U.S. patent application number 13/104079 was filed with the patent office on 2011-09-22 for process for the production of impact-modified polyalkylene terephthalate/polycarbonate compositions.
This patent application is currently assigned to BAYER MATERIALSCIENCE AG. Invention is credited to Pierre MOULINIE.
Application Number | 20110230595 13/104079 |
Document ID | / |
Family ID | 38374710 |
Filed Date | 2011-09-22 |
United States Patent
Application |
20110230595 |
Kind Code |
A1 |
MOULINIE; Pierre |
September 22, 2011 |
PROCESS FOR THE PRODUCTION OF IMPACT-MODIFIED POLYALKYLENE
TEREPHTHALATE/POLYCARBONATE COMPOSITIONS
Abstract
A process for the production of impact-modified composition that
contains polyalkylene terephthalate and polycarbonate resins is
disclosed. The process includes (i) in a first step combining in
the melt at 90 to 175.degree. C. glycidyl ester with at least one
member selected from the first group consisting of polyalkylene
terephthalate and polycarbonate to obtain a molten mixture, said
member in powder form, and (ii) in a subsequent step combining the
molten mixture with at least one component selected from the second
group consisting of polyalkylene terephthalate and polycarbonate to
obtain a composition. The composition is characterized in high
gloss value.
Inventors: |
MOULINIE; Pierre;
(Leverkusen, DE) |
Assignee: |
BAYER MATERIALSCIENCE AG
LEVERKUSEN
DE
|
Family ID: |
38374710 |
Appl. No.: |
13/104079 |
Filed: |
May 10, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11880256 |
Jul 20, 2007 |
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13104079 |
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11818389 |
Jun 14, 2007 |
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11880256 |
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Current U.S.
Class: |
523/451 ;
525/438 |
Current CPC
Class: |
C08L 23/0884 20130101;
C08L 67/02 20130101; C08L 69/00 20130101; C08L 69/00 20130101; C08L
67/02 20130101; C08L 2666/02 20130101; C08L 2666/02 20130101 |
Class at
Publication: |
523/451 ;
525/438 |
International
Class: |
C08L 63/00 20060101
C08L063/00; C08L 67/03 20060101 C08L067/03 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 20, 2006 |
DE |
10 2006 028 233.7 |
Claims
1. A process for the production of impact-modified composition that
contains polyalkylene terephthalate and polycarbonate resins,
comprising (i) in a first step combining a glycidyl ester in the
melt from 90 to 175.degree. C. with at least one member selected
from the first group consisting of polyalkylene terephthalate and
polycarbonate to obtain a mixture, said member in powder form, and
(ii) in a subsequent step combining the mixture with at least one
component selected from the second group consisting of polyalkylene
terephthalate and polycarbonate to obtain an impact-modified
PC/Polyester composition.
2. The process of claim 1 wherein the melt is at 100 to 150.degree.
C.
3. The process of claim 1 wherein the composition obtained includes
A) 4 to 95 parts by weight of polyalkylene terephthalate, B) 4 to
95 parts by weight of aromatic polycarbonate, C) 1 to 30 parts by
weight of glycidyl ester and D) 0 to 20 parts by weight of
conventional additives and processing aids.
4. The process of claim 1 wherein said member of said first group
is polyalkylene terephthalate having mean particle size (d.sub.50)
of 600 to 700 .mu.m.
5. The process of claim 4 wherein said subsequent step is carried
out in the melt at 220 to 300.degree. C.
6. The process of claim 3 wherein said member of said first group
is polyalkylene terephthalate having a mean particle size
(d.sub.50) of 600 to 700 .mu.m and wherein said subsequent step is
carried out at 220 to 300.degree. C.
7. The process of claim 1 wherein said glycidyl ester conforms to
formula (IV) ##STR00005## wherein is H or C.sub.1- to
C.sub.6-alkyl, R.sup.2 is alkyl or aryl, a+b+c=100, a is 50 to
99.5, b is 0.5 to 25 and c is 0 to 50.
8. An article of manufacture prepared by the process of claim 1.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a process for the production of
thermoplastic molding compositions and in particular to
impact-modified compositions containing polyalkylene terephthalate
and polycarbonate.
TECHNICAL BACKGROUND OF THE INVENTION
[0002] Impact-modified molding compositions containing a polyester
resin, a polycarbonate resin and a glycidyl ester as impact
modifier and their use as molding compositions, for example in the
automotive sector for moldings such as, for example, mirror casings
and bonnet ventilation grills, in which a glossy, fault-free
surface appearance is required, are known (see, for example, U.S.
Pat. No. 5,369,154).
[0003] EP-A 0 803 537 discloses a process for the production of
impact-modified polyester/polycarbonate molding compositions,
according to which in a first step a mixture of glycidyl ester
copolymer and polycarbonate resin in the melt is prepared and then,
in a second step, the mixture of glycidyl ester copolymer and
polycarbonate resin is combined with a polyester resin and a second
portion of the polycarbonate resin.
[0004] The object of this invention was, therefore, to develop an
improved process for the production of polyalkylene
terephthalate/polycarbonate compositions impact-modified with
glycidyl ester copolymer that are distinguished by improved gloss
and whereby at the same time a good notched impact strength is
maintained.
SUMMARY OF THE INVENTION
[0005] A process for the production of impact-modified composition
that contains polyalkylene terephthalate and polycarbonate resins
is disclosed. The process includes (i) in a first step combining in
the melt at 90 to 175.degree. C. glycidyl ester with at least one
member selected from the first group consisting of polyalkylene
terephthalate and polycarbonate to obtain a molten mixture, said
member in powder form, and (ii) in a subsequent step combining the
molten mixture with at least one component selected from the second
group consisting of polyalkylene terephthalate and polycarbonate to
obtain a composition. The composition is characterized in high
gloss value.
DETAILED DESCRIPTION OF THE INVENTION
[0006] Surprisingly, it has now been found that a process
comprising a first step in which the polyalkylene terephthalate
and/or polycarbonate is incorporated in powder form into a melt of
the impact modifier, and a second step in which the filled impact
modifier from the first step is mixed with further polyalkylene
terephthalate and/or polycarbonate, preferably in the melt, yields
compositions that are distinguished by improved gloss and whereby
at the same time a good notched impact strength is maintained.
[0007] The invention provides a process for the production of
impact-modified polyalkylene terephthalate/polycarbonate
compositions, comprising [0008] (i) combining a melt of an impact
modifier of glycidyl ester with at least one component selected
from the group consisting of polyalkylene terephthalate in the form
of a powder and polycarbonate in the form of a powder, [0009] (ii)
combining the mixture from (i) with at least one component selected
from the group consisting of polyalkylene terephthalate and
polycarbonate and optionally further components in the melt, [0010]
wherein the melt in step (i) has a temperature of from 90 to
175.degree. C., preferably from 100 to 150.degree. C. In a
preferred embodiment the composition contains [0011] A) from 4 to
95 parts by weight, preferably from 10 to 60 parts by weight,
particularly preferably from 12 to 40 parts by weight, especially
from 15 to 30 parts by weight, of polyalkylene terephthalate,
preferably polybutylene terephthalate, [0012] B) from 4 to 95 parts
by weight, preferably from 20 to 80 parts by weight, particularly
preferably from 25 to 60 parts by weight, especially from 35 to 55
parts by weight, of aromatic polycarbonate, [0013] C) from 1 to 30
parts by weight, preferably from 3 to 25 parts by weight,
particularly preferably from 6 to 20 parts by weight, especially
from 8 to 16 parts by weight, of impact modifier of glycidyl ester
and [0014] D) from 0 to 20 parts by weight, preferably from 0.15 to
15 parts by weight, particularly preferably from 0.2 to 10 parts by
weight, of conventional additives and processing aids, the sum of
the parts by weight of components A+B+C+D being normalized to
100.
[0015] Step (ii) is carried out according to known processes by
melt-mixing of the components. It may be advantageous to pre-mix
individual components. Mixing in the melt the mixture from step (i)
with components A) to D) and optionally with further constituents
preferably takes place at temperatures of from 220 to 300.degree.
C. by kneading, extruding or rolling the components together.
[0016] The mean particle size (d.sub.50), determined by means of
light scattering (Puckhaber, M.; Roethele, S. Powder Handling &
Processing (1999), 11(1), 91-95)), is the diameter above and below
which in each case 50 wt. % of the particles lie.
[0017] The mean particle size d.sub.50 of the pulverulent
polyalkylene terephthalate and of the pulverulent polycarbonate
used in step (i) is preferably from 600 to 700 .mu.m, particularly
preferably from 630 to 640 .mu.m.
[0018] A preferred embodiment of the invention is a process for the
production of impact-modified polyalkylene
terephthalate/polycarbonate compositions, comprising [0019] (i)
combining a melt (at a temperature of from 90 to 175.degree. C.,
preferably from 100 to 150.degree. C.) of an impact modifier of
glycidyl ester with polyalkylene terephthalate according to
component A in the form of a powder having a mean particle size
d.sub.50 of from 600 to 700 .mu.m and [0020] (ii) combining the
mixture from (i) with at least one component selected from the
group consisting of polyalkylene terephthalate (component A) and
polycarbonate (component B) and optionally further components,
characterised in that this process step is carried out at
temperatures of from 220 to 300.degree. C. in the melt by kneading,
extruding or rolling the components together, wherein the
composition contains [0021] A) from 4 to 95 parts by weight,
preferably from 10 to 60 parts by weight, particularly preferably
from 12 to 40 parts by weight, especially from 15 to 30 parts by
weight, of polyalkylene terephthalate, preferably polybutylene
terephthalate, [0022] B) from 4 to 95 parts by weight, preferably
from 20 to 80 parts by weight, particularly preferably from 25 to
60 parts by weight, especially from 35 to 55 parts by weight, of
aromatic polycarbonate, [0023] C) from 1 to 30 parts by weight,
preferably from 3 to 25 parts by weight, particularly preferably
from 6 to 20 parts by weight, especially from 8 to 16 parts by
weight, of impact modifier of glycidyl ester and [0024] D) from 0
to 20 parts by weight, preferably from 0.15 to 15 parts by weight,
particularly preferably from 0.2 to 10 parts by weight, of
conventional additives and processing aids.
Component A
[0025] According to the invention, the compositions contain as
component A) one polyalkylene terephthalate or a mixture of two or
more different polyalkylene terephthalates. Polyalkylene
terephthalates within the scope of the invention are polyalkylene
terephthalates which are derived from terephthalic acid (or
reactive derivatives thereof) and alkanediols, for example based on
propylene glycol or butanediol. According to the invention there is
preferably used as component A) polybutylene terephthalate and/or
polytrimethylene terephthalate, most preferably polybutylene
terephthalate.
[0026] Polyalkylene terephthalates within the scope of the
invention are reaction products of aromatic dicarboxylic acids or
reactive derivatives thereof (e.g. dimethyl esters or anhydrides)
and aliphatic, cycloaliphatic or araliphatic diols, and mixtures of
these reaction products.
[0027] Preferred polyalkylene terephthalates may be prepared from
terephthalic acid (or reactive derivatives thereof) and aliphatic
or cycloaliphatic diols having from 2 to 10 carbon atoms by known
methods (Kunststoff-Handbuch, Vol. VIII, p. 695 ff,
Karl-Hanser-Verlag, Munich 1973).
[0028] Preferred polyalkylene terephthalates contain at least 80
mol %, preferably 90 mol %, based on the dicarboxylic acid, of
terephthalic acid radicals and at least 80 mol %, preferably at
least 90 mol %, based on the diol component, of ethylene glycol
and/or 1,3-propanediol and/or 1,4-butanediol radicals.
[0029] The preferred polyalkylene terephthalates may contain, in
addition to terephthalic acid radicals, up to 20 mol % of radicals
of other aromatic dicarboxylic acids having from 8 to 14 carbon
atoms or of aliphatic dicarboxylic acids having from 4 to 12 carbon
atoms, such as radicals of phthalic acid, isophthalic acid,
naphthalene-2,6-dicarboxylic acid, 4,4'-diphenyldicarboxylic acid,
succinic acid, adipic acid, sebacic acid, azelaic acid,
cyclohexanediacetic acid, cyclohexanedicarboxylic acid.
[0030] The preferred polyalkylene terephthalates may contain, in
addition to ethylene or 1,3-propanediol or 1,4-butanediol glycol
radicals, up to 20 mol % of other aliphatic diols having from 3 to
12 carbon atoms or of cycloaliphatic diols having from 6 to 21
carbon atoms, for example radicals of 1,3-propanediol,
2-ethyl-1,3-propane-diol, neopentyl glycol, 1,5-pentanediol,
1,6-hexanediol, 1,4-cyclohexane-dimethanol,
3-methyl-2,4-pentanediol, 2-methyl-2,4-pentanediol,
2,2,4-trimethyl-1,3-pentanediol and -1,6,2-ethyl-1,3-hexanediol,
2,2-diethyl-1,3-propanediol, 2,5-hexanediol,
1,4-di-(.beta.-hydroxyethoxy)-benzene,
2,2-bis-(4-hydroxycyclohexyl)-propane,
2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane,
2,2-bis-(3-.beta.-hydroxyethoxyphenyl)-propane and
2,2-bis-(4-hydroxypropoxyphenyl)-propane (DE-A 24 07 674, 24 07
776, 27 15 932).
[0031] The polyalkylene terephthalates may be branched by the
incorporation of relatively small amounts of tri- or tetra-hydric
alcohols or of tri- or tetra-basic carboxylic acids, as are
described, for example, in DE-A 19 00 270 and U.S. Pat. No.
3,692,744. Examples of preferred branching agents are trimesic
acid, trimellitic acid, trimethylol-ethane and propane and
pentaerythritol.
[0032] It is advisable to use not more than 1 mol % of the
branching agent, based on the acid component.
[0033] Particular preference is given to polyalkylene
terephthalates that have been prepared solely from terephthalic
acid and reactive derivatives thereof (e.g. dialkyl esters thereof)
and ethylene glycol and/or 1,3-propanediol and/or 1,4-butanediol
(polyethylene and polybutylene terephthalate), and mixtures of
these polyalkylene terephthalates.
[0034] Preferred polyalkylene terephthalates are also copolyesters
which are prepared from at least two of the above-mentioned acid
components and/or from at least two of the above-mentioned alcohol
components, and particularly preferred copolyesters are
poly-(ethylene glycol/1,4-butanediol) terephthalates.
[0035] The polyalkylene terephthalates generally have an intrinsic
viscosity of approximately from 0.4 to 1.5 dl/g, preferably from
0.5 to 1.3 dl/g, in each case measured in phenol/o-dichlorobenzene
(1:1 parts by weight) at 25.degree. C.
[0036] Preferably, the polyesters prepared according to the
invention may also be used in admixture with other polyesters
and/or further polymers. Particular preference is given to the use
of mixtures of polyalkylene terephthalates with other polyesters.
Conventional additives, such as, for example, mold-release agents,
stabilizers and/or flow agents, may be mixed with the polyesters in
the melt or applied to the surface thereof.
Component B
[0037] According to the invention, the compositions according to
the invention contain as component B) a polycarbonate or a mixture
of polycarbonates.
[0038] Preferred polycarbonates are homopolycarbonates and
copolycarbonates based on aromatic dihydroxy compounds (herein
bisphenols) of the general formula (I)
HO--Z--OH (I)
wherein Z is a divalent organic radical having from 6 to 30 carbon
atoms which contains one or more aromatic groups.
[0039] Preference is given to bisphenols of formula (Ia)
##STR00001##
wherein [0040] A represents a single bond,
C.sub.1-C.sub.5-alkylene, C.sub.2-C.sub.5-alkylidene,
C.sub.5-C.sub.6-cycloalkylidene, --O--, --SO--, --CO--, --S--,
--SO.sub.2--, C.sub.6-C.sub.12-arylene, to which there may be fused
further aromatic rings optionally containing hetero atoms, [0041]
or a radical of formula (II) or (III)
[0041] ##STR00002## [0042] each of the substituents B represents
C.sub.1-C.sub.12-alkyl, preferably methyl, halogen, preferably
chlorine and/or bromine, [0043] the substituents x are each
independently of the other 0, 1 or 2, [0044] p represents 1 or 0,
and [0045] R.sup.1 and R.sup.2 may be selected individually for
each X.sup.1 and are each independently of the other hydrogen or
C.sub.1-C.sub.6-alkyl, preferably hydrogen, methyl or ethyl, [0046]
X.sup.1 represents carbon, and [0047] m represents an integer from
4 to 7, preferably 4 or 5, with the proviso that on at least one
atom X.sup.1, R.sup.1 and R.sup.2 are simultaneously alkyl.
[0048] Examples of bisphenols according to the general formula (I)
are bisphenols belonging to the following groups:
dihydroxydiphenyls, bis-(hydroxyphenyl)-alkanes,
bis-(hydroxyphenyl)-cycloalkanes, indane bisphenols,
bis-(hydroxyphenyl) sulfides, bis-(hydroxyphenyl)ethers,
bis-(hydroxyphenyl) ketones, bis-(hydroxyphenyl)sulfones,
bis-(hydroxyphenyl) sulfoxides and
.alpha.,.alpha.'-bis-(hydroxyphenyl)-diisopropylbenzenes.
[0049] Examples of bisphenols according to the general formula (I)
are also derivatives of the mentioned bisphenols which are
obtainable, for example, by alkylation or halogenation on the
aromatic rings of the mentioned bisphenols.
[0050] Examples of bisphenols according to the general formula (I)
are in particular the following compounds: hydroquinone,
resorcinol, 4,4'-dihydroxydiphenyl, bis-(4-hydroxyphenyl) sulfide,
bis-(4-hydroxyphenyl)sulfone,
bis-(3,5-dimethyl-4-hydroxyphenyl)-methane,
bis-(3,5-dimethyl-4-hydroxyphenyl)-sulfone,
1,1-bis-(3,5-dimethyl-4-hydroxyphenyl)-p/m-diisopropylbenzene,
1,1-bis-(4-hydroxyphenyl)-1-phenyl-ethane,
1,1-bis-(3,5-dimethyl-4-hydroxyphenyl)-cyclohexane,
1,1-bis-(4-hydroxyphenyl)-3-methylcyclohexane,
1,1-bis-(4-hydroxyphenyl)-3,3-dimethylcyclohexane,
1,1-bis-(4-hydroxyphenyl)-4-methylcyclohexane,
1,1-bis-(4-hydroxyphenyl)-cyclohexane,
1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane,
2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane,
2,2-bis-(3-methyl-4-hydroxyphenyl)-propane,
2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane,
2,2-bis-(4-hydroxyphenyl)-propane (i.e. bisphenol A),
2,2-bis-(3-chloro-4-hydroxyphenyl)-propane,
2,2-bis-(3,5-dibromo-4-hydroxyphenyl)-propane,
2,4-bis-(4-hydroxyphenyl)-2-methylbutane,
2,4-bis-(3,5-dimethyl-4-hydroxyphenyl)-2-methylbutane,
.alpha.,.alpha.'-bis-(4-hydroxyphenyl)-o-diisopropylbenzene,
.alpha.,.alpha.'-bis-(4-hydroxyphenyl)-m-diisopropylbenzene (i.e.
bisphenol M),
.alpha.,.alpha.'-bis-(4-hydroxyphenyl)-p-diisopropylbenzene and
indane bisphenol.
[0051] Particularly preferred polycarbonates are the
homopolycarbonate based on bisphenol A, the homopolycarbonate based
on 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane and the
copolycarbonates based on the two monomers bisphenol A and
1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane.
[0052] The described bisphenols according to the general formula
(I) may be prepared by known processes, for example from the
corresponding phenols and ketones.
[0053] Suitable bisphenols and processes for their preparation are
described, for example, in the monograph H. Schnell, "Chemistry and
Physics of Polycarbonates", Polymer Reviews, Volume 9, p. 77-98,
Interscience Publishers, New York, London, Sidney, 1964 and in U.S.
Pat. No. 3,028,635, in U.S. Pat. No. 3,062,781, in U.S. Pat. No.
2,999,835, in U.S. Pat. No. 3,148,172, in U.S. Pat. No. 2,991,273,
in U.S. Pat. No. 3,271,367, in U.S. Pat. No. 4,982,014, in U.S.
Pat. No. 2,999,846, in DE-A 1 570 703, in DE-A 2 063 050, in DE-A 2
036 052, in DE-A 2 211 956, in DE-A 3 832 396, and in FR-A 1 561
518 and also in the Japanese Offenlegungsschriften having the
application numbers JP-A 62039 1986, JP-A 62040 1986 and JP-A
105550 1986.
[0054] 1,1-Bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane and its
preparation are described, for example, in U.S. Pat. No.
4,982,014.
[0055] Indane bisphenols and their preparation are described, for
example, in U.S. Pat. No. 3,288,864, in JP-A 60 035 150 and in U.S.
Pat. No. 4,334,106. Indane bisphenols may be prepared, for example,
from isopropenylphenol or its derivatives or from dimers of
isopropenylphenol or its derivatives in the presence of a
Friedel-Crafts catalyst in organic solvents.
[0056] Polycarbonates may be prepared by known processes. Suitable
processes for the preparation of polycarbonates are, for example,
preparation from bisphenols with phosgene by the interfacial
process or from bisphenols with phosgene by the process in
homogeneous phase, the so-called pyridine process, or from
bisphenols with carbonic acid esters by the melt
transesterification process. These preparation processes are
described, for example, in H. Schnell, "Chemistry and Physics of
Polycarbonates", Polymer Reviews, Volume 9, p. 31-76, Interscience
Publishers, New York, London, Sidney, 1964. The mentioned
preparation processes are also described in D. Freitag, U. Grigo,
P. R. Muller, H. Nouvertne, "Polycarbonates" in Encyclopedia of
Polymer Science and Engineering, Volume 11, Second Edition, 1988,
pages 648 to 718 and in U. Grigo, K. Kircher and P. R. Muller
"Polycarbonate" in Becker, Braun, Kunststoff-Handbuch, Volume 3/1,
Polycarbonate, Polyacetale, Polyester, Celluloseester, Carl Hanser
Verlag Munich, Vienna 1992, pages 117 to 299 and in D. C.
Prevorsek, B. T. Debona and Y. Kesten, Corporate Research Center,
Allied Chemical Corporation, Morristown, New Jersey 07960,
"Synthesis of Poly(estercarbonate) Copolymers" in Journal of
Polymer Science, Polymer Chemistry Edition, Vol. 19, 75-90
(1980).
[0057] The melt transesterification process is described in
particular, for example, in H. Schnell, "Chemistry and Physics of
Polycarbonates", Polymer Reviews, Volume 9, p. 44 to 51,
Interscience Publishers, New York, London, Sidney, 1964 and in DE-A
1 031 512.
[0058] In the preparation of polycarbonate, raw materials and
auxiliary substances having a low degree of impurities are
preferably used. In the case of preparation by the melt
transesterification process in particular, the bisphenols and
carbonic acid derivatives used should be as free as possible of
alkali ions and alkaline earth ions. Such pure raw materials are
obtainable, for example, by recrystallizing, washing or distilling
the carbonic acid derivatives, for example carbonic acid esters,
and the bisphenols.
[0059] The polycarbonates that are suitable according to the
invention have a weight-average molecular weight ( M.sub.w), which
may be determined, for example, by ultracentrifugation or scattered
light measurement, of preferably from 10,000 to 200,000 g/mol.
Particularly preferably, they have a weight-average molecular
weight of from 12,000 to 80,000 g/mol, especially preferably from
20,000 to 35,000 g/mol.
[0060] The molecular weights of the polycarbonates according to the
invention may be adjusted, for example, in known manner by an
appropriate amount of chain terminators. The chain terminators may
be used individually or in the form of a mixture of different chain
terminators.
[0061] Suitable chain terminators are both monophenols and
monocarboxylic acids. Suitable monophenols are, for example,
phenol, p-chlorophenol, p-tert.-butylphenol, cumylphenol or
2,4,6-tribromophenol, as well as long-chained alkylphenols, such
as, for example, 4-(1,1,3,3-tetramethylbutyl)-phenol, or
monoalkylphenols or dialkylphenols having a total of from 8 to 20
carbon atoms in the alkyl substituents, such as, for example,
3,5-di-tert.-butylphenol, p-tert.-octylphenol, p-dodecylphenol,
2-(3,5-dimethyl-heptyl)-phenol or 4-(3,5-dimethyl-heptyl)-phenol.
Suitable monocarboxylic acids are benzoic acid, alkylbenzoic acids
and halobenzoic acids.
[0062] Preferred chain terminators are phenol, p-tert.-butylphenol,
4-(1,1,3,3-tetramethyl-butyl)-phenol and cumylphenol.
[0063] The amount of chain terminators is preferably from 0.25 to
10 mol %, based on the sum of the bisphenols used in a particular
case.
[0064] The polycarbonates that are suitable according to the
invention may be branched in a known manner, preferably by the
incorporation of branching agents having a functionality of three
or more. Suitable branching agents are, for example, those having
three or more phenolic groups or those having three or more
carboxylic acid groups.
[0065] Suitable branching agents are, for example, phloroglucinol,
4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-2-heptene,
4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptane,
1,3,5-tri-(4-hydroxyphenyl)-benzene,
1,1,1-tris-(4-hydroxyphenyl)-ethane,
tri-(4-hydroxyphenyl)-phenylmethane,
2,2-bis-[4,4-bis-(4-hydroxyphenyl)-cyclohexyl]-propane,
2,4-bis-(4-hydroxyphenyl-isopropyl)-phenol,
2,6-bis-(2-hydroxy-5'-methyl-benzyl)-4-methylphenol,
2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)-propane,
hexa-(4-(4-hydroxyphenyl-isopropyl)-phenyl)-terephthalic acid
ester, tetra-(4-hydroxyphenyl)-methane,
tetra-(4-(4-hydroxyphenyl-isopropyl)-phenoxy)-methane and
1,4-bis-(4',4''-dihydroxytriphenyl)-methylbenzene, as well as
2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride,
3,3-bis-(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole,
trimesic acid trichloride and
.alpha.,.alpha.',.alpha.''-tris-(4-hydroxyphenol)-1,3,5-triisopropylbenze-
ne.
[0066] Preferred branching agents are
1,1,1-tris-(4-hydroxyphenyl)-ethane and
3,3-bis-(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole.
[0067] The amount of the branching agents that are optionally to be
used is preferably from 0.05 mol % to 2 mol %, based on moles of
bisphenols used.
[0068] In the case of the preparation of the polycarbonate by the
interfacial process, for example, the branching agents may be
placed in a reaction vessel with the bisphenols and the chain
terminators in the aqueous alkaline phase, or they may be added in
the form of a solution in an organic solvent together with the
carbonic acid derivatives. In the case of the transesterification
process, the branching agents are preferably added together with
the dihydroxy aromatic compounds or bisphenols.
[0069] Catalysts that are preferably to be used in the preparation
of polycarbonate by the melt transesterification process are the
ammonium salts and phosphonium salts known in the literature (see,
for example, U.S. Pat. No. 3,442,864, JP-A-14742/72, U.S. Pat. No.
5,399,659 and DE-A 19 539 290).
[0070] It is also possible to use copolycarbonates.
Copolycarbonates within the scope of the invention are in
particular polydiorganosiloxane-polycarbonate block copolymers
whose weight-average molecular weight ( M.sub.w) is preferably from
10,000 to 200,000 g/mol, particularly preferably from 20,000 to
80,000 g/mol (determined by gel chromatography after prior
calibration by scattered light measurement or ultracentrifugation).
The content of aromatic carbonate structural units in the
polydiorganosiloxane-polycarbonate block copolymers is preferably
from 75 to 97.5 wt. %, particularly preferably from 85 to 97 wt. %.
The content of polydiorganosiloxane structural units in the
polydiorganosiloxane-polycarbonate block copolymers is preferably
from 25 to 2.5 wt. %, particularly preferably from 15 to 3 wt. %.
The polydiorganosiloxane-polycarbonate block copolymers may be
prepared, for example, starting from polydiorganosiloxanes
containing .alpha.,.omega.-bishydroxyaryloxy end groups and having
a mean degree of polymerization of preferably P.sub.n=from 5 to
100, particularly preferably P.sub.n=from 20 to 80. Conventional
additives, such as, for example, mold-release agents may be mixed
with the polycarbonates in the melt or applied to the surface
thereof. The polycarbonates used preferably already contain
mold-release agents prior to compounding with the other components
of the molding compositions according to the invention.
Component C
[0071] According to the invention, the compositions contain as
component C) an impact modifier of glycidyl ester that is a random
copolymer of formula (IV)
##STR00003##
wherein [0072] R.sup.1 is H or C.sub.1- to C.sub.6-alkyl,
preferably H or methyl, [0073] R.sup.2 is alkyl or aryl, preferably
(C.sub.1-C.sub.4)alkyl or (C.sub.6-C.sub.20)aryl, particularly
preferably methyl, ethyl, butyl, [0074] a+b+c=100, [0075] a has a
value of from 50 to 99.5, preferably from 45 to 75, particularly
preferably from 60 to 75, [0076] b has a value of from 0.5 to 25,
preferably from 4 to 16, particularly preferably from 6 to 8, and
[0077] c has a value of from 0 to 50, preferably from 20 to 40,
particularly preferably from 20 to 25.
[0078] The term (C.sub.6-C.sub.20)aryl denotes a hydrocarbon group
that includes one or more unsaturated 6-membered carbon rings and
may optionally be substituted by one or more alkyl groups on one of
the aromatic rings in order to form a substituent group having a
total of from 6 to 20 carbon atoms per group, such as, for example,
phenyl, naphthyl, tolyl, xylyl, mesityl, isopropylphenyl.
Component D
[0079] The composition may additionally contain polymer additives
such as, for example, flameproofing agents (e.g. organophosphates,
silicones or halogenated organic compounds), antidripping agents
(for example compounds of the substance classes of the fluorinated
polyolefins, of the silicones as well as aramid fibers), lubricants
and mold-release agents (for example pentaerythritol
tetrastearate), rubber-elastic polymers, nucleating agents,
antistatics, stabilizers, fillers and reinforcing agents (for
example glass or carbon fibers, mica, talc, wollastonite, kaolin,
CaCO.sub.3 and glass flakes) as well as coloring agents and
pigments. These additives are used in the molding compositions
according to the invention in concentrations of up to 20 wt. %,
preferably from 0.01 to 10 wt. %, particularly preferably from 0.05
to 5 wt. %, especially preferably from 0.1 to 3 wt. %, based on the
total weight of the molding compositions.
[0080] All part by weight data in this application are so
normalized that the sum of the parts by weight of components A) to
C) and optionally D) in the composition is equal to 100.
[0081] The compositions according to the invention may further
comprise as component D) conventional additives, which may be added
generally from 0 up to 15, preferably in an amount of from 0.01 to
10 wt. %, particularly preferably from 0.05 to 5 wt. %, especially
preferably from 0.1 to 3 wt. %, based on the total weight of the
molding compositions.
[0082] All conventional additives are suitable, such as, for
example, stabilizers (for example UV stabilizers, heat
stabilizers), antistatics, flow aids, mold-release agents,
fireproofing additives, emulsifiers, nucleating agents,
plasticizers, lubricants, additives that lower the pH value (e.g.
compounds containing carboxyl groups), additives for increasing
conductivity, coloring agent and pigments. The mentioned additives
and further suitable additives are described, for example, in
Gachter, Muller, Kunststoff-Additive, 3rd Edition, Hanser-Verlag,
Munich, Vienna, 1989. The additives may be used on their own or in
a mixture or in the form of masterbatches. The additives may be
mixed in and/or applied to the surface.
[0083] As stabilizers there may be used, for example, sterically
hindered phenols and/or phosphites, hydroquinones, aromatic
secondary amines, such as diphenylamines, substituted resorcinols,
salicylates, benzotriazoles and benzophenones, as well as variously
substituted representatives of these groups, and mixtures
thereof.
[0084] As nucleating agents there may be used, for example, sodium
phenylphosphinate, aluminium oxide, silicon dioxide and,
preferably, talc and the nucleating agents described
hereinbefore.
[0085] As lubricants and mold-release agents there may be used
ester waxes, pentaerythritol stearate (PETS), long-chained fatty
acids (e.g. stearic acid or behenic acid), salts thereof (e.g. Ca
or Zn stearate) as well as amide derivatives (e.g.
ethylene-bis-stearylamide) or montan waxes (mixtures of
straight-chained, saturated carboxylic acids having chain lengths
of from 28 to 32 carbon atoms) and also low molecular weight
polyethylene or polypropylene waxes.
[0086] As plasticizers there may be used, for example, phthalic
acid dioctyl esters, phthalic acid dibenzyl esters, phthalic acid
butylbenzyl esters, hydrocarbon oils,
N-(n-butyl)benzenesulfonamide.
[0087] In order to obtain conductive molding compositions it is
possible to add carbon blacks, conductive carbon blacks, carbon
fibrils, nano-scale graphite fibers (nanotubes), graphite,
conductive polymers, metal fibers as well as other conventional
additives for increasing conductivity.
[0088] As flameproofing agents there may be used commercially
available organic halogen compounds with synergists, or
commercially available organic nitrogen compounds or
organic/inorganic phosphorus compounds, individually or in a
mixture. Mineral flameproofing additives, such as magnesium
hydroxide or Ca--Mg carbonate hydrates (e.g. DE-A 4 236 122), may
also be used. Examples of halogen-containing, especially brominated
and chlorinated, compounds which may be mentioned include:
ethylene-1,2-bistetrabromophthalimide, epoxidized
tetrabromobisphenol A resin, tetrabromobisphenol A oligocarbonate,
tetrachlorobisphenol A oligocarbonate, pentabromopolyacrylate,
brominated polystyrene. Suitable organic phosphorus compounds are
the phosphorus compounds according to WO-A 98/17720 (PCT/EP/05705),
for example triphenyl phosphate (TPP), resorcinol
bis-(diphenylphosphate), including oligomers, as well as bisphenol
A bis-diphenylphosphate, including oligomers (see e.g. EP-A 363 608
and EP-A 640 655), melamine phosphate, melamine pyrophosphate,
melamine polyphosphate and mixtures thereof. Suitable nitrogen
compounds are in particular melamine and melamine cyanurate. There
are suitable as synergists, for example, antimony compounds, in
particular antimony trioxide and antimony pentoxide, zinc
compounds, tin compounds, such as, for example, tin stannate, and
borates. Carbon formers and tetrafluoroethylene polymers may be
added. The flameproofing agents, optionally with a synergist, such
as antimony compounds, and antidripping agents are generally used
up to an amount of 30 wt. %, preferably 20 wt. % (based on the
composition as a whole).
[0089] There may be present as additives also fillers such as, for
example, talc, mica, silicate, quartz, titanium dioxide,
wollastonite, kaolin, amorphous silicas, magnesium carbonate,
chalk, feldspar, barium sulfate, glass spheres and/or fibrous
fillers and/or reinforcing materials based on carbon fibers and/or
glass fibers. Preference is given to the use of particulate mineral
fillers based on talc, mica, silicate, quartz, titanium dioxide,
wollastonite, kaolin, amorphous silicas, magnesium carbonate,
chalk, feldspar, barium sulfate and/or glass fibers. Particular
preference is given according to the invention to particulate
mineral fillers based on talc, wollastonite and/or glass fibers.
Fillers based on talc are most preferred. The filler and/or
reinforcing material may optionally be surface-modified, for
example with an adhesion promoter or adhesion promoter system, e.g.
based on silane. Pretreatment is not absolutely necessary, however.
In particular when glass fibers are used, it is possible to employ,
in addition to silanes, also polymer dispersions, film formers,
branching agents and/or glass fiber processing aids.
[0090] The compositions obtained by the process according to the
invention may be processed according to conventional processes to
produce article of manufacture including semi-finished products and
moldings of all kinds. Examples of processing processes which may
be mentioned include extrusion processes and injection-molding
processes. Examples of semi-finished products which may be
mentioned are films and sheets.
[0091] Moldings or semi-finished products produced from the molding
compositions/preparations used according to the invention may also
be combined with further materials, such as, for example, metal or
plastics. The molding compositions according to the invention, or
the moldings/semi-finished products produced from the molding
compositions used according to the invention, may, by means of
conventional techniques for connecting and joining a plurality of
components or parts, such as, for example, coextrusion,
injection-molding on the back of films, injection-molding around
inserts, adhesive bonding, welding, screwing or clamping, be used
in conjunction with other materials, or may themselves be used, for
the manufacture of finished articles, such as, for example,
interior fittings for motor vehicles (for example mirror casings,
ventilation grills) or exterior bodywork parts.
[0092] Evaluation of the gloss of the moldings or semi-finished
products produced according to the invention was carried out in
accordance with DIN 67 530 using a reflectometer at an angle of
incidence of 20.degree.. High-gloss within the scope of the
invention means a gloss value of greater than or equal to 90%. The
invention therefore relates also to the use of the process
according to the invention in the production of high-gloss moldings
or semi-finished products.
EXAMPLES
Component A-1
[0093] Linear polybutylene terephthalate powder having a mean
particle size (d.sub.50) of 648 .mu.m and having a melt viscosity
according to DIN 54 811 of 199 Pas at 240.degree. C. and at a shear
rate of 500 s.sup.-1 (Pocan.RTM. B 1300, Lanxess AG, Leverkusen,
Germany).
Component A-2
[0094] Polybutylene terephthalate granules having a melt viscosity
according to DIN 54 811 of 227 Pas at 240.degree. C. and at a shear
rate of 500 s.sup.-1 (Ultradur.RTM. B 2550, BASF AG, Ludwigshafen,
Germany).
Component A-3
[0095] Linear polybutylene terephthalate granules having a melt
viscosity according to DIN 54 811 of 199 Pas at 240.degree. C. and
at a shear rate of 500 s.sup.-1 (Pocan.RTM. B 1300, Lanxess AG,
Leverkusen, Germany).
Component B-1
[0096] Cryo-ground polycarbonate powder having a mean particle size
(d.sub.50) of 632 .mu.m and having a relative solution viscosity of
1.318, measured in dichloromethane as solvent at 25.degree. C. and
in a concentration of 0.5 g/100 ml (Makrolon.RTM. 3108, Bayer
MaterialScience AG, Leverkusen, Germany).
Component B-2
[0097] Polycarbonate granules having a relative solution viscosity
of 1.280, measured in dichloromethane as solvent at 25.degree. C.
and in a concentration of 0.5 g/100 ml (Makrolon.RTM. 2608, Bayer
MaterialScience AG, Leverkusen, Germany).
Components C-1 to C-5
[0098] Glycidyl ester copolymer as impact modifier according to
formula (IV), wherein a, b, c, R.sup.1 and R.sup.2 are as defined
according to Table 1 below.
TABLE-US-00001 TABLE 1 (IV) ##STR00004## Components C-1 to C-5
MVR.sup.*) Compo- Glycidyl ester Manu- [cm.sup.3/ nent polymer
facturer a b c R.sup.1 R.sup.2 10 min] C-1 Lotader.RTM. Arkema 67 8
25 H CH.sub.3 6 AX8900 C-2 Lotryl.RTM. 29MA03 Arkema 71 0 29
CH.sub.3 CH.sub.3 2.8 C-3 Lotryl.RTM. 30BA02 Arkema 71 0 29
CH.sub.3 C.sub.4H.sub.9 2.0 C-4 Elvaloy.RTM. 2715 Dupont 85 0 15
CH.sub.3 C.sub.2H.sub.5 7.0 C-5 Elvaloy.RTM. 3427 Dupont 73 0 27
CH.sub.3 C.sub.2H.sub.5 4.0 .sup.*)Melt volume index at 190.degree.
C. according to ISO 1133 with a load of 2.16 kg.
Component D-1
[0099] Carbon black (Black Pearls.RTM. 800, Cabot Corporation,
Boston, USA).
Component D-2
[0100] Phosphite stabiliser (Irgafos.RTM. 168, Ciba Specialities,
Basel, Switzerland).
[0101] Components D-1 and D-2 are believed to have no criticality
in the context of the inventive process.
[0102] The molding compositions were tested according to the
following methods:
[0103] Izod notched impact strength: Strength according to ISO 180
method 1 U, measured at room temperature.
[0104] The gloss of the flat plastics surfaces was evaluated
according to DIN 67 530 using a reflectometer at an angle of
incidence of 20.degree.. The corresponding measured values are
given in the tables as "20.degree. gloss".
Preparation and Testing of the Molding Compositions According to
the Invention
Step 1: Preparation of the Filled CoPE
[0105] Mixing of the components corresponding to the compositions
according to Table 2 is carried out on a twin-shaft extruder (ZSK25
from Werner und Pfleiderer) at a temperature of the composition of
from 130 to 150.degree. C. Production was carried out at a
throughput of 10 kg/h, without breakage of the extrudate.
TABLE-US-00002 TABLE 2 Preparation of the mixture in the first step
of the inventive process (herein CoPE) CoPE Components (parts by
weight) a b c d e f g h A-1 (powdered polybutylene 50 50 50 50 50
50 60 terephthalate) B-1(powdered polycarbonate 60 C-1(Glycidyl
ester copolymer) 50 37.5 25 25 25 25 40 40 C-2(Glycidyl ester
copolymer) 12.5 25 C-3(Glycidyl ester copolymer) 25 C-4(Glycidyl
ester copolymer) 25 C-5(Glycidyl ester copolymer) 25
Step 2: Preparation of the Molding Compositions According to the
Invention
[0106] Mixing of the components is carried out on a twin-shaft
extruder (ZSK25 from Werner und Pfleiderer) at a temperature of the
composition of from 250.degree. C. to 255.degree. C. and a
throughput of 15 kg/h. The resulting mixture is granulated and
dried.
[0107] The molded articles are produced (unless described
otherwise) on an Arburg 270 E type injection-molding machine at
from 260 to 280.degree. C. and tool temperatures of from 70 to
90.degree. C.
[0108] The composition and properties of the thermoplastic molding
compositions according to the invention are indicated in Table 3.
From the calculation of the total composition of the molding
compositions of Table 3 it follows that the total molding
compositions each contain 20 wt. % A components (A-1 and A-2), 76.4
wt. % B components (B-1 and B-2) and 3.0 wt. % C components (C-1 to
C-5).
TABLE-US-00003 TABLE 3 Compositions and their properties 1 2 3 4 5
6 7 8 Components CoPE a b c d e f g h CoPE 6.0 6.0 6.0 6.0 6.0 6.0
7.5 7.5 (parts by wt.) A-2 17.0 17.0 17.0 17.0 17.0 17.0 15.5 20.0
(parts by wt.) B-1 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 (parts by wt.)
B-2 71.4 71.4 71.4 71.4 71.4 71.4 71.4 66.9 (parts by wt.) D-1 0.4
0.4 0.4 0.4 0.4 0.4 0.4 0.4 (parts by wt.) D-2 0.2 0.2 0.2 0.2 0.2
0.2 0.2 0.2 (parts by wt.) Resulting Composition (calculated) A-1
(wt.-%) 3 3 3 3 3 3 4.5 -- A-2 (wt.-%) 17 17 17 17 17 17 15.5 20
B-1 (wt.-%) 5 5 5 5 5 5 5 9.5 B-2 (wt.-%) 71.4 71.4 71.4 71.4 71.4
71.4 71.4 66.9 C-1 (wt.-%) 3 2.25 1.5 1.5 1.5 1.5 3 3 C-2 (wt-%) --
0.75 1.5 -- -- -- -- -- C-3 (wt.-%) -- -- -- 1.5 -- -- -- -- C-4
(wt.-%) -- -- -- -- 1.5 -- -- -- C-5 (wt.-%) -- -- -- -- -- 1.5 --
-- D-1 (wt.-%) 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 D-2 (wt.-%) 0.2 0.2
0.2 0.2 0.2 0.2 0.2 0.2 Properties Izod notched 63.6 62.2 60.0 58.5
55.1 58.4 64.7 59.5 impact strength (kJ/m.sup.2) 20.degree. gloss
(%) 92.7 97.4 99.2 94.3 95.9 99.1 92.5 94.6
Comparison Examples
Preparation and Testing of Molding Compositions not According to
the Invention
Step 1: Preparation of CoPE
[0109] For the preparation of a pre-compound from PBT in granular
form and the glycidyl ester copolymer corresponding to the
compositions according to Table 4, mixing of the components is
carried out on a twin-shaft extruder (ZSK25 from Werner und
Pfleiderer) at a temperature of the composition of from 216.degree.
C. to 220.degree. C. Production was carried out at a throughput of
15 kg/h, without breakage of the extrudate.
TABLE-US-00004 TABLE 4 pre-compound compositions (comparison
examples) CoPE Components I j (parts by weight) (comparison)
(comparison) A-2 (PBT granules) 69.5 84.5 C-1 30.0 15.0 D-1 0.2 0.2
D-2 0.3 0.3
Step 2: Preparation of the Molding Compositions not According to
the Invention (Comparison Examples)
[0110] Mixing of the components is carried out on a twin-shaft
extruder (ZSK25 from Werner und Pfleiderer) at a temperature of the
composition of from 250.degree. C. to 257.degree. C. and a
throughput of 15 kg/h. The resulting mixture is granulated and
dried. The molded bodies are produced (unless described otherwise)
on an Arburg 270 E type injection molding-machine at from 260 to
280.degree. C. and tool temperatures of from 70 to 90.degree.
C.
[0111] The composition and properties of the thermoplastic molding
compositions that are not according to the invention are indicated
in Table 5. From the calculation of the total composition of the
molding compositions of Table 5 it follows that these molding
compositions each contain approx. 17 wt. % A components, 79.5 wt. %
B components, 3.0 wt. % C components and 0.55 wt. % and 0.6 wt.-%,
respectively, D components.
TABLE-US-00005 TABLE 5 Compositions and their properties
(comparison examples) 9 10 (comparison) (comparison) CoPE
Components i j CoPE (parts by wt.) 10 20 A-3 (parts by wt.) 10 --
B-1 (parts by wt.) 5.0 5.0 B-2 (parts by wt.) 74.5 74.5 D-1 (parts
by wt.) 0.2 0.2 D-2 (parts by wt.) 0.3 0.3 A1-A3 (total, %) 17.0
17.0 B1-B2 (total, %) 79.5 79.5 C1-C5 (total, %) 3.0 3.0 D1 (total,
%) 0.2 0.2 D2 (total, %) 0.3 0.3 Resulting composition (calculated)
A-2 (wt.-%) 6.95 16.90 A-3 (wt.-%) 10 -- B-1 (wt.-%) 5 5 B-2
(wt.-%) 74.5 74.5 C-1 (wt.-%) 3 3 D-1 (wt.-%) 0.22 0.24 D-2 (wt.-%)
0.33 0.36 Properties Izod notched impact strength (kJ/m.sup.2) 67.2
66.1 20.degree. gloss (%) 90.0 87.1
[0112] The process for the production of Comparison Examples 9 and
10 leads to moldings which have lower gloss (see Table 5) than the
process according to the invention for the production of Examples 1
to 8 (see Table 3).
[0113] By means of the process according to the invention it is
possible to incorporate the glycidyl ester copolymer (component C)
very efficiently into the polyalkylene terephthalate or
polycarbonate in amounts even over 30 wt. %. As is demonstrated in
Table 2 by the filled glycidyl ester copolymers CoPE-a to CoPe-h
according to the invention, it is possible using the process
according to the invention to prepare and process even mixtures
having a content of 40 or 50 wt. % glycidyl ester copolymer without
negative effects on the gloss of the resulting moldings (see Table
3).
[0114] If, on the other hand, mixing of the glycidyl ester
copolymer (component C) with polyalkylene terephthalate takes place
in the first step in the melt according to conventional compounding
methods, a concentration of over 30 wt. % in the overall
composition of the molding cannot be achieved, because as the
content of glycidyl ester copolymer increases, the extruded melt
becomes unstable to segregation (phase separation) before the solid
state of aggregation is reached. A further disadvantage of mixing
in the melt (process according to the comparison examples) is that,
in the melt, the end groups of the polyalkylene terephthalate are
able to react with epoxy groups of the glycidyl ester copolymer,
resulting in the formation of large, not readily dispersible
particles which, after further processing, reduce the gloss of the
resulting molding.
[0115] Although the invention has been described in detail in the
foregoing for the purpose of illustration, it is to be understood
that such detail is solely for that purpose and that variations may
be made therein by those skilled in the art without departing from
the spirit and scope of the invention except as it may be limited
by the claims.
* * * * *