Molding resins

Polyethylene terephthalate resin compositions containing filler or reinforcing agent, a selected sodium or potassium salt of a hydrocarbon acid or a salt of a selected organic polymer containing pendant carboxyl groups, and a selected low molecular weight organic ester, ketone, sulfone, sulfoxide, nitrile or amide. Articles molded from the compositions have high gloss when molded at temperatures below 110.degree. C.

DESCRIPTION OF THE INVENTION 
The polyethylene terephthalate employed herein is one which has an inherent 
viscosity of at least 0.4 as measured by ASTM D-2857. The polyethylene 
terephthalate preferably has an upper limit on inherent viscosity of about 
1.2. Inherent viscosity is measured in a 3:1 by volume ratio of methylene 
chloride and trifluoroacetic acid at 30.degree. C. The polyethylene 
terephthalate can contain minor amounts of other comonomers such as 
diethylene glycol or glutaric acid. 
The reinforcing or filler material employed herein include glass fibers, 
glass beads, aluminum silicate, asbestos, mica and the like, or 
combinations thereof as for example a mixture of mica and glass fibers. 
Materials present in an amount sufficient to cause the compositions of the 
invention to have a .DELTA.H.sub.H /.DELTA.H.sub.c ratio of less than 0.25 
(component C defined above) include the sodium or potassium salts of 
hydrocarbon carboxylic acids containing between 7 and 25 carbon atoms, 
preferably more than 12 carbon atoms. Representative of these acids (which 
are fatty acids) are stearic, pelargonic, and behenic acid. These 
materials also include the sodium or potassium salts of carboxyl 
containing organic polymers, such as copolymers of olefins and acrylic or 
methacrylic acids, or copolymers of aromatic olefins and maleic anhydride. 
Preferably these materials include the sodium or potassium salt of stearic 
acid; the sodium or potassium salt of ethylene/methacrylic acid copolymers 
(including both wholly or partially neutralized salts e.g., at least about 
30% neutralized), the sodium salt of styrene/maleic anhydride copolymers 
(including both wholly or partially neutralized salts e.g., at least about 
30% neutralized) and sodium versatate. In the copolymers listed above the 
olefin or aromatic olefin moiety ordinarily comprises 50-98 percent by 
weight of the copolymer, and preferably 80-98 percent. An especially 
preferred material is the sodium salt of ethylene/methacrylic acid 
copolymer. The copolymers may be prepared by conventional high pressure 
polymerization technology. 
Preferred organic esters of component D recited above are those in which 
the aromatic carboxylic acids are hydrocarbon acids containing 1-3 
carboxyl groups and the alcohols are aliphatic. In other words, the R 
groups in the alcohols are alkyl or alkylene depending upon the particular 
R group. Preferably also when the carboxylic acids contain two or more 
carboxyl groups, the carboxyl groups are all reacted to form ester (COO) 
linkages, that is, there will be no free carboxyl groups present in the 
ester. Preferably, all the hydroxyl groups of the alcohols will also be 
reacted to form ester (COO) linkages, that is, there will be no free 
hydroxyl groups present in the ester. 
A preferred class of esters are those in which the acid is benzoic acid, 
and the alcohol is (HOCH.sub.2).sub.2 --R' wherein R' is alkylene of 4-6 
carbon atoms (preferably neopentyl glycol) or HO(R"O).sub.y H wherein R" 
is ethylene or propylene, and y is 2 or 3. 
Preferred ketones, sulfones, sulfoxides, nitriles and amides are those in 
which the R groups in the formulas provided further above for these 
organic compounds are aryl groups of 6-10 carbon atoms or alkyl groups of 
1-10 carbon atoms. 
Specific compounds within these definitions are listed following (The 
number in parenthesis after each compound is the number of degrees 
centigrade that 1 percent by weight of the compound present (based on 
polyethylene terephthalate) in the reinforced or filled polyethylene 
terephthalate lower the Tpk): dibenzoate of neopentyl glycol (2.0), 
dibenzoate of triethylene glycol (3.0), dibenzoate of diethylene glycol 
(3.2), dibenzoate of dipropylene glycol (3.0), tris-2-ethyl hexyl 
trimellitate (2.5), phenyl benzoate (3.0), trimethylolethane tribenzoate 
(1.53), dioctylphthalate (1.3), diisodecyl phthalate (0.8), benzophenone 
(2.5), 4-fluorobenzophenone (1.9), diphenyl sulfone (2.8), 
N-ethyl-o,p-toluene sulfonamide (2.3), tolyl sulfoxide (2.6), lauryl 
nitrile (2.9), and erucyl nitrile (2.3). 
Components (C) and (D) in the compositions of this invention aid in 
obtaining molded articles of high surface gloss at molding temperatures 
below 110.degree. C. by increasing the rate of crystallization of 
polyethylene terephthalate. Component (C) is believed to primarily aid in 
increasing the rate of crystallization while component (D) is believed to 
primarily improve the mobility of the polyethylene terephthalate in its 
supercooled state by reducing the viscosity in such state. Both are 
necessary to obtain the high gloss found in the articles molded from the 
composition. 
The amount of component (C) present in the compositions of this invention 
is an amount which will result in a .DELTA.H.sub.H /.DELTA.H.sub.c ratio 
of the composition less than 0.25. To find the .DELTA.H.sub.H 
/.DELTA.H.sub.c ratio, polyethylene terephthalate is molded at 70.degree. 
C. into 1/16" thick bars. The bars are heated and at between 95.degree. C. 
and 120.degree. C. an exotherm (termed .DELTA.H.sub.H) is recorded on a 
differential scanning calormeter (DSC) cell attached to a Du Pont 900 
Differential Thermal Analysis (DTA) device. The bar is heated to 
290.degree. (which is above its melting point) and the melted sample 
cooled at 10.degree. C./minute. Another exotherm at between about 
200.degree.-220.degree. C. (termed .DELTA.H.sub.c) is the exotherm 
recorded on freezing of the sample. It has been found that the 
.DELTA.H.sub.H /.DELTA.H.sub.c ratio is a convenient method of measuring 
the degree of crystallization. 
The Tpk of the composition of this invention is the temperature at which 
heat evolves most rapidly during the heating cycle recited in the previous 
paragraph. As stated earlier the amount of component (D) present in the 
composition of this invention is an amount which lowers the Tpk of the 
composition by at least 4.degree. C. over that of an identical composition 
that does not contain component (D). 
The upper limits on the amounts of components C and D are not critical. 
However, physical properties may become adversely affected as amounts 
increase. In general, the upper amount employed for any one component will 
usually be about 12 percent by weight based on weight polyethylene 
terephthalate, while the lower limit will be about 1 percent. For the 
preferred component (C) salts of ethylene/methacrylic acid copolymer the 
upper limit on the amount present will be about 12 percent by weight based 
on weight of polyethylene terephthalate while the lower limit will be 
about 0.5 percent, but preferably an amount within the range of 1-5 
percent will be used. 
In addition to the components discussed hereinabove, the compositions of 
this invention may contain additives commonly employed with polyester 
resins, such as colorants, mold release agents, antioxidants, ultraviolet 
light stabilizers, flame retardants and the like. Additives which improve 
physical properties, such as tensile strength and elongation can also be 
employed; such additives include epoxy compounds (e.g., an epoxy compound 
formed from bisphenol-A and epichlorohydrin) present in amounts of from 
0.1-1.5 percent by weight based on weight of composition. 
The compositions of this invention are prepared by blending the components 
together by any convenient means. Neither temperature nor pressure are 
critical. For example, the polyethylene terephthalate can be mixed dry in 
any suitable blender or tumbler with components B, C and D and the mixture 
melt-extruded. The extrudate can be chopped and mixed with reinforcing 
agent and then this mixture melt extruded. More conveniently, all the 
components can be mixed dry in any suitable blender or tumbler and the 
mixture then melt extruded. 
The following Examples describe the best mode of carrying out the 
invention. The .DELTA.H.sub.H /.DELTA.H.sub.c ratio and the Tpk were 
determined as described above, while the gloss of molded sample was 
measured with a Gardner Multi Angle Gloss (Model GG-9095) set at a 
selected degree angle set forth in the Examples. 
EXAMPLE 1 
A dry blend of 92.57 percent by weight of dry polyethylene terephthalate 
having an inherent viscosity of about 0.5 to 0.6, 1 percent by weight 
sodium stearate, 5 percent by weight benzophenone, and 1.43 percent by 
weight N-stearyl erucamide (a mold release additive) was extruded through 
a 28 mm twin screw extruder at a melt temperature of approximately 
264.degree. C. The chopped strands from the extruded melt were dried at 
about 110.degree. C. for 16 hours in a vacuum oven. The dried chopped 
strands were dry mixed with sufficient OCF 419AA glass fiber (chopped to 
3/16") to make 30 percent glass fiber by weight and extruded through a 
2-stage single screw extruder at about 264.degree. C. melt temperature. 
The .DELTA.H.sub.H /.DELTA.H.sub.c ratio was 0.06 and the Tpk was 
12.degree. less than the same composition but without the benzophenone 
present. The extruded strands were cooled and chopped and then dried at 
about 110.degree. C. for 16 hours in a vacuum oven. The dried chopped 
strands were molded in a 6 oz. injection molding machine at approximately 
290.degree. C. with a fast ram, 20 seconds injection forward time, and 20 
seconds mold close time and a 95.degree. C. cavity temperature. Gloss of 
the molded article was very good. As determined with a Gardner Multi Angle 
Gloss Meter (Model GG-9095) set at a twenty degree angle the gloss 
registered 23. At a 70.degree. cavity temperature gloss measured in the 
same manner was 5. 
EXAMPLES 2 TO 15 AND COMISON A TO F 
In the Examples and comparisons which follow, the procedure generally 
employed to make compositions of this invention is as follows: 
Dry polyethylene terephthalate having an inherent viscosity of about 
0.5-0.65 was mixed manually with glass fiber as specified in the tables 
below and with ethylene/methacrylic acid copolymer (85/15 by weight) which 
had been 60 percent neutralized with sodium (which is component C herein) 
in an amount specified in the tables below and with the component D 
specified in the tables. Other additives may be present to improve 
strength of molded articles or to improve mold release properties. These 
additives, if present, are specified in the tables. 
The resulting mixture was then extruded through a two-stage two inch single 
screw extruder at a melt temperature of 285.degree. C. and at a vacuum of 
28 inches. The extruded strand was cut and the resulting resin pellets 
dried at 110.degree. C. in a vacuum oven for about 16 hours. The resin 
pellets were then molded into tumblers that were 9.2 cm high, 7.5 cm in 
diameter at the top, 5.5 cm in diameter at the bottom and which had a wall 
thickness of 0.19 cm. Melt temperature in the molding machine was 
295.degree. C.; while the surface temperature of the mold was 85.degree. 
C. Cycle times and release pressures are recited in the tables. 
Gloss was measured at an angle of 60.degree. by the Gardner Multi Angle 
Gloss Meter (Model GG-9095) several times for each sample. Gloss was 
measured around the circumference of the tumbler, at one-third the way 
down from the top. Pressure needed to release the tumbler was also 
measured by recording the air pressure necessary to move the ejector. The 
tables record the highest and the lowest gloss figures obtained in all the 
gloss tests performed on the sample. The tables also record the visual 
surface appearance of the molded tumblers. 
In the tables, percent amount of components C and D are based on weight of 
polyethylene terephthalate employed. Percent amount of filler or 
reinforcing agent and other additives are based on weight of mixture that 
is to be extruded. 
In the tables, component D is identified by a single letter. The letters 
represent the specific component D as follows: 
A--Dibenzoate of neopentyl glycol 
B--Lauryl nitrile 
C--Dibenzoate of dipropylene glycol 
D--Erucyl nitrile 
E--Benzophenone 
F--Trioctyl trimellitate 
G--Diphenyl sulfone 
H--N-ethyl-o,p-toluene sulfonamide 
I--Dibenzoate of diethylene glycol 
The reinforcing or filler material employed is identified in tables by two 
letters. The letters represent the specific materials as follows: 
AA--OCF 277B glass fiber 
BB--Mica (Suzorite A60) platelets 
CC--OCF 419AA glass fiber 
The other additives are identified by letter as follows: 
X--epoxy formed from bisphenol A and epichlorohydrin 
Y--tetrakis [methylene (3,5-di-tert-butyl-4-hydroxyhydroxycinnamate)] 
methane 
TABLE I 
______________________________________ 
AMOUNT COM- OTHER 
OF PONENT FILLER ADDI- 
COM- D AND AND TIVES 
PONENT AMOUNT AMOUNT PRESENT 
EXAMPLE C (%) (%) (%) (%) 
______________________________________ 
2 5.8 A(5.7) AA(25) X(0.6) 
Y(0.3) 
3 5.8 A(5.4) AA(35) X(0.55) 
Y(0.25) 
4 5.9 A(5.4) AA(55) X(0.5) 
Y(0.18) 
5 5.7 A(5.3) BB(30) NONE 
6 5.8 A(5.6) CC(25) NONE 
7 6.1 A(11.6) CC(25) NONE 
8 5.6 B(2.8) CC(25) NONE 
9 5.8 C(5.7) AA(25) X(0.6) 
Y(0.3) 
10 5.8 D(4.3) CC(25) SAME 
11 2.1 E(5.1) CC(25) NONE 
12 5.7 F(3.7) CC(25) NONE 
13 5.8 G(5.3) CC(25) NONE 
14 5.8 H(5.3) CC(25) NONE 
15 5.7 I(3.7) CC(25) NONE 
______________________________________ 
TABLE 2 
__________________________________________________________________________ 
GLOSS AS 
MOLDED (low- 
RELEASE 
est value/ 
MOLDED 
CYCLE 
PRESSURE 
highest SURFACE 
Ex .DELTA.H.sub.H /.DELTA.H.sub.c 
.DELTA.Tpk 
TIME (psi) value) APPEARANCE 
__________________________________________________________________________ 
2 0.16 -11 10/15 
920 61/67 very smooth 
3 0.16 -10 10/10 
940 52/60 very smooth 
4 0.16 -10 10/13 
70 24/42 very smooth 
5 0.16 -10 10/30 
370 27/32 very smooth 
6 0.16 -11 10/15 
1060 62/69 very smooth 
7 0.16 -24 10/15 
1080 58/62 smooth all 
over 
8 0.16 -8.1 
10/15 
720 63/67 smooth all 
over 
9 0.16 -17 10/10 
970 55/65 very smooth 
10 0.16 -10 10/15 
440 51/54 very smooth 
11 0.16 -13 10/15 
1730 56/63 very smooth 
12 0.16 -9.3 
10/15 
1150 14/40 smooth 
13 0.16 -15 10/20 
1230 24/58 very smooth 
14 0.16 -12 10/25 
1290 20/40 smooth 
15 0.16 -12 10/15 
1430 64/70 very smooth 
all over 
__________________________________________________________________________ 
In the following comparisons, the same general procedure was employed as 
was used in the preceding examples, and the tables which follow contain 
the same column headings as the tables above. Component C was varied in 
the comparisons and is listed for each comparison. 
TABLE 3 
__________________________________________________________________________ 
COM- OTHER MOLDED 
COM- 
COM- PO- ADDI- RELEASE 
GLOSS 
SURFACE 
- 
PONENT 
NENT TIVES CYCLE PRESSURE 
lowest/ 
APPEAR- 
ISON 
C (%) D (%) 
FILLER 
(%) .DELTA.H.sub.H /.DELTA.H.sub.c 
.DELTA.Tpk 
TIME (psi) highest 
ANCE 
__________________________________________________________________________ 
A NONE A(5.4) 
AA(25) 
X(0.6) 
About Not 10/15 2150 29/38 
very rough 
Y(0.3) 
0.4 Measured 
Talc(0.7) 
B Material 
NONE CC(25) 
N--stearyl 
Not 0 10/30 1440 13/23 
moderately 
Used in Erucamide 
Measured rough 
Examples Mold Re- surface 
2-15(5.5) lease 
Agent(0.9) 
C NONE E(10) 
CC(25) 
NONE About Not 10/30 had to 36/47 
rough 
0.5 Measured spray surface 
mold 
D Sodium 
NONE CC(25) 
Methyl 
Not Not 10/25 1590 16/23 
very rough 
Stearate Stearate 
Measured 
Measured surface 
(0.5) (0.53) 
E Material 
A(1.4)* 
CC(25) 
NONE 0.16 -3 10/30 1790 9/18 
smooth to 
Used in moderately 
Examples rough 
2-15(5.5) 
F Material 
E(5.0) 
CC(25) 
NONE About Not Sticking/ 
Spray 5/8 very rough 
Used in 0.45 Measured 
No molding 
Examples cycle 
2-15(0.35) established 
__________________________________________________________________________ 
*Amount is too small 
Although gloss values for some of the experiments in Table 3 is in the 
range of gloss values found for some of the Examples in Table 2, the 
surface roughness is not acceptable in the experiments of the Comparisons.