Glass-filled polycarbonate of improved ductility

A glass-fiber reinforced aromatic polycarbonate is provided with improved ductility and improved mold release properties which is comprised of an aromatic polycarbonate resin, glass-fibers and an ester wax of montanic acid.

FIELD OF THE INVENTION 
This invention relates to polycarbonates and more particularly to 
glass-filled aromatic polycarbonates containing ester waxes from montanic 
acid. 
BACKGROUND OF THE INVENTION 
Polycarbonates derived from reactions involving organic dihydroxy compounds 
and carbonic acid derivatives have found extensive commercial application 
because of their excellent mechanical and physical properties. These 
thermoplastic polymers are particularly suited for the manufacture of 
molded products where impact strength, rigidity, toughness, thermal 
stability, dimensional stability as well as excellent electrical 
properties are required. 
In comparison to non-reinforced polycarbonates, glass fiber reinforced 
polycarbonates have both substantially increased flexural strength and 
stiffness and a substantially increased E-modulus, but have a decreased 
impact strength, notched impact strength and elongation at break. This 
degradation in impact and other physical properties is thought to be 
attributable to the formation of stress concentrations in the vicinity of 
the individual glass fibers causing propagation of cracks in the molded 
articles. 
Furthermore, polycarbonates are outstandingly ductile thermoplastic 
polymers, but become relatively brittle upon incorporation of small 
amounts of glass fiber reinforcement. As the amount of glass fibers 
incorporated into the polycarbonate increases, not only does the 
brittleness of the polycarbonate remain apparent, but the glass fiber 
reinforced polycarbonate becomes increasingly difficult to demold from 
injection mold cavities. 
In accordance with the present invention, glass-fiber reinforced aromatic 
polycarbonates are provided with improved ductility and improved mold 
release properties. 
SUMMARY OF THE INVENTION 
A glass-fiber reinforced aromatic polycarbonate is provided with improved 
ductility and improved mold release properties which is comprised of an 
aromatic polycarbonate resin, glass-fibers and an ester wax of montanic 
acid. The ester wax of montanic acid is derived from the naturally 
occurring montan wax. 
DETAILED DESCRIPTION OF THE INVENTION 
When used herein, the term "aromatic polycarbonate resin" means the neat 
resin without additives and the term "aromatic polycarbonate" means both 
the formulated aromatic polycarbonate resin with additives therein and 
also the final molded plastic product. 
The aromatic polycarbonate resins useful in practice of the invention are 
produced by reacting di-(monohydroxyaryl)-alkanes or dihydroxybenzenes and 
substituted dihydroxybenzenes with derivatives of carbonic acid such as 
carbonic acid diesters, phosgene, bis-chloro-carbonic acid esters of 
di-(monohydroxyaryl)-alkanes and the bis-chloro-carbonic acid esters of 
the dihydroxybenzenes and the substituted dihydroxybenzenes. 
By aromatic polycarbonate resin, in the sense of the present invention, 
there are understood homopolycarbonate and copolycarbonate resins which 
are based, for example, on one or more of the following bisphenols: 
hydroquinone, resorcinol, dihydroxydiphenyls, bis-(hydroxyphenyl)-alkanes, 
bis-(hydroxyphenyl)-cycloalkanes, bis-(hydroxyphenyl)sulphides, 
bis-(hydroxyphenyl)-ethers, bis-(hydroxyphenyl)ketones, 
bis-(hydroxyphenyl)-sulphoxides, bis-(hydroxyphenyl)-sulphones and 
.alpha.,.alpha.-bis-(hydroxyphenyl)-diisopropylbenzenes, as well as their 
nuclear-alkylated and nuclear-halogenated compounds. These and further 
suitable aromatic dihydroxy compounds are described, for example, in U.S. 
Pat. Nos. 3,028,365, 2,999,835, 3,148,172, 3,271,368, 2,991,273, 
3,271,367, 3,280,078, 3,014,891 and 2,999,846 (all incorporated herein by 
reference) in German Offenlegungsschriften (German Published 
Specifications) Nos. 1,570,703, 2,063,050, 2,063,052, 2,211,956 and 
2,211,957, in French Patent Specification 1,561,518 and in the monograph 
"H. Schnell, Chemistry and Physics of Polycarbonates, Interscience 
Publishers, New York, 1964." 
Preferred bisphenols are those of the formula I 
##STR1## 
in which R is identical or different and denotes H, C.sub.1 -C.sub.4 
-alkyl, Cl or Br 
and in which 
X is a bond, C.sub.1 -C.sub.8 -alkylene, C.sub.2 -C.sub.8 -alkylidene, 
C.sub.5 -C.sub.15 -cycloalkylene, C.sub.5 -C.sub.15 -cycloalkylidene, 
--SO.sub.2 --, --SO--, --CO-- or 
##STR2## 
Examples of these bisphenols are: 4,4'-dihydroxydiphenyl, 
2,2-bis-(4-hydroxyphenyl)-propane (bisphenol A), 
2,4-bis-(4-hydroxyphenyl)-2-methylbutane, 
1,1-bis-(4-hydroxyphenyl)-cyclohexane, 
.alpha.,.alpha.-bis-(4-hydroxyphenyl)-p-diisopropylbenzene, 
2,2-bis-(3-methyl-4-hydroxyphenyl)-propane, 
2,2-bis-(3-chloro-4-hydroxyphenyl)-propane, 
bis-(3,5-dimethyl-4-hydroxyphenyl)-methane, 
2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane, 
bis-(3,5-dimethyl-4-hydroxyphenyl)sulphone, 
2,4-bis-(3,5-dimethyl-4-hydroxyphenyl)-2-methylbutane, 
1,1-bis-(3,5-dimethyl-4-hydroxyphenyl)-cyclohexane, 
.alpha.,.alpha.-bis-(3,5-dimethyl-4-hydroxyphenyl)-p-diisopropyl-benzene, 
2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane and 
2,2-bis-(3,5-dibromo-4-hydroxyphenyl)-propane (tetrabromo bisphenol A) 
propane. 
Examples of particularly preferred bisphenols are: 
2,2-bis-(4-hydroxyphenyl)-propane, 
2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane, 
2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane, 
2,2-bis-(3,5-dibromo-4-hydroxyphenyl)propane and 
1,1-bis-(4-hydroxyphenyl)-cyclohexane. 
Preferred aromatic polycarbonate resins are those which are based on one or 
more of the bisphenols mentioned as being preferred. Particularly 
preferred copolycarbonate resins are those based on 
2,2-bis-(4-hydroxyphenyl)-propane and one of the other bisphenols 
mentioned as being particularly preferred. Further particularly preferred 
polycarbonate resins are those based solely on 
2,2-bis-(4-hydroxyphenyl)propane or 
2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane. 
The aromatic high-molecular weight polycarbonate resins can be branched due 
to the incorporation of small amounts, preferably of between about 0.05 
and 2.0 mol % (relative to diphenols employed), of trifunctional or more 
than trifunctional compounds, especially compounds with three or more 
phenolic hydroxyl groups. 
Polycarbonate resins of this type are described, for example, in German 
Offenlegungsschriften (German Published Specifications) Nos. 1,570,533, 
1,595,762, 2,116,974 and 2,113,347, British Patent Specification No. 
1,079,821 and U.S. Pat. No. 3,544,514 (incorporated herein by reference). 
Some examples of compounds with three or more than three phenolic hydroxyl 
groups which can be used are phloroglucinol, 
4,6dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptane-2,4,6-dimethyl-2,4,6-tri-( 
4-hydroxyphenyl)-heptane, 1,4,5-tri(4-hydroxyphenyl)-benzene, 
1,1,1-tri-(4-hydroxyphenyl)-ethane, tri-(4-hydroxyphenyl)-phenylmethane, 
2,2-bis-4,4-bis-(4-hydroxyphenyl)-cyclohexyl!-propane, 
2,4-bis-(4-hydroxyphenylisopropyl)-phenol, 
2,6-bis-(2-hydroxy-5'-methyl-benzyl)-4-methylphenol, 
2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)propane, 
hexa(4-(4-hydroxyphenylisopropyl)phenyl) orthoterephthalic acid ester, 
tetra-(4-hydroxyphenyl)-methane, 
tetra-(4-(4-hydroxyphenylisopropyl)-phenoxy)-methane and 
1,4-bis-((4',4"-dihydroxytriphenyl)-methyl)-benzene. Some of the other 
trifunctional compounds are 2,4-dihydroxybenzoic acid, trimesic acid, 
cyanuric chloride and 3,3-bis-(4-hydroxyphenyl)-2-oxo-2,3-dihydroindole. 
The polycarbonate resins are preferably those having a weight average 
molecular weight from about 10,000 to 200,000, most preferably about 
20,000 to 80,000, and preferably a melt flow rate range of about 1 to 24 
g/10 min (ASTM 1238) and are prepared by methods known to those skilled in 
the art and more particularly by methods disclosed in U.S. Pat. Nos. 
3,028,365, 2,999,846, 3,248,414, 3,153,008, 3,215,668, 3,187,065, 
2,964,794, 2,970,131, 2,991,273 and 2,999,835, all incorporated herein by 
reference. 
The ester waxes of montanic acid of the invention are present in the 
polycarbonate in an amount of about 0.1 to 2 percent by weight, preferably 
about 0.35 to 0.70 percent by weight, based on the weight of the total 
composition. 
The ester waxes of montanic acid are derived from montan wax which is 
naturally occurring in nature. Montan wax is a bituminous wax occurring in 
brown coals or lignites from which it can readily be extracted. 
Wax-containing brown coals have been mined in Australia, New Zealand, 
Czechoslovakia, Russia and the U.S. (California and Arkansas), in addition 
to the main source of supply in central Germany, where its extraction and 
processing is an old and established industry. The crude montan wax is 
complex chemically, but its composition is similar to other natural waxes. 
The crude montan wax is dark brown and melts at about 76.degree. to 
92.degree. C. It is primarily an ester wax, nearly 60% esters, but also 
has a substantial free acid content which is likely to be in excess of 
15%. The total carbon chain length of the acids and alcohols in the crude 
wax is 26 - 32 carbon atoms and 26 carbon atoms, respectively. There 
probably are some hydroxy acid esters present in the crude montan wax, and 
there may be some odd-numbered fatty acids in the C.sub.27 -C.sub.31 
range, either free or combined. In addition to a resin content of 1-12%, a 
C.sub.28 -C.sub.30 ketone content of up to 10% is frequently reported in 
crude montan wax. 
The dark brown, crude montan wax can be refined by known procedures into a 
pale acid wax having an acid number of about 10-20 (DGF Einheitsmethoden 
M-IV,2(57))* and a saponification number of about 100-160 (DGF 
Einheitsmethoden M-IV, 2(57))** by means of various oxidizing agents of 
which chromic acid has proved the most suitable, the wax molecule being 
modified to a very great extent. When the natural, crude montan wax is 
hydrolyzed, free alcohols are formed, but are reoxidized to acids by the 
oxidizing agent. Dicarboxylic acids are oxidized from the hydroxy 
carboxylic acids and their esters present in the crude wax. They may be 
present in the newly formed acid wax in proportions of up to 30%. By 
esterification with long-chain fatty alcohols or low-molecular weight 
glycols, the montanic acid waxes are converted into the montanic ester 
waxes useful in the present invention. By the appropriate choice of 
alcohols and glycols or by subsequent neutralization of non-esterified 
acids, a wide variety of montanic acid ester waxes may be provided. 
FNT * Similar to ASTM D-1386-59 but modified by using a 2:1 xylene: ethanol 
solvent system instead of a 1:2 toluene/ethanol solvent system. 
FNT ** Similar to ASTM D-1387-59 but modified by using a 2:1 xylene: ethanol 
solvent system instead of a 1:2 toluene/ethanol solvent system. 
The montanic acid ester waxes useful in the present invention are 
commercially available, such as Hoechst E-wax and Hoechst OP-wax. 
The preferred montanic acid ester waxes useful in the present invention 
have an acid number of between about 15-20 and a saponification number 
between about 140-160 and consist essentially of esters of the general 
formula: 
##STR3## 
wherein n and n' may be the same or different and are between 25 and 31 
inclusive and a is between 1 and 13 inclusive, preferably 1. Hoechst E-Wax 
is such a preferred montanic acid ester wax. 
In a preferred embodiment of the present invention, the glass-filled 
polycarbonate may contain a sufficient quantity of pigment to opacify the 
glass-filled polycarbonate in addition to containing ester waxes derived 
from montanic acid. 
Suitable pigments used to opacify and color the polycarbonate are those 
conventionally known to skilled artisans for use in high molecular weight 
thermoplastic pigmentation. By far, titanium dioxide is the most preferred 
pigment to opacify and whiten molded articles because of its high index of 
refraction, extreme whiteness and brightness. However, other white 
pigments such as lithopone, zinc sulfide, zinc oxide, antimony trioxide, 
and the like may be used. To impart color (other than white) to the 
polycarbonate pigments such as red lead, cuprous oxide, cadmium reds, 
cinnabar, antimony vermilion (red and brown pigments); zinc yellow, chrome 
yellows and oranges, cadmium yellow, antimony yellow, (orange and yellow 
pigments); chrome greens, chrome oxide greens (green pigments); cobalt 
blue, iron blues (blue pigments); lampblacks, vegetable blacks, animal 
blacks (black pigments) and the like may be used. 
In addition to the inorganic pigments, recited above, organic pigments may 
be used such as pigment chlorine, lithol fast yellow toluidine red, 
permanent orange and the like. Dyes may be added to impart color to the 
polycarbonate such as the phthalocyanines, the anthraquinones and the 
like. 
Particular examples of suitable pigments include Pigment Blue 15 (C.I. 
74160), Diluted Black-PDS 161 B-192 (Kohnstamm), Solvent Violet 13 (C.I. 
60725), Yellow 37 (C.I. 77199), Cadmium Red (C.I. 77196), Croton Fast 
Green Toner 4D-3600 (Harshaw Chemical Co.), Amaplast Yellow GHS 
(Drakenfeld), PDS 987 Thermax Blue-Black (Kohnstamm), Marine Blue 
(Drakenfeld), Scarlet Red 10177 (Drakenfeld), Scarlet Red 10051 
(Drakenfeld), phthalocyanine pigments such as, for example, copper 
phthalocyanine (Monastral Fast Blue B or Heliogen Blue BA), chlorinated 
copper phthalocyanine (Monastral Fast Green G or Heliogen Green GA), 
sulfonated copper phthalocyanine and metal free phthalocyanine (Monastral 
Fast Blue G). 
The pigment is incorporated into the polycarbonate at a level of about 1 to 
18 grams, preferably 2 to 8 grams, of pigment per pound of polycarbonate 
resin. The above ranges are sufficient to acceptably opacify the 
polycarbonate and any articles made from the polycarbonate of the present 
invention. 
Glass fibers which can be used to prepare the polycarbonate compositions 
are, for example, fibers of low-alkali, aluminum-borosilicate glass having 
a maximum alkali metal oxide content of 2.0% by weight (E-glass), of 
diameter between 8-15 .mu. length between 300 and 800 .mu. (short glass 
fibers) or 2,000 to 12,000 .mu. (chopped strands) as well as rovings. The 
glass fibers are present in the polycarbonate in from about 5 to 40% by 
weight, preferably, about 10 to 30% by weight, based on the weight of the 
total composition. 
To prepare molding compositions according to the present invention, the 
individual components are mixed in known mixing devices, such as kneaders, 
single-screw extruders, twin-screw extruders, mills and the like. 
In a preferred embodiment, the aromatic polycarbonate resin, an ester wax 
of montanic acid and optionally pigment, are preblended and the glass 
fibers are subsequently added to the preblend. The entire mixture is 
further blended and then extruded. 
During the blending process, it is possible to admix additional additives 
such as stabilizers, flame retardant agents, flow agents, lubricants and 
antistatic agents in a known manner.

The invention will further be illustrated, but is not intended to be 
limited, by the following examples. 
EXAMPLES 
Example 1 
9.39 lbs. of a bisphenol-A polycarbonate having a melt flow rate of about 
12.1 gms./10 min. at 300.degree. C (ASTM D 1238) was tray-dried overnight 
at 110.degree. C. The polycarbonate resin in the form of hot pellets was 
mixed with 3.26 grams of a phosphite-based stabilizer and the mixture was 
blended for 21/2 minutes in a 5 gallon stainless steel drum and then 
cooled to 55.degree. C. 5.4 grams of a flame retardant perfluoroalkane 
sulphonic acid salt and 65.3 grams of a grey colorant mixture were then 
added to the stabilized polycarbonate and the mixture was blended for an 
additional 21/2 minutes. 2.4 lbs. (20% by weight) of 3/16 inch long glass 
fibers were added next and the mixture was blended for an additional 11/2 
minutes. The mixture was then extruded in a single screw extruder equipped 
with a 2.75:1 compression screw and four rows of mixing pins. The 
temperature profile of extrusion was: 
______________________________________ 
Melt 
Rear Middle Front Tempera- 
Zone Zone Zone Die Screens 
ature 
______________________________________ 
540.degree. F 
450.degree. F 
455.degree. F 
520.degree. F 
none 480.degree. F 
______________________________________ 
The extruder strands were pelletized and 1/8 inch thick standard samples 
were molded for evaluation of physical properties. 
Ductility (drop dart impact strength) was measured by dropping a 10.4 lb. 
weight with a contact surface of a 1 inch diameter hemisphere upon a 1/8 
inch thick, 4 inch diameter securely clamped, molded specimen. The drop 
height corresponding to a 50% breakage of the specimen was proportional to 
the ductility of the test specimen. 
The ease of release from the mold was determined subjectively by observing 
the ejection of test specimens from the mold. 
The ductility (drop dart impact resistance), ease of mold release, and 
additional physical properties of the composition of Example 1 and the 
additional Examples are reported in the following Table 1. 
Example 2 
A polycarbonate composition was prepared by the method of Example 1 except 
that 19 grams (0.35% by weight based on the total composition) of the 
stearyl ester of behenic acid (Henkel International, GMBH Loxiol G-47) was 
blended with the components used in Example 1. 
Example 3 
A polycarbonate composition was prepared by the method of Example 1 except 
that 19 grams (0.35% by weight based on the total composition) of an ester 
wax of montanic acid (Hoechst E-Wax) was blended with the components of 
Example 1. 
Example 4 
A polycarbonate composition was prepared by the method of Example 1 except 
that 38 grams (0.70% by weight based on the total composition) of an ester 
wax of montanic acid (Hoechst E-Wax) was blended with the components of 
Example 1. 
Example 5 
A polycarbonate composition was prepared by the method of Example 1 except 
that 19 grams (0.35% by weight based on the total composition) of a partly 
saponified ester wax of montanic acid (Hoechst OP wax) was blended with 
the components of Example 1. 
TABLE 1 
__________________________________________________________________________ 
Flexural 
Flexural 
Concentration 
Drop Dart 
Modulus Strength 
Ease Of Mold 
Example 
Additive (wt. %) (ft. lb.) 
(PSI .times. 10.sup.5) 
(PSI .times. 10.sup.3) 
Release 
__________________________________________________________________________ 
1 None None 4.7 8.2 16.8 Poor-must 
use extern- 
al mold 
release 
agent 
2 The stearyl 
0.35 19.7 7.9 16.1 Minor 
ester of be- sticking 
henic acid to mold 
(Loxiol G-47) 
3 Ester wax 
0.35 29.6 8.3 15.8 Minor 
of montanic sticking 
acid (Hoechst to mold 
E-Wax) 
4 Ester wax 
0.70 27.6 8.3 15.3 Minor 
of montanic sticking 
acid (Hoechst to mold 
E-Wax) 
5 Partly 0.35 9.6 8.4 16.7 Minor 
saponified sticking 
ester wax to mold 
of montanic 
acid (Hoechst 
OP Wax) 
__________________________________________________________________________ 
The data in Table 1 demonstrates that the addition of an ester wax of 
montanic acid to an aromatic polycarbonate composition results in 
ductility and mold release properties superior to those properties 
encountered in a polycarbonate composition containing no internal mold 
release agent and that the addition of the applicants' preferred ester wax 
of montanic acid (Hoechst E-Wax) used in Examples 3 and 4 to an aromatic 
polycarbonate results in ductility and mold release properties superior to 
those properties exhibited in a polycarbonate composition containing a 
known mold release-agent (Loxiol G-47) as an internal mold release agent. 
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 can 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.