Porous body

Abstract

To provide a porous body resistant to discoloration.SOLUTION: The present invention provides a porous body comprising a resin, a phenolic antioxidant, and a trivalent phosphorus antioxidant in an amount of 100 wt.ppm or more. The porous body may be obtained by removing a pore-forming material through extraction from a resin composition comprising the resin, the phenolic antioxidant, the phosphorus antioxidant, and the pore-forming material.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Porous bodies have been produced using resins. Conventional methods for producing porous bodies include, for example, a wet or dry method in which a molded body is formed by mixing or dispersing a water-soluble pore-forming material, and then the pore-forming material is extracted and removed to produce a porous body.

[0003] Here, phenolic antioxidants and the like are sometimes used to prevent oxidation, but it is known that the antioxidants undergo structural changes over time and react with nitrogen compounds generated from the air, etc., leading to discoloration of the resin (e.g., yellowing, pinking, etc.).

[0004] In response to this, for example, Patent Document 1 proposes a primer composition for use in forming a coating film by applying a primer and a topcoat paint to a polypropylene substrate, which contains a polyolefin resin or a chlorinated polyolefin resin and an epoxy resin as resin components, and uses a phosphorus-based antioxidant and a mono-hindered phenol-based antioxidant in combination.

[0005] Furthermore, for example, Patent Document 2 proposes a polyolefin resin composition containing 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 a specific 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 the 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 the 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 the polyolefin. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 07-118568 [Patent Document 2] Japanese Patent Application Publication No. 2018-203864 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 diversified, 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, 100 ppm by weight or more of a trivalent phosphorus antioxidant; The present invention provides a porous body comprising: The phosphorus-based antioxidant may include a phosphorus-based antioxidant having a molecular weight of 640 or less. The porous body according to the present technology has a specific gravity of 0.35 g / cm 3 It may be the following: 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 resin, the phenol-based antioxidant, the phosphorus-based antioxidant, and a pore-forming material. DETAILED DESCRIPTION OF THE INVENTION

[0010] A preferred embodiment for carrying out 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 as being narrow.

[0011] 1. Porous materials The porous body according to the present technology contains a resin, a phenolic antioxidant, and 100 ppm by weight or more of a trivalent phosphorus-based antioxidant. The porous body containing these components is inhibited from discoloring. Note that the term "discoloration" as used herein is a broad concept that includes not only yellowing and pinking, but also color changes measured by the difference in values ​​measured with a color difference meter. Each component will be described in detail below.

[0012] (1) Resin The resins that can be used in this technology include thermoplastic resins and thermosetting resins, but 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] In the present technology, it is particularly preferable to use polyolefin resin among these. 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 copolymerizable with the olefin-based monomers, and these can be used alone or in combination of two or more.

[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) measured under the conditions of JIS K7210-1:2014 at 190°C and a load of 2.16 kg of 1.0 g / 10 min or more and 5.0 g / 10 min or less are particularly preferred, and polyolefin resins having an MFR of 2.0 g / 10 min or more and 4.0 g / 10 min or less are more preferred.

[0018] (2) Phenolic antioxidants Examples of phenolic 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][ethylenebis(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, and 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 total composition is, for example, 800 ppm by weight or less, preferably 700 ppm by weight or less, more preferably 600 ppm by weight or less, and particularly preferably 500 ppm by weight or less. By making the content in the total composition 800 ppm by weight or less, oxidative degradation is suppressed and durability is improved. The lower limit of the content in the total composition is not particularly limited, but it is preferably contained within a range that allows the antioxidant function to be fulfilled, for example, 50 ppm by weight or more.

[0020] (3) Trivalent phosphorus antioxidants With this technology, the produced porous body contains 100 ppm by weight or more of a trivalent phosphorus-based antioxidant, which suppresses structural changes in the phenolic antioxidant over time and thereby reduces discoloration caused by the phenolic antioxidant.

[0021] The lower limit of the content of the trivalent phosphorus-based antioxidant in the porous body is 100 ppm by weight or more, as described above, but is preferably 250 ppm by weight or more, more preferably 500 ppm by weight or more, even more preferably 750 ppm by weight or more, and particularly preferably 1000 ppm by weight or more. The upper limit of the content of the trivalent phosphorus-based antioxidant in the porous body is not particularly limited, but from the viewpoint of cost, it is, for example, 10,000 ppm by weight or less.

[0022] In this specification, the term "trivalent phosphorus-based antioxidant" refers to a trivalent phosphorus compound having at least one trivalent phosphorus. Specific examples include compounds represented by the following general formula (1):

[0023] [ka]

[0024] where R 1 ~R 3 are each independently 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 carboxylic acid ester group, a sulfonic acid group, a formyl group, a nitro group, a cyano group, a silyl group, groups combining these (e.g., hydroxy acid, groups in which a portion of the above-mentioned substituents is substituted with other substituents, etc.), and groups bonded via a divalent linking group such as -O-, -NR-, -S-, -C(=O)-, -C(=O)O-, and -C(=O)NH-, but the present technology is not limited to these.

[0025] In addition, R 1 ~R 3 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.

[0026] In addition, in the present technology, for example, as shown in the following general formula (2), a divalent substituent may be further introduced.

[0027] [ka]

[0028] where R 4 ~R 6 is the above R 1 ~R 3 X is a divalent substituent, and examples thereof include those having a structure in which one hydrogen atom has been further removed from the above-mentioned monovalent substituent (for example, a divalent hydrocarbon group), an ether group (an oxygen atom bonded to an ether bond), other divalent oxygen atoms, an amide group, and a sulfur atom, but are not limited to these in the present technology.

[0029] When the trivalent phosphorus-based antioxidant has two phosphorus atoms, for example, a compound represented by the following general formula (3) can be mentioned.

[0030] [ka]

[0031] where R 7 and R 8 is the above R 1 ~R 3 is the same as:

[0032] In addition, when the trivalent phosphorus-based antioxidant has two phosphorus atoms, for example, a compound represented by the following general formula (4) can be mentioned.

[0033] [ka]

[0034] where R 9 ~R 12 is the above R 1 ~R 3 is the same as:

[0035] In the present technology, it is particularly preferable that the trivalent phosphorus-based antioxidant contains a trivalent phosphorus-based antioxidant having a molecular weight of not more than 640. Examples of trivalent phosphorus-based antioxidants having a molecular weight of not more than 640 include compounds represented by the following chemical formula (I) and chemical formula (II).

[0036] [ka]

[0037] [ka]

[0038] In this technology, when the trivalent phosphorus-based antioxidant is a compound represented by the above chemical formula (I) or (II), the lower limit of the amount added during production 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 resin components. By adding the compound represented by the above chemical formula (I) or (II) at 0.01 wt.% or more based on the total amount of resin components, discoloration can be further suppressed. Furthermore, the upper limit of the amount added during production is not particularly limited, but can be, for example, 1 wt.% or less from a cost perspective.

[0039] (4) Pore-forming material The pore-forming material that can be used in the present technology is preferably a substance that is soluble in water, alcohol, or an aqueous alcohol solution (preferably water) and that is 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, and the like), and these can be used alone or in combination of two or more.

[0040] 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.

[0041] The average particle size of the pore-forming material is preferably 10 μm or more and 200 μm or less, and particularly preferably 50 μm or more and 190 μm or less. By setting the average particle size of the pore-forming material to 10 μm or more, the pore size of the porous body can be controlled to a certain level or more, and a porous body with excellent formability and abrasion 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 pore size of the porous body can be controlled to a certain level or less. Note that, when two or more pore-forming materials having a single peak are mixed, the "average particle size of the pore-forming material" referred to here refers to the average particle size in the mixed state.

[0042] 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 laser diffraction method.

[0043] (5) Other The porous body according to the present technology may be produced using a water-soluble polymer compound that acts as a lubricant. 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.

[0044] Among these, polyethylene glycol is particularly preferably used in the present technology. This is because polyethylene glycol 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.

[0045] In the production of a 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.

[0046] Furthermore, 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 purpose and effect of the present technology are not impaired.

[0047] 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, and a phosphorus-based antioxidant under heated conditions, and then further mixing a pore-forming material and a water-soluble polymer compound under heated conditions to form a molded body of the mixture, and then extracting and removing the pore-forming material and the water-soluble polymer compound from the molded body.

[0048] Specifically, the raw material resin, phenolic antioxidant, and phosphorus-based antioxidant are first mixed and kneaded in a predetermined ratio using a predetermined device, and then this mixture is mixed and kneaded with one or more pore-forming materials and a water-soluble polymer compound in a predetermined 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 water or the like at a predetermined temperature to extract and remove the pore-forming materials and the water-soluble polymer compound, resulting in a porous body with many fine bubbles.

[0049] To mix and knead the resin, 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 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 as long as the mixture is thoroughly mixed and kneaded. The kneaded raw materials can be molded into the desired shape by extrusion, injection, pressing, rolling, blowing, etc.

[0050] 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.

[0051] 3. Physical properties of porous materials The physical properties of the porous body will be described in detail below.

[0052] (1) Specific gravity The specific gravity of the porous body according to the present technology is 0.35 g / cm 3 Preferably, it is 0.30 g / cm or less. 3 More preferably, it is 0.25 g / cm or less. 3 More preferably, it is 0.20 g / cm or less. 3 Even more preferably, it is 0.15 g / cm or less. 3 It is particularly preferable that the specific gravity is 0.35 g / cm or less. 3 By making the following, a porous body having a good feel can be provided.

[0053] The specific gravity of the porous body according to this technology is 0.110 g / cm3 It is preferable that the concentration 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, a porous body having excellent durability can be provided.

[0054] 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 added amount is "g" and the unit of each specific gravity is "g / cm 3 "

[0055]

number

[0056] In addition, in the present technology, when two or more types of resins are used, the specific gravity can be calculated using the following formula (2): In the 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 "···" part is to be substituted with the "addition amount" or "addition amount / specific gravity" of the third and subsequent resins as needed, similar to the second type of resin (i.e., D: Resin 2).

[0057]

number

[0058] 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.

[0059] (2) Surface hardness The surface hardness of the porous body according to the present technology is 100 or less, preferably 90 or less, and particularly preferably 80 or less, in terms of Asker F hardness. By setting the Asker F hardness to 100 or less, a porous body with low hardness can be provided. As a result, since hardness is one of the factors that contribute to a good feel, a porous body with a good feel can be provided.

[0060] Furthermore, the Asker F hardness of the porous body according to the present technology is preferably not less than 30, more preferably not less than 35, even more preferably not less than 40, and particularly preferably not less than 45. By making the Asker F hardness not less than 30, it is possible to provide a porous body having excellent durability.

[0061] In the present technology, the Asker F hardness can be a value measured using a Type F durometer (manufactured by Kobunshi Keiki Co., Ltd.) in accordance with JIS 6253-3, for example.

[0062] (3) Tensile properties The tensile strength of the porous body according to the present technology is preferably 0.05 MPa or more, more preferably 1 MPa or more, and particularly preferably 1.25 MPa. The tensile strength of the porous body according to the present technology is not particularly limited, but is usually 5 MPa or less.

[0063] 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.

[0064] In the present technology, the above-mentioned tensile properties can be values ​​measured in accordance with JIS K 6251, for example.

[0065] (4) Water absorption amount The water absorption capacity of the porous body according to the present technology is preferably 10 g or more, and particularly preferably 13 g or more. A water absorption capacity of 10 g or more indicates that the porous body has open cells.

[0066] In the present technology, the above-mentioned water absorption amount can be measured, for example, by using a sample size of 10 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 absorption liquid, dropping 20 g of the absorption liquid onto the sample, and measuring the water absorption amount from the weight difference before and after dropping.

[0067] (5) Degree of discoloration (ΔE), yellowing index (YI) The degree of discoloration and yellowing of this technology is NO compared to the reference sample. X The difference in the degree of discoloration (ΔE) or yellowing index (YI) after treatment was measured. X The treatment conditions can be, for example, NO2 gas used, treatment conditions can be 200 ppm for 4 hours, and stirring speed can be 200 rpm. The reference sample can be, for example, a standard white sample attached to the measuring device.

[0068] The degree of discoloration (ΔE) value 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 side by side, 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 colors side by side, and is within the range of acceptable color difference, including errors between general color measuring instruments.

[0069] The yellowing index (YI) value is preferably 4 or less, more preferably 3.5 or less, and particularly preferably 3 or less.

[0070] 4. Applications of porous materials Taking advantage of its high quality, the porous body according to the present technology can be used for a wide variety of applications in a wide 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 that absorb and retain organic solvents, exudation pad materials, cosmetic tools, and medical tools. [Example]

[0071] The present technology will be described in further detail below based on examples. It should be noted that the embodiment described below is an example of a typical embodiment of the present technology, and the scope of the present technology should not be interpreted as being narrow.

[0072] <Experimental Example> In this experimental example, the inhibition of discoloration was investigated using the above general formula (I) and general formula (II).

[0073] (1) Raw materials Resin 1: Polyolefin resin (MFR: 3.6 g / 10 min, conditions: JIS K7210-1:2014, 190°C, load 2.16 kg) Phenolic antioxidants: 500 ppm by weight or less of the total composition *Not listed in Table 1 due to small quantity. Phosphorus-based antioxidant 1: a compound represented by the above general formula (I) Phosphorus-based antioxidant 2: a compound represented by the above general formula (II) Pore ​​former: NaCl (average particle size 185.5 μm) Water-soluble polymer compound: polyethylene glycol (molecular weight: 20,000)

[0074] (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 elute overnight (temperature: about 25°C), followed by drying to produce each porous body.

[0075] (3) Evaluation Each of the produced porous bodies was evaluated using the following methods.

[0076] [Formability] After the elution of the pore-forming material and the water-soluble polymer compound, samples that did not shrink (no change in thickness) were marked with "O", and samples that shrunk (changed in thickness) were marked with "X".

[0077] [specific gravity] The calculation was carried out using the above-mentioned formula (2).

[0078] [Surface hardness] Measurement was carried out in accordance with JIS 6253-3 using a Type F durometer (manufactured by Kobunshi Keiki Co., Ltd.).

[0079] [Tensile strength] [Tensile elongation] The tensile strength and tensile elongation were measured in accordance with JIS K 6251.

[0080] [Water absorption] The measurement was carried out by the method described in "(4) Water absorption" of "3. Physical properties of porous bodies" above.

[0081] [Discoloration degree (ΔE)] [Yellowing index (YI)] Measurements were made using the methods described in "(5) Degree of discoloration (ΔE) and yellowing index (YI)" of "3. Physical properties of porous body" above.

[0082] (4) Results The results are shown in Table 1 below.

[0083] [Table 1]

[0084] (5) Discussion As shown in Table 1 above, Examples 1 to 7 all have NO X Even after the treatment, the degree of discoloration (ΔE) and the yellowing index (YI) were small. Furthermore, it was found that 1820 ppm by weight of the phosphorus-based antioxidant remained in Example 3, and 3320 ppm by weight of the phosphorus-based antioxidant remained in Example 7. Furthermore, all of Examples 1 to 7 were excellent in terms of physical properties such as formability, specific gravity, surface hardness, tensile strength, tensile elongation, and water absorption.

[0085] On the other hand, in Comparative Example 1, compared with Examples 1 to 7, NO X After the treatment, the degree of discoloration (ΔE) and the yellowing index (YI) were both large.

[0086] Therefore, it was suggested that discoloration of the porous body can be suppressed by including a resin, a phenolic antioxidant, and 100 ppm by weight or more of a trivalent phosphorus antioxidant.Furthermore, it was found that the obtained porous body also has excellent physical properties such as formability, specific gravity, surface hardness, tensile strength, tensile elongation, and water absorption.

Claims

1. Resin and a phenolic antioxidant, 100 ppm by weight or more of a trivalent phosphorus-based antioxidant; A porous body comprising:

2. The porous body according to claim 1 , wherein the phosphorus-based antioxidant comprises a phosphorus-based antioxidant having a molecular weight of 640 or less.

3. Specific gravity is 0.35 g / cm ３ The porous body according to claim 1, wherein:

4. 2. The porous body according to claim 1, obtained by extracting and removing the pore-forming material from a resin composition containing the resin, the phenol-based antioxidant, the phosphorus-based antioxidant, and the pore-forming material.

Images