Thermoplastic molding materials

Details Thermoplastic molding materials Thermoplastic molding materials

2001-08-09

2003-08-19

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...

C525S071000, C525S080000, C525S086000

Reexamination Certificate

active

06608139

ABSTRACT:

The invention relates to thermoplastic molding compositions based on ASA (acrylonitrile-styrene-acrylate) and comprising acrylate copolymers and having improved flowability and improved extrusion properties. The invention further relates to a process for preparing these thermoplastic molding compositions and to their use, and also to films, moldings and coatings produced therefrom and having reduced gloss, and to the use of these.
There is a wide variety of application sectors for thermoplastic molding compositions, and there is therefore a variety of known molding compositions with differing mixes for different application sectors.
EP-A 0 526 813 describes polymer blends for flexible films. These are made from a graft copolymer of vinyl monomers as graft shell on an acrylate rubber as graft base, a partially crosslinked copolymer rubber based on acrylate, an uncrosslinked polymer based on styrene compounds and/or on acrylic compounds and an ethylene-vinyl acetate copolymer. The plastic material which can be obtained, in which no PVC is present, is suitable for producing leather-like films. However, these mixtures tend to discolor undesirably during processing and have a disadvantageous relationship between tensile strength and elongation at break. Films of this type also exhibit relatively severe fogging when processed by methods similar to those conventionally used.
DE-A 31 49 358 relates to thermoplastic molding compositions obtainable from a graft copolymer with a core made from a crosslinked alkyl acrylate and, if desired, from comonomers and with a shell obtainable by polymerizing a vinylaromatic monomer with an ethylenically unsaturated monomer, and with a copolymer obtainable by polymerizing a vinylaromatic monomer with an ethylenically unsaturated monomer. Films produced from these thermoplastic molding compositions have the disadvantage of excessively low elongation at break together with excessively high hardness. Molding compositions of this type are moreover unsuitable for soft coextrusion compositions.
Plastic films with reduced-gloss surface and leather-like appearance are used, for example, for interior trim in motor vehicles. The plastic usually used nowadays is PVC, mixed with a variety of vinyl polymers and plasticizers. These films are not fully aging-resistant at high temperatures, and they comprise volatile constituents and naturally contain halogen (see DE-A 42 11 415).
The use of acrylate copolymers (component (D)) in thermoplastic molding compositions based on poly-olefins, PVC, SAN or ABS is known.
BE-A 782 372 (Derwent abstract) relates to thermo-plastic compositions which are composed of a vinyl halide copolymer and from 0.1 to 4.0% by weight of a liquid acrylic homo- or copolymer. The acrylic copolymer serves as lubricant and improves the processibility of the vinyl halide copolymer.
CA-A 923645 relates to thermoplastic molding compositions which comprise a liquid alkyl acrylate homo- or copolymer to lower their viscosity.
Thermoplastic molding compositions which may be used are vinylaromatic homo- or copolymers, in particular ABS (acrylonitrile-butadiene-styrene) polymers, polymers or copolymers of vinyl chloride, or poly-carbonates. The hardness, impact strength and heat distortion temperature (HDT) of the thermoplastic molding compositions are not substantially affected by adding the liquid acrylate homopolymers or copolymers.
There is no hitherto known use of acrylate copolymers in molding compositions which are composed predominately of ASA graft rubber (acrylonitrile-styrene-acrylate) with SAN (styrene-acrylonitrile) copolymers and with an olefin polymer.
It is an object of the present invention, therefore, to provide thermoplastic molding compositions which may be used either as films or else as soft, reduced-gloss surface coatings for hard, brittle or impact-modified thermoplastics. These molding compositions are applied as coatings, for example by coextrusion, and for this have to have good flowability. However, in order not to be damaged during further processing, coating compositions of this type still have to have a high level of mechanical strength and heat resistance, in particular adequate for use in the automotive interior sector. A further object was to provide a process for preparing these thermoplastic molding compositions, and also the use of the molding compositions of the invention for producing moldings or films, or as coextrusion compositions. The films should have a balanced ratio of ultimate tensile strength, elongation at break, tear propagation resistance, hardness and colorfastness during processing, and also have reduced surface gloss and reduced susceptibility to electrostatic charging. In particular, tear propagation resistances to DIN 53515 of at least 35 N/mm should be achieved by the films, and the films should be aging-resistant and halogen-free with a leather-like appearance and comprise a lower level of volatile constituents than corresponding films of the prior art. Other objects are to provide films and moldings made from the molding compositions of the invention which have good and balanced mechanical properties, and the use of these.
We have found that this object is achieved, as are the other objects described, by way of thermoplastic molding compositions, essentially comprising
(A) from 20 to 99% by weight of at least one graft copolymer, essentially obtainable from
(a1) from 30 to 90% by weight of a core, obtainable by polymerizing a monomer mixture, essentially consisting of
(a11) from 80 to 99.99% by weight of at least one C
1
-C
10
-alkyl acrylate,
(a12) from 0.01 to 20% by weight of at least one copolymerizable, polyfunctional, cross-linking monomer, and
(a13) from 0 to 40% by weight, based on the total weight of components (a11) and (a12), of at least one other copolymerizable, mono-ethylenically unsaturated monomer, and
(a2) from 10 to 70% by weight of a graft shell, obtainable by polymerizing a monomer mixture in the presence of the core (a1), and essentially consisting of
(a21) from 50 to 100% by weight of at least one styrene compound of the formula (I)
where R
1
and R
2
, independently of one another, are hydrogen or C
1
-C
8
-alkyl and/or of a C
1
-C
8
-alkyl (meth)acrylate, and
(a22) from 0 to 50% by weight of at least one monofunctional comonomer, and
(B) from 1 to 80% by weight of a copolymer obtainable from at least one alpha-olefin and from at least one polar comonomer, with the proviso that the monomers used are not vinyl acetate or any vinylaromatic monomer, and
(C) from 0 to 80% by weight of a thermoplastic polymer, obtainable by polymerizing a monomer mixture, essentially consisting of
(c1) from 50 to 100% by weight of at least one vinylaromatic monomer and/or of a C
1
-C
8
-alkyl (meth)acrylate, and
(c2) from 0 to 50% by weight of at least one monofunctional comonomer, and
(D) from 0.1 to 20% by weight of a substantially uncrosslinked, low-molecular-weight polyalkyl acrylate with a molar mass of from 300 to 25 000 g/mol, where the overall total of components A to D is 100% by weight.
These molding compositions have excellent flowability and very good extrusion properties. They can be processed to give films or moldings with a soft, matt surface, at, consistent product quality. The molding compositions have a high level of mechanical strength and heat resistance. They are readily coextrudable. The molding compositions of the invention are particularly suitable for injection molding. Films and moldings made from these molding compositions have reduced surface gloss and reduced susceptibility to electrostatic charging. They are suitable for interior trim in motor vehicles, in the construction of houses, for the sanitary sector and for the furniture sector.
The molding compositions of the invention achieve the abovementioned combination of properties. The fundamental properties for film use are achieved here by mixing components (A) to (C), and the overall property profile for application in coextrusion is achieved by mixing components (A) to (D). Component (D) brings about not only t

Affiliated with

Also associated with

Rating

Thermoplastic molding materials does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Thermoplastic molding materials, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermoplastic molding materials will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3090186