U.S. patent application number 11/786247 was filed with the patent office on 2007-08-16 for rubber modified styrenic copolymers and their use in disposable card applications.
Invention is credited to Richard JR. Delaney, Michael W. Desmarais, Richard W. Desmarais, John Chi Hee Kwok.
Application Number | 20070191543 11/786247 |
Document ID | / |
Family ID | 36654121 |
Filed Date | 2007-08-16 |
United States Patent
Application |
20070191543 |
Kind Code |
A1 |
Hee Kwok; John Chi ; et
al. |
August 16, 2007 |
Rubber modified styrenic copolymers and their use in disposable
card applications
Abstract
A thermoplastic sheet that includes a continuous phase and a
dispersed phase, where A) the continuous phase contains a polymer
composition resulting from the polymerization of a monomer mixture
containing a styrenic monomer and an alkyl (meth)acrylate monomer
in the presence of the dispersed phase; and B) the dispersed phase
contains one or more block copolymer selected from diblock and
triblock copolymers of styrene-butadiene,
styrene-butadiene-styrene, styrene-isoprene,
styrene-isoprene-styrene, partially hydrogenated
styrene-isoprene-styrene. The thermoplastic sheet is formed by
extruding a thermoplastic composition that is cut to desired
dimensions to form thermoplastic items, e.g. identification cards,
credit cards, bank cards, key cards, gift cards, phone cards,
playing cards, menus, and the like. Indicia and/or printing can be
applied to the items to provide for commercial applications. The
sheet may be opaque or may be relatively clear to transparent with
a Haze value of 0.01% up to 10%.
Inventors: |
Hee Kwok; John Chi; (Moon
Township, PA) ; Delaney; Richard JR.; (Lunenburg,
MA) ; Desmarais; Michael W.; (Hampton Falls, NH)
; Desmarais; Richard W.; (Manchester, NH) |
Correspondence
Address: |
Gary F. Matz;NOVA Chemicals Inc.
Westpointe Center
1550 Coraopolis Heights Road
Moon Township
PA
15108
US
|
Family ID: |
36654121 |
Appl. No.: |
11/786247 |
Filed: |
April 11, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11034084 |
Jan 12, 2005 |
7223460 |
|
|
11786247 |
Apr 11, 2007 |
|
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Current U.S.
Class: |
525/88 |
Current CPC
Class: |
C08L 35/06 20130101;
C08L 53/02 20130101; C08L 53/025 20130101; C08L 51/006 20130101;
C08L 51/006 20130101; C08L 2666/02 20130101; C08L 53/02 20130101;
C08L 2666/02 20130101; C08L 2666/02 20130101; C08L 2666/04
20130101; C08L 2666/24 20130101; C08L 2666/04 20130101; C08L
2666/24 20130101; C08L 53/025 20130101; C08L 35/06 20130101; C08L
33/06 20130101; C08L 33/06 20130101; C08L 53/025 20130101; C08F
287/00 20130101; Y10T 428/24479 20150115; C08L 53/02 20130101 |
Class at
Publication: |
525/088 |
International
Class: |
C08L 53/00 20060101
C08L053/00 |
Claims
1. A thermoplastic sheet comprising a continuous phase and a
dispersed phase, wherein: A) the continuous phase comprises a
polymer composition resulting from the polymerization of a monomer
mixture comprising (i) from about 25 parts by weight to 75 parts by
weight of a styrenic monomer and (ii) from about 25 parts by weight
to 75 parts by weight of an alkyl(meth)acrylate monomer, wherein
the alkyl group is a C.sub.1 to C.sub.12 linear, branched or cyclic
alkyl group, in the presence of the dispersed phase; and B) the
dispersed phase comprises from about 2 parts by weight to about 50
parts by weight of one or more block copolymers selected from the
group consisting of diblock and triblock copolymers of
styrene-butadiene, styrene-butadiene-styrene, styrene-isoprene,
styrene-isoprene-styrene, partially hydrogenated
styrene-isoprene-styrene, for a total of 100 parts by weight of the
combination of A) and B), wherein the thermoplastic sheet has a
Haze value of less than 10% and has a melt flow, as measured
according to ASTM D-1238 of at least 2.5 g/10 minutes.
2. The thermoplastic sheet according to claim 1, wherein the
dispersed phase B) is present as discrete particles dispersed
within the continuous phase A).
3. The thermoplastic sheet according to claim 2, wherein the volume
average particle size of the dispersed phase B) is from about 0.1
.mu.m to about 2 .mu.m.
4. (canceled)
5. The thermoplastic sheet according to claim 1, wherein the
difference between the refractive index of the continuous phase A)
and the dispersed phase B) is not more than 0.01.
6. The thermoplastic sheet according to claim 1, wherein the
styrenic monomer is selected from the group consisting of styrene,
p-methyl styrene, tertiary butyl styrene, dimethyl styrene, nuclear
brominated or chlorinated derivatives thereof and combinations
thereof.
7. The thermoplastic sheet according to claim 1, wherein the
alkyl(meth)acrylate monomer comprises methylmethacrylate and
optionally butyl acrylate.
8. The thermoplastic sheet according to claim 1, wherein the block
copolymer has a weight average molecular weight of not less than
about 75,000.
9. The thermoplastic sheet according to claim 1, wherein the block
copolymer is a linear or radial block copolymer.
10. The thermoplastic sheet according to claim 1, wherein the block
copolymer is a triblock styrene-butadiene-styrene or
styrene-isoprene-styrene copolymer having a weight average
molecular weight of from about 175,000 to about 275,000.
11. The thermoplastic sheet according to claim 1, wherein at least
some of the polymers in A) are grafted onto the block copolymer in
B).
12. The thermoplastic sheet according to claim 1, further
comprising a printed layer over at least a portion of a surface of
the thermoplastic sheet.
13. The thermoplastic sheet according to claim 12, wherein the
printed layer comprises an ink composition.
14. The thermoplastic sheet according to claim 1, having a
thickness of from about 0.05 mm to about 5 mm.
15. The thermoplastic sheet according to claim 1, wherein the sheet
is an opaque sheet further comprising pigments or colorants or
both.
16. The thermoplastic sheet according to claim 1, wherein the
thermoplastic sheet contains indicia thereon.
17. The thermoplastic sheet according to claim 1, wherein the sheet
is an opaque sheet further comprising one or more additives
selected from the group consisting of lubricants, fillers, light
stabilizers, heat stabilizers, surface active agents, and
combinations thereof.
18. The thermoplastic sheet according to claim 1, wherein the
monomer mixture further comprises a chain transfer agent.
19. A method of making a thermoplastic item comprising: extruding a
thermoplastic composition to form a thermoplastic sheet, wherein
the thermoplastic composition comprises a continuous phase and a
dispersed phase and has a Haze value of less than 10% and has a
melt flow, as measured according to ASTM D-1238 of at least 2.5
g/10 minutes, wherein A) the continuous phase comprises a polymer
composition resulting from the polymerization of a monomer mixture
comprising (i) from about 25 to 75 parts by weight of a styrenic
monomer and (ii) from about 25 to 75 parts by weight of an
alkyl(meth)acrylate monomer, wherein the alkyl group is a C.sub.1
to C.sub.12 linear, branched or cyclic alkyl group, in the presence
of the dispersed phase; and B) the dispersed phase comprises from
about 2 to about 50 parts by weight of one or more block copolymers
selected from the group consisting of diblock and triblock
copolymers of styrene-butadiene, styrene-butadiene-styrene,
styrene-isoprene, styrene-isoprene-styrene, partially hydrogenated
styrene-isoprene-styrene, for a total of 100 parts by weight of the
combination of A) and B); optionally surface treating the extruded
sheet; cutting the sheet to form a smaller sheet of desired
dimensions; printing on a surface of the smaller sheet; optionally
cutting the smaller sheet to desired item dimensions; and
optionally laminating the item.
20-38. (canceled)
39. A rectangular card made according to the method of claim
19.
40. The card according to claim 39, having a first dimensional
length of from about 2 cm to about 15 cm, a second dimension of
from about 1 cm to about 12 cm and a thickness of from about 0.05
mm to about 5 mm.
41-43. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention is directed to thermoplastic sheets
containing rubber modified styrenic copolymers and the use of said
sheets in making thermoplastic items.
[0003] 2. Description of the Prior Art
[0004] Plastic sheet laminates are commonly used in a variety of
applications, including identification cards, credit cards, bank
cards, key cards, gift cards and the like. Such laminates are
generally comprised of a relatively thick core layer containing
printed indicia on at least one side thereof, and a relatively
thin, transparent layer laminated to each side of the core layer.
For certain applications, particularly for credit cards, the
laminate is embossed and the raised areas are typically printed or
tipped with ink.
[0005] These laminates are typically made of plastic sheets
containing various thermoplastic blends including primarily
polyvinyl chloride homopolymers or copolymers. Typical credit card
laminates require properties such as stiffness, impact strength,
resilience and flexural durability sufficient to provide about a
one- to two-year service life.
[0006] In some applications, the printing and/or printed indicia is
applied on the protective or laminated layer and then
reverse-laminated onto the core layer.
[0007] As an example, U.S. Pat. No. 5,543,466 to Norman discloses
laminates for use in credit card applications that have at least
one core layer and at least one over layer on each side. The core
layer composition includes polyvinyl chloride, a copolymer derived
from vinyl chloride and vinyl ester monomers, at least one acrylic
resin polymer, as well as a copolymer derived from ethylene and
vinyl acetate monomers. The core layer is corona treated in order
to improve ink adhesion thereto. The overlay composition is similar
but generally is transparent. The laminated credit card can
optionally contain a magnetic strip on the over layer or a
microchip therein.
[0008] A particular drawback to polyvinyl chloride based cards is
their generally poor printability or ink acceptability. As
indicated in the Norman patent, the core layer requires corona
treatment in order to improve ink adhesion and is further totally
laminated to protect the printed layer. The extra processing steps
required for protective lamination add considerable cost to the
final card. The elimination of these steps and their added cost is
an ongoing objective in the art.
[0009] U.S. Pat. No. 4,772,667 to Biletch et al. discloses a
thermoplastic polymer that includes a styrenic monomer, an
acrylate, a methacrylate and a block copolymer.
[0010] U.S. Pat. No. 5,290,862 to Blasius discloses a polymer alloy
that contains from 30 to 83 weight percent of a brittle polymer;
from 3 to 50 weight percent of a rubbery polymer; and from 15 to 67
weight percent of a ductile polymer, provided that the ductile
polymer and the rubbery polymer are at least compatible.
[0011] U.S. Pat. No. 5,891,962 to Otsuzuki et al. discloses a
transparent, rubber-modified styrene resin that contains 70 to 96
parts by weight of a copolymer formed of 20 to 70 wt. % of styrene
monomer units and 30 to 80 wt. % of alkyl (meth)acrylate monomer
units and 4 to 30 parts by weight of a rubbery polymer. The rubbery
polymer is dispersed in the copolymer as particles and the
copolymer and the rubbery polymer have substantially the same
refractive index.
[0012] Heretofore, the above described thermoplastic polymer
compositions have not been used in sheet and/or disposable card
applications because they do not provide the required stiffness,
impact strength, resilience and flexural durability properties.
[0013] It would be desirable to provide a low cost thermoplastic
sheet material that can be used in disposable card applications
that provides sufficient stiffness, resilience and flexural
durability properties, while also having ink printability and ink
acceptability properties such that a lamination layer is not
required to protect the printed image.
SUMMARY OF THE INVENTION
[0014] The present invention provides a thermoplastic sheet that
includes a continuous phase and a dispersed phase, where:
[0015] A) the continuous phase contains a polymer composition
resulting from the polymerization of a monomer mixture including
(i) from about 25 to 75 parts by weight of a styrenic monomer and
(ii) from about 25 to 75 parts by weight of an alkyl (meth)acrylate
monomer, wherein the alkyl group is a C.sub.1 to C.sub.12 linear,
branched or cyclic alkyl group, in the presence of the dispersed
phase; and
[0016] B) the dispersed phase contains from about 2 to about 50
parts by weight of one or more block copolymers selected from
diblock and triblock copolymers of styrene-butadiene,
styrene-butadiene-styrene, styrene-isoprene,
styrene-isoprene-styrene, partially hydrogenated
styrene-isoprene-styrene, for a total of 100 parts by weight of the
combination of A) and B).
[0017] The present invention also provides a method of making a
thermoplastic item, e.g. card. The method includes the steps of:
[0018] extruding a thermoplastic composition to form the
above-described thermoplastic sheet, [0019] cutting the sheet to
form a thermoplastic item of desired dimensions; [0020] printing on
a surface of the item; and [0021] optionally laminating the
item.
[0022] The present invention is additionally directed to
thermoplastic items made according to the above-described
method.
DETAILED DESCRIPTION OF THE INVENTION
[0023] Other than in the operating examples or where otherwise
indicated, all numbers or expressions referring to quantities of
ingredients, reaction conditions, etc. used in the specification
and claims are to be understood as modified in all instances by the
term "about." Accordingly, unless indicated to the contrary, the
numerical parameters set forth in the following specification and
attached claims are approximations that may vary depending upon the
desired properties, which the present invention desires to obtain.
At the very least, and not as an attempt to limit the application
of the doctrine of equivalents to the scope of the claims, each
numerical parameter should at least be construed in light of the
number of reported significant digits and by applying ordinary
rounding techniques.
[0024] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical values, however,
inherently contain certain errors necessarily resulting from the
standard deviation found in their respective testing
measurements.
[0025] Also, it should be understood that any numerical range
recited herein is intended to include all sub-ranges subsumed
therein. For example, a range of "1 to 10" is intended to include
all sub-ranges between and including the recited minimum value of 1
and the recited maximum value of 10; that is, having a minimum
value equal to or greater than 1 and a maximum value of equal to or
less than 10. Because the disclosed numerical ranges are
continuous, they include every value between the minimum and
maximum values. Unless expressly indicated otherwise, the various
numerical ranges specified in this application are
approximations.
[0026] As used herein, the terms "(meth)acrylic" and
"(meth)acrylate" are meant to include both acrylic and methacrylic
acid derivatives, such as the corresponding alkyl esters often
referred to as acrylates and (meth)acrylates, which the term
"(meth)acrylate" is meant to encompass.
[0027] As used herein, the term "polymer" is meant to encompass,
without limitation, homopolymers, copolymers and graft
copolymers.
[0028] Unless otherwise specified, all molecular weight values are
determined using gel permeation chromatography (GPC) using
appropriate polystyrene standards. Unless otherwise indicated, the
molecular weight values indicated herein are weight average
molecular weights (Mw).
[0029] In making the present thermoplastic sheet, a particular
thermoplastic composition is used. The thermoplastic composition is
characterized as having a continuous phase and a dispersed phase.
The continuous phase contains a polymer composition resulting from
the polymerization of a monomer mixture containing styrenic and
alkyl(meth)acrylate monomers in the presence of the dispersed
phase.
[0030] The styrenic monomers are present in the monomer mixture at
a level of at least 25, in some cases at least 30 and in other
cases at least 35 parts by weight based on the combined weight of
the monomer mixture and the dispersed phase. Also, the styrenic
monomers are present in the monomer mixture at a level of up to 75,
in some cases up to 70, in other cases up to 65, in some instances
up to 60, in other instances up to 55 and in particular situations
up to 50 parts by weight based on the combined weight of the
monomer mixture and dispersed phase. The amount of styrenic monomer
is determined based on the physical properties desired in the
resulting thermoplastic sheet. The amount of styrenic monomer in
the monomer mixture can be any value recited above or can range
between any of the values recited above.
[0031] The alkyl(meth)acrylate monomers are present in the monomer
mixture at a level of at least 25, in some cases at least 30 and in
other cases at least 35 parts by weight based on the combined
weight of the monomer mixture and dispersed phase. Also, the
alkyl(meth)acrylate monomers are present in the monomer mixture at
a level of up to 75, in some cases up to 70, in other cases up to
65, in some instances up to 60, in other instances up to 55 and in
particular situations up to 50 parts by weight based on the
combined weight of the monomer mixture and dispersed phase. The
amount and type of alkyl(meth)acrylate monomers is determined based
on the physical properties desired in the resulting thermoplastic
sheet. The alkyl group in the alkyl(meth)acrylate monomers can be a
C.sub.1 to C.sub.12, in some cases a C.sub.1 to C.sub.8 and in
other cases a C.sub.1 to C.sub.4 linear, branched or cyclic alkyl
group. The amount and type of alkyl(meth)acrylate monomers in the
monomer mixture can be any value recited above or can range between
any of the values recited above.
[0032] In an embodiment of the invention, the styrenic monomer is
selected from styrene, p-methyl styrene, tertiary butyl styrene,
dimethyl styrene, nuclear brominated or chlorinated derivatives
thereof and combinations thereof.
[0033] In another embodiment of the invention, the
alkyl(meth)acrylate monomers include methylmethacrylate and
optionally butyl acrylate.
[0034] In an embodiment of the invention, the monomer mixture
includes one or more chain transfer agents. Any chain transfer
agent that effectively controls the molecular weight of the
styrenic/alkyl(meth)acrylate copolymers can be used in the
invention. Non-limiting examples of suitable chain transfer agents
include alkyl mercaptans according to the structure R--SH, where R
represents a C.sub.1 to C.sub.32 linear, branched or cyclic alkyl
or alkenyl group; mercaptoacids according to the structure
HS--R--COOX, where R is as defined above and X is H, a metal ion,
N.sup.+H.sub.4 or a cationic amine salt; dimers or cross-dimers of
.alpha.-methylstyrene, methyl methacrylate, hydroxy ethylacrylate,
benzyl methacrylate, allyl methacrylate, methacrylonitrile,
glycidyl methacrylate, methacrylic acid, tert-butyl methacrylate,
isocyanatoethyl methacrylate,
meta-isopropenyl-.alpha.,.alpha.-dimethyl isocyanate,
.omega.-sulfoxyalkyl methacrylates and alkali salts thereof.
Suitable dimers that can be used in the invention are disclosed,
for example, in U.S. Patent Application Publication No.
2004/0176527, the relevant portions of which are herein
incorporated herein by reference.
[0035] When used, the one or more chain transfer agents may be
present in the monomer mixture at a level of from at least 0.001
wt. %, in some cases at least 0.01 wt. % and in other cases at
least 0.1 wt. % and up to 10 wt. %, in some cases up to 7.5 wt. %
and in other cases up to 5 wt. % of the monomer mixture. The amount
of chain transfer agent can be any value or can range between any
of the values recited above.
[0036] The dispersed phase is present in the thermoplastic
composition at a level of at least 2 parts by weight, in some cases
at least 3 parts by weight, in other cases at least 5 parts by
weight, and in some situations at least 10 parts by weight based on
the combined weight of the monomer mixture and dispersed phase.
Also, the dispersed phase is present in the thermoplastic
composition at a level of up to 50 parts by weight, in some cases
up to 45 parts by weight, in other cases up to 40 parts by weight,
in some instances up to 35 parts by weight, in other instances up
to 30 parts by weight, and in particular situations up to 25 parts
by weight based on the combined weight of the monomer mixture and
dispersed phase. The amount of dispersed phase is determined based
on the physical properties desired in the resulting thermoplastic
sheet. The amount of dispersed phase in the thermoplastic
composition can be any value recited above or can range between any
of the values recited above.
[0037] The dispersed phase desirably contains one or more block
copolymers, which can be rubbery block copolymers. Desirably, the
block copolymers include one or more diblock and triblock
copolymers of styrene-butadiene, styrene-butadiene-styrene,
styrene-isoprene, styrene-isoprene-styrene and partially
hydrogenated styrene-isoprene-styrene. Examples of suitable block
copolymers include, but are not limited to, the STEREON.RTM. block
copolymers available from the Firestone Tire and Rubber Company,
Akron Ohio; the ASAPRENE.TM. block copolymers available from Asahi
Kasei Chemicals Corporation, Tokyo Japan; the KRATON.RTM. block
copolymers available from Kraton Polymers, Houston, Tex.; and the
VECTOR.RTM. block copolymers available from Dexco Polymers LP,
Houston, Tex.
[0038] In an embodiment of the invention, the block copolymer is a
linear or radial block copolymer.
[0039] In an embodiment of the invention, the block copolymer has a
weight average molecular weight of at least 50,000 and in some
cases not less than about 75,000, and can be up to 500,000, in some
cases up to 400,000 and in other cases up to 300,000. The weight
average molecular weight of the block copolymer can be any value or
can range between any of the values recited above.
[0040] In another embodiment of the invention, the block copolymer
is a triblock styrene-butadiene-styrene or styrene-isoprene-styrene
copolymer having a weight average molecular weight of from about
175,000 to about 275,000.
[0041] In a further embodiment of the invention, at least some of
the polymers in the continuous phase are grafted onto the block
copolymer in the dispersed phase.
[0042] In an embodiment of the invention, the dispersed phase is
present as discrete particles dispersed within the continuous
phase. Further to this embodiment, the volume average particle size
of the dispersed phase in the continuous phase is at least about
0.1 .mu.m, in some cases at least 0.2 .mu.m and in other cases at
least 0.25 .mu.m. Also, the volume average particle size of the
dispersed phase in the continuous phase can be up to about 2 .mu.m,
in some cases up to 1.5 .mu.m and in other cases up to 1 .mu.m. The
particle size of the dispersed phase in the continuous phase can be
any value recited above and can range between any of the values
recited above.
[0043] In another embodiment of the invention, the aspect ratio of
the discrete particles is from at least about 1, in some cases at
least about 1.5 and in other cases at least about 2 and can be up
to about 5, in some cases up to about 4 and in other cases at least
up to about 3. When the aspect ratio of the dispersed particles is
too large, the resulting thermoplastic sheet is hazy and not clear
or transparent. The aspect ratio of the dispersed discrete
particles can be any value or range between any of the values
recited above. As a non-limiting example, the aspect ratio can be
measured by scanning electron microscopy or light scattering.
[0044] The particle size and aspect ratio of the dispersed phase
can be determined using low angle light scattering. As a
non-limiting example, a Model LA-910 Laser Diffraction Particle
Size Analyzer available from Horiba Ltd., Kyoto, Japan can be used.
As a non-limiting example, a rubber-modified polystyrene sample can
be dispersed in methyl ethyl ketone. The suspended rubber particles
can then be placed in a glass cell and subjected to light
scattering. The scattered light from the particles in the cell can
be passed through a condenser lens and converted into electric
signals by detectors located around the sample cell. As a
non-limiting example, a He--Ne laser and/or a tungsten lamp can be
used to supply light with a shorter wavelength. Particle size
distribution can be calculated based on Mie scattering theory from
the angular measurement of the scattered light.
[0045] The thermoplastic composition is formed by dispersing the
dispersed phase in a monomer mixture containing styrenic and
alkyl(meth)acrylate monomers, deaerating or sparging with nitrogen,
while mixing and adding a suitable free radical polymerization
initiator at a suitable temperature to effect free radical
polymerization. In an embodiment of the invention, at least some of
the monomer mixture reacts with unsaturated groups in the dispersed
phase to provide grafting to the dispersed phase. Methods for
polymerizing the monomer mixture and dispersed phase are known in
the art. Examples of such methods are disclosed in, as non-limiting
examples, U.S. Pat. No. 4,772,667 to Biletch et al., and U.S. Pat.
No. 5,891,962 to Otsuzuki et al., the relevant portions of which
are herein incorporated by reference. Desirably, the manufacturing
conditions are adapted to provide thermoplastic compositions,
thermoplastic sheets and thermoplastic items having the properties
described herein.
[0046] Any suitable polymerization initiator can be used in the
invention. Non-limiting examples of suitable polymerization
initiators include dibenzoyl peroxide, di-tert-butyl peroxide,
dilauryl peroxide, dicumyl peroxide, didecanoyl peroxide,
tert-butyl peroxy-2-ethylhexanoate, tert-butyl perpivalate,
tert-butyl peroxyacetate, or butyl peroxybenzoate and also azo
compounds, e.g., 2,2'-azobis(2,4-dimethylvaleronitrile),
2,2-azobis-(isobutyronitrile),
2,2'-azobis(2,3-dimethylbutyronitrile),
1,1'-azobis-(1-cyclohexanenitrile), as well as combinations of any
of the above.
[0047] In an embodiment of the invention, the difference between
the refractive index of the continuous phase and the dispersed
phase is not more than 0.01 and in some cases not more than
0.001.
[0048] In an embodiment of the invention, the adjuvants include
pigments or colorants or both. The pigments and/or colorants can be
included in the thermoplastic composition and are included as part
of the resulting thermoplastic sheet. As non-limiting examples, the
pigments and/or colorants can include titanium dioxide. The
pigments and/or colorants when added to the thermoplastic
composition will generally result in an opaque sheet. A clear or
transparent sheet can be defined as having Haze values of 10% or
less, and it is known to those skilled in the art that Haze values
generally do not apply to an opaque sheet.
[0049] As used herein, "pigments and/or colorants" refer to any
suitable inorganic or organic pigment or organic dyestuff. Suitable
pigments and/or colorants are those that do not adversely impact
the desirable physical properties of the thermoplastic sheet.
Non-limiting examples of inorganic pigments include titanium
dioxide, iron oxide, zinc chromate, cadmium sulfides, chromium
oxides and sodium aluminum silicate complexes. Non-limiting
examples of organic type pigments include azo and diazo pigments,
carbon black, phthalocyanines, quinacridone pigments, perylene
pigments, isoindolinone, anthraquinones, thioindigo and solvent
dyes.
[0050] In another embodiment of the invention, the adjuvants can
include one or more additives selected from lubricants, fillers,
light stabilizers, heat stabilizers, surface-active agents, and
combinations thereof. These additives, when added to the
thermoplastic composition will generally result in an opaque
sheet.
[0051] Suitable fillers are those that do not adversely impact, and
in some cases enhance, the desirable physical properties of the
thermoplastic sheet. Suitable fillers include, but are not limited
to, calcium carbonate in ground and precipitated form, barium
sulfate, talc, glass, clays such as kaolin and montmorolites, mica,
and combinations thereof.
[0052] Suitable lubricants include, but are not limited to, ester
waxes such as the glycerol types, the polymeric complex esters, the
oxidized polyethylene type ester waxes and the like, metallic
stearates such as barium, calcium, magnesium, zinc and aluminum
stearate, and/or combinations thereof.
[0053] Generally, any conventional ultra-violet light (UV)
stabilizer known in the art can be utilized in the present
invention. Non-limiting examples of suitable UV stabilizers include
2-hydroxy-4-(octyloxy)-benzophenone, 2-hydroxy-4-(octyl oxy)-phenyl
phenyl-methanone, 2-(2'-hydroxy-3,5'di-teramylphenyl)benzotriazole,
and the family of UV stabilizers available under the trade
TINUVIN.RTM. from Ciba Specialty Chemicals Co., Tarrytown, N.Y.
[0054] Heat stabilizers that can be used in the invention include,
but are not limited to, hindered phenols, non-limiting examples
being the IRGANOX.RTM. stabilizers and antioxidants available from
Ciba Specialty Chemicals.
[0055] When any or all of the indicated adjuvants are used in the
present invention, they can be used at a level of at least 0.01
weight percent, in some cases at least 0.1 weight percent and in
other cases at least 0.5 and up to 10 weight percent, in some cases
up to 7.5 weight percent, in other cases up to 5 weight percent,
and in some situations up to 2.5 weight percent of the
thermoplastic composition and/or the thermoplastic sheet of the
invention. The amount, type and combination of adjuvants used will
depend on the particular properties desired in the thermoplastic
sheet. The amount of any single adjuvant or any combination of
adjuvants can be any value recited above and can range between any
of the values recited above.
[0056] Thorough mixing and dispersion of the additive in the
thermoplastic composition is important, but otherwise processing
conditions are similar to those typically employed in the art.
[0057] The present thermoplastic sheet is prepared by working the
above-described thermoplastic composition to form the thermoplastic
sheet. Desirably, the thermoplastic composition, along with any
desired adjuvants and/or other polymers are combined, may be mixed
on a heated mill roll or other compounding equipment, and the
mixture cooled, granulated and extruded into a sheet. The
formulation may be admixed in extruders, such as single-screw or
double-screw extruders, compounded and extruded into pellets, which
may be then re-fabricated. The extruder may also be used to extrude
the composition as pipe, sheet, film or profile.
[0058] The thermoplastic composition can be extruded at a
temperature that allows for formation of a sheet with the desired
physical properties. In an embodiment of the invention, the
thermoplastic composition is extruded at from at least about
400.degree. F. (204.degree. C.), in some cases at least about
450.degree. F. (232.degree. C.) and up to about 550.degree. F.
(288.degree. C.), in some cases up to about 500.degree. F.
(260.degree. C.). The extrusion temperature can be any temperature
or range between any of the temperatures indicated above.
[0059] Films or sheets may be uniaxially or biaxially oriented
either during extrusion or after such processing by reheating and
stretching.
[0060] Granules of the thermoplastic composition may be molded or
extruded into appropriate parisons which are then treated by
conventional molding and blowing techniques into bottles or other
containers, which containers may be stretch oriented uniaxially or
biaxially, or may be left unoriented. It is known in the art for
such containers to have closures that allow them to be sealed or
capped.
[0061] Films or sheets may be treated with additives after forming,
such as appropriate heat-seal adhesives, coatings for ink
adhesions, printing, labels, and the like.
[0062] In an embodiment of the invention, the thermoplastic sheet
has a melt flow of from at least about 1.0 g/10 minutes, in some
cases at least about 2.5 g/10 minutes, and in other cases at least
about 3 g/10 minutes, and up to about 10 g/10 minutes, in some
cases up to 4.5 g/10 minutes, and in other cases up to 4 g/10
minutes measured according to ASTM D-1238. The melt flow of the
thermoplastic sheet can be any value, or can range between any of
the values recited above.
[0063] In an embodiment of the invention, a clear sheet is desired
and/or required. For clear sheets, the thermoplastic sheet has a
Haze value of from at least about 0.01 % and can be up to about
10%, in some cases up to 7.5%, in other cases up to 5% and in some
situations up to 4%. The Haze value of a sheet sample is measured
using a ColorQuest.RTM. XE-Touch reflectance/transmittance
spectrophotometer equipped with Universal.RTM. color quality
control software, available from Hunter Associates Laboratory,
Inc., Reston, Va. The Haze value of the thermoplastic sheet can be
any value, or can range between any of the values recited
above.
[0064] In an embodiment of the invention, the tensile strength
(tensile break) of the thermoplastic sheet is at least about 3,500
psi, in some cases at least about 4,000 psi and in other cases at
least about 5,000 psi and can be up to about 10,000 psi, in some
cases up to 9,000 psi, in other cases up to 8,000 psi and in some
situations up to 7,000 psi measured according to ASTM D-638. The
tensile strength of the thermoplastic sheet can be any value, or
can range between any of the values recited above.
[0065] In an embodiment of the invention, the flexural modulus
tensile of the thermoplastic sheet is at least about 100,000 psi,
in some cases at least about 200,000 psi and in other cases at
least about 300,000 psi and can be up to about 700,000 psi, in some
cases up to 600,000 psi, in other cases up to 500,000 psi and in
some situations up to 400,000 psi measured according to ASTM D-790.
The tensile strength of the thermoplastic sheet can be any value,
or can range between any of the values recited above.
[0066] In an embodiment of the invention, the thermoplastic sheet
can have a thickness of at least about 0.05 mm, in some cases at
least about 0.1 mm and in other cases at least about 0.25 mm and
can be up to about 5 mm, in some case up to about 4 mm and in other
cases up to about 5 mm. The thickness of the thermoplastic sheet
can vary depending on its intended use. The thickness of the
thermoplastic sheet can be any value or can range between any of
the values recited above.
[0067] Once formed, printing can be applied to the present
thermoplastic sheet. Typically, a printed layer is applied over at
least a portion of a surface of the thermoplastic sheet. The
printed layer can be applied using art known methods, not limited
to, offset printing, gravure printing, stamping, and the like.
[0068] In an embodiment of the invention, the surface of the sheet
can be treated prior to printing. Any suitable surface treatment
that improves the quality of the printing and/or improves the
printability of the sheet surface can be used. As a non-limiting
example, the surface treatment can be an oxidative surface
treatment, a non-limiting example being corona discharge, which can
be used to improve ink receptivity prior to printing. As a
non-limiting example, the corona treatment can be applied using one
of the UNI-DYNE.RTM. corona systems available from Corotec
Corporation, Farmington, Conn.
[0069] Desirably, the printed layer includes an ink composition.
Any suitable ink composition known in the art can be used, so long
as the ink composition is substantive to the thermoplastic
sheet.
[0070] In an embodiment of the invention, the thermoplastic sheet
has a Fatigue Test value of at least about 5,000 cycles, in some
cases at least about 10,000 cycles and in other cases at least
about 15,000 cycles. The Fatigue Test is meant to simulate card
use, for example the action of inserting a key card into a slot
opening. The Fatigue Test or assessment of the flexural fatigue
properties of an extruded sheet can be conducted using a
servo-hydraulic load frame. The intent is to simulate the
incomplete or obstructed insertion of a keycard into a reader.
Specimens are cut one inch in width, with one end clamped to a
reciprocating hydraulic actuator while the other is fed into a
stationary blind slot. The actuator is cycled over about a
0.75-inch stroke, with about 3.75 inches of unsupported sheet. The
resultant deflection at mid-span of the sheet is about 0.75 inches.
This flexing action is repeated at 120 cycles per minute until the
sheet fails. In particular embodiments of the invention, the sheet
lasts at least and sometimes in excess of 30,000 cycles.
[0071] In an embodiment of the invention, physical indicia, such as
magnetic strips, code bars, pictures, microchips, computer printed
pictures and other information, can also be applied to a surface of
the thermoplastic sheet. The indicia can be laminated with or
without adhesives to the thermoplastic sheet.
[0072] In a particular embodiment of the invention, the magnetic
strip is applied and/or adhered to a surface of the thermoplastic
sheet.
[0073] In another particular embodiment, a computer chip or
microchip can be utilized where a portion of the thermoplastic
sheet, the same size and thickness and shape as the computer chip
or microchip, is removed, and a computer chip or microchip is
adhered to the thermoplastic sheet.
[0074] Aspects of the present invention also provide a method of
making a thermoplastic item including the steps of: [0075]
extruding a thermoplastic composition to form a thermoplastic sheet
where the thermoplastic composition and extrusion are as described
above; [0076] optionally surface treating the extruded sheet;
[0077] cutting the sheet to form a smaller sheet of desired
dimensions; [0078] printing on a surface of the smaller sheet;
[0079] optionally cutting the smaller sheet to desired item
dimensions; and [0080] optionally laminating the item. Depending on
the particular manufacturing configuration, the thermoplastic sheet
can be printed and then cut, or cut and then printed, or printed,
cut and then printed again. Thus the order of the cutting, printing
and laminating steps can be changed to suit the available equipment
or desired item. The thermoplastic items made according to the
present method can include many commonly used articles. As
non-limiting examples, the thermoplastic items can include
identification cards, credit cards, bank cards, key cards, gift
cards, phone cards, playing cards, menus, game pieces, signs,
decorations, and the like.
[0081] Any surface treatment that improves printability and/or
print quality can be used. In an embodiment of the invention, the
surface treatment is an oxidative surface treatment, as a
non-limiting example, the surface treatment can include corona
discharge treatment as described above.
[0082] Any suitable method can be used to cut the thermoplastic
sheet. Suitable methods include, but are not limited to,
die-cutting, knifes, blades and saws.
[0083] In an embodiment of the invention, the thermoplastic sheets
can be cut into individual cards, embossed with a name, account
number or other desired information. The raised surfaces of the
embossed information can be tipped with ink if desired.
[0084] Optionally, the item can be laminated, where the lamination
includes adding physical indicia selected from magnetic strips,
code bars, pictures, microchips, images, and combinations thereof
to the item.
[0085] Thus, the present invention provides an item made according
to the above-described method. The item can be any desired shape,
depending on its desired use. The shape of the item can be, without
limitation, rectangular, square, circular, oval, round, triangular,
trapezoidal, a parallelogram, pentagonal, hexagonal, octagonal and
any combination of such shapes.
[0086] In an embodiment of the invention, the item is rectangular,
can be used as a card, and can have a first dimensional length of
from about 2 cm to about 15 cm, a second dimension of from about 1
cm to about 12 cm, and a thickness of from about 0.05 mm to about 5
mm.
[0087] The physical indicia on the item can include, but is not
limited to, magnetic strips, code bars, pictures, microchips,
images, and combinations thereof that are affixed to the item. The
physical indicia can be applied to the thermoplastic sheet before
it is cut or to the item after the sheet is cut.
[0088] When the item is embossed, the item is formed so that a
portion of the thermoplastic composition is raised above a plane of
the item. The raised portion can be in the form of characters,
numbers and/or letters.
[0089] The thermoplastic sheets, items and cards of the present
invention readily receive ink and other printing, which generally
does not smear after it has been applied and allowed to dry and/or
cure. The thermoplastic sheets, items and cards provide sufficient
stiffness, impact strength, resilience, flexural durability
properties and ink printability and ink acceptability properties,
are typically low cost and thus are suitable for use in disposable
or limited use applications. Although surface treatment and/or
lamination layers can be used, they are generally not required to
protect the printed image.
[0090] The present invention will further be described by reference
to the following examples. The following examples are merely
illustrative of the invention and are not intended to be limiting.
Unless otherwise indicated, all percentages are by weight.
EXAMPLES
[0091] The test methods used to evaluate the thermoplastic sheets
were: [0092] Graves Tear--ASTM D-1004 [0093] Trousers Tear--ASTM
D-1938 [0094] Tensile Test--ASTM D-638 [0095] Flexural
modulus--ASTM D-790 [0096] Impact (Instrumented Impact)--ASTM
D-3763 [0097] Haze of a sheet sample was measured using a
ColorQuest.RTM. XE-Touch reflectance/transmittance
spectrophotometer equipped with Universal Software.RTM. color
quality control software, available from Hunter Associates
Laboratory, Inc., Reston, Va.
Example 1
Comparative
[0098] A high impact polystyrene composition was prepared by
polymerizing a mixture containing 92 wt. % styrene and 8%
polybutadiene rubber using tert butyl peroxyacetate as initiator
and extruding the polymer to form a sheet 20 mils thick.
Example 2
Comparative
[0099] A high impact polystyrene composition was prepared by
polymerizing a mixture containing 90.75 wt. % polystyrene and 9.25%
polybutadiene rubber using tert butyl peroxyacetate as initiator
and extruding the polymer to form a sheet 20 mils thick.
Example 3
Invention
[0100] A thermoplastic composition of the present invention was
prepared by polymerizing 47 wt. % styrene, 33.5 wt. % methyl
methacrylate and 5 wt. % butyl acrylate in the presence of 14.5 wt.
% styrene-butadiene block copolymer with an average styrene content
of 39.75 wt. % using tert butyl peroxyacetate as initiator. The
resulting product was clear. The thermoplastic composition was then
extruded to form a sheet 20 mils thick.
[0101] Results for Examples 1-3 are shown in Table 1:
TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Tensile Stress
@ Yield, KSI (MD) 3.5 3.9 6.6 Tensile Strain @ Break, % (MD) 106.4
92.7 94.8 Tensile Stress @ Yield, KSI (TD) 3.0 3.7 6.6 Tensile
Strain @ Break, % (TD) 100.7 87.7 62.8 Flexural - Max Load, lb.
(MD) 5.8 6.3 9.9 Flexural - Max Load, lb. (TD) 6.6 6.9 10.4
Instrumented Impact Resistance - 169.2 164.3 168.8 Maximum Load,
lb. Instrumented Impact Resistance - 4.0 4.0 3.2 Total Energy,
ft-lb. Graves Tear, lb. (parallel to MD) 18.5 18.2 28.6 Graves
Tear, lb. (perpendicular to 16.9 17.3 27.2 MD) Trousers Tear, lb.
(MD) 0.8 0.9 1.9 Trousers Tear, lb. (TD) 1.2 2.1 1.9
[0102] MD denotes the machine direction of the sheet. TD denotes
the transverse direction of the sheet. The thermoplastic sheets
made with the rubber modified styrene acrylic copolymer (Example 3)
were stiffer than the comparative samples (Examples 1 and 2) as
shown by tensile stress at yield and flexural strength. Similar
impact resistance (or toughness) was shown by the Instrumented
Impact Resistance, and significantly better tear resistance was
shown by the Graves Tear and Trousers Tear results.
Example 4
Invention
[0103] A sample was prepared as in Example 3, except that 5%
titanium dioxide, as a pigment, was included in the thermoplastic
composition. This material was extruded to form an opaque sheet
measuring 24 mils thick.
[0104] Printing was applied to the thermoplastic sheets of Example
4 and evaluated according to ASTM D 3359-02 (method B). No printing
was removed after ten repetitions of tape adhesion and removal.
Additionally, rubbing the printed area with a finger did not smudge
or smear the printed image.
Examples 5
Comparative
[0105] Example 5 is a commercially available vinyl chloride-vinyl
acetate copolymer (Oxy 1710, Occidental Petroleum Corp., Los
Angeles, Calif.) extruded to 26 mils thick.
[0106] The Fatigue Test was an assessment of the flexural fatigue
properties of extruded sheets. It was conducted using a
servo-hydraulic load frame. The intent was to simulate the
incomplete or obstructed insertion of a keycard into a reader.
Specimens were cut one inch in width, with one end clamped to a
reciprocating hydraulic actuator while the other was fed into a
stationary blind slot. The actuator was cycled over a 0.75-inch
stroke, with 3.75 inch of unsupported sheet. The resultant
deflection at mid span of the sheet was 0.75 inches. This flexing
action was repeated at 120 cycles per minute until the sheet
failed. Comparative results for the thermoplastic sheets in
Examples 3-5 are summarized in Table 2, where the Graves Tear
results are normalized to 20 mils. TABLE-US-00002 TABLE 2 Example 5
Example 4 Example 3 Fatigue Test, 7000 30000 Not Tested Cycles to
Failure Graves Tear 35.5 22.7 28.6 (parallel to MD), lb. Graves
Tear 33.5 20.1 27.2 (perpendicular to MD), lb.
[0107] The results show that the thermoplastic sheets according to
the invention provide adequate unilateral tear results and
surprisingly good Fatigue Test (flex resistance) results while
being able to be used as a one layer (no lamination) printed
card.
[0108] The present invention has been described with reference to
specific details of particular embodiments thereof. It is not
intended that such details be regarded as limitations upon the
scope of the invention except insofar as and to the extent that
they are included in the accompanying claims.
* * * * *