JP5683194B2 - Holding pad - Google Patents

Description

  The present invention relates to a holding pad, and in particular, has a holding surface for holding an object to be polished, and a plurality of foams and a large number of fine holes are continuously formed by a wet film forming method. The present invention relates to a holding pad provided with a foam sheet having a foam structure.

  Conventionally, optical materials such as lenses, plane-parallel plates and reflecting mirrors, aluminum substrates for hard disks, silicon wafers for semiconductor devices, mother glass for liquid crystal displays, such as STN (Super-Twisted Nematic) liquid crystal and TN (Twisted Nematic) liquid crystal Polishing is performed in the manufacturing process of materials (substances to be polished) that require flatness with high accuracy, such as soda-lime glass and alkali-free glass of TFT (Thin Film Transistor) liquid crystal. Usually, for polishing these objects to be polished, a single-side polishing machine for polishing the objects to be polished one side at a time, a double-side polishing machine for simultaneously polishing both surfaces of the objects to be polished, and the like are used. In a single-side polishing machine, one surface of the object to be polished is held on a holding surface plate having a flat surface, and a polishing pad (slurry) is supplied to the object to be polished by a polishing pad affixed to the polishing surface plate having a flat surface. Polishing is performed on the other side (processed surface).

  In polishing processing using a single-side polishing machine, the parallelism between the holding surface plate and the polishing pad and the uneven load generated during polishing are absorbed, and the object to be polished is held on the holding surface plate almost flatly. The holding pad is attached to the holding surface plate. Usually, a polyurethane resin foam sheet formed by a wet film forming method is used for the holding pad. In the wet film-forming method, a resin solution in which a polyurethane resin is dissolved in a water-miscible organic solvent is applied to a sheet-shaped film-forming substrate, and then immersed in an aqueous coagulating liquid, so that the resin is solidified and regenerated into a sheet. The The obtained foamed sheet has a dense skin layer on the surface side that comes into contact with the object to be polished, is vertically long in the thickness direction inside the skin layer, and is opposite to the skin layer (hereinafter referred to as the back surface) side. It has a foamed structure in which a plurality of foams expanded in diameter and a large number of micropores having an average diameter smaller than the average diameter of the foam are continuously formed. By having such a foam structure, cushioning properties are exhibited during the polishing process, so that the object to be polished can be held substantially flat. Since the skin layer has a flat surface and excellent contact with the object to be polished, the object to be polished can be reliably held by fixing by water-filled adsorption. That is, the surface of the skin layer becomes a holding surface for holding the object to be polished.

  However, in the holding pad formed by the wet film forming method, during the polishing process, slurry having acidic or alkaline properties, elution components from the object to be polished, for example, alkali components eluted from the soda lime glass described above, are contained. In order to contact the skin layer, the skin layer may deteriorate when used for a long time. In addition, the elution component from the slurry and the object to be polished may gradually permeate through the deteriorated skin layer. When the elution component from the slurry or the object to be polished enters the foamed or fine pores formed inside the foamed sheet, the resin part of the foamed sheet is eroded from the inside of the foamed or fine pores by these chemical actions, and the foamed sheet Degradation progresses rapidly. Further, since the foamed sheet and the object to be polished are in sliding contact with each other in the polishing process, a shear stress is repeatedly applied to the foamed sheet. For this reason, the resin portion in which the micropores of the foamed sheet are easily broken, so that the so-called “cohesive failure” in which the foamed structure is destroyed and cannot be restored is likely to occur. When cohesive failure occurs, the cushioning property is impaired, so that the object to be polished cannot be held substantially flat.

  In order to avoid these problems, for example, as a technique for improving acid resistance and alkali resistance of the holding pad, for example, an elastic body made of vinyl chloride for holding a semiconductor in an air bag type polishing head is disclosed. (See Patent Document 1). In addition, a holding pad using a fiber of polyolefin or polyphenylene sulfide having acid resistance and alkali resistance is disclosed (see Patent Document 2).

JP 2007-324497 A JP 2009-88456 A

  However, in the technique of Patent Document 1, the object to be polished can be held on the surface of the elastic body due to the surface tension of water, etc., but the object to be polished is sufficiently retained as compared with the foamed sheet formed by the wet film formation method described above. However, it is difficult to suppress the lateral shift of the object to be polished. In patent document 2, it becomes difficult to suppress the lateral shift | offset | difference of a to-be-polished object during grinding | polishing by using a fiber material. If it is possible to maintain the cushioning and holding properties necessary for holding the object to be polished for a long period of time, that is, to suppress the deterioration of the foamed sheet due to acidity and alkalinity and maintain the foamed structure, the object can be stably polished for a long time. You can expect to hold things.

  An object of the present invention is to provide a holding pad that can hold an object to be polished stably for a long period of time in view of the above-mentioned cases.

In order to solve the above problems, a holding surface for holding an object to be polished is provided, and a plurality of foams are formed on the inner side of the holding surface by a wet film forming method, and the plurality of foams are interposed between the plurality of foams. In the holding pad having a foam sheet having a foam structure in which a large number of micropores having an average diameter smaller than the average diameter of the foam is continuously formed, the foam sheet is formed of a polyurethane-based first resin. And the ratio of the volume of the second resin present in the plurality of micropores to the volume of the micropores in the second resin having higher acid resistance or alkali resistance than the first resin is 30% or more. The second resin is formed by impregnating a foamed sheet having the foamed structure with a resin emulsion .

In the present invention, since the second resin is formed by impregnating the foamed sheet with the resin emulsion, the resin emulsion can be infiltrated into the micropores, and the polyurethane-based first resin is contained in the micropores of the foamed sheet. Since the second resin having higher acid resistance or alkali resistance is contained so that the ratio of the volume of the second resin to the volume of the micropores is 30% or more, the surface of the micropores is the second resin. By protecting the foamed structure, the deterioration of the holding surface or the foamed sheet inside due to the chemical action of the slurry supplied during polishing and the elution component from the object to be polished is suppressed, and the foamed structure is reinforced by the second resin. Therefore, even if a shearing stress is applied to the foamed sheet during polishing, the object to be polished can be stably held for a long time.

In this case, the second resin is formed so that a film is formed on the surface of a large number of micropores, and the ratio of the volume existing in the micropores is 70% or more with respect to the volume of the micropores. It is preferable . The diameter of the dispersed phase of the tree fat emulsion is preferably set to 1μm or less. Silicone rubber, fluoro rubber, chlorinated polyethylene rubber, chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylonitrile butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, ethylene-propylene rubber, chloroprene rubber, butyl rubber, styrene-butadiene rubber And at least one selected from butadiene rubber. The foam sheet preferably has a tensile strength retention of 80% or more before and after being immersed in an aqueous sodium hydroxide solution having a liquid temperature of 40 ° C. and a pH of 14 for 8 hours. The foam sheet preferably has a tensile strength retention of 80% or more before and after being immersed in an aqueous hydrochloric acid solution having a liquid temperature of 40 ° C. and a pH of 1 for 24 hours.

According to the present invention , since the second resin is formed by impregnating the foamed sheet with the resin emulsion, the resin emulsion can be infiltrated into the micropores, and the polyurethane-based first in the micropores of the foamed sheet. Since the second resin having higher acid resistance or alkali resistance than the above resin is contained so that the ratio of the volume of the second resin to the volume of the micropores is 30% or more, the surface of the micropores is the second. By the protection of the resin, deterioration of the holding surface or the foamed sheet due to the chemical action of the slurry supplied during polishing and the elution component from the object to be polished is suppressed, and the foam structure is the second resin. Therefore, even if shearing stress is applied to the foamed sheet during the polishing process, it is possible to obtain an effect that the object to be polished can be stably held for a long time.

It is sectional drawing which shows typically the holding pad of embodiment to which this invention is applied. It is process drawing which shows the outline of the manufacturing process of the holding pad of embodiment.

  Hereinafter, embodiments of a holding pad to which the present invention is applied will be described with reference to the drawings.

(Constitution)
As shown in FIG. 1, the holding pad 10 of the present embodiment includes a foam sheet 2 formed of a polyurethane-based first resin by a wet film forming method. The first polyurethane resin is a resin having a urethane bond in the main chain. In this example, a polyurethane resin is used. The foam sheet 2 has a holding surface P.

  The foam sheet 2 has a skin layer 4 formed at the time of wet film formation on the holding surface P side, and the thickness is uniform on the surface opposite to the holding surface P (hereinafter referred to as back surface Q). Is buffed. The foamed sheet 2 is formed in a state where a plurality of foams 3 having a triangular cross section rounded along the thickness direction are substantially uniformly dispersed. The foam 3 is formed such that the average pore diameter on the holding surface P side is smaller than the average pore diameter on the back surface Q side. That is, the diameter of the foam 3 is expanded on the back surface Q side from the holding surface P side. The plurality of foams 3 include a vertically long foam 3 over the entire thickness of the foam sheet 2 and a foam 3 having a length less than half of the thickness of the foam sheet 2. In the foam sheet 2, the back surface Q side is buffed, and at least a part of the plurality of foams 3 is opened on the buffed surface (back surface Q) side. In the polyurethane resin between the foams 3, a large number of fine holes 6 having an average pore diameter smaller than that of the foams 3 are formed. The equivalent circle diameter of the micropores 6 measured by binarizing the cross-sectional image of the foamed sheet 2 observed with an electron micrograph is set to 15 μm or less. The foam 3 and the fine holes 6 of the foam sheet 2 are communicated in a mesh shape with the communication holes. That is, the foam sheet 2 has a continuous foam structure. In the continuous foamed structure of the foamed sheet 2 formed by the wet film-forming method, the resistant resin 5 as the second resin is continuous on the surface of at least some of the fine holes 6. It exists to form a film. That is, a phase of the resistant resin 5 is formed in the micropore 6.

  Here, the resistant resin 5 will be described. The resistant resin 5 is continuously formed in a state where the surface of the fine hole 6 is substantially coated (a state of a film) through the communication hole. The resistant resin 5 forms a continuous phase. In the fine hole 6, the fine hole 6 in which the phase of the resistant resin 5 is formed in most of the single fine hole 6 and the fine hole 6 in which the phase of the resistant resin 5 is hardly formed are formed. . That is, the amount of the resistant resin 5 present in each micropore 6 varies depending on the thickness of the coating of the resistant resin 5. The filling rate of the resistant resin 5 into the large number of micropores 6 before the formation of the phase of the resistant resin 5 is set to 30% or more. The filling rate of the resistant resin 5 is expressed as a percentage of the volume of the resistant resin 5 to the volume of the voids of the numerous micropores 6 before the phase of the resistant resin 5 is formed.

A method for calculating the filling rate of the resistant resin 5 will be described. First, before forming the phase of the resistant resin 5, a cross-sectional photograph of the foam sheet is taken with a scanning electron microscope (SEM), and from the binarized image, the area of the fine hole 6 is defined as the equivalent circle diameter. 5 points out of the foam sheet 1 mm ² was measured, when the value of the mean and a, (the volume of the micropores 6) the volume of the gap portion of the formation before the micropores 6 resistant resin 5 is? pa ^3/6 expressed. Similarly, after forming the phase of the resistant resin 5, the pore diameters of the void portions (portions where the phase of the resistant resin 5 is not formed) of many micropores 6 are measured as equivalent circle diameters, and this average value is calculated as B When the volume of the gap portion of the micropores 6 after formation of resistant resin 5 is represented by πB ^3/6. Assuming that the volume of the resistant resin 5 is the difference in volume of the voids of the micropores 6 before and after the phase of the resistant resin 5 is formed, that is, π (A ³ −B ³ ) / 6, the resistant resin The filling rate of 5 is calculated by the formula of (A ³ −B ³ ) / A ³ × 100.

  The resistant resin 5 is formed of a resin having higher acid resistance or alkali resistance than the polyurethane resin forming the foamed sheet 2. For acid resistance, the tensile strength after dipping the foamed sheet 2 in which the phase of the resistant resin 5 is formed in a hydrochloric acid aqueous solution having a liquid temperature of 40 ° C. and pH 1 for 24 hours is A1, and the tensile strength before dipping in the aqueous hydrochloric acid solution is A1. When the strength is B1, the tensile strength retention represented by A1 / B1 × 100 is 80% or more. On the other hand, as alkali resistance, when the liquid temperature is 40 ° C. and the tensile strength after immersion in an aqueous sodium hydroxide solution at pH 14 for 8 hours is A2, and the tensile strength before immersion in the aqueous sodium hydroxide solution is B2, The tensile strength retention represented by A2 / B2 × 100 is 80% or more. Examples of such a resin include rubber materials. Specifically, silicone rubber, fluorine rubber, chlorinated polyethylene rubber, chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylonitrile butadiene rubber, hydrogenated acrylonitrile- At least one selected from butadiene rubber, ethylene-propylene rubber, chloroprene rubber, butyl rubber, styrene-butadiene rubber, and butadiene rubber is used. In this example, chloroprene rubber having higher acid resistance and alkali resistance properties than polyurethane resin is used as the resistant resin 5. When the resistant resin 5 excellent in acid resistance or alkali resistance is present in the fine holes 6, the resistant resin 5 functions to protect the foamed sheet 2.

  The resistant resin 5 is formed by impregnating the foam sheet 2 with a chloroprene rubber emulsion (resin emulsion). The diameter of the dispersed phase of the resin emulsion is set to 1 μm or less. The foam sheet 2 has a foam structure in which an opening 4 in which the foam 3 is opened is formed on the back surface Q side, and the foam 3 and the fine holes 6 are communicated with each other through the communication holes. By impregnating the emulsion, the resin emulsion can be infiltrated into the fine holes 6 through the foam 3 and the communication holes.

  In addition, the holding pad 10 has one side of the double-sided tape 7 for attaching the holding pad 10 to the polishing machine bonded to the back surface Q side. The double-sided tape 7 has a base material such as polyethylene terephthalate (hereinafter abbreviated as PET), and an adhesive is applied to both surfaces thereof. A release paper 8 is provided on the other surface side (lowermost surface side) of the double-sided tape 7.

(Manufacturing)
As shown in FIG. 2, the holding pad 10 includes a preparation step for preparing a resin solution in which a polyurethane resin is dissolved, a coating step for continuously applying the resin solution to a film forming substrate, and a polyurethane resin in an aqueous coagulating liquid. A coagulation regeneration process for coagulating and regenerating into a sheet shape, a cleaning / drying process for cleaning and drying the polyurethane resin that has been coagulated and regenerated, a grinding process for performing a grinding process so as to make the thickness uniform, and impregnating the foamed sheet 2 with a resin emulsion and drying It is manufactured through an impregnation / drying step, a laminating step of bonding the foam sheet 2 and the double-sided tape 7 together. Hereinafter, it demonstrates in order of a process.

  In the preparation step, 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. As the polyurethane resin, a resin having a 100% resin modulus in the range of 5 to 20 MPa is selected from polyester, polyether, polycarbonate, or the like. For example, the polyurethane resin is added to DMF so that the polyurethane resin becomes 30% by mass. Dissolve. Examples of additives include pigments such as carbon black, hydrophilic activators that promote foam formation, and hydrophobic activators that stabilize the coagulation regeneration of polyurethane resins in order to control the size and quantity (number) of foam 3. Can be used. The resulting solution is degassed under reduced pressure to obtain a polyurethane resin solution.

  In the application step, the polyurethane resin solution prepared in the preparation step is applied substantially uniformly to the belt-shaped film forming substrate at a normal temperature by an application device such as a knife coater. At this time, the application thickness (application amount) of the polyurethane resin solution is adjusted by adjusting the gap between the knife coater and the film forming substrate. Although a nonwoven fabric, a woven fabric, etc. can also be used for a film-forming base material, in this example, a PET film is used.

  In the coagulation regeneration process, the polyurethane resin solution applied to the film forming substrate in the application process is guided to a coagulation liquid (water-based coagulation liquid) whose main component is water which is a poor solvent for the polyurethane resin. In the coagulation liquid, first, a skin layer 4 having a thickness of about several μm is formed on the surface side of the applied polyurethane resin solution. Thereafter, the polyurethane resin coagulates and regenerates in a sheet form on one side of the film forming substrate by the progress of substitution between the DMF in the polyurethane resin solution and the coagulating liquid. When DMF is removed from the polyurethane resin solution and DMF and the coagulating liquid are replaced, foam 3 and a large number of micropores 6 are formed inside the skin layer 4 (in the polyurethane resin). A communication hole that connects the holes 6 in a mesh shape is formed. At this time, since the PET film of the film formation substrate does not allow water to permeate, desolvation occurs on the surface side (skin layer 4 side) of the polyurethane resin solution, and foam 3 having a larger film formation substrate side than the surface side is formed. The

  In the cleaning / drying process, the sheet-like polyurethane resin solidified and regenerated in the coagulation regeneration process (hereinafter referred to as a film-forming resin) is peeled off from the film-forming substrate, washed in a cleaning solution such as water and washed into the film-forming resin. Residual DMF is removed. After cleaning, the film forming resin is dried with a cylinder dryer. The cylinder dryer includes a cylinder having a heat source therein. The film-forming resin is dried by passing along the peripheral surface of the cylinder. The film-forming resin after drying is wound up in a roll shape.

  In the grinding process, a grinding process such as a buffing process is performed on the surface opposite to the skin layer 4 of the film forming resin. That is, the substantially flat surface of the pressure welding jig is brought into pressure contact with the surface of the skin layer 4 of the film forming resin, and buffing is performed on the opposite surface side of the skin layer 4. Thereby, the back surface Q in which at least a part of the plurality of foams 3 is opened is formed, and the thickness of the film forming resin is made uniform.

In the impregnation / drying step, a resin emulsion in which chloroprene rubber having acid resistance and alkali resistance is dispersed in a dispersion medium such as water is impregnated or coated on the film-forming resin after buffing. In the film-forming resin impregnated with the resin emulsion, the resin emulsion enters from the opening of the foam 3 formed on the back surface Q side, and enters the fine holes 6 through the foam 3 and the communication holes. That is, the film-forming resin is wetted with the resin emulsion. After impregnation, excess resin emulsion is squeezed out by a mangle roller under a low load. The amount of the resin emulsion remaining in the fine holes 6 depends on the size of the fine holes 6 and the distance from the foam 3 of the fine holes 6 but can be adjusted by adjusting the load of the mangle roller. . At this time, since the foam 3 is opened on the back surface Q side where the diameter has been expanded, when the foamed sheet 2 is impregnated with the resin emulsion, the resin emulsion immediately flows out of the opening in the foam 3, whereas the micropore 6 Then, most of the resin emulsion remains in the micropores 6 due to the surface tension of the resin emulsion. As a result, the resin emulsion hardly exists in the foam 3 and enters a large amount in the fine holes 6. Thereafter, the film forming resin is dried with a dryer. At this time, water or the like of the dispersion medium evaporates first in the resin emulsion, and the chloroprene rubber in the dispersed phase is solidified later. The filling rate is adjusted by repeating the same operation 2 to 5 times, and the foamed sheet 2 is formed in a state where the surface of the micropores 6 is almost coated with the resistant resin 5.

  In the laminating process, the one surface side of the double-sided tape 7 is bonded to the back surface Q of the obtained foamed sheet 2. The other side of the double-sided tape 7 is covered with a release paper 8. The holding pad 10 is completed by performing an inspection such as confirming that there is no adhesion of dirt or foreign matter.

(Function)
Next, the operation and the like of the holding pad 10 of this embodiment will be described.

  In this embodiment, the phase of the resistant resin 5 is formed in many micropores 6. In the resistant resin 5, chloroprene rubber having higher acid resistance and alkali resistance than polyurethane resin is used. Since the chloroprene rubber forming the resistant resin 5 has better acid resistance and alkali resistance than the polyurethane resin forming the foamed sheet 2, the surface of the micropores 6 is protected by the resistant resin 5. That is, even if the skin layer 4 deteriorates due to components such as slurry supplied during polishing and alkali eluted from the object to be polished, even if the skin layer 4 gradually penetrates into the micropores 6 through the deteriorated skin layer 4, resistance is maintained. The foamed sheet 2 is protected from the inside by the resin 5. Further, the resistant resin 5 also has a function of reinforcing the foam sheet 2 by being present in the fine holes 6. For this reason, even if shear stress is applied during the polishing process, the foamed structure is maintained, so that the object to be polished can be held stably for a long period of time.

  Moreover, in this embodiment, since the surface of the micropore 6 is protected by the resistant resin 5, deterioration due to chemical action of the elution component of the slurry and the object to be polished is suppressed. The influence which the elution component of a thing has on a foaming structure can be reduced. As a result, the holding pad 10 can be used without being limited by the liquid property of the object to be polished or the slurry, and the replacement frequency of the holding pad 10 itself is reduced by the amount that can be stably used for a long period of time, thereby improving the polishing efficiency. Improvements can be made.

  Furthermore, in this embodiment, the filling rate of the resistant resin 5 with respect to the numerous fine holes 6 before the formation of the resistant resin 5 is set to 30% or more. When the filling rate of the resistant resin 5 is less than 30%, the ratio of the slurry coming into contact with the surface of the micropores 6 is increased, and the protective function of the resistant resin 5 is insufficient, thereby suppressing the deterioration of the foamed sheet 2 due to the slurry. The effect to do is not obtained. Moreover, the function which reinforces the foam sheet 2 of the resistant resin 5 is not sufficiently exhibited, and it becomes difficult to suppress the destruction of the foam sheet 2 due to the shear stress repeatedly applied to the foam sheet 2 during the polishing process. For this reason, it becomes impossible to hold | maintain a to-be-polished object stably for a long period of time, and a to-be-polished object will remove | deviate from a holding pad and will be damaged.

  Furthermore, in this embodiment, the resistant resin 5 is formed by impregnation with a resin emulsion. The diameter of the dispersed phase of the resin emulsion is set to 1 μm or less. For this reason, when the resin emulsion penetrates to the fine holes 6 through the foam 3 or the communication holes, the resistant resin 5 can be continuously formed in the fine holes 6. In the present embodiment, the plurality of foams 3 are opened by the grinding process. For this reason, in the impregnation / drying step, the resin emulsion can be easily infiltrated into the fine holes 6 through the foam 3 and the communication holes.

  In the present embodiment, an example in which the phase of the resistant resin 5 is formed in the micropores 6 has been shown. However, the present invention is not limited to this, and the phase of the foam 3 is also at least partially. It may be formed. This can be realized by adjusting the size of the opening of the foam 3 on the back surface Q side, that is, adjusting the buff amount in the grinding process and adjusting the load of the mangle roller in the impregnation / drying process. . If it does in this way, the tolerance resin 5 can improve the function which reinforces a foaming structure more. Moreover, in this embodiment, although the example in which the filling rate of the resistant resin 5 with respect to the large number of micropores 6 before the formation of the phase of the resistant resin 5 is set to 30% or more is shown, the foamed structure is further reinforced. Is taken into consideration, it is more preferable that the filling rate of the resistant resin 5 is 70% or more.

  Moreover, in this embodiment, although the chloroprene rubber whose both acid resistance and alkali resistance property are higher than a polyurethane resin was illustrated as resistant resin 5, ie, resin used for a resin emulsion, this invention is not limited to this. Any material can be used as long as it is a material having higher acid resistance or alkali resistance than the polyurethane resin forming the foam sheet 2, in other words, a material having at least one of acid resistance and alkali resistance. Examples of such materials include fluorine rubber, chlorinated polyethylene rubber, chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, ethylene-propylene rubber, chloroprene rubber, butyl rubber, Mention may be made of at least one selected from styrene-butadiene rubber and butadiene rubber. When a material having only higher acid resistance than the polyurethane resin is used as the resistant resin 5, an acidic slurry can be used. On the other hand, when a material having only higher alkali resistance than the polyurethane resin is used, an alkaline slurry can be used.

  Furthermore, in this embodiment, although the example which uses water etc. as a dispersion medium of a resin emulsion was shown, this invention is not limited to this, If the polyurethane-type resin used for the foam sheet 2 is not melt | dissolved, Liquids other than water may be used. For example, a liquid containing alcohol or the like as a dispersion medium may be used. Moreover, in this embodiment, although the example which uses a resin emulsion for formation of the resistant resin 5 was shown, this invention is not limited to this. For example, a resin solution other than the resin emulsion may be used. In this case, it is preferable that the solvent used for the resin solution can dissolve the resin used for the resistant resin 5 and does not dissolve the polyurethane resin used for the foam sheet 2. Moreover, in this embodiment, although the example which makes the diameter of the dispersed phase of a resin emulsion 1 micrometer or less was shown, this invention is not restrict | limited to this, resin emulsion (dispersed phase) is fully in the micropore 6 In addition, considering the permeation without uneven distribution, the diameter of the dispersed phase is preferably 1 μm or less.

  Furthermore, in this embodiment, although the example which uses a polyurethane resin for the foam sheet 2 was shown, this invention is not limited to this, As long as it is a polyurethane system, you may use another resin. For example, a polyurethane graft copolymer or a polyurethane block copolymer may be used. In the present embodiment, the polyurethane resin used for the foam sheet 2 has a 100% resin modulus (tension when pulled twice) from 5 to 20 MPa from a resin such as polyester, polyether or polycarbonate. It is preferable to select and use these resins. In this way, the object to be polished can be held in close contact with the holding surface P of the holding pad 10. Further, even if the resistant resin 5 is contained in the fine holes 6, the cushioning properties necessary as a holding pad can be ensured.

  Furthermore, in the present embodiment, when the foamed sheet 2 is produced, the polyurethane resin is coagulated and regenerated, and then the film-forming substrate is peeled off, and the double-sided tape 7 is bonded. It is not limited. For example, after the polyurethane resin is solidified and regenerated, the double-sided tape 7 may be bonded without peeling off the film forming substrate. In addition, the polyurethane resin is solidified and regenerated on the film-forming substrate on which a resin having good adhesiveness has been applied in advance so that the film-forming resin and the film-forming substrate are not easily separated. Good. Further, when a non-woven fabric is used as the film forming substrate, it is difficult to peel off the film forming resin, and thus the film forming substrate may be dried as it is without being peeled off. Furthermore, as the double-sided tape 7, an adhesive may be applied to both sides of the base material, or it may be composed of only an adhesive without having a base material.

  Moreover, in this embodiment, although the example which buffs the back surface Q side of the foam sheet 2 in the grinding process was shown, this invention is not limited to this. For example, any method that can open the foam 3 may be used in addition to the buffing process in the grinding process. For example, you may perform the slice process etc. which used the slicing machine. Further, the sanding (dressing process) may be performed so light that the skin layer 4 is not removed on the holding surface P side, or the skin layer 4 may be removed by buffing or slicing the holding surface P side. When dressing or buffing is performed on the holding surface P, it becomes easy to remove the object to be polished from the holding pad after the polishing process, so that the object to be polished can be prevented from being damaged.

  Hereinafter, the Example of the foam sheet 2 manufactured according to this embodiment is described. In addition, it describes together about the foamed sheet of the comparative example manufactured for the comparison.

(Example 1)
In Example 1, polyester MDI (diphenylmethane diisocyanate) polyurethane resin was used as the polyurethane resin for producing the foam sheet 2. A polyurethane resin solution is prepared by adding 45 parts of DMF as a solvent and 40 parts of a DMF dispersion containing 30% by weight of carbon black as a pigment to 100 parts of a 30% by weight solution in which this polyurethane resin is dissolved. Was prepared. The obtained polyurethane resin solution was applied to a film-forming substrate and then coagulated and regenerated in a coagulating liquid. The film-forming substrate was peeled from the polyurethane resin after the coagulation regeneration, and after washing and drying, the back surface Q side was ground so that the thickness was uniform, and a foam sheet 2 having a thickness of 1 mm was obtained. The operation of impregnating and drying the polyurethane resin after grinding with a resin emulsion in which chloroprene rubber (manufactured by Denki Kagaku Kogyo Co., Ltd., LM-50) is dispersed in water and the like is repeated three times, and the phase of the resistant resin 5 is formed. The foam sheet 2 of Example 1 was obtained. At this time, the filling rate of the resistant resin 5 was 30%.

(Example 2)
In Example 2, the foam sheet 2 of Example 2 was produced in the same manner as in Example 1 except that the number of repetitions in the impregnation / drying process was increased and the filling rate of the resistant resin 5 was set to 70%.

(Comparative Example 1)
In Comparative Example 1, a foamed sheet of Comparative Example 1 was produced in the same manner as in Example 1 except that the phase of the resistant resin 5 was not formed in the polyurethane resin after the grinding treatment. That is, the foam sheet of Comparative Example 1 is a conventional foam sheet.

(Comparative Example 2)
In Comparative Example 2, a foamed sheet of Comparative Example 2 was produced in the same manner as in Example 1 except that the number of repetitions in the impregnation / drying process was reduced and the filling rate of the resistant resin 5 was 15%.

(Evaluation 1)
The tensile strength was measured about the foam sheet of each Example and the comparative example, respectively. In the measurement, a specimen piece cut out from each foamed sheet, that is, a strip-like specimen piece having a width of 10 mm (the thickness is 1 mm in all), and a tensile universal testing machine (manufactured by A & D Corporation, RTC-1210A). )It was used. The measuring method was measured by a method according to Japanese Industrial Standard (JIS K6550). Thereafter, the foamed sheets of Examples and Comparative Examples were immersed in an aqueous sodium hydroxide solution having a liquid temperature of 40 ° C. and a pH of 14 for 8 hours. After the immersion, the tensile strength of each foamed sheet was measured again. The tensile strength retention before and after being immersed in the sodium hydroxide aqueous solution was calculated. The measurement results of the tensile strength and the tensile strength retention are shown in Table 1 below.

  As shown in Table 1, the tensile strength retention rate was 66% in Comparative Example 1 where the resistant resin 5 was not formed, and 71% in Comparative Example 2 where the filling rate of the resistant resin 5 was 15%. In contrast, Example 1 in which the filling rate of the resistant resin 5 is 30% showed 89%, and Example 2 in which the filling rate of the resistant resin 5 was 70% showed 97%. That is, Comparative Example 1 showed the lowest value and Comparative Example 2 showed a higher value than Comparative Example 1, but showed a lower value than Examples 1 and 2. This is because the resistant resin 5 is not formed in Comparative Example 1 and the surface of the micropores 6 is not sufficiently covered with the resistant resin 5 in Comparative Example 2, so that both are in contact with the sodium hydroxide aqueous solution on the surface of the micropores 6. This is because the ratio is larger than those of Examples 1 and 2, and the deterioration of the foamed sheet, that is, the progress of hydrolysis cannot be suppressed. On the other hand, in Example 1, 2, the value higher than Comparative Example 1, 2 was shown, and all were 80% or more. This is considered to be because in Examples 1 and 2, the surface of the fine holes 6 was protected by the resistant resin 5, thereby suppressing the deterioration of the foam sheet 2. Thereby, Examples 1 and 2 are excellent in alkali resistance, and even if a shearing stress is applied to the foamed sheet at the time of polishing processing, it can be expected to perform polishing processing stable for a long period of time.

(Evaluation 2)
The tensile strength was measured about the foam sheet of each Example and the comparative example, respectively. In the measurement, a tensile universal testing machine (manufactured by A & D, RTC-1210A) was used. The measuring method was measured by a method according to Japanese Industrial Standard (JIS K6550). Thereafter, the foam sheets of Examples and Comparative Examples were immersed in an aqueous hydrochloric acid solution having a liquid temperature of 40 ° C. and pH 1 for 24 hours. After the immersion, the tensile strength of each foamed sheet was measured again. The tensile strength retention before and after immersion in the aqueous hydrochloric acid solution was calculated. The measurement results of tensile strength and the tensile strength retention are shown in Table 1 below.

  As shown in Table 2, the tensile strength retention rate was 70% in Comparative Example 1 where the resistant resin 5 was not formed, and 77% in Comparative Example 2 where the filling rate of the resistant resin 5 was 15%. On the other hand, Example 1 in which the filling rate of the resistant resin 5 was 30% showed 89%, and Example 2 in which the filling rate of the resistant resin 5 was 70% showed 92%. That is, Comparative Example 1 showed the lowest value and Comparative Example 2 showed a higher value than Comparative Example 1, but showed a lower value than Examples 1 and 2. This is because the resistant resin 5 is not formed in the comparative example 1 and the surface of the micropores 6 is not sufficiently covered with the resistant resin 5 in the comparative example 2, so that the ratio of contact with the hydrochloric acid aqueous solution on the surface of the micropores 6 is high. It is considered to be larger than Examples 1 and 2 because the deterioration of the foamed sheet, that is, the progress of hydrolysis cannot be suppressed. On the other hand, in Example 1, 2, the value higher than Comparative Example 1, 2 was shown, and all were 80% or more. This is considered to be because in Examples 1 and 2, the surface of the fine holes 6 was protected by the resistant resin 5, thereby suppressing the deterioration of the foam sheet 2. Thereby, Examples 1 and 2 are excellent in acid resistance, and even if a shearing stress is applied to the foamed sheet at the time of polishing processing, it can be expected to perform stable polishing processing for a long period of time.

  Since the present invention provides a holding pad that can hold an object to be polished stably for a long period of time, it contributes to the manufacture and sale of the holding pad, and thus has industrial applicability.

P Holding surface 2 Foam sheet 3 Foam 5 Resistant resin (second resin)
6 Micropore 10 Holding pad

Claims (6)

It has a holding surface for holding an object to be polished, and has an average smaller than the average diameter of the plurality of foams between the plurality of foams and a plurality of foams inside the holding surface by a wet film formation method. In the holding pad provided with a foam sheet having a foam structure in which a large number of micropores having a diameter are continuously formed, the foam sheet is formed of a polyurethane-based first resin, and the plurality of micropores within, are contained as the ratio of the volume of the high acid resistance or alkali resistance than the first resin a second resin is present in the second resin to the volume of the micropores is 30% or more The holding pad is characterized in that the second resin is formed by impregnating a foamed sheet having the foamed structure with a resin emulsion .   The second resin was formed so that a film was formed on the surface of the large number of micropores, and the volume ratio in the micropores was 70% or more with respect to the volume of the micropores. The holding pad according to claim 1. The holding pad according to claim 1 , wherein the resin emulsion has a dispersed phase diameter of 1 μm or less. The resin emulsion is silicone rubber, fluorine rubber, chlorinated polyethylene rubber, chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, ethylene-propylene rubber, chloroprene rubber, butyl rubber, styrene. The holding pad according to claim 3 , wherein the holding pad is made of at least one selected from butadiene rubber and butadiene rubber.   2. The holding pad according to claim 1, wherein the foamed sheet has a tensile strength retention of 80% or more before and after being immersed in a sodium hydroxide aqueous solution having a liquid temperature of 40 ° C. and a pH of 14 for 8 hours. 6. The holding pad according to claim 5 , wherein the foamed sheet has a tensile strength retention rate of 80% or more before and after being immersed in an aqueous hydrochloric acid solution having a liquid temperature of 40 ° C. and a pH of 1 for 24 hours.

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