JP2006063129A - Thermoplastic polyurethane resin composition - Google Patents

Abstract

An object of the present invention is to have excellent melting characteristics, thermoforming, suitable hardness for various applications, excellent yellowing resistance, hardly causing oligomer-derived substances to precipitate on the surface, and water resistance. To provide a thermoplastic polyurethane resin composition capable of obtaining an excellent molded product.
A polymer polyol containing a polyester polyol having a hydroxyl value of 20 to 120 obtained from 2-methyl-1,3-propanediol and adipic acid, a chain extender containing 1,6-hexanediol, and HDI. A thermoplastic polyurethane resin obtained by reacting polyisocyanate at a specific ratio; a hydrolysis inhibitor; and a thermoplastic resin composition containing an antioxidant, and a molded product obtained by thermoforming this thermoplastic resin composition Hardness is 80-95 in JIS-A hardness.
[Selection figure] None

Description

  The present invention relates to a thermoplastic polyurethane resin composition. More specifically, the present invention has excellent melting characteristics. By thermoforming the thermoplastic polyurethane resin composition, the composition is excellent in yellowing resistance and hardly causes oligomer-derived substances to precipitate on the surface. It is related with the thermoplastic polyurethane resin composition which can obtain the molded article excellent also in the property.

For example, tubes, films, sheets, belts, hoses, screens, casters, gears, packing, automotive parts, squeegees, paper feed rolls, etc., copier cleaning blades, snow plows, chains, solid tires, anti-vibration materials Thermoplastic polyurethane resin compositions are widely used as materials for molding articles such as shoe soles, sports shoes, and machine parts.
Articles used for the above applications (molded products obtained by thermoforming a thermoplastic polyurethane resin composition) are durable in the environment of use (for example, due to their flexibility, they are not damaged by vibration or impact). From the viewpoint of the performance to prevent, a certain hardness (JIS-A hardness 80 to 95) is required.

  On the other hand, aliphatic thermoplastic polyurethane resin compositions obtained using aliphatic polyisocyanates are known as thermoplastic polyurethane resin compositions that are stable to light and excellent in yellowing resistance (for example, See Patent Document 1 below).

  However, in a molded product formed by thermoforming an aliphatic thermoplastic polyurethane resin composition, a substance derived from an oligomer precipitates on the surface (bloom or bleed) during storage, and the surface There is a problem that a white layer is formed on a part or the whole of the substrate.

  In response to such problems, the following are introduced as thermoplastic polyurethane resin compositions that can suppress deposits on the surface of the molded product.

  (A) one or more aliphatics selected from the group consisting of polyadipate, polycaprolactone, polycarbonate, polytetrahydrofuran and copolymers corresponding to these, having a molecular weight of 450 to 4000 and a hydroxyl value of 20 to 235 Produced by reaction of a mixture of a polyol with 1,6-hexamethylene diisocyanate and a chain extender selected from the group consisting of 1,5-pentanediol, 1,6-hexanediol and 1,4-cyclohexanediol. The equivalent ratio of 1,6-hexamethylene diisocyanate to polyol is in the range of 1: 1.5 to 1: 14.0, and the equivalent ratio of isocyanate groups to the total of hydroxyl groups of the polyol and chain extender is multiplied by 100. Isocyanate index in the range of 96-105 Thermoplastic polyurethane resin composition in (see Patent Document 2).

  (B) Diisocyanate reactant containing 100 to 60 mol% of hexamethylene diisocyanate and 0 to 40 mol% of other aliphatic diisocyanate; 100 to 30% by mass of polytetramethylene and other polyols 0 to 0 of number average molecular weight 600 to 5000 A polyol reactant containing 70% by weight; and a chain extender reaction product containing 0-100% by weight of 1,6-hexanediol and 0-20% by weight of other chain extenders having a number average molecular weight of 60-500. A thermoplastic polyurethane resin composition (see Patent Document 3 below).

However, a molded article obtained by thermoforming the thermoplastic polyurethane resin composition (a) or (b) does not have sufficient water resistance and cannot be used for applications where this is required. In addition, the thermoplastic polyurethane resin composition (b) or (b) is not suitable as a material for injection molding because of poor melting characteristics.
JP 10-1110025 A JP 2000-355619 A JP 2001-354748 A

  The present invention has been made on the basis of the circumstances as described above, and its purpose is excellent in melting characteristics, and by thermoforming this, a hardness suitable for various applications (80 to JIS-A hardness). 95), an excellent yellowing resistance, an oligomer-derived substance hardly deposits on the surface, and a thermoplastic polyurethane resin composition capable of obtaining a molded product excellent in water resistance. There is.

The thermoplastic polyurethane resin composition of the present invention is a polyester polyol having a hydroxyl value of 20 to 120 obtained from 2-methyl-1,3-propanediol and adipic acid (hereinafter also referred to as “specific polyester polyol”). A polymer polyol (a1) containing 50 to 100% by mass, a chain extender (a2) containing 1,6-hexanediol at a rate of 50 to 100% by mass, and 50 to 100% by mass of hexamethylene diisocyanate. Thermoplastic polyurethane resin (hereinafter referred to as “polyurethane resin (A)”) produced by reaction of polyisocyanate (a3) contained in a proportion; a hydrolysis inhibitor; and a thermoplastic resin composition containing an antioxidant a is the number of active hydrogen groups molar included in the polymer polyol (a1) [m _1], wherein the chain extender (A2) [m _2] of active hydrogen group mole number possessed by, when the number of moles of isocyanate groups and [m _3] having the said polyisocyanate (a3), [m _3] / ([m _1] + [m ₂ ]) (R value) is 0.9 to 1.2, and [m ₁ ] / [m ₂ ] value (R ′ value) is 0.1 to 15.0, The hardness of the molded product obtained by thermoforming the resin composition is 80 to 95 in terms of JIS-A hardness.

The thermoplastic polyurethane resin composition of the present invention is excellent in melting characteristics. That is, when the temperature of the resin composition in a solidified state is raised, when the temperature reaches a certain temperature (usually the flow start temperature), the melt viscosity of the resin composition decreases sharply and is used for injection molding. Suitable fluidity is developed.
By thermoforming the thermoplastic polyurethane resin composition of the present invention, it has a hardness suitable for various applications (JIS-A hardness 80 to 95), is excellent in yellowing resistance, and has an oligomer-derived substance on the surface. It is possible to obtain a molded product that hardly precipitates and is excellent in water resistance.

  The thermoplastic polyurethane resin composition of the present invention contains a polyurethane resin (A), a hydrolysis inhibitor and an antioxidant as essential components.

<Polyurethane resin (A)>
The polyurethane resin (A) constituting the thermoplastic polyurethane resin composition of the present invention includes a polymer polyol (a1) mainly composed of a specific polyester polyol and a chain extender mainly composed of 1,6-hexanediol. It is produced by a reaction between (a2) and polyisocyanate (a3) containing hexamethylene diisocyanate as a main component.

<Polymer polyol (a1)>
The polymer polyol (a1) used for obtaining the polyurethane resin (A) contains a specific polyester polyol as a main component (50% by mass or more).
In the present invention, the molecular weight of the polyol (including a specific polyester polyol) constituting the polymer polyol (a1) is 400 to 10,000, preferably 1,000 to 5,000.

The specific polyester polyol constituting the polymer polyol (a1) is a copolymer of 2-methyl-1,3-propanediol and adipic acid.
By using a specific polyester polyol, excellent melting characteristics are expressed in the obtained thermoplastic polyurethane resin composition, and excellent water resistance is expressed in the resulting molded product.
Such excellent performance is due to the adoption of 2-methyl-1,3-propanediol as a component (diol) for forming polyester.

  The hydroxyl value of the specific polyester polyol is usually 20 to 120, preferably 30 to 80. When this hydroxyl value is too small (molecular weight is too large), it becomes difficult to set the hardness of the molded product of the resin composition to 80 to 95 (JIS-A). Viscosity is excessive and inferior in homogenous mixing properties. Furthermore, severe reaction conditions are required to obtain a resin composition. On the other hand, even when the hydroxyl value is excessive (molecular weight is excessively low), it is difficult to set the hardness of the molded product of the resin composition to 80 to 95 (JIS-A).

  The polymer polyol (a1) is preferably composed of only a specific polyester polyol, but other types of polyols can be used in combination as long as the effects of the present invention are not impaired. Examples of the polyol used in combination include polyesters, polyesteramides, polyethers, polyetheresters, and polycarbonates having a molecular weight of 400 to 10,000.

Polyesters and polyesteramides constituting the polymer polyol (a1) as an optional component can be obtained by a condensation reaction from polyhydric alcohols and polyhydric carboxylic acids, optionally in combination with diamines or aminoalcohols. Things.
Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol (adipic acid And 3-methyl-1,5-pentanediol, neopentyl glycol, 2-methyloctanediol, 1,9-nonanediol, 1,4-cyclohexanedimethanol, and the like.
Examples of the polyvalent carboxylic acid include oxalic acid, adipic acid (excluding a combination with 2-methyl-1,3-propanediol), sebacic acid, dimer acid, hydrogenated dimer acid, phthalic acid, and phthalic acid alkyl ester. , Maleic acid, fumaric acid, itaconic acid and the like. Further, those obtained by ring-opening polymerization of cyclic esters such as butyrolactone, valerolactone and caprolactone are also included.

  Examples of the polyether constituting the high-molecular polyol (a1) include polymerization products such as tetrahydrofuran, propylene oxide, and ethylene oxide, copolymerization products thereof, or graft polymers of a polyether vinyl monomer. Is mentioned.

  The polyether ester constituting the polymer polyol (a1) is the same as the polyester except that the polyether is used for a part or all of the polyhydric alcohol used in the condensation reaction when the polyester is obtained. Can be obtained.

  Polycarbonates constituting the polymer polyol (a1) include esters of diols such as 1,6-hexanediol and 1,4-cyclohexanedimethanol with cyclic carbonates such as dialkyl carbonate, diaryl carbonate, and ethylene carbonate. What is obtained by an exchange reaction is mentioned.

  The ratio of the specific polyester polyol in the polymer polyol (a1) is 50 to 100% by mass, preferably 80 to 100% by mass, and particularly preferably 100% by mass. When the ratio of the specific polyester polyol is less than 50% by mass, the resulting thermoplastic polyurethane resin composition cannot exhibit sufficient melting characteristics, and molding obtained by such a resin composition The product cannot exhibit sufficient water resistance.

<Chain extender (a2)>
The chain extender (a2) used for obtaining the polyurethane resin (A) contains 1,6-hexanediol as a main component (50% by mass or more).
By using the chain extender (a2) mainly composed of 1,6-hexanediol, in the molded article of the obtained thermoplastic polyurethane resin composition, it is suppressed that the oligomer-derived substance is deposited on the surface, It is reliably prevented that a white layer due to precipitates is formed on the surface of the molded article.

The chain extender (a2) is preferably composed only of 1,6-hexanediol, but other compounds can be used in combination as long as the effects of the present invention are not impaired.
Here, examples of the compound (chain extender) used in combination include ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,9-nonanediol, bis-β-hydroxyethoxybenzene, Examples include compounds having a molecular weight of less than 400, such as 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, N-phenyldiisopropanolamine, and monoethanolamine. These can be used alone or in combination of two or more.

  The proportion of 1,6-hexanediol in the chain extender (a2) is 50 to 100% by mass, preferably 80 to 100% by mass, and particularly preferably 100% by mass. When the proportion of 1,6-hexanediol is less than 50% by mass, surface precipitation of the substance derived from the oligomer cannot be sufficiently suppressed in the molded article of the obtained thermoplastic polyurethane resin composition.

<Polyisocyanate (a3)>
The polyisocyanate (a3) used for obtaining the polyurethane resin (A) contains hexamethylene diisocyanate as a main component (50% by mass or more).
By using the polyisocyanate (a3) containing hexamethylene diisocyanate as a main component, a thermoplastic polyurethane resin composition (molded product) excellent in yellowing resistance (light stability) can be obtained.

The polyisocyanate (a3) is preferably composed only of hexamethylene diisocyanate, but other polyisocyanates can be used in combination as long as the effects of the present invention are not impaired.
Examples of the polyisocyanate used here include aliphatic diisocyanates such as dodecane diisocyanate and trimethyl-hexamethylene diisocyanate; fats such as cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and norbornane diisocyanate methyl. Cyclic diisocyanate; Isocyanate group-terminated compound by reaction of polyisocyanate with active hydrogen group-containing compound; Polyisocyanate modified by reaction of polyisocyanate (for example, carbodiimidization reaction); Blocking agent having one active hydrogen in the molecule ( For example, methanol, n-butanol, benzyl alcohol, ethyl acetoacetate, ε-caprolactam, methyl ethyl Ton'okishimu, phenol, partly in cresol, etc.) can be mentioned stabilized polyisocyanate.

  The proportion of hexamethylene diisocyanate in the polyisocyanate (a3) is 50 to 100% by mass, preferably 80 to 100% by mass, and particularly preferably 100% by mass. When the ratio of hexamethylene diisocyanate is less than 50% by mass, sufficient yellowing resistance cannot be expressed in the molded article of the obtained thermoplastic polyurethane resin composition.

  The polyurethane resin (A) constituting the thermoplastic polyurethane resin composition of the present invention includes a polymer polyol (a1) mainly composed of a specific polyester polyol and a chain extender mainly composed of 1,6-hexanediol. It is produced by a reaction between (a2) and polyisocyanate (a3) containing hexamethylene diisocyanate as a main component.

The ratio of the polymer polyol (a1), the chain extender (a2), and the polyisocyanate (a3) used in the formation reaction of the polyurethane resin (A) is the number of moles of active hydrogen groups that the polymer polyol (a1) has. When [m ₁ ], the number of moles of active hydrogen groups possessed by the chain extender (a2) is [m ₂ ], and the number of moles of isocyanate groups possessed by the polyisocyanate (a3) is [m ₃ ], [m ₃ ] / ([M ₁ ] + [m ₂ ]) value (R value) is 0.9 to 1.2, and [m ₁ ] / [m ₂ ] value (R ′ value) is 0. It is set as the ratio which is 1-15.0.

  When the R value is less than 0.9 (the number of active hydrogen groups is excessive), the resulting resin composition has adhesiveness, and blocking tends to occur when it is pelletized (flaked). . On the other hand, when the R value exceeds 1.2 (isocyanate groups are excessive), the hardness of the molded product of the obtained resin composition becomes excessive, the molded product has brittleness, and its durability is significantly reduced. .

  When the R ′ value is less than 0.1 (the chain extender is excessive), the resulting thermoplastic polyurethane resin composition cannot exhibit sufficient melting properties, and such a resin composition The hardness of the molded product obtained by the above becomes excessive. On the other hand, when the R ′ value exceeds 15.0 (the polymer polyol is excessive), the resulting molded product of the thermoplastic polyurethane resin composition has an excessively low hardness, and the resulting molded product of the resin composition has It does not have sufficient strength.

The reaction (polymerization reaction of the polyurethane resin (A)) of the polymer polyol (a1), the chain extender (a2), and the polyisocyanate (a3) may be performed in the presence of a catalyst.
Such catalysts include, for example, amines such as triethylamine, triethylenediamine, N-methylimidazole and N-ethylmorpholine, organometallics such as potassium acetate, stannous octoate, dibutyltin dilaurate and dioctyltin dilaurate, tributylphosphine, Examples thereof include phosphorus compounds such as phospholene and phospholene oxide.

<Hydrolysis inhibitor>
Examples of the hydrolysis inhibitor constituting the thermoplastic polyurethane resin composition of the present invention include carbodiimide compounds (for example, bis (2,6-diisopropylphenyl) carbodiimide), 4-t-butylcatechol, azodicarbonamide, azo A dicarboxylic acid ester, a fatty acid amide, etc. can be mentioned, Among these, a carbodiimide type compound is preferable.
As a commercial product of a carbodiimide compound (bis (2,6-diisopropylphenyl) carbodiimide) suitable as a hydrolysis inhibitor, “Stabilizer 7000” (manufactured by Raschig) can be mentioned.
The content ratio of the hydrolysis inhibitor is preferably 0.001 to 5 parts by mass with respect to 100 parts by mass of the polymer polyol (a1).

<Antioxidant>
Examples of the oxidative decomposition antioxidant constituting the thermoplastic polyurethane resin composition of the present invention include phenolic antioxidants, phosphorus antioxidants and sulfur antioxidants. Among these, phenolic oxidation agents Inhibitors are preferred.

  Here, as the “phenolic antioxidant”, pentaerythrityl-tetrakis- [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 3,9-bis {2 -[3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxapyro [5,5] undecane, 1,3,5-tris (2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) ) -2,4,6-trimethylbenzene, 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, bis (3,5-di-t-butyl-4) -Hydro (Ethyl benzyl phosphonate) calcium, 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis [1,1-dimethyl-2- [Β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8,10-tetraoxaspiro [5.5] un Can, 1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl) -4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis- (4 ′ -Hydroxy-3'-t-butylphenyl) butyric acid] glycol ester, 1,3,5-tris (3 ', 5'-di-t-butyl-4'-hydroxybenzyl) -S-triazine-2 , 4,6- (1H, 3H, 5H) trione, tocopherols and the like.

  In addition, examples of the “phosphorus antioxidant” include phosphorus stabilizers such as alkyl phosphites, alkyl allyl phosphites, allyl phosphites, alkyl phosphonites, and allyl phosphonites. Specifically, Tris (2,4-di-t-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylene phosphonite, bis ( 2,4-di-t-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, 1,1,3-tris (2-methyl -4-ditridecyl phosphite-5-t-butylphenyl) butane, triphenyl phosphite, Phenylisodecyl phosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenylditridecyl) phosphite, cyclic neopentanetetraylbis (octadecyl phosphite), tris (nonylphenyl) phos Phyto, tris (monononylphenyl) phosphite, tris (dinonylphenyl) phosphite, diisodecylpentaerythritol diphosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10- ( 3,5-di-t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10-dihydro-9-oxa- 10-phosphaphenanthrene, tris 2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-) Examples thereof include t-butyl-4-methylphenyl) phosphite and 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite.

  Examples of the “sulfur antioxidant” include distearyl-3,3′-thiodipropionate, pentaerythritol-tetrakis (3-laurylthiopropionate), dilauryl-3,3′-thiodipropioate. Nate, dimyristyl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, dilauryl thiodipropionate, and the like.

  “Irganox 1010” (manufactured by Ciba Specialty Chemicals Co., Ltd.) may be mentioned as a commercially available phenolic antioxidant suitable as an antioxidant.

<Any resin component>
The resin component constituting the thermoplastic polyurethane resin composition of the present invention is preferably composed only of the polyurethane resin (A), but other resins are used in combination as long as the effects of the present invention are not impaired. Can do.
Examples of the resin used in combination here include ABS resin, SAN resin, vinyl chloride resin, polypropylene, polyethylene, polystyrene, polyacetal, polyamide, polyester, polyester ether, polycarbonate, epoxy resin, amino resin, phenol resin, silicon resin, A fluororesin etc. can be mentioned.

  In the thermoplastic polyurethane resin composition of the present invention, the content ratio of the polyurethane resin (A) and any resin component is the former: the latter = 100: 0 to 100: 100.

<Optional components>
Other substances can be added to the thermoplastic polyurethane resin composition of the present invention as necessary.
As optional addition components, examples of substances that can be added include ultraviolet absorbers, heat resistance improvers, plasticizers, lubricants, antistatic agents, conductivity-imparting agents, colorants, inorganic and organic fillers, fiber-based reinforcing agents, reaction A retarder etc. can be mentioned.

<Method for producing resin composition>
It does not specifically limit as a manufacturing method of the thermoplastic polyurethane resin composition of this invention, A conventionally well-known manufacturing method is employable.
Here, in the production reaction of the polyurethane resin (A), a one-shot method or a prepolymer may be employed.
In addition, the production method of the thermoplastic polyurethane resin composition may be batch production or continuous production.
Further, the production apparatus is not particularly limited, and examples thereof include a kneader and an extruder.

  If an example of a manufacturing method is shown here, a polymer polyol (a1), a chain extension agent (a2), a hydrolysis inhibitor, and an antioxidant will be charged into a kneader and heated to 70 to 150 ° C. Thereafter, the polyisocyanate (a3) is added and reacted for 10 to 60 minutes to cool the reaction product. Thereby, a powdery or blocky resin composition (the thermoplastic polyurethane resin composition of the present invention) can be obtained.

<Method of molding resin composition>
The molding method of the thermoplastic polyurethane resin composition of the present invention is not particularly limited, and a conventionally known molding method (for example, extrusion molding method, injection molding method, blow molding method, calendar processing method, roll processing method, Pressing method, stretch molding method) and molding conditions can be employed.

<Hardness of molded product>
In the thermoplastic polyurethane resin composition of the present invention, the hardness of a molded product obtained by thermally deforming the thermoplastic polyurethane resin composition is required to be 80 to 95 in terms of JIS-A hardness.
When the obtained molded article has a JIS-A hardness of less than 80, it does not have sufficient mechanical properties applicable to various uses. On the other hand, when the JIS-A hardness of the molded product exceeds 95, the molded product is brittle and may be damaged by vibration or impact in a use environment.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by these. In the examples and comparative examples, “part” means “part by mass”.

<Example 1>
In accordance with the formulation shown in Table 1 below, a reaction vessel equipped with a stirrer is obtained from 2-methyl-1,3-propanediol and adipic acid as the polymer polyol (a1), hydroxyl value = 56, molecular weight = 2. Polyester polyol “TA22-510A” (manufactured by Hitachi Chemical Co., Ltd.), 100.0 parts, 1,6-hexanediol as chain extender (a2), 8.61 parts, and hydrolysis inhibitor, 0.80 part of bis (2,6-diisopropylphenyl) carbodiimide “Stabilizer 7000” (manufactured by Raschig) and “Irganox 1010” (manufactured by Ciba Specialty Chemicals) 0.04 as an antioxidant Are mixed uniformly and adjusted to 120 ° C., and then hexamethylene diisocyanate as polyisocyanate (a3). Added the door 20.64 parts, was carried out a urethane reaction. When the temperature of the reaction product reached 120 ° C. (after about 1 minute from the addition of hexamethylene diisocyanate), the reaction product was taken out from the reaction vessel and poured onto a vat to solidify. The obtained solid was aged in an electric furnace at 80 ° C. for 24 hours and cooled, and then the solid was pulverized to obtain 130 parts of a flaky resin composition (thermoplastic polyurethane resin composition of the present invention). The obtained flaky resin composition was molded into a 110 × 55 × 2 mm sheet with a molding temperature of 150 to 190 ° C. and a molding pressure of 600 kgf / cm ² using an injection molding machine. By post-curing by heating for a time, a molded article (sheet) was obtained.

<Example 2>
According to the formulation shown in Table 1 below, as the polymer polyol (a1), a polyester polyol “TA22-” obtained from 2-methyl-1,3-propanediol and adipic acid and having a hydroxyl value of 40 and a molecular weight of 2,800 is used. 513A "(manufactured by Hitachi Chemical Co., Ltd.), the amount of 1,6-hexanediol used as the chain extender (a2) was changed to 7.61 parts, and polyisocyanate (a3) 125 parts of a flaky resin composition (the thermoplastic polyurethane resin composition of the present invention) were obtained in the same manner as in Example 1 except that the amount of hexamethylene diisocyanate used was changed to 16.55 parts. Was molded into a sheet shape and post-cured to obtain a molded product (sheet).

<Example 3>
According to the formulation shown in Table 1 below, the amount of 1,6-hexanediol used as the chain extender (a2) was changed to 19.6 parts, the amount of antioxidant used was changed to 0.05 parts, 157 parts of a flaky resin composition (the thermoplastic polyurethane resin composition of the present invention) was obtained in the same manner as in Example 1 except that the amount of hexamethylene diisocyanate, which is the isocyanate (a3), was changed to 36.13 parts. Was molded into a sheet and post-cured to obtain a molded product (sheet).

<Example 4>
In accordance with the formulation shown in Table 1 below, 100.0 parts of “TA22-513A” (manufactured by Hitachi Chemical Co., Ltd.) is used as the polymer polyol (a1), and 1,6-hexane which is a chain extender (a2) The amount of diol used was changed to 20.2 parts, the amount of antioxidant used was changed to 0.05 parts, and the amount of polyisocyanate (a3) hexamethylene diisocyanate was changed to 34.28 parts. Except for the above, 155 parts of a flaky resin composition (the thermoplastic polyurethane resin composition of the present invention) was obtained in the same manner as in Example 1, and this was molded into a sheet shape and post-cured to obtain a molded product (sheet). Obtained.

<Comparative Example 1>
In accordance with the formulation shown in Table 1 below, as a polymer polyol, 100 parts of a polyester polyol obtained from 1,4-butanediol and adipic acid having a hydroxyl value of 55 and a molecular weight of 2,000 is used as a chain extender. A flaky resin composition (thermoplastic for comparison) was used in the same manner as in Example 1 except that 7.80 parts of 1,4-butanediol was used and the amount of hexamethylene diisocyanate was changed to 22.52 parts. 131 parts of a polyurethane resin composition) was obtained, formed into a sheet, and post-cured to obtain a molded product (sheet).

<Comparative Example 2>
According to the formulation shown in Table 1 below, 100 parts of a polyester polyol having a hydroxyl value of 49 and a molecular weight of 2,300 obtained from 3-methyl-1,5-pentanediol and adipic acid is used as the polymer polyol. A flake-shaped resin composition (Comparative) as in Example 1, except that 7.98 parts of 1,4-butanediol was used as a chain extender and the amount of hexamethylene diisocyanate was changed to 21.93 parts. 131 parts of a thermoplastic polyurethane resin composition) was molded into a sheet and post-cured to obtain a molded product (sheet).

<Comparative Example 3>
According to the formulation shown in Table 1 below, 100 parts of a polyester polyol having a hydroxyl value of 49 and a molecular weight of 2,300 obtained from 3-methyl-1,5-pentanediol and adipic acid is used as the polymer polyol. The amount of flakes was changed in the same manner as in Example 1 except that the amount of 1,6-hexanediol, which is a chain extender, was changed to 7.58 parts, and the amount of hexamethylene diisocyanate was changed to 17.91 parts. 126 parts of a resin composition (a thermoplastic polyurethane resin composition for comparison) was obtained, molded into a sheet shape, and post-cured to obtain a molded product (sheet).

<Comparative example 4>
According to the formulation shown in Table 1 below, 1.94 parts of 1,4-butanediol was used as a chain extender, and the same procedure as in Example 1 was performed except that the amount of hexamethylene diisocyanate was changed to 22.87 parts. 132 parts of a flaky resin composition (comparative thermoplastic polyurethane resin composition) were obtained, molded into a sheet, and post-cured to obtain a molded product (sheet).

<Comparative Example 5>
In accordance with the formulation shown in Table 1 below, 100.0 parts of “TA22-513A” (manufactured by Hitachi Chemical Co., Ltd.) is used as the polymer polyol, and 7.68 parts of 1,4-butanediol is used as the chain extender. In the same manner as in Example 1 except that the amount of hexamethylene diisocyanate was changed to 19.48 parts, 128 parts of a flaky resin composition (comparative thermoplastic polyurethane resin composition) was obtained. Was molded into a sheet shape and post-cured to obtain a molded product (sheet).

<Comparative Example 6>
According to the formulation shown in Table 1 below, 100.0 parts of “TA22-513A” (manufactured by Hitachi Chemical Co., Ltd.) is used as the polymer polyol, and 21.9 parts of 1,4-butanediol is used as the chain extender. In the same manner as in Example 1, except that the amount of the antioxidant used was changed to 0.06 parts and the amount of the hexamethylene diisocyanate used was changed to 46.11 parts (for comparison) 169 parts of a thermoplastic polyurethane resin composition) was molded into a sheet and post-cured to obtain a molded product (sheet).

<Comparative Example 7>
According to the formulation shown in Table 1 below, 22.5 parts of 1,4-butanediol was used as a chain extender, the amount of antioxidant used was changed to 0.06 parts, and the amount of hexamethylene diisocyanate used was 49. Except that it was changed to 89 parts, 173 parts of a flaky resin composition (comparative thermoplastic polyurethane resin composition) was obtained in the same manner as in Example 1, and this was molded into a sheet and post-cured. A molded product (sheet) was obtained.

<Comparative Example 8>
In accordance with the formulation shown in Table 1 below, 129 parts of a flaky resin composition (comparative thermoplastic polyurethane resin composition) was obtained in the same manner as in Example 1 except that the hydrolysis inhibitor was not used. This was formed into a sheet shape and post-cured to obtain a molded product (sheet).

The symbols in Table 1 indicate the following substances.
* “2MPA-1”:
Polyester polyol “TA22-510A” (manufactured by Hitachi Chemical Co., Ltd.) obtained from 2-methyl-1,3-propanediol and adipic acid and having a hydroxyl value of 56 and a molecular weight of 2,000.
* “2MPA-2”:
A polyester polyol “TA22-513A” (manufactured by Hitachi Chemical Co., Ltd.) having a hydroxyl value of 40 and a molecular weight of 2,800, obtained from 2-methyl-1,3-propanediol and adipic acid.
* "BA-1": Polyester polyol obtained from 1,4-butanediol and adipic acid and having a hydroxyl value of 55 and a molecular weight of 2,000.
* “3MPA-1”:
A polyester polyol obtained from 3-methyl-1,5-pentanediol and adipic acid and having a hydroxyl value of 49 and a molecular weight of 2,300.
* "1,6HD": 1,6-hexanediol * "1,4BD": 1,4-butanediol

* 1) (Hydrolysis inhibitor): Bis (2,6-diisopropylphenyl) carbodiimide “Stabilizer 7000” (manufactured by Raschig)
* 2) (Antioxidant): "Irganox 1010" (manufactured by Ciba Specialty Chemicals)

<Evaluation of molded products>
The following items were measured or evaluated for each of the flaky resin compositions and molded articles obtained in Examples 1 to 4 and Comparative Examples 1 to 13. The results are shown in Table 2 below.

(1) Flow start temperature of resin composition:
In accordance with JIS K 7311, a sample (flaky-shaped sample) heated at a rate of temperature increase of 3 ° C./min using an elevated flow tester “Shimadzu Flow Tester CFT-500 type” (manufactured by Shimadzu Corporation) When the resin composition) is extruded from a die having a diameter of 1 mm and a length of 1 mm under a load of 98 N, the temperature at which the resin composition starts to flow and as a result the viscosity recording starts (flow starting temperature) is It was measured. The temperature increase start temperature was 100 ° C., and the preheating time of the resin composition was 3 minutes.

(2) Melting characteristics of resin composition:
The melt viscosity at a temperature (T ₂ ) that is 5 ° C. higher than the flow start temperature (T ₁ ) measured in (1) above is measured, and the melt viscosity at (T ₂ ) is the flow start temperature (T ₁ ). When the melt viscosity is 0.125 times or less of the melt viscosity (that is, when a sharp decrease in melt viscosity is observed), when it exceeds 0.125 times (that is, the melt viscosity is slowly decreased) Case) “×”.

(3) Tensile properties of molded products:
A test piece (No. 3 dumbbell) was produced from the molded article, and the tensile strength and elongation were measured according to JIS K 7311.

(4) Hardness of molded product:
Based on JIS K7311, the JIS-A hardness about a molded article was measured.

(5) Surface state of molded product (initial):
The surface of the molded product was visually observed, and the occurrence of precipitates was evaluated according to the following criteria.
“◯”: Almost no precipitate is observed.
“Δ”: Slight deposits are observed.
“X”: A white layer due to the precipitate is partially observed.
“XX”: A white layer due to precipitates is observed in the entire region.

(6) Surface condition of the molded product (accelerated test by high temperature and high humidity atmosphere):
For the molded product for which the evaluation of (5) was “◯”, the molded product was left for 72 hours in an atmosphere at a temperature of 70 ° C. and a relative humidity of 95%. The occurrence situation was evaluated.

(7) Water resistance of molded products:
A test piece (No. 3 dumbbell) having the same shape as that used in the measurement in (3) above was prepared, and this was immersed in water at 85 ° C. for 2 weeks, and then the tensile strength was measured in the same manner as in (3) above. And the retention with respect to the tensile strength (measured value in the above (3)) before immersion was determined.

(8) Yellowing resistance of molded products:
After the molded product was left outdoors for one month, the presence or absence of discoloration (yellowing) was visually observed.

The thermoplastic polyurethane resin composition of the present invention has various resin products (for example, tubes, films, sheets, belts, hoses, etc.) that are excellent in yellowing resistance, water resistance and melt properties and require a good surface state without precipitates. Rolls such as screens, casters, gears, packing, automobile parts, squeegees, paper feed rolls, copier cleaning blades, snow plows, chains, solid tires, anti-vibration materials, soles, sports shoes, machine parts, etc.) Is used as a material for molding.

Claims (1)

(A) Polymer polyol (a1) containing 1,4-hexane, a polyester polyol having a hydroxyl value of 20 to 120 obtained from 2-methyl-1,3-propanediol and adipic acid in a proportion of 50 to 100% by mass A thermoplastic polyurethane resin produced by a reaction of a chain extender (a2) containing 50 to 100% by weight of a diol and a polyisocyanate (a3) containing 50 to 100% by weight of hexamethylene diisocyanate,
(B) a hydrolysis inhibitor, and (C) a thermoplastic resin composition containing an antioxidant,
Isocyanate group possessed by the polyisocyanate (a3), wherein the polymer polyol (a1) has the number of moles of active hydrogen groups [m ₁ ], the chain extender (a2) has the number of moles of active hydrogen groups [m ₂ ]. When the number of moles and [m _3], [m _3] / ([m _1] + [m _2]) value (R value) of a 0.9-1.2, and, [m _1] / [M ₂ ] value (R ′ value) is 0.1 to 15.0,
A thermoplastic polyurethane resin composition, wherein the molded product obtained by thermoforming the resin composition has a JIS-A hardness of 80 to 95.