Porous body, and polishing material or cleaning material provided with said porous body

Abstract

To provide a novel porous body that achieves both chemical resistance and wear resistance and has good solvent impregnation.　The present technology provides a porous body that contains a fluororesin as a resin component, has a porosity of 85% or less, an Asker C hardness of 25 or more, and is obtained by extracting and removing a pore-forming material from the resin component. Although conventional materials having high chemical resistance tended to be difficult to mold and had low porous body wear resistance, the present technology achieves both chemical resistance and wear resistance.

Description

Porous body, and polishing material or cleaning material comprising said porous body

[0001] The present technology relates to a porous body and an abrasive material or cleaning material comprising the porous body.

[0002] Porous bodies using resins are used in a variety of fields, including, for example, functional separation membranes such as filters and filtration membranes, water-retaining materials, water-stopping materials, sustained-release materials, stamp pads for use with solvent-based inks, components for absorbing and retaining organic solvents, seepage pads, cosmetic tools, medical tools, abrasive materials, and cleaning materials.

[0003] As the manufacturing method of porous body, a molding is formed by mixing and dispersing a pore-forming material that is soluble in a specific solvent, and then the pore-forming material is extracted and removed to manufacture a porous body.For example, Patent Document 1 discloses a technology that can uniformly distribute the pores of a porous body with high porosity by melting a second pore-forming material made of a water-soluble polymer and kneading it with a first pore-forming material, and covering the granular first pore-forming material with the second pore-forming material.This makes the granular first pore-forming material coated with a water-soluble polymer with lipophilicity well blend with the base material of a water-insoluble polymer, and can be uniformly dispersed in the base material in the kneading process.In addition, in the molding process of a solid molding, only the first pore-forming material is left unmelted, and the base material and the second pore-forming material are melted, so that even if the addition rate of the pore-forming material is increased, the fluidity during molding can be ensured, and the pore distribution of a porous body with high porosity can be uniform.

[0004] Techniques for imparting additional properties to porous bodies depending on their applications are also being developed. For example, Patent Document 2 discloses a fluorine-based thermoplastic elastomer porous body that is chemical-resistant, heat-resistant, and breathable, and describes that the fluorine-based thermoplastic elastomer porous body can be used as a gasket or a cushioning material.

[0005] Furthermore, Patent Document 3 discloses a technology for producing a microporous body having a fine interconnected pore structure that exhibits flexibility, compression recovery, heat resistance, and oil resistance, by mixing a fluororubber with a ketone solvent such as acetone or methyl ethyl ketone to form a viscous slurry to reduce the viscosity, kneading and molding the mixture with a pore-forming material, and then extracting the pore-forming material.

[0006] JP 2014-148581 A JP 2012-102265 A JP 2005-97367 A

[0007] As mentioned above, technologies for imparting new properties to porous bodies are being developed, and a technology for improving chemical resistance by using fluorine-based resins has also been proposed. However, porous bodies manufactured using conventional technologies are too soft and therefore unsuitable for applications requiring abrasion resistance, such as polishing materials or cleaning materials. While increasing the resin density of a porous body can increase its strength, increasing the resin density reduces the internal porosity, resulting in a problem of reduced solvent impregnation performance required for the porous body. Another problem is that increasing the resin density increases the weight of the porous body.

[0008] Therefore, the main object of the present technology is to provide a novel porous body that has both chemical resistance and abrasion resistance and also has an appropriate solvent impregnation property.

[0009] The present technology provides a porous body containing a fluororesin as a resin component, having a porosity of 85% or less, and an Asker C hardness of 25 or more, the porous body being obtained by extracting and removing a pore-forming material from the resin component. The porous body according to the present technology can be a fluororesin having a viscosity at 140°C of 12,400 Pa·s or less at a shear rate of 24 (1 / sec) and a 140°C / 170°C viscosity ratio at the shear rate of 1.0 or more. The porous body according to the present technology can also be a fluororesin having a flexural modulus of 100 MPa or more as measured in accordance with JIS K7171:2016. Furthermore, the porous body according to the present technology can also be a fluororesin having a Shore D hardness of 45 or more. The porous body according to the present technology can be used as a polishing material or a cleaning material.

[0010] Preferred embodiments for implementing the present technology will be described below. The embodiments described below are examples of typical embodiments of the present technology, and any of the embodiments can be combined. Furthermore, the scope of the present technology is not to be interpreted narrowly by these embodiments.

[0011] 1. Porous Body The porous body according to the present technology is obtained by extracting and removing the pore-forming material described below from a resin component. In addition to the resin component and the pore-forming material, a water-soluble polymer that serves as a lubricant and other components depending on the purpose can be used to produce the porous body according to the present technology. The components used in producing the porous body according to the present technology are described in detail below.

[0012] (1) Resin Component The porous body according to the present technology is characterized by containing a fluororesin as a resin component. In the present technology, the fluororesin refers to a polymer of a fluorine-containing monomer or a copolymer of two or more fluorine-containing monomers, such as a copolymer of one or more monomers such as vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene, or perfluoromethyl vinyl ether, with one or more other monomers, as needed, within a range that does not impair the action or effect of the present technology.

[0013] More specifically, examples of the fluororesin used in the present technology include vinylidene fluoride-based fluororesins such as hexafluoropropylene-vinylidene fluoride copolymer, hexafluoropropylene-vinylidene fluoride-tetrafluoroethylene copolymer, chlorotrifluoroethylene-vinylidene fluoride copolymer, 1,2,3,3,3-pentafluoropropylene-vinylidene fluoride copolymer, hexafluoropropylene-vinylidene fluoride-tetrafluoroethylene-brominated olefin copolymer, vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene-brominated olefin copolymer, and vinylidene fluoride-tetrafluoroethylene-propylene copolymer; tetrafluoroethylene-perfluoromethyl vinyl ether copolymer; tetrafluoroethylene-perfluoromethyl vinyl ether-perfluorovinyl polyether copolymer; tetrafluoroethylene-perfluorovinyl ether copolymer; trifluoroethoxyphosphonitrile-pentafluorobutoxyphosphonitrile copolymer; perfluoromethyl vinyl ether-tetrafluoroethylene-brominated olefin-ethylene copolymer, and the like.

[0014] Among these, in the present technology, it is particularly preferable to use a vinylidene fluoride-based fluororesin as the fluororesin, and among vinylidene fluoride-based fluororesins, it is more preferable to use a hexafluoropropylene-vinylidene fluoride copolymer or a hexafluoropropylene-vinylidene fluoride-tetrafluoroethylene copolymer, and it is even more preferable to use a hexafluoropropylene-vinylidene fluoride copolymer.

[0015] The fluorine content in the fluororesin used in the present technology can be freely set as long as it does not impair the functions and effects of the present technology. The lower limit of the fluorine content in the fluororesin is, for example, 50% or more, preferably 55% or more, more preferably 60% or more, and even more preferably 65% ​​or more. By setting the lower limit of the fluorine content in the fluororesin used in the present technology within this range, the chemical resistance, heat resistance, oil resistance, etc. of the produced porous body can be improved.

[0016] The upper limit of the fluorine content in the fluororesin is, for example, 85% or less, preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less. By setting the upper limit of the fluorine content in the fluororesin used in the present technology within this range, the processability of the porous body can be improved.

[0017] The viscosity of the fluororesin used in the present technology can be freely set as long as it does not impair the functions and effects of the present technology, but it is preferable that the viscosity decreases with increasing temperature. Compared to fluororesins whose viscosity remains constant regardless of temperature, using a fluororesin whose viscosity decreases with increasing temperature improves workability during production and makes it possible to adjust the hardness and strength of the porous body after molding, thereby improving the wear resistance of the porous body.

[0018] Specific viscosity limits for the fluororesin used in the present technology are, at a shear rate of 24 (1 / sec), for example, 14,500 Pa·s or less, preferably 14,000 Pa·s or less, more preferably 13,500 Pa·s or less, even more preferably 13,000 Pa·s or less, and particularly preferably 12,400 Pa·s or less. By using a fluororesin whose upper limit on viscosity at 140°C is within this range, the hardness and strength of the molded porous body can be further improved, and as a result, the wear resistance of the porous body can also be further improved. The lower limit on the viscosity of the fluororesin at 140°C can be, for example, 6,000 Pa·s or more at a shear rate of 24 (1 / sec).

[0019] The lower limit of the viscosity of the fluororesin at 170°C is not particularly limited, and it is preferable to use a fluororesin whose viscosity ratio to the viscosity at 140°C described above falls within a specific range. The 140°C / 170°C viscosity ratio of the fluororesin at the shear rate is, for example, 1.0 or more, preferably 1.2 or more, more preferably 1.4 or more, even more preferably 1.6 or more, still more preferably 1.8 or more, and particularly preferably 1.9 or more. By using a fluororesin whose lower limit of the 140°C / 170°C viscosity ratio falls within this range, the moldability range is broadened, and the hardness and strength of the porous body after molding can be adjusted. The upper limit of the 140°C / 170°C viscosity ratio of the fluororesin at the shear rate can be, for example, 5.0 or less.

[0020] In the present technology, the viscosity of the resin is a value measured in accordance with JIS K7119:1999.

[0021] The flexural modulus of the fluororesin used in the present technology can be freely set as long as it does not impair the functions and effects of the present technology. In the present technology, it is particularly preferable to use a fluororesin having a flexural modulus of 100 MPa or more, more preferably 130 MPa or more, even more preferably 150 MPa or more, still more preferably 170 MPa or more, and particularly preferably 180 MPa or more, as measured in accordance with JIS K7171:2016. By using a fluororesin having a flexural modulus in this range, the hardness and strength of the porous body after molding can be improved, and as a result, the wear resistance of the porous body can also be improved.

[0022] The upper limit of the flexural modulus of the fluororesin used is not particularly limited, and is, for example, 400 MPa or less, preferably 350 MPa or less, and more preferably 300 MPa or less. By using a fluororesin whose upper limit of the flexural modulus is within this range, the produced porous body can be prevented from becoming too hard, and when the porous body is used as a polishing material, cleaning material, or the like, damage to the object to be polished can be prevented.

[0023] The heat resistance (material melting point) of the fluororesin used in the present technology can be freely set as long as it does not impair the functions and effects of the present technology. In the present technology, it is particularly preferable to use a fluororesin having a material melting point of 115°C or higher, more preferably a fluororesin having a material melting point of 117°C or higher, and even more preferably a fluororesin having a material melting point of 120°C or higher. By using a fluororesin having a material melting point within this range, the heat resistance of the porous body after molding can be improved.

[0024] The upper limit of the material melting point of the fluororesin used in the present technology is not particularly limited, but when a water-soluble polymer compound described below is used, it is preferably equal to or lower than the heat resistance temperature of the water-soluble polymer compound. A specific upper limit of the material melting point of the fluororesin is, for example, 180°C or lower, preferably 175°C or lower, and more preferably 170°C or lower. By using a fluororesin with a material melting point within this range, the water-soluble polymer compound can be molded in a stable state, and a stable porous body can be molded after molding.

[0025] The hardness of the fluororesin used in the present technology can be freely set as long as it does not impair the functions and effects of the present technology. In the present technology, it is particularly preferable to use a fluororesin having a Shore D hardness of 45 or more, more preferably a fluororesin having a Shore D hardness of 46 or more, even more preferably a fluororesin having a Shore D hardness of 47 or more, even more preferably a fluororesin having a Shore D hardness of 48 or more, and particularly preferably a fluororesin having a Shore D hardness of 49 or more. By using a fluororesin having a Shore D hardness within this range, the hardness and strength of the porous body after molding can be improved, and as a result, the wear resistance of the porous body can also be improved.

[0026] The upper limit of the Shore D hardness of the fluororesin used is not particularly limited, and is, for example, not more than 70, preferably not more than 65, and more preferably not more than 60. By using a fluororesin whose upper limit of Shore D hardness is in this range, the porous body produced can be prevented from becoming too hard, and when the porous body is used as a polishing material, a cleaning material, or the like, damage to the object to be polished can be prevented.

[0027] In the present technology, the Shore D hardness of the resin is a value measured in accordance with ISO 7619-1.

[0028] (2) Pore-forming material Pore-forming materials that can be used in the present technology are preferably substances that are soluble in water, alcohol, or an aqueous alcohol solution (preferably water) and that remain stable when the resin is melted. Specific examples include inorganic substances such as NaCl, KCl, CaCl, NH4Cl, NaNO3, and NaNO2; and organic substances such as TME (trimethylolethane), trimethylolpropane, trimethylolbutane, sucrose, soluble starch, sorbitol, glycine, and sodium salts of various organic acids (e.g., malic acid, citric acid, glutamic acid, succinic acid, etc.), and these can be used alone or in combination of two or more.

[0029] In the present technology, it is particularly preferable to use inorganic substances among these, and among inorganic substances, it is particularly preferable to use NaCl.

[0030] The average particle size of the pore-forming material can be freely set as long as it does not impair the function and effect of the present technology. The lower limit of the average particle size of the pore-forming material is, for example, 10 μm or more, preferably 20 μm or more, and more preferably 30 μm or more. By setting the lower limit of the average particle size of the pore-forming material within this range, the size of the pores in the porous body can be controlled to a certain level or more, and a porous body having excellent formability and wear resistance and a smooth surface can be provided.

[0031] The upper limit of the average particle size of the pore-forming material is, for example, 200 μm or less, preferably 180 μm or less, and more preferably 150 μm or less. By setting the upper limit of the average particle size of the pore-forming material within this range, the pore size of the porous body can be controlled to a certain level or less, and a stable porous body can be obtained.

[0032] In the present technology, the "average particle size of the pore-forming material" refers to the average particle size of the mixed state when two or more pore-forming materials each having a single peak are mixed. In addition, in the present technology, the average particle size refers to the particle size (D-50) at a cumulative frequency of 50% in the particle size distribution measured by laser diffraction.

[0033] The amount of pore-forming material used in the production of the porous body according to the present technology can be freely set as long as it does not impair the function and effect of the present technology. The lower limit of the amount of pore-forming material used in the raw material for the porous body is, for example, 40% by volume or more, preferably 45% by volume or more, and more preferably 50% by volume or more. The upper limit of the amount of pore-forming material used in the raw material for the porous body is, for example, 70% by volume or less, preferably 65% ​​by volume or less, and more preferably 60% by volume or less.

[0034] (3) Water-soluble polymer compounds In the production of the porous body according to the present technology, a water-soluble polymer compound acting as a lubricant may be used. Specific examples include polyethylene glycol, polyethylene oxide, polyethylene glycol diacrylate, polyethylene glycol dioleate, polyethylene glycol diacetate, and other polyethylene glycol derivatives, and these may be used alone or in combination of two or more.

[0035] Among these, polyethylene glycol is particularly preferred in the present technology because it has a high melt flow and high water solubility. When molding is performed by extrusion molding, the molecular weight of the polyethylene glycol is preferably 2,000 to 30,000, more preferably 5,000 to 25,000, and even more preferably 15,000 to 25,000.

[0036] The amount of water-soluble polymer compound used in the production of the porous body according to the present technology can be freely set as long as it does not impair the function and effect of the present technology. The lower limit of the amount of water-soluble polymer compound used in the raw material for the porous body is, for example, 10% by volume or more, preferably 15% by volume or more, and more preferably 20% by volume or more. The upper limit of the amount of pore-forming material used in the raw material for the porous body is, for example, 40% by volume or less, preferably 35% by volume or less, and more preferably 30% by volume or less.

[0037] (4) Others The porous body according to the present technology may contain one or more other components that can be used in general porous bodies, as long as they do not impair the functions and effects of the present technology. For example, any component such as a filler, a colorant, a flame retardant, a plasticizer, an antistatic agent, an antioxidant, an ultraviolet absorber, or an antifungal agent may be included.

[0038] 2. Manufacturing Method of Porous Body The manufacturing method of a porous body according to the present technology involves extracting and removing a pore-forming material from a resin component. In this technology, other steps performed in general manufacturing methods of porous bodies can be freely combined as long as the action and effect of the present technology are not impaired. For example, a porous body can be manufactured by extracting and removing the pore-forming material and the water-soluble polymer compound from a molded product of a mixture obtained by mixing a pore-forming material and a water-soluble polymer compound with a resin component and, if necessary, other components. Heating may be performed as needed during the mixing. Furthermore, the raw materials for the porous body can also be mixed separately as needed.

[0039] More specifically, first, the raw resin components and, if necessary, other components are mixed and kneaded at a predetermined mixing ratio using a predetermined device, and then the mixture is mixed and kneaded with one or more pore-forming materials and a water-soluble polymer compound at a predetermined mixing ratio using a predetermined device to obtain a mixture. The resulting mixture is then molded into a molded body of a predetermined shape using an extruder or the like. The molded body is then immersed in an extraction solvent at a predetermined temperature to extract and remove the pore-forming material and the water-soluble polymer compound, thereby obtaining a porous body with a large number of fine bubbles. The type of extraction solvent that can be used in this technology is not particularly limited and can be freely selected depending on the type of pore-forming material and the type of water-soluble polymer compound used. A specific type of extraction solvent is, for example, water.

[0040] For mixing and kneading the resin component, pore-forming material, and water-soluble polymer compound, kneading devices such as a Labo Plastomill, a single-screw or twin-screw extruder, a kneader, a pressure kneader, a co-kneader, a Banbury mixer, a Henschel mixer, and a rotor mixer can be used. No special equipment is required for this kneading, and the kneading speed, etc., is not particularly limited. The temperature during kneading is appropriately set depending on the melting point of the resin, etc., used. The kneading time depends on the physical properties of the mixture, but is sufficient as long as the mixture is thoroughly mixed and kneaded. The kneaded raw materials can be molded into a desired shape by extrusion, injection, pressing, rolling, blowing, etc.

[0041] The pore-forming material and the water-soluble polymer compound are extracted and removed from the molded article formed into a desired shape by immersing them in a solvent such as water for a predetermined time (for example, 24 to 48 hours, depending on the shape and thickness of the molded article). Any method of immersion may be used, but extraction and removal by immersion in which the entire mixture is brought into contact with water is preferred. The temperature of the water used is not particularly limited as long as it is lower than the melting point of the resin used, but warm water at 15 to 60°C may be used to efficiently remove the water-soluble material.

[0042] 3. Physical Properties of Porous Body (1) Porosity The porosity of the porous body according to the present technology is 85% or less. If the porosity exceeds 85%, the formability of the porous body decreases, making it difficult to manufacture a porous body of high quality. The lower limit of the porosity of the porous body is not particularly limited, but is, for example, 60% or more, preferably 65% ​​or more, more preferably 70% or more, and even more preferably 75% or more. By setting the lower limit of the porosity of the porous body within this range, solvent impregnation can be improved. For example, when the porous body is used as an abrasive material or a cleaning material, the cleaning solvent or the like can sufficiently penetrate into the interior of the porous body, thereby improving the cleaning effect.

[0043] In the present technology, the porosity of the porous body is a value calculated by the method described in the examples below.

[0044] (2) Asker C Hardness The surface hardness of the porous body according to the present technology is 25 or more in Asker C hardness. As long as the Asker C hardness of the porous body according to the present technology is 25 or more, the lower limit is not particularly limited, but is preferably 27 or more, more preferably 28 or more, even more preferably 30 or more, and still more preferably 35 or more. By setting the lower limit of the Asker C hardness of the porous body within this range, the abrasion resistance of the porous body can be further improved.

[0045] The upper limit of the Asker C hardness of the porous body according to the present technology is not particularly limited, but is, for example, not more than 70, preferably not more than 65, and more preferably not more than 60. By setting the upper limit of the Asker C hardness of the porous body within this range, the porous body can be prevented from becoming too hard, and for example, when the porous body is used as an abrasive or the like, damage to the object to be polished can be prevented.

[0046] In the present technology, the Asker C hardness of the porous body is a value measured by a method in accordance with JIS K 7312.

[0047] (3) Tensile strength The tensile strength of the porous body according to the present technology can be freely set as long as it does not impair the action and effect of the present technology, but is, for example, 0.25 MPa or more, preferably 0.30 MPa or more, more preferably 0.35 MPa or more. In addition, the upper limit of the tensile strength of the porous body according to the present technology is not particularly limited, but is usually 5 MPa or less.

[0048] In the present technology, the tensile strength of the porous body is a value measured in accordance with JIS K 6251.

[0049] (4) Tensile elongation The tensile elongation of the porous body according to the present technology can be freely set as long as it does not impair the function and effect of the present technology. The lower limit of the tensile elongation of the porous body according to the present technology is, for example, 50% or more, preferably 65% ​​or more, and more preferably 80% or more. The upper limit of the tensile elongation of the porous body according to the present technology is, for example, 400% or less, preferably 350% or less, and more preferably 300% or less.

[0050] In the present technology, the tensile elongation of the porous body is a value measured in accordance with JIS K 6251.

[0051] (5) Chemical Resistance and Abrasion Resistance The porous body according to the present technology is characterized by having high chemical resistance as well as high abrasion resistance. Conventionally, materials with high chemical resistance have tended to be difficult to mold and have low abrasion resistance as porous bodies, but the present technology is characterized by achieving both chemical resistance and abrasion resistance. The chemical resistance of the porous body according to the present technology is particularly characterized by high resistance to ozone.

[0052] 4. Uses of the Porous Body The porous body according to the present technology can be used for a variety of applications in a variety of fields, taking advantage of its high quality. In particular, the porous body according to the present technology can be used suitably as an abrasive material or a cleaning material, taking advantage of its high abrasion resistance. As an abrasive material or a cleaning material, the porous body according to the present technology can be used even more suitably as an abrasive material or a cleaning material used under ozone water exposure conditions, such as cleaning using ozone water, taking advantage of its high ozone resistance.

[0053] The present technology can also employ the following configurations. [1] A porous body containing a fluororesin as a resin component, having a porosity of 85% or less, and an Asker C hardness of 25 or more, obtained by extracting and removing a pore-forming material from the resin component. [2] The porous body according to [1], wherein the viscosity of the fluororesin at 140°C is 12,400 Pa·s or less at a shear rate of 24 (1 / sec), and the 140°C / 170°C viscosity ratio of the fluororesin at the shear rate is 1.0 or more. [3] The porous body according to [1] or [2], wherein the fluororesin has a flexural modulus of 100 MPa or more as measured in accordance with JIS K7171:2016. [4] The porous body according to any one of [1] to [3], wherein the fluororesin has a Shore D hardness of 45 or more. [5] A polishing material or cleaning material comprising the porous body according to any one of [1] to [4].

[0054] The present technology will be described in more detail below based on examples. Note that the examples described below are examples of typical examples of the present technology, and the scope of the present technology should not be construed as being narrow.

[0055] (1) Production of porous bodies Each raw material shown in Table 1 below was weighed and then kneaded in a Labo Plastomill (temperature: 160°C, time: 10 min, rotation speed: 50 rpm). The kneaded mixture was molded in a hand press (temperature: 160°C, time: 5 min, pressure: 40 kN), cooled with water, and immersed in water to elute the pore-forming material and water-soluble polymer compound overnight (temperature: about 25°C), followed by drying to produce each porous body.

[0056] (2) Measurement and Evaluation of Physical Properties The physical properties of each of the produced porous bodies were measured and evaluated using the following methods.

[0057] [Formability] After the elution of the pore-forming material and the water-soluble polymer compound, those that did not shrink (no change in thickness) were marked with "Good", and those that shrunk (changed in thickness) were marked with "Poor".

[0058] [Porosity] The porosity (%) was calculated by dividing the apparent density of the porous body measured in accordance with JIS K7222 by the density of the resin component, subtracting this divisor from 1, and multiplying the result by 100 to obtain a percentage using the following formula: Porosity (%) = {1 - (apparent density of porous body) / (density of resin component)} × 100 (%).

[0059] [Asker C Hardness] Asker C hardness was measured by a method in accordance with JIS K 7312.

[0060] [Tensile Strength] [Tensile Elongation] The tensile strength and tensile elongation were measured in accordance with JIS K 6251.

[0061] [Ozone resistance] The appearance and tensile elongation of the produced porous body were evaluated for changes before and after immersion in ozone water with an ozone concentration of 20 ppm for 100 hours. Specifically, the change in the appearance of the porous body was evaluated as ○ when no change was observed visually, and × when a change was observed visually. The change in tensile elongation was calculated by taking the tensile elongation of the porous body before immersion in ozone water as 100%.

[0062] [Abrasion resistance] Gauze was placed on the test piece stage of a Gakushin-type friction tester, and the produced porous body was subjected to Gakushin (reciprocating motion) 100 times on the gauze, and the rate of change in weight of the porous body before and after Gakushin testing was calculated. A calculated rate of change of 1% or less was evaluated as ○, more than 2% but less than 5% as △, and 5% or more as ×.

[0063] (3) Results The results are shown in Table 1 below.

[0064]

[0065] (4) Discussion As shown in Table 1 above, Examples 1 to 3, which contained a fluororesin as a resin component, had a porosity of 85% or less, and an Asker C hardness of 25 or more, were excellent in both ozone resistance and abrasion resistance. On the other hand, Comparative Example 1, which used a fluororesin but had an Asker C hardness of less than 25, was slightly poor in ozone resistance but had low abrasion resistance. Comparative Example 2, which used an olefin-based resin, was poor in both ozone resistance and abrasion resistance. Comparative Example 3, which used a fluororesin but had a porosity of more than 85%, was poor in formability and could not be used as a polishing material or cleaning material.

Claims

1. A porous body containing a fluororesin as a resin component, having a porosity of 85% or less and an Asker C hardness of 25 or more, and obtained by extracting and removing a pore-forming material from the resin component.

2. The porous body according to claim 1, wherein the viscosity of the fluororesin at 140°C is 12,400 Pa·s or less at a shear rate of 24 (1 / sec), and the viscosity ratio of the fluororesin at 140°C / 170°C at said shear rate is 1.0 or more.

3. The porous body according to claim 1, wherein the fluororesin has a flexural modulus of 100 MPa or more as measured in accordance with JIS K7171:2016.

4. The porous body according to claim 1, wherein the fluororesin has a Shore D hardness of 45 or more.

5. A polishing material or cleaning material comprising the porous body according to any one of claims 1 to 4.

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