JP2004169017A - Foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foam with sufficient strength and simultaneously having moderate elasticity and high rebound resilience. <P>SOLUTION: The foam with a storage modulus of 1.7-2.5 MPa obtained from dynamic viscoelasticity at 25°C and 10 Hz frequency, and tanδ of 0.01-0.14, a member of shoe sole made of the foam and the shoe sole having the foam with rebound resilience of 36-80%. The foam exhibits wear-out amount of 100 mg or less in DIN wear test under conditions of pressing force of 7.5 N of a disk form test piece of 18 cm diameter and 10 mm thickness to an abrasive cloth, and 100% modulus of 1.2 MPa and a polyurethane foam is manufactured by a reaction of a polyol component and a isocyanate compound. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to foams. More specifically, the present invention relates to a foam which can be suitably used as a cushioning material used for, for example, shoe soles, automobiles and other vehicles, furniture, bedding, and the like.

  Foams represented by polyurethane foams are widely used in various fields. Generally, the properties required for a foam differ depending on the purpose of use and the site of use. As properties, polyurethane foams having sufficient strength, appropriate elasticity and high rebound resilience are being developed from the viewpoint of improving safety, comfort and tactile sensation. However, a foam having sufficient strength and satisfying appropriate elasticity and high resilience simultaneously has not been obtained.

  For example, in the field of flexible polyurethane foam, a polyurethane foam having high rebound resilience is known (for example, see Patent Document 1). However, this polyurethane foam has a drawback that it does not have appropriate hardness and sufficient strength.

  Further, as a polyurethane having a high density and a high strength, a high resilience polyurethane has been proposed (for example, see Patent Document 2). However, this polyurethane has a disadvantage that it has high hardness and does not have appropriate elasticity.

JP-A-9-176276 Japanese Patent Application Laid-Open No. H10-1110025

  It is an object of the present invention to provide a foam having sufficient strength and having appropriate elasticity and high resilience at the same time.

That is, the present invention
(1) a foam having a storage elastic modulus obtained from dynamic viscoelasticity at a frequency of 10 Hz and 25 ° C. of 1.7 to 2.5 MPa and a tan δ of 0.01 to 0.14;
(2) A shoe sole member made of the foam,
(3) a shoe sole having the foam,
(4) Under the conditions that the rebound resilience is 36 to 80%, the force for pressing the test piece against the polishing cloth is 7.5N, and the test piece is a disc-shaped test piece having a diameter of 18 mm and a thickness of 10 mm, A method for producing a foam having a wear amount of 100 mg or less in a wear test and a 100% modulus of 1.2 MPa or less, and (5) a polyurethane foam in which a polyol component is reacted with an isocyanate compound, wherein the polyol component is It is a bifunctional polyol, and uses ethylene glycol and 1,4-butanediol as polyhydric alcohols as a raw material of the bifunctional polyol, and has a storage elastic modulus obtained from dynamic viscoelasticity at a frequency of 10 Hz and 25 ° C. of 1.7. To 2.5 MPa and a method for producing a polyurethane foam having a tan δ of 0.01 to 0.14.

  ADVANTAGE OF THE INVENTION The foam of this invention has sufficient intensity | strength, and it has the effect of having moderate elasticity and high rebound resilience simultaneously. Therefore, the foam of the present invention can be suitably used especially as a foam for shoe soles.

  The foam of the present invention has a storage elastic modulus of 1.7 to 2.5 MPa obtained from dynamic viscoelasticity measured at a frequency of 10 Hz and 25 ° C. based on a test method specified in JIS K 7198, In addition, since tan δ is 0.01 to 0.14, an excellent effect of having sufficient strength and having appropriate elasticity and high resilience simultaneously is exhibited.

  The present inventors have intensively studied to obtain a foam exhibiting an excellent effect of simultaneously providing a suitable elasticity and a high rebound resilience. It has been found that the elastic modulus and tan δ, which indicates the ratio of the loss elastic modulus to the storage elastic modulus, have a correlation between moderate elasticity felt by humans and high rebound resilience. That is, when the tactile sensation was evaluated by the touch finger and the storage elastic modulus, it had sufficient strength in a temperature range from -5 ° C to 40 ° C, which is a general living temperature when a person lives throughout the year. A foam having an appropriate elasticity and high resilience can be obtained when the storage elastic modulus (E ′) and tan δ when measured at 25 ° C., at a frequency of 10 Hz, and at a heating rate of 2 ° C./min. It was found that it was within a certain range. Therefore, the foam of the present invention is appropriately defined by a specific storage modulus and a specific tan δ.

  The temperature of 25 ° C. and the frequency of 10 Hz, which are the conditions at the time of the measurement of the dynamic viscoelasticity, are such that the average value of the temperature experienced by humans in daily life is about 25 ° C. This is set based on the fact that the natural frequency that the sole receives when walking, running lightly, or running at full speed while wearing shoes with the sole is 5 to 10 Hz.

  The term “moderate elasticity” as used herein means that when the foam is directly pressed and pinched at or near the tip of a fingernail or at a part where a fingertip is present, the foam does not feel as hard as a stone. It means that the body is collapsed but returns a moderate reaction force without sinking, and no fingerprint remains when the hand is released after directly pressing or stopping the pinching operation.

  The term "high rebound resilience" used herein refers to a foam having a diameter of 32 mm punched out of a sheet of foam having a thickness of 10 mm based on a rebound resilience test specified in JIS K6301 and a temperature of 25 ° C. Means that the rebound resilience measured by is 36% or more.

  Dynamic viscoelasticity is a combined behavior of viscosity and elasticity when a steady sine wave strain is applied to a foam. Dynamic viscoelasticity is determined by measuring stress to strain or strain to stress.

  It is the value of the ratio between the maximum stress and the maximum strain in dynamic viscoelasticity, and the complex elastic modulus is obtained as a vector by a complex number operation. The storage modulus (dynamic storage modulus) is the real part of the complex modulus that indicates the magnitude of the in-phase stress component when a sine wave strain of the characteristic frequency is applied. The magnitude of the stress component whose phase is advanced by π / 2 from the strain when a sine wave strain is applied is the loss elastic modulus (dynamic loss elastic modulus).

tan δ is also called a loss tangent, and the equation:
[Tan δ] = [loss elastic modulus] / [storage elastic modulus]
Is represented by tan δ is used as a measure of the energy absorption of the foam. In measuring the temperature change of dynamic viscoelasticity, the frequency at the time of measurement is kept constant, and the storage elastic modulus, loss elastic modulus and tan δ are obtained as a function of temperature. It is possible to know the transition of the foam used in the measurement from the glass state to the rubber state, the relaxation of impact energy given from the outside, and the like.

  The storage modulus (E ') is in the range of 1.7 to 2.5 MPa, preferably 1.9 to 2.5 MPa, more preferably 1.9 to 2.4 MPa, and still more preferably 2.0 to 2.35 MPa. In this case, a foam having sufficient strength, moderate elasticity and high resilience can be obtained. That is, when the storage elastic modulus (E ') is smaller than the lower limit, the foam is too soft to lower the mechanical strength, and when the storage elastic modulus (E') is larger than the upper limit, In this case, the foam becomes hard and does not have appropriate elasticity.

  When tan δ is in the range of 0.01 to 0.14, preferably 0.05 to 0.14, more preferably 0.07 to 0.14, and still more preferably 0.08 to 0.13, high rebound A foam having excellent elasticity and shape restoration properties can be obtained. That is, when tan δ is smaller than the lower limit, the production is difficult, and when tan δ is larger than the upper limit, appropriate elasticity and high resilience cannot be obtained.

  The rebound resilience of a foam is given externally when measured at a temperature of 25 ° C. using a foam having a diameter of 32 mm punched from a sheet of foam having a thickness of 10 mm based on a measurement method described in JIS K 6301. From the viewpoint of absorbing impact energy, the content is preferably 36% or more, more preferably 38% or more, and further preferably 40% or more. From the viewpoint of imparting high rebound resilience, the upper limit is preferably as high as possible, but is preferably 80% or less, more preferably 70% or less, and still more preferably 60% or less in consideration of the range in which it can be manufactured. From these viewpoints, the rebound resilience of the foam is preferably 36 to 80%, more preferably 38 to 70%, and still more preferably 40 to 70%.

  Further, the tensile strength of the foam was sufficient when measured at a temperature of 25 ° C. using a dumbbell No. 2 type test piece punched from a foam sheet having a thickness of 10 mm based on the measurement method described in JIS K 6301. From the viewpoint of obtaining mechanical strength and durability, it is preferably 1.47 MPa or more, more preferably 1.67 MPa or more, and still more preferably 1.96 MPa or more.

  Raw materials constituting the foam of the present invention include self-foaming polyurethane and the like, rubber, polyvinyl chloride, ethylene-vinyl acetate copolymer, olefin resin, styrene resin and the like. When rubber, polyvinyl chloride, ethylene-vinyl acetate copolymer, olefin-based resin, styrene-based resin, or the like is used, a method of foaming these resins using pre-foamed particles or a foaming agent , And then a method of in-mold foam molding can be adopted.

  The case where the foam of the present invention is made of a typical polyurethane foam will be described below.

  The polyurethane foam having a predetermined storage modulus and tan δ of the present invention can be obtained by appropriately adjusting (a) a polyol, (b) a chain extender, (c) a polyisocyanate compound, (d) a catalyst, and (e) a foaming agent. It can be obtained by mixing and reacting and controlling the ratio of the soft segment and the hard segment forming the polyurethane foam.

  A polyurethane foam is formed from a soft segment composed of a polyol and a hard segment composed of an aggregate containing urethane bonds and urea bonds having high binding energy. Since the dynamic viscoelastic behavior caused by the hard segment affects the storage elastic modulus and tan δ in a temperature range of -5 to 40 ° C, it is important to control the behavior.

  The polyol is at least one selected from the group consisting of polyether polyols having two or more hydroxyl groups (hereinafter, referred to as polyether polyols), polymer polyols based on polyether polyols (hereinafter, referred to as polymer polyols), and polyester polyols. It is preferable that

  Examples of polyether polyols include ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, glycerin, trimethylolpropane, 1,2,6-hexanetriol, and pentaerythritol. Examples thereof include polyether polyols and polyoxytetramethylene glycols obtained by addition-polymerizing an alkylene oxide with a polyhydric alcohol.

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

  The ethylene oxide content of the polyether polyol is preferably from 5 to 50% by weight, more preferably from 5 to 45% by weight, from the viewpoint of achieving sufficient strength and shortening the molding time.

  Representative 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, dispersing the polymerizable unsaturated group-containing monomer in the polyether polyol. By polymerizing, the polymer fine particles obtained from the polymerizable unsaturated group-containing monomer can be produced by, for example, 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 an alkyl group having 1 to 4 carbon atoms such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate; glycidyl methacrylate; Examples thereof include alkyl acrylates having 1 to 4 carbon atoms in an alkyl group; glycidyl acrylate, and the like. These monomers can be used alone or in combination 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, and trimethylolpropane, and phthalic acid, maleic acid, malonic acid, succinic acid, and adipic acid. And condensates with polybasic acids such as terephthalic acid, which have a hydroxyl group at the terminal.

  Among these polyols, polyester polyols are preferred from the viewpoint of achieving both appropriate elasticity and high rebound resilience.

  In order to satisfy the dynamic viscoelasticity conditions of the present invention and obtain a polyurethane foam having sufficient strength, desired storage elastic modulus and tan δ, the molecular weight of the bifunctional polyol or trifunctional polyol and the weight ratio of both polyols must be adjusted. Just fine.

  In addition, the "dynamic viscoelastic condition" referred to in this specification means that the storage elastic modulus is 1.7 to 2.5 MPa and tan δ is 0.01 to 0.14.

  For example, when strength, storage elastic modulus and tan δ are controlled only by a bifunctional polyol, the soft segment is hardly affected by the hard segment by using a high molecular weight bifunctional polyol, and the degree of freedom is improved. It is preferable to add sharpness to the hard segment. By such an operation, the dynamic viscoelastic condition can be satisfied.

  When a bifunctional polyol and a trifunctional polyol are used in combination, the type of the bifunctional polyol is kept constant, and the molecular weight of the trifunctional polyol and the weight ratio of the bifunctional polyol and the trifunctional polyol are controlled. It is preferable to reduce the crystallinity of the soft segment portion. Thus, the dynamic viscoelasticity condition can be satisfied by controlling the molecular weight of the trifunctional polyol and the weight ratio between the bifunctional polyol and the trifunctional polyol.

  The molecular weight of the bifunctional polyol and the trifunctional polyol, and the weight ratio of the bifunctional polyol to the trifunctional polyol are important factors for obtaining a foam having sufficient strength.

  The bifunctional polyol preferably has an average number of functional groups of 1.5 to 2.5 and a number average molecular weight of 1,000 to 5,000 from the viewpoint of imparting sufficient strength.

  The trifunctional polyol may have an average functional group number of 2.5 to 3.5 and a number average molecular weight of 2,000 to 10,000 from the viewpoints of improving initial reactivity, securing dimensional stability of the molded article, and shortening the demolding time. preferable.

  The weight ratio of the bifunctional polyol / trifunctional polyol is preferably 85/15 to 95/5 or 5/95 to 35/65 from the viewpoint of ensuring sufficient strength and dimensional stability of the molded article.

  When a polyether polyol is used as the bifunctional polyol, the average number of functional groups is preferably 1.5 to 2.5, and the number average molecular weight is preferably 1500 to 4500 from the viewpoint of imparting sufficient strength. In addition, when a polyester polyol is used as the bifunctional polyol, the average number of functional groups is 1.5 to 2.5, and the number average molecular weight is 1,000 to 2500, which imparts sufficient strength and ensures liquidity. It is preferable from the viewpoint of doing.

  When a polyether polyol is used as the trifunctional polyol, the average number of functional groups is 2.5 to 3.5, and the number average molecular weight is 2,000 to 8,000 from the viewpoint of the dimensional stability of the molded article. preferable. When a polyester polyol is used as the trifunctional polyol, the average number of functional groups is from 2.5 to 3.5, and the number average molecular weight is from 2,000 to 4,000 in view of securing the dimensional stability and liquidity of the molded article. Is preferred.

  In the case of using a polyester polyol, in order to sufficiently increase the strength in terms of physical properties, to lower the glass transition temperature, and to improve the liquid flowability and the filling property during molding on the working surface, only the bifunctional polyol is used. As the functional polyol, it is desirable to use a polyester polyol having an average number of functional groups of 1.5 to 2.5 and an average molecular weight of 1,000 to 2,200 using ethylene glycol and 1,4-butanediol as polyhydric alcohols.

  When a polyester polyol is used, in order to obtain a polyurethane foam having the characteristics of the present invention by using a bifunctional polyol and a trifunctional polyol in combination, ethylene glycol and 1,4-butanediol as polyfunctional alcohols are used as the bifunctional polyol. It is preferable to use a polyester polyol having an average number of functional groups of 1.5 to 2.5 and an average molecular weight of 1,000 to 2,200.

  From the viewpoint of improving initial reactivity, dimensional stability, strength and hydrolysis resistance in terms of physical properties, the trifunctional polyol has an average number of functional groups of 2.5 to 3.5 and an average of trimethylolpropane as a polyhydric alcohol. It is desirable to use a polyester polyol having a molecular weight of 2,000 to 3,000.

  When a polyester polyol is used, the weight ratio of the bifunctional polyol and the trifunctional polyol is an important factor for obtaining a foam having sufficient strength and excellent in dimensional stability and flex resistance.

  In the case of using a polyester polyol, the weight ratio of the bifunctional polyol / trifunctional polyol is such that a foam having sufficient strength, excellent dimensional stability and excellent bending resistance can be obtained with excellent liquid flowability and filling property. From the viewpoint of molding, the ratio is preferably 85/15 to 95/5, more preferably 87/13 to 93/7.

  As the chain extender, a compound having a number average molecular weight of 1,000 or less and having two or more active hydrogens in the molecule can be used.

  Representative examples of the chain extender include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, methylpentanediol, 1,6-hexanediol, trimethylolpropane, glycerin, and pentaerythritol , Diglycerin, dextrose, polyhydric alcohols such as sorbitol, ethylenediamine, aliphatic polyamines such as hexamethylenediamine, aromatic polyamines, alkanolamines such as diethanolamine, triethanolamine, diisopropanolamine, etc. Objects and the like. These can be used alone or in combination of two or more.

  Suitable chain extenders are at least one selected from the group consisting of ethylene glycol, diethylene glycol, 1,4-butanediol, pentaerythritol, a modified product thereof, and the like. Among them, from the viewpoint of obtaining sufficient strength and a low glass transition temperature, ethylene glycol is preferable, and ethylene glycol having a number average molecular weight of 1,000 or less is more preferable.

  A polyurethane foam that satisfies the dynamic viscoelasticity conditions and has sufficient strength and a desired storage modulus and tan δ can be obtained by adjusting the amount of a low molecular weight chain extender.

  Generally, chain extenders react with the isocyanate component to form strong hard segments. The dynamic viscoelastic behavior resulting from this hard segment directly affects the dynamic viscoelastic conditions. It is presumed that increasing the amount of the chain extender increases the storage modulus and tan δ in the temperature range of -5 to 40 ° C in order to increase the size and number of hard segments.

  However, when the amount of the chain extender is too large, the polyurethane foam has an appropriate elasticity and high rebound resilience because it leads to an increase in hardness, storage elasticity and a reduction in resilience and rebound resilience. From the viewpoint of obtaining a foam, the amount of the chain extender is preferably 3 to 20 parts by weight, more preferably 3 to 15 parts by weight, and still more preferably 3 to 12 parts by weight based on 100 parts by weight of the polyol.

  Typical examples of the polyisocyanate compound include an isocyanate prepolymer.

  The isocyanate prepolymer is obtained by stirring and reacting a polyisocyanate monomer and a polyol in the presence of an excess 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 compounds, modified products thereof, for example, carbodiimide modified products, and these can be used alone or in combination of two or more. . Among these, from the viewpoint of obtaining a foam having sufficient mechanical strength, it is preferable to use 4,4'-diphenylmethane diisocyanate alone or to use the 4,4'-diphenylmethane diisocyanate in combination with a carbodiimide modified product thereof.

  Among the isocyanate prepolymers, isocyanate prepolymers obtained by using 4,4′-diphenylmethane diisocyanate and a carbodiimide modified product of 4,4′-diphenylmethane diisocyanate can shorten molding time, ensure liquidity, and have sufficient strength. It is preferable from the viewpoint of securing

  The isocyanate prepolymer obtained using the carbodiimide-modified 4,4'-diphenylmethane diisocyanate may contain 4,4'-diphenylmethane diisocyanate.

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

Examples of the additive include, for example, an additive used when preparing a polyester polyol, an acid gas such as a hydrogen chloride gas and a sulfurous acid gas, and acetyl chloride in order to prevent the isocyanate prepolymer from self-polymerizing. Isocyanate self-polymerization inhibitors such as acid chlorides such as benzoyl chloride and isophthalic chloride, and phosphoric compounds such as phosphoric acid, monoethyl phosphate and diethyl phosphate. These additives can be used alone or in combination of two or more.
The NCO% of the isocyanate prepolymer is preferably at least 10%, more preferably at least 15%, so that the viscosity is not so high that molding with a low-pressure foaming machine becomes difficult. In order to avoid a decrease in the measuring accuracy of the foaming machine, it is preferably 25% or less, more preferably 22% or less, and further preferably 20% or less.

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

  The NCO% of the polyisocyanate compound is preferably from 10 to 25% from the viewpoint of preventing increase in the viscosity of the liquid and storage stability of the liquid.

  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- Examples thereof include dimethyl-β-phenylethylamine, 1,2-dimethylimidazole, and 2-methylimidazole, and these catalysts may be used alone or in combination of two or more. From the viewpoint of improving the reaction rate, a tertiary amine is preferred.

  As a catalyst other than the tertiary amine, for example, an organic metal compound such as dibutyltin dilaurate, stannous oleate, cobalt naphthenate, or lead naphthenate can be used.

  As the foaming agent, water is an essential component, and hydrocarbons, chlorofluorocarbons, hydrogenated fluorocarbons, and the like may coexist. From the viewpoint of avoiding the problem of the ozone layer depletion on the earth, it is preferable to use water alone as a foaming agent.

  When water is used as the blowing agent, the water generally reacts with the polyisocyanate compound to form strong hard segments. The dynamic viscoelastic behavior resulting from this hard segment directly affects the dynamic viscoelastic conditions. It is presumed that increasing the amount of water increases the value of tan δ in a temperature range of −5 to 40 ° C. in order to increase the size and number of hard segments. However, the density of the polyurethane foam decreases due to the influence of carbon dioxide gas generated by the reaction between isocyanate and water. Therefore, the amount of water is important. From such a viewpoint, the amount of water as the blowing agent is preferably 0.3 to 2 parts by weight, more preferably 0.5 to 1.8 parts by weight, and further preferably 0.5 to 1.8 parts by weight, based on 100 parts by weight of the polyol. To 1.6 parts by weight.

  In the present invention, a silicone-based foam stabilizer, a crosslinking agent, a pigment, an antioxidant, an anti-yellowing agent and the like can be used as additives.

  The polyol, the chain extender, the polyisocyanate compound, the catalyst and the foaming agent are appropriately adjusted and mixed and reacted to control the degree of the soft segment and the hard segment forming the polyurethane foam, whereby the dynamic viscosity of the present invention is controlled. A polyurethane foam which satisfies elasticity conditions and has sufficient strength, desired storage modulus and tan δ can be obtained.

  When reacting the polyol and the polyisocyanate compound, the ratio of the two is preferably adjusted so that the isocyanate index is 80 to 110, more preferably 85 to 105, particularly preferably 90 to 100.

  As a method for producing a polyurethane foam, for example, a polyol, a chain extender, a catalyst, a foaming agent, additives, and the like are preliminarily mixed and stirred, and a polyol component and a polyisocyanate compound are mixed and stirred by a molding machine. And foaming. More specifically, for example, after mixing and stirring the polyol component using a tank and the like, and usually adjusting the temperature to about 40 ° C., a foaming machine such as an automatic mixing injection foaming machine and an automatic mixing injection foaming machine. And a method of reacting and foaming with a polyisocyanate compound.

In order to satisfy the dynamic viscoelasticity conditions and obtain a polyurethane foam having sufficient strength, a desired storage elastic modulus and tan δ, the density of the polyurethane foam is preferably 0.1 g / cm ³ or more, more preferably It is 0.2 to 0.6 g / cm ³ , more preferably 0.3 to 0.5 g / cm ³ .

  The foam of the present invention can be suitably used as a foam for shoe soles. Suitable uses include soles for men's shoes, sports shoes and the like. Generally, shoe soles are used for soles classified into an outsole used for sandals, men's shoes, etc., a midsole used for sports shoes, etc., and an inner sole (insoles) installed inside shoes. Consists of members. The foam of the present invention can be suitably used for these shoe sole members. Among these, outsole is particularly preferable from the viewpoint of the effect of the foam.

  The shoe of the present invention can be usually manufactured by integrating a shoe body (such as an upper) and a shoe sole. The shoe body is a portion that wraps the instep, and is not particularly limited in material and shape.

  In soles, flexibility is a very important factor. Specifically, regarding the flexibility, it is required that “not to be broken” in consideration of durability and “bendable” in consideration of walking. In order to realize this “easy bending”, it is important that the stress with respect to the initial elongation of the foam is low. This “easy bending” is evaluated by the modulus at the time of measuring the tensile strength. The modulus is expressed as a stress value in a state of being stretched by 100% or 200% of the distance between the reference lines at the time of elongation measurement with reference to the reference line for elongation measurement. The smaller the stress value is, the more easily it can be deformed with a smaller stress. At this time, from the viewpoint of realizing “easy bending”, it is desirable that the 100% modulus is 1.2 MPa or less, preferably 1.1 MPa or less, and the 200% modulus is 2 MPa or less, preferably 1.9 MPa or less. .

  Also, in shoe soles, abrasion is also a very important factor. This “wear property” is evaluated according to the DIN abrasion test specified in JIS K 6264. As the test piece, a disc-shaped test piece having a diameter of 18 mm and a thickness of 10 mm cut out from a sheet sample is used. The force for pressing the test piece against the polishing cloth is set to 7.5 N, and the load device is adjusted using a weight. At this time, the weights of the test pieces before and after the wear test are measured with a precision balance, and the difference between the two (the amount of wear) is used as an index of wear. In this test, from the viewpoint of maintaining durability, it is desirable that the wear amount is 100 mg or less, preferably 90 mg or less, and more preferably 80 mg or less.

  The case where the foam is a polyurethane foam has been described above, but the storage elastic modulus obtained from the dynamic viscoelasticity at a frequency of 10 Hz and 25 ° C. is 1.7 to 2.5 MPa, and tan δ is 0.01. The method for producing a foam having a size of ~ 0.14 varies depending on the type of the foam. Therefore, it is preferable to appropriately adjust these properties according to the type of the foam.

  Hereinafter, a case where the foam of the present invention is a polyurethane foam will be described in more detail with respect to a method for producing a foam having the above-described properties.

Examples 1 to 6 and Comparative Examples 1 to 9
A polyol component was prepared by mixing a polyol, a chain extender, a catalyst, a foaming agent (water), a foam stabilizer, and a white pigment so as to have the composition shown in Table 1.

The mixing ratio of the polyol component and the polyisocyanate is represented by the formula:
(Isocyanate index)
= [Actual amount of isocyanate used]
÷ (Amount of isocyanate stoichiometrically equivalent to polyol)
× 100
Was adjusted so that the isocyanate index obtained on the basis of the above was a value shown in Table 1.

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

〔Molding condition〕
-Reactivity: cream time 5 to 15 seconds-Demolding time: 5.5 to 6.5 minutes The abbreviations of the components used in each example and each comparative example mean the following.

(Polyol)
PO1: polypropylene glycol [manufactured by Asahi Glass Urethane Co., Ltd., trade name: Preminol 5005, number of functional groups: 2, hydroxyl value: 28 mgKOH / g, number average molecular weight: 4000]
PO2: polypropylene glycol [manufactured by Asahi Glass Urethane Co., Ltd., trade name: Exenol 540, number of functional groups: 2, hydroxyl value: 56 mgKOH / g, number average molecular weight: 2000]
PO3: polypropylene triol [manufactured by Asahi Glass Urethane Co., Ltd., trade name: Exenol 820, number of functional groups: 3, hydroxyl value: 34 mgKOH / g, number average molecular weight: 4900]
PO4: Polyester polyol (raw material monomers: ethylene glycol, 1,4-butanediol and adipic acid, ethylene glycol / 1,4 butanediol (weight ratio) = 1/1, number of functional groups: 2, hydroxyl value: 86 mgKOH / g, (Number average molecular weight: 1300)
PO5: polyester polyol [raw material monomer: ethylene glycol, 1,4-butanediol and adipic acid, weight ratio of ethylene glycol / 1,4-butanediol: 3/2, number of functional groups: 2, hydroxyl value: 52 mgKOH / g, Number average molecular weight: 2200]
PO6: polyester polyol [raw material monomers: ethylene glycol, diethylene glycol and adipic acid, weight of ethylene glycol / diethylene glycol: = 5/6, number of functional groups: 2, hydroxyl value: 86 mgKOH / g, number average molecular weight: 1,300]
PO7: Polyester polyol [raw material monomer: 1,4-butanediol, trimethylolpropane and adipic acid, weight ratio of 1,4-butanediol / trimethylolpropane: 12/1, number of functional groups: 3, hydroxyl value: 61 mgKOH / g, number average molecular weight: 2500]

(Polyisocyanate)
PI1: Kao Corporation, trade name: Ediform B-6106M (NCO%: 16.0%, isocyanate used for isocyanate prepolymer: 4,4′-diphenylmethane diisocyanate)
PI2: manufactured by Kao Corporation, trade name: Ediform B-2009 (NCO%: 18.5%, isocyanate used for isocyanate prepolymer: 4,4'-diphenylmethane diisocyanate)

(Chain extender)
CE1: ethylene glycol CE2: 1,4-butanediol CE3: DEG (diethylene glycol)

〔catalyst〕
Triethylenediamine (foam stabilizer)
Toray Dow Corning Silicone Co., Ltd., trade name: SRX-253
(White pigment)
Product name: FTR White, manufactured by Dainichi Seika Industry Co., Ltd.

  The physical properties of the produced test sheet were examined according to the following methods. Table 2 shows the results.

(1) Storage modulus and tan δ
The dynamic viscoelasticity test was performed using a rectangular parallelepiped sample piece having a length of 30 mm and a cross section of 5 mm × 10 mm cut out from a prepared test sheet based on the test method of JIS K 7198, and manufactured by IT Measurement Control Co., Ltd. And a dynamic viscoelasticity measuring device DVA-225 at a heating rate of 2 ° C./min and a frequency of 10 Hz. The measurement was started from minus 100 ° C. after cooling. From the obtained data, the storage elastic modulus (E ′) at 25 ° C. and tan δ were determined.

(2) Density The weight of the test sheet (100 mm × 300 mm × 10 mm) was measured and divided by the volume of 300 cm ³ .
(3) Hardness The hardness of the test sheet surface was measured at 25 ° C. using an Asker C hardness meter.
(4) Tensile strength, tear strength and elongation Measured in accordance with JIS K 6301 using a dumbbell No. 2 type test piece punched from a test sheet.

(5) Rebound resilience Using a test piece having a diameter of 32 mm (thickness: 10 mm) punched out of a test sheet, measurement was performed in accordance with JIS K6301.
(6) Feeling At 25 ° C., the touch of the polyurethane foam having a thickness of 10 mm was evaluated with a touch finger. The case where the elasticity was moderate was indicated by ○, the case where it was hard and the elasticity was not felt was indicated by x, and the case where the elasticity was not soft and appropriate was not indicated by Δ.

(7) Abrasion Abrasion was evaluated according to the DIN abrasion test specified in JIS K 6264. As the test piece, a disc-shaped test piece having a diameter of 18 mm and a thickness of 10 mm cut out from a sheet sample was used. The force for pressing the test piece against the polishing cloth was 7.5 N, and the load device was adjusted using a weight. At this time, the masses of the test pieces before and after the abrasion test were measured with a precision balance, and the difference between the two masses (amount of abrasion) was used as an index of abrasion.

From the results shown in Table 2, the polyurethane foams obtained in each Example had a density of 0.1 g / cm ³ or more, and a storage elastic modulus obtained from dynamic viscoelasticity at a frequency of 10 Hz and 25 ° C. Is 1.7 to 2.5 MPa, and tan δ is 0.01 to 0.14, so that it can be seen that the rubber composition has appropriate elasticity and high rebound resilience at the same time.

  On the other hand, the polyurethane foams obtained in Comparative Examples 1 and 2 have a high storage modulus and a high hardness, do not have appropriate elasticity, and do not have high rebound resilience.

  Further, although the polyurethane foam obtained in Comparative Example 4 has high rebound resilience, it has an appropriate elasticity, and the fact that this polyurethane foam does not have an appropriate elasticity is based on the value of hardness (Asker C). Is also clear.

  The polyurethane foam obtained in Comparative Example 3 has high rebound resilience, but has a strong soft feeling and does not have appropriate elasticity.

  The polyurethane foam obtained in Comparative Example 5 satisfies the storage elastic modulus under dynamic viscoelasticity conditions, but has a high tan δ, does not have appropriate elasticity from the viewpoint of feel, and has a high rebound resilience. Also have no.

  In the polyurethane foams obtained in Examples 1 and 2 and Comparative Examples 3 and 4, the polyol, the chain extender, the catalyst, the pigment, the amount of water added as the foaming agent, and the foam stabilizer were mixed in the same type. It can be seen that the storage modulus and tan δ differ depending on the amount of the compound.

  ADVANTAGE OF THE INVENTION The foam of this invention has sufficient intensity | strength, and it has the effect of having moderate elasticity and high rebound resilience simultaneously. Therefore, the foam of the present invention can be suitably used especially as a foam for shoe soles.

Claims (10)

  A foam having a storage elastic modulus obtained from dynamic viscoelasticity at a frequency of 10 Hz and 25 ° C. of 1.7 to 2.5 MPa and a tan δ of 0.01 to 0.14.   The foam according to claim 1, comprising a polyurethane foam.   The foam according to claim 1 or 2, having a tensile strength of 1.47 MPa or more.   The foam according to any one of claims 1 to 3, having a rebound resilience of 36 to 80%.   The amount of abrasion in a DIN abrasion test is 100 mg or less under the condition that the force for pressing the test piece against the polishing cloth is 7.5 N and the test piece is a disk-shaped test piece having a diameter of 18 mm and a thickness of 10 mm. 4. The foam according to any one of 4.   The foam according to any one of claims 1 to 5, wherein the 100% modulus is 1.2 MPa or less.   A shoe sole member comprising the foam according to any one of claims 1 to 6.   A shoe sole having the foam according to any one of claims 1 to 6.   Under the conditions that the rebound resilience is 36 to 80%, the force for pressing the test piece against the polishing cloth is 7.5 N, and the test piece is a disc-shaped test piece having a diameter of 18 mm and a thickness of 10 mm, A foam having a wear amount of 100 mg or less and a 100% modulus of 1.2 MPa or less.   A method for producing a polyurethane foam by reacting a polyol component and an isocyanate compound, wherein the polyol component is a bifunctional polyol, and ethylene glycol and 1,4-butanediol are used as polyhydric alcohols of the bifunctional polyol raw material, A method for producing a polyurethane foam having a storage elastic modulus obtained from dynamic viscoelasticity at a frequency of 10 Hz and 25 ° C. of 1.7 to 2.5 MPa and a tan δ of 0.01 to 0.14.