JPH0218684B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) This invention relates to a method for obtaining a moldable, cold-resistant polyurethane elastomer, particularly a polyurethane elastomer with excellent moldability and cold resistance for use in shoe soles. (Prior art) As a polyurethane composition, the molecular weight is 300 to 25,000.
The technology of using a liquid diene polymer containing active hydrogen groups in combination with a polyester polyol was disclosed in Japanese Patent Application Laid-Open No. 1986-
It is known in Japanese Patent Application Laid-open No. 38224 and JP-A-59-38225, and it is also disclosed that lactone-based polyester and other known polyester polyols are used as the polyester polyol and exhibit excellent physical properties and low-temperature properties. (Problems to be Solved by the Invention) However, the above-mentioned known invention is a one-shot method in which a liquid diene polymer containing active hydrogen groups and a polyester polyol are mixed in advance and reacted with a polyisocyanate. As stated in the publication, active hydrogen group-containing liquid diene polymers generally have high viscosity, and especially when they have a high molecular weight, it is difficult to mix them with general-purpose polyesters and polyethers. When the molecular weight is 2800, there is a problem with adipate polyesters that it is difficult to disperse uniformly even when heated to 70 to 80°C, so the molecular weight of liquid diene polymers containing active hydrogen groups is in the range of 300 to 2000. limited to. On the other hand, in the footwear industry, although polyurethane soles are recognized for their excellent abrasion resistance and moldability, there is a problem that they are inferior to rubber soles in low-temperature properties, especially grip properties against ice burns, and there is an urgent need to improve these soles. It was said that (Means for Solving the Problems) In order to solve the above problems, the present invention combines a general-purpose polyol and a liquid diene polymer containing active hydrogen groups, which has poor workability due to high viscosity, alone or in combination with other polyols. This is a method for producing a urethane elastomer using a prepolymer method in which a mixed polyol is made into a prepolymer having terminal isocyanate groups, and the prepolymer is cured. That is, the present invention is directed to a) reacting a polyisocyanate with a polyol component which includes a liquid diene polymer containing active hydrogen groups as an essential component and which is mixed with at least one polyol selected from lactone polyester polyols and adipate polyester polyols. This is a method for producing a polyurethane elastomer, which is characterized in that b) a curing agent prepared by mixing an adipate-based polyester polyol with a crosslinking agent and a catalyst is added to the isocyanate-terminated prepolymer obtained by the above-mentioned isocyanate-terminated prepolymer, and the curing agent is cured. The active hydrogen group-containing liquid diene polymer in the present invention is a polymer or copolymer having a molecular weight of 500 to 10,000 and an average number of functional groups of 1.7 to 3.0, such as butadiene homopolymer, isoprene homopolymer, butadiene/styrene copolymer, butadiene/isoprene copolymer, etc. It is a combination. These polymers or copolymers are commonly used polyisocyanates such as diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), meta-xylylene diisocyanate (MXDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI) etc., by a known method in an excess of isocyanate to form an isocyanate-terminated prepolymer. The content of reactive terminal isocyanates is 5-30%, preferably 10-25%
is within the range of The lactone-based polyester polyol used in the present invention is polycaprolactone having an average molecular weight of 500 to 4000 and a functional group number of 2 to 3, and may be a copolymer with an adipic acid ester or a polyalkylene ether polyol. The polyester polyol can also be prepolymerized in the same manner as the active hydrogen group-containing liquid diene polymer. In addition, as the adipate polyester polyol used in the present invention,
Any known material can be used. When these adipate polyester polyols are used as one component of a prepolymer, they can be prepolymerized in the same manner as the active hydrogen group-containing liquid diene polymer. Incidentally, all of the above prepolymers can also contain a quasi prepolymer. As the adipate polyester polyol used as the curing agent, those mentioned above can be used. In addition, all known blowing agents, foam stabilizers, crosslinking agents, catalysts, etc. can be used, and if necessary, fillers, reinforcing agents, coloring agents, flame retardants, etc. can also be added. (Function) This invention can reduce the viscosity by reacting a high-viscosity, high-molecular-weight, active hydrogen-containing liquid diene polymer that has poor miscibility with general-purpose adipate polyester polyols with polyisocyanate to form a prepolymer. Since this is a mixed prepolymer method in which a prepolymer obtained by reacting a lactone polyester polyol or an adipate polyester polyol with a polyisocyanate as another polyol is mixed, the mixture can be uniformly mixed in a short time. In addition, the diene polymer having an average molecular weight of 2000 or more can also be used. (Examples) Hereinafter, the present invention will be explained based on Examples. (1) Preparation of diene prepolymer A Place 52.4 parts by weight of MDI in a three-necked flask and heat to 50°C.
The liquid polybutadiene R-45HT (average molecular weight 2800) manufactured by Idemitsu Petrochemical Co., Ltd. is used as a liquid diene polymer containing active hydrogen groups.
The mixture was added in an amount of 47.6 parts by weight and reacted at 70 to 80° C. for 2 hours to obtain diene prepolymer A with 0% of unterminated NCs of 15.9%. (2) Preparation of lactone-based prepolymer B As a lactone-based polyester polyol, 46.56 parts by weight of PCL-220 (product name: average molecular weight 2000) manufactured by Daicel Chemical Industries, Ltd. was added in the same manner as in Example 1.
Terminal NCO% by reacting with MDI53.44 parts by weight
A lactone-based prepolymer B containing 16.0% was obtained. (3) Preparation of adipate-based prepolymer C As a general-purpose polyester polyol, for 44.9 parts by weight of copolymerized adipate (average molecular weight 1500) of ethylene glycol and diethylene glycol,
Terminal NCO% by reacting with MDI155.1 parts by weight
An adipate prepolymer C having a content of 16.0% was obtained. (4) Production of polyurethane elastomer To the mixed prepolymer obtained by mixing diene prepolymer A obtained above and lactone prepolymer B or adipate prepolymer C so that NCO/OH = 1, diene prepolymer A curing agent containing adipate triol, adipate diol, ethylene glycol, triethylene diamine, etc. is added to lactone-based mixed polyol prepolymer D, and heated to 35 to 45°C to form a three-blade propeller shaft. A homogeneous mixture was obtained by mixing for 10 seconds using a mold stirrer, and this homogeneous mixture was immediately cast into a 6 x 15 x 200 cm flat iron mold.
After 7 minutes, the cured product was demolded and aged at room temperature for 24 hours, after which the physical properties of each polyurethane elastomer were measured. As a comparative example, a polyurethane elastomer was obtained in the same manner as in the above example except that only diene prepolymer A or adipate prepolymer C was used. The formulations of the prepolymers and curing agents of the above Examples and Comparative Examples and various physical property values of the polyurethane elastomers are shown in Tables 1 and 2 below.

[Table] Adipate polyol E in the above table is a copolymerized adipate of ethylene glycol and diethylene glycol (average molecular weight 1500), F is a copolymerized adipate of ethylene glycol and butylene glycol (average molecular weight 2000), and ethylene glycol and 1.4
- 2:1 mixed copolymerized adipate (average molecular weight 1500) with copolymerized adipate of butanediol (average molecular weight 1000), G is a copolymerized triol of trimethylolpropane and diethylene glycol (average molecular weight 2500, number of functional groups 2.7) It is. The silicone foam stabilizer is trade name SRX-295 (manufactured by Toray Silicone Co., Ltd.).

[Table] In Table 2, density and A hardness are JIS-K6301
The tensile strength and elongation rate were measured in accordance with the regulations of JIS-K6301 using a Shimadzu Autograph DSS-2000 with a No. 3 dumbbell at a head speed of 500 mm/min.
It is a measured value of elongation rate. The bending test is JIS-
Tests were conducted in an atmosphere of room temperature and -20°C using a Demarzier bending tester manufactured by Toyo Seiki Co., Ltd. in accordance with the provisions of K6301, and the results were expressed as the number of crack growth initiation times. The skid resistance index is based on the Rubber Testing Method (New Edition) (1973).
This is a value measured on ice at an ambient temperature of -10° C. using a portable skid resistance tester described on page 367 of the Japan Rubber Association, published on November 1, 2015 (Natural rubber skid resistance index is 45). The Gehman torsion test is a measurement of freezing temperature using methanol and dry ice as refrigerants using a testing machine manufactured by Ueshima Seisakusho in accordance with the provisions of JIS-K6301. In the moisture and heat deterioration test, the specimen was exposed to a constant temperature and humidity chamber at 80° C. and 95% RH for 1 to 5 days, and then the number of days it could withstand 100,000 bending tests at room temperature was determined. As shown in Table 2 above, Comparative Example 1 using only Prepolymer A has excellent moisture and heat deterioration resistance, but has poor bending resistance and is considerably inferior in strength and elongation properties. Comparative example 2 using only prepolymer C
Not only does it have poor moisture and heat deterioration resistance, it also has poor low-temperature bending resistance, and in addition, it has a low low-temperature skid resistance index and is easily slippery on ice, so it cannot be used for shoe soles. On the other hand, all the properties of Examples 1 to 5 are well balanced, and the results of practical tests indicate that they are suitable as shoe sole materials. (Effects of the Invention) Since the method of the present invention is based on a prepolymer method, the active hydrogen group-containing liquid diene polymer component in the polyurethane elastomer and the general-purpose polyol component can be blended uniformly and quickly. Therefore, the above diene polymers having an average molecular weight of 2000 or more can also be used. The obtained polyurethane elastomer is suitable for use in shoe soles because it has well-balanced physical properties such as strength and elongation, bending resistance, skid resistance index, freezing resistance, and resistance to moist heat deterioration.

Claims (1)

[Scope of Claims] 1a A polyisocyanate is added to a polyol component in which an active hydrogen group-containing liquid diene polymer is an essential component, and at least one polyol selected from lactone polyester polyols and adipate polyester polyols is mixed therewith. A method for producing a polyurethane elastomer, which comprises curing the isocyanate-terminated prepolymer obtained by the reaction by adding (b) a curing agent prepared by mixing an adipate polyester polyol with a crosslinking agent and a catalyst. 2. In producing the isocyanate-terminated prepolymer, a mixed prepolymer obtained by mixing a prepolymer obtained by reacting at least one polyol component with a polyisocyanate component in advance is used as the isocyanate-terminated prepolymer, as described in claim 1. A method for producing polyurethane elastomer. 3 The density of the obtained polyurethane elastomer is
0.2 to 1.15g/ ^cm3 , and the demerger flex life is
100,000 times or more, growth is 400% or more, and JIS
The manufacturing method according to claim 1, wherein the A hardness is 40 or more. 4. The manufacturing method according to claim 1, wherein the obtained polyurethane elastomer is used for footwear.