Polyester molding composition

Details Polyester molding composition Polyester molding composition

2000-04-18

2002-09-03

Michl, Paul R. (Department: 1714)

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

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S169000, C525S171000

Reexamination Certificate

active

06444753

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to blends of polyester resin.
SUMMARY OF THE INVENTION
Blends of polybutylene terephthalate with styrenic impact modifier (PBT/Styrenic) give good mechanical properties such as impact strength, high Vicat values and chemical resistance. For certain applications, such as interior automotive parts, it is desirable for the surface of a part after injection molding to have low gloss. The surface in these applications is normally textured, and it is desirable that the gloss level is low. These blends, however, do not show gloss levels that are low enough. The problem to be solved is to formulate a PBT/Styrenic impact modifier blend formulation that has low gloss on a textured surface.
Some polyester/ABS blends are described in the following references. EP 383058A1 to Liu et al describes a polyester with ABS. DE 4101699 to Bayer describes a composition including a polyester in the amount from 30 to 80 percent with styrenic modifiers. U.S. Pat. No. 4,292,233 to Binsack et al describes improving the toughness of PBT by adding an ABS-graft copolymer having a high content of graft base and a defined particle size. U.S. Pat. No. 4,753,986 to Wang describes improving the impact strength of linear polyesters by incorporating a core-shell impact modifier. EP 614943A2 to Kuruganti et al describes a PBT blend with rubber graft (grafted vinyl aromatic and vinyl cyanide monomers (ABS)), and with non-grafted vinylcyanide-vinyl aromatic copolymer (SAN), and with carboxylic fatty acid metal salts. U.S. Pat. No. 5,475,053 to Niessner et al relates to an impact modified molding composition containing a thermoplastic with an acrylate based matting agent. U.S. Pat. No. 5,162,416 to Udipi relates to impact resistant polymer blends of polyester, ABS and an impact modifying amount of a fatty acid salt. U.S. Pat. No. 5,210,134 to Akkapeddi relates to a modified styrenic polymer comprising a polyester and a maleated ABS. U.S. Pat. No. 3,954,903 to Kudo et al describes an impact resistant ABS resin including a saturated polyester.
The references are deficient in describing a solution to the problem of achieving high impact, low gloss properties with the PBT/Styrenic impact modifier blend. Hence, it is desired to have a PBT/Styrenic impact modifier blend formulation that is low gloss on a textured surface.
SUMMARY OF THE INVENTION
It has been found that gloss reducing amounts of polyethylene terephthalate (PET) or polyester ionomer, or mixtures thereof may be used a in a blend of PBT and a styrene polymer to provide low gloss on a textured surface. Examples of polymers referred to as styrene polymers are acrylonitrile-butadiene-styrene (ABS), acrylonitrile-butadiene-alpha-methylstyrene, styrene-butadiene, styrene butadiene styrene (SBS), styrene ethylene butylene styrene (SEBS), methacrylate-butadiene-styrene (MBS), acrylate-styrene-acrylonitrile (ASA), acrylonitrile-EPDM-styrene (AES) and other high impact styrene-containing polymers.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The terms PBT ionomer, PBT containing ionomeric groups, polyester ionomer, or sulfonate polyester or metal sulfonate polyester, generally refers to polyester polymers derived from the reaction residue of an aryl carboxylic sulfonate salt, an aromatic dicarboxylic acid, an aliphatic diol or any of their ester forming derivatives. The ionomer polyester polymers comprise some monovalent and/or divalent sulfonate salt units represented by the formula IA:
or formula IB:
(M
+n
O
3
S)
d
-A-(OR″OH)
p
wherein p=1-3; d=1-3, and p+d=2-6, and A is an aryl group containing one or more aromatic rings; for example, benzene, naphthalene, anthracene, biphenyl, terphenyl, oxy diplienyl, sulfonyl diphenyl or alkyl diphenyl, where the sulfonate substituent is directly attached to an aryl ring. These groups are incorporated into the polyester through carboxylic ester linkages. The aryl groups may contain one or more sulfonate substituents; d=1-3 and may have one or more carboxylic acid linkages; p=1-3. Groups with one sulfonate substituent (d=1) and two carboxylic linkages (p=2) are preferred. M is a metal, n=1-5. Preferred metals are alkaline or alkaline earth metals where n=1-2. Zinc and tin are also preferred metals. R″ is a divalent group, for example, —CH
2
CH
2
—, —CH
2
CH
2
OCH
2
CH
2
—, —CH(CH
3
)CH
2
—, —CH
2
CH
2
CH
2
—, and —CH
2
CH
2
CH
2
.
Typical sulfonate substituents that can be incorporated into the metal sulfonate polyester copolymer may be derived from the following carboxylic acids or their ester forming derivatives: sodium sulfo isophthalic acid, potassium sulfo terephthalic acid, sodium sulfo naphthalene dicarboxylic acid, calcium sulfo isophthalate, potassium 4,4′-di(carbomethoxy)biphenyl sulfonate, lithium 3,5-di(carbomethoxy)benzene sulfonate, sodium p-carbomethoxy benzene sulfonate, dipotassium 5-carbomethoxy-1,3-disulfonate, sodio 4-sulfo naphthalene-2,7-dicarboxylic acid, 4-lithio sulfophenyl-3,5-dicarboxy benzene sulfonate, 6-sodiosulfo-2-naphthyl-3,5-dicarbomethoxy benzene sulfonate and dimethyl 5-(4-(sodiosulfo)phenoxy) isophthalate. Other suitable sulfonate carboxylic acids and their ester forming derivatives are described in U.S. Pat. Nos. 3,018,272 and 3,546,008. The most preferred sulfonate polyesters are derived from sodium 3,5-dicarbomethoxy benzene sulfonate.
One ionomer polyester polymer comprises divalent ionomer units represented by the formula III:
wherein R is hydrogen, halogen, alkyl or aryl, and M is a metal.
Another polyester ionomer has the formula IV:
where the ionomer units, x, are from 0.1-50 mole percent of the polymer with 0.5 to 10 mole percent being preferred. Most preferably R is hydrogen. When R is hydrogen, R
1
is phenylene, and A
1
is an alkylene radical of from C1-C12, preferably from C2 or C4, and x and y are in mole percent, then x is from about 1 to about 20 percent, and more preferably from about 2 to about 15 percent, and most preferably from about 3 to about 12 percent.
Typical glycol or diol reactants, R
1
, include straight chain, branched, or cycloaliphatic alkane diols and may contain from 2 to 12 carbon atoms. Examples of such diols include but are not limited to ethylene glycol; propylene glycol, i.e., 1,2- and 1,3-propylene glycol; butane diol, i.e., 1,3- and 1,4-butane diol; diethylene glycol; 2,2-dimethyl-1,3-propane diol; 2-ethyl, 2-methyl, 1,3-propane diol; 1,3- and 1,5-pentane diol; dipropylene glycol; 2-methyl-1,5-pentane diol; 1,6-hexane diol; dimethanol decalin, dimethanol bicyclo octane; 1,4-cyclohexane dimethanol and particularly its cis- and trans-isomers; triethylene glycol; 1,10-decane diol; and mixtures of any of the foregoing. A preferred cycloaliphatic diol is 1,4-cyclohexane dimethanol or its chemical equivalent. When cycloaliphatic diols are used as the diol component, a mixture of cis- to trans-isomers may be used, it is preferred to have a trans isomer content of 70% or more. Chemical equivalents to the diols include esters, such as dialkyl esters, diaryl esters and the like.
Examples of aromatic dicarboxylic acid reactants, as represented by the decarboxylated residue A
1
, are isophthalic or terephthalic acid, 1,2-di(p-carboxyphenyl)ethane, 4,4′-dicarboxydiphenyl ether, 4,4′ bisbenzoic acid and mixtures thereof. All of these acids contain at least one aromatic nucleus. Acids containing fused rings can also be present, such as in 1,4-1,5- or 2,6-naphthalene dicarboxylic acids. The preferred dicarboxylic acids are terephthalic acid, isophthalic acid or mixtures thereof.
Ionomer polyesters include poly(ethylene terephthalate) (PET) ionomers, and poly(1,4-butylene terephthalate)ionomers, (PBT), and (polypropylene terephthalate) (PPT) ionomers.
One poly(1,4-butylene terephthalate)ionomer resin is obtained by polymerizing an ionomer component comprising a dimethyl 5-sodium sulfo-1,3-phenylenedicarboxylate, from 1 to 10 mole %, a glycol component of at least 70 mole %, preferably at least 90 mole %, of tetramethylen

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