JP2007119580A - Method for producing polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a polyurethane foam having low resiliency and improved mechanical strength and flexibility. <P>SOLUTION: The method for producing the polyurethane foam comprises reacting a polyol component with a polyisocyanate component in the presence of a polyalkylene chain-containing compound represented by formula (I) (wherein R is a residue of an n-valent polyalkylene-polyol, an n-valent polyalkylene-ether-polyol, or an n-valent polyalkylene-ester polyol; and n is 2 or 3). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a polyurethane foam. More specifically, the present invention relates to a method for producing a polyurethane foam that can be suitably used as a cushioning material used for, for example, a shoe sole, an automobile, other vehicles, furniture, bedding, and the like.

  Polyurethane foam is widely used for a wide variety of applications such as heat insulating materials, cushions, and shoe soles. Among polyurethane foams, especially in the field of semi-rigid polyurethane foams used for shoe soles, etc., it has mechanical strength to ensure its function as a shoe sole, etc., has excellent flexibility and low resilience. A polyurethane foam is desired.

  In recent years, as a rigid foam that can be applied to vibration absorbing materials and shock absorbing materials, a urea elastic rigid material obtained by foaming and curing a main component composed of polyisocyanate and an aromatic diamine composed of an aromatic diamine oligomer and an aromatic diamine compound. Forms have been proposed (see, for example, Patent Document 1).

  However, this polyurea elastic rigid foam does not have mechanical strength, good flexibility and low resilience for ensuring the function as a shoe sole or the like.

JP 2003-2946 A

  An object of the present invention is to provide a method for producing a polyurethane foam having low impact resilience and improved mechanical strength and flexibility.

  The present invention is directed to general formula (I):

(In the formula, R represents a residue of an n-valent polyalkylene polyol, an n-valent polyalkylene ether polyol or an n-valent polyalkylene ester polyol, and n represents 2 or 3)
The present invention relates to a method for producing a polyurethane foam in which a polyol component and a polyisocyanate component are reacted in the presence of a polyalkylene chain-containing compound represented by the formula:

  According to the method for producing a polyurethane foam of the present invention, a polyurethane foam having low rebound resilience and excellent in mechanical strength and flexibility can be obtained.

  In the production method of the present invention, a polyol component and a polyisocyanate component are reacted in the presence of a polyalkylene chain-containing compound represented by the general formula (I) (hereinafter simply referred to as a polyalkylene chain-containing compound). There is one feature. In the present invention, since the means for reacting the polyol component and the polyisocyanate component in the presence of the polyalkylene chain-containing compound is employed in this way, it has low rebound resilience, mechanical strength such as tensile strength, and the like. A polyurethane foam excellent in flexibility indicated by elongation can be obtained.

  In the polyalkylene chain-containing compound, a residue of an n-valent polyalkylene polyol, an n-valent polyalkylene ether polyol or an n-valent polyalkylene ester polyol is shown. n represents 2 or 3. In addition, the polyalkylene unit in these polyols described above may contain an unsaturated bond.

  The hydroxyl value of the residue of the n-valent polyalkylene polyol, n-valent polyalkylene ether polyol or n-valent polyalkylene ester polyol is preferably 50 to 200 mg KOH from the viewpoint of adjusting the viscosity of the polyol component and maintaining flexibility. / G, more preferably 80 to 150 mg KOH / g. The hydroxyl value is a value measured based on JIS K 0070.

  The polyalkylene chain-containing compound can be easily prepared by, for example, a method of reacting a polyol and paranitrobenzoic acid chloride and then reducing a nitro group, a method of reacting a polyol and an aminobenzoic acid alkyl ester, or the like. .

  Examples of the polyol used in preparing the polyalkylene chain-containing compound include polyether polyols such as polytetramethylene ether glycol, polypropylene ether glycol, ethylene oxide-propylene oxide copolymer glycol, polyethylene adipate polyol, and polybutylene adipate. Examples include lactone polyester polyols derived from polyols, ε-caprolactone, γ-butyrolactone, polyester polyols obtained by reacting 3-methylpentanediol and adipic acid, polybutadiene polyols, and the like.

  The polyalkylene chain-containing compound generally has an amino group as a terminal group as represented by the general formula (I), but may have a hydroxyl group at one or both terminals. In addition, an amide group may be included in a part of the main chain of the polyalkylene chain-containing compound.

  The polyalkylene chain-containing compound can be easily obtained commercially. As a typical example of the polyol used when preparing the polyalkylene chain-containing compound, a product name: Versaring P-650 (polyol molecular weight: manufactured by Air Products and Chemical Co., Ltd. using polytetramethylene ether glycol as a raw material) 650), Bersering P-1000 (polyol molecular weight: 1000), etc .; manufactured by Ihara Chemical Industry Co., Ltd., trade name: Elastomer 1000 (polyol molecular weight: 1000), and Ihara Chemical Industry Co., Ltd. modified to a low melting point ), Trade name: Porea SL-100A (molecular weight of polyol: 1000), and the like.

  Representative examples of suitable polyalkylene chain-containing compounds include aminobenzoates having amino groups at both ends, polytetramethylene oxide-di-p-aminobenzoate, and the like.

  The amount of the polyalkylene chain-containing compound and the polyol component (polyol component used in the production of the polyurethane foam) is 0.05 to 0.3, preferably 0.1 to 0.1. It is preferable to adjust so that it may become 0.25.

  The polyol component used for the production of the polyurethane foam contains a polyol. The polyol is at least one selected from the group consisting of a polyether polyol having two or more hydroxyl groups (hereinafter referred to as polyether polyol), a polymer polyol based on polyether polyol (hereinafter referred to as polymer polyol), and a polyester polyol. It is preferable that

  Examples of the polyether polyol include ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, glycerin, trimethylolpropane, 1,2,6-hexanetriol, and pentaerythritol. Examples include polyether polyols and polyoxytetramethylene glycols obtained by addition polymerization of alkylene oxides to polyhydric alcohols.

  Representative examples of polyether polyols include polyoxypropylene polyols in which ethylene oxide is added to the terminal hydroxyl groups of polyoxypropylene polyol, the molecular weight per hydroxyl group of 1500 or more, and the molecular weight of 1000 or more obtained by ring-opening polymerization of tetrahydrofuran. And polyoxytetramethylene glycol and mixtures thereof.

  Typical examples of the polymer polyol include those in which polymer fine particles obtained by polymerizing a polymerizable unsaturated group-containing monomer are dispersed in a polyether polyol. This is, for example, a method of mixing and dispersing polymer fine particles obtained by polymerizing a polymerizable unsaturated group-containing monomer and a polyether polyol, and the polymerizable unsaturated group-containing monomer in the polyether polyol. By polymerizing, polymer fine particles obtained from the polymerizable unsaturated group-containing monomer can be produced and produced by a method of dispersing in a polyether polyol. Among these methods, the latter method is preferable because a polymer polyol in which polymer fine particles are uniformly dispersed in the polyether polyol can be easily obtained.

  Examples of the polymerizable unsaturated group-containing monomer include styrene; acrylonitrile; alkyl methacrylate having 1 to 4 carbon atoms such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate; glycidyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, and the like. Examples thereof include alkyl acrylates having 1 to 4 carbon atoms in the alkyl group; glycidyl acrylate, etc. These monomers can be used alone or in admixture of two or more.

  Examples of the polyester polyol include polyhydric alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, neopentyl glycol, trimethylolpropane, phthalic acid, maleic acid, malonic acid, succinic acid, and adipic acid. And a condensate with a polybasic acid such as terephthalic acid having a hydroxyl group at the terminal.

  Among the polyol components, polyether polyol is preferable from the viewpoint of achieving both soft and good feel and low resilience.

  The average functional group number of the polyol is preferably 2-6. The hydroxyl value of the polyol is preferably 15 to 600 mgKOH / g, more preferably 20 to 550 mgKOH / g, and still more preferably 30 to 500 mgKOH / g, from the viewpoint of increasing the crosslink density and increasing the foam strength. In addition, the hydroxyl value of a polyol component is a value when calculated | required based on JISK0070.

  The polyol is preferably a polyol having an average functional group number of 2 to 3 from the viewpoints of mechanical strength, imparting flexibility and dimensional stability. The content of the polyol having an average functional group number of 2 to 3 in the polyol component is preferably 60 to 100% by weight, more preferably 70 to 100% by weight. The polyol is preferably a polyol having an average functional group number of 4 to 6 from the viewpoint of imparting low impact resilience and dimensional stability. The content of the polyol having an average functional group number of 4 to 6 in the polyol component is preferably 1 to 20% by weight, more preferably 5 to 15% by weight.

  If necessary, the polyol component can be used as a polyol mixture together with other components such as a catalyst described later. The content of the polyol component in the polyol mixture is preferably 80% by weight or more, more preferably 85% by weight or more, from the viewpoint of improving mechanical strength, imparting flexibility and improving dimensional stability.

  A typical example of the polyisocyanate component used in the production of the polyurethane foam includes an isocyanate prepolymer.

  The isocyanate prepolymer is obtained by stirring and reacting a polyol and an excess amount of a polyisocyanate monomer by a conventional method.

  Specific examples of the polyisocyanate monomer include tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, polymethylene polyphenyl diisocyanate, 3, 3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, etc. Polyisocyanate components, modified products thereof such as carbodiimide modified products, etc., which may be used alone or in combination of two or more. Can. Among these, 4,4'-diphenylmethane diisocyanate or the combined use of 4,4'-diphenylmethane diisocyanate and a modified carbodiimide thereof is preferable.

  Among the isocyanate prepolymers, an isocyanate prepolymer obtained by using 4,4'-diphenylmethane diisocyanate and a carbodiimide modification of 4,4'-diphenylmethane diisocyanate is preferable from the viewpoint of securing sufficient strength.

  In addition, 4,4'-diphenylmethane diisocyanate may be mixed in the isocyanate prepolymer obtained by using the carbodiimide modified product of 4,4'-diphenylmethane diisocyanate.

  When preparing an isocyanate prepolymer, an additive may be added as necessary.

  Examples of additives include additives used as necessary when preparing polyester polyols, acidic gases such as hydrogen chloride gas and sulfurous acid gas, acetyl chloride to prevent the isocyanate prepolymer from self-polymerizing. An isocyanate self-polymerization inhibitor such as acid chlorides such as benzoyl chloride and isophthalic acid chloride, and phosphoric acid compounds such as phosphoric acid, monoethyl phosphate, and diethyl phosphate can be used. These additives can be used alone or in admixture of two or more.

  The NCO% of the isocyanate prepolymer is preferably 10% or more, more preferably 15% or more, so that the viscosity does not increase and molding with a low-pressure foaming machine becomes difficult. In order to avoid that the measurement accuracy of the foaming machine is lowered, it is preferably 25% or less, more preferably 22% or less, and still more preferably 20% or less.

  Since the isocyanate prepolymer is liquid at 15 ° C. or higher and can be discharged even at a low pressure, it can be used for the production of polyurethane foam without any problem even at a molding temperature of 40 to 50 ° C., for example.

  The NCO% of the polyisocyanate component is preferably 10 to 25% from the viewpoint of preventing increase in liquid viscosity and storage stability of the liquid. As the polyisocyanate monomer constituting the polyisocyanate component, 4,4′-diphenylmethane diisocyanate is preferable from the viewpoint of obtaining a foam having sufficient mechanical strength.

  In the present invention, a catalyst is preferably used from the viewpoint of improving the reaction rate. The catalyst can be contained in the polyol mixture.

  Examples of the catalyst include TEDA [1,4-diazabicyclo- [2.2.2] -octane], N, N, N ′, N′-tetramethylhexamethylenediamine, N, N, N ′, N ′. -Tetramethylpropylenediamine, N, N, N ', N', N "-pentamethyldiethylenetriamine, trimethylaminoethylpiperazine, N, N-dimethylcyclohexylamine, N, N-dimethylbenzylamine, N-methylmorpholine, N -Ethylmorpholine, triethylamine, tributylamine, bis (dimethylaminoalkyl) piperazine, N, N, N ', N'-tetramethylethylenediamine, N, N-diethylbenzylamine, bis (N, N-diethylaminoethyl) adipate, N, N, N ′, N′-tetramethyl-1,3-butanediamine, N, N-dimethyl β-phenylethylamine, 1,2-dimethylimidazole, 2-methylimidazole, etc. may be used, and these may be used alone or in admixture of two or more. From the viewpoint of improvement, a tertiary amine is preferable.

  In addition to amine-based catalysts, for example, organometallic compounds such as dibutyltin dilaurate, stannous oleate, cobalt naphthenate, and lead naphthenate can be used as the catalyst.

  In producing the polyurethane foam, a foaming agent can be used. The blowing agent can be contained in the polyol mixture. As the blowing agent, water may be used alone, or water may be used in combination with hydrocarbon, chlorofluorocarbon, or hydrogenated fluorocarbon. From the viewpoint of avoiding the problem of the earth's ozone layer destruction, it is preferable to use water alone as the foaming agent. The blowing agent can be contained in the polyol mixture.

  When water is used as the foaming agent, water generally reacts with the polyisocyanate component to form a strong hard segment. However, the density of the polyurethane foam is lowered due to the influence of carbon dioxide generated by the reaction between the polyisocyanate component and water. Therefore, the amount of water as the blowing agent is preferably 0.3 to 2 parts by weight, more preferably 0.5 to 1 part with respect to 100 parts by weight of the total amount of the polyalkylene chain-containing compound and the polyol component. 0.8 parts by weight, more preferably 0.8 to 1.6 parts by weight.

  In the present invention, chain extenders, silicone-based foam stabilizers, pigments, antioxidants, yellowing inhibitors, and the like can be used as additives. These additives can be contained in the polyol mixture.

  As the chain extender, a compound having a number average molecular weight of 1000 or less and having two or more active hydrogens in the molecule can be used.

  Typical examples of chain extenders include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, methylpentanediol, 1,6-hexanediol, trimethylolpropane, glycerin, pentaerythritol. Modification of polyhydric alcohols such as diglycerin, dextrose and sorbitol, aliphatic polyamines such as ethylenediamine and hexamethylenediamine, aromatic polyamines, alkanolamines such as diethanolamine, triethanolamine and diisopropanolamine These may be used alone or in combination of two or more.

  Suitable chain extenders include ethylene glycol, diethylene glycol, 1,4-butanediol, pentaerythritol, modified products thereof and the like having a number average molecular weight of 1000 or less.

  The mixing ratio of the polyol component and the polyisocyanate component is preferably adjusted so that the isocyanate index is preferably 80 to 110, more preferably 85 to 105, and still more preferably 90 to 100.

  As a method for producing a polyurethane foam, for example, a polyol component, a catalyst, a foaming agent, an additive and the like are mixed and stirred in advance, and the resulting polyol mixture and the polyisocyanate component are mixed and stirred by a molding machine. The method of injecting into a foam and making it foam is mentioned. More specifically, for example, a polyol component, a catalyst, a foaming agent, an additive, and the like are mixed and stirred using a tank or the like, and the resulting polyol mixture is adjusted to about 40 ° C., and then automatically mixed injection type foaming. Examples thereof include a method of mixing a polyol mixture and a polyisocyanate component using a foaming machine such as an automatic mixing type injection foaming machine, reacting and foaming.

The density of the polyurethane foam thus obtained, from the viewpoint of securing sufficient mechanical strength and dimensional stability, 0.1 g / cm ³ or more, preferably 0.1 to 0.6 g / cm ^3, more preferably 0. It is 2-0.6 g / cm < ³ >, More preferably, it is 0.3-0.55 g / cm < ³ >.

Examples 1 to 3 and Comparative Example 1
Polytetramethylene oxide-di-p-aminobenzoate (produced by Ihara Chemical Industry Co., Ltd., trade name: Elastomer 1000P, functional group number: 2, as a polyol component and a polyalkylene chain-containing compound so as to have the composition shown in Table 1. Amine value: 86.1 mgKOH / g], chain extender (ethylene glycol), catalyst (triethylenediamine), foaming agent (water), silicone foam stabilizer [manufactured by Toray Dow Corning Co., Ltd., trade name: SH193] And a pigment [Nippon Pigment Co., Ltd., trade name: NV-7-478] were mixed to prepare a polyol mixture.

As the polyisocyanate component, product name: EDIPFORM B-6106M (NCO%: 16%) manufactured by Kao Corporation is used, and the blending ratio of the polyol mixture and the polyisocyanate component is expressed by the formula:
[Isocyanate index]
= [Amount of isocyanate actually used]
÷ (isocyanate amount stoichiometrically equivalent to polyol component)
× 100
It adjusted so that the isocyanate index calculated | required based on might become the value shown in Table 1.

  The polyol mixture and the polyisocyanate component were charged into an automatic mixing type injection foaming machine (manufactured by Polyurethane Engineering, model: MU-203S, model number: 6-018), mixed at a temperature of 35 to 45 ° C., and the resulting mixture was molded. A test sheet made of a polyurethane foam of 10 mm × 100 mm × 300 mm was prepared by charging into a mold having a temperature of 45 to 55 ° C. (with a silicone release agent applied to the inner surface) and foaming under the following molding conditions.

〔Molding condition〕
・ Reactivity: Cream time 5-15 seconds ・ Demolding time: 5.5-6.5 minutes

In addition, the abbreviation of a polyol component means the following.
<Polyol a1>
Polypropylene glycol [manufactured by Asahi Glass Urethane Co., Ltd., trade name: preminol 5005, functional group number: 2, hydroxyl value: 28 mgKOH / g, number average molecular weight: 4000, unsaturation degree 0.02 meq / g]

<Polyol a2>
Polypropylene triol [Asahi Glass Urethane Co., Ltd., trade name: Exenol 820, functional group number: 3, hydroxyl value: 34 mg KOH / g, number average molecular weight: 4900, unsaturation degree 0.06 meq / g]

<Polyol a3>
Pentaerythritol polyol (manufactured by Sanyo Chemical Industries, Ltd., trade name: Sanniks HD-402, functional group number: 4, hydroxyl value: 400 mgKOH / g, number average molecular weight: 550)

  Next, the physical properties of the produced test sheet were examined according to the following method. The results are shown in Table 2.

(1) Hardness The hardness of the test sheet surface was measured at 25 ° C. with an Asker C hardness tester.

(2) Density The test sheet (100 mm × 300 mm × 10 mm) was weighed and divided by a volume of 300 cm ³ .

(3) Tensile strength and elongation Using a dumbbell No. 2 test piece punched from a test sheet, the tensile strength and elongation were measured according to JIS K6251.
In addition, it shows that it is excellent in a softness | flexibility, so that elongation is high.

(4) Rebound resilience This was measured according to JIS K6255 using a test piece having a diameter of 32 mm (thickness 10 mm) punched from the test sheet.

  From the results shown in Table 2, the polyurethane foam obtained in each example is superior to the polyurethane foam obtained in Comparative Example 1 and has excellent tensile strength and low rebound resilience. Recognize.

  The polyurethane foam obtained by the production method of the present invention is excellent in tensile strength and flexibility and has a low rebound resilience, so that it is used for, for example, shoe soles, automobiles and other vehicles, furniture, bedding and the like. It can be suitably used as a cushion material or the like.

Claims (3)

Formula (I):

(In the formula, R represents a residue of an n-valent polyalkylene polyol, an n-valent polyalkylene ether polyol or an n-valent polyalkylene ester polyol, and n represents 2 or 3)
A process for producing a polyurethane foam in which a polyol component and a polyisocyanate component are reacted in the presence of a polyalkylene chain-containing compound represented by the formula:   The process according to claim 1, wherein the hydroxyl value of the n-valent polyalkylene polyol, n-valent polyalkylene ether polyol or n-valent polyalkylene ester polyol is 50 to 200 mgKOH / g.   The production method according to claim 1 or 2, wherein a weight ratio of the polyalkylene chain-containing compound and the polyol component (polyalkylene chain-containing compound / polyol component) is 0.05 to 0.3.