Note: Descriptions are shown in the official language in which they were submitted.
AD-4940-A 11~3~'~3
TITLE
PRODUCT AND PROCESS
FIELD OF THE INVENTION
This invention relates to polyethylene
terephthalate resins useful in molding applications.
More particularly, this invention relates to
polyethylene terephthalate resins containing an
inorg~nic reinforclng or ~iller material.
B~CKGROUND
It is desirable to enhance the strength
o~ articles molded ~rom polyethylene terephthalate
resin by employing a reinforcing materialJ such as
glass fibers, asbestos ~ibers or other fibrous
mineral materials with a coupling agent, in
the resin. Furthermore, it is sometimes sufficient
to merely increase the modulus by use of a filler,
such aæ beads or a mineral of low aspect ratio, in
the resin. However, heretofore, it was necessary
to use very high mold temperatures, on the order
o~ 130C, to obtain molded articles from such
reinforced or filled resins which had a glossy surface
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and which were not rough in texture. If these high
mold temperatures were not employed, the molded
articles had a rough surface with poor gloss. It
is believed that the crystallization rate of poly-
ethylene terephthalate is too slow below about 130Cto result in a molded article having good surface
characteristics.
While good surface characteristics can
be obtained at molding temperatures of 130C or
more, the use of such temperatures is not pxactical
in the molding field, for most molds are heated
with water and attain temperatures of only about
85-110C.
A few molding devices employ heating means
such as oil to reach temperatures higher than 85-
110C but these generally are inconvenient to
use and still either do not generally reach such
temperatures or reach them unevenly because of
inadequate coring. Because of these heating problems,
it has proven commercially unattractive to employ
these high temperature molding devices with reinforced
or filled polyethylene terephthalate resins.
SUMMARY OF THE INVENTION
It is desirable to provide a
reinforced or filled polyethylene terephthalate
resin that can be molded at mold temperatures
below about 110C to produce a molded article
having a smooth and glossy surface. The reinforced
or filled polyethylene terephthalate resins of this
invention achieve the foregoing by having incorpor-
ated therein 1) a sodium or potassium salt of a
selected hy~rocarhon acid or a sodium or potassium
salt of a selected organic polymer containing
pendant carboxyl groups and 2) a selected low
molecular weight organic ester, ketone, sulfone,
11336~3
sulfoxide nitrile or amideO
Specific~lly the resins of this invention
are compositions consisting essentially of:
A. polyethylene terephthalate having an
lnherent viscosity of at least about 0.4;
B. between about 10 and about 60 percent
by weight reinforcing or filling material;
C. a material selected from a sodium or
potassium salt of a hydrocarbon aci~ containin~
between about 7 and 25 carbon atoms or a sodium
or potassium salt of an organic polymer which contains
pendant carboxyl groups said material present in
an amount sufficient to provide a ~H~j~HC ra~io of
less than 0.25 to a mixture of components A B and
C;
-D. a compound present in an amount
sufficient to provide a Tpk at least 4C lower than
the Tpk of a mixture of components A B and C
said compound being selected from
a) organic esters selected from
the product of an aromatic carboxylic acid of 7-11
carbon atoms containing at }east 1 carboxyl group
per aromatic nucleus and an alcohol selected from
~hose of the formula (HOCH2tXR wherein x is 1 2
25 or 3 and R is a hydrocarbon radical of 2-15 carbon
atoms (preferably 2-10 carbon atoms) or those of the
formula HO~Rn0tyRn wherein y is a cardinal number
between 1 ~ud 15 and preferably between 2 and 8
: R~ is a hydrocarbon radical of 2-15 carbon atoms
(preferably 2-8 carbon atoms~ and R ' is -H or a
. hydrocarbon radical of 2-20 carbon atoms (preferably
2-12 carbon atoms); or
b) organic ketones of the formula RCR .
c) organic sulfones of the formula RSOOR
d) organic sulfoxides of the formula R2SO
e) organi~ nitriles of the formula RCN or
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o
f) organic amides of the formula RCNR'R or
Jol
RSONR'R
wherein in formulas b) through f) each R can be the
same as or different from any other R and i8 a hydro-
carbyl group of 1-25 carbon atoms, while in the
formulas in f) R~ is hydrogen or a hydrocarbyl group
of 1-25 carbon atoms.
DESCRIPTION OF T B INVENTION
The polyethylene terephthalate em~loyed
herein is one which has an inherent viscosity of at
least O.4. The polyethylene terephthalate preferably
has an upper limit on inherent viscosity of about 1.2.
Inherent viscosity is measured at 30C using 0.5 g of
polyethylene terephthalate per 100 ml of a liquid that
is a mixture, at a 3:1 ratio by volume, of methylene
chloride and trifluoroacetic acid i.e. using the proce-
dure of ASTM D-2857. me 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 combina-
tions thereof as for example a mixture of mica andglass fibers.
Materials present in an amount sufficient
to cause the compositions of the inventi~n to have a
~HH/~HC ratio of less than 0.25 (component C defined
- 30 above~ include the sodium or potassium salts of hydro-
carbon 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 poly-
mers, such as copolymers of olefins and acrylic or
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methacrylic acids, or copolymers of aromatic olefins
and maleic anhydride. Preferably these materials
include the sodium or potassium salt of ~tearlc
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 co-
polymers 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 o'rganic 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
25 or more carboxyl groups, the carboxyl groups are all
reacted to form ester (COO) linkages, that is,
there will be no free carboxylgroups 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 (HOCH2)2-R' wherein R' is alkylene of
4-6 carbon atoms (preferably neopentyl glycol)
or HO(R"OtyH wherin R" is ethylene or propylene, and
y is 2 or 3.
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Preferred ketones, sulfanes, 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 di-
ethyleneglycol (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-fluorobenzo-
phenone (1.9), diphenyl sulfone (2.8), N-ethyl-o,p-
toluene gulfonamide (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 o~taining molded articles
of high sur~ace gloss at molding temperatures below
110C 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 re-
ducing 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
il33643
will result in a ~HH/~HC ratio of the composition
less than 0.25. To find the ~H~/~HC ratio, poly-
ethylene terephthalate is molded at 70C into 1/16"
thick bars. The bars are heated and at between
95C and 120C an exotherm (termed aHH) 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
(which is above its melting point) and the melted
sample cooled at 10C/minute. Another exotherm
at between about 200-220C (termed ~Hc) is the
exotherm recorded on freezing of the sample. It
has been found that the ~H/~HC 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 4C 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.
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In addition to the components discussed
hereinabove, the compositions of this invention
may contain additives commonly employed with poly-
ester 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-L.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 poly-
ethylene terephthalate can be mixe-d dry in any
suitable blender or tumbler with components B, C
and D and the mix~ure melt-extruded. The ~xtrudate
can be chopped and mixed with reinforcing agent
and then this mixture melt extruded. More con-
veniently, 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 in~ention. The ~HH/~HC
ratio and the Tpk were determined as described
above, while the gloss of molded sample was measured
with a Gardner Multi Angle Gloss (P~odel GG-9095)
set a~ a selected degree angle set forth in the
Examples.
Example l
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
113~ 3
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~C. The chopped
strands from the extruded melt were dried at about
110C 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
264C melt temperature. The AHH/~HC ratio was 0.06
and the Tpk was 12 less than the same composition
but without the benzophenone present. The
extruded strands were cooled and chopped and then
dried at about 110C for 16 hours in a vacuum
- oven. The dried chopped strands were molded in a
6 Z- injection molding machine at approximately
290C, with a fast ram, 20 seconds injection forward
time, and 20 seconds mold close ~ime and a 95C
cavity temperature. Gloss of the molded article
was very good. As determined with a Gardner Multi
Angle Gloss Meter,(Model GG-90~5) set at a twenty
degree angle the gloss registered 23. At a 70
cavity temperature gloss measured in the same
manner was 5.
EXAMPLES 2 TO 15 AND COMPARISONS A TO ~
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 c 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
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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~C and at a
vaccum of 28 inches. The extruded strand was cut
and the resulting resin pellets dried at 110C 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
thic~ness of 0.19 cm. Melt temperature in
the molding machine was 295C; while the surface
temperature of the mold was 85C. Cycle times
and release pressures are recited in the tables.
Gloss was measured at an angle of 60
by theGardner 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 t~bles 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 poly-
ethylene terephthalate employed. Percent amount
of filler or reinforcing agent and other additives
1:1336~1t3
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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-hydroxyhydrocinnamate)] methane
* denotes trade mark
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TABLE I
AMOUNT OF COMPONENT FILLER OT~ER ADDI-
COMPONENT D AND AND TIVES
EXAMPLE C !~) AMOUNT (%) AMOUNT(%) PRESENT(%~
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)
5.7 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)
5.8 D(4.3) CC(2S)SA2~E
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
5.7 I(3.7) ` CC(25) NONE
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TABLE 2
GLOSS AS
MOLDED(low-
RELEASE est value/ MOLDED
QHH/ CYCLE PRESSURE highest SURFACE
Ex. ~H~ aTpk 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
10 5 0.16 -10 i0/30 370 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
0.16 -10 1~/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
0.16 -12 10/15 1430 64/70 very smooth
all over
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. In the following comparisons, the same
general procedure was employed as was usefl 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 OTHER
COMPONENT COMPONENT ADDITIVES
COMPARISON C t~) D (%) FILLER ~%)
.
A NONE A~5.4) AA(25) X(0.6)
Y(0 3)
Talc(0.7)
B Material NONE CC(25) N-stearyl
Used in Erucamide
Examples Mold Re-
2-15(5.5) lease
Agent(0.9)
C NONE E(10) CC(25) NONE
D Sodium NONE CC(25) Methyl
Stearate Stearate
(0.5) (0.53)
E Material A(1.4)* CC(25) NONE
Used in
Examples
2-15(5.5)
F Material E(5.0) CC(25) NONE
Used in
Examples
2-15(0.35)*
* Amount is too small
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113361~3
TABLE~ 3 (Continued)
RELEASE GLOSS MOLDED
CYCLE PRESSURE lowest/ SURFACE
5 ~H /~H ~ TIME (PSi3 hlqhest APPEARANCE
--H --c
A About Not 10/15 2150 29/38 very rough
0.4 Measured
B Not 0 1~/30 144013/23moderately
10 Measured rough
surface
C About Not 10/30 had to 36/47rough
0.5 Measured spray surface
mold
D Not Not 10/25 159016/23very rough
Measured Measured surface
E 0.16 -3 10/30 17909/18 smooth to
moderately
rough
F About Not Sticking/ Spray 5/8 very rough5 0.45 Measured No molding cycle
established
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.
