JPH0841158A - Polyurethane and its molded products - Google Patents

Abstract

(57) [Summary] [Constitution] 1,9-nonanediol and 3-methyl-1,5-
A polyester diol having a number average molecular weight of 2,200 to 8,000, 1,4-butanediol, obtained by deactivating the titanium catalyst after polycondensing a diol component mainly composed of pentanediol and a dicarboxylic acid component in the presence of the titanium catalyst, and Formula; HO-
A chain extender comprising an aliphatic diol of (CH ₂ ) n-OH (where n is an integer of 5 to 10) and an organic diisocyanate are represented by the formula;
7 ≦ c ₁ / (c ₁ + c ₂ ) ≦ 0.98 and formula; 0.98 ≦ b / (a + c ₁ + c ₂ ) ≦
1.10 [wherein c ₁ is the number of moles of 1,4-butanediol, c ₂ is the number of moles of an aliphatic diol represented by the formula (I), a is the number of polyester diols, and b is the number of organic diisocyanates. ] Polyurethane obtained by reacting in the presence of a tin-based urethane-forming catalyst in a ratio satisfying the above, a process for producing the same, and a molded article made of the polyurethane. [Effect] The polyurethane of the present invention is excellent in moldability, and the molded product is excellent in all of heat resistance, heat resistance strength, heat resistance retention rate, melt abrasion resistance, cold resistance and hydrolysis resistance, and has a compression set. Is small and can be effectively used for various products.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a polyurethane having excellent moldability, heat resistance, melt abrasion resistance, cold resistance and hydrolysis resistance, and having a small compression set, a process for producing the same, a polyurethane molded product and a process for producing the same. Regarding Specifically, the present invention is excellent in moldability such as extrusion moldability without having a sharp increase in melt viscosity even when the time in the molten state is long, has a high softening point and excellent heat resistance, and It has high strength and strength retention rate and excellent heat resistance and heat strength retention, as well as excellent melt wear resistance, cold resistance and hydrolysis resistance, and moreover, it is possible to obtain a molded product with less compression set. The present invention relates to a thermoplastic polyurethane that can be produced, a method for producing the same, a polyurethane molded article, and a method for producing the same.

[0002]

2. Description of the Related Art Thermoplastic polyurethane has a high elasticity and is excellent in various properties such as abrasion resistance and oil resistance, and moreover, since it is possible to apply a usual thermoplastic resin molding processing method, In recent years, it has been used in large amounts in a wide range of applications as a polymer material that replaces the diene rubber, polyolefin, and other general-purpose thermoplastic polymers. However, among thermoplastic polyurethanes, those with good heat resistance tend to have a sharp increase in viscosity as the time in the molten state becomes longer, so that the molding can be performed smoothly in extrusion molding with a relatively long melt residence time. It is difficult to carry out, and there are many restrictions on molding. Further, the existing heat-resistant thermoplastic polyurethane has a large compression set and does not have sufficient cold resistance, and a thermoplastic polyurethane having heat resistance, compression set and cold resistance has not yet been known. In addition, the conventional thermoplastic polyurethane has low strength at high temperature (hereinafter referred to as "heat resistant strength") and strength retention at high temperature (hereinafter referred to as "heat resistant strength retention rate"), and also has insufficient melt wear resistance. , There was a problem in practice. From this point, the viscosity does not rise sharply even if the time in the molten state is long, it is possible to perform smooth molding even by extrusion molding and the like, the moldability is excellent, and the heat resistance strength and heat resistance retention rate are large, There is a demand for a thermoplastic polyurethane having a small compression set and excellent in all properties such as heat resistance, cold resistance, melt abrasion resistance, and hydrolysis resistance.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is not to increase the viscosity sharply even if the time in the molten state (hereinafter referred to as “melt residence time”) is long, and the molded product is excellent even by extrusion molding. Thermoplastic polyurethane that can be manufactured with excellent moldability, has a high heat resistance and a high heat resistance retention rate, has a low compression set, and is also excellent in heat resistance, cold resistance, melt abrasion resistance and hydrolysis resistance. And a method for manufacturing the same. Further, an object of the present invention is to provide a polyurethane molded article having the above-mentioned excellent properties and a method for producing the same.

[0004]

As a result of extensive studies by the present inventors to achieve the above object, a specific polyester diol and a specific chain extender are selected and used, and When a chain extender is reacted with an organic diisocyanate in a specific ratio, the melt viscosity does not rise sharply even if the melt residence time becomes long, the extrusion moldability is excellent, and the strength at high temperature is large and the compression set is high. It has been found that a polyurethane having a small practical value and excellent in various properties such as heat resistance, cold resistance, melt abrasion resistance and hydrolysis resistance and having an extremely high practical value can be obtained. Furthermore, the present inventors further improved the above-mentioned various properties by heat-treating the obtained molded product at a specific temperature or higher after molding using the polyurethane thus obtained. The present invention was completed based on the findings that the properties are further improved and the compression set is further reduced.

That is, the present invention is a polyurethane obtained by the reaction of a polyester diol, an organic diisocyanate and a chain extender, wherein (i) the polyester diol comprises a dicarboxylic acid component, 1,9-nonane diol and 3- Methyl-1,5
A polyester diol having a number average molecular weight of 2200 to 8000, obtained by polycondensing a diol component mainly composed of pentanediol in the presence of a titanium polycondensation catalyst and deactivating the titanium polycondensation catalyst. (Ii) the chain extender is 1,4-butanediol and the following general formula (I);

[0006]

Embedded image An aliphatic diol represented by HO— (CH ₂ ) n—OH (I) (wherein, n represents an integer of 5 to 10); (iii) the polyester diol, organic The use ratios of the diisocyanate and the chain extender are the following formulas and;

[0007]

## EQU7 ## 0.70 ≦ c ₁ / (c ₁ + c ₂ ) ≦ 0.98

0.98 ≦ b / (a + c ₁ + c ₂ ) ≦ 1.10 [wherein c ₁ is the number of moles of 1,4-butanediol, and c ₂ is the above general formula (I)] The number of moles of aliphatic diol represented, a is the number of moles of polyester diol, and b is the number of moles of organic diisocyanate], and (iv) contains a tin-based urethane-forming catalyst. It is a characteristic polyurethane.

The present invention is a method for producing a polyurethane by reacting a polyester diol, an organic diisocyanate and a chain extender, wherein (i) the polyester diol is a dicarboxylic acid component and 1,9-nonane diol. And 3-methyl-
After polycondensing a diol component mainly composed of 1,5-pentanediol in the presence of a titanium-based polycondensation catalyst,
A polyester diol having a number average molecular weight of 2200 to 8000 obtained by deactivating the titanium-based polycondensation catalyst is used; (ii) 1,4-butanediol and the following general formula (I) as the chain extender. );

[0009]

Embedded image An aliphatic diol represented by HO— (CH ₂ ) n—OH (I) (wherein, n represents an integer of 5 to 10) is used; and (iii) the polyester diol, The organic diisocyanate and chain extender are represented by the following formula and;

[0010]

[Formula 9] 0.70 ≦ c ₁ / (c ₁ + c ₂ ) ≦ 0.98

0.98 ≦ b / (a + c ₁ + c ₂ ) ≦ 1.10 [wherein c ₁ is the number of moles of 1,4-butanediol, and c ₂ is the above general formula (I)] Represented by the number of moles of the aliphatic diol, a is the number of moles of the polyester diol, and b is the number of moles of the organic diisocyanate] in the presence of the tin urethanization catalyst; Is a method for producing a polyurethane.

Furthermore, the present invention is characterized in that a molded product obtained from the above-mentioned polyurethane and a molded product obtained by molding using the above-mentioned polyurethane are heat-treated at a temperature of 60 ° C. or higher. It is a method for producing a polyurethane molded product.

As described above, in the present invention, the polyester diol constituting the polyurethane is composed of the dicarboxylic acid component, 1,9-nonanediol and 3-methyl-1,
It is necessary that the polyester diol is obtained by a reaction with a diol component mainly composed of 5-pentanediol.

In this case, as the dicarboxylic acid component constituting the polyester diol, it is preferable to use a linear aliphatic dicarboxylic acid having 6 to 12 carbon atoms or an ester-forming derivative thereof, which is resistant to melt abrasion and resistance to melting. It is preferable in that the hydrolyzability is good and the compression set is small.
Specific examples of the aliphatic dicarboxylic acid component may include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, or their ester-forming derivatives, and these dicarboxylic acid components may be used alone. Alternatively, two or more kinds may be used in combination.

Further, the diol component constituting the polyester diol needs to be mainly composed of 1,9-nonanediol and 3-methyl-1,5-pentanediol as described above, which constitutes the polyester diol. 80 mol% or more of the diol component
It is preferably composed of nonanediol and 3-methyl-1,5-pentanediol. And in the present invention, the diol component constituting the polyester diol is
The following formula;

[0015]

0.3 ≦ d ₁ / (d ₁ + d ₂ ) ≦ 0.7 (wherein d ₁ is the mole fraction of 1,9-nonanediol, and d ₂ is 3-methyl-1,5 -Which represents the mole fraction of pentanediol) and 3,
Particularly preferably, it consists of a mixed diol with -methyl-1,5-pentanediol. d ₁ / (d ₁ + d ₂ )
If the value is less than 0.3, the heat resistance of the resulting polyurethane is lowered and the compression set tends to increase, while if it is greater than 0.7, the cold resistance of the resulting polyurethane tends to be insufficient. .

In the present invention, the diol component constituting the polyester diol may optionally contain a small amount (usually less than 10 mol% of the total diol component) of another diol component, and examples of the other diol component include Examples thereof include ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,8-octanediol.

The number average molecular weight of the polyester diol constituting the polyurethane is 2200 to 8000.
And it is preferably 2500 to 6000. When the number average molecular weight of the polyester diol is less than 2200, the heat resistance of the obtained polyurethane is lowered and the compression set is increased, while the value of 800
When it exceeds 0, the moldability, tensile strength and transparency of the resulting polyurethane deteriorate. Here, the number average molecular weights of the polyester diols referred to in this specification are all JIS
It is the number average molecular weight calculated based on the hydroxyl value measured according to K 1577.

The method for producing the polyester diol is not particularly limited, and the polyester diol can be produced by polycondensation using the above-mentioned dicarboxylic acid component and diol component by a conventionally known transesterification reaction, direct esterification reaction or the like. However, in that case, the polycondensation reaction for producing the polyester diol is carried out in the presence of the titanium-based polycondensation catalyst, and the titanium-based polycondensation catalyst contained in the polyester diol is deactivated after the completion of the polycondensation reaction. It is important to note that if the titanium-based polycondensation catalyst is not deactivated, the resulting polyurethane will have significantly reduced hydrolysis resistance, poor cold resistance and heat resistance, and a large compression set. Become.

In the above, the titanium-based polycondensation catalyst used in the production of the polyester diol may be any titanium-based catalyst conventionally used in the production of a polyester diol-based polymer and is not particularly limited. As an example of a preferable titanium-based catalyst, titanic acid,
Examples thereof include tetraalkoxytitanium compounds, titanium acylate compounds, and titanium chelate compounds.
More specifically, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-2-ethylhexyl titanate, tetraalkoxy titanium compounds such as tetrastearyl titanate, polyhydroxytitanium stearate, polyisopropoxytitanium stearate and other titanium acylates. Rate compounds, titanium acetylacetonate,
Examples thereof include titanium chelate compounds such as triethanolamine titanate, titanium ammonium lactate, titanium ethyl lactate, and titanium octylene glycolate. The amount of the titanium-based polycondensation catalyst used is not particularly limited, but in general, it is preferably about 0.1 to 50 ppm, and preferably about 1 ppm, based on the total weight of the dicarboxylic acid component and the diol for forming the polyester diol.
-30 ppm is more preferable.

The titanium-based polycondensation catalyst contained in the polyester diol can be deactivated by, for example, bringing the polyester diol obtained by the polycondensation reaction into contact with water under heating to deactivate the polyester diol. ,
Examples thereof include a method of treating with a phosphorus compound such as phosphoric acid ester, phosphorous acid, and phosphorous acid ester. Among them, the former method of contacting with water under heating is preferable.
When deactivating the titanium-based polycondensation catalyst by contacting with water, 1% by weight or more of water is added to the polyester diol obtained by the polycondensation reaction, and the temperature is 70 to 150 ° C, preferably 90 to 130 ° C. It is good to heat for 1 to 3 hours. The deactivation treatment of the titanium-based polycondensation catalyst may be performed under normal pressure or under increased pressure. When the system is depressurized after deactivating the titanium-based polycondensation catalyst, the water used for deactivation is removed. Can be removed and is desirable.

In the present invention, as the organic diisocyanate used for producing polyurethane, any of the organic diisocyanates conventionally used for producing polyurethane can be used, and the kind thereof is not particularly limited, and aromatic diisocyanate, alicyclic One or two or more of diisocyanate and aliphatic diisocyanate can be used. Among them, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate,
Aromatic diisocyanates such as toluylene diisocyanate and 1,5-naphthylene diisocyanate are preferable, and 4,4′-diphenylmethane diisocyanate is particularly preferable.

In the present invention, as the chain extender, 1,
It is necessary to use 4-butanediol and the aliphatic diol represented by the above general formula (I), and at that time, the number of moles c ₁ of 1,4-butanediol and the moles of the aliphatic diol are required. It is important that the ratio with the number c ₂ is a ratio that satisfies the above-mentioned mathematical formula. If the value of c ₁ / (c ₁ + c ₂ ) is out of the range of the above formula, the value is 0.7.
If it is less than 0, the heat resistance, heat resistant strength retention rate, and melt wear resistance of the resulting polyurethane will decrease and the compression set will increase. On the other hand, when the value of c ₁ / (c ₁ + c ₂ ) is larger than 0.98, the obtained polyurethane has a rapid melt viscosity when the melt residence time becomes long and cannot be melt extruded. It becomes difficult to manufacture a molded product. The value of c ₁ / (c ₁ + c ₂ ) is 0.80
The range of 0.95 is preferable because the resulting polyurethane has better moldability, heat resistance, heat resistance, heat resistance retention, and melt wear resistance, and further has a smaller compression set.

The above-mentioned general formula (I) used as a chain extender
Specific examples of the aliphatic diol represented by
Pentanediol, 1,6-hexanediol, 1,8
-Octanediol, 1,9-nonanediol, 1,1
There may be mentioned 0-decanediol and the like, and these may be used alone or in combination of two or more, and among them, 1,9-nonanediol and / or 1,6-hexanediol are preferable, More preferred is 1,9-nonanediol.

The above-mentioned polyester diol,
The polyurethane of the present invention is produced by reacting an organic diisocyanate and a chain extender. In producing the polyurethane, the number of moles of polyester diol is a, the number of moles of organic diisocyanate is b, 1,4.
When the number of moles of butanediol is c ₁ and the number of moles of the aliphatic diol represented by the above general formula (I) is c ₂ , the polyester diol, organic diisocyanate and It is necessary to react also with a chain extender. b / (a + c ₁
The value of + c ₂ ) is out of the range of the above mathematical formula and is 0.9
If it is less than 8, the molecular weight of the resulting polyurethane does not increase sufficiently even after heat treatment after molding, and the heat resistance and heat resistance retention of the molded product decrease, the compression set increases, and melt wear resistance increases. Sex decreases. On the other hand, b / (a
If the value of + c ₁ + c ₂ ) deviates from the range of the above-mentioned mathematical formula and is larger than 1.10, the obtained polyurethane has a rapidly increased melt viscosity when the melt residence time becomes long, and thus the polyurethane has a problem of being extruded. Molding becomes difficult and moldability decreases. The value of b / (a + c ₁ + c ₂ ) is 1.00 to 1.0
It is preferable to react each component within the range of 8 because the moldability and heat resistance of the resulting polyurethane will be better and the compression set will be smaller.

In the present invention, together with the above-mentioned polyester diol, organic diisocyanate and chain extender as raw material components of polyurethane, if a small amount, a high molecular diol other than the above polyester diol and / or other low molecular weight compounds are used. You may use diol etc. as needed.

Further, in the present invention, it is necessary to use a tin-based urethane-forming catalyst having a catalytic activity for the urethane-forming reaction in producing a polyurethane using the above-mentioned polyester diol, organic diisocyanate and chain extender. Is. The amount of the tin-based urethanization catalyst used is, in terms of tin atoms, 0.1 with respect to the obtained polyurethane [that is, the total weight of the reactive raw material components such as polyester diol, organic diisocyanate, and chain extender used in the production of polyurethane]. It is preferably from 5 to 15 ppm, more preferably from 1 to 12 ppm.

If the resulting polyurethane contains a tin-based urethane-forming catalyst in an amount of 0.5 ppm or more in terms of tin atom, the molecular weight of the polyurethane is maintained at a sufficiently high level even after molding, and its physical properties, particularly hydrolysis resistance, are maintained. Good heat resistance, cold resistance, etc. are maintained. However, when the content of the tin-based urethane-forming catalyst in the polyurethane exceeds 15 ppm in terms of tin atom, hydrolysis resistance and thermal stability are deteriorated, which is not preferable. Although it is not clear why the physical properties of the polyurethane are kept good when an appropriate amount of tin-based urethane-forming catalyst is contained, the tin-based urethane-forming catalyst re-bonds the dissociated urethane bond, and the excess isocyanate group and water It is presumed that the molecular weight of polyurethane may be maintained at a high level by promoting the reaction.

Examples of the tin-based urethane-forming catalyst that can be used in the present invention include tin octylate, monomethyltin mercaptoacetate, monobutyltin triacetate, monobutyltin monooctylate, monobutyltin monoacetate, monobutyltin maleate, Monobutyltin maleate benzyl ester salt, monooctyltin maleate salt, monooctyltin thiodipropionate salt, monooctyltin tris (isooctylthioglycolate ester), monophenyltin triacetate, dimethyltin maleate salt, dimethyl Tin bis (ethylene glycol monothioglycolate), dimethyl tin bis (mercaptoacetic acid) salt, dimethyl tin bis (3-mercaptopropionic acid) salt, dimethyl tin bis (isooctyl mercapto) Cetate), dibutyltin diacetate, dibutyltin dioctoate, dibutyltin distearate, dibutyltin dilaurate, dibutyltin maleate, dibutyltin maleate polymer, dityltin maleate ester salt, dibutyltin bis (mercaptoacetic acid), dibutyltin bis (mercaptoacetic acid) Alkyl ester) salt, dibutyltin bis (3-mercaptopropionic acid alkoxybutyl ester) salt, dibutyltin bis (octylthioglycol ester) salt, dibutyltin (3-mercaptopropionic acid) salt, dioctyltin maleate, dioctyltin maleate Salt, dioctyl tin maleate polymer, dioctyl tin laurate, dioctyl tin bis (isooctyl mercaptoacetate), dioct Examples thereof include tin acylate compounds such as rutin bis (isooctyl thioglycolic acid ester) and dioctyl tin bis (3-mercaptopropionic acid) salt, and mercaptocarboxylic acid salts. These may be used alone or in combination of two or more. You may use together.

Among the above tin-based urethane-forming catalysts, dialkyltin diacylates such as dibutyltin diacetate and dibutyltin dilaurate, and dialkyltin bismercaptocarboxylic acid esters such as dibutyltin bis (3-mercaptopropionic acid ethoxybutyl ester) salts. Salt and the like are preferable. The tin-based urethane-forming catalyst is used for polyester diol,
If added at the same time as the chain extender and organic diisocyanate, or one of these polyurethane raw materials
One or two or more of them may be mixed in advance, but it is desirable to mix them in the polyester diol beforehand so that the tin-based urethane-forming catalyst can be uniformly mixed and dispersed.

The reaction method for obtaining the polyurethane of the present invention is not particularly limited, and the above-mentioned polyester diol,
It may be produced by a prepolymer method or a one-shot method using a known urethanization reaction technique using an organic diisocyanate and a chain extender. Among them, it is preferable to carry out melt polymerization in the substantial absence of a solvent, and particularly preferable is continuous melt polymerization using a multi-screw extruder. Although it may vary depending on the content of the polyester diol used, the type of organic diisocyanate, the content of the chain extender, etc., when producing the polyurethane of the present invention using a multi-screw extruder, those components are generally used. Simultaneously or almost simultaneously, continuously fed to the extruder at 190 to 280 ° C., preferably 210 to 26
It is advisable to manufacture polyurethane by continuous melt polymerization at 0 ° C., then extrude and cut to manufacture polyurethane in the form of pellets, chips, and the like.

If necessary, a colorant, a lubricant, a crystal nucleating agent, a flame retardant, and
One or two of additives such as ultraviolet absorbers, antioxidants, weather resistance improvers, hydrolysis inhibitors, tackifiers and mildew proofing agents
You may add suitably more than one kind. Furthermore, although not limited thereto, the polyurethane of the present invention having a hardness (JIS-A hardness) in the range of 55 to 97 has better performance such as moldability, heat resistance and low compression set. It is preferable because Further, the polyurethane of the present invention has an inherent viscosity (ηinh) of 0.5 to 2.1.
It is preferably dl / g, and by setting the logarithmic viscosity of polyurethane within this range, the moldability such as heat resistance and extrusion moldability is further improved, and the compression set is reduced. The logarithmic viscosity as used herein means that a polyurethane sample is dissolved in a 0.05 M N, N-dimethylformamide solution of n-butylamine so as to have a concentration of 0.5 g / dl, and after 24 hours, a Ubbelohde type viscosity is obtained at 30 ° C. The solution viscosity is measured with a meter and is the value obtained by the following formula.

[0032]

[Equation 12] η _rel = t / t ₀ η _inh = ln (η _rel ) / c [wherein, t = flow time of solution (second), t ₀ = flow time of solvent (second), η _rel = Specific viscosity, η _inh = logarithmic viscosity, c = representing polyurethane concentration (g / dl)]

The polyurethane of the present invention does not show a sharp increase in melt viscosity even if the melt residence time is long, and the melt viscosity does not increase much even if melt-retained at a temperature of 180 ° C. or higher for 1 hour or longer. Various molded products can be smoothly manufactured by various molding methods such as molding, injection molding, blow molding, and calender molding. And
Molded products obtained by these molding methods have excellent heat resistance, melt wear resistance, cold resistance, hydrolysis resistance, low compression set, high heat resistance and heat resistance retention, and excellent properties. For example, tubes, films, sheets, belts, hoses, various rolls, screens, casters, gears, packing materials, automobile parts, squeegees, paper feed rolls, copier cleaning blades, snow plows, chains, linings. It can be effectively used for a wide range of applications such as solid tires, anti-vibration materials, shoe soles, sports shoes, marking materials, binders, adhesives, leather, elastic fibers and machine parts.

The molded product made of the polyurethane of the present invention may be directly used after molding, but after molding, the molded product is heated to a temperature of 60 ° C. or higher, particularly 80 to 1
Heat treatment (annealing) at a temperature in the range of 10 ° C
It is desirable because the heat resistance, heat resistance and heat resistance retention of the molded product can be further improved and the compression set can be further reduced. In this case, the heat treatment time can be appropriately selected according to the content of polyurethane, the size, thickness, shape and the like of the molded product, but it is generally preferable to perform the heat treatment for about 4 to 20 hours.

[0035]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In the following examples, the logarithmic viscosity of polyurethane, extrusion moldability, hardness of the molded product made of polyurethane, tensile strength, heat resistance,
Heat resistance retention rate, heat resistance (Vicat softening temperature), melt wear resistance, compression set, cold resistance and hydrolysis resistance are
It was measured or evaluated by the following method.

[Logarithmic Viscosity] The logarithmic viscosity of polyurethane was determined by the above-mentioned method using a polyurethane pellet produced by melt polymerization or an injection-molded article made of the same.

[Extrusion Moldability] Using a Koka type flow tester, 21 pellets of polyurethane were prepared under the conditions of load 50 kgf, nozzle size 1φ × 10 mm and temperature 210 ° C.
Melt viscosity is measured independently after being placed in a molten and retained state at 0 ° C. for 6 minutes and 210 ° C. for 60 minutes,
The melt viscosity increase rate was calculated from the following equation, and the value was used as an index of extrusion moldability.

[0038]

Melt viscosity increase rate (%) = {(η−η ₀ ) / η ₀ } × 100 η ₀ = melt viscosity after pouring at 210 ° C. for 6 minutes η = 60 at 210 ° C. Melt viscosity (poise) after melt retention for 1 minute

[Hardness] Using a small injection molding tester manufactured by Nissei Plastic Industry Co., Ltd., injection molding was performed under the conditions of a melting temperature of 200 ° C., an injection nozzle pressure of 60 kgf / cm ² and a mold temperature of 30 ° C. The obtained test piece having a thickness of 6 mm was used to measure with a Shore A hardness meter.

[Tensile Strength] The tensile strength was measured according to JIS K-7331. That is, a dumbbell-shaped test piece was prepared from a molded sample with a thickness of 2 mm obtained by injection molding in the same manner as above, and the tensile speed was 30 cm / at room temperature (25 ° C.).
The breaking strength was measured in minutes and used as the tensile strength.

[Heat Resistant Strength] A dumbbell-shaped test piece was prepared from a molded sample having a thickness of 2 mm obtained by injection molding in the same manner as described above, and the tensile tester equipped with a thermostatic chamber whose temperature was controlled at 100 ° C. The breaking strength was measured at a pulling rate of 30 cm / min using the to obtain the heat resistant strength.

[Heat-resistant strength retention rate] From the values of tensile strength and heat-resistant strength measured above, the heat-resistant strength retention rate was determined by the following formula.

[0043]

[Equation 14] Heat resistance strength retention rate (%) = {S / S ₀ } × 100 S ₀ = Tensile strength (kgf / cm ² ) S = Heat resistance strength (kgf / cm ² )

[Heat resistance (Vicat softening temperature)] Using a test piece having a thickness of 4 mm obtained by injection molding in the same manner as above, a measuring load of 1 k was measured according to JIS K-7206.
The Vicat softening temperature was measured under the conditions of gf. And
The heat resistance of polyurethane (polyurethane molded product) was evaluated using the value of the Vicat softening temperature obtained by the measurement as an index of heat resistance.

[Melting wear resistance] Using a Taber-type wear tester (wear wheel CS17) improved by using a test piece having a thickness of 2 mm obtained by injection molding in the same manner as above, a load of 1000 g, a wear wheel Rotation speed 140 rpm, test time 1
A wear test is performed under the condition of 2 hours, and the surface condition of the test piece at the end of the test is observed with the naked eye. When there is almost no damage, the mark is ○, the damage is large, and the worn surface is in a semi-molten state. Was evaluated as x, and the middle thereof was evaluated as Δ.

[Compression set] Using a 20 mm-thick test piece obtained by injection molding in the same manner as described above, J
Method according to IS K-6301 (heat treatment condition: 70
The measurement was performed at 22 ° C. for 22 hours.

[Cold resistance] A test piece was prepared from a disk having a thickness of 2 mm obtained by injection molding in the same manner as described above, and the dynamic viscoelasticity of the test piece was measured at a frequency of 11 Hz to obtain a dynamic value. The temperature (Tα) at which the loss elastic modulus (E ") reaches a peak is calculated,
This was used as an index of cold resistance.

[Hydrolysis resistance] A dumbbell-shaped test piece was prepared from a disk having a thickness of 2 mm obtained by injection molding in the same manner as described above, and the dumbbell-shaped test piece was prepared at 70 ° C. and a relative humidity of 95% RH. The specimen was allowed to stand for 3 weeks, the breaking strength of the test piece before and after that was measured, and the retention rate of the breaking strength after standing with respect to the breaking strength before standing was determined as an index of hydrolysis resistance.

The abbreviations for the compounds used in the following Reference Examples, Examples and Comparative Examples and the contents of the compounds are as shown in Table 1 below.

[0050]

[Table 1] Abbreviation: Compound BD: 1,4-butanediol EG: ethylene glycol HD: 1,6-hexanediol MPD: 3-methyl-1,5-pentanediol ND: 1,9-nonanediol Ad: adipic acid PNMA: ND, MPD and Polyester diol obtained from Ad PNA: Polyester diol obtained from ND and Ad PMPA: Polyester diol obtained from MPD and Ad PBA: Polyester diol obtained from BD and Ad MDI: 4,4′-diphenylmethane diisocyanate DBA: dibutyltin diacetate

Reference Example 1 [Production of PNMA 3000] 1920 g of ND, 1416 g of MPD and 2 of Ad
920 g was charged into the reactor, and the esterification reaction was carried out while distilling out water generated at 200 ° C. under normal pressure to the outside of the system. When the acid value of the reaction product reached 30 or less, 90 mg of tetraisopropyl titanate was added to obtain 200 mmHg-10.
The reaction was continued while reducing the pressure to 0 mmHg. Acid value is 1.0
At that point, the degree of vacuum was gradually raised by a vacuum pump to complete the reaction. As a result, a number average molecular weight of 3,000,
5090 g of PNMA (hereinafter referred to as PNMA-A) having ND / MPD = 1/1 (molar ratio) was obtained.

Reference Example 2 [Production of PNMA 3000 in which the titanium-based catalyst was deactivated] 5000 g of PNMA-A obtained in Reference Example 1 was heated to 100 ° C., and 150 g of water (3% by weight) was added thereto. ) Was added and the mixture was heated with stirring for 2 hours to deactivate the titanium-based catalyst. PNMA in which the titanium-based catalyst was deactivated by distilling off water from the obtained mixture under reduced pressure
(Hereinafter referred to as PNMA-B) was obtained.

Reference Example 3 [Production of PNMA 3000 to which tin-based urethane-forming catalyst was added] 5000 g of PNMA-B obtained in Reference Example 2 above was heated to 100 ° C. to obtain a tin-based urethane-forming catalyst. Dibutyltin diacetate (DBA) was added at 10 ppm (3.4 ppm in terms of tin atom) and stirred for 1 hour. This deactivates the titanium-based catalyst and then adds the tin-based urethane conversion catalyst to PNMA (hereinafter referred to as PNM).
A-C) was obtained.

Reference Example 4 [Production of PNMA 3000 to which a tin-based urethane-forming catalyst was added] 2304 g of ND, 1133 g of MPD and 2 of Ad
PNM with a number average molecular weight of 3000 and ND / MPD = 6/4 (molar ratio) was prepared by charging 920 g into a reactor and carrying out an esterification and polycondensation reaction in the same manner as in Reference Example 1.
5190 g of A was obtained. Using this, the titanium-based catalyst was deactivated in the same manner as in Reference Example 2, and then water was distilled off under reduced pressure.
Furthermore, as in Reference Example 3, dibutyltin diacetate was added as a tin-based urethane-forming catalyst in an amount of 10 ppm (3.4 ppm in terms of tin atom) to deactivate the titanium-based catalyst, and then dibutyltin diacetate (DBA).
To obtain PNMA (hereinafter referred to as PNMA-D).

Reference Example 5 [Production of PNMA 5000 to which a tin-based urethane-forming catalyst was added] 3908 g of MPD, 4204 g of ND and 7 of Ad
300 g of a PNM having a number average molecular weight of 5000 and ND / MPD = 5/5 (molar ratio) was prepared by charging 300 g into a reactor and carrying out an esterification and polycondensation reaction in the same manner as in Reference Example 1.
12800 g of A was obtained. Using this, the titanium-based catalyst was deactivated in the same manner as in Reference Example 2, and water was distilled off under reduced pressure. Then, as in Reference Example 3, dibutyltin diacetate was used as a tin-based urethanization catalyst in an amount of 10 ppm (in the tin atom). By adding 3.4 ppm in terms of conversion, PNMA (hereinafter referred to as PNMA-E) to which dibutyltin diacetate (DBA) was added after deactivating the titanium-based catalyst was obtained.

Reference Example 6 [Production of PNMA 5000 with a tin-based urethane-forming catalyst added] 3356 g of MPD, 4608 g of ND and 7 of Ad
300 g of a PNM having a number average molecular weight of 5000 and ND / MPD = 6/4 (molar ratio) was prepared by charging 300 g into a reactor and carrying out an esterification and polycondensation reaction in the same manner as in Reference Example 1.
12590 g of A was obtained. Using this, the titanium-based catalyst was deactivated in the same manner as in Reference Example 2, and water was distilled off under reduced pressure. Then, as in Reference Example 3, dibutyltin diacetate was used as a tin-based urethanization catalyst in an amount of 10 ppm (in the tin atom). By adding 3.4 ppm in terms of conversion, PNMA (hereinafter referred to as PNMA-F) to which dibutyltin diacetate (DBA) was added after deactivating the titanium-based catalyst was obtained.

Reference Example 7 [Production of PNMA2000 to which tin-based urethane-forming catalyst was added] 2032 g of ND, 1499 g of MPD and 2 of Ad
PNM with a number average molecular weight of 2000 and ND / MPD = 5/5 (molar ratio) was prepared by charging 920 g into a reactor and carrying out an esterification and polycondensation reaction in the same manner as in Reference Example 1.
5100 g of A was obtained. Using this, the titanium-based catalyst was deactivated in the same manner as in Reference Example 2, and water was distilled off under reduced pressure.
Dibutyltin diacetate (DBA) was added after deactivating the titanium-based catalyst by adding 10 ppm (3.4 ppm in terms of tin atom) of dibutyltin diacetate as a tin-based urethane-forming catalyst as in Reference Example 3. PNMA (hereinafter referred to as PNMA-G) was obtained.

Reference Example 8 [Production of PNA 3000 to which tin-based urethane-forming catalyst was added] 3862 g of ND and 2920 g of Ad were charged in a reactor, and esterification and polycondensation reaction was carried out in the same manner as in Reference Example 1. Thus, 5400 g of PNA having a number average molecular weight of 3000 was obtained. Using this, the titanium-based catalyst was deactivated in the same manner as in Reference Example 2, and water was distilled off under reduced pressure. Then, as in Reference Example 3, dibutyltin diacetate was used as a tin-based urethanization catalyst in an amount of 10 ppm (in the tin atom). Converted to 3.4
(ppm) to deactivate the titanium-based catalyst and then add dibutyltin diacetate (DBA) to obtain PNA (hereinafter referred to as PNA-A).

Reference Example 9 [Production of PMPA 3000 to which a tin-based urethane-forming catalyst was added] 2714 g of MPD and 2920 g of Ad were charged in a reactor, and esterification and polycondensation reaction was carried out in the same manner as in Reference Example 1. PMP with a number average molecular weight of 3000
4700 g of A was obtained. Using this, the titanium-based catalyst was deactivated in the same manner as in Reference Example 2, and water was distilled off under reduced pressure.
Dibutyltin diacetate (DBA) was added after deactivating the titanium-based catalyst by adding 10 ppm (3.4 ppm in terms of tin atom) of dibutyltin diacetate as a tin-based urethane-forming catalyst as in Reference Example 3. PMPA (hereinafter referred to as PMPA-A) was obtained.

Reference Example 10 [Production of PBA3000 to which a tin-based urethane-forming catalyst was added] 2160 g of BD and 2920 g of Ad were charged in a reactor, and esterification and polycondensation reaction was carried out in the same manner as in Reference Example 1. Thus, 4100 g of PBA having a number average molecular weight of 3000 was obtained. Using this, the titanium-based catalyst was deactivated in the same manner as in Reference Example 2, and water was distilled off under reduced pressure. Then, as in Reference Example 3, dibutyltin diacetate was used as a tin-based urethanization catalyst in an amount of 10 ppm (in the tin atom). Converted to 3.4
(ppm) to deactivate the titanium-based catalyst and then add dibutyltin diacetate (DBA) to obtain PBA (hereinafter referred to as PBA-A).

Reference Example 11 [Production of PBA5000 to which a tin-based urethane-forming catalyst was added] 5400 g of BD and 7300 g of Ad were charged in a reactor, and esterification and polycondensation reaction was carried out in the same manner as in Reference Example 1. Thus, 10180 g of PBA having a number average molecular weight of 5000 was obtained. Using this, the titanium-based catalyst was deactivated in the same manner as in Reference Example 2, and water was distilled off under reduced pressure. Then, as in Reference Example 3, dibutyltin diacetate was used as a tin-based urethanization catalyst in an amount of 10 ppm (in the tin atom Converted to 3.
4 ppm) was added to deactivate the titanium-based catalyst and then dibutyltin diacetate (DBA) was added to obtain PBA (hereinafter referred to as PBA-B).

Reference Example 12 [Production of PNMA10000 to which tin-based urethane-forming catalyst was added] 1705 g of ND, 1258 g of MPD and 2 of Ad
By charging 891 g into a reactor and carrying out the esterification and polycondensation reaction in the same manner as in Reference Example 1, PN having a number average molecular weight of 10,000 and ND / MPD = 5/5 (molar ratio) was obtained.
5000 g of MA was obtained. Using this, the titanium-based catalyst was deactivated in the same manner as in Reference Example 2, and water was distilled off under reduced pressure. Then, as in Reference Example 3, dibutyltin diacetate was used as a tin-based urethanization catalyst in an amount of 10 ppm (in the tin atom). By adding 3.4 ppm in terms of conversion, PNMA (hereinafter referred to as PNMA-H) to which dibutyltin diacetate (DBA) was added after deactivating the titanium-based catalyst was obtained.

The contents of the polyester diols obtained in Reference Examples 1 to 12 above are summarized in Table 2 below.

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[Table 2]

Example 1 (1) PNMA-C obtained in Reference Example 3 above, a chain extender [a mixture of BD: ND = 85: 15 (molar ratio)] and MDI heated to 50 ° C. As shown in Table 3 below, [PNMA-C]: [MDI]: [BD: N
D] = [1.0]: [6.86]: [4.76: 0.8]
4] (molar ratio) and such that the total feed rate of these is 200 g / min, continuously from a metering pump to a twin-screw extruder (30φ, L / D = 36) that rotates in the coaxial direction. After being supplied, continuous melt polymerization was carried out at a temperature of 260 ° C. The resulting polyurethane melt was continuously extruded in strands into water and then cut with a pelletizer to produce pellets. The pellets were dehumidified and dried at 80 ° C. for 20 hours, and the extrusion moldability was measured by the method described above.
Using the pellets after dehumidification and drying, each test piece for measuring or evaluating physical properties was manufactured by injection molding by the method described above. Test each test piece at a temperature of 80 ° C for 12
After heat treatment for a period of time, using each of the test pieces, logarithmic viscosity, hardness, tensile strength, heat resistant strength, heat resistant strength retention rate, Vicat softening temperature, compression set, cold resistance and hydrolysis resistance were measured by the methods described above or evaluated. The results are shown in Table 4 below.

Example 2 PNMA-D and a chain extender (BD and N were prepared in the same manner as in Example 1 except that PNMA-D obtained in Reference Example 4 was used as the polyester diol.
D) and MDI were continuously melt-polymerized and then extruded and cut to produce polyurethane pellets, which were dehumidified and dried in the same manner as in Example 1. Using the dehumidified and dried pellets, respective test pieces for measurement or evaluation of physical properties were manufactured by injection molding by the method described above. After heat-treating each test piece for 12 hours at a temperature of 80 ° C., using each test piece, logarithmic viscosity, hardness, tensile strength, heat resistant strength, heat resistant strength retention rate, Vicat softening temperature, compression set, cold resistance And hydrolysis resistance was measured or evaluated by the method described above. The results are shown in Table 4 below.

Examples 3 to 5 Polyester diols shown in Table 3 below were added to the chain extender shown in Table 3 and MDI.
In the same manner as in Example 1 except that the reaction was carried out at the molar ratios shown in Table 3, continuous melt polymerization, production of polyurethane pellets and dehumidification drying, production of each test piece by injection molding and heat treatment of the test piece were performed. The same physical properties as in Example 1 were measured or evaluated. The results are shown in Table 4 below.

<< Embodiment 6 >> In the same manner as in Embodiment 1, PN
MA-D, chain extenders (BD and ND), and MDI were continuously melt-polymerized and then extruded and cut to produce polyurethane pellets, which were dehumidified and dried in the same manner as in Example 1. Using dehumidified and dried pellets, respective test pieces for measuring or evaluating physical properties were manufactured by injection molding by the above-mentioned method, and the obtained test pieces were
After being left for a week, the same physical properties as in Example 1 were measured or evaluated. The results are shown in Table 4.

Examples 7 to 8 The polyester diols shown in Table 3 below were added to the chain extenders shown in Table 3 and MDI.
In the same manner as in Example 1 except that the reaction was carried out at the molar ratios shown in Table 3, continuous melt polymerization, production of polyurethane pellets and dehumidification drying, production of each test piece by injection molding and heat treatment of the test piece were performed. The same physical properties as in Example 1 were measured or evaluated. The results are shown in Table 4 below.

Example 9 A polyester diol shown in Table 3 below was continuously reacted in the same manner as in Example 1 except that the chain extender and MDI shown in Table 3 were reacted at the molar ratio shown in Table 3. Melt polymerization, production of polyurethane pellets, dehumidification drying, and production of each test piece by injection molding were performed, and the obtained test piece was allowed to stand at a temperature of 20 ° C. for 1 week, after which the same physical properties as in Example 1 were measured or evaluated. I went. The results are shown in Table 4.

Comparative Example 1 PNMA-A obtained in Reference Example 1 was used as the polyester diol, and PNMA-
Continuous melt polymerization, production of polyurethane pellets and dehumidification drying were carried out in the same manner as in Example 1 except that A was reacted with the chain extender and MDI shown in Table 3 at the molar ratios shown in Table 3.
Each test piece was manufactured by injection molding and the test piece was heat-treated, and the same physical properties as in Example 1 were measured or evaluated. The results are shown in Table 4 below.

Comparative Examples 2 to 6 The polyester diols shown in Table 3 below were used in combination with the chain extender shown in Table 3 and MDI.
And in the same manner as in Example 1 except that the reaction was conducted at the molar ratios shown in Table 3, continuous melt polymerization, production of polyurethane pellets and dehumidification drying, production of each test piece by injection molding, and heat treatment of the obtained test piece. Then, the same physical properties as in Example 1 were measured or evaluated. The results are shown in Table 4.

Comparative Example 7 PNMA-C obtained in Reference Example 3 was used as the polyester diol, and PNMA-
When C was reacted with the chain extender [BD: EG = 85: 15 (molar ratio) mixture] shown in Table 3 and MDI in the molar ratio shown in Table 3 in the same manner as in Example 1, the polymerizability was found to be high. Poorly, polyurethane pellets could not be obtained.

Comparative Examples 8 to 12 The polyester diols shown in Table 3 below were used in combination with the chain extender shown in Table 3 and MDI.
And in the same manner as in Example 1 except that the reaction was conducted at the molar ratios shown in Table 3, continuous melt polymerization, production of polyurethane pellets and dehumidification drying, production of each test piece by injection molding, and heat treatment of the obtained test piece. Then, the same physical properties as in Example 1 were measured or evaluated. The results are shown in Table 4.

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[Table 3]

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[Table 4]

From the results of Tables 3 and 4 above, Examples 1 to 1 satisfying all of the above requirements (i) to (iv)
The polyurethane of Example 9 is excellent in moldability such as extrusion moldability without rapidly increasing the viscosity even when the melt residence time is long, and the polyurethane molded products of Examples 1 to 9 have hardness, tensile strength, and It can be seen that it has excellent heat resistance, heat retention strength, cold resistance and hydrolysis resistance, has a high Vicat softening temperature and excellent heat resistance, and has a small compression set. Further, when comparing Example 1 and Example 6 and Example 8 and Example 9, respectively, in Example 1 and Example 8 where heat treatment is performed after molding, Example 6 and Example 8 where heat treatment is not performed Compared with Example 9, the molded article had a high Vicat softening temperature and was excellent in heat resistance, and the compression set was further smaller. From these results, when molding was performed using the polyurethane of the present invention, It can be seen that when heat treatment is performed after molding, a molded product having more excellent physical properties can be obtained.

On the other hand, the above-mentioned (i) to
Comparative Examples 1-12 lacking any of the requirements of (iv),
That is, the polyurethane of Comparative Example 1 produced in the absence of the tin-based urethane-forming catalyst by using the polyester diol that does not deactivate the titanium-based polycondensation catalyst, and the Comparative Example 2 produced without using the tin-based urethane-forming catalyst. And the polyurethane, polyester diol and the chain extender in Comparative Example 3 and Comparative Example 12 prepared using polyester diol having a number average molecular weight outside the range of 2200 to 8000 satisfy the above formula. Not included in the polyurethane of Comparative Example 4, 1,4-butanediol in the chain extender and the general formula (I)
An aliphatic diol represented by (1,9-nonanediol)
Comparative Example 5 in which the molar ratio of is out of the range of the above formula
Comparative Example 7 in which the chain extender used in combination with the polyurethane and 1,4-butanediol of Comparative Example 6 is not an aliphatic diol represented by the above general formula (I), and 1,9 as a diol component constituting the polyester diol -In the case of the polyurethanes of Comparative Examples 8-11 obtained using polyester diols that do not use both nonanediol and 3-methyl-1,5-pentanediol, extrusion moldability, hardness, tensile strength, heat resistance Strength, heat resistance retention rate, cold resistance, hydrolysis resistance, heat resistance (Vicat softening temperature), compression set, or two or more physical properties, in comparison with the polyurethane of Examples 1 to 9. It turns out that it is significantly inferior. In particular, in the case of Comparative Example 7 in which ethylene glycol was used as the chain extender together with 1,4-butanediol, it was found that polyurethane could not be polymerized smoothly and polyurethane pellets could not be obtained.

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EFFECTS OF THE INVENTION According to the present invention, it is excellent in moldability such as extrusion moldability, heat resistance, heat resistant strength, heat resistant strength retention rate, melt abrasion resistance, cold resistance and hydrolysis resistance, and has little compression set. A polyurethane with very good properties is provided. And, from the polyurethane of the present invention, by utilizing its thermoplasticity, various moldings can be made extremely smooth by molding methods such as extrusion molding, injection molding, blow molding, casting, cast molding, and calender molding. It can be manufactured with good moldability, and the molded product obtained as a result can be effectively used for a wide range of applications by taking advantage of the above-mentioned various properties. Further, the polyurethane molded product of the present invention obtained by further heat-treating under a specific temperature condition after molding is further excellent in heat resistance, heat resistance strength and heat resistance retention rate, and further smaller in compression set. It has characteristics.

Claims (6)

[Claims] 1. A polyurethane obtained by reacting a polyester diol, an organic diisocyanate and a chain extender, wherein (i) the polyester diol comprises a dicarboxylic acid component, 1,9-nonanediol and 3-methyl-1, 5
A polyester diol having a number average molecular weight of 2200 to 8000, obtained by polycondensing a diol component mainly composed of pentanediol in the presence of a titanium polycondensation catalyst and deactivating the titanium polycondensation catalyst. (Ii) the chain extender is 1,4-butanediol and the following general formula (I): embedded image HO— (CH ₂ ) n—OH (I) (wherein n is 5 to 5) And (iii) the proportions of the polyester diol, the organic diisocyanate and the chain extender are represented by the following mathematical formulas; and [Equation 1] 0.70 ≦ c ₁ / (C ₁ + c ₂ ) ≦ 0.98 ## EQU2 ## 0.98 ≦ b / (a + c ₁ + c ₂ ) ≦ 1.10 [wherein c ₁ is the number of moles of 1,4-butanediol, c ₂ is aliphatic represented by the general formula (I) Moles of all, a is the number of moles of the polyester diols, b is a ratio that satisfies] indicates the number of moles of an organic diisocyanate; and (iv) containing tin-based urethanization catalyst; polyurethane, characterized in that. 2. A diol component constituting a polyester diol is represented by the following mathematical formula: 0.3 ≦ d ₁ / (d ₁ + d ₂ ) ≦ 0.7 (where d ₁ is 1,9 -A mole fraction of nonanediol, d ₂ represents a mole fraction of 3-methyl-1,5-pentanediol), and the aliphatic diol represented by the general formula (I) is 1 The polyurethane according to claim 1, wherein the polyurethane-containing catalyst is 9,9-nonanediol, and the content of the tin-based urethane-forming catalyst is 0.5 to 15 ppm in terms of tin atom. 3. A method for producing a polyurethane by reacting a polyester diol, an organic diisocyanate and a chain extender, comprising: (i) a dicarboxylic acid component, 1,9-nonanediol and 3-methyl as the polyester diol. −
After polycondensing a diol component mainly composed of 1,5-pentanediol in the presence of a titanium-based polycondensation catalyst,
A polyester diol having a number average molecular weight of 2200 to 8000 obtained by deactivating the titanium-based polycondensation catalyst is used; (ii) 1,4-butanediol and the following general formula (I) as the chain extender. ); Embedded image An aliphatic diol represented by HO— (CH ₂ ) n—OH (I) (wherein, n represents an integer of 5 to 10) is used; and (iii) the polyester A diol, an organic diisocyanate and a chain extender are represented by the following formulas; and [Formula 4] 0.70 ≦ c ₁ / (c ₁ + c ₂ ) ≦ 0.98 [Formula 5] 0.98 ≦ b / (a + c ₁ + c ₂ ) ≦ 1.10 [wherein c ₁ is the number of moles of 1,4-butanediol, c ₂ is the number of moles of the aliphatic diol represented by the above general formula (I), and a is of the polyester diol. Number of moles, b is the number of moles of organic diisocyanate At a rate that satisfies the are reacted in the presence of a tin-based urethanization catalyst; method for producing a polyurethane, characterized in that. 4. The diol component constituting the polyester diol has the following mathematical formula: 0.3 ≦ d ₁ / (d ₁ + d ₂ ) ≦ 0.7 (wherein d ₁ is 1,9 -A mole fraction of nonanediol, d ₂ represents a mole fraction of 3-methyl-1,5-pentanediol), and the aliphatic diol represented by the general formula (I) is 1 , 9-Nonanediol, and the method for producing a polyurethane according to claim 3, wherein the tin-based urethane-forming catalyst is used at 0.5 to 15 ppm in terms of tin atom. 5. A molded product obtained from the polyurethane according to claim 1 or 2. 6. A method for producing a polyurethane molded article, which comprises molding the polyurethane according to claim 1 or 2 and then heat-treating the obtained molded article at a temperature of 60 ° C. or higher.