Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1990-06-04
1993-06-01
Short, Patricia A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525437, 524539, C08L 6703, C08L 6704
Patent
active
052160920
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a blend comprising a first LCP polyester polymer consisting essentially of units (I), (II), (III), and (IV). ##STR2## having a melting point under about 420.degree. C., p is approximately equal to r+q, r is from about 0.05 to about 0.9, q is from about 0.95 to about 0.1 and s is from about 0.05 to about 9, and a second LCP polyester polymer comprising at least one moiety selected from the group consisting of hydroxybenzoic acid, hydroxynaphthalene carboxylic acid, dihydroxy naphthalene, naphthalene dicarboxylic acid, oxybisbenzoic acid and substituted hydroquinones wherein the said moiety of moieties comprise(s) at least about 5 mole percent of the units in said second LCP polyester.
Wholly aromatic polyester resins have long been known. For instance, 4-hydroxybenzoic acid homopolymer and copolymers have been described in the past and are commercially available. Such polymers commonly are crystalline in nature and, when molten, frequently exhibit orientation in the melt; however, they have relatively high melting points or possess a decomposition temperature which is below the melting point, which leads to great difficulty in processing.
The homopolymer of p-hydroxybenzoic acid is a very high melting, insoluble material and, hence, very difficult to fabricate. Melting points as high as 610.degree. C. were quoted--see W. J. Jackson, The British Polymer Journal, December 1980, p. 155. In order to depress the high melting point of the homopolymer so as to make it melt fabricable, a variety of materials incorporating different types of comonomers were prepared over the years.
One such material is, for example, the resin made from p-hydroxybenzoic acid, isophthalic and/or terephthalic acids and 4,4'-biphenol as described in Cottis et al., U.S. Pat. Nos. 3,673,595 and 3,975,487. The polymer has outstanding high temperature properties and can be molded to give articles of high modulus and strength. It is offered commercially by Amoco Performance Products, Inc. under the trade name of Xydar.RTM.. These LCPs usually contain a relatively high percent concentration of hydroxybenzoic acid to reduce the concentration of the expensive biphenol.
The main drawback of the prior art p-hydroxybenzoic acid copolymers and LCP polyesters containing no p-hydroxybenzoic acid moieties is the relatively high cost associated with the use of an expensive comonomer, such as 4,4'-biphenol, substituted hydroquinones (e.g., phenylhydroquinone), naphthalene diols, naphthalene dicarboxylic acids, and hydroxy-naphthoic acids. Efforts to replace these expensive monomers with the significantly less expensive hydroquinone, which is disclosed as an equivalent of biphenol in the aforementioned U.S. Pat. Nos. 3,637,595 and 3,075,487, were made by several research groups; however, none of these investigations were successful.
Study of the prior art shows that replacement of 4,4'-biphenol with hydroquinone leads to materials with inferior properties. The problem created by the introduction of hydroquinone is basically the following: at high terephthalate contents, high melting generally intractable polymers are obtained; tractability may be achieved at higher isophthalate levels, but the polyesters are relatively low melting and often display low second order glass transition temperatures which lead to low moduli and low heat distortion temperatures. For example, polyesters from p-hydroxybenzoic acid (PHBA) isophthalic acid (IA) and hydroquinone (HQ) were prepared by Deex, U.S. Pat. No. 4,377,681. At mole ratios PHBA/IA/HQ of 33.3/33.3/33.3 the material had a glass transition temperature of 110.degree. C.; when the above coreactants were used at ratios of 50/25/25, a Tg of 115.degree. C. was obtained.
The high melting points of a series of p-hydroxybenzoic acid/terephthalic acid/hydroquinone copolymers are graphically illustrated in FIG. 2 of the paper by G. W. Calundann, Industrial Development of Thermotropic Polyesters in High Performance Polymers: Their Origin and Development, 233-249 (R. B. Seymour and G. S. Kirshenbau
REFERENCES:
patent: 4414365 (1983-11-01), Sugimoto
patent: 4563508 (1986-01-01), Cottis
patent: 5091464 (1992-02-01), Huspeni
Frayer Paul D.
Huspeni Paul J.
Layton Richard
Matzner Markus
Stern Brian A.
Amoco Corporation
Hensley Stephen L.
Hooper Matthew R.
Short Patricia A.
Sroka Frank J.
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