JPS63319247A - Production of ceramic molded body - Google Patents

Abstract

PURPOSE:To produce the title molded body which permits defatting at relatively low temp. and contains no breakage by molding a slurry contg. ceramic powder, a specified binder, and an alcohol, then defatting and calcining. CONSTITUTION:A binder consisting of poly(alpha-ethyl styrene) is prepd. by adding oxygen to a polymer having several thousands-several millions mol.wt. obtd. by the living anion polymn. of alpha-methyl styrene at <=50 deg.C in vacuum or in inert gas atmosphere in the presence of an organolithium compd. (e.g. butyl Li). Then, a slurry is prepd. by mixing 100pts.wt. ceramic powder, 5-50pts.wt. said binder, 0-50pts.wt. plasticizer (e.g. phthalic diester), and 0.1-10 times by weight (basing on the amt. of the ceramic powder) 1-20C alcohol (e.g. methanol). Then, the slurry is molded, then defatted, sintered or coagulated by fusion.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a ceramic molded body, and more specifically, to a method for producing a ceramic molded body, and more specifically, to a method for producing a ceramic molded body, the present invention relates to a method for manufacturing a ceramic molded body, and more specifically, to a method for producing a ceramic molded body, and more particularly, to a method for producing a ceramic molded body, the present invention relates to a method for manufacturing a ceramic molded body, and more specifically, to a method for manufacturing a ceramic molded body, and in particular, to a method for producing a ceramic molded body, the present invention relates to a method for producing a ceramic molded body, and more specifically, to a method for producing a ceramic molded body, and in particular to a method for producing a ceramic molded body, the present invention relates to a method for producing a ceramic molded body, and more specifically, to a method for producing a ceramic molded body, and more specifically, to a method for producing a ceramic molded body, the present invention relates to a method for producing a ceramic molded body, and more specifically, to The present invention relates to a method for producing a ceramic molded body, which improves the properties of the molded product and allows complete degreasing at a relatively low temperature.

[Conventional technology]

Industrial methods for manufacturing ceramic products that require complex shapes and high dimensional accuracy include the so-called pressureless sintering method, which involves firing preformed compacts, and the reaction sintering method. It is.

Here, methods for forming the compact include a wet pressing method, a doctor blade method, an extrusion molding method, and a composition prepared by adding a sintering accelerator in addition to a binder to ceramic powder such as alumina or ferrite, if necessary. Molding into a desired shape is performed by a dry or wet method such as injection molding.

The present inventors have already developed a method using polyα-methylstyrene (Japanese Unexamined Patent Application Publication No. 1983-1990) as a method that allows degreasing at a relatively low temperature.
-51657).

[Problem that the invention seeks to solve]

However, when manufacturing molded products before degreasing using a wet method, especially using a mixture of slurry-like resin, ceramic powder, and solvent, the flowability of the slurry is poor, making it difficult to mold the molded products, or using paste. When manufacturing a multilayer molded product by placing the paste on a ceramic plate, there were problems such as poor fluidity of the paste and difficulty in applying it properly.

[Means for solving problems]

The present inventors have intensively studied methods for solving the above problems and have completed the present invention.

That is, the present invention provides a method for producing a ceramic molded body in which ceramic powder is mixed with a thermoplastic resin as a binder, molded, degreased, and sintered or fused. Poly-α-methylstyrene is made by adding oxygen to a polymer with active terminals, and is characterized by mixing ceramic powder and poly-α-methylstyrene in a solvent containing at least alcohol and forming it into a slurry. This is a method for manufacturing a ceramic molded body.

In the present invention, the polyα-methylstyrene used as a binder may be a homopolymer of α-methylstyrene, or a polymer that can be polymerized in a state in which the decomposition properties of polyα-methylstyrene are not lost and the active terminals are still alive. do, i.e.
Copolymers with other copolymerizable monomers to the extent that living anionic polymerization is possible can also be used. For example, it can be polymerized to contain several percent to several tens of percent of styrene and its derivatives, or dienes such as butadiene, as other copolymerizable monomers.

What is important in the present invention is that α-methylstyrene or other copolymerizable monomer is subjected to living anion polymerization using organic lithium such as butyllithium, ethyllithium, methyllithium, or organic sodium such as sodium naphthalene, and then The key point is to use polyα-methylstyrene to which oxygen is added while the active end is alive.

There is no particular restriction on the method of living anionic polymerization, and any known ordinary method can be employed.

The polymerization temperature is 50"C or less, preferably 30C or less, and the reaction is carried out in vacuum or in an inert gas atmosphere such as nitrogen in the presence or absence of an aromatic hydrocarbon such as benzene or toluene. During polymerization, diglyme or the like may be used as an activator, or α-methylstyrene and other copolymerizable monomers may be reacted randomly or in a block manner.

As oxygen, a mixture with an inert gas such as nitrogen or, for example, air can be used, but oxygen that has been sufficiently dehydrated is used. The amount used is equal to or more times the mole of active terminals as oxygen.

There is no particular restriction on the molecular weight of the α-methylstyrene polymer used, but a range of several thousand to several million is usually appropriate. Further, a mixture of α-methylstyrene dimers to octamers can also be used.

Also important in the present invention is the binder α
- When mixing the methylstyrene polymer and the ceramic powder, a solvent containing at least alcohols is used, and the alcohols are compounds containing one or more OH groups in the molecule. It does not matter if it is a alcohol. As alcohols, those having about 1 to 20 carbon atoms can be used, and aliphatic alcohols such as methanol, ethanol, propatool, butanol, and hexanol are common, but of course alicyclic alcohols such as cyclohexanol and terpineol can be used. , phenol, aromatic alcohols such as benzyl alcohol, etc. can also be used.

In the present invention, in addition to the above-mentioned alcohol, benzene, toluene, which is a good solvent for α-methylstyrene polymer,
Aromatic hydrocarbon compounds such as xylene and ethylbenzene,
Alicyclic hydrocarbon compounds such as cyclohexane and decalin,
It is preferable to use an ether such as tetrahydrofuran.

The amount of alcohol used varies depending on the type and type of ceramic, but it is appropriate that the volume of alcohol be approximately 0.1 to 10 times the volume of the ceramic powder used, and a good solvent should be used. If so, the ratio thereof varies depending on the type of solvent used, but it is preferable to use the above-mentioned solvent which is a good solvent to the extent that the α-methylstyrene polymer is uniformly dissolved. Also, if necessary, first α
- It is also possible to dissolve the methylstyrene polymer in a good solvent, disperse the ceramic powder in alcohol, and then mix the two.

For mixing, it is preferable to use a device capable of relatively strong mixing, such as a ball mill or a homogenizer. There are no particular restrictions on the temperature during mixing, and room temperature is sufficient.

In the present invention, in addition to the above-mentioned α-methylstyrene polymer, a plasticizer such as phthalic acid diester, liquid paraffin, styrene or α-methylstyrene oligomer can be used in combination, if necessary. Generally, the proportions of these materials are 5 to 50 parts by weight of polyα-methylstyrene and 0 to 50 parts by weight of plasticizer per 100 parts by weight of ceramic powder.

The method of the present invention can be applied to any molding method, but in particular, it can be applied to a method in which ceramic powder and a binder are mixed in a suitable solvent and fluidized, and then formed into a sheet by a doctor blade method, etc. Various wet methods can be applied, such as a method in which a paste is applied to a substrate, degreased, and then sintered or melted.

The present invention will be further explained below with reference to Examples.

Example 1 Poly α-methylstyrene [a 2/1 volume ratio solution of toluene and α-methylstyrene at 0°C with a butyllithium concentration of 0.
Polymerization was carried out by stirring at 0.001M for 2 hours, and then oxygen sufficiently dried with 3A molecular sieves was charged until the red color of living anions disappeared (II! of oxygen was charged into the gas phase for 11 of the solution). Synthesized with a number average molecular weight of 150,000 obtained by precipitating in a large amount of methanol] 3
In 60 g of a toluene solution containing 5 wt% of α-methylstyrene oligomer (manufactured by Mitsui Toatsu Chemical ■, MS-730), 20 g of 2-methylhexanol, 40 g of luene, and 100 g of ultrafine alumina for ceramic molding were thoroughly mixed in advance. The resulting slurry was added and mixed, and further mixed in a ball mill for 3 hours.

The pasty slurry could be easily removed by tilting the container. Pour this slurry onto a Teflon sheet to a thickness of 1
It was made into a sheet of mIn.

After drying, the sheet was cut and the cut surface was observed to find that the alumina was uniformly dispersed.

Also, cut the sheet into 10 x 10 cm and make a diameter of 5+
400° of the nn+ hole drilled with a patch cutter
Although it was degreased with C, no defects were caused in the shape of the sheet and holes.

This degreased sheet was sintered at 1400°C to obtain a defect-free alumina sintered body.

Comparative Example 1 2-methylhexanol was replaced with toluene of the same weight,
Furthermore, a polymer obtained by deactivating polyα-methylstyrene by adding methanol without using oxygen (
When the same procedure as in Example 1 was carried out except that a slurry with a number average molecular weight of 160,000 was used, the slurry mixed in a ball mill could not be taken out by simply tilting the container, and the fluidity was poor, and the sheet produced from it was clearly non-uniform. Met. Further, the cut surface of the obtained sheet was also non-uniform, with some parts of the sheet broken when holes were made, and a total of five places broken after degreasing.

Example 2 The same procedure as in Example 1 was carried out except that 2-methylhexanol and toluene were replaced with terpineol and decalin, respectively.

The cross section of the obtained sheet was uniform, there was no problem with the shape of the molded product after degreasing, and there were no defects after sintering.

Example 3 In the polymerization, 10% of α-methylstyrene was replaced with styrene,
Moreover, the procedure was the same as in Example 1 except that air dried in the same manner was used instead of oxygen. The number average molecular weight of the obtained polymer was 180,000. There were no abnormalities in the shape of the molded product after degreasing, and the sheets obtained by the same operation were further heated to 1400
A uniform sintered body was obtained by sintering at °C.

〔Effect of the invention〕

By carrying out the method of the present invention, molding is easy because the slurry of the mixture of ceramic and binder has good flowability, the molded product is uniform before degreasing, and degreasing can be performed at a relatively low temperature. , ceramic molded bodies can be produced without breaking during processing, degreasing, sintering or fusion,
It is extremely valuable industrially.

Claims (1)

[Claims] 1. In a method for producing a ceramic molded body in which ceramic powder is mixed with a thermoplastic resin as a binder, molded, degreased, and sintered or fused, active terminals obtained by polymerizing the thermoplastic resin by a living anionic polymerization method are used. A ceramic made by adding oxygen to a polymer having a poly(α-methylstyrene), which is formed by mixing ceramic powder and poly(α-methylstyrene) in a solvent containing at least an alcohol and forming a slurry. Method for manufacturing a molded object.