JP2011224701A - Method of manufacturing material for polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a material for a polishing pad that has excellent homogeneity and smoothness as well as excellent durability.SOLUTION: The method of manufacturing the material for the polishing pad includes coating the surface of a porous layer composed of a polymer elastic body having openings with the solvent of the polymer elastic body and drying it. Further, it is preferable that the solvent to be coated on the surface is an organic solvent, that the coating method of the solvent is a gravure roll processing, and that the porous layer composed of the polymer elastic body is formed by a wet coagulation method.

Description

  The present invention relates to a method for manufacturing a polishing pad material, and more particularly to a method for manufacturing a polishing pad material that is optimally used for polishing in a substrate, a lens, liquid crystal glass, or the like used in precision equipment.

  In recent years, with the development of information processing technologies such as computers, high-precision surface finishing is required for magnetic recording media and silicon wafers. For example, when manufacturing a hard disk or the like of a magnetic recording medium, a polishing process is performed to smooth the surface of aluminum, glass, or the like. For this polishing process, a porous sheet of a polymer elastic body is widely used. The elastic body made of a polymer becomes more flexible by making it more porous, and becomes an abrasive cloth that can effectively prevent scratches on the polished article. And in the porous sheet-like material used at the time of this grinding | polishing process, higher homogeneity and smoothness have been requested | required. There is a demand for a material that can be processed to sufficiently satisfy the required characteristics for the finished polished product.

  As a porous sheet used for such a polishing process, for example, a production method is used in which a polyurethane foam is prepared and bonded to the surface of a support made of a film, a nonwoven fabric, a woven fabric, or the like (Patent Document). 1). However, when a wet coagulated polyurethane having excellent compression characteristics is used as the polyurethane foam, there is a problem that the smoothness is inferior. In view of this, for example, the above-mentioned patent document proposes a method in which the front surface or back surface is polished and smoothed in advance. However, the smoothness was still not satisfactory.

JP 2006-175576 A

  The objective of this invention is providing the manufacturing method of the raw material for polishing pads which is excellent in durability, while being excellent in homogeneity and smoothness.

The method for producing a polishing pad material of the present invention is characterized in that a solvent of a polymer elastic body is applied to the surface of a porous layer made of a polymer elastic body having an opening and dried.
Furthermore, it is preferable that the solvent applied to the surface is an organic solvent, the method of applying the solvent is gravure roll treatment, and the porous layer made of a polymer elastic body is formed by a wet coagulation method.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the raw material for polishing pads which is excellent in durability while being excellent in homogeneity and smoothness is provided.

In the method for producing a polishing pad material of the present invention, it is essential to apply a solvent of a polymer elastic body to the surface of a porous layer made of a polymer elastic body having an opening.
As a more specific method of the production method of the present invention, for example, a porous layer is formed on a sheet such as a film or a nonwoven fabric which is a substrate of a polishing pad material, and then the surface is subjected to polishing treatment or the like. This is a method in which a solvent of a polymer elastic body constituting the porous layer is applied to the surface of the porous layer made of the polymer elastic body having the opening.

  In the production method of the present invention, it is necessary to apply the solvent of the polymer elastic body constituting the porous layer of the surface layer of the polishing pad material to the surface as described above, but a preferable solvent is usually an organic solvent. As the organic solvent, dimethylformamide, methyl ethyl ketone, toluene and the like are common. Among them, in the production method of the present invention, it is preferable to use dimethylamide (DMF) which is known as a good solvent for the polymer elastic polymer for forming the porous layer. At this time, dimethylformamide alone may be used. However, in order to adjust the change of the surface form due to solvent coating, it is preferable to use a mixed solvent containing other organic solvent such as methyl ethyl ketone in addition to the good solvent dimethylformamide.

  Although various methods can be applied, a coating method using a gravure roll is preferably used because the amount of application can be easily adjusted and the change of the material surface due to the application can be finely adjusted.

  In the production method of the present invention, the surface state can be changed by changing the coating solution and the coating conditions in this way. For example, when dimethylformamide with good solubility is used alone for the coating solution, on the contrary, as the coating method, a gravure roll with a large count, that is, a roll with many meshes and small grooves is selected, and the amount of processing solution retained It is also possible to balance by lowering. At this time, usually, when dimethylformamide is mixed with another solvent such as methyl ethyl ketone, the content (weight ratio) of dimethylformamide is preferably in the range of 50 to 100% by weight, particularly 75 to 85% by weight. % Range is preferred. When the weight ratio of dimethylformamide is small, the surface of the macromolecular elastic polymer in which the porous layer is opened is difficult to dissolve, and the effects of the present invention tend not to be exhibited. Moreover, as a component other than dimethylformamide, an organic solvent such as methyl ethyl ketone may be used, or water or the like may be used in combination as long as mixing is possible.

Moreover, as a range of the coating amount of the solvent to the porous layer surface of a coating liquid, the range of 0.1-100 g / m < ² > is preferable, Especially preferably, it is preferable that it is 1-40 g / m < ² >. When the coating amount is too large, the coating liquid tends to penetrate not only into the surface of the opening of the porous layer but also into the pores. The coating solution that has penetrated inside tends to dissolve the porous walls in the porous layer and destroy the porous structure. When the wall between adjacent pores dissolves and disappears, a plurality of pores communicate with each other and become large pores. When the porous structure disappears in this way, when the polishing pad material is pressed during polishing, partial compression deformation failure, or the depression does not recover even when no pressure is applied, and the dent is generated. There is a tendency to be unable to polish smoothly. On the other hand, when the coating amount is too small, the smoothness improving effect of the present invention tends to be hindered by coating unevenness.

  In order to realize such a coating amount by the gravure method, the range of the mesh of the gravure roll to be used is preferably 70 to 300 mesh, and more preferably 150 to 220 mesh. If the mesh is made smaller, the depth of the groove is usually increased, so that the amount that the gravure roll holds the treatment liquid increases and it tends to be unevenly applied. On the contrary, when the mesh is increased, the number of meshes is increased, but the amount of processing liquid retained in each mesh is reduced for each groove, and a sufficient smoothing effect cannot be obtained.

  In the present invention, the solvent is applied and then dried, but the temperature is preferably in the range of 110 to 150 ° C, and most preferably in the range of 115 to 125 ° C when dimethylformamide and methyl ethyl ketone are used. By quickly evaporating the organic solvent after applying the treatment liquid, the polymer elastic body constituting the porous layer is re-dissolved more than necessary by the treatment liquid on the surface of the porous layer made of the polymer elastic body having openings. This is to prevent the pores of the opening from being blocked. By appropriately drying in this manner, re-dissolution of the polymer elastic body can be prevented and an opening on the surface of the porous layer can be ensured.

  The polishing pad material used in the production method of the present invention is a sheet having a porous layer made of a polymer elastic body having openings. Such a sheet is produced, for example, by forming an opening by forming a porous layer on a sheet such as a film or a non-woven fabric that is a substrate of a polishing pad material, and then polishing the surface. Can do.

  As a substrate (sheet) that serves as a support for the porous layer of this material, any form can be used as long as its form is a sheet-like material such as a nonwoven fabric, a woven fabric, or a film. In particular, a plastic having a uniform thickness and hardness. A sheet is preferable, and in order to achieve a uniform thickness of the polishing pad material, a film is preferable.

  Examples of the material constituting the substrate include materials such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polypropylene (PP), polyethylene (PE), and polycarbonate (PC). However, polyethylene terephthalate (PET) can be selected as a good material because of its homogeneity and ease of handling. When the substrate is in the form of a film, the thickness is preferably in the range of 10 to 300 μm, more preferably in the range of 100 μm to 250 μm.

  If the thickness of the film is thin, it tends to be difficult to break or wrinkle during subsequent film formation processing of the porous layer or the like. On the contrary, if it is thick, handling becomes easier and processability improves, but the resulting material has high rigidity, making it difficult to wind it up into a roll, and the resulting material is prone to curling. There is a concern that problems such as warping may occur after processing into a final polishing pad.

  Moreover, as a base | substrate used as the support body of the porous layer of this raw material, it is preferable that an adhesive layer exists on a sheet-like material. As the adhesive layer, a polymer elastic body is used, but it is preferable that a terminal contains a highly reactive crosslinking agent such as an isocyanate group.

  In particular, when a urethane resin is used for the porous layer, it is preferable that a cross-linking agent having a substituent highly reactive with the urethane group is present in the adhesive layer. This is because a cross-linking reaction occurs between the film constituting the substrate and the polymer elastic body forming the porous layer existing on the film, and peeling of the polishing pad material is less likely to occur.

  The thickness of the adhesive layer is preferably in the range of 5 to 50 μm, and more preferably in the range of 5 to 35 μm. When the thickness of the adhesive layer is too thin, there is a tendency to cause poor adhesion due to slight distortion or the like in a processing apparatus such as a coating apparatus. On the other hand, when it is too thick, the thickness of the adhesive layer affects the hardness of the material and tends to be undesirable. When the rigidity of a raw material becomes high, the workability at the time of winding in a roll shape tends to deteriorate. Furthermore, there is a tendency for problems such as warping to occur after the material is curled and processed into a final polishing pad.

  In the case where such an adhesive layer is formed, the drying temperature after coating is preferably 100 ° C. or less, particularly preferably 70 to 80 ° C., and the porous layer is formed thereon as soon as possible after the film formation. It is preferable to form a film. By drying at such a low temperature, it is possible to further improve the adhesion with the porous layer subsequently applied on the adhesion treatment liquid without completely drying the adhesion treatment liquid. Further, in the present invention, by performing such drying, it is possible to effectively suppress the application unevenness of the adhesive layer and the flow of the adhesive due to pressurization and heating, which are likely to occur when performing separate adhesive processing. It is. Also, if the adhesive layer is dried and then exposed to a high temperature before forming the porous layer, or if it is left for a long time, the reactive group of the crosslinking agent reacts in the same manner, which is not preferable. This is because peeling easily occurs between the porous layer and the adhesive layer.

  In the production method of the present invention, a polishing pad material having a porous layer made of a polymer elastic body having an opening on the surface thereof is used. This porous layer is preferably formed directly on the substrate layer described above or on the substrate layer and the adhesive layer. By directly molding in such a manner, it is possible to omit the peeling step after the formation of the porous layer, the bonding hole step, and the like, and to improve the smoothness.

  In addition, a process of creating and attaching a porous film separately as in the prior art may be adopted, but in this case, there is a difficulty that the thickness spots of the film, the adhesive layer, and the porous layer are easily added. . Conversely, when each layer is formed directly, the next layer is thick in the thin part of the previous step, and thinly applied to the thick part, thereby averaging the thickness and improving the smoothness. In addition, when applied directly, there is an effect of improving the fatigue property by compression without impairing the porous structure of the porous layer. This is because when a porous film is prepared separately, the porous structure tends to be lost in the peeling process, the bonding process, etc., and the skin layer on the front and back surfaces tends to be damaged.

  The following can be used as the polymer elastic body forming the porous layer. Examples include polyurethane elastomers, polyurea elastomers, polyurethane / polyurea elastomers, polyacrylic resins, acrylonitrile / butadiene elastomers, styrene / butadiene elastomers, among which polyurethane elastomers such as polyurethane elastomers, polyurea elastomers, polyurethane / polyurea elastomers, etc. It is preferable that These polyurethane elastomers are, for example, one or more polymer glycols selected from polyether glycols, polyester glycols, polyester ether glycols, polycaprolactone glycols, polycarbonate glycols and the like having an average molecular weight of 500 to 4000, and 4,4 Selected from organic diisocyanates such as' -diphenylmethane diisocyanate, xylylene resin isocyanate, triresin isocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate, and low molecular glycols, diamines, hydrazines, hydrazine derivatives such as organic acid hydrazides, amino acid hydrazides, etc. It is obtained by reacting a chain extender.

  The 100% modulus of the polymer elastic body used here is preferably between 2 and 30 MPa. When the modulus is too low, there are extremely few crystal components in the polymer elastic body, and it is difficult to use a stable film at the time of film formation, so that it tends to be difficult to use. On the other hand, if it is too high, on the contrary, there are many crystal components and elastic behavior is reduced, and the pressure distribution during processing becomes non-uniform, and when used for polishing, defects such as micro scratches occur on the surface of the object to be polished. It tends to be easy to do.

  Such a porous layer made of a polymer elastic body is formed by coating an organic solvent solution of a polymer elastic body on a substrate, preferably a substrate having an adhesive layer, and wet coagulating it in a coagulation bath containing water. Obtainable. At this time, it is preferable to add an additive for adjusting the porous structure in order to adjust the porous shape so as to be a cross-sectional porous structure consisting of a large pore and a microporous shape. The thickness of the porous layer is preferably in the range of 200 to 1000 μm, more preferably in the range of 500 to 900 μm.

  A porous layer made of a wet film-forming film made of such a polymer elastic body is excellent in surface adhesion and fit to an object to be polished, and exhibits a suitable cushioning property in the thickness direction. This contributes to the stabilization of the performance.

  Furthermore, in the polishing pad material used in the present invention, it is preferable to improve the surface smoothness by heating press after forming the porous layer or forming the opening by polishing or the like.

As for the conditions of the heating press, the temperature is preferably in the range of 60 to 130 ° C., and the pressure is preferably in the range of 1 to 5000 kg / cm ² , more preferably 1 to 10 kg / cm ² . Moreover, the compression rate in a press has the preferable range of 30 to 95% with respect to the thickness before a press. These conditions are preferably adjusted by looking at the finished surface after pressing. At a low temperature during the heat press treatment, the effect of improving the surface smoothness tends to be insufficient. On the other hand, if it is too high, the porous structure of the porous layer tends to be crushed, and the surface opening tends to be adversely affected. Moreover, when the numerical value of said compression rate is low, since the degree of compression is high, there exists a tendency for a porous structure to collapse. Conversely, when the numerical value of the compression ratio is high, it tends to be difficult to sufficiently increase the surface smoothness. As a method of hot pressing, a method of pressing between smooth metal rolls, a method of pressing with a smooth metal roll only on one side, a method of performing with a smooth film and a hot roll, or the like can be adopted.

  Then, the sheet-like material subjected to or not subjected to the heat press is further polished on the outermost surface, thereby exposing the pores on the surface and forming an opening. The opening allows the polishing liquid (slurry) to stably act on the object to be polished. Further, it is also preferable to perform a heat press after the opening.

  Further, the method for producing the polishing pad material will be specifically described. In order to open the surface of the porous layer, the abrasive grains are made so that the depth of the porous layer of the porous sheet is a predetermined length. Polishing processing of the porous sheet-like material is performed using the attached sandpaper. The count of sandpaper with abrasive grains can be appropriately selected from # 120 to # 1000 according to the polishing amount. As the polishing pad material, the pore diameter (opening diameter) of the porous layer surface is preferably in the range of 20 to 130 μm, more preferably 30 to 100 μm. When the pore diameter is small, there is a tendency that the slurry (polishing liquid) used in the polishing process is poorly circulated in the porous layer, and the shaving powder at the polishing process is clogged at the opening entrance or inside the porous part. In this case, the circulation of the slurry is hindered, and it takes time for the polishing process, and the object to be polished tends not to obtain a desired polished surface. Also, if the hole diameter is too large, the area of the polishing pad surface in contact with the object to be polished will decrease, and although the amount of slurry circulated will increase, the polishing rate will tend to decrease, leading to inefficiency in polishing processing. . This is because the amount of slurry that can exist between the surface of the porous layer and the object to be polished decreases, resulting in a decrease in the physicochemical grinding work.

  In the production method of the present invention, a solvent of a polymer elastic body is applied to the surface of a porous layer made of a polymer elastic body having such an opening and dried. The polishing pad material obtained by the production method of the present invention is coated with a polymer elastic solvent. For example, in the vicinity of the surface of the porous layer dissolved by the so-called gravure treatment, the microporous material existing before the gravure treatment is present. And there is only a large porous structure, and the polymer elastic body is enriched. The length of the solid portion of the polymer elastic body such as polyurethane is preferably in the range of 50 to 200 μm from the porous layer surface, and more preferably within 120 μm. Other porous layer portions have porosity.

  In such a polishing pad material, the surface of a porous layer made of a polymer elastic body having an opening is dissolved by a treatment liquid containing a solvent for the polymer elastic body to form a surface having a low surface roughness. Yes. The range of the surface roughness of the obtained polishing pad material is preferably 0 to 50 μm in terms of arithmetic average surface roughness (hereinafter referred to as Ra).

  And the raw material for polishing pads obtained by such a production method of the present invention can be suitably used for polishing. Especially, it is preferable to use for the grinding | polishing process in the base | substrate used for a precision instrument, a lens, liquid crystal glass, etc. As a method of polishing, there are a method of simultaneously performing polishing on both surfaces of an object to be polished and a method of performing polishing on only one surface while holding the object to be polished, which were obtained by the manufacturing method of the present invention. The polishing pad material is preferably used in any method.

  When using it for polishing, attach double-sided tape to the back side where the porous layer of the polishing pad material does not exist, cut it to the size suitable for the pressure platen of the polishing machine to be used, and use the surface plate of the polishing machine It can be used as a polishing pad by bonding with a double-sided tape.

  Hereinafter, the present invention will be described more specifically with reference to examples. The concentration was weight percent unless otherwise specified, and the arithmetic average surface roughness Ra was measured by the following method.

(1) Arithmetic average surface roughness Ra
Based on JIS B0601: 1994 with a surface roughness measuring instrument (Mitutoyo Co., Ltd., product number SJ-301), a cutoff value (λc: a component having a long wavelength (swell component or shape accuracy component) from the roughness curve cross-section curve) The length to be removed was 2.5 mm, the evaluation length was 12.5 mm, and the tip of the used measurement detector was R: 10 μm (SR10 detector).
Ra = 1 / L∫ | F (x) | dx
(Integration range 0 → L (L))

[Example 1]
As an adhesion treatment liquid, a weight ratio of 100: 10 is used as an adhesive that is a polymer elastic body (manufactured by Dainichi Seika Co., Ltd., polyester polyol-based adhesive, E-256) and isocyanate as a crosslinking agent. The adhesion processing liquid which mixed and adjusted with the solvent so that solid content concentration might be 25% was prepared.
Then, the above-mentioned adhesive treatment liquid is coated on a polyester (PET) film having a thickness of 190 μm under the condition of a clearance of 100 μm, and dried for 2 minutes with a dryer at 80 ° C., thereby forming a 25 μm adhesive layer on the polyester film. A base substrate once wound up was obtained. At the time of winding, the tackiness (tackiness) of the adhesive layer was lost. The thickness of the adhesive layer and the like was measured with a general thickness meter. Then, when the cross-sectional layer of the sampled sample was measured with an electron microscope and a microscope, the film thickness was 24 μm.

Next, 800 g of a 20% dimethylformamide (DMF) solution of a polyetherester polyurethane having a 100% modulus of 7 MPa and a silicone coagulation regulator added on the adhesive layer of the obtained base substrate. / M ² to coat. Thereafter, it was solidified in a water bath (coagulation bath) of a 10% DMF aqueous solution, sufficiently washed with water, and then dried at 140 ° C. to obtain a porous sheet.
The surface of the resulting porous sheet was buffed with # 150 sandpaper to form a sheet with openings distributed in the range of 30 to 70 μm in pore diameter excluding micropores on the surface. .
Further, using a roll press machine, the obtained sheet-like material was heated and pressed under the condition of a pressure of 5 kg / cm ² with the mirror roll heated to 120 ° C. to smooth the surface of the porous layer.

Next, dimethylformamide and methyl ethyl ketone were mixed at a mixing ratio of 80% / 20% to prepare a treatment liquid. Using a gravure roll treatment machine, a gravure roll mesh # 200 roll was used to carry out a gravure treatment on the surface of the porous layer having a smoothed opening, and a 20 g / m ² coating was applied. Subsequently, it dried at 120 degreeC and the hardening of the crosslinking agent in an adhesive agent was also advanced in parallel. When the cross-sectional structure was observed after drying, the thickness of the porous layer was 650 μm, and the length of the solid portion was 80 μm.
A double-sided tape was affixed to the surface of the obtained sheet where the porous layer did not exist, to obtain a polishing pad material. When the physical properties of the obtained polishing pad material were measured, the surface roughness of the polishing pad was as low as Ra = 4.53 μm and the frictional resistance value was as low as 0.29. Despite the fact that the contact area with the object to be polished was thought to be increased by improving the surface smoothness of the polishing pad, the frictional resistance was sufficiently low.
Moreover, when this polishing pad material was used for polishing, the surface roughness of the sapphire glass after polishing was Ra = 0.01 μm, which was higher due to the polishing pad obtained by the production method of the present invention. Surface smoothness was achieved.

[Example 2]
As the base substrate, a substrate obtained by impregnating a polymer elastic body into a nonwoven fabric was used instead of the polyester (PET) film. That is, a polyester non-woven fabric (weighing 340 g / m ² , density 0.34 g / cm ³ ) was impregnated with a 20% concentration solution of polyetherester polyurethane, solidified in a 10% DMF aqueous water bath, and sufficiently washed with water. After drying, it was dried at 140 ° C., and buffed with # 600 sandpaper to adjust the thickness, and a polyurethane-impregnated nonwoven fabric (weight per unit area 250 g / m ² , density 0.31 g / cm ³ ) was used. Moreover, this base substrate did not have an adhesive layer unlike a polyester film.
Except for using this base substrate, a porous layer having an opening is formed on the base substrate in the same manner as in Example 1, and subjected to hot pressing and gravure treatment, and the thickness of the porous layer is 600 μm. A polishing pad was obtained.
The surface roughness of the resulting polishing pad material is Ra = 5.21 μm, the frictional resistance is as low as 0.31, and the surface roughness of the polished sapphire glass is excellent at Ra = 0.02 μm. It was the raw material for polishing pads which can achieve the surface smoothness of the object to be polished (sapphire glass).

[Comparative Example 1]
A polishing pad material was obtained in the same manner as in Example 1 except that the gravure treatment was not performed on the surface of the porous layer. The surface roughness of the resulting polishing pad material is Ra = 6.71 μm, the frictional resistance is as high as 0.55, and the surface roughness of the polished sapphire glass is Ra = 0.05 μm It was a polishing pad material in which the surface smoothness of the body (sapphire glass) could not be sufficiently achieved.

[Comparative Example 2]
A polishing pad was obtained in the same manner as in Example 2 except that the gravure treatment was not performed on the surface of the porous layer. The surface roughness of the resulting polishing pad material is Ra = 7.79 μm, the frictional resistance value is as high as 0.57, and the surface roughness of the polished sapphire glass is Ra = 0.06 μm. It was a polishing pad material in which the surface smoothness of the body (sapphire glass) could not be sufficiently achieved.

Claims (4)

  A method for producing a polishing pad material, comprising: applying a solvent of a polymer elastic body to a surface of a porous layer made of a polymer elastic body having an opening, and drying.   The method for producing a polishing pad material according to claim 1, wherein the solvent applied to the surface is an organic solvent.   The method for producing a polishing pad material according to claim 1, wherein the solvent application method is gravure roll treatment.   The method for producing a polishing pad material according to any one of claims 1 to 3, wherein the porous layer made of a polymer elastic body is formed by a wet coagulation method.