JPH0762107B2 - Thermoplastic polyurethane composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a composition obtained by blending a specific thermoplastic polyurethane with a small amount of a thermoplastic graft polymer.

The composition provided by the present invention has excellent heat resistance and injection moldability as well as excellent cold resistance and mechanical performance.

[Conventional technology]

Conventionally, thermoplastic polyurethane has been attracting attention as a substitute material for rubber and plastics because it has a high elastic modulus and many features such as excellent wear resistance and oil resistance, and the usual plastic molding method is applied. As a molding material that can be used, it has been widely used in a wide range of applications. Thermoplastic polyurethane is produced by mixing and polymerizing a chain extender such as polymer diol, diisocyanate and 1,4-butanediol.

Releasability (prevention of tackiness) during molding of thermoplastic polyurethane
For the purpose of improving the temperature dependence of the melt viscosity,
Attempts have been made to blend 90 to 10% by weight of thermoplastic polyurethane and 10 to 90% by weight of a resin obtained by graft-polymerizing an ethylene-propylene rubber with an aromatic vinyl compound and a vinyl cyanide compound (Japanese Patent Publication Sho 60). -17281 and Japanese Patent Publication No. 62-34265). Further, in order to improve the molding processability of the thermoplastic polyurethane, blending 1 to 30% by weight of a terpolymer or terpolymer blend polymer of acrylonitrile-styrene-butadiene with 99 to 70% by weight of the thermoplastic polyurethane. Has been proposed (see Japanese Patent Publication No. 54-7827).

[Problems to be Solved by the Invention]

The conventional thermoplastic polyurethane has extremely poor heat resistance, has a long cycle time of injection molding, is inferior in productivity, and has a problem in injection moldability such as occurrence of sink marks, and improvement thereof is strongly desired. There is.

The thermoplastic polyurethane composition prepared by blending the above ethylene-propylene rubber with a resin obtained by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound contains a large amount of the graft polymer. Although the tackiness is improved, there is a problem that the original characteristics of the thermoplastic polyurethane such as increase in hardness, decrease in elongation, decrease in flex resistance, etc. are lost. Also,
A thermoplastic polyurethane composition containing an acrylonitrile-styrene-butadiene terpolymer or ternary blend polymer has not been improved to a satisfactory level of molding processability without causing other problems. Is.

An object of the present invention is to provide a thermoplastic polyurethane composition having excellent heat resistance and injection moldability.

[Means for Solving the Problems]

According to the invention, the above object consists of (A) 92-99% by weight of thermoplastic polyurethane and (B) 8-1% by weight of thermoplastic graft polymer, wherein the thermoplastic polyurethane is (a) of the structure Polyester diol and / or polycarbonate diol having a number average molecular weight of 1,500 to 3,500, which has units (I) and (II) and / or (III) as essential structural units, and (b) diisocyanate and (c) A chain extender, and the sum of the weights of components (b) and (c) is in the range of 23 to 56% with respect to the sum of the weights of components (a), (b) and (c), To provide a thermoplastic polyurethane composition characterized in that the thermoplastic graft polymer is a polymer obtained by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound on an elastomer. Is Yotsute achieved.

(I): - O- (CH 2) 9 -O- The composition of the present invention has a high injection molding cycle speed,
It is important that the thermoplastic polyurethane has the above-specified structure so that the molding strain is small, and the properties such as excellent heat resistance and cold resistance are highly exhibited. In the case of the thermoplastic polyurethane composition having no specified structure, the effect of the composition of the present invention is hardly recognized.

The polyester diol and polycarbonate diol constituting the thermoplastic polyurethane in the present invention have a number average molecular weight of 1,500 to 3,500 determined from a hydroxyl value and an acid value.
It is extremely important to be in the range of. The number average molecular weight is preferably in the range of 1,800 to 3,000. When the number average molecular weight is less than 1,500, almost no improvement in injection molding cycle speed, molding strain rate, and heat resistance is observed, and when it exceeds 3,500, the change in melt viscosity during molding is large and stable molding is possible. It will be difficult.

The polyester diol and polycarbonate diol have the above structural units (I) and (II) and / or (III) as essential structural units in the molecule. Structural unit (I) is derived from 1,9-nonanediol, structural unit (II) is derived from 2-methyl-1,8-octanediol, and structural unit (III) is 3-methyl-1,5. -Derived from pentanediol. Structural units (II) and (II
The sum of the mole fractions of I) is 10% or more with respect to the sum of the mole fractions of structural units (I) to (III), and the sum of the mole fractions of structural units (I) and (II) is The composition of the present invention obtained from the polyester diol and / or the polycarbonate diol, which is 50% or more based on the sum of the mole fractions of the structural units derived from the diol, exhibits the above-mentioned effects to a higher degree. If the sum of the mole fractions of structural units (II) and (III) is less than 10% with respect to the sum of the mole fractions of structural units (I) to (III), the composition has cold resistance and flexibility. And the sum of the mole fractions of the structural units (I) and (II) is relative to the sum of the mole fractions of the diol-derived structural units.
When it is less than 50%, the effect of improving the heat resistance of the composition, the injection molding cycle speed, the molding strain rate, etc. does not reach a sufficient level, and therefore, either case is not preferable.

Examples of the glycol used in the production of the polyester diol or the polycarbonate diol in the present invention include ethylene glycol, 1,4-butadiol,
Examples thereof include 2-methyl 1,3-propanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexane glycol, 1,8-octanediol and 1,10-decanediol. These glycols alone or 2
Although used in mixtures of one or more, it is appropriate to use less than 50 mol% of the total diols used. The amount used is preferably 30 mol% or less. The dicarboxylic acid used in the production of polyester diol,
Examples thereof include succinic acid, adipic acid, azelaic acid, sebacic acid and the like, and among them, adipic acid and azelaic acid are preferable. These dicarboxylic acids are used alone or in a mixture of two or more.

The thermoplastic polyurethane in the present invention has a weight of the components (b) and (c), that is, the weight of the hard segment constituent is 23 to 56 with respect to the weight of the components (a), (b) and (c). It is important to be in the range of%. When the weight of the hard segment constituent is less than 23%, the effect of improving the injection moldability and heat resistance of the composition is small, and when it exceeds 56%, the change in melt viscosity of the composition with time is large. The moldability becomes poor.

The thermoplastic polyurethane in the present invention is obtained by melt-polymerizing a polyester diol and / or a polycarbonate diol, a diisocyanate and a chain extender. The diisocyanate to be used is an aliphatic, alicyclic or aromatic diisocyanate containing two isocyanate groups in the molecule, for example 4,4'-
Diphenyl methane diisocyanate, p-phenylene diisocyanate, tolylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'- Examples thereof include dicyclohexylmethane diisocyanate. As the diisocyanate, 4,4'-diphenylmetadiisocyanate is particularly preferable. As the chain extender, a chain growth agent commonly used in the polyurethane industry, that is, a low molecular weight compound having a molecular weight of 400 or less and containing at least two hydrogen atoms capable of reacting with isocyanato can be used. For example, ethylene glycol, propylene glycol, 1 , 4-butanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, 1,4-bis (β-hydroxyethoxy) benzene, bis ( β-hydroxyethyl) terephthalate, diol such as xylylene glycol; ethylenediamine, propylenediamine, xylylenediamine,
Examples include diamines such as isophoronediamine, piperazine, phenylenediamine, and tolylenediamine; hydrazine; hydrazides such as adipic acid dihydrazide and isophthalic acid dihydrazide. 1,4 as a chain extender
Most preferably, butanediol or 1,4-bis (β-hydroxyethoxy) benzene is used. These compounds are used alone or in combination of two or more. As the polymerization conditions, the conditions adopted in the known urethane-forming reaction are applied, but it is preferable to adopt a temperature in the range of 200 to 240 ° C. as the polymerization temperature. By maintaining the polymerization temperature at 200 ° C or higher, a polyurethane having good moldability can be obtained, and by maintaining the polymerization temperature at 240 ° C or lower, a polyurethane having increased heat resistance can be obtained. As a polymerization method, it is particularly preferable to adopt a continuous melt polymerization method using a multi-screw screw type extruder.

In the composition of the present invention, a thermoplastic graft obtained by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound (graft monomer) on an elastomer (graft substrate), on the thermoplastic polyurethane having the above-mentioned specified structure Incorporation of the polymer in a specific ratio is an important requirement for achieving the above-mentioned object of the present invention. In the present invention, it is necessary to blend 92 to 99% by weight of thermoplastic polyurethane and 8 to 1% by weight of thermoplastic graft polymer. When the blending ratio of the thermoplastic graft polymer is less than 1% by weight, the effect of the present invention is hardly exhibited, and when it exceeds 8% by weight, the hardness of the composition becomes high and the elongation decreases. . Therefore, when comparing a composition having an increased hardness of more than 8% by weight of the thermoplastic graft polymer with a composition of the present invention having the same hardness, the former composition is The hard segment content is lower than that of the latter composition, the heat resistance is lower than that of the latter composition, and the flex resistance is also reduced, the original characteristics of thermoplastic polyurethane are impaired, and the application is limited. It will be what was done.

As the elastomer of the above-mentioned graft substrate, it is preferable to use one having a second-order transition temperature lower than -30 ° C. As the aromatic vinyl compound of the graft monomer, for example, styrene, α-methylstyrene, nuclear alkyl-substituted styrene, nuclear halogen-substituted styrene, etc. are used. It is particularly preferable to use styrene. As the vinyl cyanide compound, for example, acrylonitrile, methacrylonitrile, etc. are used. It is particularly preferable to use acrylonitrile.

The thermoplastic graft polymer used in the present invention includes, for example, a resin obtained by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound on ethylene-propylene rubber (hereinafter, abbreviated as AES resin). To be As the ethylene-propylene rubber, ethylene-propylene copolymer rubber and ethylene-propylene-diene copolymer rubber are used. The weight ratio of ethylene to propylene is preferably in the range of 9: 1 to 2: 8. As the diene monomer, norbornenes such as alkenyl norbornene, cyclic dienes such as dicyclopentadiene, and aliphatic dienes such as hexadiene are used. The diene monomer may be used alone or in combination of two or more. Ethylene-aromatic vinyl compounds and aromatic vinyl compounds, the weight ratio of vinyl compounds used in the graft polymerization of vinyl cyanide compounds, etc. is appropriately in the range of 5:95 to 50:50, 10:90 to 40:60. Is preferred. AES
The resin is produced by a bulk polymerization method, an emulsion polymerization method, a solution polymerization method, a bulk-suspension polymerization method, a suspension polymerization method, an emulsion-suspension polymerization method, or the like.

Further, as the thermoplastic graft polymer used in the present invention, for example, a copolymer obtained by adding both graft monomers of acrylonitrile and styrene to the latex of a butadiene-based polymer and emulsion-polymerizing it, acrylonitrile-butadiene copolymer and styrene- Examples thereof include blend polymers obtained by blending with an acrylonitrile copolymer (hereinafter, these are collectively referred to as ABS resin). Examples of the butadiene-based polymer latex include polybutadiene latex, acrylonitrile-butadiene copolymer latex, and styrene-butadiene copolymer latex. The proportion of each of the above components is 5 to 50% by weight of butadiene, 20 to 85% by weight of styrene, and 5 to 40% by weight of acrylonitrile.

The thermoplastic polyurethane composition of the present invention is premixed at a predetermined ratio using a vertical type or horizontal type mixer which is usually used for mixing resin materials with the above-mentioned thermoplastic polyurethane and thermoplastic graft polymer. Then, it is produced by heating and kneading in a batch type or a continuous type using a single-screw or twin-screw extruder, a mixing roll, a Banbury mixer and the like. Light resistance during mixing, stabilizers for further improving heat resistance, plasticizers, waxes of montanic acid, lubricants such as aliphatic amides, fillers, antistatic agents,
It is possible to add additives such as pigments in an amount that does not impair the effects of the present invention.

The thermoplastic polyurethane composition of the present invention is particularly excellent in moldability and heat resistance including injection moldability,
It is easily molded by a commonly used injection molding machine, extrusion molding machine, blow molding machine, calender, or the like. The thermoplastic polyurethane composition of the present invention has a high molding dimensional accuracy, and excellent heat resistance, cold resistance, oil resistance, abrasion resistance, toughness and mechanical performance, and therefore, a sheet, a film, a roll, Gear, solid tires, snow tires,
Snow chains, belts, watch bands, hoses, tubes, packing materials, anti-vibration materials, shoe soles, sports shoes, other laminated product materials, machine parts, automobile parts,
Used for sports equipment and elastic fibers. Further, the thermoplastic polyurethane composition of the present invention is dissolved in a solvent and used for artificial leather, coating agents, fiber treatment agents, adhesives, binders, paints and the like.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In addition, in the reference example, the number average molecular weight is obtained according to the following method. Further, in Examples and Comparative Examples, the injection moldability (molding cycle time), heat resistance, cold resistance, flex resistance, and hardness of the thermoplastic polyurethane compositions were evaluated according to the following methods. The hard segment content of the thermoplastic polyurethane means the weight ratio of the segment based on the diisocyanate and the chain extender in the thermoplastic polyurethane.

(1) Number average molecular weight: determined from the hydroxyl value and acid value of polyester diol or polycarbonate diol.

(2) Heat resistance and cold resistance: Using a dynamic viscoelasticity measuring device [DVE Rheospectler, manufactured by Rheology Co., Ltd.] for a test piece prepared from a polyurethane composition film having a thickness of 500 μ obtained by extrusion molding. , Storage modulus E '(100) (dyne / cm ² ) at 100 ° C was measured, and E' (10
0) evaluated the heat resistance. Those having a large value have excellent heat resistance. Further, with respect to a test piece prepared from a polyurethane composition film having the same thickness, Tα (peak temperature of E ″, 11 Hz) was measured by temperature dispersion using the same dynamic viscoelasticity measuring device, and thereby cold resistance was evaluated. did.

(3) Injection moldability: injection molding is performed by changing the molding cycle time (injection time + cooling time), and the molding cycle time at which sink marks and deformation do not occur in the obtained molded product is measured. evaluated.

(4) Flex resistance: A test piece of 500 μ (thickness) × 70 mm × 45 mm was examined for flex resistance at −20 ° C. by a flex resistance tester according to the method specified in JIS K-6545.
The bending resistance was evaluated by the number of times of bending until the test piece cracked.

(5) Hardness: The Shore hardness A was evaluated according to the method specified in JIS K-6301.

Reference Example 1 Production of Polyester Diol 1,600 g of a mixture of 2-methyl-1,8-octanediol and 1,9-nonanediol (molar ratio = 35: 65) and 1,460 g of adipic acid were charged into a reactor, and the mixture was kept under normal pressure. The esterification reaction was carried out while passing condensed gas out of the system at a temperature of about 220 ° C while passing nitrogen gas through the system. Acid value of polyester is 0.3
When the following was reached, the degree of vacuum was gradually raised by a vacuum pump to complete the reaction. The polyester diol thus obtained has a hydroxyl value of 56, an acid value of 0.12 and a number average molecular weight.
Had 2,000.

Reference Examples 2 to 7 Production of Polyester Diol The esterification reaction was carried out in the same manner as in Reference Example 1 except that the dicarboxylic acid that gave the dicarboxylic acid component and the diol that gave the diol component shown in Table 1 were used, respectively.
The polyester diols shown in Table 1 were obtained.

Reference Example 8 Production of Polycarbonate Diol Under a nitrogen stream, 2-methyl-1,8-octanediol and 1,9
Charging 1,730 g of a mixture of nonanediols (molar ratio = 35: 65) and 2,140 g of diphenyl carbonate in a reactor,
The temperature was raised to 200 ° C by heating, and the generated phenol was distilled out of the system. After gradually raising the temperature to 210-220 ° C and distilling most of the phenol out of the system, the pressure inside the system was reduced to 6-10 mmHg, and the remaining phenol was completely distilled out at the same temperature under this reduced pressure. did. The polycarbonate diol thus obtained had a hydroxyl value of 56.0 and a number average molecular weight of 2,000.

Reference Examples 9 and 10 Reactions were carried out in the same manner as in Reference Example 8 except that diols giving the diol components shown in Table 1 were used and ethylene carbonate was used instead of diphenyl carbonate to obtain polycarbonate diols shown in Table 1, respectively. It was

For the polyester diols obtained in Reference Examples 1 to 7 and the polycarbonate diols obtained in Reference Examples 8 to 10, the diol components and their proportions, the dicarboxylic acid components of the polyester diols, and the number average molecular weights are summarized in Table 1. In Table 1, the diol component and the dicarboxylic acid component are represented by the diols and dicarboxylic acids shown by the following abbreviations that give them respectively.

ND: 1,9-nonanediol MOD: 2-methyl-1,8-octanediol MPD: 3-methyl-1,5-pentanediol HD: 1,6-hexanediol NPG: neopentyl glycol EG: ethylene glycol AD : Adipic acid Example 1 Production and Performance Evaluation of Polyurethane Composition A mixture of polyester diol (A) and 1,4-butane diol (hereinafter abbreviated as BD) in a molar ratio of 1: 4 was heated to 50 ° C. 4,4'-heated to 50 ℃
Diphenylmethane diisocyanate (hereinafter referred to as MDI
(Abbreviated as)) polyester diol (A) vs MDI vs BD
Was continuously charged into a secondary screw type extruder rotating in the same direction by a metering pump in an amount such that the molar ratio of was 5: 4, and a continuous melt polymerization reaction was carried out. When the inside of this twin-screw extruder was divided into three zones of a front portion, a middle portion and a rear portion, the temperature of the middle portion (polymerization temperature), which was the highest temperature, was 230 ° C. The resulting polyurethane was continuously extruded into water in the form of strands and then formed into pellets by a pelletizer.

To 100 parts of the obtained polyurethane pellets, 3 parts of AES resin (AES110, manufactured by Nippon Synthetic Rubber Co., Ltd.) and 0.5 parts of montanic acid wax (Hoechst wax OP) are added at 25 mmφ extruder (cylinder temperature 200 ° C, die temperature 180 ° C) ) And kneaded and added to form pellets. Next, an injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd.,
FS80S12ASE, cylinder temperature 175-200 ℃, nozzle temperature 20
0 ℃, mold temperature 30 ℃, injection pressure 100kg / cm ² G)
Injection molding was performed by changing the molding cycle time (injection time + cooling time) to produce a molded product (150 mm x 25 mm x 6 mm).

The molding cycle time was measured for the obtained molded product so that sink marks and deformation did not occur. Further, pellets of the above-mentioned polyurethane composition were molded according to the method described above, and heat resistance, cold resistance, flex resistance and hardness were evaluated. The evaluation results are shown in Table 2.

Comparative Example 1 Production and Performance Evaluation of Polyurethane Composition A pellet of a polyurethane composition was obtained by the same operation as in Example 1 except that the AES resin was not added, and this pellet was injection-molded in the same manner to produce a molded article. The same evaluations as in Example 1 were performed, and the evaluation results are shown in Table 2.

Examples 2 to 7 and Comparative Examples 2 to 13 Production and Performance Evaluation of Polyurethane Compositions Polyester diols or polycarbonate diols shown in Table 2 were used in place of the polyester diol (A) in Example 1, and the molar ratios shown in Table 2 were used. A polyurethane pellet was obtained by carrying out the same reaction and operation except that the polyester diol or polycarbonate diol and MDI and BD were charged. AES resin (manufactured by Japan Synthetic Rubber Co., Ltd., AES110) or ABS resin (manufactured by Japan Synthetic Rubber Co., Ltd., ABS10) is kneaded and added to these pellets at a predetermined ratio in the same manner as in Example 1.
Or to obtain a pellet of polyurethane composition without addition,
These pellets were injection-molded in the same manner to produce molded products. The same evaluations as in Example 1 were performed, and the evaluation results are shown in Table 2.

Example 8 Production and Performance Evaluation of Polyurethane Composition A polyurethane pellet was obtained by the same reaction and operation as in Example 1 except that p-phenylene diisocyanate was used instead of MDI. A pellet of the polyurethane composition was obtained from the pellet by the same operation as in Example 1, and the pellet was injection-molded in the same manner to prepare a molded article. The same evaluations as in Example 1 were performed, and the evaluation results are shown in Table 2.

Example 9 Production of polyurethane composition and performance evaluation A polyurethane pellet was obtained by performing the same reaction and operation as in Example 1 except that 1,4-bis (hydroxyethoxy) benzene was used instead of BD.
A polyurethane composition was obtained from the pellet by performing the same operation as in Example 1, and the pellet was injection-molded in the same manner to prepare a molded article. The same evaluations as in Example 1 were performed, and the evaluation results are shown in Table 2.

[Effect of the Invention] As is clear from Table 2 above, the thermoplastic polyurethane composition provided by the present invention is excellent in all of heat resistance, injection moldability, cold resistance, flex resistance, and hardness.
The composition is also excellent in oil resistance, wear resistance, toughness and mechanical performance.

Front page continuation (72) Inventor Setsuo Yamashita, 1621 Sakata, Kurashiki, Okayama Prefecture, Kuraray Co., Ltd. (72) Inventor, Koji Hirai, 1621 Sakata, Kurashiki, Okayama, Kuraray Co., Ltd. (56) References 1-121359 (JP, A) JP-A 1-121349 (JP, A) JP-A-57-14641 (JP, A) JP-A-57-8245 (JP, A) JP-A-3-35054 (JP, A) A)

Claims (2)

[Claims] (A) 92 to 99% by weight of (A) thermoplastic polyurethane
And (B) 8 to 1% by weight of the thermoplastic graft polymer, and the thermoplastic polyurethane has (a) the following structural units (I) and (II) and / or (III) as essential structural units. Is obtained from a polyester diol and / or a polycarbonate diol having a number average molecular weight of 1,500 to 3,500, and (b) diisocyanate and (c) a chain extender, and the sum of the weights of components (b) and (c) is It is in the range of 23 to 56% based on the sum of the weights of components (a), (b) and (c), and the thermoplastic graft polymer is obtained by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound on an elastomer. A thermoplastic polyurethane composition, which is the obtained polymer. (I): - O- (CH 2) 9 -O- 2. The sum of the mole fractions of the structural units (II) and (III) in the polyester diol and the polycarbonate diol is 10% or more with respect to the sum of the mole fractions of the structural units (I) to (III). The thermoplastic polyurethane composition according to claim 1, wherein the sum of the mole fractions of the structural units (I) and (II) is 50% or more with respect to the sum of the mole fractions of the diol-derived structural units.