JP6963446B2 - Holding pad - Google Patents

Description

The present invention relates to a holding pad having a polyurethane resin sheet manufactured by a wet film forming method.

In recent years, for example, in a flat display panel such as a glass substrate for a liquid crystal display, there is a great need for larger size, lighter weight, and thinner size, and for example, a large glass substrate having a side of more than 3 m has been used. When an object to be polished such as a glass substrate is polished by a polishing pad, the holding pad for holding the object to be polished also needs to be enlarged in accordance with the increase in the size of the object to be polished.

The large holding pad has a polyurethane resin sheet that has a soft and adhesive holding surface to hold the object to be polished, and a platen that is adhered to the opposite side of the holding surface of the polyurethane resin sheet to hold the polyurethane resin sheet. It is configured to have a double-sided adhesive tape to be attached to. The presence of the tape base material provided by the double-sided adhesive tape adds waist strength to the soft polyurethane resin sheet to improve handleability.

In such a large holding pad for a large glass substrate, a large double-sided adhesive tape for attaching to the holding surface plate is also required to be large enough to correspond to the large holding pad, but the width is 2000 mm or more (particularly 2500 mm width or more). Since it is difficult to obtain the double-sided adhesive tape as a general-purpose product, it has been proposed to use a plurality of double-sided adhesive tapes side by side on one large holding pad. However, double-sided adhesive tape has adhesive layers provided on both sides of a rigid tape base material, and when such double-sided adhesive tape is stored or transported, it bends at the boundary between adjacent double-sided adhesive tapes, resulting in creases. As a result, the flatness of the holding surface may be impaired. In addition, since the polyurethane resin sheet is soft when attached to the holding platen, the polyurethane resin sheet may be stretched at the boundary between adjacent double-sided adhesive tapes, and the polyurethane resin attached to the holding platen may be stretched. Wrinkles and dents may be formed on the holding surface of the sheet, and the polishing quality of the object to be polished using such a holding pad may be impaired.

Therefore, conventionally, as a double-sided adhesive tape for a large holding pad, a tape base material made of PET film or the like, which has the same size as a large polyurethane resin sheet and forms a single piece with high rigidity, has been adopted, and adhesive to both sides of the tape base material. A plurality of non-support type adhesive tapes formed in a sheet shape with only layers are disclosed in parallel with each other through a gap (Patent Documents 1 and 2).

Japanese Patent No. 5398376 Japanese Patent No. 5640076

The holding pad described in Patent Document 1 is provided in a gap between a plurality of non-support type adhesive tapes provided on one side of a tape base material constituting a double-sided adhesive tape and on the other side of the tape base material. The gaps between the plurality of non-support type adhesive tapes overlap in the thickness direction of the holding pad. At the time of polishing the object to be polished held by such a holding pad, it is held on the holding surface of the soft polyurethane resin arranged on the holding platen of the single-sided polishing device via the above-mentioned double-sided adhesive tape. The object to be polished is polished in a state where the gap on one side and the gap on the other side of the double-sided adhesive tape overlap in the length direction and are synergistically transferred. It impairs the polishing quality of objects.

The holding pad described in Patent Document 2 includes the extending direction of the gap between a plurality of non-support type adhesive tapes provided on one side of the tape base material constituting the double-sided adhesive tape, and the other side of the tape base material. The extending direction of the gap between the plurality of non-support type adhesive tapes provided on the side is arranged at a position parallel to each other, and the overlap in the thickness direction as described in Patent Document 1 is avoided. Even for an object to be polished using such a double-sided adhesive tape, each of the gaps arranged at positions parallel to each other of the double-sided adhesive tape is transferred to the surface to be polished at regular intervals. Extremely characteristic streaky polishing unevenness may occur in parallel. This characteristic polishing unevenness is not desirable because the quality is not a problem in the past due to the thinning, but the polishing of a thin substrate tends to have an influence and the quality deteriorates.

An object of the present invention is to prepare a double-sided adhesive tape in which a plurality of non-support type adhesive tapes are bonded side by side through a small gap on one surface and the other surface of the tape base material without forming a gap with each other. The purpose is to suppress the occurrence of characteristic polishing unevenness on the surface to be polished of the object to be polished in the polishing process using the holding pad formed by adhering to the opposite side surface of the holding surface of the sheet.

The invention according to claim 1 has a polyurethane resin sheet provided with a holding surface for holding an object to be polished, and a plurality of non-support type adhesive tapes do not overlap each other on one surface and the other surface of the tape base material. Adjacently bonded double-sided adhesive tape is a holding pad that is adhered to the opposite side of the holding surface of the polyurethane resin sheet, and is all between a plurality of non-support type adhesive tapes provided on one surface of the tape base material. and each of the extending direction of the border, in which as the respective extending directions of all the boundaries between a plurality of non-support type adhesive tape with the other surface of the tape base material is cross each other ..

The invention according to claim 2 is the invention according to claim 1, wherein the holding pad has a rectangular shape having two adjacent sides having a length of 2000 mm or more, or a circular shape having a diameter of 2000 mm or more. It was made like this.

The invention according to claim 3 is the invention according to claim 1 or 2, further comprising the extending direction of the boundary between a plurality of non-support type adhesive tapes provided on one surface of the tape base material, the tape base material, and the like. The intersection angle in the extending direction of the boundary between a plurality of non-support type adhesive tapes provided on the surface is set within the range of 60 degrees to 120 degrees.

In the invention according to claim 4, in the invention according to any one of claims 1 to 3, the width of the boundary between a plurality of non-support type adhesive tapes bonded to one surface and the other surface of the tape base material is further set. It is set to 1.0 mm or less.

The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the polyurethane resin sheet constituting the holding pad further includes a holding surface having an A hardness of 5 or more and 50 or less. Is.

According to the present invention, in a double-sided adhesive tape that is adhered to the opposite side surface of a polyurethane resin sheet constituting a holding pad, the boundary between a plurality of non-support type adhesive tapes provided on one surface of the tape base material is extended. The existing direction and the extending direction of the boundary between the plurality of non-supported adhesive tapes provided on the other surface of the tape base material are arranged so as to intersect each other. Thereby, in the polishing process using such a holding pad, it is possible to suppress the polishing unevenness that occurs on the surface to be polished due to the above-mentioned boundary in the two directions on the surface to be polished.

FIG. 1 is a perspective view schematically showing an example of the holding pad of the present invention in an exploded manner.

1. 1. Characteristic composition and action of holding pad
(1) In the double-sided adhesive tape that is adhered to the polyurethane resin sheet that constitutes the holding pad, no gap is formed or a small gap is formed between a plurality of non-support type adhesive tapes provided on one surface of the tape base material. The extending direction of the boundary G1 and the extending direction of the boundary G2 formed on the other surface of the tape base material without forming a gap or forming a small gap. Are arranged to intersect each other with an intersection angle α.

In this way, in the holding pad, the boundary G1 and the boundary G2 formed on both sides of the above-mentioned tape base material overlap each other in the thickness direction of the holding pad only locally, which is the intersection of the boundary G1 and the boundary G2. become. Therefore, when the object to be polished is held on such a holding pad and polished, the overlapping portion of the above-mentioned boundaries G1 and G2 is small and the influence is very small, and the flatness of the surface to be polished in the object to be polished Does not significantly damage. In addition, extremely characteristic streak-like polishing unevenness that is parallel to the surface to be polished of the object to be polished does not occur at regular intervals, and deterioration of quality is suppressed.

(2) When the holding pad is a large holding pad having a rectangular shape having two adjacent sides having a length of 2000 mm or more or a circular shape having a diameter of 2000 mm or more, the holding pad is made of double-sided adhesive tape. The presence of the provided tape base material adds waist strength to the soft polyurethane resin sheet, and does not cause air to get caught or wrinkle between the flexible polyurethane resin sheet and the holding surface plate when it is attached to the holding surface plate. Therefore, it can be pasted without requiring skill, and the handleability can be improved.

Further, since the tape base material constituting the double-sided adhesive tape is made of one piece, the non-support bonded to both sides of the tape base material can be used even when the holding pad is used as a scroll during storage or transportation of the holding pad. Bending of the holding pad at the boundary portion of the type adhesive tape can be suppressed. Further, it is possible to prevent the soft polyurethane resin sheet from stretching at the portion corresponding to the boundary of the non-support type adhesive tape described above when the holding pad is attached to the holding surface plate. As a result, it is possible to prevent wrinkles and dents from being generated on the holding surface of the polyurethane resin sheet constituting the holding pad, and these wrinkles and dents are transferred to the object to be polished to improve the flatness of the surface to be polished in the object to be polished. It can be prevented from being damaged.

(3) Ideally, the intersection angle α of the boundary G1 and the boundary G2 of the above-mentioned (1) is 90 degrees, but if it is 90 degrees ± 30 degrees (60 to 120 degrees), the above-mentioned (1) The action can be obtained, and if it is 90 degrees ± 10 degrees (80 degrees to 100 degrees), the action of (1) described above can be obtained more reliably.

(4) The width of the boundary G1 and the boundary G2 in (1) described above is most preferably 0.0 mm (no gap), but if it is 1.0 mm or less (small gap), the boundary G1 and the boundary G2, The adverse effect of the presence of G2 on the flatness of the surface to be polished on the object to be polished can be minimized.

(5) When the polyurethane resin sheet constituting the holding pad of the present invention has a holding surface soft to such an extent that the A hardness is 5 or more and 50 or less, the holding surface of the polyurethane resin sheet stably adheres to the object to be polished. It ensures that the softness required for holding is provided, and prevents the object to be polished from excessively sinking into the holding surface. Then, when the present invention is applied to such a holding pad, the overlap of the boundaries G1 and G2 of the above-mentioned (1) is transferred to the object to be polished through the holding surface of such a soft polyurethane resin sheet, and the said. It is possible to effectively and remarkably avoid the possibility that the flatness of the surface to be polished in the object to be polished is impaired.

2. Method for manufacturing a holding pad A typical method for manufacturing the holding pad of the present invention will be described below. The method has at least the following configurations:
Preparation process Coating process Solidification regeneration process Cleaning / drying process Grinding process Includes laminating process.

(Preparation process)
In the preparatory step, the polyurethane resin, N, N-dimethylformamide (hereinafter abbreviated as DMF), which is a water-miscible organic solvent capable of dissolving the polyurethane resin, and an additive are mixed to dissolve the polyurethane resin. The water-miscible organic solvent may be any organic solvent that mixes with water at an arbitrary ratio, and for example, N, N-dimethylacetamide or the like may be used in addition to DMF. As the polyurethane resin, a resin having a number average molecular weight in the range of 5,000 to 100,000 is selected from resins such as polyester, polyether, and polycarbonate, and the polyurethane resin is, for example, 30% by weight. Dissolve in DMF. By limiting the molecular weight of the polyurethane resin, the molecular movement of the polyurethane resin can be facilitated in the solidification / regeneration step. As additives, in order to control the length in the average thickness direction of foam and the number per unit volume, pigments such as carbon black, hydrophilic additives that promote the formation of foam, and the solidification and regeneration of polyurethane resin are stabilized. Hydrophobic additives and the like can be used. The obtained solution is defoamed under reduced pressure to obtain a polyurethane resin solution.

(Applying process)
In the coating step, the polyurethane resin solution obtained in the preparatory step is continuously coated at room temperature with a knife coater or the like so as to be substantially uniform on the strip-shaped film-forming substrate. At this time, the coating thickness (coating amount) of the polyurethane resin solution is adjusted by adjusting the gap (clearance) between the knife coater or the like and the film-forming substrate. A non-woven fabric or film made of a resin such as PET resin can be used as the film-forming base material, but in this example, a PET film is used as the film-forming base material.

(Coagulation regeneration process)
In the solidification / regeneration step, the polyurethane resin solution applied to the film-forming substrate is guided to a coagulation liquid (aqueous coagulation liquid) containing water, which is a poor solvent for the polyurethane resin, as a main component. In this example, water is used as the coagulating liquid. In the coagulating liquid, first, dense micropores are formed on the surface side of the polyurethane resin solution to form a skin layer. After that, as the replacement of the DMF with the coagulating liquid in the polyurethane resin solution progresses, the polyurethane resin is solidified and regenerated into a sheet on the film-forming substrate to form a resin sheet in which foam is formed. DMF is desolvated from the polyurethane resin solution, and DMF is replaced with water, so that foaming and micropores communicate with each other in a mesh pattern.

(Washing / drying process)
In the washing / drying step, the sheet-shaped polyurethane resin (hereinafter referred to as film-forming resin) solidified and regenerated in the solidification / regeneration step is peeled off from the film-forming substrate, washed in a cleaning solution such as water, and remains in the polyurethane resin. Remove the DMF. After cleaning, the film-forming resin is dried in a cylinder dryer. The cylinder dryer is provided with a cylinder having a heat source inside. The film-forming resin passes along the peripheral surface of the cylinder to dry. The film-forming resin after drying is wound into a roll.

(Grinding process)
In the grinding process, a grinding process such as a buffing process is performed on the surface side opposite to the skin layer formed on the surface of the film-forming resin. A buffing machine, a slicing machine, or the like can be used for the grinding process. As a result, the thickness of the film-forming resin is made uniform, and a polyurethane resin sheet can be obtained.

(Laminating process)
In the laminating process, a separately produced double-sided adhesive tape is lined up and bonded to the opposite side surface of the holding surface of the polyurethane resin sheet obtained in the grinding process by a laminating machine.

In the double-sided adhesive tape, a plurality of non-support type adhesive tapes formed in a sheet shape with only an adhesive layer are adjacent to each other on both sides of a tape base material made of one high-rigidity PET film or the like without overlapping each other. It is pasted together. At this time, the extending direction of the boundary G1 between the plurality of non-support type adhesive tapes provided on one surface of the tape base material and the boundary G2 between the plurality of non-support type adhesive tapes provided on the other surface of the tape base material. The extending directions of the above form an intersection angle α and are arranged so as to intersect each other. The opposite side of the surface to which the polyurethane resin sheet of the non-support type adhesive tape is adhered is covered with a release film.

The thickness of the tape base material can be arbitrarily set within a range that does not deviate from the gist of the present invention, and can be, for example, 50 to 200 μm, preferably 50 to 100 μm. Moreover, although PET film is exemplified as a tape base material, the present invention is not limited thereto. For example, polypropylene, biaxially stretched polypropylene (OPP), or the like may be used. The thickness of the adhesive layer can be arbitrarily set as long as it does not deviate from the gist of the present invention, and can be, for example, 10 to 70 μm.

A film-like surface layer (skin layer) is formed on the surface of the polyurethane resin sheet produced in this manner at a higher density than the inside. Since the surface of this skin layer has excellent contact with the object to be polished, it is possible to hold the object to be polished. That is, the surface of the skin layer serves as a holding surface for holding the object to be polished.

3. 3. Specific implementation results
3-1. Example 1 (see FIG. 1)
(1) The holding pad 100 of Example 1 was prepared by the following procedure.
i. The side surface of the polyurethane resin sheet 10 having an A hardness of 30 obtained by the wet film forming method with respect to the holding surface 11 was buffed to obtain a thickness of 0.8 mm.

The A hardness was at 25 ° C. and was measured in accordance with Japanese Industrial Standards (JIS K 6253). More specifically, sample pieces of 30 mm × 30 mm were stacked so as to have a thickness of 4.5 mm or more, and measured using an A-type hardness tester (Japanese Industrial Standards, JIS K7311).

The obtained polyurethane resin sheet 10 was cut into squares having a side length of 2100 mm.

ii. A double-sided adhesive tape 20 was produced. The double-sided adhesive tape 20 is a 55 μm-thick non-support type adhesive tape 21 or 22 formed in a sheet shape with only an adhesive layer on both sides of a 75 μm-thick tape base material 20A made of one high-rigidity PET film. Was bonded adjacent to each other without overlapping each other. At this time, the extending direction of the boundary G1 between the two non-support type adhesive tapes 21 provided on one surface of the tape base material 20A and the two non-support type adhesive tapes 22 provided on the other surface of the tape base material 20A. The extending direction of the boundary G2 between them is arranged so as to intersect each other with an intersection angle α = 90 degrees. Release films 21F and 22F were attached to the outer surfaces of the non-support type adhesive tapes 21 and 22.

iii. As shown in FIG. 1, the non-support type adhesive tape 21 from which the release film 21F of the double-sided adhesive tape 20 was peeled off was adhered to the buffed surface on the opposite side of the polyurethane resin sheet 10 with respect to the holding surface 11. As a result, the holding pad 100 was produced.

(2) The holding pad 100 produced in (1) above was cut into a circle having a diameter of 680 mm for test polishing. At this time, it was cut so as to include both the boundaries G1 and G2 between the adhesive tapes. The release film 22F of the cut holding pad 100 was peeled off, and the holding pad 100 was attached to the holding surface plate via the non-support type adhesive tape 22.

The glass substrate was held on the holding pad 100 as an object to be polished, and the glass substrate was polished by the polishing pad provided on the polishing surface plate of the single-sided polishing apparatus.

3-2. Comparative Example 1
When producing the holding pad by the same polyurethane resin sheet 10 and double-sided adhesive tape 20 as in Example 1, the boundary G1 and the boundary G2 are arranged in parallel with each other, and this holding pad is used for polishing the glass substrate as in Example 1. Was offered.

3-3. Results After polishing the glass substrate according to Example 1 and Comparative Example 1, the surface to be polished of the glass substrate was irradiated with a halogen lamp, and an appearance inspection was carried out.

In the holding pad of Comparative Example 1, thin streaks that were parallel at regular intervals were observed on a part of the glass surface, probably because the soft holding pad had slack in the same direction. On the other hand, in the holding pad of Example 1, no streaks were observed on the appearance.

According to the present invention, a double-sided adhesive tape in which a plurality of non-support type adhesive tapes are laminated adjacent to each other on one surface and the other surface of the tape base material without overlapping each other is formed on the opposite side surface of the holding surface of the polyurethane resin sheet. In the polishing process using the holding pad formed by adhering to the material, it is possible to suppress the occurrence of characteristic polishing unevenness on the surface to be polished of the object to be polished.

100 Retaining pad 10 Polyurethane resin sheet 11 Retaining surface 20 Double-sided adhesive tape 21, 22 Non-support type adhesive tape G1, G2 Boundary α Intersection angle

Claims (5)

A double-sided adhesive having a polyurethane resin sheet having a holding surface for holding an object to be polished, and a plurality of non-support type adhesive tapes are laminated adjacent to each other on one surface and the other surface of the tape base material without overlapping each other. A holding pad in which the tape is adhered to the opposite side of the holding surface of the polyurethane resin sheet.
All in the extending direction of all boundaries between multiple non-supported adhesive tapes on one side of the tape substrate and all between multiple non-supported adhesive tapes on the other side of the tape substrate . A holding pad in which each of the extending directions of the boundary is arranged so as to intersect with each other. The holding pad according to claim 1, wherein the holding pad has a rectangular shape having two adjacent sides having a length of 2000 mm or more, or a circular shape having a diameter of 2000 mm or more. The extending direction of the gap between the plurality of non-support type adhesive tapes provided on one surface of the tape base material and the extending direction of the gap between the plurality of non-support type adhesive tapes provided on the other surface of the tape base material. The holding pad according to claim 1 or 2, wherein the crossing angle of the above is within the range of 60 degrees to 120 degrees. The holding pad according to any one of claims 1 to 3, wherein the boundary between a plurality of non-support type adhesive tapes bonded to one surface and the other surface of the tape base material is 1.0 mm or less. The holding pad according to any one of claims 1 to 4, wherein the polyurethane resin sheet constituting the holding pad has a holding surface having an A hardness of 5 or more and 50 or less.

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