Polyurethane foam and porous body for producing electrode

Abstract

In this invention, cells of polyurethane foam are micronized without using any fluorine compound and volatile silicone.　Polyurethane foam (10) is obtained from a composition in which a polyol and a polyisocyanate are mixed. The polyol includes a polyester polyol. The composition includes a hydrocarbon having 5-50 carbon atoms.

Description

Polyurethane foam and porous material for electrode production

[0001] This disclosure relates to a polyurethane foam and a porous body for electrode fabrication. This application is based on and claims the benefit of priority from Japanese Patent Application No. 2022-153370, filed on September 27, 2022, the entire contents of which are incorporated herein by reference.

[0002] Conventionally, a method using a fluorine compound as a blowing agent to obtain polyurethane foam with fine cells has been known. However, with the enforcement of the Law Concerning the Promotion of Measures to Combat Global Warming, there is a demand for polyurethane foam that does not use fluorine compounds. Patent Document 1 discloses a technology for miniaturizing cells by using a volatile silicone.

[0003] JP 2010-180369 A

[0004] However, the technology of Patent Document 1 adds volatile silicone, which may result in low-molecular-weight siloxanes floating in the air, and therefore alternative technologies are desired. The 19th SVHC (Substances of Very High Concern) list of the European REACH Regulation lists decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and octamethylcyclotetrasiloxane as volatile silicones. Furthermore, the addition of volatile silicones may affect the properties of polyurethane foam, such as its impregnation ability (hydrophilicity), and may not be suitable for some applications.

[0005] The present disclosure has been made in view of the above-mentioned circumstances, and aims to reduce the cell size of a polyurethane foam by reducing the amount of fluorine compounds and volatile silicones, or by using no fluorine compounds or volatile silicones. The present disclosure can be realized in the following aspects.

[0006] [1] A polyurethane foam obtained from a composition obtained by mixing a polyol and a polyisocyanate, wherein the polyol includes a polyester polyol, and the composition includes a hydrocarbon having 5 to 50 carbon atoms.

[0007] According to the present disclosure, the cells of polyurethane foam can be made finer with reduced or no use of fluorine compounds and volatile silicones.

[0008] 1 is a perspective view of a polyurethane foam according to one embodiment. FIG. 2 is a view for explaining a method for measuring an average cell diameter.

[0009] Hereinafter, preferred examples of the present disclosure will be described. [2] The polyurethane foam according to [1], wherein the polyurethane foam has an average cell diameter of 460 μm or less. [3] The polyurethane foam according to [1] or [2], wherein the composition contains more than 0 parts by mass and not more than 2.0 parts by mass of the hydrocarbon per 100 parts by mass of the polyol. [4] A porous body for electrode fabrication using the polyurethane foam according to any one of [1] to [3].

[0010] The present disclosure will be described in detail below. In this specification, when a numerical range is indicated using "-", it is intended to include both the lower limit and the upper limit unless otherwise specified. For example, the expression "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less".

[0011] 1. Polyurethane Foam Polyurethane foam is obtained from a composition (hereinafter also referred to as a "polyurethane resin composition") in which a polyol and a polyisocyanate are mixed. The polyol includes a polyester polyol. The composition also includes a hydrocarbon having 5 to 50 carbon atoms.

[0012] (1) Polyol Polyols include polyester polyols. Polyester polyols are less likely to cause cell coalescence (integration by coalescence) during foaming of polyurethane foam, making it easier to maintain the formed fine cell structure. Polyester polyols are polyester polyols obtained by condensation of one or more compounds having at least two hydroxyl groups with one or more compounds having at least two carboxyl groups, or ring-opening polymers of cyclic esters such as caprolactone and methylvalerolactone. Only one type of polyester polyol may be included, or two or more types may be included.

[0013] The compound having at least two hydroxy groups is not particularly limited. Examples of the compound having at least two hydroxy groups include compounds selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,3- and 1,4-butanediol, tetramethylene glycol, neopentyl glycol, methylpentanediol, butylethylpropanediol, hexamethylene glycol, decamethylene glycol, glycerin, trimethylolpropane, pentaerythritol, and sorbitol. The compound having at least two hydroxy groups may be one type only, or two or more types. As the compound having at least two hydroxy groups, it is preferable to use a diol and a polyhydric alcohol in combination, and it is more preferable to use diethylene glycol and trimethylolpropane in combination.

[0014] The compound having at least two carboxyl groups is not particularly limited. Examples of the compound having at least two carboxyl groups include compounds selected from the group consisting of malonic acid, maleic acid, succinic acid, adipic acid, tartaric acid, pimelic acid, azelaic acid, sebacic acid, oxalic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and hemellitic acid. The compound having at least two carboxyl groups may be one type or two or more types. The compound having at least two carboxyl groups is preferably an aliphatic dibasic acid, more preferably adipic acid.

[0015] The number average molecular weight of the polyester polyol is not particularly limited. The number average molecular weight of the polyester polyol is preferably 500 or more and 10,000 or less, more preferably 1,000 or more and 6,000 or less, and even more preferably 1,500 or more and 4,000 or less. In the present disclosure, the number average molecular weight of the polyol can be measured by gel permeation chromatography (GPC). When the polyol is a commercially available product, the catalog value may be used as the number average molecular weight. The hydroxyl value of the polyester polyol is not particularly limited. The hydroxyl value of the polyester polyol is preferably 40 mgKOH / g or more and 300 mgKOH / g or less, more preferably 45 mgKOH / g or more and 150 mgKOH / g or less, and even more preferably 50 mgKOH / g or more and 80 mgKOH / g or less. The number of functional groups of the polyester polyol is not particularly limited. The number of functional groups of the polyester polyol is preferably 2.0 or more, more preferably 2.1 or more, and even more preferably 2.2 or more. The number of functional groups of the polyester polyol is usually 4.0 or less, and may be 3.0 or less, 2.8 or less, or 2.6 or less. The viscosity of the polyester polyol is not particularly limited. From the viewpoint of cell miniaturization and reactivity, the viscosity of the polyester polyol is preferably 1,000 to 70,000 mPa·s at 25°C, more preferably 5,000 to 40,000 mPa·s at 25°C, or 10,000 to 30,000 mPa·s at 25°C.

[0016] The polyol may include a polyol other than polyester polyol. Examples of polyols other than polyester polyols include polyether polyols, polyether ester polyols, polycarbonate diols, and polyols having a carbon-carbon bond main chain. The various polyols exemplified as polyols other than polyester polyols may be used alone or in combination of two or more.

[0017] The content of the polyester polyol is preferably 75 parts by mass or more and 100 parts by mass or less, more preferably 85 parts by mass or more and 100 parts by mass or less, and even more preferably 95 parts by mass or more and 100 parts by mass or less, based on 100 parts by mass of the total polyol.

[0018] (2) Catalyst The polyurethane resin composition may contain a catalyst. Conventionally known catalysts can be used without any particular limitation. Various catalysts may be used alone or in combination of two or more. As the catalyst, an amine catalyst or a quaternary ammonium salt catalyst can be used. Specific examples of these catalysts are shown below. Tertiary amine catalysts such as triethylenediamine, triethylamine, tripropylamine, triisopropanolamine, tributylamine, trioctylamine, hexadecyldimethylamine, N-methylmorpholine, N-ethylmorpholine, N-octadecylmorpholine, monoethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N,N-dimethylethanolamine, N,N-dimethylaminohexanol, N,N-dimethylaminoethoxyethoxyethanol, and N,N-dimethylaminoethoxyethanol; formate and other salts of triethylenediamine; oxyalkylene adducts of amino groups of primary and secondary amines; azacyclic compounds such as N-N-dialkylpiperazines; various N,N',N'-trialkylaminoalkylhexahydrotriazines; and amine catalysts having an amino group as a functional group such as N,N,N",N"-tetramethyldiethylenetriamine. Further, quaternary ammonium salt catalysts such as tetraalkylammonium halides such as tetramethylammonium chloride, tetraalkylammonium hydroxides such as tetramethylammonium hydroxide salts, and tetraalkylammonium organic acid salts such as tetramethylammonium 2-ethylhexanoate, 2-hydroxypropyltrimethylammonium formate, and 2-hydroxypropyltrimethylammonium 2-ethylhexanoate can also be used. The amount of one or more catalysts selected from the group consisting of amine catalysts and quaternary ammonium salt catalysts in the polyurethane resin composition is not particularly limited. The amount of these catalysts is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1.0 part by mass or more, per 100 parts by mass of polyol, from the viewpoint of sufficiently promoting the polyurethane-forming reaction.On the other hand, from the viewpoint of maintaining the various physical properties of the polyurethane foam and from the viewpoint of production costs, the amount of the one or more catalysts selected from the group consisting of amine catalysts and quaternary ammonium salt catalysts is preferably 0.1 to 3.0 parts by mass, more preferably 0.5 to 2.5 parts by mass, and even more preferably 1.0 to 2.0 parts by mass, per 100 parts by mass of the polyol.

[0019] As the catalyst, a metal catalyst (organometallic catalyst) can be used. Any conventionally known metal catalyst can be used as the metal catalyst without any particular limitation. Examples of metal catalysts that can be used include metal salts of Sn (tin), Pb (lead), Bi (bismuth), Ni (nickel), Co (cobalt), Fe (iron), Zr (zirconium), Cu (copper), Zn (zinc), and the like, and organic acid metal salts. More specifically, the following metal catalysts can be used. Sn catalysts: tin(II) octoate (tin 2-ethylhexanoate, stannous dioctoate), tin(II) acetate, stannous diacetate, tin(II) octoate, tin stannous dioleate, tin(II) neodecanoate, stannous dilaurate, dibutyltin oxide, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, dioctyltin dilaurate, dibutyltin dimaleate, dioctyltin diacetate, etc. Pb catalysts: lead octoate, lead naphthenate, etc. Bi catalysts: bismuth octoate, bismuth naphthenate, bismuth neodecanoate, bismuth rosinate, etc. Fe catalysts: iron acetylacetonate, etc. Zr catalysts: zirconium acetylacetonate, etc. Ni catalysts: nickel acetylacetonate, nickel octoate, nickel naphthenate, etc. Co catalyst: cobalt acetylacetonate, cobalt octylate, cobalt naphthenate, etc.

[0020] The amount of the metal catalyst in the polyurethane resin composition is not particularly limited. From the viewpoint of sufficiently promoting the polyurethane-forming reaction, the amount of the metal catalyst is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and even more preferably 0.06 parts by mass or more, per 100 parts by mass of polyol. On the other hand, from the viewpoint of maintaining the various physical properties of the polyurethane foam and from the viewpoint of production costs, the amount is preferably 1.0 part by mass or less, more preferably 0.5 parts by mass or less, and even more preferably 0.1 parts by mass or less. From these viewpoints, the amount of the metal catalyst is preferably 0.01 parts by mass or more and 1.0 parts by mass or less, more preferably 0.03 parts by mass or more and 0.5 parts by mass or less, and even more preferably 0.06 parts by mass or more and 0.1 parts by mass or less, per 100 parts by mass of polyol.

[0021] (3) Foam Stabilizer The polyurethane resin composition may contain a foam stabilizer. The foam stabilizer is not particularly limited. Specific examples of the foam stabilizer include silicone compounds such as organopolysiloxane, organopolysiloxane-polyoxyalkylene copolymer, polyalkenylsiloxane having a polyoxyalkylene side chain, and silicone-grease copolymer, polyether siloxane, and phenolic compounds. These foam stabilizers may be used alone or in combination of two or more. The amount of the foam stabilizer is not particularly limited. The amount of the foam stabilizer is preferably 0.03 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of the polyol.

[0022] (4) Surfactant The polyurethane resin composition may contain a surfactant. The surfactant is not particularly limited. Examples of surfactants include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. These surfactants can be used alone or in combination. Among these, nonionic surfactants are preferred. Examples of nonionic surfactants include ether-type surfactants such as polyoxyalkylene alkyl ethers and polyoxyethylene alkylphenyl ethers, ester-ether-type surfactants such as polyoxyethylene oleate esters, alkyl glycosides such as polyoxyethylene alkyl esters, alkanolamide-type surfactants such as polyoxyethylene oleic acid amides, amine oxides such as dodecyldimethylamine oxide, alkylamine-type surfactants such as polyoxyethylene alkylamines, and higher alcohols such as cetanol. The amount of surfactant is not particularly limited. The amount of surfactant is preferably 0.03 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of polyol.

[0023] (5) Foaming Agent The polyurethane resin composition may contain a foaming agent. The foaming agent is not particularly limited. Suitable foaming agents include water, pentane, cyclopentane, hexane, cyclohexane, dichloromethane, and carbon dioxide gas. When the foaming agent is water, the amount added is determined within a range that allows the polyurethane foam to have a desired density and a good foaming state, and is usually preferably 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of polyol. When the polyurethane foam is used as a porous body for electrode fabrication, the amount of water added is preferably 6 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less per 100 parts by mass of polyol.

[0024] (6) Polyisocyanate The polyisocyanate is not particularly limited. At least one selected from the group consisting of aromatic isocyanates, alicyclic isocyanates, and aliphatic isocyanates is preferably used as the polyisocyanate. One or more aliphatic isocyanates and one or more aromatic isocyanates may be used in combination. The polyisocyanate may be a bifunctional polyisocyanate having two isocyanate groups per molecule, or a trifunctional or higher polyisocyanate having three or more isocyanate groups per molecule, and may be used alone or in combination. For example, bifunctional polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, xylylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, and 3,3'-dimethoxy-4,4'-biphenylene diisocyanate. Examples of the isocyanate include aromatic isocyanates such as phenylene diisocyanate, alicyclic isocyanates such as cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and methylcyclohexane diisocyanate, and aliphatic isocyanates such as butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, and lysine isocyanate. Examples of tri- or higher functional polyisocyanates include 1-methylbenzene-2,4,6-triisocyanate, 1,3,5-trimethylbenzene-2,4,6-triisocyanate, biphenyl-2,4,4'-triisocyanate, diphenylmethane-2,4,4'-triisocyanate, methyldiphenylmethane-4,6,4'-triisocyanate, 4,4'-dimethyldiphenylmethane-2,2',5,5'tetraisocyanate, triphenylmethane-4,4',4"-triisocyanate, and polymeric MDI.Additionally, urethane prepolymers, carbodiimide-modified isocyanates, isocyanurate-modified isocyanates, and biuret-modified isocyanates can also be used.

[0025] The mixing ratio of polyisocyanate and polyol is not particularly limited. The isocyanate index is preferably 80 to 140, more preferably 90 to 130, and even more preferably 100 to 120. The isocyanate index (INDEX) is the value obtained by multiplying the number of moles of isocyanate groups per mole of active hydrogen groups contained in a polyurethane resin composition by 100, and is calculated by [(isocyanate equivalent in the composition / active hydrogen equivalent in the composition) × 100].

[0026] (7) Hydrocarbons with 5 to 50 Carbon atoms The hydrocarbons with 5 to 50 carbon atoms are not particularly limited as long as the number of carbon atoms is within this range. The hydrocarbons may be either saturated hydrocarbons or unsaturated hydrocarbons. The hydrocarbons may be either hydrocarbons having a branched structure or cyclic hydrocarbons. Suitable examples of hydrocarbons include n-paraffins with 5 to 50 carbon atoms and isoparaffins with 5 to 50 carbon atoms. The hydrocarbons with 5 to 50 carbon atoms may be used alone or in combination of two or more.

[0027] (7.1) n-Paraffins Having 5 to 50 Carbon Atoms Examples of n-paraffins having 5 to 50 carbon atoms include at least one selected from the group consisting of n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, and n-eicosane.

[0028] (7.2) Isoparaffins having 5 to 50 carbon atoms Examples of isoparaffins having 5 to 50 carbon atoms include at least one selected from the group consisting of isodecane, isododecane, 7-methyldecane, and 7-n-hexylitridecane.

[0029] (7.3) Amount of Hydrocarbon Having 5 to 50 Carbon Atoms The amount of hydrocarbon having 5 to 50 carbon atoms in the polyurethane resin composition is not particularly limited, as long as it is present. The amount of hydrocarbon is greater than 0 parts by mass relative to 100 parts by mass of polyol, and from the viewpoint of miniaturizing the cells of the polyurethane foam, it is preferably 0.1 parts by mass or more, more preferably 0.4 parts by mass or more, and even more preferably 0.6 parts by mass or more. On the other hand, from the viewpoint of ease of mixing of the polyurethane resin composition and suppressing voids, it is preferably 2.0 parts by mass or less, more preferably 1.8 parts by mass or less, even more preferably 1.6 parts by mass or less, and particularly preferably 1.3 parts by mass or less. From these viewpoints, the amount of hydrocarbon is preferably greater than 0 parts by mass and 2.0 parts by mass or less, more preferably 0.1 parts by mass or more and 1.8 parts by mass or less, more preferably 0.4 parts by mass or more and 1.6 parts by mass or less, and particularly preferably 0.6 parts by mass or more and 1.3 parts by mass or less, relative to 100 parts by mass of polyol. When two or more hydrocarbons are used, the above blending amount means the total amount of all hydrocarbons.

[0030] (8) Other Additives The polyurethane resin composition may contain other additives as appropriate, such as crosslinking agents, plasticizers, flame retardants, fillers, antioxidants, ultraviolet absorbers, defoamers, compatibilizers, colorants, stabilizers, antibacterial agents, antifungal agents, deodorizers, deodorizers, fragrances, perfumes, etc. Examples of crosslinking agents include short-chain diol crosslinking agents such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, glycerin, and trimethylolpropane.

[0031] (9) Presumed Reasons for the Refinement of Cells in Polyurethane Foam The following explains the presumed reasons for the refining of cells in polyurethane foam. It is believed that the inclusion of hydrocarbons having 5 to 50 carbon atoms in the polyurethane resin composition causes the hydrocarbons to vaporize during foam molding of the polyurethane foam, resulting in the formation of a fine cell structure. Furthermore, because the polyol contains a polyester polyol, the viscosity of the polyurethane resin composition is ensured, making it difficult for bubbles to coalesce once formed, and thus making it easier to maintain a fine, uniform cell structure. It is believed that this is how the cells in the polyurethane foam are refined.

[0032] (10) Physical Properties of Polyurethane Foam The physical properties of the polyurethane foam can be appropriately set depending on the application, etc. The polyurethane foam is preferably a flexible polyurethane foam. The polyurethane foam preferably has the following physical properties: (10.1) Apparent Density The apparent density (JIS K7222:2005) is 8 kg / m ３ -150 kg / m ３ is preferred, and 10 kg / m ３ -100 kg / m ３ More preferably, 25 kg / m ３ -45 kg / m ３is more preferable. (10.2) 25% ILD Hardness The 25% ILD hardness (JIS K6400-2D method: 2012) is preferably 10N-600N, more preferably 50N-400N, and even more preferably 100N-200N. (10.3) Tensile Strength, Elongation The tensile strength (JIS K6400-5: 2012) is preferably 50 kPa or more, more preferably 100 kPa or more, and even more preferably 150 kPa or more. The upper limit of the tensile strength is not particularly limited, and is, for example, 500 kPa or less. The elongation (JIS K6400-5: 2012) is preferably 100% or more, more preferably 150% or more, and even more preferably 200% or more. The upper limit of the elongation is not particularly limited, and is, for example, 500% or less. (10.4) Compression Residual Strain The compression residual strain (JIS K6400-4 Method A: 2004) is preferably 20% or less, more preferably 15% or less. The lower limit of the compression residual strain is not particularly limited, and is, for example, 0% or more. (10.5) Average Cell Diameter The average cell diameter is preferably 460 μm or less, more preferably 450 μm or less, and even more preferably 445 μm or less. The lower limit of the average cell diameter is not particularly limited, and may be, for example, 100 μm or more, 200 μm or more, 300 μm or more, or 350 μm or more. The average cell diameter can be measured, for example, as follows: A cross section of the polyurethane foam perpendicular to the foaming direction (foam height direction) is magnified (50 times) using a microscope (Keyence VHX-8000, lens VH-ZST) and an image is obtained. In the acquired image, a rectangular field of view of 4.92 mm x 6.56 mm is observed. Multiple parallel lines are drawn in the field of view at intervals of 610 μm. The diameter of the cells located on the lines is measured. The cell diameter is taken as the maximum diameter of the cell. This is repeated for 100 cells. If there are fewer than 100 cells in one field of view, multiple fields of view are observed until the number of cells reaches 100. The average of the maximum diameters of the 100 cells is calculated and taken as the average cell diameter. In the case of continuously produced slab foam, the measurement can be performed as follows. This will be explained with reference to Figures 1 and 2. In Figures 1 and 2, the X-axis direction is the production flow direction (the direction in which the belt conveyor described below moves), the Y-axis direction is the production width direction, and the Z-axis direction is the direction perpendicular to the X-axis and Y-axis directions.A cross section (II-II cross section) perpendicular to the foaming direction (foam height direction, the direction of the white arrow in Figure 1) of polyurethane foam 10 is magnified (50 times) using a microscope (Keyence VHX-8000, lens VH-ZST) and an image is obtained. In the obtained image, a rectangular field of view of 4.92 mm x 6.56 mm is observed. Multiple parallel lines are drawn in the field of view at intervals of 610 μm. The diameter of cells located on the lines is measured. The cell diameter is the maximum diameter of the cell. In this case, the maximum diameter of the cell is the maximum dimension in the production flow direction (X-axis direction). This is repeated for 100 cells. If there are fewer than 100 cells in one field of view, multiple fields of view are observed until the number of cells reaches 100. The average of the maximum diameters of the 100 cells is calculated and used as the average cell diameter. (10.6) Water Absorption Rate The water absorption rate of polyurethane foam is preferably 90 minutes or less, more preferably 60 minutes or less, and even more preferably 40 minutes or less. The lower limit of the water absorption rate of polyurethane foam is not particularly limited, and is, for example, 5 seconds or more. The water absorption rate of polyurethane foam can be measured, for example, as follows: A polyurethane foam sample is obtained. One drop of water (approximately 0.05 mL) is gently dropped on the surface of the polyurethane foam, and the time (seconds) until the water droplet completely penetrates the polyurethane foam is measured. The penetration of the water droplet is determined by whether or not the specular reflection of the water droplet disappears. The time (minutes) until the water droplet completely penetrates the polyurethane foam is measured at three different positions on one sample, and the average of these is calculated to determine the water absorption rate.

[0033] 2. Production of Polyurethane Foam Polyurethane foam can be produced by a known foaming method in which a polyurethane resin composition is stirred and mixed to react a polyol and a polyisocyanate. Foaming methods include slab foaming and mold foaming, and either molding method may be used. Slab foaming is a method in which a mixed polyurethane resin composition is discharged onto a belt conveyor and foamed at atmospheric pressure and room temperature. On the other hand, mold foaming is a method in which a mixed polyurethane resin composition is filled into a mold (forming die) and foamed within the mold.

[0034] 3. Porous Body for Electrode Fabrication The use of polyurethane foam is not particularly limited. The polyurethane foam of this embodiment can be suitably used as a porous body for electrode fabrication. In a porous body for electrode fabrication, the fineness of the cells and the uniformity of the cell diameter can affect the performance of the electrode. The polyurethane foam of this embodiment has finer cells, which can contribute to improving the performance of the electrode. Furthermore, a porous body for electrode fabrication using polyurethane foam is more likely to have a high porosity (void fraction) than a porous body for electrode fabrication using a nonwoven fabric. The porous body for electrode fabrication of this embodiment is useful as an electrode material for batteries such as nickel-metal hydride batteries and nickel-cadmium batteries.

[0035] An electrode can be produced using polyurethane foam, for example, as follows: The surface of the polyurethane foam skeleton is treated to be conductive. Examples of conductive treatments include electroless plating and applying a conductive binder mixed solution to the surface of the polyurethane foam and drying it. The conductive polyurethane foam is used as the cathode and electroplated with metal. After forming a metal plating layer on the surface of the polyurethane foam, a further heat treatment is performed as necessary to remove the polyurethane foam. This completes the production of a porous metal electrode.

[0036] The porous body for electrode fabrication is preferably a polyurethane foam from which the cell membrane has been partially or entirely removed. In the case of a polyurethane foam from which the cell membrane has been partially or entirely removed, a metal layer can be suitably formed even inside the polyurethane foam. The cell membrane can be removed by any known method, such as a method involving blending polyurethane foam, or an alkali treatment or explosion treatment method performed after polyurethane foam formation.

[0037] 1. Production of Polyurethane Foams Polyurethane resin compositions were prepared according to the proportions shown in Table 1, and polyurethane foams of the Examples and Comparative Examples were produced by slab foaming. Details of each raw material are as follows: Polyol: polyester polyol obtained by condensing adipic acid with diethylene glycol and trimethylolpropane, functionality 2.6, number average molecular weight 2400, hydroxyl value 60.5 mgKOH / g, DG173R, manufactured by COIM Catalyst-1: amine catalyst Catalyst-2: metal catalyst, tin (II) octoate Foam stabilizer: silicone-based foam stabilizer Surfactant: nonionic surfactant Foaming agent: water Isocyanate: tolylene diisocyanate (a mixture of 65 mass% of 2,4-tolylene diisocyanate and 35 mass% of 2,6-tolylene diisocyanate) Fluorine compound: perfluoro compound, PF5060, manufactured by 3M Volatile silicone: decamethylcyclopentasiloxane, SH245, manufactured by Dow Corning Toray Hydrocarbon: n-dodecane, C １２ H ２６

[0038]

[0039] 2. Evaluation Methods (1) Apparent Density The apparent density was measured according to JIS K7222:2005. (2) Hardness (25% ILD Hardness) The hardness was measured according to JIS K6400-2 Method D:2012. (3) Tensile Strength and Elongation The tensile strength and elongation were measured according to JIS K6400-5:2012. (4) Compression Set (Compression Set) The compression set was measured according to JIS K6400-4 Method A:2004. (5) Average Cell Diameter The average cell diameter was measured according to the method described in the embodiment "For continuously produced slab foam." (6) Water Absorption Rate The water absorption rate was measured according to the method described in the embodiment.

[0040] 3. Results The results are also shown in Table 1. Comparative Example 1 shows the results for a flexible polyurethane foam without any additives (fluorine compounds, volatile silicones, or hydrocarbons). Comparative Examples 2 and 3 show the results for a flexible polyurethane foam with an added fluorine compound. Comparative Examples 4 and 5 show the results for a flexible polyurethane foam with an added volatile silicone. Note that decamethylcyclopentasiloxane, used as the volatile silicone, is included in the EU REACH Regulation 19th SVHC (Substances of Very High Concern) list.

[0041] Example 1 shows the results when 1.1 parts by mass of hydrocarbon (n-dodecane) was added. Example 2 shows the results when 1.4 parts by mass of n-dodecane was added. Examples 1 and 2 had smaller average cell diameters than Comparative Example 1. This suggests that adding a hydrocarbon can make the cells of the polyurethane foam finer.

[0042] It was found that Example 1, even without the addition of a fluorine compound, had an average cell diameter equivalent to those of Comparative Examples 2 and 3. It was suggested that hydrocarbons can be an alternative to fluorine compounds in miniaturizing the cells of polyurethane foam. It was found that Example 1, even without the addition of a volatile silicone, had an average cell diameter equivalent to those of Comparative Examples 4 and 5. It was suggested that hydrocarbons can be an alternative to fluorine compounds in miniaturizing the cells of polyurethane foam. Furthermore, Examples 1 and 2 had better water absorption than Comparative Examples 4 and 5. It was suggested that Examples 1 and 2 are suitable as porous bodies for electrode fabrication.

[0043] According to the above examples, the cells of the polyurethane foam could be made finer without using a fluorine compound or a volatile silicone.

[0044] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the present disclosure.

Claims

1. A polyol, A polyisocyanate, A polyurethane foam obtained from a composition comprising: The polyol includes a polyester polyol, The composition includes a hydrocarbon having 5 to 50 carbon atoms, A polyurethane foam that satisfies at least one of the following (a) and (b): (a) The polyurethane foam has a cell membrane partially or entirely removed. (b) the composition includes a hydrocarbon having 9 to 50 carbon atoms;

2. 2. The polyurethane foam according to claim 1, wherein the hydrocarbon is at least one selected from the group consisting of n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, n-eicosane, isodecane, isododecane, 7-methyldecane, and 7-n-hexylitridecane.

3. A porous body for electrode production using polyurethane foam, The polyurethane foam is A polyol, A polyisocyanate, A polyurethane foam obtained from a composition comprising: The polyol includes a polyester polyol, The composition includes a hydrocarbon having 5 to 50 carbon atoms.