Method for manufacturing polyurethane foam and polyurethane foam

Abstract

To suppress discoloration of a polyurethane foam blended with a polyolefin-based resin.SOLUTION: A polyurethane foam is obtained from a composition obtained by mixing polyol, polyisocyanate and polyolefin-based resin powder. The composition contains a hydroxy carboxylic acid.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to polyurethane foam.

Background Art

[0002] In the production of lightweight flexible polyurethane foam, in order to increase the expansion ratio, it is necessary to increase the amount of water added as a blowing agent. However, when the amount of water added increases, there is a problem that the amount of heat generated by the reaction between water and isocyanate increases. Therefore, in order to solve this problem, Patent Documents 1 and 2 disclose a technique of using a polymer to absorb heat. For example, in these documents, a polyolefin resin powder having a melting point of 100°C - 150°C is preferably used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when a polyolefin resin powder is added, the polyurethane foam may change color to yellow. In addition, a technique of adding a cyclic siloxane for improving air permeability is disclosed in Patent Document 3. However, this additive is subject to various regulations. The present disclosure is for suppressing the discoloration of polyurethane foam and can be realized in the following forms.

Means for Solving the Problems

[0005] Polyols and, Polyisocyanate and, Polyolefin resin powder, A polyurethane foam obtained from a mixed composition, The composition comprises a polyurethane foam containing a hydroxycarboxylic acid. [Effects of the Invention]

[0006] According to this disclosure, discoloration of polyurethane foam can be suppressed. [Modes for carrying out the invention]

[0007] Herein lies a preferred example of this disclosure. The hydroxycarboxylic acid is lactic acid in the polyurethane foam. • Polyurethane foam with a YI value of 0.9 or less. • Polyolefin resins, Hydroxycarboxylic acid and Polyurethane foam containing polyurethane foam.

[0008] The disclosure is described in detail below. In this specification, when a numerical range is indicated using "-", it includes both the lower and upper limits 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".

[0009] 1. Polyurethane foam (Part 1) Polyurethane foam is obtained from a composition (hereinafter also referred to as "polyurethane resin composition") which is a mixture of polyol, polyisocyanate, and polyolefin resin powder. The composition contains hydrocarbons having 5 to 50 carbon atoms.

[0010] (1) Polyol The polyol is not particularly limited. Various polyols may be used individually or in combination of two or more. Examples of the polyol include polyether polyol, polyester polyol, polyether ester polyol, polycarbonate diol, and polyol having a carbon-carbon bond-based main chain. Examples of the polyether polyol include polyoxypropylene·polyoxyethylene polyol, polymer polyol, and polyoxytetramethylene glycol. Examples of the polyester polyol include aliphatic or aromatic polycondensation-based polyester polyol and polycaprolactone polyol. Examples of the polyol having a carbon-carbon bond-based main chain include polyolefin-based polyols such as polybutadiene polyol and isoprene polyol, and acrylic polyol.

[0011] (1.1) Polyether polyol Examples of the polyether polyol include polyether polyols obtained by adding one or more of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, epichlorohydrin, styrene oxide, etc. to one or more of the following initiators (compounds), or polytetramethylene ether glycol.

[0012] (1.1.1) Initiator (1.1.1.1) Polyhydric alcohol and alkylene oxide adduct of polyhydric alcohol Examples of the polyhydric alcohol: [Difunctional alcohol] Ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, trimethylene glycol [Trifunctional alcohol] Glycerin, trimethylolpropane [Tetrafunctional alcohol] Pentaerythritol [Hexafunctional alcohol] Sorbitol [Octafunctional alcohol] Sucrose (1.1.1.2) Alkylene oxide adduct of polyhydric phenols Examples of alkylene oxide adducts of polyhydric phenols: alkylene oxide adducts of bisphenol A (1.1.1.3) Polyhydric hydroxy compounds Examples of polyhydric hydroxy compounds: phosphoric acid, benzene phosphoric acid, polyphosphoric acids (e.g., tripolyphosphoric acid and tetrapolyphosphoric acid), etc. (1.1.1.4) Phenol - aniline - formaldehyde ternary condensation product (1.1.1.5) Aniline - formaldehyde condensation product (1.1.1.6) Polyamines Examples of polyamines: ethylenediamine, diethylenetriamine, triethylenetetramine, methylenebis orthochloroaniline, 4,4 - and 2,4’ - diphenylmethanediamine, 2,4 - tolylenediamine, 2,6 - tolylenediamine, etc. (1.1.1.7) Alkanolamines Examples of alkanolamines: triethanolamine, diethanolamine, etc.

[0013] (1.1.2) Polymer polyol A polymer polyol is a polyol obtained by graft - polymerizing an ethylenically unsaturated compound such as acrylonitrile, styrene, alkyl methacrylate, etc. onto the aforementioned polyether polyol.

[0014] (1.2) Polyester polyol A polyester polyol is a polyester polyol obtained by condensation of one or more compounds having at least two hydroxy groups and one or more compounds having at least two carboxyl groups, or ring - opening polymers of cyclic esters such as caprolactone, methyl valerolactone, etc.

[0015] (1.2.1) Examples of compounds having at least two hydroxy groups 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, sorbitol

[0016] (1.2.2) Examples of compounds having at least two carboxyl groups 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, hemeltic acid

[0017] (1.3) Polycarbonate diol Examples of polycarbonate polyols include those obtained by transesterification reactions between low molecular weight polyols such as butanediol and hexanediol and low molecular weight carbonates such as propylene carbonate and diethyl carbonate.

[0018] (1.4) Polyolefin-based polyols Examples of polyolefin-based polyols include polybutadiene polyols, polyisoprene polyols, hydrogenated polybutadiene polyols, and hydrogenated polyisoprene polyols.

[0019] (1.5) Plant-derived polyols In addition to the polyols listed above, plant-derived polyols may also be included as polyols. Examples of plant-derived polyols include castor oil polyols, soybean oil polyols, palm oil polyols, palm kernel oil polyols, coconut oil polyols, cashew oil polyols, olive oil polyols, cottonseed oil polyols, safflower oil polyols, sesame oil polyols, sunflower oil polyols, and linseed oil polyols. Plant-derived polyols typically have 2 to 3 hydroxyl functional groups per molecule. Examples of castor oil-based polyols include castor oil, reaction products of castor oil and polyols, and esterification reaction products of castor oil fatty acids and polyols. Examples of polyols to be reacted with castor oil or castor oil fatty acids include divalent polyols such as ethylene glycol, diethylene glycol, and propylene glycol, or trivalent or higher polyols such as glycerin, trimethylolpropane, hexanetriol, and sorbitol. Examples of soybean oil-based polyols include polyols derived from soybean oil, such as reaction products of soybean oil and polyols, and esterification reaction products of soybean oil fatty acids and polyols. The polyols used to react with soybean oil or soybean oil fatty acids can be the same as those used for castor oil. The same applies to palm oil-based polyols, cashew oil-based polyols, etc., as to soybean oil-based polyols. The various polyols exemplified as plant-derived polyols may be used individually or in combination of two or more.

[0020] (2) Catalyst The polyurethane resin composition may contain a catalyst. Conventional known catalysts can be used without particular limitation. Various catalysts may be used individually or in combination of two or more. Amine catalysts and quaternary ammonium salt catalysts can be used as catalysts. 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 can be used, as well as formate and other salts of triethylenediamine, oxyalkylene adducts of amino groups of primary and secondary amines, aza ring compounds such as NN-dialkylpiperazines, various N,N',N'-trialkylaminoalkylhexahydrotriazines, and amine catalysts having an amino group as a functional group such as N,N,N",N"-tetramethyldiethylenetriamine can be employed. Furthermore, quaternary ammonium salt catalysts such as tetraalkylammonium halides including tetramethylammonium chloride, tetraalkylammonium hydroxides including tetramethylammonium hydroxide, and tetraalkylammonium organic acid salts such as tetramethylammonium 2-ethylhexanoate, 2-hydroxypropyltrimethylammonium forate, 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. From the viewpoint of sufficiently promoting the polyurethane formation reaction, the amount of these catalysts is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.07 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 manufacturing costs, it is preferably 1 part by mass or less, more preferably 0.8 parts by mass or less, and even more preferably 0.5 parts by mass or less. From these viewpoints, the amount of one or more catalysts selected from the group consisting of amine catalysts and quaternary ammonium salt catalysts is preferably 0.01 parts by mass or more and 1 part by mass or less, more preferably 0.05 parts by mass or more and 0.8 parts by mass or less, and even more preferably 0.07 parts by mass or more and 0.5 parts by mass or less, per 100 parts by mass of polyol.

[0021] A metal catalyst (organometallic catalyst) can be used as the catalyst. Any conventionally known metal catalyst can be used without any particular limitations. As metal catalysts, for example, metal salts of Sn (tin), Pb (lead), Bi (bismuth), Ni (nickel), Co (cobalt), Fe (iron), Zr (zirconium), Cu (copper), Zn (zinc), etc., as well as metal salts of organic acids, can be used. More specifically, the following metal catalysts can be used. Sn catalysts: Tin(II) octyolate (2-ethylhexanoate tin, stanas dioctoate), tin(II) acetate, stanas diacetate, tin(II) octanoate, tin stanas dioleate, tin(II) neodecanoate stanas dilaurate, dibutyltin oxide, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, dioctyltin dilaurate, dibutyltin dimaleate, dioctyltin diacetate, etc. Pb catalysts: Lead octanoate, lead naphthenate, etc. Bi catalysts: Bismuth octylate, bismuth naphthenate, bismuth neodecanoate, bismuth rosinate, etc. Fe catalyst: Iron acetylacetonate, etc. Zr catalyst: Zirconium acetylacetonate, etc. Ni catalysts: Nickel acetylacetonate, nickel octylate, nickel naphthenate, etc. Co catalysts: Cobalt acetylacetonate, cobalt octylate, cobalt naphthenate, etc.

[0022] The amount of metal catalyst blended in a polyurethane resin composition is not particularly limited. From the viewpoint of sufficiently promoting the polyurethane formation reaction, the amount of metal catalyst blended is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, per 100 parts by mass of polyol. On the other hand, from the viewpoint of suppressing volatile organic compounds (such as 2-ethylhexanoic acid) derived from the metal catalyst, the amount is preferably 1.0 part by mass or less, more preferably 0.5 parts by mass or less, and even more preferably 0.3 parts by mass or less. From these viewpoints, the amount of metal catalyst blended is preferably 0.01 parts by mass or more and 1.0 part by mass or less, more preferably 0.05 parts by mass or more and 0.5 parts by mass or less, and even more preferably 0.1 parts by mass or more and 0.3 parts by mass or less, per 100 parts by mass of polyol.

[0023] (3) Foam stabilizer The polyurethane resin composition may contain a foam stabilizer. The foam stabilizer is not particularly limited. Specifically, foam stabilizers include silicone compounds such as organopolysiloxanes, organopolysiloxane-polyoxyalkylene copolymers, polyalkenylsiloxanes having polyoxyalkylene side chains, and silicone-grease copolymers; anionic surfactants such as sodium dodecylbenzenesulfonate and sodium lauryl sulfate; polyethersiloxanes; and phenolic compounds. These foam stabilizers may be used individually or in combination of two or more. The amount of foam stabilizer added is not particularly limited. Preferably, the amount of foam stabilizer added is 0.03 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of polyol.

[0024] (4) Foaming agent The polyurethane resin composition may contain a blowing agent. The blowing agent is not particularly limited. Suitable blowing agents include water, pentane, cyclopentane, hexane, cyclohexane, dichloromethane, and carbon dioxide. When water is used as the blowing agent, the amount added is determined to obtain the desired density and good foaming state in the polyurethane foam, and is usually preferably 1 to 10 parts by mass per 100 parts by mass of polyol.

[0025] (5) Polyisocyanates The polyisocyanate is not particularly limited. Preferably, at least one polyisocyanate selected from the group consisting of aromatic isocyanates, alicyclic isocyanates, and aliphatic isocyanates is used. A combination of one or more aliphatic isocyanates and one or more aromatic isocyanates is also possible. Furthermore, the polyisocyanate may be a bifunctional polyisocyanate having two isocyanate groups in one molecule, or a trifunctional or more polyisocyanate having three or more isocyanate groups in one molecule, and may be used alone or in combination of several. For example, difunctional polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylenediisocyanate, p-phenylenediisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, xylylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylenediisocyanate, and 3,3'-dimethoxy-4,4'-biphenylenediisocyanate. Examples include aromatic isocyanates such as phenylenediisocyanate, 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, isopropylenediisocyanate, methylene diisocyanate, and lysine isocyanate. Examples of polyisocyanates with three or more functions include 1-methylbenzol-2,4,6-triisocyanate, 1,3,5-trimethylbenzol-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, polymeric MDI, and the like. In addition, other urethane prepolymers, carbodiimide-modified isocyanates, isocyanurate-modified isocyanates, and burette-modified isocyanates can also be used.

[0026] The mixing ratio of polyisocyanate and polyol is not particularly limited. The isocyanate index is preferably between 80 and 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 the polyurethane resin composition by 100, and is calculated as [(Isocyanate equivalent in composition / Equivalent of active hydrogen in composition) × 100].

[0027] (6) Hydrocarbons with 5 to 50 carbon atoms Polyurethane resin compositions may contain hydrocarbons having 5 to 50 carbon atoms. The hydrocarbons having 5 to 50 carbon atoms are not particularly limited as long as their carbon number is within this range. The hydrocarbons may be saturated or unsaturated. The hydrocarbons may be branched or cyclic. Suitable examples of hydrocarbons include n-paraffins having 5 to 50 carbon atoms and isoparaffins having 5 to 50 carbon atoms. Hydrocarbons having 5 to 50 carbon atoms may be used individually or in mixtures of two or more types.

[0028] When a polyurethane resin composition contains hydrocarbons with 5 to 50 carbon atoms, the permeability of the polyurethane foam improves. The reason for this is explained below. It is presumed that the inclusion of hydrocarbons with 5 to 50 carbon atoms in the polyurethane resin composition causes numerous cell membranes to break during the foaming process of the polyurethane foam. Therefore, it is thought that high permeability of the polyurethane foam is ensured. Furthermore, it is presumed that the presence of hydrocarbons with 5 to 50 carbon atoms suppresses static electricity during the processing of polyurethane foam. Furthermore, hydrocarbons with 5 to 50 carbon atoms are presumed to exert an endothermic effect by vaporizing during the foaming process of polyurethane foam. Therefore, this effect is thought to lower the internal temperature of the polyurethane foam, further suppressing discoloration.

[0029] (6.1) n-paraffins with 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.

[0030] (6.2) Isoparaffins with 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-hexyltridecane.

[0031] (6.3) Amount of hydrocarbons with 5 to 50 carbon atoms The amount of hydrocarbons having 5 to 50 carbon atoms in a polyurethane resin composition is not particularly limited. From the viewpoint of ensuring sufficient permeability of the polyurethane foam, the amount of hydrocarbons is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and even more preferably 0.3 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 manufacturing costs, it is preferably 7.0 parts by mass or less, more preferably 5.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. From these viewpoints, the amount of hydrocarbons is preferably 0.1 parts by mass or more and 7.0 parts by mass or less, more preferably 0.2 parts by mass or more and 5.0 parts by mass or less, and even more preferably 0.3 parts by mass or more and 3.0 parts by mass or less, per 100 parts by mass of polyol. When two or more types of hydrocarbons are used, the above amounts refer to the total amount of all hydrocarbons.

[0032] (7) Polyolefin resin powder The polyolefin resin contained in the polyolefin resin powder is a resin obtained by the homopolymerization or copolymerization of α-olefins such as ethylene and propylene. Preferably, the polyolefin resin is one or more selected from the group consisting of polyethylene, polypropylene, and propylene-ethylene copolymer. Examples of polyolefin resin powders include polyethylene powder and polypropylene powder, and one or more of these can be used. From the viewpoint of melting point, polyethylene powder is preferred. The particle size of the polyolefin resin powder is not particularly limited. From the viewpoint of maintaining the tactile feel of the foam, the central particle diameter of the polyolefin resin powder is preferably 1 μm to 1000 μm, more preferably 5 μm to 800 μm, and even more preferably 10 μm to 600 μm. The amount of polyolefin resin powder blended in a polyurethane resin composition is not particularly limited and is acceptable as long as it is included. From the viewpoint of endothermic effect, the amount of polyolefin resin powder blended is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 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, it is preferably 50 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 20 parts by mass or less. From these viewpoints, the amount of polyolefin resin powder blended is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 5 parts by mass or more and 35 parts by mass or less, and even more preferably 10 parts by mass or more and 20 parts by mass or less, per 100 parts by mass of polyol. When two or more types of polyolefin resin powder are used, the above blending amounts refer to the total amount of all polyolefin resin powders.

[0033] (8) Hydroxycarboxylic acid The polyurethane resin composition contains hydroxycarboxylic acid from the viewpoint of suppressing discoloration of the polyurethane foam. Hydroxycarboxylic acids are compounds that have both a hydroxyl group and a carboxyl group in their molecule. In this disclosure, lactones, which are cyclic compounds formed by intramolecular dehydration condensation of the hydroxyl and carboxyl groups of a hydroxycarboxylic acid, and lactides, which are cyclic compounds formed by dehydration condensation of the hydroxyl and carboxyl groups of two molecules of hydroxycarboxylic acids, are also included as hydroxycarboxylic acids. Examples of hydroxycarboxylic acids include lactic acid, glycolic acid, propionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, 2-hydroxyethoxyacetic acid, 1,3-propanediol, 1-carbonate and their derivatives, lactones formed by intramolecular dehydration condensation of one or more of these, and lactides formed by intermolecular dehydration condensation of one or more of these. One or more of these hydroxycarboxylic acids can be used. The amount of hydroxycarboxylic acid blended in the polyurethane resin composition is not particularly limited. From the viewpoint of effectively suppressing discoloration of the polyurethane foam, the amount of hydroxycarboxylic acid blended is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and even more preferably 0.05 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 manufacturing costs, it is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less. From these viewpoints, the amount of lactic acid blended is preferably 0.01 parts by mass or more and 5 parts by mass or less, more preferably 0.03 parts by mass or more and 3 parts by mass or less, and even more preferably 0.05 parts by mass or more and 1 part by mass or less, per 100 parts by mass of polyol.

[0034] (9) Other additives Polyurethane resin compositions may contain other additives as appropriate, such as crosslinking agents, plasticizers, flame retardants, fillers, antioxidants, UV absorbers, defoaming agents, compatibilizers, colorants, stabilizers, antibacterial agents, antifungal agents, deodorizers, fragrances, and scents. 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. Examples of colorants include pigments, dyes, and colorants.

[0035] (10) Physical properties of polyurethane foam The physical properties of the polyurethane foam can be appropriately set according to the application and other factors. Flexible polyurethane foam is preferred. The polyurethane foam preferably possesses the following physical properties. (10.1) Apparent density The apparent density (JIS K7222) is 8 kg / m³. 3 -150kg / m 3 Preferably, 10 kg / m 3 -100kg / m 3 More preferably, 12 kg / m 3 -80kg / m 3 That is even more preferable. (10.2) Hardness The hardness (JIS K6400-2 Method D) is preferably 10N-600N, more preferably 20N-400N, and even more preferably 30N-200N. Within this range, the material is highly flexible and is suitable as a soft polyurethane foam. (10.3) Rebound elasticity The rebound elasticity (JIS K6400-3) is preferably 1%-80%, and more preferably 5%-70%. (10.4) Tensile strength, elongation The tensile strength (JIS K6400-5) is preferably 30 kPa or higher, and more preferably 50 kPa or higher. The elongation (JIS K6400-5) is preferably between 50% and 500%. If it is 50% or higher, it is highly flexible and preferable as a soft polyurethane foam. (10.5) Air permeability The air permeability (JIS K6400-7 Method A: 2012) is preferably 80 L / min or more, more preferably 100 L / min or more, and even more preferably 120 L / min or more. However, the air permeability is usually 300 L / min or less. (10.6) Hue (YI value) The YI value measured according to the method based on JIS Z8722 is preferably 5 or less, more preferably 1 or less, and even more preferably 0 or less. The YI value is usually -3 or higher. A higher YI value indicates a higher degree of yellowness.

[0036] 2. Polyurethane foam (Part 2) Polyurethane foam (part 2) is a polyurethane foam containing a polyolefin resin and a hydroxycarboxylic acid. This polyurethane foam (part 2) is usually obtained from a composition mixed with a polyol, a catalyst, a foam stabilizer, a blowing agent, a polyisocyanate, a hydroxycarboxylic acid, and a polyolefin resin powder. In polyurethane foam (part 2), the hydroxycarboxylic acid remains in the composition even after foam molding. In Polyurethane Foam (Part 2), the explanations for "Polyolefin Resin," "Hydroxycarboxylic Acid," and "Physical Properties of Polyurethane Foam" are the same as those in the "Polyurethane Foam (Part 1)" section, and are omitted here. In other words, the explanations for "Polyolefin Resin" (specifically, the explanation of "Polyolefin Resin contained in Polyolefin Resin Powder" in the explanation of "Polyolefin Resin Powder"), "Hydroxycarboxylic Acid," and "Physical Properties of Polyurethane Foam" as explained in the "Polyurethane Foam (Part 1)" section are applied as is.

[0037] 3. Manufacturing of polyurethane foam Polyurethane foam can be produced by known foaming methods, which involve stirring and mixing a polyurethane resin composition to react a polyol with a polyisocyanate. Foaming methods include slab foaming and mold foaming, and either method may be used. Slab foaming involves extruding the mixed polyurethane resin composition onto a belt conveyor and foaming it at atmospheric pressure and room temperature. Mold foaming, on the other hand, involves filling a mold with the mixed polyurethane resin composition and foaming it within the mold. [Examples]

[0038] 1. Manufacturing of polyurethane foam Polyurethane resin compositions were prepared using the proportions shown in Tables 1 and 2, and polyurethane foams for the examples and comparative examples were produced by slab foaming. Details of each ingredient are as follows: • Polyol: Polyether polyol, 3 functional groups, molecular weight 3000, hydroxyl value 56 mgKOH / g • Amine catalyst: N,N-dimethylaminohexanol • Foam stabilizer: Silicone-based foam stabilizer, product name: L-595, manufactured by Momentive. • Polyethylene powder (PE powder): Product name: Mipelon XM-330, manufactured by Mitsui Chemicals, Inc. • Metal catalyst: Tin(II) octoate • Polyisocyanates: Toluene diisocyanate (TDI)

[0039] The polyurethane foam was manufactured using the following procedure: The raw materials other than polyisocyanate were weighed into a cup container, stirred, and mixed to form a solution. Polyisocyanate was added to the mixed solution and stirred to obtain a polyurethane resin composition.

[0040] [Table 1]

[0041] [Table 2]

[0042] 2. Evaluation Method (1) Apparent density (density) The apparent density was measured according to JIS K7222. (2) Hardness Hardness was measured using the JIS K6400-2 Method D. (3) Rebound elasticity The rebound elasticity was measured according to JIS K6400-3. (4) Tensile strength, elongation Tensile strength and elongation were measured according to JIS K6400-5. (5) Air permeability Air permeability was measured according to the JIS K6400-7B method. (6) Hue (YI value) The hue (YI value) was measured according to the method based on JIS Z8722. The inside of the polyurethane foam being tested was measured the day after it was manufactured. (7) Processability Polyurethane foam was sliced ​​into multiple 5mm thick sheets. The sliced ​​polyurethane foam sheets were stacked and evaluated. Processability was evaluated according to the following criteria. Good: Even when sliced ​​foam pieces are stacked on top of each other, the electrostatic repulsion between the foam pieces is weak, resulting in good workability. Defect: When sliced ​​foam pieces are stacked together, static electricity causes strong repulsion between the foam pieces, resulting in poor workability.

[0043] 3.Results The results are shown in Tables 1 and 2. Note that "internal temperature" in the tables refers to the highest temperature inside the polyurethane foam during slab foaming. Comparative Examples 1-3 show the results for flexible polyurethane foam without the addition of lactic acid, a hydroxycarboxylic acid. Comparative Examples 1-3 had high YI values. Examples 1-8 show the results after adding lactic acid. In Examples 1-8, the YI value was lower than in Comparative Example 1-3, indicating that discoloration was suppressed. Furthermore, Examples 2, 3, 4, 5, 7, and 8, which also contained n-pentadecane, a hydrocarbon with 5 to 50 carbon atoms, showed good processability. Therefore, it was confirmed that processability is improved by incorporating hydrocarbons with 5 to 50 carbon atoms along with hydroxycarboxylic acids.

[0044] According to the above embodiments, a polyurethane foam with suppressed discoloration is provided.

[0045] This disclosure is not limited to the embodiments detailed above, and various modifications or changes are possible within the scope of this disclosure.

Claims

1. Polyols and, Polyisocyanate and, Polyolefin resin powder, A method for producing polyurethane foam by foaming a mixed composition, The composition contains a hydroxycarboxylic acid and a hydrocarbon having 5 to 50 carbon atoms. The hydroxycarboxylic acid is one or more selected from lactic acid and glycolic acid. A method for producing polyurethane foam, wherein the hydrocarbon having 5 to 50 carbon atoms is at least one selected from the group consisting of n-paraffin, isodecane, isododecane, 7-methyldecane, and 7-n-hexyltridecane, each having 5 to 50 carbon atoms.

2. Polyolefin resins, One or more hydroxycarboxylic acids selected from lactic acid and glycolic acid, It contains hydrocarbons with 5 to 50 carbon atoms, The aforementioned hydrocarbon having 5 to 50 carbon atoms is at least one selected from the group consisting of n-paraffin, isodecane, isododecane, 7-methyldecane, and 7-n-hexyltridecane, wherein the hydrocarbon has 5 to 50 carbon atoms.

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