JPH0687123A - Recovering method of inorganic filler silica - Google Patents

Abstract

PURPOSE:To efficiently recover silica favorable in purity and contrive to effectively utilize resources by a method wherein a set matter of thermosetting resin molding material mainly containing silica as filler is ground into particles having the size of 500mum or less and calcined at 800-1,300 deg.C under the state being sprayed in oxidizing atmosphere. CONSTITUTION:The recovery of silica is performed by grinding the set matter of thermosetting resin molding material mainly containing silica as filler into particles having the size of 500mum or less and the calcining at 800-1,300 deg.C under the state being sprayed in oxidizing atmosphere. Since the silica melts at 1,500-1,700 deg.C, the melting temperature of which differs depending upon its crystal system and which turns into block by melting near the melting the point, the calcination at 1,300 deg.C or lower in necessary in order to obtain silica having the same particle size as that of stock is without melting. By grinding lump set matter into particles having the size of 500mum or less, the surface area of the matter is increased remarkably and the heat transfer to the whole set matter is facilitated, resulting in perfectly burning the matter in a short period of time by calcining the matter in the manner being sprayed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for recovering silica from a cured product of a thermosetting resin molding material containing silica as a main filler.

[0002]

2. Description of the Related Art Regarding sprues, runners, etc., which are conventionally generated when a molded article is manufactured from a resin molding material, in the case of a thermoplastic resin molding material, it can be recycled and reused relatively easily because it is reheated and melted. In the case of thermosetting resin molding materials, sprues, runners, etc. are hardened products.
Since it cannot be recycled by remelting, it has been disposed of. In recent years, the increase in waste causes deterioration of living environment and waste of limited resources, so that it is required to devise a method of recycling as much as possible. Sprues, runners, and sometimes defective moldings produced during molding of thermosetting resin molding materials are considered to be used as a compounding agent by crushing, but the application is limited because the composition contains a resin and a filler. It will be.

Also with respect to thermosetting resin molding materials, defective products before molding or before curing are uncured, so that the resin can be dissolved and the filler can be easily recovered by using an appropriate solvent. However, once cured, it becomes insoluble in the solvent and cannot be recovered by the solvent.
Until now, as a method of recovering the filler from the sprue and runner of the thermosetting resin molding material, it has been attempted to incinerate it as it is, but as its composition, in addition to the filler, a resin as a binder, depending on the case, Since some of them contain a flame retardant, it takes a lot of heat energy to incinerate them, and it takes time, so that it is difficult to take out silica in a good condition.

[0004]

If the filler in the cured product of the thermosetting resin molding material can be recovered in good condition, it can be recycled for a wider range of uses. The present inventor has conducted various studies on such a method of recovering the filler and has completed the present invention.

[0005]

According to the present invention, a cured product such as a sprue or runner generated during molding of a thermosetting resin molding material is pulverized to 500 μm or less and sprayed in an oxidizing atmosphere to 800 to 1300. By incineration under the temperature condition of ° C, silica can be recovered in a short time in a particle size of the raw material with good purity. Thermosetting resin molding materials contain epoxy resin, phenol resin, melamine resin, polyester resin, etc. as binders, and they are burned by heating, but they are carbonized in a reducing atmosphere, so oxygen is sufficient. If it is incinerated in the state existing in, it cannot be fully decomposed. The thermal decomposition temperature of the thermosetting resin is generally 600 ° C. or lower, and if it is higher than that, it should be incinerated, but in reality, it is mixed with other components, so in order to burn it in a short time, ,
By incineration at 800 ° C. or higher, it is possible to prevent the incomplete combustion products of the resin from remaining in the recovered components.

Silica varies depending on its crystal system,
The melting point is 1500 to 1700 ° C., and when it approaches the melting point, it melts and blocks, so in order to obtain the raw material particle size without melting, it is necessary to incinerate at 1300 ° C. or less. Hardened products such as sprues and runners are lumpy as they are, and some resin components have flame retardant properties such as phenolic resin, and some contain flame retardants, so complete combustion up to the center To do so requires a large amount of heat energy and a long time. In order to eliminate such drawbacks, the lump-shaped cured product is pulverized to 500 μm or less, so that the surface area is greatly increased and heat transfer to the entire cured product is facilitated. Complete combustion is possible in time, and silica can be recovered in good condition.

[0007]

【Example】

«Example 1» Sprue and runner (cured product) generated during molding of an epoxy resin molding material for low-pressure encapsulation molding containing 60% by weight of silica powder as a filler were crushed to a particle size of 500 μm or less, and the temperature accuracy was ± 100 ° C. While spraying into an incinerator with sufficient air supply, while supplying sufficient air 11
Burned at a temperature of 00 ± 100 ° C. The obtained recovered silica was a silica powder having a purity of 99.6% and no agglomeration and the same particle size (average particle size 15 μm) as the raw material. «Comparative Example 1» A sprue and runner (cured product) generated during molding of the same epoxy resin molding material for low-pressure encapsulation molding as in Example were crushed and the temperature was 1100 ± 100.
It was incinerated at ℃ for 2 hours under natural air supply. In the state after the incineration, the surface was ashed, but the inside was not separated because the resin was carbonized, and silica with high purity could not be recovered.

[0008]

According to the method of the present invention, silica as an inorganic filler can be efficiently recovered from a cured product of a thermosetting resin molding material, and the purity of silica is also good. Since silica can be easily recovered from sprues, runners, etc. generated during molding of thermosetting resin molding materials,
This is a useful method for effective use of resources.

Claims (1)

[Claims] 1. A cured product of a thermosetting resin molding material containing silica as a main filler is pulverized to 500 μm or less,
A method for recovering silica, which comprises incineration at a temperature of 800 to 1300 ° C. while spraying in an oxidizing atmosphere.