Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-12-20
2003-12-09
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S504000, C524S514000, C524S517000, C524S539000, C525S063000, C525S064000, C525S066000, C525S074000
Reexamination Certificate
active
06660796
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a material having good low-temperature impact strength and comprising, besides polyester as matrix polymer, at least two other polymers which act synergistically to improve the impact strength of the material. The invention further relates to moldings made from this material.
2. Discussion of the Background
Engineering components such as those used in the automotive industry sector nowadays have to fulfill very strict requirements with respect to low-temperature impact strength. To this end, tests are carried out using a variety of methods at test temperatures of, for example, −40° C.
However, thermoplastic polyesters that are used for automotive engineering components, for example as a barrier layer material for suppressing diffusion of fuel components through the wall of, for example, fuel lines, are to some extent brittle. Therefore, the developer is forced to modify these barrier layer materials in order to fulfill the appropriate requirements placed upon low-temperature impact strength. The modifiers commonly used for low impact strength, for example, EPM rubbers or EPDM rubbers, are materials which have a specific adverse effect on the barrier properties of polyesters with respect to fuels. Therefore, the content of modifiers for low-temperature impact strength cannot be increased as desired. Impact-modified polyesters are described in, for example, DE-A 26 22 876 or DE-A4401 165.
Another difficulty facing the developer of moldings is that thermoplastic polyesters have poor compatibility with the usual modifiers for low-temperature impact strength, for example, EPM or EPDM, even when these have been functionalized and contain anhydride groups, which is usually accomplished by free-radical grafting of the rubber with an ethylenically unsaturated anhydride. Poor compatibility is seen in poor bonding of the dispersed rubber to the matrix of the material at the phase boundary. Therefore, to achieve the desired low-temperature impact strength effect, very high concentrations of an EPM- or EPDM-based impact modifier have to be used. However, there is an adverse effect on other important properties, such as barrier action, resistance to solvents or to chemicals.
Therefore, a critical need exists to provide polyester molding compositions with improved low-temperature impact strength, and in particular to provide polyester molding compositions with good low-temperature impact strength but with the lowest possible content of impact modifiers, so that there is the smallest possible effect on other important properties. Furthermore, there is a need to provide moldings which have good low-temperature impact strength without making the barrier action with respect to fuel components, the solvent resistance or the chemicals resistance, unacceptably poorer than those of the matrix material.
SUMMARY OF THE INVENTION
These objects are achieved with a molding composition which comprises the following components:
I. from 60 to 96.6 parts by weight of thermoplastic polyesters,
II. from 3 to 39.5 parts by weight of an impact-modifying component which contains anhydride groups, where the impact-modifying component is selected from the group consisting of ethylene/&agr;-olefin copolymers and styrene-ethylene/butylene block copolymers,
III. from 0.4 to 20 parts by weight of a copolymer which contains units of the following monomers:
a) from 20 to 94.5% by weight of one or more &agr;-olefins having from 2 to 12 carbon atoms,
b) from 5 to 79.5% by weight of one or more acrylic compounds, selected from the group consisting of
acrylic acid and methacrylic acid and salts thereof,
esters of acrylic acid and/or of methacrylic acid with a C
1
-C
12
alcohol, which may carry, where appropriate, a free hydroxyl or epoxide function
acrylonitrile and methacrylonitrile,
acrylamides and methacrylamides, and
c) from 0.5 to 50% by weight of an olefinically unsaturated epoxide, carboxylic anhydride, carboximide, oxazoline or oxazinone,
where the total of the parts by weight of components I, II and III is 100.
In preferred embodiments, the molding composition comprises:
I. from 70 to 94 parts by weight, particularly preferably from 75 to 92 parts by weight, of polyester,
II. from 5 to 28 parts by weight, particularly preferably from 6 to 23 parts by weight, and particularly preferably from 7 to 22 parts by weight, of the impact-modifying component, and
III. from 0.6 to 15 parts by weight, particularly preferably from 0.7 to 10 parts by weight, of the copolymer, which preferably contains units of the following monomers:
a) from 30 to 80% by weight of &bgr;-olefin(s),
b) from 7 to 70% by weight, particularly preferably from 10 to 60% by weight, of the acrylic compound(s), and
c) from 1 to 40% by weight, particularly preferably from 5 to 30% by weight, of the olefinically unsaturated epoxide, carboxylic anhydride, carboximide, oxazoline, or oxazinone.
Other objects of the present invention include methods of preparing the molding compositions, methods of using the molding composition to make moldings and the molding prepared therein.
DETAILED DESCRIPTION OF THE INVENTION
Polyesters that may be used are thermoplastic polyesters of linear structure. These are prepared by polycondensing diols with dicarboxylic acid or with polyester-forming derivatives of these, such as dimethyl esters. Suitable diols have the formula HO—R—OH, where R is a divalent, branched or unbranched aliphatic and/or cycloaliphatic radical having from 2 to 40 carbon atoms, preferably from 2 to 12 carbon atoms. Suitable dicarboxylic acids have the formula HOOC—R′—COOH where R′ is a divalent aromatic radical having from 6 to 20 carbon atoms, preferably from 6 to 12 carbon atoms.
Examples of diols include ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, cyclohexane-dimethanol, and also the C
36
diol dimer diol. The diols may be used alone or as a diol mixture.
Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, 1,4-, 1,5-, 2,6- or 2,7-naphthalenedicarboxylic acid, diphenic acid and diphenyl ether 4,4′-dicarboxylic acid. Up to 30 mol % of these dicarboxylic acids may have been replaced by aliphatic or cycloaliphatic dicarboxylic acids having from 3 to 50 carbon atoms and more preferably having from 6 to 40 carbon atoms, e.g. succinic acid, adipic acid, sebacic acid, dodecanedioic acid or cyclohexane-1,4-dicarboxylic acid.
Examples of suitable polyesters include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene 2,6-naphthalate, polypropylene 2,6-naphthalate and polybutylene 2,6-naphthalate.
The preparation of these polyesters has been described previously, for example, see DE-A 24 07 155, DE-A 24 07 156; Ullmanns Encyclopädie der technischen Chemie [Ullmann's Encyclopedia of Industrial Chemistry], 4
th
Edn., Vol. 19, pp. 65 et seq, Verlag Chemie, Weinheim, 1980, the contents of which are incorporated by reference.
Preferred suitable ethylene/&agr;-olefin copolymers of component II include:
ethylene/C
3
-C
12
-&agr;-olefin copolymers containing from 20 to 96% by weight, preferably from 25 to 85% by weight, of ethylene. Examples of C
3
-C
12
-&agr;-olefins used are propene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene or 1-dodecene. Typical examples of these materials are ethylene-propylene rubber and also LLDPE and VLDPE.
ethylene/C
3
-C
12
-&agr;-olefin/unconjugated-diene terpolymers containing from 20 to 96% by weight, preferably from 25 to 85% by weight, of ethylene and up to at most about 10% by weight of an unconjugated diene, such as bicyclo[2.2.1]heptadiene, 1,4-hexadiene, dicyclopentadiene or in particular 5-ethylidenenorbornene. Examples of suitable C
3
-C
12
-&agr;-olefins are propene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene or 1-dodecene.
The preparation of these copolymers or terpolymers with the aid of a Ziegler-Natta catalyst has been described previously (Kirk-Othme
Haeger Harald
Oenbrink Georg
Peirick Heinz
Schmitz Guido
Schueler Ralf
Degussa - AG
Niland Patrick D.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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