JPS5941949B2 - Method of forming ceramic powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for molding ceramic powder, particularly when mixing resin with ceramic powder and injection or extrusion molding.
This relates to a molding method in which the amount of resin used is minimized without substantially impairing moldability.

In recent years, ceramics have come to be widely used in everything from general industrial materials to electronic components.

Along with this, these products have come to have considerably stricter requirements regarding dimensional accuracy, physical properties, shape, etc.

As a means to meet these demands, a suitable resin is added to ceramic powder to give it thermoplasticity, which is molded by injection or extrusion, and then the resin contained in the molded product is thermally decomposed. After removal, several methods have been proposed and implemented to perform main firing to obtain a desired ceramic product.

Although the resin used in this method facilitates moldability during injection or extrusion molding, the resin must ultimately be removed from the molded article, and such removal usually involves There is a risk that cracks, blisters, or deformation may occur in molded products whose resin is gasified and removed by thermal decomposition.

In order to avoid such inconveniences, thermal decomposition usually needs to be carried out carefully over several tens to hundreds of hours at a very low rate of temperature increase per unit time.

For this reason, this method is not necessarily satisfactory for industrial mass production, and even if the resin is removed over such a long period of time, cracks and deformations still occur at a considerable rate.

Furthermore, in the conventional method, the A-phase resin that improves moldability is used in approximately the same volume as the ceramic or metal powder, and when this is removed to obtain the final fired product, the amount of resin is Usually, the resin tends to be present non-uniformly within the molded body, and such shrinkage tends to cause the entire molded body to deform.

In view of this, the present inventor believes that if the amount of resin used can be reduced as much as possible without substantially impairing moldability, the above-mentioned drawbacks of the conventional method can be improved,
As a result of various studies and examinations aimed at finding such means, we found that in a method of mixing resin with ceramic powder and molding them, by using a silane coupling agent or a titanium coupling agent together with the resin,
It has been found that the above object can be achieved.

Suitable resins used in the present invention include thermoplastic resins such as polyethylene, polypropylene, polystyrene, acrylonitrile-tsukudiene-styrene copolymer, and polyvinyl chloride.

Further, examples of the silane coupling agent used with the resin include γ-meccryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, These include vinylt'J ethoxysilane, vinyl-tris(β-methoxyethoxy)silane, and γ-aminepropyltriethoxysilane.

Further, as a titanium-based coupling agent, for example, isopropyl triisostearic acid can be mentioned.

Strictly speaking, the amount of these coupling agents used varies depending on the type of resin, camping agent, ceramic powder, etc. used, but it is generally 1 to 5 weight by weight based on the total mixture of resin and ceramic powder used. It is appropriate to use about %.

If the amount of the coupling agent used is less than the above range, it will not be possible to effectively reduce the amount of resin used without substantially impairing the moldability, whereas if it exceeds the above range, the molding will not be possible. Neither of these methods is preferable since there is a risk that cavities may be formed or swelling may occur in some parts of the body.

When using 1 to 3% by weight within this range, it is particularly preferable because the amount of resin can be effectively reduced without substantially impairing moldability, and no cavities or bulges will occur in the molded product. .

In addition, the amount of resin used varies slightly depending on the type of resin, the type of ceramic powder, and the type of coupling agent used, but in general, the amount of resin used is 10 If it is used in an amount of about 20% by weight, it has sufficient moldability and does not cause problems such as cracks.

This amount is 5 to 1 % of the amount of conventionally used resin.
This corresponds to a reduction of 0%.

Further, the ceramic powder used in the present invention includes, for example, silicon nitride, alumina, zirconia, cordierite, silicon carbide, aluminum nitride, etc., and the particle size thereof is suitably about 1 to 10 μm.

In addition, in the present invention, in addition to the resin and coupling agent,
Additives such as plasticizers such as diethyl phthalate and dioctyl phthalate and lubricants such as stearic acid and lead stearate can be used as appropriate.

Although there are no particular restrictions on the molding means used in the present invention, injection molding, extrusion molding, and similar molding methods are particularly advantageous.

In this case, there are no particular restrictions on the injection or extrusion molding equipment or method used, and equipment and methods commonly used for molding plastics can be used as appropriate.

As a means for removing the resin from the molded article obtained by employing the method of the present invention, any conventional removal method may be employed as appropriate.

For example, the obtained molded product is heated to a temperature of 30 to 50°C from room temperature to around 200°C using an appropriate heating means such as a circulating hot air electric furnace.
The resin can be effectively removed by raising the temperature at a temperature increase rate of about 200 to 350 degrees Celsius and waiting for about 5 to 10 hours at about 3 to 350 degrees Celsius. It becomes possible to reduce the resin removal time by about 20 to 40% by conventional methods.

Next, the present invention will be explained by examples.

Example 1 79.5% by weight of silicon nitride powder, 11.9% by weight of polystyrene, 2.0% by weight of active polypropylene, 1.6% by weight of polyethylene, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane 1.6% by weight of diethyl chloride, 1.6% by weight of stearic acid, and 1.8% by weight of stearic acid were sufficiently kneaded using a pressure kneader at a temperature of 180°C and 2.5 atm to form pellets of 3 to 5 mvb. It was formed into a shape.

The pellets were heated at a heating cylinder temperature of 250°C and an injection pressure of 1 t/i.
, mold temperature 50°Ct Trowel 60mm x 100mm x 8
It was possible to easily injection mold a mvt plate-like body without any problems such as cracks.

The obtained molded body was heated from room temperature to 200°C at a heating rate of 50°C/hour using a hot air circulating electric furnace.
- 350℃ by increasing the temperature to 350℃ at a heating rate of 4℃/hour
It was kept at ℃ for 5 hours.

The resin contained in the obtained molded product was substantially completely removed due to weight loss, and no cracks or deformation were observed in the molded product.

Example 2 Alumina powder 76.3% by weight, polystyrene 15.2% by weight, polyethylene 2.8% by weight, γ-methacryloxypropyltrimethoxysilane 2.0% by weight, diethyl tucrate 1.5% by weight, stearin 1.7% by weight of acid was kneaded in the same manner as in Example 1, and pelletized in the same manner.

The pellets were injection molded in the same manner as in Example 1, and were easily molded without any cracks.

Example 3 Cordierite powder 79°5% by weight, polystyrene 15
．． 5% by weight, β-(3,4-epoxycyclohexyl)
2.4% by weight of ethyltrimethoxysilane, 0.8% by weight of diethyl phthalate, and 1.8% by weight of stearic acid were kneaded in the same manner as in Example 1, and pelletized in the same manner.

The pellets were injection molded in the same manner as in Example 1, and were easily molded without any cracks.

Example 4 77.6% by weight of silicon nitride powder, 14.4% by weight of polystyrene, 3.7% by weight of polyethylene, 2.4% by weight of isopropyl triisostearic titanate, and 1.8% by weight of stearic acid as in Example 1. The mixture was kneaded in the same manner and pelletized in the same manner.

The pellets were injection molded in the same manner as in Example 1, and were easily molded without any cracks.

Claims (1)

[Scope of Claims] 1. A method for molding ceramic powder, characterized in that a silane coupling agent or a titanium coupling agent is used together with the resin in the method of mixing ceramic powder with a resin and molding the mixture. 2. The method of claim 1, wherein the resin is a thermoplastic resin. 3. The method according to claim 1 or 2, wherein the thermoplastic resin is polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene copolymer, or polyvinyl chloride. 4. Silane coupling agents include γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxyltrimethoxysilane, vinyltriethoxysilane, vinyl-tris( The method according to claim 1, wherein the silane is β-methoxyethoxy)silane, or γ-aminopropyltriethoxysilane. 5. The method of claim 1, wherein the titanium-based coupling agent is isopropyl triisostearic titanate. 6. The method according to claim 1, wherein the silane coupling agent or the titanium coupling agent is used in an amount of 1 to 5% by weight based on the total mixture. 7. The method according to claim 1, 2 or 3, in which the resin is used in an amount of 10 to 20% by weight based on the total mixture.