JP2765971B2 - Thermoplastic polyurethane composition - Google Patents

Description

The present invention relates to a composition comprising a specific thermoplastic polyurethane and a small amount of a thermoplastic resin. The composition provided by the present invention has excellent injection moldability,
Excellent in water resistance, cold resistance and mechanical performance.

[Conventional technology]

Conventionally, thermoplastic polyurethane has many features such as high elastic modulus and excellent abrasion resistance and oil resistance, so it has been attracting attention as a substitute for rubber and plastic, and ordinary plastic molding method is applied. It is becoming increasingly used in a wide range of applications as a possible molding material. Thermoplastic polyurethane is produced by mixing and polymerizing a chain extender such as a polymer diol, diisocyanate and 1,4-butanediol.

As the thermoplastic polyurethane, polyester-based polyurethane, polyether-based polyurethane, and polycarbonate-based polyurethane are known, and are used for various applications by making use of their respective features. Of these, polyester-based polyurethane has excellent mechanical performance,
It is known that water resistance is poor.

For the purpose of improving the release property (prevention of tackiness) during molding of thermoplastic polyurethane and reducing the molding shrinkage, a copolymer or blend polymer of 99 to 50% by weight of thermoplastic polyurethane and acrylonitrile-styrene is used. It has been proposed to blend 50% by weight (see Japanese Patent Publication No. 46-659), to improve the release property (prevention of tackiness) during molding of thermoplastic polyurethane and to improve the temperature dependence of melt viscosity. For the purpose of reducing the size, a resin 10 to 90 obtained by graft polymerization of an aromatic vinyl compound and a vinyl cyanide compound to 90 to 10% by weight of a thermoplastic polyurethane and ethylene-propylene rubber is used.
% By weight (Japanese Patent Publication No. 60-17)
281 and Japanese Patent Publication No. 62-34265). Also,
In order to improve the moldability of thermoplastic polyurethane,
It has been proposed to blend 1 to 30% by weight of an acrylonitrile-styrene-butadiene terpolymer or ternary blend polymer with 99 to 70% by weight of a thermoplastic polyurethane (see Japanese Patent Publication No. 54-7927). .

[Problems to be solved by the invention]

Conventional thermoplastic polyurethanes have a long injection molding cycle time, are inferior in productivity, and have problems in injection moldability such as generation of sink marks. Improvements in these are strongly desired.

The thermoplastic polyurethane composition in which a resin obtained by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound to the ethylene-propylene rubber is blended with a large amount of a graft polymer. While the adhesiveness is improved, there is a problem that the inherent characteristics of the thermoplastic polyurethane such as an increase in hardness, a decrease in elongation and a decrease in flex resistance are lost. Further, a thermoplastic polyurethane composition containing an acrylonitrile-styrene copolymer or a blend polymer and a thermoplastic polyurethane composition containing an acrylonitrile-styrene-butadiene terpolymer or a ternary blend polymer are other. In fact, the molding processability has not been improved to a satisfactory level without the problem described above.

An object of the present invention is to provide a thermoplastic polyurethane composition which is excellent in water resistance, cold resistance, mechanical performance and the like and is excellent in injection moldability.

[Means for solving the problem]

According to the present invention, the object is to provide a thermoplastic polyurethane containing from 92 to 99% by weight of (A) a thermoplastic polyurethane and (B) a thermoplastic resin containing an aromatic vinyl compound and a vinyl cyanide compound as essential components. % Of the thermoplastic polyurethane, wherein (a) a polyester diol having a number average molecular weight of 1,500 to 3,500, (b) diisocyanate and (c)
A chain extender, and the sum of the weights of components (b) and (c) is in the range of 13-40% relative to the sum of the weights of components (a), (b) and (c); The polyester diol has the following structural units (I) and / or (II) as essential structural units derived from diol, and the following structural units (III) and (IV) as essential structural units derived from dicarboxylic acid. And the ratio of the mole fraction of the structural unit (I) to the mole fraction of the structural unit (II) is in the range of 100: 0 to 50:50, and the mole fraction of the structural unit (III) is Structural unit (I
This is achieved by providing a thermoplastic polyurethane composition characterized in that the molar fraction ratio of V) is in the range from 80:20 to 35:65.

(In the formula, n represents an integer of 4 to 12, and Ar represents a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms.) In the composition of the present invention, the injection molding cycle speed is high and the molding strain rate is high. Is small, and mechanical properties, water resistance, properties such as excellent cold resistance etc. are expressed in hardness,
It is important that the thermoplastic plastic polyurethane has the above specified structure. In the case of the thermoplastic polyurethane composition not having the specified structure, the effect of the composition of the present invention is hardly observed.

It is extremely important that the polyester diol constituting the thermoplastic polyurethane in the present invention has a number average molecular weight in the range of 1,500 to 3,500 determined from the hydroxyl value and the acid value. The number average molecular weight is particularly 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 the injection molding cycle speed and molding strain rate is observed, and when it exceeds 3,500, the change in melt viscosity during molding is large, making stable molding difficult. .

The polyester diol has the structural units (I) and / or (II) as essential structural units derived from diol, and has the structural units (III) and (IV) as essential structural units derived from dicarboxylic acid. .

As a typical compound giving the structural unit (I), 1,9-
Nonanediol is exemplified, and a typical compound that provides the structural unit (II) is 2-methyl-1,8-octanediol. The higher the proportion of the structural unit (I) and / or (II) in the diol-derived structural unit, the higher the composition exhibiting the above-mentioned excellent properties. The proportion of the structural unit (I) and / or (II) in the diol-derived structural unit is preferably 30% by weight or more, more preferably 50% by weight or more. When the structural unit derived from a diol is the structural unit (I) and / or
Or, the case of only consisting of (II) is particularly preferred. The ratio of the mole fraction of the structural unit (I) to the mole fraction of the structural unit (II) is
The range is from 100 to 0 to 50 to 50. When the mole fraction of the structural unit (II) is higher than the mole fraction of the structural unit (I),
Poor heat resistance and cold resistance of the composition. Examples of the diol used in the production of the polyester diol in the present invention include ethylene glycol, propylene glycol, 1,4-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, and 3-methyl-1, Five
-Pentanediol, 1,6-hexanediol, 1,10-
Decanediol and the like. These diols are used alone or in a mixture of two or more.

Examples of the aliphatic dicarboxylic acid giving the structural unit (III) include adipic acid, azelaic acid, sebacic acid, dodecane diacid, and the like, with adipic acid and azelaic acid being preferred. These aliphatic dicarboxylic acids are used alone or in a mixture of two or more. The divalent aromatic hydrocarbon group having 6 to 12 carbon atoms represented by Ar in the structural unit (IV) is specifically a phenylene group or a naphthylene group.
As the aromatic dicarboxylic acid giving the structural unit (IV),
Terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-
Examples include naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid, and isophthalic acid and terephthalic acid are preferred. These aromatic dicarboxylic acids are used alone or in a mixture of two or more. The ratio of the mole fraction of structural unit (III) to the mole fraction of structural unit (IV) is in the range from 80:20 to 35:65. The molar fraction of the structural unit (III) is
Compositions obtained from polyester diols exceeding 80% based on the sum of the molar fraction of V) do not exhibit the above-mentioned excellent properties in the present invention. If the molar fraction of the structural unit (IV) and the molar fraction of the structural unit (III) are more than 65%, the injection moldability and cold resistance of the composition will be reduced.

The polyester diol in the present invention is produced by, for example, a method similar to a known method used in the production of polyethylene terephthalate or polybutylene terephthalate, that is, a transesterification reaction or a direct esterification reaction followed by a melt polycondensation reaction.

In the thermoplastic polyurethane of the present invention, the sum of the weights of the components (b) and (c), that is, the weight of the hard segment component is 13 to 40 with respect to the sum of the weights of the components (a), (b) and (c). It is important to be in the% range. When the weight of the hard segment component is less than 13%, the effect of improving the injection moldability of the composition is small, and
If the ratio exceeds the above range, the change in the melt viscosity of the composition with time will be large, and the moldability will be poor.

The thermoplastic polyurethane of the present invention is obtained by melt-polymerizing a polyester diol, a diisocyanate, and a chain extender. The diisocyanate used is an aliphatic, alicyclic or aromatic diisocyanate containing two isocyanate groups in the molecule, for example, 4,4′-diphenylmethane diisocyanate, p −
Phenylene diisocyanate, tolylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexyl methane diisocyanate and the like. . As the diisocyanate, 4,4'-diphenylmethane diisocyanate is particularly preferred. As the chain extender, a conventional chain growing agent in the polyurethane industry, that is, a low molecular weight compound having a molecular weight of 400 or less containing at least two hydrogen atoms capable of reacting with isocyanate can be used, for example, ethylene glycol, propylene glycol, 1,4-
Butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,
4-cyclohexanediol, xylylene glycol,
Polyols such as 1,4-bis (β-hydroxyethoxy) benzene, bis (β-hydroxyethyl) terephthalate, trimethylolpropane, and glycerin; ethylenediamine, propylenediamine, xylylenediamine,
4'-diaminodiphenylmethane, 3,3'-dichloro-4,
Diamines such as 4'-diaminodiphenylmethane, isophoronediamine, piperazine, phenylenediamine and tolylenediamine; hydrazine; hydrazides such as adipic dihydrazide and isophthalic dihydrazide; Most preferably, 1,4-butanediol or 1,4-bis (β-hydroxyethoxy) benzene is used as the chain extender. These compounds are used alone or in combination of two or more. As the polymerization conditions, those known in the art for the urethane formation reaction are applied, and the polymerization temperature is preferably in the range of 200 to 240 ° C. By maintaining the polymerization temperature at 200 ° C. or higher, a polyurethane having good moldability can be obtained. By maintaining the polymerization temperature at 240 ° C. or lower, a polyurethane having increased heat resistance can be obtained. As the polymerization method, it is particularly preferable to employ a continuous melt polymerization method using a multi-screw extruder.

In the composition of the present invention, the thermoplastic polyurethane having an aromatic vinyl compound and a vinyl cyanide compound as essential components is blended with the thermoplastic polyurethane having the above-mentioned specified structure at a specific ratio. It is an important requirement to achieve the above object of the invention. In the present invention, it is necessary to blend 92 to 99% by weight of the thermoplastic polyurethane and 8 to 1% by weight of the above-mentioned thermoplastic resin. If the blending ratio of the thermoplastic resin is less than 1% by weight, the effect of the present invention is hardly exhibited, and if it exceeds 8% by weight, the composition becomes too high and the elongation decreases. Therefore, when comparing a composition having an elevated height in which the blending ratio of the thermoplastic resin is more than 8% by weight with a composition of the present invention having the same hardness, the former composition is harder than polyurethane. The segment content is lower than that of the latter composition, no improvement in injection moldability is observed compared to the latter composition, and the bending resistance is also reduced, the original characteristics of the thermoplastic polyurethane are impaired, The use is limited.

Examples of the thermoplastic resin containing an aromatic vinyl compound and a vinyl cyanide compound as essential components in the present invention include, for example, a copolymer or a blend polymer of an aromatic vinyl compound and a vinyl cyanide compound (hereinafter referred to as AS Resin), elastomer (graft base)
And a thermoplastic graft polymer obtained by graft polymerization of an aromatic vinyl compound and a vinyl cyanide compound (graft monomer). As the aromatic vinyl compound, for example, styrene, α-methylstyrene, nucleus alkyl-substituted styrene, nucleus halogen-substituted styrene and the like are used. Particularly, it is preferable to use styrene. Further, as the vinyl cyanide compound, for example, acrylonitrile, methacrylonitrile and the like are used. In particular, it is preferable to use acrylonitrile. As the above-mentioned elastomer for the graft substrate, it is preferable to use an elastomer having a secondary transition temperature lower than -30 ° C.

Representative examples of the AS resin include a copolymer obtained by emulsion polymerization of styrene and acrylonitrile, and a blend polymer obtained by blending a homopolymer of styrene and a homopolymer of acrylonitrile. A copolymer is preferable as the AS resin. The proportion of the aromatic vinyl compound and the vinyl cyanide compound used is not particularly limited, but the former is in the range of 60 to 90% by weight, and the latter is in the range of 40 to 90% by weight.
Preferably it is in the range of 10% by weight.

Examples of the thermoplastic graft polymer include a resin obtained by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound onto an ethylene-propylene rubber (hereinafter, this resin is abbreviated as AES resin). 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 9: 1 ~
A range of 2: 8 is preferred. Examples of the diene monomer include norbornenes such as alkenyl norbornene, cyclic dienes such as dicyclopentadiene, and aliphatic dienes such as hexadiene. The diene monomers are used alone or in combination of two or more. Ethylene-
Propylene rubber and aromatic vinyl compound, the weight ratio of vinyl compound used for graft polymerization such as vinyl cyanide compound is suitably in the range of 5:95 to 50:50, 10:90 to 50:50
A range of 40:60 is preferred. AES resins are produced by bulk polymerization, emulsion polymerization, solution polymerization, bulk-suspension polymerization, suspension polymerization, emulsion-suspension polymerization, and the like.

Further, as a thermoplastic graft polymer, for example, a copolymer obtained by adding both acrylonitrile and styrene graft monomers to a latex of a butadiene polymer and emulsion-polymerizing the same, an acrylonitrile-butadiene copolymer, a styrene-acrylonitrile copolymer, and styrene −
Blend polymers obtained by blending with an acrylonitrile copolymer (hereinafter, these are collectively referred to as ABS resins) are exemplified. As the latex of the butadiene polymer, for example, polybutadiene latex, acrylonitrile-butadiene copolymer latex, styrene-
Butadiene copolymer latex or the like is used. The proportion of each of the above components is 5 to 50% by weight of butadiene,
20-85% by weight, acrylonitrile 5-40% by weight.

The thermoplastic polyurethane composition of the present invention can be prepared, for example, by using the above-mentioned thermoplastic polyurethane and a thermoplastic resin containing an aromatic vinyl compound and a vinyl cyanide compound as essential components in a longitudinal direction which is usually used for mixing a resin material. It is manufactured by premixing at a predetermined ratio using a mold or horizontal mixer, followed by heating and kneading in a batch or continuous manner using a single-screw or twin-screw extruder, mixing roll, Banbury mixer, or the like. . Additives such as stabilizers, plasticizers, waxes of montanic acid, aliphatic amides, lubricants such as aliphatic amides, fillers, antistatic agents and pigments for further improving light resistance and heat resistance during mixing impair the effects of the present invention. It is possible to add in an unacceptable amount.

The thermoplastic polyurethane composition of the present invention is particularly excellent in molding processability including injection moldability, and can be easily molded by commonly used injection molding machines, extrusion molding machines, blow molding machines, calenders and the like. . Since the thermoplastic polyurethane composition of the present invention has high molding dimensional accuracy, and has excellent heat resistance, cold resistance, oil resistance, abrasion resistance, toughness and mechanical performance, sheets, films, rolls, Gears, solid tires, snow tires, snow chains, belts, watch bands, hoses, tubes, packing agents, anti-vibration materials, shoe soles, sports shoes, and other laminated product materials, machine parts, automotive parts, sports equipment, elastic fibers Used for etc. Further, the thermoplastic polyurethane composition of the present invention is dissolved in a solvent and used for artificial leather, a coating agent, a fiber treatment agent, an adhesive, a binder, a paint, and the like.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

In the reference examples, the number average molecular weight was determined according to the following method. In the examples and comparative examples, the injection moldability (molding cycle time), mechanical performance, water resistance and cold resistance of the thermoplastic polyurethane composition were evaluated according to the following methods. The hard segment content of the thermoplastic polyurethane means the weight percentage 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 the polyester diol.

(2) Injection moldability: Injection molding was performed while changing the molding cycle time (injection time + cooling time), and the molding cycle time at which sink and deformation did not occur from the obtained molded article was measured.
Thereby, injection moldability was evaluated.

(3) Mechanical performance: A 100 μm thick film obtained by compression molding a pellet of the polyurethane composition was punched out with a No. 3 dumbbell, and the breaking strength and breaking elongation were measured at a tensile speed of 30 cm / min. Thereby, the mechanical performance was evaluated.

(4) Water resistance: A 100 μm-thick film obtained by compression-molding a pellet of the polyurethane composition was placed in hot water at 100 ° C. and subjected to a hydrolysis promotion test for 2 weeks. Water resistance was evaluated by the tensile strength retention.

(5) Cold resistance: A test piece prepared from a 100 μm-thick polyurethane composition film was subjected to Tα (E ″) by temperature dispersion using a dynamic viscoelasticity measuring device (DVE Rheospectral, manufactured by Rheology Co., Ltd.). , Peak temperature of 11 Hz), thereby evaluating cold resistance.

Reference Example 1 Production of Polyester Diol 2,080 g of a mixture of 1,9-nonanediol and 2-methyl-1,8-octanediol (molar ratio = 95: 5) and a mixture of adipic acid and isophthalic acid (molar ratio = 50) : 50) 1,560g
(Molar ratio of diol and adipic acid = 1.3: 1.0) was charged into the reactor, and while condensing water from the system while gradually increasing the reaction temperature from 160 ° C to 220 ° C while passing nitrogen gas into the system under normal pressure. Evaporation was carried out to carry out an esterification reaction. When the acid value of the polyester became 0.5 or less, the degree of vacuum was gradually increased by a vacuum pump to complete the reaction. The polyester diol thus obtained had a hydroxyl value of 55.8, an acid value of 0.3, and a number average molecular weight of about 2,000.

Reference Examples 2 to 11 Production of Polyester Diol An esterification reaction was carried out in the same manner as in Reference Example 1 except that a dicarboxylic acid giving a dicarboxylic acid component shown in Table 1 and a diol giving a diol component were used. The diol was obtained.

For the polyester diols obtained in Reference Examples 1 to 11, the diol component and its ratio, a dicarboxylic acid component,
Table 1 summarizes the number average molecular weight. In Table 1, the diol component and the dicarboxylic acid component are represented by diols and dicarboxylic acids indicated by the following abbreviations, which provide these components.

MOD: 2-methyl-1,8-octanediol ND: 1,9-nonanediol HD: 1,6-hexanediol AD: adipic acid AZA: azelaic acid SA: sebacic acid IPA: isophthalic acid TA: terephthalic acid Example 1 Production of Polyurethane Composition and Performance Evaluation A mixture of polyester diol (A) and 1,4-butanediol (hereinafter abbreviated as BD) at a molar ratio of 1: 2 was heated to 30 ° C. 4,4 'heated and melted to 50 ° C
-Diphenylmethane diisocyanate (hereinafter referred to as MD
I) for polyester diol (A) vs. MDI vs. BD
Was continuously charged into a twin-screw extruder rotating in the same direction by a metering pump at a molar ratio of 1: 3: 2 to carry out a continuous melt polymerization reaction. When the inside of the twin-screw extruder was divided into three zones of a front portion, an intermediate portion and a rear portion, the temperature (polymerization temperature) of the intermediate portion, which was the highest, was 220 ° C. The resulting polyurethane was continuously extruded into water in the form of a strand, and then formed into a pellet with a pelletizer.

100 parts of the obtained polyurethane were mixed with 3 parts of AS resin (Stylac-AS769, manufactured by Asahi Kasei Corporation) and 0.5 part of montanic acid wax (Hoechstwax OP) for 25 m.
mφ extruder (cylinder temperature 200 ° C, die temperature 180 ° C)
And kneaded and pelletized. Then, the Peretsuto of the resulting polyurethane composition an injection molding machine (Nissei Plastic Industrial Co., Ltd., FS ₈₀ S ₁₂ ASE, cylinder temperature 175-200 ° C.,
Nozzle temperature 200 ° C, mold temperature 30 ° C, injection pressure 100kg / cm
With ² G), and injection molding by changing the molding cycle time (injection time + cooling time), the molded article (150 mm × 25 mm × 6 mm)
It was created.

With respect to the obtained molded article, a molding cycle time at which sink and deformation did not occur was measured. Further, the pellet of the polyurethane composition is molded according to the method described above,
Mechanical performance, water resistance and cold resistance were evaluated. Table 2 shows the evaluation results.

The above polyurethane composition had good injection moldability, mechanical properties, water resistance and cold resistance.

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 AS resin was not added, and the pellet was injection-molded in the same manner to produce a molded product. The same evaluation as in Example 1 was performed, and the evaluation results are shown in Table 2. The injection moldability was extremely poor.

Examples 2 to 7 and Comparative Examples 2 to 13 Production and Performance Evaluation of Polyurethane Composition In Example 1, polyester diol shown in Table 2 was used in place of polyester diol (A), and polyester diol was used in a molar ratio shown in Table 2. The reaction and operation were carried out in the same manner except that MDI and BD were charged to obtain a pellet of polyurethane. AS resin (as described above), AES resin (manufactured by Nippon Synthetic Rubber Co., Ltd., AES ₁₁₀ ) or ABS resin (Nippon Synthetic Rubber Co., Ltd., ABS ₁₀ ) were used in these pellets in the same manner as in Example 1. Pellets of the polyurethane composition were obtained with or without kneading at a predetermined ratio, and the pellets were injection-molded in the same manner to produce molded articles. The same evaluation as in Example 1 was performed, and the evaluation results are shown in Table 2.

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

Continuation of the front page (72) Inventor Koji Hirai 1621 Sazu, Kurashiki City, Okayama Prefecture Kuraray Co., Ltd. Examiner Takeshi Sato (56) References JP-A-2-281073 (JP, A) (58) Int.Cl. ⁶ , DB name) C08L 75/06 C08G 18/42

Claims (1)

(57) [Claims] (A) 92 to 99% by weight of a thermoplastic polyurethane
And thermoplastic resins 8 to 1 containing (B) an aromatic vinyl compound and a vinyl cyanide compound as essential constituents
% Of the thermoplastic polyurethane obtained from (a) a polyesterdiol having a number average molecular weight of 1,500 to 3,500, (b) a diisocyanate and (c) a chain extender, and the components (b) and (c) ) Is 13 to 40 with respect to the sum of the weights of components (a), (b) and (c).
%, And the polyester diol has the following structural units (I) and / or (II) as essential structural units derived from diol, and the following structural unit (III) as essential structural units derived from dicarboxylic acid. ) And (IV), and the molar fraction of the structural unit (I) and the structural unit (I
The ratio of the mole fraction of I) is in the range of 100: 0 to 50:50, and the ratio of the mole fraction of the structural unit (III) to the mole fraction of the structural unit (IV) is 80:20 to 35:65. A thermoplastic polyurethane composition characterized by the following range: (In the formula, n represents an integer of 4 to 12, and Ar represents a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms.)