Porous body

Abstract

To provide a porous body with suppressed discoloration.SOLUTION: The present technology provides a porous body containing a resin, a phenolic antioxidant, and a carboxylic acid or its salt. The porous body may be obtained by extracting and removing a pore-forming material from a resin composition containing the resin, the phenolic antioxidant, the carboxylic acid or its salt, and the pore-forming material.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present technology relates to porous bodies. [Background technology]

[0002] Porous bodies using resins have been conventionally produced. Conventional methods for producing porous bodies include, for example, a method for producing a porous body by forming a molded body in which a water-soluble pore-forming material is mixed and dispersed by a wet method or a dry method, and then extracting and removing the pore-forming material.

[0003] Here, phenolic antioxidants and the like are sometimes used to prevent oxidation, but it is known that structural changes in the antioxidant over time can lead to discoloration of the porous body (e.g., yellowing, pinking, etc.).

[0004] In response to this, for example, Patent Document 1 proposes a polyolefin resin composition that contains a polyolefin, a higher fatty acid ester which is an esterification product of a saturated fatty acid having 10 to 30 carbon atoms, a singly hindered phenol-based antioxidant, and a phosphorus-based antioxidant represented by a specific chemical formula (I) or chemical formula (II), in which the content of the higher fatty acid ester is 0.1 to 1.0 part by mass relative to 100 parts by mass of polyolefin, the content of the singly hindered phenol-based antioxidant is 0.03 to 0.3 part by mass relative to 100 parts by mass of polyolefin, and the content of the phosphorus-based antioxidant is 0.03 to 0.3 part by mass relative to 100 parts by mass of polyolefin.

[0005] Furthermore, for example, Patent Document 2 proposes a polyvinyl chloride resin film that contains 10 to 60 parts by weight of a plasticizer and 1 to 5 parts by weight of a stabilizer relative to 100 parts by weight of polyvinyl chloride resin as a main material, and does not contain a phenolic antioxidant as an antioxidant, or, if a phenolic antioxidant is contained, the content thereof relative to 100 parts by weight of the polyvinyl chloride resin is 0.06 part by weight or less and the content in the entire composition is 500 ppm by weight or less. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-203864 A [Patent Document 2] JP 2022-181729 A Summary of the Invention [Problem to be solved by the invention]

[0007] Although technologies relating to porous bodies using resins have been developed in the past, the needs for porous bodies have become more diverse, and the development of porous bodies that are inhibited from discoloring has not been sufficient.

[0008] Therefore, a main object of the present technology is to provide a porous body in which discoloration is suppressed. [Means for solving the problem]

[0009] In this technology, Resin and A phenolic antioxidant, A carboxylic acid or a salt thereof; The present invention provides a porous body comprising: The carboxylic acid or salt thereof may have multiple carboxy groups. The carboxylic acid or salt thereof may be a hydroxy acid having a hydroxy group. The porous body according to the present technology may be obtained by extracting and removing the pore-forming material from a resin composition containing the phenol-based antioxidant, the carboxylic acid or a salt thereof, and a pore-forming material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Preferred embodiments for carrying out the present technology will be described below. The embodiments described below are representative examples of the present technology, and any of the embodiments can be combined. In addition, the scope of the present technology is not narrowed by these embodiments.

[0011] 1.Porous bodies The porous body according to the present technology includes a resin, a phenolic antioxidant, and a carboxylic acid or a salt thereof. The porous body including these components is suppressed from discoloring. Note that the term "discoloration" as used herein is a broad concept including not only yellowing and pinking, but also color changes measured by the difference in values ​​measured by a color difference meter. Each component will be described in detail below.

[0012] (1) Resin The resin that can be used in the present technology includes thermoplastic resins and thermosetting resins, and among these, it is particularly preferable to use thermoplastic resins from the viewpoint of recyclability. Examples of thermoplastic resins include polyolefin resins, thermoplastic elastomers (TPE), thermoplastic polyurethane elastomers (TPU), polyamides, polyimides, and polyacetals, and these can be used alone or in combination of two or more.

[0013] Among these, it is particularly preferable to use a polyolefin resin in the present technology. A polyolefin resin is a resin whose main component is an olefin component unit. A resin whose main component is an olefin component unit is a resin containing 50% by mass or more of an olefin component unit.

[0014] Examples of polyolefin resins that can be used in the present technology include polyethylene, polypropylene, polybutene, polypentene, and copolymers of olefin-based monomers and monomers that can be copolymerized with the olefin-based monomers. These can be used alone or in combination of two or more kinds.

[0015] Examples of polyethylene include ethylene homopolymers such as high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and very low density polyethylene (VLDPE); ethylene-propylene random copolymers, ethylene-propylene block copolymers, ethylene-butene block copolymers, ethylene-butene random copolymers, ethylene-vinyl acetate copolymers, and ethylene-methyl methacrylate copolymers.

[0016] Examples of polypropylene resins include propylene homopolymers such as isotactic polypropylene, syndiotactic polypropylene, and atactic polypropylene; propylene-ethylene random copolymers, propylene-ethylene block copolymers, propylene-butene random copolymers, propylene-butene block copolymers, propylene-ethylene-butene terpolymers, propylene-acrylic acid copolymers, and propylene-maleic anhydride copolymers.

[0017] In the present technology, among these, polyolefin resins having an MFR (melt flow rate) of 1.0 to 5.0 are particularly preferred, and polyolefin resins having an MFR of 2.0 to 4.0 are more preferred.

[0018] (2) Phenolic antioxidants Examples of phenol-based antioxidants that can be used in the present technology include 2,6-di-tert-butyl-p-cresol (BHT, also known as "dibutylhydroxytoluene"), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]-1,3,5-triazine-2,4,6 (1H,3H,5H)-trione, bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylene bis(oxyethylene)], 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, and the like. These can be used alone or in combination of two or more.

[0019] The upper limit of the content of the phenolic antioxidant in the resin relative to the porous body in the entire composition is, for example, 800 ppm by weight or less, preferably 700 ppm by weight or less, and more preferably 600 ppm by weight or less, because by making the content in the entire composition 800 ppm by weight or less, oxidative deterioration is suppressed and durability is improved.

[0020] The lower limit of the content in the entire composition is not particularly limited, but it is preferably contained in a range that allows the antioxidant function to be exerted, for example, 50 ppm by weight or more.

[0021] (3) Carboxylic acid or its salt In this specification, the term "carboxylic acid" refers to an organic acid having at least one carboxy group (-COOH). That is, it is represented by the following general formula (1). m represents an integer of 0 to 1. When m=0, R 1 is a hydrogen atom.

[0022] [ka]

[0023] Here, for m=1, R 1 is a monovalent substituent, and examples of the monovalent substituent include an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxy group, a hydroxy group, a hydroxycarboxylic acid, a carboxy group, a mercapto group, an amino group, a halogen atom (e.g., chlorine, bromine, etc.), an alkyl ether group, a carboxylate group, a sulfonic acid group, a formyl group, a nitro group, a cyano group, a silyl group, a group combining these (e.g., hydroxy acid, a group in which a portion of the above-mentioned substituents is substituted with another substituent, etc.), a group bonded via a divalent linking group such as -O-, -NR-, -S-, -C(=O)-, -C(=O)O-, and -C(=O)NH-, and the like, but are not limited to these in the present technology.

[0024] In addition, R 1 When is an alkyl group and / or an alkenyl group, it may be linear, branched, or cyclic. Adjacent groups may be bonded to each other to form a ring.

[0025] In the present technology, the carboxylic acid or its salt preferably has a plurality of carboxy groups. Specifically, it is preferable that the carboxylic acid or its salt has two or more carboxy groups, and it is particularly preferable that the carboxylic acid or its salt has three or more carboxy groups. This is because discoloration can be more suppressed by the carboxylic acid or its salt having a plurality of carboxy groups. Specifically, examples of compounds having two or more carboxy groups include polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, fumaric acid, maleic acid, and adipic acid, and these can be used alone or in combination of two or more.

[0026] In addition, in the present technology, the carboxylic acid or its salt is preferably a hydroxy acid. In this specification, "hydroxy acid" is a general term for carboxylic acids having a hydroxy group, and is also called hydroxy carboxylic acid, oxy acid, and alcohol acid. By using the carboxylic acid as a hydroxy acid, discoloration can be further suppressed. Specifically, for example, aliphatic hydroxy acids, aromatic hydroxy acids, etc. can be mentioned, and these can be used alone or in combination of two or more.

[0027] Examples of aliphatic hydroxy acids include citric acid, glycolic acid, lactic acid, tartronic acid, glyceric acid, hydroxybutyric acid, malic acid, tartaric acid, citramalic acid, leucic acid, mevalonic acid, pantoic acid, ricinoleic acid, ricineraidic acid, cerebronic acid, quinic acid, shikimic acid, etc. Examples of aromatic hydroxy acids include monohydroxybenzoic acid derivatives such as salicylic acid, creosote acid, vanillic acid, syringic acid, etc.; dihydroxybenzoic acid derivatives such as pyrocatechuic acid, resorcylic acid, protocatechuic acid, gentisic acid, orselliic acid, etc.; trihydroxybenzoic acid derivatives such as gallic acid, etc.; phenylacetic acid derivatives such as mandelic acid, benzilic acid, atrolactic acid, etc.; cinnamic acid and hydrocinnamic acid derivatives such as mellitic acid, phloretic acid, coumaric acid, umbellic acid, caffeic acid, ferulic acid, sinapic acid, etc., and these can be used alone or in combination of two or more.

[0028] In the present technology, among these, citric acid is particularly preferred as the hydroxy acid.

[0029] In addition, in the present technology, the salt may be a salt formed by replacing the hydrogen ion resulting from dissociation of the hydrogen atom in the compound represented by the general formula (1) with a cation such as a metal ion or an ammonium ion, and such salts may be included in the scope of the present technology. Specifically, the salt may be, for example, an inorganic salt or an organic salt. Examples of the inorganic salt include, for example, an alkali metal salt such as sodium or potassium; an alkaline earth metal salt such as calcium or magnesium; and an ammonium salt, and these may be used alone or in combination of two or more. Examples of the organic salt include diethanolamine salts, triethanolamine salts, and basic amino acid salts. These can be used alone or in combination of two or more kinds.

[0030] In the present technology, when the carboxylic acid is citric acid, the lower limit of the content of citric acid is preferably 0.01 wt.% or more, more preferably 0.05 wt.% or more, and particularly preferably 0.1 wt.% or more, based on the total amount of the resin components. By making the content of citric acid 0.01 wt.% or more based on the total amount of the resin components, discoloration can be further suppressed.

[0031] Furthermore, the upper limit of the citric acid content is not particularly limited, but can be, for example, 10 wt.% or less, 7.5 wt.% or less, or 5 wt.% or less from the viewpoint of cost.

[0032] (4) Pore-forming material The pore-forming material that can be used in the present technology is preferably a material that is soluble in water, alcohol, or an alcohol aqueous solution (preferably water) and is stable when the resin is melted. 4 Cl, NaNO 3 , and NaNO 2and 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, succinic acid, etc.), and these can be used alone or in combination of two or more kinds.

[0033] In the present technology, among these, it is particularly preferable to use an inorganic substance, and among the inorganic substances, it is particularly preferable to use NaCl.

[0034] The average particle size of the pore-forming material is preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 180 μm or less, and even more preferably 30 μm or more and 150 μm or less. By setting the average particle size of the pore-forming material to 10 μm or more, the size of the pores in the porous body can be controlled to a certain level or more, and a porous body with excellent formability and wear resistance can be provided. On the other hand, by setting the average particle size of the pore-forming material to 200 μm or less, the size of the pores in the porous body can be controlled to a certain level or less. In addition, the "average particle size of the pore-forming material" referred to here refers to the average particle size in a mixed state when two or more pore-forming materials having a single peak are mixed.

[0035] In the present technology, the average particle size is the particle size (D-50) at a cumulative frequency of 50% in the particle size distribution measured by a laser diffraction method.

[0036] (5)Other In the production of the porous body according to the present technology, a water-soluble polymeric compound acting as a lubricant may be used.Specific examples of the lubricant include polyethylene glycol, polyethylene oxide, polyethylene glycol diacrylate, polyethylene glycol dioleate, and polyethylene glycol diacetate, and other polyethylene glycol derivatives, and these may be used alone or in combination of two or more.

[0037] Among these, it is particularly preferable to use polyethylene glycol in the present technology. This is because polyethylene glycol has high melt flow and high water solubility. When molding is performed by extrusion molding, the molecular weight of polyethylene glycol is preferably 2,000 to 30,000, more preferably 5,000 to 25,000, and further preferably 15,000 to 25,000.

[0038] In the production of the porous body according to the present technology, the mixing ratio of the resin to the pore-forming material and the water-soluble polymer compound is preferably 6:94 to 40:60 by weight, more preferably 12:88 to 30:70, even more preferably 15:85 to 20:80, and particularly preferably 16:84 to 18:82. If the resin is less than 6 wt.%, the molded body itself will separate during extraction and removal of the water-soluble substance. On the other hand, if the pore-forming material and the water-soluble polymer compound are less than 60 wt.%, the porosity will be too low to form a porous body.

[0039] In addition, the porous body according to the present technology may contain any component such as a filler, a colorant, a flame retardant, a plasticizer, an antistatic agent, an antioxidant, an ultraviolet absorber, or an anti-mold agent, as long as the component does not impair the purpose or effect of the present technology.

[0040] 2. Manufacturing method of porous body The method for producing the porous body according to the present technology is not particularly limited. For example, the porous body can be produced by mixing a resin, a phenolic antioxidant, a carboxylic acid or a salt thereof under a heated state, and then mixing a pore-forming material and a water-soluble polymeric compound under a heated state to form a molded product of the mixture, and then extracting and removing the pore-forming material and the water-soluble polymeric compound from the molded product.

[0041] Specifically, first, the raw material resin, phenolic antioxidant, carboxylic acid, or its salt 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 water-soluble polymeric compounds at a predetermined mixing ratio using a predetermined device to obtain a mixture. Next, the mixture obtained is molded into a molded body of a predetermined shape using an extruder or the like. The molded body obtained is immersed in water or the like at a predetermined temperature to extract and remove the pore-forming materials and the water-soluble polymeric compounds, thereby obtaining a porous body with a large number of fine bubbles.

[0042] For mixing and kneading the resin, pore-forming material and water-soluble polymer compound, kneading devices such as a lab 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 device is required for this kneading, and the kneading speed is not particularly limited. The temperature during kneading is appropriately set depending on the melting point of the resin used. The kneading time depends on the physical properties of the mixture, but it is sufficient if the mixture is sufficiently mixed and kneaded. The kneaded raw material can be molded into a desired shape by extrusion, injection, pressing, rolling, blowing, etc.

[0043] The pore-forming material and the water-soluble polymeric compound are extracted and removed from the molded product molded into a desired shape by immersing them in a solvent such as water for a predetermined time (for example, 24 to 48 hours, although this depends on the shape and thickness of the molded product). 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.

[0044] 3. Physical properties of porous bodies The physical properties of the porous body will be described in detail below.

[0045] (1) Specific gravity In addition, the specific gravity of the porous body according to the present technology is 0.140 g / cm 3 It is preferable that the density is 0.135 g / cm or less. 3 More preferably, it is 0.130 g / cm or less. 3 More preferably, the specific gravity is 0.140 g / cm or less. 3 By providing the following, a porous body that feels good to the touch can be provided.

[0046] The specific gravity of the porous body according to this technology is 0.110 g / cm 3 It is preferable that the content is 0.115 g / cm or more. 3 More preferably, it is 0.120 g / cm or more. 3 More preferably, it is 0.125 / cm or more. 3 It is particularly preferable that the specific gravity is 0.110 g / cm or more. 3 By doing so, it is possible to provide a porous body having excellent durability.

[0047] In this technology, when one type of resin is used, the specific gravity can be calculated using the following formula (1). In the formula (1), the unit of each additive amount is "g" and the unit of each specific gravity is "g / cm 3 "

[0048]

number

[0049] In addition, in the present technology, when two or more types of resins are used, the specific gravity can be calculated by the following formula (2). In the following formula (2), the unit of each added amount is "g" and the unit of each specific gravity is "g / cm 3 In addition, in the following formula (2), the "···" portion is substituted with the "addition amount" or "addition amount / specific gravity" of the third and subsequent resins as necessary, similar to the second resin (i.e., D: resin 2).

[0050]

number

[0051] Furthermore, when the porous body according to the present technology contains other optional components described below, a person skilled in the art can calculate the specific gravity by appropriately setting the above-mentioned formula depending on the physical properties of the other optional components.

[0052] (2) Surface hardness The surface hardness of the porous body according to the present technology is 70 or less, preferably 60 or less, and particularly preferably 55 or less, in terms of Asker F hardness. By setting the Asker F hardness to 70 or less, a porous body with low hardness can be provided. As a result, since hardness is one of the elements that contribute to a good feel, a porous body with a good feel can be provided.

[0053] Moreover, the Asker F hardness of the porous body according to the present technology is preferably not less than 30, more preferably not less than 34, even more preferably not less than 38, and particularly preferably not less than 42. By making the Asker F hardness not less than 30, it is possible to provide a porous body having excellent wear resistance and durability.

[0054] In the present technology, the Asker F hardness can be, for example, a value measured using a Type F durometer (manufactured by Kobunshi Keiki Co., Ltd.) in accordance with JIS 6253-3.

[0055] (3) Tensile properties The tensile strength of the porous body according to the present technology is preferably 0.05 MPa or more, particularly preferably 1 MPa or more. The tensile strength of the porous body according to the present technology is not particularly limited, but is usually 5 MPa or less.

[0056] The tensile elongation of the porous body according to the present technology is preferably 200% or more, more preferably 230% or more, and particularly preferably 250% or more. The tensile elongation of the porous body according to the present technology is not particularly limited, but is usually 800% or less.

[0057] In the present technology, the above-mentioned tensile properties can be values ​​measured in accordance with JIS K 6251, for example.

[0058] (4) Water absorption amount The water absorption amount of the porous body according to the present technology is preferably 10 g or more, and particularly preferably 13 g or more. When the water absorption amount is 10 g or more, it is evident that the porous body has open cells.

[0059] In the present technology, the above-mentioned water absorption amount can be measured, for example, by preparing a sample having a size of t10 mm and 3 cm×3 cm, preparing a solution in which a surfactant with an HLB of 14 is diluted 400 times with pure water as an absorbing liquid, dropping 20 g of the absorbing liquid onto the sample, and measuring the water absorption amount from the weight difference before and after dropping.

[0060] (5) Degree of discoloration (ΔE), yellowing index (YI) The degree of discoloration and yellowing of this technology is NO X The difference in the degree of discoloration (ΔE) or yellowing index (YI) after treatment was measured. X The treatment conditions are, for example, NO 2 The treatment conditions can be 200 ppm for 4 hours and 200 rpm for the stirring speed. The reference sample can be, for example, a standard white sample attached to the measuring device.

[0061] The degree of discoloration (ΔE) is preferably 4 or less, more preferably 3.2 or less, and particularly preferably 1.6 or less. When the ΔE value is 3.2 or less, the color difference is barely noticeable when comparing colors far apart, and is generally considered to be the same color. When the ΔE value is 1.6 or less, the color difference is slightly noticeable when comparing adjacent colors, and is within the range of allowable color difference including errors between general color measuring instruments.

[0062] The yellowing index (YI) value is preferably 4 or less, more preferably 3.5 or less, and particularly preferably 3 or less.

[0063] 4. Applications of porous bodies The porous body according to the present technology can be used for various purposes in various fields by taking advantage of its high quality.Specifically, it can be used for purposes such as functional separation membranes such as filters and filtration membranes, water retention materials, water stop materials, sustained release materials, ink pads using solvent-type inks, components that absorb and retain organic solvents, seepage pad materials, cosmetic tools, medical tools, etc. EXAMPLES

[0064] The present technology will be described in further detail below based on examples. Note that the embodiment described below is merely an example of a typical embodiment of the present technology, and the scope of the present technology is not narrowed by this embodiment.

[0065] <Experimental Example> In this experimental example, citric acid was used as the carboxylic acid, and inhibition of discoloration was examined.

[0066] (1) Raw materials Carboxylic acid: Citric acid Resin 1: Polyolefin resin (MFR: 3.6, Condition: ASTM D1238 190℃) Phenolic antioxidants: 500 ppm by weight or less of the total composition *Not listed in Table 1 due to small quantity. Pore ​​former: NaCl Water-soluble polymer compound: Polyethylene glycol (molecular weight: 15,000 to 25,000)

[0067] (2) Manufacturing of porous bodies The raw materials shown in Table 1 below were weighed and then kneaded in a Labo Plastomill (temperature: 130°C, time: 10 min, rotation speed: 50 rpm). The kneaded mixture was molded in a hand press (temperature: 130°C, time: 5 min, pressure: 40 kN), cooled with water, and immersed in water to allow the pore-forming material and water-soluble polymer compound to dissolve overnight (temperature: about 25°C), and then dried to produce each porous body.

[0068] (3) Evaluation Each of the produced porous bodies was evaluated using the following methods.

[0069] [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 "O", and those that shrank (changed in thickness) were marked with "X".

[0070] [specific gravity] The calculation was performed using the above-mentioned formula (2).

[0071] [Surface hardness] The measurement was performed using a Type F durometer (manufactured by Kobunshi Keiki Co., Ltd.) in accordance with JIS 6253-3.

[0072] [Tensile strength] [Tensile elongation] The tensile strength and tensile elongation were measured in accordance with JIS K 6251.

[0073] [Water absorption] The measurement was performed by the method described in "(4) Water absorption amount" of "3. Physical properties of porous body" above.

[0074] [Discoloration degree (ΔE)] [Yellowing index (YI)] The measurements were made by the method described in "(5) Degree of discoloration (ΔE) and yellowing index (YI)" of "3. Physical properties of the porous body" above.

[0075] (4) Results The results are shown in Table 1 below.

[0076] [Table 1]

[0077] (5) Discussion As shown in Table 1 above, in Examples 1 to 3, NO X Even after the treatment, the degree of discoloration (ΔE) and the yellowing index (YI) were small. Furthermore, all of Examples 1 to 3 were excellent in terms of physical properties such as formability, specific gravity, surface hardness, tensile strength, and tensile elongation.

[0078] On the other hand, in Comparative Example 1, NO X Even after processing, the degree of discoloration (ΔE) and the yellowing index (YI) were both large.

[0079] Therefore, it was found that discoloration was suppressed by containing a resin, a phenolic antioxidant, and a carboxylic acid or a salt thereof in a porous body. It was also found that the obtained porous body had excellent physical properties such as formability, specific gravity, surface hardness, tensile strength, tensile elongation, and water absorption.

Claims

1. Resin and A phenolic antioxidant, A carboxylic acid or a salt thereof; A porous body comprising:

2. The porous body according to claim 1 , wherein the carboxylic acid or salt thereof has a plurality of carboxy groups.

3. The porous body according to claim 1 , wherein the carboxylic acid or the salt thereof is a hydroxy acid having a hydroxy group.

4. 2. The porous body according to claim 1, which is obtained by extracting and removing the pore-forming material from a resin composition containing the resin, the phenol-based antioxidant, the carboxylic acid or a salt thereof, and the pore-forming material.

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