JP2012214944A - Leather-like base material, artificial leather using the same and abrasive pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leather-like base material containing nonwoven cloth and a porous polymer elastomer, having flexible feeling and light weight, and being used for manufacturing artificial leather, an abrasive pad, and the like.SOLUTION: A leather-like base material comprises nonwoven cloth and a porous polymer elastomer impregnated into the nonwoven cloth. The nonwoven cloth is an entangled body of a porous hollow fiber having a plurality of holes each having an average diameter (A) of 1 to 10 μm in a cross section thereof. The porous polymer elastomer has holes each having an average diameter (B) of 1 to 10 μm. The average diameter (A)/the average diameter (B) is 0.5 to 2. A content rate of the porous polymer elastomer to a total amount of the nonwoven cloth and the porous polymer elastomer is 15 to 50%.

Description

  The present invention relates to a leather-like base material including a nonwoven fabric and a porous polymer elastic body, which is used for manufacturing artificial leather, polishing pads, and the like.

  Conventionally, a leather-like base material including a nonwoven fabric is known. Such leather-like base materials are widely used in the production of artificial leather that becomes a surface material for footwear, bags, clothing, furniture, and the like.

  Artificial leather is required to be lightweight in addition to mechanical properties and texture. As artificial leather with improved lightness, artificial leather including a fiber base material formed from ultrafine fibers is known. The fiber base material formed from the ultrafine fibers is formed, for example, by selectively dissolving and removing only the sea components from the fiber base material formed from the sea-island type composite fiber. According to such a method, it is possible to obtain a lightweight fiber substrate made of ultrafine fibers. However, the fiber base material obtained by such a method has a problem that the lightness cannot be sufficiently obtained because the gap between the fibers is greatly reduced by the press treatment for adjusting the thickness. In order to solve such a problem, a method of using a fiber base material formed from hollow fibers as artificial leather is known.

  For example, Patent Document 1 below discloses a fiber structure excellent in lightness including hollow fibers made of a thermoplastic polymer having an equilibrium moisture content of 2% or less. Moreover, for example, the following Patent Document 2 discloses an artificial leather containing polyester fibers having a hollow ratio of 40 to 85%. Further, for example, Patent Document 3 below discloses a nonwoven fabric made of hollow fibers, in which the hollow ratio of the hollow fibers has a gradient from one side to the other in the thickness direction. Further, for example, Patent Document 4 below has an ultrafine fiber (A) of 0.5 dtex or less and 5 to 50 dtex in a transverse section, and the total area ratio of the hollow portions is 25. The fiber (B) in which the area occupied by one hollow part is 5% or less is in the range of ~ 50%, and (A) / (B) is 20/80 to 80/20 by weight ratio and is three-dimensionally entangled An artificial leather base material comprising a nonwoven fabric and a polymer elastic body is disclosed.

  In addition, the leather-like base material including the nonwoven fabric and the porous polymer elastic body is pressed against the base material to be polished while dropping slurry of abrasive grains as disclosed in, for example, Patent Document 5 below. It is also used to manufacture polishing pads used for chemical mechanical polishing (CMP) for polishing.

  As a polishing pad used for CMP, a polishing pad mainly composed of a leather-like base material including a polishing pad made of a polyurethane molded body and a nonwoven fabric and a polymer elastic body is known. Among these, a polishing pad made of a polyurethane molded body has a problem that it has a high rigidity and therefore has a poor followability to the surface of the substrate to be polished, and it is easy to generate scratches due to the force applied to the aggregate of abrasive grains. there were. On the other hand, a polishing pad mainly composed of a leather-like base material including a nonwoven fabric and a polymer elastic body has low rigidity and is excellent in conformity to the shape of the surface of the base material to be polished. Since the flatness is excellent, there is an advantage that scratches are hardly generated.

Japanese Patent Laid-Open No. 2002-220741 Japanese Patent No. 3924360 Japanese Patent No. 3361967 Japanese Patent Laid-Open No. 2002-242077 International Publication 2010/0164486 Pamphlet

  Artificial leather is required to be both natural and soft as natural leather and lightweight. Also, polishing pads used in CMP are required to be flexible in order to obtain excellent followability with respect to the shape of the surface of the substrate to be polished.

  An object of the present invention is to provide a leather-like substrate comprising a nonwoven fabric and a porous polymer elastic body, which has a supple texture and is lightweight, and is used for the production of artificial leather and polishing pads. To do.

  One aspect of the present invention is a leather-like base material including a nonwoven fabric and a porous polymer elastic body impregnated in the nonwoven fabric, and the nonwoven fabric is an entangled body of porous hollow fibers having a plurality of holes in the cross section. The average pore diameter (A) of the plurality of holes in the cross section is 1 to 10 μm, the average pore diameter (B) of the porous polymer elastic body is 1 to 10 μm, and average pore diameter (A) / average pore diameter (B) It is a leather-like base material in which the content ratio of the porous polymer elastic body to the total amount of the nonwoven fabric and the porous polymer elastic body is 15 to 50% by mass.

The leather-like base material preferably has an apparent density of 0.1 to 0.4 g / cm ³ .

  Moreover, it is preferable that the nonwoven fabric and the porous polymer elastic body are not bonded.

  The porous hollow fiber is preferably a porous hollow polyamide fiber.

  Another aspect of the present invention is an artificial leather including any one of the above leather-like base materials.

  Another aspect of the present invention is a polishing pad including any one of the above leather-like substrates.

  ADVANTAGE OF THE INVENTION According to this invention, the leather-like base material excellent in the softness | flexibility (flexibility) and lightness is obtained.

It is a model longitudinal cross-sectional view of the leather-like base material 10 of this embodiment. It is a model expansion longitudinal cross-sectional view of the leather-like base material 10 of this embodiment. It is a model expansion longitudinal cross-sectional view of the artificial leather 20 of this embodiment. It is an imaging by SEM of the leather-like base material obtained in Example 1.

  An embodiment of a leather-like base material according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic longitudinal sectional view of a leather-like base material 10 of the present embodiment. The leather-like base material 10 includes, for example, a nonwoven fabric 1 in which porous hollow fibers 1a having a fineness of about 0.5 to 10 dtex are entangled three-dimensionally, a porous polymer elastic body 2 impregnated in the nonwoven fabric 1, and including. The content ratio of the porous polymer elastic body 2 is in the range of 15 to 50% by mass with respect to the total amount of the nonwoven fabric 1 and the porous polymer elastic body 2.

FIG. 2 is a schematic enlarged longitudinal sectional view of the leather-like base material 10. As shown in FIG. 2, the porous hollow fiber 1 a has a hollow portion v <b> 1 having a pore diameter (average pore diameter (A)) of 1 to 10 μm on its cross section. A porous polymer elastic body 2 is present around the porous hollow fiber 1a.
The porous polymer elastic body 2 is a sponge-like elastic body having fine pores v2. The pore diameter (average pore diameter (B)) of the micropores v2 of the porous polymer elastic body is 1 to 10 μm. The average pore size (A) (average pore size (A) / average pore size (B)) of the cross section of the porous hollow fiber 1a with respect to the average pore size (B) of the micropores v2 of the porous polymer elastic body is 0.5. It is the range of ~ 2.

First, the porous hollow fiber 1a will be described in detail.
The resin forming the porous hollow fiber is not particularly limited, and specific examples include polyamides such as polyamide 6; polyolefins such as polypropylene and polyethylene; polyesters such as polyethylene terephthalate and isophthalic acid-modified polyethylene terephthalate. These may be used alone or in combination of two or more. Among these, polyamide 6 is preferable because it is excellent in stability of melt spinning and particularly excellent in mechanical properties and buckling resistance.

  Further, the resin forming the porous hollow fiber may contain a coloring agent such as a dye or a pigment, an ultraviolet absorber, a heat stabilizer, a deodorant, a fungicide, various stabilizers and the like as necessary.

  The fineness of the porous hollow fiber 1a is not particularly limited, but is preferably in the range of 0.5 to 10 dtex, more preferably 1 to 6 dtex. When the fineness is too high, the suppleness of the obtained leather-like base material tends to decrease, and the tactile sensation tends to be strong. Further, if the fineness is too low, the fiber density tends to be too high during production, and it tends to be difficult to maintain light weight.

  The porous hollow fiber 1a has a hollow portion v1 having a pore diameter (average pore diameter (A)) of 1 to 10 μm in the cross section thereof. Moreover, it is preferable that the number of the hollow parts v1 in the cross section of the porous hollow fiber 1a is 5-50 pieces, Furthermore, 10-30 pieces. When the number of hollow portions is too small, it becomes difficult to form a hollow structure having homogeneous partition walls. Moreover, when there are too many hollow parts, there exists a tendency for an average hole diameter (A) to become low too much. In this case, the hollow portion v1 is easily crushed.

The hollow ratio per hollow portion v1 in the cross section of the porous hollow fiber 1a is preferably 1 to 10%, more preferably 2 to 5%. Here, the hollow ratio per one hollow portion v1 is
This is the ratio of the area per hollow portion v1 to the total area inside the outer peripheral contour of the cross section of the porous hollow fiber 1a. If the hollowness ratio per hollow part v1 is too high, the hollow part will be easily crushed when subjected to external forces such as bending and compression, resulting in reduced lightness and reduced buckling resistance. It becomes easy. In addition, when the hollow ratio per hollow portion v1 is too low, the average pore diameter (
A) tends to be too low.

Moreover, it is preferable that the total hollow ratio of the hollow part v1 in the cross section of the porous hollow fiber 1a is 25 to 50%, and further 30 to 40%. Here, the total hollow ratio of the hollow portion v1 is a ratio of the total area of all the hollow portions v1 to the total area inside the outer peripheral contour of the cross section of the porous hollow fiber 1a. When the total hollow ratio is too low, it tends to be difficult to reduce the weight sufficiently, and when it is too high, the hollow portion is easily crushed by receiving external force such as bending and compression. There is a tendency for lightness to decrease and buckling resistance to decrease.

The porous hollow fiber 1a may be a long fiber (filament) or a short fiber (staple), but is preferably a long fiber from the viewpoint of excellent tear strength and the like. The long fibers are continuous long fibers, and are distinguished from so-called staples, which are short fibers cut to a predetermined fiber length.

  The nonwoven fabric 1 is a nonwoven fabric in which the porous hollow fibers 1a are three-dimensionally entangled. Such a non-woven fabric is formed, for example, by selectively dissolving and removing a resin component forming an island component from a three-dimensional entangled non-woven fabric made of sea-island composite filaments, as will be described later.

The apparent density of the nonwoven fabric 1 is not particularly limited, but is preferably 0.05 to 0.3 g / cm ³ , and more preferably 0.1 to 0.2 g / cm ³ from the viewpoint of excellent flexibility.

Moreover, the fabric weight of the nonwoven fabric 1 is 100-1000 g / m < ² >, Furthermore, 200-600 g /
m ² is preferable from the viewpoint of light weight.

  Next, the porous polymer elastic body 2 will be described in detail.

  As shown in FIGS. 1 and 2, the porous polymer elastic body 2 is applied to the voids present inside the nonwoven fabric 1.

  Specific examples of the resin forming the porous polymer elastic body 2 include, for example, polyurethane, polyvinyl chloride, polyamide, polyester, polyester ether copolymer, polyacrylate copolymer, neoprene, styrene butadiene copolymer, silicone resin, polyamino acid And an elastic body such as a polyamino acid polyurethane copolymer. These may be used alone or in combination of two or more. Among these, polyurethane is particularly preferable from the viewpoint of obtaining a soft texture. Moreover, the polymer elastic body 2 may contain a pigment, a dye, a crosslinking agent, a filler, a plasticizer, various stabilizers, and the like as necessary.

As shown in FIGS. 1 and 2, the porous polymer elastic body 2 is a sponge-like elastic body having fine holes v2. The pore diameter (average pore diameter (B)) of the micropores v2 of the porous polymer elastic body is 1 to 10 μm, preferably 3 to 7 μm. The number of micropores v2 in the porous polymer elastic body per unit cross-sectional area is 20 to 200/10000 μm ² , and further 50 to 150 /
It is preferably 10,000 μm ² . When the number per unit cross-sectional area of the fine holes v2 is too small, the supple texture tends to decrease. In addition, when the number of the fine holes v2 per unit cross-sectional area is too large, the resilience of the base material becomes strong, resulting in a rubber-like texture.

  The content rate of the porous polymer elastic body 2 is 15-50 mass% with respect to the total amount of the nonwoven fabric 1 and the porous polymer elastic body 2, Preferably it is 20-50 mass%. When the content of the porous polymer elastic body 2 is less than 15% by mass, durability, shape stability, and surface smoothness are lowered, buckling resistance is lowered, and bending bends are also generated. It becomes easy. Moreover, when the content rate of the polymeric elastic body 2 exceeds 50 mass%, it becomes a rubber-like hard texture and the lightness falls.

The porous polymer elastic body 2 is integrated by impregnating the voids inside the nonwoven fabric 1, but the porous polymer elastic body 2 is between the surface of the porous hollow fiber 1 a forming the nonwoven fabric 1. It is preferable to have voids. In other words, it is preferable that the surface of the porous hollow fiber 1a and the porous polymer elastic body 2 are not substantially bonded or slightly bonded. Specifically, for example, as shown in FIG. 2, in the cross section of the leather-like base material 10, the porous polymer elasticity is in the range of 0 to 50%, further 0 to 30% of the outer periphery of the porous hollow fiber 1 a. It is preferable that the body 2 is bonded, and the range of 50 to 100%, more preferably 70 to 100% of the outer periphery is not bonded to the porous polymer elastic body 2. Thus, when the porous polymer elastic body 2 is not firmly bonded and fixed to the outer peripheral surface of the porous hollow fiber 1a, the porous hollow fiber 1a and the porous polymer elastic body 2 are appropriately shifted from each other. Is possible. As a result, a leather-like base material having a supple texture can be obtained, and the occurrence of buckling wrinkles that occur due to the difference in elongation characteristics between the porous hollow fiber 1a and the porous polymer elastic body 2 even when bent. Is suppressed.

  The ratio of the porous polymer elastic body adhered to the outer periphery of the cross section of the porous hollow fiber is determined by observing the cross section in the thickness direction of the leather-like substrate with an electron microscope, and in the observation field of view, the axial direction of the porous hollow fiber For example, 50 cross sections perpendicular to the cross section are selected, and the outer peripheral length of each cross section and the length of the portion where the polymer elastic body is bonded to the outer periphery of each cross section are measured. Every time, it is obtained by calculating the ratio of the length of the portion where the polymer elastic body is bonded to the entire length of the outer periphery.

And the leather-like base material 10 of this embodiment is the average pore diameter (A) (average pore diameter (A) of the cross section of the porous hollow fiber 1a with respect to the average pore diameter (B) of the micropore v2 of the porous polymer elastic body. / Average pore diameter (B)) is 0.5-2. Thus, the average pore diameter (A) / average pore diameter (B) is 0.5 to 2, so that the texture of the fibers and the porous polymer elastic body in the leather-like substrate is not impaired, and the texture as a whole A sense of unity can be obtained. When the average pore diameter (A) / average pore diameter (B) is less than 0.5, the texture of the porous polymer elastic body becomes too soft with respect to the nonwoven fabric, resulting in a texture with a large crease and a lack of fullness. On the other hand, when the number exceeds 2, there is a sense of fulfillment but a hard rubber-like texture.

  Although the thickness of a leather-like base material is not specifically limited, It is preferable that it is the range of 0.3-3 mm, Furthermore, 0.7-1.8 mm. When the thickness of the leather-like base material is too thin, durability and mechanical properties that can withstand practicality tend to be difficult to obtain, and when it is too thick, the lightness tends to be thinned.

The apparent density of the leather-like substrate is 0.1 to 0.4 g / cm ³ , and further 0.2 to 0.3.
It is preferably g / cm ³ . When the apparent density is too high, the supple texture of the resulting leather-like base material tends to be lost, and when the apparent density is too low, the mechanical properties tend to decrease.

Next, an example of the manufacturing method of the leather-like base material of this embodiment will be described in detail.
In the method for producing a leather-like base material of the present embodiment, first, the resin that forms the porous hollow fiber as described above is used as a sea component, and selectively extracted with a chemical or physical property different from that of the resin used as the sea component. For example, a sea-island type composite fiber having a fineness of 0.5 to 10 dtex is manufactured using a resin other than the resin that becomes a removable sea component as an island component. And the sea-island type composite fiber web is formed. The sea-island type composite fiber may be a long fiber or a short fiber, but in the present embodiment, an example of forming a long fiber web will be described as a representative example.

  A long fiber web of sea-island type composite fibers is formed using a so-called spunbond method. Specifically, a resin for forming a sea component and a resin for forming an island component that can be selectively extracted and removed are melt-combined to obtain a strand of sea-island composite fibers. Subsequently, after the obtained strands of sea-island type composite fibers are cooled by a cooling device, they are drawn by a high-speed air flow at a speed corresponding to a take-up speed of 1000 to 6000 m / min, for example, by a suction device such as an air jet nozzle. Thus, a filament of a sea-island composite fiber (hereinafter also referred to as a sea-island composite filament) is obtained. A spunbond sheet is obtained by depositing the sea-island type composite filament on a collection surface such as a movable net while opening the sea-island composite filament.

The sea-island type composite filament is composed of a resin for forming a sea component and a resin for forming a selectively extractable island component having a different chemical or physical property from the resin for forming the sea component. Is a long-fiber composite fiber having a sea-island cross section. Then, by selectively extracting and removing the island component resin from such a sea-island type composite filament, a porous hollow fiber filament mainly composed of a resin for forming the sea component is formed.

  Examples of the resin for forming the sea component include various resins that form porous hollow fibers as described above. In addition, the resin that can be extracted and removed to form the island component is different from the resin that forms the sea component in terms of solubility in solvents or decomposability to the decomposing agent, and resin that has low compatibility with the resin that forms the sea component. Any resin that can be melt-spun can be used without particular limitation. Specific examples of such a resin include, for example, a water-soluble thermoplastic polyvinyl alcohol resin (hereinafter, also simply referred to as “PVA”), polystyrene having different solvent solubility from the resin forming the sea component, and ethylene propylene copolymer. Examples thereof include a copolymer, an ethylene vinyl acetate copolymer, a styrene ethylene copolymer, and a styrene acrylic copolymer. In these, PVA is especially preferable from the point that the outer wall and partition which form a hollow part are hard to be destroyed. Furthermore, PVA is preferable from the viewpoint of low environmental load. In this embodiment, the case where PVA is used as a sea component will be described in detail as a representative example.

  PVA is polyvinyl alcohol that can be dissolved in hot water by saponifying a polymer containing a vinyl ester unit derived from a fatty acid vinyl ester monomer and another copolymer unit included as necessary. can get.

  Specific examples of the fatty acid vinyl ester monomer include, for example, vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, and versatha. Examples thereof include vinyl tick acid.

  Further, specific examples of the monomer that forms other copolymer units included as necessary include, for example, α-olefins having 4 or less carbon atoms such as ethylene, propylene, 1-butene, and isobutene; methyl vinyl ether , Vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, and the like. Among these, ethylene is particularly preferable from the viewpoint of excellent mechanical properties of the obtained artificial leather. As a content rate of the other copolymerization unit in PVA, it is preferable to contain 1-20 mol%, further 4-15 mol%, especially 6-13 mol%.

  As PVA, a modified PVA obtained by saponifying a polymer mainly containing vinyl ester units derived from vinyl acetate containing 4 to 15 mol%, further 6 to 13 mol% of ethylene units is commonly used. This is particularly preferable from the viewpoint of excellent polymerizability, melt spinnability and water solubility of the fiber.

  The degree of polymerization of PVA is preferably 200 to 500, more preferably 230 to 470, and particularly preferably 250 to 450 from the viewpoint of excellent melt spinning stability and dissolution / removability to hot water.

In addition, the said polymerization degree (P) means the viscosity average polymerization degree measured according to JIS-K6726. Specifically, after re-saponification and purification of PVA, the intrinsic viscosity [η] measured in water at 30 ° C. is obtained by the following formula.
P = ([η] 10 ³ /8.29) ^{(1 / 0.62)}

  The degree of saponification of PVA is from 90 to 99.99 mol%, more preferably from 93 to 99.98 mol%, especially from 94 to 99.97 mol%, in particular from 96 to 99.96 mol%. Preferably there is. If the degree of saponification is too low, melt spinnability tends to decrease or water solubility tends to decrease.

  The melting point (Tm) of PVA is preferably in the range of 160 to 230 ° C., more preferably 170 to 227 ° C., and particularly preferably 175 to 224 ° C., more preferably 180 to 220 ° C. When the melting point is too low, the thermal stability of PVA is lowered, and thus fiberization tends to be difficult. Further, when the melting point is too high, the melting point and the decomposition temperature are close to each other, so that there is a tendency that stable spinning cannot be performed.

  The melting point of PVA is that when DSC is used, the temperature is raised to 300 ° C. in nitrogen at a heating rate of 10 ° C./min, cooled to room temperature, and then heated again to 300 ° C. at a heating rate of 10 ° C./min It means the temperature at the peak top of the endothermic peak indicating the melting point of PVA.

  PVA is obtained by radical polymerization using a bulk polymerization method, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, or the like. Among these, a bulk polymerization method in which polymerization is performed without solvent and a solution polymerization in which polymerization is performed in a polar solvent such as alcohol are preferably used. Specific examples of the polar solvent used in the solution polymerization include lower alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol. Specific examples of radical polymerization initiators include azo initiators such as a, a′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethyl-valeronitrile), Examples thereof include peroxide initiators such as benzoyl oxide and n-propyl peroxycarbonate. Moreover, although superposition | polymerization temperature is not specifically limited, For example, the range of 0-150 degreeC is mentioned.

  In the melt composite spinning, the number of islands is preferably 5 to 50 islands / fiber cross section, more preferably 9 to 30 islands / fiber cross section.

  Moreover, the thickness of the partition wall having a hollow structure formed by the sea component is preferably about 0.5 to 5 μm. In such a range, it is preferable because the extraction and removal processing of island components is easy.

  Furthermore, the ratio of the resin for forming the island component in the sea-island composite filament is preferably 25 to 60% by mass, more preferably 30 to 55% by mass. When the proportion of the resin for forming the island component is too high, the proportion of the hollow portion formed tends to be too high, and when it is too low, the proportion of the hollow portion formed tends to be too low. There is.

  After the sea-island type composite strand formed by melt composite spinning is cooled by a cooling device, it has a speed corresponding to a take-up speed of 1000 to 6000 m / min so as to achieve a desired fineness using a suction device such as an air jet nozzle. Stretched by high-speed airflow. Then, the spunbond sheet is formed by depositing the stretched sea-island type composite fiber on the movable collection surface. At this time, the spunbond sheet may be partially crimped as necessary.

  The fineness of the sea-island composite filament is preferably in the range of 0.7 to 12.5 dtex, and more preferably in the range of 2.5 to 8 dtex, from the viewpoint of excellent island component extraction and removal.

  Moreover, it is preferable from the point of stability of the hollow structure of the hollow fiber obtained that the fineness of the island part which forms a sea-island type composite filament is 0.5-5 dtex, Furthermore, it is the range of 2-5 dtex.

Further, the basis weight of the spunbond sheet is preferably in the range of ^{20 to} 50 g / m ² from the viewpoint of excellent productivity.

Next, two or more spunbond sheets obtained as described above are superposed and an entangled web is formed by needle punching. This step is a step of obtaining an entangled web in which fibers are entangled in the thickness direction by performing an entanglement process by needle punching after overlapping a plurality of spunbond sheets. The number of spunbond sheets to be superimposed is not particularly limited, but is preferably 4 or more, and more preferably 8 or more.

  An entangled web is formed by performing an entanglement process by needle punching on an overlapped body obtained by overlapping a plurality of spunbond sheets.

  The type of felt needle used for needle punching is not particularly limited. In order to sufficiently increase the entanglement of the fibers in the thickness direction, it is preferable to use a thin felt needle or a felt needle with few barbs such as a 1 barb needle. Moreover, it is preferable to use felt needles, such as 3 barb, 6 barb, and 9 barb, from the point which suppresses the cutting | disconnection of a sea island type composite filament.

Further, the number of felt needles used in needle punching per unit area is not particularly limited, but a range of 200 to 2500 / cm ² is preferable.

The basis weight of the entangled web thus obtained is preferably 100 to 3000 g / m ² , more preferably 200 to 1000 g / m ² .

  In addition, it is preferable to heat-press the obtained entangled web in order to smooth the surface or adjust the thickness. Examples of the heating press method include a method of passing between a plurality of heating rolls, a method of passing a preheated entangled web between cooling rolls, and the like. During pressing, an adhesive such as polyvinyl alcohol, starch, or resin emulsion may be applied to the entangled web. Thus, by apply | coating an adhesive agent, the press-fit state of a fiber and the form of an entanglement web are controllable. By such a heating press, the surface of the entangled web is smoothed and the thickness is adjusted.

  The rate of decrease in the thickness of the entangled web after pressing relative to the thickness of the entangled web before pressing is preferably 5 to 30%, and more preferably 10 to 25%.

  Next, the hot-pressed entangled web is impregnated with a solution of the polymer elastic body, and then the polymer elastic body is dry-type or wet-solidified. Specifically, for example, it is preferable to impregnate a polymer elastic body solution obtained by dissolving a polymer elastic body in an organic solvent into an entangled web after pressing, and then wet-solidify the polymer elastic body.

  The porous polymer elastic body can be solidified by impregnating the hot-pressed entangled web with the polymer elastic body solution and immersing it in a wet coagulation bath.

  Examples of the polymer elastic body include polyurethane, polyvinyl chloride, polyamide, polyester, polyester ether copolymer, polyacrylate copolymer, neoprene, styrene butadiene copolymer, silicone resin, polyamino acid, polyamino acid polyurethane copolymer, and the like.

  Examples of the organic solvent for preparing the polymer elastic body solution include acetone, methyl ethyl ketone, tetrahydrofuran, N, N-dimethylformamide (DMF) and the like.

The pore diameter and the number of pores of the porous polymer elastic body can be adjusted by the composition of polyurethane, the coagulating liquid component and temperature of the wet coagulation bath, and the type and amount of coagulation regulator. For example, when polyurethane is used as the polymer elastic body, a DMF solution of polyurethane is used as the polymer elastic body solution because it has excellent wet coagulation properties. The polyurethane concentration in the polyurethane solution is preferably about 10 to 25% by mass. Moreover, when using a polyurethane solution, it is preferable to wet-coagulate in DMF aqueous solution with a liquid temperature of 20-50 degreeC. As the DMF aqueous solution, a 0 to 40% by mass aqueous solution of DMF is preferably used.

  Examples of the method for impregnating the entangled web with the polymer elastic body solution include a method using a knife coater, a bar coater, or a roll coater, or a dipping method.

  Next, a non-woven fabric made of porous hollow fibers is formed by dissolving and removing the island component resin from the sea-island composite filament. In this step, it is preferable to extract and remove all or most (for example, 95% or more) of the resin that forms the island component contained in the sea-island composite filament.

  By treating the entangled web provided with the polymer elastic body in hot water containing a surfactant, the island component resin such as PVA is dissolved and removed from the sea-island composite filament forming the entangled web. .

  In the case of PVA, examples of the hot water treatment include a method of treating at a water temperature of 80 to 95 ° C. using a dyeing machine such as a liquid dyeing machine or a jigger, or a scouring machine such as an open soaper. In particular, in order to improve the extraction efficiency, it is preferable to use a liquid flow dyeing machine that can physically deform the hollow fiber, or a device that combines a vibro washing machine and a squeezing device in multiple stages.

  In addition, nonionic surfactants such as poly (oxyethylene) alkyl ethers that improve the wettability of sea component resins and known anionic surfactants to improve the extraction efficiency of island component resins It is preferable to use hot water containing an agent. As such a surfactant, the HLB (Hydrophile-Lipophile Balance) is preferably in the range of 4-16.

  And after extracting and removing all or most of resin of island components, such as PVA, contained in a sea-island type composite filament, the leather-like base material of this embodiment is obtained by drying.

  The leather-like substrate of the present embodiment thus obtained is a flexible substrate having low rigidity. Therefore, the leather-like base material of the present embodiment can be preferably used as artificial leather used as a surface material for footwear, bags, clothing, furniture, etc., having a supple texture and excellent lightness and buckling resistance.

  Artificial leather is obtained by subjecting the above-described leather-like base material to post-processing such as silver surface treatment, raising treatment, softening treatment, two-division treatment, molding treatment, and dyeing treatment according to various uses.

  For example, when producing a silver-tone artificial leather, a resin skin layer containing a polymer elastic body is formed on the surface of a leather-like base material. FIG. 3 is a schematic cross-sectional view of the artificial leather 20 in which the resin skin layer 4 is formed on the surface of the leather-like base material 10.

  The resin skin layer can be formed by directly applying a dispersion or solution of a polymer elastic body to the surface of a leather-like substrate and then coagulating the polymer elastic body, or by releasing paper on the surface of the leather-like substrate. A method of bonding the resin skin layer formed on the top with an adhesive or the like is used. As the polymer elastic body used for forming the resin skin layer, a polymer elastic body conventionally used for the production of silver surface artificial leather can be used without any particular limitation.

The resin forming the resin skin layer is not particularly limited. Specifically, a polyurethane resin, an acrylic resin, a polyamide resin, a polyester resin, a polyolefin resin, etc. are mentioned, for example. Among these, a polyurethane resin or an acrylic resin is preferable because it is excellent in surface wear resistance, flex resistance, surface touch property, durability, and the like.

  The thickness of the resin skin layer is not particularly limited, but is preferably 20 to 500 μm, and more preferably 50 to 300 μm. When the thickness of the resin skin layer is too thick, the lightness tends to decrease, and when the thickness is too thin, the surface of the artificial leather tends not to be sufficiently protected and decorated.

  The resin skin layer may be a silver-like one having a smooth surface or a surface decorated by embossing or the like. Moreover, a desired function, texture, etc. can also be provided by setting it as a porous structure or a non-porous structure.

The apparent density of the artificial leather obtained as described above is not particularly limited, but the range of 0.25 to 0.35 g / cm ³ is a balance between durability, light weight, and buckling resistance. From the point which is excellent in it. The thickness of the artificial leather is not particularly limited, but is preferably in the range of about 0.3 to 4 mm.

  Moreover, the leather-like base material of this embodiment is a flexible base material with low rigidity as mentioned above. Therefore, the leather-like substrate of the present embodiment can be preferably used as a polishing pad used in CMP having excellent followability with respect to the shape of the surface of the substrate to be polished.

  The polishing pad is obtained by subjecting the above-described leather-like base material to a forming process, a flattening process, a raising process, a lamination process, a surface process, and the like.

  The forming process and the flattening process are processes in which the surface of the obtained leather-like base material is hot press-molded to a predetermined thickness by grinding or cut into a predetermined outer shape. The polishing pad is preferably ground to a thickness of about 0.5 to 3 mm.

  Brushing treatment is a process of raising porous hollow fibers by applying mechanical frictional force or polishing force to the surface of a polishing pad with sandpaper, needle cloth, diamond, etc. on the surface of a flattened leather-like substrate. is there. By such a raising treatment, the porous hollow fiber on the surface is raised.

  The lamination process is a process for adjusting rigidity by laminating a leather-like substrate to be processed into a polishing pad on various substrates such as sponge, nonwoven fabric, rubber, and resin film. Thus, by laminating | stacking with another base material, the planarization performance of the polishing pad obtained can be improved further.

  The surface treatment is a treatment for forming grooves, holes such as lattices, concentric circles, and spirals on the surface of the polishing pad in order to adjust the retention and discharge of the abrasive slurry.

  The polishing pad obtained by processing the leather-like substrate of the present embodiment includes a wafer (silicon wafer, compound semiconductor wafer, semiconductor wafer, etc.), liquid crystal / display member (LED substrate, glass substrate), semiconductor product, glass product, Metal products, plastic products, ceramic products, crystals, MEMS (micro-electro-mechanical systems), other substrates (hard disk substrates, metal substrates, plastic substrates, ceramic substrates, optical substrates, electronic circuit substrates, electronic circuit mask substrates, multilayers It is preferably used as a polishing pad for polishing various substrates to be polished such as a wiring board, a hard disk substrate and the like.

  EXAMPLES The present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples. Moreover, the part and% which are described in an Example are related with mass unless there is particular notice.

  First, the measurement method and the evaluation method used in this example will be described together.

[Measurement of average pore diameter (A) of cross section of porous hollow fiber]
A cross section in the thickness direction of the obtained leather-like base material was photographed with a scanning electron microscope at a magnification of about 200 to 1000 times. Then, 20 cross sections perpendicular to the axial direction of the observed porous hollow fiber were selected so as not to be biased. And the diameter of the some hole contained in each of each cross section was calculated | required.

[Measurement of average pore diameter (B) of porous polymer elastic body]
The pore diameters of ten porous polymer elastic bodies were uniformly obtained and averaged from the images obtained in the same manner as obtained with “average pore diameter (A) of the cross section of the porous hollow fiber”. The average pore diameter (B) of the porous polymer elastic body was obtained by further averaging the values obtained from the average values obtained from the respective five images.

[Flexibility test]
A sample obtained by cutting the obtained leather-like base material into a 200 × 200 mm square was put into the palm and judged by the following criteria based on the tactile sensation.
A: It has a waist and has a flexible flexibility.
B: A texture with a large crease and a lack of unity, or a strong resilience and a rubber-like texture.

[Measurement of apparent density of leather-like substrate]
The apparent density (g / cm ³ ) was obtained by dividing the mass (g / cm ² ) per unit area of the obtained leather-like substrate by its thickness (cm). The result is the arithmetic average value of the apparent density measured for any 10 locations. The thickness was measured under a load of 240 gf / cm ² according to JISL1096.

[Buckling resistance test]
The bent shape generated when the obtained leather-like base material was cut into a square of 200 × 200 mm was valley-folded so that the upper end and the lower end were aligned was visually observed. And it determined with the following references | standards.
A: Dense and uniform folding wrinkles were generated on the surface, similar to when folding cowhide leather.
B: It was an intermediate state between A and C.
C: Rough wrinkles such as corrugated cardboard were generated on the folded surface.

[Example 1]
Polyamide 6 (PA6) as a sea component, water-soluble thermoplastic PVA as an island component, and a sea-island type composite fiber strand of 12 islands having a sea component / island component mass ratio of 50/50 at 240 ° C. The product was discharged from the base. Ube nylon 1011 manufactured by Ube Industries, Ltd. was used as polyamide 6, and Exeval CP-4104MI (melting point 209 ° C., MFR measured by M method of JIS K7210: 80) manufactured by Kuraray Co., Ltd. was used as water-soluble thermoplastic PVA.
Then, the resin strand discharged from the die was cooled while being stretched and thinned by an air jet suction device installed immediately below the die, thereby spinning a sea-island composite filament having an average fineness of 3.0 dtex. The suction force of the air jet suction device was adjusted so that the spinning speed obtained indirectly from the ratio of the discharge amount per unit time and the fineness of the obtained long fibers was 2000 m / min. Then, the sea-island type composite filament is continuously collected on a mobile net installed just under the air jet suction device, and pressed at a linear pressure of 25 kg / cm using a metal roll having a surface temperature of 50 ° C. A spunbond sheet of / m ² was obtained.

The spunbond sheets were overlapped using a cross wrapper so as to have a basis weight equivalent to eight sheets. Further, the needle breakage preventing oil was uniformly applied to the surface of the spunbond sheet using a spray. Next, the needle punching process was alternately performed on both surfaces of the spunbond sheet to entangle the sea-island type composite filaments, thereby obtaining an entangled web having a basis weight of 350 g / m ² . The entangled web was pressed with a pair of smooth metal rolls having a surface temperature of 180 ° C. to compress the thickness to 85% before pressing. Then, both surfaces were smoothed by buffing with 180th sandpaper. In this way, an entangled web having a thickness of 2.7 mm and a density of 0.13 g / cm ³ and a smooth surface was obtained.

  Next, the smoothed entangled web was impregnated with PVA having a solid content concentration of 4% by mass and dried. Further, both surfaces were smoothed by buffing with 240th sandpaper. Then, impregnation with a polyester polyurethane DMF solution having a solid content concentration of 13% by mass, followed by immersion in a coagulation bath storing a mixed solution of DMF and water (DMF concentration of 30% by mass) to form a porous polyurethane elastic body. Solidified.

Next, using a flow dyeing machine, entangled in 95 ° C hot water containing 0.1% nonionic surfactant (Sunmol BK-57NM manufactured by Nikka Chemical Co., Ltd.) with an HLB of 5.5. PVA as an island component was dissolved and removed from the sea-island type composite filament in the web. And the three-dimensional entangled nonwoven fabric of porous hollow filaments of polyamide 6 having a thickness of 1.3 mm, a basis weight of 350 g / m ² and having 12 hollow portions in the cross section and a porous polyurethane elastic body by drying treatment A leather-like substrate containing was obtained.

  The mass ratio of the porous hollow filament of polyamide 6 and the porous polyurethane elastic body of the obtained leather-like base material was porous hollow filament / porous polyurethane elastic body = 50/50. Moreover, from the image by SEM of the cross section of a porous hollow filament, the average hole diameter (A) of the several hole of a cross section was 5 micrometers, and the average hole diameter (B) of the porous polyurethane elastic body was 5 micrometers. The imaging at this time is shown in FIG. The leather-like substrate thus obtained was evaluated by the method described above. The results are shown in Table 1.

[Examples 2 to 4]
In the production of the leather-like base material of Example 1, the number of islands of the sea-island type composite filament, the mass ratio of the sea component / island component, the fineness of the filament, and the solid content concentration of the porous polyurethane elastic body are as shown in Table 1. A leather-like base material was obtained in the same manner as in Example 1 except for the change. And the leather-like base material obtained in this way was evaluated. The results are shown in Table 1.

[Comparative Example 1]
In the same manner as in Example 1, a smoothed entangled web was obtained. Next, the smoothed entangled web was impregnated with a forced emulsification type aqueous polyurethane emulsion having a solid content concentration of 35% by mass. And nonporous polyurethane was solidified by performing a drying process and a curing process with a hot air of 150 degreeC.

Next, in the same manner as in Example 1, PVA as an island component was dissolved and removed from the sea-island composite filament in the entangled web using a liquid dyeing machine. Then, a three-dimensional entangled nonwoven fabric of polyamide 6 porous hollow filaments having a thickness of 0.9 mm, a basis weight of 350 g / m ² and having 12 hollow portions in the cross section and a non-porous polyurethane elastic body by drying treatment A leather-like substrate containing was obtained.

  The mass ratio of the porous hollow filament of polyamide 6 and the nonporous polyurethane elastic body of the obtained leather-like base material was porous hollow filament / nonporous polyurethane elastic body = 50/50. Moreover, from the SEM image of the cross section of the porous hollow filament, the average pore diameter (A) of the plurality of holes in the cross section was 5 μm. The non-porous polyurethane elastic body was not sponge-like and was an elastic body having substantially no voids. The leather-like substrate thus obtained was evaluated by the method described above. The results are shown in Table 1.

[Comparative Examples 2 to 5]
In the production of the leather-like base material of Example 1, except that the number of islands of the sea-island composite filament, the mass ratio of the sea component / island component, the fineness of the filament, and the wet solidification conditions were changed as shown in Table 1. A leather-like substrate was obtained in the same manner as in Example 1. And the leather-like base material obtained in this way was evaluated. The results are shown in Table 1.

From the results of Table 1, the leather-like substrates of Examples 1 to 4 were all supple and had excellent flexibility, despite their flexibility in the flexibility test. Further, the apparent density was 0.35 g / cm ³ or less, and the lightness was excellent. Therefore, it can be seen that such a leather-like base material can achieve both the natural flexibility and lightness of natural leather when used as artificial leather. In addition, when used as a base material for a polishing pad used in CMP, it can be seen that it has sufficient flexibility to obtain excellent followability with respect to the shape of the surface of the base material to be polished.

On the other hand, the leather-like base materials of Comparative Examples 1 to 5 including the non-porous polyurethane elastic body were not flexible in the flexibility test and had a hard texture. Moreover, the leather-like base material of Comparative Example 1 had an apparent density of 0.41 g / cm ³ and was inferior in lightness.

  Since the leather-like base material of the present invention has excellent suppleness, the manufacture of artificial leather that becomes a surface material for footwear, bags, clothing, furniture, etc., the manufacture of polishing pads used in CMP, and a water purification filter It can be preferably used for such applications.

DESCRIPTION OF SYMBOLS 1 Nonwoven fabric 1a Porous hollow fiber 2 Porous polymer elastic body 3 Artificial leather base material 4 Resin skin layer 10 Leather-like base material v1 Hollow part of porous hollow fiber 1a v2 Micropore of porous polymer elastic body 2

Claims (6)

A leather-like substrate comprising a nonwoven fabric and a porous polymer elastic body impregnated in the nonwoven fabric,
The non-woven fabric is an entangled body of porous hollow fibers having a plurality of holes in the cross section,
The average pore diameter (A) of the plurality of holes in the cross section is 1 to 10 μm,
The porous polymer elastic body has an average pore diameter (B) of 1 to 10 μm,
Average pore diameter (A) / average pore diameter (B) = 0.5-2,
A leather-like base material, wherein a content ratio of the porous polymer elastic body to a total amount of the nonwoven fabric and the porous polymer elastic body is in a range of 15 to 50% by mass. The leather-like base material according to claim 1, which has an apparent density of 0.1 to 0.4 g / cm ³ .   The leather-like base material according to claim 1 or 2, wherein the nonwoven fabric and the porous polymer elastic body are not bonded.   The leather-like substrate according to any one of claims 1 to 3, wherein the porous hollow fiber is a porous hollow polyamide fiber.   An artificial leather comprising the leather-like base material according to any one of claims 1 to 4.   A polishing pad comprising the leather-like base material according to claim 1.