JPS61222953A - Additive for forming ceramics - 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 [Industrial Field of Application] The present invention relates to additives used to improve ceramic molding, particularly injection molding properties, in the process of manufacturing ceramic products.

[Conventional technology]

In general, ceramic products are prepared as a raw material powder made by adding sintering aids to metal oxides, clay minerals, non-oxides, etc., and then a variety of organic forming aids such as binders and plasticizers are added to create the desired shape. It is manufactured by forming into a shape, sintering, and processing. Among these manufacturing processes, the molding process is the most important in order to achieve and maintain desired quality and to manufacture low-cost products with little post-processing.

This molding process includes (1) a method of pressure molding a granulated ceramic composition using a spray dryer, (ii)
) A method of molding a ceramic slurry obtained by adding an appropriate solvent to ceramic powder, a dispersant, a binder, etc. by casting molding or a doctor blade method, (iii) A method of mixing and kneading the ceramic powder and a plastic organic material. A method of extrusion molding or injection molding a ceramic composition obtained by
It is carried out by Among these molding methods, injection molding in particular is currently attracting attention as a molding method for engineering ceramics because it allows products with complex shapes to be manufactured in large quantities with high precision.

In this injection molding, ceramic powder and a predetermined amount of organic molding aid are mixed, heated and kneaded to form a -supported ceramic composition, and then injection molded into a mold. Therefore,
The ceramic composition used here needs to have good moldability during the molding process, shape retention after molding, and good properties during the degreasing and firing processes.
1) The total amount of organic molding aid added to the ceramic powder is small, and the molded product has green strength and good shape characteristics. (2) Good compatibility between the ceramic raw material powder and the organic molding aid. (3) The powder is uniformly dispersed in the molding material by short-time heating and kneading, and the resulting ceramic composition has good thermal fluidity and high moldability. (3) The molded product is free from deformation and cracking. (4) The quality of the organic molding aid is constant, and it is easily available, inexpensive, and easy to handle. It is desirable to have the following.

However, in reality, a single organic molding aid that satisfies all of the above conditions has yet to be found.It is a combination of a suitable thermoplastic resin and additives with specific functions (e.g. plasticity, wetting agent). At present, various methods have been proposed to satisfy the above conditions.

For example, regarding the technique of using a thermoplastic resin as a molding aid, JP-A-48-18305 describes the use of actinic propylene, which has good affinity with ceramic powder and good thermal fluidity of the ceramic composition. is proposed. Regarding the technique of using resins other than thermoplastic resins, Japanese Patent Publication No. 36-13919 proposes thermosetting resins such as phenolic resins that provide good shape retention of molded products. Further, in JP-A-57-156365, sublimation substances such as naphthalene and camphor are proposed as additives for improving degreasing properties.

However, recently, very fine particles with a particle size of 1μ or less are used as ceramic powder, so when manufacturing ceramic molded products, the above conditions (1) (2)
1 is highly desired. In other words, the affinity between the ceramic powder and the organic molding aid is good, and the ceramic powder is uniformly dispersed in the molding aid after a short time of heating and kneading, and the composition has good thermal fluidity, making it easy to mold. High workability is desired. It is also desirable from the viewpoint of degreasing properties that the amount of the machine forming motive agent added is small.

[Problem that the invention seeks to solve]

Therefore, an object of the present invention is to improve the affinity between organic molding aids such as thermoplastic resins, plasticizers, and infiltrating agents in ceramic compositions and ceramic raw material powder in ceramic molding in the ceramic product manufacturing process. It is an object of the present invention to provide an additive for ceramic molding that can uniformly disperse raw material powder in a molding aid by heating and kneading for hours, has good fluidity, and can achieve high moldability and productivity.

[Means for solving problems]

The present invention shows that when a polyether compound starting from a compound having three or more active hydrogen atoms in the molecule is used as an additive for ceramic molding, particularly as an additive for injection molding, ceramic powder can be heated and kneaded in a short time. This was based on the knowledge that the composition can be uniformly dispersed in an organic molding aid, and that the composition has good thermal fluidity and provides high moldability and productivity.

That is, the present invention uses a compound having 3 or more active hydrogens in the molecule as a starting material, and contains a polyether compound in which 5 moles or more of alkylene oxide is added per active hydrogen to the 3 or more active hydrogens. Provided is an additive for ceramic molding characterized by:

Examples of starting materials for the polyether compound of the present invention include the following. Alcohols having three or more active hydrogens (e.g. glycerin, butanetriol, hexanetriol, trimethylolpropane, diglycerin, pentaerythritol) Amines (e.g. ammonia, monoethanolamine, jetanolamine, triethanolamine, beef tallow propylene diamine) , aminoethylethanolamine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, phenylenediamine, benzidine, cyclohexyldiamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine) carboxylic acids (e.g. tartaric acid, trimesic acid, butanetetracarboxylic acid, pyro Mellitic acid)
There is.

In addition, as synthetic polymers, polyamines (for example, polyethyleneimine, polypropyleneimine), polyamides (
For example, dehydrated condensates of polycarboxylic acid components and polyamine components, ring-opening polymers of lactams or co-ring-opening copolymers of two or more lactams, self-condensates of ω-amino-ω′-carboxylic acids) polynuclear polyvalent Examples include alcohols (for example, a condensate of (alkyl)phenol or (alkyl)naphthol and formaldehyde), partially saponified polyvinyl acetate, and partially saponified polyvinyl acetate copolymer.

Natural products include monosaccharides (such as sorbitan, sorbitol, glucose, shakerose), oligo IJ! (
for example cyclodextrin) polysaccharides (for example cellulose, starch, chitin, chitosan). of course,
Derivatives of these compounds can also be used, and they essentially contain 3 active hydrogen atoms in the molecule that can react with alkylene oxide.
It is sufficient to have at least one. The polyether compound used in the present invention is characterized by having a structure in which polyalkylene oxide moieties are branched, and the polyether compound is a polyether compound using a compound having one or two active hydrogens as a starting material. is a linear structure and is not a subject of the present invention.

The alkylene oxide added to the above starting material is:
Any alkylene oxide having 2 or more carbon atoms may be used, specifically one or two of ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, α-olefin oxide having 6 to 20 carbon atoms, styrene oxide, etc. Although mixtures of the above may be used, alkylene oxides having 2 to 4 carbon atoms are preferred.

The structure may be either a random structure or a block structure.

The number of moles of alkylene oxide added may be 5 moles or more per active hydrogen, and usually 5 to 300 moles per active hydrogen, based on 3 or more active hydrogens contained in the compound as a starting material.
The mole amount is preferably 5 to 150 moles. If it is less than 5 moles, it will exhibit properties similar to those of the starting material compound, and if it is more than 300 moles, it will show properties similar to those of a polyethyl compound having a linear structure, which is the object of the present invention as an additive for ceramic molding. Performance is not achieved.

In addition, it is preferable that the alkylene oxide has an average of 5 moles or more added to each of all active hydrogens in the molecule, but if there are many active hydrogens, an average of 5 moles or more of alkylene oxide is added to at least three of them. All you have to do is add .

Furthermore, the present invention also includes compounds in which part or all of the terminal hydroxyl groups of the above polyether compounds are modified with a suitable reaction reagent, and compounds in which the terminal hydroxyl groups are modified with a suitable reaction reagent, and compounds in which the polyether compounds are crosslinked with a suitable crosslinking agent.

As mentioned above, the additive of the present invention is composed of a starting material, a compound part having three or more active hydrogens, and a polyalkylene oxide part, and the type of starting material, the type of alkylene oxide, and the number of moles to be added are selected. Furthermore, by modifying and crosslinking the terminal hydroxyl group to adjust the hydrophilicity and hydrophobicity of this additive, it becomes effective as a ceramic molding additive for all kinds of combinations of ceramic powder and organic molding aids. is demonstrated. The amount added is preferably 0.1 to 30 parts by weight, preferably 0.1 to 20 parts by weight, per 100 parts by weight of the ceramic powder.

This additive increases the affinity between the ceramic powder and the organic forming aid, improves the dispersibility of the powder, and improves the thermal fluidity of the ceramic composition.
If the amount added is less than 0.1 weight, sufficient effects cannot be obtained.
On the other hand, if it exceeds 30 parts by weight, the strength of the molded product will decrease, which is not preferable.

When producing a ceramic composition from ceramic powder and an organic molding aid using the ceramic molding additive of the present invention, the method of adding each component such as the ceramic powder, the organic molding aid, the additive of the present invention, etc. The order, heat kneading, dispersion method for dispersion, type of kneader, and mixing conditions can be arbitrarily determined as long as the performance of the additive of the present invention is not impaired. However, the additive of the present invention is also effective as a dispersant for ceramics (Japanese Patent Application
9-258555, Japanese Patent Application No. 59-269552), first, using the additive of the present invention as a dispersant, ceramic powder and sintering aid are dispersed down to the primary particles and mixed uniformly to obtain a raw material powder. After that, by heating and kneading it with an organic molding aid, its effect as an additive is further demonstrated.

Ceramic powders and organic molding aids in which the additives of the present invention are suitably used are shown below.

O Ceramic Powder Ceramic powders to which the present invention is applied include both oxide-based and non-oxide-based ceramic powders. Specifically, oxide ceramics of single oxides such as aluminum oxide, zirconium oxide, silicon oxide, magnesium oxide, titanium oxide, yttrium oxide, beryllium oxide, kaolinite, composite oxides such as PLZT and manganese ferrite, and carbonized Carbides such as silicon, tungsten carbide, titanium carbide, and boron carbide; nitrides such as silicon nitride, aluminum nitride, boron nitride, and titanium nitride; carbons such as graphite and amorphous carbon; and boron such as lanthanum polide and titanium polide. Examples include one or more ceramic powders selected from non-oxide ceramics such as oxides, sulfides such as cadmium sulfide and zinc sulfide, and silicides such as molybdenum silicide. In addition, these ceramic powders include:
Particles with a diameter of lμ or less are preferable, but are not limited to this,
Anything can be used regardless of production method, crystalline state, purity (chemical composition), particle morphology, particle size and specific surface area. Furthermore, as a sintering aid, a compound containing beryllium, aluminum, carbon, boron, nitrogen, etc. can be added, or various aids can be added to develop a specific function.

○ Organic molding aids Compounds of thermoplastic resins, wetting agents, plasticizers, etc. are used.

Specifically, thermoplastic resins include polystyrene, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, acidic polypropylene, styrene-butadiene copolymer, polymethyl acrylate, polybutyl methacrylate, polyethylene glycol, etc. There is. These resins may be used alone or in amounts of 3 to 30 parts per 100 parts by weight of the ceramic powder.

Wetting agents include liquid paraffin, natural paraffin, micro wax, polyethylene wax, stearic acid, lauric acid, myristic acid, erucylamide, hardened beef tallow amide, oleic acid amide, stearic acid amide,
Valmitic acid amide, lyrinic acid amide, methylene bis stearamide, ethylene bis stearamide, methylene bis acrylamide, butyl stearate, glycerin monostearate, ethylene glycol monostearate, polyethylene glycol monostearate,
Cetyl alcohol, stearyl alcohol, myristyl alcohol, octadecylamine, primary tallow amine,
Turpentine oil, corn oil, menhaden oil, pentene oil,
Waxes such as pine oil, coconut oil, castor oil, and hydrogenated peanut oil, oils and fats, and derivatives thereof are included. These wetting agents may be used alone or in amounts of two or more, and are generally used in an amount of 0.1 to 20 parts by weight per 100 parts by weight of the ceramic powder.

Examples of the plasticizer include glycerin, ethylene glycol, dioctyl phthalate, dibutyl phthalate, diethyl phthalate, etc., and are used in an amount of 0.1 to 20 parts by weight per 100 parts by weight of the ceramic powder.

However, it is not limited to the thermoplastic resin, wetting agent, plasticizer, etc., and organic molding aids that can be used in injection molding (
For example, surfactants) may be used in combination.

In the present invention, when heating and kneading this organic molding aid and ceramic powder, by adding a polyether compound, which is an additive for ceramic molding of the present invention, the ceramic powder can be heated and kneaded in a short time. It is possible to uniformly disperse the composition in a molding aid, and the composition has good thermal fluidity, thereby providing high moldability and productivity. The reason why the additive of the present invention exhibits its performance is that it has an affinity for both ceramic powder and organic forming aids, as is clear from its structure and its effectiveness as a dispersant for ceramics. Therefore, the affinity between the ceramic powder and the organic molding aid is improved, and the kneaded particles are dispersed in the molding aid by short-time heating and kneading. In addition, since the polyalkylene oxide portion plays the role of steric protection between particles, it is believed that the powder particles are more uniformly dispersed and the thermal fluidity of the ceramic composition is improved. Therefore, when the additive of the present invention is first used as a dispersant, the particle surface is uniformly coated with the additive of the present invention, and even more effects are exhibited.

〔Effect of the invention〕

When the ceramic molding additive of the present invention is added to a ceramic molding composition, especially an injection molding composition, the affinity between the ceramic powder and the organic molding aid improves, and the powder can be molded by heating and kneading for a short time. It can be uniformly dispersed in the molding aid. Further, by adding the additive of the present invention, the fluidity of the ceramic composition is improved, giving high moldability and productivity, while making it possible to mold with a small amount of molding material.

Therefore, since the additive for ceramic molding of the present invention has the above characteristics, it can be suitably used not only for injection molding but also for extrusion molding, cast molding, and pressure molding.

Next, the present invention will be explained with reference to Examples, but the present invention is not limited thereto. Note that both "parts" and "%" shown in Examples are based on weight.

〔Example〕

Example 1 As a ceramic injection molding composition, the following raw material powder and organic molding aid were mixed and heated and kneaded at 160° C. for 30 minutes in a Laboplasto mill. Table 1 shows the torque during kneading at that time. Note that performance was evaluated by replacing 1 part of 1.5 parts of plasticizers (D, B, P) with the additive of the present invention.

The compositions used are shown below, and the results obtained are summarized in Table 1.

Ceramic raw material powder: Alumina 100 parts Organic molding aid: 16.5 parts Breakdown Ethylene-vinyl acetate copolymerization 4.1 parts Polybutyl methacrylate 8.4 parts Stearic acid
2.5 parts, B, P (dibutyl phthalate))
1.5 parts Table 1 shows that the torque value of the ceramic composition containing the additive of the present invention is lower, and the fluidity of the ceramic composition is improved.

Example 2 As a composition for ceramic injection molding, the following raw material powder and organic molding aid were mixed, and the mixture was heated and kneaded at 140° C. in a laboplast mill. At that time, the time required to reach an equilibrium state and the torque at that time are shown in Table 2. Table 2 also shows the dispersibility of the ceramic powder in the organic molding aid.

Ceramic powder: 100 parts Silicon carbide 90 parts Carbon
4 parts boron carbide 6 parts Organic molding aid: 21.9 parts Ethylene-vinyl acetate copolymer 5.4 parts polybutyl methacrylate Il, 2 parts stearic acid
3.3 parts, B, P 1
．． 0 parts Additive of the present invention 1.0 parts Example 3 Performance was evaluated in the same manner as in Example 2, except that the following organic molding aids were used and kneaded under heat at 160°C. The results are shown in Table-3.

Organic molding aid: 21 parts Polyethylene 6.1 parts Acrylic polypropylene 10.1 parts Stearic acid
2.3 parts, B, P
1.5 parts Additive of the invention 1.0 parts Example 4

Claims (2)

[Claims] (1) A compound having three or more active hydrogens in the molecule is used as a starting material, and a polyether compound containing at least 5 moles of alkylene oxide per active hydrogen is added to the three or more active hydrogens. A characteristic additive for ceramic molding. (2) The additive according to claim (1), wherein the alkylene oxide is at least one alkylene oxide selected from the group of ethylene oxide, propylene oxide, and butylene oxide.