Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2000-04-26
2002-07-23
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S280000, C528S286000, C528S301000, C528S307000, C528S308600, C524S706000, C524S710000, C524S785000
Reexamination Certificate
active
06423814
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a polyester resin composition having high whiteness, good spinning stability and excellent melt stability. More specifically, the present invention relates to a resin composition comprising poly(trimethylene terephthalate) which itself has high whiteness, good spinning stability and excellent melt stability, therefore, scarcely causes discoloration of the resin composition or reduction in the molecular weight due to thermal decomposition at the melt spinning stage and in turn facilitates the production of a fiber having high tenacity.
BACKGROUND ART
The poly(trimethylene terephthalate) fiber is an epoch-making fiber having soft touch attributable to the low modulus, properties analogous to a nylon fiber such as excellent elastic recovery or easy dyeability, and properties analogous to a poly(ethylene terephthalate) fiber, such as wash-and-wear property, dimensional stability and good color fastness, all at the same time. By using these characteristic features, application of poly(trimethylene terephthalate) fiber to clothing, carpets and the like is proceeding.
Poly(trimethylene terephthalate) can be polymerized by the same method as used for poly(ethylene terephthalate) or poly(butylene terephthalate) analogous to poly(trimethylene terephthalate) in chemical structure. More specifically, terephthalic acid or a lower alcohol diester of terephthalic acid, such as dimethyl terephthalate, and a trimethylene glycol (also called 1,3-propanediol) are previously subjected to an ester exchange reaction shown by the following formula (1) while heating in the absence or presence of a catalyst such as a metal carboxylate, titanium alkoxide or an organic acid, and then to a polycondensation reaction shown by the following formula (2) using a catalyst such as titanium alkoxide or an antimony oxide:
ROOC&phgr;COOR+HOCH
2
CH
2
CH
2
OH→HOCH
2
CH
2
CH
2
OOC&phgr;COOCH
2
CH
2
CH
2
OH+ROH (1)
HOCH
2
CH
2
CH
2
OOC&phgr;COOCH
2
CH
2
CH
2
OH→(OCH
2
CH
2
CH
2
OOC&phgr;CO)
n
(2)
(wherein R represents hydrogen or methyl group and &phgr; represents a benzene ring bonded at the para-position).
However, the polymerization of poly(trimethylene terephthalate) encounters technical difficulties unlike poly(ethylene terephthalate) or poly(butylene terephthalate), and various problems are left to be overcome. To be brief, the technical difficulties to be overcome are the following three problems, namely, whiteness, spinning stability and melt stability.
The problem in the whiteness is the coloration of polymer to yellow at the polymerization stage, which incurs coloration of the fiber or cloth obtained and impairs the commercial performance. More specifically, the fields of inner wear, panty stocking, sportswear, outer wear and the like are considered to be particularly promising for making use of soft touch, excellent elastic recovery and easy care property of the poly(trimethylene terephthalate) fiber. In order to find a way into these commercial fields, the fiber must have sufficiently high whiteness, so that all dyed products of from light to heavy shades can form a brilliant color. However, the poly(trimethylene terephthalate) is readily colored at the stage of polymerization and even if a dyed fiber or cloth is produced using such a polymer, the dyed product is deficient in the color brilliancy and the commercial value is seriously impaired.
The problem in spinning stability is the adverse effect of many impurities contained in the polymer on the spinning stability. More specifically, in the polymerization step of poly(trimethylene terephthalate), a cyclic dimer or other cyclic or linear oligomers are produced in a large amount and these precipitate in the periphery of spinneret at the spinning to disadvantageously increase the frequency of yarn breaking or cleaning of the spinneret (called wiping cycle). In particular, the cyclic dimer is produced in a large amount and mainly gives rise to the above-described troubles.
The problem in the melt stability is the reduction in molecular weight of the polymer or the coloration of polymer at the melting due to poor thermal stability of the melted polymer. In particular, the easy occurrence of reduction in the molecular weight means that even if the molecular weight is high at the polymer stage, the molecular weight decreases at the stage of melt spinning. If such a phenomenon takes place, the fiber obtained can hardly have high tenacity. This adversely affects the fundamental performance of commercial product, such as a reduction in the tearing strength or bursting strength of the fabric obtained.
Conventional techniques are described below, however, there is no case where all of these three technical problems are overcome and a poly(ethylene terephthalate) fiber favored with excellent whiteness, easy production in industry and sufficiently high tenacity is obtained.
For improving the whiteness or spinnability of poly(trimethylene terephthalate), several methods are known.
For example, Japanese Unexamined Patent Publication (Kokai) No. 5-262862 discloses a technique of using a tin catalyst as the polymerization catalyst for improving the whiteness. However, according to studies by the present inventors, the whiteness is rather poorer than in the case of using titanium alkoxide as the catalyst, though the polymerization rate is very high when a tin catalyst is used. Also, zinc acetate and a tin catalyst are used as the ester exchange catalyst and the polycondensation catalyst, respectively. However, if only melt polymerization is performed using such a combination without passing through solid phase polymerization, the amount of cyclic dimer exceeds 3 wt % and the spinning stability is bad. Furthermore, in the Examples of this prior art, tridecyl phosphate is allowed to be present in an amount of at most 500 ppm during the polymerization. However, if such a compound having a long chain is present together, there arise problems such as bubbling at the dyeing state or easy occurrence of spotted dyeing. Moreover, if a tin catalyst or tridecyl phosphate is used, the fiber obtained is low in tenacity and can hardly have a tenacity of 3.5 g/d or more.
In addition, for improving the whiteness, use of a titanium catalyst as the ester exchange reaction catalyst and an antimony catalyst as the polycondensation catalyst has been proposed (see, Chemical, Fiber International, Vol. 45, pp. 263-264 (1996)). In this publication, formation of by-products is also referred to and it is stated that depending on the case, 3% or more of oligomer is contained in poly(trimethylene terephthalate) and these impurities cause problems in the spinning process or dyeing process. However, according to studies by the present inventors, when an antimony catalyst is used, the polymerization rate is reduced, therefore, the polymer is exposed at a high temperature for a longer time and the whiteness rather decreases. Furthermore, even in this publication, means for reducing the amount of cyclic dimer or improving the melt stability of polymer is not specifically described by any means.
As means for achieving improvement in the whiteness of poly(trimethylene terephthalate) and reduction of oligomer, Japanese Unexamined Patent Publication (Kokai) No. 8-311177 discloses a poly(trimethylene terephthalate) resin having an intrinsic viscosity of 0.9 or more, a ‘b’ value as an index for showing the degree of yellowing of chip of 10 or less and an oligomer content of 1 wt % or more, where the poly(trimethylene terephthalate) obtained by an ordinary manner is subjected to solid phase polymerization at a temperature of approximately from 190 to 200° C. under reduced pressure so as to reduce the production of white powder on the metal face or in the vicinity of spinneret at the spinning process and prevent yarn breaking. In the Examples of this prior art, a terephthalic acid and 1,3-propanediol are ester exchanged in the absence of a catalyst without using a phosphorus compound or a cobalt compound, thereafter, tetr
Fujimoto Katsuhiro
Kato Jinichiro
Takahashi Tetsuko
Acquah Samuel A.
Asahi Kasei Kabushiki Kaisha
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
LandOfFree
Polyester resin composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polyester resin composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polyester resin composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2869432