JP2000302526A - Binder for ceramics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flexible binder having excellent melt-fixing property for green sheets by incorporating a water-soluble or water-dispersible modified polyvinylalcohol as a main component which is prepared by saponifying a specified amt. of aliphatic vinylester copolymers produced by copolymn. of the specified amt. of alkylvinylethers having oxyalkylene groups. SOLUTION: This binder essentially consists of a water-soluble or water- dispersible modified polyvinylalcohol having >=30 mol% saponification degree which is obtd. by saponifying copolymers of aliphatic vinylesters produced by copolymn. of >=0.1 mol%, preferably 1 to 30 mol% of alkylvinylethers having oxyalkylene groups. As for the alkylvinylethers containing oxyalkylene groups, for example, alkylvinylethers having 1 to 40 units of ethylene oxide in the side chains are used. To produce a green sheet, this binder is preferably incorporated by 3 to 20 wt.% into the slurry of the ceramic source material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a binder for ceramics.

[0002]

2. Description of the Related Art Conventionally, precision parts of electronic materials such as ceramic circuit boards have been manufactured through the following steps. That is, a ceramic powder such as alumina, zirconia, aluminum silicate, titanium oxide, zinc oxide or barium titanate is added to a solution containing a binder resin and a plasticizer, mixed, defoamed, and a slurry of ceramic raw material is formed. Prepare. This slurry is applied on a suitable support such as a polyester film, and heated and heated.
After drying, the support is peeled off to obtain a green sheet. Next, the green sheet is punched into an appropriate shape, a circuit, a character, and the like are printed on the surface as necessary, and a plurality of the sheets are laminated and pressed to obtain a laminate. Thereafter, the laminate is fired, and the binder resin is decomposed at the time of firing to produce a desired ceramic circuit board.

As a binder resin contained in the slurry of the ceramic raw material, a butyral resin such as a polyvinyl butyral resin and a cellulosic resin such as ethyl cellulose have been conventionally used. Therefore, as a solvent for dissolving the binder resin, an organic solvent that can dissolve a butyral-based resin or a cellulose-based resin is used. However, in recent years, from the viewpoint of environmental pollution and toxicity, a binder resin that can use water as a solvent has been required for the binder resin.

[0004] Since polyvinyl alcohol (hereinafter abbreviated as PVA) is water-soluble, water can be used as a solvent by using PVA as a binder resin contained in the slurry of the above ceramic raw material. In the case of producing a small number of ceramic circuit substrates for general use, when a ceramic raw material slurry is contained as a binder resin, it can be normally used without any problem.

[0005] However, in recent years, as the degree of integration of ceramic circuit substrates has increased, a hybrid circuit substrate formed by laminating a large number of green sheets has been required. In the production of this hybrid circuit board, several to several tens of green sheets are laminated and integrated by heat fusion to obtain a laminate,
The obtained laminate is fired to produce a hybrid circuit substrate. The slurry of the ceramic raw material for producing such a hybrid type circuit substrate is made of PV.
When A is contained as a binder resin, thermal fusion between the green sheets is not sufficient, so that delamination or the like is likely to occur in the obtained hybrid circuit substrate,
It was not possible to obtain a hybrid-type circuit board with sufficient performance.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a hybrid type circuit board having a water-soluble or water-dispersible property and having a large number of green sheets laminated thereon. In addition, the green sheets are sufficiently heat-sealed to each other, and the resulting hybrid circuit substrate does not undergo delamination or the like, and a highly flexible PVA-based substrate capable of obtaining a hybrid circuit substrate having sufficient performance. An object of the present invention is to provide a ceramic binder.

[0007]

The ceramic binder of the present invention is obtained by saponifying an aliphatic vinyl ester copolymer obtained by copolymerizing at least 0.1 mol% of an alkyl vinyl ether containing an oxyalkylene group. And a water-soluble or water-dispersible modified PVA having a saponification degree of 30 mol% or more as a main component.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below. Water-soluble or water-dispersible modified P used in the present invention
VA is obtained by saponifying an aliphatic vinyl ester copolymer in which 0.1 mol% or more of an alkyl vinyl ether containing an oxyalkylene group is copolymerized. These production methods can be performed by a known method.

The alkyl vinyl ethers containing an oxyalkylene group include alkyl vinyl ethers containing 1 to 40 ethylene oxide units in the side chain, and alkyl vinyl ethers containing 1 to 30 propylene oxide units in the side chain. Is mentioned.

As the aliphatic vinyl ester copolymerized with the above-mentioned alkyl vinyl ether, various ones are used. For example, known vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate and vinyl stearate are used. Aliphatic vinyl esters can be mentioned. P
For the purpose of producing an aliphatic polyvinyl ester as a raw material for VA, vinyl acetate is particularly industrially preferable.

The above-mentioned aliphatic vinyl ester may be obtained by copolymerization with an unsaturated monomer copolymerizable with the aliphatic vinyl ester as long as the effects of the present invention are not impaired. Examples of the unsaturated monomer copolymerizable with the aliphatic vinyl ester include, for example, acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, unsaturated acids such as maleic anhydride, salts or mono- or dialkyl esters, Examples include (meth) acrylonitriles, (meth) acrylamides, vinyl ethers, olefins, vinyl chloride, vinylidene chloride, vinyl sulfonic acid and salts thereof, but are not limited thereto.

In the copolymerization of the above-mentioned alkyl vinyl ether having an oxyalkylene group with the above-mentioned aliphatic vinyl ester, a lower alcohol such as methanol is used as a solvent in the presence of a polymerization catalyst to form an alkyl vinyl ether having an oxyalkylene group. Obtained by copolymerizing with vinyl ester.

The ratio of the alkyl vinyl ether having an oxyalkylene group in the obtained copolymer (degree of modification)
Is in the range of 0.1 mol% or more, preferably 1 to 30 mol%. When the degree of modification is less than 0.1 mol%, the flexibility of the obtained green sheet is inferior, and the heat-sealing property also deteriorates. On the other hand, when the modification degree exceeds 30 mol%, the modified PVA
Depending on the degree of polymerization, the strength of the obtained green sheet is significantly reduced. The degree of polymerization of the copolymer is not particularly limited, but is preferably 200 or more.

Next, saponification of the copolymer can be carried out by adding an acid or alkali to an alcohol solution of the copolymer and saponifying it. Examples of the alcohol used here include methanol, ethanol and the like.
Methanol is preferably used. As the saponification catalyst, an alkali catalyst such as sodium hydroxide or sodium methylate, or an acid catalyst such as sulfuric acid or hydrochloric acid is used. The degree of saponification of the copolymer is desirably 30 mol% or more, preferably 65 mol% or more, and more preferably 90 mol% or more. When the saponification degree of the copolymer is less than 30 mol%, the water solubility or water dispersibility is impaired, and the strength of the green sheet is reduced.

The modified PVA of the present invention is obtained by drying the saponified product of the copolymer obtained as described above by heating or the like according to a conventional method and pulverizing it if necessary.

The binder for ceramics of the present invention is obtained by saponifying a copolymer of at least 0.1 mol% of an alkyl vinyl ether containing an oxyalkylene group and an aliphatic vinyl ester, and has a degree of saponification. 30 mol%
The composition is obtained by using the above-described composition containing water-soluble or dispersible modified PVA as a main component as a green sheet-forming substance.

A method for producing a green sheet using the ceramic binder of the present invention can be carried out by a known method. The amount of the ceramic binder of the present invention (expressed by the weight of the modified PVA) contained in the slurry of the ceramic raw material is preferably in the range of 3 to 20% by weight. 2 ceramic binders
If the amount is more than 0% by weight, the viscosity of the slurry of the ceramic raw material becomes too high, the dispersibility decreases, and the shrinkage of the green sheet increases when the obtained green sheet is fired. When the binder for ceramics is less than 3% by weight, it is insufficient to disperse the binder resin throughout the ceramic raw material powder, so that the obtained green sheet has insufficient flexibility and cracks and the like after firing. Prone to occur.

Further, in producing a green sheet,
If necessary, a known plasticizer such as a polyhydric alcohol such as glycerin, diglycerin, polyethylene glycol, or sorbitol can be added to impart flexibility to the sheet.

[0019]

Next, the present invention will be described more specifically with reference to examples. In the examples, “part” and “%” are
Unless otherwise specified, "parts by weight" and "% by weight" are indicated.

Example 1 A flask equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser was charged with 1000 parts of vinyl acetate, 380 parts of an alkyl vinyl ether containing about 10 units of ethylene oxide units and 300 parts of methanol. After the system was replaced with nitrogen, the internal temperature was raised to 60 ° C.
To this system, 1 part of 2,2-azobisisobutyronitrile was added to initiate polymerization. The polymerization was stopped 5 hours after the start of the polymerization. When the polymerization was stopped, the solid content in the system was 53%, and the polymerization yield with respect to all monomers was 65%. After removing unreacted monomers under reduced pressure, 45
% Methanol solution was obtained. The copolymer is vinyl acetate unit 9
The amount of unreacted monomer was confirmed to be 4 mol% and to contain 6 mol% of alkyl vinyl ether units containing ethylene oxide.

While stirring 100 parts of a methanol solution of the copolymer at 40 ° C., 15 parts of a 3% methanol solution of NaOH was added, mixed well, and allowed to stand. After 30 minutes, the solidified polymer was pulverized with a pulverizer, washed with methanol, and dried to obtain a polymer powder (hereinafter, this is referred to as a saponified copolymer (A)). The saponification degree of the copolymer saponified product (A) is 88.3 mol%, and the degree of polymerization is 1100.
Met.

10% aqueous solution of saponified copolymer (A) 6
0 parts were mixed with 120 parts of water, and 4 parts of polyethylene glycol and 200 parts of alumina powder were added as plasticizers and mixed by a ball mill for about 15 hours to obtain a slurry of ceramic raw material. After defoaming the obtained slurry of the ceramic raw material under stirring, the slurry is applied to a release-treated polyester film to a thickness of about 50 μm, and
Air dried for days. Next, it was dried in a dryer at 110 ° C. for about 3 hours to obtain a green sheet having a thickness of 25 μm.

This green sheet was evaluated in the following manner. 1 Flexibility The flexibility of a green sheet conditioned at 20 ° C. and 65% RH for 24 hours was evaluated. The evaluation of flexibility is determined by the size of the diameter when the green sheet is wound,
The evaluation was performed based on the following criteria. ◎: No cracks even when the diameter is 2 cm or less. Even when the thickness was set to 10 cm or more, the results of cracking were excellent as shown in Table 2.

2. A 50 mm square test piece was cut out from the green sheet, and ten test pieces were laminated.
A pressure of kg / cm ² was applied in the laminating direction to perform press molding for 10 minutes. Thereafter, the press-formed laminate was cracked by hand, and the state of the lamination line generated in the longitudinal section was visually observed. The evaluation was performed based on the following criteria. ◎: A state in which the lamination line is not recognized at all. ○: A state in which the lamination line is hardly recognized. Δ: A state in which the lamination line is partially recognized. X: A state in which the lamination line is clearly recognized. It was excellent.

Examples 2 to 5 A copolymer obtained by copolymerizing vinyl acetate and an alkyl vinyl ether containing an oxyalkylene group was saponified in the same manner as in Example 1 except as described in Table 1. Saponified copolymers (B), (C), (D) and (E) were obtained.

[0026]

[Table 1]

A green sheet having a thickness of 25 μm was obtained in the same manner as in Example 1 except that the saponified copolymer and the ceramic raw material powder were changed as shown in Table 2. Evaluation of the obtained green sheet was performed in the same manner as in Example 1. As shown in Table 2, the results were excellent.

Examples 6 and 7 A green sheet having a thickness of 25 μm was obtained in the same manner as in Examples 3 and 5, except that 10% by weight of glycerin was added to the saponified copolymer. Evaluation of the obtained green sheet was performed in the same manner as in Example 1. As shown in Table 2, the results were excellent.

Comparative Examples 1 and 2 A saponified copolymer and a ceramic raw material powder were changed as shown in Table 2 in the same manner as in Example 1 except that the thickness was 2
A 5 μm green sheet was obtained. Evaluation of the obtained green sheet was performed in the same manner as in Example 1. As shown in Table 2, as shown in Table 2, in the case of Comparative Example 1, the green sheet was excellent in flexibility, but inferior in heat fusibility. Also, in the case of Comparative Example 2, although the flexibility of the green sheet was excellent, the strength of the green sheet was weak and a laminate could not be obtained.

Comparative Example 3 A partially saponified PVA having a degree of polymerization of 500 and a saponification degree of 88 mol% was used as a binder resin, and the thickness was changed in the same manner as in Example 1 except that the ceramic powder was changed as shown in Table 2. A 25 μm green sheet was obtained. Evaluation of the obtained green sheet was performed in the same manner as in Example 1. As shown in Table 2, the results were all inferior.

[0031]

[Table 2]

[0032]

As is clear from the above description, when manufacturing a hybrid type circuit board or the like having a water-soluble or water-dispersible property and laminating a large number of green sheets, the green sheets can be connected to each other. It is possible to provide a ceramic binder having excellent flexibility which can be sufficiently heat-fused, does not cause delamination or the like in the obtained hybrid circuit substrate, and can obtain a hybrid circuit substrate having sufficient performance. it can.

Claims (1)

[Claims] 1. A water solution wherein 0.1 mol% or more of an alkyl vinyl ether containing an oxyalkylene group is obtained by saponifying a copolymer of a copolymerized aliphatic vinyl ester and which has a saponification degree of 30 mol% or more. A binder for ceramics, comprising a modified or water-dispersible modified polyvinyl alcohol as a main component.