JPS61241069A - Manufacture of abrasives for blast processing - Google Patents

Abstract

PURPOSE:To collect screened-through particles in good performance by mixing powder of hardened polyester resin below a particle size of 150mum with unsaturated polyester resin in liquid state in a specified proportion followed by hardening, by post-hardening in specified temperature condition and then crushing. CONSTITUTION:100 parts by weight by weight of powder of hardened polyester resin having a particle size below 150mum is mixed with 300 parts by weight or more of polyester resin liquid state followed by agitation until uniform consis tency is obtained. After hardening with a hardening agent added, the admixture is hardened for 4-10 hr, or preferably 4-7hr, at a temperature of 100-180 deg.C, or desiarably 100-150 deg.C. As this hardened polyester resin is in lumps, they are coarse crushed with a jaw crusher etc. followed by further crushing with a roll mill etc., and then screening is carried out to provide an abrasive material with specified particle size. Thus screened-through particles below a particle size of 150mum can be collected without impairing the quality as a grinding element such as hardness and form as well as without lowering the rate of collection.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing an abrasive material for blasting made of an unsaturated polyester resin, and particularly to an abrasive material suitable for removing pars from synthetic resins.

(Prior art and its problems) Powder of cured unsaturated polyester resin (hereinafter simply referred to as polyester resin) is widely used as an abrasive material for blasting (hereinafter simply referred to as abrasive material) like other synthetic resins. ing. Polyester resin is a thermosetting resin, so in order to use this resin as an abrasive, it is cured by adding a curing agent such as methyl ethyl ketone peroxide to the resin, and then cured by further heating (post-curing). It was manufactured by crushing and sifting. In addition, post-curing is usually performed at a temperature of 60 to 8
This method is carried out by heating at 0°C for about 3 hours.

Important characteristics for an abrasive material include hardness and shape. In order to remove debris without damaging the object to be polished, the hardness of the abrasive must be lower than that of the object to be polished. Further, it is preferable to have a rounded shape with a mass window, and it is preferable that the particle size is within a certain particle size range.

The hardness of the abrasive differs depending on the material of the object to be polished, the shape of the surface, etc., but it is usually 40 in JISK-6911 Percoll hardness.
~60 are frequently used.

The particle size of the abrasive varies depending on the shape and hardness of the object to be polished, the polishing method (wet method, dry method), etc., but it is usually 0.15 to 1.
．． It is about 0u. Therefore, conventionally, when manufacturing abrasive materials from polyester resin, there is a problem in that during the crushing and sieving process, so-called spec-out products with particle sizes outside this range are generated, resulting in a decrease in yield. Among these spec-out products,
The upper part of the sieve, which has a particle size larger than the above range, can be re-pulverized to adjust the particle size and be used as an abrasive, but the lower part of the sieve, which has a smaller particle size, can no longer be used as an abrasive. It is. Moreover, since the cured polyester resin is thermosetting, it cannot be melted and remolded like thermoplastic resins. Therefore, the unsieved material had to be disposed of as industrial waste, but since it is a fine powder, it is difficult to dispose of it, and it also easily causes dust pollution, which is also a big problem in terms of resource and energy conservation. Met. Therefore, it has been desired to develop a method for effectively utilizing these out-of-spec products, especially the unsieved products.

In view of the above points, the present inventor thought that it would be possible to reuse the mixture as an abrasive by mixing the under-sieve product and a polyester resin, curing and pulverizing the mixture. However, even when attempting to produce an abrasive material wM using this method, an extremely large amount of small particles were generated during the crushing process, and it was practically impossible to obtain an abrasive material with an appropriate particle size and shape as an abrasive material for blasting. .

(Means for Solving the Problem) As a result of further various studies on this point, the inventor of the present invention found that the above problem can be solved by post-curing under specific conditions after curing the mixture of the unsieved product and the liquid polyester resin. This discovery led to the present invention.

That is, in the present invention, 100 parts by weight of a cured polyester resin powder having a particle size of 7 or less than 150 μm is mixed with 300 parts by weight or more of a liquid unsaturated polyester resin, and the mixture is cured at a temperature of 10
This is a method for producing an abrasive for blasting, which is characterized by post-curing at 0 to 180°C for 4 to 10 hours, and then pulverizing.

A method of implementing the present invention will be explained in detail.

First, a cured polyester resin powder with a particle size of 150 μm or less (hereinafter simply referred to as small particle product) is added to a liquid polyester resin.

) and 300 parts by weight or more of liquid polyester resin are mixed well until uniform. Next, a curing agent is added thereto and after curing, the temperature is 100 to 180°C, preferably 100 to 150°C, for 4 to 10 hours, preferably 4 to 7 hours.
Allow to harden after hours.

Since the cured polyester resin is in the form of lumps, it is possible to obtain an abrasive material of a predetermined particle size by forming the resin into a frame using a show crusher, crushing it with a crusher such as a hammer mill or roll mill, and sieving it. Approximately 5 to 10% by weight of unsieved material is generated during sieving, but since the particle size is in most cases less than 150μ, it can be effectively reused as small particles to be mixed with the liquid polyester resin. I can do it.

As the curing agent, for example, 55% methyl ethyl ketone peroxide dissolved in dimethyl phthalate is used, as in the conventional method, and the appropriate amount of addition is about 1% based on the liquid polyester resin.

Part by weight or more is appropriate. If the amount of liquid polyester resin is less than 600 parts by weight, it will be difficult to mix uniformly with small particles, and small particles will be unevenly distributed locally, and most of the hardened and pulverized products will have a particle size of 0.15 m or less. Therefore, it is unsuitable as an abrasive material. There is no particular upper limit to the amount of liquid polyester resin, but in view of the purpose of the present invention, which is to effectively utilize small particles, it is not preferable to use it for fire extinguishing.
00 parts by weight or less is suitable. Further, the particle size of the small particles used must be 150 μm or less, and if it is thicker than 150 μm, it will be difficult to mix uniformly, and as a result, it will not be possible to obtain an abrasive material with an appropriate particle size.

In the present invention, post-curing conditions are extremely important.

Conventionally, in the production of polyester resin abrasive materials, post-curing conditions of about 3 hours at 60 to 80 DEG C. have been generally adopted in order to obtain materials with appropriate hardness. However, when using a mixture of small particles and liquid polyester resin, if the mixture is post-cured under these conditions, a large amount of small particles will be generated during the crushing process, making it virtually impossible to use a particle size suitable for use as an abrasive. You can't get it. The present invention is 100 to 180
By selecting different post-curing conditions than the conventional conditions of 4 to 10 hours at ℃, it is possible to create an abrasive material for blasting with appropriate hardness, particle size, and shape. It is significant in that it is significant. Post-curing conditions are unfavorable at temperatures below 100°C, as the compatibility between the liquid polyester resin and small particles becomes poor, and the amount of unsieved products increases during the pulverization process. Temperatures above 180°C are undesirable. In this case, the cured polyester resin undergoes thermal deterioration and becomes brittle, causing a problem in its repeated use as an abrasive.

The heating time during post-curing is determined by the relationship with temperature,
Although 4 to 10 hours is necessary in terms of the compatibility between the cured polyester resin and the small particles and the hardness of the abrasive, longer times are problematic because the polyester resin will undergo thermal deterioration and become brittle.

(Effect of the invention) In the past, attempts have been made to recover the unsifted product in the sieving process using a method similar to the present invention, but when the unsifted product is added, it is mixed with the liquid polyester resin cured product that is the virgin resin and small particles. There was a problem in that adhesion with certain unsieved products was insufficient, and the unsieved products increased during the crushing and sieving steps, and the hardness of the abrasive material also decreased, making it impossible to obtain a shape with a sense of mass.

The present invention specifies the type, particle size, and amount of cured resin added to liquid polyester resin, and also specifies the curing temperature and time during post-curing. A method has been established to recover particles with a particle size of 150 μm or less that do not impair the quality of the abrasive, such as its hardness, shape, or yield.

(Example and comparative example) EXAMPLES The present invention will be specifically explained below using examples.

Example 1 To 100 parts by weight of a liquid polyester resin (manufactured by Mitsui Toatsu Kagaku ■, trade name Nyster R-235), 25 parts by weight of the cured resin (small particle product) having a particle size of 150 μm or less was added and mixed,
Add 1 part by weight of methyl ethyl ketone peroxide (concentration 55% by weight) dissolved in dimethyl phthalate as a hardening agent, stir thoroughly and mix.
It was poured into a container with a height of 0u and a height of 35+u+ and cured. This molded product was post-cured at 120°C for 5 hours, then coarsely crushed with a crusher, and then crushed with a hammer mill to obtain a particle size of 1.
An abrasive material with a feeling of mass was obtained in the range of 5o to 1oooμ. The yield was 94.8%, and the unsieved product with a particle size of 150 μm or less was 5.2%. The Percoll hardness of the post-cured product was 44.

Using this abrasive material, seven deburrs were removed using a wet blast polishing apparatus for molded semiconductor molded products sealed with epoxy resin. As a result, the mold part was not damaged (paris was completely removed).

Example 2 Liquid polyester resin (Mitsui Toatsu Chemical Co., Ltd., x, r,
An abrasive material with a feeling of mass was obtained in the same manner as in Example 1, except that the post-curing was carried out at 160° C. for 4 hours. The yield was 94.2% and the particle size was 15゜μ.
The following unsieved products were 5.8%. The Percoll hardness of the post-cured product was 46.

This abrasive was used to deburr an epoxy resin-sealed semiconductor molded product in the same manner as in Example 1. As a result, the mold part was not damaged (paris was completely removed).

Example 3 Y (manufactured by Mitsui Toatsu Chemical ■, Nistar R-2140) was used as a liquid polyester resin, and post-curing was carried out. : An abrasive material with a feeling of mass was obtained in the same manner as in Example 1 except that it was carried out at 100° C. for 7 hours. Yield is 95.1% and particle size is 150μ
The following unsieved products were 4.9%. Incidentally, the epoxy resin-sealed semiconductor molded product was deburred using a post-polishing material in the same manner as in Example 1.

As a result, the paris could be completely removed without damaging the mold part.

Comparative Example 1 An abrasive with a particle size of 150 to 1000μ was obtained in the same manner as in Example 1, except that post-curing was carried out at 80°C for 3 hours, but the yield of the obtained abrasive was 85%, which was low. . (15% of unsieved products with a size of 150 μ or less) The Percoll hardness of the post-cured product is 35
(The shape of the abrasive material also lacked a sense of mass, and there were many flakes.

Using this abrasive material, an epoxy resin-sealed semiconductor molded product was deburred in the same manner as in Example 1, but it was not possible to completely remove deburrs.

Comparative Example 2 An abrasive with a particle size of 150 to 1 oooμ was obtained in the same manner as in Example 1, except that post-curing was carried out at 200°C for 7 hours.
The yield of the obtained abrasive material was significantly reduced to 60%. (1
(40% of unsieved products of 50 μ or less) Although the Percoll hardness of the post-cured product was 46, the shape of the abrasive lacked a sense of mass,
There were many flaky and needle-like substances. When this abrasive Z was used to remove burrs from an epoxy resin-sealed semiconductor molded product in the same manner as in Example 1, the burrs were successfully removed, but the molded product was damaged.

Claims (1)

[Claims] 100 parts by weight of cured polyester resin powder having a particle size of 150μ or less and 300 parts by weight of liquid unsaturated polyester resin
1. A method for producing an abrasive material for blasting, which comprises mixing parts by weight or more, curing, post-curing at a temperature of 100 to 180° C. for 4 to 10 hours, and then pulverizing.