JP5810802B2 - Polishing cloth - Google Patents

Description

  The present invention relates to a polishing cloth, and particularly to a polishing cloth that is suitably used for polishing and / or cleaning an aluminum alloy substrate or glass substrate used for a magnetic recording disk with an ultra-high precision finish.

  Magnetic recording disks are required to be smooth to the limit of the disk surface with the recent increase in recording density for rapidly increasing recording capacity. In recent years, a perpendicular recording medium in which an easy axis of magnetization in a magnetic film is oriented in a perpendicular direction has become mainstream. For this reason, if there are irregularities or scratches on the substrate before the magnetic layer is formed, there is a risk that the easy axis of magnetization will become an abnormally tilted part after the magnetic film is formed, and the low flying height of the magnetic head may not be satisfied. In response to such problems, a substrate called a scratch defect is achieved by performing a polishing process using a polishing cloth to achieve a substrate surface roughness of 0.1 nm or less and performing a cleaning process using a wiping tape. There is a demand for minimizing scratches on the surface and for removing foreign matters such as residuals and dirt on the substrate surface, and a polishing cloth that can meet such demands is desired.

  In order to reduce the surface roughness of the substrate, it has been proposed to impregnate the nonwoven fabric with a polymer elastic body so as to have cushioning properties in order to minimize the fibers constituting the polishing cloth and to minimize scratches on the substrate surface. ing. As such a fiber structure, for example, a non-woven fabric composed of ultrafine fibers having a single fiber diameter of 0.05 to 2.0 μm, a polishing cloth containing a polymer elastic body mainly composed of polyurethane has been proposed. The surface roughness of the substrate was about 0.2 nm (see Patent Documents 1 and 2).

  Further, as a method for reducing the surface roughness of the substrate, it has been proposed to reduce the surface roughness of the abrasive material to make the surface uniform. For example, by using a film-made polishing tape having a surface roughness of 0.07-2.7 μm, the surface roughness of the substrate is improved as compared with a conventional film-made polishing tape. However, since the polishing tape has a polishing layer to which abrasive grains are fixed, the polishing rate is not sufficient as compared with a polishing cloth using loose abrasive grains, and the surface roughness of the substrate is 0.4 to 0. It was about 6 nm (see Patent Document 3).

  Further, in the conventional polishing process, a polishing cloth having a high friction coefficient capable of a high polishing rate for high efficiency has been proposed. As such a polishing cloth, for example, a polishing cloth having a friction coefficient in the direction of the minimum friction coefficient of the polishing cloth surface of 1.0 or more was capable of a high polishing rate, but a scratch defect is frequently generated on the substrate. This was the cause of the error (see Patent Document 4).

Japanese Patent Laid-Open No. 9-262775 JP-A-9-277175 JP 2006-142388 A JP 2001-1254 A

  Accordingly, the object of the present invention is to solve the above-described conventional problems, and is made of ultrafine fibers, which have not been able to be achieved by conventional polishing cloths in polishing and / or cleaning processes, and have high performance with low surface roughness and low dynamic friction coefficient. It is to provide an abrasive cloth.

The present invention is to solve the above problems, and the polishing cloth of the present invention is a fiber structure including ultrafine fibers having an average single fiber diameter of 0.05 to 5.0 μm and a polymer elastic body. The silicon structure has a silicon content of 100 to 1000 ppm in at least a part of the fiber structure, and has at least one surface of the fiber structure having napped fibers made of ultrafine fibers . A polishing cloth characterized in that the surface roughness (Ra) is 1 to 20 μm and the coefficient of dynamic friction when wet is 0.1 to 1.0.

  According to a preferred aspect of the polishing cloth of the present invention, the water droplet absorption time for the surface of at least one side of the fiber structure is 0.1 second to 60 minutes.

  According to a preferred aspect of the polishing cloth of the present invention, the fiber structure contains a silicon compound having a siloxane skeleton.

  According to the preferable aspect of the polishing cloth of the present invention, the surface roughness of the fiber structure is 3 to 15 μm.

  According to the preferable aspect of the polishing cloth of the present invention, the dynamic friction coefficient of the fiber structure is 0.3 to 0.8.

According to a preferred aspect of the polishing cloth of the present invention, a silicon compound having a silicon content of 300 to 800 ppm is present in at least a part of the fiber structure.

  According to a preferred aspect of the polishing cloth of the present invention, a silicon compound having a siloxane skeleton is imparted before napping of the fiber structure.

  According to the present invention, since the surface roughness of the polishing cloth is low and the coefficient of dynamic friction is small, the substrate can be processed uniformly after dispersing the abrasive on the polishing cloth as compared with the conventional polishing cloth. A polishing cloth that can reduce the surface roughness of the substrate, suppress scratch defects, and exhibit excellent polishing performance is obtained.

  The polishing cloth of the present invention is suitably used when an aluminum alloy substrate or a glass substrate used for a magnetic recording disk is subjected to polishing or cleaning with an ultra-high precision finish.

  The abrasive cloth of the present invention is a fiber structure containing ultrafine fibers. By including the ultrafine fibers, the surface roughness of the polishing cloth can be reduced, and the surface roughness of the object to be polished can be reduced during polishing.

  The polishing cloth of the present invention is a fiber structure containing ultrafine fibers having an average single fiber diameter of 0.05 to 5.0 μm, the surface roughness of the fiber structure is 1 to 20 μm, and the dynamic friction coefficient is 0.1. It is an abrasive cloth characterized by being 1 to 1.0.

  Examples of the polymer that forms the ultrafine fiber include polyester, polyamide, polyolefin, polyphenylene sulfide, and the like. Many polycondensation polymers represented by polyester and polyamide have a high melting point and are more preferably used because they are excellent in heat resistance against heat generated during polishing. Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, and potytrimethylene terephthalate. Specific examples of polyamide include nylon 6, nylon 66, nylon 12, and the like.

  In addition, the polymer constituting the ultrafine fiber may be copolymerized with other components, or may contain additives such as particles, flame retardant, and antistatic agent. Examples of other copolymer components include sodium 5-sulfoisophthalate, 3-hydroxybutanoic acid, nylon 6, nylon 66, nylon 12, and the like. Examples of the particles include titanium oxide, examples of the flame retardant include organic flame retardants and inorganic flame retardants, and examples of the antistatic agent include alcohol-based charging agents. An inhibitor may be mentioned.

  It is important that the average single fiber diameter of the ultrafine fibers used in the present invention is 0.05 to 5.0 μm from the viewpoint of the density of the polishing cloth surface fibers, the fiber strength, and the gripping ability of the abrasive grains. By setting the average single fiber diameter to 5.0 μm or less, the surface roughness of the polishing cloth can be reduced, and the surface roughness of the object to be polished can be reduced. On the other hand, since the fiber strength and rigidity can be maintained by setting the average single fiber diameter to 0.05 μm or more, polishing can be performed efficiently. From the above balance, the average single fiber diameter of the ultrafine fibers is preferably 0.3 to 3.0 μm, more preferably 0.5 to 1.5 μm.

  As for the average single fiber diameter of the ultrafine fibers, as will be described later in the measurement method of the example, when fibers having a single fiber diameter exceeding 10 μm are mixed, the average of the fibers does not correspond to the ultrafine fibers. It shall be excluded from the measurement target of single fiber diameter.

  As a form of the ultrafine fiber bundle, the ultrafine fibers may be slightly separated from each other, may be partially bonded, or may be aggregated.

  In the nonwoven fabric used for the polishing cloth of the present invention, fibers thicker than the ultrafine fibers defined above may be mixed. By doing so, the strength of the polishing pad can be reinforced and the cushioning property can be improved. As the polymer that forms fibers thicker than the ultrafine fibers, the same polymers as those constituting the ultrafine fibers described above can be employed. The mixing amount of the fibers thicker than the ultrafine fibers with respect to the nonwoven fabric is preferably 30% by mass or less, and more preferably 10% by mass or less, so that the smoothness of the polishing cloth surface can be suitably maintained.

  As a nonwoven fabric which is a fiber entangled body used in the polishing cloth of the present invention, a short fiber is obtained by forming a laminated fiber web using a card and a cross wrapper and then performing needle punching or water jet punching. Nonwoven fabrics, long fiber nonwoven fabrics obtained from the spunbond method, melt blow method, etc., and nonwoven fabrics obtained by the papermaking method can be appropriately employed. Among these, a short fiber nonwoven fabric and a spunbond nonwoven fabric are preferably used because an aspect of an ultrafine fiber bundle as described later can be obtained by a needle punching process.

Polishing cloth of the present invention, the nonwoven is a fiber-entangled body you containing elastic polymer. By including the polymer elastic body in the fiber entangled body, it is possible to prevent the ultrafine fibers from falling off from the polishing cloth due to the binder effect of the polymer elastic body, and it is possible to form uniform napping at the napping process. Further, by incorporating a polymer elastic body into a nonwoven fabric that is a fiber-entangled body, cushioning properties can be imparted to the polishing cloth, and scratch defects can be reduced.

  Examples of the polymer elastic body used in the present invention include polyurethane, polyurea, polyurethane-polyurea elastomer, polyacrylic acid, acrylonitrile-butadiene elastomer, and styrene-butadiene elastomer. Of these, polyurethane elastomers such as polyurethane and polyurethane / polyurea elastomer are preferably used.

  The weight average molecular weight of the polymer diol component of the polyurethane used as the main component of the polymer elastic body is preferably 500 to 5000, more preferably 1000 to 3000. By setting the weight average molecular weight to 500 or more, more preferably 1000 or more, it is possible to maintain the strength of the polishing cloth and to prevent the fine fibers from falling off. Moreover, by making a weight average molecular weight into 5000 or less, More preferably, 3000 or less, the increase in the viscosity of a polyurethane solution can be suppressed and it can make it easy to impregnate an ultrafine fiber layer.

  In addition, as the raw material diol component, polyether diol, polyester diol, polycarbonate diol, polylactone diol, or a copolymer thereof is preferably used.

  Moreover, aromatic diisocyanate, alicyclic isocyanate, aliphatic isocyanate, etc. can be used as a diisocyanate component. Among them, in order to enhance the cushioning property that contributes to the fit to the object to be polished and the suppression of scratches, the ratio of the polyether diol component in the polymer diol is preferably 60% by mass or more from the viewpoint of flexibility. It is a more preferable aspect that it is 70 mass% or more.

  The weight average molecular weight of the polyurethane used in the present invention is preferably 100,000 to 300,000, more preferably 150,000 to 250,000. By setting the weight average molecular weight to 100,000 or more, it is possible to maintain the strength of the resulting polishing cloth and to prevent the fine fibers on the napped surface from falling off. Moreover, by making a weight average molecular weight into 300,000 or less, the increase in the viscosity of a polyurethane solution can be suppressed and it can make it easy to impregnate a nonwoven fabric.

  In the present invention, polyurethane is preferably used as the main component as the polymer elastic body, and as a binder, polyesters, polyamides, polyolefins, etc., as long as the performance and the uniform dispersion state of the napped fibers are not impaired. Elastomer resins, acrylic resins, ethylene-vinyl acetate resins, and the like may be included. Further, the polymer elastic body includes various additives such as phosphorus, halogen and inorganic flame retardants, phenol, sulfur and phosphorus antioxidants, benzotriazole, benzophenone, salicylate. UV absorbers such as cyanoacrylates and oxalic acid anilides, light stabilizers such as hindered amines and benzoates, hydrolysis stabilizers such as polycarbodiimides, plasticizers, antistatic agents, surfactants, Further, it may contain a trace amount of a coagulation regulator and the like.

  Examples of the elastic polymer include polyurethane, polyurea, polyurethane / polyurea elastomer, polyacrylic acid, acrylonitrile / butadiene elastomer, and styrene / butadiene elastomer.

  Among these, polyurethane elastomers such as polyurethane and polyurethane / polyurea elastomer are preferable. As the polyol component of the polyurethane-based elastomer, polyester-based, polyether-based, polycarbonate-based diols, or copolymers thereof can be used. Moreover, as a diisocyanate component, aromatic diisocyanate, alicyclic isocyanate, aliphatic isocyanate, etc. can be used.

  The weight average molecular weight of the polyurethane elastomer is preferably 50,000 to 300,000. By setting the weight average molecular weight to 50,000 or more, more preferably 100,000 or more, and further preferably 150,000 or more, it is possible to maintain the strength of the polishing cloth and prevent the fine fibers from falling off. In addition, by setting the viscosity to 300,000 or less, more preferably 250,000 or less, it is possible to suppress the increase in the viscosity of the polyurethane solution and facilitate the impregnation of the ultrafine fiber layer.

  In addition, additives such as colorants, antioxidants, antistatic agents, dispersants, softeners, coagulation modifiers, flame retardants, antibacterial agents, and deodorants are blended in the elastic polymer as necessary. Also good.

  In this invention, it is preferable that the content rate of said elastic polymer is 5-200 mass% with respect to the nonwoven fabric formed by an ultrafine fiber bundle being entangled. The surface state, cushioning properties, hardness, strength, and the like of the polishing cloth can be adjusted by the content. When the content of the elastic polymer is preferably 5% by mass or more, more preferably 20% by mass or more, and still more preferably 30% by mass or more, fiber dropout can be reduced. On the other hand, when the content of the elastic polymer is preferably 200% by mass or less, more preferably 100% by mass or less, and further preferably 80% by mass or less, workability and productivity are improved, and on the surface. A state in which ultrafine fibers are uniformly dispersed can be obtained.

The basis weight of the portion of the polishing cloth of the present invention excluding the reinforcing layer described later is preferably 100 to 600 g / m ² . By making the above-mentioned basis weight preferably 100 g / m ² or more, more preferably 150 g / m ² or more, the shape stability and dimensional stability of the polishing cloth are excellent, and the processing unevenness due to the elongation of the polishing cloth during polishing processing. The occurrence of scratch defects can be suppressed. On the other hand, when the basis weight is preferably 600 g / m ² or less, more preferably 300 g / m ² or less, the handleability of the polishing cloth in the form of a tape becomes easy, and the cushioning property of the polishing cloth is also improved. The polishing pressure can be moderately suppressed, and the pressing pressure by the rubber roller from the non-polishing surface can be appropriately propagated to the polishing surface during polishing processing, so that efficient polishing processing can be performed.

  The thickness of the portion of the polishing cloth of the present invention excluding the reinforcing layer described later is preferably 0.1 to 10 mm. By making the above thickness preferably 0.1 mm or more, more preferably 0.3 mm or more, the polishing cloth is excellent in form stability and dimensional stability, and the polishing cloth stretches during polishing and cleaning. It is possible to suppress the occurrence of processing unevenness and scratch defects due to. On the other hand, when the thickness is preferably 10 mm or less, more preferably 5 mm or less, the pressing pressure during polishing can be sufficiently propagated.

  Moreover, the polishing cloth of the present invention may have a structure having a reinforcing layer on the other surface (the surface on the side subjected to polishing) having a cut end of the ultrafine fiber bundle described later. By doing so, it is excellent in the form stability and dimensional stability of the polishing cloth, and it is possible to suppress the occurrence of processing unevenness and scratch defects due to the elongation of the polishing cloth during polishing. As the reinforcing layer, a woven fabric, a knitted fabric, a nonwoven fabric (including paper), a film-like material (plastic film, metal thin film sheet, etc.) and the like can be employed.

  In the polishing cloth of the present invention, it is preferable that napping treatment is applied to the surface in contact with the substrate, that is, the surface on the side used for polishing. As a result, it is possible to finely disperse the free abrasive grains on the fibers on the surface of the polishing cloth and uniformly polish, and to efficiently remove residuals and dirt of organic and inorganic compounds such as polishing scraps and abrasives. . Further, since the raised hairs increase cushioning properties, scratch defects can be reduced.

The abrasive cloth of the present invention can be obtained by applying a polymer elastic body to an ultra-fine short fiber nonwoven fabric and washing and removing the water-soluble resin with water, followed by buffing treatment (napping treatment). The buffing treatment referred to here may be a suede finish in a state where at least one surface is a raised surface. The buffing treatment is generally performed using a needle cloth or sandpaper. In particular, after the polymer elastic body is applied, uniform and dense napping can be formed by napping the surface using sandpaper. Furthermore, in order to improve the uniformity and denseness of the surface fiber distribution on the surface of the polishing pad and extremely reduce the directionality of the napped fibers, it is preferable to reduce the grinding load. When the grinding load is small, there are few napped fibers that are curly, and the napped fibers are less likely to stick together in a bundle, so that a low surface roughness of the substrate can be achieved during substrate polishing, and scratch defects can be suppressed. preferable. In order to reduce the grinding load, it is preferable to appropriately adjust the number of buff stages, sandpaper count, grinding weight at each stage, sandpaper traveling speed, and sheet traveling speed. Among them, the number of buff stages is preferably multistage buffing with 3 or more stages, and the sandpaper used in each stage is preferably in the range of No. 150 to No. 600 defined by JIS. The grinding weight at each stage is preferably 50 g / m ² or less, more preferably 40 g / m ² or less, and even more preferably 30 g / m ² or less. Furthermore, it is preferable that the value obtained by dividing the sandpaper traveling speed in each stage by the sheet traveling speed is set in the range of 50 to 200. In the case of 50 or more, the density of surface fibers on the surface of the polishing cloth is not excessively lowered, and in the case of less than 200, good dispersibility of the surface fibers on the surface of the polishing cloth can be maintained. This is preferable because the directional disturbance is small and unevenness of the surface fibers is suppressed.

  Next, a method for producing the polishing cloth of the present invention will be described.

  As a means for obtaining a nonwoven fabric in which ultrafine fiber bundles are entangled, it is preferable to use ultrafine fiber generating fibers. Although it is difficult to produce a nonwoven fabric directly from ultrafine fibers, by producing a nonwoven fabric from ultrafine fiber-generating fibers and generating ultrafine fibers from sea-island composite fibers in this nonwoven fabric, the ultrafine fiber bundles are intertwined Can be obtained.

  As ultra-fine fiber-generating fibers, two-component thermoplastic resins with different solvent solubility are used as sea components and island components, and island components are made into ultra-fine fibers by dissolving and removing the sea components using a solvent. Alternatively, a two-component thermoplastic resin may be alternately disposed in a radial or multilayer manner on the fiber cross section, and a peelable composite fiber that is split into ultrafine fibers by separating and separating each component may be employed.

  Sea-island type fibers include sea-island type composite fibers that use a sea-island type composite base to spun two sea and island components together, and mixed spinning fibers that mix and spin the two sea and island components. However, sea-island type composite fibers are more preferably used because ultrafine fibers having a uniform fineness can be obtained, and because a sufficiently long ultrafine fiber is obtained and contributes to the strength of the sheet-like material.

  As the sea component of the sea-island fiber, polyethylene, polypropylene, polystyrene, copolymerized polyester obtained by copolymerizing sodium sulfoisophthalic acid, polyethylene glycol, or the like, polylactic acid, or the like can be used.

  The sea component may be dissolved and removed at any timing before the elastic polymer is applied, after the elastic polymer is applied, or after the napping treatment.

  As a method for obtaining a nonwoven fabric, as described above, a method of entanglement of a fiber web with a needle punch or a water jet punch, a spun bond method, a melt blow method, a paper making method, etc. can be adopted. In order to obtain a fiber bundle, it is preferable to use a needle punch or a water jet punch.

  In the needle punching process, the number of barbs is preferably 1-9. By making the number of barbs one or more, efficient fiber entanglement becomes possible. On the other hand, fiber damage can be suppressed by setting the number of barbs to preferably 9 or less.

  The total depth of the barb is preferably 0.05 to 0.09 mm. By making the total depth of the barb preferably 0.05 mm or more, a sufficient catch on the fiber bundle can be obtained, so that efficient fiber entanglement becomes possible. On the other hand, fiber damage can be suppressed by making the total depth of the barb preferably 0.09 mm or less.

The number of punching is preferably 4500 to 14000 / cm ² . By setting the number of punching to preferably 4500 / cm ² or more, denseness can be obtained and high-precision finishing can be obtained. On the other hand, when the number of punching is preferably 14000 pieces / cm ² or less, deterioration of workability, fiber damage, and strength reduction can be prevented.

  Moreover, when performing a water jet punch process, it is preferable to perform water in the state of a columnar flow. Specifically, it is preferable to eject water from a nozzle having a diameter of 0.05 to 1.0 mm at a pressure of 1 to 60 MPa.

The apparent density of the ultrafine fiber-generating fiber nonwoven fabric after needle punching or water jet punching is preferably 0.15 to 0.30 g / cm ³ . By making the above apparent density preferably 0.15 g / cm ³ or more, it is excellent in the form stability and dimensional stability of the polishing cloth, and processing unevenness and scratch defects due to the elongation of the polishing cloth during polishing processing are generated. Can be suppressed. On the other hand, when the apparent density is preferably 0.30 g / cm ³ or less, a sufficient space for applying the elastic polymer can be maintained.

  From the viewpoint of densification, it is preferable that the ultrafine fiber generating fiber nonwoven fabric thus obtained is contracted by dry heat or wet heat, or both, and further densified.

  As the solvent for dissolving the easily soluble polymer (sea component) from the ultrafine fiber generating fiber, if the sea component is polyolefin such as polyethylene or polystyrene, an organic solvent such as toluene or trichloroethylene can be used. If the component is polylactic acid or a copolyester, an alkaline aqueous solution such as sodium hydroxide can be used. Further, the ultrafine fiber generation processing (sea removal treatment) can be performed by immersing the ultrafine fiber generation type fiber (nonwoven fabric made of) in a solvent and squeezing it.

  In addition, for the ultrafine fiber generation processing, known apparatuses such as a continuous dyeing machine, a vibro-washer type sea removal machine, a liquid dyeing machine, a Wins dyeing machine, and a jigger dyeing machine can be used. The ultrafine fiber generation processing may be performed before the napping treatment or after the napping treatment.

  The elastic polymer may be applied before or after the ultrafine fiber generation processing.

  As the solvent used for imparting the elastic polymer, N, N′-dimethylformamide, dimethyl sulfoxide and the like can be preferably used. Further, an aqueous polyurethane in which polyurethane is dispersed in water as an emulsion may be used.

  The elastic polymer is applied to the non-woven fabric by immersing the non-woven fabric in an elastic polymer solution dissolved in a solvent, and then dried to substantially solidify and solidify the elastic polymer. In drying, you may heat at the temperature which does not impair the performance of a nonwoven fabric and an elastic polymer.

  As a method for laminating the reinforcing layer on the polishing cloth, a known method such as entanglement or adhesion may be used.

  As a method of laminating the reinforcing layers by entanglement, when manufacturing a nonwoven fabric made of the above-described ultrafine fiber-generating fiber, a needle punch, a water jet punch, or the like by overlapping a woven fabric, a knitted fabric, a nonwoven fabric (including paper), etc. The method of performing this process is mentioned.

  As a method of laminating the reinforcing layer by adhesion, a nonwoven fabric including a woven fabric, a knitted fabric, a nonwoven fabric (including paper), a film-like material (plastic film, metal thin film sheet, etc.), etc. containing a thermal bonding fiber or a resin And a method of adhering by a thermocompression bonding method or a frame lamination method, or a method of adhering by providing an adhesive layer between a reinforcing layer and a sheet layer made of a nonwoven fabric. Any adhesive layer can be used as long as it has rubber elasticity such as polyurethane, SBR, NBR, polyamino acid, and acrylic adhesive, but in view of cost and practicality, an adhesive such as NBR or SBR is preferable. . As a method for applying the adhesive, it is preferable to apply the adhesive to the sheet layer in the form of emulsion or latex.

  The polishing cloth of the present invention has a surface roughness of 1 to 20 μm. By setting the surface roughness to 1 μm or more, it is possible to obtain an excellent aspect from the viewpoints of retention and dispersibility of abrasive grains during polishing and wiping properties during cleaning. Further, when the surface roughness is less than 20 μm, it is difficult to give a scratch defect to the object to be polished when used for polishing, and the surface roughness of the object to be polished can be reduced. The surface roughness is more preferably 3 to 15 μm, still more preferably 5 to 10 μm. The surface roughness in this invention was calculated | required by the method as described in the Example mentioned later.

  When the surface roughness is not uniform in each manufacturing process of a polishing cloth made of a fiber structure containing ultrafine fibers, the surface roughness becomes high, and therefore the napped treatment process is important.

  The abrasive cloth of the present invention has a surface dynamic friction coefficient of 0.1 to 1.0. If the dynamic friction coefficient is 0.1 or more, good polishing performance and cleaning performance are exhibited when pressed against the substrate in the polishing and cleaning processes. Further, if the dynamic friction coefficient is 1.0 or less, the frictional resistance is not too high, and there is a low risk of causing scratches on the substrate. The dynamic friction coefficient is preferably 0.2 to 0.9, more preferably 0.3 to 0.8. The dynamic friction coefficient in this invention was calculated | required by the method as described in the Example mentioned later.

  The dynamic friction coefficient can be achieved by performing each manufacturing process of the polishing cloth composed of the fiber structure including the ultrafine fibers described above. In addition, since the dynamic friction coefficient varies depending on the application of the processing chemical, which will be described later, when the processing chemical is applied, it is necessary to adjust the chemical type and application conditions so that the above-mentioned dynamic friction coefficient is within the range.

  The polishing cloth of the present invention preferably has a water droplet absorption time on the surface of 0.1 second to 60 minutes. If the water droplet absorption time is 0.1 seconds or more, the abrasive does not pass too much into the inner layer of the polishing pad, the abrasive grains can be held on the fibers on the surface of the polishing pad, and the amount of grinding does not become insufficient. Moreover, if the water droplet absorption time is within 60 minutes, the abrasive grains are dispersed and gripped on the fibers without being overly repelled on the fibers on the surface of the polishing cloth and can be polished uniformly. When abrasive grains are continuously supplied onto the polishing surface, the polishing surface is slow to be wet, the abrasive grains cannot be sufficiently dispersed, and scratches are likely to increase, resulting in a decrease in polishing accuracy. The time is more preferably 0.1 second to 10 minutes, and still more preferably 0.1 second to 1 minute. The water droplet absorption time in the present invention was determined by the method described in the examples described later.

  Water droplet absorption time can be achieved by performing each manufacturing process of the polishing cloth which consists of the fiber structure containing an ultrafine fiber mentioned above. In addition, since it varies depending on the application of the processing drug described later, when applying the processing drug, it is necessary to adjust the drug type and the application conditions so that the water droplet absorption time is within the range.

  The napped length of the polishing cloth of the present invention is preferably 2 mm or less. The napped length is more preferably in the range of 0.1 to 2 mm. When the napped length exceeds 2 mm, the degree of freedom of the napped fibers becomes too large, and the direction of the napped fibers in the napped surface is greatly disturbed. The abrasive grain distribution may be uneven and scratch defects may not be suppressed. The napped length is an average value of the fiber length exposed on the outermost layer of any 50 napped fibers in a surface electron micrograph taken with the surface direction of the polishing cloth facing downward. It points to. In order to control the napped length to 2 mm or less, it can be achieved by combining the above-described method for producing a sheet composed of the entangled nonwoven fabric and the polymer elastic body and the buffing method.

The apparent density of the polishing cloth of the present invention is in the range of 0.2 to 0.5 g / cm ^{3 in} consideration of the high density and uniformity of the surface fibers and the retention and pressing force of the abrasive grains. It is preferable.

  It is preferable that the surface of the polishing cloth of the present invention has a hardness of 20 to 60 as measured according to JISK-6253A. When the hardness is less than 20, the pressing force of the abrasive grains is insufficient, the grinding becomes insufficient, and an unpolished portion is generated. On the other hand, when the hardness exceeds 60, the pressing of the abrasive grains becomes too strong, so that a scratch defect occurs and a desired surface roughness cannot be achieved. The above-mentioned hardness can be obtained by adopting the configuration of the ultrafine short fiber nonwoven fabric and the polymer elastic body described above.

  The polishing cloth of the present invention may be provided with a processing agent for the purpose of improving the polishing performance. Examples of such processing agents include silicon-based agents and WAX-based agents that can improve smoothness (for example, Neoseed NR-90 manufactured by Nikka Chemical Co., Ltd.), fluorine-based agents that can improve water and oil repellency and slidability. In addition to drugs (for example, NK Guard S-02 manufactured by Nikka Chemical Co., Ltd.), auxiliary agents such as dispersants, softeners and surfactants can be mentioned. After such a processing chemical has been applied, depending on the type of the drug, there may be a case where a heat treatment called a curing process is performed after drying to develop the effect of the chemical.

  The use of non-woven fabrics as abrasive cloths and wiping tapes also has interactions with abrasives during the polishing process and cleaning agents during the cleaning process, so there are a wide variety of combinations of processing agents. In particular, as will be described later, it is preferable to contain a certain amount of silicon compound in order to improve fiber dispersibility and improve the smoothness and the number of scratches in substrate evaluation after the polishing step.

  The polishing cloth of the present invention may be provided with the above-described processing chemical before or after any process or during the process. From the viewpoint of process passability, it is preferably applied during or after sea removal. Moreover, when applying after a napping process, since a nap | float aggregates after drying and the fiber uniformity of a surface falls and surface roughness deteriorates, it is preferable to provide a processing chemical | medical agent before a napping process.

  In this case, the fiber opening property is improved during napping treatment, and the fibers on the surface of the polishing cloth are densely and uniformly arranged, so that the surface roughness is excellent. In general, it is known that the friction coefficient tends to be small when the silicone agent is applied by post-processing, but in the application of the processing agent before napping treatment, which is exemplified as a preferable processing method example of the polishing cloth of the present invention, For example, in the case of a silicone agent, since the surface fibers after the napping treatment are densely and uniformly arranged as described above, the contact area of the fibers is increased, so that the friction coefficient is increased. Thus, the contact area of the fibers increases and the uniformity is high, so that the substrate can be uniformly processed in the polishing process and the cleaning process, and as a result, the surface roughness of the substrate and the number of scratches can be suppressed.

In the polishing cloth of the present invention, it may be contained at least in part on the silicofluoride-containing compounds of the fiber structure, in which case, the silicon content of the fiber structure is preferably 100 to 1000 ppm. If the silicon content is 100 ppm or more, the fiber dispersibility is improved. Further, if the silicon content is 1000 ppm or less, in napping treatment, the paper cannot slide normally on the polishing cloth treated surface when it is processed with sandpaper as an example of a preferred processing method of the polishing cloth of the present invention. Is less frequent, the fibers on the surface of the polishing cloth can be arranged densely and uniformly, the surface roughness can be improved, and the water repellency of the polishing cloth does not become too strong. Dispersibility of the used abrasive and cleaning agent on the polishing cloth is good and can be processed uniformly.

As described above, it is preferable that the silicon content is capable of normal napping treatment and increase the fiber contact area. From the viewpoint of the smoothness and the number of scratches in the substrate evaluation after the polishing and cleaning steps, the silicon content it is good preferable embodiment the amount is 3 00~800ppm.

  In the polishing cloth of the present invention, the above range for the silicon compound is given as a preferable content. However, it is important to set the optimum silicon content or processing chemical application amount according to the characteristics of the fiber structure used for the polishing cloth. is there.

  The silicon compound used for the polishing cloth of the present invention preferably has a siloxane skeleton. When there is a substituent, the silicon compound having a siloxane skeleton may have, for example, a polyether, an epoxy group, an amine, an alkyl group such as a carboxyl group, a methyl group, and a phenyl group as a substituent.

  When the treatment is performed at a high temperature of 150 ° C. or higher, polymethylphenylsiloxane having high heat resistance is preferably used. Examples of the heat-resistant silicone oil include heat-resistant methylphenyl silicone oil (KF-54 manufactured by Shin-Etsu Chemical Co., Ltd.), heat-resistant dimethyl silicone oil (SH510 manufactured by Toray Dow Corning Co., Ltd., manufactured by Shin-Etsu Chemical Co., Ltd.). KF-965, KF-968) can be used.

  Moreover, when importance is attached to the compatibility with polyester, for example, alkyl-modified silicone oil (SF8416, BY16-846, SH203, SH230 manufactured by Toray Dow Corning Co., Ltd.) can be used.

  Moreover, when importance is attached to flexibility, for example, amino-modified silicone (Bebner HCA manufactured by Maruhishi Oil Chemical Co., Ltd.) can be used. Of these, polyalkylsiloxane is preferably used because of its high versatility. For example, polydimethylsiloxane (SM7060EX, SH200 manufactured by Toray Dow Corning Co., Ltd., POLON-MWS manufactured by Shin-Etsu Chemical Co., Ltd.) is preferably used.

  The polishing cloth of the present invention may be subjected to a treatment such as pressing. The press treatment may be performed between any steps as long as it is between the step of obtaining the nonwoven fabric and the step of cutting the polishing cloth into a tape shape. Among these, it is preferable to perform the press before the napping treatment in terms of preventing the fiber from being disturbed after densifying the polishing cloth surface. In order to enhance the setability during pressing, it is preferable to perform hot pressing. Even when the silicon compound is applied, the press may be processed between any steps. However, the application of the silicon compound in the step before the press treatment may cause the chemical compound of the silicon compound to penetrate with the polishing cloth. it can.

  For example, the polishing cloth of the present invention can be cut into a tape shape having a width of 20 to 50 mm from the viewpoint of processing efficiency and stability and used as a polishing tape.

  The polishing cloth of the present invention preferably uses a generally known tape polishing process. For example, by continuously rotating a magnetic recording disk substrate made of glass or aluminum alloy and supplying an abrasive containing free abrasive grains between the polishing tape and the substrate, the surface fiber of the polishing tape In the state in which loose abrasive grains are finely dispersed in the substrate, polishing is performed by continuously running the polishing tape against the substrate with a rubber roller. As the abrasive, those obtained by dispersing high-hardness abrasive grains such as diamond fine particles in an aqueous dispersion medium are preferably used. An abrasive grain size of 0.2 μm or less is preferably used from the viewpoint of retention and dispersibility of abrasive grains suitable for the ultrafine fibers constituting the polishing cloth of the present invention.

  The polishing cloth of the present invention can also be suitably used as a cleaning tape. As a cleaning method, a polishing tape is used as the cleaning tape, and is performed in substantially the same manner as the above-described polishing process except that water or a cleaning agent is used in place of the polishing agent. A method for removing residuals and dirt of organic and inorganic compounds such as abrasives can be mentioned. At this time, the same tape as at the time of polishing may be used, or a different tape may be used. In addition, the cleaning process may be performed on the substrate after tape polishing or the substrate after pad polishing, or when the surface roughness is suppressed after forming the substrate, on the substrate that has not been polished. You can go.

  The polishing cloth of the present invention is made of ultrafine fibers, and has a low surface roughness and a small dynamic friction coefficient, so that the substrate is uniformly processed after the abrasive is uniformly dispersed on the polishing cloth as compared with the conventional polishing cloth. Therefore, the surface roughness of the substrate can be reduced, scratch defects can be suppressed, and excellent polishing performance can be exhibited. Due to these effects, the aluminum alloy substrate and the glass substrate used for the magnetic recording disk are suitably used when polishing or cleaning is performed with an extremely high precision finish.

  Next, the polishing cloth of the present invention and the method for producing the same will be described more specifically with reference to examples, but the present invention is not limited thereto. Moreover, the evaluation method used in the Example and the processing method for the evaluation are as follows.

[Evaluation method and processing method for evaluation]
(1) Melting point of polymer Using DSC-7 manufactured by Perkin Elmaer, the peak top temperature showing melting of the polymer at 2ndrun was defined as the melting point of the polymer. At this time, the rate of temperature increase was 16 ° C./min, and the sample amount was 10 mg.

(2) Polymer melt flow rate (MFR)
5 g of sample pellets are put in a cylinder of an MFR meter electric furnace, and the amount (g) of resin extruded in 10 minutes is measured using a Toyo Seiki melt indexer (S101) under a load of 2160 gf and a temperature of 285 ° C. did. The same measurement was repeated 3 times, and the average value was defined as MFR.

(3) Average single fiber diameter of the ultrafine fibers A cross section perpendicular to the thickness direction including the ultrafine fibers of the polishing cloth was observed with a scanning electron microscope (VE-7800, manufactured by SEM KEYENCE) at a magnification of 3000, and was 30 μm × 30 μm. The diameters of 50 single fibers extracted at random within the field of view were measured. However, this was performed at three locations, the diameters of a total of 150 single fibers were measured, and the average value was calculated by rounding off the numbers after the decimal point. When fibers having a single fiber diameter exceeding 10 μm are mixed, the fiber is excluded from the measurement target of the average single fiber diameter as not corresponding to the ultrafine fiber. When the ultrafine fiber has an irregular cross section, first, the cross-sectional area of the single fiber is measured, and the average diameter of the single fiber is obtained by calculating the diameter when the cross section is regarded as a circle.

(4) Surface roughness (Ra) of polishing cloth
The surface roughness of the polishing cloth of the present invention is measured using a surf coder SE-40C (Kosaka-Laboratory Ltd). The polishing cloth is fixed on a flat table so that the normal direction of the napping (the direction in which napping lies) and the moving direction of the stylus of the apparatus are the same direction, and a stylus with a tip radius of 5 μm and a tip area of 79 μm ² Was measured at a feed rate of 0.5 m / min, an evaluation length of 12.5 cm, a cutoff of 2.5 cm, a vertical magnification of 500 times, and a horizontal magnification of 2 times. The measurement was performed 5 times, and the average value was adopted as the numerical value of the surface roughness.

(5) Dynamic friction coefficient of the surface of the polishing cloth The dynamic friction coefficient of the surface of the polishing cloth of the present invention was obtained by attaching a sample cut into a 1 cm square to a flat indenter using double-sided tape and soaking sufficient water. When this is placed on a glass plate attached to a moving table of a surface property measuring instrument (HEIDON-14D manufactured by Shinto Kagaku Co., Ltd.), and the moving table is moved horizontally in the normal direction of napping (the direction in which napping lies) The frictional resistance was measured to determine the dynamic friction coefficient. The test speed was 500 mm / min, and the load condition was 600 g / cm ² . The measurement was performed three times, and the average value was adopted as the numerical value of the dynamic friction coefficient.

(6) Measurement of water absorption on the surface of the polishing cloth Using a FACE / CA-A type contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd.), distilled water was put into a syringe and an injection needle (outer diameter 0.60 mm, One drop of water from an inner diameter of 0.45 mm was dropped on the polishing cloth, the water drop was observed from the eyepiece of the device, and the absorption time (tq) was determined by the following equation.
tq = t2-t1 (seconds)
t1: Time when water drops fell on the polishing cloth t2: Time when water drops are sucked into the polishing cloth and no water drops remain on the surface The condition of t1 and t2 is visually observed in a normal case (approximately tq is 10 seconds or more). If it is very fast or difficult to observe, the state from when the water droplet begins to drip from the injection needle to the time when the water droplet is sufficiently absorbed into the polishing cloth by the above-mentioned device is measured. It can be measured after taking a full image of the water droplets through the eyepiece.

  In this way, 20 samples are measured with a sample arbitrarily taken from the product, and the average value of the five largest data among the 20 measured values (tq) is taken. Was the water absorption time value.

(7) Silicon content of polishing cloth Sulfuric acid was added to 5 g of a polishing cloth sample, left to stand overnight for carbonization, and then the sulfuric acid was evaporated on a hot plate. The obtained carbide was heated at a temperature of 550 ° C. for 2 hours using an electric furnace to perform an ashing treatment. The obtained ashed product was melted with sodium carbonate and dissolved in dilute hydrochloric acid to obtain a sample solution. The sample solution was introduced into an ICP emission spectroscopic analyzer, and silicon was quantified.

(8) Polishing The polishing cloth was a 30 mm wide tape. As a polishing target, a substrate made of amorphous glass manufactured by KMG whose surface roughness was controlled to 0.3 nm or less was used. In order to polish both sides of the substrate at once, tapes were set on both sides of the substrate, and free abrasive grains in which single crystal diamond particles having a primary particle diameter of 1 to 10 nm were clustered to an average diameter of 50 nm on the polishing cloth surface were 0 A 0.1% abrasive is dripped onto both sides at 15 ml / min, the pressure of the tape to the substrate is 1500g, the substrate rotation speed is 400rpm, the substrate swinging frequency is 5Hz, and the tape running speed is 2.5cm / min. And polished for 10 seconds.

(9) Cleaning process The substrate immediately after polishing is cleaned under the same conditions as the polishing process except that the polishing agent is changed to a cleaning agent (Chemclean PR-122 manufactured by Sanyo Chemical Co., Ltd.) and the processing time is 30 seconds. And washed with running water.

(10) Surface roughness of substrate Measured based on JIS B 0601: 2001. Using a surface roughness measuring machine (TMS-2000 manufactured by Schmidt Measurement System Co., Ltd.), the surface roughness is measured at 10 locations on the disk substrate sample surface after polishing and cleaning, and the measured values at 10 locations are averaged. Thus, the substrate surface roughness was calculated. The lower the value, the higher the performance.

  Using an atomic force microscope AFM (NanoScope II Ia AFM Dimension 3000 stage system manufactured by Digital Instruments), an arbitrary 10 locations (per 1 location) on each of both surfaces of 5 disk substrate samples after polishing, that is, a total of 10 surfaces Is an area of 5 μm in the radial direction on the disk surface × 5 μm in the circumferential direction). Next, a cross-sectional profile with one point at each of the 10 locations and a radial direction along the horizontal axis in the thickness direction of the disk is arbitrarily extracted. Each cross-sectional profile obtained is in accordance with JIS B 0601 (2001 edition). The arithmetic average roughness Ra is calculated. The substrate surface roughness was calculated by averaging the measured values of the obtained 10 surfaces × 10 points = total 100 points. The lower the value, the higher the performance. A substrate surface roughness of 1.5 mm or less was regarded as good polishing performance.

(11) The number of scratches on the substrate Using the optical surface analyzer (Candela 6100) as a measurement target on both surfaces of the five substrates after polishing and cleaning, that is, the total area of the surface of 10 substrates, a groove having a depth of 1 nm or more is formed. The number of scratches was measured as a scratch, and the average value of 10 measured values was evaluated. The lower the value, the higher the performance. When the number of scratches was 20 or less, the polishing performance was good.

(12) Comprehensive Evaluation of Substrate As for the surface roughness and scratch score of the substrate after polishing and cleaning processing, “○” indicates that the surface roughness is 1.0 mm or less and the scratch score is 10 or less, and the surface roughness is 1 Evaluation was made as “Δ” for those having a .0 to 1.5 mm or scratch score of 10 to 20, and “X” for those having a surface roughness of 1.5 mm or more or a scratch score of 20 or more. Was accepted.

[Example 1]
(raw cotton)
(Sea component / island component)
Nylon 6 having a melting point of 220 ° C. and MFR 10.5 was used as an island component, and copolymerized polystyrene (co-PSt) obtained by copolymerizing 22 mol% of 2-ethylhexyl acrylate having a melting point of 53 ° C. and MFR 12 was used as a sea component.

(Spinning / drawing)
Using the sea and island components described above, using a 376 island / hole sea-island composite die, spinning temperature of 285 ° C., island / sea mass ratio of 40/60, discharge rate of 1.7 g / min / hole, spinning speed of 1200 m Umijima fiber was melt spun at / min. Next, it is stretched 3.0 times in an oil solution bath for spinning at a temperature of 85 ° C., crimped using an indentation type crimping machine, cut, single fiber fineness 6.5 dtex, fiber length A 51 mm sea-island composite fiber raw cotton was produced.

(Extra-fine fiber generation type nonwoven fabric)
A laminated fiber web was formed through the card and cross wrapping process using the raw cotton of the above-mentioned sea-island type composite fibers. Subsequently, the obtained laminated fiber web was subjected to a needle depth of 8 mm and 3200 punches using a needle punch machine in which needles having a throat depth of 60 μm, a kick-up of 0 μm, an undercut angle of 4 °, and a throat length of 0.9 mm were implanted. Needle-punched at / cm ² to produce an ultrafine fiber-generating fiber nonwoven fabric having a basis weight of 800 g / m ² and an apparent density of 0.190 g / cm ³ .

(Polishing cloth)
The ultrafine fiber generating fiber nonwoven fabric was subjected to hot water shrinkage treatment with hot water at a temperature of about 95 ° C., then impregnated with a 12% aqueous solution of polyvinyl alcohol and dried. Thereafter, the sea component co-PST was dissolved and removed in trichlorethylene and dried to produce an ultrafine fiber nonwoven fabric in which ultrafine fiber bundles were entangled.

Polyurethane (gel point 4.2 ml) in which the polymer diol is composed of 75% by mass of a polyether and 25% by mass of a polyester is added to the ultrafine fiber nonwoven fabric thus obtained in a solid content of 20% by mass. After the polyurethane was solidified with a 30% DMF aqueous solution with a liquid temperature of 35 ° C. and the DMF and polyvinyl alcohol were removed with hot water at a temperature of about 85 ° C. , the silicon content was 500 ppm in terms of the mass of the ultrafine fiber nonwoven fabric. The chemical concentration and wet pick-up rate of a silicon-based chemical (SM7060EX manufactured by Toray Dow Corning Co., Ltd.) were adjusted so as to give impregnation . Thereafter, the paper was cut in the thickness direction by a half-cutting machine having an endless band knife, and the non-half-cut surface was ground in three stages using a JIS # 240 sandpaper to form napped hairs to produce a polishing cloth.

The obtained polishing cloth had an average single fiber diameter of ultrafine fibers of 0.72 μm, a thickness of 0.50 mm, a basis weight of 180 g / m ² , and an apparent density of 0.360 g / cm ^3. It was. Also, the chemicals applied to the obtained polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. The results are shown in Table 1.

[Example 2 ]
(Polishing cloth)
A polishing cloth was produced in the same manner as in Example 1 except that the chemical concentration of the silicon-based chemical and the wet pickup rate were adjusted so that the silicon content was 150 ppm (Example 2) . The results of summarizing the chemicals applied to the resulting polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. Table 1 shows.

[Example 3]
(raw cotton)
(Spinning / drawing)
A single fiber fineness of 2.2 dtex and a fiber length of 51 mm were obtained in the same manner as in Example 1 except that a sea-island type composite base having 600 islands / hole was used and the discharge rate was 1.0 g / min / hole. A raw cotton of sea-island type composite fiber was prepared.

(Polishing cloth)
An ultrafine fiber-generating fiber nonwoven fabric was produced in the same manner as in Example 1 except that the raw cotton was used, and then an abrasive cloth was produced. The obtained polishing cloth had an average single fiber diameter of ultrafine fibers of 0.35 μm, a thickness of 0.5 mm, a basis weight of 177 g / m ² , and an apparent density of 0.354 g / cm ³ . . Also, the chemicals applied to the obtained polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. The results are shown in Table 1.

[Example 4 ]
(raw cotton)
(Spinning / drawing)
A single fiber fineness of 4.0 dtex and a fiber length of 51 mm were obtained in the same manner as in Example 1 except that a sea-island type compound base having 376 islands / hole was used and the discharge rate was 1.9 g / min / hole. A raw cotton of sea-island type composite fiber was prepared.

(Polishing cloth)
An ultrafine fiber-generating fiber nonwoven fabric was produced in the same manner as in Example 1 except that the raw cotton was used, and then an abrasive cloth was produced. The obtained polishing cloth had an average single fiber diameter of ultrafine fibers of 0.58 μm, a thickness of 0.52 mm, a basis weight of 178 g / m ² , and an apparent density of 0.342 g / cm ³ . . The results of summarizing the chemicals applied to the resulting polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. Table 1 shows.

[Example 5 ]
(raw cotton)
(Sea component and island component)
The sea component and the island component were the same as in Example 1.

(Spinning / drawing)
Using the sea and island components described above, using a 200 island / hole sea-island composite die, spinning temperature of 285 ° C., island / sea mass ratio of 40/60, discharge rate of 0.9 g / min / hole, spinning speed of 1200 m The sea-island type composite fiber was melt-spun under the conditions of / min. Next, it is stretched 3.0 times in an oil solution bath for spinning at a temperature of 85 ° C., crimped using an indentation type crimping machine, cut, single fiber fineness 5.2 dtex, fiber length A 51 mm sea-island composite fiber raw cotton was produced.

(Extra-fine fiber generation type nonwoven fabric)
An ultrafine fiber-generating fiber nonwoven fabric was produced in the same manner as in Example 1 except that the raw cotton was used.

(Polishing cloth)
An abrasive cloth was produced in the same manner as in Example 1 except that the above ultrafine fiber generating fiber nonwoven fabric was used. The obtained polishing cloth had an average single fiber diameter of ultrafine fibers of 1.53 μm, a thickness of 0.51 mm, a basis weight of 186 g / m ² , and an apparent density of 0.365 g / cm ^3. It was. Also, the chemicals applied to the obtained polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. The results are shown in Table 1.

[Example 6 ]
(raw cotton)
A sea island having a single fiber fineness of 7.3 dtex and a fiber length of 51 mm, except that a discharge amount of 2.6 g / min / hole was used using a sea-island type composite base having 36 islands / hole. A raw cotton of type composite fiber was prepared.

(Extra-fine fiber generation type nonwoven fabric)
An ultrafine fiber-generating fiber nonwoven fabric was produced in the same manner as in Example 1 except that the raw cotton was used.

(Polishing cloth)
An abrasive cloth was produced in the same manner as in Example 1 except that the above-described ultrafine fiber-generating fiber nonwoven fabric was used. The obtained polishing cloth had an average single fiber diameter of ultrafine fibers of 2.99 μm, a thickness of 0.51 mm, a basis weight of 167 g / m ² , and an apparent density of 0.327 g / cm ³ . Also, the chemicals applied to the obtained polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. The results are shown in Table 1.

[Example 7 ]
(raw cotton)
A sea island having a single fiber fineness of 18.3 dtex and a fiber length of 51 mm, except that a discharge amount of 6.6 g / min / hole was obtained using a sea-island type composite base having 36 islands / hole. A raw cotton of type composite fiber was prepared.

(Extra-fine fiber generation type nonwoven fabric)
An ultrafine fiber-generating fiber nonwoven fabric was produced in the same manner as in Example 1 except that the raw cotton was used.

(Polishing cloth)
An abrasive cloth was produced in the same manner as in Example 1 except that the above-described ultrafine fiber-generating fiber nonwoven fabric was used. The obtained polishing cloth had an average single fiber diameter of ultrafine fibers of 4.73 μm, a thickness of 0.51 mm, a basis weight of 172 g / m ² , and an apparent density of 0.337 g / cm ³ . Also, the chemicals applied to the obtained polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. The results are shown in Table 1.

[Example 8 ]
(raw cotton)
(Sea component / island component)
Same as Example 1 except that PET having a melting point of 260 ° C. and MFR 46.5 was used as an island component, and a copolymer PET obtained by copolymerizing 8 mol% of 5-sodium isophthalic acid having a melting point of 230 ° C. and MFR 100 was used as a sea component. Thus, a raw cotton of sea-island type composite fiber having a single fiber fineness of 4.7 dtex and a fiber length of 51 mm was produced.

(Extra-fine fiber generation type nonwoven fabric)
An ultrafine fiber-generating fiber nonwoven fabric was produced in the same manner as in Example 1 except that the above raw cotton was used.

(Water-dispersed polyurethane liquid)
To a nonionic forced emulsification type polyurethane emulsion (polycarbonate type), sodium sulfate as a heat-sensitive gelling agent is added in an amount of 4% by mass relative to the polyurethane solid content, and the water-dispersed polyurethane liquid is added so that the polyurethane liquid concentration becomes 10% by mass. It was adjusted.

(Polishing cloth)
The above-mentioned water-dispersed polyurethane liquid is applied to the above-mentioned ultrafine fiber-generating fiber nonwoven fabric and dried with hot air at a drying temperature of 120 ° C. for 5 minutes, and the amount of polyurethane attached is 30% by mass with respect to the island component of the nonwoven fabric. A sheet with polyurethane was prepared. The sheet with polyurethane is immersed in a 20 g / L sodium hydroxide aqueous solution heated to a temperature of 90 ° C. using a liquid dyeing machine and treated for 30 minutes to dissolve and remove sea components from the sea-island composite fiber. An ultrafine fiber nonwoven fabric was produced. Next, the drug concentration and wet pick-up rate of the silicon-based drug (SM7060EX manufactured by Toray Dow Corning Co., Ltd.) were adjusted so that the silicon content was 500 ppm with respect to the mass of the ultrafine fiber nonwoven fabric. Impregnated. Thereafter, half-cutting and buffing were performed in the same manner as in Example 1 to prepare an abrasive cloth.

The obtained polishing cloth had an average single fiber diameter of ultrafine fibers of 0.74 μm, a thickness of 0.52 mm, a basis weight of 175 g / m ² , and an apparent density of 0.337 g / cm ³ . Also, the chemicals applied to the obtained polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. The results are shown in Table 1.

[Example 9 ]
(raw cotton)
(Sea component and island component)
The same sea component and island component as those used in Example 1 were used.

(Spinning / drawing)
The sea component and the island component are mixed by 50% by mass, and the sea-island fiber is melt-spun at a spinning temperature of 285 ° C., so that the ultrafine fiber in which about 1000 island components are arranged in the sea component by the so-called mixed spinning method. The generating fiber was melt-spun at a spinning speed of 1200 m / min. Next, it is stretched 3.0 times in an oil solution bath for spinning at a temperature of 85 ° C., crimped using an indentation type crimping machine, cut, and the single fiber fineness is 11.6 dtex, A raw cotton of sea-island type composite fiber having a fiber length of 51 mm was produced.

(Extra-fine fiber generation type nonwoven fabric)
An ultrafine fiber-generating nonwoven fabric was produced in the same manner as in Example 1 except that the above raw cotton was used.

(Polishing cloth)
The nonwoven fabric composed of the above-mentioned ultrafine fiber-generating fiber was subjected to hot water shrinkage, then impregnated with a 12% aqueous solution of polyvinyl alcohol and dried. To this non-woven fabric, 20% by mass of a solid content with respect to the mass of fiber is added to a polyurethane whose polymer diol is 75% by mass of polyether and 25% by mass of polyester. Was solidified and DMF was removed with hot water at a temperature of about 85 ° C. Thereafter, the sea component co-PST was dissolved and removed in trichlorethylene and dried to produce an ultrafine fiber nonwoven fabric composed of an ultrafine fiber bundle and polyurethane, and impregnated with a silicon-based agent in the same manner as in Example 2. Thereafter, an abrasive cloth was produced in the same manner as in Example 1 except that JIS # 320 sandpaper was used.

The obtained abrasive cloth had an average single fiber diameter of ultrafine fibers of 0.72 μm, a thickness of 0.55 mm, a basis weight of 180 g / m ² , and an apparent density of 0.327 g / cm ³ . Also, the chemicals applied to the obtained polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. The results are shown in Table 1.

[Example 10 ]
(Polishing cloth)
In the same manner as in Example 1, an ultrafine fiber nonwoven fabric formed by intertwining ultrafine fiber bundles was produced. Polyurethane (gel point 4.2 ml) in which the polymer diol is composed of 75% by mass of a polyether and 25% by mass of a polyester is added to the ultrafine fiber nonwoven fabric thus obtained in a solid content of 20% by mass. The polyurethane was coagulated with a 30% DMF aqueous solution having a liquid temperature of 35 ° C., and DMF and polyvinyl alcohol were removed with hot water at a temperature of about 85 ° C. Then, after half-cutting in the same manner as in Example 1, the chemical concentration and wet pickup rate of the silicon-based chemical (SM7060EX manufactured by Toray Dow Corning Co., Ltd.) were adjusted so that the silicon content was 500 ppm with respect to the mass of the ultrafine fiber nonwoven fabric. Adjusted and impregnated. Thereafter, buffing was performed to prepare an abrasive cloth.

  The results of summarizing the chemicals applied to the resulting polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. Table 1 shows.

[Example 11 ]
(Polishing cloth)
In the same manner as in Example 1, an ultrafine fiber nonwoven fabric formed by intertwining ultrafine fiber bundles was produced. Polyurethane (gel point 4.2 ml) in which the polymer diol is composed of 75% by mass of a polyether and 25% by mass of a polyester is added to the ultrafine fiber nonwoven fabric thus obtained in a solid content of 20% by mass. The polyurethane was coagulated with a 30% DMF aqueous solution having a liquid temperature of 35 ° C., and DMF and polyvinyl alcohol were removed with hot water at about 85 ° C. Thereafter, after half-buffing and buffing in the same manner as in Example 1, the concentration of the silicon-based drug (SM7060EX manufactured by Toray Dow Corning Co., Ltd.) was adjusted so that the silicon content was 500 ppm relative to the mass of the ultrafine fiber nonwoven fabric. The wet pick-up rate was adjusted, impregnation was applied, and an abrasive cloth was produced.

  The results of summarizing the chemicals applied to the resulting polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. Table 1 shows.

[Examples 12 to 13 ]
(Polishing cloth)
The treatment from the processing agent and the impregnation step was carried out as another polydimethylsiloxane agent (POLON-MWS, manufactured by Shin-Etsu Chemical Co., Ltd., Example 12 ) and heated at 120 ° C. for 3 minutes after impregnation and drying. A polishing cloth was produced in the same manner as in Example 1 except that it was impregnated and dried as Beviner HCA manufactured by Yuka Co., Ltd., Example 13 ). The results of summarizing the chemicals applied to the resulting polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. Table 1 shows.

[Comparative Example 1]
(raw cotton)
(Spinning / drawing)
A single fiber fineness of 0.09 dtex and a fiber length of 51 mm were obtained in the same manner as in Example 1 except that a sea-island type composite base having 1200 islands / hole was used and the discharge rate was 0.04 g / minute / hole. A raw cotton of sea-island type composite fiber was prepared.

(Polishing cloth)
An ultrafine fiber-generating fiber nonwoven fabric was produced in the same manner as in Example 1 except that the raw cotton was used, and then an abrasive cloth was produced. The obtained polishing cloth had an average single fiber diameter of ultrafine fibers of 0.03 μm, a thickness of 0.41 mm, a basis weight of 162 g / m ² , and an apparent density of 0.395 g / cm ³ . . Also, the chemicals applied to the obtained polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. The results are shown in Table 1.

[Comparative Example 2]
(raw cotton)
A sea island having a single fiber fineness of 26.7 dtex and a fiber length of 51 mm, except that a discharge amount of 9.6 g / minute / hole was made using a sea-island type composite base having 16 islands / hole. A raw cotton of type composite fiber was prepared.

(Extra-fine fiber generation type nonwoven fabric)
An ultrafine fiber-generating fiber nonwoven fabric was produced in the same manner as in Example 1 except that the above raw cotton was used.

(Polishing cloth)
An abrasive cloth was produced in the same manner as in Example 1 except that the above-described ultrafine fiber-generating fiber nonwoven fabric was used. The obtained polishing cloth had an average single fiber diameter of ultrafine fibers of 8.65 μm, a thickness of 0.52 mm, a basis weight of 162 g / m ² , and an apparent density of 0.312 g / cm ³ . Also, the chemicals applied to the obtained polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. The results are shown in Table 1.

[Comparative Example 3]
(Polishing cloth)
A polishing cloth was produced in the same manner as in Example 1 except that the chemical concentration of the silicon-based chemical and the wet pickup rate were adjusted so that the silicon content was 4000 ppm. Since the silicon content was large, the roll frequently slipped on the grinding symmetry surface during the buffing process, so that the buffing could not be performed uniformly. The results of summarizing the chemicals applied to the resulting polishing cloth, the silicon content of the polishing cloth, the average single fiber diameter, the surface roughness, the dynamic friction coefficient, the water absorption and the surface roughness of the substrate after the polishing process, and the number of scratches are summarized. Table 1 shows.

Claims (7)

A fiber structure including ultrafine fibers having an average single fiber diameter of 0.05 to 5.0 μm and a polymer elastic body , and a silicon compound having a silicon content of 100 to 1000 ppm is present in at least a part of the fiber structure The fiber structure has napped fibers on at least one surface, the surface roughness (Ra) of the fiber structure is 1 to 20 μm, and the coefficient of dynamic friction when wet is 0.1. A polishing cloth characterized by being 1 to 1.0. At least the water droplet absorption time relative to one side surface, the polishing pad of claim 1 Symbol mounting, characterized in that from 0.1 seconds to 60 minutes of the fiber structure. The polishing cloth according to claim 1 or 2 , wherein the fiber structure contains a silicon compound having a siloxane skeleton. The polishing cloth according to any one of claims 1 to 3 , wherein the fiber structure has a surface roughness (Ra) of 3 to 15 µm. The abrasive cloth according to any one of claims 1 to 4 , wherein the dynamic friction coefficient of the fiber structure is 0.3 to 0.8. The abrasive cloth according to any one of claims 1 to 5 , wherein a silicon compound having a silicon content of 300 to 800 ppm is present in at least a part of the fiber structure. The abrasive cloth according to any one of claims 1 to 6 , wherein a silicon compound having a siloxane skeleton is applied before the napping of the fiber structure.