JP2002080675A - Acrylic binder resin composition for baking-type paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic binder resin composition for a baking-type paste which can impart high viscosity to the paste by the use of a small amount and exhibits excellent properties in baking. SOLUTION: This binder resin composition is a solution comprising (A) 100 pts.mass thermoplastic acrylic polymer having a wt. average mol.wt. of 1,000,000-6,000,000 and (B) 400-1,900 pts.mass organic solvent containing at least 50 mass% aromatic alcohol having a boiling point of 200 deg.C or higher and has a Brookfield viscosity (at 25 deg.C) of 10,000 mPa.s or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to Ag, Cu, N
A resin composition suitably used as a binder, which is a component of a paste used for shaping and sintering various fillers including conductor powders such as i and Pd on a substrate such as a ceramic substrate or a capacitor. More particularly, the present invention relates to a binder resin composition for a baked paste which can impart high viscosity to a paste with a small amount and has excellent sinterability.

[0002]

2. Description of the Related Art Hitherto, a pattern or a molded body has been produced using a paste in which a filler made of a metal, an inorganic substance, or the like is dispersed in a binder. A method for producing a molded body is known. The binder, which is a component of this paste, is necessary to hold the shape of the produced pattern or molded body by fixing the filler, and is to be thermally decomposed when the filler is sintered. .

[0003] Therefore, it is necessary for the binder to be excellent in firing properties (having good thermal decomposability and leaving no residue). In addition, the binder has a high viscosity in the paste in order to correspond to various processing methods (dip method, method of forming into a sheet shape by a doctor plate, screen printing method, etc.) used in producing a pattern or a molded body. Must be able to be provided.

[0004] In particular, when the paste is used by dipping or screen printing, it is necessary to minimize the amount of binder in the paste in order to further increase the filling rate of the filler component to be sintered. Therefore, in order to impart high viscosity to the paste with a small amount of binder, a solvent-based binder in which butyral resin, ethyl cellulose, or the like is dissolved in an organic solvent has been used.

However, recent electronic materials use high-temperature firing type fillers such as alumina and low-temperature firing type fillers such as glass powder, particularly when sintering low-temperature firing type fillers. In the case of sintering in an inert gas atmosphere (reducing atmosphere) to prevent oxidation of the metal filler, if the above-mentioned butyral resin or ethyl cellulose resin binder is used, sludge is generated due to poor firing, and the resulting metal conductor And the properties of ceramics are degraded.

[0006] In order to solve the drawbacks of the conventional binder, an acrylic resin binder using an acrylic resin having good firing properties has been proposed. For example, JP-A-10-1
No. 67,836 discloses that isobutyl methacrylate and 2
-Ethylhexyl methacrylate, and β-position or α
The use of a copolymer with a methacrylate having a hydroxyl group at the position is described.

[0007]

However, Japanese Patent Application Laid-Open No.
The acrylic resin binder described in Japanese Patent No. 167836 has higher thermal decomposability than butyral resin and ethyl cellulose resin when compared with the same resin amount, but imparts the paste with high viscosity required for dip coating and screen printing. To do so, it was necessary to increase the amount of the binder. As a result, the density of the obtained sintered body was reduced, and sufficient characteristics as a metal conductor or ceramic could not be obtained.

[0008] An object of the present invention is to provide an acrylic binder resin composition for a fired paste which can impart high viscosity to the paste in a small amount and has excellent firing properties.

[0009]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that an acrylic polymer having a specific weight average molecular weight and an organic solvent mainly containing an alcohol containing an aromatic hydrocarbon are used. It has been found that the above problem can be solved by using the present invention, and the present invention has been completed.

That is, according to the present invention, the weight average molecular weight is 1.0
An organic solvent (B) containing 50% by mass or more of an aromatic hydrocarbon-containing alcohol having a boiling point of 200 ° C. or more with respect to 100 parts by mass of a thermoplastic acrylic polymer (A) having a range of 00,000 to 6,000,000. The present invention relates to an acrylic binder resin composition for a baked paste, comprising a melt in which 400 to 1,900 parts by mass are blended, and having a B-type viscosity of 10,000 mPa · s or more at a temperature of 25 ° C.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The acrylic binder resin composition for a baked paste according to the present invention must have a B-type viscosity at a temperature of 25 ° C. of 10,000 mPa · s or more.
This is because the B-type viscosity at a temperature of 25 ° C. is 10,000 m
If the viscosity is less than Pa · s, the viscosity of the obtained baked paste tends to be insufficient, and the workability of the paste tends to be impaired. The lower limit of the B-type viscosity at a temperature of 25 ° C. is preferably 20,000 mPa · s or more, and the upper limit is preferably 50,000 mPa · s or less.

The thermoplastic acrylic polymer (A) used in the present invention has a weight average molecular weight of 1,000,000 to 6,000.
Must be in the range of 1,000,000. If the weight average molecular weight is less than 1,000,000, the viscosity of the resulting baked paste tends to be insufficient, and the workability and workability during dip coating and the like tend to be impaired. This is because, if the amount exceeds 3,000,000, it tends to be difficult to dissolve the polymer in an organic solvent. The weight average molecular weight is preferably 2,000,000 or more as a lower limit, and 5,000,000 as an upper limit.
It is preferable to set the following.

[0013] The thermoplastic acrylic polymer (A) used in the present invention is at least one (a-1) 80 selected from alkyl (meth) acrylate monomers having 1 to 4 carbon atoms.
A monomer mixture containing 0 to 10% by mass of a (meth) acrylate monomer (a-2) containing a hydroxyl group and 0 to 10% by mass of another copolymerizable monomer (a-3) (However, the total of the monomers is 100% by mass) is preferably obtained by copolymerization.

The thermoplastic acrylic obtained by containing at least one kind (a-1) selected from alkyl (meth) acrylate monomers having 1 to 4 carbon atoms as a constituent component of the monomer mixture is 80% by mass or more. It can impart excellent sinterability to a sinterable paste using a system polymer. It is more preferably at least 90% by mass.

As the component (a-1), for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-
Mono (meth) acrylates such as butyl (meth) acrylate and i-butyl (meth) acrylate can be mentioned. These can be used alone or two or more of them can be appropriately selected as needed.

When the (meth) acrylate monomer (a-2) containing a hydroxyl group is contained in an amount of 10% by mass or less as a constituent component of the monomer mixture, a sinterable paste using the obtained thermoplastic acrylic polymer is prepared. Viscosity and dispersion stability of metal pigments and the like can be improved, and excellent thermal decomposition properties can be imparted to the baked paste. The lower limit of the content of the component (a-2) is 0.1.
% By mass or more, and preferably 5% by weight or less as the upper limit.

As the component (a-2), for example, hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxypropyl (meth) acrylate, 1,2-dihydroxyethyl (meth) acrylate, 1,2- Dihydroxypropyl (meth) acrylate, 1,2-dihydroxybutyl (meth) acrylate, 1,2-dihydroxy-5-ethylhexyl (meth)
Acrylate, 1,2,3-trihydroxypropyl (meth) acrylate, 1,2,3-trihydroxybutyl (meth) acrylate, 1,1-dihydroxyethyl (meth) acrylate, 1,1-dihydroxypropyl (meth) Acrylate, 1,1-dihydroxybutyl (meth) acrylate, 1,1,2-trihydroxypropyl (meth) acrylate, 1,1,2-trihydroxybutyl (meth) acrylate, and the like can be given. These can be used alone or two or more of them can be appropriately selected as needed.
(Meth) acrylates containing one or more hydroxyl groups in the alkyl group of No. 8 tend to be able to improve the dispersibility with fillers composed of metals, inorganic substances, and the like, and are therefore preferable.

The other copolymerizable monomer (a-3) may be used alone or in an amount of at least 10% by weight as a component of the monomer mixture, as long as it does not significantly reduce the baking property. Can be selected and used.

As the component (a-3), for example, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, alkyl (meth) acrylate having 5 or more carbon atoms, styrene, α-methylstyrene, acrylonitrile, acrylamide , Methacrylamide, diethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth)
Acrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, trimethylolpropane tri (meth) acrylate, polybutylene glycol dimethacrylate,
1,6-hexanediol dimethacrylate, 1,3-
Examples thereof include butylene glycol dimethacrylate, triethylene glycol dimethacrylate, ethylene glycol dimethacrylate, and vinyl acetate.

[0020] The thermoplastic acrylic polymer (A) used in the present invention can be produced by a method such as solution polymerization, suspension polymerization, and emulsion polymerization.

The organic solvent (B) used in the present invention has a boiling point of 2
It is necessary that an aromatic hydrocarbon-containing alcohol having a temperature of 00 ° C. or more is contained in an amount of 50% by mass or more. It has a boiling point of 200
The content of the aromatic hydrocarbon-containing alcohol of 50 ° C. or more is 50
When the amount is less than mass%, the solubility of the thermoplastic acrylic polymer (A) is reduced, and the solvent and the polymer may phase-separate in the solution, or a polymer insoluble may be generated. It is preferably at least 60% by mass.

As the aromatic hydrocarbon-containing alcohol having a boiling point of 200 ° C. or higher, for example, benzyl alcohol (boiling point of 20
6 ° C.), phenylpropylene glycol (boiling point 243)
C) and cresol (boiling point: 202 ° C.). Among them, benzyl alcohol is particularly preferable because it tends to have a high effect of giving a high viscosity to a melt with the thermoplastic acrylic polymer (A).

As the organic solvent other than the aromatic hydrocarbon-containing alcohol having a boiling point of 200 ° C. or higher, one or more organic solvents can be appropriately selected and used within a range of less than 50% by mass of the organic solvent (B). Although not particularly limited, among them, an organic solvent having a boiling point of 150 ° C. or higher is preferred in terms of workability (slowing the drying of the solvent and preventing a change in the viscosity of the paste).

Examples of the organic solvent having a boiling point of 150 ° C. or higher include terpineol, dihydroterpineol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, butyl carbitol acetate, and diethylene glycol. Monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, 2,2,4-trimethyl 1,3-pentadiol monoisobutyrate, isophorone, 3-methoxybutyl acetate, aromatic or aliphatic having a boiling point of 150 ° C or higher Phthalic acid esters such as hydrocarbons, butyl lactate, dibutyl phthalate, dioctyl phthalate or dibutyl adipate And a plasticizer such as an adipate such as dioctyl adipate.

The content of the organic solvent (B) in the acrylic binder resin composition for a baked paste of the present invention is 400 to 1900 with respect to 100 parts by mass of the acrylic polymer.
It must be in parts by weight. If the amount of the organic solvent (B) is less than 400 parts by mass, the thermoplastic acrylic polymer (A) is not uniformly dissolved in the organic solvent (B), and an insoluble matter is generated. When screen printing is performed, it is difficult to obtain a uniform coating film, and when it exceeds 1900 parts by mass, the B at a temperature of 25 ° C. of the acrylic binder resin composition for a firing paste is used.
This is because it is difficult to make the mold viscosity 10,000 mPa · s or more, the viscosity of the obtained baked mold paste is insufficient, and the workability of the paste tends to be impaired. The content of the organic solvent (B) is preferably at least 700 parts by mass as a lower limit, and is preferably at most 1400 parts by mass as an upper limit.

The acrylic binder resin composition for a baked paste according to the present invention is characterized in that there is little thermal decomposition residue such as sludge even in an air atmosphere and / or an inert gas atmosphere. 450 at heating rate
It is possible to reduce the thermal decomposition residue under baking conditions by heating to a temperature of up to 0.5% by mass or less.

The conventionally used ethylcellulose resin or butyral resin has a problem that a large amount of residue called sludge is generated at a low temperature of 450 ° C. or less, and further sludge is generated when the material is fired in an inert atmosphere. Therefore, there was a disadvantage that it could not be used for parts requiring high-purity quality for electronic materials and the like, but the acrylic binder resin composition of the present invention did not have such disadvantages, and was used for electronic materials and the like. It can be used for parts requiring high purity quality. Further, it can be suitably used for a metal filler which undergoes an oxidation reaction due to heat, a metal oxide which is liable to undergo thermal degradation, a phosphor and the like.

The inert atmosphere generally means a nitrogen atmosphere, but here, an atmosphere of a mixed gas of oxygen and nitrogen may be used, and an inert atmosphere such as helium, neon, or argon may be used. The atmosphere may be an active gas atmosphere.

[0029] The filler used together with the acrylic binder resin composition for a baked paste of the present invention is not particularly limited, but examples thereof include oxides such as alumina, zirconia, titanium oxide and barium titanate. Compounds, nitride compounds such as alumina nitride, silicon nitride, and boron nitride; metals such as copper, silver, and nickel; silica powders such as low-melting glass powder; and various phosphors used for cathode rays and PDPs. be able to.

The mixing ratio of the filler, which is a constituent component of the firing type paste, to the acrylic binder resin composition of the present invention is such that the solid content of the binder resin composition is 3 to 30 parts by mass with respect to 100 parts by mass of the filler. However, since the optimum mixing ratio varies depending on the specific gravity of the filler, it is not limited to this range. If necessary, a plasticizer, a dispersing aid, an antifoaming agent and the like may be added to the baked paste.

[0031] Examples of the method of applying the firing type paste include dip coating or screen printing for high viscosity applications, and doctor blade method or casting method for low viscosity applications.

Hereinafter, the present invention will be described more specifically with reference to examples.

[0033]

In the examples, "parts" means "parts by mass",
“%” Indicates “% by mass”. The evaluation method in the examples is as follows.

<Firing property> The binder resin was dried at 105 ° C under drying conditions for about 2 hours, and a sample amount of 10 to 20 mg was placed on an aluminum dish and evaluated by TG (thermal loss analysis). The atmosphere was heated from room temperature to 45 ° C.
After the temperature was raised to 0 ° C., it was cooled to room temperature, and the state of the residue was observed. Heat loss rate (mass%) = (sampling mass (mg) -residue mass (mg)) / sampling mass (mg) A: There was no black or gray residue in the aluminum dish, and it was completely decomposed. Heat loss rate of 99.9% by mass or more ：: There was no black or gray residue in the aluminum dish, and it was completely decomposed. Heat loss rate of 99.5% by mass or more and less than 99.9% by mass Δ: A black or gray residue was present on the aluminum dish, and poor decomposition products were observed. Heat loss rate of 97% by mass or more to less than 99.5% by mass ×: Black or gray residue was present on the aluminum dish, and poor decomposition products were observed. Heat loss rate less than 97% by mass

<Solubility in Organic Solvent> The acrylic polymer was put into an organic solvent placed in a two-liter three-necked flask equipped with a stirrer and a condenser, and heated to 100 ° C.
After stirring for 3 hours at 100 ° C for 3 hours,
After 0 to 20 g was placed on a glass plate and spread over about 5 cm ² , the solubility of the acrylic binder resin was visually evaluated. ：: The sample placed on the glass plate was uniformly dissolved in the organic solvent, and no insoluble matter was observed. . Δ: Insoluble matter was partially observed in the sample placed on the glass plate. ×: Many insolubles were observed in the sample placed on the glass plate.

<Resin Composition B Type Viscosity> An acrylic polymer was put into an organic solvent placed in a two-liter three-necked flask equipped with a stirrer and a condenser, heated to 100 ° C., and stirred for 3 hours. After holding at 3 ° C. for 3 hours, a sample amount of about 180 g was placed in a glass sample bottle (capacity: 200 ml).
And then immersed in a constant temperature water bath at 25 ° C. for 2 hours or more, and the B-type viscosity was measured.

<Weight average molecular weight> The weight average molecular weight was measured using GPC (gel permeation chromatography).

Example 1 A 2-liter separable flask equipped with a stirrer and a condenser was charged with 750 parts of pure water and polyvinyl alcohol (degree of saponification 80%, degree of polymerization 1700).
2.0 parts were dissolved, and 2.5 parts of sodium sulfate were added, and a monomer mixture of 200 parts of methyl methacrylate, 300 parts of isobutyl methacrylate, and 0.5 part of benzoyl peroxide was added, and the mixture was vigorously stirred at 500 rpm. Into a suspension, raise the temperature to 80 ° C., hold at 80 ° C. for 4 hours,
The polymerization was terminated. The obtained suspension is dehydrated and dried (40
C. for 24 hours) to obtain a beaded polymer (A1).

100 parts of the obtained polymer (A1) was put into 900 parts of benzyl alcohol in a two-liter three-necked flask equipped with a stirrer and a condenser.
Temperature, stirred for 3 hours, kept at 100 ° C. for 3 hours,
Acrylic binder resin composition for firing paste (C
1) was manufactured.

[Examples 2 to 8] By the same method as in Example 1,
Acrylic binder resin compositions for fired pastes (C2 to C8) shown in Tables 1 and 2 were produced.

Tables 1 and 2 show the evaluation results of the obtained binder resins of the respective examples.

[0042]

[Table 1]

The symbols in the table are as follows. iBMA: isobutyl methacrylate nBMA: normal butyl methacrylate MMA: methyl methacrylate

[0044]

[Table 2]

The symbols in the table are as follows. iBMA: isobutyl methacrylate nBMA: normal butyl methacrylate MMA: methyl methacrylate

[Comparative Examples 1-4] In the same manner as in Example 1,
Acrylic binder resin compositions (C9 to C12) for firing pastes shown in Tables 1 and 2 were produced. Example 1
In the same manner as in the above, various acrylic binder resin compositions shown in Table 3 were obtained. Table 3 shows the evaluation results of the obtained binder resins of Comparative Examples.

[0047]

[Table 3]

The symbols in the table are as follows. iBMA: isobutyl methacrylate nBMA: normal butyl methacrylate MMA: methyl methacrylate

[0049]

As is apparent from the above description, the present invention provides an acrylic binder resin composition for a baked paste which can impart high viscosity to the paste in a small amount and has excellent sinterability. Yes, it is very useful industrially.

Claims (4)

[Claims] (1) a weight average molecular weight of 1,000,000 or more;
Organic solvent (B) 400 to 1 containing 50% by mass or more of an aromatic hydrocarbon-containing alcohol having a boiling point of 200 ° C or more based on 100 parts by mass of a thermoplastic acrylic polymer (A) having a range of 6,000,000. , 900 parts by weight of a blended material, having a B-type viscosity of 1 at a temperature of 25 ° C.
An acrylic binder resin composition for a firing type paste having a viscosity of not less than 000 mPa · s. 2. The thermoplastic acrylic polymer (A) contains 80 to 100% by mass of at least one (a-1) selected from alkyl (meth) acrylate monomers having 1 to 4 carbon atoms and contains a hydroxyl group ( (Meth) acrylate monomer (a
-2) 0 to 10% by mass, and other copolymerizable monomers (a
-3) The acrylic binder resin composition for a firing type paste according to claim 1, wherein the acrylic binder resin composition is a copolymer of a monomer mixture containing 0 to 10% by mass (the total of all monomers is 100% by mass). 3. A boiling point of 200 ° C. contained in the organic solvent (B).
The acrylic binder resin composition for a fired paste according to claim 1 or 2, wherein the aromatic hydrocarbon-containing alcohol is benzyl alcohol. 4. A pyrolysis residue under baking conditions of heating to 450 ° C. at a rate of 10 ° C./min in an atmosphere in the atmosphere and / or an inert gas atmosphere, wherein 0.5 mass%
The acrylic binder resin composition for a fired paste according to any one of claims 1 to 3, which is: