U.S. patent application number 12/986718 was filed with the patent office on 2011-07-21 for process for producing thermoplastic molding compositions based on styrene copolymers and polyamide with improved toughness.
Invention is credited to Marko Blinzler, Norbert Guntherberg, Martin Weber.
Application Number | 20110178205 12/986718 |
Document ID | / |
Family ID | 44278010 |
Filed Date | 2011-07-21 |
United States Patent
Application |
20110178205 |
Kind Code |
A1 |
Weber; Martin ; et
al. |
July 21, 2011 |
PROCESS FOR PRODUCING THERMOPLASTIC MOLDING COMPOSITIONS BASED ON
STYRENE COPOLYMERS AND POLYAMIDE WITH IMPROVED TOUGHNESS
Abstract
The invention relates to processes for producing thermoplastic
molding compositions, where the thermoplastic molding compositions
comprise a) as component A, from 3 to 79% by weight of one or more
(methyl)styrene-acrylonitrile copolymers, which have no
maleic-anhydride-derived units. b) as component B, from 15 to 91%
by weight of one or more polyamides, c) as component C, from 5 to
50% by weight of one or more rubbers, d) as component D, from 1 to
25% by weight of one or more compatibilizers, e) as component E,
from 0 to 2% by weight of one or more low-molecular-weight
compounds which comprise a dicarboxylic anhydride group, f) as
component F, from 0 to 50% by weight of one or more fibrous or
particulate fillers, and g) as component G, from 0 to 40% by weight
of further additives, where each of the % by weight values is based
on the total weight of components A to G, and these give a total of
100% by weight, via mixing of components A to G in the melt, which
comprises producing a melt comprising components A, B, and C in a
first step of the process, in the absence of component D, and
delaying the mixing to incorporate component D into this melt until
a subsequent second step of the process, and also to thermoplastic
molding compositions obtainable by these processes, the use of
these thermoplastic molding compositions, and also moldings,
fibers, and foils comprising these thermoplastic molding
compositions.
Inventors: |
Weber; Martin; (Maikammer,
DE) ; Blinzler; Marko; (Mannheim, DE) ;
Guntherberg; Norbert; (Speyer, DE) |
Family ID: |
44278010 |
Appl. No.: |
12/986718 |
Filed: |
January 7, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61295777 |
Jan 18, 2010 |
|
|
|
Current U.S.
Class: |
523/348 ;
524/107 |
Current CPC
Class: |
C08K 7/00 20130101; C08L
33/20 20130101; C08L 25/12 20130101; C08L 77/00 20130101; C08L
51/04 20130101; C08K 5/1539 20130101; C08L 77/00 20130101 |
Class at
Publication: |
523/348 ;
524/107 |
International
Class: |
C08K 5/151 20060101
C08K005/151 |
Claims
1. A process for producing thermoplastic molding compositions,
where the thermoplastic molding compositions comprise a) as
component A, from 3 to 79% by weight of one or more
(methyl)styrene-acrylonitrile copolymers, which have no
maleic-anhydride-derived units, b) as component B, from 15 to 91%
by weight of one or more polyamides, c) as component C, from 5 to
50% by weight of one or more rubbers, d) as component D, from 1 to
25% by weight of one or more compatibilizers, e) as component E,
from 0 to 2% by weight of one or more low-molecular-weight
compounds, which comprise a dicarboxylic anhydride group, f) as
component F, from 0 to 50% by weight of one or more fibrous or
particulate fillers, and g) as component G, from 0 to 40% by weight
of further additives, where each of the % by weight values is based
on the total weight of components A to G, and these give a total of
100% by weight, via mixing of components A to G in a melt, which
comprises producing a melt comprising components A, B, and C in a
first step of the process, in the absence of component D, and
delaying the mixing to incorporate component D into the melt
comprising components A, B, and C until a second step of the
process.
2. The process according to claim 1, wherein component C comprises
a butadiene graft rubber and/or an alkyl acrylate graft rubber.
3. The process according to claim 1, wherein component D comprises
one or more (methyl)styrene-acrylonitrile copolymers, which, based
on the entirety of component D, have from 0.5 to 5% by weight of
maleic-anhydride-derived units.
4. The process according to claim 1, wherein component E comprises
maleic anhydride, phthalic anhydride, trimellitic anhydride, or a
mixture thereof.
5. The process according to claim 1, wherein the melt is produced
in a screw extruder, which comprises, in a sequence along a
direction of conveying, at least one feed zone, one plastifying
zone, one homogenizing zone, and one discharge zone, after addition
of components A, B, and C to the feed zone, in the first step of
the process, in the absence of component D, and, in the second step
of the process, after addition of component D to the homogenizing
zone, the mixing to incorporate component D into the melt is
carried out.
6. The process according to claim 1, wherein the melt is produced
in a screw extruder with effective length L, where the effective
length L is defined as the distance from the first feed device for
the addition of components A, B, and/or C to the discharge aperture
in the direction of conveying, after addition of components A, B,
and C, in the region from 0 L to 0.15 L, in the first step of the
process, in the absence of component D, and, in the second step of
the process, after addition of component D, in the region from 0.3
L to 0.99 L, the mixing to incorporate component D into the melt is
carried out.
7. A thermoplastic molding composition, capable of production by a
process according to claim 1.
8. The use of thermoplastic molding compositions according to claim
7 for producing moldings, foils, or fibers.
9. A molding, fiber, or film, comprising thermoplastic molding
compositions according to claim 7.
10. The process according to claim 2, wherein component D comprises
one or more (methyl)styrene-acrylonitrile copolymers, which, based
on the entirety of component D, have from 0.5 to 5% by weight of
maleic-anhydride-derived units.
11. The process according to claim 2, wherein component F comprises
maleic anhydride, phthalic anhydride, trimellitic anhydride, or a
mixture thereof.
12. The process according to claim 3, wherein component E comprises
maleic anhydride, phthalic anhydride, trimellitic anhydride, or a
mixture thereof.
13. The process according to claim 2, wherein the melt is produced
in a screw extruder, which comprises, in a sequence along a
direction of conveying, at least one feed zone, one plastifying
zone, one homogenizing zone, and one discharge zone, after addition
of components A, B, and C to the feed zone, in the first step of
the process, in the absence of component D, and, in the second step
of the process, after addition of component D to the homogenizing
zone, the mixing to incorporate component D into the melt is
carried out.
14. The process according to claim 3, wherein the melt is produced
in a screw extruder, which comprises, in a sequence along a
direction of conveying, at least one feed zone, one plastifying
zone, one homogenizing zone, and one discharge zone, after addition
of components A, B, and C to the feed zone, in the first step of
the process, in the absence of component D, and, in the second step
of the process, after addition of component D to the homogenizing
zone, the mixing to incorporate component D into the melt is
carried out.
15. The process according to claim 4, wherein the melt is produced
in a screw extruder, which comprises, in a sequence along a
direction of conveying, at least one feed zone, one plastifying
zone, one homogenizing zone, and one discharge zone, after addition
of components A, B, and C to the feed zone, in the first step of
the process, in the absence of component D, and, in the second step
of the process, after addition of component D to the homogenizing
zone, the mixing to incorporate component D into the melt is
carried out.
16. The process according to claim 2, wherein the melt is produced
in a screw extruder, which comprises, in a sequence along a
direction of conveying, at least one feed zone, one plastifying
zone, one homogenizing zone, and one discharge zone, after addition
of components A, B, and C to the feed zone, in the first step of
the process, in the absence of component D, and, in the second step
of the process, after addition of component D to the homogenizing
zone, the mixing to incorporate component D into the melt is
carried out.
17. The process according to claim 3, wherein the melt is produced
in a screw extruder, which comprises, in a sequence along a
direction of conveying, at least one feed zone, one plastifying
zone, one homogenizing zone, and one discharge zone, after addition
of components A, B, and C to the feed zone, in the first step of
the process, in the absence of component D, and, in the second step
of the process, after addition of component D to the homogenizing
zone, the mixing to incorporate component D into the melt is
carried out.
18. The process according to claim 4, wherein the melt is produced
in a screw extruder, which comprises, in a sequence along a
direction of conveying, at least one feed zone, one plastifying
zone, one homogenizing zone, and one discharge zone, after addition
of components A, B, and C to the feed zone, in the first step of
the process, in the absence of component D, and, in the second step
of the process, after addition of component D to the homogenizing
zone, the mixing to incorporate component D into the melt is
carried out.
19. The process according to claim 5, wherein the melt is produced
in a screw extruder, which comprises, in a sequence along a
direction of conveying, at least one feed zone, one plastifying
zone, one homogenizing zone, and one discharge zone, after addition
of components A, B, and C to the feed zone, in the first step of
the process, in the absence of component D, and, in the second step
of the process, after addition of component D to the homogenizing
zone, the mixing to incorporate component D into the melt is
carried out.
20. A thermoplastic molding composition, capable of production by a
process according to claim 2.
Description
[0001] The invention relates to processes for producing
thermoplastic molding compositions, where the thermoplastic molding
compositions comprise [0002] a) as component A, from 3 to 79% by
weight of one or more (methyl)styrene-acrylonitrile copolymers,
which have no maleic-anhydride-derived units, [0003] b) as
component B, from 15 to 91% by weight of one or more polyamides,
[0004] c) as component C, from 5 to 50% by weight of one or more
rubbers, [0005] d) as component D, from 1 to 25% by weight of one
or more compatibilizers, [0006] e) as component E, from 0 to 2% by
weight of one or more low-molecular-weight compounds which comprise
a dicarboxylic anhydride group, [0007] f) as component F, from 0 to
50% by weight of one or more fibrous or particulate fillers, and
[0008] g) as component G, from 0 to 40% by weight of further
additives, where each of the % by weight values is based on the
total weight of components A to G, and these give a total of 100%
by weight, via mixing of components A to G in the melt, and also to
thermoplastic molding compositions obtainable by these processes,
the use of these thermoplastic molding compositions, and also
moldings, fibers, and foils comprising these thermoplastic molding
compositions.
[0009] Polymeric blends made of (methyl)styrene-acrylonitrile
copolymers and of polyamides are known per se. Binary blends made
of these polymer components have very poor toughness values,
because of the incompatibility between polyamide and, for example,
styrene-acrylonitrile copolymer. Use of compatibilizers can
significantly improve the toughness of the blends, and also their
chemicals resistance, as described by way of example in EP 202 214
B1, EP 402 528 A2, and EP 784 080 B1. The sequence of mixing of the
polymer components and compatibilizer during production of the
blends HMS/ma 18.01.10
made of (methyl)styrene-acrylonitrile copolymers and of polyamides
is in principle described in the abovementioned specifications as
being any desired sequence, and all of the components are generally
introduced together into a mixing apparatus, i.e. are mixed with
one another in the melt simultaneously in a single step of the
process. Particularly suitable compatibilizers are
styrene-acrylonitrile-maleic anhydride terpolymers,
styrene-N-phenylmaleimide-maleic anhydride terpolymers, and methyl
methacrylate-maleic anhydride copolymers. It is assumed that the
amino or carboxy end groups of the polyamides react with the
functional groups of the abovementioned co- and terpolymers, thus
producing in situ copolymers which provide compatibility between
the styrene copolymer phase and the polyamide phase.
[0010] However, there are many applications for which the toughness
level of known mixtures of (methyl)styrene-acrylonitrile copolymers
and of polyamides is not satisfactory. The content of volatile
components in the known mixtures is moreover disadvantageous in
many applications.
[0011] It is therefore an object of the present invention to
provide thermoplastic molding compositions which are based on
impact-modified (methyl)styrene-acrylonitrile copolymers and on
polyamides and which, when compared with known molding compositions
of this type, exhibit a further improvement in impact resistance
and/or lower content of volatile components.
[0012] The processes mentioned in the introduction have accordingly
been found, and it is essential to the invention here that a melt
comprising components A, B, and C is produced in a first step of
the process, in the absence of component D, and that the mixing to
incorporate component D into this melt is delayed to a subsequent
second step of the process.
[0013] Thermoplastic molding compositions obtainable by these
processes have moreover been found, as also has the use of these
thermoplastic molding compositions, and also moldings, fibers, and
foils which comprise these thermoplastic molding compositions.
[0014] When the thermoplastic molding compositions that can be
produced by the processes of the invention are compared with known
molding compositions based on impact-modified
(methyl)styrene-acrylonitrile copolymers and on polyamides, they
exhibit a further improvement in impact resistance and/or lower
content of volatile components.
[0015] The processes and articles of the invention are described
below.
[0016] The thermoplastic molding compositions that can be produced
by the processes of the invention comprise [0017] a) from 3 to 79%
by weight, preferably from 5 to 55% by weight, particularly
preferably from 10 to 25% by weight, of component A, [0018] b) from
15 to 91% by weight, preferably from 25 to 78% by weight,
particularly preferably from 35 to 60% by weight, of component B,
[0019] c) from 5 to 50% by weight, preferably from 15 to 45% by
weight, particularly preferably from 25 to 40% by weight of
component C, [0020] d) from 1 to 25% by weight, preferably from 2
to 15% by weight, particularly preferably from 3 to 7% by weight,
of component D, [0021] e) from 0 to 2% by weight, preferably from 0
to 1% by weight, particularly preferably from 0 to 0.5% by weight,
of component E, [0022] f) from 0 to 50% by weight, preferably from
0 to 38% by weight, particularly preferably from 0 to 27% by
weight, of component F, and [0023] g) from 0 to 40% by weight,
preferably from 0 to 10% by weight, particularly preferably from 0
to 5% by weight, of component G, and each of the % by weight values
is based on the total weight of components A to G, and these give a
total of 100% by weight.
Component A
[0024] The thermoplastic molding compositions of the invention
comprise, as component A, one or more (methyl)styrene-acrylonitrile
copolymers which have no maleic-anhydride-derived units.
(Methyl)styrene-acrylonitrile copolymers are any of the copolymers
which are obtainable via copolymerization of one or more
vinylaromatic monomers, preferably from styrene and/or
.alpha.-methylstyrene, with acrylonitrile; any desired other
suitable monomers that differ from maleic anhydride can be present
here in the copolymers, alongside the abovementioned monomers.
Component A is preferably a styrene-acrylonitrile copolymer and/or
an .alpha.-methylstyrene-acrylonitrile copolymer.
(Methyl)styrene-acrylonitrile copolymers and the production thereof
are known to the person skilled in the art and are described in the
literature.
[0025] 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 vinylaromatic monomers, in particular styrene
and/or .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 these give a total of
100% by weight.
[0026] The abovementioned further monomers that can be used are any
monomers that are copolymerizable and differ from maleic anhydride,
examples being p-methylstyrene, tert-butylstyrene,
vinylnaphthaline, alkyl acrylates and/or alkyl methacrylates, for
example those having C.sub.1-C.sub.8-alkyl radicals,
N-phenylmaleimide, and mixtures of these.
[0027] The copolymers of component A can be produced by methods
known per se. By way of example, they can be produced via
free-radical polymerization, in particular via emulsion,
suspension, solution, or bulk polymerization.
[0028] Component A is preferably rubber-free.
Component B
[0029] The thermoplastic molding compositions of the invention
comprise, as component B, one or more polyamides. Polyamides and
production thereof are known to the person skilled in the art and
are described in the literature (see, for example, WO 95/28443, WO
99/41297 and DE-A 198 12 135).
[0030] Polyamides are understood to be homopolymers or copolymers
which have repeat amide groups as essential constituent in the main
polymer chain. Examples of these polyamides are nylon-6
(polycaprolactam), nylon-6,6 (polyhexamethyleneadipamide),
nylon-4,6 (polytetramethyleneadipamide), nylon-5,10
(polypentamethyleneadipamide), nylon-6,10
(polyhexamethylenesebacamide), nylon-7 (polyenantholactam),
nylon-11 (polyundecanolactam), nylon-12 (polydodecanolactam).
Nylon-6 is preferably used as component B.
[0031] In another preferred embodiment, a polyamide is used as
component B and comprises, based on the entirety of component B,
from 0.01 to 1% by weight, preferably from 0.05 to 0.5% by weight,
in particular from 0.1 to 0.2% by weight, of end groups that derive
from triacetonediamine (TAD).
[0032] It is also possible to use polyamides that have been
produced via copolycondensation of two or more of the
abovementioned monomers or components thereof, e.g. copolymers of
adipic acid, isophthalic acid, or terephthalic acid and
hexamethylenediamine, or copolymers of caprolactam, terephthalic
acid, and hexamethylenediamine. Semiaromatic copolyamides of this
type preferably comprise from 40 to 90% by weight of units derived
from terephthalic acid and from hexamethylenediamine. A small
proportion of the terephthalic acid, and preferably not more than
10% by weight of the entirety of aromatic dicarboxylic acids used,
can be replaced by isophthalic acid or by other aromatic
dicarboxylic acids, preferably those in which the carboxy groups
are in para-position. A preferred semiaromatic polyamide is
nylon-9,T, derived from nonanediamine and terephthalic acid. The
semiaromatic copolyamides can by way of example be produced by the
process described in EP-A-129 195 and EPA-129 196.
Component C
[0033] The thermoplastic molding compositions that can be produced
in the invention comprise, as component C, one or more rubbers. In
principle, any of the elastomeric polymers or elastomers known to
the person skilled in the art is suitable. Examples of suitable
materials are graft rubbers based on butadiene, for example
butadiene/styrene, and EPDM (ethylene-propylene-diene rubbers), or
alkyl acrylates. The glass transition temperature Tg of these
elastomeric polymers is generally .ltoreq.0.degree. C.
[0034] Particularly suitable rubbers C for the purposes of the
present invention are those which comprise [0035] a diene rubber
based on dienes such as butadiene or isoprene, [0036] an alkyl
acrylate rubber based on alkyl esters of acrylic acid, e.g. n-butyl
acrylate and 2-ethylhexyl acrylate, [0037] an EPDM rubber based on
ethylene and propylene, and on a diene, [0038] a silicone rubber
based on polyorganosiloxanes, or any mixture of these rubbers and,
respectively, rubber monomers.
[0039] A rubber C to which particular preference is given is a
graft polymer made of a graft base, in particular a crosslinked
diene graft base or a crosslinked alkyl acrylate graft base, and of
one or more graft shells, in particular one or more styrene,
acrylonitrile or methyl methacrylate graft shells.
[0040] Processes for producing the elastomeric polymers are known
to the person skilled in the art and are described in the
literature.
Component D
[0041] The thermoplastic molding compositions that can be produced
by the processes of the invention comprise, as component D, one or
more compatibilizers. These compatibilizers suitable for mixtures
of (methyl)styrene-acrylonitrile copolymers and polyamides are
known to the person skilled in the art and are described in the
literature.
[0042] Components D that can be used with preference as
compatibilizers are (methyl)styrene-acrylonitrile copolymers which,
based on the entirety of component D, have from 0.5 to 5% by weight
of maleic-anhydride-derived units. This proportion of maleic
anhydride is preferably from 1 to 3% by weight, in particular from
2.0 to 2.2% by weight. In principle, the materials can also
comprise further monomer components, in particular
N-phenylmaleimide.
[0043] Component D is particularly preferably a
styrene-acrylonitrile-maleic anhydride terpolymer. The proportion
of acrylonitrile, based on the entirety of the terpolymer, is
preferably from 10 to 30% by weight in the terpolymer, particularly
preferably from 15 to 30% by weight, in particular from 20 to 25%
by weight, and the proportion of maleic-anhydride-derived units
corresponds to the amounts mentioned above. The remainder is made
up by styrene.
[0044] The molar masses M.sub.w of the maleic-anhydride-containing
(methyl)styrene-acrylonitrile copolymers that can be used with
preference are generally from 30 000 to 500 000 g/mol, preferably
from 50 000 to 250 000 g/mol, in particular from 70 000 to 200 000
g/mol, determined by GPC, using tetrahydrofuran (THF) as eluent,
and polystyrene calibration.
Component E
[0045] A low-molecular-weight compound which has only one
dicarboxylic anhydride group can be used concomitantly as further
component E. For the purposes of the present inventions,
low-molecular-weight compounds are those with molar mass less than
1000 g/mol. However, it is also possible to use two or more of
these compounds as component E. These compounds can comprise,
alongside the dicarboxylic anhydride group, further functional
groups, where these can react with the end groups of the
polyamides. Examples of suitable compounds E are
C.sub.4-C.sub.10-alkyldicarboxylic anhydrides, such as succinic
anhydride, glutaric anhydride, and adipic anhydride. Cycloaliphatic
dicarboxylic anhydrides can also be used, an example being
cyclohexane-1,2-dicarboxylic anhydride. However, it is also
possible to use dicarboxylic anhydrides which are ethylenically
unsaturated or aromatic compounds, examples being maleic anhydride,
phthalic anhydride, trimellitic anhydride, and mixtures of these.
The compounds that can be used as component E and the production
thereof, are known to the person skilled in the art and are
described in the literature.
Component F
[0046] The thermoplastic molding compositions of the invention can
comprise, as component F, one or more fibers or particulate
fillers. Preferred fibrous fillers or fibrous reinforcing materials
are carbon fibers, potassium titanate whiskers, aramid fibers, and
particularly preferably glass fibers. If glass fibers are used,
these can have been equipped with size and with an adhesion
promoter, to improve compatibility with the matrix material. The
diameter of the carbon fibers and glass fibers used is generally in
the range from 6 to 20 .mu.m. The glass fibers can be incorporated
either in the form of short glass fibers or else in the form of
long glass fibers or continuous-filament strands, and also by way
of example in the form of what are known as rovings. The average
length of the glass fibers in the finished injection molding is
preferably in the range from 0.08 to 0.5 mm.
[0047] Carbon fibers or glass fibers can also be used in the form
of textiles, mats, or glass silk rovings.
[0048] Suitable particulate fillers are amorphous silica, magnesium
carbonate (chalk), powdered quartz, mica, talc, feldspar, glass
beads, and in particular calcium silicates, such as wollastonite,
and kaolin (particularly calcined kaolin).
[0049] Particularly preferred combinations of fillers are those
made of glass fibers and wollastonite.
Component G
[0050] The thermoplastic molding compositions that can be produced
in the invention can comprise, as component G, one or more further
additives. In principle, any of the additives conventionally used
in plastics and described in the literature and known to the person
skilled in the art is suitable. For the purposes of the present
invention, examples of additives conventionally used in plastics
are stabilizers and oxidation retarders, agents to counteract
decomposition due to heat and decomposition due to ultraviolet
light, lubricants and mold-release agents, dyes and pigments, and
plasticizers.
[0051] Examples of oxidation retarders and heat stabilizers are
halides of metals of group I of the Periodic Table of the Elements,
e.g. sodium halides, potassium halides, and lithium halides. It is
also possible to use zinc fluoride and zinc chloride. It is also
possible to use sterically hindered phenols, hydroquinones,
substituted members of that group, secondary aromatic amines, if
appropriate in conjunction with phosphorus-containing acids or
salts of these, and mixtures of said compounds, preferably at
concentrations of up to 1% by weight, based on the weight of the
thermoplastic molding compositions. Examples of UV stabilizers are
various substituted resorcinols, salicylates, benzotriazoles, and
benzophenones, the amounts generally used of these being up to 2%
by weight, based on the weight of the thermoplastic molding
compositions.
[0052] Lubricants and mold-release agents, the amounts of which
that can generally be added, based on the weight of the
thermoplastic molding compositions, are up to 1%. are stearic acid,
stearyl alcohol, alkyl stearates, and stearamides, and also esters
of pentaerythritol with long-chain fatty acids. It is also possible
to use stearates of calcium, of zinc, or of aluminum, and also
dialkyl ketones, e.g. distearyl ketone. Calcium stearate is
particularly suitable in the invention.
Production Processes
[0053] According to the processes of the invention, a melt
comprising components A, B, and C is produced in a first step of
the process, in the absence of component D and the mixing to
incorporate component D into said melt is delayed until a
subsequent second step of the process. If the intention is to admix
one or more components E, F, or G, this can take place in the first
step of the process or in the second step of the process, or else
in both steps of the process. In principle it is of course also
possible not to use the entire amount of components A, B, and C in
the first step of the process, and instead to delay feeding of some
amount of said components into the melt until the second step of
the process.
[0054] The form in which component D is added to the melt
comprising components A, B, C, and, if appropriate, E, F, and G can
preferably be that of a solid, in particular of pellets, but in
principle can also be that of a melt or a solution.
[0055] The production of the melt comprising components A, B, C,
and, if appropriate, E, F, and G in the first step of the process,
in the absence of component D, takes place by processes known to
the person skilled in the art, for example via mixing of a melt of
component A with the further components B and C, and/or, if
appropriate, E, F, and G, using apparatuses known to the person
skilled in the art, for example screw extruders, kneaders, or
mixers, preferably at temperatures in the range from 220 to
300.degree. C., in particular from 230 to 290.degree. C. Each of
the components can be introduced in pure form into the mixing
apparatuses. However, it is also possible to begin by premixing
individual components and then to mix them with the other
components.
[0056] In the second step of the process of the invention,
component D is incorporated by mixing into the melt obtained in the
first step of the process. (It is also possible in the second step
of the process to use mixing to incorporate some amounts of
components A, B, and C which were not incorporated by mixing in the
first step of the process.) The mixing to incorporate component D
takes place by processes that are known to the person skilled in
the art and that have been described above, examples being mixing
in the melt in screw extruders, kneaders, or mixers. The average
mixing time to achieve a homogeneous mixture, in both the first and
the second step of the process, independently of one another, is
generally from 5 sec to 30 min.
[0057] In one preferred embodiment of the processes of the
invention, the thermoplastic molding compositions are produced via
mixing in the melt in a screw extruder which comprises in this
sequence along the direction of conveying, at least one feed zone,
one plastifying zone, one homogenizing zone, and one discharge
zone, where, after addition of components A, B, and C to the feed
zone, in a first step of the process, in the absence of component
D, a melt is produced, and, in a second step of the process, after
addition of component D to the homogenizing zone, the mixing to
incorporate component D into said melt is carried out.
[0058] Suitable screw extruders are described by way of example in
Saechtling, Kunststoff-Taschenbuch [Plastics handbook], Hanser
Verlag, Munich, Vienna, 26th edition, 1995, pp. 191 to 246.
[0059] Screw extruders usually have sections of different
functionality, known as "zones". (See, for example, Kohlgruber, Der
gleichlaufige Doppelschnecken-extruder [Corotating twin-screw
extruders], Carl Hanser Verlag, Munich, 2007, pp. 61-75). The
various zones of screw extruders are not necessarily identical with
the individual components such as barrel sections or screw
segments, from which the screw extruders have been assembled. One
zone is generally composed of a plurality of components. The
individual zones can, depending on function, have various spatial
dimensions, for example various lengths or volumes.
[0060] Screw extruders usually have one or more of the zones
described below. However, screw extruders can also have zones with
a function not explicitly described below.
[0061] The feed zone is to be understood to mean that section of a
screw extruder in which one or more components, for example a
thermoplastically processable polymer, are introduced into the
screw extruder. This introduction can be achieved by using a feed
device, composed by way of example of an upper aperture in the
screw extruder with superposed hopper, so that gravity conveys the
feed component into the screw extruder. However, the feed device
can also by way of example be composed of a conveying screw or of
an extruder, via which the feed component is forced through the
feed aperture of the screw extruder.
[0062] The plastifying zone (also often termed melting zone) is
that section of a screw extruder in which a component, in
particular components A, B, and C, is converted to a condition that
is moldable by supply of heat, mostly molten or capable of plastic
deformation. This is generally achieved via heating or via
mechanical introduction of energy. For the introduction of
mechanical energy it is possible to use, as plastifying elements,
the components familiar to the person skilled in the art, examples
being screw elements with very small degree of pitch in the
direction of conveying, screw elements with pitch opposed to the
direction of conveying, kneading blocks with conveying, neutral, or
reverse-conveying pitch, or a combination of these elements. The
selection of the type, number, and dimensions of the plastifying
elements in the plastifying zone depends on the components of the
thermoplastic molding compositions, in particular on the viscosity
and softening point, and also the miscibility of the
components.
[0063] The homogenizing zone is that section of a screw extruder in
which one or more components are homogenized, at least one of these
being in the condition that is moldable by supply of heat. Said
homogenization is mostly achieved via mixing, kneading, or
shearing. Examples of suitable mixing, kneading, and shearing
elements are kneading blocks having narrow or wide, conveying or
non-conveying kneading disks.
[0064] The discharge zone is that section of a screw extruder in
which the thermoplastically processable molding composition is
prepared discharged from the screw extruder and is discharged
through the discharge aperture. The discharge zone is mostly
composed of a conveying screw and of a closed barrel section
terminated by a defined discharge aperture.
[0065] A die head is preferably used as discharge aperture and by
way of example has been designed in the form of a die plate or die
lip, where the dies can be circular (perforated die plate),
slot-shaped, or of any other shape. When a die plate is used, the
product discharged in the form of a strand is conventionally cooled
and pelletized, for example in water.
[0066] If the thermoplastically processable molding composition is
not first obtained in the form of pellets but is intended for
direct further use, another advantageous method is further
processing while the material is hot, or direct extrusion of
sheets, foils, pipes, and profiles.
[0067] A screw extruder can moreover comprise further zones, such
as deaeration zones or devolatilization zones, for the dissipation
of gaseous constituents, or squeeze zones and dewatering zones, for
the removal and discharge of liquid constituents, which can be
water or else other substances. WO 98/13412 describes
devolatilization zones, squeeze zones, and dewatering zones, and
also the apparatus and arrangement used for these, and express
reference is therefore made to the abovementioned specification in
relation to said features.
[0068] The individual zones can be capable of clear delimitation
spatially from one another, or can transform continuously into one
another. By way of example, therefore, the transition from the
plastifying zone to the homogenizing zone is not always capable of
clear spatial delimitation in an extruder. There is often a
continuous transition between the two zones.
[0069] As is well known, the various zones of a screw extruder can
be individually heated or cooled, in order to establish an ideal
temperature profile along the direction of conveying. Suitable
heating and cooling equipment is known to the person skilled in the
art.
[0070] The temperatures and spatial dimensions to be selected in
any individual case for the individual zones differ as a function
of the chemical and physical properties of the components and the
quantitative proportions of these. By way of example, therefore,
the mixing temperatures in the homogenizing zone are generally from
100 to 400.degree. C. preferably from 200 to 320.degree. C.
[0071] The screw extruders used can comprise single-screw extruders
or twin-screw extruders, which may be corotating and intermeshing,
contrarotating and intermeshing, or else non-intermeshing. It is
preferable to use twin-screw extruders. Particular preference is
given to corotating, intermeshing twin-screw extruders.
[0072] It is possible to use extruders having screws with small,
moderate, or large flight depth (known as "deepcut screws"). The
flight depth of the screws to be used depends on the type of
machinery. The respective type of machinery to be used depends on
the respective task.
[0073] The number of flights on the screws of the extruder can
vary. It is preferable to use double-flighted screws. However, it
is also possible to use screws having other numbers of flights,
examples being single-flighted or triple-flighted screws, or screws
which have sections with different numbers of flights.
[0074] The screw rotation rates of the extruder can vary widely. It
is preferable to use relatively high rotation rates. Suitable
rotation rates are in the range from 50 to 1800 rpm, preferably
from 100 to 1000 rpm, particularly preferably from 200 to 900
rpm.
[0075] In one preferred embodiment of the processes of the
invention, a screw extruder of effective length L is used for the
mixing of components A, B, C, D, and, if appropriate, E, F, and G
in the melt, where the effective length L is defined as the
distance from the first feed device for the addition of components
A, B, and/or C to the discharge aperture in the direction of
conveying. Addition of components A, B, and C preferably takes
place in the region from 0 L to 0.15 L, where a melt is produced in
a first step of the process, in the absence of component D.
Addition of component D, and incorporation by mixing into the melt
comprising components A, B, and C, in the second step of the
process, preferably takes place in the region from 0.3 L to 0.99 L,
particularly preferably in the region from 0.35 L to 0.9 L, in
particular in the region from 0.4 L to 0.7 L. Irrespective of the
expressions "first step of the process" and "second step of the
process", which serve for clarification, to the effect that the
production of the melt comprising components A, B, and C on the one
hand and the mixing to incorporate component D on the other hand
are two chronologically and/or spatially separate procedures, the
operation of the extruder is of course continuous and preferably
steady-state.
[0076] The thermoplastic molding compositions of the invention can
be used for producing moldings, fibers, and foils. They are
particularly used for producing moldings. e.g. for motor-vehicle
components or in electronic equipment.
[0077] When the thermoplastic molding compositions that can be
produced by the processes of the invention are compared with known
molding compositions based on impact-modified
(methyl)styrene-acrylonitrile copolymers and on polyamides, they
exhibit a further improvement in impact resistance and/or a lower
content of volatile components.
[0078] The examples below provide further illustration of the
invention.
EXAMPLES
Test Methods
[0079] The intrinsic viscosities IV of the
(methyl)styrene-acrylonitrile copolymers and compatibilizers were
determined to DIN 53727 on a 0.5% strength by weight solution in
dimethylformamide at 25.degree. C.
[0080] The intrinsic viscosities IV of the polyamides were
determined to DIN 53727 on a 0.5% strength by weight solution in
concentrated sulfuric acid (96% by weight H.sub.2SO.sub.4) at
25.degree. C.
[0081] The average particle sizes of the graft copolymers used as
rubbers were determined in the form of weight-average particle
sizes by means of an analytical ultracentrifuge, using the method
of W. Scholtan and H. Lange, Kolloid-Z, und Z.-Polymere 250 (1972),
pp. 782 to 796.
[0082] The Vicat B heat-distortion temperature of the thermoplastic
molding compositions was determined by means of the Vicat softening
point. The Vicat softening point was determined to DIN 53 460,
using a force of 49.05 N and a temperature rise of 50 K per hour,
on standard small specimens.
[0083] The impact resistance a.sub.n of the thermoplastic molding
compositions at room temperature (RT) and -30.degree. C. was
determined on ISO specimens to ISO 179 1eU.
[0084] The notched impact resistance a.sub.k of the thermoplastic
molding compositions at room temperature (RT) and -30.degree. C.
was determined on ISO specimens to ISO 179 1eA. Flowability MVI was
determined to ISO 1133 at 240.degree. C. with 10 kg load.
[0085] Contact of volatile compounds in the thermoplastic molding
compositions was determined in the form of total C emission to VDA
277.
Starting Materials:
Component A-1
[0086] Copolymer of 75% by weight of styrene and 25% by weight of
acrylonitrile, characterized via an intrinsic viscosity IV of 80
ml/g.
Component B-1
[0087] Ultramid.RTM. B27 from BASF SE, a nylon-6 obtained from
.epsilon.-caprolactam with intrinsic viscosity of 150 ml/g.
Component B-2
[0088] Nylon-6, obtained from .epsilon.-caprolactam, with 0.16% by
weight triacetonediamine content and intrinsic viscosity of 130
ml/g.
Component C-1
[0089] Particulate graft copolymer composed of 62% by weight of a
graft base made of polybutadiene and 38% by weight of a graft shell
made of 75% by weight of styrene and 25% by weight of
acrylonitrile, with an average particle size of 400 nm.
Component C-2
[0090] Particulate graft copolymer composed of 70% by weight of a
graft base made of polybutadiene and 30% by weight of a graft shell
made of 75% by weight of styrene and 25% by weight of
acrylonitrile, with an average particle size of 370 nm.
Component D-1
[0091] Terpolymer of 74.4% by weight of styrene, 23.5% by weight of
acrylonitrile, and 2.1% by weight of maleic anhydride, with
intrinsic viscosity IV of 66 ml/g.
Component E-1
Phthalic Anhydride
Component F-1
[0092] Chopped glass fiber with polyurethane size and with fiber
diameter of 14 .mu.m.
Component G-1
[0093] Irganox.RTM. PS 802 from BASF SE, a distearyl
dithiopropionate.
[0094] Production of the Thermoplastic Molding Compositions and
Determination of the Properties Thereof:
[0095] The amounts of components A-G specified in tables 1 and 2
were fed into the respective regions 0 to 9 specified in tables 1
and 2 of a twin-screw extruder in continuous steady-state
operation. (The effective length L of the extruder was ten times
the screw diameter (10 D) and comprised 10 regions each of
identical length 0.1 L, where the individual regions were numbered
sequentially in the direction of conveying, beginning with region 0
and ending with region 9). The barrel temperature of the extruder
was from 240 to 260.degree. C. The melt discharged from the
extruder was passed through a water bath and pelletized. The
properties specified in table 1 were determined on said pellets or
on test specimens injection-molded therefrom.
TABLE-US-00001 TABLE 1 Parts by weight of components, region of
respective feed, and properties of molding compositions produced
Example* c-1 c-2 c-3 c-4 c-5 6 7 8 c-9 10 11 Pts. by weight A-1
18.8 18.8 18.8 18.8 18.8 18.8 18.8 18.8 13.8 13.8 13.8 B-1 41 41 41
41 41 41 41 41 -- -- -- B-2 -- -- -- -- -- -- -- -- 53 53 53 C-1 35
35 35 35 35 35 35 28 28 28 23 C-2 -- -- -- -- -- -- -- 7 -- -- 5
D-1 4.88 4.88 4.88 4.88 4.88 4.88 4.88 4.88 5 5 5 E-1 0.12 0.12
0.12 0.12 0.12 0.12 0.12 0.12 -- -- -- G-1 0.2 0.2 0.2 0.2 0.2 0.2
0.2 0.2 0.2 0.2 0.2 Feed region A-1 0 0 0 6 0 0 0 0 0 0 0 B-1 0 4 6
0 0 0 0 0 -- -- -- B-2 -- -- -- -- -- -- -- -- 0 0 0 C-1 0 0 0 0 6
0 0 0 0 0 0 C-2 -- -- -- -- -- -- -- 0 -- -- 0 D-1 0 0 0 0 0 4 6 6
0 6 6 E-1 0 0 0 0 0 4 6 6 -- -- -- G-1 0 0 0 0 0 0 0 0 0 0 0
Properties Vicat B 103 102 102 102 102 102 103 103 115 115 116
[.degree. C.] MVI 14.9 13.5 13.8 16.5 15.7 13.4 16.4 19.3 28.1 30.1
32.1 [ml/10'] a.sub.k, RT 61.1 60.2 58.2 23.2 21.1 62.2 72.9 75.1
56.3 71.2 75.1 [kJ/m.sup.2] a.sub.k, -30.degree. C. 14.2 13.2 12.6
8.9 9.2 13.7 17.3 18.6 14.7 18.9 19.8 [kJ/m.sup.2] Total C emission
[mg/kg] 59 61 63 62 63 51 49 49 41 34 33 *examples identified by
"c" are comparative examples
TABLE-US-00002 TABLE 2 Parts by weight of components, region of
respective feed, and properties of molding compositions produced
Example* c-12 13 14 15 Pts. by weight A-1 18.2 18.2 18.2 18.2 B-1
-- -- -- -- B-2 36.6 36.6 36.6 36.6 C-1 32 32 32 27 C-2 -- -- -- 5
D-1 5 5 5 5 F-1 8 8 8 8 G-1 0.2 0.2 0.2 0.2 Feed region A-1 0 0 0 0
B-1 -- -- -- -- B-2 0 0 0 0 C-1 0 0 0 0 C-2 -- -- -- 0 D-1 0 4 6 6
F-1 6 6 6 6 G-1 0 0 0 0 Properties Vicat B 110 110 111 111
[.degree. C.] MVI 4.2 3.9 3.8 3.6 [ml/10{grave over ( )}] a.sub.k,
RT 8.5 12.1 12.5 13.1 [kJ/m.sup.2] a.sub.n, RT 46 54 56 58
[kJ/m.sup.2] Total C emission 54 43 42 43 [mg/kg] *examples
identified by "c" are comparative examples
[0096] Although, in comparison with known processes, there has been
a marked reduction in the residence time of the compatibilizer,
component D, during the mixing procedure in the extruder, when the
thermoplastic molding compositions that can be produced by the
processes of the invention are compared with known molding
compositions based on impact-modified (methyl)styrene-acrylonitrile
copolymers and on polyamides, they exhibit a further improvement in
impact resistance and/or lower content of volatile components.
* * * * *