JPS62297257A - Polyamide base binder for ceramic injection molding - 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 Summary of the Invention The present invention relates to improvements in binders used in injection molding of ceramics.

<Description of Prior Art> Generally, ceramic products are manufactured by mixing a ceramic material and a binder, molding, degreasing, and firing the mixture. In this case, the selection of the binder cannot be ignored because it particularly affects the success or failure of the molding and degreasing steps.

That is, if the binder is selected incorrectly, degreasing may not be sufficient, causing adverse effects such as partial carbonization or cracking of the molded product. This is especially true when molding is performed using methods such as injection molding or extrusion molding that use a large amount of resin, when the molded product is relatively large, or when the structure is complex. It was seen.

Objective of the present invention The objective of the present invention is to use an amide compound such as polyamide resin as the main component of the binder, and to
The object of the present invention is to improve or improve moldability and degreasing properties, as well as improve the yield of the obtained fired crystals.

Detailed Description of the Present Invention> The binder for ceramic injection molding of the present invention comprises (a) 2
(2) an auxiliary substance;

(I) When 50 mg of one of the above two types of resins having an amide bond is heated at 5°C/min and the weight change in air is examined using a thermobalance, the temperature at which the weight loss is reduced by 50% is determined. It is a polyamide resin having a temperature of 380°C to 480°C.

More specifically, they are polyamide resins obtained by polycondensation of aliphatic carboxylic acids or reactive salts such as acid chlorides thereof with polyamines, or self-polymerization of cyclic lactams.

Examples of the acid raw material include 02 to C54 carboxylic acids or reactive salts thereof such as acid chlorides, preferably C2 to C2□ carboxylic acids or dimer acids. These acids can be used in combination if necessary.

Examples of the polyamine raw material include C2 to CI2 diamines, polyether diamines, etc., and preferably ethylene diamine, hexamethylene diamine, xylylene diamine, polyether diamine, etc. These can be mixed and used if necessary.

The polyamide resin as described above is hereinafter referred to as a resin material for convenience.

This "resin powder" is used in an amount of about 20 to 60% by weight of the total amount of binder.

(II) When 50 mg of the other resin of the two types of resins having an amide bond is examined for weight change in air using a thermobalance while heating at 5°C/min, the temperature at which the weight loss is 50% is 18
It is an amide compound having a molecular weight of 170 to 560 at 0 to 350°C.

More specifically, they include amide compounds derived from fatty acids or reactive salts thereof such as acid chlorides, and ammonia, fatty acid amines, or alicyclic amines.

Examples of the fatty acid include Cl-C22 monocarboxylic acid. They can be mixed and used if necessary. Examples of the amine component include 08 to C2□ monoamines and heterocyclic compounds such as piperazine, which may be used in combination if necessary. Both are subjected to a condensation reaction to form an amide compound having a molecular weight of about 170 to 560.

In the present invention, it is believed (without intending to be bound by theory) that amide bonds in polyamide resins and the like provide positive affinity. In particular, it is thought that when it exists between the ceramic particles of the molded body, it exerts a strong adhesive force and works to maintain the positional relationship of the ceramic particles when it reaches a static state.

This is predicted or supported because the auxiliary substances described in detail later can maintain sufficiently high shape retention even if they do not have particularly strong adhesion to the ceramic particles. If we focus on such functions, it will be understood that both the type and amount of auxiliary substances can be selected within a relatively wide range.

In short, one of the features of the present invention is the use of a compound with an amide bond, which has a positive effect on the surface interaction called "wettability" or "compatibility" between the ceramic material and the binder, For example, when silicon nitride is selected as one of the ceramic raw materials, water bonds form, improving wettability and shape retention.

(I [I) Auxiliary substance In the binder of the present invention, (B) an auxiliary substance is further added to (a) two types of resins having amide bonds.

The auxiliary substances include a bisphenol-type epoxy resin with a molecular weight of 320 to 1000, a resin obtained by reacting one or more amines selected from monoalkylamine, monoethanolamine, and piperazine, and dimethylformamide. , dimethylacetamide, dialkyl phthalate, benzyl alcohol, benzyl acetate, caproic acid, capric acid, caprylic acid, lauric acid, myristic acid, palmitic acid, and stearic acid.

In the present invention, the auxiliary substance serves to prevent rapid degreasing and assist the degreasing of the resins (A) and (B).

The auxiliary substance moderates the heat loss curve of the binder measured on a thermobalance at elevated temperatures. Therefore, its suitability can be selected mainly based on the heating loss curve (see FIG. 1).

The amount of auxiliary substances used must be at least 6% by weight of the total binder amount. This is because if it is less than 6% by weight, it does not play a sufficient auxiliary role and therefore, for example, cracks occur in the degreased body.

Hereinafter, the auxiliary substance will be abbreviated as (C) for convenience.

In the resin described above, (B) and (C) are heated, melted,
The mixture is mixed and, if necessary, made into a sheet or pellet form and used as a binder.

Alternatively, the ceramic material and each component may be kneaded directly.

Note that all known injection molding methods can be employed as a method for molding ceramics.

Effects of the present invention The binder of the present invention exhibits better wettability than conventional binders. Therefore, by adding a small amount, it works more effectively, and as a result, moldability, degreasing properties, and yield of fired crystals are significantly improved.

Example 1 The compounds shown in the following formulation examples were polycondensed, and the compounds (
Polyamide resin) was manufactured.

Dimer acid 580 parts by weight Ethylene diamine 4 Polyether diamine
216 This produced resin is hereinafter referred to as <A,)-1.

C22 dicarboxylic acid 370 parts by weight Infrondiamine 34 Xylylenediamine
109 This produced resin is hereinafter referred to as (A)-2.

Next, stearylamine and acetic acid and stearylamine and lauric acid are subjected to a synthesis reaction, respectively, by a conventional method to form a resin (an amide compound). Hereinafter, for convenience, the former product will be referred to as (B)-1, and the latter product will be referred to as (B)-2.

Further, bisphenol A type epoxy resin 380 weight Ims stearylamine 280 was reacted in a conventional manner to obtain a resin.

Hereinafter, it will be referred to as (C) for convenience.

Next, various raw materials (A) to (C) obtained in this way
were mixed in the following proportions.

('') Binder composition 1 (A)-1100 weight section)-150" ω)-275〃 (c) 75〃
Dibutyl phthalate 15 Dimethyl phthalate 15 (ii) Binder composition 2 (A) -2150 weight Miyakoda) -2150 Dibutyl phthalate 25 parts by weight Stearic acid 8 Example 2 Easily sintered alumina [pressure bulk density 2.30 g / am
(Pressure 1000 kg/ci) Specific surface area 5.5 m'/g
l) 16 parts by weight of the polyamide binder having binder composition 1 was heated and kneaded at 120°C, cooled and pulverized to obtain a molding material based on 100 parts by weight. This was molded into a top shape at a molding temperature of 140°C and a pressure of 660 kgf/cd, and then heated from room temperature to 80°C for 2 hours at 80°C.
to 420℃ for 1 hour at 5.6℃, and after degreasing 1
It was baked at 620°C for 8 hours. Yield over 85%. A product with a bulk density of 3.95 or more was obtained.

Comparative Example 1 A conventional binder showing good results was prepared for comparison.

First, 3.5 parts by weight of ethylene vinyl acetate copolymer (hereinafter referred to as EVA resin) was added to 100 parts by weight of the alumina of Example 2.
4.5 parts by weight of acrylic resin, 8.0 parts by weight of modified wax, and 1.5 parts by weight of dibutyl phthalate were heated and kneaded at 120°C, cooled, and then pulverized.

This molding material could be molded at a pressure of 660 kgf/c++f and an injection temperature of 165° C. or higher.

The degreasing and firing process was the same as in Example 2. Thus the yield is about 75
%, bulk density of 3.94 or more was obtained.

Example 3 Silicon nitride (φ2 μm or less 63.5% by weight, specific surface area 7
．． 0m'/g) 100 parts by weight and high purity alumina (purity 9
9.99%) and 35 parts by weight of Y2O were mixed in alcohol for 48 hours.

Adding 22 parts by weight of the polyamide binder having binder composition 2 to 100 parts by weight of this adjusted powder,
The mixture was heated and kneaded at 120°C, cooled, and then ground to obtain a molding material.

This was molded into a top shape at a molding temperature of 150°C and a pressure of 660 kgf/ant, and then heated at 5 to 10°C per hour in an N2 atmosphere.
The temperature was raised to 500°C for degreasing, and the product was fired at 1800°C for 8 hours.

Yield over 75%. A product with a bulk density of 3.10 or more was obtained.

Comparative Example 2 For comparison, a conventional binder was prepared which showed good results.

First, to 100 parts by weight of the silicon nitride powder used in Example 3, 6.4 parts by weight of EVA resin, 9.5 parts by weight of acrylic resin, 4.3 parts by weight of stearic acid, 2.2 parts by weight of dibutyl phthalate, 3.8 parts by weight of modified wax was added, and the same treatments as in Example 3, ie, molding, degreasing, and baking, were performed.

A product with a yield of about 50% and a bulk density of 3.10 or more was obtained.

[Brief explanation of the drawing]

FIG. 1 shows the heating loss curve of the binder of the present invention. Figure 1

Claims (6)

[Claims] (1) (a) Two types of resins having amide bonds and (b)
A resin obtained by reacting a bisphenol-type epoxy resin with a molecular weight of 320 to 1000 with one or more amines selected from monoalkylamine, monoethanolamine, and piperazine, dimethylformamide, dimethylacetamide, dialkyl phthalate, Polyamide for ceramic injection molding, characterized in that it consists of one or more compounds selected from benzyl alcohol, benzyl acetate, caproic acid, capric acid, caprylic acid, lauric acid, myristic acid, palmitic acid, and stearic acid. system binder. (2) For one of the two types of resins having an amide bond, when the weight change of 50 mg of the resin is examined in air using a thermobalance while heating at 5°C/min, the temperature at which the weight loss is 50% is 38
The polyamide binder for ceramic injection molding according to claim 1, which is a polyamide resin having a temperature of 0°C to 480°C. (3) The polyamide binder for ceramic injection molding according to claim 1, wherein one of the two types of resins having an amide bond accounts for 20 to 60% by weight of the total binder amount. (4) For the other resin having an amide bond, when the weight change of 50 mg of the resin is examined in air using a thermobalance while heating at 5° C./min, the temperature at which the weight is reduced by 50% is 180 to 35.
The polyamide binder for ceramic injection molding according to claim 1, which is an amide compound having a molecular weight of 170 to 560 at 0°C. (5) The other of the resins having an amide bond is 20 to 60% by weight of the total binder amount.
A polyamide binder for ceramic injection molding as described in . (6) The polyamide binder for ceramic injection molding according to claim 1, wherein the compound (b) accounts for 6% by weight or more of the total binder amount.