Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-11-30
2001-08-21
Sanders, Kriellion (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S120000, C524S153000, C524S372000, C524S411000, C524S445000, C524S449000, C524S451000, C524S494000
Reexamination Certificate
active
06277905
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for improving the toughness of a fiber reinforced, flame retardant (FR) poly(cyclohexylenedimethylene terephthalate) (PCT) formulation.
BACKGROUND OF THE INVENTION
Certain electronics must be soldered at high temperatures and require high heat deflection temperature (HDT) materials. Such materials typically have high melting points and thus must be melt processed at relatively high temperatures. PCT is a high-melting polyester with a melting point of about 290° C. and, consequently, is very challenging to formulate while retaining good molecular weight. In addition to good melt stability, good dimensional stability, flammability, and toughness characteristics are important.
In the industry, use of tougheners in polymers has been known for some time. However, in most cases, HDT is sacrificed in order to achieve the characteristic of toughness.
U.S. Pat. No. 5,021,495 by Minnick discloses high temperature glass fiber reinforced, flame retardant PCT formulations. In the Minnick patent, it is shown that use of functional olefins (not acrylate/methacrylate rubber impact modifiers) can improve flame retardancy without hurting dimensional stability. These materials did not improve the toughness of the PCT formulations.
U.S. Pat. No. 5,428,086 discloses high temperature glass fiber reinforced, flame retardant PCT formulations. This patent discloses that certain additives can compromise the dimensional stability of the PCT formulation.
BRIEF SUMMARY OF THE INVENTION
This invention relates to a process for improving the toughness of a polymer composition comprising blending:
(A) a polyester comprising:
(1) terephthalic acid in the amount of 85 to 100 mole % based on the mole percentages of the dicarboxylic acid component equaling a total of 100 mole %.
(2) a glycol component comprising from about 60 to 100 mole % 1,4-cyclohexanedimethanol based on the mole percentages of the glycol component equaling a total of 100 mole %;
(B) one or more rubber impact modifiers;
(C) one or more halogenated organic compounds containing at least one imide group having a melting point of greater than 240° C.; and
(D) reinforcing fiber.
A preferred embodiment of the composition useful in this invention comprises sodium antimonate and or one or more phosphorous based compounds.
The polymer composition useful in the process of this invention has improved dimensional stability, improved toughness, and improved flammability characteristics that are particularly useful in high temperature electronics. Certain embodiments of the composition useful in this invention also have improved melt stability.
DETAILED DESCRIPTION
This invention relates to a process for improving the toughness of a fiber reinforced, flame retardant (FR) poly(cyclohexylenedimethylene terephthalate) (PCT) formulation. Dimensional stability and flammability characteristics are also improved in the process of this invention.
Specifically, the formulation produced by the process of this invention simultaneously achieves improved dimensional stability (as demonstrated by Heat Deflection Temperature above 260° C.) and improved toughness (as demonstrated by tensile elongation as measured by ASTM Method 638). At the same time, formulations must have acceptable flammability characteristics to be useful. This is typified by UL-94 flammability testing. Also, the relative hazard or environmental load of the metallic synergist can be considered in evaluating the usefulness of the invention.
It is preferred in this invention that the polyester comprise 90 mole % or more of terephthalic acid based on the mole percentages of the dicarboxylic acid component of the polyester equaling a total of 100 mole %. By terephthalic acid, suitable synthetic equivalents, such as dimethyl terephthalate, are included.
The polyester useful in this invention comprises 0 to 15 mole %, preferably 0 to 10 mole %, of dicarboxylic acids other than terephthalic acid, based on the mole percentages of the dicarboxylic acid component of the polyester equaling a total of 100 mole %. The other dicarboxylic acids include, but are not limited to, aromatic dicarboxylic acids preferably having 4 to 40 carbon atoms, more preferably, 8 to 14 carbon atoms; aliphatic dicarboxylic acids having, preferably 4 to 40 carbon atoms, more preferably, 4 to 12 carbon atoms; or cycloaliphatic dicarboxylic acids having 4 to 40 carbon atoms, more preferably, 8 to 12 carbon atoms.
Particularly preferred examples of other dicarboxylic acids useful in forming the copolyester useful in this invention include, but are not limited to, isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, 1,4-cyclohexanediacetic acid, diphenyl-4,4′-dicarboxylic acid, naphthalenedicarboxylate, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and the like.
Of these, isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid and naphthalenedicarboxyate are preferred, either singly or in combination.
When cyclohexanedicarboxylic acid is used as a comonomer in the context of the invention, trans-, cis-, or cis/trans mixtures may be used.
Any of the naphthalenedicarboxylic acid isomers or mixtures of isomers may be used. Some preferred naphthalenedicarboxylic acid isomers include 2,6-, 2,7- 1,4- and 1,5-isomers.
It should be understood that “dicarboxylic acids” includes the corresponding acid anhydrides, esters, and acid chlorides of these acids. In the acid component of this invention, the mole percentages of the acids of the polyester referred to herein equal a total of 100 mole %.
In the glycol component of the polyester useful in this invention, the mole percentages of the glycols referred to herein equal a total of 100 mole %.
It is preferred that the glycol component of the polyester useful in the invention contain from about 80 to 100 mole %, preferably 90 to 100 mole %, of one or more isomers of 1,4-cyclohexanedimethanol.
Preferably, the polyesters useful in this invention may be based on trans-, or cis/trans mixtures of 1,4-cyclohexanedimethanol. For example, a 30/70 cis/trans mixture of the isomers may be readily used.
The glycol component may comprise up to 20 mole %, and more preferably, up to 10 mole %, of one or more other aliphatic or alicyclic glycols.
Such additional diols include cycloaliphatic diols preferably having 6 to 20 carbon atoms or aliphatic diols preferably having 2 to 20 carbon atoms. Examples of such diols are: ethylene glycol, diethylene glycol, triethylene glycol, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, 3-methylpentanediol-(2,4), 2-methylpentanediol-(1,4), 2,2,4-trimethylpentane-diol-(1,3), 2-ethylhexanediol-(1,3), 2,2-diethylpropane-diol-(1,3), hexanediol-(1,3), 1,4-di-(hydroxyethoxy)-benzene, 2,2-bis-(4-hydroxycyclohexyl)-propane, 2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane, 2,2-bis-(3-hydroxyethoxyphenyl)-propane, decalin diol, and 2,2-bis-(4-hydroxypropoxyphenyl)-propane. Copolyesters may be prepared from the above diols in addition to the 1,4-cyclohexanedimethanol.
It is more preferred that the one or more glycols are selected from ethylene glycol, diethylene glycol, triethylene glycol, propanediol, butanediol, pentanediol, hexanediol, and tetramethylcyclobutanediol.
When the polyester of the process of this invention contains ethylene glycol, it is preferable that the ethylene glycol be present in an amount less than 20 mole %, more preferably, less than 10 mole %.
Copolyesters containing substantially only 1,4-cyclohexanedimethanol and terephthalic acid or substantially only 1,4-cyclohexanedimethanol, isophthalic, and terephthalic acid are preferred.
The polyester resins useful in this invention are well known and are commercially available. By the term “polyester”, copolyesters are also intended. Methods for their preparation are described, for example, in U.S. Pat. No. 2,465,319 and 3,047,539. For example, the polyesters can be prepared by direct condensation of terephthalic acid or ester interchange using dimethyl terephthalate with
Boshears Betty J.
Eastman Chemical Company
Graves Bernard
Sanders Kriellion
Tubach Cheryl
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