JPH07179556A - Polyurethane and method for producing molded article made of the same - Google Patents

Abstract

(57) [Summary] [Objective] To provide a high-hardness polyurethane excellent in all of heat resistance, compression set and cold resistance. [Structure] A high hardness polyurethane obtained by reacting a specific polyester polyol having a molecular weight of 2500 to 3500, 1,4-butanediol and diisocyanate (particularly 4,4'-diphenylmethane diisocyanate) in a specific ratio. The diol component that constitutes this polyester polyol is 1,9-nonanediol and 3-
It is a mixed diol in a specific ratio with methyl-1,5-pentanediol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane having excellent heat resistance, compression set and cold resistance, and a molded article made of the polyurethane. The polyurethane of the present invention gives a molded article excellent in all the properties of heat resistance, compression set and cold resistance after being molded and left at room temperature, and the performance is further improved by heat treatment after molding. Give a molded product.

[0002]

2. Description of the Related Art Since thermoplastic polyurethane has many features such as high elasticity, excellent abrasion resistance and oil resistance, it has been attracting attention as an alternative material for rubber and plastics. As a molding material that can be applied, it has been used in a large amount in a wide range of applications.

[0003]

However, among thermoplastic polyurethanes, those having good heat resistance are inferior in compression set or cold resistance. Therefore, in order to expand the application, heat resistance, compression set and There is a demand for a thermoplastic polyurethane that has both cold resistance. Therefore, one of the objects of the present invention is to provide a polyurethane having excellent heat resistance, compression set and cold resistance. Another object of the present invention is to provide a method for producing a polyurethane molded product that effectively exhibits these excellent performances.

[0004]

According to the present invention, one of the above objects is to provide a polyester polyol having a molecular weight of 2500 to 3500, 1,4-butanediol and diisocyanate with a mole number a of the polyester polyol.
The number of moles b of 1,4-butanediol and the number of moles c of diisocyanate are represented by the following formula (I)

1.01 ≦ c / (a + b) ≦ 1.10 (I)

J obtained by reacting at a ratio satisfying J
A polyester polyurethane having an IS-A hardness of 75 or more, wherein the polyester polyol is mainly 1,9
-Having a diol component consisting of a nonanediol component and a 3-methyl-1,5-pentanediol component and a dicarboxylic acid component, the molar fraction d and 3-methyl of the 1,9-nonanediol component based on the total diol components -1,
The molar fraction e of the 5-pentanediol component is represented by the following formula (II)

0.4 ≦ d / (d + e) ≦ 0.6 (II)

It is achieved by providing a polyurethane characterized by satisfying: Further, another object of the present invention is achieved by providing a method for producing a polyurethane molded product, which comprises subjecting the polyurethane to a heat treatment at a temperature of 60 ° C. or higher after molding.

The polyester polyol used in the present invention mainly comprises a diol component and a dicarboxylic acid component, and the diol component mainly comprises a 1,9-nonanediol component and a 3-methyl-1,5-pentanediol component. 1,9 in the diol component
-Mole fraction d of nonanediol component and 3-methyl-
It is important that the mole fraction e of the 1,5-pentanediol component satisfies the above mathematical formula (II). d / (d + e)
If the value is less than 0.4, the cold resistance of the polyurethane decreases, and if it exceeds 0.6, the heat resistance and compression set performance decrease. The molecular weight (number average molecular weight) of the polyester polyol used in the present invention is in the range of 2500 to 3500. When the molecular weight of the polyester polyol is less than 2,500, the heat resistance and compression set performance of the resulting polyurethane deteriorate, whereas when it exceeds 3500, the moldability, tensile strength and transparency of the obtained polyurethane are unsatisfactory. Will be enough.

The dicarboxylic acid component in the polyester polyol used in the present invention has a carbon number of 6 to 1.
A straight chain aliphatic dicarboxylic acid of 2 is preferred. Examples of the aliphatic dicarboxylic acid include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and the like. Further, the diol component may be only 1,9-nonanediol and 3-methyl-1,5-pentanediol, but other diols may be supplementarily used as long as the amount is small.

The method for producing the polyester polyol is not particularly limited, and for example, it can be produced by a known polycondensation method by an esterification reaction or a transesterification reaction using a diol, a dicarboxylic acid or an esterified product thereof as a raw material. it can. It is possible to use an esterification catalyst such as a titanium catalyst or a tin catalyst in the polycondensation. When a titanium-based esterification catalyst is used,
After polycondensation, it is preferable to deactivate the catalyst contained in the obtained polyester polyol. As the deactivation treatment, a method of bringing the polyester polyol into contact with water under heating conditions is preferable.

Examples of the diisocyanate that can be used in the present invention include 4,4'-diphenylmethane diisocyanate, p-phenylene diisocyanate, toluylene diisocyanate and 1,5-naphthylene diisocyanate. Among these,
4,4'-diphenylmethane diisocyanate is particularly preferred.

The thermoplastic polyurethane is obtained by reacting a polymer polyol, a chain extender and a diisocyanate, but in the present invention, in order to secure excellent heat resistance, compression set and cold resistance, The above-mentioned polyester polyol is used as the molecular polyol, 1,4-butanediol is used as the chain extender, and the relative amounts of the polyester polyol, the chain extender and the diisocyanate are set within the range satisfying the above formula (I). This is very important. That is, the number a of moles of the polyester polyol, the number b of 1,4-butanediol and the number c of diisocyanates are c / (a +
When the value of b) is less than 1.01, the molecular weight of polyurethane does not increase sufficiently after molding, so that only molded products having insufficient heat resistance and compression set performance can be obtained. Conversely, the value of c / (a + b) is 1.10
If it is larger than the above range, the moldability of the polyurethane becomes poor and it becomes difficult to exhibit the thermoplastic characteristics. c / (a +
The value of b) is preferably in the range of 1.02 to 1.08.

Regarding the method for polymerizing the polyester polyol, 1,4-butanediol and diisocyanate to produce the polyurethane of the present invention, a known technique for urethanization reaction can be adopted. 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. Incidentally, when producing the polyurethane of the present invention,
As the polymer polyol, the chain extender and the diisocyanate, compounds other than the above polyester polyol and 1,4-butanediol may be used in combination as long as the amounts are small. In addition, a coloring agent, a lubricant,
Additives such as a crystal nucleating agent, a flame retardant, an ultraviolet absorber, an antioxidant, a light resistance improving agent, an anti-hydrolysis agent and an antifungal agent may be appropriately added.

In the polyurethane of the present invention, it is important that the hardness (JIS-A) is 75 or more in order to ensure excellent heat resistance, compression set and cold resistance.

The polyurethane of the present invention has a logarithmic viscosity (ηin
h) is preferably in the range of 0.5 to 2.1 dl / g. Within this range, excellent performances in heat resistance, compression set and moldability will be more remarkable.
The logarithmic viscosity was measured by dissolving the sample in a 0.05 M N, N-dimethylformamide solution of n-butylamine at 0.5 g / dl, and after 24 hours, measure the solution viscosity with a Ubbelohde viscometer at 30 ° C. It can be measured and calculated from the following formula.

Ηrel = t / to ηinh = ln (ηrel) / ct: Solution flow time (seconds) to: Solvent flow time (seconds) ηrel: Specific viscosity c: Polyurethane (sample) concentration (g / dl) )

The polyurethane of the present invention is excellent in all of the heat resistance, compression set and cold resistance. The polyurethane of the present invention can be subjected to molding such as injection molding, and the obtained molded product exhibits the above-mentioned various performances derived from the polyurethane of the present invention. Furthermore, the performance such as compression set is further improved by heat-treating the obtained molded product after molding at a temperature of 60 ° C. or higher at a temperature at which the molded product is not deformed, particularly in the range of 80 to 110 ° C. Become. Therefore, specific applications of the polyurethane of the present invention include sheets, films, squeegees, chains, belts, screens, tubes, cleaning blades for copying, paper feed rolls, various rolls, gears, casters, binders, solid tires, packing materials. , Automobile parts, shoe soles, sports shoes, adhesives, machine parts, anti-vibration materials, vibration-damping materials, elastic fibers, etc., which can be obtained by injection molding, extrusion molding, etc., which have been conventionally used for molding polyurethane. Is.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples. In the examples, hardness, heat resistance, compression set and cold resistance were measured by the following methods.

[Hardness] Thickness of 6 m obtained by injection molding
Using a molded sample of m, the hardness was measured by a Shore A hardness meter.

[Heat resistance] Thickness 4 obtained by injection molding
The Vicat softening temperature was measured using a molded sample of mm, and used as an index of heat resistance. The measurement load of the Vicat softening temperature was 1 kgf, and the measurement was performed according to JIS-K-7206.

[Compression set] JIS-K-6 was used by using a molding sample having a thickness of 20 mm obtained by injection molding.
The measurement was performed by the method according to 301 (heat treatment condition: 70 ° C. × 22 hours).

[Cold resistance] Thickness 2 obtained by injection molding
A test piece was prepared from a molded disc of mm. The dynamic viscoelasticity of this test piece was measured at a frequency of 11 Hz, and the temperature (Tα) at which the dynamic loss elastic modulus (E ″) reached a peak was determined and used as an index of cold resistance.

[Hydrolysis resistance] A dumbbell-shaped test piece prepared from a molded disc having a thickness of 2 mm obtained by injection molding was allowed to stand at 70 ° C. and 95% relative humidity for 3 weeks, and tests before and after that were performed. The breaking strength of each piece was measured, and the retention rate of the strength after standing with respect to the strength before standing was determined and used as an index of hydrolysis resistance.

The compounds used in the examples are indicated by abbreviations. The compound names represented by the abbreviations are shown in Table 1 below.

[0026]

[Table 1]

[Reference Example 1] (Production of PNMA-A) ND 1920 g, MPD 1416 g and adipic acid 2
920 g was charged into the reactor, and the esterification reaction was carried out under reduced pressure at 200 ° C. while distilling the produced water out of the system.
When the acid value of the reaction product became 30 or less, 90 mg of tetraisopropyl titanate was added, and 200-100 mmH
The polycondensation reaction was started while reducing the pressure to g. 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,
PNMA of ND / MPD = 1/1 (molar ratio) is 5090
g (hereinafter, the polyester diol obtained here is referred to as “PNMA-A”).

Reference Example 2 (Deactivation of titanium-based catalyst) 5000 g of PNMA-A obtained in Reference Example 1 was heated to 100 ° C.
Then, 150 g (3% by weight) of water was added thereto. The titanium-based catalyst was deactivated by continuing heating for 2 hours with stirring, and water was distilled off under reduced pressure (the polyester diol obtained by this treatment was referred to as "PNMA-B").
That).

[Reference Examples 3 to 7] Esterification reaction, polycondensation reaction and catalyst deactivation treatment were carried out according to Reference Examples 1 and 2 except that the diol used was changed to obtain polyester diols. The diol component and the molecular weight (number average molecular weight) of the obtained polyester diol are
Each is shown in Table 2.

[0030]

[Table 2]

[Example 1] PNMA obtained in Reference Example 2
-B, BD, and MDI heated and melted at 50 [deg.] C., as shown in Table 3 below, were in a molar ratio of PNMA-B: BD: MDI of 1: 5.60: 6.86 and the total amount thereof was 2: 1.
30m from the metering pump so that it becomes 00g / min.
It was continuously charged into a twin-screw type extruder rotating in the coaxial direction of L / D = 36 at mφ, and a continuous melt polymerization reaction was carried out at a temperature of 260 ° C. The resulting thermoplastic polyurethane melt was continuously extruded into water in strands, then cut with a pelletizer and formed into pellets. The pellets were dehumidified and dried at 80 ° C. for 20 hours, injection-molded at 200 ° C. to prepare a measurement sample, and left at 80 ° C. for 8 hours or at 20 ° C. for 1 week, and then logarithmic viscosity, hardness, heat resistance,
The compression set and cold resistance were measured. The obtained results are shown in Table 4 below.

[Examples 2 to 4] Polymerization and pelletization were carried out in the same manner as in Example 1 except that the conditions shown in Table 3 were adopted as the type of polyester diol and the ratio of use of each raw material compound. Of pellets were obtained. The pellets obtained were dried and injection-molded in the same manner as in Example 1, and then at 80 ° C. for 8 hours or 2 hours.
The physical properties of the sample left for 1 week at 0 ° C. were measured. The results obtained are shown in Table 4.

[Comparative Examples 1 to 7] Polymerization and pelletization were carried out in the same manner as in Example 1 except that the conditions shown in Table 3 were adopted as the type of polyester diol and the use ratio of each raw material compound, and thermoplastic polyurethanes were prepared. Of pellets were obtained. The pellets obtained were dried and injection-molded in the same manner as in Example 1, and then at 80 ° C. for 8 hours or 2 hours.
The physical properties of the sample left for 1 week at 0 ° C. were measured. The results obtained are shown in Table 4.

[0034]

[Table 3]

[0035]

[Table 4]

From Table 4 above, the polyurethane of the present invention is
It can be seen that the heat resistance, compression set, and cold resistance are all excellent, and that the heat treatment after molding further improves the compression set of the molded product (Examples 1 to 1).
4). On the other hand, a polyurethane having a diol component of the polyester diol, a molecular weight of the polyester diol, or a relative amount of the polyurethane raw material compound different from that of the present invention has at least one of poor heat resistance, compression set, and cold resistance. It turns out that there is (Comparative Examples 1 to 7).

[0037]

Industrial Applicability According to the present invention, there is provided a high hardness polyurethane excellent in all of heat resistance, compression set and cold resistance. A molded article made of the polyurethane exhibits even more excellent performance when heat-treated.

Claims (4)

[Claims] 1. A polyester polyol having a molecular weight of 2500 to 3500, 1,4-butanediol and diisocyanate are added to the polyester polyol in the number of moles a,
The number of moles of 1,4-butanediol b and the number of moles of diisocyanate c are obtained by reacting at a ratio satisfying the following mathematical formula (I) 1.01 ≦ c / (a + b) ≦ 1.10 (I). A polyester polyurethane having a JIS-A hardness of 75 or more, wherein the polyester polyol has a diol component mainly composed of a 1,9-nonanediol component and a 3-methyl-1,5-pentanediol component and a dicarboxylic acid component. However, the molar fraction d of the 1,9-nonanediol component and the molar fraction e of the 3-methyl-1,5-pentanediol component on the basis of all diol components are represented by the following mathematical formula (II) 0.4 ≦ d / ( Polyurethane characterized by satisfying d + e) ≦ 0.6 (II). 2. The polyurethane according to claim 1, wherein the diisocyanate is 4,4′-diphenylmethane diisocyanate. 3. The polyester polyol is a polyester polyol obtained by polycondensing a diol and a dicarboxylic acid in the presence of a titanium-based esterification catalyst and then deactivating the titanium-based esterification catalyst. 1
Or the polyurethane according to 2. 4. A method for producing a polyurethane molded article, which comprises subjecting the polyurethane according to claim 1, 2 or 3 to heat treatment at a temperature of 60 ° C. or higher.