JPH0392255A - Polishing sheet and manufacture thereof - Google Patents

Abstract

PURPOSE:To increase polishing pressure by forming a polishing layer, which is constituted by mixing abrasive particles and filler particles in a binder adhesive, at least on one side of a base. CONSTITUTION:At least on one side of a base 4, polishing particles 1 and at least one kind of filler particles 7 are mixed. And further thereto, a binder adhesive 2 is mixed, and they are evenly applied to form a desired polishing layer 3.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an abrasive sheet that is useful for precision finishing polishing of the surfaces of machines, devices, parts, and other general objects, and has good abrasive performance, and a method for manufacturing the same.

[Conventional technology]

Conventional abrasive sheets, as shown in FIG. See Patent Nos. 2,755,807 and 3,868,325). Other conventional abrasive sheets, as shown in FIG. 7, are made by mixing two types of abrasive particles with different hardnesses, in which the particle size of the soft abrasive particles 1a is increased, and the particle size of the hard abrasive particles 1b is increased. This sheet has a reduced particle size and can remove foreign matter attached to the surface of the material 6 to be polished, and can polish protrusions on the surface of the material 6 to be polished. (See U.S. Pat. No. 4,138,229).Also, as a method for manufacturing abrasive tape, static electricity is used to coat the binder in order to efficiently attach a small amount of abrasive particles to the substrate. There was also a method of bonding a single layer of abrasive particles to a substrate with vertical alignment (ELECTROSTAT
ICS ＾． D. by Moore, Double
ay&Cos+pany. Inc. , New
York) *

[Problem to be solved by the invention]

However, as shown in Figure 6, the manufacturing method of an abrasive sheet in which the layer of abrasive particles is thin and formed into one layer (or two layers) has poor flatness accuracy due to variations in the particle size of the abrasive particles5. In addition, in the polishing sheet I method of mixing two types of abrasive particles with greatly different particle sizes as shown in Figure 7, the particles pass through the gaps between the large particle particles. A so-called segregation phenomenon occurs in which particles with small diameters gather downward.Therefore, this method has the problem that it is difficult to uniformly disperse and coat two types of abrasive particles with different particle sizes. The conventional polishing sheet manufactured in
As can be seen in the figure and FIG. 7, only the particles 1a with a large particle size came into contact with the material to be polished 6 under a large pressure, and the particles 1b with a small particle size did not come into contact with the surface of the material to be polished 6. Since these abrasive particles are generally hard and the material to be polished is also hard, if the polishing pressure is increased during polishing, the abrasive particles will immerse into the binder adhesive or plastic substrate more than the material to be polished. However, it was not possible to improve the polishing performance. As described above, the polishing performance of conventional polishing sheets was low, and the finishing accuracy of the surface of the material to be polished was also poor. SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and it is an object of the present invention to provide a polishing sheet that is relatively simple to manufacture, has good planar accuracy, and has good polishing performance, and a method for manufacturing the same.

[Means to solve the problem]

The abrasive sheet of the present invention has, on at least one side of a substrate, an abrasive layer comprising a Pai Goo adhesive mixed with abrasive particles and at least one type of filler particles. Here, the thickness of the iiJf polishing layer is set so that the plane accuracy of the polishing layer can be increased, and the polishing particles on the surface can be supported from below by a plurality of particles, and the total projected contact area can be increased. It is desirable that the diameter be at least three times the average particle diameter of the material particles. Further, when the weight ratio of the abrasive particles constituting the polishing layer is χ, and the weight ratio of the filler particles is 1-χ, χ=o. oi～0
．． It is desirable that the average particle size of the two be approximately the same. The method for manufacturing an abrasive sheet of the present invention is the method for manufacturing the abrasive sheet described above, in which at least one side of a substrate is
mixing abrasive particles and at least one type of filler particles;
This method of manufacturing an abrasive sheet is further characterized by mixing a binder adhesive and uniformly applying the mixture. In order to improve the flatness of the polishing layer, it is desirable to uniformly apply a slurry containing abrasive particles, filler particles, and binder adhesive onto the substrate sheet using a roller or blade.

【Example】

Preferred embodiments of the present invention will be described with reference to the drawings. Figure 1 shows a cross section of the polishing sheet of the present invention. In this polishing sheet, a thick polishing layer 3 consisting of four layers of abrasive particles is formed on a substrate 4. On this point, 1 to 2
This is in contrast to the conventional polishing layer formed on the polishing layer. Here, abrasive particles 1 and filler particles 7 are mixed in the abrasive mm3 via a binder adhesive 3. In addition, in the example, an example of an abrasive layer with a layer of abrasive particles of 41 was shown, but this layer has at least three layers,
Practically speaking, 4 to 5 layers or more is desirable. There are two main reasons why the polishing layer was formed so thick as described below. First of all, when the abrasive particles are a single layer, the variation in the particle size of the particles as shown in Figure 6 directly deteriorates the flatness accuracy. In addition, when the abrasive particles have two layers, as shown in Figures 3a and 3b, there is a case where the particles form an orthographically arranged layer (Fig. 3a), and a case where the particles form a squarely arranged layer (Fig. 3b). ), a step 10 occurs on the surface of the polishing layer, making it difficult to improve the plane accuracy. Therefore, adjusting the thickness of the abrasive layer to at least three or more abrasive particle layers, ideally four or more layers is a condition for producing an abrasive sheet with good planar accuracy. Secondly, it is necessary to thicken the polishing layer (abrasive particle layer) in order to increase the polishing force. The reason for this will be explained with reference to Figures 4 and 5. Figure 4 shows the polishing layer. The upper part is the material 6 to be polished, and the lower part is the polishing sheet.The abrasive particles 1 are sufficiently harder than the material 6 to be polished and the binder adhesive 2, and the material 6 to be polished is It is generally relatively harder than binder adhesive 2.
As shown in FIG. 4, the projected contact area A. (The shaded area in FIG. 4) is proportional to the vertical force Fl (polishing pressure) applied to the surface of the material 6 to be polished through the abrasive particles 1, and inversely proportional to the surface yield pressure P+s of the material to be polished, so that It can be expressed. Here, the surface yield pressure Pa is a force F1 perpendicular to the surface of the material to be polished 6, and when that force F,l exceeds P, the material to be polished 6 yields, and the abrasive particles are absorbed into the material to be polished. 6 and the projected contact surface $1A. It is thought that the pressure increases and equilibrium is reached when the pressure reaches PI1. This Pa is a constant depending on the material. On the other hand, between the abrasive particles 1 and the binder adhesive 2,
You can think of a similar idea. That is, binder adhesive 2
Projected contact surface WIAb of abrasive particle 1 in contact with WIAb (
4) is proportional to the vertical force Fw applied to the surface of the binder adhesive 2 through the abrasive particles l, and is inversely proportional to the surface yield pressure P1 of the binder adhesive, so it can be expressed as follows. Force F. applied to the material to be polished 6 and the binder adhesive 2 through the abrasive particles 1. are the same, so
By eliminating F. from equations (1) and (2), we get the following (3
) formula is obtained. A. Pa = Ab Pa (3) In most cases, the material to be polished is hard, and its surface yield pressure Pm is considered to be 102 to 105 times the surface yield pressure P1 of the binder adhesive. Therefore, from equation (3), the projected contact area of the abrasive particles to the material to be polished is A. is the projected contact surface W of the binder adhesive
It must be less than 101 to 10-2 times that of IAb.
FIG. 4 shows Aw and A. Although it is drawn relatively large compared to A. is very small. When used, the abrasive particles will immerse into the binder adhesive, destroying the abrasive layer. Therefore, in order to use the polishing seal 1 without destroying the polishing sheet, Ab must be made sufficiently large since (Pm'/Pa) is a constant that is determined once the material is determined. If Ab, that is, the projected contact area of the particles that support the force F, can be increased, the polishing layer will not be destroyed even if a polishing pressure that increases Am is applied.
If the polishing pressure can be increased as Ab increases, the abrasive particles will penetrate deeper into the material to be polished, leading to improvement in polishing performance. By the way, when several layers of abrasive particles are stacked to form a thick abrasive layer, as shown in FIG. Supported by a plurality of abrasive particles 1° in the layer, which in turn are supported by a plurality of abrasive particles l' in the second layer, a plurality of abrasive particles 11 in the third M, and further abrasive particles 1' (we will call this the Ishigaki effect). Therefore, the total projected contact area A1 of the particles of the second layer supporting one abrasive particle of the first layer (this area A The total projected contact area of each of the plurality of abrasive particles in A. is several times the projected contact area A. of the particles in the case of the first layer. When the polishing layer is thickened by stacking the polishing layers, the total projected contact area of each layer Ab'', Ab'''
...is dramatically increased compared to the projected contact area of conventional polishing sheets. In this way, the abrasive layer is formed thickly so that at least three or more layers of abrasive particle waste are formed;
It was found that a stone wall effect appeared, and as a result, the projected contact area supporting the polishing pressure could be significantly increased, and the polishing pressure could be increased accordingly, thereby improving polishing performance. Note that even if the first layer is manufactured with good surface precision, the number of abrasive particles in the first layer that actually come into contact with the substance to be polished is only 1/100 to iooo of all the particles lined up in the first layer. It has been experimentally determined that the following is true. Therefore, even if a plurality of abrasive particle layers are formed, the abrasive particles in the second layer and below rarely support the abrasive particles in the first layer redundantly.
As shown in Figure 5, it is safe to consider a pyramid-like stone wall structure for each abrasive particle in the first layer. On the other hand, in conventional abrasive sheet manufacturing, the only particles directly involved in polishing are the abrasive particles present on the surface, so in order to reduce costs, the abrasive particle layer is attached to a substrate coated with a binder using static electricity. We tried to make it as single layer as possible by attaching abrasive particles (^. D. Moore). However, the second layer supports the abrasive particles of the first layer on the surface of the thick abrasive layer. Third,・
...The stone wall particles in the layer do not need to be as hard as the abrasive particles,
As long as it is harder than the binder adhesive and has the same particle size as the abrasive particles, at least one type of inexpensive crystal or glass particles or natural mineral particles can be used as a filler for stone walls. Therefore, even if the polishing layer is formed thickly, the manufacturing cost of the polishing sheet does not increase. For the above reasons, the abrasive sheet of the present invention was formed to have at least three abrasive particle layers. Such a polishing layer improves the plane accuracy and polishing performance of the polishing layer, and therefore reduces the polishing time using conventional polishing sheets by 20 to 40%, and does not increase manufacturing costs. The specific substances of the abrasive, filler, and binder adhesive will be explained in the manufacturing method below.゛First, the abrasive particles to be adhered to the abrasive sheet are heated to a temperature of 10
Heat at 0 to 150°C for 1 hour or more to remove moisture on the particle surface. Similarly, filler particles are
Heat for more than an hour to remove moisture on the surface of the particles. As the abrasive particles, aluminum oxide, chromium oxide, silicon carbide, iron oxide, etc. with a diameter of 0.1 uz to 40p are used. In addition, the filler particles have a diameter of 0.1
~40νl, in addition to fine particles of natural minerals and glass such as kaolin, natural barium sulfide, Bengara, and agalmatolite, at least one of simple crystals such as silicon dioxide, zirconium oxide, iron oxide, titanium oxide, and calcium carbonate. Use different types of filler particles. The mixing ratio of the abrasive particles and the filler particles is expressed as follows:
= 0.01 to χ = o,9, and when the average particle diameters of both are approximately equal, the two can be easily mixed uniformly. Mix uniformly mixed abrasive particles and filler particles with binder adhesive. The binder adhesive is preferably a polyester resin adhesive, but is not limited thereto. For example, as abrasive particles, 0.10 chromium oxide with an average particle size of 3 μl and 0.9 kg of filler particles with an average particle size of 3 IIJ are uniformly mixed, and this and 1 kg of saturated polyester resin are mixed uniformly. Mix. To this mixture, add 7.5 g of incyanate curing agent and a mixed solvent of toluene, xylene, ethyl acetate, and methyl ethyl ketone and stir to form a slurry with a viscosity of 500 to 100 cp. This slurry is uniformly applied onto a polyester substrate sheet having a thickness of 16 II to 150 pi. While conventional abrasive sheets were designed to be applied as thinly as possible, in the present invention, the thickness of the thriller applied was at least 3 times the average particle size of the abrasive and filler to achieve a stone wall effect.
For example, in the case of particles with an average particle size of 3 IJl, 10
It is recommended to apply it to a thickness of 1m to 15pm. When applying, in order to improve the surface precision of the polishing layer,
A roller 8 or a blade 9 is used as shown in Figure 3a or Figure 3b. The sheet uniformly coated with slurry in this way enters the first dryer kept at a temperature of 40°C to 90°C, and then enters the second dryer kept at a temperature of 100°C to 110°C, where the slurry is removed. The solvent is evaporated.
After that, through a curing process at a temperature of 40℃ to 180℃ for 5 hours to 12 hours, the flat surface accuracy shown in Figure 1 was obtained.
The production of a polishing sheet with excellent polishing performance is completed. So-1 In the polishing sheet according to the present invention, since the polishing layer is formed thickly, the planar accuracy of the polishing layer is improved. The polishing sheet exhibits a stone wall effect, which makes it possible to increase the polishing pressure and thus obtain high polishing performance. Furthermore, the filler particles constituting the polishing layer of the polishing sheet can be made of inexpensive materials such as natural minerals or fine glass particles, so even if the thickness of the polishing layer is increased, the cost of the polishing sheet will not increase. Further, by carrying out the method for producing an abrasive sheet of the present invention, it is possible to form an abrasive layer with good planar accuracy, and also to produce an abrasive sheet with excellent abrasive performance as described above in which a stone wall effect appears in the abrasive layer. Can be done.

[Brief explanation of drawings]

Figure 1 shows a partial sectional view of the polishing sheet of the present invention. Figure 2a shows the step of flattening the polishing layer with a roller in the method of manufacturing the polishing sheet of the present invention, and Figure 2b shows the step of flattening the polishing layer with a blade in the method of manufacturing the polishing sheet of the present invention. show. Fig. 3a shows a schematic cross-sectional view of the abrasive sheet when the abrasive particles form a diagonally arranged layer, and Fig. 3b shows a schematic cross-sectional view of the abrasive sheet when the abrasive particles form a tetragonally arranged layer. is shown. Figure 4 is a perspective view of the polishing sheet in contact with the material to be polished. FIG. 5 is a perspective view of the abrasive sheet of the present invention in which the stone wall effect appears. Figure 6 shows a schematic cross-sectional view of a conventional polishing sheet in contact with a material to be polished. FIG. 7 shows a schematic cross-sectional view of a polishing sheet having two types of abrasive particles of different sizes in contact with a material to be polished.

[Explanation of main symbols]

1... Abrasive particles 2... Binder adhesive 3... Abrasive layer 4... Substrate sheet 7...
・Filling material

Claims (1)

[Claims] 1. An abrasive sheet having, on at least one side of a substrate, an abrasive layer comprising a mixture of abrasive particles and filler particles in a binder adhesive. 2. The polishing sheet according to claim 1, wherein the thickness of the polishing layer is at least three times or more the average particle diameter of the abrasive particles. 3. The abrasive sheet according to claim 1, wherein χ=0.01 to 0.9, where the weight ratio of the abrasive particles is χ and the weight ratio of the filler particles is 1-χ.
Polishing sheets with approximately the same average particle size. 4. A method for producing an abrasive sheet, which comprises mixing abrasive particles and at least one type of filler particles on at least one side of a substrate, and further mixing and uniformly applying a binder adhesive thereto. 5. The manufacturing method according to claim 4, wherein the abrasive layer is coated so that the thickness thereof is at least three times the average particle diameter of the abrasive particles. 6. The manufacturing method according to claim 4, wherein χ=0.01 to 0.9, where the weight ratio of the abrasive particles is χ and the weight ratio of the filler particles is 1-χ.
A method in which the average particle size of both is approximately the same.