Elastic polyurethane fiber

Details Elastic polyurethane fiber Elastic polyurethane fiber

1992-12-21

1994-05-10

Foelak, Morton

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From reactant having at least one -n=c=x group as well as...

528906, C08G 1830

Patent

active

053108523

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to an elastic polyurethane fiber having excellent resistance to hot water to be dyeable under high-temperature and high-pressure conditions which are commonly used for dyeing polyester fibers. That is, the elastic fibers of the present invention are usable in combination with polyester fibers, besides with nylon or cotton which has been co-used in practice.


BACKGROUND ART

Known processes for producing elastic polyurethane fibers are dry, wet, and melt spinning systems. In recent years, production of elastic polyurethane fibers by melt spinning has been increasing because this process can give fibers having fine deniers and good transparency at relatively low cost.
However, the elastic polyurethane fibers produced by melt spinning have the essential disadvantages of poorer resistance to heat and hot water than that of elastic polyurethane fibers obtained by dry spinning. There has therefore been demanded improvement in resistance to heat and hot water of elastic polyurethane fibers produced by melt spinning.
The present inventors have proposed a melt-spun elastic polyurethane fiber using a branched polyesterpolycarbonate-based polymer diol and having excellent resistance to heat and hot water (see EP 0449036A2) It has been, however, found that the proposed process can, on laboratory scale, yield elastic polyurethane fibers with good properties but cannot always produce fibers having good properties stably on commercial scales.


DISCLOSURE OF THE INVENTION

Accordingly, an object of the present invention is to provide an elastic polyurethane fiber having good resistance to chlorine and light and being excellent in all of elastic recovery and resistance to heat and hot water and, at the same time, dyeable under high-temperature and high-pressure conditions together with polyester fibers.
The present invention provides ah elastic polyurethane fiber comprising a polyurethane obtained by copolymerizing a polymer diol (A) , an organic diisocyanate (B) and a chain extender (C);
said polymer diol (A) that constitutes the polyurethane being a polyester diol and/or polyesterpolycarbonate diol having an average molecular weight of 1,000 to 6,000, and satisfying the following condition (I); ##EQU3## wherein the total number of carbon atoms means the number of the carbon atoms contained in the polymer diol and excluding those contained in the ester bonds and carbonate bonds thereof;
the diol units that constitute said polymer diol containing branched diols in an amount of at least 10 mol %;
said polyurethane constituting said elastic fiber satisfying the following conditions (II) and (III) of long chain hard segments containing at least 3 repeating units from (B) and (C) combinedly, to the amount of total hard segments comprising components (B) and (C) and, linked thereto via urethane bonds, the terminal diol component of (A) , the amounts of said three components being determined on the three components taken out by alcoholysis of component (A) of said polyurethane with an alkalireethanol solution; ##EQU4## wherein the retention of long chain hard segment content after heat melting means the ratio between the contents of long chain hard segments after and before melt-kneading at 230.degree. C. for 60 minutes of said polyurethane constituting said elastic fiber.


BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows an example of hard segment chain-length distribution (GPC chart) of an elastic fiber according to the present invention (obtained in Example 9). The numbers at the peaks in FIG. 1 show the number of repetition of combined units of 4,4'-diphenylmethane diisocyanate (MDI) and butanediol (BD) which is the basic component of the hard segments. The peak 5 includes all units repeating at least 5 times.
The structures of hard segments shown by 0 through 5 in FIG. 1 are as follows.


______________________________________ 0: MPD-MDI-MPD (n = 0) 1: MPD-(MDI-BD).sub.1 -MID-MPD (n = 1) 2: MPD-(MDI-BD).sub.2 -MID-MPD (n = 2) 3: MPD-(MDI-BD).sub.3 -MID-MPD (n = 3)

REFERENCES:
patent: 5118780 (1992-06-01), Hirai et al.

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