) a monomer containing (meth) acrylonitrile and (c) a monomer containing (meth) acrylate as a main component is polymerized to form a first resin constituting an inner layer, and then (c) (meth) A) A method for producing a ceramic molding binder in which a second resin constituting an outer layer is formed by polymerizing a monomer containing an acrylate ester as a main component.