JP2009057485A - Method of manufacturing polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing polyurethane foam having sufficient strength, capable of holding hardness and bending resistance and free from the occurrence of surface void to be excellent in surface appearance with dimensional stability, wear resistance and solvent resistance even when low density polyurethane foam is molded using a mold having a complicated design. <P>SOLUTION: In the manufacturing the polyurethane foam by the reaction of (1) a polyol-containing composition containing a polyol component, a chain extender, a catalyst, water, a silicone based antifoaming agent and silicon-containing inorganic powder with (2) a polyisocyanate compound, the polyol component comprises a bi-functional polyether based polyol B obtained from a compound having two active hydrogen-containing group and containing a polyoxy propylene based glycol A having ≤0.06 meq/g unsaturation degree and a tri-functional polyoxy propylene based polyol C obtained from a compound having three active hydrogen-containing group and having ≤0.06 meq/g unsaturation degree, wherein the weight ratio (polyether based polyol B/polyoxy propylene based polyol C) is 2.0-3.5 and the density of the molding is 0.2-1.0 g/cm<SP>3</SP>. <P>COPYRIGHT: (C)2009,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 polyurethane foam for shoe soles.

  Polyether polyurethane is superior in hydrolysis resistance compared to polyester polyurethane, so it is used for the soles of men's shoes that are used for a long time. It is inferior to the characteristic. Particularly in the case of a low density sole, it is difficult to put it to practical use because the strength of the final product is insufficient not only during foam molding.

  On the other hand, Patent Document 1 discloses a production method using a polyoxypropylene-based polyol having an unsaturation degree of a specific value or less. Patent Document 2 discloses a production method using a polyol component containing polyoxypropylene glycol and polyoxypropylene polyol in a specific weight ratio.

  On the other hand, the inner surface shape and design of molds used when manufacturing polyurethane foam for shoe soles are complicated by market demands, and the difficulty of design reproducibility increases due to the low density of polyurethane foam. However, defects such as air chipping, pinholes, surface voids, etc. are likely to occur on the surface of the obtained molded product.

In the method of Patent Document 3, a polyurethane foam free from surface voids can be obtained by performing a reaction between a polyol component and an isocyanate component in the presence of a silicone-based antifoaming agent and a silicon-containing inorganic powder.
JP 2000-191741 A JP 2000-273141 A JP 2005-298760 A

  However, in the methods described in Patent Documents 1 and 2, a polyurethane foam having excellent strength can be obtained. However, when molding is performed using a mold having a complicated design, air chips and surface voids are formed on the surface of the obtained molded product. It tends to occur. Moreover, even if the polyurethane foam which is excellent in surface shape is obtained by the method described in Patent Document 3, the strength thereof is not sufficient.

  The problem of the present invention is that even when a low-density polyurethane foam is molded using a mold having a complicated design, sufficient strength, hardness and bending resistance are maintained, and dimensional stability and abrasion resistance are maintained. Another object of the present invention is to provide a method for producing a polyurethane foam excellent in surface appearance without generation of surface voids in addition to solvent resistance. Especially, an object of this invention is to provide the manufacturing method of the polyurethane foam which can be used conveniently as a polyurethane foam for shoe soles.

The present invention relates to a polyurethane foam in which (1) a polyol-containing composition comprising a polyol component, a chain extender, a catalyst, water, a silicone-based antifoaming agent and a silicon-containing inorganic powder, and (2) a polyisocyanate compound are reacted. A bifunctional polyether containing a polyoxypropylene glycol A having a degree of unsaturation of 0.06 meq / g or less, wherein the polyol component is obtained from a compound having two active hydrogen-containing groups. A trifunctional polyoxypropylene polyol C obtained from a compound polyol B and a compound having three active hydrogen-containing groups and having an unsaturation degree of 0.06 meq / g or less. polyether polyol B / polyoxypropylene polyol C) is 2.0 to 3.5 the method of manufacturing a polyurethane foam density of 0.2 to 1.0 g / cm ³ On.

  By the production method of the present invention, even a low-density polyurethane foam having a complicated design has high foam strength, excellent bending resistance, dimensional stability, abrasion resistance, solvent resistance, and surface A polyurethane foam without voids can be obtained.

  The method for producing the polyurethane foam of the present invention comprises (1) a polyol-containing composition containing a polyol component, a chain extender, a catalyst, water, a silicone-based antifoaming agent and a silicon-containing inorganic powder, and (2) a polyisocyanate compound. In which the polyol component contains a bifunctional polyether polyol B having a low degree of unsaturation and a trifunctional polyoxypropylene polyol C having a low degree of unsaturation in a specific weight ratio. And it has the big characteristic in using together such a polyol component, a silicone type antifoamer, and a silicon-containing inorganic powder. In the present invention, a polyol compound having a low degree of unsaturation is used. Since such a polyol compound has a low monool content, the molded polyurethane resin has a higher molecular weight, and the tensile strength and tear of the foam are increased. A polyurethane foam excellent in mechanical strength such as strength can be obtained.

  Since both the bifunctional polyether polyol B (hereinafter referred to as PPG-B) and the trifunctional polyoxypropylene polyol C (hereinafter referred to as PPG-C) have a large number of repeating units of the oxypropylene chain. In the obtained polyurethane foam, it works effectively as a soft segment and plays a role of imparting good elongation characteristics and elasticity. Moreover, PPG-B has the effect which was excellent in foam strength, abrasion resistance, and bending resistance, and PPG-C was excellent in dimensional stability and solvent resistance. In Patent Document 2, in combination with PPG-B and PPG-C in a weight ratio of 4 to 100 from the viewpoint of dimensional stability, solvent resistance, flex resistance, and wear resistance, An excellent polyurethane foam for use in shoe soles has been obtained.

  However, in recent years, as the demand for molding using a mold having a complicated design increases, the molded product obtained when PPG-B and PPG-C are used in the range of 4 to 100 by weight ratio is Although the strength is sufficient, it has been found that problems such as air chipping and surface voids occur on the surface. Therefore, as a result of examining the poor surface shape when the present inventors used PPG-B and PPG-C together, the relationship between the composition of the polyol component used and the state control method of the bubbles in the foaming / curing process, It is important to use together a polyol component having a composition in a very limited range in which PPG-B and PPG-C are in a weight ratio of 2.0 to 3.5, and a silicone-based antifoaming agent and silicon-containing inorganic powder. It turned out to be.

  The method for producing the polyurethane foam of the present invention comprises (1) a polyol-containing composition containing a polyol component, a chain extender, a catalyst, water, a silicone-based antifoaming agent and a silicon-containing inorganic powder, and (2) a polyisocyanate compound. React.

  The polyol component contains PPG-B and PPG-C in a weight ratio in the range of 2.0 to 3.5.

  PPG-B contains polyoxypropylene glycol A (hereinafter referred to as PPG-A) having a degree of unsaturation of 0.06 meq / g or less using a compound having two active hydrogen-containing groups as a starting material. . PPG-A is a compound having two active hydrogen-containing groups as a starting material, and one or more alkylene oxides in which propylene oxide is essential using a catalyst such as a double metal cyanide such as zinc hexacyanocobaltate. The ring-opening addition reaction is carried out randomly or in a block, preferably in a block manner, and the resulting compound having two active hydrogen-containing groups is randomly or blocked, preferably ethylene oxide, at the molecular ends of the compound. Can be manufactured by a method of adding a block as a block. In the present specification, the “active hydrogen-containing group” means a functional group containing active hydrogen.

  Examples of the compound having two active hydrogen-containing groups include dihydric alcohol, dihydric phenol, amine having two secondary amino groups, monoalkyl dialkanolamine having two hydroxyl groups, and the like. 2-9 carbon atoms such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol And alkylene glycol, xylylene glycol, hydroquinone, bisphenol A and other aromatic glycols, alkyldiethanolamine, dimethylolurea, and modified products thereof. These can be used alone or in admixture of two or more.

  PPG-C can be produced by the same method as PPG-A, except that a compound having three active hydrogen-containing groups is used as a starting material.

  Examples of the compound having three active hydrogen-containing groups include polyhydric alcohol having three hydroxyl groups, polyhydric phenol having three hydroxyl groups, dialkanolamine having two hydroxyl groups and one amino group, and the like. Specific examples include glycerin, trimethylolpropane, triethanolamine, and diethanolamine. These can be used alone or in admixture of two or more, among which glycerin and trimethylolpropane are preferred.

  Examples of the alkylene oxide that undergoes ring-opening addition reaction to a compound having two active hydrogen-containing groups or a compound having three active hydrogen include ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, and styrene oxide. Is mentioned. Among these, propylene oxide is used alone, or propylene oxide is a main component (50% by weight or more, preferably 65% by weight or more, more preferably 80% by weight or more), and this and other alkylene oxides. Are preferably used together so as to be a random copolymer or a block copolymer, and more preferably used together so as to be a block copolymer. Specifically, it is preferable to prepare a polyol by subjecting propylene oxide alone to a ring-opening addition reaction and then subjecting the end group to a block-opening addition reaction with ethylene oxide in a block manner.

  The hydroxyl value of PPG-A is preferably 18 to 35 mg KOH / g, more preferably 20 to 30 mg KOH / g, from the viewpoint of foam strength. The hydroxyl value of PPG-C is from the viewpoint of foam strength and elongation characteristics. Preferably it is 11-35 mgKOH / g, More preferably, it is 15-30 mgKOH / g. The hydroxyl value is a value measured according to JIS K1557.

  When the content of oxyethylene groups existing in and at the ends of PPG-A and PPG-C is increased, the hydrophilicity is increased and water is attracted. Hydrolysis resistance, which is a characteristic of polyether polyurethane foams Therefore, the content of oxyethylene groups in PPG-A and PPG-C is preferably 35% by weight or less, more preferably 20% by weight or less, respectively, from the viewpoint of the reactivity of terminal hydroxyl groups. To 5 wt% or more, more preferably 8 wt% or more.

  The degree of unsaturation of PPG-A and PPG-C is 0.06 meq / g or less, preferably 0.03 meq / g or less from the viewpoint of achieving high molecular weight as a polyurethane resin, and preferably 0.015 meq / g or less from the viewpoint of market price. Over meq / g. In the present specification, the degree of unsaturation is measured based on ASTM D2849-69. Note that PPG-A and PPG-C may be prepared by mixing several polyoxyalkylene polyols as long as the degree of unsaturation, the hydroxyl value, and the content of oxyethylene groups are within the above ranges. .

  In addition to PPG-A, other polyol compounds may be appropriately contained in PPG-B as long as the effects of the present invention are not impaired. As another polyol compound, it is preferable to contain PTMG modified with polyoxytetramethylene glycol (hereinafter referred to as PTMG) or ε-caprolactone from the viewpoint of further improving foam strength and wear resistance.

  The hydroxyl value of PTMG is preferably 37 to 160 mgKOH / g, more preferably 50 to 120 mgKOH / g, from the viewpoint of exerting sufficient elasticity as a soft segment of the oxytetramethylene chain and handling workability.

  The content of PPG-A in PPG-B is preferably from 30 to 100% by weight, more preferably from 50 to 100% by weight, from the viewpoint of improving the elongation characteristics and elasticity and obtaining a polyurethane foam excellent in strength. Preferably it is 70 to 100% by weight

  The content of PTMG in PPG-B is preferably 0 to 70% by weight, more preferably 0 to 50% by weight, and still more preferably 0 to 0% from the viewpoint of further improving properties such as foam strength and manufacturing cost. 30% by weight.

  The weight ratio of PPG-B and PPG-C in the polyol component (PPG-B / PPG-C) is 2.0 to 3.5, preferably 2.2 to 3.0, from the viewpoint of comprehensive evaluation such as solvent resistance and appearance design. is there.

  The total amount of PPG-B and PPG-C in the polyol component is preferably 80 to 100% by weight, more preferably 90 to 100% by weight, and still more preferably, from the viewpoint of obtaining a polyurethane foam that is inexpensive and excellent in strength. It is substantially 100% by weight.

  In the present invention, polymer polyols based on PPG-A and PPG-C can also be used as the polyol component. Typical examples thereof include those in which polymer fine particles obtained by polymerizing a polymerizable unsaturated-containing monomer are dispersed in PPG-A and PPG-C.

  Even when the silicone-based antifoaming agent and silicon-containing inorganic powder in the present invention are molded using a mold having a complicated shape, design, etc., it is possible to produce a polyurethane foam that does not generate surface voids. Used together because it can.

  In general, when an antifoaming agent is used for polyurethane foam, it is considered that the closed cell property becomes strong, so that the polyurethane foam may be shrunk. However, a silicone-based antifoaming agent and a silicon-containing inorganic powder are considered. When used together, surface voids can be reduced without causing shrinkage in the polyurethane foam.

  As the silicone-based antifoaming agent, polysiloxane composed only of hydrophobic structural units and modified products thereof, and polysiloxane composed only of hydrophobic structural units have short-chain hydrophilic structural units with an average addition mole number of 10 or less. Those added with are preferred. Examples of the modified body include compounds such as fluorosilicone in which a part of a polysiloxane skeleton composed of only hydrophobic structural units is modified with fluorine or the like. As the short-chain hydrophilic structural unit, an alkylene oxide adduct having an average addition mole number of hydrophilic groups such as ethylene oxide and propylene oxide of preferably 10 or less, more preferably 5 or less (the carbon number of alkylene is 2 to 4). ).

  The surface tension of the silicone antifoam used in the present invention is preferably 21 mN / m or less from the viewpoint of reducing surface voids. In addition, in this specification, the surface tension of a silicone type antifoamer is a value when measured by Showa Interface Chemical Co., Ltd., brand name: FACE CNVP-Z.

  Examples of the silicone antifoaming agent include an oil type, a solution type, a compound type, and an emulsion type. Among these, an oil type and a compound type are preferable.

  Specific examples of silicone antifoaming agents include polysiloxanes such as chain polysiloxanes and cyclic polysiloxanes, and fluorosilicones.

  Examples of suitable chain polysiloxanes include those of formula (I):

(In the formula, each R ¹ independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and n represents 1 to 10)
And a modified product thereof having a surface tension of 21 mN / m or less. Among R ¹ is hydrogen atom, methyl group and phenyl group are preferable. A smaller n is preferable because the surface tension becomes smaller. Preferred n is an integer of 1 to 4.

Among the chain polysiloxanes represented by the formula (I) and modified products thereof, dimethylpolysiloxane or modified products thereof in which R ¹ is a methyl group, each having a surface tension of 21 mN / m or less Is more preferable.

  Examples of the commercially available chain polysiloxane represented by the formula (I) or a modified product thereof are manufactured by Shin-Etsu Chemical Co., Ltd., product number: KF-96, manufactured by Toray Dow Corning Silicone Co., product number: SH-200, manufactured by GE Toshiba Silicones Co., Ltd., product number: TSF-451, and the like can be mentioned, but the present invention is not limited to such examples.

  Examples of suitable cyclic polysiloxanes include those of formula (II):

Wherein R ² is independently a hydrocarbon group having 1 to 18 carbon atoms, R ³ is each independently a hydrocarbon group having 1 to 18 carbon atoms or an organic substituent, and x and y are 1 or an integer greater than 1 and the sum of x and y is 3 to 8)
Or a modified product thereof having a surface tension of 21 mN / m or less.

Among R ² , an alkyl group having 1 to 18 carbon atoms and an aryl group having 6 to 12 carbon atoms are preferable, a methyl group, an ethyl group, and a phenyl group are more preferable, and a methyl group is further preferable.

In R ³ , the alkyl group having 1 to 18 carbon atoms, the aryl group having 6 to 12 carbon atoms, the oxyalkylene chain is an oxymethylene group or an oxyethylene group, and the added mole number of the oxyalkylene group is 1 to 8. A (poly) oxyalkylenealkyl group having 2 to 16 carbon atoms in total and an aminoalkyl group having 1 to 8 carbon atoms, preferably a methyl group, an ethyl group, a phenyl group, the polyoxyalkylenealkyl group and the amino group. An alkyl group is more preferred.

  Suitable fluorosilicones include those in which fluorine-containing substituents are introduced into the main chain or side chain of the linear and cyclic polysiloxanes. Examples of commercially available fluorosilicones include Shin-Etsu Chemical Co., Ltd. Product No .: FL100, manufactured by Toray Dow Corning Silicone Co., Ltd., Product No .: FS1265, manufactured by GE Toshiba Silicone Corp., Product No .: FQF501, etc., but the present invention is not limited to such examples.

  In addition, the silicone type antifoamer in this invention differs from the silicone type foam stabilizer generally used when manufacturing a polyurethane foam by the following points. That is, the silicone-based antifoaming agent used in the present invention has the above structure, whereas the silicone-based foam stabilizer is a compound having both a hydrophobic structural unit and a sufficiently large hydrophilic structural unit such as polyalkylene oxide. Different from. Silicone antifoaming agents must not dissolve uniformly in foam-forming substances, whereas silicone-based foam stabilizers dissolve uniformly in foaming substances and reduce surface tension. Both of them have completely opposite properties.

  The silicon-containing inorganic powder includes various shapes such as particles and fibers. Examples of the silicon-containing inorganic powder include talc, kaolin, silica particles, and silicone powder, and these can be used alone or in combination of two or more. Among these, silica particles and silicone powder are preferable from the viewpoint of reducing surface voids. As the silica particles, those generally used as an antifoaming agent can be suitably used. Examples thereof include Tosoh Silica Co., Ltd., product numbers: L-250 and SS-10.

  The average particle size of the silicon-containing inorganic powder is preferably 0.05 to 50 μm, more preferably 0.05 to 20 μm, from the viewpoints of surface void reduction, workability, cost, and the like. In the case of a silicon-containing inorganic powder having a shape other than a spherical shape, the average value of the length in the major axis direction and the length in the minor axis direction of one particle is the average particle size, and the numerical range of the average particle size is It means a numerical range to which the average particle diameter of particles belongs. The average particle diameter of the powder is measured by image analysis using a scanning electron microscope (SEM).

  In the present invention, from the viewpoint of reducing surface voids, a combination of a silicone-based antifoaming agent and silica particles is preferable, and a combination of a silicone-based antifoaming agent having a surface tension of 21 mN / m or less and silica particles is more preferable. . In addition, as the silicone-based antifoaming agent and the silica particles, those prepared separately as the silicone-based antifoaming agent and the silica particles may be used, or those combined may be used. Examples of those that are also used include Toray Dow Corning Silicone Co., Ltd., product number: SH5500, silica particle-containing compound type silicone, and the like.

  The total amount of the silicone-based antifoaming agent and the silicon-containing inorganic powder is preferably 0.001 to 0.5 parts by weight with respect to 100 parts by weight of the polyol component from the viewpoint of reducing surface voids without causing shrinkage in the polyurethane foam. More preferably, it is 0.001-0.3 weight part, More preferably, it is 0.01-0.3 weight part.

  The weight ratio of the silicone-based antifoaming agent to the silicon-containing inorganic powder (silicone-based antifoaming agent / silicon-containing inorganic powder) is preferably from the viewpoint of reducing surface voids without causing shrinkage in the polyurethane foam. It is 3-25, More preferably, it is 5-20, More preferably, it is 7-17.

  The polyol-containing composition contains a catalyst, a chain extender, and water in addition to the polyol component, the silicone-based antifoaming agent, and the silicon-containing inorganic powder.

  A tertiary amine is suitable as the catalyst. Examples include 1,4-diazabicyclo- (2,2,2) -octane] (hereinafter referred to as TEDA), 2-methyl-1,4-diazabicyclo [2.2.2] octane, N, N, N ′. , N′-tetramethylhexamethylenediamine, N, N, N ′, N′-tetramethylpropylenediamine, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine, N, N ′, N′-trimethylaminoethylpiperazine, N, N-dimethylcyclohexylamine, N, N-dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, triethylamine, tri Butylamine, 1,8-diazabicyclo [5.4.0] undecene-7, bis (N, N-dimethylaminoethyl) ether, 1,2-dimethylimid Examples include dazole, 1-methylimidazole, 1-isobutyl-2-methylimidazole, and the like. These catalysts can be used alone or in admixture of two or more. As catalysts other than tertiary amines, organometallic compounds such as dibutyltin dilaurate, bis (2-ethylhexanoic acid) tin, tris (2-ethylhexanoic acid) bismuth, and bis (2-ethylhexanoic acid) lead are used. You can also The amount of the catalyst is preferably 0.1 to 8 parts by weight, more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the polyol component.

  The chain extender is not particularly limited, and known crosslinking agents and chain extenders can be used. Two active hydrogen-containing groups capable of reacting with a hydroxyl group, a primary amino group, a secondary amino group, and other isocyanate groups are used. The low molecular compound etc. which have the above are mentioned. Specifically, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, trimethylolpropane, glycerin, pentaerythritol, bisphenol A Polyhydric alcohols such as alkylene oxide adducts, alkanolamines such as ethanolamine, diethanolamine, triethanolamine, and methyldiethanolamine, and polyhydric amines such as diethyltoluenediamine, ethylenediamine, and 1,6-hexanediamine. These can be used alone or in admixture of two or more. Among these, ethylene glycol is preferable from the viewpoint of adjusting the polyurethane foam to a desired hardness.

  The amount of the chain extender is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the polyol component, from the viewpoint of securing the strength and hardness of the polyurethane molded product.

  Water used in the polyol-containing composition is used as a foaming agent. The amount of water is preferably 0.1 to 1.8 parts by weight, more preferably 0.2 to 1.8 parts by weight, and still more preferably 0.25 to 1.5 parts by weight with respect to 100 parts by weight of the polyol component.

  If necessary, a foaming agent such as hydrocarbon or hydrofluorocarbon can be used together with water. However, it is preferable to use water alone from the viewpoint of environmental protection.

  Furthermore, additives such as silicone-based foam stabilizers, pigments, antioxidants, yellowing inhibitors, and antifungal agents can be added to the polyol-containing composition in an appropriate amount as necessary.

  Examples of the polyisocyanate compound in the present invention include aromatic, alicyclic, and aliphatic polyisocyanates having two or more isocyanate groups, mixtures thereof, and modified polyisocyanates obtained by modifying them. . Specifically, aromatic polyisocyanates such as tolylene diisocyanate, methylene diphenyl diisocyanate, naphthylene diisocyanate, xylylene diisocyanate, polymethylene polyphenylene polyisocyanate, hydrogenated methylene diphenyl diisocyanate, hydrogenated tolylene diisocyanate, isophorone diisocyanate, etc. Aliphatic polyisocyanates such as alicyclic polyisocyanate, hexamethylene diisocyanate, lysine diisocyanate, mixtures thereof, modified products thereof and the like. Examples of the modified products include prepolymer modified products, isocyanurate modified products, urea modified products, carbodiimide modified products, allophanate modified products, and burette modified products that are reaction products with polyols. In these, aromatic polyisocyanate and its modified body are preferable.

  As a more preferred polyisocyanate compound, a prepolymer type modified product comprising polyoxyalkylene glycol and methylene diphenyl diisocyanate and / or a modified product thereof, and a mixture of methylene diphenyl diisocyanate, or the mixture and a carbodiimide modified product are used. Of the mixture.

  The prepolymer-modified product has a structure containing a soft segment made of polyoxyalkylene glycol, and exhibits a low viscosity and mild reactivity, and thus is useful for producing a low density polyurethane foam.

  Polyoxyalkylene glycol is a method of preparing low-unsaturation PPG such as PPG-A and PPG-C, and general-purpose PPG obtained by ring-opening addition reaction of alkylene oxide with an alkali catalyst such as KOH and NaOH. It can be manufactured by the same method as the preparation method. Among the polyoxyalkylene glycols, polyoxypropylene glycols having a hydroxyl value of 56 mgKOH / g or less can be suitably used, and since the oxyalkylene chain is long, it plays a role as a soft segment in urethane foam. Works effectively and has good elongation and bending properties. Since the polyoxyalkylene glycol is reacted with polyisocyanate in advance, it is not always necessary to make the hydroxyl group primary, and ethylene oxide may or may not be added to the terminal. The prepolymer-type modified product may contain a reaction product of methylene diphenyl diisocyanate or a modified product thereof and a chain extender.

  When the polyol-containing composition and the polyisocyanate compound are reacted, the ratio of the polyol-containing composition and the polyisocyanate compound is adjusted so that the isocyanate index is preferably 80 to 110, more preferably 90 to 105. It is desirable.

  The method for producing the polyurethane foam of the present invention includes a polyol component, a catalyst, a chain extender, water, a silicone-based antifoaming agent, a silicon-containing inorganic powder and other additives previously mixed and stirred. And a method of mixing and stirring the polyisocyanate compound with a molding machine, injecting the mixture into a mold, and foaming. More specifically, the polyol-containing composition is mixed and stirred using a tank or the like, and usually adjusted to a temperature of about 40 ° C., and then foamed by an automatic mixing injection type foaming machine, an automatic mixing type injection foaming machine or the like. Examples thereof include a method of reacting with a polyisocyanate compound and foaming using a machine.

  There is no particular limitation on the material of the mold. Examples thereof include iron, stainless steel, copper, aluminum, aluminum alloy, epoxy resin, phenol resin, and the like. Moreover, there is no limitation in particular also about the inner surface shape of a shaping | molding die, What is necessary is just to have the shape corresponding to the shape of the target molded object, and is arbitrary.

  When molding is performed, it is preferable that a mold release agent is previously attached to the inner surface of the mold by an ordinary method such as application or spraying in order to improve the mold release property. Typical examples of the mold release agent include silicone-based mold release agents, mineral oil, paraffin wax, and the like, but the present invention is not limited to such examples.

  According to the present invention, even when a mold having a complicated shape, design, or the like, for example, a mold having an internal shape corresponding to the shape of a shoe sole, is used, there is no generation of surface voids. Polyurethane foams such as

  The polyurethane foam thus obtained has sufficient strength and hardness even when molded at low density, excellent dimensional stability, flex resistance, abrasion resistance and solvent resistance, and generation of surface voids. There is no excellent thing. Accordingly, the polyurethane foam can be suitably used as a polyurethane foam for shoe soles.

From the viewpoint of maintaining the mechanical strength of polyurethane foam and more effective in suppressing the generation of surface voids, the density of the molded product of polyurethane foam is in addition to the physical properties of shoe soles when manufacturing polyurethane foam for shoe soles. From the viewpoint of securing the heel and the comfort of the sole, it is 0.2 to 1.0 g / cm ³ , preferably 0.4 to 1.0 g / cm ³ , more preferably 0.45 to 0.8 g / cm ³ . The C hardness is preferably 35 to 90, more preferably 50 to 85, and still more preferably from the viewpoint of improving the resilience required for the shoe sole and imparting the desired hardness desired for the shoe sole. 60-80.

[Hydroxyl value of polyol compound]
The hydroxyl value is measured according to JIS K1557.

[Unsaturation degree of polyol compound]
Unsaturation is measured according to ASTM D2849-69.

〔surface tension〕
Measured using Showa Interface Chemical Co., Ltd., trade name: FACE CNVP-Z.

Examples 1-5 and Comparative Examples 1-6
Table 1 shows the proportions of chain extender (ethylene glycol), catalyst, foaming agent (water), silicone-based antifoaming agent, silicon-containing inorganic powder, silicone-based foam stabilizer and pigment based on 100 parts by weight of the polyol component. Then, it was mixed with a polyol component and homogenized using a hand mixer (trade name: UM-15, manufactured by Hitachi Koki Co., Ltd.) to prepare a polyol-containing composition.

In addition, the detail of each component described in Table 1 is as follows.
[Polyol component]
Preminol 5005: Polyoxypropylene glycol having a hydroxyl value of 28 mg KOH / g and an unsaturation degree of 0.024 meq / g obtained by sequentially adding propylene oxide and ethylene oxide to a bifunctional alcohol (product name: Preminol 5005)
Preminol 7005: Polyoxypropylene triol having a hydroxyl value of 24 mg KOH / g and an unsaturation of 0.022 meq / g obtained by sequentially adding propylene oxide and ethylene oxide to a trifunctional alcohol (Asahi Glass Urethane Co., Ltd., trade name: Preminol 7005)
Preminol 7012: Polyoxypropylene triol having a hydroxyl value of 16.8 mgKOH / g and an unsaturation degree of 0.024 eq / g obtained by sequentially adding propylene oxide and ethylene oxide to a trifunctional alcohol (Asahi Glass Urethane Co., Ltd., trade name: Preminol 7012)
Exenol 510: Polyoxypropylene glycol having a hydroxyl value of 28 mg KOH / g and an unsaturation of 0.087 meq / g obtained by sequentially adding propylene oxide and ethylene oxide to a bifunctional alcohol (product name: Exenol 510, manufactured by Asahi Glass Urethane Co., Ltd.)
Exenol 850: Polyoxypropylene triol with a hydroxyl value of 24 mgKOH / g and an unsaturation of 0.067 meq / g obtained by sequentially adding propylene oxide and ethylene oxide to a trifunctional alcohol (Asahi Glass Urethane Co., Ltd., trade name: Exenol 850)
PTMG1000: polyoxytetramethylene glycol having a hydroxyl value of 112 mg KOH / g (trade name: Poly THF 1000, manufactured by BASF)

〔catalyst〕
・ Tertiary amine catalyst (ethylene glycol solution containing 33% TEDA)

[Silicone-based antifoaming agent]
・ Dimethylpolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., product number: KF-96, surface tension: 20.9 mN / m)

[Combined silicone antifoam and silicon-containing inorganic powder]
・ Silica particle-dispersed silicone (Toray Dow Corning Silicone, product number: SH5500, silica particle-containing compound type silicone, surface tension: 20.7 mN / m)

[Inorganic powder containing silicon]
・ Silica particles (manufactured by Tosoh Silica, product number: L-250)

[Silicone-based foam stabilizer]
・ Dimethylpolysiloxane (made by Toray Dow Corning Silicone Co., Ltd., product number: SRX253, surface tension: 21.4 mN / m)

[Pigment]
White pigment (Nippon Pigment, trade name: NV-9-953)

  Next, the polyol-containing composition obtained above was placed in one tank of an injection-type low-pressure foaming machine (manufactured by KLOECKNER DESMA, product number: DESMA 583 PSA95), and its liquid temperature Was adjusted to 40 ° C., the polyisocyanate compound was placed in the other tank, and the liquid temperature was similarly adjusted to 40 ° C.

The details of the polyisocyanate compound used are as follows.
[Polyisocyanate compound]
・ Polyol-modified diphenylmethane diisocyanate (trade name: Edifice B-6106M, NCO content: 16%, manufactured by Kao Corporation)

Next, using this foaming machine, the polyol-containing composition shown in Table 1 and the polyisocyanate compound are mixed and stirred at a ratio such that the isocyanate index is 100, and a shoe sole molding having a design on a predetermined sole side surface portion is obtained. It was poured into a molding die (controlled at 50 ° C.) and foamed to mold a sole made of polyurethane foam having a molded body density of 0.60 g / cm ³ . Similarly, for the evaluation of foam properties, it was poured into a 100 mm × 300 mm × 10 mm mold (temperature controlled at 50 ° C.) and foamed to obtain a polyurethane foam having a molded body density of 0.60 g / cm ³ .

The blending ratio of the polyol-containing composition and the polyisocyanate compound is represented by the formula:
[Isocyanate index]
= [Amount of isocyanate actually used]
÷ (isocyanate amount stoichiometrically equivalent to polyol) × 100
It adjusted so that the isocyanate index calculated | required based on might become the value shown in Table 1.

  The foam characteristics of the obtained polyurethane foam were examined according to the methods of Test Examples 1 to 8 below. The results are shown in Table 1.

[Test Example 1] (Molded body density)
The weight of a polyurethane foam of 100 mm × 300 mm × 10 mm is measured and divided by a volume of 300 cm ³ .

[Test Example 2] (C hardness)
Measure with Asker C hardness tester.

[Test Example 3] (foam strength)
The strength of the entire polyurethane foam having a thickness of 10 mm is measured by the method described in JIS K 6251.

[Test Example 4] (Bend resistance)
It is measured by the method described in DIN 52243.

[Test Example 5] (Abrasion resistance)
It is measured by the method described in DIN 53516.

[Test Example 6] (Dimensional change)
The raw material is poured into an iron mold having an inner dimension of 100 mm × 300 mm × 10 mm so that the density of the molded body becomes a value shown in Table 1. After 7 minutes from the injection of the raw material, the mold is removed, and the resulting polyurethane foam is allowed to stand at room temperature (25 ° C.) for 1 day, and then the dimensional change in the longitudinal direction of the polyurethane foam is measured.

[Test Example 7] (Solvent resistance)
After molding, the obtained polyurethane foam is allowed to stand at room temperature (25 ° C.) for 1 day, the polyurethane foam tested in Test Example 6 is folded in half, and the bent portion is impregnated with trichlorethylene for 15 seconds, then taken out, and the bent portion is removed. The presence or absence of cracks is visually observed and evaluated based on the following evaluation criteria.

[Evaluation criteria for solvent resistance]
○: No crack △: No crack but solvent erosion X: Crack

[Test Example 8] (Appearance: voids A and B and comprehensive judgment)
When the voids present on the side of the sole can be confirmed by visual inspection, the surface void A is obtained, and when the visual confirmation is confirmed by the tactile sense, the surface void B is obtained. The maximum length of each void in each void is examined using a caliper. Are determined based on the following evaluation criteria.

[Evaluation criteria for void A]
○: No generation of voids ×: Generation of voids

[Evaluation criteria for void B]
○: No occurrence of voids △: Total maximum length of voids is 5mm or less ×: Total maximum length of voids exceeds 5mm

[Evaluation criteria for comprehensive judgment]
○: None of surface void A and surface void B Δ: Surface void A does not exist, and the total maximum length of surface void B is 5 mm or less ×: Cases other than the above ○ and Δ clear)

  From the above results, the polyurethane foams of Examples 1 to 5 have high foam strength as compared with the polyurethane foams of Comparative Examples 1 to 6, and have flex resistance, abrasion resistance, dimensional stability, and solvent resistance. Further, it is found that the surface voids are not generated and the appearance is excellent, and it is good in all items. On the other hand, Comparative Examples 3 and 4 in which the weight ratio of the bifunctional polyol to the trifunctional polyol exceeds 3.5 and Comparative Example 6 in which the weight ratio is 0.7 are a combination of a silicone-based antifoaming agent and a silicon-containing inorganic powder. Even if it does, a void generate | occur | produces and it turns out that it is inferior to an external appearance. Further, Comparative Example 5 in which the weight ratio of the bifunctional polyol to the trifunctional polyol is 2.3 does not use the silicone antifoaming agent and the silicon-containing inorganic powder in combination, so that voids are generated and the appearance is inferior. It has become. Therefore, in addition to using a polyol component in which the weight ratio of a bifunctional polyol and a trifunctional polyol is 2.0 to 3.5, it is possible to use a silicone-based antifoaming agent and a silicon-containing inorganic powder in combination with mechanical properties and appearance. It is suggested that it is important to achieve both.

  The polyurethane foam obtained by the present invention can be suitably used for, for example, a shoe sole.

Claims (4)

(1) A process for producing a polyurethane foam comprising reacting a polyol component, a chain extender, a catalyst, water, a silicone-based antifoaming agent and a silicon-containing inorganic powder, and (2) a polyisocyanate compound. A bifunctional polyether-based polyol B containing a polyoxypropylene-based glycol A having a degree of unsaturation of 0.06 meq / g or less, wherein the polyol component is obtained from a compound having two active hydrogen-containing groups; A trifunctional polyoxypropylene polyol C obtained from a compound having three active hydrogen-containing groups and having an unsaturation level of 0.06 meq / g or less, and a weight ratio thereof (polyether polyol) B / polyoxypropylene-based polyol C) is 2.0 to 3.5, and a method for producing a polyurethane foam having a molded body density of 0.2 to 1.0 g / cm ³ .   The production method according to claim 1, wherein the polyether-based polyol B further contains polytetramethylene ether glycol.   The production method according to claim 1 or 2, wherein the polyoxypropylene glycol A has a hydroxyl value of 18 to 35 mgKOH / g, and the polyoxypropylene polyol C has a hydroxyl value of 11 to 35 mgKOH / g.   The manufacturing method in any one of Claims 1-3 which manufactures the polyurethane foam for shoe soles.