Stock material or miscellaneous articles – Composite – Of polyamide
Reexamination Certificate
2001-12-21
2004-04-27
Woodward, Ana L. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polyamide
C428S475200, C428S475500, C524S538000, C525S425000
Reexamination Certificate
active
06726999
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a free-flowing polyester molding composition, in particular for injection molding, and also to a molding produced from this polyester molding composition.
2. Discussion of the Background
In electrical engineering and the electronics industry, the trend is toward ever smaller components. This means that the requirements for flowability of plastics are constantly increasing.
A simple way of improving the flowability of plastics is to reduce the molecular weight. However, there are certain limits here, since any excessively drastic reduction in the molecular weight also has an adverse effect on the mechanical properties of the plastics.
Instead of reducing the molecular weight, there is also the possibility of improving the flow performance of plastics by using flow promoters, such as stearates or montanic esters. For example, JP-A-04 275 327 and DE-A-30 31 491 describe an improvement in the flowability of polyesters on adding pentaerythritol tetrastearate. However, low-molecular-weight esters of this type can bleed out during processing or during use of the resultant molding. In addition, purely aliphatic ester groups of this type are susceptible to hydrolysis, and the degradation products can bleed out and/or damage the polyester matrix. These problems also occur when using trialkyl phosphates, as described in JP-A-55 012 103.
JP-A-11 049 939 and JP-A-03 095 256 propose mixing a polyester with polyalkenyl glycol benzoates to improve flowability. However, on mixing the melts transesterification reactions occur here—as in the abovementioned cases in which other esters are added. In this case the product is a block copolyetherester, i.e. a polymer which is a thermoplastic elastomer with a quite different property profile.
DE-A-19 15 772 discloses a mixture suitable for producing filaments, yarns and bands of improved dye-ability, and the like, and comprising from 5 to 80% by weight of a polyimine-polyamide graft copolymer and from 95 to 20% by weight of a polyester. However, these mixtures are not used for producing moldings. Nor is it apparent from DE-A-19 15 772 that the graft copolymer is suitable as a flow auxiliary for polyester molding compositions. Nor is there any recognition in DE-A-19 15 772 that the compatibility of the polyester and the graft copolymer in the range now claimed below is so good that there is very substantially no adverse effect on the mechanical properties of the polyester. Rather, the results of DE-A-19 15 772 imply that, as stated in its Example 3, the incompatibility of a mixture made from 50 parts of graft copolymer and 50 parts of polyethylene terephthalate is so high that it delaminates under mechanical stress. A result of this type is more likely to dissuade the skilled worker from studying molding compositions that comprise polyester and graft copolymers of this type for the production of moldings.
German patent application 100 05 641.5, unpublished at the priority date of the present specification, discloses molding compositions which comprise at least 5 parts by weight of a polyamine-polyamide graft copolymer and up to 95 parts by weight of polyester, or a mixture made from polyester and polyamide. These molding compositions are used as adhesion promoters in composites having two or more layers.
There is a need to improve the flowability of polyesters without any substantial adverse change in the mechanical properties of the polyester, and without bleed-out, during processing or from the molding, of the flow promoter added.
SUMMARY OF THE INVENTION
The present invention provides a polyester molding composition with an improved combination of flowability and mechanical properties. The molding composition comprises from 80 to 99.9 parts by weight of thermoplastic polyester and from 0.1 to 20 parts by weight of a polyamine-polyamide graft copolymer described in further detail below, where the total of the parts by weight of the polyester and of the graft copolymer is 100.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
A first aspect of the present invention is based on providing a molding composition which comprises the following components:
I. from 0.1 to less than 5 parts by weight, preferably at least 0.2 parts by weight, and particularly preferably at least 0.3 parts by weight, of a polyamine-polyamide graft copolymer described in further detail below, and
II. from more than 95 to 99.9 parts by weight of a thermoplastic polyester, where the total of the parts by weight of I and II is 100.
The invention also provides moldings produced using this molding composition.
A second aspect of the present invention is based on providing an injection molding composition which comprises the following components:
I. from 0.1 to 20 parts by weight, preferably from 0.2 to 10 parts by weight, and particularly preferably from at least 0.3 to less than 5 parts by weight, of a polyamine-polyamide graft copolymer described in further detail below, and
II. from 80 to 99.9 parts by weight, preferably from 90 to 99.8 parts by weight, and particularly preferably from more than 95 to 99.7 parts by weight, of a thermoplastic polyester,
where the total of the parts by weight of I and II is 100.
The invention also provides moldings produced by injection molding, using this injection molding composition.
A third aspect of the invention is based on providing a molding composition which comprises the following components,
A. from 40 to 99.5% by weight of a mixture made from
I. from 0.1 to 20 parts by weight, preferably from 0.2 to 10 parts by weight, and particularly preferably from 0.3 to less than 5 parts by weight, of a polyamine-polyamide graft copolymer described in further detail below, and
II. from 80 to 99.9 parts by weight, preferably from 90 to 99.8 parts by weight, and particularly preferably from more than 95 to 99.7 parts by weight, of a thermoplastic polyester,
where the total of the parts by weight of I and II is 100, and
B. from 0.5 to 60% by weight, preferably from 2 to 55% by weight, and particularly preferably from 4 to 50% by weight, of particulate, laminar and/or fibrous additives selected from fillers, pigments, reinforcing materials, additives which give the molding composition antistatic properties or electrical conductivity, nucleating agents, and particulate flame retardants.
The flow-promoting action of the graft copolymer is capable of counteracting the viscosity-increasing action of component B., and it is therefore possible to prepare particularly highly filled molding compositions.
The invention also provides moldings produced using this molding composition.
Thermoplastic polyesters are prepared by polycondensing diols with dicarboxylic acids 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 which may be mentioned for diols are ethylene glycol, trimethylene glycol, tetramethylene glycol, but-2-ene-1,4-diol, hexamethylene glycol, neopentyl glycol, cyclohexanedimethanol, and also the C
36
diol dimer diol. The diols may be used alone or as a diol mixture.
Examples of aromatic dicarboxylic acids which may be used are terephthalic acid, isophthalic acid, 1,4-, 1,5-, 2,6- and 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, 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 are polyethylene terephthalate, polypropylene terephthalate, polybuty
Haeger Harald
Peirick Heinz
Richter Ralf
Schueler Ralf
Degussa - AG
Woodward Ana L.
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