U.S. patent number 3,554,552 [Application Number 04/711,509] was granted by the patent office on 1971-01-12 for frangible article composed of polystyrene and polyethylene waxes.
This patent grant is currently assigned to The Dow Chemical Company. Invention is credited to John A. Barber, Floyd B. Nagle, Thomas E. Nixon.
United States Patent |
3,554,552 |
Nixon , et al. |
January 12, 1971 |
FRANGIBLE ARTICLE COMPOSED OF POLYSTYRENE AND POLYETHYLENE
WAXES
Abstract
The invention comprises fragile molded articles composed of
compositions of polystyrene and polyethylene waxes, together with a
lubricant or mold release agent, which articles are useful as
targets in the practice of skeet shooting.
Inventors: |
Nixon; Thomas E. (Midland,
MI), Barber; John A. (Midland, MI), Nagle; Floyd B.
(Midland, MI) |
Assignee: |
The Dow Chemical Company
(Midland, MI)
|
Family
ID: |
24858368 |
Appl.
No.: |
04/711,509 |
Filed: |
March 8, 1968 |
Current U.S.
Class: |
273/362;
273/DIG.2; 273/DIG.4; 524/300; 524/322; 524/528 |
Current CPC
Class: |
F41J
1/01 (20130101); C08L 25/06 (20130101); C08K
5/09 (20130101); C08K 5/09 (20130101); C08L
25/06 (20130101); C08L 25/06 (20130101); C08L
2666/04 (20130101); C08L 23/06 (20130101); Y10S
273/04 (20130101); Y10S 273/02 (20130101) |
Current International
Class: |
C08L
25/06 (20060101); C08L 25/00 (20060101); C08K
5/00 (20060101); C08K 5/09 (20060101); F41J
1/00 (20060101); F41J 1/01 (20060101); C08L
23/06 (20060101); C08L 23/00 (20060101); F41j
009/16 (); C08c 011/70 (); C08f 045/52 () |
Field of
Search: |
;272/56.6SS
;273/105.4,105.5,(Styrene Digest)/ ;273/(Ethylene Digest)/
;260/28.5A,(Inquired) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Oechsle; Anton O.
Assistant Examiner: Siskind; Marvin
Claims
We claim:
1. A fragile article of manufacture comprising a molding having
walls between 0.01 and 0.03 inch thick, prepared from a composition
consisting essentially of from 96.7 to 99.4 percent by weight of
polystyrene having a viscosity characteristic of from 12 to 30
centipoise as determined for a 30 weight percent solution of said
polystyrene in toluene at 25.degree. C., from 0.5 to 3 percent by
weight of a polyethylene having a viscosity between 2,000 and 6,000
centipoise at 121.degree. C., and from 0.01 to 0.03 percent by
weight of an aliphatic monocarboxylic acid having from 12 to 26
carbon atoms in the molecule.
2. An article as claimed in claim 1 containing an orange dye.
3. An article as claimed in claim 1 when in the form of a disc.
4. An article as claimed in claim 1 when in the form of a hollow
sphere.
5. An article of manufacture suitable for use as a target in
practice and competition shooting comprising a fragile hollow
sphere having walls between 0.01 and 0.03 inch thick prepared by
molding half sphere shells from a composition consisting
essentially of from 96.7 to 99.4 percent by weight of polystyrene
having a viscosity characteristic of from 10 to 30 centipoise as
determined for a 30 weight percent solution of said polystyrene in
toluene at 25.degree. C., from 0.5 to 3 percent by weight of a
polyethylene having a viscosity between 2,000 and 6,000 centipoise
at 121.degree. C. and from 0.01 to 0.03 percent by weight of an
aliphatic monocarboxylic acid having from 12 to 26 carbon atoms in
the molecule, and adhesively forming two half sphere shells to one
another.
6. An article as claimed in claim 5 containing an orange dye.
7. An article as claimed in claim 5 wherein the aliphatic
monocarboxylic acid is stearic acid.
8. An article as claimed in claim 5 wherein the aliphatic
monocarboxylic acid is behenic acid.
Description
This invention concerns fragile molded articles composed low
molecular weight polystyrene and polyethylene waxes, together with
a lubricant or mold release agent, which fragile articles are
suitable for use as targets in practice shooting.
It has now been found that compositions of low molecular weight
polystyrene and polyethylene waxes, together with a small amount of
a fatty acid sufficient to act as lubricant and mold release agent,
can readily be compression or injection molded to make fragile
articles suitable for use in practice shooting.
More specifically, the compositions consist essentially of from
96.7 to 99.4 percent by weight of the polystyrene, from 0.5 to 3.0
percent by weight of the polyethylene wax and from 0.1 to 0.3
percent by weight of a fatty acid having from 12 to 26 carbon atoms
in the molecule.
The polystyrene to be employed can have a molecular weight
corresponding to a viscosity characteristic of from about 12 to
about 30, preferably from 15 to 25, centipoise as determined for a
30 weight percent solution of the polystyrene in toluene at
25.degree. C.
The polyethylene wax can be a polyethylene having a molecular
weight of from about 2,000 to 4,000. Such polyethylenes have
(Brookfield) viscosities of from about 2,000 to 6,000 centipoise at
250.degree. F. 121.degree. C.)
The fatty acid can be an aliphatic monocarboxylic acid having from
12 to 26 carbon atoms in the molecule. Among suitable fatty acids
are lauric acid, myristic acid, palmitic acid, stearic acid,
arachidic acid, behenic acid, lignoceric acid and cerotic acid.
Mixtures of two or more of said fatty acids can also be used. The
fatty acids are preferably saturated aliphatic acids, but
monoethylenically unsaturated fatty acids such as dodecylenic,
palmitic, oleic, ricinoleic, petroselinic, vaccenic, linoleic,
linolenic, eleostearic, licanic, parinaric, tariric, gadoleic,
arachidonic, cetoleic, erucic or selacholeic, acid or mixtures
thereof with one another or with the aforementioned saturated fatty
acids can also be used.
The ingredients can be blended together in any usual way. For
example, the polystyrene in granular or powdered form, the
polyethylene in particulate or in finely powdered form and the
fatty acid, can be dry blended by tumbling a mixture of the
ingredients in the desired proportions in a suitable bender. The
mixture of ingredients can be dry blended, compounded or mixed on
compounding rolls, a Banbury mixer or in a plastics extruder.
In a preferred practice the ingredients are dry blended and fed to
a plastics extruder wherein the materials are heated, pressed and
mechanically worked and blended into a uniform product which is
then extruded and is cooled and cut to a granular form suitable for
molding.
In molding the compositions either the dry blended or the melt
blended mixture of ingredients is employed to compression,
injection, or screw injection mold said material into articles
suitable for a desired purpose, e.g. as discs or as half sphere
shells which are usually glued together to form balls suitable for
use as targets in practice shooting. It may be mentioned that for
use as targets two half sphere shells are adhered together by
adhesive or solvent softening of the edges to form spheres.
The walls of the moldings suitable for use as targets in practice
shooting usually have a thickness of from about 0.01 to 0.03 inch,
although somewhat greater or lesser wall thickness of the moldings
can be used to make fragile targets.
Small amounts of dyes, coloring agents, pigments and the like can
be incorporated into the compositions to make molded articles
prepared therefrom more visible, are not required.
The following example illustrates ways in which the principle of
the invention has been applied but is not to be construed as
limiting its scope.
EXAMPLE
A charge of 97.75 parts by weight of granular low molecular weight
polystyrene having a viscosity characteristic of 20.5 centipoise as
determined for a 30 weight percent solution of the polystyrene in
toluene at 25.degree. C. and which polystyrene had a weight average
molecular weight Mw of about 45,000 and a number average molecular
weight Mn of about 12,700 and 2 parts of "EPOLENE, " (a waxlike
polyethylene having a molecular weight of about 2,500 ), together
with 0.25 part of powdered stearic acid, was dry blended, then was
fed to a plastics extruder wherein the ingredients were heated,
melted and blended into a uniform composition and were extruded,
cooled and cut or broken to a granular form. Portions of the
product were compression molded at a temperature of about
150.degree. C. and 500 pounds per square inch pressure to form half
sphere shells 21/2 inches in diameter having walls 0.025 inch
thick. The molded half sphere shells were easily removed from the
mold without sticking or breakage. Two molded half shell spheres
were solvent welded to form a sphere. The spheres were fragile
objects, easily broken by dropping on the floor or by other impact.
Test specimens of the spheres were shot with No. 12 (mustard seed)
shot shells fired from a 22 caliber smooth bore gun and were found
to readily shatter into a great plurality of pieces upon being hit.
The fragile plastic spheres were useful targets for practice of
indoors shooting with pellets and fine shot.
In contrast, a similar formulation prepared from low molecular
weight polystyrene having a viscosity characteristic of 34.6
centipoise and an Mw of about 61,500 and a Mn of about 21,000 was
unsatisfactory.
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