U.S. patent application number 13/169381 was filed with the patent office on 2012-01-12 for stabilisierte acrylnitril/styrol/butadien formmassen.
This patent application is currently assigned to BASF SE. Invention is credited to Rolf Minkwitz.
Application Number | 20120010335 13/169381 |
Document ID | / |
Family ID | 45438026 |
Filed Date | 2012-01-12 |
United States Patent
Application |
20120010335 |
Kind Code |
A1 |
Minkwitz; Rolf |
January 12, 2012 |
STABILISIERTE ACRYLNITRIL/STYROL/BUTADIEN FORMMASSEN
Abstract
The invention relates to a thermoplastic molding composition
containing: from 3 to 94.6% by weight of one or more styrene
copolymers as component A from 5 to 95.2% by weight of one or more
impact-modifying graft rubbers having an olefinic double bond in
the rubber phase as component B from 0.2 to 0.9% by weight of a
compound of the formula (I) as component C: from 0 to 0.9% by
weight of a mixture of the formula (II) as component D: from 0 to
0.5% by weight of a compound of the formula (III) as component E:
or from 0 to 0.5% by weight of a compound of the formula (IV): or
from 0 to 0.5% by weight of a compound of the formula (V): or from
0 to 0.5% by weight of a compound of the formula (VI): from 0 to
10% by weight of one or more additives, where these differ from
components C, D, and E, as component F, and from 0 to 40% by weight
of fibrous or particulate fillers as component G, with the proviso
that if the amount of component D is 0% by weight the amount of
component E is from 0.01 to 0.5% by weight of one or more of the
compounds III, IV, V, or VI, where each of the % by weight values
is based on the sum weight of components A to G, and the sum of
these values does not exceed 100% by weight. The invention also
relates to a process to make the thermoplastic composition and the
use of the thermoplastic composition.
Inventors: |
Minkwitz; Rolf; (Dortmund,
DE) |
Assignee: |
BASF SE
Ludwigshafen
DE
|
Family ID: |
45438026 |
Appl. No.: |
13/169381 |
Filed: |
June 27, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61433537 |
Jan 18, 2011 |
|
|
|
Current U.S.
Class: |
524/100 ;
524/102 |
Current CPC
Class: |
C08K 5/16 20130101; C08K
5/315 20130101; C08K 5/34 20130101; C08K 5/16 20130101; C08K 5/34
20130101; C08L 25/12 20130101; C08L 25/08 20130101; C08L 25/12
20130101; C08K 5/315 20130101 |
Class at
Publication: |
524/100 ;
524/102 |
International
Class: |
C08L 55/02 20060101
C08L055/02; C08K 5/3492 20060101 C08K005/3492; C08L 51/04 20060101
C08L051/04; C08K 5/3435 20060101 C08K005/3435 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 12, 2010 |
EP |
10169243.2 |
Jul 12, 2010 |
EP |
10169245.7 |
Jul 12, 2010 |
EP |
10169250.7 |
Jul 12, 2010 |
EP |
10169257.2 |
Claims
1-13. (canceled)
14. A thermoplastic molding composition comprising: a) from 3 to
94.6% by weight of one or more styrene copolymers as component A b)
from 5 to 95.2% by weight of one or more impact-modifying graft
rubbers having an olefinic double bond in the rubber phase as
component B c) from 0.2 to 0.9% by weight of a compound of the
formula (I) as component C: ##STR00015## d) from 0 to 0.9% by
weight of a mixture of the formula (II) as component D:
##STR00016## e) from 0 to 0.5% by weight of a compound of the
formula (III) as component E: ##STR00017## or from 0 to 0.5% by
weight of a compound of the formula (IV): ##STR00018## or from 0 to
0.5% by weight of a compound of the formula (V): ##STR00019## or
from 0 to 0.5% by weight of a compound of the formula (VI):
##STR00020## f) from 0 to 10% by weight of one or more additives,
where these differ from components C, D, and E, as component F, and
g) from 0 to 40% by weight of fibrous or particulate fillers as
component G, with the proviso that if the amount of component D is
0% by weight the amount of component E is from 0.01 to 0.5% by
weight of one or more of the compounds III, IV, V, or VI, where
each of the % by weight values is based on the sum weight of
components A to G, and the sum of these values does not exceed 100%
by weight.
15. The thermoplastic molding composition according to claim 14,
wherein the proviso that if the amount of component D is 0% by
weight the amount of component E is from 0.1 to 0.5% by weight, of
one or more of the compounds III, IV, V, or VI, where each of the %
by weight values is based on the sum weight of components A to G,
and the sum of these values is 100% by weight.
16. The thermoplastic molding composition according to claim 14,
wherein the proviso that if the amount of component D is 0% by
weight the amount of component E is from 0.2 to 0.5% by weight, of
one or more of the compounds III, IV, V, or VI, where each of the %
by weight values is based on the sum weight of components A to G,
and the sum of these values is 100% by weight.
17. The thermoplastic molding composition according to claim 14,
wherein the swelling index of component B is from 5 to 20.
18. The thermoplastic molding composition according to claim 14,
wherein component A used comprises a copolymer made of
acrylonitrile, styrene, and/or .alpha.-methylstyrene,
phenylmaleimide, methyl methacrylate, or a mixture of these.
19. The thermoplastic molding composition according to claim 16,
wherein the swelling index of component B is from 5 to 20 and
component A used comprises a copolymer made of acrylonitrile,
styrene, and/or .alpha.-methylstyrene, phenylmaleimide, methyl
methacrylate, or a mixture of these.
20. The thermoplastic molding composition according to claim 14,
wherein component B used comprises a mixture made of an
acrylonitrile-butadiene-styrene (ABS) graft polymer which comprises
from 50 to 80% by weight, based on B, of an elastomerically
crosslinked butadiene polymer B1 and from 50 to 20% by weight,
based on B, of a graft shell B2 made of a vinylaromatic monomer and
made of one or more polar, copolymerizable, ethylenically
unsaturated monomers, and optionally made of a further
copolymerizable, ethylenically unsaturated monomer, in a ratio by
weight of from 85:15 to 75:25.
21. The thermoplastic molding composition according to claim 19,
wherein component B used comprises a mixture made of an
acrylonitrile-butadiene-styrene (ABS) graft polymer which comprises
from 50 to 80% by weight, based on B, of an elastomerically
crosslinked butadiene polymer B1 and from 50 to 20% by weight,
based on B, of a graft shell B2 made of a vinylaromatic monomer and
made of one or more polar, copolymerizable, ethylenically
unsaturated monomers, and optionally made of a further
copolymerizable, ethylenically unsaturated monomer, in a ratio by
weight of from 85:15 to 75:25.
22. The thermoplastic molding composition according to claim 14,
wherein the average particle diameter of component B is from 50 to
800 nm.
23. The thermoplastic molding composition according to claim 14,
which uses components C and D in a ratio by weight of from 3:1 to
1:1 and components D and E in a ratio by weight of from 2:1 to
0.5:1.
24. The thermoplastic molding composition according to claim 21,
which uses components C and D in a ratio by weight of from 3:1 to
1:1 and components D and E in a ratio by weight of from 2:1 to
0.5:1 and the average particle diameter of component B is from 50
to 800 nm.
25. The thermoplastic molding composition according to claim 14,
which uses styrene or .alpha.-methylstyrene as vinylaromatic
component in B2.
26. The thermoplastic molding composition according to claim 14,
which uses, as ethylenically unsaturated component in B2,
acrylonitrile and/or alkyl methacrylates and/or alkyl acrylates
having C.sub.1-C.sub.8-alkyl radicals.
27. The thermoplastic molding composition according to claim 14,
which uses component B in bimodal form.
28. A process for producing a thermoplastic molding composition
according claim 14, which comprises mixing components A to F with
one another at temperatures of from 100 to 300.degree. C. and at a
pressure of from 1 to 50 bar in any desired sequence, and then
kneading and extruding the material.
29. A process for producing a molding, a foil or a fiber which
comprises utilizing the thermoplastic molding composition according
to claim 14.
30. The process as claimed in claim 29, wherein a molding is
produced for motor-vehicle components or for parts of electronic
equipment.
31. A molding, fiber, or foil made of a thermoplastic molding
composition according to claim 14.
Description
[0001] The present invention relates to thermoplastic molding
compositions comprising styrene copolymers and comprising
impact-modifying graft rubbers having an olefinic double bond in
the rubber phase.
[0002] There is a very wide variety of known stabilized
thermoplastic molding compositions, and these have a wide range of
possible uses because their property profile, in particular their
good impact resistance, is advantageous for many applications.
[0003] U.S. Pat. No. 4,692,486 discloses stabilizer mixtures
comprising compounds of the formulae (I) and (III) of the present
application for polypropylene, polyurethane, and polystyrene, where
the amounts used of the individual stabilizer components are
smaller than or equal to 0.1% by weight.
[0004] DE-A-103 16 198 discloses stabilizer mixtures for a very
wide variety of thermoplastic polymers, an example highlighted
being polypropylene. The stabilizer mixtures are three-substance
mixtures. For each of the three components of said stabilizer
mixture, a large number of possible generic and specific compounds
are described. Just one of many possibilities described includes
stabilizer mixtures which also comprise compounds of the formulae
(VI), (VII), and (VIII) of the present application. The amount of
each of the three stabilizer components that can be present here is
preferably from 0.05 to 1% by weight, based on the organic
material. A disadvantage of this embodiment is the marked decrease
in multiaxial toughness during weathering.
[0005] It was therefore an object of the present invention to
provide improved molding compositions based on
acrylonitrile/butadiene/styrene molding compositions.
[0006] Novel and improved thermoplastic molding compositions have
accordingly been discovered, comprising: [0007] from 3 to 94.6% by
weight of one or more styrene copolymers as component A [0008] b)
from 5 to 95.2% by weight of one or more impact-modifying graft
rubbers having an olefinic double bond in the rubber phase as
component B [0009] c) from 0.2 to 0.9% by weight of a compound of
the formula (I) as component C:
[0009] ##STR00001## [0010] d) from 0 to 0.9% by weight of a mixture
of the formula (II) as component D:
[0010] ##STR00002## [0011] e) from 0 to 0.5% by weight of a
compound of the formula (III) as component E:
[0011] ##STR00003## [0012] or from 0 to 0.5% by weight of a
compound of the formula (IV):
[0012] ##STR00004## [0013] or from 0 to 0.5% by weight of a
compound of the formula (V):
[0013] ##STR00005## [0014] or from 0 to 0.5% by weight of a
compound of the formula (VI):
[0014] ##STR00006## [0015] f) from 0 to 10% by weight of one or
more additives, where these differ from components C, D, and E, as
component F, and [0016] g) from 0 to 40% by weight of fibrous or
particulate fillers as component G, with the proviso that if the
amount of component D is 0% by weight (i.e. no component D is
present), the amount of component E is from 0.01 to 0.5% by weight,
preferably from 0.1 to 0.5% by weight, particularly preferably from
0.2 to 0.5% by weight, of one of the compounds III, IV, V, or VI,
where each of the % by weight values is based on the sum weight of
components A to G, and the sum of these values is 100% by
weight.
[0017] Processes for producing said molding compositions have
moreover been invented, as also have the use thereof for producing
foils, moldings, or fibers, and said foils, moldings, or
fibers.
[0018] By virtue of the specific selection, essential to the
invention, of each individual component, and specific quantitative
proportions thereof, when the molding compositions of the invention
are compared with the known stabilized molding compositions they
exhibit a further improvement in weathering resistance, i.e. a
further improvement in resistance to heat, to light, and/or to
oxygen.
[0019] A description follows of the articles, processes, and uses
of the invention.
[0020] The molding compositions of the invention comprise, based on
the total weight of components A, B, C, D, E, F, and G, which is
100% by weight [0021] a) from 3 to 94.6% by weight, preferably from
10 to 75% by weight, particularly preferably from 20 to 70% by
weight of component A, [0022] b) from 5 to 95.2% by weight,
preferably from 10 to 50% by weight, particularly preferably from
15 to 40% by weight of component B, [0023] c) from 0.2 to 0.9% by
weight, preferably from 0.2 to 0.7% by weight, particularly
preferably from 0.3 to 0.6% by weight of component C, [0024] d)
from 0 to 0.9% by weight, preferably from 0.2 to 0.7% by weight,
particularly preferably from 0.2 to 0.4% by weight of component D,
with the proviso that if the amount of component D is 0% by weight
(i.e. no component D is present), the amount of component E is from
0.01 to 0.5% by weight, preferably from 0.1 to 0.5% by weight,
particularly preferably from 0.2 to 0.5% by weight, of one of the
compounds III, IV, V, or VI, [0025] e) from 0 to 0.5% by weight,
preferably from 0.1 to 0.5% by weight, particularly preferably from
0.2 to 0.4% by weight of component E [0026] f) from 0 to 10% by
weight, preferably from 0 to 8% by weight, particularly preferably
from 0 to 5% by weight of component F, and [0027] g) from 0 to 40%
by weight, preferably from 0 to 25% by weight, particularly
preferably from 0 to 15% by weight of component G.
[0028] The ratio by weight of component C to component D is
generally in the range from 4:1 to 0.25:1, preferably from 4:1 to
1:1, particularly preferably from 3:1 to 1:1.
[0029] The ratio by weight of component D to E is generally in the
range from 2:1 to 0.5:1.
Component A:
[0030] The thermoplastic molding compositions of the invention
comprise one or more styrene copolymers as component A. Any desired
suitable comonomers can be present alongside styrene here in the
copolymers. Preference is given to a styrene-acrylonitrile
copolymer, alpha-methylstyrene-acrylonitrile copolymer, or
N-phenylmaleimide-acrylonitrile copolymer.
[0031] A suitable component A is in principle any of the following
that are known to the person skilled in the art and described in
the literature: styrene-acrylonitrile copolymers,
.alpha.-methylstyrene-acrylonitrile copolymers,
N-phenylmaleimide-acrylonitrile copolymer, or a mixture of these,
as long as the intrinsic viscosity IV of a mixture of these is less
than or equal to 85 ml/g (measured to DIN 53727 at 25.degree. C. on
a 0.5% strength by weight solution in dimethylformamide; this
measurement method also applies to all of the intrinsic viscosities
IV mentioned hereinafter).
[0032] Preferred components A are composed of from 50 to 90% by
weight, preferably from 60 to 80% by weight, in particular from 65
to 78% by weight, of styrene, and from 10 to 50% by weight,
preferably from 20 to 40% by weight, in particular from 22 to 35%
by weight, of acrylonitrile, and also from 0 to 5% by weight,
preferably from 0 to 4% by weight, in particular from 0 to 3% by
weight, of further monomers, where each of the % by weight values
is based on the weight of component A, and the sum of these is 100%
by weight.
[0033] Further preferred components A are composed of from 50 to
90% by weight, preferably from 60 to 80% by weight, in particular
from 65 to 78% by weight, of .alpha.-methylstyrene, and from 10 to
50% by weight, preferably from 20 to 40% by weight, in particular
from 22 to 35% by weight, of acrylonitrile, and also from 0 to 5%
by weight, preferably from 0 to 4% by weight, in particular from 0
to 3% by weight, of further monomers, where each of the % by weight
values is based on the weight of component A, and the sum of these
is 100% by weight.
[0034] Components A to which preference is likewise given are
composed of 50 to 90% by weight, preferably from 60 to 80% by
weight, in particular from 65 to 78% by weight, of
N-phenylmaleimide, and from 10 to 50% by weight, preferably from 20
to 40% by weight, in particular from 22 to 35% by weight, of
acrylonitrile, and also from 0 to 5% by weight, preferably from 0
to 4% by weight, in particular from 0 to 3% by weight, of further
monomers, where each of the % by weight values is based on the
weight of component A, and the sum of these is 100% by weight.
[0035] Components A to which preference is likewise given are
mixtures of said styrene-acrylonitrile copolymers,
.alpha.-methylstyrene-acrylonitrile copolymers, and
N-phenylmaleimide-acrylonitrile copolymers.
[0036] The abovementioned further monomers that can be used are any
of the copolymerizable monomers, examples being p-methylstyrene,
tert-butylstyrene, vinylnaphthalene, alkyl acrylates, and/or alkyl
methacrylates, for example those having C.sub.1-C.sub.8-alkyl
radicals, N-phenylmaleimide, or a mixture of these.
[0037] The copolymers of component A can be produced by known
methods. By way of example, they can be produced via free-radical
polymerization, in particular via emulsion, suspension, solution,
or bulk polymerization.
Component B:
[0038] Component B is preferably composed of one or more
impact-modifying graft rubbers having an olefinic double bond in
the rubber phase. Component B is a graft copolymer with bimodal
particle size distribution, and the proportion thereof in the
molding compositions of the invention is from 5 to 80% by weight,
preferably from 10 to 70% by weight, and particularly preferably
from 15 to 60% by weight, based on the entirety of components A, B,
C, D, and/or E, and also, if present, F and G. The graft polymer B
is composed of a "soft" elastomeric, particulate graft base b1, and
of a "hard" graft b2. The swelling index of component B is
generally from 5 to 20, preferably from 6 to 15, and particularly
preferably from 7 to 13.
[0039] The proportion of the graft base b1 comprised is from 40 to
90% by weight, preferably from 45 to 85% by weight, and
particularly preferably from 50 to 80% by weight, based on
component B. The graft base b1 is obtained via polymerization of,
based on b1, from 70 to 100% by weight, preferably from 75 to 100%
by weight, and particularly preferably from 80 to 100% by weight,
of at least one conjugated diene b11, and from 0 to 30% by weight,
preferably from 0 to 25% by weight, and particularly preferably
from 0 to 10% by weight, of at least one further monoethylenically
unsaturated monomer. Conjugated dienes b11 that can be used are
butadiene, isoprene, chloroprene, and mixtures thereof. It is
preferable to use butadiene or isoprene or a mixture thereof, and
butadiene is very particularly preferably used.
[0040] Constituent b1 of the molding compositions can moreover
comprise, with concomitant reduction in the amount of the monomers
b11, further monomers b12 which vary the mechanical and thermal
properties of the core within a certain range. Examples that may be
mentioned of these monoethylenically unsaturated comonomers are:
styrene, alpha-methylstyrene, acrylonitrile, maleic anhydride,
acrylic acid, methacrylic acid, maleic acid, and fumaric acid.
[0041] It is preferable to use styrene, .alpha.-methylstyrene,
n-butyl acrylate, or a mixture of these as monomers b12, and it is
particularly preferable to use styrene and n-butyl acrylate or a
mixture of these, and it is very particularly preferable to use
styrene. The amounts used of styrene or n-butyl acrylate, or a
mixture of these, are in particular up to 20% by weight in total,
based on b1.
[0042] One particular embodiment uses a graft base made of, based
on b1:
b11 from 70 to 99.9% by weight, preferably from 90 to 99% by
weight, of butadiene, and b12 from 0.1 to 30% by weight, preferably
from 1 to 10% by weight, of styrene.
[0043] The proportion comprised of the graft b2 is from 10 to 60%
by weight, preferably from 15 to 55% by weight, and particularly
preferably from 20 to 50% by weight, based on component B.
[0044] The graft b2 is obtained via polymerization of, based on
b2:
b21 from 65 to 95% by weight, preferably from 70 to 90% by weight,
and particularly preferably from 72 to 85% by weight, of at least
one vinylaromatic monomer, b22 from 5 to 35% by weight, preferably
from 10 to 30% by weight, and particularly preferably from 15 to
28% by weight, of acrylonitrile, and b23 from 0 to 30% by weight,
preferably from 0 to 20% by weight, and particularly preferably
from 0 to 15% by weight, of at least one other monoethylenically
unsaturated monomer.
[0045] Styrene and/or alpha-methylstyrene can be used as
vinylaromatic monomers. The monomers mentioned at an earlier stage
above for component b12 can be used as other monomers b23. Methyl
methacrylate and acrylates, such as n-butyl acrylate, are
particularly suitable. Methyl methacrylate MMA is very particularly
suitable as monomer b23, and preference is given here to an amount
of up to 20% by weight of MMA, based on b2.
[0046] The graft polymers are produced by the emulsion
polymerization process. It is usual to polymerize at from 20 to
100.degree. C., but preferably from 30 to 90.degree. C.
Conventional emulsifiers are usually used concomitantly, examples
being the alkali metal salts of alkylsulfonic acids or of
alkylarylsulfonic acids, other examples being alkyl sulfates, fatty
alcohol sulfonates, and salts of higher fatty acids having from 10
to 30 carbon atoms, and other examples are sulfosuccinates, ether
sulfonates, and resin soaps. Preference is given to use of the
alkali metal salts, in particular the Na salts and K salts, of
alkylsulfonates or fatty acids having from 10 to 18 carbon
atoms.
[0047] The amounts generally used of the emulsifiers are from 0.5
to 5% by weight, in particular from 0.5 to 3% by weight, based on
the monomers used in producing the graft base b1.
[0048] In producing the dispersion it is preferable to use an
amount of water such that the solids content of the finished
dispersion is from 20 to 50% by weight. Operations are usually
carried out with a water/monomer ratio of from 2:1 to 0.7:1.
[0049] Suitable free-radical generators for initiating the
polymerization reaction are any of those which decompose at the
selected reaction temperature, i.e. either those which decompose
solely thermally or those which decompose in the presence of a
redox system. Preferred polymerization initiators that can be used
are free-radical generators such as peroxides, a preferred example
being peroxosulfates (e.g. sodium persulfate or potassium
persulfate), and azo compounds, such as azodiisobutyronitrile.
However, it is also possible to use redox systems, in particular
those based on hydroperoxides, such as cumene hydroperoxide.
[0050] The amount generally used of the polymerization initiators
is from 0.1 to 1% by weight, based on the graft base monomers b11
and b12.
[0051] The free-radical generators, and also the emulsifiers, are
added to the reaction mixture by way of example batchwise, by
adding the total amount at the start of the reaction, or are added
batchwise after division into a plurality of portions, at the start
and at one or more subsequent junctures, or are added continuously
during a certain time interval. The continuous addition process can
also follow a gradient, which can by way of example be upward- or
downward-inclined, linear, or exponential, or else can be a staged
gradient (step function).
[0052] Molecular-weight regulators can moreover be used
concomitantly, examples being ethylhexyl thioglycolate, n- or
tert-dodecyl mercaptan, and other mercaptans, terpinols, and
dimeric .alpha.-methylstyrene, or other compounds suitable as
molecular-weight regulators. The molecular-weight regulators are
added to the reaction mixture batchwise or continuously, as has
been described above for the free-radical generators and
emulsifiers.
[0053] In order to maintain constant pH, which is preferably from 6
to 9, buffer substances can be used concomitantly, an example being
Na2HPO4/NaH2PO4, sodium hydrogencarbonate, or buffers based on
citric acid/citrate. The amounts used of regulators and buffer
substances are conventional, and there is therefore no need for
further information in this respect.
[0054] In one particular preferred embodiment, a reducing agent is
added during the grafting of the graft base b1 with the monomers
b21 to b23.
[0055] In one particular embodiment, the graft base can also be
produced via polymerization of the monomers b1 in the presence of a
fine-particle latex, this being known as the seed latex
polymerization procedure. This latex is used as initial charge and
can be composed of monomers that form elastomeric polymers, or else
of the other monomers mentioned above. Suitable seed latices are
composed by way of example of polybutadiene or polystyrene.
[0056] In another preferred embodiment, the graft base IA can be
produced by what is known as the feed process. In this process, a
certain proportion of the monomers b1 is used as initial charge,
and the polymerization reaction is initiated, and then the
remainder of the monomers ("feed") a1) is added as feed during the
polymerization reaction. The parameters for the feed (shape of
gradient, amount, duration, etc.) depend on the other
polymerization conditions. The principles of the statements made in
relation to the mode of addition of the free-radical initiator or
of the emulsifier are again applicable here. The proportion of the
monomers b1 preferably used as initial charge in the feed process
is from 5 to 50% by weight, particularly preferably from 8 to 40%
by weight, based on loll. It is preferable that the feed of a1) is
added within a period of from 1 to 18 hours, in particular from 2
to 16 hours, very particularly from 4 to 12 hours.
[0057] Graft polymers having a plurality of "soft" and "hard"
shells are moreover also suitable, for example those having the
structure b1-b2-b1-b2, or b2-b1-b2, especially in the case of
relatively large particles.
[0058] The precise polymerization conditions, in particular the
nature of and amount of, and the metering procedure for, the
emulsifier, and the other polymerization auxiliaries, are
preferably selected in such a way that the average particle size of
the resultant latex of the graft polymer B, defined via the d50
value of the particle size distribution, is from 80 to 800,
preferably from 80 to 600, and particularly preferably from 85 to
400, measured with the aid of HDC (W. Wohlleben and H. Schuch in
Measurement of Particle Size Distribution of Polymer Latexes, 2010,
Editors: Luis M. Gugliotta and Jorge R. Vega, p. 130-153).
[0059] The reaction conditions are balanced in such a way that the
polymer particles of B have bimodal particle size distribution,
i.e. a size distribution with two relatively pronounced maxima. The
first maximum is more pronounced (comparatively narrow peak) than
the second, and is generally at from 25 to 200 nm, preferably from
60 to 170 nm, particularly preferably from 70 to 150 nm. The second
maximum is generally at from 150 to 800 nm, preferably from 180 to
700 nm, particularly preferably from 200 to 600 nm. The second
maximum here (from 150 to 800 nm) is at particle sizes larger than
those of the first maximum (from 25 to 200 nm).
[0060] The bimodal particle size distribution is preferably
achieved via (partial) agglomeration of the polymer particles. An
example of a procedure for achieving this is as follows: the
monomers b1 which form the core are polymerized to a conversion
which is usually at least 90%, preferably greater than 95%, based
on the monomers used. This conversion has generally been achieved
after from 4 to 20 hours. The average particle size d50 of the
resultant rubber latex is at most 200 nm and it has a narrow
particle size distribution (almost monodisperse system).
[0061] In the second stage, the rubber latex is agglomerated. This
is generally achieved via addition of a dispersion of an acrylate
polymer. It is preferable to use dispersions of copolymers of
(C1-C4-alkyl)acrylates, preferably of ethyl acrylate, with from 0.1
to 10% by weight of monomers forming polar polymers, e.g. acrylic
acid, methacrylic acid, acrylamide, or methacrylamide,
N-methylolmethacrylamide or N-vinylpyrrolidone. Preference is given
to a composition made of from 80 to 98% of ethyl acrylate and from
2 to 20% of methacrylamide, and particular preference is given to a
composition made of from 90 to 98% of ethyl acrylate and from 2 to
10% of methacrylamide. The agglomeration dispersion can also
optionally comprise a plurality of the acrylate polymers
mentioned.
[0062] The concentration of the acrylate polymers in the dispersion
used for agglomeration is in general to be from 3 to 40% by weight.
The agglomeration process uses from 0.2 to 20 parts by weight,
preferably from 1 to 5 parts by weight, of the agglomeration
dispersion for every 100 parts of the rubber latex, the calculation
in each case being based on solids. The agglomeration process is
carried out via addition of the agglomeration dispersion to the
rubber. The rate of addition is normally not critical, and the
addition generally takes from about 1 to 30 minutes at a
temperature of from 20 to 90.degree. C., preferably from 30 to
75.degree. C.
[0063] The rubber latex can also be agglomerated via other
agglomeration agents, e.g. acetic anhydride, as well as by means of
an acrylate polymer dispersion. Agglomeration via pressure or
freezing is also possible (pressure agglomeration or freeze
agglomeration). The methods mentioned are known to the person
skilled in the art.
[0064] Under the conditions mentioned, only a portion of the rubber
particles is agglomerated, and the distribution produced is
therefore bimodal. After the agglomeration process here, the
proportion of the particles present in the non-agglomerated state
(numeric distribution) is generally more than 50%, preferably from
75 to 95%. The resultant partially agglomerated rubber latex is
relatively stable, and can therefore be readily stored and
transported without coagulation.
[0065] In order to achieve bimodal particle size distribution in
the graft polymer B, it is also possible to produce, separately
from one another and in a usual manner, two different graft
polymers B' and B'' which differ in their average particle size,
and to combine the graft polymers B' and B'' in the desired
quantitative proportion.
[0066] The polymerization of the graft base b1 is usually conducted
in such a way, via selection of the reaction conditions, as to give
a graft base with a particular condition of crosslinking. Examples
that may be mentioned of parameters essential for this purpose are
the reaction temperature and reaction time, the ratio of monomers,
regulator, free-radical initiator and, for example in the case of
the feed process, the feed rate and the amount, and the juncture of
addition, of regulator and initiator.
[0067] A method for characterizing the condition of crosslinking of
crosslinked polymer particles is measurement of the swelling index
SI, which is a measure of the solvent-swellability of a polymer
having some degree of crosslinking. An example of conventional
swelling agents is methyl ethyl ketone or toluene. The SI of the
ungrafted molding compositions b1 of the invention is usually in
the range SI=from 10 to 60, preferably from 15 to 55, and
particularly preferably from 20 to 50, in toluene.
[0068] Another method of characterizing the condition of
crosslinking is measurement of NMR relaxation times for the labile
protons, these being known as T2 times. As the degree of
crosslinking of a particular network increases, its T2 times
decrease. Usual T2 times for the graft bases b1 of the invention
are average T2 times in the range from 2.0 to 4.5 ms, preferably
from 2.5 to 4.0 ms, and particular preferably from 2.5 to 3.8 ms,
measured on filmed specimens at 80.degree. C.
[0069] Another measure for characterizing the graft base and its
condition of crosslinking is gel content, i.e. the proportion of
the product which has been crosslinked and is therefore insoluble
in a particular solvent. The solvent used for determination of gel
content is usefully the same as that used for determination of the
swelling index. Usual gel contents of the graft bases b1 of the
invention are in the range from 50 to 90%, preferably from 55 to
85%, and particularly preferably from 60 to 80%.
[0070] The swelling index is determined by way of example by the
following method: about 0.2 g of the solid of a graft base
dispersion filmed via evaporation of the water is swollen in a
sufficient amount (e.g. 50 g) of toluene. After, for example, 24 h
the toluene is removed under suction and the specimen is weighed.
The specimen is dried in vacuo and again weighed. The swelling
index is the ratio of the outgoing weight after the swelling
procedure to the outgoing dry weight after the further drying
process. The gel content is calculated correspondingly from the
ratio of dry outgoing weight after the swelling step to the ingoing
weight prior to the swelling step (.times.100%).
[0071] The T2 time is determined via measurement of NMR relaxation
of a specimen of the graft base dispersion which has been filmed
after removal of water. For this, by way of example, the specimen
is dried in air overnight and at, for example, 60.degree. C. dried
in vacuo for 3 h and then subjected to measurement using suitable
measuring equipment, e.g. minispec equipment from Bruker, at
80.degree. C. The relaxation process is markedly
temperature-dependent, and comparison can therefore be made only
between specimens subjected to measurement by the same method.
[0072] The conditions used to produce the graft b2 can be the same
as those used to produce the graft base b1, and the graft b2 can be
produced here in one or more steps of a process. By way of example,
for two-stage grafting, styrene and, respectively,
.alpha.-methylstyrene can first be polymerized alone, and then
styrene and acrylonitrile can be polymerized, in two successive
steps. This two-stage grafting process (first styrene, then
styrene/acrylonitrile) is a preferred embodiment. Further details
concerning production of the graft polymers B are described in
DE-OS 12 60 135 and 31 49 358.
[0073] It is advantageous in turn to carry out the graft
polymerization onto the graft base b1 in aqueous emulsion. The
system used for this process can be the same as that used for the
polymerization of the graft base, and further emulsifier and
initiator can be added here. These do not have to be identical with
the emulsifiers and initiators used for producing the graft base
a1). By way of example, therefore, it can be advantageous to use a
persulfate as initiator for producing the graft base b1 but to use
a redox initiator system for polymerizing the graft shell b2. In
other respects', the statements made in relation to the production
of the graft base b1 apply to the selection of emulsifier,
initiator, and polymerization auxiliaries. The monomer mixture to
be grafted onto the material can be added to the reaction mixture
all at once, batchwise in a plurality of stages, or preferably
continuously during the polymerization reaction.
[0074] To the extent that ungrafted polymers are produced from the
monomers b2 during the grafting of the graft base b1, the amounts
are counted with the mass of component B, and are generally less
than 10% by weight of b2.
[0075] The graft copolymers B of the invention can be used as they
stand, as they are produced in the reaction mixture, for example in
the form of latex emulsion or of latex dispersion. However, as an
alternative, which is preferable for most applications, they can
also be worked up in a further step. Methods of work-up are known
to the person skilled in the art. One example of these is isolation
of the graft copolymers B from the reaction mixture, e.g. via spray
drying or shear, or via precipitation using strong acids, or by
means of nucleating agents, such as inorganic compounds, e.g.
magnesium sulfate. The graft copolymers B present in the reaction
mixture can also be worked up by dewatering them completely or
partially. Another possibility is to undertake the work-up by means
of a combination of the methods mentioned.
[0076] The SI of the graft polymers is usually in the range SI=from
5 to 20, preferably from 6 to 15, and particularly preferably from
7 to 13.
[0077] Components A and B can be mixed in any desired manner by any
of the known methods to produce the molding composition. If, by way
of example, these components have been produced via emulsion
polymerization, the resultant polymer dispersions can be mixed with
one another, and then the polymers can be precipitated together,
and the polymer mixture can be worked up. However, the blending of
these components preferably takes place via extrusion, kneading, or
rolling of the components together, where the components have been
previously isolated, if necessary, from the aqueous dispersion or
solution obtained during the polymerization reaction. The
graft-copolymerization products B obtained in aqueous dispersion
can also be dewatered only partially and mixed in the form of moist
crumb with the hard matrix A, whereupon full drying of the graft
copolymers B then takes place during the mixing process.
Component C:
[0078] A compound of the formula (I) is used as component C of the
molding compositions of the invention:
##STR00007##
[0079] This sterically hindered amine (CAS number 52829-07-9) and
production thereof are known to the person skilled in the art and
are described in the literature (see by way of example U.S. Pat.
No. 4,396,769 and the references cited therein). It is marketed as
Tinuvin.RTM. 770 by BASF SE.
Component D:
[0080] A compound of the formula (II) is used as component D of the
molding compositions of the invention:
##STR00008##
[0081] This sterically hindered amine (CAS number 167078-06-0) and
production thereof are known to the person skilled in the art and
described in the literature (Carlsson et al., Can. Journal of
Polymer Science, Polymer Chemistry Edition (1982), 20(2), 575-82).
It is marketed as Cyasorb.RTM. 3853 by Cytec Industries.
Component E:
[0082] A compound of the formula (III) can be used as component E
of the molding compositions of the invention:
##STR00009##
[0083] This sterically hindered amine (CAS number 71878-19-8) and
production thereof are known to the person skilled in the art and
are described in the literature (see by way of example EP-A-93 693
and the references cited therein). It is marketed as
Chimassorb.RTM. 944 by BASF SE.
[0084] A compound of the formula (IV) can be used as further
component E of the molding compositions of the invention:
##STR00010##
[0085] This sterically hindered amine (CAS number 101357-37-3) and
production thereof are known to the person skilled in the art and
are described in the literature (see by way of example U.S. Pat.
No. 5,208,132 and the references cited therein). It is marketed as
Adeka Stab.RTM. LA-68 by ADEKA.
[0086] A compound of the formula (V) can be used as further
component E of the molding compositions of the invention:
##STR00011##
[0087] This sterically hindered amine (CAS number 82451-48-7) and
production thereof are known to the person skilled in the art and
are described in the literature (see by way of example U.S. Pat.
No. 4,331,586 and the references cited therein). It is marketed as
Cyasorb.RTM. UV-3346 by Cytec Industries.
[0088] A compound of the formula (VI) can be used as further
component E of the molding compositions of the invention:
##STR00012##
[0089] This sterically hindered amine (CAS number 192268-64-7) and
production thereof are known to the person skilled in the art and
are described in the literature (see by way of example EP-A-782 994
and the references cited therein). It is marketed as
Chimassorb.RTM. 2020 by BASF.
Component F:
[0090] The molding compositions of the invention can comprise,
alongside components A, B, C, D, and E, one or more additives which
are typical for, and commonly used in, plastics mixtures, and which
differ from components C, D, and E.
[0091] Examples that may be mentioned of these additives are dyes,
pigments, colorants, antistatic agents, antioxidants, stabilizers
for improving thermal stability, for increasing lightfastness, and
for raising hydrolysis resistance and chemicals resistance, agents
to counteract decomposition by heat, and in particular the
lubricants which are advantageous for producing moldings. These
further additives can be metered into the material at any stage of
the production process, but preferably at an early juncture, in
order to utilize the stabilizing effects (or other specific
effects) of the additive at an early juncture. Heat stabilizers or
oxidation retarders are usually metal halides (chlorides, bromides,
iodides) deriving from metals of group I of the Periodic Table of
the Elements (e.g. Li, Na, K, Cu).
[0092] Stabilizers suitable as component E are the conventional
hindered phenols, and also "vitamin E" and compounds of analogous
structure. Other suitable compounds are benzophenones, resorcinols,
salicylates, benzotriazoles, and others. The amounts of these
usually used (based on the total weight of the molding compositions
of the invention) are usually from 0 to 2% by weight, preferably
from 0.01 to 2% by weight.
[0093] Suitable lubricants and mold-release agents are stearic
acids, stearyl alcohol, stearic esters, and generally higher fatty
acids, derivatives of these, and corresponding fatty acid mixtures
having from 12 to 30 carbon atoms. The amounts of said
additions--insofar as they are present--are in the range from 0.05
to 1% by weight (based on the total weight of the molding
compositions of the invention).
[0094] Other additives that can be used are silicone oils,
oligomeric isobutylene, or similar substances, and the conventional
amounts--if these are present--are from 0.05 to 5% by weight (based
on the total weight of the molding compositions of the invention).
It is equally possible to use pigments, dyes, optical brighteners,
such as ultramarine blue, phthalocyanines, titanium dioxide,
cadmium sulfides, and derivatives of perylenetetracarboxylic
acid.
[0095] The amounts usually used of processing aids and stabilizers,
lubricants, and antistatic agents are from 0 to 4% by weight,
preferably from 0.01 to 4% by weight (based on the total weight of
the molding compositions of the invention).
Component G:
[0096] The molding compositions of the invention comprise, as
component G, fibrous or particulate fillers which differ from
components C, D, E, and F, or a mixture of these fillers. These are
preferably commercially available products, for example carbon
fibers and glass fibers. Glass fibers that can be used can be those
made of E, A, or C glass, and have preferably been equipped with a
size and with an adhesion promoter. Their diameter is generally
from 6 to 20 .mu.m. It is possible to use either
continuous-filament fibers or chopped glass fibers (staple) or
rovings with length from 1 to 10 mm, preferably from 3 to 6 mm.
[0097] It is also possible to add fillers or reinforcing materials
such as glass beads, mineral fibers, whiskers, aluminum oxide
fibers, mica, powdered quartz, and wollastonite.
[0098] The molding compositions of the invention can comprise
further polymers alongside components A, B, C, D and optionally E
and F.
[0099] The molding compositions of the invention can be produced
from the components in any desired manner by any of the known
methods. However, it is preferable that the components are blended
by mixing in the melt, for example by extruding, kneading or
rolling of the components together, e.g. at temperatures in the
range from 160 to 400.degree. C., preferably from 180 to
280.degree. C., and in one preferred embodiment here the components
have been to some extent or completely isolated in advance from the
reaction mixtures obtained during the respective steps of
production. By way of example, the graft copolymers B can be mixed
in the form of moist crumb with granules of the vinylaromatic
copolymer A, whereupon the full drying to give the graft copolymers
described then takes place during the mixing process. The
components can be introduced in respectively pure form into
suitable mixing apparatuses, in particular extruders, preferably
twin-screw extruders. However, it is also possible to begin by
premixing individual components, for example A and B, and then to
mix these with further components A or B or with other components,
e.g. C and D. Component A here can be used in the form of component
separately produced previously; however it is also possible to add
the acrylate rubber and the vinylaromatic copolymer independently
of one another. In one embodiment, a concentrate is first produced,
for example, from components B and C in component A (these being
known as additive batches or masterbatches), and is then mixed with
the desired amounts of the remaining components. The molding
compositions can be processed by processes known to the person
skilled in the art by way of example to give granules, or else
directly to give, for example, moldings.
[0100] The molding compositions of the invention can be processed
to give foils, moldings or fibers. Said foils, moldings or fibers
are particularly suitable for use outdoors, i.e. with exposure to
weathering.
[0101] Said foils, moldings or fibers can be produced from the
molding compositions of the invention by the known methods of
thermoplastic processing. In particular, the production method used
can be thermoforming, extrusion, injection molding, calendering,
blow molding, compression molding, pressure sintering or any other
type of sintering, preferably injection molding.
[0102] When the molding compositions of the invention are compared
with the known stabilized molding compositions, they exhibit a
further improvement in weathering resistance, i.e. a further
improvement in resistance to heat, to light, and/or to oxygen.
[0103] The examples below provide further explanation of the
invention.
EXAMPLES
Test Methods:
[0104] To give a measure of weathering resistance, Xenotest
weathering was carried out to ISO 4892/2, Method A, external, on
test specimens (60.times.60.times.2 mm, produced to ISO 294 in a
mold family at a melt temperature of 260.degree. C. and at a mold
temperature of 60.degree. C.). The surface gloss of all of the
specimens was measured to DIN 67530 at an observation angle of
60.degree. after the weathering times specified in Table 1.
[0105] Another measure of weathering resistance was the change
within the color space .DELTA.E to DIN 52 336 calculated from
.DELTA.L, .DELTA.A, and .DELTA.B to DIN 6174.
Starting Materials
[0106] Components or products with prefix "comp-" are not of the
invention and serve for comparison.
[0107] Components A and B (and comp-A for comparison) used were:
[0108] AB-i: a butadiene-rubber-modified styrene-acrylonitrile
copolymer (ABS) with swelling index 9 in toluene for A6 on
repetition of example 11 from DE 197 28 629 A1. Instead of
component B1, a styrene-acrylonitrile copolymer with intrinsic
viscosity 81 and molecular weight 141 000, measured with the aid of
SEC-MALLS, (Chi-san Wu, Handbook of size exclusion chromatography
and related techniques, page 19) was used. [0109] comp-AB-ii: a
butadiene-rubber-modified styrene-acrylonitrile copolymer (ABS)
with a swelling index of 23.1 in toluene in modification of example
11 of DE 197 28 629 A1, prepared using 40% more tert-dodecyl
mercaptan in K4. Instead of component B1, a styrene-acrylonitrile
copolymer with intrinsic viscosity 81 and molecular weight 141 000,
measured with the aid of SEC-MALLS, (Chi-san Wu, Handbook of size
exclusion chromatography and related techniques, page 19) was used.
[0110] comp-AB-iii: a polystyrene marketed by BASF SE as
polystyrene 158K.
[0111] Component C (and comp-C for comparison) used was: [0112]
C-i: a compound of the formula (I), marketed by BASF SE as
Tinuvin.RTM. 770. [0113] comp-C-ii: a compound of the formula
(VII), marketed by BASF SE as Tinuvin.RTM. 765.
##STR00013##
[0114] Component D (and comp-D for comparison) used was: [0115]
D-i: a compound of the formula (II), marketed by Cytec Industries
as Cyasorb.RTM. 3853.
[0116] Component E (and comp-E for comparison) used was: [0117]
E-i: a compound of the formula (III), marketed by BASF SE as
Chimassorb.RTM. 944. [0118] E-ii: a compound of the formula (IV),
marketed by Adeka as Adeka Stab.RTM. LA-68. [0119] E-iii: a
compound of the formula (V), marketed by Cytec Industries as
Cyasorb.RTM. UV-3346. [0120] comp-E-iiii: a high-molecular-weight
sterically hindered amine, CAS number 106990-43-6, marketed by SABO
S.p.A. as Sabostab.RTM. 119.
##STR00014##
[0121] Component F (and comp-F for comparison) used was: [0122]
F-i: Black Pearls 880 carbon black, marketed by Cabot
Corporation
Production of the Molding Compositions and Moldings:
[0123] Components A, B, C, and D (see Table 1 for respective parts
by weight) were homogenized in a ZSK30 twin-screw extruder from
Werner & Pfleiderer at 250.degree. C., and extruded into a
water bath. The extrudates were granulated and dried. The granules
were used in an injection-molding machine at a melt temperature of
260.degree. C. and a mold surface temperature of 60.degree. C. to
produce test specimens, and the properties specified in Table 1
were determined.
TABLE-US-00001 TABLE 1 Constitution and properties of molding
compositions (prefix comp: for comparison) comp- comp- comp- comp-
comp- Example 1 2 3 4 5 6 7 8 9 Constitution AB-i 97 97 97 97 -- --
-- 97 97 comp-AB-ii -- -- -- -- 97 99.75 -- -- -- comp-AB-iii --
99.8 -- -- C-i 0.5 0.5 0.5 0.5 0.5 0.05 0.1 0.5 comp-C-ii -- -- --
-- -- -- -- 0.5 -- D-i 0.5 0.25 0.25 0.25 0.25 0.05 -- 0.25 -- E-i
-- 0.25 -- -- 0.25 0.1 0.1 0.25 -- E-ii -- -- 0.25 -- -- -- -- --
-- E-iii -- -- -- 0.25 -- -- -- -- -- comp-E-iv -- -- -- -- -- --
-- -- 0.5 F-i 2 2 2 2 2 2 2 2 2 Properties Gloss after 0 h of WT 97
96 98 96 83 89 102 98 96 500 h of WT 83 88 87 87 71 65 101 78 74
1000 h of WT 27 32 35 33 11 5 7 3 2 .DELTA.E after 0 h of WT 0 0 0
0 0 0 0 0 0 500 h of WT 0.3 0.2 0.3 0.3 1.1 1.4 1.2 1.4 1.8 1000 h
of WT 0.8 0.6 0.7 0.6 1.7 2.3 3.8 3.8 4.2
[0124] The examples provide evidence that when the molding
compositions of the invention are compared with the known
stabilized molding compositions they exhibit a further improvement
in weathering resistance, i.e. a further improvement in resistance
to heat, to light, and/or to oxygen. Constitution has been given in
parts by weight, and the abbreviation WT means weathering time.
* * * * *