Mat moulding materials

The invention relates to moulding materials which have a mat surface and are based on neutral and acid graft polymers.

The invention relates to moulding materials which have a mat surface and 
are based on neutral and acid graft polymers. 
Polymer blends with elastic-thermoplastic properties and a mat surface are 
of growing interest for fields of application in which high toughness and 
at the same time low gloss are required, thus, for example, for components 
for automobile interiors or for equipment coverings. 
Attempts have hitherto been made to prepare such polymer blends by using 
large particles of rubber (compare, for example, U.S. Pat. No. 4,169,869) 
or using rubbers which are not crosslinked or only slightly crosslinked 
(compare, for example, DE-OS (German Published Specification) No. 
2,057,936) as the graft base of the graft polymers. 
In all these attempts, however, the desired nature of the surface has been 
achieved with the loss of product qualities which are similarly desirable, 
such as, for example, notched impact strength, hardness or processability. 
The invention relates to mat moulding materials of 
(A) 99.95 to 0.05% by weight, preferably 70 to 30% by weight, of a graft 
product of a mixture of 40 to 100 parts by weight of styrene, 
.alpha.-methylstyrene, p-methylstyrene, vinyltoluene, methyl methacrylate 
or mixtures thereof and 60 to 0 parts by weight of acrylonitrile on a 
rubber in particle form with an average particle diameter (d.sub.50) of 
0.05 to 20.0 .mu.m and a glass transition temperature of 
.ltoreq.10.degree. C., with a total rubber content of 5 to 80% by weight 
and 
(B) 0.05 to 99.95% by weight, preferably 30 to 70% by weight, of a graft 
product of a mixture of 40 to 99.9 parts by weight of styrene, 
.alpha.-methylstyrene, p-methylstyrene, vinyltoluene, methyl methacrylate 
or mixtures thereof, 40 to 0.1 parts by weight of a monoacid or diacid 
containing a polymerisable double bond and 0 to 49 parts by weight of 
acrylonitrile on a rubber in particle form with an average particle 
diameter (d.sub.50) of 0.05 to 20.0 .mu.m and a glass transition 
temperature of .ltoreq.10.degree. C., with a total rubber content of 5 to 
80% by weight. 
Virtually all the rubbers with glass transition temperatures of 
.ltoreq.10.degree. C. are suitable as the graft base for graft products 
(A) and (B). Examples are polybutadiene, polyisoprene, styrene/butadiene 
copolymers, acrylonitrile/butadiene copolymers, acrylate rubbers, EPM 
rubbers (ethylene/propylene rubbers) and EPDM rubbers 
(ethylene/propylene/diene rubbers which contain a small amount of 
conjugated diene, such as, for example, hexa-1,5-diene or norbornadiene, 
as the diene). 
These rubbers must be in the form of particles with an average diameter 
(d.sub.50) of 0.05 to 20.0 .mu.m, preferably 0.1 to 2.0 .mu.m and 
particularly preferably 0.1 to 0.8 .mu.m. 
The graft products (A) and (B) are prepared in a manner which is known per 
se by grafting polymerisation in emulsion, suspension or solution or by a 
combination of these processes. 
They contain 5 to 80% by weight of rubber, in particular 20 to 60% by 
weight, and have gel contents, measured in acetone at 25.degree. C., of 30 
to 90% by weight, in particular 40 to 80% by weight. 
Suitable grafting monomers are, for example, styrene, 
.alpha.-methylstyrene, p-methylstyrene, vinyltoluene, acrylonitrile, 
methacrylonitrile, methyl methacrylate, vinyl acetate or mixtures thereof, 
in particular mixtures of acrylonitrile and styrene. 
Whilst the graft product (A) is prepared by polymerisation of these 
monomers in the presence of diene or acrylate rubbers, the graft product 
(B) is also prepared using the abovementioned monomers in the presence of 
the diene or acrylate rubbers, but a polymerisable monoacid or diacid, for 
example acrylic acid, methacrylic acid, maleic acid, fumaric acid, 
itaconic acid, crotonic acid, cinnamic acid, vinylsulphonic acid, 
vinylbenzenesulphonic acid or mixtures thereof, is required as a further 
monomer component, aliphatic C.sub.3 -C.sub.10 - or aromatic C.sub.9 
-C.sub.18 -mono- or di-carboxylic acids being preferred. 
The moulding materials according to the invention can be obtained by mixing 
their constituents (A) and (B) with one another at elevated temperatures, 
in particular at 100.degree. C. to 280.degree. C., for example in 
kneaders, on roll mills or in screw machines. 
If (A) and (B) are obtained as dispersions, suspensions or solutions, these 
can be mixed and worked up together. 
The customary amounts of the usual additives, such as antioxidants, 
anti-ageing agents, lubricants, flameproofing agents, fillers, pigments 
and antistatics, can be added to the moulding materials. 
The blends according to the invention are mat flexible thermoplastic 
moulding materials with good flow properties during processing by 
extrusion, calendering and injection-moulding. They can be processed to 
mat moulded articles, but are also suitable as modifiers for other 
plastics, in particular for thermoplastics, such as 
acrylonitrile/butadiene/styrene terpolymers (ABS), methyl 
methacrylate/butadiene/styrene terpolymers (MBS), styrene/acrylonitrile 
copolymers (SAN), .alpha.-methylstyrene/acrylonitrile copolymers, 
polystyrene, high impact polystyrene (HIPS), polymethyl methacrylate, 
polyvinyl chloride, polycarbonate, polycarbonate/ABS mixtures, 
polyphenylene oxide, polyphenylene oxide/HIPS mixtures, polyamides, for 
example polyamide 6 and polyamide 66, and polyesters, for example 
polyethylene terephthalate and polybutylene terephthalate. Those mixtures 
according to the invention which contain a large amount of rubber--for 
example 50 to 70% by weight--are preferably used as "matting modifiers". 
They are generally used in an amount of 5 to 40% by weight, based on the 
total modified product. 
A preferred mixture of this type consists of 10 to 80% by weight of the mat 
polymer blend according to the invention, and 90 to 20% by weight of a 
thermoplastic resin consisting of 5 to 40 parts by weight of styrene, 
.alpha.-methylstyrene, p-methylstyrene, methyl methacrylate or mixtures 
thereof and 0 to 70% by weight of an aromatic polycarbonate.

EXAMPLES AND COMISON EXAMPLES 
The following examples illustrate the invention. Parts are parts by weight 
and always relate to solid constituents or polymerisable constituents. 
PREATION OF THE GRAFT PRODUCTS 
G parts of rubber base (in the form of a Latex with a solids content of 
between 35 and 50% by weight) are warmed to 65.degree. C. in a reactor, 
after which 0.5 part of potassium persulphate (dissolved in 20 parts of 
water) is added. M parts of the monomer mixture stated in Table 1 and 2 
parts of the emulsifier given in Table 1 (dissolved in 25 parts of water) 
are then metered in over a period of 4 hours, during which the grafting 
reaction takes place. After an after-reaction time, the graft latex is 
coagulated in an aqueous magnesium sulphate/acetic acid solution, after 
addition of 1.2 parts of antioxidant. The resulting powder is washed with 
water and dried at 70.degree. C. in vacuo. 
TABLE 1 
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Composition and preparation conditions of the graft products 
Graft Average 
Graft 
product particle 
product 
type Rubber base 
size G Monomer M Emulsifier 
__________________________________________________________________________ 
1 A polybutadiene latex 
0.4 .mu.m 
50 
72 styrene 
50 
sodium salt of 
28 acrylonitrile 
disproportionated 
abietic acid 
2 A polybutadiene latex 
0.4 .mu.m 
80 
72 styrene 
20 
sodium salt of 
28 acrylonitrile 
disproportionated 
abietic acid 
3 A polybutyl acrylate 
0.5 .mu.m 
50 
72 styrene 
50 
sodium salt of 
latex 28 acrylonitrile 
disproportionated 
abietic acid 
4 B polybutadiene latex 
0.4 .mu.m 
50 
65 styrene 
50 
sodium salt of 
25 acrylonitrile 
C.sub.9-18 --alkyl- 
10 methacrylic 
sulphonic acids 
acid 
5 B polybutadiene latex 
0.4 .mu.m 
60 
55 styrene 
40 
sodium salt of 
15 acrylonitrile 
C.sub.9-18 --alkyl- 
10 methyl meth- 
sulphonic acids 
acrylate 
20 acrylic acid 
6 B polybutyl acrylate 
0.5 .mu.m 
50 
61 styrene 
50 
sodium salt of 
latex 24 acrylonitrile 
C.sub.9-18 --alkyl- 
15 methacrylic acid 
sulphonic acids 
7 B polybutadiene latex 
0.4 .mu.m 
65 
58 styrene 
35 
sodium salt of 
22 acrylonitrile 
C.sub.9-18 --alkyl- 
20 methacrylic acid 
sulphonic acids 
__________________________________________________________________________ 
PREATION AND TESTING OF THE MOULDING MATERIALS 
P parts of a mixture of graft product A and graft product B in the weight 
ratio stated in Table 2 are mixed with H parts of a thermoplastic resin 
and 3 parts of a lubricant in a kneader and the mixtures are then 
injection-moulded to standard test bars, a sheet (for evaluation of the 
surface) and a helix (for evaluation of the flow distance). Part of the 
material was processed to sheets by extrusion. The notched impact strength 
was measured at room temperature (a.sub.k.sup.RT) and at -40.degree. C. 
(a.sub.k.sup.-40.degree. C.) in accordance with DIN 53,453 (units: 
kJ/m.sup.2), the ball indentation hardness (H.sub.c) was measured in 
accordance with DIN 53,456 (units: N/mm.sup.2), the heat distortion point 
(Vicat B) was measured in accordance with DIN 53,460 (units: .degree.C.) 
and the flow distance was measured at 220.degree. C. on a helix about 8 mm 
wide and about 2 mm thick (units: cm). The gloss was measured in 
accordance with DIN 67,530 on a flat sheet at a reflection angle of 
60.degree. (reflectometer value) with the aid of a "Multi-Gloss" 
multiangle reflectometer from Byk-Mallinckrodt (see Table 2). 
The thermoplastic resins used are: styrene/acrylonitrile (SAN)=72.28 
copolymer with an M.sub.w of about 80,000 
.alpha.-methylstyrene/acrylonitrile (AMSAN)=69:31 copolymer with an 
M.sub.w of about 75,000, bisphenol A polycarbonate (PC) with an M.sub.w of 
about 30,000; all the resins have an (M.sub.w /M.sub.n)-1.ltoreq.2.0. 
TABLE 2 
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Composition and test data of the moulding materials 
Headings as follows: Test data 
Thermo- Reflecto- 
Appearance 
Moulding Graft 
Weight 
P plastic 
H Vicat 
Flow meter 
of the 
material product 
ratio 
parts 
resin parts 
a .sub.k.sup.RT 
a .sub.k.sup.-40.degree.C. 
H.sub.c 
B distance 
value 
extruded 
__________________________________________________________________________ 
sheet 
1 (Comparison) 
1 40 SAN 60 16 11 86 
97 41 78 glossy 
2 (Comparison) 
2 30 SAN 70 18.5 
12 79 
91 38 66 glossy 
3 (Comparison) 
3 40 SAN 60 15 5 85 
95 40 80 glossy 
4 (Comparison) 
4 40 SAN 60 12 7 87 
98 34 25 mat 
5 1 + 4 
1:1 40 SAN 60 14 9 88 
99 38 25 mat 
6 2 + 5 
2:1 30 SAN 70 14.5 
8 85 
96 38 19 mat 
7 3 + 6 
1:1 40 SAN 60 15 4.5 86 
96 39 27 mat 
8 1 + 7 
3:2 30 AMSAN 70 12.5 
6 90 
104 31 11 mat 
9 1 + 4 
1:1 35 AMSAN 65 13 6 89 
103 31 18 mat 
10 1 + 4 
1:1 35 PC/SAN = 
65 22 7.5 80 
110 23 25 mat 
2:1-mixture 
__________________________________________________________________________ 
As can be seen from Table 2, the incorporation of a graft product A by 
itself (moulding materials 1 to 3) into a thermoplastic matrix does not 
lead to a mat surface. Although a matted surface can be observed after 
mixing the graft product B by itself with the thermoplastic resin, a 
decrease in the notched impact strength and a reduced flowability at the 
same time occur (moulding material 4). Only when the mixtures according to 
the invention of graft product A and graft product B are used in a 
thermoplastic resin matrix (moulding materials 5 to 10) is a mat surface 
obtained, without an adverse influence on the other properties, on 
processing both by extrusion and by injection-moulding.