Thermoplastic moulding compounds

Details Thermoplastic moulding compounds Thermoplastic moulding compounds

1999-03-17

2001-05-22

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...

Reexamination Certificate

active

06235839

ABSTRACT:

The present invention relates to halogen-free thermoplastic molding compositions comprising
A) from 30 to 98% by weight of a graft polymer comprising
a
K
) from 30 to 90% by weight of an elastomeric graft core, obtainable by copolymerization of
a
K
/1) from 80 to 99.99% by weight of one or more C
1
-C
10
-alkyl acrylates,
a
K
/2)from 0.01 to 20% by weight of a monomer with crosslinking effect, and
a
K
/3)from 0 to 40% by weight of one or more other monoethylenically unsaturated monomers,
a
S
) from 10 to 70% by weight of a graft shell comprising
a
S
/1) from 50 to 100% by weight of a styrene compound of the formula
where R
1
and R
2
are hydrogen or C
1
-C
8
-alkyl,
or a C
1
-C
8
-alkyl acrylate or methacrylate,
or a mixture of the styrene compound and the C
1
-C
8
-alkyl acrylate or methacryate, and
a
S
/2)from 0 to 50% by weight of one or more other monoethylenically unsaturated monomers,
B) from 1 to 50% by weight of a thermoplastic polymer comprising
b1) from 50 to 100% by weight of styrene and/or &agr;-methylstyrene,
b2) from 0 to 50% by weight of acrylonitrile, and
b3) from 0 to 50% by weight of one or more other monomers,
and from 1 to 70% by weight of a component C, which
is an elastomeric block copolymer in which all or virtually all of the olefinic double bonds have been hydrogenated, comprising
at least two blocks A which contain, in their polymer chains, units of a vinylaromatic monomer, and have a glass transition temperature above 25° C.,
and, situated between the blocks A, at least one elastomeric block B/A
which contains, randomly in its polymer chain, units of both a vinylaromatic monomer (A) and a diene (B) and has a random structure and a glass transition temperature Tg below 25° C.,
where the proportion in the entire block copolymer of the hard phase formed from the blocks B/A is from 1 to 40 volume % and the proportion of the diene is less than 50% by weight.
The invention relates, furthermore, to molding compositions in which component C) has a specific formulation, to the use of these molding compositions for producing films and shaped articles and to films and shaped articles made from these molding compositions.
Plastic films have various areas of application. Certain films, in particular flexible films with a leather-like appearance, are extensively used in interior decoration, for example of automobiles, or as leather substitutes. They are mostly produced by calendering or extrusion.
The main constituent of these films is currently usually polyvinyl chloride (PVC), which contains plasticizer and frequently also contains other vinyl polymers. However, the films have only limited resistance to aging, and furthermore the plasticizer which is used can exude out over the course of time.
EP-A 526 813 discloses thermoplastic molding compositions made from a highly crosslinked acrylate rubber with a graft shell of methyl methacrylate or styrene-acrylonitrile, a partially crosslinked acrylate rubber, an ethylene-vinyl acetate copolymer and, if desired, a further polymer based on styrene and/or acrylic compounds. Under the conditions of shaping, to give films for example, these materials tend, however, to undergo undesirable degradation reactions.
DE-A 42 11 412 recommends as a material for films mixtures which are made from styrene-acrylonitrile polymers and thermoplastics and which have a graft shell of an elastomeric polymer. The preparation of graft copolymers of this type is, however, technically complicated, so that it is difficult to obtain consistent product quality.
In particular, films made from presently known molding compositions do not have fully satisfactory thermoforming properties; they also have a high Shore hardness, which does not always allow the desired soft, leather-like surface to be achieved.
It is an object of the present invention to provide thermoplastic molding compositions which are easy to prepare in consistent quality and which can be further processed into shaped articles, in particular into films, without loss of quality arising, for example, through degradation reactions. A further object is to provide molding compositions from which it is possible to produce shaped articles, in particular films, which are distinguished by good thermoforming properties (high elongation at break and high tear resistance) and by low Shore hardness.
We have found that this object is achieved by means of the thermoplastic molding compositions defined at the outset.
Furthermore, molding compositions comprising specific embodiments of component C) have been found. In addition, the use of the polymer mixtures for producing films and shaped articles, and films and shaped articles made from these materials, have been found.
Component A) is present in the novel compositions in an amount, based on the sum of components A), B) and C), of from 30 to 98, preferably from 40 to 90 and particularly preferably from 50 to 82% by weight. This component is a particulate graft copolymer built up from an elastomeric graft core a
K
) (“soft component”) and a shell a
S
) (“hard component”) grafted thereto.
The graft core a
K
) is present in a proportion of from 30 to 90, preferably from 40 to 80 and in particular from 50 to 75% by weight, based on component A).
The graft core a
K
) is obtained by polymerization of a monomer mixture of, based on a
K
),
a
K
/1) from 80 to 99.99, preferably from 85 to 99.5 and particularly preferably from 90 to 99% by weight of one or more C
1
-C
10
-alkyl acrylates,
a
K
/2) from 0.01 to 20, preferably from 0.5 to 10 and particularly preferably from 1 to 5% by weight of a monomer with crosslinking effect, and
a
K
/3) from 0 to 20, preferably from 0 to 5% by weight of one or more other monomers.
Useful alkyl acrylates a
K
/1) are especially those derived from ethanol, 2-ethylhexanol or in particular from n-butanol. One single alkyl acrylate or a mixture of a number of alkyl acrylates with different alkyl radicals may be used.
Monomers with crosslinking effect a
K
/2) are bi- or polyfunctional comonomers, for example butadiene, isoprene, divinyl esters of dicarboxylic acids, such as succinic acid and adipic acid, diallyl and divinyl ethers of dihydric alcohols, such as ethylene glycol and butane-1,4-diol, diesters of acrylic acid and methacrylic acid with the abovementioned dihydric alcohols, 1,4-divinylbenzene and triallyl cyanurate. Particular preference is given to the tricyclodecenyl acrylate of the formula below
which is known as dihydrodicyclopentadienyl acrylate, and to allyl acrylates and allyl methacrylates.
Component a
K
) in the molding compositions can also contain other monomers a
K
/3) which vary the mechanical and thermal properties of the core within a particular range, with reduction in the amounts of the monomers a
K
/1) and a
K
/2). The following may be mentioned as examples of such monoethylenically unsaturated comonomers a
K
/3):
vinylaromatic monomers, such as styrene and styrene derivatives of the formula I
where R
1
and R
2
are hydrogen or C
1
-C
8
-alkyl;
methacrylonitrile, acrylonitrile;
acrylic acid, methacrylic acid, dicarboxylic acids, such as maleic acid and fumaric acid, and their anhydrides, such as maleic anhydride;
nitrogen-functional monomers, such as dimethylaminoethyl acrylate, diethylaminoethyl acrylate, vinylimidazole, vinylpyrrolidone, vinylcaprolactam, vinylcarbazole, vinylaniline, acrylamide;
C
1
-C
4
-alkyl methacrylates, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate and hydroxyethyl acrylate;
aromatic and araliphatic esters of acrylic acid and of methacrylic acid, such as phenyl acrylate, phenyl methacrylate, benzyl acrylate, benzyl methacrylate, 2-phenylethyl acrylate, 2-phenylethyl methacrylate, 2-phenoxyethyl acrylate and 2-phenoxyethyl methacrylate;
unsaturated ethers, such as vinyl methyl ether and mixtures of these monomers.
The graft shell a
S
) is obtained by polymerization of a monomer mixture comprising, based on a
S
),
a
S
/1) from 50 to

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