Polyurethane foam manufacturing method

Abstract

The objective is to provide a method for producing polyurethane foam that exhibits good miscibility between the polyol composition and the polyisocyanate composition, and also has excellent initial reactivity during polyurethane foam formation. [Solution] The present invention relates to a method for producing polyurethane foam by mixing and reacting a polyol composition containing a catalyst comprising a polyol and a metal carboxylate salt with a polyisocyanate composition containing a polyisocyanate, and then foaming and curing the mixture. The production method includes a step of supplying a blowing agent A in a separate system from the polyol composition and the polyisocyanate composition, wherein the blowing agent A comprises a mixture of carbon dioxide and a hydrofluoroolefin with a boiling point of 0°C or lower. The blowing agent A is added to at least one of the polyol composition and the polyisocyanate composition in a ratio of 0.01 to 4 parts by mass per 100 parts by mass of polyol in the polyol composition, and the reaction proceeds after the addition.

Description

Technical Field

[0004] , , , , , , ,

[0001] The present invention relates to a method for producing polyurethane foam.

Background Art

[0002] Conventionally, polyurethane foam has been used as a heat insulating material in vehicles such as automobiles and furniture. Generally, polyurethane foam is formed by discharging and mixing a polyol composition and a polyisocyanate composition filled in separate containers.

[0003] Regarding the method for producing polyurethane foam, various methods are known. For example, there is a method in which a foaming agent is previously contained in the polyol composition, and at the production site, the polyol composition and the polyisocyanate composition are mixed and foamed and cured to produce the polyurethane foam. On the other hand, there is known a method for producing polyurethane foam that utilizes a system in which a foaming agent is added to either the polyol composition or the polyisocyanate composition at the production site. For example, in Patent Document 1, a method for producing polyurethane foam is disclosed in which carbon dioxide (supercritical, subcritical or liquid carbon dioxide) is added as a foaming agent in a certain amount to at least one of a polyol composition and a polyisocyanate composition at the production site of polyurethane foam. Further, in the examples, an embodiment in which a mixture of liquefied carbon dioxides and HFO-1234ze (1,3,3,3-tetrafluoropropene) is added as a foaming agent is also disclosed. It is described that by producing polyurethane foam by such a method, the miscibility of both compositions and the like are improved, and the uneven distribution of red phosphorus and the like used as a flame retardant in the foam is prevented.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] When the above-mentioned mixture of carbon dioxide and HFO-1234ze is used as a blowing agent and added to the polyol composition and / or polyisocyanate composition at the foam manufacturing site, the mixing properties of both compositions are improved, the foaming ratio is increased, and the thermal insulation properties are also improved. However, the method described above, which uses a mixture of carbon dioxide and HFO-1234ze as a foaming agent, has the problem of poor initial reactivity during foam formation, resulting in low adhesion.

[0006] Therefore, the present invention aims to provide a manufacturing method that exhibits good miscibility between a polyol composition and a polyisocyanate composition, and excellent initial reactivity during polyurethane foam formation. [Means for solving the problem]

[0007] The present inventors have found that the above problem can be solved by including a metal carboxylate salt as a catalyst in the polyol composition in a method for producing polyurethane foam, which includes a step of supplying a blowing agent containing a mixture of carbon dioxide and a hydrofluoroolefin with a boiling point of 0°C or lower, in a separate system from the polyol composition and the polyisocyanate composition, and have completed the present invention. In other words, the present invention is as follows [1] to [7].

[0008] [1] A method for producing polyurethane foam by mixing and reacting a polyol composition containing a polyol and a catalyst with a polyisocyanate composition containing a polyisocyanate, and then foaming and curing the mixture, wherein the catalyst contains a metal carboxylate salt, and the method includes a step of supplying a blowing agent A in a separate system from the polyol composition and the polyisocyanate composition, wherein the blowing agent A contains a mixture of carbon dioxide and a hydrofluoroolefin with a boiling point of 0°C or lower, and the blowing agent A is added to at least one of the polyol composition and the polyisocyanate composition in a ratio of 0.01 to 4 parts by mass per 100 parts by mass of polyol in the polyol composition, and the reaction proceeds after the addition, the method for producing polyurethane foam. [2] The method for producing polyurethane foam according to [1] above, wherein the hydrofluoroolefin with a boiling point of 0°C or less is HFO-1234ze. [3] The method for producing polyurethane foam according to [1] or [2] above, wherein the metal carboxylate salt is at least one selected from the group consisting of bismuth carboxylate, lead carboxylate, tin carboxylate, and zinc carboxylate. [4] A method for producing polyurethane foam according to any one of [1] to [3] above, wherein the metal carboxylate salt is a bismuth carboxylate salt. [5] A method for producing polyurethane foam according to any one of [1] to [4] above, wherein the carbon dioxide contained in the blowing agent A is supercritical, subcritical, or liquid carbon dioxide. [6] A method for producing polyurethane foam according to any one of [1] to [5] above, wherein the polyol composition contains a foaming agent B. [7] A method for producing polyurethane foam according to [6] above, wherein the blowing agent B contains a hydrofluoroolefin. [Effects of the Invention]

[0009] According to the method for producing polyurethane foam of the present invention, the polyol composition and the polyisocyanate composition have good miscibility, and the initial reaction during polyurethane foam formation is excellent, resulting in a polyurethane foam with excellent adhesion. [Modes for carrying out the invention]

[0010] The present invention relates to a method for producing polyurethane foam, which involves mixing a polyol composition containing a polyol and a catalyst with a polyisocyanate composition containing a polyisocyanate, reacting the mixture, and then foaming and curing the mixture. The present invention includes a step of supplying a blowing agent A in a separate system from the polyol composition and the polyisocyanate composition. The blowing agent A contains a mixture of carbon dioxide and a hydrofluoroolefin with a boiling point of 0°C or lower, and the blowing agent A is added to at least one of the polyol composition and the polyisocyanate composition in a ratio of 0.01 to 4 parts by mass per 100 parts by mass of polyol in the polyol composition, and the reaction proceeds after the addition. The present invention is characterized in that the catalyst contains a metal carboxylate salt.

[0011] The present invention provides a method for producing polyurethane foam, which includes a step of supplying a blowing agent A containing a mixture of carbon dioxide and a hydrofluoroolefin with a boiling point of 0°C or lower, in a separate system from the polyol composition and the polyisocyanate composition. In other words, in the manufacturing site for polyurethane foam, a separate channel for supplying the blowing agent A is provided in addition to the channels for supplying the polyol composition and the polyisocyanate, and the polyurethane foam is produced in this manner. That is, the blowing agent A is not included in the polyol composition or polyisocyanate composition during storage, but is added to at least one of the polyol composition and the polyisocyanate composition immediately before the production of the polyurethane foam. Thus, by supplying a foaming agent A containing a mixture of carbon dioxide and a hydrofluoroolefin with a boiling point of 0°C or lower in a separate system from the two compositions at the manufacturing site, polyurethane foam is produced. This improves the miscibility between the polyol composition and the polyisocyanate composition, making it easier to achieve uniform density and other properties, resulting in a polyurethane foam with excellent physical properties. Furthermore, in the manufacturing method of the present invention, since the polyol composition contains a metal carboxylate salt as a catalyst, the initial reactivity between the polyol and polyisocyanate is enhanced, resulting in good adhesion of the formed polyurethane foam.

[0012] [Polyol composition] The polyol composition used in the method for producing polyurethane foam of the present invention contains a polyol and a catalyst.

[0013] (catalyst) The catalyst used in this invention includes a metal carboxylate salt. The inclusion of the metal carboxylate salt enhances the initial reactivity between the polyol and polyisocyanate, resulting in improved adhesion of the resulting polyurethane foam. The metal carboxylate salt is a urethane catalyst used to promote the reaction between the polyol and polyisocyanate. The carboxylic acids used in carboxylic acid metal salts are not particularly limited as long as they are compounds having a carboxylic acid group, but examples include saturated aliphatic carboxylic acids, unsaturated aliphatic carboxylic acids, aromatic carboxylic acids, and dicarboxylic acids. Saturated aliphatic carboxylic acids are monocarboxylic acids, and examples include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, 2-ethylhexanoic acid, pelargonic acid, capric acid, neodecanoic acid, naphthenic acid, lauric acid, myristic acid, palmitic acid, margaric acid, and stearic acid. Examples of unsaturated aliphatic carboxylic acids include oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and sorbic acid. Examples of the aromatic carboxylic acid include benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, cinnamic acid, and the like. Examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, and the like.

[0014] The metal used for the metal carboxylate is not particularly limited, but for example, bismuth, lead, tin, zinc, etc. are preferable. That is, the metal carboxylate in the present invention is preferably at least one selected from the group consisting of bismuth carboxylate, lead carboxylate, tin carboxylate, and zinc carboxylate.

[0015] Examples of the bismuth carboxylate include bismuth 2-ethylhexanoate, bismuth neodecanoate, bismuth naphthenate, and the like. Examples of the lead carboxylate include lead 2-ethylhexanoate, lead benzoate, lead naphthenate, and the like. Examples of the tin carboxylate include tin acetate, tin 2-ethylhexanoate, tin oleate, tin laurate, dibutyltin diacetate, dimethyltin dilaurate, dibutyltin dilaurate, dibutyltin dineodecanoate, dioctyltin dilaurate, and the like. Examples of the zinc carboxylate include zinc 2-ethylhexanoate, zinc naphthenate, and the like.

[0016] Among the above, the metal carboxylate in the present invention is preferably a bismuth carboxylate, particularly bismuth 2-ethylhexanoate, from the viewpoints of improving the initial reactivity and reducing the environmental load.

[0017] The content of the metal carboxylate in the polyol composition is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 1 to 8 parts by mass with respect to 100 parts by mass of the polyol. When the content of the metal carboxylate is not less than these lower limit values, the initial reactivity is improved, and when it is not more than these upper limit values, the control of the reaction becomes easy.

[0018] In the present invention, a urethanization catalyst other than the metal carboxylate may be used in combination with the metal carboxylate. Examples of the urethanization catalyst other than the metal carboxylate include amine-based catalysts such as imidazole compounds and piperazine compounds. Examples of the imidazole compound include tertiary amines in which the secondary amine at the 1-position of the imidazole ring is substituted with an alkyl group, an alkenyl group, etc. Specifically, N-methylimidazole, 1,2-dimethylimidazole, 1-ethyl-2-methylimidazole, 1-methyl-2-ethylimidazole, 1,2-diethylimidazole, and 1-isobutyl-2-methylimidazole, etc. are included. Also included are imidazole compounds in which the secondary amine in the imidazole ring is substituted with a cyanoethyl group. Examples of the piperazine compound include tertiary amines such as N-methyl-N’,N’-dimethylaminoethylpiperazine and trimethylaminoethylpiperazine. Examples of the amine-based catalyst include various tertiary amines such as pentamethyldiethylenetriamine, triethylamine, N-methyldicyclohexylamine, N-methylmorpholine bis(2-dimethylaminoethyl)ether, N,N,N’,N”,N”-pentamethyldiethylenetriamine, N,N,N’-trimethylaminoethyl-ethanolamine, bis(2-dimethylaminoethyl)ether, N,N-dimethylcyclohexylamine, diazabicycloundecene, triethylenediamine, tetramethylhexamethylenediamine, and tripropylamine, etc., in addition to imidazole compounds and piperazine compounds.

[0019] The content of the urethane catalyst is, for example, 0.2 to 20 parts by mass, preferably 1 to 10 parts by mass, per 100 parts by mass of polyol.

[0020] In the present invention, the catalyst preferably includes a trimerizing catalyst in addition to the urethane catalyst described above. A trimerization catalyst is a catalyst that reacts with the isocyanate groups contained in polyisocyanates to trimerize them and promote the formation of isocyanurate rings. Suitable trimerization catalysts include nitrogen-containing aromatic compounds such as tris(dimethylaminomethyl)phenol, 2,4-bis(dimethylaminomethyl)phenol, and 2,4,6-tris(dialkylaminoalkyl)hexahydro-S-triazine; alkali metal salts of carboxylic acids such as potassium acetate, potassium 2-ethylhexanoate, and potassium octoate; tertiary ammonium salts such as trimethylammonium salt, triethylammonium salt, and triphenylammonium salt; quaternary ammonium salts such as tetramethylammonium salt, tetraethylammonium salt, tetraphenylammonium salt, triethylmonomethylammonium salt, and quaternary ammonium carboxylic acid salts. A suitable specific example of the carboxylic acid in the above-mentioned ammonium carboxylic acid salts is at least one selected from the group consisting of 2-ethylhexanoic acid, 2,2-dimethylpropanoic acid, acetic acid, and formic acid. The trimerization catalyst may be used alone or in combination of two or more, but the use of two or more is preferable.

[0021] The content of the trimerizing catalyst is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 1 to 5 parts by mass, per 100 parts by mass of polyol.

[0022] (Polyol) Examples of polyols included in the polyol composition include polylactone polyols, polycarbonate polyols, aromatic polyols, alicyclic polyols, polyester polyols, polymer polyols, and polyether polyols.

[0023] Examples of polylactone polyols include polypropiolactone glycol, polycaprolactone glycol, and polyvalerolactone glycol. Examples of polycarbonate polyols include polyols obtained by the de-alcoholization reaction of hydroxyl group-containing compounds such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, and nonanediol with ethylene carbonate, propylene carbonate, etc.

[0024] Examples of aromatic polyols include bisphenol A, bisphenol F, phenol novolac, and cresol novolac. Examples of alicyclic polyols include cyclohexanediol, methylcyclohexanediol, isophoronediol, dicyclohexylmethanediol, and dimethyldicyclohexylmethanediol.

[0025] Examples of polyester polyols include polymers obtained by dehydrating and condensing a polybasic acid and a polyhydric alcohol, and condensates of hydroxycarboxylic acids and the aforementioned polyhydric alcohols. Examples of polybasic acids include adipic acid, aze1 acid, sebacic acid, isophthalic acid (m-phthalic acid), terephthalic acid (p-phthalic acid), and succinic acid. Examples of polyhydric alcohols include bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexane glycol, and neopentyl glycol. Examples of hydroxycarboxylic acids include castor oil and reaction products of castor oil and ethylene glycol.

[0026] Examples of polymer polyols include polymers obtained by graft polymerization of ethylenically unsaturated compounds such as acrylonitrile, styrene, methyl acrylate, and methacrylate onto aromatic polyols, alicyclic polyols, aliphatic polyols, and polyester polyols, as well as polybutadiene polyols, or hydrogenated versions thereof.

[0027] Examples of polyether polyols include polymers obtained by ring-opening polymerization of at least one alkylene oxide such as ethylene oxide, propylene oxide, or tetrahydrofuran in the presence of at least one low molecular weight active hydrogen compound having two or more active hydrogen atoms. Examples of low molecular weight active hydrogen compounds having two or more active hydrogen atoms include diols such as bisphenol A, ethylene glycol, propylene glycol, butylene glycol, and 1,6-hexanediol, triols such as glycerin and trimethylolpropane, amines such as ethylenediamine, and butylenediamine.

[0028] The polyol used in the present invention preferably contains at least one selected from polyester polyols and polyether polyols, and preferably contains at least a polyester polyol. More preferably, it contains a polyester polyol obtained by dehydrating and condensing an aromatic ring-containing polybasic acid such as isophthalic acid (m-phthalic acid) or terephthalic acid (p-phthalic acid) with a dihydric alcohol such as bisphenol A, ethylene glycol, and 1,2-propylene glycol. The polyester polyol content per 100 parts by mass of polyol is preferably 50 parts by mass or more, more preferably 80 parts by mass or more, and even more preferably 90 parts by mass or more.

[0029] The hydroxyl value of the polyol is preferably 20 to 300 mg KOH / g, more preferably 30 to 275 mg KOH / g, and even more preferably 50 to 250 mg KOH / g. When the hydroxyl value of the polyol is below the upper limit, the viscosity of the polyol liquid does not become excessively high, which is preferable from the viewpoint of handling and other factors. On the other hand, when the hydroxyl value of the polyol is above the lower limit, the crosslinking density of the polyurethane foam increases, resulting in higher strength. The hydroxyl value of polyols can be measured according to JIS K 1557-1:2007.

[0030] (Foaming agent B) The polyol composition of the present invention preferably contains a foaming agent B. The foaming agent B can be used to mix and foam the polyol composition and polyisocyanate composition, thereby promoting the formation of polyurethane foam. It should be noted that, unlike the foaming agent A described above, foaming agent B is not added immediately before the manufacture of the polyurethane foam, but is incorporated into the polyol composition before the addition of foaming agent A. While the foaming agent B is not particularly limited, it is preferable to include, for example, water, hydrocarbon compounds, chlorinated aliphatic hydrocarbon compounds, hydrofluorocarbons, hydrochlorofluorocarbon compounds, and hydrofluoroolefins. In particular, from the viewpoint of good foam formation and reduction of environmental impact, it is preferable that the foaming agent B contains hydrofluoroolefins. By including hydrofluoroolefins, the dispersibility of the fillers in the foam is improved when the fillers described later are used. Furthermore, from the viewpoint of improving foaming properties, foaming agent B preferably contains water, and more preferably contains both water and hydrofluoroolefin.

[0031] Examples of hydrofluoroolefins included in foaming agent B include fluoroalkenes having 3 to 6 carbon atoms. Furthermore, the hydrofluoroolefin may also be a hydrochlorofluoroolefin containing a chlorine atom, and therefore may also be a chlorofluoroalkene having 3 to 6 carbon atoms. Hydrofluoroolefins with 3 or 4 carbon atoms are preferred.

[0032] The hydrofluoroolefin used as the foaming agent B is preferably one whose boiling point at 1 atmosphere is greater than 0°C. Examples include (E)-1-chloro-3,3,3-trifluoropropene (HFO-1233zd(E)), (Z)-1-chloro-3,3,3-trifluoropropene (HFO-1233zd(Z)), (Z)-1,1,1,4,4,4-hexafluorobuto-2-ene (HFO-1336mzz(Z)), (E)-1,1,1,4,4,4-hexafluorobuto-2-ene (HFO-1336mzz(E)), and (Z)-1-chloro-2,3,3,3-tetrafluoropropene (HFO-1224yd(Z)).

[0033] The content of the hydrofluoroolefin used as the foaming agent B is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, and even more preferably 15 to 30 parts by mass, per 100 parts by mass of polyol, from the viewpoint of setting the density of the polyurethane foam within a desired range.

[0034] The water content used as the foaming agent B is preferably 0.1 to 15 parts by mass, more preferably 0.2 to 10 parts by mass, and even more preferably 0.5 to 5 parts by mass, per 100 parts by mass of polyol, from the viewpoint of setting the density of the polyurethane foam within a desired range.

[0035] The content of foaming agent B in the polyol composition is preferably 0.1 to 65 parts by mass, more preferably 0.2 to 50 parts by mass, and even more preferably 0.5 to 35 parts by mass, per 100 parts by mass of polyol, from the viewpoint of setting the density of the polyurethane foam within a desired range.

[0036] (Filler) The polyol composition may contain a filler. By including a filler, the polyurethane foam can be given functions depending on the type of filler. Preferably, the filler contains a flame retardant. By using a flame retardant as a filler, the polyurethane foam can be given high flame retardant performance. The flame retardant used as a filler is preferably a solid flame retardant. Using a solid flame retardant can more effectively enhance flame retardancy. A solid flame retardant is a flame retardant that becomes solid at room temperature (23°C) and normal pressure (1 atmosphere).

[0037] From the viewpoint of more effectively enhancing flame retardancy, the solid flame retardant is preferably at least one selected from the group consisting of red phosphorus-based flame retardants, boron-containing flame retardants, bromine-containing flame retardants, phosphate-containing flame retardants, chlorine-containing flame retardants, antimony-containing flame retardants, metal hydroxides, and needle-shaped fillers.

[0038] <Red phosphorus-based flame retardant> Red phosphorus-based flame retardants may consist of pure red phosphorus, but they may also be red phosphorus coated with a resin, metal hydroxide, metal oxide, etc., or red phosphorus mixed with a resin, metal hydroxide, metal oxide, etc. The resin used to coat or mix with red phosphorus is not particularly limited, but examples include thermosetting resins such as phenolic resins, epoxy resins, unsaturated polyester resins, melamine resins, urea resins, aniline resins, and silicone resins. From the viewpoint of flame retardancy, metal hydroxides are preferred as the compound used for coating or mixing. The metal hydroxides described later may be appropriately selected and used.

[0039] The amount of red phosphorus-based flame retardant added is preferably 3 to 60 parts by mass, more preferably 10 to 50 parts by mass, and even more preferably 20 to 45 parts by mass, per 100 parts by mass of polyol. By setting the amount of red phosphorus-based flame retardant above these lower limits, the effect of the red phosphorus-based flame retardant is more easily achieved. On the other hand, by setting it below the upper limit, foaming is not inhibited by the red phosphorus-based flame retardant.

[0040] <Boron-containing flame retardant> Examples of boron-containing flame retardants include borax, boron oxide, boric acid, and borates. Examples of boron oxides include diboron trioxide, boron trioxide, diboron dioxide, tetraboron trioxide, and tetraboron pentoxide. Examples of borates include alkali metals, alkaline earth metals, elements from groups 4, 12, and 13 of the periodic table, and ammonium borates. Specifically, examples include alkali metal borates such as lithium borate, sodium borate, potassium borate, and cesium borate; alkaline earth metal borates such as magnesium borate, calcium borate, and barium borate; zirconium borate, zinc borate, aluminum borate, and ammonium borate. Boron-containing flame retardants may be used alone or in combination of two or more types. The boron-containing flame retardant is preferably a borate, and more preferably zinc borate.

[0041] The amount of boron-containing flame retardant is not particularly limited, but is preferably 3 to 45 parts by mass, more preferably 5 to 40 parts by mass, and even more preferably 10 to 25 parts by mass per 100 parts by mass of polyol. By setting the amount of boron-containing flame retardant above these lower limits, the effect of the boron-containing flame retardant is more easily exerted, and flame retardancy is enhanced. On the other hand, by setting it below the upper limit, foaming is not inhibited by the boron-containing flame retardant.

[0042] <Bromine-containing flame retardant> Bromine-containing flame retardants are not particularly limited as long as they contain bromine in their molecular structure and are solid at room temperature and pressure, but examples include aromatic compounds containing brominated aromatic rings. Examples of brominated aromatic ring-containing aromatic compounds include monomeric organic bromine compounds such as hexabromobenzene, pentabromotoluene, hexabromobiphenyl, decabromobiphenyl, decabromodiphenyl ether, octabromodiphenyl ether, hexabromodiphenyl ether, bis(pentabromophenoxy)ethane, ethylenebis(pentabromophenyl), ethylenebis(tetrabromophthalimide), and tetrabromobisphenol A.

[0043] Furthermore, the brominated aromatic ring-containing aromatic compound may also be a brominated polymer. Specifically, examples include polycarbonate oligomers produced using brominated bisphenol A as a raw material, brominated polycarbonates such as copolymers of this polycarbonate oligomer and bisphenol A, and diexo compounds produced by the reaction of brominated bisphenol A and epichlorohydrin. In addition, examples include brominated epoxy compounds such as monoepoxy compounds obtained by the reaction of brominated phenols and epichlorohydrin, poly(brominated benzyl acrylate), brominated polyphenylene ether, brominated bisphenol A and cyanuryl chloride condensates, brominated polystyrene such as brominated (polystyrene), poly(brominated styrene), and crosslinked brominated polystyrene, and crosslinked or non-crosslinked brominated poly(methylstyrene). Furthermore, compounds other than brominated aromatic ring-containing aromatic compounds such as hexabromocyclododecane may also be used. These bromine-containing flame retardants may be used individually or in combination of two or more. Among the above, brominated aromatic ring-containing aromatic compounds are preferred, and among these, monomer-based organic bromine compounds such as ethylenebis(pentabromophenyl) are preferred.

[0044] The amount of bromine-containing flame retardant added is preferably 3 to 60 parts by mass, more preferably 10 to 50 parts by mass, and even more preferably 20 to 45 parts by mass, per 100 parts by mass of polyol. By setting the amount of bromine-containing flame retardant above these lower limits, the effect of the bromine-containing flame retardant is more easily achieved. On the other hand, by setting it below the upper limit, foaming is not inhibited by the bromine-containing flame retardant.

[0045] <Phosphate-containing flame retardant> Examples of phosphate-containing flame retardants include phosphates comprising salts of various phosphoric acids with at least one metal or compound selected from metals of groups IA to IVB of the periodic table, ammonia, aliphatic amines, aromatic amines, and heterocyclic compounds containing nitrogen in the ring. Phosphates are not particularly limited, but examples include monophosphates, pyrophosphates, and polyphosphates. Examples of metals in groups IA through IVB of the periodic table include lithium, sodium, calcium, barium, iron(II), iron(III), and aluminum. Examples of aliphatic amines include methylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, and piperazine. Examples of aromatic amines include aniline, o-triidine, 2,4,6-trimethylaniline, anisidine, and 3-(trifluoromethyl)aniline. Examples of heterocyclic compounds containing nitrogen in the ring include pyridine, triazine, and melamine.

[0046] Specific examples of phosphate-containing flame retardants include monophosphates such as trialuminum phosphate, pyrophosphates, and polyphosphates. Here, the polyphosphate is not particularly limited, but examples include ammonium polyphosphate, piperazine polyphosphate, melamine polyphosphate, ammonium polyphosphate amide, and aluminum polyphosphate. One or more of the above-mentioned phosphate-containing flame retardants may be used.

[0047] The amount of phosphate-containing flame retardant is not particularly limited, but is 3 to 40 parts by mass, more preferably 5 to 35 parts by mass, and even more preferably 10 to 30 parts by mass, per 100 parts by mass of polyol. By setting the amount of phosphate-containing flame retardant above these lower limits, the effect of the phosphate-containing flame retardant is more easily achieved. On the other hand, by setting it below the upper limit, foaming is not inhibited by the phosphate-containing flame retardant.

[0048] <Chlorine-containing flame retardant> Examples of chlorine-containing flame retardants include those commonly used in flame-retardant resin compositions, such as polychlorinated naphthalene, chlorendic acid, and dodecachlorododecahydrodimethanodibenzocyclooctene, which is sold under the trade name "Dechloran Plus." The amount of chlorine-containing flame retardant is not particularly limited, but is preferably 3 to 40 parts by mass, more preferably 5 to 35 parts by mass, and even more preferably 10 to 30 parts by mass per 100 parts by mass of polyol. By setting the amount of chlorine-containing flame retardant above these lower limits, the effect of the chlorine-containing flame retardant is more easily achieved. On the other hand, by setting it below the upper limit, foaming is not inhibited by the chlorine-containing flame retardant.

[0049] <Antimony-containing flame retardant> Examples of antimony-containing flame retardants include antimony oxide, antimonate salts, and pyroantimonate salts. Examples of antimony oxide include antimony trioxide and antimony pentoxide. Examples of antimonate salts include sodium antimonate and potassium antimonate. Examples of pyroantimonate salts include sodium pyroantimonate and potassium pyroantimonate. Antimony-containing flame retardants may be used alone or in combination of two or more types. The preferred antimony-containing flame retardant used in this invention is antimony trioxide.

[0050] The amount of antimony-containing flame retardant is not particularly limited, but is preferably 1 to 40 parts by mass, more preferably 2 to 35 parts by mass, and even more preferably 3 to 30 parts by mass per 100 parts by mass of polyol. By setting the amount of antimony-containing flame retardant above these lower limits, the effect of the antimony-containing flame retardant is more easily exerted, and flame retardancy is enhanced. On the other hand, by setting it below the upper limit, foaming is not inhibited by the antimony-containing flame retardant.

[0051] <Metal hydroxide> Examples of metal hydroxides used in the present invention include magnesium hydroxide, calcium hydroxide, aluminum hydroxide, iron hydroxide, nickel hydroxide, zirconium hydroxide, titanium hydroxide, zinc hydroxide, copper hydroxide, vanadium hydroxide, and tin hydroxide. A single metal hydroxide may be used, or two or more may be used in combination.

[0052] The amount of metal hydroxide added is, for example, 0.1 to 50 parts by mass, preferably 0.2 to 30 parts by mass, more preferably 0.3 to 20 parts by mass, and even more preferably 0.5 to 15 parts by mass, per 100 parts by mass of polyol. By setting the amount of metal hydroxide above these lower limits, the effects of the metal hydroxide are more easily exhibited, and flame retardancy is enhanced. On the other hand, by setting it below the upper limit, foaming is not inhibited by the metal hydroxide.

[0053] <Needle-shaped filler> Examples of needle-shaped fillers include potassium titanate whiskers, aluminum borate whiskers, magnesium-containing whiskers, silicon-containing whiskers, wollastonite, sepiolite, zonolite, elestadite, boehmite, rod-shaped hydroxyapatite, glass fibers, carbon fibers, graphite fibers, metal fibers, slag fibers, gypsum fibers, silica fibers, alumina fibers, silica-alumina fibers, zirconia fibers, boron nitride fibers, boron fibers, stainless steel fibers, and the like. These needle-shaped fillers can be used individually or in combination of two or more types.

[0054] The aspect ratio (length / diameter) of the needle-shaped filler used in the present invention is preferably in the range of 5 to 50, and more preferably in the range of 10 to 40. This aspect ratio can be determined by observing the needle-shaped filler with a scanning electron microscope and measuring its length and width.

[0055] The amount of needle-shaped filler added is, for example, 10 to 100 parts by mass, preferably 20 to 90 parts by mass, more preferably 30 to 80 parts by mass, and even more preferably 40 to 70 parts by mass, per 100 parts by mass of polyol. By setting the amount of needle-shaped filler above these lower limits, the shape of the polyurethane foam after combustion is more easily maintained. On the other hand, by setting the amount below these upper limits, foaming is less likely to be inhibited by the needle-shaped filler.

[0056] The amount of solid flame retardant is not particularly limited, but is, for example, 10 to 200 parts by mass, preferably 20 to 150 parts by mass, and more preferably 40 to 120 parts by mass, per 100 parts by mass of polyol. By setting the amount of solid flame retardant to be above these lower limits, appropriate flame retardancy can be imparted to the polyurethane foam. By setting the amount of solid flame retardant to be below these upper limits, it becomes easier to obtain polyurethane foam with less density variation depending on the location.

[0057] As fillers, inorganic fillers other than the flame retardants mentioned above may be included. As inorganic fillers, alumina, titanium oxide, calcium oxide, magnesium oxide, iron oxide, tin oxide, ferrites, basic magnesium carbonate, calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, dawsonite, hydrotalcite, calcium sulfate, barium sulfate, calcium silicate, talc, mica, montmorillonite, bentonite, activated clay, imogolite, sericite, glass beads, aluminum nitride, boron nitride, silicon nitride, various metal powders, magnesium sulfate, lead zirconate titanate, molybdenum sulfide, silicon carbide, various magnetic powders, fly ash, etc. can be used as appropriate. Inorganic fillers may be used individually or in combination of two or more types.

[0058] The filler content in the polyol composition is, for example, 10 to 300 parts by mass, preferably 20 to 150 parts by mass, and more preferably 40 to 120 parts by mass, per 100 parts by mass of polyol. By setting the filler content above these lower limits, it becomes easier to impart functions to the polyurethane foam according to the type of filler. By setting the filler content below these upper limits, it becomes easier to obtain polyurethane foam with less density variation depending on the location.

[0059] (Liquid flame retardant) The polyol composition may contain a liquid flame retardant. A liquid flame retardant is a flame retardant that becomes liquid at room temperature (23°C) and normal pressure (1 atm). A specific example of a liquid flame retardant is a phosphate ester. Unlike solid flame retardants, liquid flame retardants are less likely to form precipitates during storage and are easy to handle.

[0060] As the phosphate ester, it is preferable to use monophosphate esters, condensed phosphate esters, etc. Examples of monophosphate esters include trialkyl phosphates such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, and tri(2-ethylhexyl) phosphate; halogen-containing phosphate esters such as tris(β-chloropropyl) phosphate; trialkoxy phosphates such as tributoxyethyl phosphate; aromatic ring-containing phosphate esters such as tricresyl phosphate, trixylenyl phosphate, tris(isopropylphenyl) phosphate, cresyldiphenyl phosphate, and diphenyl(2-ethylhexyl) phosphate; and acidic phosphate esters such as monoisodecyl phosphate and diisodecyl phosphate.

[0061] Examples of condensed phosphate esters include aromatic condensed phosphate esters such as trialkyl polyphosphates, resorcinol polyphenyl phosphates, bisphenol A polycresyl phosphates, and bisphenol A polyphenyl phosphates. Examples of commercially available condensed phosphate esters include "CR-733S," "CR-741," and "CR747" from Daihachi Chemical Industry Co., Ltd., and "ADEKA Stab PFR" and "FP-600" from ADEKA Corporation.

[0062] Liquid flame retardants may be used individually from the above-mentioned types, or two or more types may be used in combination. Among these, monophosphate esters are preferred, and tris(β-chloropropyl) phosphate is more preferred, from the viewpoint of facilitating the manufacture of polyurethane foam and improving the flame retardancy of polyurethane foam.

[0063] If a liquid flame retardant is included, the amount is preferably 5 to 80 parts by mass, more preferably 10 to 70 parts by mass, and even more preferably 20 to 60 parts by mass, per 100 parts by mass of polyol.

[0064] (Foam stabilizer) The polyol composition preferably contains a foam stabilizer. The foam stabilizer improves the foaming properties of the polyurethane composition obtained by mixing the polyol composition and the polyisocyanate composition. Examples of foam stabilizers include polyoxyalkylene-based foam stabilizers such as polyoxyalkylene alkyl ethers, and surfactants such as silicone-based foam stabilizers such as organopolysiloxanes. These foam stabilizers may be used individually or in combination of two or more types. The amount of foam stabilizer added is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, and even more preferably 1 to 5 parts by mass, per 100 parts by mass of polyol. If the amount of foam stabilizer is above these lower limits, the polyurethane composition becomes easier to foam, and a homogeneous polyurethane foam is easier to obtain. If the amount of foam stabilizer is below these upper limits, a good balance is achieved between manufacturing costs and the effects obtained.

[0065] (Other ingredients) The polyol liquid formulation may, as necessary and within the limits that do not impair the objectives of the present invention, contain one or more additives selected from phenolic, amine, and sulfur-based antioxidants, heat stabilizers, metal damage inhibitors, antistatic agents, stabilizers, crosslinking agents, lubricants, softeners, pigments, tackifying resins, polybutene, petroleum resins, and other tackifying agents.

[0066] [Polyisocyanate composition] The polyisocyanate composition used in the method for producing polyurethane foam of the present invention contains a polyisocyanate. As the polyisocyanate, known polyisocyanates used for forming polyurethane foam can be used, such as aromatic polyisocyanates, alicyclic polyisocyanates, and aliphatic polyisocyanates. Examples of aromatic polyisocyanates include phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, triphenylmethane triisocyanate, naphthalene diisocyanate, and polymethylene polyphenyl polyisocyanate.

[0067] Examples of alicyclic polyisocyanates include cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and dimethyldicyclohexylmethane diisocyanate.

[0068] Examples of aliphatic polyisocyanates include methylene diisocyanate, ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, and hexamethylene diisocyanate.

[0069] Among these, aromatic polyisocyanates are preferred from the viewpoint of ease of use and availability, and diphenylmethane diisocyanate is more preferred. Polyisocyanates may be used individually or in mixtures of two or more types.

[0070] (Isocyanate Index) The isocyanate index of the polyurethane composition obtained by mixing the polyol composition and the polyisocyanate composition of the present invention is not particularly limited, but is preferably 120 to 500, and more preferably 150 to 400. If the isocyanate index is above the lower limit, the amount of polyisocyanate relative to the polyol becomes excessive, making it easier for isocyanurate bonds to be formed by the trimer of polyisocyanate, resulting in improved flame retardancy of the polyurethane foam. If the isocyanate index is below the upper limit, a good balance is achieved between the flame retardancy of the resulting polyurethane foam and the manufacturing cost.

[0071] The isocyanate index can be calculated using the following method. Isocyanate Index = Equivalents of polyisocyanate ÷ (Equivalents of polyol + Equivalents of water) × 100 Here, each equivalent number can be calculated as follows: • Equivalent weight of polyisocyanate = Amount of polyisocyanate used (g) × NCO content (mass%) / Molecular weight of NCO (moles) × 100 • Equivalent weight of polyol = OHV × Amount of polyol used (g) ÷ Molecular weight of KOH (millimoles) OHV is the hydroxyl value (mgKOH / g) of a polyol. • Equivalent amount of water = Amount of water used (g) / Molecular weight of water (moles) × Number of OH groups in water In the above formulas, the molecular weight of NCO is 42 moles, the molecular weight of KOH is 56100 millimoles, the molecular weight of water is 18 moles, and the number of OH groups in water is 2.

[0072] [Foaming agent A supply process] The present invention provides a method for producing polyurethane foam, which includes a step of supplying the blowing agent A in a separate system from the polyol composition and the polyisocyanate composition. In other words, in the manufacturing site for polyurethane foam, a separate channel for supplying the blowing agent A is provided in addition to the channels for supplying the polyol composition and the polyisocyanate, and the polyurethane foam is produced in this manner. By supplying the blowing agent A in a separate system from the other two compositions in the manufacturing site, the polyol composition and the polyisocyanate composition become more miscible, making it easier to achieve uniform density and other properties, and resulting in the formation of a polyurethane foam with excellent physical properties.

[0073] In this invention, polyurethane foam is produced by mixing a polyol composition and a polyisocyanate composition, reacting them, and then foaming and curing them. The foaming agent A may be supplied to either the polyol composition or the polyisocyanate composition before mixing them, but it is preferable to supply it to the polyol composition considering the ease of foam formation. The foaming agent A may also be mixed simultaneously with the mixing of the polyol composition and the polyisocyanate composition (i.e., the foaming agent A may be supplied at the location where the two compositions are mixed).

[0074] The blowing agent A contains a mixture of carbon dioxide and hydrofluoroolefin with a boiling point of 0°C or lower. The carbon dioxide is supercritical, subcritical, or liquid carbon dioxide. Supercritical, subcritical, or liquid carbon dioxide is carbon dioxide gas that has been brought to a supercritical, subcritical, or liquid state by pressurizing it at a predetermined temperature. Specifically, supercritical carbon dioxide is carbon dioxide in a fluid state where both the pressure and temperature exceed the critical pressure and critical temperature. Subcritical carbon dioxide is carbon dioxide in a liquid state where the pressure is above the critical pressure and the temperature is below the critical temperature, or carbon dioxide in a liquid state where the pressure is below the critical pressure and the temperature is above the critical temperature, or carbon dioxide in a state where the temperature and pressure are below the critical point but close to it. Furthermore, liquid carbon dioxide is obtained by liquefying under temperature and pressure conditions above the triple point. The mass ratio of carbon dioxide to hydrofluoroolefin with a boiling point of 0°C or less in the mixture (carbon dioxide / hydrofluoroolefin with a boiling point of 0°C or less) is not particularly limited, but from the viewpoint of improving the miscibility of the composition, it is, for example, 0.05 to 5, preferably 0.1 to 2, and more preferably 0.2 to 1.

[0075] Examples of hydrofluoroolefins with a boiling point of 0°C or lower include 1,3,3,3-tetrafluoropropene (HFO-1234ze), 1,2,3,3,3-pentafluoropropene (HFO-1225ye), 1,1,1,3,3-pentafluoropropene (HFO-1225zc), and 2,3,3,3-tetrafluoropropene (HFO-1234yf). One hydrofluoroolefin with a boiling point of 0°C or lower may be used alone, or two or more may be used in combination. Among these, HFO-1234ze is preferred as the hydrofluoroolefin with a boiling point of 0°C or lower. That is, the foaming agent A preferably contains a mixture of carbon dioxide and HFO-1234ze, and more preferably consists only of carbon dioxide and HFO-1234ze. In this specification, boiling point means the boiling point at 1 atmosphere.

[0076] The foaming agent A may be added to at least one of the polyol composition and the polyisocyanate composition before mixing them, but it is preferable to supply it to the polyol composition considering the ease of foam formation. Alternatively, the foaming agent A may be added simultaneously with the mixing of the polyol composition and the polyisocyanate composition (i.e., the foaming agent A may be supplied at the point where the two compositions are mixed). The foaming agent A is added to at least one of the polyol composition and the polyisocyanate composition in a ratio of 0.01 to 4 parts by mass per 100 parts by mass of polyol in the polyol composition. If the amount of foaming agent A added is less than 0.01 parts by mass, the miscibility between the polyol composition and the polyisocyanate composition decreases. If the amount of foaming agent A added exceeds 4 parts by mass, it tends to adversely affect the foaming properties. From this viewpoint, the amount of foaming agent A added is preferably 0.1 to 3 parts by mass, more preferably 0.2 to 2 parts by mass, per 100 parts by mass of polyol. After adding foaming agent A, the polyol in the polyol composition reacts with the polyisocyanate in the polyisocyanate composition, causing foaming and curing to form a polyurethane foam.

[0077] In the present invention, when mixing the polyol composition and the polyisocyanate composition, and then foaming and curing them, various known methods for producing polyurethane foam can be applied. For example, various methods such as coating, injection, and spraying can be applied. Specifically, these include a method of applying a polyurethane composition, which is a mixture of a polyol composition and a polyisocyanate composition, to a substrate and allowing it to foam and harden; a method of injecting the polyurethane composition into a structure having a cavity and allowing it to foam and harden; and a method of spraying the polyurethane composition onto a substrate. For spraying, a spraying device equipped with a carbon dioxide supply device can be used. Specifically, this can be carried out by adjusting the temperature of the polyol composition and polyisocyanate composition in separate containers within the spraying device, supplying foaming agent A to either composition using a carbon dioxide supply device, then causing the two compositions to collide and mix at the tip of a spray gun, and finally atomizing the mixture with air pressure. [Examples]

[0078] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The components used in the examples and comparative examples are shown below.

[0079] <Polyol> (A-1) Polyester polyol (manufactured by Kawasaki Chemical Industries, Ltd., product name: Maximol RLK-087, hydroxyl value 200 mg KOH / g) (A-2) Polyester polyol (manufactured by Kawasaki Chemical Industries, Ltd., product name: Maximol RFK-505, hydroxyl value = 250 mg KOH / g) (A-3) Polyester polyol (manufactured by Kawasaki Chemical Industries, Ltd., product name: Maximol RFK-509, hydroxyl value = 200 mg KOH / g)

[0080] <Urethane catalyst> (B-1) Bismuth carboxylate salt: Bismuth 2-ethylhexanoate (manufactured by Nitto Chemical Co., Ltd., product name: Bi28), concentration 81-90% by mass (B-2) Tin carboxylate salt: Tin 2-ethylhexanoate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (B-3) Amine-based catalyst: N-methyldicyclohexylamine (manufactured by Evonik Japan, product name: Polycat 12)

[0081] <Trimerization catalyst> • Quaternary ammonium carboxylate (DABCO TMR-7, manufactured by Evonik Japan Co., Ltd.), concentration 45-55% by mass

[0082] <Foam stabilizer> (C-1) Polyoxyalkylene-based foam stabilizer (SH-193, manufactured by Toray Dow Corning Co., Ltd.)

[0083] <Foaming agent B> (D-1) HFO-1233zd(E) (Solstice LBA manufactured by Central Glass Co.) (D-2) HFO-1336mzz(Z) (Chemours Opteon 1100) water

[0084] <Foaming agent A> A mixture of liquid carbon dioxide and HFO-1234ze, manufactured by Tokyo High Pressure Yamazaki Co., Ltd., liquid CO2:HFO-1234ze = 3:7 (by weight).

[0085] <Polyisocyanate> Polyisocyanate (MDI, manufactured by Sumitomo Chemical Co., Ltd., product name: Sumijoule 44V20)

[0086] The evaluation method is as follows: <Mixability> In each example and comparative example, the polyol composition and the polyisocyanate composition were sprayed onto a slate board, and then visually observed to determine whether the two compositions were mixed. ○...It was uniformly mixed, and the mixing properties were good. △··Some unmixed portions were found. ×...There were many unmixed parts, and the mixing was poor. <Cream Time> In each example and comparative example, the time it took for the polyol composition and polyisocyanate composition to turn white after being sprayed onto a slate board (cream time) was measured and used as an indicator of initial reactivity. A shorter cream time indicates higher initial reactivity.

[0087] [Examples 1-8] On-site foam spraying device equipped with liquefied carbon dioxide supply system (manufactured by Asahi Organic Chemicals Co., Ltd., product name: Using the AYK-1000 series, polyurethane foam was formed as follows. A polyol composition was prepared by mixing the polyol, urethane catalyst, trimerizing catalyst, foam stabilizer, and blowing agent B shown in Table 1. In the flow path of the polyol composition, blowing agent A (liquid CO2 / HFO-1234ze) in the proportions shown in Table 1 was supplied to the polyol composition and mixed. Then, the polyol composition mixed with blowing agent A and a polyisocyanate composition consisting of polyisocyanate (MDI) were contact-mixed in a volume ratio of 1:1 to obtain a mixture (polyurethane composition). After contact mixing, the mixture (polyurethane composition) was continuously sprayed onto the surface of a slate board (size 900 mm x 900 mm) to produce polyurethane foam by foaming and curing.

[0088] [Comparative Example 1] Polyurethane foam was prepared in the same manner as in the examples, except that foaming agent A (liquid CO2 / HFO-1234ze) was not used.

[0089] [Comparative Example 2] Polyurethane foam was prepared in the same manner as in the examples, except that an amine-based catalyst was used instead of a metal carboxylate as the urethane catalyst.

[0090] [Table 1]

[0091] The results from each example showed that the manufacturing method of the present invention exhibits good miscibility between the polyol composition and the polyisocyanate composition, and high initial reactivity due to a short cream time. In contrast, Comparative Example 1, in which foaming agent A (liquid CO2 / HFO-1234ze) was not used, showed poor miscibility between the polyol composition and the polyisocyanate composition. Furthermore, Comparative Example 2, in which a metal carboxylate salt was not used, showed a long cream time and low initial reactivity.

Claims

1. A method for producing polyurethane foam by mixing a polyol composition containing a polyol and a catalyst with a polyisocyanate composition containing a polyisocyanate, reacting the mixture, and then foaming and curing the mixture, The catalyst comprises a metal carboxylate salt, The process includes supplying the foaming agent A in a separate system from the polyol composition and the polyisocyanate composition. The blowing agent A comprises a mixture of carbon dioxide and a hydrofluoroolefin with a boiling point of 0°C or lower. A method for producing polyurethane foam, wherein the foaming agent A is added to at least one of a polyol composition and a polyisocyanate composition in a proportion of 0.01 to 4 parts by mass per 100 parts by mass of polyol in the polyol composition, and the reaction proceeds after the addition.

2. A method for producing polyurethane foam according to claim 1, wherein the hydrofluoroolefin with a boiling point of 0°C or less is HFO-1234ze.

3. The method for producing polyurethane foam according to claim 1 or 2, wherein the metal carboxylate salt is at least one selected from the group consisting of bismuth carboxylate salts, lead carboxylate salts, tin carboxylate salts, and zinc carboxylate salts.

4. A method for producing polyurethane foam according to any one of claims 1 to 3, wherein the metal carboxylate salt is a bismuth carboxylate salt.

5. A method for producing polyurethane foam according to any one of claims 1 to 4, wherein the carbon dioxide contained in the blowing agent A is supercritical, subcritical, or liquid carbon dioxide.

6. A method for producing polyurethane foam according to any one of claims 1 to 5, wherein the polyol composition contains foaming agent B.

7. The method for producing polyurethane foam according to claim 6, wherein the blowing agent B contains a hydrofluoroolefin.

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