U.S. patent application number 10/361342 was filed with the patent office on 2003-09-18 for stiff and impact resistant compositions containing poly(propylene) or poly(ethylene/propylene) and calcium carbonate for closures.
Invention is credited to Goldman, Anatoliy.
Application Number | 20030176548 10/361342 |
Document ID | / |
Family ID | 24462030 |
Filed Date | 2003-09-18 |
United States Patent
Application |
20030176548 |
Kind Code |
A1 |
Goldman, Anatoliy |
September 18, 2003 |
Stiff and impact resistant compositions containing poly(propylene)
or poly(ethylene/propylene) and calcium carbonate for closures
Abstract
Stiff and impact resistant closures derived from the stiff and
impact resistant blends including poly(propylene) or
poly(ethylene/propylene) and calcium carbonate; stiff and impact
resistant compositions including poly(propylene) or
poly(ethylene/propylene) and calcium carbonate; methods for
increasing stiffness and impact resistance of a poly(propylene) or
poly(ethylene/propylene) resin, or a closure; and a method for
measuring the impact strength of a closure or a resin at a reduced
temperature are disclosed. A presently preferred blend contains
from about 40 to about 60 weight percent of poly(propylene) or
poly(ethylene/propylene) and from about 25 to about 35 weight
percent of calcium carbonate particles treated with fatty acid, the
treated particles having a particle size of from about 2.5 to about
3.5 microns.
Inventors: |
Goldman, Anatoliy;
(Indianapolis, IN) |
Correspondence
Address: |
ALCOA INC
ALCOA TECHNICAL CENTER
100 TECHNICAL DRIVE
ALCOA CENTER
PA
15069-0001
US
|
Family ID: |
24462030 |
Appl. No.: |
10/361342 |
Filed: |
February 10, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10361342 |
Feb 10, 2003 |
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09614618 |
Jul 12, 2000 |
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6544609 |
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Current U.S.
Class: |
524/425 ;
523/210 |
Current CPC
Class: |
C08L 23/02 20130101;
B29C 48/40 20190201; B65D 41/34 20130101; B29C 48/00 20190201; C08K
9/04 20130101; B29C 48/12 20190201; Y10T 428/1352 20150115; B65D
41/0428 20130101; C08K 9/04 20130101 |
Class at
Publication: |
524/425 ;
523/210 |
International
Class: |
C08K 009/12; C08K
003/26 |
Claims
I claim:
1. A closure for a container comprising a top and a depending
shell, said closure is formed of a stiff and impact resistant
polymeric blend having from about 40 to about 60 weight percent of
a polymer selected from the group consisting of poly(propylene) and
poly(ethylene/propylene); and from about 25 to about 35 weight
percent of calcium carbonate particles treated with fatty acid,
wherein said calcium carbonate particles have a particle size of
from about 2.5 to about 3.5 microns, wherein said closure has a
falling weight impact resistance at -20.degree. C. of from about
0.4 to about 2.5 joules and a stiffness at room temperature of from
about 1800 to about 2200 megapascals.
2. A closure for a container comprising a top and a depending
shell, said closure is formed of a stiff and impact resistant
polymeric blend having from about 40 to about 60 weight percent of
a polymer selected from the group consisting of poly(propylene) and
poly(ethylene/propylene) and from about 25 to about 35 weight
percent of calcium carbonate particles treated with fatty acid,
wherein said calcium carbonate particles have a particle size of
from about 2.5 to about 3.5 microns, wherein said closure has a
falling weight impact resistance at room temperature of from about
0.8 to about 4.0 joules and a stiffness at room temperature of from
about 1800 to about 2200 megapascals.
3. A closure for a container comprising a top and a depending
shell, said closure is formed of a stiff and impact resistant
polymeric blend having from about 40 to about 60 weight percent of
a polymer selected from the group consisting of poly(propylene) and
poly(ethylene/propylene) and from about 25 to about 35 weight
percent of calcium carbonate particles treated with fatty acid,
wherein said calcium carbonate particles have a particle size of
from about 2.5 to about 3.5 microns, wherein said closure has a
falling weight impact resistance at -20.degree. C. of from about
0.4 to about 2.5 joules, a falling weight impact resistance at room
temperature of from about 0.8 to about 4.0 joules and a stiffness
at room temperature of from about 1800 to about 2200
megapascals.
4. A method of increasing stiffness and impact resistance in a
closure comprising the steps of: a) making a stiff and impact
resistant polymeric blend by compounding from about 40 to about 60
weight percent of a polymer selected from the group consisting of
poly(propylene) and poly(ethylene/propylene) with from about 25 to
about 35 weight percent of calcium carbonate particles treated with
fatty acid, wherein said calcium carbonate particles have a
particle size of from about 2.5 to about 3.5 microns; and then, b)
molding said blend into a closure.
5. The method of claim 4 wherein said compounding is carried out in
an extruder at a die temperature of 350-425.degree. F., a rate of
20-40 lbs/hr and a screw speed of 200-500 rpm to obtain good
dispersion of said calcium carbonate particles.
6. The method of claim 5 wherein said extruder is a twin screw
extruder having at least a first temperature zone, a second
temperature zone, a third temperature zone and a fourth temperature
zone.
7. The method of claim 6 wherein said first, second, third and
fourth temperature zones are each 400.degree. F.
8. A stiff and impact resistant polymeric composition comprising:
from about 40 to about 60 weight percent of a polymer selected from
the group consisting of poly(propylene) and
poly(ethylene/propylene); and, from about 25 to about 35 weight
percent of calcium carbonate particles treated with fatty acid,
wherein said calcium carbonate particles have a particle size of
from about 2.5 to about 3.5 microns, wherein said composition has a
falling weight impact resistance at -20.degree. C. of from about
0.4 to about 2.5 joules and a stiffness at room temperature of from
about 1800 to about 2200 megapascals.
9. The composition of claim 8 wherein said fatty acid is stearic
acid.
10. The composition of claim 8 further comprising at least one
additive selected from the group consisting of pigments,
lubricants, anti-oxidants, emulsifiers and a combination
thereof.
11. A stiff and impact resistant polymeric composition comprising:
from about 40 to about 60 weight percent of a polymer selected from
the group consisting of poly(propylene) and
poly(ethylene/propylene); and, from about 25 to about 35 weight
percent of calcium carbonate particles treated with fatty acid,
wherein said calcium carbonate particles have a particle size of
from about 2.5 to about 3.5 microns, wherein said composition has a
falling weight impact resistance at room temperature of from about
0.8 to about 4.0 joules and a stiffness at room temperature of from
about 1800 to about 2200 megapascals.
12. The composition of claim 11 wherein said fatty acid is stearic
acid.
13. The composition of claim 11 further comprising at least one
additive selected from the group consisting of pigments,
lubricants, anti-oxidants, emulsifiers and a combination
thereof.
14. A stiff and impact resistant polymeric composition comprising:
from about 40 to about 60 weight percent of a polymer selected from
the group consisting of poly(propylene) and
poly(ethylene/propylene); and, from about 25 to about 35 weight
percent of calcium carbonate particles treated with fatty acid,
wherein said calcium carbonate particles have a particle size of
from about 2.5 to about 3.5 microns, wherein said composition has
an impact resistance at -20.degree. C. of from about 0.4 to about
2.5 joules, a falling weight impact resistance at room temperature
of from about 0.8 to about 4.0 joules and a stiffness at room
temperature of from about 1800 to about 2200 megapascals.
15. The composition of claim 14 wherein said fatty acid is stearic
acid.
16. The composition of claim 14 further comprising at least one
additive selected from the group consisting of pigments,
lubricants, anti-oxidants, emulsifiers and a combination
thereof.
17. A method for increasing the impact strength and stiffness of a
polypropylene or poly(ethylene/propylene) resin comprising the step
of compounding from about 40 to about 60 weight percent of said
resin with from about 25 to about 35 weight percent of calcium
carbonate particles treated with fatty acid, wherein said calcium
carbonate particles have a particle size of from about 2.5 to about
3.5 microns.
18. The method of claim 17 wherein said impact strength to be
improved is room temperature impact strength, cold temperature
impact strength, or both room temperature impact strength and cold
temperature impact strength.
19. The method of claim 17 wherein said compounding is carried out
in an extruder at a die temperature of 350-425.degree. F., a rate
of 20-40 lbs/hr and a screw speed of 200-500 rpm to obtain good
dispersion of said calcium carbonate particles.
20. The method of claim 19 wherein said extruder is a twin screw
extruder having at least a first temperature zone, a second
temperature zone, a third temperature zone and a fourth temperature
zone.
21. The method of claim 20 wherein said first, second, third and
fourth temperature zones are each 400.degree. F.
22. A method for measuring impact resistance of a closure at a
reduced temperature comprising the steps of: a) conditioning a
closure for forty hours at 23.degree. C. and 50% relative humidity
according to ASTM D-4101 to produce a conditioned closure; b)
acclimating said conditioned closure for two hours at a reduced
temperature to produce an acclimated closure; and then, c)
measuring impact resistance of said acclimated closure by the
falling weight impact test according to ASTM D-5628-94.
23. The method of claim 22 wherein said reduced temperature is
selected from the group consisting of 0.degree. C., -20.degree. C.
and -40.degree. C.
Description
FIELD OF THE INVENTION
[0001] The invention is directed to stiff and impact resistant
closures derived from the stiff and impact resistant blends
including poly(propylene) or poly(ethylene/propylene) and calcium
carbonate; stiff and impact resistant compositions including
poly(propylene) or poly(ethylene/propylene) and calcium carbonate;
methods for increasing stiffness and impact resistance of a
poly(propylene) or poly(ethylene/propylene) resin, or a closure;
and a method for measuring the impact strength of a closure or a
resin at a reduced temperature. A presently preferred blend
contains from about 40 to about 60 weight percent of
poly(propylene) or poly(ethylene/propylene) and from about 25 to
about 35 weight percent of calcium carbonate particles treated with
fatty acid, the treated particles having a particle size of from
about 2.5 to about 3.5 microns.
BACKGROUND OF THE INVENTION
[0002] Polymers such as polypropylene or polymers formed from the
polymerization of propylene and at least one other monomer have
been utilized extensively for making closures. It is desirable to
have a stiff and impact resistant closure, both at room
temperature, as well as at reduced temperature. Properties of
increased stiffness and increased impact resistance are
advantageous for any structural materials, to avoid cracking when
the structural materials are impacted.
[0003] The properties of the closure at reduced temperature are
important when closures are to be used on containers stored at
reduced temperatures, or when closures are destined to be used on
containers for use in cooler climates. Therefore, improvements in
closures made from compositions including polypropylene have
focused on increasing the stiffness and the impact strength of the
polymer. However, when one of these properties is improved, the
other is usually worsened. For example, when stiffness is
increased, impact strength normally is decreased. It would be very
useful to be able to improve both of these characteristics at the
same time.
[0004] I have now discovered that a conventional filler for
polymeric compositions, of a certain particle size and in a certain
proportion, may surprisingly provide the highly desirable result of
improving both impact strength and stiffness of the polymeric
composition to which it is added. This additive is calcium
carbonate, used as a filler in polymeric compositions.
[0005] Inorganic fillers such as calcium carbonate are frequently
added to polymers. Examples of other fillers include talc, kaolin,
clays, silica, alumina, mica, carbon black, TiO.sub.2, ZnO and
Sb.sub.2O.sub.3. Conventionally, calcium carbonate is utilized as a
filler for resins such as polypropylene. When improved impact
resistance is desired, other additives to achieve this property are
introduced, such as rubber. Therefore, although calcium carbonate
has been utilized as an additive to reduce the cost of a resin, it
has not been considered to be useful for the improvement of both
stiffness and impact resistance of a resin. Moreover, addition of
calcium carbonate to a resin has not been considered to improve
impact resistance both at room temperature and at reduced
temperature.
[0006] Therefore, a polymeric composition for use in making
closures which has both improved stiffness and improved impact
resistance would be desirable.
SUMMARY OF THE INVENTION
[0007] The invention is directed to a closure for a container
comprising a top and a depending shell, said closure is formed of a
stiff and impact resistant polymeric blend having from about 40 to
about 60 weight percent of a polymer selected from the group
consisting of poly(propylene) and poly(ethylene/propylene); and
from about 25 to about 35 weight percent of calcium carbonate
particles treated with fatty acid, wherein said calcium carbonate
particles have a particle size of from about 2.5 to about 3.5
microns, wherein said closure has a falling weight impact
resistance at -20.degree. C. of from about 0.4 to about 2.5 joules
and a stiffness at room temperature of from about 1800 to about
2200 megapascals.
[0008] The invention is also directed to a closure for a container
comprising a top and a depending shell, said closure is formed of a
stiff and impact resistant polymeric blend having from about 40 to
about 60 weight percent of a polymer selected from the group
consisting of poly(propylene) and poly(ethylene/propylene) and from
about 25 to about 35 weight percent of calcium carbonate particles
treated with fatty acid, wherein said calcium carbonate particles
have a particle size of from about 2.5 to about 3.5 microns,
wherein said closure has a falling weight impact resistance at room
temperature of from about 0.8 to about 4.0 joules and a stiffness
at room temperature of from about 1800 to about 2200
megapascals.
[0009] The invention is also directed to a closure for a container
comprising a top and a depending shell, said closure is formed of a
stiff and impact resistant polymeric blend having from about 40 to
about 60 weight percent of a polymer selected from the group
consisting of poly(propylene) and poly(ethylene/propylene) and from
about 25 to about 35 weight percent of calcium carbonate particles
treated with fatty acid, wherein said calcium carbonate particles
have a particle size of from about 2.5 to about 3.5 microns,
wherein said closure has a falling weight impact resistance at
-20.degree. C. of from about 0.4 to about 2.5 joules, a falling
weight impact resistance at room temperature of from about 0.8 to
about 4.0 joules and a stiffness at room temperature of from about
1800 to about 2200 megapascals.
[0010] The invention is also directed to a method of increasing
stiffness and impact resistance in a closure comprising the steps
of:
[0011] a) making a stiff and impact resistant polymeric blend
by
[0012] compounding from about 40 to about 60 weight percent of a
polymer selected from the group consisting of poly(propylene) and
poly(ethylene/propylene) with
[0013] from about 25 to about 35 weight percent of calcium
carbonate particles treated with fatty acid, wherein said calcium
carbonate particles have a particle size of from about 2.5 to about
3.5 microns; and then,
[0014] b) molding said blend into a closure.
[0015] The invention is also directed to a stiff and impact
resistant polymeric composition comprising:
[0016] from about 40 to about 60 weight percent of a polymer
selected from the group consisting of poly(propylene) and
poly(ethylene/propylene); and,
[0017] from about 25 to about 35 weight percent of calcium
carbonate particles treated with fatty acid, wherein said calcium
carbonate particles have a particle size of from about 2.5 to about
3.5 microns,
[0018] wherein said composition has a falling weight impact
resistance at -20.degree. C. of from about 0.4 to about 2.5 joules
and a stiffness at room temperature of from about 1800 to about
2200 megapascals.
[0019] Such a composition is very useful as a structural material
for a closure. The invention is also directed to a stiff and impact
resistant polymeric composition comprising:
[0020] from about 40 to about 60 weight percent of a polymer
selected from the group consisting of poly(propylene) and
poly(ethylene/propylene); and,
[0021] from about 25 to about 35 weight percent of calcium
carbonate particles treated with fatty acid, wherein said calcium
carbonate particles have a particle size of from about 2.5 to about
3.5 microns,
[0022] wherein said composition has a falling weight impact
resistance at room temperature of from about 0.8 to about 4.0
joules and a stiffness at room temperature of from about 1800 to
about 2200 megapascals.
[0023] The invention is also directed to a stiff and impact
resistant polymeric composition comprising:
[0024] from about 40 to about 60 weight percent of a polymer
selected from the group consisting of poly(propylene) and
poly(ethylene/propylene); and,
[0025] from about 25 to about 35 weight percent of calcium
carbonate particles treated with fatty acid, wherein said calcium
carbonate particles have a particle size of from about 2.5 to about
3.5 microns,
[0026] wherein said composition has a falling weight impact
resistance at -20.degree. C. of from about 0.4 to about 2.5 joules,
an impact resistance at room temperature of from about 0.8 to about
4.0 joules and a stiffness at room temperature of from about 1800
to about 2200 megapascals.
[0027] For any of the above-mentioned compositions, the fatty acid
may be stearic acid; and the compositions may also include at least
one additive such as pigments, lubricants, anti-oxidants,
emulsifiers and a combination thereof. The compositions described
above may be used to manufacture any product wherein structural
materials having increased stiffness and impact resistance is
desirable, such as automobile parts, containers, or laundry tubs
among others; in addition to the closures described herein.
[0028] The invention is also directed to a method for increasing
the impact strength and stiffness of a polypropylene or
poly(ethylene/propylene) resin comprising the step of
[0029] compounding from about 40 to about 60 weight percent of said
resin with from about 25 to about 35 weight percent of calcium
carbonate particles treated with fatty acid, wherein said calcium
carbonate particles have a particle size of from about 2.5 to about
3.5 microns.
[0030] The impact strength of the above-mentioned method may be
room temperature impact strength, cold temperature impact strength,
or room temperature impact strength and cold temperature impact
strength.
[0031] In the methods described above, the compounding may be
carried out in an extruder at a die temperature of 350-425.degree.
F., a rate of 20-40 lbs/hr and a screw speed of 200-500 rpm to
obtain good dispersion of the calcium carbonate particles; and the
extruder may be a twin screw extruder having at least a first
temperature zone, a second temperature zone, a third temperature
zone and a fourth temperature zone. The first, second, third and
fourth temperature zones may each be maintained at a temperature of
400.degree. F.
[0032] The invention is also directed to a method for measuring
impact strength of a closure at a reduced temperature comprising
the steps of:
[0033] a) conditioning a closure for forty hours at 23.degree. C.
and 50% relative humidity according to ASTM D-4101 to produce a
conditioned closure;
[0034] b) acclimating said conditioned closure for two hours at a
reduced temperature to produce an acclimated closure; and then,
[0035] c) measuring impact resistance of said acclimated closure by
the falling weight impact test according to ASTM D-5628-94.
[0036] The reduced temperature for the method described above may
be 0.degree. C., -20.degree. C. or -40.degree. C.
DETAILED DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is a cross-sectional view of a plastic closure
embodying the principles of the present invention; and
[0038] FIG. 2 is an enlarged, fragmentary view of the closure shown
in FIG. 1 illustrated with an associated container.
[0039] FIG. 3 shows the dependence of Youngs' Modulus on the amount
of calcium carbonate in compositions at ambient temperature.
[0040] FIG. 4 shows the dependence of Youngs' Modulus on the amount
of calcium carbonate in compositions at 42.degree. C.
DETAILED DESCRIPTION OF THE INVENTION
The Resins
[0041] Polyolefins such as polyethylene, polypropylene or
copolymers formed from propylene or ethylene with at least a second
monomer may be utilized in the closure compositions. Polypropylene
is a particularly preferred resin. Combinations of any of the
above-mentioned polyolefins may also be utilized.
[0042] Preferably, the polymer is from about 40 to 60 weight
percent of the polymeric composition. Polymers such as
poly(propylene) or poly(ethylene/propylene) are presently
preferred.
Calcium Carbonate
[0043] Calcium carbonate is obtained from a natural source,
limestone. Most of the commercially mined deposits of calcium
carbonate originated in the form of fossil shells in marine
environment. The purity of the deposit is governed by the level of
impurities in the marine environment. The majority of limestone
deposits occur with silicas or clay-like muds, and thus are not
suitable as high brightness fillers. Furthermore, many deposits
react with magnesium compounds to form Dolomite, a calcium
magnesium carbonate. Deposits are found in the U.S. in Vermont,
Maryland, Georgia, Alabama and Southern California.
[0044] The calcium carbonate particles for use in the polymeric
compositions of the present invention are treated with a fatty
acid, to coat the particles. Upon treating the calcium carbonate
particles with fatty acid, they become partially coated. This
partial coating helps prevent agglomeration, and facilitates good
dispersion throughout the composition. A useful fatty acid is
stearic acid. Calcium carbonate particles having a particle size of
from about 2.5 to about 3.5 microns are presently preferred. Such
particles are available from several sources. The use of larger
particles, such as those of from about 4.5 to about 6.0 microns is
undesirable, as they have a tendency to agglomerate. Preferably,
the coated calcium particles are from about 25% to about 35% by
weight of the polymeric composition.
Other Constituents
[0045] The improved polymeric compositions including the polymer
(polypropylene, a copolymer of propylene and at least one other
monomer, or a combination of polypropylene with a copolymer of
propylene and at least one other monomer) and calcium carbonate may
also include other additives such as pigments, anti-oxidants,
lubricants, or emulsifiers.
[0046] Pigments may be added to the closure compositions. In order
to color the closure, or render it opaque, white pigments such
titanium dioxide may be added; color pigments such as carbon black,
red iron oxide, tartrazine lake or ultramarine blue (ULTRAMARINE
BLUE NUBIX E-25, available from Clariant) may be added.
Microencapsuled pigments may be particularly advantageous. Pigment
is usually from about 0.2% to about 0.8% of the total
composition.
[0047] Lubricants may also be added to the polymeric composition.
Either single lubricants, or a combination of lubricants may be
utilized.
[0048] The lubricants to be used in conjunction with the polymeric
compositions may be erucamide; aliphatic hydrocarbon lubricants
such as liquid paraffin, white mineral oils of industrial grade,
synthetic paraffin, petroleum wax, petrolatum and odorless light
hydrocarbons; silicones such as organopolysiloxanes; higher
saturated fatty acids obtained from vegetable and animal oils and
fats and hydrogenation products thereof, having 8 to 22 carbon
atoms; hydroxystearic acid; linear aliphatic monohydric alcohols
having at least 4 carbon atoms, obtained by reducing animal and
vegetable oils and saturated fats or by cracking distillation of
natural waxes; dodecyl alcohol, polyglycols such as polyethylene
glycols having a molecular weight of 200 to 9500, polypropylene
glycols having a molecular weight of at least 1000, and
polyoxypropylene-polyoxyethylene block copolymers having a
molecular weight of 1900 to 9000; alkali metal, alkaline earth
metal, zinc or aluminum salts of higher saturated fatty acids;
various metal soaps; low molecular weight olefin resins such as low
molecular weight polyethylene, low molecular weight polypropylene
and oxidized polyethylene; fluorine resins such as
polytetrafluoroethylene, tetrafluoroethylene/hexafluoropro- pylene
copolymer, polychlorotrifluoroethylene and polyvinyl fluoride;
propylene glycol alginate, dialkyl ketone and acrylic copolymers
among others.
[0049] Other lubricants include amides or amines such as higher
fatty acid amides, 2-steroamidoethyl stearate,
ethylene-bis-saturated fatty acid amides,
N,N'-bis-(2-hydroxyethyl)-alkyl amides having 12 to 18 carbon atoms
in the alkyl group; N.N'-bis(hydroxyethyl)-lauroamide, fatty acid
diethanolamines and distearic acid esters of
di(hydroxyethyl)-diethylene triamine monoacetate, fatty acid esters
of monohydric or polyhydric alcohols such as n-butyl stearate,
methyl ester of hydrogenated rosin, di-n-butyl sebacate,
2-ethylhexyl sebacate, octyl sebacate, glycerin fatty acid ester,
stearic acid ester of pentaerythritol, pentaerythritol
tetrastearate, sorbitan fatty acid ester, polyethylene glycol fatty
acid ester, polyethylene glycol monostearate, polyethylene glycol
dilaurate, polyethylene glycol monooleate, polyethylene glycol
dioleate, polyethylene glycol coconut fatty acid ester,
polyethylene glycol tall oil fatty acid ester, 1,3-butanediol
diethylene glycol stearate and propylene glycol fatty acid ester
among others, triglycerides and waxes such as hydrogenated edible
oils and fats; cotton seed oil and other edible oils; linseed oil;
palm oil; glycerin ester of 12-hydroxystearic acid; hydrogenated
fish oils; beef tallow; spermaceti wax; montan wax; carnauba wax;
bees' wax; haze wax; esters of monohydric aliphatic alcohols with
aliphatic saturated acids such as hardened whale oil, lauryl
stearate and stearyl stearate and lanoline among others.
[0050] The lubricant may be incorporated in an amount of 0.01 to
1.5% by weight, preferably 0.2 to 1% by weight, and especially
preferably 0.4 to 0.5% by weight in the closure composition, based
on the base resin. When the amount of the lubricant is too small
and below this range, the opening torque becomes too high and the
opening operation is difficult. When the amount of lubricant is too
large and exceeds the above range, the application torque is too
low, causing insufficient sealing.
[0051] Useful anti-oxidants include ascorbic acid; iso-ascorbic
acid; gallic acid; tocopherol; hydroquinone; catechol; resorcine;
dibutylhydroxytoluene; dibutylhydroxyanisole; pyrogallol;
hydroxyphenylpropionates such as
tetrakismethylene(3,5-di-t-butyl-4'-hydr- oxyphenyl propionate;
alkyl phenols such as 2,6-di-tert-butyl-4-methylphen- ol;
hydroxybenzyl compounds such as
tris(3,5-di-t-butyl-4-hydroxybenzyl)is- ocyanurate; alkylidene
bisphenols such as 2,2'-methylene-bis(4-methyl-6-t-- butylphenol);
phosphites and phosphonites such as bis(2,4-di-tert-butylphe- nyl)
pentaerythritol diphosphite; sorbose; glucose; lignin; iron based
anti-oxidants such as iron powder, activated iron, ferrous oxide
and iron salt; inorganic anti-oxidants such as sulfite,
thiosulfite, dithionite and hydrogen sulfite; polymers such as
redox resins and polymer-metal complexes; zeolites; activated
carbon or salts thereof among others. Combinations of the
above-mentioned anti-oxidants will also have utility in the present
closure compositions. Furthermore, useful anti-oxidants may contain
catalysts, water-retentive agents or hydrates.
[0052] Preferably, the anti-oxidants are present in the closure
composition in an amount of from about 0.1 to about 3% weight
percent, more preferably in an amount of from about 0.2% to 2%
weight percent, and most preferably in an amount of from about 0.5
to 1.5 weight percent.
[0053] When two anti-oxidants are used together in the closure
compositions, the ratio of the first anti-oxidant to the second
anti-oxidant is from about 1:5 to about 5:1, preferably from about
1:3 to about 3:1 and most preferably from about 1:2 to about
2:1.
[0054] Emulsifiers may be added to the closure compositions.
Appropriate emulsifiers include non-toxic, non-ionic surfactants
which are virtually tasteless at the concentrations employed, or at
least devoid of any unpleasant or undesired taste. Examples are
sorbitan polyoxyethylene fatty acid esters such as sorbitan
polyethylene (20) mono-oleate (TWEEN 80).
The Method of Making the Composition
[0055] To make the polymeric composition of the present invention,
polymer pellets were pre-mixed with calcium carbonate powder in the
molten state in a 30 mm Werner and Pfleider twin screw extruder.
The extrusion-mixing process was performed with a special screw
design, so that the filler will be well-dispersed. A representative
screw design, and mixing requirements for polymer compounding, are
disclosed in "The Werner & Pfleiderer Twin-Screw Co-Rotating
Extruder System" in Plastics Compounding, D. B. Todd Ed.,
Hanser/Gardner Publications, Inc., Cincinnati, 1998, pp. 94 and 95,
hereby incorporated by reference.
[0056] The polymeric compositions may be formed by compounding
coated calcium carbonate particles with the appropriate polymer.
The compounding may be done in a twin screw extruder having four
temperature zones along the barrel of the extruder. In general,
compounding is carried out in a twin screw extruder at a die
temperature of 350-425.degree. F., a rate of 20-40 lbs/hr and a
screw speed of 200-500 rpm. As a specific example of the
compounding process, each of the four zones of the twin screw
extruder may be held at a temperature of 400.degree. F.; while the
die temperature may be held at a temperature of 380.degree. F. The
rate may be 30 lbs/hr and the screw speed may be 322 rpm.
Compounding should be performed at appropriate shear and
temperature conditions such that blending occurs, but the polymer
is not degraded.
The Closures
[0057] The compositions described above may be utilized to form
closures. A presently preferred closure is described as
follows.
[0058] While the present invention is susceptible of embodiment in
various forms, there is shown in the drawings and will hereinafter
be described a embodiment, with the understanding that the present
disclosure is to be considered as an exemplification of the
invention and is not intended to limit the invention to the
specific embodiment illustrated.
[0059] With reference to FIGS. 1 and 2, therein is shown a
container closure 10 which is used in conjunction with an
associated container C. The closure includes a circular top wall
portion 12, and a depending annular skirt portion 14. The closure
includes an internal thread formation 16 on the skirt portion 14
for threaded cooperation with a thread formation on the associated
container C.
[0060] In order to facilitate venting of gas pressure from within
an associated container, the skirt portion 14 of the closure 10
defines a plurality of axially extending vent grooves 18.
[0061] In the illustrated embodiment, the closure 10 is configured
for tamper-indication, and accordingly, includes an annular pilfer
band 20 which depends from, and is at least partially frangibly
connected to skirt portion 14. The pilfer band includes an annular
band portion 22 which is distinguished from the skirt portion 14 by
a circumferentially extending score 24 which separates the pilfer
band from the skirt portion. A plurality of circumferentially
spaced frangible bridges 26 extend between the inside surfaces of
the skirt portion and pilfer band to provide the desired frangible
connection therebetween.
[0062] In the illustrated embodiment, the pilfer band 20 of the
closure 10 is configured in accordance with the teachings of U.S.
Pat. No. 4,938,370, to McBride, hereby incorporated by reference.
Accordingly, the illustrated pilfer band includes a plurality of
circumferentially space, inwardly extending flexible projections 28
which are configured for cooperative engagement with the annular
locking ring of the associated container C. The pilfer band of the
closure 10 may be otherwise configured, such as in accordance with
the teachings of U.S. Pat. No. 4,418,828, to Wilde et al., hereby
incorporated by reference.
[0063] The illustrated closure 10 is of a linerless construction,
that is, the closure does not include a sealing liner component or
like element positioned near or adjacent to the top wall portion 12
for sealing engagement with an associated container. Rather, the
closure includes an integral and unitary annular sealing lip 30
which projects inwardly generally from the juncture of top wall
portion 12 and skirt portion 14. Annular sealing lip 30 is
configured for resiliently flexible engagement with the associated
container C, as shown in FIG. 2. The desired sealing cooperation
between the sealing lip and the container is enhanced by the
provision of an annular stop element 32 which depends from top wall
portion 12 of the closure 10. As illustrated in FIG. 2, flexible
sealing lip 30 is urged upwardly against the stop element 32 as the
closure 10 is applied to the associated container C, with the stop
element thus cooperating with the sealing lip to urge the sealing
lip into sealing cooperation with the container C.
Making Closures from the Polymeric Compositions
[0064] Closures can be made from the polymeric blends of the
present invention by compression molding on a 54-station rotary
compression molding machine (HC-8A), for example. Test samples were
made by injection molding the compositions on a Cincinnati Milacron
Vista/Sentry machine. Appropriate temperatures and pressures can be
determined by those skilled in the art.
[0065] The following Examples are presented to describe the
preferred embodiments and utilities of the invention and are not
meant to limit the invention unless otherwise stated in the claims
appended hereto.
EXAMPLE 1
[0066] A DSC Perkin-Elmer Thermal analysis TAC/7DX was utilized to
determine the thermal properties of the compositions.
Crystallization and melting temperature were obtained for the
compositions using calcium carbonate from different sources, each
approximately of three micron particle size.
[0067] Test samples for each of these Examples were prepared in the
following manner. Different blends of polymer and calcium carbonate
were prepared using polypropylene homopolymer (PP, density=0.91
g/cm.sup.3, available from Phillips Petroleum Co. or Fina Co.) or a
random copolymer of ethylene and propylene (available from
available from Phillips Petroleum Co. or Fina Co., density=0.90
g/cm.sup.3) and 0.15 to 0.40 weight percent of calcium carbonate.
Three types of calcium carbonate were utilized: 1) 0.7 micron from
OMYA Corporation of Alpharetta, Ga.; 2) 1.4 microns from OMYA
Corporation of Alpharetta, Ga.; and 3) 3.0 microns from Micro
Minerals USA, Talc Co. of Norway, Polar Minerals of Mount Vernon,
Ind. or Georgia Marble Co. of Kennesaw, Ga. All particles were
surface-treated with a fatty acid to improve dispersion. Samples
for physical and mechanical testing were prepared by a Cincinnati
Milacron injection molding machine.
[0068] Table 1 shows that the calcium carbonate strongly influences
the kinetics of polypropylene crystallization by decreasing
crystallization temperature (T.sub.c) more than 5-10.degree. C. A
decreased crystallization temperature means that the polymeric
material, blend, or closure formed from the polymeric material or
blend will be more ductile and have an increased impact
resistance.
[0069] This is a remarkable result, in that polypropylene additives
conventionally increase crystallization temperature, due to a
nucleation effect. For example, talc is a conventional filler. When
it is added to polypropylene, T.sub.c increases since talc acts as
a nucleating agent, as shown in Table 2. The increased T.sub.c
indicates a decreased impact resistance for closures made from the
compositions with talc added.
1TABLE 1 DSC Crystallization and Melting Data for
Polypropylene/CaCO.sub.3 Blends Having Different Grades of
CaCO.sub.3 Crystallization T.sub.c Melting T.sub.m Composition
(.degree. C.) (.degree. C.) Blend (weight %) Onset T.sub.c T.sub.c
Peak Onset Peak PP.sup.1 100% 130.67 126.80 159.13 164.42
PP.sup.1/CaCO.sub.3.sup.2 85:15 120.04 115.72 155.47 161.6
PP.sup.1/CaCO.sub.3.sub.2 80:20 120.10 115.97 155.43 161.08
PP.sup.1/CaCO.sub.3.sub.2 75:25 120.22 116.22 155.09 160.50
PP.sup.1/CaCO.sub.3.sub.2 70:30 120.51 116.72 155.79 160.42
PP.sup.1/CaCO.sub.3.sub.2 60:40 120.93 117.93 155.79 160.58
PP.sub.1/CaCO.sub.3.sub.3 85:15 123.11 119.38 155.25 161.50
PP.sub.1/CaCO.sub.3.sub.3 75:25 124.37 120.88 156.73 161.67
PP.sub.1/CaCO.sub.3.sub.3 60:40 124.29 121.05 157.10 161.25
PP.sub.1/CaCO.sub.3.sub.4 95:5 129.02 125.47 159.61 163.58
PP.sub.1/CaCO.sub.3.sub.4 90:10 125.87 122.27 158.26 162.50
PP.sub.1/CaCO.sub.3.sub.4 85:15 125.68 122.13 158.67 162.58
PP.sub.1/CaCO.sub.3.sub.4 80:20 125.02 121.38 158.42 162.25
PP.sub.1/CaCO.sub.3.sub.4 75:25 124.96 121.22 158.60 162.58
PP.sub.1/CaCO.sub.3.sub.4 70:30 124.75 121.05 157.94 162.58
PP.sub.1/CaCO.sub.3.sub.4 65:35 124.08 120.13 157.43 161.50 .sup.1=
polypropylene homopolymer .sup.2= calcium carbonate C-11, available
from Georgia Marble, 3.mu. particle size. .sup.3= calcium carbonate
available from Polar Minerals Co., 3-3.5.mu. particle size. .sup.4=
calcium carbonate Microdol Extra, available from Micro Mineral USA
and Talc Co. of Norway, 3.mu. particle size.
[0070]
2TABLE 2 DSC Crystallization Data for Polypropylene Blended with
Filler Talc Talc T.sub.c (% by weight) (.degree. C.) 15 123.204 5
122.131 2 121.103 0.5 117.526 0.1 116.241 none 115.319
EXAMPLE 2
[0071] To determine whether polymeric compositions of the present
invention have increased stiffness, tensile and flexural properties
of various blends were evaluated. Each data point represents an
average of at least five samples.
[0072] Stiffness is the capacity of the structure to resist elastic
deformation under stress. Youngs' modulus, also known as the
modulus of elasticity, is the ratio of stress (nominal) to
corresponding strain below the proportional limit of a material,
and can be determined according to ASTM D-638-95. Flexural modulus,
also known as the tangent modulus of elasticity, is the ratio
within the elastic limit of stress to corresponding strain, and can
be determined according to ASTM D-790-95A.
[0073] FIGS. 3 and 4 illustrate stiffness properties by presenting
the dependence of Youngs' modulus on the amount of calcium
carbonate in the composition containing polypropylene homopolymer.
ASTM D-638-95 was utilized to determine this tensile property. The
data for FIG. 3 was obtained based upon addition of calcium
carbonate CS11, (3 micron particle size) available from Georgia
Marble Co. at ambient temperature (23.degree. C.); while the data
for FIG. 4 was obtained based upon addition of calcium carbonate
8103C, (3.0-3.5 micron particle size) available from Polar
Minerals, at elevated temperature (42.degree. C.).
[0074] The flex modulus of a material is also an indicator of
stiffness. A higher value for flex modulus indicates a stiffer
composition. ASTM D-790-95 was utilized to determine flexural
properties. Table 3 illustrates that when calcium carbonate is
added to polymer, stiffness increases. Therefore, the compositions
of the present invention result in an increase in stiffness and
impact strength. If the time for the break is longer, the crack
propagates more slowly, which is advantageous to any structural
material, or a plastic part such as a closure.
[0075] Normally, the higher the stiffness, the lower the impact
strength, so the compositions of the present invention have
unexpected properties.
3TABLE 3 Mechanical Properties of PP and PP Blends with CaCO.sub.3
at 23.degree. C. Stress @ Max Flex Modulus @ Load @ Composition
Room Temp. Room Temp. Material (weight %) (Mpa) (Mpa) PP.sup.1 100
1736.10 48.54 PP.sup.1/CaCO.sub.3.sup.2 75/25 2068.17 44.19
Copolymer.sup.5 100 1862.06 50.19 Copolymer.sup.5/CaCO.sub.3.sup.2
75/25 1981.07 42.19 .sup.1polypropylene homopolymer .sup.2calcium
carbonate C-11, available from Georgia Marble, 3.mu. particle size.
.sup.5random copolymer obtained by polymerization of ethylene and
propylene
EXAMPLE 3
[0076] To determine whether or not the polymeric compositions of
the present invention had increased impact resistance, falling
weight impact properties of the compositions including
polypropylene and varying amounts of calcium carbonate (Microdol
Extra, available from Micro Mineral USA and Talc Co. of Norway,
3.mu. particle size) were determined with a Dynatup 8250 Impact
Tester according to ASTM D-5628-94 (method entitled "Standard Test
Method for Impact Resistance of Flat, Rigid Plastic Specimens by
Means of a Falling Dart (TUP of Falling Mass)). The Dynatup test
determines the impact resistance of flat plastic samples to a
falling weight. Each data point represents an average of at least
ten samples. The test was run at two temperatures: 23.degree. C.
(rows 1-5 of Table 4) and -20.degree. C. (rows 6-10 of Table 4).
kgf stands for kilogram force.
[0077] Table 4 shows that the compositions of the present invention
significantly increase maximum load and energy to maximum load at
either temperature.
4TABLE 4 Dynatup Impact Test of Polypropylene/CaCO.sub.3
Compositions Technolog- ical Regime Impact Test at Room Temperature
Total Max. Energy to Time to Total Material Cycle Cool Load Max.
Load Max. Load Energy PP.sup.1: Time Time Average Average Average
Average CaCO.sub.3 (sec.) (sec.) (kgf) (J) (msec.) (J) 100:0 18 7
27.62 0.54 2.00 0.82 85:15 18 7 78.22 1.70 2.31 1.86 75:25 18 7
81.42 2.15 2.53 2.32 70:30 18 7 92.77 3.34 3.12 3.59 65:35 18 7
86.60 2.37 2.75 2.58 Temperature -20.degree. C. 100:0 18 7 13.62
0.31 1.41 0.45 85:15 18 7 18.49 0.56 1.50 0.66 75:25 18 7 61.10
1.12 1.53 1.30 70:30 18 7 63.69 0.94 1.52 1.07 65:35 18 7 64.22
1.31 1.81 1.52 1 = polypropylene homopolymer
EXAMPLE 4
[0078] To determine whether or not the polymeric compositions of
the present invention had increased impact resistance, falling
weight impact properties were further studied. The test procedure
described in Example 3 was utilized to assess the effect of use of
calcium carbonate of different sizes upon falling weight impact
properties of the compositions of the present invention including
polypropylene and varying amounts of calcium carbonate at room
temperature.
[0079] Table 5 indicates that while the compositions of the present
invention increase maximum load and energy to maximum load values
regardless of particle size, the best effect for impact resistance
is demonstrated by filler of particle size 1.4 to 3.0 microns.
5TABLE 5 Dynatup Impact Test for Polypropylene/CaCO.sub.3 Blends
having Different Sizes of CaCO.sub.3 at Room Temperature Technolog-
ical Regime Impact Test at Room Temperature Total Max. Energy to
Time to Total Cycle Cool Load Max. Load Max. Load Energy Material
Time Time Average Average Average Average PP:CaCO.sub.3 (sec.)
(sec.) (kgf) (J) (msec.) (J) 100:0 18 7 28.64 0.79 1.97 0.95
85:15.sup.2 18 7 75.36 2.12 2.03 2.35 75:25.sup.2 18 7 77 08 2.64
2.45 2.95 85:15.sup.6 18 7 43.54 0.82 1.13 0.99 75:25.sup.6 18 7
82.23 2.56 2.18 2.87 85:15.sup.7 18 7 45 63 0.84 1.43 1.08
75:25.sup.7 18 7 57.40 1.34 1.68 1.64 .sup.1= polypropylene
homopolymer .sup.2= calcium carbonate C-11, available from Georgia
Marble, 3.mu. particle size. .sup.6= calcium carbonate FTHS,
available from OMYA Co., 1.4 .mu. particle size. .sup.7= calcium
carbonate UFT, available from OMYA Co., 0.7 .mu. particle size.
EXAMPLE 5
[0080] The test procedure described in Example 3 was utilized to
assess the effect of use of calcium carbonate of different sizes
upon falling weight impact properties of the compositions of the
present invention including polypropylene and varying amounts of
calcium carbonate at reduced temperature.
[0081] Table 6 indicates that while the compositions of the present
invention increase maximum load and energy to maximum load values
regardless of particle size, the best effect for impact resistance
is demonstrated by filler of particle size 1.4 to 3.0 microns.
6TABLE 6 Dynatup Impact Test for Polypropylene/CaCO.sub.3 Blends
having Different Sizes of CaCO.sub.3 at Low Temperature Technolog-
ical Regime Impact Test at Temperature -20.degree. C. Total Max.
Energy to Time to Total Cycle Cool Load Max. Load Max. Load Energy
Material Time Time Average Average Average Average PP:CaCO.sub.3
(sec) (sec.) (kgf) (J) (msec.) (J) 100:0 18 7 10.45 0.33 1.41 0.64
85:15.sup.2 18 7 16.44 0.46 1.51 0.66 75:25.sup.2 18 7 45.12 0.71
1.2 0.89 85:15.sup.6 18 7 21.30 0.46 1.51 0.72 75:25.sup.6 18 7
39.32 0.62 1.12 0.94 85:15.sup.6 18 7 20.41 0.49 1.57 0.66
75:25.sup.7 18 7 21.73 0.61 1.88 0.87 .sup.2= calcium carbonate
C-11, available from Georgia Marble, 3 .mu. particle size. .sup.6=
calcium carbonate FTHS, available from OMYA Co., 1.4 .mu. particle
size. .sup.7= calcium carbonate UFT, available from OMYA Co., 0.7
.mu. particle size.
EXAMPLE 6
[0082] The test procedure described in Example 3 was utilized to
assess the effect of the variation of polymer type upon falling
weight impact properties of the compositions of the present
invention including calcium carbonate and either homopolymer or
copolymer at room temperature.
[0083] Table 7 indicates that the toughness of the homopolymer
blend increases more than 290% compared to neat resin, and the
impact energy for the copolymer blend increases 60% compared to the
homopolymer blend at room temperature.
7TABLE 7 Dynatup Impact Test of Propylene Derived Homopolymer or
Copolymer Blends with CaCO.sub.3 at Room Temperature Technolog-
ical Regime Room Temperature Total Max. Energy to Time to Total
Material Cycle Cool Load Max. Load Max. Load Energy Polymer: Time
Time Average Average Average Average CaCO.sub.2.sup.2 (sec.) (sec.)
(kgf) (J) (msec.) (J) 1001:0 18 7 28.57 0.88 2.04 1.25 75.sup.1:25
18 7 87.55 3.46 2.70 3.74 100.sup.5:0 18 7 79.49 2.41 2.15 3.14
75.sup.5:25 18 7 89.95 3.93 2.83 4.26 100.sup.1:0 25 14 25.94 0.77
2.09 1.04 75.sup.1:25 25 14 84.48 3.21 2.61 3.54 100.sup.5:0 25 14
84.64 2.56 2.15 3.15 75.sup.5:25 25 14 82.87 3.48 2.64 3.76
100.sup.1:0 32 21 23.41 0.76 2.05 1.14 75.sup.1:25 32 21 81.33 2.90
2.49 3.24 75.sup.5:25 32 21 83.19 3.44 2.64 3.77 .sup.1=
polypropylene homopolymer .sup.2= calcium carbonate CS-11,
available from Georgia Marble, 3 .mu. particle size. .sup.5= random
copolymer obtained by polymerization of ethylene and propylene
EXAMPLE 7
[0084] The test procedure described in Example 3 was utilized to
assess the effect of the variation of polymer type upon falling
weight impact properties of the compositions of the present
invention including calcium carbonate and either homopolymer or
copolymer at reduced temperature (-20.degree. C.).
[0085] Table 8 indicates that the toughness of the homopolymer or
copolymer blends increase more than three to six times compared to
neat resin.
8TABLE 8 Dynatup Impact Test of Propylene Derived Homopolymer or
Copolymer Blends with CaCO.sub.3 at Reduced Temperature Technolog-
ical Regime Temperature -20.degree. C. Total Max. Energy to Time to
Total Material Cycle Cool Load Max. Load Max. Load Energy Polymer:
Time Time Average Average Average Average CaCO.sub.3.sup.2 (sec.)
(sec.) (kgf) (J) (msec.) (J) 100.sup.1:0 18 7 11.04 0.27 1.24 0.50
75.sup.1:25 18 7 84.56 2.06 1.86 2.27 100.sup.5:0 18 7 23.62 0.58
1.69 0.95 75.sup.5:25 18 7 93.99 2.22 1.85 2.47 100.sup.1:0 25 14
12.37 0.23 1.06 0.50 75.sup.1:25 25 14 77.88 1.60 1.59 1.81
100.sup.5:0 25 14 23.24 0.58 1.8 0.96 75.sup.5:25 25 14 94.13 2.31
1.87 2.56 100.sup.1:0 32 21 12.43 0.27 1.3 0.51 75.sup.1:25 32 21
72.45 1.41 1.59 1.62 75.sup.5:25 32 21 82.47 1.76 1.72 1.99 .sup.1=
polypropylene homopolymer .sup.2= calcium carbonate C-11, available
from Georgia Marble, 3 .mu. particle size. .sup.5= random copolymer
obtained by polymerization of ethylene and propylene
EXAMPLE 8
[0086] To determine the effect of various cold temperatures on
strength properties of the blends of the present invention, Izod
Impact tests (ASTM D-256-93A, method entitled "Standard Test Method
for Izod--Determining the Pendulum Impact Resistance of Notched
Specimens of Plastic Izod Test") were conducted at 0.degree. C.,
-20.degree. C. and -40.degree. C. on blends containing varied
amounts of calcium carbonate. Samples were molded as per ASTM
D-4101-95B (method entitled "Standard Specification for Propylene
Plastic Injection and Extrusion Materials"). Samples were
conditioned over forty hours at 23.degree. C. and 50 percent
relative humidity per ASTM D-618-95 (method entitled "Standard
Practice for Conditioning Plastics and Electrical Insulating
Material for Testing") after notching and two hours at the testing
temperature of 0.degree. C., -20.degree. C. and -40.degree. C. as
indicated in Table 9. The notching generated an artificial crack in
the test material, which was then tested with a pendulum
impactor.
[0087] As indicated in Table 9, similar impact behavior is observed
at each tested temperature. Izod impacts at various temperatures
was measured in Joules per meter (J/m). Each of the blends showed
improved performance over polymer alone.
9TABLE 9 Izod Impact Test of Polypropylene.sup.1 and Calcium
Carbonate Blends with different grades of CaCO.sub.3 at Various
Cold Temperatures Temp- Calcium erature PP.sup.1 Calcium
Carbonate.sup.2 Calcium Carbonate.sup.3 Carbonate.sup.4 Filler none
15% 25% 40% 15% 25% 40% 15% 25% loading Izod 16.94 29.12 24.77
26.29 23.57 24.35 24.84 24.41 25.15 Impact at 0.degree. C. Izod
15.36 28.03 21.16 23.73 25.28 21.17 24.88 20.71 21.47 Impact at
-20.degree. C. Izod 17.56 25.56 21.06 25.09 23.75 22.95 22.99 22.15
22.53 Impact at -40.degree. C. .sup.1= polypropylene homopolymer
.sup.2= calcium carbonate C-11, available from Georgia Marble, 3
.mu. particle size .sup.3= calcium carbonate available from Polar
Mineral Co., 3-3.5 .mu. particle size. .sup.4= calcium carbonate
Microdol Extra, available from Micro Mineral Co., 3 .mu. particle
size.
EXAMPLE 9
[0088] To test the properties of closures made from the polymeric
compositions of the present invention, 28 AQUALOK III closures (a
type of closure made by Alcoa CSI) were molded from polypropylene
compounded with varying amounts of calcium carbonate, and tested
according to the procedure described in Example 3. The calcium
carbonate utilized was 8103C, available from Polar Minerals, of
particle size 2.5 to 3.5 microns. The polypropylene was obtained
from Phillips Petroleum Company. Some of the test blends also
included pigment, to make colored closures at ambient temperature.
Ppm stands for parts per minute.
[0089] The results in Table 10 show that addition of calcium
carbonate enhances each of the measured properties. Therefore,
impact resistance of closures made from the polymeric compositions
is improved.
10TABLE 10 Impact Resistance of Closures made from Blends of
Polypropylene and Calcium Carbonate Speed of Average Average Time
Polymer: Machine Average Max. Energy to Max. to Max. Load
CaCO.sub.3 (ppm) Load (lbs) Load (inch lbs) (msec) 100:0 300 147.72
6.24 0.78 100:0 550 131.57 5.28 0.72 100:0 .sup. 550.sup.1 144.89
6.96 0.77 85:15 300 190.01 14.04 1.27 85:15 550 182.89 13.20 1.30
85:15 .sup. 550.sup.1 177.78 12.72 1.25 75:25 300 266.02 25.56 1.73
75:25 550 222.27 20.04 1.60 75:25 .sup. 550.sup.1 191.20 14.76 1.28
60:40 300 558.25 59.88 2.67 60:40 550 449.66 46.92 2.72 60:40 .sup.
550.sup.1 542.07 56.52 2.78 .sup.11.6% by weight of color
concentrate
EXAMPLE 10
[0090] To test the properties of closures made from the polymeric
compositions of the present invention, 28DL ULTRA closures (a type
of closure made by Alcoa CSI) were molded from polypropylene
compounded with varying amounts of calcium carbonate, and tested
according to the procedure described in Example 3. The calcium
carbonate utilized was Microdol Extra, available from Micro Mineral
Co., of particle size 3.0 microns. The polypropylene was obtained
from Phillips Petroleum Company. Some of the test blends also
included pigment, to make colored closures.
[0091] The results in Table 11 show that addition of calcium
carbonate starting from 15% loading enhances each of the measured
properties. Therefore, impact resistance of closures made from the
polymeric compositions is improved.
11TABLE 11 Impact Resistance of Closures made from Blends of
Polypropylene and Calcium Carbonate Speed of Average Average Time
Polymer: Machine Average Max. Energy to Max. to Max. CaCO.sub.3
(ppm) Load (lbs) Load (inch lbs) Load (msec) 100:0 300 147.72 6.24
0.78 100:0 550 131.57 5.28 0.72 100:0 .sup. 550.sup.1 144.89 6.96
0.77 95:5 550 110.45 5.04 0.65 95:5 600 108.21 4.68 0.55 90:10 550
145.11 8.64 0.79 90:10 600 119.05 5.64 0.59 85:15 .sup. 500.sup.1
164.40 11.04 0.8 85:15 500 151.34 9.24 0.74 80:20 .sup. 500.sup.2
164.02 11.52 0.83 80:20 .sup. 500.sup.1 156.65 10.44 0.78 75:25 550
164.51 12.12 0.89 70:30 .sup. 500.sup.1 175.16 14.52 1.09 70:30 550
177.84 14.4 1.02 65:35 .sup. 500.sup.1 148.03 13.56 1.22 65:35 550
160.41 13.32 1.08 .sup.12.2% by weight of color concentrate
.sup.21.6% by weight of color concentrate
[0092] All references cited are hereby incorporated by
reference.
[0093] The present invention is illustrated by way of the foregoing
description and examples. The foregoing description is intended as
a non-limiting illustration, since many variations will become
apparent to those skilled in the art in view thereof. It is
intended that all such variations within the scope and spirit of
the appended claims be embraced thereby.
[0094] Changes can be made in the composition, operation and
arrangement of the method of the present invention described herein
without departing from the concept and scope of the invention as
defined in the following claims:
* * * * *