U.S. patent application number 10/689239 was filed with the patent office on 2005-04-21 for modified weatherable polyester molding composition.
This patent application is currently assigned to General Electric Company. Invention is credited to Kim, Sung Dug.
Application Number | 20050085589 10/689239 |
Document ID | / |
Family ID | 34435439 |
Filed Date | 2005-04-21 |
United States Patent
Application |
20050085589 |
Kind Code |
A1 |
Kim, Sung Dug |
April 21, 2005 |
Modified weatherable polyester molding composition
Abstract
A flame retarded resin molding composition with weatherable
properties comprises a polyester and polycarbonate blend modified
with an organopolysiloxane polycarbonate and an acrylic impact
modifier for enhancing weatherablity.
Inventors: |
Kim, Sung Dug; (Evansville,
IN) |
Correspondence
Address: |
Robert E. Walter
GE Plastics
One Plastics Avenue
Pittsfield
MA
01201
US
|
Assignee: |
General Electric Company
|
Family ID: |
34435439 |
Appl. No.: |
10/689239 |
Filed: |
October 20, 2003 |
Current U.S.
Class: |
525/67 ; 252/609;
525/437; 525/461; 525/474 |
Current CPC
Class: |
C08L 67/02 20130101;
C08L 69/00 20130101; C08L 69/00 20130101; C08L 67/02 20130101; C08K
5/13 20130101; C08L 2666/02 20130101; C08L 51/00 20130101; C08K
5/13 20130101; C08L 83/10 20130101; C08L 2666/02 20130101; C08L
83/10 20130101; C08L 69/00 20130101 |
Class at
Publication: |
525/067 ;
525/437; 525/461; 525/474; 252/609 |
International
Class: |
C08L 051/00; C08L
067/00; C08L 069/00 |
Claims
1. A modified flame retarded resin molding composition with
enhanced weatherable properties comprising a polyester and
polycarbonate blend with an organopolysiloxane-polycarbonate and a
acrylic impact modifier for enhancing weatherablity and a flame
retarding amount of a halogenated flame retardant.
2. A flame retarded resin molding composition according to claim 1
wherein the acrylic rubber has a particle size of from 300 to 800
nm.
3. A flame retarded resin molding composition according to claim 1
wherein said acrylic core shell rubber comprises a multi-phase
composite interpolymer comprising about 25 to 95 weight percent of
a first acrylic elastomeric phase polymerized from a monomer system
comprising about 75 to 99.8% by weight C.sub.1 to C.sub.14 alkyl
acrylate, 0.1 to 5% by weight cross linking member, 0.1 to 5% by
weight graft linking monomer, said cross linking monomer being a
polyethylenically unsaturated monomer having a plurality of
addition polymerizable reactive groups and about 75 to 5 weight
percent of a final, rigid thermoplastic acrylic or methacrylic
phase polymerized in the presence of said elastomer.
4. A flame retarded resin molding composition according to claim 1
wherein said acrylic core shell rubber comprises a multi-phase
composite interpolymer comprising about 25 to 95 weight percent of
a first acrylic elastomeric phase polymerized from a monomer system
comprising about 75 to 99.8%, by weight C.sub.1 to C.sub.14 alkyl
acrylate, 0.1 to 5% by weight cross linking member, 0.1 to 5%, by
weight graft linking monomer, said cross linking monomer being a
polyethylenically unsaturated monomer having a plurality of
addition polymerizable reactive groups and about 75 to 5 weight
percent of a final, rigid thermoplastic acrylic or methacrylic
phase polymerized in the presence of said elastomer.
5. A flame retarded resin molding composition according to claim 1
wherein said acrylic core shell rubber comprises a multi-phase
composite interpolymer comprising about 25 to 95 weight percent of
a first elastomeric phase polymerized from a monomer system
comprising about 5-50% polydimethylsiloxane, 30 to 99.8% by weight
C.sub.1 to C.sub.14 alkyl acrylate, 0.1 to 5% by weight cross
linking member, 0.1 to 5% by weight graft linking monomer, said
cross linking monomer being a polyethylenically unsaturated monomer
having a plurality of addition polymerizable reactive groups and
about 75 to 5 weight percent of a final, rigid thermoplastic
acrylic or methacrylic phase polymerized in the presence of said
elastomer.
6. A flame retarded resin molding composition according to claim 1
wherein said organopolysiloxane-polycarbonate copolymer comprises
organopolysiloxane blocks having repeating units of the general
formula: 8
7. wherein R' is a member selected from the class of monovalent
hydrocarbon radicals, halogenated monovalent hydrocarbon radicals
and cyanoalkyl radicals; E is independently selected from the group
consisting of hydrogen, lower alkyl, alkoxy radicals, aryl, and
alkylaryl, halogen radicals and mixtures thereof, and R" is a
divalent hydrocarbon radical, and n is from about 10 to about
120.
8. A flame retarded resin molding composition according to claim 2
wherein said organopolysiloxane-polycarbonate copolymer comprises
polycarbonate blocks having repeating units of the general
formulae: 9and D is a divalent hydrocarbon radical containing from
1-15 carbon atoms; --S--, --SO--, --S(O).sub.2; --O--.
9. A flame retarded resin molding composition according to claim 3
wherein said organopolysiloxane-polycarbonate copolymer comprises
polycarbonate blocks having repeating units of the general
formulae: 10wherein R is a member selected from the class of
hydrogen, cycloaliphatic, aryl, monovalent hydrocarbon radicals,
aryl or alkyaryl.
10. A flame retarded resin molding composition according to claim 1
wherein said organopolysiloxane-polycarbonate copolymer comprises
organopolysiloxane blocks having repeating units of the general
formulae: 11
11. A flame retarded resin molding compositions according to claim
5 wherein E is independently selected from the group consisting of
hydrogen, alkyl of 1 to 6 carbon atoms, and halogen.
12. A flame retarded resin molding compositions according to claim
1 wherein said acrylic impact modifier comprises first repeating
units derived one or more glycidyl ester monomers and second
repeating units derived from one or more x-olefin monomers.
13. A flame retarded resin molding compositions according to claim
1 wherein said polyester is derived from an aliphatic diol and an
aromatic dicarboxylic acid having repeating units of the following
general formula: 12wherein each A is independently a divalent
aliphatic, salicylic or aromatic hydrocarbon or polyoxyalkylene
radical, or mixtures thereof and each B is independently a divalent
aliphatic, salicylic or aromatic radical, or mixtures thereof.
14. A flame retarded resin molding compositions according to claim
1 wherein comprises an aromatic polycarbonate resin comprises one
or more resins selected from linear aromatic polycarbonate resins,
branched aromatic polycarbonate resins and poly(ester-carbonate)
resins.
15. A flame retarded resin molding compositions according to claim
1 wherein said polycarbonate comprises a linear aromatic
polycarbonate resin.
16. flame retarded resin molding compositions according to claim 1
wherein said polycarbonate comprises a poly(ester carbonate).
17. A flame retarded resin molding compositions according to claim
1 wherein the resin comprises from 20 to 80 parts by weight of the
polycarbonate resin; from 20 to 80 parts by weight of the polyester
resin; from 5 to 30 parts by weight of the
organopolysiloxane-polycarbona- te block copolymer; and from 1 to
10 parts by weight of the glycidyl ester impact modifier, each
based on 100 parts by weight of the blend.
18. A flame retarded resin molding compositions according to claim
1 wherein the resin comprises from 25 to 55 parts by weight, of the
polycarbonate resin; from 25 to 55 parts by weight of the polyester
resin; from 10 to 20 parts by weight of the
organopolysiloxane-polycarbon- ate block copolymer; and from 2 to 8
parts by weight of the acrylic impact modifier, each based on 100
parts by weight of the blend.
19. A flame retarded resin molding composition according to claim 1
wherein said flame retardant is a halogenated epoxy,
poly(haloarylmethacrylate), halogenated polystyrene or a
poly(haloarylacrylate) flame retardant.
20. A flame retarded resin molding composition according to claim 1
wherein said flame retardant is a polybromobenzylacrylate flame
retardant
21. An article molded from the composition of claim 1.
22. A molded article according to claim 18 comprising an injection
molded article.
23. A molded article according to claim 18 comprising an
enclosures.
24. A molded article according to claim 20 for use in an electrical
communication device.
25. A molded article according to claim 21 comprising a cable
connector, telephone, computer, video, and network interface
devices for residential, commercial or industrial use.
Description
FIELD OF THE INVENTION
[0001] The field is directed to modified thermoplastic resin
compositions, and, more particularly, to weatherable and impact
modified compositions containing a blend of a polyester resin and a
polycarbonate resin.
BACKGROUND OF THE INVENTION
[0002] Moldable thermoplastic polyester crystalline resin blends
offer a high degree of surface hardness, solvent resistance and
abrasion resistance, high gloss, and low surface friction. However,
loss of impact strength when subjected to ultra violet radiation
may limit the usefulness of polyester crystalline resin blends for
outdoor applications where molded articles made from the polyester
will be exposed to sun and hot wet conditions.
[0003] Often a rubbery modifier is added to polyesters to improve
impact strength. For example, improved impact strength is obtained
by melt compounding polybutylene terephthalate with ethylene homo-
and copolymers functionalized with either acid or ester moieties as
taught in U.S. Pat. Nos. 3,405,198; 3,769,260; 4,327,764; and
4,364,280. Polyblends of polybutylene terephthalate with a styrene
alpha-olefin-styrene triblock are taught in U.S. Pat. No.
4,119,607. U.S. Pat. No. 4,172,859 teaches impact modification of
polybutylene terephthalate with random ethylene-acrylate copolymers
and EPDM rubbers grafted with a monomeric ester or acid
functionality.
[0004] Although articles molded from impact-modified polyester
resin/polycarbonate resin blends typically provide good impact
performance, the weatherability of the such articles may be
deficient in some applications where it is desired to retain the
impact resistance after long term UV exposure. Hence, it is
desirable to provide a molding composition having a combination of
flame resistance, impact resistance with enhanced
weatherability.
[0005] U.S. Pat. No. 4,161,469 describes a polymer blend comprising
a polyalkyl terephthalate resin and organosiloxane-polycarbonate
block copolymer having improved impact and heat distortion
properties. U.S. Pat. No. 4,794,141 describes
polysiloxane/polycarbonate block copolymers, elastomeric polymers,
and polyalkylene terephthalates. The elastomeric polymer is
described as a hydrogenated block copolymer of a vinyl aromatic
monomer and a conjugated diene. U.S. Pat. No. 5,380,795 describes a
polymer mixture comprising all aromatic polycarbonate, a
styrene-containing copolymer and/or graft polymer, and a
polysiloxane-polycarbonate block copolymer, and articles formed
therefrom. However, these patents do not describe flame-retarded
blend and do not address question of weatherability of the
blends.
[0006] U.S. Pat. No. 4,155,898 describes a polymer blend comprising
a polyalkylene terephthalate, an organopolysiloxane-polycarbonate
block copolymer, and a halogenated copolycarbonate having impact,
heat distortion and flame retardant properties.
[0007] U.S. Pat. No. 5,981,661 describes a flame retarded molding
compositions with enhanced weatherable properties, which comprise a
polyester and polycarbonate blend with
organopolysiloxane-polycarbonate block copolymer and a glycidyl
ester impact modifier. However, high amount of gycidyl impact
modifier could cause undesirable viscosity increase through the
reaction between glycidyl groups in the impact modifier and
carboxyl groups in polyesters. In addition, gycidyl impact modifier
is less effective impact modifiers than core-shell type rubbers.
Accordingly, there is a need for enhancing the impact and
processibility, as well as the retention of impact and color upon
long term UV exposure. The present invention demonstrates good
weatherable polyester crystalline resin blends with flame retardant
for outdoors application.
SUMMARY OF THE INVENTION
[0008] According to an embodiment, a flame-retarded resin molding
compositions with weatherable properties comprise a polyester and
polycarbonate blend modified with an
organopolysiloxane-polycarbonate and an acrylic impact modifier for
enhancing weatherability.
[0009] According to other embodiments, additional ingredients may
include a flame retarding amount of a halogenated flame retardant,
a mineral filler, and other ingredients such as quenchers, flame
retardant synergist, and anti-drip additives.
[0010] According to an embodiment, a thermoplastic resin comprises
polycarbonate, an alkylene aryl polyester, an
organopolysiloxane-polycarb- onate, and a core-shell impact
modifier for enhancing heat resistance having a shell derived from
an alkylacrylate and a rubbery acrylate core derived from an
acrylate having 4 to 12 carbon atoms and the core may have silicone
copolymers.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0011] Polycarbonate Resin Component
[0012] Aromatic polycarbonate resins suitable for use in the
present invention, methods of making polycarbonate resins and the
use of polycarbonate resins in thermoplastic molding compounds are
well known in the art, see, generally, U.S. Pat. Nos. 3,169,121,
4,487,896 and 5,411,999, the respective disclosures of which are
each incorporated herein by reference.
[0013] Aromatic polycarbonate resins are, in general, prepared by
reacting a dihydric phenol, e.g., 2,2-bis-(4-hydroxyphenyl)propane
("bisphenol A"), 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane,
bis(2-hydroxyphenyl)methane, 2,6-dihydroxy naphthalene,
hydroquinone, 2,4'-dihydroxyphenyl sulfone and
4,4'-dihydroxy-3,3-dichlorophenyl ether, with a carbonate
precursor, e.g., carbonyl bromide and carbonyl chloride, a halogen
formate, a bishaloformate of a dihydric phenol or a carbonate
ester, e.g., diphenyl carbonate, dichlorophenyl carbonate,
dinaphthyl carbonate, phenyl tolyl carbonate and ditolyl
carbonate.
[0014] In a preferred embodiment, the aromatic polycarbonate resin
comprises one or more resins selected from linear aromatic
polycarbonate resins, branched aromatic polycarbonate resins and
poly(ester-carbonate) resins.
[0015] Suitable linear aromatic polycarbonates resins include,
e.g., bisphenol A polycarbonate resin.
[0016] Suitable branched aromatic polycarbonates are made, e.g., by
reacting a polyfunctional aromatic compound, e.g., trimellitic
anhydride, trimellitic acid, trimesic acid, trihydroxy phenyl
ethane or trimellityl trichloride, with a dihydric phenol and a
carbonate precursor to form a branching polymer.
[0017] Suitable poly(ester-carbonate) copolymers are made, e.g., by
reacting a difunctional carboxylic acid, terephthalic acid,
isophthalic acid, 2,6-naphthalic acid, or mixtures of acids, or a
derivative of a difunctional carboxylic acid, e.g., an acid
chloride, with a dihydric phenol and a carbonate precursor.
[0018] In a preferred embodiment, the polycarbonate resin has an
intrinsic viscosity of about 0.3 to about 1.5 deciliters per gram
in methylene chloride at 25.degree. C.
[0019] In a preferred embodiment, the polycarbonate resin is a
linear polycarbonate resin that is derived from bisphenol A and
phosgene. In an alternative preferred embodiment, the polycarbonate
resin is a blend of two or more polycarbonate resins.
[0020] Suitable aromatic polycarbonate resins are commercially
available, e.g., LEXAN.TM. bisphenol A-type polycarbonate resins
from (General Electric Company.
[0021] Polyester
[0022] The term alkylene aryl polyester refers to crystalline
thermoplastic polyesters such as polyesters derived from an
aliphatic or cycloaliphatic diols, or mixtures thereof, containing
from 2 to about 10 carbon atoms and at least one aromatic
dicarboxylic acid. Preferred polyesters are derived from an
aliphatic diol and an aromatic dicarboxylic acid having repeating
units of the following general formula: 1
[0023] wherein n is an integer of from 2 to 6, R is a
C.sub.1-C.sub.20 aryl radical comprising a decarboxylated residue
derived from an aromatic dicarboxylic acid.
[0024] Examples of aromatic dicarboxylic acids represented by the
decarboxylated residue R are isophthalic or terephthalic acid,
1,2-di(p-carboxyphenyl)ethane, 4,4'-dicarboxydiphenyl ether, 4,4'
bisbenzoic acid and mixtures thereof. All of these acids contain at
least one aromatic nucleus. Acids containing fused rings can also
be present, such as in 1,4-1, 5 or 2,6-naphthalenedicarboxylic
acids. The preferred dicarboxylic acids are terephthalic acid,
isophthalic acid, naphthalene dicarboxylic acid or mixtures
thereof.
[0025] The most preferred polyesters are poly(ethylene
terephthalate) ("PET"), and poly(1,4-butylene terephthalate),
("PBT"), poly(ethylene naphthanoate) ("PEN"), poly(butylene
naphthanoate), ("PBN") poly(propylene terephthalate) ("PPT") and
poly(cyclohexane dimethanol terephthalate), (PCT).
[0026] Also contemplated herein are the above polyesters with minor
amounts, e.g., from about 0.5 to about 5 percent by weight, of
units derived from aliphatic acid and/or aliphatic polyols to form
copolyesters. The aliphatic polyols include glycols, such as
poly(ethylene glycol). Such polyesters can be made following the
teachings of, for example, U.S. Pat. Nos. 2,465,319 and
3,047,539.
[0027] The preferred poly(1,4-butylene terephthalate) resin used in
this invention is one obtained by polymerizing a glycol component
at least 70 mol %, preferably at least 80 mol %, of which consists
of tetramethylene glycol and an acid component at least 70 mol %,
preferably at least 80 mol %, of which consists of terephthalic
acid, or polyester-forming derivatives therefore.
[0028] The polyesters used herein have an intrinsic viscosity of
from about 0.4 to about 2.0 dl/g as measured in a 60:40
phenol/tetrachloroethane mixture or similar solvent at
23.degree.-30.degree. C. VALOX 315 polyester is particularly
suitable for this invention having an intrinsic viscosity of 1.1 to
1.4 dl/g.
[0029] A mixture of polyester resins with differing viscosities may
be used to make a blend mixture to allow for better control of the
viscosity of the final formulation.
[0030] Blends of polyesters may also be employed in the
composition. As indicated earlier, preferred polyester blends are
made from poly(ethylene terephthalate) and poly(1,4-butylene
terephthalate).
[0031] Acrylic Impact Modifier
[0032] The composition comprises an impact modifier, preferably a
core-shell polymers built up from a rubber-like core on which one
or more shells have been grafted. Typical core material consists
substantially of in acrylate rubber. Preferable the core is an
acrylate rubber of derived from a C4 to C12 acrylate. Typically,
one or more shells are grafted on the core. Usually these shells
are built up for the greater part from a vinyl aromatic compound
and/or a vinyl cyanide and/or an alkyl(meth)acrylate and/or
(meth)acrylic acid. Preferable the shell is derived from an
alkyl(meth)acrylate, more preferable a methyl(meth)acrylate. The
core and/or the shell(s) often comprise multi-functional compounds
that may act as a crosslinking agent and/or as a grafting agent.
These polymers are usually prepared in several stages. The
preparation of core-shell polymers and their use as impact
modifiers in combination with polycarbonate are described in U.S.
Pat. Nos. 3,864,428 and 4,264,487. Especially preferred grafted
polymers are the core-shell polymers available from Rohm & Haas
under the trade name PARALOID.RTM., including, for example,
PARALOID.RTM. EXL3330 and EXL2300.
[0033] In another aspect of the invention the acrylic core shell
rubber comprises a multi-phase composite interpolymer comprising
about 25 to 95 weight percent of a first acrylic elastomeric phase
polymerized from a monomer system comprising about 75 to 99.8% by
weight C.sub.1 to C.sub.14 alkyl acrylate, 0.1 to 5%, by weight
cross linking member, 0.1 to 5% by weight graft linking monomer,
said cross linking monomer being a polyethylenically unsaturated
monomer having a plurality of addition polymerizable reactive
groups and about 75 to 5 weight percent of a final, rigid
thermoplastic acrylic or methacrylic phase polymerized in the
presence of said elastomer.
[0034] Preferred impact modifiers include core-shell impact
modifiers, such as those having a core of poly(butyl acrylate) and
a shell of poly(methyl methacrylate).
[0035] In other embodiments suitable impact modifiers comprise
those that are core shell type impact modifiers including shell
comprising poly(methyl methacrylate) and core comprising a silicone
rubber and at least one poly(alkylacrylate). In a particular
embodiment a suitable impact modifier is core-shell type impact
modifies including shell comprising poly(methyl methacrylate) and
core comprising a silicone rubber and at least one
poly(butylacrylate). One type of suitable core-shell impact
modifier can be prepared in accordance with the method described in
U.S. Pat. No. 5,132,359. In some embodiments suitable impact
modifiers include those sold under the trade name Metablend by
Mitsubishi Rayon Co. Ltd.
[0036] A useful amount of impact modifier is about 1 to about 30
weight percent, preferably about 5 to about 15 weight percent, more
preferably about 6 to about 12 weight percent, wherein the weight
percentages are based on the entire weight of the composition.
[0037] Core shell acrylic rubbers can be of various particle sizes.
The preferred range is from 300-800 nm, however larger particles,
or mixtures of small and large particles, may also be used. In some
instances, especially where good appearance is required acrylic
rubber with a particle size of 350-450 nm may be preferred. In
other applications where higher impact is desired acrylic rubber
particle sizes of 450-550 nm or 650-750 nm may be employed.
[0038] The Siloxane-Copolycarbonate Block Copolymer
[0039] Preferred polysiloxane-polycarbonate block copolymers are
set forth in copending application Ser. No. 08/062,485 entitled
Polymer blends of Polycarbonate-Polysiloxane block Copolymers with
Polycarbonate and Polyestercarbonate Copolymers by Hoover (Our Case
8CL-7015). The blend comprises a polysiloxane from recurring
polysiloxane blocks of the formula: 2
[0040] The polycarbonate-block comprises units of the formula:
3
[0041] with the preferred polycarbonate-block comprises units of
the formula: 4
[0042] The resulting organopolysiloxane-polycarbonate block
copolymer includes organopolysiloxane-polycarbonate blocks having
repeating units of the general formula: 5
[0043] In the above formulae, R' is a member selected from the
class of monovalent hydrocarbon radicals, halogenated monovalent
hydrocarbon radicals and cyanoalkyl radicals; E is a member
independently selected from the class of hydrogen, lower alkyl,
alkoxy radicals, aryl, and alkylaryl, halogen radicals and mixtures
thereof, preferably hydrogen or alkoxy and when alkoxy, preferably
methoxy; R" is a divalent hydrocarbon radical, preferably an
alkylene radical of from 1 to 6 carbon atoms with C.sub.3 being
most preferred, and n is from about 10 to about 120, preferably
from about 40 to about 60.
[0044] A is a divalent hydrocarbon radical containing from 1-15
carbon atoms; --S--, --SO--, --S(O).sub.2; --O--. Preferably D is a
divalent hydrocarbon radial. In the case where A is --C(R).sub.2--,
R is a member selected from the class of hydrogen, cycloaliphatic,
aryl, monovalent hydrocarbon radicals, aryl or alkyaryl, preferably
R is alkyl, preferably C.sub.1-C.sub.6 alkyl, and more preferably
methyl.
[0045] Preferred polysiloxane-polycarbonate block copolymers are
set forth in copending application Ser. No. 08/062,485, comprise
from about 1 to about 50 percent by weight of siloxane. Pages 2-14
of the above mentioned application are incorporated into the
present specification by reference. These pages relate to the
preferred polycarbonate-polysiloxane blocks of utilized in the
present invention. Additional preferred embodiments are set forth
in Ser. No. 08/668,445 to Hoover et al entitled Terpolymer Having
Aromatic Polyester, Polysiloxane and Polycarbonate Segments, (Our
Case 8CL-7001) which pages 3-14 is incorporated into the present
specification by reference.
[0046] Other illustrative organopolysiloxane block copolymers are
set forth in U.S. Pat. No. 4,161,498 to Bopp which describes
polysiloxane blocks of the following general formulae: 6
[0047] A organopolysiloxane-polycarbonate block copolymer of Bopp
is represented by the following formula comprising
organopolysiloxane-polyca- rbonate blocks having repeating units of
the general formula: 7
[0048] where X is an integer equal to 1 to 1000, inclusive,
preferably 2 to 100, Z is equal to 1, n is a number average equal
to 1 to 100, inclusive, preferably 5 to 40, a is a number average
equal to 1.1 to 100, m is equal to 1, and Z is an integer equal to
1 to 1000, inclusive, preferably 5 to 12. E, R, and R' being as
defined hereinafter.
[0049] Included within the radicals represented by R aryl radicals
and halogenated aryl radicals such as phenyl, chlorophenyl, xylyl,
tolyl, etc.; aralkyl radicals such as phenylethyl, benzyl, etc.;
aliphatic, haloaliphatic and cycloaliphatic radicals such as alkyl,
cycloalkyl, haloalkyl including methyl, ethyl propyl, chlorobutyl,
cyclohexyl, etc.; R can be all the same radical or any two or more
of the aforementioned radicals, while R is preferably methyl, R'
includes all radicals included by R above except hydrogen, where R'
also can be all the same radical or any two or more of the
aforementioned R radicals except hydrogen and R' is preferably
methyl. R' also includes, in addition to all the radicals included
by R, except hydrogen, cyanoalkyl radicals such as cyanoethyl,
cyanobutyl, etc. radicals. Radicals that are included within the
definition of E are hydrogen, methyl, ethyl, propyl, chloro, bromo,
etc. and combinations thereof, and E is preferably hydrogen.
[0050] The organopolysiloxane-polycarbonate block copolymers can be
made by any technique known to those skilled in the art including
the techniques described by Merritt, Merritt, Jr., et al., and
Vaughn Jr. in the U.S. patents referenced in the description of the
prior art hereinbefore.
[0051] Accordingly, all of the procedures described in the
aforesaid patents relating to methods for the preparation of the
organopolysiloxane-polycarbonate block copolymers are incorporated
herein in their entirety by reference.
[0052] Illustratively presently preferred
organopolysiloxane-polycarbonate block copolymers contain repeating
units of above Formula, set out herein before wherein X, Y, Z, a, n
and m are as defined hereafter: Resin Type "A"; X equals about 7; Y
equals about 8 to 10; Z equals about 1; a equals about 2; n equals
about 10; m equals about 1. Resin Type "B"; X equals about 10; Y
equals about 8 to 10; Z equals about 1; a equals about 2; n equals
about 20; m equals about 1. Resin Type "C"; X equals about 5; Y
equals about 8 to 10; Z equals about 1; a equals about 2; n equals
about 20; m equals about 1.
[0053] Flame Retardant
[0054] Flame-retardant additives are desirably present in an amount
at least sufficient to reduce the flammability of the polyester
resin, preferably to a UL94 V-0 rating. The amount will vary with
the nature of the resin and with the efficiency of the additive. In
general, however, the amount of additive ill be from 2 to 30
percent by weight based on the weight of resin. A preferred range
will be from about 8 to 20 percent.
[0055] Typically halogenated aromatic flame-retardants include
tetrabromobisphenol A polycarbonate oligomer, polybromophenyl
ether, brominated polystyrene, brominated BPA polyepoxide,
brominated imides, brominated polycarbonate, poly (haloaryl
acrylate), poly(haloaryl methacrylate), or mixtures thereof.
[0056] Examples of other suitable flame retardants are brominated
polystyrenes such as polydibromostyrene and polytribromostyrene,
decabromobiphenyl ethane, tetrabromobiphenyl, brominated alpha,
omega-alkylene-bis-phthalimides, e.g.
N,N'-ethylene-bis-tetrabromophthali- mide, oligomeric brominated
carbonates, especially carbonates derived from tetrabromobisphenol
A, which, if desired, are end-capped with phenoxy radicals, or with
brominated phenoxy radicals, or brominated epoxy resins.
[0057] The flame-retardants are typically used with a synergist,
particularly inorganic antimony compounds. Such compounds are
widely available or can be made in known ways. Typical, inorganic
synergist compounds include Sb.sub.2O.sub.5, SbS.sub.3, sodium
antimonite and the like. Especially preferred is antimony trioxide
(Sb.sub.2O.sub.3). Synergists, such as antimony oxides, are
typically used at about 0.5 to 15 by weight based on the weight
percent of resin in the final composition.
[0058] Fillers
[0059] Additionally, it may be desired to employ inorganic fillers
to the thermoplastic resin provided the favorable properties are
not deleteriously affected. Typical inorganic fillers include:
alumina, amorphous silica, anhydrous alumino silicates, mica,
wollastonite, clays, talc, metal oxides such as titanium dioxide,
zinc sulfide, ground quartz, and the like. Low levels (0.1-10.0 wt.
%) of very small particle size (largest particles less than 10
microns in diameter) are preferred.
[0060] Fiber Additives
[0061] The polyester resins of the invention may be further blended
with reinforcements, fillers and colorants.
[0062] Reinforcing fiber and fillers may comprise from about 5 to
about 50 weight percent of the composition, preferably from about
10 to about 35 weight percent based on the total weight of the
composition. The preferred reinforcing fibers are glass, ceramic
and carbon and are generally well known in the art, as are their
methods of manufacture.
[0063] In one embodiment, glass is preferred, especially glass that
is relatively soda free. Fibrous glass filaments comprised of
lime-alumino-borosilicate glass, which is also known as "E" glass
are often especially preferred. Glass fiber is added to the
composition to greatly increase the flexural modulus and strength,
albeit making the product more brittle. The glass filaments can be
made by standard processes, e.g., by steam or air blowing, flame
blowing and mechanical pulling. The preferred filaments for plastic
reinforcement are made by mechanical pulling. For achieving optimal
mechanical properties fiber diameter between 6-20 microns are
required with a diameter of from 10-15 microns being preferred. In
preparing the molding compositions it is convenient to use the
fiber in the form of chopped strands of from about 1/8" to about
1/2" long although roving may also be used. In articles molded from
the compositions, the fiber length is typically shorter presumably
due to fiber fragmentation during compounding of the composition.
The fibers may be treated with a variety of coupling agents to
improve adhesion to the resin matrix. Preferred coupling agents
include; amino, epoxy, amide or mercapto functionalized silanes.
Organo metallic coupling agents, for example, titanium or zirconium
based organo metallic compounds, may also be used.
[0064] Other preferred sizing-coated glass fibers are commercially
available from Owens Corning Fiberglass as, for example, OCF K
filament class fiber 183F.
[0065] Other fillers and reinforcing agents may be used in alone or
in combination with reinforcing fibers. These include but are not
limited to: carbon fibrils, mica, talc, barite, calcium carbonate,
wollastonite, milled glass, flaked glass, ground quartz, silica,
zeolites, and solid or hollow glass beads or spheres.
[0066] The glass fibers may be blended first with the aromatic
polyester and then fed to an extruder and the extrudate cut into
pellets, or, in a preferred embodiment, they may be separately fed
to the feed hopper of an extruder. In a highly preferred
embodiment, the glass fibers may be fed downstream in the extruder
to minimize attrition of the glass. Generally, for preparing
pellets of the composition set forth herein, the extruder is
maintained at a temperature of approximately 480.degree. F. to
550.degree. F. The pellets so prepared when cutting the extrudate
may be one-fourth inch long or less. As stated previously, such
pellets contain finely divided uniformly dispersed glass fibers in
the composition. The dispersed glass fibers are reduced in length
as a result of the shearing action on the chopped glass strands in
the extruder barrel.
[0067] Other Additives
[0068] The composition of the present invention may include
additional components that do not interfere with the previously
mentioned desirable properties but enhance other favorable
properties such as antioxidants, colorant, including dyes and
pigments, lubricants, mold release materials, nucleants or ultra
violet (UV) stabilizers. Examples of lubricants are alkyl esters,
for example pentaerythritol tetrastearate, alkyl amides, such as
ethylene bis-stearamide, and polyolefins, such as polyethylene.
[0069] Also, the final composition may contain
polytetrafluoroethylene (PTFE) type resins or copolymers used to
reduce dripping in flame retardant thermoplastics.
[0070] In one embodiment, the thermoplastic polyester resin molding
composition includes a core-shell impact modifier for enhancing
heat resistance having a shell derived from an alkylacrylate and a
rubbery acrylate core derived from an acrylate having 4 to 12
carbon atoms.
[0071] In another aspect of the invention a thermoplastic molding
composition comprising the following is preferred;
[0072] (a) 25-60% polycarbonate
[0073] (b) 25-50% alkylene terephthalate
[0074] (c) 5-15% acrylic rubber core shell impact modifier
[0075] (d) 5-20% organopolysiloxane-polycarbonate
[0076] (e) 5-20% flame retardant
[0077] The blends of the invention may be formed into shaped
articles by a variety of common processes for shaping molten
polymers such as injection molding, compression molding, extrusion
and gas assist injection molding. Examples of such articles include
electrical connectors, enclosures for electrical equipment,
automotive engine parts, lighting sockets and reflectors, electric
motor parts, power distribution equipment, communication equipment
and the like including devices that have molded in snap fit
connectors. The impact modified polyester resins can also be made
into film and sheet.
EXAMPLES
[0078] The following examples illustrate the present invention, but
are not meant to be limitations to the scope thereof. Examples of
the invention are designated by numbers, comparative examples are
shown by letters. The examples of Table II and III were all
prepared and tested in a similar manner:
[0079] The ingredients of the examples shown below in Table II and
III, were tumble blended and then extruded on a 30 mm Werner
Pfleiderer Twin Screw Extruder with a vacuum vented mixing screw,
at a barrel and die head temperature between 240 and 265 degrees C.
and 300 rpm screw speed. The extrudate was cooled through a water
bath prior to pelletizing. Test parts were injection molded on a
van Dorn molding machine with a set temperature of approximately
240 to 265.degree. C. The pellets were dried for 3-4 hours at
120.degree. C. in a forced air circulating oven prior to injection
molding.
[0080] Notched Izod (NI) testing as done on 3.times.1/2.times.1/8
inch bars using ASTM method D256. Bars were notched prior to test
at various temperature.
[0081] Biaxial impact testing, sometimes referred to as
instrumented impact testing, was done as per ASTM D3763 using a
4.times.{fraction (1/8)} inch molded discs. The total energy
absorbed by the sample is reported as ft-lbs.
[0082] Accelerated weathering test was done as per ASTM-G26. The
samples of 2.times.3.times.1/8 inch molded rectangular specimen,
"color chip", were subjected to light in xenon are weatherometer
equipped with borosilicate inner and outer filters at an irradiance
of 0.35 W/m.sup.2 at 340 nm, using cycles of 90 min light and 30
min dark with water spray. The humidity and temperature were kept
at 60%, and 70.degree. C., respectively.
[0083] Chip color was measured on a ACS CS-5 ChromoSensor in
reflectance mode with a D65 illuminant source, a 10 degree
observer, specular component included, CIE color scale as described
in "Principles of Color Technology" F. W. Billmeyer and M.
Saltzman/John Wiley & Sons, 1966. The instrument was calibrated
immediately prior to sample analysis against a standard white tile.
The color values reported below are the difference before and after
UV exposure. The color change is expressed as delta E. Testing was
done as per ASTM D2244.
[0084] The impact modifier used was a core-shell acrylic rubber.
The impact modifier comprised a butyl acrylate (or derivatives
thereof) core grafted to a poly(methyl methacrylate) shell. These
pellets were obtained from Rohm and Haas under the trade name
PARALOID.RTM. as PARALOID.RTM. 3330 or EXL3330. EXL3330 is a
pelletized form of the powder acrylic rubber EXL3330. The acrylic
modifier was made by an emulsion polymerization similar to that
described in U.S. Pat. No. 3,808,180. It has an average particle
size of about 600 nm.
[0085] The core-shell acrylic impact modifiers with
polydimethylsiloxane and poly(butyl acrylate) in core was obtained
from Mitsubishi Rayon Co. Ltd. under the trade name of Metablend
S-2001.
[0086] The heat stabilizer was obtained from Ciba Geigy under the
trade name IRGAPHOS.RTM. as IRGAPHOS.RTM. 168, which is a tris
di-t-butyl phenyl phosphite.
[0087] The heat stabilizer was obtained from Ciba Ceigy under the
trade name IRGANOX.RTM. as IRGANOX.RTM. 1010. This antioxidant is a
tetra functional 2,6-di-tert butyl hindered phenol.
[0088] The heat stabilizer was obtained from Crompton Co under the
trade name SEENOX.RTM. 412S, which is a tetra ester of
pentaerythritol and 3-dodceylthioproprionic acid.
[0089] Table I shows the ingredients used in the blends discussed
in the comparative examples (designated by letters) and the
examples of the invention (designated by numbers).
[0090] All examples and comparative examples in Table II and III
have 2% titanium dioxide, 0.1%-0.2% mono zinc phosphate, and less
than 0.6% of combined heat stabilizers of IRGANOX.RTM. 1010,
IRGAPHOS.RTM. 168, and Seenox 412S.
Examples A-C & 1
[0091] The composition of the blends and test results are shown in
Table 2. Comparative examples A, B, and C show that a use of MBS
induces good notched Izod impact on un-weathered samples. However,
A, B, and C shows significant loss of impact properties after 1
month (720 hours) as per ASTM G26 accelerated weathering test.
Comparative example C shows slightly better weatherability in terms
of impact retention and color shift than B and C probably due to
the 0.5% UV absorber, UVA5411. However, more significant
improvement in the weatherability was achieved in the example 1.
Example 1 shows that both good low temperature impact properties
and weatherability can be obtained by using PC_ST and EXL3330. Note
that the example 1 does not have UV absorber but still has much
better weatherability than formulations with MBS.
Examples D-G & 2
[0092] Comparative examples F and G illustrate the enhanced
weathering properties obtained by using EXL3330 only. However,
EXL3330 only did not give good notched Izod impact at -10.degree.
C. and -20.degree. C. Comparative examples D and E shows that
S-2001 induces slightly better initial notched Izod but causes
earlier loss of instrumented impact under UV exposure than EXL3330.
Example 2 demonstrates that the combination of PC_ST and S-2001
improves notched Izod impact as well as weatherability of the
blend. Note that comparative examples D-G and example 1-2 have
lower color shift than comparative examples A-C with MBS after G26
weathering
1TABLE I Abbreviation Materials MBS
Butadiene-styrene-methyl-methacrylate core-shell rubber impact
modifier, EXL3691 from Rohm and Haas Company Lotader Lotader .RTM.
modifier AX8900 from Elf Atochem contains 67% of ethylene, 25% of
methyl acrylate, and 8% of glycidyl methacrylate S-2001 Core-shell
type impact modifier with silicone-acrylic-based rubber, METABLEN
S-2001 from Mitsubishi Rayon. EXL 3330 Acrylic impact modifier from
Rohm and Haas PC_ST SiloxanePC Eugenolcapped
siloxanecopolycarbonate, 20% polydimethylsiloxane by wt % UVA5411
2-(2'HYDROXY-5-T-OCTYLPHENYL)- BENZOTRIAZOLE, UV stabilizer Tinuvin
234 Benzotriazol UV stabilizer from Ciba-Geigy Company PC PC
bisphenol polycarbonate Lexan .RTM. resin from General Electric
Company PBT 315 Poly(1,4-butylene terephthalate) Mw .about.37,000
from GE Plastics Sb.sub.2O.sub.3 Antimony trioxide LDPE Low density
polyethylene BC52 Phenoxy-terminated tetrabromobisphenol-A
carbonate oligomer, flame retardant from Great Lakes Chemical Co.
ML1624 Brominated flame-retardant PC from GE plastics. Br-acrylate
Poly(pentabromobezyl acrylate) MW 15,000, 71% Bromine PTFE
Poly(tetrafluoroethylene), anti-dripping agent
[0093]
2 TABLE II Comparative Comparative Comparative Example A Example B
Example C Example 1 MBS 8.0 9.0 10.0 -- Lotader 2.0 -- -- -- S-2001
-- -- -- -- EXL3330 -- -- -- 12 PC_ST -- -- -- 15 UVA5411 0.25 --
0.5 -- Tinuvin234 PC 37.3 30.0 34.0 28.3 PBT 38.0 38.0 35.0 34.0
Br-acrylate 10.9 ML1624 20.0 15.4 BC52 8.1 Sb2O3 3.5 3.0 3.1 2.4
LDPE 2.0 PTFE 0.07 -- -- 0.2 Initial notched Izod impact (ft-lb/in)
at 0 degree C. 14.5 (100%) 13.9 (100%) 13.3 (100%) 15.1 (100%) at 0
degree C. -- 12.1 (100%) 11.6 (100%) 14.0 (100%) at -10 12.0 (100%)
11.7 (100%) 11.2 (100%) 12.3 (100%) degree C. at -20 12.0 (20%) 9.6
(80%) 10.4 (100%) 11.5 (100%) degree C. Instrumented impact at -20
degree C. after ASTM G26 weathering (ft-lb) 0 hrs, G26 25.2 (100%)
26.4 (100%) 26.8 (100%) 28.2 (100%) 720 hrs, G26 1.3 (0%) 2.1 (0%)
6.5 (0%) 23.4 (100%) 1440 hrs, G26 1.2 (0%) 2.2 (0%) -- 17.8 (100%)
Notched Izod impact at RT after ASTM G26 weathering (ft-lb/in) 0
hrs, G26 12.9 11.1 -- 15.2 720 hrs, G26 11.5 8.6 -- 14.4 1440 hrs,
G26 10.6 8.1 -- 13.6 2880 hrs, G26 5.4 5.5 -- 13.1 Color shift
(delta E) after ASTM G26 weathering 720 hrs, G26 11.4 8.1 5.9 5.0
1440 hrs, G26 13.7 9.8 -- 4.3
[0094]
3 TABLE III Comparative Comparative Comparative Comparative Example
D Example E Example F Example G Example2 MBS -- -- -- -- -- Lotader
-- -- -- -- -- S2001 8 12 -- -- 9.2 EXL3330 -- -- 8 12 -- PC ST --
-- -- -- 10.6 UVA5411 0.25 0.25 0.5 0.5 Tinuvin234 0.5 PC 41.3 36.6
42.4 36.7 32.8 PBT 37.0 38.0 37.0 37.0 35.8 BC52 10.0 9.6 9.0 10.3
8.0 Sb2O3 3.1 2.9 2.7 3.1 2.9 LDPE PTFE 0.4 0.4 0.6 0.4 0.2 Initial
notched Izod impact (ft-lb/in) at 0 degree C. 15.5 (100%) 15.5
(100%) 16.3 (100%) 16.6 (100%) 15.0 (100%) at 0 degree C. 11.2
(80%) 13.2 (100%) 6.2 (20%) 13.8 (100%) 13.7 (100%) at -10 degree
C. 5.0 (0%) 8.1 (60%) 4.0 (0%) 4.7 (0%) 12.8 (100%) at -20 degree
C. 4.1 (0%) 4.5 (0%) 3.6 (0%) 4.0 (0%) 6.9 (20%) Instrumented
impact at -20 degree C. after ASTM G26 weathering (ft-lb) 0 hrs,
G26 31.9 (100%) 33.4 (100%) 31.8 (100%) 30.1 (100%) 32.2 (100%) 720
hrs, G26 30.4 (100%) 29.2 (100%) 32.5 (100%) 25.7 (100%) 28.0
(100%) 1440 hrs, G26 1.6 (0%) 0.9 (0%) 15 (50%) 29.9 (100%) 26.6
(100%) Notched Izod impact at RT after ASTM G26 weathering
(ft-lb/in) 0 hrs, G26 15.5 15.5 16.2 16.6 15.1 720 hrs, G26 14.7
14.6 1440 hrs, G26 14.3 14.0 14.1 14.5 14.2 2160 hrs, G26 13.6 14.1
2880 hrs, G26 13.5 13.3 14.0 -- Color shift (delta E) after ASTM
G26 weathering 720 hrs, G26 4.4 4.6 4.3 4.3 4.7 1440 hrs, G26 3.5
4.2 3.9 3.9 3.8
* * * * *