JP5437894B2 - Method for producing perforated sheet - Google Patents

Description

  The present invention relates to a method for producing a porous sheet-like material, and more particularly to a method for producing a porous sheet-like material that is optimally used during smoothing processing 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 process of smoothing the surface of aluminum, glass or the like that is an object to be polished is performed. For this smoothing process, a porous sheet of a polymer elastic body is widely used. This is because, by making the elastic body made of a polymer more porous, it becomes more flexible and can effectively prevent scratches on the object to be polished. And in the porous sheet-like material used at the time of this smoothing process, higher homogeneity and smoothness have been required. There is a demand for a material that can be processed to sufficiently satisfy the required characteristics for the finished polished object.

  As a porous sheet used for such smooth processing, 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, nonwoven fabric, woven fabric or the like (for polishing). Patent Document 1 as a pad and Patent Document 2 as a suction pad). 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, there is a problem that the physical properties of the bonded portion are lowered due to the bonding, peeling occurs, and the durability is inferior.

JP 2006-175576 A JP 2006-62059 A

  An object of the present invention is to provide a method for producing a porous sheet-like product having excellent durability while being excellent in homogeneity and smoothness.

  In the method for producing a porous sheet-like product of the present invention, an adhesive treatment liquid containing a crosslinking agent and a polymer elastic body (A) is applied on a film and dried to form an adhesive layer. A solution comprising B) and an organic solvent is applied, and the polymer elastic body (B) is wet-coagulated in a coagulation bath containing water as a main component to form a porous layer.

  Furthermore, it is preferable that the crosslinking agent is an isocyanate-based crosslinking agent, and that the glass transition temperature Tg of the polymer elastic body (A) constituting the adhesive layer is 40 ° C. or higher. Moreover, it is preferable that the drying temperature of an adhesion processing liquid is 100 degrees C or less, and the drying temperature after wet coagulation is 90 to 120 degreeC. Further, it is preferable to polish the outermost surface or heat press the surface.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the porous sheet-like thing excellent in durability is provided while being excellent in homogeneity and smoothness.

  In the method for producing a porous sheet-like product of the present invention, an adhesive treatment liquid containing a crosslinking agent and a polymer elastic body (A) is applied on a film and dried to form an adhesive layer. It is essential to apply a solution comprising B) and an organic solvent, and to wet-coagulate the polymer elastic body (B) in a coagulation bath containing water as a main component.

  The film used in the production method of the present invention serves as a support for the adhesive layer and the wet coagulation layer, but is preferably a film made of a synthetic resin having a uniform thickness and hardness. Specifically, for example, as a synthetic resin film, mainly polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polypropylene (PP), polyethylene (PE), polycarbonate (PC), etc. Among them, polyethylene terephthalate (PET) is a good material because of its homogeneity, dimensional stability and ease of handling.

  The film thickness is preferably in the range of 10 μm to 300 μm, more preferably 50 μm or more, and particularly preferably in the range of 100 μm to 250 μm. If the thickness of the film is thin, the film will not have sufficient rigidity, and the porous sheet that has been molded or wet-coagulated as described later may be broken during film formation, wrinkled due to tension, etc. The uniform coating process tends to be difficult. On the contrary, when the film is thick, the handleability and processability are improved, but the rigidity of the finished porous sheet-like product tends to be too high. If the film is too thick, it may be difficult to wind, for example, when it is wound into a roll, or the resulting porous sheet is wrinkled and used for surface processing of an object to be polished. There is a tendency for defects such as warpage to occur.

  In the production method of the present invention, first, an adhesive treatment agent containing a crosslinking agent and a polymer elastic body (A) is applied onto such a film and dried to form an adhesive layer. As the polymer elastic body (A) used in the adhesive layer, a polymer elastic body used in a normal adhesive can be used, and a solvent-based adhesive is preferable. Moreover, it is preferable that it is an ester resin type adhesive, and it is especially preferable that it is a polyester polyol type adhesive. The glass transition temperature Tg of the polymer elastic body (A) constituting the adhesive layer is preferably 40 ° C. or higher. As an upper limit, it is preferable that it is 80 degrees C or less, especially Tg is the range of 60 degrees C or less. By setting it as such a temperature range, it becomes possible to implement | achieve the higher adhesiveness between the porous layer and the film which were wet-coagulated.

  And as an adhesion processing liquid used by the present invention, it is necessary to contain a crosslinking agent. The cross-linking agent having a high reactive group at the terminal can exhibit high adhesiveness and improve the durability of the porous sheet-like material.

  Further, this crosslinking agent is preferably an isocyanate crosslinking agent. In particular, when the polymer elastic body constituting the porous layer is a polyurethane resin, the isocyanate-based cross-linking agent can exhibit high adhesiveness. Furthermore, it is also preferable that the highly reactive substituent group in the crosslinking agent is a block type crosslinking agent blocked with a reaction blocking group. The dissociation temperature of the blocked reaction blocking group may be in the range of 80 to 180 ° C, and more preferably in the range of 110 ° C to 150 ° C.

  Such a block-type isocyanate cross-linking agent preferably used in the present invention is obtained by adding a blocking agent having active hydrogen to polyisocyanate, and the heating dissociates the blocking agent to generate an isocyanate group. It reacts with a functional group such as a group and cures. Examples of such blocked isocyanates include, for example, polyisocyanates such as aliphatic isocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclopentane diisocyanate. , 1,4-cyclohexane diisocyanate, 1,2-cyclosoxane diisocyanate and other aliphatic cyclic isocyanates, xylylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate and other aromatic isocyanates, Many alicyclic isocyanates such as forone diisocyanate and norbornane diisocyanate methyl, and their nurate compounds It can be used form and mixtures thereof. Examples of the blocking agent include aliphatic hydrocarbons such as halogenated hydrocarbons, methanol, ethanol, n-propanol, isopropanol, and benzyl alcohol, aromatic or heterocyclic alcohols, methyl ethyl ketone oxime, methyl isobutyl ketone oxime, and acetone oxime. And oximes such as cyclohexane oxime, and caprolactam.

  In the production method of the present invention, an adhesive treatment liquid containing such a crosslinking agent and the polymer elastic body (A) is applied onto a film and dried to form an adhesive layer. As the application amount of the adhesion treatment liquid, it is preferable to apply an amount such that the thickness of the adhesive layer after drying is 5 to 100 μm, and it is more preferable to apply so as to have a thickness of 5 to 35 μm. . This thickness can be adjusted by changing the coating amount of the treatment liquid and the solid content concentration. When the thickness of the adhesive layer is too small, adhesion failure or the like tends to occur due to a slight distortion of the apparatus in the coating process. On the other hand, if the thickness of the adhesive layer is too large, it tends to adversely affect the flexibility of the resulting porous sheet. The adhesive layer becomes too thick. The influence of the adhesive layer will affect the hardness of the material. For example, if the rigidity of the porous sheet-like material becomes too high, not only winding becomes difficult when winding in the roll process in the final process or in the middle process, but the final porous sheet has a curl. There is also a tendency for problems such as warpage to appear in the objects.

  Moreover, as drying conditions after application | coating of an adhesion | attachment processing liquid, it is preferable that drying temperature is 100 degrees C or less. In particular, the temperature is preferably 60 to 80 ° C., and the porous layer is preferably formed as soon as possible after the formation of the adhesive layer. 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. When dried at a temperature that is too high, the cross-linking agent tends to be deactivated and the adhesiveness tends to decrease. On the other hand, when the drying temperature is too low, the adhesive layer has tackiness and tends to cause defects in the next step such as winding.

  And in order to raise productivity, after providing an adhesive layer and drying, it is preferable to wind up the sheet | seat which consists of a film and an adhesive layer once. However, in this case, it is preferable not to leave in a high temperature atmosphere or a high humidity atmosphere for a long time, and it is preferable to store in a range of 5 to 25 ° C. which is room temperature. This is to maintain adhesiveness. On the other hand, in order to wind up, it is preferable that an adhesive layer does not have tackiness. This is because, when having tackiness (adhesiveness), peeling of the adhesive layer may occur when performing the step after winding, and the adhesiveness of the obtained sheet may be lowered.

  In the method for producing a porous sheet-like product of the present invention, a solution composed of the polymer elastic body (B) and an organic solvent is subsequently applied to the surface of such an adhesive layer, and in a coagulation bath containing water as a main component. It is necessary to wet solidify the polymer elastic body (B) to form a porous layer. In the present invention, high smoothness is achieved by directly forming a wet porous layer directly on the film and the adhesive layer without adopting a step of creating and attaching a porous film separately. In this case, the thickness of each of the film, adhesive layer and porous layer is added when pasted together, but by forming each layer directly, the next layer is thick and thin in the thin part of the previous step. It is considered that the thickness is averaged by being thinly applied to the part, and the smoothness is improved. Further, since it is applied directly, the physical properties are excellent without impairing the porous structure of the porous layer. In particular, it has the effect of improving fatigue by compression. When a porous film is separately prepared, the porous structure is often destroyed in the peeling step or the skin layer on the front or back surface is often damaged.

  In the present invention, first, a solution composed of the polymer elastic body (B) and an organic solvent is applied to the surface of the adhesive layer. As the application method, it is preferable to adopt a roll coat method or a knife coat method. More specifically, it is preferable to apply a coating treatment by applying an appropriate amount of the coating liquid on the adhesive layer formed on the film with a roll or knife having a predetermined clearance.

  Examples of the polymer elastic body (B) used for forming the porous layer include polyurethane elastomer, polyurea elastomer, polyurethane / polyurea elastomer, polyacrylic resin, acrylonitrile / butadiene elastomer, styrene / butadiene elastomer, and the like. However, among them, polyurethane elastomers such as polyurethane elastomers, polyurea elastomers, polyurethane / polyurea elastomers and the like are preferable. Further, for example, in the case of a polyurethane-based elastomer, one or more polymer glycols selected from polyether glycol, polyester glycol, polyester ether glycol, polycaprolactone glycol, polycarbonate glycol and the like having an average molecular weight of 500 to 4000, From organic diisocyanates such as 4,4'-diphenylmethane diisocyanate, xylylene resin isocyanate, triresin isocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and low molecular glycols, diamines, hydrazines, hydrazine derivatives such as organic acid hydrazides, amino acid hydrazides, etc. It is preferably obtained by reacting a selected chain extender.

  The polymer elastic body (B) to be used may be a single resin, but it is also preferable to use a blend of two or more resins. By using the blend, it becomes possible to adjust the elasticity and plasticity of the porous layer and control it to an optimal compression deformation state. For example, to control the deformation behavior of a porous layer, it is effective to change the balance of the constituent segment ratio (hard component, mid component, soft component) of the polyurethane resin, and this component segment ratio can be blended with various resins. It is also possible to adjust by the ratio.

  Moreover, as a physical property of the polymeric elastic body (B) used with the manufacturing method of this invention, it is preferable that the 100% modulus is 2-30 Mpa. Furthermore, the range of 2 to 10 MPa is preferable. This 100% modulus and the distribution of pores in the porous layer result in a porous sheet-like material more suitable for smoothing.

  The porous sheet-like material obtained by the production method of the present invention is such that the wet porous layer made of a polymer elastic body has an appropriate cushioning property in the thickness direction, thereby providing surface adhesion to the object to be polished. Improves fit and stabilizes performance as a porous sheet for polishing. If the 100% modulus is too small, the crystal component in the polymer elastic polymer is extremely small, and it is difficult to use a stable porous layer film at the time of film formation. On the other hand, when the 100% modulus is too large, there are many crystal components in the polymer, the elastic behavior is reduced, and the pressure distribution during smoothing tends to be non-uniform. For example, when used for polishing, defects such as micro scratches on the surface of the object to be polished tend to increase. By adjusting the 100% modulus in this way, it is possible to further optimize the deformation rate (compression rate) at the time of compression of the porous sheet-like material obtained in the present invention and the compression elastic modulus indicating the recovery property after compression. It becomes possible. This porous sheet-like material compression rate and compression modulus can be changed depending on the object to be polished using the porous sheet-like material, and the required characteristics (of the object to be polished) differ depending on the type of object to be polished by optimization. It is possible to obtain a porous sheet-like material in accordance with the surface roughness after polishing, waviness, edge shape, polishing rate, pad life, and the like.

  In the present invention, a solution containing such a polymer elastic body (B) is wet coagulated in a coagulation bath containing water as a main component to form a porous layer. During this wet coagulation, the porous state is adjusted. For this purpose, it is also preferable to add various additives for adjusting the porous structure to the solution of the polymer elastic polymer (B).

  When the polymer elastic body (B) is a polyurethane resin, it is preferable to use dimethylformamide (DMF) as the organic solvent in order to obtain wet porosity. As various additives used in this case, it is preferable to use a cellulose-based additive as a wet coagulation aid, a toner as a colorant, and the like in a polymer elastic body solution dissolved in DMF. Moreover, it is also preferable to use a solution to which a silicone-based hydrophilic agent or hydrophobic agent is added as an auxiliary agent for forming a wet porous structure of polyurethane.

  More specifically, for example, in the case of a polyurethane resin in which the polymer elastic body (B) is dissolved in DMF, DMF in the treatment solution is replaced with water in a coagulation bath, and wet coagulation film formation is performed. At this time, as the coagulation bath, an aqueous solution having a DMF concentration of 0 to 20%, preferably 0 to 10% is usually used. By immersing the sheet-like material coated with the solution in the coagulation bath, a porous layer having a cross-sectional porosity composed of a large tear-shaped or cylindrical hole and a microporous is formed. If the concentration of the organic solvent in water is too high, the coagulation rate becomes slow, and the surface smoothness tends to decrease. This is because the inside of the porous layer is in contact with a roll or the like in the manufacturing process while it is not solidified, so that the surface film of the porous layer is solidified due to the contact pressure with the roll, and surface irregularities are generated.

The apparent density of the porous layer after coagulation, is preferably in the range of 0.10 to 0.40 g / cm ^3, more preferably 0.15~0.35g / cm ^3. When the apparent density is too small, the deformation of the porous sheet-like material due to the pressure during the smoothing process increases, and the processing spots with a large cycle on the surface of the object to be polished tend to increase. This is because the stress during processing is difficult to stabilize because the stress dispersion becomes large. On the other hand, when the density is too high, the deformation rate when the porous layer is compressed tends to be small, and the processing spots having a small cycle on the surface of the object to be polished tend to be large. This is because the resilience of the porous sheet-like material is increased during the polishing process, but partial stress concentration inevitably occurs, and polishing proceeds only in that portion.

  In the production method of the present invention, it is preferable to remove the organic solvent such as DMF remaining in the pores from the porous layer by wet coagulation to form a porous layer and then immersing in water or warm water. Furthermore, the obtained porous sheet-like material is subjected to a drying treatment to become a sheet-like material.

  As drying temperature in the drying process of this porous sheet-like material, 90-120 degreeC is preferable and 100-120 degreeC is more preferable. When the porous layer is formed by wet coagulation, the organic solvent such as dimethylformamide in the polymer elastic body solution is replaced with water. However, when it is dried at a low temperature, the water remaining in the porous layer is sufficiently evaporated. The drying time becomes very long and the production efficiency tends to decrease. On the other hand, when the drying process is performed at a high temperature, the organic solvent such as dimethylformamide remaining in the porous layer tends to boil and evaporate, and the quality tends to deteriorate. The organic solvent may be redissolved on the surface and the inside of the formed porous layer to close the pores and deteriorate the surface smoothness. The drying temperature is particularly preferably in the range of 100 ° C to 120 ° C. Some organic solvents (for example, toluene, methyl ethyl ketone, ethyl acetate, etc.) are also contained in the crosslinking agent, etc., but the evaporation of these organic solvents can be promoted and the amount of residual solvent in the sheet-like material can be reduced. Because. In addition, the substituent group in the cross-linking agent that has not been reacted by drying reacts with the urethane group in the polymer elastic body, thereby strengthening the adhesive strength between the porous layer and the adhesive layer, and between the adhesive layer and the film. It becomes.

  As the porous state of the porous layer of the porous sheet-like material obtained by the production method of the present invention, it is particularly preferable to form a cross-sectional porosity composed of large tear-shaped pores and micropores. The thickness is preferably in the range of 200 to 1000 μm, more preferably 300 to 900 μm. By setting it as such a shape, the elasticity modulus suitable for the smoothing process can be obtained. A large porosity is deformed at the time of a small deformation, and a load applied to the object to be polished can be controlled continuously with respect to various stresses by a micro-porosity at the time of a large deformation and an elastic deformation that the elastic body has. The wet film-forming film made of a high-molecular elastic polymer improves the surface adhesion and fit to the object to be polished by giving an appropriate cushioning property in the thickness direction. In particular, the polishing accuracy of an object to be polished can be improved by using it as an adsorption pad or a polishing pad.

  The mechanism by which the excellent porous sheet-like material is obtained by the production method of the present invention is not clear, but the crosslinking agent contained in the adhesion treatment liquid and the polymer elastic body (B) to be wet-coagulated in the porous layer, It is considered that a crosslinking reaction is important. For example, when the adhesion treatment liquid is an organic solvent solution and does not contain water, a crosslinking reaction occurs with the polymer elastic body (B) constituting the porous layer, but coagulation mainly comprising water during the subsequent wet coagulation. It is considered that the excess cross-linking agent is deactivated in the bath, and the physical properties of the porous sheet-like material are kept moderately flexible without being hardened more than necessary by subsequent drying or the like. Furthermore, the cross-linking agent causes a cross-linking reaction with the polymer elastic body (A) or the like of the adhesive layer and improves the adhesive force.

  In addition, when a crosslinking agent such as a blocked isocyanate in which a crosslinking reactive group is blocked is used as a preferred embodiment, an excellent porous sheet-like material is obtained by performing the drying temperature of the adhesion treatment liquid at a temperature lower than the dissociation temperature. Is considered to be obtained. The reactive group in the blocked crosslinking agent remains blocked even in a coagulation bath containing water, and the reactive group remains even during wet film formation. Then, when the moisture is removed at the time of subsequent drying and the material temperature becomes 100 ° C. or higher and the dissociation temperature of the reaction blocking group is reached, the reactive group in the crosslinking agent becomes free and forms a porous layer (B) A cross-linking reaction between the film and the porous layer composed of the polymer elastic polymer (B) is prevented by the adhesion treatment liquid containing the cross-linking agent and the polymer elastic body (A). It can exhibit strong adhesive strength.

  Thus, the smoothness of a porous sheet-like material becomes important as a factor of the accuracy of the smoothing process of the porous sheet-like material obtained by the production method of the present invention. Therefore, after forming a porous layer on the surface, it is also a preferable method to improve the smoothness of the surface by heating press.

  As a method of heat-pressing the surface, a method of pressing and applying heat and pressure uniformly on a flat plate for each porous sheet-like material, or a surface of a porous sheet-like material on a metal roll with a flat surface The method of pressing and performing a heat press etc. can be mentioned. Further, the method of hot pressing using a metal roll in a sheet state is preferable because of good productivity. When using a metal roll, in addition to the method of pressing between two smooth metal rolls, a method of pressing only one of the metal rolls with a smooth metal roll can also be employed.

  A more preferable heating press method is a film pressing method in which a smooth film is placed in contact with the porous layer and heated from the opposite side of the porous layer of the film. As a more specific method of this film press, for example, an adhesive layer and a porous layer are formed on a film that becomes a substrate of a porous sheet material, and then a smooth synthetic resin film surface is adhered to the surface of the porous layer. The method of applying heat and applying pressure through a metal plate or metal roll can be mentioned. By this film press processing, the shape of the surface of the synthetic resin film having a low surface roughness can be transferred to the surface of the porous layer, and the surface roughness unevenness of the porous sheet can be made to a very low level. . In order to improve the smoothness, the surface of the synthetic resin film used for the film press is preferably smooth.

  Further, at this time, a continuous (continuous processing) or discontinuous (batch processing) process can be adopted as the processing process, and continuous processing is preferable from the viewpoint of productivity.

  The type of synthetic resin film that can be used in this film pressing step can be selected depending on the processing time in the process, the heating roll temperature, the tension applied to the synthetic resin film in the process, and the like. Examples of such synthetic resin film materials include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polypropylene (PP), polyethylene (PE), and polycarbonate (PC). Is mentioned. Among these, polyethylene terephthalate (PET) is particularly preferable from the viewpoint of its homogeneity, ease of handling, and heat resistance.

  The preferred thickness of the synthetic resin film is preferably in the range of 0.10 mm to 0.50 mm, and more preferably in the range of 0.15 mm to 0.30 mm. When it is thin, there is a problem that deformation of the synthetic resin film during pressurization is large and wrinkles or the like easily enter the film surface. In such a case, wrinkles and the like are transferred to the porous layer of the porous sheet-like material, which tends to be a defect. If it is too thick, there is a problem that the heat transfer rate from the heated metal roll or metal plate is lowered. There is a tendency that transfer of the smooth synthetic resin film surface to the porous sheet-like material is insufficient.

  As a thing heated while making it closely_contact | adhere to the back surface of a synthetic resin film, the product made from a metal with favorable thermal conductivity and being hard to thermally expand is preferable. As the shape, a roll shape, a plate shape or the like can be adopted, but in order to further improve the surface roughness, the surface shape is preferably a mirror surface. In addition, when performing heat treatment, it is preferable to apply pressure at the same time, and for that purpose, the side where the porous layer of the substrate does not exist, that is, the opposite side of the film used in the film press, is brought into contact with the support and held. preferable. By using such a support, it becomes easy to heat and pressurize while maintaining a planar state. The time during which the pressing film surface is in close contact with the suction pad material can be lengthened. The support may be a metal roll or a metal plate, but it is preferable to use a sheet-like material such as a felt-like material, a woven or knitted fabric, or a mesh-like material.

  As heating temperature, 60-200 degreeC is preferable, and 100-180 degreeC is more preferable especially. If the temperature is low, even if the heat contact time is long, the smooth transfer of the synthetic resin film surface is not sufficient, and the desired smoothness tends not to be obtained. Further, when the temperature is high, the surface of the porous sheet-like material is excessively softened and tends to cause problems such as being fused to a synthetic resin film and being unable to be peeled off after passing through the process.

The applied pressure at the time of heat pressing is preferably in the range of 1 to 10 kg / cm ^2, more preferably 4~8kg / cm ^2. If the pressure is low, the surface of the synthetic resin film cannot be transferred sufficiently and the desired surface roughness tends to be not obtained. Conversely, when too high, it exists in the tendency for peeling from a synthetic resin film after processing to become difficult. There is a tendency to cause problems such as process passability and peeling of the surface of the porous layer.

  In addition, it is necessary to contact the surface of the synthetic resin film in close contact with the surface of the porous layer at the time of heating press, but after heat is applied for a certain period of time, it is cooled for a certain period of time to promote heat fixation. It is preferable. The cooling time is preferably 5 minutes or longer. The heating temperature and cooling temperature are determined according to the properties of the elastic polymer, such as the glass transition temperature and the flow start temperature, with reference to the molecular weight of the elastic polymer (B), the type of polymer, the degree of crosslinking, etc. can do.

  As a preferred embodiment of the present invention, the finished surface can be adjusted more smoothly by hot pressing the surface. Moreover, the compression rate in a press has the preferable range of 30 to 95% with respect to the thickness before a press. When the heating temperature is too low, the effect of improving the smoothness of the surface cannot be obtained sufficiently. On the other hand, when the heating temperature is too high, the porous structure of the porous layer is crushed and the performance tends to deteriorate. Also, when the compression is excessive, the porous structure is crushed in the same manner, and when the compression is small, the effect of improving the surface smoothness cannot be obtained so much.

  The porous sheet-like material obtained by the production method of the present invention can be used for processing purposes such as smoothing. By the way, among the smoothing processes, as a smoothing process for a substrate, a lens, liquid crystal glass, etc. used in precision equipment, a method of performing polishing simultaneously on both sides of the object to be polished, and a single side while holding the object to be polished There is a method for carrying out the polishing process only. The porous sheet-like material obtained in the present invention can be used as a polishing pad or a suction pad for holding an object to be polished in the smoothing process for these precision instruments.

  When using the obtained porous sheet-like material as a polishing pad, it is preferable to further polish the outermost surface. By thus exposing the pores on the surface and forming the openings, the polishing liquid (slurry) can be stably applied to the object to be polished. Further, since smoothness on the surface is important as a factor of polishing accuracy, after the porous layer is formed, the surface smoothness is improved by the above-mentioned hot press, and then the surface is opened. It can also be used.

  Further, a method for producing a polishing porous sheet (polishing pad) for polishing purposes will be described in detail. In order to open the surface of the porous layer, the depth of the porous layer of the porous sheet is determined as follows. In this method, the porous sheet-like material is polished using a sandpaper with abrasive grains so as to have a predetermined length. The count of sandpaper with abrasive grains can be appropriately selected from # 120 to # 1000 according to the polishing amount. In the case of a polishing pad, the pore diameter (opening diameter) on the surface of the porous layer 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.

  On the other hand, when the obtained porous sheet-like material is used as an adsorption pad, since the fine pores are already opened on the wet porous surface, the porous sheet-like material of the present invention is used as it is without polishing the surface. Can do. Furthermore, it is preferable to perform a smoothing process such as the heating press described above. Since the suction pad is intended to be sucked and held, it is particularly effective to improve the adhesion to the workpiece by smoothness. In particular, for single-side polishing using an adsorption pad, high homogeneity and smoothness are required, and the porous sheet-like material obtained by the production method of the present invention is effective. This is because in recent years, the demand for products using liquid crystal glass has soared, and the size of liquid crystal glass has also increased in size, and the accompanying increase in the size of polishing machines. The porous sheet-like material obtained by the production method of the present invention can meet the requirements at a high level.

  The porous sheet-like material obtained by the production method of the present invention is obtained by adhering a double-sided tape to the side where the porous layer of the film does not exist, and adhering to the surface plate of the smoothing machine using the double-sided tape. For example, it can be used as the above-mentioned polishing pad or suction pad.

  Hereinafter, the present invention will be described more specifically with reference to examples. The concentration is weight percent unless otherwise specified.

[Example 1]
As an adhesion treatment liquid, a polyester polyol adhesive (E-256, manufactured by Dainichi Seika Co., Ltd.) which is a polymer elastic body (A) and an isocyanate which is a cross-linking agent are set to a weight ratio of 100: 12. The solution which mixed and adjusted with the solvent so that solid content concentration might be 25% was prepared.
Then, on the polyester (PET) film having a thickness of 150 μm, the above-mentioned adhesive treatment liquid comprising a polyester polyol adhesive is coated under a condition of clearance of 100 μm, and dried for 2 minutes with an oven at 80 ° C. A 25 μm adhesive layer was formed, and 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, 750 g of a 20% dimethylformamide (DMF) solution of a polyether ester polyurethane having a 100% modulus of 7 MPa and a silicone coagulation regulator added on the adhesive layer of the base substrate thus obtained. / 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. When measured by sampling, the thickness of the porous layer was 600 μm.
A double-sided tape was affixed to the surface of the porous sheet-like product on which the porous layer of the polyester film or the like was not coated, to obtain an adsorption pad for fixing the object to be polished during polishing. When the obtained suction pad was used, the surface smoothness, the suction force, and the processing spots were excellent.

[Example 2]
A porous sheet-like material was obtained in the same manner as in Example 1 except that the porous layer coating of Example 1 was changed from 750 g / m ² to 800 g / m ² .
The surface of the obtained porous sheet was buffed with # 150 sandpaper to form openings distributed in the surface with pore diameters in the range of 30 to 70 μm excluding micropores, and used as a polishing pad. . As a result of sampling and measurement, the thickness of the porous layer was 540 μm. When the obtained polishing pad was used, the polishing rate was excellent and scratch scratches were small. However, some swells and disturbances in the shape of the end portions occurred.

[Example 3]
A porous sheet was obtained in the same manner as in Example 1 except that the 100% modulus of the polyurethane used for coating the porous layer in Example 1 was changed from 7 MPa to 6 MPa.
In a state where the porous layer surface of the obtained porous sheet-like material is in close contact with the surface of a smooth polyester film having a thickness of 0.25 mm, it is heated from the back side of the polyester film to 150 ° C. through a metal roll and pressurized. A heated film press treatment was continuously performed at a pressure of 5 kg / cm ² for 6 minutes to obtain a final porous sheet. When measured by sampling, the film thickness of the adhesive layer was 23 μm, and the film thickness of the porous layer was 570 μm.
A double-sided tape was affixed to the surface of the porous sheet-like product on which the porous layer of the polyester film or the like was not coated, to obtain an adsorption pad for fixing the object to be polished during polishing. When the obtained suction pad was used, the surface smooth state, the suction force, and the processing spots were excellent, and in particular, the surface smooth state and the suction force were superior to those of Example 1.

[Example 4]
A porous sheet was obtained in the same manner as in Example 1 except that the 100% modulus of polyurethane used for coating the porous layer of Example 2 was changed from 7 MPa to 6 MPa.
In a state where the porous layer surface of the obtained porous sheet-like material is in close contact with the surface of a smooth polyester film having a thickness of 0.25 mm, it is heated from the back side of the polyester film to 150 ° C. through a metal roll and pressurized. A heated film press treatment was performed continuously at a pressure of 5 kg / cm ² for 6 minutes.
Further, the surface of the obtained porous sheet was buffed with # 150 sandpaper to form a polishing pad with openings distributed in the range of 30 to 70 μm in pore diameter excluding micropores on the surface; did. When measured by sampling, the film thickness of the adhesive layer was 23 μm, and the film thickness of the porous layer was 470 μm. When the obtained polishing pad was used, it was excellent not only in polishing rate and scratch scratches, but also in swell and disorder in the shape of the end.

[Example 5]
A porous sheet was obtained in the same manner as in Example 1 except that the 100% modulus of the polyurethane used for coating the porous layer in Example 1 was changed from 7 MPa to 23 MPa. When measured by sampling, the film thickness of the adhesive layer was 23 μm, and the film thickness of the porous layer was 650 μm.
A double-sided tape was affixed to the surface of the porous sheet-like product on which the porous layer of the polyester film or the like was not coated, to obtain an adsorption pad for fixing the object to be polished during polishing. When the obtained suction pad was used, the surface smoothness was superior to that of Example 1 and was at the same level as in Example 3. However, the suction force and processing spots were slightly unsatisfactory.

[Example 6]
A porous sheet was obtained in the same manner as in Example 1 except that the 100% modulus of the polyurethane used for coating the porous layer in Example 2 was changed from 7 MPa to 23 MPa.
Further, the surface of the obtained porous sheet was buffed with # 150 sandpaper to form a polishing pad with openings distributed in the range of 30 to 70 μm in pore diameter excluding micropores on the surface; did. When measured by sampling, the film thickness of the adhesive layer was 23 μm, and the film thickness of the porous layer was 550 μm. When the obtained polishing pad was used, although the irregular shape of the end portion was superior to that of Example 4 in which the press work was performed, the polishing rate, scratches and waviness were slightly unsatisfactory.

[Comparative Example 1]
A porous sheet-like material was obtained in the same manner as in Example 1 except that the isocyanate as a crosslinking agent was not used from the adhesion treatment liquid of Example 1. However, the porous layer is peeled off from the film in some places and cannot be used as a suction pad or a polishing pad.

  The present invention is a method for producing a porous sheet material suitable for smoothing. In particular, it improves the flatness of the surface to be polished of the substrate, lens, liquid crystal glass, etc. used in precision equipment in a smooth manner, and consists of a support layer and a polymer elastic polymer during processing. This is a method for producing a porous sheet-like material that realizes performance that does not peel off between layers and enables long-term use with less trouble during processing.

Claims (7)

  On the film, an adhesion treatment liquid containing a crosslinking agent and a polymer elastic body (A) is applied, dried to form an adhesive layer, and a solution composed of the polymer elastic body (B) and an organic solvent is applied to the surface. A method for producing a porous sheet material, comprising forming a porous layer by wet coagulation of a polymer elastic body (B) in a coagulation bath containing water as a main component.   The method for producing a porous sheet-like product according to claim 1, wherein the crosslinking agent is an isocyanate-based crosslinking agent.   The method for producing a porous sheet-like material according to claim 1 or 2, wherein the elastic glass body (A) constituting the adhesive layer has a glass transition temperature Tg of 40 ° C or higher.   The method for producing a porous sheet-like material according to any one of claims 1 to 3, wherein the drying temperature of the adhesion treatment liquid is 100 ° C or lower.   The drying temperature after wet coagulation is 90 to 120 ° C. The method for producing a porous sheet-like material according to any one of claims 1 to 4.   The method for producing a porous sheet-like material according to any one of claims 1 to 5, wherein the outermost surface is polished.   The method for producing a porous sheet-like material according to any one of claims 1 to 6, wherein the surface is subjected to a heat press treatment.