JPS6288568A - Abrasive - Google Patents

Abstract

PURPOSE:To stabilize the performance of abrasives for a long time of period by constituting the abrasive substantially from hollow ceramic beads consisting of silica and alumina and synthetic resin. CONSTITUTION:Hollow ceramic beads formed substantially of spherical substance (outer diameter: 0.5-20mu) consisting of silica and alumina and having in the interior respectively cavities having the outer diameter of 1/4-1/2 of the outer diameter are dispersed in synthetic resin. The amount of mixed spherical substances is preferably 10-30wt%. Then, said substances are crushed to provide a desired grain size distribution of abrasives by sorting. This hollow ceramic bead has about 7 Mohs' hardness and about same polishing force as glass bead, while the compressive strength is about 20 times that of glass bead so that an amount of beads broken in use is very few and the abrasives can be used with the stable performance for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an abrasive material, and more particularly, to an abrasive material having stable abrasive performance over a long period of time.

<Prior Art and Problems> Conventionally, commonly used hard abrasives include carborundum, emery, alundum, white alundum, green carborundum, sand stone, silica sand, tubaculite, heptadium, iron powder, There were glass peas etc. However, since glass beads have an irregular shape, the surface of the polished object is highly uneven and has sharp convexities, and the gloss of the polished surface is significantly reduced. I had done it. Further, when plating or soldering is performed after polishing, the presence of sharp convex portions may cause problems such as a decrease in plating gloss and deterioration of solder wettability. On the other hand, since glass beads are spherical, the above-mentioned phenomenon does not occur and a semi-glossy polished surface can be obtained, and furthermore, plating and soldering do not cause any inconvenience on work vehicles.

Glass beads occupy a unique position among hard abrasive materials because of their semi-gloss polished surface and ease of plating and soldering in the post-processing process, and are used in many applications. however,
Glass peas also have the following drawbacks. That is, if a strong impact is applied, for example by blasting under high pressure, it has the disadvantage that it is easily destroyed due to its brittleness. After glass beads are broken, they become shaped with edges, so if a large number of glass beads are broken, the unique polishing performance due to their spherical shape is also lost. That is, if the glass beads break during use, the polishing performance changes accordingly.

In recent years, glass beads have been used as an abrasive for deburring epoxy molding materials such as ICs due to their moderate hardness and ease of plating and soldering in post-processes, but the same problem occurs in this case as well. There is a point.

When deburring mold materials such as ICs, if the surface of the molded product is damaged, it not only spoils the aesthetics but also causes serious problems such as moisture seeping through the damaged area and negatively affecting the reliability of the semiconductor element. However, when glass beads are used as an abrasive, there is a problem in that the glass beads become irregular in shape as well as being destroyed, resulting in severe damage to the mold surface. Furthermore, there is another problem in that fragments of the broken glass beads stick to the lead frame, causing poor appearance during plating and soldering in subsequent steps, and causing corrosion of the lead frame.

As mentioned above, when glass beads are used to remove burrs from molded products such as ICs, the initial performance is good, but after being broken, the glass beads become irregularly shaped, so the characteristics of glass beads are will be lost. ``In order to solve this drawback, it has been desired to develop an abrasive that has the same performance as glass beads and can be used for a long period of time.

Means for Solving the Problems> As a result of extensive research by the present inventors to solve the above problems, we have found that hollow ceramic beads consisting essentially of silica and alumina are useful. See ℃
・Achieved the present invention.

The hollow ceramic beads referred to in the present invention are essentially
A spherical substance made of silica and alumina that has a cavity with a diameter of 1/4 to 1/2 of the outer diameter. Generally, the outer diameter is 0.5 to 20μ, such as Maruwa It is something like ZEEO8PHE-RES from Biochemical ■. The ratio of silica and alumina is usually 99:1 to 99:1 by weight.
The ratio is 1:99, preferably 95:/-5:95.

These hollow ceramic beads are characterized by extremely high compressive strength. Its compressive strength is about 4000 kg/ctl for particles with a particle size of 2μ, which is about 20 times stronger than glass beads of the same particle size. Therefore, the amount crushed during use is very small. Since the aforementioned problem with glass beads is caused by the glass beads being crushed during plastination, the use of hollow ceramic beads solves this problem. Further, the hardness of these hollow ceramic beads is approximately 7 on the Mohs scale, which is the same as that of glass beads. Therefore, a polishing force comparable to that of glass beads can be obtained.

When used as an abrasive material in the form of hollow ceramic beads, if the particle size is small, the abrasive material may back up in the hopper, which may be inconvenient for work.

In order to solve this problem, it is possible to obtain an abrasive material with a desired particle size distribution by dispersing it in a resin in the form of hollow ceramic beads, then crushing it, and then classifying it. The synthetic resin used in this case may be a thermoplastic resin such as polystyrene, polyvinyl chloride, polyacetal, polycarbonate, polyethylene terephthalate, or nylon, or a thermoplastic resin such as unsaturated polyester, melamine resin, phenolic resin, epoxy resin, or urea resin. A cured resin may be used (and if necessary, these resins may be mixed and used.Among them, polyacetal resin and unsaturated polyester resin are preferable in terms of ease of manufacture, physical properties, and cost. Depending on the situation, surfactants, dispersants, antisettling agents, antistatic agents, and various coupling agents may be added.

When making an abrasive material by dispersing hollow ceramic beads in a synthetic resin, if the amount of the abrasive material mixed is small, the abrasive power becomes low, which is not preferable. In addition, if the mixing amount is too large, the binder effect of the resin will be low (this will cause the synthetic resin part to easily break down, the abrasive will quickly become pulverized, and the abrasive will tend to back up in the hopper (which is undesirable). .

When using unsaturated polyester resin or polyacetal resin, the amount of hollow ceramic beads mixed is 100% of the abrasive material.
It is 5 to 50 parts by weight, preferably 10 to 30 parts by weight.

In order to manufacture an abrasive material in which hollow ceramic beads are mixed into a synthetic resin, the following procedure may be used.0 If the synthetic resin is a thermosetting resin, for example, a disburr, three-roll mill, sand mill, ball mill, After dispersing and mixing the hollow ceramic beads into synthetic resin using a dispersion device such as a hot roll, the resin is cured by a normal method, and the resulting cured product is coarsely crushed using a crusher, hammer, etc., and then crushed using various types of crushers. For example, it may be finely pulverized using a hammer mill, a disc pulverizer, an articulated pulverizer, or the like.

When the synthetic resin is a thermoplastic resin, dispersion is preferably carried out using heated rolls. When pulverizing, freezing pulverization may be carried out if necessary.

The abrasive thus obtained is subjected to operations such as classification, if necessary, to obtain a suitable particle size distribution before use. The particle size usually ranges from 0.05 to 1.0 m.

Effect> Since the abrasive material of the present invention uses hollow ceramic beads with extremely high compressive strength, it is less likely to fracture compared to abrasive materials that use conventional glass beads, and therefore has stable performance over a long period of time. has.

<Example> Next, the present invention will be explained in detail with reference to Examples and Comparative Examples.

Although the Examples and Comparative Examples were evaluated using wet blasting, the present invention naturally provides an abrasive material that is useful in conventional polishing methods such as dry blasting, impeller set, and barrel polishing. . All parts and percentages in the examples are based on weight unless otherwise specified.

Comparative Example 1 1.5 mol of isophthalic acid, 3.0 mol of maleic anhydride, 3.5 mol of propylene gellicol, and 1.45 mol of ethylene glycol were added and kept at 180 to 210°C until the acid value reached 35. Made it react. The obtained polyester was dissolved in an equal weight of styrene to obtain unsaturated polyester 1.

1100 parts of unsaturated polyester, 0.5 parts of 6% cobalt naphthenate, 5 parts of methyl ethyl ketone peroxide
After adding 1 part of the 5% product and mixing well, the mixture was left at room temperature for 20 hours, and then heated at 100° C. for 3 hours.

The obtained cured product was coarsely crushed using a crusher, and then further finely crushed using an impact crusher. By classification, 60 mesh passes and 80 mesh passes were separated to obtain abrasive material 1.

Comparative Example 2 A pellet was produced by extruding a polyacetal resin using an extruder and cutting it. This was frozen in liquid nitrogen and pulverized, and then classified to obtain abrasive material 2 with 60 mesh passes and 80 mesh passes.

Comparative Example 3 An abrasive material was obtained in the same manner as in Comparative Example 1 by mixing unsaturated polyester 1 and glass beads having an average particle size of 10 μm. Abrasives 3 to 5 were obtained by changing the amount of glass beads in the abrasive to 20.40.60 parts.

Comparative Example 4 An abrasive was obtained in the same manner as in Comparative Example 2 by mixing with polyacetal resin using a heated roll made of glass beads having an average particle size of 10 μm. The amount of glass beads in the abrasive is 20,40.6
Abrasive materials 6 to 8 were obtained by changing the amount to 0 part.

Example 1 An abrasive material was obtained in the same manner as in Comparative Example 1 by mixing unsaturated polyester 1 and silica-alumina hollow ceramic beads having an average particle size of 10 μm and a hollow average inner diameter of about 3.3 μm.

The amount of hollow ceramic beads in the abrasive material is 5.10.2
Abrasive materials 9 to 13 were obtained by changing the amount to 0.40160 parts.

Example 2 A polyacetal resin and the hollow ceramic beads used in Example 1 were mixed using a heated roll, and the same procedure as in Comparative Example 2 was carried out to obtain an abrasive material. Abrasive material 1 by changing the amount of hollow ceramic beads in the abrasive material to 5.10.20.40.60 parts
4 to 18 were obtained.

Evaluation example Plast tests were conducted on abrasives 1 to 18.

The plast test was conducted using a liquid honing machine LH-5 manufactured by Fuji Seiki Seisakusho Co., Ltd. Slurry concentration 40
%, projection pressure 4kg/cd, projection distance 5crIL
Each chip of C was blasted for 1 second, and the deburring performance and mold roughness were evaluated. Evaluation was performed on a 10-point scale, with 10 being the best, 5 being practically acceptable, and 1 being the worst.

The results are shown in Table-1.

Furthermore, under the same conditions, the acrylic plate was plated for a certain period of time, the weight loss was measured, and the time required for the value to become 1/2 of the initial value was determined. This is a guideline for the usable time of the abrasive. This is also shown in Table 1 as life.

It should be noted that no weight loss was observed in Abrasive Material 2, so the life was not measured.

Reference evaluation example Under the same blasting conditions as the previous example, the average particle size was 10 as an abrasive.
An iron plate was plastered using 325 μm glass beads. Samples were taken 25,50,75,100 hours after the start, and the degree of crushing of the particles was evaluated by checking the weight percentage of 325 methion.

A similar experiment was conducted using the 325 mesh hollow ceramic beads used in Example 1 instead of the glass beads.

The results are shown in Table-2.

Table 2 <Effects of the Invention> As can be seen from the implementation column, since the abrasive material of the present invention uses hollow ceramic beads, it has the same level of polishing power as the abrasive material using glass beads. However, it can be used for a very long time.

Claims (5)

[Claims] (1) An abrasive material whose constituent components are hollow ceramic beads consisting essentially of silica and alumina. (2) The abrasive material according to claim 1, which contains a synthetic resin as one of the other components. (3) The abrasive material according to claim 2, wherein the content of hollow ceramic beads is 5 to 50 parts by weight based on 100 parts by weight of the abrasive material. (4) The abrasive material according to claim 2 or 3, wherein the synthetic resin is an unsaturated polyester resin. (5) The abrasive material according to claim 2 or 3, wherein the synthetic resin is a polyacetal resin.