U.S. patent application number 11/527527 was filed with the patent office on 2007-01-25 for polyesters and polyester containers having a reduced coefficient of friction and improved clarity.
This patent application is currently assigned to EASTMAN CHEMICAL COMPANY. Invention is credited to Louis Thomas Germinario, Ronald Richard Light, Emerson Eston JR. Sharpe, Steven Lee Stafford.
Application Number | 20070020419 11/527527 |
Document ID | / |
Family ID | 26802638 |
Filed Date | 2007-01-25 |
United States Patent
Application |
20070020419 |
Kind Code |
A1 |
Stafford; Steven Lee ; et
al. |
January 25, 2007 |
Polyesters and polyester containers having a reduced coefficient of
friction and improved clarity
Abstract
Polyesters and polyester containers having a reduced coefficient
of friction and improved clarity are produced using an antiblock
agent comprising a dried talc having from about 20 to about 300 ppm
water or a fatty acid tethered talc. The use of these talcs result
in polyesters and polyester containers having a coefficient of less
than about 1.0 and a clarity with haze values of less than about
4%.
Inventors: |
Stafford; Steven Lee; (Gray,
TN) ; Light; Ronald Richard; (Kingsport, TN) ;
Germinario; Louis Thomas; (Kingsport, TN) ; Sharpe;
Emerson Eston JR.; (Kingsport, TN) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
EASTMAN CHEMICAL COMPANY
|
Family ID: |
26802638 |
Appl. No.: |
11/527527 |
Filed: |
September 27, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10105488 |
Mar 25, 2002 |
|
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11527527 |
Sep 27, 2006 |
|
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60280295 |
Mar 30, 2001 |
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Current U.S.
Class: |
428/35.7 |
Current CPC
Class: |
C08K 3/34 20130101; Y10T
428/1372 20150115; Y10T 428/1352 20150115; C08K 3/34 20130101; C08L
67/00 20130101 |
Class at
Publication: |
428/035.7 |
International
Class: |
B32B 27/08 20060101
B32B027/08 |
Claims
1-40. (canceled)
41. A bottle made from a composition comprising polyester and talc,
said bottle having a haze value of less than about 4% and a reduced
coefficient of friction compared to a bottle made from a
composition without talc.
42. The bottle according to claim 41, which is a carbonated
soft-drink bottle.
43. The bottle according to claim 42, which is a two-liter
bottle.
44. The bottle according to claim 41, wherein the composition
comprises about 0.005 to about 0.025 weight percent of talc having
an average particle size of about 0.2 to about 10 microns.
45. The bottle according to claim 41, wherein the composition
comprises about 0.0125 to about 0.025 weight percent of talc having
an average particle size of 20 nanometers to 7 microns.
46. The bottle according to claim 41, which has a haze value of
about 0.1 to about 3%.
47. The bottle according to claim 41, which has a coefficient of
friction of about 0.01 to about 1.0.
48. The bottle according to claim 41, wherein the talc has been
dried so that it contains about 20 to about 300 ppm of water before
addition to the polyester.
49. The bottle according to claim 41, wherein the talc has been
treated with a fatty acid.
50. The bottle according to claim 41, wherein the talc is a mixture
of talc that has been dried so that it contains about 20 to about
300 ppm of water before addition to the polyester and talc that has
been treated with a fatty acid.
51. The bottle according to claim 41, wherein the polyester
comprises dicarboxylic acid repeat units formed from terephthalic
acid, dimethyl terephthalate, isophthalic acid, dimethyl
isophthalate, dimethyl-2,6-naphthalenedicarboxylate,
2,6-naphthalenedicarboxylic acid, or mixtures thereof; and glycol
repeat units formed from ethylene glycol, diethylene glycol,
1,4-cyclohexane-dimethanol, 1,4-butanediol, or mixtures
thereof.
52. The bottle according to claim 51, wherein the dicarboxylic acid
repeat units are modified with up to about 15 mole percent of
phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid,
cyclohexanedicarboxylic acid, cyclohexanediacetic acid,
diphenyl-4,4'-dicarboxylic acid, succinic acid, glutaric acid,
adipic acid, azelaic acid, sebacic acid, or mixtures thereof.
53. The bottle according to claim 51, wherein the glycol repeat
units are modified with up to about 15 mole percent of diethylene
glycol, triethylene glycol, 1,4-cyclohexanedimethanol,
propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol,
hexane-1,6-diol, 3-methylpentanediol-(2,4),
2-methylpentanediol-(1,4), 2,2,4-trimethylpentane-diol-(1,3),
2-ethylhexanediol-(1,3), 2,2-diethylpropane-diol-(1,3),
hexanediol-(1,3), 1,4-di-(hydroxyethoxy)-benzene,
2,2-bis-(4-hydroxycyclohexyl)-propane,
2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane,
2,2-bis-(3-hydroxyethoxyphenyl)-propane,
2,2-bis-(4-hydroxypropoxyphenyl)-propane, or mixtures thereof.
54. The bottle according to claim 41, wherein the polyester is a
poly(ethyleneterephthalate).
55. The bottle according to claim 41, wherein the polyester is a
copolyester of terephthalic acid, isopthalic acid, and ethylene
glycol.
56. A stretch blow molded container made from a composition
comprising polyester and talc, said container having a haze value
of less than about 4% and a reduced coefficient of friction
compared to a container made from a composition without talc.
57. The container according to claim 56, which is a carbonated
soft-drink bottle.
58. The container according to claim 57, which is a two-liter
bottle.
59. The container according to claim 56, wherein the composition
comprises about 0.005 to about 0.025 weight percent of talc having
an average particle size of about 0.2 to about 10 microns.
60. The container according to claim 56, wherein the composition
comprises about 0.0125 to about 0.025 weight percent of talc having
an average particle size of 20 nanometers to 7 microns.
61. The container according to claim 56, which has a haze value of
about 0.1 to about 3%.
62. The container according to claim 56, which has a coefficient of
friction of about 0.01 to about 1.0.
63. The container according to claim 56, wherein the talc has been
dried so that it contains about 20 to about 300 ppm of water before
addition to the polyester.
64. The container according to claim 56, wherein the talc has been
treated with a fatty acid.
65. The container according to claim 56, wherein the talc is a
mixture of talc that has been dried so that it contains about 20 to
about 300 ppm of water before addition to the polyester and talc
that has been treated with a fatty acid.
66. The container according to claim 56, wherein the polyester
comprises dicarboxylic acid repeat units formed from terephthalic
acid, dimethyl terephthalate, isophthalic acid, dimethyl
isophthalate, dimethyl-2,6-naphthalenedicarboxylate,
2,6-naphthalenedicarboxylic acid, or mixtures thereof; and glycol
repeat units formed from ethylene glycol, diethylene glycol,
1,4-cyclohexane-dimethanol, 1,4-butanediol, or mixtures
thereof.
67. The container according to claim 56, wherein the dicarboxylic
acid repeat units are modified with up to about 15 mole percent of
phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid,
cyclohexanedicarboxylic acid, cyclohexanediacetic acid,
diphenyl-4,4'-dicarboxylic acid, succinic acid, glutaric acid,
adipic acid, azelaic acid, sebacic acid, or mixtures thereof.
68. The container according to claim 56, wherein the glycol repeat
units are modified with up to about 15 mole percent of diethylene
glycol, triethylene glycol, 1,4-cyclohexanedimethanol,
propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol,
hexane-1,6-diol, 3-methylpentanediol-(2,4),
2-methylpentanediol-(1,4), 2,2,4-trimethylpentane-diol-(1,3),
2-ethylhexanediol-(1,3), 2,2-diethylpropane-diol-(1,3),
hexanediol-(1,3), 1,4-di-(hydroxyethoxy)-benzene,
2,2-bis-(4-hydroxycyclohexyl)-propane,
2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane,
2,2-bis-(3-hydroxyethoxyphenyl)-propane,
2,2-bis-(4-hydroxypropoxyphenyl)-propane, or mixtures thereof.
69. The container according to claim 56, wherein the polyester is a
poly(ethyleneterephthalate).
70. The container according to claim 56, wherein the polyester is a
copolyester of terephthalic acid, isopthalic acid, and ethylene
glycol.
71. A bottle preform made from a composition comprising a polyester
and about 0.0125 to about 0.025 weight percent of talc having an
average particle size of 20 nanometers to 7 microns, wherein the
preform is capable of being formed into a bottle having a reduced
coefficient of friction and a haze value of less than about 4%.
72. The bottle preform according to claim 71, which is capable of
being formed into a bottle having a haze value of about 0.1 to
about 3%.
73. The bottle preform according to claim 71, which is capable of
being formed into a bottle having a coefficient of friction of
about 0.01 to about 1.0.
74. The bottle preform according to claim 71, wherein the talc has
been dried so that it contains about 20 to about 300 ppm of water
before addition to the polyester.
75. The bottle preform according to claim 71, wherein the talc has
been treated with a fatty acid.
76. The bottle preform according to claim 71, wherein the talc is a
mixture of talc that has been dried so that it contains about 20 to
about 300 ppm of water before addition to the polyester and talc
that has been treated with a fatty acid.
77. The bottle preform according to claim 71, wherein the polyester
comprises dicarboxylic acid repeat units formed from terephthalic
acid, dimethyl terephthalate, isophthalic acid, dimethyl
isophthalate, dimethyl-2,6-naphthalenedicarboxylate,
2,6-naphthalenedicarboxylic acid, or mixtures thereof; and glycol
repeat units formed from ethylene glycol, diethylene glycol,
1,4-cyclohexane-dimethanol, 1,4-butanediol, or mixtures
thereof.
78. The bottle preform according to claim 77, wherein the
dicarboxylic acid repeat units are modified with up to about 15
mole percent of phthalic acid, isophthalic acid,
naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid,
cyclohexanediacetic acid, diphenyl-4,4'-dicarboxylic acid, succinic
acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, or
mixtures thereof.
79. The bottle preform according to claim 77, wherein the glycol
repeat units are modified with up to about 15 mole percent of
diethylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol,
propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol,
hexane-1,6-diol, 3-methylpentanediol-(2,4),
2-methylpentanediol-(1,4), 2,2,4-trimethylpentane-diol-(1,3),
2-ethylhexanediol-(1,3), 2,2-diethylpropane-diol-(1,3),
hexanediol-(1,3), 1,4-di-(hydroxyethoxy)-benzene,
2,2-bis-(4-hydroxycyclohexyl)-propane,
2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane,
2,2-bis-(3-hydroxyethoxyphenyl)-propane,
2,2-bis-(4-hydroxypropoxyphenyl)-propane, or mixtures thereof.
80. The bottle preform according to claim 71, wherein the polyester
is a poly(ethyleneterephthalate).
81. The bottle preform according to claim 71, wherein the polyester
is a copolyester of terephthalic acid, isopthalic acid, and
ethylene glycol.
82. A drink bottle, said bottle having been stretch blown from a
preform into a bottle without thermoforming, said preform having
been made from a polyester, said polyester containing from about
0.001 to about 0.025 wt % talc having an average particle size of
from about 0.2 .mu.m to about 10 .mu.m, said bottle having a
reduced coefficient of friction as compared to a bottle made from
said polyester but not containing said talc, and said bottle having
a haze value of about 0.1% to about 4%.
83. A drink bottle having smooth surfaces such that when placed
perpendicular to another said bottle the bottles can rotate against
each other with continuous point contact, said bottle having been
made from a polyester, said polyester comprising from about 0.001
to about 0.025 wt % talc having an average particle size of from
about 0.2 .mu.m to about 10 .mu.m, said bottle having a reduced
coefficient of friction as compared to a bottle made from said
polyester but not containing said talc, and said bottle having a
haze value of about 0.1% to about 4%.
84. A carbonated soft-drink bottle, said bottle having been stretch
blown from a preform into a bottle suitable for storage of a
carbonated soft-drink, said preform having been made from a
polyester, said polyester containing from about 0.001 to about
0.025 wt % talc having an average particle size of from about 0.2
.mu.m to about 10 .mu.m, said bottle having a reduced, coefficient
of friction as compared to a bottle made from said polyester but
not containing said talc, and said bottle having a haze value of
about 0.1% to about 4%.
85. A straight-walled bottle suitable for use in containing a
carbonated soft-drink, said bottle having been blown from a
preform, said preform comprising a polyester and talc, said talc
being present in an amount of about 0.001 wt % to about 0.025 wt %
and having an average particle size of about 0.2 .mu.m to about 10
.mu.m, said bottle having a reduced coefficient of friction as
compared to a bottle made from said polyester but not containing
said talc, and said bottle having a haze value of about 0.1% to
about 4%.
86. A preform of a drink bottle, said preform comprising a
polyester containing talc, said talc being present in an amount of
about 0.001 to about 0.025 wt % and having an average particle size
of from about 0.2 .mu.m to about 10 .mu.m, said preform capable of
being stretch blown into a drink bottle having a reduced
coefficient of friction as compared to a bottle made from said
polyester but not containing said talc and a haze value of about
0.1% to about 4%.
87. A preform of a drink bottle, said preform having smooth
surfaces such that when placed perpendicular to another said
preform, the preforms can rotate against each other with continuous
point contact, said preform having been made from a polyester, said
polyester comprising from about 0.001 to about 0.025 wt % talc
having an average particle size of from about 0.2 .mu.m to about 10
.mu.m, said preform capable of being stretch blown into bottle
having a reduced coefficient of friction as compared to a bottle
not containing said talc and a haze value of about 0.1% to about
4%.
88. A carbonated soft-drink bottle made from a composition
comprising a polyester or copolyester and from about 0.005 to about
0.025 weight percent of talc having an average particle size of 0.2
to 10 microns, said bottle having a haze value of less than about
4%.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 60/280,295, filed Mar. 30, 2001, the
disclosure of which is incorporated herein by this reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to polyesters and polyester
containers and particularly to polyesters and polyester containers
having a reduced coefficient of friction and improved clarity.
[0004] 2. Description of the Prior Art
[0005] Problems exist in conveying various types of polyester
containers due to the excessive amount of static friction
encountered when container surfaces contact. This excessive
friction can lead to "process line" or "filling line" interruptions
that are economically undesirable. The problem occurs after the
polyester polymer has been molded into preforms or stretch blown
into various types of containers. The containers are sometimes
conveyed directly into a palletizing station and then shipped to a
filling plant or they are conveyed to a labeling and filling line
contained within the same plant. This problem is more pronounced in
the carbonated soft-drink ("CSD") industry due to the high speed of
stretch-blow molding conveying and filling lines. The problem is
also encountered in other parts of the polyester container industry
where the containers are being conveyed under pressures applied
from congested areas of the conveying process.
[0006] During the process of blow molding or injection molding
container preforms, the preforms are fed into a large box (gaylord
box) that holds more than 1000 preforms. Given the high coefficient
of friction ("COF") that is common between polyester surfaces, the
preforms tend to stack on top of one another in a conical shape as
viewed from the side of the box. This stacking results in fewer
preforms being loaded into a box and therefore higher shipping
costs per preform. The high level of friction between the preform
surfaces can also cause jams in the feeder bin as the preforms are
loaded onto the feed rail. Similarly, jams may also occur on the
feed rail due to such friction.
[0007] Straight-walled containers such as the two liter bottles
used in the carbonated soft-drink ("CSD") industry have a very
smooth surface that maximizes the amount of surface area that comes
in contact between two adjacent bottles. With the inherently high
COF of polyester containers such as PET (PET has a static COF
greater than 1.0), the containers become entangled and "tip over"
or just stop moving in the conveying line after blowing or during
filling. Such tip over and stopage obviously causes undesirable
disruptions in the conveying or filling process.
[0008] A high COF prevents adjacent containers on a multiple-row
conveying line from moving (turning or slipping) during conveying.
When the conveying line changes direction, sometimes as much as 90
degrees, the containers may become entangled and either stay
upright and stop the feed or tip over and stop the line. In either
event, someone has to monitor these problem areas at all times to
keep the line moving. Therefore, a container having a low static
COF that could slide and rotate against other containers during
conveying would minimize or eliminate process downtime and the need
for someone to constantly monitor the process. These problems are
all related to polyesters having an unacceptably COF.
[0009] There is prior art relating to methods for reducing the COF
for polyesters. One such method involves the addition of an
antiblock agents such as silica, talc, calcium carbonate, calcium
stearate, and other inorganic compounds. JP 9272191 discloses a
multi-layer sheet containing inert particulates (10 to 5000 ppm at
0.5 to 30 micron size) including silica and talc used to improve
the slip properties, scratch resistance, cut properties and
adhesive properties of the sheet and articles made from the sheet.
U.S. Pat. No. 5,840,419 discloses multilayer polyolefin films that
use cross-linked silicone in combination with inorganic antiblock
agents such as talc in amounts of 500 to 5000 ppm with particles
sizes from 1 to 6 micrometers to reduce the COF. Neither reference
discloses stretch blow molded containers. U.S. Pat. No. 6,323,271
discloses polyester resins containing a silica selected from the
group consisting of fumed silica, colloidal silica and silica beads
that is useful for making containers having reduced sticliness
relative to containers made from the same resin but without the
silica U.S. Pat. No. 5,258,161 discloses polyolefin films having
talc in amounts of 0.05% to 3% by weight as an antiblock agent.
U.S. Pat. No. 5,908,890 disclose a polymer film comprising a
polyolefin matrix containing a pumice antiblock agent in amounts of
less than about I percent by weight.
[0010] U.S. Pat. No. 5,830,544 discloses
poly(ethyleneterephthalate) ("PET") bottles having reduced
sticliness due to the addition of amorphous silica at a
concentration range of 10 to 100 ppm. The use of additives other
than amorphous silica and methods for improving clarity of the
bottle containing anti-stick additives are not disclosed. JP Patent
Application Heisei 2-307117 discloses the optimization of loading
and particulate size of the antiblock on film properties such as
haze and COF. The reference does not disclose containers such as
plastic bottles nor does it disclose drying an antiblock before
processing.
[0011] JP Patent Application Heisei 4-180957 discloses mono- and
multi-layer sheet and thermoformed moldings formed from PET having
100 to 10,000 ppm talc with particle size less than 10 microns.
Suitable thermoformed containers include blister packs that have
good clarity. Containers such as plastic bottles, the benefits of
drying the antiblock before processing, and the use of fatty acid
tethers are not disclosed.
[0012] There is prior art relating to polyester films incorporating
a variety of inorganic particles to improve crystallinity and slip.
JP 7238211 discloses magnetic tape; JP 6065478 discloses magnetic
tape, photograph, packaging film; JP5104621 discloses thermoformed
sheets; JP 4183718 discloses base film for magnetic tape,
photographic film, electrical insulating film, a base material for
gold yarn, and packaging material; and JP 4180957 discloses PET
w/talc with good slipping and stacking properties with good
transparency.
[0013] None of the prior art references disclose polyesters or
polyester containers having a coefficient of friction of much less
than 1.0, particularly polyesters or polyester containers having
talc as an antiblock agent There is, therefore, a need for new and
improved polyesters and polyester containers having a reduced COF,
particularly high clarity (low haze) containers that have a reduced
COF.
SUMMARY OF THE INVENTION
[0014] It is, therefore, an object of the invention to provide
polyesters and polyester containers having a reduced coefficient of
friction and acceptable clarity.
[0015] It is another object of the invention to provide polyesters
and polyester containers having a reduced coefficient of friction
and enhanced clarity.
[0016] It is a further object of the invention to provide antiblock
agents useful in the production of polyester and polyester
containers having acceptable and enhanced clarity.
[0017] It is another object of the invention to provide an
antiblock agent useful in the production of polyester and polyester
containers.
[0018] These and other objects are achieved using a dried talc
having from about 20 to about 300 ppm water or a fatty acid
tethered talc to reduce the coefficient of friction for polyesters
and polyester containers. The uses of these talcs result in
polyesters and polyester containers having a coefficient of less
than about 1.0 and a clarity with haze values of less than about
4%. Such polyesters and polyester containers can be used to package
various foods and beverages.
[0019] Other and further objects, features and advantages of the
present invention will be readily apparent to those skilled in the
art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a graph showing the effect of talc particle size
on COF.
[0021] FIG. 2 is a graph showing the effect of talc particle size
on haze.
[0022] FIG. 3 is a graph showing the effect of BaSO.sub.4 particle
size on COF.
[0023] FIG. 4 is a graph showing the effect of BaSO.sub.4 particle
size on haze.
[0024] FIG. 5 is a graph showing the effect of SiO.sub.2 particle
size on COF.
[0025] FIG. 6 is a graph showing the effect of SiO.sub.2 particle
size on haze.
[0026] FIG. 7 is a graph comparing the effect of talc, BaSO.sub.4
and SiO.sub.2 on COF.
[0027] FIG. 8 is a graph comparing the effect of talc, BaSO.sub.4
and SiO.sub.2 on haze.
[0028] FIG. 9 is a graph comparing the effect of dried and undried
talc on COF.
[0029] FIG. 10 is a graph comparing the effect of dried and undried
talc on haze.
DETAILED DESCRIPTION OF THE INVENTION
[0030] The term "weight percentages" and the acronym "wt %" as used
herein refer to weight percentages based on the total weight of the
polyester composition in its final form with all ingredients
added.
[0031] The term "container" as used herein includes containers and
the performs used to manufacture the containers.
[0032] In one aspect, the present invention provides polyesters and
polyester containers having a reduced coefficient of friction
("COF") and acceptable clarity. The reduced COF is obtained by
adding talc, a hydrated magnesium silicate with the chemical
formula Mg, Si, O.sub.10(OH).sub.2, to the polyesters. The talc, or
antiblock agent, creates a surface roughness that decreases the COF
of the polyester while not adversely affecting the clarity of the
polyester or polyester container.
[0033] The talc useful in the present invention comprises about 62
wt % SiO.sub.2 and about 31% MgO, has a density of about 2.7 grams
per cubic centimeter (g/cc), and average particle sizes of from
about 0.05 to about 50 microns, preferably from about 0.1 to about
20 microns, most preferably from about 0.2 to about 10 microns.
Suitable talc is commercially available from several sources,
including Polar Minerals, Inc., 2005 Newpoint Place Parkway,
Lawrenceville, Ga. 30043, under the name Polar Talc 9107 or 9103
(with or without fatty acid tether attached).
[0034] Before addition to the polyester, the talc is dried so that
it contains from about 20 to about 300 ppm water, preferably from
about 50 to about 250 ppm water. The use of this "dried talc" is
critical to this aspect of the present invention because it permits
the production of a polyester with a combination of the maximum
reduction in the COF and minimum adverse affect on clarity and
haze. The talc can be dried by conventional means, such as a dryer
or oven under conditions that are known to skill artisans. If the
talc is not dried, a higher loading of the talc will be required.
If the talc is not dried, the level of haze acquired for a certain
amount of friction reduction will be increased.
[0035] The concentration of dried talc in the polyesters of the
present invention is from about 0.001 to about 0.1 wt %. Because
the clarity of the container decreases with increasing talc
concentration, the preferred concentration is from about 0.001 to
about 0.05 wt %, most preferably from about 0.005 to about 0.025 wt
%.
[0036] The polyesters and polyester containers made according to
this aspect of present invention have a coefficient of friction of
from about 0.01 to about 1.0.
[0037] The polyesters and polyester containers made according to
this aspect of present invention have an acceptable clarity with
haze values of from about 0.1 to about 4%, preferably from about
0.1 to about 3%.
[0038] Other well known antiblock agents useful in the production
of polyesters and polyester containers and having properties
similar to talc will perform equally well in the present invention
when dried so that they contain from about 20 to about 300 ppm
water, e.g., amorphous silica, barium sulfate, zinc stearate,
calcium phosphate, and mixtures thereof.
[0039] In a further aspect, the present invention provides
polyesters and polyester containers having a reduced coefficient of
friction ("COF") and enhanced clarity. The clarity of the
polyesters and polyester containers is enhanced by treating the
talc with a fatty acid to attach a tether on the talc ("tethered
talc").
[0040] Fatty acids useful in the present invention are fatty acids
that are compatible with the polyesters and thermally stable at the
selected polymerization and/or processing conditions used to make
the polyesters and polyester containers. Preferred fatty acids are
selected from the group consisting of branched stearic acid,
C.sub.6 to C.sub.20 saturated and unsaturated, linear and branched,
fatty acids. Most preferred fatty acids are linolic, palmitic,
oleic, linoleic, and palmolenic fatty acids.
[0041] The talc useful to produce tethered talc is "undried talc"
available commercially or "dried talc" produced as described
herein. The talc is tethered to the fatty acid by conventional
means well known to skilled artisans. Such fatty acid tethered
talcs are also commercially available from several sources
including Polar Minerals, Inc., 2005 Newpoint Place Parkway,
Lawrenceville, Ga. 30043.
[0042] Although not bound by theory, it is believed that the fatty
acids make the talc more compatible with the polyester and reduce
voids upon orientation of the polymer. Voids are caused by
incompatibility of the polyester at the interface with the talc.
When a container is stretched, if the polyester is not compatible
with the talc particulate, it pulls away and creates a void. The
organic fatty acid tethers act as a liaison between the inorganic
talc particulate and the polyester.
[0043] The concentration of tethered talc in the polyesters of the
present invention is from about 0.001 to about 0.1 wt %. Because
less tethered talc is needed generally, the preferred concentration
is from about 0.001 to about 0.04 wt %, most preferably from about
0.005 to about 0.020 wt %.
[0044] The polyesters and polyester containers made according to
this aspect of present invention have a coefficient of friction of
from about 0.01 to about 1.0.
[0045] The polyesters and polyester containers made according to
this aspect of present invention have an enhanced clarity with haze
values of from about 0.1 to about 3%, preferably from about 0.1 to
about 2%.
[0046] The tethered talc is added to polyesters during the
production process to produce polyesters and polyester containers
having a reduced coefficient of friction and enhanced clarity.
[0047] The talc and the tethered talc can be added to the polyester
during the polymerization process or it can be pre-blended with a
polyester before processing to form a concentrate. The concentrate
can then be mixed with virgin polyester to achieve the desired
concentration of talc or tethered talc. Mixtures of dried talc and
tethered talc (tethered talc made with dried or undried talc) are
embodiments of the present invention.
[0048] The polyesters of the present invention can be made using
processes well known to skilled artisans. Suitable polyesters can
be produced in a conventional manner by the reaction of a
dicarboxylic acid having 2 to 40 carbon atoms with polyhydric
alcohols such as glycols or diols containing from 2 to about 20
carbon atoms. The processes for producing polyesters, including
process conditions, catalysts, sequestering agents, quenching
agents, and additives, are known to skilled artisans. Methods of
producing polyester materials and combinations of polyesters with
other polymeric materials are given in W. R. Sorenson and T. W.
Campbell, "Preparative Methods of Polymer Chemistry," (Interscience
Publishers, New York 1968, and subsequent editions) and the
"Encyclopedia of Polymer Science; and Engineering, 2nd Ed.," H. F.
Mark et al., (John Wiley & Sons, New York 1985), particularly
Volume 12, pages 1-290 (polyesters generally) and especially pages
259-274 for resin manufacturing processes.
[0049] The dicarboxylic acid for producing the polyester is an
alkyl dicarboxylic acid having 2 to 20 carbon atoms, or an aryl- or
alkyl-substituted aryl dicarboxylic acid containing from 8 to 16
carbon atoms. Additionally, an alkyl dicarboxylic acid diester
having from 4 to 20 carbon atoms or an alkyl-substituted aryl
dicarboxylic acid diester having from 10 to 20 carbon atoms can be
utilized instead of the dicarboxylic acid. Polyhydric glycols or
diols containing from 2 to 8 carbon atoms are preferred, most
preferably ethylene glycol. Glycol or diol ethers having from 4 to
12 carbon atoms may be substituted for the glycol or diol.
[0050] Terephthalate polyesters are made from either dimethyl
terephthalate or terephthalic acid with ethylene glycol or from
either dimethyl terephthalate or terephthalic acid with
1,4-cyclohexane diol. Suitable dicarboxylic acids include
terephthalic acid, isophthalic acid, malonic, succinic, glutaric,
adipic, suberic, sebacic, maleic and fumaric acid, all of which are
well known dicarboxylic acids, or mixtures of these such that a
copolyester is produced. Suitable glycols, in addition to ethylene
glycol and 1,4-cyclohexane diol, include propylene glycol,
1,3-propanediol, glycerol, 1,2-butanediol, 1,4-butanediol,
pentaerythritol, neopentylglycol, similar glycols and diols, and
mixtures thereof. These compounds and the processes for making
polyesters and copolyesters using the compounds are all well known
in the art.
[0051] Conventional production of polyethylene terephthalate (and
other polyesters such as other terephthalate, isophthalate and
mixed terephthalate-isophthalate polyesters) comprises reacting
terephthalic acid or dimethyl terephthalate with ethylene glycol at
a temperature of about 200.degree. C. to about 250.degree. C. to
form monomers and water (or methanol). Because the reaction is
reversible, the water (or methanol) is continuously removed to
drive the reaction to the production of monomer. Next, the monomer
undergoes a polycondensation reaction to form the polymer. During
the reaction of the terephthalic acid or dimethyl terephthalate and
ethylene glycol, it is not necessary to have a catalyst present
although it may be advantageous to do so to increase the rate of
reaction. Generally, during the polycondensation reaction, the use
of a catalyst is preferred, for example, antimony compounds or
other catalyst known to those skilled in the art. In the making of
bottle preforms and plastic bottles from the preforms, it is
desirable to produce the cleanest, clearest polymer. Generally, the
less additives employed, the clearer the polymer produced.
Conversely, it is sometimes desirable to make a colored plastic
bottle which means that the bottle preform may also be colored.
Accordingly, various pigments, dyes, fillers and other substances
known to those skilled in the art may be added to the polymer,
generally during or near the end of the polycondensation reaction.
The specific additives used and the point of introduction during
the reaction is known in the art and does not form a part of the
present invention. Any conventional system may be employed and
those skilled in the art can pick and choose among the various
systems for the introduction of additives to select the best for
the desired result.
[0052] The polyester containers of the present invention can be
made using well known processes for producing containers from
polyesters. Such processes include injection stretch blow molding
and extrusion blow molding. Preferably, such containers are bottles
made using a conventional blow molding process well known to
skilled artisans.
[0053] In another aspect, the present invention provides antiblock
agents useful in the production of polyester and polyester
containers in the form of talc that has been dried to contain from
about 20 to about 300 ppm water. The talc can be treated by any
conventional method for removing water but is preferably dried in a
conventional oven. The talc is added to polyesters during the
production process to produce polyesters and polyester containers
having a reduced coefficient of friction and acceptable
clarity.
[0054] In a further aspect, the present invention provides
antiblock agents useful in the production of polyester and
polyester containers in the form of dried talc that has been
treated with fatty acids to produce a tethered talc.
[0055] Suitable polyesters useful in the present invention are well
known in the art and are generally formed from repeat units
comprising terephthalic acid, dimethyl terephthalate, isophthalic
acid, dimethyl isophthalate, dimethyl-2,6-naphthalenedicarboxylate,
2,6-naphthalenedicarboxylic acid, ethylene glycol, diethylene
glycol, 1,4-cyclohexane-dimethanol, 1,4-butanediol, and mixtures
thereof.
[0056] The dicarboxylic acid component of the polyester may
optionally be modified with up to about 15 mole percent of one or
more different dicarboxylic acids. Such additional dicarboxylic
acids include aromatic dicarboxylic acids preferably having 8 to 14
carbon atoms, aliphatic dicarboxylic acids preferably having 4 to
12 carbon atoms, or cycloaliphatic dicarboxylic acids preferably
having 8 to 12 carbon atoms. Examples of dicarboxylic acids to be
included with terephthaic acid are: phthalic acid, isophthalic
acid, naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic
acid, cyclohexanediacetic acid, diphenyl-4,4'-dicarboxylic acid,
succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic
acid, mixtures thereof and the like.
[0057] In addition, the glycol component may optionally be modified
with up to about 15 mole percent, of one or more different diols
other than ethylene glycol. Such additional diols include
cycloaliphatic diols preferably having 6 to 20 carbon atoms or
aliphatic diols preferably having 3 to 20 carbon atoms. Examples of
such diols include: diethylene glycol, triethylene glycol,
1,4-cyclohexanedimethanol, propane-1,3-diol, butane-1,4-diol,
pentane-1,5-diol, hexane-1,6-diol, 3-methylpentanediol-(2,4),
2-methylpentanediol-(1,4), 2,2,4-trimethylpentane-diol-(1,3),
2-ethylhexanediol-(1,3), 2,2-diethylpropane-diol-(1,3),
hexanediol-(1,3), 1,4di-(hydroxyethoxy)-benzene,
2,2-bis-(4-hydroxycyclohexyl)-propane,
2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane,
2,2-bis-(3-hydroxyethoxyphenyl)-propane,
2,2-bis-(4-hydroxypropoxyphenyl)-propane, mixtures thereof and the
like. Polyesters may be prepared from two or more of the above
diols.
[0058] The preferred polyesters of the present invention are
poly(ethyleneterephthalate) (PET"), poly(ethylenenaphthalate)
("PEN"), poly(ethyleneisophthalate) ("PIT"), and
poly(ethylenebutyleneterephthalate), with PET being the most
preferred., most preferably poly(ethyleneterephthalate)
("PET").
[0059] The polyester may also contain small amounts of
trifunctional or tetrafunctional comonomers such as trimellitic
anhydride, trimethylolpropane, pyromellitic dianhydride,
pentaerythritol, and other polyester forming polyacids or polyols
generally known in the art.
[0060] Also, although not required, other additives normally used
in polyesters may be added to the polyester. Such additives
include, but are not limited to colorants, toners, pigments, carbon
black, glass fibers, fillers, impact modifiers, antioxidants,
stabilizers, flame retardants, reheat aids, acetaldehyde reducing
compounds, oxygen scavengers, barrier enhancing aids and the
like.
[0061] This invention can be further illustrated by the following
examples of preferred embodiments thereof, although it will be
understood that these examples are included merely for purposes of
illustration and are not intended to limit the scope of the
invention unless otherwise specifically indicated.
EXAMPLES 1 THROUGH 51
[0062] The antiblock agents Ba.sub.2SO.sub.4, talc, and SiO.sub.2
were added to PET CB-12 (CB-12 is a copolyester of terephthalic
acid, isophthalic acid, and ethylene glycol commercially available
from Eastman Chemical Company as ESTAPAK.RTM. CSC Resin) at
concentrations of 0.0125 to 0.10 wt % with particle sizes ranging
from 20 nanometers to 7 microns. The "undried" antiblock agents
were incorporated into the PET in the form of concentrates made by
two processes: (1) melt blending on a twin screw extruder into a
1.0 wt % concentrate ("SC/MB") and (2) in situ in the PET
preparation to make a 1.0 wt % concentrate ("MBC/MB"). Both methods
were evaluated in PET bottles by injection molding pellet/pellet
blends on an eight cavity Husky injection molding machine to make
2-liter preforms. The resulting preforms were stretch blown on a
SIDEL 2/3 stretch blow molding machine into 2-liter bottles. The
bottles were analyzed for their haze level (sidewall haze was
measured using ASTM D-1003) and for coefficient of friction by
mounting two bottles perpendicular and in contact with each other,
turning one bottle and measuring torque required to turn the second
bottle. The coefficient of friction was calculated as
.mu.=(Torque/R)/F.sub.2, where Torque is the output of the
torque-sensing device, R is the bottle radius, and F.sub.2 is the
actual load or force experienced by the bottles at their contact
point. The results are shown in Tables 1, 2, and 3 and FIGS. 1
through 8. FIGS. 1 through 6 are graphs comparing the haze, COF,
loadings, and particle sizes of the samples. Referring to the
Tables and Figures, a comparison of the data show that the
polyesters and polyester containers made according to the present
invention have a reduced coefficient of friction and acceptable
clarity.
[0063] FIG. 7 shows that the resulting COF's are very similar for a
given loading of antiblock. Comparison of bottle sidewall haze is
shown in FIG. 8. The results show that containers made using the
talc have a have a slightly higher clarity when compared to
containers made using SiO.sub.2 and Ba.sub.2SO.sub.4.
TABLE-US-00001 TABLE 1 Coefficient of Friction for PET/Talc Blends
Prep Particle Bottle COF Sidewall Ex. # Polymer Method size (.mu.)
wt % Ave Stdev Haze 1 CB-12 SC./MB 0.2 0.0125 0.633 0.063 1.62 2
CB-12 SC./MB 0.2 0.025 0.487 0.042 3.22 3 CB-12 SC./MB 0.2 0.05
0.415 0.059 7.01 4 CB-12 SC./MB 0.2 0.1 0.372 0.029 12.54 5 CB-12
SC./MB 7 0.0125 0.827 0.074 1.84 6 CB-12 SC./MB 7 0.025 0.425 0.029
4.08 7 CB-12 SC./MB 7 0.05 0.411 0.068 7.25 8 CB-12 SC./MB 7 0.1
0.360 0.036 13.96 9 CB-12 MBC/MB 7 0.0125 0.953 0.200 2.71 10 CB-12
MBC/MB 7 0.025 0.575 0.018 4.58 11 CB-12 MBC/MB 7 0.05 0.516 0.070
8.43 12 CB-12 MBC/MB 7 0.1 0.485 0.053 14.22
[0064] TABLE-US-00002 TABLE 2 Coefficient of Friction for
PET/BaSO.sub.4 Blends Particle wt % COF % Haze Example Polymer Prep
Method Size (.mu.) BaSO.sub.4 (Ave of 4 sets) (Measured) 13 CB-12
-- 0 1.443 1.07 14 CB-12/PP SC/MB -- 0 1.617 0.7 PET 15 CB-12 SC/MB
<1 0.0125 1.136 4.53 16 CB-12 SC/MB <1 0.025 0.649 8.85 17
CB-12 SC/MB <1 0.05 0.397 14.5 18 CB-12 SC/MB <1 0.1 0.345
33.35 19 CB-12 SC/MB 3 0.0125 0.731 2.8 20 CB-12 SC/MB 3 0.025
0.413 5.83 21 CB-12 SC/MB 3 0.05 0.270 9.16 22 CB-12 SC/MB 3 0.1
0.247 14.54 23 CB-12 SC./MB 1 0.0125 0.996 4.22 24 CB-12 SC/MB 1
0.025 0.467 9.76 25 CB-12 SC/MB 1 0.05 0.328 16.12 26 CB-12 SC/MB 1
0.1 0.320 30.56 27 CB-12 MBC/MB <1 0.0125 1.076 3.67 28 CB-12
MBC/MB <1 0.025 0.840 7.95 29 CB-12 MBC/MB <1 0.05 0.355
14.64 30 CB-12 MBC/MB <1 0.1 0.282 25.08 31 CB-12 MBC/MB 3
0.0125 0.714 4.17 32 CB-12 MBC/MB 3 0.025 0.294 6.89 33 CB-12
MBC/MB 3 0.05 0.224 12.57 34 CB-12 MBC/MB 3 0.1 0.189 24.08 35
CB-12 MBC/MB 1 0.0125 0.973 4.89 36 CB-12 MBC/MB 1 0.025 0.479 9.42
37 CB-12 MBC/MB 1 0.05 0.282 14.05 38 CB-12 MBC/MB 1 0.1 0.268
25.06
[0065] TABLE-US-00003 TABLE 3 Coefficient of Friction for
PET/SiO.sub.2 Blends SiO.sub.2 % Haze Ex- Prep PartSize wt % Bottle
COF (ASTM ample Polymer Method (.mu.) SiO.sub.2 Ave Stdev D-1003)
39 CB-12l none -- 0 1.443 0.061 1.07 40 CB-12 SC/MB 0.02 0.0125
1.536 0.191 1.34 41 CB-12 SC/MB 0.02 0.025 1.348 0.148 1.55 42
CB-12 SC/MB 0.02 0.05 1.090 0.092 2.15 43 CB-12 SC/MB 0.02 0.1
0.932 0.143 5.94 44 CB-12 SC/MB 5 0.0125 0.760 0.260 5.28 45 CB-12
SC/MB 5 0.025 0.362 0.079 9.95 46 CB-12 SC/MB 5 0.05 0.324 0.058
20.31 47 CB-12 SC/MB 5 0.1 0.278 0.022 33.53 48 CB-12 MBC/MB 5
0.0125 0.674 0.088 4.3 49 CB-12 MBC/MB 5 0.025 0.317 0.080 8.34 50
CB-12 MBC/MB 5 0.05 0.293 0.057 12.3 51 CB-12 MBC/MB 5 0.1 0.278
0.023 20.72
EXAMPLES 52 THROUGH 63
[0066] Polar talc 9107 (7 micron) was dried to approximately 250
ppm moisture and then added to PET reaction mixture at a loading of
1.0 wt %. The resulting concentrate was used to make blends as
described in Example 1. The resulting COF and haze (measured using
ASTM D-1003) were determined on the bottles and bottle sidewalls,
respectively. Coefficient of friction was measured by mounting two
bottles perpendicular and in contact with each other, turning one
bottle and measuring torque required to turn the second bottle. The
coefficient of friction was calculated as .mu.=(Torque/R)/F.sub.2,
where Torque is the output of the torque-sensing device, R is the
bottle radius, and F.sub.2 is the actual load or force experienced
by the bottles at their contact point. The results are shown in
Table 4 (COF is an average of 4 tests and % Haze is an average of 3
tests). When compared to bottles prepared with "undried" talc
(Examples 61, 62, and 63), the results shown graphically in FIG. 9
show that a significant improvement in bottle sidewall COF was
obtained at similar loadings when using the "dried" talc. FIG. 10
shows that a significant improvement in % haze was obtained at
similar loadings when using the "dried" talc. TABLE-US-00004 TABLE
4 Example wt % Talc Talc, Dried or Undried COF % Haze 52 0 Control
Sample 1.28 1.04 53 0.01 Dried 0.35 2.23 54 0.015 Dried 0.25 3.55
55 0.02 Dried 0.26 3.23 56 0.025 Dried 0.22 4.73 57 0.03 Dried 0.22
4.95 58 0 Control Sample 1.19 0.96 (repeat) 59 0.01 Dried 0.27 2.21
(repeat) 60 0 Control Sample 1.443 1.070 61 0.0125 Undried 0.827
1.62 62 0.025 Undried 0.425 3.22 63 0.05 Undried 0.411 7.01
[0067] In the drawings and specification, there have been disclosed
typical preferred embodiments of the invention and, although
specific terms are employed, they are used in a generic and
descriptive sense only and not for purposes of limitation, the
scope of the invention being set forth in the following claims.
Obviously many modifications and variations of the present
invention are possible in light of the above teachings. It is
therefore to be understood that within the scope of the appended
claims the invention may be practiced otherwise than as
specifically described.
* * * * *