Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-09-26
2003-07-22
Mullis, Jeffrey (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S064000, C525S066000, C525S069000
Reexamination Certificate
active
06596811
ABSTRACT:
The invention relates to thermoplastic molding compositions with high puncture resistance and good antistatic performance. The molding compositions are impact-modified copolymers of styrene and/or &agr;-methylstyrene with acrylonitrile.
Impact-modified styrene-acrylonitrile copolymers are used in a wide variety of applications. They are preferably used for producing moldings which are to have good mechanical properties. It is frequently necessary for molding compositions of this type to be given antistatic properties. This is generally done by adding an antistat to the molding compositions. To ensure sufficient breadth of application for the molding compositions it is desirable to make them suitable for a wide range of working conditions.
FR-B-1 239 902 has disclosed re sins which have been given antistatic properties. Three-block copolymers of the formula X-Y-X can be added, inter alia, to molding compositions having polystyrene units, polyacrylo-nitrile units and polybutadiene units. Y here is a polypropylene oxide block with a molecular weight of from 1000 to 1800 and each X is a polyethylene oxide block. The proportion of polyethylene oxide is from 20 to 80%.
It is known from EP-B 0 018 591 that the abovementioned three-block copolymers of the formula X-Y-X can be added to styrene-acrylonitrile copolymers with no rubber component. The addition increases the internal lubrication of the molding compositions, giving an improvement in processing latitude in injection molding. The molecular weight of the block Y in the three-block copolymer may be from 1200 to 3650, and the proportion of ethylene oxide units is from 10 to 30% by weight.
It is known from EP-A-0 135 801 that the abovementioned three-block copolymers of the formula X-Y-X can be added to polymer blends made from polycarbonate and impact-modified styrene-acrylonitrile copolymer to improve processing latitude. Here, the molecular weight of the polypropylene oxide block Y is, for example, 1200, 2250 or 3600. The proportion of ethylene oxide here is 10 or 40% by weight.
It is an object of the present invention to provide impact-modified copolymers of styrene and/or &agr;-methylstyrene with acrylonitrile which have increased puncture resistance and at the same time good antistatic performance.
We have found that this object is achieved by means of a molding composition made from components A to C and, if desired, D:
a: as component A, from 20 to 94% by weight of a hard component made from one or more copolymers of styrene and/or &agr;-methylstyrene with acrylonitrile, where the proportion of acrylonitrile is from 10 to 50% by weight,
b: from 5 to 70% by weight of at least one graft copolymer B, made from
b1 : as component B1, from 10 to 90% by weight of at least one elastomeric particulate graft base with a glass transition temperature below 0° C., and
b2: as component B2, from 10 to 90% by weight of at least one graft made from a copolymer below 0° C., and
b2: as component B2, from 10 to 90% by weight of at least one graft made from a copolymer of styrene and/or &agr;-methylstyrene with acrylonitrile, where the proportion of acrylonitrile is from 10 to 50% by weight,
c: as component C, from 0.1 to 10% by weight of at least one three-block copolymer of the formula X-Y-X with a central block Y made from propylene oxide units with an average molecular weight in the range from 2000 to 4000 and terminal blocks X made from ethylene oxide units whose average proportion in the three-block copolymer is from 2 to 35% by weight,
where the total weight of components A to C is 100% by weight, and
d: as component D, from 0 to 10% by weight, based on the total weight of components A to C, of other conventional auxiliaries and fillers.
Molding compositions with components A, B and D and suitable to be given these properties have been described, for example, in DE-A-29 01 576 and in particular in the earlier document DE-A-197 28 629 which, however, was unpublished at the priority date of the present application.
The proportion of component A in the novel molding compositions is preferably from 40 to 84.9% by weight, particularly preferably from 55 to 79.7% by weight. The proportion of component B is preferably from 15 to 50% by weight, particularly preferably from 20 to 40% by weight. The proportion of component C is preferably from 0.1 to 5% by weight, particularly preferably from 0.3 to 2% by weight. The proportion of component D is preferably from 0 to 5% by weight, particularly preferably from 0 to 3% by weight.
The proportion of acrylonitrile in component A is preferably from 10 to 50% by weight, particularly preferably from 15 to 40% by weight, in particular from 18.5 to 36% by weight.
In component B, the proportion of component B1 is preferably from 20 to 80% by weight, particularly preferably from 25 to 75% by weight, and the proportion of component B2 is preferably from 20 to 80% by weight, particularly preferably from 25 to 75% by weight. The proportion of acrylonitrile in component B2 here is preferably from 15 to 40% by weight, particularly preferably from 15 to 35% by weight.
In component C, the average molecular weight of the block Y made from propylene oxide units is preferably from 2200 to 3800, particularly preferably from 2300 to 3500, in particular about 2300, about 2750 or about 3250, in each case +/−10%. The average proportion of the terminal blocks X made from ethylene oxide units, based on component C, is preferably from 3 to 28% by weight, particularly preferably from 8 to 24% by weight, in particular from about 8 to 14% by weight or from about 18 to 24% by weight.
Component A
Component A preferably has a viscosity number VN (determined in accordance with DIN 53726 at 25° C., 0.5% strength by weight in dimethylformamide) of from 50 to 120 ml/g, particularly preferably from 52 to 110 ml/g and in particular from 55 to 105 ml/g. It is particularly preferably a styrene-acrylonitrile copolymer. Copolymers of this type are obtained in a known manner by bulk, solution, suspension, precipitation or emulsion polymerization. Bulk and solution polymerization are preferred. Details of these processes are described, for example, in Kunststoffhandbuch, ed. R. Vieweg and G. Daumiller, vol. V “Polystyrol”, Carl-Hanser-Verlag Munich, 1969, pp. 118 ff.
Component B
Component B is a graft copolymer with an elastomeric particulate graft base with a glass transition temperature below 0° C. The graft base here may have been selected from all of the known suitable elastomeric polymers. It is preferably ABS (acrylonitrile-butadiene-styrene) rubber, ASA (acrylo-nitrile-styrene-alkyl acrylate) rubber, EPDM rubber, siloxane rubber or another rubber.
Component B1 is preferably at least one (co)polymer made from
b11: as component B11, from 60 to 100% by weight, preferably from 70 to 100% by weight, of at least one conjugated diene, of a C
1
-C
10
-alkyl acrylate, or of a mixture of these,
b12: as component B12, from 0 to 30% by weight, preferably from 0 to 25% by weight, of at least one monoethylenically unsaturated monomer differing from component B11, and
b13: as component B13, from 0 to 10% by weight, preferably from 0 to 6% by weight, of at least one crosslinking monomer.
Possible conjugated dienes B11 are in particular butadiene, isoprene, chloroprene and mixtures of these, and also the C
1
-C
10
-alkyl acrylates listed below and mixtures of these. Preference is given to the use of butadiene or isoprene or mixtures of these, especially butadiene, or of n-butyl acrylate.
The monomers present as component B12 may, if desired, be monomers which vary the mechanical and thermal properties of the core within a particular range. Examples of monoethylenically unsaturated comonomers of this type which may be mentioned are styrene, substituted styrenes, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, dicarboxylic acids, such as maleic acid and fumaric acid, and also anhydrides of these, such as maleic anhydride, nitrogen-functional monomers, such as dimethylamino-ethyl acrylate, diethylaminoethyl acrylate, vinylimida
Barghoorn Peter
Ittemann Peter
BASF - Aktiengesellschaft
Keil & Weinkauf
Mullis Jeffrey
LandOfFree
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