JP2003266298A - Sheet for polishing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet for polishing capable of achieving high polishing speed and excellent productivity. <P>SOLUTION: This sheet for polishing containing three-dimensional slip nonwoven fabric and a resin in its inside is constituted in such a way that fibers constituting the nonwoven fabric are composed substantially of polystyrene and polyamide, a weight ratio of polystyrene to polyamide is in the range of 1:99 to 90:10, polyamide forms a continuous layer in the fibers, and a surface of fiber is composed substantially of polyamide. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polishing sheet having an excellent polishing rate.

[0002]

2. Description of the Related Art For glass parts such as cathode ray tubes and electronic parts such as hard disks, it is indispensable to polish the surface of the parts during the manufacturing process. The polishing sheet used at this time is strongly required to have an improved polishing rate so that the target surface state can be quickly reached in response to the demand for productivity improvement accompanying the recent progress in price reduction.

As a polishing sheet for such polishing, a porous and highly rigid plate is used which is obtained by impregnating a nonwoven fabric mainly made of polyamide or a polyamide hollow fiber with a polyurethane resin. Although this has performance sufficient for practical use, it is as described above that further improvement in polishing rate is required.

Further, since the sheet having such a constitution is originally a material having a high flexibility, in order to use it as a polishing sheet, a foamed cell of impregnated polyurethane resin is secondarily impregnated with a hard resin, The performance as a grinding sheet is obtained by increasing the density and elastic modulus of the sheet. However, this method has a problem that not only the productivity of the polishing sheet is low but also the productivity is not so high as a whole because the voids in the sheet are less likely to cause clogging and shorten the life.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a polishing sheet having a high polishing rate and excellent productivity.

[0006]

Means for Solving the Problems As a result of studies to achieve the above object, if a fiber made of a polyamide / polystyrene mixture in which polyamide forms a continuous layer is used as a fiber for a non-woven fabric, the sheet itself is The inventors have found that the rigidity is improved and the polishing rate can be improved, and the present invention has been completed.

That is, according to the present invention, in a three-dimensional entangled nonwoven fabric and a sheet containing a resin therein, the fibers constituting the nonwoven fabric consist essentially of polystyrene and polyamide, and the weight ratio of the polystyrene and the polyamide is 1:
It is in the range of 99 to 90:10, the polyamide inside the fiber forms a continuous layer, and the surface of the fiber is substantially made of polyamide. And, preferably, the fiber is a polishing sheet made of sea-island type fibers having polyamide as a sea component and polystyrene as an island component, and further, the fibers are polishing sheets made of hollow fibers. The resin contained in the three-dimensional entangled nonwoven fabric that constitutes the polishing sheet of the present invention is preferably polyurethane.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below.

In the present invention, the fibers constituting the three-dimensional entangled nonwoven fabric consist essentially of polystyrene and polyamide,
The weight ratio of the polystyrene to the polyamide is 1:99 to 9
The range is 0:10. And, a fiber in which the polyamide forms a continuous layer in the fiber means a fiber in a state in which the fiber is not cut in the longitudinal direction even when the fiber is dipped in a good solvent of polystyrene such as toluene. Specific examples thereof include sea-island type fibers in which polyamide is a sea component, and fibers having a structure generally called a co-continuous structure or a multi-layer laminated type in which both polyamide and polystyrene are continuous layers. When the polyamide is discontinuous, fiber breakage frequently occurs during use as an abrasive sheet, and the generated lint causes defects on the surface to be abraded, which makes it unsuitable as an abrasive sheet. The fiber of the above requires that the polyamide is a continuous layer.

Furthermore, the surface of the fiber must be substantially coated with polyamide. When the surface is covered with polystyrene, the wetting by the polishing liquid will be poor, so that the unevenness of polishing of the material to be polished is likely to occur, and the fibers are apt to stick due to friction during polishing. There is a problem that defects easily occur on the polished surface. The fact that the fiber surface is substantially made of polyamide is determined by whether or not fusion of the fibers occurs due to melting of polystyrene when the fibers constituting the nonwoven fabric are stacked and pressed at 100 ° C. 1
It does not mean that it consists of 00% polyamide.

The fibers constituting the present fiber consist essentially of polystyrene and polyamide, and it is essential that the weight ratio of the polystyrene and the polyamide is in the range of 1:99 to 90:10, preferably polystyrene 2: 98-3
0:70, more preferably polystyrene 3: 97-6
0:40, optimally polystyrene 4:96 to 45:55
Consists of. When the ratio of polystyrene is less than 1, a difference from that in which polystyrene is not present is not substantially found, and it is difficult to obtain the rigidity which is the property of polystyrene, and the polishing rate tends to decrease. On the other hand, if the polystyrene ratio exceeds 90, the fibers tend to break during polishing because they are hard but brittle, and the toughness of the fibers tends to be insufficient regardless of the structure of the fibers, and the strength as a polishing sheet decreases. There is a tendency. In addition, since the fiber surface is easily coated with polystyrene, as described above, the wettability with the polishing liquid deteriorates, so that the unevenness of polishing of the material to be polished is likely to occur, and further, the sticking of the fiber due to friction during polishing is caused. It tends to occur, and such a glued portion tends to cause a defect on the surface to be ground, which makes it unsuitable as a polishing sheet.

The same result as described above will be explained from the constituent weight ratio of the polyamide component.
When it exceeds 9, there is no substantial difference from the polyamide alone,
As described above, it is difficult to obtain rigidity, which is a property of polystyrene, and the polishing rate tends to decrease. If the polyamide ratio is less than 10, the toughness of the fiber tends to be insufficient,
Tear of the fiber is likely to occur during use, it becomes unsuitable as a polishing sheet, and the surface coating becomes unstable, and it is difficult to substantially cover the surface with polyamide. is there. With respect to the polishing property, the higher the rigidity of the fiber, the higher the polishing rate. Therefore, it is necessary to add polystyrene, which is a very hard resin and easily fibrillated, in a ratio of 1 or more with respect to the polyamide for the polishing sheet. However, polystyrene alone has a low melting point and is vulnerable to frictional heat, and is hard but has a brittleness, so that it is easily broken during polishing and does not have strength as a polishing sheet. Therefore, by coating polystyrene with polyamide, it is possible to give the polyamide excellent wettability and toughness, and achieve both rigidity and fiber strength (toughness), and further, wetting of the fiber by the polishing liquid. The fiber which also has is obtained.

The polyamide used as the raw material for such fibers is not particularly limited, and nylon 6, nylon 11,
Nylon 12, nylon 46, nylon 66, nylon 96 (nonamethylenediamine and / or 2-methyl-1,8-octanediamine and adipic acid nylon), nylon 910 (nonamethylenediamine and / or 2-methyl-1) , 8-octanediamine and sebacic acid nylon), nylon 912 (nonamethylenediamine and / or 2-methyl-1,8-octanediamine and dodecanedioic acid nylon), nylon 6/12 (caprolactam and laurolactam) Copolymer), nylon 6T (nylon consisting of hexamethylenediamine and terephthalic acid), nylon 9T (nonamethylenediamine and / or nylon consisting of 2-methyl-1,8-octanediamine and terephthalic acid), polyamide block copolymer Like polymer (polyamide elastomer) is used. Further, the fibers constituting the present invention may be added with resin components other than polyamide and polystyrene to the extent that the effects of the present invention are not impaired, and further various stabilizers and the like may be added.

The method for obtaining such fibers is not particularly limited, and any known method can be used. For example, there is a method of composite spinning using a nozzle having a special shape, or a method of preparing sea-island fibers in which a resin is mixed and spun in advance with an extruder so that polyamide becomes a continuous phase. In particular, the latter is more preferable because the strength and toughness of the fibers are balanced at a higher level by finely dispersing the sea component as the polyamide and the polystyrene as the island component and giving an excellent polishing sheet. Further, for the purpose of suppressing clogging during polishing of the present fiber and obtaining stable abradability for a longer period of time, it is also preferable to provide a cavity in the fiber. Examples of the method for forming such cavities include a method of spinning a hollow fiber using a modified nozzle, a method of extracting a part of fiber constituent components using a solvent, and the like.

The diameter of the present fiber is preferably 100 μm or less, more preferably 50 μm or less, particularly preferably 20 μm or less. If the thickness exceeds 100 μm and becomes excessively thick, scratches and the like are likely to occur during polishing, and the surface smoothness after polishing becomes rough. Further, the diameter is preferably 0.1 μm or more, more preferably 1 μm or more, still more preferably 5 μm or more. If the diameter is less than 0.1 μm, the rigidity of the fiber tends to be low, and the polishing rate tends to decrease.

When the fiber of the present invention is a hollow fiber, the diameter of one hole of the hollow fiber is preferably 1/2 or less of the fiber diameter, more preferably 10 μm or less, and further preferably 5 μm or less. More preferably, it is particularly preferably 3 μm or less. The larger the diameter of one hole, the lower the rigidity of the fiber, and if there is a single hole having a diameter exceeding ½ of the fiber diameter, the rigidity of the fiber decreases,
As a result, the polishing rate tends to decrease.

The diameter of one hole of the hollow fiber of the present invention is preferably 0.005 μm or more, and 0.01
It is more preferably at least μm. The existence of pores smaller than this is not excluded, and the average diameter of the abrasive grains is several nm.
Since there are many particles in the range of to several tens of nm, it tends to be difficult to contribute to the performance improvement as a silicon wafer polishing sheet (hereinafter referred to as a polishing sheet).

In this case, the effect of the holes not only suppresses clogging and improves the polishing efficiency, but also serves as an escape area for the abrasive grains when an excessive force is applied to the abrasive grains, so that the polishing is instantaneously over-polished. This can be prevented, and as a result, a smooth surface can be obtained in a shorter time. The number of pores in the hollow fiber is preferably as large as possible in any cross section of each fiber, and at least one or more is required, preferably two or more, more preferably 5 or more, and further preferably 10 or more. In addition, it is particularly preferable that a part of the holes is opened on the side surface of the hollow fiber or that the side surface is uneven due to the hole because the escape of the abrasive grains increases. Although the upper limit of the number of holes is not particularly specified from the viewpoint of performance, it is usually 200
Those exceeding 0 are difficult to mass produce.

The method for producing the hollow fiber of the present invention is not particularly limited, and any known method for producing a hollow fiber can be applied. For example, a method of extruding a molten resin from a die having an irregular cross section to obtain a hollow fiber, and also using a special die, after spinning two or more kinds of resins having different melting characteristics in the form of a core-sheath fiber A method of dissolving and removing the resin of the core, a method of melt-mixing two or more kinds of resins, spinning, and then dissolving and removing the resin constituting the island component, and the like.

In such a method for producing a hollow fiber, the largest number of pores can be formed in the obtained fiber, and further,
Since the openings of holes are formed in the side wall of the fiber, and as a result, the side surface of the fiber also acts as an effective surface at the time of polishing, it gives a particularly excellent polishing rate and polishing accuracy. Therefore, after melting and mixing two or more kinds of resins, A method of producing by so-called mixed spinning, in which the resin in the island portion is later dissolved and removed by a solvent, is more preferable. It is preferable that the fibers are stretched and / or heat-treated in the manufacturing process, because the strength of the fibers increases and the life of the polishing sheet becomes longer. Also, when dissolving and removing the resin in the island part,
This may be performed in any step from spinning to non-woven fabric to the final polishing sheet. In the case of the mixed-spun sea-island type fibers constituting the present invention,
A sea-island type fiber may be spun using polystyrene as an island component and polyamide as a sea component, and a polishing sheet may be produced without dissolving and removing the island component as it is, or may be dissolved and removed to form a hollow fiber. It is possible. In the case of dissolving and removing into hollow fibers, it is possible to change the dissolving and removing conditions to obtain a desired weight ratio of polystyrene to polyamide. That is, the sea-island type fibers of polyamide and polystyrene are spun at a desired ratio, in order to obtain a desired polystyrene ratio, the contact time with an organic solvent such as toluene as a dissolving and removing agent for polystyrene, the temperature of the organic solvent, and It can be achieved by a known method such as dip / nip treatment conditions for fibers or a nonwoven fabric composed of the fibers. As a result, the voids in which polystyrene is partially dissolved and removed become hollow, and hollow fibers can be obtained from sea-island fibers.

The method for forming the three-dimensional entangled nonwoven fabric of the fiber of the present invention is not particularly limited, and any known method can be used. For example, needle punching, hydroentanglement and the like can be exemplified.

The non-woven fabric constituting the polishing sheet of the present invention has a filling rate of 0.10 because the carrying force of the resin is strong and the hardness of the polishing sheet is higher and the polishing performance is improved.
It is preferably not less than 0.15, more preferably not less than 0.15 and not less than 0.20, because the hardness of the polishing sheet is further increased, the distribution of the fibers and the resin is more uniform, and the polishing accuracy is improved. Is particularly preferred.
Further, it is preferably 0.5 or less, more preferably 0.4 or less, and further preferably 0.3 or less. When the filling rate exceeds 0.5, it becomes difficult to impregnate the resin, and the productivity of the polishing sheet tends to decrease. Therefore, the hardness of the sheet is likely to decrease, and the distribution of the fibers and the resin becomes nonuniform, so that the polishing accuracy tends to decrease. Here, the determination of the filling rate of the nonwoven fabric is performed by previously determining the apparent volume of the nonwoven fabric in a dry state (thickness x width x length; the thickness is measured by a Peacock thickness meter), and then immersing in the alcohol to The volume increase is taken as the volume of the fiber and is calculated by the following formula. Filling rate = volume of fiber / apparent volume of non-woven fabric

[0023] It should be noted that the polishing sheet can be obtained by the same method after extracting the resin contained therein.

Further, the preferable basis weight of the non-woven fabric is in the range of 100 to 3000 g / m ^{2 in view} of easy handling of the polishing sheet.

Further, the non-woven fabric is preferably pressed in the thickness direction in order to smooth the surface and regulate the thickness. As the pressing method, a conventionally known method such as a method of passing between a plurality of heating rolls and a method of passing a preheated nonwoven fabric between cooling rolls can be used. It is also possible to achieve smoothing. In this step, the polishing effect is enhanced by suppressing the morphological change of the step due to tension, pressing, etc., and preventing the adhesion between the hollow fiber and the resin, and providing a void between the nonwoven fabric of the polishing sheet and the resin. For that purpose, after adding an adhesive such as polyvinyl alcohol, starch, or a resin emulsion to the non-woven fabric in advance, the resin is applied to the non-woven fabric, and then the pre-added adhesive or the like is extracted and removed with hot water or the like. Is preferably used.

In the present invention, the resin constituting the polishing sheet together with the non-woven fabric is not particularly limited as long as it has a flow starting temperature of 50 ° C. or more in a moisture-absorbed state, and any known resin can be used. Examples of such resins include high Tg thermoplastic resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polymethylmethacrylate resin and thermoplastic polyurethane resins, epoxy resins, crosslinkable acrylic resins, phenolic resins, crosslinkable (thermosetting) polyurethanes. Resin etc. are mentioned.

Among these resins, it is resistant to abrasion, has excellent durability during polishing, has a high frictional force, does not easily cause troubles such as detachment of threads of the nonwoven fabric during polishing, and further has solubility in a solvent. The thermoplastic or crosslinked polyurethane is particularly preferable from the viewpoints of good productivity, easy application evenly in the nonwoven fabric, and excellent productivity, because it has the best productivity without problems such as life during handling. Most preferred is thermoplastic polyurethane. Specific examples of such a polyurethane resin include known diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, naphthylene diisocyanate, hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane and urethane bond-forming derivatives thereof. One or more diisocyanates selected from, polyester polyols, polyether polyols, one or more polyols selected from known polyols such as polycarbonate polyols, ethylene glycol, propylene glycol, butane diol,
Two or more active hydrogens selected from diols such as 3-methyl-1,5-pentanediol, diamines such as ethylenediamine, isophoronediamine, piperazine and phenylenediamine, and hydrazides such as adipic acid hydrazide and isophthalic acid dihydrazide. Preferable examples include polyurethane synthesized from at least one low molecular weight compound having an atom and having a molecular weight of 300 or less.

The method of integrating the three-dimensional entangled nonwoven fabric of the present invention and the resin to form a sheet is not particularly limited. For example, the three-dimensional entangled nonwoven fabric is dipped in a resin solution,
Immediately moving into a poor solvent to solidify the resin, a method of applying a resin solution or a resin emulsion liquid to the inside of the three-dimensional entangled nonwoven fabric, and drying / precipitating the resin, impregnating a resin monomer and / or oligomer, Known methods such as a method of polymerizing / polymerizing by heating can be adopted.

In the present invention, the preferred range of the weight ratio of the three-dimensional entangled nonwoven fabric constituting the sheet and the resin contained therein is 10% by weight or more of the resin ratio from the viewpoint that the durability of the polishing sheet is further improved. Is preferable, and it is particularly preferable that the resin ratio is 30 w% or more because polishing spots are less likely to occur. Further, in order to sufficiently obtain the effect of the present invention, a fiber ratio of 10 w% or more is preferable, and a fiber ratio of 30 w% or more is preferable in that the maintenance interval due to clogging becomes longer.

In the polishing sheet of the present invention, in order to finely adjust the hardness of the polishing sheet after the resin and the nonwoven fabric are integrated, the porosity, the thickness, etc. may be further adjusted by pressing, foaming or other treatment. It is possible.

In the polishing sheet of the present invention, the surface of the sheet can be used as a polishing surface, or the sheet can be cut into an arbitrary shape and its cross section can be used as a polishing surface.
When the surface is used as the polishing surface, more precise polishing is possible than when using the cross section of the sheet, and it is preferable to use such a method for polishing in which accuracy is important. When the surface of the sheet is used as a polishing surface, it is preferable that the surface of the polishing sheet is smoothed during use in order to prevent large irregularities on the surface. The smoothing method is not particularly limited, and any method such as flat plate pressing can be used, but it is preferable to perform a buffing treatment with sandpaper or the like from the viewpoint that the fibers of the present invention are uniformly raised and exposed to improve the polishing rate. It is most useful to smooth the surface by performing the polishing.

When the cross section of the sheet is used as the polishing surface, the orientation of the fibers provides the most suitable structure for polishing.
It is preferable to use such a method in a step where polishing can be performed at a higher speed and importance is attached to the polishing rate. Further, in this case, it is particularly preferable from the viewpoint of improving the polishing efficiency that the polishing sheets of the present invention are overlapped with each other or the polishing sheets are bonded together.

The polishing sheet of the present invention has a thickness of 0.
The range of 1 to 10 mm is preferable, and the range of 0.3 mm to 3 mm is preferable. If the thickness is less than 0.1 mm, the rigidity is insufficient, wrinkles are likely to occur, and the handleability is deteriorated. In particular, when the surface is used as a polishing surface, the life of the polishing sheet is shortened, which is disadvantageous for practical use.
If the thickness exceeds mm, handling is deteriorated, such as buckling due to slight strain, and it is difficult to evenly distribute the resin in the sheet, which tends to cause a decrease in productivity.

The density of the polishing sheet of the present invention is not particularly limited, but a range of 0.1 to 0.9 g / cm ³ is suitable for high productivity. The surface hardness of the polishing sheet of the present invention is C specified in JIS K7312.
Expressed in hardness, it is preferably 40 ° or more, and 50
It is more preferable that the angle is ≧ °, and it is particularly preferable that the angle is ≧ 55 °. When the hardness is lower than 40 °, the polishing rate and the productivity tend to be lowered, and the polishing sheet itself tends to be deformed, which tends to make it difficult to obtain smooth quality.
Further, it is preferably 100 ° or less, more preferably 95 ° or less, and further preferably 90 ° or less. If the hardness exceeds 100 °, the deformation of the polishing sheet will be too small, and surface defects of the polishing sheet, defective abrasive grains, defective polishing conditions, etc. will directly lead to poor quality, resulting in a smooth surface. It tends to decrease.

[0035]

The present invention will be described in more detail based on the following examples and comparative examples, but the present invention is in no way limited by these examples. In the text,% means% by weight and part means part by weight unless otherwise specified. [Sea-island ratio of sea-island type fiber] The area ratio of sea-islands in the fiber cross section is calculated from the average fiber diameter, the average diameter of the islands, and the number of islands by taking an enlarged photograph of the fiber cross section at 500 to 2000 times. . [Hollowness of Fiber Section] The hollowness of a fiber having a hollow portion is calculated by the following formula by taking an enlarged photograph of a fiber section of 500 to 2000 times with an electron microscope. Hollow ratio (%) = (A / B) × 100 A = Area of hollow part of fiber cross section B = Area of part surrounded by outer circumference of fiber cross section

Example 1 Nylon 6 (hereinafter abbreviated as PA6) 50 as polyamide
Part and polystyrene (hereinafter abbreviated as PS) 50 parts by dry blending, melt kneading with a single-screw extruder, then extruded from a die, sea component is PA6, island component is PS diameter 15μ
It prevented sea-island type fibers with m and 50 islands. The obtained fiber was drawn, crimped and cut to obtain a staple fiber having 3.5 decitex and a cut length of 55 mm. The staple fiber was passed through a card to make a web by a cross-wrapper method, and laminated. Next, a felt needle having one barb on the needle was used for needle punching at a needle sticking density of 980 P / cm ² to obtain a nonwoven fabric having a basis weight of 450 g / m ² .
The filling factor of the non-woven fabric was 0.21. It was confirmed whether the fibers constituting the non-woven fabric were fused by PS when the fibers were pressed at 100 ° C. However, the fusion of the fibers was not observed. This non-woven fabric was gravure coated with polyvinyl alcohol (hereinafter abbreviated as PVA) and subjected to shape retention treatment, then impregnated with a 17% dimethylformamide (hereinafter abbreviated as DMF) solution of polyurethane, coagulated with a 3% DMF aqueous solution, and hot water was added. It was washed to obtain a porous sheet made of a three-dimensional entangled nonwoven fabric and a thermoplastic polyurethane resin. The weight ratio of nonwoven fabric to resin of the obtained sheet was 2: 1. Further, the surface was buffed with sandpaper to smooth the surface to obtain a polishing sheet having a thickness of 1.5 mm. When the C hardness of this polishing sheet was measured using an Asker C type hardness meter manufactured by Kobunshi Keiki Co., Ltd. according to JIS K7312, the hardness was 75.

The polishing sheet of the present invention was attached to a lower platen having a diameter of 500 mm with a pressure-sensitive adhesive, and then three aluminum discs having a diameter of 4 inches and a surface roughness before polishing of 2 μm were adhered to the upper platen with wax. Then, both of them were set in a polishing machine, and a 20-fold pure water dilution of a colloidal silica slurry (# 2350 manufactured by Nalco) was refluxed at a flow rate of 1 liter / min and
Polishing was performed at a rotation speed of 00 rpm. The surface roughness of the aluminum disc after 2 minutes was evaluated. The measurement is JIS B0601-19
According to 94, a surface roughness meter (Surfcom 120A manufactured by Tokyo Seimitsu Co., Ltd., conical stylus; apex angle 90 °, tip curvature radius 5 μm) was used to evaluate roughness between two points at 40 mm intervals.

Further, using the same polishing sheet, a new aluminum disc was repeatedly polished for 2 minutes, and the surface roughness of the aluminum disc after polishing was 1. The durability was evaluated by using the number of times when the number became 5 times as a measure of the durability of the polishing sheet. The results are shown in Table 1.
Shown in.

Example 2 The polishing sheet used in Example 1 was dipped in toluene and a part of PS was extracted to polish a multi-hollow fiber having an average hollow rate of 6% at 10 arbitrary cross sections. Got the sheet.
After the polyurethane resin component of this polishing sheet was extracted and removed with DMF, it was confirmed whether the fibers forming the non-woven fabric were melted by PS when the fibers were pressed at 100 ° C. I couldn't do it. At this time, the component ratio of the fibers is PA6: PS = 62.
At 5: 37.5, it was observed that polystyrene in the island part was partially dissolved and removed to form a hollow part in the fiber cross section.
The fiber to resin ratio was 8: 5. This polishing sheet was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 3 A nonwoven fabric was obtained in the same manner as in Example 1 except that the ratio of PA6 to PS was 62.5: 37.5 and the basis weight was 360 g / m ² . The filling factor of the non-woven fabric was 0.17. It was confirmed whether the fibers constituting the non-woven fabric were fused by PS when the fibers were pressed at 100 ° C. However, the fusion of the fibers was not observed. A polishing sheet was obtained in exactly the same manner as in Example 1 except that the impregnation rate of this nonwoven fabric was adjusted so that the fiber-to-resin ratio was 8: 5. This polishing sheet was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 4 Spinning was carried out under the same conditions as in Example 1 except that a hollow fiber nozzle was used, and a cavity having a diameter of 5 μm was formed in the center, PA6 being the sea component, and PS being the island component from 42 islands. A hollow fiber having a diameter of 15 μm was obtained. This was made into a nonwoven fabric under the same conditions as in Example 1 to obtain a nonwoven fabric having a basis weight of 450 g / m ² . The filling factor of the non-woven fabric was 0.21. 100 fibers that make up the non-woven fabric
It was confirmed whether or not fusion of fibers occurred due to melting of PS when pressed at 0 ° C. However, fusion of fibers was not observed. Polyvinyl alcohol (hereinafter PVA)
17% after gravure coating and shape retention treatment
Was impregnated with the DMF solution of polyurethane, coagulated with a 3% aqueous DMF solution, and washed with hot water to obtain a porous sheet composed of a three-dimensional entangled nonwoven fabric and a thermoplastic polyurethane resin. The weight ratio of the non-woven fabric of the obtained sheet to the resin contained was 17:10.
there were. Further, the surface was buffed with sandpaper to smooth the surface to obtain a polishing sheet having a thickness of 1.5 mm. When the C hardness of this polishing sheet was measured using an Asker C type hardness meter manufactured by Kobunshi Keiki Co., Ltd. according to JIS K7312, the hardness was 71. This polishing sheet was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 A polishing sheet was obtained in the same manner as in Example 1 except that only PA6 was used as the fiber raw material. It was confirmed whether or not fusion of fibers occurred due to melting of polystyrene when the fibers constituting the used nonwoven fabric were pressed at 100 ° C. However, fusion of fibers was not observed. This polishing sheet was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 A polishing sheet was obtained in the same manner as in Example 1 except that PS was used as the fiber raw material. When the fibers constituting the used nonwoven fabric were pressed at 100 ° C., it was confirmed whether the fusion of the fibers occurred due to the melting of the polystyrene, and the fibers were melted, and the fibers were adhered to each other to form a plate. When the same evaluation as in Example 1 was attempted for this polishing sheet, a large amount of lint was generated due to fiber breakage and sticking, and the material to be polished was contaminated, so the evaluation was stopped.

Comparative Example 3 A polishing sheet was obtained in exactly the same manner as in Example 1 except that PA6 was an island component, PS was a sea component, and the ratio of PA6 and PS was 3: 7. When the fibers constituting the used nonwoven fabric were pressed at 100 ° C., it was confirmed whether the fusion of the fibers occurred due to the melting of the polystyrene, and the fibers were melted, and the fibers were adhered to each other to form a plate. When the same evaluation as in Example 1 was attempted for this polishing sheet, a large amount of lint was generated due to the sticking and breaking of the fibers, and the material to be polished was contaminated, so the evaluation was stopped.

Example 5 After the front and back surfaces of the polishing sheet obtained in Example 1 were bonded together with a 17% polyurethane DMF solution as an adhesive, the polishing sheet was cut to a thickness of 5 mm in the bonding direction, and Example 1 was used.
A polishing sheet having a polishing surface in which the cross-sections of the polishing sheet were laminated was obtained. When the glass for cathode ray tubes was polished on the production line using this polishing sheet, the intended product was obtained by polishing for 5 minutes per piece.

Comparative Example 4 The same test as in Example 4 was carried out except that the sheet obtained in Comparative Example 1 was used, and a desired product was obtained by polishing for 9 minutes per piece.

Comparing Example 1 with Comparative Examples 1, 2, and 3, the polishing performance of the polishing sheet of the present invention is superior to that using the fiber of PA alone, and PS alone or PS is sea. It can be seen that those using fibers are not suitable as abrasives, and it is essential that the PA of the present invention is sea. Also, comparing Examples 1 and 4, and 2 and 3,
It can be seen that when the fiber is a hollow fiber, the polishing sheet exhibits more excellent performance. Further, by comparing Example 4 with Comparative Example 4, it can be confirmed that the effects of the present invention are exhibited even when the cross section is used as a polishing surface.

[0048]

[Table 1]

[0049]

If the polishing sheet of the present invention is used,
Not only can the object to be polished such as a cathode ray tube be polished in a shorter time, but the productivity of the polishing cloth itself can be improved and the manufacturing cost can be reduced, which is useful because the productivity of the entire polishing process can be improved.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) D06M 15/564 D06M 15/564 F term (reference) 3C058 AA07 AA09 CB01 CB03 DA17 3C063 AA03 BB11 BC03 FF23 4L033 AA05 AA08 AB07 AC15 CA18 CA34 CA45 CA47 CA49 CA50 4L041 AA07 BA04 BA05 BA16 BA41 BB05 BC20 BD20 CA19 CA55 4L047 AA18 AA23 AA25 AA27 AB02 AB09 BA03 BA04 CB10 CC14 DA00

Claims (4)

[Claims] 1. A three-dimensional entangled non-woven fabric and a sheet containing a resin therein, wherein the fibers constituting the non-woven fabric are substantially composed of polystyrene and polyamide, and the weight ratio of the polystyrene and the polyamide is 1:99. ~ 90: 10
And the polyamide inside the fiber forms a continuous layer, and the surface of the fiber is substantially made of polyamide. 2. The polishing sheet according to claim 1, wherein the fiber is a sea-island type fiber containing polyamide as a sea component and polystyrene as an island component. 3. The polishing sheet according to claim 1, wherein the fiber is a hollow fiber. 4. The resin according to claim 1, which is polyurethane.
3. The polishing sheet according to any one of 3 above.