JP2012071366A - Holding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a holding material securing holding force to an object to be polished and facilitating removal of the object to be polished.SOLUTION: The holding material 10 includes a polyurethane sheet 2 prepared by a wet coagulation method and a protective layer 5 disposed on a surface of the polyurethane sheet 2. The polyurethane sheet 2 includes a skin layer 2a and a nap layer 2b formed while cells 3 are substantially equally dispersed on the inner side from the skin layer 2a. The protective layer 5 is formed of an aqueous emulsion type polyurethane resin so as to cover the skin layer 2a after the preparation of the polyurethane sheet 2 by the wet coagulation method. The surface of the protective layer 5 forms the holding surface S. A recess 5a in which the surface of the skin layer 2a is partially exposed is formed on the protective layer 5. The surface of the skin layer 2a is protected by the protective layer 5, and the adhesion relative to the object to be polished is limited by the formation of the recess 5a.

Description

  The present invention relates to a holding material, and more particularly, to a holding material having a resin layer made of a soft resin having a skin layer formed by a wet coagulation method and having a number of cells formed on the inner side of the skin layer.

  Conventional glass substrate for liquid crystal display (LCD), glass substrate on which color material films of three primary colors of red (R), green (G), and blue (B) in color filters are formed, flat composed of LCD cells, etc. In panel displays and the like, polishing is performed in the manufacturing process thereof. Generally, in the polishing process, a porous sheet having a skin layer on the surface side by a wet coagulation method and having a large number of cells (foaming) formed therein is provided for the purpose of holding an object to be polished. Retaining material is used. That is, a holding material is used in which a porous sheet (resin holding layer) having a uniform thickness by grinding the back side is bonded to a base material having an adhesive layer and the porous sheet is supported by the base material. Yes.

  When the holding material is used, the object to be polished is held by a composite action such as an adhesion force on the surface of the holding material, an adsorption force due to a surface tension of water or the like. However, since the skin layer surface of the porous sheet is worn and damaged over time due to friction with the object to be polished, the adhesion between the object to be polished and the holding material may be insufficient. When the surface of the skin layer is damaged, the cells formed inside open, and the cleaning liquid and cleaning water for exchanging the object to be polished rapidly infiltrate the porous sheet, and the cells are filled with the polishing liquid. It is. The polishing liquid or the like in the cell is released to the holding surface side due to the deformation of the cell due to the pressing force during the polishing process, and the holding force with respect to the object to be polished may be abruptly reduced. As a result, there is a problem that the object to be polished falls from the holding material during the polishing process, and the manufacturing efficiency is reduced due to the damage to the object to be polished and the accompanying machine stoppage. In addition, when the polishing liquid that has entered from the damaged portion of the skin layer reaches the bonding surface between the porous sheet and the substrate, the adhesive layer may be exposed to the polishing liquid and the porous sheet and the substrate may be peeled off. For this reason, there is also a problem that the structure of the holding material is lost and the flatness of the object to be polished is lowered.

  On the other hand, in order to improve productivity, the object to be polished tends to be enlarged. For example, glass substrates, which are constituent materials for LCDs, have been increasing in size year by year, and large glass substrates with a side approaching 3 m have been used. Along with the increase in size of the glass substrate, when the glass substrate is removed from the holding material after the polishing process, there is a problem that a force applied to the glass substrate is increased and a crack or the like due to the bending of the glass substrate occurs.

  In order to avoid these problems, for example, there is a technique for suppressing the infiltration of the polishing liquid into the inside due to the liquid permeability of the skin layer itself by covering the surface of the skin layer and ensuring the holding power to the object to be polished. It is disclosed (see Patent Document 1). In this technology, the adhesive material is laminated on the surface of the skin layer, and through-holes are formed in the adhesive material. It is possible to suppress the penetration of the polishing liquid into the. Moreover, the technique of the holding material which bonded and laminated | stacked two porous sheets produced by the wet coagulation method via the adhesive agent is disclosed (refer patent document 2). In this technique, the upper porous sheet is brought into contact with the object to be polished, but the infiltration of the polishing liquid into the lower layer can be suppressed by the adhesive interposed between the two porous sheets.

JP 2005-224888 A JP 2005-11972 A

  However, in the technique of Patent Document 1, the object to be polished can be held by the adhesion force with the adhesive material, but the holding force for the object to be polished becomes too high due to the strong adhesive force as compared with the conventional holding material. For this reason, in the polishing process of a large object to be polished, the object to be polished is easily damaged. Moreover, in the technique of patent document 2, the process of bonding two porous sheets is needed, and the cost per one holding | maintenance material will be caused. Furthermore, since a porous sheet is used on the upper layer side, it is difficult to avoid damage to the skin layer, and thus penetration of the polishing liquid into the porous sheet. Insufficient suppression of decrease in holding power with respect to the polished article becomes insufficient. Therefore, it is important to limit the adhesion force between the object to be polished and the holding material in order to suppress damage when attaching and detaching the object to be polished. It is important to secure the holding force.

  An object of the present invention is to provide a holding material that can secure a holding force for an object to be polished and can easily attach and detach the object to be polished.

  In order to solve the above problems, the present invention provides a first resin layer made of a soft resin having a skin layer formed by a wet coagulation method and having a plurality of cells formed on the inner side of the skin layer, A second resin layer disposed on the surface of the skin layer, the surface forming a holding surface for holding an object to be polished, wherein the second resin layer partially covers the surface of the skin layer A holding material is characterized in that a hole or a groove is formed so as to be exposed.

  In the present invention, since the second resin layer is disposed on the surface of the skin layer of the first resin layer, the damage of the skin layer is suppressed even when the object to be polished comes into contact with the holding surface, so that the first resin is suppressed. It is possible to prevent water from entering the layer and to secure the holding force to the object to be polished, and the rigidity of the holding surface is enhanced by the second resin layer, and holes or grooves are formed in the second resin layer. Since the adhesion to the object to be polished is limited, the object to be polished can be easily attached and detached.

In this case, the second resin layer can be formed of an emulsion type or solution type polyurethane resin having a tensile strength of 10 MPa or more. At this time, the 100% modulus of the polyurethane resin may be 10 MPa or less. Moreover, the coverage with respect to the surface of the skin layer of a 2nd resin layer can be made into the range of 50%-99%. A hole is formed in the second resin layer so as to partially expose the surface of the skin layer, and the hole is formed in a circular shape having a diameter of 2 mm or less and uniform in the holding surface. It may be. The thickness of the second resin layer may be in the range of 1 μm to 100 μm, and the thickness of the first resin layer may be in the range of 200 μm to 2000 μm. The second resin layer may be screen-printed on the skin layer of the first resin layer. Further, the object to be polished may have a surface area that contacts the holding surface of 10,000 cm ² or less.

  According to the present invention, since the second resin layer is disposed on the surface of the skin layer of the first resin layer, the damage to the skin layer is suppressed even when the object to be polished comes into contact with the holding surface, so that the first It is possible to prevent water from entering the resin layer and to secure a holding force for the object to be polished. The second resin layer increases the rigidity of the holding surface, and a hole or groove is formed in the second resin layer. As a result, the adhesion to the object to be polished is limited, so that the effect that the object can be easily attached and detached can be obtained.

It is sectional drawing which shows typically the holding material of embodiment to which this invention is applied. It is a top view which shows the formation pattern of the recessed part in the protective layer of a holding material, (A) shows the holding material of embodiment, and the formation pattern formed so that a circular recessed part may disperse | distribute uniformly, (B) is The holding material of another aspect is shown, and the formation pattern in which a grid-like groove is formed as a recess, and (C) shows the holding material of another aspect and the formation pattern in which a concentric groove is formed as a recess. . The positional relationship of a holding material and a to-be-polished object when evaluating the to-be-polished object holding | maintenance property of a holding material is shown typically, (A) is a top view, (B) is sectional drawing.

  Embodiments of a holding material to which the present invention is applied will be described below with reference to the drawings.

<Configuration>
As shown in FIG. 1, the holding material 10 of the present embodiment includes a polyurethane sheet 2 as a first resin layer made of polyurethane resin produced by a wet coagulation method, and a second disposed on the surface of the polyurethane sheet 2. And a protective layer 5 as a resin layer.

  The polyurethane sheet 2 has a skin layer 2a formed at the time of production by a wet coagulation method and having surface flatness, and a nap layer 2b formed on the inner side from the skin layer 2a. In the nap layer 2b, in a state in which cells (pores) 3 which are vertically long and rounded in the thickness direction (longitudinal direction in FIG. 1) of the polyurethane sheet 2 are distributed substantially evenly. Is formed. The length in the longitudinal direction of the cell 3 varies within the range of the thickness of the polyurethane sheet 2. In the vicinity of the skin layer 2a, a fine cell structure is formed in which a large number of cells 3 having a small length are formed. The cell 3 is formed such that the pore diameter on the skin layer 2a side is smaller than the pore diameter on the surface side opposite to the skin layer 2a (hereinafter, the surface opposite to the skin layer 2a is referred to as the back surface). That is, the diameter of the cell 3 is reduced on the skin layer 2a side from the back side. The polyurethane resin between the cells 3 is formed in a microporous shape in which a large number of micropores (not shown) having a pore diameter smaller than that of the cells 3 are formed. The skin layer 2a, the cells 3 and the fine holes (not shown) communicate with each other in a mesh shape through communication holes (not shown), and the polyurethane sheet 2 has a continuous cell structure as a whole. The thickness of the polyurethane sheet 2 can be adjusted in the range of 200 to 2000 μm, and is adjusted to 800 μm in this example.

  The protective layer 5 disposed on the surface of the skin layer 2a is formed of an emulsion type or solution type polyurethane resin. The emulsion-type polyurethane resin here is a polyurethane resin that is emulsified or suspended in a solvent insoluble in polyurethane resin such as water or alcohol. The solution-type polyurethane resin can be dissolved in an aqueous solvent such as water or alcohol, and becomes insoluble in an aqueous solvent after solidification due to a crosslinking reaction or the like. Further, in both emulsion type and solution type polyurethane resins, a solvent that does not dissolve the polyurethane sheet 2 is used. In this example, an aqueous emulsion type polyurethane resin is used. The protective layer 5 is formed so as to cover the surface of the skin layer 2a after the production of the polyurethane sheet 2 by the wet coagulation method. The surface of the protective layer 5 forms a holding surface S for holding an object to be polished. In the protective layer 5, a recess 5a is formed so as to penetrate the thickness of the protective layer 5, that is, from the holding surface S to the surface of the skin layer 2a. That is, since the protective layer 5 is formed on the surface of the skin layer 2a, the surface of the skin layer 2a is partially exposed. Further, since the skin layer 2a is left as it is formed by the wet coagulation method, the cell 3 formed in the nap layer 2b does not form a hole at the position of the holding surface S or the recess 5a. The thickness of the protective layer 5 can be adjusted in the range of 1 to 100 μm, and is adjusted to 50 μm in this example.

The recess 5a formed in the protective layer 5 can be formed as a hole or a groove, but in this example, it is formed as a circular hole. That is, as shown in FIG. 2A, on the holding surface S, the circular concave portions 5a are formed so as to be evenly dispersed. The size of the recess 5a can be adjusted with a diameter of 2 mm or less. The recess 5a is formed at a rate of 1 to 250 pieces / cm ² on the holding surface S. Although the protective layer 5 is formed so as to cover the surface of the skin layer 2a, the coating showing the ratio of the area where the protective layer 5 is formed to the total area of the surface of the skin layer 2a due to the formation of the recess 5a. The rate can be adjusted in the range of 50-99%. In this example, the circular recess 5a having a diameter of 1.5 mm is formed at a rate of 3 pieces / cm ² , and the coverage is about 95%. Further, in the protective layer 5 formed of an aqueous emulsion type polyurethane resin, the tensile strength (a numerical value obtained by dividing the maximum tension by the cross-sectional area) is 10 MPa or more. As this polyurethane resin, a resin having a 100% modulus (a numerical value indicating a tension when pulled twice) is 10 MPa or less. Thereby, the protective layer 5 can ensure the holding | maintenance force of a to-be-polished object in the appropriate range, suppressing the tearing and tearing of the skin layer 2a by external force.

  In the holding material 10, the double-sided tape 7 is bonded to the back side of the polyurethane sheet 2. The double-sided tape 7 has a base material such as a resin film having flexibility. As the substrate, polyethylene terephthalate (hereinafter abbreviated as PET), polyethylene (PE), polypropylene (PP), or the like can be used. In this example, a PET film is used. The base material has an adhesive layer (not shown) in which an adhesive is applied to both sides. As the pressure-sensitive adhesive for the pressure-sensitive adhesive layer, acrylic-based, urethane-based, and epoxy-based pressure-sensitive adhesives can be used. In this example, an acrylic pressure-sensitive adhesive is used. The double-sided tape 7 is bonded to the back surface side of the polyurethane sheet 2 via an adhesive layer on one side, and the adhesive layer on the other side is covered with a release paper 8. In this example, the base material of the double-sided tape 7 also functions to support the entire holding material 10.

<Manufacturing>
The holding material 10 is manufactured by forming a protective layer 5 and a recess 5a on the skin layer 2a side of a polyurethane resin sheet produced by a wet coagulation method, and bonding the double-sided tape 7 together. That is, a preparation process for preparing a resin solution in which a polyurethane resin is dissolved, a sheet formation process for coagulating the resin solution in an aqueous coagulation liquid to form a sheet-like polyurethane resin, and a washing / drying process for washing and drying the polyurethane resin The holding material 10 is manufactured through a coating process in which an aqueous emulsion type polyurethane resin is applied to the skin layer 2a side to form the protective layer 5 and the recess 5a, and a laminating process in which the double-sided tape is bonded. Hereinafter, it demonstrates in order of a process.

  In the preparation step, the polyurethane resin is dissolved by mixing the polyurethane resin, a water-miscible organic solvent capable of dissolving the polyurethane resin, and an additive. As the organic solvent, N, N-dimethylformamide (hereinafter abbreviated as DMF), N, N-dimethylacetamide (DMAc), or the like can be used. In this example, DMF is used. As the polyurethane resin, a polyester resin, a polyether resin, a polycarbonate resin or the like having a 100% modulus of 20 MPa or less is selected and used, for example, DMF so that the polyurethane resin is 30% by mass (wt%). Dissolve in. As the additive, a pigment such as carbon black for controlling the size and amount (number) of the cells 3, a hydrophilic activator for promoting cell formation, a hydrophobic activator for stabilizing regeneration of the polyurethane resin, and the like are used. it can. The obtained solution is degassed under reduced pressure to prepare a resin solution.

  In the sheet forming step, the resin solution prepared in the preparation step is continuously applied to the film forming substrate, and the resin solution is solidified in an aqueous coagulating liquid to form a sheet-like polyurethane resin. The resin solution is applied to the band-shaped film-forming substrate at a normal temperature by a coating apparatus so as to have a uniform thickness. In this example, a knife coater is used as the coating apparatus, and the coating thickness (coating amount) of the resin solution is adjusted by adjusting the gap (clearance) between the knife coater and the film forming substrate. In this example, in order to make the thickness of the polyurethane sheet obtained into the above-mentioned range, the coating thickness is adjusted to a range of 500 to 2000 μm. Although a flexible film, a nonwoven fabric, a woven fabric, or the like can be used as the film forming substrate, in this example, the film forming substrate is described as a PET film.

  The resin solution applied to the film forming substrate is guided into a coagulating liquid (water-based coagulating liquid) whose main component is water, which is a poor solvent for the polyurethane resin. As the coagulation liquid, an organic solvent such as DMF or DMAc can be mixed with water, but in this example, water is used. In the coagulation liquid, first, the skin layer 2a is formed on the surface side of the applied resin solution over a thickness of about several μm. Thereafter, the nap layer 2b is formed by the progress of substitution between the DMF in the resin solution and the coagulating liquid (water), and the polyurethane resin is regenerated into a sheet shape. When the DMF is desolvated from the resin solution and the DMF and the coagulating liquid are replaced, the cells 3 and fine pores (not shown) are formed in the polyurethane resin inside the skin layer 2a, and the skin layers 2a and 3 are not shown. A continuous cell structure is formed in which the micropores are connected in a network. At this time, since the PET film of the film formation substrate does not permeate water, desolvation occurs on the surface side (skin layer 2a side) of the resin solution, and cells 3 having a larger film formation substrate side than the surface side are formed. .

  In the cleaning / drying step, the regenerated band-shaped (long-length) film-forming resin is cleaned and then dried. That is, after the film-forming resin is peeled from the film-forming substrate, it is washed in a cleaning liquid such as water to remove DMF remaining in the film-forming resin. After cleaning, in this example, the film-forming resin is dried using a cylinder dryer provided with a cylinder having a heat source inside. The film-forming resin is dried by passing along the peripheral surface of the cylinder.

  When forming the protective layer 5, in this example, a screen printing method using a screen printer is used. In other words, the protective layer 5 is screen-printed on the skin layer 2 a of the polyurethane sheet 2. Specifically, a plate in which a hole pattern is formed in accordance with the formation pattern of the recess 5a is placed on the surface of the dried polyurethane sheet 2 on the skin layer 2a side. An aqueous solution in which an aqueous emulsion type polyurethane resin is dissolved in water is poured into a plate and stretched to a uniform thickness with a squeegee. The protective layer 5 and the recess 5a are formed by removing moisture in a heated atmosphere. The thickness of the protective layer 5 can be adjusted by the thickness of the plate and the concentration of the resin.

  In the laminating step, the surface opposite to the protective layer 5 of the polyurethane sheet 2, that is, the back surface side, and the double-sided tape 7 are bonded together. At this time, the pressure-sensitive adhesive layer on one side of the double-sided tape 7 and the back side of the polyurethane sheet 2 are bonded together. After the polyurethane sheet 2 and the double-sided tape 7 are bonded together, the sheet is cut into a desired size and shape. Then, an inspection such as confirming that there is no adhesion of scratches, dirt, foreign matter, etc. is performed, and the holding material 10 is completed.

  When polishing an object to be polished using the holding material 10, for example, a single-side polishing machine arranged so that the holding surface plate and the polishing surface plate face each other is used. A holding material 10 is attached to the holding surface plate, and a polishing pad is attached to the polishing surface plate. When the holding material 10 is attached to the holding surface plate, the release paper 8 is removed and the exposed adhesive layer is attached. When holding an object to be polished, the object to be polished is brought into contact with the holding surface S and pressed against the holding platen side. The object to be polished is held on the holding surface plate via the holding material 10. A polishing liquid containing abrasive particles is circulated and supplied between the processing surface of the object to be polished and the polishing pad, and the holding surface plate or polishing surface plate is rotated while applying polishing pressure to the object to be polished. Polish the polished object (processed surface).

<Action etc.>
Next, the operation and the like of the holding material 10 of the present embodiment will be described.

  In the present embodiment, the protective layer 5 is formed on the surface of the skin layer 2 a of the polyurethane sheet 2. In the protective layer 5, an aqueous emulsion type polyurethane resin is used, and the tensile strength is 10 MPa or more. Since it is an aqueous emulsion type polyurethane resin, water can be used as a solvent, and it is possible to avoid damage such as dissolution to the skin layer 2a when the protective layer 5 is formed. Since the tensile strength of the protective layer 5 is 10 MPa or more, damage to the surface of the protective layer 5 due to friction with an object to be polished during polishing can be suppressed. In addition, although the protective layer 5 has the recess 5a, the object to be polished is not in direct contact with the skin layer 2a, and as a whole, the deterioration of the surface of the skin layer 2a can be suppressed to protect the skin layer 2a. it can. In the conventional holding material that does not have the protective layer 5, the surface of the skin layer is damaged, so that the polishing liquid suddenly infiltrates into the polyurethane sheet, and the object to be polished is dropped or damaged. Furthermore, the polyurethane sheet and the double-sided tape May cause peeling. On the other hand, in the holding material 10, since the surface of the skin layer 2a is protected by the protective layer 5, it becomes difficult for the polishing liquid to enter the polyurethane sheet 2, and the stable holding property of the object to be polished is ensured for a long time. can do.

Further, the protective layer 5 is formed so that the circular recesses 5 a are uniform in the holding surface S. For this reason, even if air biting occurs between the object to be polished and the holding material 10 when holding the object to be polished, the recess 5a suppresses the storage of air between the holding surface S and the object to be polished. be able to. As a result, the object to be polished can be held flat, and the flatness of the object to be polished can be improved by polishing. In such a holding material 10, since the protective layer 5 of the aqueous emulsion type polyurethane resin is formed on the surface of the skin layer 2 a, the rigidity of the holding surface S is increased, and in other words, the holding power is improved. Limited. Thereby, even in polishing of a large-sized object having an area of 10,000 cm ² or more, it is possible to easily attach and detach the object to / from the holding material 10 while ensuring a minimum holding force for the object to be polished. It is possible to suppress damage due to bending of the object to be polished. Furthermore, since the damage to the object to be polished is suppressed, the stoppage of the polishing machine due to the damage to the object to be polished can be reduced, and the efficiency of the polishing process can be improved.

  Furthermore, in this embodiment, since the rapid penetration | invasion of the polishing liquid into the polyurethane sheet 2 which comprises the holding material 10 is suppressed, peeling with the polyurethane sheet 2 and the double-sided tape 7 can be suppressed. For this reason, since the retainability of the object to be polished is stabilized, the occurrence of uneven polishing on the object to be polished can be suppressed.

  In addition, in this embodiment, although the water-emulsion type polyurethane resin which has a tensile strength of 10 Mpa or more was illustrated as the protective layer 5, this invention is not limited to this. It is necessary to use an organic solvent as the solvent, and it is not preferable when the organic solvent may swell and dissolve the surface of the skin layer 2a when the protective layer 5 is formed. Further, if the tensile strength is less than 10 MPa, it is difficult to increase the rigidity of the holding surface S, and the restriction of the holding force on the object to be polished becomes insufficient. In addition, water-based emulsion type polyurethane resins having a 100% modulus of 10 MPa or less are used. When the 100% modulus exceeds 10 MPa, when the thickness of the protective layer 5 is 100 μm or less, the protective layer 5 becomes too hard and the adhesion between the workpiece and the holding material 10 is significantly impaired. It is not preferable because it causes a drop of the polished product. Therefore, any resin may be used as long as the tensile strength is 10 MPa or more and the 100% modulus is 10 MPa or less, thereby improving the durability on the holding surface S and ensuring the retention of the object to be polished. Can do. Examples of such a resin include an aqueous acrylic resin and latex.

  In the present embodiment, the example in which the coverage of the protective layer 5 on the skin layer 2a is adjusted to a range of 50 to 99% is shown, but the present invention is not limited to this. When the coverage is less than 50%, the surface of the skin layer 2a exposed at the position of the recess 5a may come into contact with the object to be polished, and the protective function of the protective layer 5 with respect to the skin layer 2a becomes insufficient. On the other hand, when the coverage ratio exceeds 99%, it becomes difficult to remove the air bitten between the holding surface S and the object to be polished when the object to be polished is held, and the air is stored. Therefore, the improvement in flatness of the object to be polished by the polishing process is hindered. Further, since the contact area between the holding surface S and the object to be polished becomes large, the object to be polished may be damaged when the object to be polished is removed. Therefore, in consideration of protection of the skin layer 2a and air removal, the coverage is preferably in the range of 50 to 99%.

  Furthermore, in this embodiment, although the example which makes the recessed part 5a circular shape with a diameter of 2 mm or less was shown, this invention is not limited to this. For example, as shown in FIG. 2B, a formation pattern in which lattice-like grooves are formed may be used, or as shown in FIG. 2C, a formation pattern in which concentric grooves are formed may be used. In the formation pattern in which such a groove is formed, in other words, in a pattern in which a portion where the resin for forming the protective layer 5 is not continuously applied is formed, the retention property on the object to be polished is reduced during the polishing process. there is a possibility. Therefore, in consideration of retention of the object to be polished, it is preferable that the circular concave portions 5a described above are formed so as to be evenly dispersed.

  Furthermore, in this embodiment, although the example which makes the thickness of the protective layer 5 the range of 1-100 micrometers was shown, this invention is not restrict | limited to this. If the thickness of the protective layer 5 is less than 1 μm, it is insufficient to protect the surface of the skin layer 2a. On the contrary, if the thickness exceeds 100 μm, the rigidity of the protective layer 5 itself becomes too high. Adhesion cannot be ensured. In other words, since the thickness of the protective layer 5 affects the rigidity of the holding surface S, the thickness of the protective layer 5 may be adjusted according to the size of the object to be polished. For example, when the thickness of the protective layer 5 is increased, the rigidity becomes high and suitable for a large object to be polished, but a small (small diameter) object to be polished may cause a decrease in retention. Moreover, when the thickness of the protective layer 5 exceeds 100 micrometers, even a 3 m class large-sized to-be-polished object may fall out from a holding material during grinding | polishing process. Therefore, it is preferable to adjust the thickness of the protective layer 5 within the above-mentioned range, considering the protection of the skin layer 2a and the adhesion to the object to be polished.

  Furthermore, in this embodiment, although the example which uses a screen printer for formation of the protective layer 5 and the recessed part 5a was shown, this invention is not restrict | limited to this. Any method may be adopted as long as the protective layer 5 is formed to have a uniform thickness and the concave portion 5a can be formed so as to partially expose the surface of the skin layer 2a. Good. An example of such a method is a transfer method using a gravure printing technique.

  Moreover, in this embodiment, although the polyurethane sheet 2 made from a polyurethane resin was illustrated, this invention is not limited to this. For example, a polyethylene resin or the like may be used as long as it has a cell structure in which a skin layer is formed by a wet coagulation method. In addition, for soft plastics (soft resins), the Japanese Industrial Standard (JIS K6900-1994 Plastics-Terminology) states that in the bending test or the tensile test if it cannot be applied under the specified conditions. Since it is defined as “plastic whose elastic modulus is not greater than 70 MPa”, any material satisfying this condition may be used.

  Further, although not particularly mentioned in the present embodiment, in order to make the thickness of the polyurethane sheet 2 uniform, a buffing process, a slicing process, or the like is performed on the surface opposite to the skin layer 2a of the polyurethane sheet 2, that is, the back surface side. You may do it. For example, when buffing is performed, a pressure welding jig having a flat surface is pressed against the surface of the film-forming resin after drying on the skin layer 2a side, and irregularities appearing on the back side may be removed by buffing or the like. .

  Next, examples of the holding material 10 manufactured according to the present embodiment will be described. In addition, it describes together about the holding material of the comparative example manufactured for the comparison.

Example 1
In Example 1, a polyurethane sheet 2 having a thickness of 800 μm was formed by a wet coagulation method, and a protective layer 5 having a thickness of 50 μm was formed on the surface of the skin layer 2a with an aqueous emulsion type polyurethane resin. The protective layer 5 has a diameter of 1.5 mm, and the concave portions 5a are formed on the holding surface S side at a rate of 10 pieces / cm ² to manufacture the holding material 10. In this holding material 10, the coverage of the protective layer 5 is 82%.

(Comparative Example 1)
In Comparative Example 1, a holding material was manufactured in the same manner as in Example 1 except that the protective layer 5 and the recess 5a were not formed. That is, Comparative Example 1 is a holding material having a conventional skin layer 2a.

(Evaluation)
About the holding material of each Example and a comparative example, to-be-polished material holding | maintenance property was evaluated. The retention property of the object to be polished was measured by the following method. As shown in FIG. 3, the holding material 10 is affixed to a surface plate 81 having a substantially flat surface, and a glass plate 82 of 10 cm long × 10 cm wide is placed on the surface (holding surface S) of the holding material 10. In order to reproduce the holding force with the holding material in the large-sized workpiece after placing the weight 83 so that a load of 80 gf / cm ² (784 mN / cm ² ) is applied to the substrate at 2 ° C. at 60 ° C. Adhesion was enhanced by sufficient pressure contact over time. The glass plate 82 was pulled in the horizontal (horizontal) direction (arrow A direction in FIG. 3), and the peak value (maximum value) of the tensile force when the glass plate 82 was displaced was measured. The measurement was performed 5 times, and the average value was calculated to evaluate the retention.

  In the holding material of Comparative Example 1 in which the protective layer 5 and the recess 5a are not formed, the average tensile force was 890 N in the measurement of 4 times out of 5 times, but the glass plate 82 was damaged in the measurement of 1 time. Data could not be obtained. This is because the holding material of Comparative Example 1 can hold the glass plate 82, but the adhesion between the glass plate 82 and the holding material is too large, so that the removal work after polishing becomes difficult, and the glass plate 82 is Probably damaged. On the other hand, in the holding material 10 of Example 1 in which the protective layer 5 and the recess 5a are formed on the holding surface S side, the peak value of the tensile force is 680 N, which is smaller than the holding material of Comparative Example 1, and the glass plate Did not damage it. Therefore, by forming the protective layer 5 and the recess 5a on the holding surface S side, the rigidity on the holding surface S is increased and the adhesion to the object to be polished is limited. It has been found that the possibility of damage when removing is reduced.

  Since the present invention provides a holding material that can secure the holding power to the object to be polished and facilitate the attachment and detachment of the object to be polished, it contributes to the manufacture and sale of the holding material. Have sex.

S holding surface 2 polyurethane sheet (first resin layer)
2a Skin layer 2b Nap layer 3 Cell 5 Protective layer (second resin layer)
5a Recess 10 Holding material

Claims (8)

A first resin layer made of a soft resin having a skin layer formed by a wet coagulation method and having many cells formed on the inner side of the skin layer;
A second resin layer disposed on the surface of the skin layer, the surface forming a holding surface for holding an object to be polished;
With
The holding material, wherein the second resin layer is formed with holes or grooves so as to partially expose the surface of the skin layer.   The holding material according to claim 1, wherein the second resin layer is formed of an emulsion type or solution type polyurethane resin having a tensile strength of 10 MPa or more.   The holding material according to claim 2, wherein the polyurethane resin has a 100% modulus of 10 MPa or less.   The holding material according to claim 1, wherein the second resin layer has a coverage of 50% to 99% with respect to the surface of the skin layer.   A hole is formed in the second resin layer so as to partially expose the surface of the skin layer, and the hole has a circular shape having a diameter of 2 mm or less, and is uniform in the holding surface. It is formed so that it may become. The holding material of Claim 4 characterized by the above-mentioned.   The thickness of the said 2nd resin layer is the range of 1 micrometer-100 micrometers, The thickness of the said 1st resin layer is the range of 200 micrometers-2000 micrometers, The holding material of Claim 1 characterized by the above-mentioned.   The holding material according to claim 1, wherein the second resin layer is screen-printed on a skin layer of the first resin layer. The holding material according to claim 1, wherein the object to be polished has a surface area that contacts the holding surface of 10,000 cm ² or more.

Images