JPH0138629B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to an improved structure for a coated abrasive paper. Generally, α-alumina sintered abrasive grains (abrasive material) are α
-It is made up of a collection of microscopic particles of alumina, α
This is an abrasive grain obtained by heating and sintering alumina or an α-alumina precursor, and is expected to have a self-generating effect in which the abrasive grain breaks into small pieces during the grinding process and generates new cutting edges. However, during grinding, the α-alumina sintered abrasive grains in coated abrasive paper may fall off in the early stages of use, or the abrasive grains themselves may fall off due to the original micro-fractures, especially in heavy grinding where a large grinding load is applied. Since the abrasive grains do not work properly and are missing, the abrasive grains do not work effectively and the abrasive cloth paper has the disadvantage of prematurely ending its life. The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks, and to provide high grinding performance that prevents alumina abrasive grains from falling off during grinding and effectively generates cutting edges by micro-fracture. , to provide abrasive cloth paper. Another object of the present invention is to provide a coated abrasive paper which has a protective layer on its surface that prevents alumina abrasive grains from falling off during the initial stage of grinding, and which has high durability in grinding. The present invention provides an abrasive coated paper in which abrasive grains are bonded to a base material via an adhesive layer, in which the abrasive grains are α-
It is a sintered abrasive grain mainly composed of alumina, and the adhesive layer is composed of an adhesive mainly composed of a thermosetting synthetic resin used in the well-known "resin bond" coated abrasive paper and an inorganic filler. The structure of the coated abrasive paper is made of a mixture of the above-mentioned abrasive grains and a protective layer is deposited on the abrasive grains and the adhesive layer. The substrates used are conventional coated abrasive substrates such as paper, cloth, vulcanized fiber, and cloth-paper composites. The mixture constituting the adhesive layer has an inorganic filler/synthetic resin ratio (weight ratio) of generally less than 1.5 in a known abrasive coated paper.
The composition of the mixture is related to coating properties, adhesion, heat resistance, etc. If there is a large amount of inorganic filler, the adhesion of the mixture will be low, but the compressive strength and heat resistance will be high. Considering the relationship, this will be done within the above range. The alumina sintered abrasive grains are α-
Fine particles of alumina (fine particles mainly composed of α-alumina or fine particles made of α-alumina precursor) are compression molded, fired at 1800°C for 15 hours to sinter, cooled, crushed, and averaged. It is classified into particle sizes of approximately 100 to 600μ (equivalent to #24 to #120 of the JIS abrasive grain standard). In the present invention, in order to compensate for the retention of alumina sintered abrasive grains with a protective layer, if the abrasive grain size is small, the effect of the protective layer cannot be obtained, so from a practical standpoint, the average grain size of the abrasive grains is approximately 100~600μ
The degree is selected. The protective layer is made of a mixture of synthetic resin and inorganic filler. Common thermosetting resins such as phenol-formaldehyde resin, polyester resin, polyurethane resin, melamine resin, urea resin, and epoxy resin are effective for this synthetic resin, but these curable resins and polyvinyl alcohol (PVA) , ethyl cellulose, polyacrylamide, vinyl acetate, vinyl chloride, latex, and other thermoplastic resins can also be used in combination. Inorganic fillers include calcium carbonate, cryolite, clay, graphite, silica,
Common inorganic materials used for coated abrasive paper such as calcium fluoride and potassium fluoride are used.
Depending on the use of the coated abrasive paper, plasticizers and lubricants may also be added. Note that the protective layer may contain voids. The inorganic filler preferably has an average particle size of about 80 μm or less in view of coating properties when forming coated abrasive paper and the average particle size of the abrasive grains used in the present invention. The ratio of the mixture to the protective layer is about 1.5 to 32.3.
A range of is preferred. If the ratio of the mixture in the protective layer is smaller than the above range, the protective layer will be difficult to wear during grinding, and the sintered α-alumina abrasive grains will not work sufficiently and the abrasive paper will last a long time. There is an inconvenience that the protective layer peels off and falls off at the beginning of grinding because it does not synchronize with the reduction of grains. The adhesive layer and the protective layer are dried and cured by aging (for example, at 135° C.), and the sintered abrasive grains are fixed to the base material by these layers. Next, test examples of the present invention will be explained. Test α-alumina fine powder with an average particle size of 2.0μ was heated at 1800℃.
After sintering for 15 hours, it is cooled, crushed, and JIS-R
- Alumina abrasive grains 1 classified into No. 60 according to the 6001 grain size standard
~1 was prepared. Then, liquid phenol-formaldehyde resin (Showa Union Synthetic
Manufactured by KK, "Resole resin BRL" with a solid content of approximately 75%
2867) and calcium carbonate powder in a weight ratio of 1:
150g wet weight of adhesive mixed in a ratio of 1
m ² was applied to form the primary adhesive layer 3. Next, 480 g/m ² of the prepared alumina abrasive grains 1 to 1 were applied electrostatically onto the primary adhesive layer 3 and dried in a dryer at 70 to 80° C. for about 2 hours. And alumina abrasive grain 1~1
On the primary adhesive layer 3, the same adhesive as the primary adhesive was applied as a secondary adhesive at a wet weight of 200 g/ ^m2 , and then pre-dried for 2 hours in a dryer at 70 to 80°C. A secondary adhesive layer 4 is formed, and then a protective layer 5 having a composition shown in Table 1 below is formed on the secondary adhesive layer 4.
After drying, it was applied at a weight of 150 g/m ² .

[Table] In the formulation shown in Table 1, the solid content weight ratio of the inorganic filler/synthetic resin adhesive is 3.3. Then, it was dried in an oven at 135° C. for 10 hours to obtain a test article abrasive cloth 6 having a protective layer 5 adhered thereto. The polishing cloth 6 thus formed has a width of 50 mm and a circumference of
Processed into a 2300mm endless belt. A square bar of carbon steel S45C (cross section 25 x 25 mm) was used as the work material, grinding load 8 kg, belt circumferential speed 1600 m/min, rubber hardness.
The grindability of this endless belt-like abrasive cloth was investigated using a constant load grinder with a 70° contact wheel and a land ratio of 1:1. As a result, carbon steel
The amount of grinding for 5 minutes on the S45C square bar was 320g. After use, the abrasive cloth 6 of this test product had little damage to the abrasive surface and no abrasive surfaces were formed on the abrasive grains, so when grinding was continued for an additional 5 minutes, a grinding amount of 160 g was obtained, and the workpiece No burn occurred on the carbon steel material. Next, as a control for the test product abrasive cloth 6, an abrasive cloth 7 having the same structure as the test product but without a protective layer was formed and compared with the control product (see Fig. 2.
Components that are the same as the abrasive cloth 6 of the test product are indicated by the same numbers). This control product, abrasive cloth 7, was processed into an endless belt in the same manner as the abrasive cloth 6 described above, and its grindability was examined under the same conditions as the test product, and the amount of grinding of a carbon steel S45C square bar in 5 minutes was 212 g. It was hot. After use, the belt showed some damage to the abrasive material, but no burning occurred on the surface of the work material. It was observed that the abrasive cloth's abrasive power and durability were significantly improved in the test product compared to the control product due to the formation of the protective layer. Test Sintered abrasive grains (SG abrasive material) manufactured by Kennekotsu Co., Ltd. in the United States
A test abrasive cloth (not shown) with a protective layer was made using a particle size standard No. 36. The protective layer has the composition shown in Table 2 and has a dry weight of 300%.
g/m ² was applied, dried for 3 hours in a dryer at 40°C, and then left in a room at 25°C and 65% relative humidity for 48 hours to cure the urethane resin with moisture.

[Table] In the formulation shown in Table 2, the solid content weight ratio of the inorganic filler/synthetic resin adhesive is 1.5. This abrasive cloth was processed into an endless belt, and when a square bar of carbon steel S45C was subjected to a grinding test under the same conditions as the test product, the amount of grinding in 5 minutes was 1180 g. After use, there was hardly any loss or shedding of the abrasive material on the belt, and the protective layer was well regenerated along with the main action of the abrasive material. Next, as a control for the abrasive cloth of the test product, an abrasive cloth (control product) with the same structure as the test product but without a protective layer was formed, and this was processed into an endless belt and subjected to the same conditions as the test product. When examining the grindability, the amount of grinding of a carbon steel S45C square bar in 5 minutes was 820g.
It was hot. Many of the abrasive grains on the belt after use of the control product were missing, but no worn surfaces were formed at the tips of the abrasive grains. Test A square bar of stainless steel SUS304 (with a cross section of 25 x 25 mm) was ground with a grinding load of 20 kg using the new abrasive belt of the test product. The grinding machine used was the same as in the test. The amount of grinding of the stainless steel square rod in 5 minutes was 1100 g, and the abrasive grains of the abrasive belt after use showed good self-growth, and the wear of the protective layer was also good. On the other hand, when a square bar made of stainless steel SUS304 was similarly ground with a grinding load of 20 kg using a new abrasive belt as a control product, the amount of grinding of the square bar of stainless steel in 5 minutes was 730 g. The abrasive grains were severely damaged. Test Alumina abrasive grains manufactured by the melting method (melted α-alumina fine particles, cooled, crushed and classified)
An abrasive cloth of the test article treated in the same manner as in the above test using No. 60 and having a protective layer on the surface (not shown)
I made it. Next, this abrasive cloth was processed into an endless abrasive belt made of carbon steel S45C 25×25
When a grinding test was carried out on a work material of mm in diameter under the same conditions as the test, the amount of grinding for 5 minutes was 197 g.
A worn surface was formed at the tip of the abrasive grain, and the work material was also burnt. Next, as a control product for the test product, an abrasive cloth (not shown) with the same structure as the test product but without a protective layer.
is formed and processed into an endless abrasive belt,
When the grindability of a square bar made of carbon steel S45C was examined under the same conditions as in the test, the amount of grinding in 5 minutes was 185 g. After use, some of the abrasive grains on the belt were shedding (falling off), but there was a worn surface (a plateau-shaped part where the abrasive material had worn down) at the tip of the abrasive grains, which were in strong contact with the adhesive. The cut surface of the work material was burnt. In this test product and the control product, no self-growth effect like that of sintered abrasive grains was observed from the alumina abrasive grains produced by the fusion process, and almost no effect of the protective layer was observed. Since the coated abrasive paper of the present invention provides a protective layer on the abrasive grains adhered to the base material, the alumina abrasive grains are prevented from falling off during grinding. In other words, the protective layer has an appropriately determined ratio of inorganic filler/thermosetting synthetic resin, and is gradually reduced during polishing, so it does not interfere with polishing and retains abrasive grains well. It has the effect of making something happen. Therefore, according to the coated abrasive paper of the present invention, the retention of the abrasive material is good, and the abrasive grains during grinding do not fall off or become chipped without being micro-fractured, and the grindability of the abrasive grains is improved. is enhanced. Furthermore, since the abrasive grains of the present invention are sintered abrasive grains containing α-alumina as a main component, new cutting edges are generated while being micro-fractured during the grinding process, thereby improving the grindability.

[Brief explanation of drawings]

The drawings show an abrasive cloth of a test example of the present invention; FIG. 1 is an enlarged sectional view showing the structure of the test product, and FIG. 2 is an enlarged sectional view showing the structure of a control product. DESCRIPTION OF SYMBOLS 1... Alumina abrasive grain, 2... Drill cloth, 3... Primary adhesive layer, 4... Secondary adhesive layer, 5... Protective layer, 6... Abrasive cloth.

Claims (1)

[Claims] 1. A coated abrasive paper in which abrasive grains are adhered to a base material via an adhesive layer, wherein the abrasive grains are sintered abrasive grains containing α-alumina as a main component and having an average particle diameter of about 100 to 600 μm, A protective layer is applied on the abrasive grains and the adhesive layer, and the protective layer is made of synthetic resin and has an average particle size of about 80 μm.
A structure of a coated abrasive paper comprising a mixture of the following inorganic fillers and having an inorganic filler/synthetic resin solid content weight ratio of about 1.5 to 32.3.