JPH0598511A - Polyurethane elastic fiber - Google Patents

Abstract

PURPOSE:To obtain the subject fiber excellent in resistance to hydrolysis and heat and elastic recovery properties in a low-temperature atmosphere by using a polyurethane obtained from a specific polyester polyol, a low-molecular chain extender and a polyisocyanate. CONSTITUTION:The objective elastic fiber is obtained by spinning a polyurethane prepared from (A) a polyester polyol, obtained by reacting a mixture of (i) 1,6-hexanediol with (ii) 1,4-butanediol ad (iii) a low-molecular polyol expressed by the formula (R<1> is lower alkyl; n is 1-5) {mixed under conditions of the formulas 5<=100r/(p+q+r)<=50 and 20<=100q/(p+q+r)<=60 [(p) is the number of mol of the component (i); (q) is the number of mol of the component (ii) and (r) is the number of mol of the component (iii)} with a dicarboxylic acid and having 1000-3500 molecular weight, (B) a low-molecular chain extender and (C) a polyisocyanate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane elastic fiber excellent in hydrolysis resistance, heat resistance and elastic recovery under a low temperature atmosphere.

[0002]

2. Description of the Related Art Conventionally, polyurethane has been prepared by using high molecular weight polyol and polyisocyanate as raw materials and, if desired, low molecular weight compounds having two or more activated hydrogens as raw materials. Examples of the polymer polyol include dicarboxylic acid components such as aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid, and sebacic acid, ethylene glycol, propylene glycol, and 1.
4-butanediol, neopentyl glycol, 1,6
-Polyester polyol obtained by polycondensing with a glycol component such as hexanediol, or polycaprolactone polyol is used. [Keiji Iwata "Polyurethane Resin"]

[0003]

An elastic fiber made of polyurethane produced by using the above polyester polyol as a polymer polyol must simultaneously satisfy hydrolysis resistance, heat resistance and elastic recovery under a low temperature atmosphere. I can't. In order to improve the hydrolysis resistance of this type of polyurethane elastic fiber, it is effective to reduce the ester group concentration of the polyester polyol residue existing as a polymer polyol residue in the polyurethane. To that end, the use of polyester polyols derived from high-carbon glycols and dicarboxylic acids gives favorable results.

However, although the polyurethane elastic fiber obtained by using such a polyester polyol is excellent in hydrolysis resistance, it has a large tendency to be crystallized, and the polyurethane is elastically recovered in a low temperature atmosphere such as -20.degree. Sex significantly decreases. On the other hand, as a method for improving the elastic recovery property in a low temperature atmosphere, there is a method using a mixed glycol of a linear glycol and neopentyl glycol and a polyester polyol obtained from a dicarboxylic acid, but the hydrolysis resistance and heat resistance are deteriorated. There are drawbacks.

An object of the present invention is to provide a polyurethane elastic fiber having excellent hydrolysis resistance, heat resistance, and excellent elastic recovery under a low temperature (eg, -20 ° C) atmosphere.

[0006]

The present invention is an elastic fiber composed of a polyurethane obtained from a polyester polyol, a low molecular chain extender and a polyisocyanate.
As the polyester polyol, a polyester polyol having a molecular weight of 1000 to 3500 obtained by reacting a mixture of 1,6-hexanediol, 1,4-butanediol and a low molecular weight polyol represented by Chemical formula 2 with a dicarboxylic acid is used. And polyurethane elastic fiber.

[0007]

[Chemical 2] (In the formula, R ¹ represents a lower alkyl group such as a methyl group and an ethyl group, and n represents an integer of 1 to 5.)

The low molecular weight polyol represented by Chemical formula 2 is preferably 2-methyl-1,3-propanediol, 3
-Chain linear carbon number 3 such as methyl-1,5-pentanediol
~ 5 diols. Furthermore, the number of linear carbon atoms is 7 to
In the case of 11, it is preferable to use one having an ethyl group, a propyl group or the like as a side chain alkyl group in order to reduce the crystallinity of the soft segment. Above all, when 3-methyl-1,5-pentanediol is used, a polyurethane having excellent hydrolysis resistance, heat resistance and physical properties in a low temperature atmosphere can be obtained.

In the mixture of 1,6-hexanediol, 1,4-butanediol and Chemical formula 2, the ratio of each diol is such that the molar number of 1,6-hexanediol is p, 1,4.
-When the number of moles of butanediol is q and the number of moles of the low molecular weight polyol represented by Chemical formula 2 is r, the conditions of the following formulas (1) and (2) are satisfied. 5 ≦ 100r / (p + q + r) ≦ 50 (1) 20 ≦ 100q / (p + q + r) ≦ 60 (2) In the formula (1), when the ratio of r is higher than this range, hydrolysis resistance and heat resistance are deteriorated. .. In equation (2),
If the proportion of q is lower than this range, the heat resistance is lowered, and conversely, if it is high, the hydrolysis resistance is lowered.

The dicarboxylic acid for producing the polyester polyol used in the present invention is preferably an aliphatic or aromatic dicarboxylic acid having 5 to 12 carbon atoms. Of these, aliphatic dicarboxylic acids are preferred. Examples of the aliphatic dicarboxylic acid include glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and the like, and examples of the aromatic dicarboxylic acid include phthalic acid, terephthalic acid and isophthalic acid. Be done. The use of adipic acid, azelaic acid or sebacic acid, particularly adipic acid or azelaic acid, is preferred in order to obtain a polyurethane having particularly excellent hydrolysis resistance and elastic recovery under a low temperature atmosphere. These dicarboxylic acids may be used alone or in combination of two or more. The molecular weight of the polyester polyol used in the present invention is 10
00-3500 is preferable. If the molecular weight is larger than this, the properties in a low temperature atmosphere deteriorate due to the increase in the crystallinity of the soft segment.

The polyisocyanate used in the present invention is a known aliphatic, alicyclic or aromatic organic polyisocyanate containing two or more isocyanate groups in the molecule, particularly 4,4'-diphenylmethane. Diisocyanate, p-phenylene diisocyanate, toluylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4 ′
Examples thereof include diisocyanates such as dicyclohexylmethane diisocyanate, and triisocyanates obtained by adding 3 mol of tolylene diisocyanate to 1 mol of trimethylolpropane or glycerin.

In the present invention, a suitable chain extender may be used if desired, and the chain extender is a low molecular weight compound having a molecular weight of 400 or less and containing at least two hydrogen atoms capable of reacting with an isocyanate. , Ethylene glycol, 1,4-butanediol, xylylene glycol, catechol, neopentyl glycol, 3,3 ′
-Dichloro-4,4'-diaminodiphenylmethane,
4,4′-diaminodiphenylmethane, hydrazine, dihydrazide, trimethylolpropane, glycerin and the like can be mentioned.

With regard to the operation method for obtaining the polyurethane, a known technique for the polyurethane reaction is used.
For example, the ratio in which the ratio of the number of active hydrogen atoms in these compounds to the isocyanate group is about 1: 1 after preheating a polymer polyol or a mixture thereof with a low molecular weight compound having active hydrogen to about 40 to 100 ° C. After adding the amount of polyisocyanate and stirring vigorously for a short time, about 50-150
A polyurethane is obtained by leaving it at ℃. It is also possible to use a method of obtaining polyurethane via a urethane prepolymer. Polyisocyanate is used in a slight excess because it is usually affected by moisture. These reactions can also be carried out in a solvent composed of one or more of dimethylformamide, diethylformamide, dimethylsulfoxide, dimethylacetamide, tetrahydrofuran, isopropanol, benzene, toluene, ethylcellosolve, trichlene and the like. In this case, when the solvent concentration of polyurethane is within the range of 10 to 40% by weight, it is convenient to obtain a high molecular weight one.

The average molecular weight of the resulting polyurethane is generally 5,000 to 500,000, preferably 10,000.
It is preferably in the range of 0 to 300,000.

Regarding the spinning method for obtaining the elastic fiber from the polyurethane obtained by the above method, the elastic fiber can be obtained by a known spinning method such as wet, dry or melt spinning.

[0016]

The present invention will be described in detail below with reference to examples.
The compounds used are indicated by abbreviations. Table 1 shows the relationship between abbreviations and compounds.

[0017]

[Table 1]

The polyurethane obtained was evaluated by the following method. <Hydrolysis resistance of polyurethane> Polyurethane elastic fiber was subjected to a hydrolysis acceleration test in hot water at 100 ° C for 1 week, and a dimethylformamide / toluene (weight ratio 7/3) mixed solvent of the polyurethane solution before and after the test was used. The viscosity of the solution was measured and evaluated by the retention rate of the logarithmic viscosity after the test with respect to the logarithmic viscosity before the test.

<Flexibility in low temperature atmosphere> 0.2
Vibron Model, a direct-reading dynamic viscoelasticity measuring instrument manufactured by Toyo Sokki Co., Ltd.
It was evaluated by measuring Tα by DDV-II (11.0 Hz) and further by elastic recovery rate (200% elongation) of the polyurethane elastic fiber in a low temperature (−20 ° C.) atmosphere.

<Heat Resistance of Polyurethane> Heating the polyurethane elastic fiber in a 100% stretched state (heating rate: 3 ° C.)
/ Min) and evaluated by the temperature at which the yarn was cut.

Examples 1 to 8 and Comparative Examples 1 to 4 80 comprising a polymeric diol having the composition shown in Table 2 and BD
The mixture heated to 50 ° C. and MDI heated to 50 ° C. were continuously fed to a twin-screw extruder by a metering pump (molar ratio of polymer diol / BD / MDI = 1/2 /
3), continuous melt polymerization was performed, and the produced polyurethane was extruded into water in a strand shape and cut into pellets. The pellet was vacuum dried at 80 ° C. for 20 hours.

[0022]

[Table 2]

These pellets were vacuum dried at 80 ° C. for 20 hours and then spun at a spinning temperature of 230 ° C. with a single-screw extruder.
Spinning at a spinning speed of 500 m / min (using straight oil)
Then, a 40 dr × 2 f polyurethane elastic fiber was obtained. The fiber was aged at 80 ° C. for 48 hours. Various physical properties were measured using this polyurethane elastic fiber. The results are shown in Table 3.

[0024]

[Table 3]

[0025]

As is clear from the above results, according to the present invention, it is possible to obtain a polyester polyurethane elastic fiber having excellent hydrolysis resistance, heat resistance and excellent elastic recovery under a low temperature atmosphere.

Claims (2)

[Claims] 1. An elastic fiber comprising a polyurethane obtained from a polyester polyol, a low molecular weight chain extender and a polyisocyanate, wherein the polyester polyol is 1,6-hexanediol, 1,4-butanediol and Chemical Formula 1 A molecular weight of 1,000 to 100 obtained by reacting a mixture of the low-molecular polyol shown with dicarboxylic acid.
Polyurethane elastic fiber characterized by using 3500 polyester polyols. [Chemical 1] (In the formula, R ¹ represents a lower alkyl group such as a methyl group and an ethyl group, and n represents an integer of 1 to 5.) 2. As the polyester polyol, 1,6
When the number of moles of hexanediol is p, the number of moles of 1,4-butanediol is q, and the number of moles of the low molecular weight polyol represented by Chemical formula 1 is r, the conditions of the following formulas (1) and (2) are The polyurethane elastic fiber according to claim 1, which is satisfied. 5 ≦ 100r / (p + q + r) ≦ 50 (1) 20 ≦ 100q / (p + q + r) ≦ 60 (2)