JP2732479B2 - Composition for manufacturing molded article - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a composition for producing a molded article for producing a high-performance ceramic molded article and / or a metal molded article, and more particularly to a plastic composition such as injection molding or extrusion molding. The present invention relates to a composition for producing a molded article capable of producing a ceramic molded article or a metal molded article by forming.

TECHNICAL BACKGROUND AND PROBLEMS OF THE INVENTION Various methods have been conventionally proposed as methods for producing a ceramic molded body or a metal molded body. Particularly in recent years, an injection molding method capable of producing a large number of molded articles having a complicated shape with high precision has been receiving attention.

The injection molding method of a ceramic or metal molded body means that a composition for producing a molded body is first preformed into a desired shape by an injection molding machine, and then the obtained preformed body is heated to obtain ceramics in the raw material. This is a method in which components other than powder or metal powder are decomposed and volatilized, degreased, and then sintered to obtain a molded body having a desired shape. The composition for producing a molded body used at this time is usually a mixture of ceramic powder and / or metal powder, a thermoplastic binder, and, if necessary, a lubricant, etc. Plays a role of imparting strength to the preformed body obtained by the above method, and generally employs either a water-soluble binder or a synthetic resin binder.

The lubricant is added to the composition for producing a molded article in order to improve the wettability between the ceramic powder or the metal powder or between these powders and the binder. Conventionally, stearic acid has been used as such a lubricant. However, stearic acid is easily decomposed at a temperature of 150 ° C. or higher, and therefore, in the step of kneading a ceramic powder or a metal powder and a thermoplastic binder, the stearic acid has a melting point or softening point of 150 ° C.
When it is necessary to knead the composition for producing a molded body at the above temperature, stearic acid is decomposed and volatilized during kneading,
There was a risk of poor kneading. If the composition for ceramics production becomes poorly kneaded, there is a problem that molding defects such as welds occur during injection molding of the composition, and the probability of occurrence of defective products in the obtained molded article becomes extremely high.

Object of the Invention The present invention is to solve the above problems, even if the composition for producing a molded body at a high temperature of 150 ° C. or more for a long time, the lubricant is decomposed or volatilized. It is an object of the present invention to provide a composition for producing a molded article which is free from defects and therefore does not cause defects in a molded article obtained from the composition for producing a ceramic.

SUMMARY OF THE INVENTION A composition for producing a molded article according to the present invention comprises a ceramic powder and / or a metal powder, a thermoplastic binder,
It is characterized by containing behenic acid.

Since the composition for producing a molded article according to the present invention contains a thermoplastic binder and behenic acid in addition to the ceramic powder and / or the metal powder, the ceramic powder and / or the metal powder and / or the above powder and Behenic acid has good wettability with a plastic binder, and does not decompose or volatilize even when the composition is kneaded at a temperature of 150 ° C or higher, and therefore has a melting point or softening point of 150 ° C or higher. A binder can be used, and furthermore, no defect occurs in the obtained molded article.

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the composition for producing a molded article according to the present invention will be specifically described.

In this specification, the term "formed body" means a formed body made of a ceramic or metal, or a mixture of ceramic and metal, and also includes a preformed body.

The composition for producing a molded article according to the present invention comprises a ceramic powder and / or a metal powder, a thermoplastic binder,
Contains behenic acid as a lubricant.

Behenic acid used in the present invention is also called docosanoic acid, and has a structure of CH ₃ (CH ₂ ) ₂₀ COOH. As shown in FIG. 1, the thermal decomposition curve of such behenic acid starts to decrease in weight at 170 ° C. or higher,
Even if the composition for producing a molded article containing behenic acid is heated and kneaded at a temperature of about ℃, decomposition and volatilization does not occur. On the other hand, as shown in FIG. 1, stearic acid, which has been conventionally used as a lubricant, starts to lose weight at a temperature of about 150 ° C., and is used for producing a molded article containing stearic acid at a temperature of 150 ° C. or more. When the composition is heated and kneaded, the decomposition and volatilization of stearic acid starts, and the composition cannot be kneaded sufficiently. The measurement of the thermal decomposition curve shown in FIG. 1 was performed in air at a rate of 10 ° C./min.

Also, behenic acid is a carboxylic acid type lubricant like stearic acid, has good wettability with ceramic powder and / or metal powder, and has excellent properties as a lubricant of a composition for producing a molded article. I have.

The thermoplastic binder used in combination with behenic acid as described above plays a role as a binder for ceramic powder and / or metal powder, and such a thermoplastic binder is usually used as a binder for injection molding. Any binder can be used as long as it is obtained.

Specific examples of such a thermoplastic binder include isotactic polypropylene, polyalkylene carbonate, a compound having one or more epoxy groups in a molecule, polyethylene, polybutene, polymethyl (meth) acrylate, polystyrene, and the like. Ethylene, vinyl acetate copolymers or their low molecular weights, various natural waxes and the like are used.

Among these, polyalkylene carbonate is particularly easily decomposable, and it is effective to use it in combination with behenic acid. Such polyalkylene carbonates have excellent thermal decomposability, and more specifically, are rapid in a low-temperature region even under an oxidizing atmosphere such as in air and a non-oxidizing atmosphere such as in nitrogen. Thermally decomposes into Moreover, the polyalkylene carbonate exhibits excellent thermal decomposition properties as described above even when used in combination with ceramic powder or metal powder. These characteristics are characteristic of polyalkylene carbonate, and are characteristics that are not found in aromatic polycarbonates even for the same polycarbonates.

Such a polyalkylene carbonate can be obtained, for example, by copolymerizing at least one alkylene oxide such as tylene oxide, propylene oxide, butene oxide, and cyclohexene oxide with carbon dioxide (CO ₂ ) using an organozinc catalyst. The obtained copolymer is a chain polymer, and the alkylene group and the carbonate group are alternately contained, or the alkylene group forms a chain by an ether bond.
If necessary, these polyalkylene carbonates may be modified with an unsaturated carboxylic acid or the like.
The molecular weight of such a polyalkylene carbonate is usually 10,000 to 100,000, preferably about 20,000 to 50,000.

In the present invention, basically any polyalkylene carbonate can be used, but the number of carbon atoms of the alkylene group is preferably about 2 to 6, and specifically, polyethylene carbonate and polypropylene carbonate are preferably used. Can be

In the present invention, as a thermoplastic binder,
It is preferable to use a compound having one or more epoxy groups in the molecule together with the above-described polyalkylene carbonate. When a compound having one or more epoxies in a molecule is used in combination with a polyalkylene carbonate as a binder for producing a ceramic molded article, when the pre-molded article is heated and degreased, the heating loss is simply reduced. It became clear that the following effects could be obtained. That is, even if the temperature rise rate at the time of degreasing is increased, it is possible to obtain an extremely good degreased body without swelling or cracking of the preformed body at the time of degreasing. This leads to a reduction in the degreasing time and an improvement in the yield of the obtained molded body.

As the compound having one or more epoxy groups in such a molecule, specifically, the following compounds are used.

Bisphenol A, 2,2-bis (4-hydroxyphenylbutane) (may be abbreviated as bisphenol B), 1,1'-bis (4-hydroxyphenyl) ethane (may be abbreviated as bisphenol AD), Screw (4-
Polyphenols such as hydroxyphenyl) methane (sometimes abbreviated as bisphenol F), 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, 4-hydroxyphenyl ether, P- (4-hydroxy) phenol A glycidyl ether epoxy compound of the compound.

A glycidyl ether-based epoxy compound of a nuclear hydride of the polyphenol compound.

Glycidyl ether epoxy compounds of polyhydric phenols such as catechol, resorcin, hydroquinone, and phloroglucin.

Glycidyl ether epoxy compounds of polyhydric alcohols such as ethylene glycol, polypropylene glycol, butanediol, glycerol, erythritol and polyoxyalkylene glycol.

 Novolak type epoxy compound.

Alicyclic epoxy compounds such as vinylcyclohexene dioxide, limonene dioxide and dicyclopentadiene oxide.

Polyglycidyl ester epoxy compounds of ester condensates of polycarboxylic acids such as phthalic acid and cyclohexane-1,2-dicarboxylic acid.

 Polyglycidylamine-based epoxy compound.

 Methyl epichloro epoxy compound.

The molecular weight n of these epoxy compounds is 100 to 2
It is preferably 0000 to 100 to 3000, more preferably 300 to 1000.

Behenic acid used in the present invention is 70 to 10 parts by volume, preferably 50 to 10 parts by volume, based on 100 parts by volume of the thermoplastic binder.
It is preferably used in an amount of 30 to 10 parts by volume.

It is preferable that the above-mentioned thermoplastic binder and behenic acid are present in a total amount of 20 to 65% by volume, preferably 35 to 60% by volume in the composition for producing a molded article.

In such a thermoplastic binder, various additives usually blended in the ceramic composition and / or the metal composition, for example, a plasticizer, a lubricant, a deflocculant, a surfactant and the like may be blended. Specifically, a plasticizer such as diethyl phthalate or dioctyl phthalate is used as such an additive.

Various known ceramic powders or metal powders that can be used in the present invention can be widely used, and are not particularly limited. Specifically, the following powders are used.

(1) Metal powder Aluminum, silicon, scandium, yttrium, lanthanide, actinide, titanium, zirconium,
Hafnium, thorium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, technetium, rhenium, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium,
Platinum, copper, silver, iron, gold, zinc, cadmium, thallium,
Germanium, tin, lead, arsenic, antimony, bismuth, tellurium, polonium, or alloys thereof such as Fe-Ni alloy, Ni-Cr-Fe alloy, Ni-Cr-Fe alloy, Mo-
Powders such as Fe-Ni alloy and Mn-Fe-Ni alloy.

(2) Metal oxides Oxides of the above metals or other metals such as beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, lanthanum oxide, gallium oxide, indium oxide, selenium oxide, and the like. Is an oxide containing multiple metal elements, namely NaNb
_{O 3, SrZrO 3, PbZrO 3} , BrTiO 3, BrZrO 3, PbTiO 3, AgTa
O _3, BaTiO _3, a metal oxide having a perovskite structure, such as _{LaAlO 3, MgAl 2 O 4,} ZnAl 2 O 4, CoAl 2 O 4, NiAl 2 O 4, NiCr
_{2 O 4, FeCr 2 O 4} , MgFe 2 O 4, Fe 2 O 4, Zn metal oxide having a spinel structure, such as _{2 O 4, MgTiO 3, MnTiO} 3, FeTiO 3, CoTiO 3,
Powders such as metal oxides having an ilmenite structure such as NiTiO ₃ , LiNbO ₃ and LiTaO ₃ and metal oxides having a garnet structure such as Gd ₃ GaO ₁₈ and Y ₃ Fe ₅ O ₈ .

(3) Metal carbide Powders of metal carbides such as silicon carbide, titanium carbide, tantalum carbide, chromium carbide, molybdenum carbide, hafnium carbide, zirconium carbide, and boron carbide.

(4) Metal nitride Powder of metal nitride such as silicon nitride, aluminum nitride, boron nitride, and titanium nitride.

(5) Metal boride Powder of metal boride such as titanium boride, zirconium boride, and lanthanum boride.

(6) Surface modified products of the above (1) to (5) Specifically, the powders of the above (1) to (5) are surface-treated with a coupling agent, a surfactant, a polymerizable monomer, or the like.

(7) Mixture of (1) to (6) In the present invention, the particle diameter of the ceramic powder and the metal powder is not particularly limited, but it is preferable that these powders have an average particle diameter of 100 μm or less. Further, from the viewpoint of the homogeneity of the compact, the ceramic powder and / or the metal powder preferably have an average particle size of 40 μm or less.

Effects of the Invention Since the composition for producing a molded article according to the present invention contains a thermoplastic binder and behenic acid in addition to the ceramic powder and / or the metal powder, the ceramic powder and / or the metal powder or each other The wettability between the powder and the thermoplastic binder is good, and even if the composition is kneaded at a temperature of 150 ° C. or more, behenic acid does not decompose and volatilize, and therefore has a melting point or softening point of 150 ° C. or more. A thermoplastic binder having
In addition, no defects occur in the obtained molded body.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Example 1 Aluminum oxide powder (average particle size: 0.6 μm) 60% by volume
And 20% by volume of isotactic polypropylene and 20% by volume of behenic acid.
For 30 minutes.

The obtained mixture was pulverized to a size of about 3 mm square. Subsequently, the composition was heated at a temperature of 180 ° C., a mold temperature of 40 ° C., and an injection pressure of 1
Injection molding was performed under the condition of 000 kg / cm ² to obtain a preform of 4.5 × 5.5 × 55 mm.

The appearance of the obtained preform was visually inspected and found to be good without weld. Further, when examined by X-ray nondestructive inspection, it was found that there was no defect such as a crack inside the preform.

Next, the preformed body is heated from 0 to 100 ° C at a heating rate of 5 ° C / hour, from 100 to 400 ° C at a heating rate of 3 ° C / hour, and from 400 to 500 ° C at 5 ° C. Degreased by heating at a heating rate of / hour.

Further, the obtained degreased body was heated at a heating rate of 20 ° C./hour for 16 hours.
The temperature was raised to 00 ° C and sintering was performed for 2 hours.

The aluminum oxide sintered body (molded body) thus obtained was examined by an X-ray non-destructive inspection, and it was found that the aluminum oxide sintered body did not include defects such as cracks.

Example 2 57% by volume of silicon carbide powder having an average particle diameter of 0.7 μm containing 0.3% by weight of boron carbide and polypropylene carbonate 13
Epoxy compound with the following structure by volume 20% by volume and 10% by volume of behenic acid were mixed and kneaded at 150 ° C. for 30 minutes in a pressure kneader.

After crushing the obtained mixture to a size of 3 mm square, temperature 1
Injection molding was performed under the conditions of 60 ° C., a mold temperature of 30 ° C., and an injection pressure of 1000 kg / cm ² to obtain a preform of 12 × 14 × 40 mm. The appearance of the obtained preformed body was visually inspected, and it was found that there was no weld and the appearance was good. Further, when examined by X-ray nondestructive inspection, it was found that there were no defects such as cracks inside the molded product.

Next, the preformed body is heated from 0 to 100 ° C at a heating rate of 5 ° C / hour, from 100 to 350 ° C at a heating rate of 3 ° C / hour, and from 350 to 500 ° C at 10 ° C. Degreased by heating at a heating rate of / hour.

Next, the obtained degreased body was heated from room temperature to 2100 ° C. at 400 ° C./hour in an argon atmosphere at a pressure of 2 kg / cm ² ,
And sintered for 2 hours.

Examination of the silicon carbide sintered body thus obtained by X-ray nondestructive inspection revealed that the sintered body did not contain any defects such as cracks.

Example 3 55 vol% of SUS 304L powder (average particle size 9 μm) produced by a water atomizing method, 25 vol% of polypropylene carbonate, and 20 vol% of behenic acid were mixed, and the mixture was heated at a temperature of 150 ° C. for 30 minutes. The mixture was kneaded with a pressure kneader.

After crushing the obtained composition to 3 mm square, temperature 160 ° C., mold temperature 30 ° C., injection molding under the conditions of injection pressure 800 kg / cm ² ,
A preform of 4.5 × 5.5 × 55 mm was obtained.

The appearance of the obtained preform was visually inspected and found to be good without weld. Further, when examined by X-ray nondestructive inspection, it was found that there was no defect such as a crack inside the preform.

Next, the temperature of this preformed body was increased from 0 to 100 ° C at a heating rate of 1 ° C.
Degreasing was performed by heating at a heating rate of 0 ° C./hour, from 100 to 350 ° C. at a heating rate of 5 ° C./hour, and from 350 to 500 ° C. at a heating rate of 10 ° C./hour. The degreasing at this time was performed in nitrogen to prevent oxidation of the metal powder.

After degreasing the preformed body in this way, it was sintered at 1200 ° C. for 1 hour under vacuum conditions.

The sintered body (molded body) thus obtained was examined by an X-ray nondestructive inspection, and it was found that the sintered body did not contain defects such as cracks and was good.

[Brief description of the drawings]

FIG. 1 is a thermal decomposition curve of behenic acid. FIG. 1 also shows a thermal decomposition curve of stearic acid.

Claims (3)

(57) [Claims] 1. A composition for producing a molded article, comprising a ceramic powder and / or a metal powder, a thermoplastic binder, and behenic acid. 2. The composition according to claim 1, wherein behenic acid is contained in an amount of 10 to 50 parts by volume based on 100 parts by volume of the thermoplastic binder. 3. The composition according to claim 1, wherein the thermoplastic binder is a polyalkylene carbonate.