JPS6259072B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a binder used in forming ceramics by firing inorganic powders such as alumina.

Ceramics obtained by firing inorganic powders such as alumina are used as substrates for integrated circuits and the like. Conventionally, such ceramics have been manufactured as follows. First, alumina is dispersed in a solution containing a binder and a plasticizer to form a slurry, and the slurry is applied in a layer onto a polyester sheet using a doctor blade or the like and dried. The sheet thus obtained is called a raw sheet or green sheet. This sheet is rolled up and stored, taken out as needed and punched out with a die, and the punched pieces are fired to decompose the binder and sinter the alumina to produce ceramic.

In the above method, a cellulose resin such as ethyl cellulose or a butyral resin such as polyvinyl butyral was used as the binder. However, when these resins are used as binders, there is a drawback that residues tend to remain during firing. This requires firing at high temperatures for a long time, resulting in high costs. In addition, these resins have the disadvantage that alumina easily becomes secondary particles due to poor dispersibility, resulting in large gaps between particles and the formation of pores in the product. Furthermore, if these resins are used alone, the sheet will not be flexible and will break easily when rolled into a roll or punched with a mold, so a plasticizer must be added, but adding a plasticizer will cause large shrinkage during firing and the size will be reduced. The drawback was poor stability.

The inventors searched for binder resins that do not have the above drawbacks. As a result of repeated experiments, it was confirmed that the methacrylic acid ester polymer completely decomposes at a relatively low temperature without leaving any residue upon firing. However, among methacrylic acid esters, common ester homopolymers such as methacrylic acid alkyl esters have insufficient dispersibility, lack flexibility when made into sheets, and still require plasticizers. I found out that. Therefore, as a result of further research, we found that using a copolymer of methacrylic ester that does not contain hydroxyl groups, methacrylic ester that contains hydroxyl groups, and acrylic ester has good dispersibility, and that when a sheet is made, it can be used as a copolymer. It has been confirmed that it is advantageous in that it provides flexibility, leaves no residue during firing, and the decomposition temperature and the sintering temperature of alumina are appropriately close to each other. This invention was made based on such confirmation.

That is, the present invention is a ceramic-forming binder comprising a copolymer of a hydroxyl group-free methacrylic ester, a hydroxyl group-containing methacrylic ester, and an acrylic ester.

As the hydroxyl group-free methacrylic ester, an ester of methacrylic acid and an aliphatic monohydric alcohol is used. Specifically, n-butyl methacrylate, isobutyl methacrylate,
These include alkyl methacrylates such as 2-ethylhexyl methacrylate, and tertiary aminoalkyl methacrylates such as dimethylaminoethyl methacrylate. Among them, n-butyl methacrylate and 2-ethylhexyl methacrylate are preferred. The hydroxyl group-free methacrylic ester is used as the main component, and the amount used is suitably 99.8 to 50% by weight, preferably 99 to 80% by weight, and most preferably 95 to 85% by weight.

As the hydroxyl group-containing methacrylic ester, an ester of methacrylic acid and an aliphatic polyhydric alcohol is used. Specifically, these include hydroxyalkyl methacrylates such as 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate, and polyethylene glycol monomethacrylate and polypropylene glycol monomethacrylate. Among them, 2-hydroxyethyl methacrylate is preferred. The amount of the hydroxyl group-containing methacrylic acid ester to be used is suitably 0.1 to 20% by weight, preferably 0.5 to 5% by weight, and most preferably 1 to 2% by weight, since too much will impair decomposition during firing. .

As the acrylic ester, an ester of acrylic acid and an aliphatic alcohol is used.
Specifically, these include alkyl acrylates such as n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, and tertiary aminoalkyl acrylates such as dimethylaminoethyl acrylate. Among them, 2-ethylhexyl acrylate is preferred. The amount of acrylic ester used should be between 0.1 and 30, as too much will worsen decomposition during firing.
Weight percent is suitable, preferably 0.5 to 15 weight percent, most preferably 5 to 10 weight percent.

The above-mentioned copolymer consisting of at least three types of monomers, ie, a methacrylic ester without a hydroxyl group, a methacrylic ester containing a hydroxyl group, and an acrylic ester, can be produced by, for example, adding a polymerization initiator to a mixture of monomers and causing a polymerization reaction. be done. As the polymerization method, known techniques such as suspension polymerization, solution polymerization, emulsion polymerization, etc. can be applied as they are. Further, the obtained copolymer can be used as it is without being separated and collected from the reaction solution.

Ceramics can be made using the ceramic-forming binder of the present invention as follows. First, a solvent and the binder of the present invention are added to inorganic powder (alumina, zircon, aluminum silicate, titanium oxide, etc.), mixed and defoamed to produce a slurry-like ceramic paint. This is applied onto a support (for example, a polyester sheet), dried by heating as appropriate, and peeled off from the support to obtain a green sheet. The green sheet is punched out into a suitable shape, printed with circuits, characters, etc. as necessary, laminated and pressed together, and fired to obtain ceramic.

The ceramic-forming binder of the present invention has good dispersibility of inorganic powder when it is used to prepare a ceramic slurry. Therefore, the inorganic powder is finely dispersed in the form of primary particles, and as a result, pores are less likely to form in the product. In addition, because of its good dispersibility, the amount used is small, resulting in less shrinkage and deformation during firing.
Good dimensional stability.

Furthermore, when the slurry is applied onto a support to form a green sheet, the sheet has appropriate flexibility, that is, a sheet that is flexible enough to be easily rolled up and not deformed when peeled off from the support. is obtained. Additionally, the sheet is less likely to break when punched. Therefore, when the binder of the present invention is used, no plasticizer can be used at all, or the amount of plasticizer used can be extremely reduced.

Moreover, the ceramic-forming binder of the present invention has good decomposition properties when firing green sheets. Therefore, no residue remains. In addition, since it has good decomposability, it can be fired at a relatively low temperature, so heating costs can be reduced. As noted above, the ceramic forming binder of the present invention has a number of advantages.

Next, the present invention will be explained in more detail with reference to Examples, and the effects of the present invention will be clarified with reference to Comparative Examples.

Example 1 (a) Production of copolymer 100 parts by weight of toluene was placed as a solvent in a separable flask equipped with a stirrer, a cooling tube, a nitrogen introduction tube, and a thermometer, and the air in the flask was replaced with nitrogen. . Next, add 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator and 2 parts by weight as a monomer.
-88 parts of ethylhexyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, and 10 parts of 2-ethylhexyl acrylate were added, and the temperature was raised to 60°C with stirring, and polymerization was carried out for 26 hours. moreover,
The temperature was raised to 80°C, polymerization was carried out for 4 hours, and the mixture was cooled to obtain a terpolymer solution of 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, and 2-ethylhexyl acrylate as a transparent viscous solution.

(b) Production of ceramics Add 30 parts by weight of toluene to 40 parts by weight of the above terpolymer solution.
and 50 parts of methyl ethyl ketone were added and mixed. Add alumina powder to the binder solution thus obtained.
100 parts by weight was added and mixed in a ball mill for 48 hours to disperse the alumina powder to obtain a ceramic paint. This ceramic paint was casted on a polyester film to a thickness of 1 mm.
Air dry at room temperature for 24 hours, then in a hot air dryer at 100℃
It was dried for 1 hour. After cooling, the dried material was peeled off from the polyester film to obtain a green sheet.
This green sheet was fired and made into ceramic.

The above-mentioned green sheet had particularly good gloss, indicating that alumina was well dispersed. In addition, the elastic modulus was 6.91Kg/mm ² , indicating excellent flexibility. Furthermore, it was found that the tensile strength was as high as 0.14 Kg/mm ² and the peelability from polyethylene film was also good.
Also, no residue remained during firing. In addition, when the dried terpolymer was examined by thermogravimetric analysis, the 90% decomposition point was 331°C, indicating excellent thermal decomposition properties.

Comparative Example 1 A copolymer solution was obtained in the same manner as in Example 1 (a) using 90 parts by weight of 2-ethylhexyl methacrylate and 10 parts by weight of 2-ethylhexyl acrylate as monomers. Using this copolymer solution, a green sheet was prepared in the same manner as in Example 1 (b), and was fired to form a ceramic.

This green sheet had a rough surface and poor gloss, indicating that the alumina was poorly dispersed. In addition, the elastic modulus was 2.68 Kg/mm ² and the flexibility was poor, the tensile strength was 0.081 and low, and the peelability from the polyethylene film was also poor.

Comparative Example 2 As a binder solution, 12 parts by weight of polyvinyl butyral, 8 parts by weight of dibutyl phthalate, 50 parts by weight of toluene
Using a mixture of 50 parts by weight and 50 parts by weight of methyl ethyl ketone, a green sheet was prepared in the same manner as in (b) of Example 1, and fired to form a ceramic.

It was found that this green sheet had poor flexibility with an elastic modulus of 1.23 Kg/mm ² and a low tensile strength of 0.090 and was easily broken. Furthermore, it was found that even when the green sheet of Example 1 was fired at a temperature at which no residue was left, carbonaceous residue remained in this green sheet.

Claims (1)

[Scope of Claims] 1. A ceramic-forming binder comprising a copolymer of a hydroxyl group-free methacrylic ester, a hydroxyl group-containing methacrylic ester, and an acrylic ester. 2 Hydroxyl group-free methacrylic acid ester is 2-
A ceramic-forming binder according to claim 1, which is ethylhexyl methacrylate. 3. The ceramic-forming binder according to claim 1, wherein the hydroxyl group-containing methacrylic ester is 2-hydroxyethyl methacrylate. 4. The ceramic-forming binder according to claim 1, wherein the acrylic ester is n-butyl acrylate or 2-ethylhexyl acrylate. 5. The binder for forming ceramics according to claim 1, wherein the content of the methacrylic acid ester not containing a hydroxyl group is 99 to 50% by weight. 6. The ceramic-forming binder according to claim 1, wherein the content of the hydroxyl group-containing methacrylic ester is 0.05 to 10% by weight.