JPS627663A - Binder for forming ceramic - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a binder used when forming a ceramic by firing an inorganic powder such as alumina.

(Prior Art) 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, a slurry is prepared by adding a fraction of alumina to a solution containing a binder and a plasticizer, and the slurry is applied in a layer on a polyester sheet or the like using a doctor grade, and then dried. The sheet obtained in this manner is called a raw sheet or green sheet. This sheet is rolled up and stored, taken out and punched out with a die as needed, and the punched pieces are fired to decompose the binder and sinter the alumina to form a ceramic.

In the above method, cellulose resin, acrylic resin, polyvinyl butyral, etc. are used as the binder, but they have good dispersibility of inorganic powder, moldability during sheet molding, sheet strength, etc. Butyral resin is attracting attention.

However, recently, for example, there has been a trend to use finer inorganic powder as a raw material in order to further improve the surface smoothness of integrated circuit boards, so there is a demand for resins with better dispersibility of inorganic powder. Furthermore, improvements in tensile strength and abrasion resistance of green sheets are required.

(Problems to be Solved) In view of the above-mentioned drawbacks of the conventional binders for forming ceramics, the object of the present invention is to use polyvinyl acetate which has good dispersibility of inorganic powder and good tensile strength and abrasion resistance of the obtained green sheet. An object of the present invention is to provide a binder for forming ceramics.

(Means for Solving the Problems) One of the characteristics of the ceramic-forming binder according to the present invention is that it contains, as the polyvinyl acetal, a polyvinyl mixed acetal that has been mixed and acetalized with different aldehydes.

Generally, polyvinyl acetal is obtained by acetalizing polyvinyl alcohol with an aldehyde, but in the present invention, the polyvinyl alcohol used for this acetalization may be a completely saponified product or a partially saponified product. good. However, polyvinyl alcohol having a degree of saponification of 90 to 100% is preferably used. Furthermore, the degree of polymerization is not limited at all, but is preferably in the range of 200 to 2,600.

In the present invention, butyraldehyde is used in combination with at least two aldehydes selected from formaldehyde, acetaldehyde, globionaldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde, and octylaldehyde. still,
Among these aldehydes, formaldehyde and acetaldehyde include formaldehyde and paraacetaldehyde which can be converted into these.

In the polyvinyl mixed acetal used in the present invention, lower aldehyde F1 special formaldehyde improves its wear resistance, higher aldehydes including butyraldehyde improve its solubility in solvents, and acetaldehyde has properties intermediate between these. It helps to grant.

Among the above aldehydes, butyraldehyde is essential for the following reason. That is, butyraldehyde improves the compatibility of the polyvinyl mixed acetal with the plasticizer, thereby increasing the dispersibility of the inorganic powder (without forming secondary particles) and improving the sheet bottom shape. This is because it increases the physical properties such as tensile strength of the obtained green sheet.

As other aldehydes, formaldehyde and acetaldehyde are particularly preferably used.

The total degree of acetalization of these polyvinyl mixed acetals is not particularly limited, but is generally 50 to 80 mol%, preferably 60 to 75 mol%. This is thought to be because dispersibility with the inorganic powder is ensured by retaining an appropriate amount of residual hydroxyl groups. However, when the degree of acetalization by a single aldehyde exceeds 50 mol %, the resulting binder substantially exhibits properties based on the properties of a single acetal by the aldehyde, which is not preferable. Therefore, in the binder according to the invention:
When the total degree of acetalization is in the range of 60 to 75 mol% and the degree of acetalization by each aldehyde is in the range of 5 to 50 mol%, the dispersibility of the inorganic powder is particularly excellent, and It is particularly preferred that the total degree of acetalization by aldehyde to the solvent is at least 1 mol %, and the degree of acetalization by butyraldehyde is at least 1 mol %.

The method for preparing the mixed acetal as described above is not limited at all. For example, known methods for acetalizing polyvinyl alcohol include acetalization in a solvent system using A/L/C-/L/ etc. as a solvent, and acetalization in an aqueous system using water as a solvent. This method may also be used.

The above-mentioned polyvinyl mixed acetal is used in combination with a plasticizer to become the binder of the present invention, and the plasticizers include fucuric acid esters, phosphoric esters, fatty acid esters, glycol derivatives, etc., which are mainly known as softening agents for polyvinyl butyral. A wide range of methods are used, but the invention is not limited to these.

Further, the mixing ratio of the polyvinyl acetal and the plasticizer is preferably 1:α3 to 1:L5 in terms of weight ratio, and particularly preferably 1:α4 to 1:LO.

To make a ceramic using the ceramic-forming binder of the present invention, generally, the following steps are performed.

First, an inorganic powder (alumina, zirufun, aluminum silicate, titanium oxide, paricum titanate, etc.) is added as a solvent and the binder of the present invention is mixed and defoamed to form 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 a ceramic.

(Example) In the following, the term % simply indicates weight %.

Example I Synthesis of Kl i-polymerized polyvinyl acetal 51 Pure water 3400F and polyvinyl alcohol (average degree of polymerization 800, degree of saponification 95 mol%) were added to a 320°C rubble flask.
After completely dissolving the mixture at 90° C. for 2 hours, an acetalization reaction was carried out in the following manner.

Cool the liquid temperature to 50-55℃ and add hydrochloric acid (35%) as a catalyst.
After adding 245y of
% Formaldehyde 1042.99%/N-butyraldehyde 31f and 99% n-butyraldehyde 1132 were appropriately added to precipitate a white powder.

Next, the reaction system was heated and aged at 40 to 60°C for 2 to 5 hours, washed with water and neutralized to remove the catalyst and remaining aldehyde from wood bark, and dried to give about 350 f of white powdery polyvinyl mixed acetaf VM fat. I got an A.

The results of the compositional analysis of Resin A were that the total degree of acetalization was 7L2 mol%, and the proportions of each mixed acetalization were haformalization, 30 mol%, acetoacetalization, 11 mol%, and butyralization.

311L was 2 mol%.

(b) Production of Green Sheet 10 parts by weight of the above resin A was added to 30 parts by weight of toluene and 215 parts by weight of methyl ethyl but and dissolved with stirring. After that, 5 parts by weight of digtylphthalate as a plasticizer was added and mixed with stirring.

To the thus obtained binder solution, 100 parts by weight of alumina powder was added as an inorganic powder and mixed for 48 hours using a ball sill to fractionate the alumina powder and create a slurry.

This slurry was cast onto a polyester film to a thickness of 1 layer, air-dried at room temperature for 30 minutes, and further dried in a hot-air dryer at 60-80° C. for 1 hour. After cooling, the dried material was peeled off from the polyester film to obtain a green sheet.

This green sheet has excellent surface gloss, indicating that alumina is well-fractionated.

It was also revealed that the elastic modulus is high and the flexibility is excellent.

It was also found that the film had a high tensile strength and good releasability from the polyester film. Furthermore, the percent surface hardness was also good. The detailed physical properties were as shown in Table 1.

Example 2 A green sheet was produced in the same manner as in Example 1 except that paricum titanate was used as the inorganic powder. This sheet also had good surface gloss, and its tensile strength, elastic modulus, surface hardness, etc. were as shown in Table 1.

Comparative Example 1 (a) Synthesis of resin 51cm/(Pour 2650P of pure water and 320Y of polyvinyl alcohol used in Example 1 into a rubble flask,
The mixture was heated at ℃ for 2 hours to completely dissolve it. Thereafter, a butyralization reaction was carried out using fire. Hydrochloric acid (35%) as a catalyst at 40-50°C 55f! After adding the liquid, lower the liquid temperature to 20~3℃.
n-butyraldehy)'' (99%) 489 and 1
84y was added in portions to obtain a white powdery resin. Further, 3172 ml of hydrochloric acid was added as a catalyst, and the reaction system was aged at 30 to 40° C. for 5 hours, followed by aqueous neutralization and drying to obtain about 350 P of white powdery resin B.

As a result of analysis, Resin B has a butycooling degree of 721) mol%.
polyvinyl butyral.

(W) Production of Green Sheet A green sheet was produced in the same manner as in Example 1, except that Resin B was used as the binder resin, and its physical properties were measured. The results were as shown in Table III.

Comparative Example 2 A green sheet was created in the same manner as Comparative Example 1 except that paricum titanate was used as the inorganic powder.

The physical properties were as shown in Table gg1.

1st! The surface hardness of the fist was measured using a type A deeromeku.

(Effects of the Invention) The ceramic-forming binder of the present invention has the above-mentioned structure, and due to the balance of characteristics of the specific polyvinyl mixed acetal, it is possible to use inorganic powder when making a slurry for ceramics. Good dispersibility. Therefore, the inorganic powder is finely fractionated in the form of primary particles, and together with a good balance of the above properties, it has higher tensile strength, elastic modulus, and abrasion resistance than when using conventional polyvinylguticool binders. A green sheet with excellent physical properties such as

Claims (1)

[Claims] 1 Formaldehyde, acetaldehyde, propionaldehyde, amylaldehyde, hexylaldehyde,
1. A ceramic-forming binder comprising a polyvinyl mixed acetal mixed with butyraldehyde and at least two aldehydes selected from heptylaldehyde and octylaldehyde, and a plasticizer.