JPH0493178A - Projection member for wet blast - Google Patents

Abstract

PURPOSE:To properly perform a precise blasting by forming a projection member for a wet type blasting with the mixture of alumina and at least one kind of thermoplastic resin selected from the group of polyamide, polycarbonate, polyphenylene sulfide, polyolefine and polystyrene, being formed in a granular shape. CONSTITUTION:A wet type blasting projection member is made with fine alumina being uniformly dispersed in granular shape in at least one kind of a thermoplastic resin selected from the group of polyamide, polycarbonate, polyphenylene sulfide, polyolefine and polystyrene. Consequently, the polishing capacity is increased, yet the smoothness of the polishing face of a resin molding and good external appearance are maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a projectile for wet blasting used for deburring resin molded products.

(Prior Art) Conventionally, blasting has been widely performed for the purpose of removing burrs from metal castings and resin moldings.

Metal particles and various ceramic particles are generally used as blasting materials for blasting.

Furthermore, for resin molded products, a resin composite material is used as a projectile material in order to maintain a good surface appearance.

Examples of this resin composite material for projectile materials include, for example, JP-A-59
Examples include those described in Japanese Patent Application Laid-open No. 69265 and Japanese Patent Application Laid-Open No. 60-228075. This publication discloses a projectile material having an average specific gravity of 1.6 or more, in which the surface of glass peas or fine grains of natural igneous rock is coated with a synthetic resin having a relatively high specific gravity, such as polyacetal or polycarbonate. Since these blasting materials have a specific gravity of 1.5 or more, it is stated that when used in wet blasting, uniform processing can be performed without floating on the water surface due to water flow.

However, both glass peas and natural igneous rock in the shot material contain silicate as a main component, and their polishing ability as abrasive grains is not sufficient. Moreover, these abrasive grains are relatively coarse, with a particle diameter of 0.3 mm or less, or 0.1 mm or less, and the smoothness of the polished surface is insufficient.

(Problems to be Solved by the Invention) The present inventors have completed the present invention as a result of intensive research in order to improve the drawbacks of the prior art, and the object of the present invention is to The object of the present invention is to provide a projectile material for wet blasting that has excellent polishing ability and can maintain the smoothness and good appearance of the polished surface of a resin molded product.

(Means for Solving the Problems) The above object is to produce a wet blasting material made of a granulated mixture of alumina and at least one thermoplastic resin selected from the group of polyamide, polycarbonate, polyphenylene sulfide, polyolefin, and polystyrene. Achieved by projectile material.

The present invention will be explained in detail below.

In the present invention, at least one thermoplastic resin selected from the group of polyamide, polycarbonate, polyphenylene sulfide, polyolefin, and polystyrene is used.

First, the polyamide resin used in the present invention is generally not particularly limited as long as it is a linear polymer having an amide group in the molecular button, and examples thereof include ε-caprolactam, aminocaproic acid, 7-aminohebbutanoic acid, 11 - Polymers such as aminoundecanoic acid, 9-aminononanoic acid, α-pyrrolidone, diamines such as hexamethylene diamine, nonamethylene diamine, undecamethylene diamine, dodecamethylene diamine, metaxylylene diamine, terephthalic acid, isophthalic acid, adipine, etc. A polymer obtained by polycondensation with an acid, a dicarboxylic acid such as sepatic acid, or a copolymer thereof can be used.

Specific examples of these polymers or copolymers include nylon 4.6.7.8, 11.12.6G, 69°61
0.611,612.6T, 6I, 6/86, 6/12
Examples include ゜6/6T.

Next, the polycarbonate resin used in the present invention can be prepared by the phosgene method in which dihydric phenol and phosgene are reacted, or by the
It is a polymer or copolymer obtained by a transesterification method in which a hydric phenol and a carbonate ester such as diphenyl carbonate are reacted, and a polycarbonate resin produced from 2,2-bis(4-hydroxyphenyl)propane is particularly preferable. .

Further, the polyphenylene sulfide resin used in the present invention is a polymer in which benzene rings and sulfur are alternately bonded, and examples thereof include a polymer produced using baladichlorobenzene and sodium sulfide as starting materials.

Moreover, the polyolefin resin used in the present invention is a polymer of olefinic hydrocarbon, and polyethylene and polypropylene are preferably used.

Next, the alumina used in the present invention is normally one obtained by high-temperature firing of aluminum hydroxide, but in particular, α
Alumina is preferred. In addition, the average particle size of alumina is
It may be 100 μm or less, particularly preferably 10 μm.
m or less, more preferably 0.5 to 7 μm.

Furthermore, although alumina may be used as it is, it is preferable to subject alumina to various surface treatments, including coupling treatment, in order to improve fluidity and physical properties.

The blending amount of alumina in the present invention is 10% of the thermoplastic resin.
0 parts by weight, preferably 50 to 300 parts by weight, particularly preferably 80 to 200 parts by weight. If the blending amount is less than 50 parts by weight, the abrasive power as a projectile for wet blasting is likely to be insufficient, and because the specific gravity is low, it tends to float on the surface of the water stream, making it difficult to process uniformly and precisely. This tends to be difficult. On the other hand, if the blending amount exceeds 300 parts by weight, the fluidity is insufficient, and melt mixing becomes difficult when blending into a thermoplastic resin, and the resulting product may also be brittle and have problems with durability. be.

In the present invention, the mixture of thermoplastic resin and alumina is
Various methods can be used. For example, melt-kneading may be performed using a single-screw or multi-screw extruder, or frictional melt-kneading may be performed using a mixer having high-speed stirring blades such as a hexiel mixer.

The alumina mixed thermoplastic resin composition thus obtained usually has an average particle size of preferably 100
After pulverizing to 700 μm, preferably 200 to 500 μm, it is used as a projectile material for wet blasting. That is,
If the average particle diameter of the blasting material is less than 100 μm, the polishing force during wet blasting tends to be insufficient, whereas if it exceeds 700 μm, polishing of the details of the molded product tends to be insufficient.

(Effects of the Invention) As described above, the projectile material for wet blasting according to the present invention has fine alumina uniformly dispersed in the thermoplastic resin, has excellent polishing power, and has excellent polishing power on the polished surface after polishing. It has excellent smoothness and a good appearance, making it a suitable blasting material for precision blasting.

The present invention will be specifically described below with reference to Examples.

[Example 1] Polyamide resin (Kanebo ■, MC-112I), polycarbonate resin (Kijin Kasei ■, Panrai) -L-12
25) and 0: Mix polyphenylene sulfide resin (■Toprene, 1-Prene T-3) and alumina with an average particle size of 5 μm (Nippon Light Metal ■, A-31) in the proportions shown in Table 1, After melt-kneading in a twin-screw mixer, the mixture was pulverized to the average particle size shown in Table 1.

Next, after making these into a 30% water slurry by volume,
For IC lead frame packages, slurry pressure cuff kg/Cm2 for odd number slurries.
Nozzle injection amount: 12 d/min For even-numbered slurries, blasting treatment was performed for 30 seconds under the conditions of slurry pressure of 5 kg/cm 2 and nozzle injection amount of 8/min.

As a result, in all cases, the blasting material for wet blasting exhibited stable slurry uniformity without sedimentation and accumulation in the slurry regions.

In addition, the outer ring of the package after the blasting process is free from dents from the blasting material.
It is good with no whitening due to scratches, has excellent smoothness, and
The deburring effect was also excellent.

[Example 2] Polypropylene resin (manufactured by Mitsui Petrochemical Industries, Ltd., J740)
) and polystyrene resin (Dialex HF55, manufactured by Mitsubishi Monsanto Kasei ■) and alumina (manufactured by Nippon Light Metal ■, A14) with an average particle size of 50 μm were mixed in the proportions shown in Table 2, and after melting and kneading with a twin-screw kneader. The particles were ground to the average particle size shown in Table 2.

Next, after making these into a water slurry with a volume ratio of 30≠,
A blast projection process was performed on the IC lead frame pancage for 30 seconds under the conditions of a slurry pressure of 6 kg/cm2 and a nozzle injection rate of 106/min.

As a result, the uniformity of the slurry, the appearance of the package after the projection treatment, the smoothness, and the deburring effect were all good and excellent.

Claims (1)

[Claims] A projectile material for wet blasting characterized by comprising a granulated mixture of alumina and at least one thermoplastic resin selected from the group of polyamide, polycarbonate, polyphenylene sulfide, polyolefin and polystyrene.