U.S. patent application number 10/036743 was filed with the patent office on 2003-06-26 for elastomeric articles having improved chemical resistance.
This patent application is currently assigned to Kimberly-Clark Worldwide, Inc.. Invention is credited to Kister, Mary E., Littleton, Kermit R., Triebes, Thomas G..
Application Number | 20030118761 10/036743 |
Document ID | / |
Family ID | 21890381 |
Filed Date | 2003-06-26 |
United States Patent
Application |
20030118761 |
Kind Code |
A1 |
Triebes, Thomas G. ; et
al. |
June 26, 2003 |
Elastomeric articles having improved chemical resistance
Abstract
An elastomeric article (e.g., glove, condom, etc.) that includes
a chemical protection layer that will not substantially dissolve
when applied with certain chemicals or solvents, such as methyl
methyacrylate, is provided. The chemical protection layer contains
at least one crosslinked, modified silicone elastomer. For example,
in one embodiment, the modified silicone chemical protection layer
covers the outer surface of a styrene-ethylene-butylene-styrene
(S-EB-S) block copolymer substrate body to impart relative chemical
resistance to the resulting elastomeric article.
Inventors: |
Triebes, Thomas G.;
(Alpharetta, GA) ; Kister, Mary E.; (Cumming,
GA) ; Littleton, Kermit R.; (Ellijay, GA) |
Correspondence
Address: |
DORITY & MANNING, P.A.
POST OFFICE BOX 1449
GREENVILLE
SC
29602-1449
US
|
Assignee: |
Kimberly-Clark Worldwide,
Inc.
|
Family ID: |
21890381 |
Appl. No.: |
10/036743 |
Filed: |
December 21, 2001 |
Current U.S.
Class: |
428/35.7 ;
427/387; 427/430.1 |
Current CPC
Class: |
C08J 2321/00 20130101;
Y10T 428/1352 20150115; C08J 7/0427 20200101; A61L 31/048 20130101;
A41D 19/0058 20130101; Y10T 428/31551 20150401; Y10T 428/31569
20150401; C08G 18/0823 20130101; A61L 31/14 20130101; Y10T
428/31663 20150401; Y10T 428/1386 20150115; A61L 31/10 20130101;
C08J 2483/00 20130101; Y10T 428/31598 20150401; C08J 7/043
20200101; A61L 31/048 20130101; C08L 53/02 20130101; A61L 31/10
20130101; C08L 75/04 20130101; A61L 31/10 20130101; C08L 83/04
20130101 |
Class at
Publication: |
428/35.7 ;
427/387; 427/430.1 |
International
Class: |
B32B 001/02; B05D
001/18; B05D 003/02 |
Claims
What is claimed is:
1. An elastomeric article that comprises: a substrate body
including a layer made of an elastomeric material, said substrate
body having an inside surface and an outside surface; and a
chemical protection layer covering said outside surface of said
substrate body, said chemical protection layer including at least
one modified silicone elastomer that has been crosslinked.
2. An elastomeric article as defined in claim 1, wherein said
modified silicone elastomer is selected from the group consisting
of phenyl-modified silicones, vinyl-modified silicones,
methyl-modified silicones, fluoro-modified silicones,
alkyl-modified silicones, alkoxy-modified silicones,
alkylamino-modified silicones, and combinations thereof.
3. An elastomeric article as defined in claim 2, wherein said
modified silicone elastomer is selected from the group consisting
of phenyl-modified silicones, vinyl-modified silicones,
methyl-modified silicones, fluoro-modified silicones.
4. An elastomeric article as defined in claim 3, wherein said
modified silicone elastomer contains a diphenyl modified
dimethylsilicone.
5. An elastomeric article as defined in claim 1, wherein said
chemical protection layer has a thickness of from about 0.01
millimeters to about 0.30 millimeters.
6. An elastomeric article as defined in claim 1, wherein said
chemical protection layer has a thickness of from about 0.01
millimeters to about 0.20 millimeters.
7. An elastomeric article as defined in claim 1, wherein said
chemical protection layer defines an outer surface of the
elastomeric article.
8. An elastomeric article as defined in claim 1, wherein the
elastomeric material of said substrate body is selected from the
group consisting of styrene-ethylene-butylene-styrene block
copolymers, styrene-isoprene-styrene block copolymers,
styrene-polybutadiene-styrene block copolymers, styrene-isoprene
block copolymers, styrene-butadiene block copolymers, natural
rubber latex, nitrile rubbers, isoprene rubbers, chloroprene
rubbers, polyvinyl chlorides, silicone rubbers, and combinations
thereof.
9. An elastomeric article as defined in claim 8, wherein the
elastomeric material of said substrate body contains at least one
styrene-ethylene-butylene-styrene triblock copolymer.
10. An elastomeric article as defined in claim 1, further
comprising a donning layer overlying the inside surface of said
substrate body.
11. An elastomeric article as defined in claim 10, wherein said
donning layer contains syndiotactic 1,2 polybutadiene.
12. An elastomeric article as defined in claim 10, further
comprising a lubricant layer overlying the inside surface of said
donning layer.
13. An elastomeric article as defined in claim 1, wherein the
article is a glove.
14. An elastomeric glove that comprises: a substrate body including
a layer made of an elastomeric material, said elastomeric material
including at least one styrene-ethylene-butylene-styrene triblock
copolymer, wherein said substrate body has an inside surface and an
outside surface; and a chemical protection layer covering said
outside surface of said substrate body, said chemical protection
layer including at least one modified silicone elastomer that has
been crosslinked, wherein said modified silicone elastomer is
selected from the group consisting of phenyl-modified silicones,
vinyl-modified silicones, methyl-modified silicones,
fluoro-modified silicones, alkyl-modified silicones,
alkoxy-modified silicones, alkylamino-modified silicones, and
combinations thereof.
15. An elastomeric glove as defined in claim 14, wherein said
modified silicone elastomer is selected from the group consisting
of phenyl-modified silicones, vinyl-modified silicones,
methyl-modified silicones, fluoro-modified silicones.
16. An elastomeric glove as defined in claim 14, wherein said
chemical protection layer has a thickness of from about 0.01
millimeters to about 0.30 millimeters.
17. An elastomeric glove as defined in claim 14, wherein said
chemical protection layer has a thickness of from about 0.01
millimeters to about 0.20 millimeters.
18. An elastomeric glove as defined in claim 14, wherein said
chemical protection layer defines an outer surface of the
glove.
19. An elastomeric glove as defined in claim 14, further comprising
a donning layer overlying the inside surface of said substrate
body.
20. An elastomeric glove as defined in claim 19, further comprising
a lubricant layer overlying the inside surface of said donning
layer.
21. A method for forming an elastomeric article, said method
comprising: furnishing a liquid solution comprising a modified
silicone elastomer and a solvent; dipping a former having the shape
of the elastomeric article into said liquid solution and
withdrawing the former from said liquid solution; evaporating the
solvent from the liquid solution present on the former so that a
modified silicone elastomer film is formed thereon; and heating the
modified silicone elastomer to induce crosslinking.
22. A method as defined in claim 21, wherein the modified silicone
elastomer is crosslinked at a temperature of from about 200.degree.
F. to about 400.degree. F.
23. A method as defined in claim 21, wherein the modified silicone
elastomer is crosslinked at a temperature of from about 200.degree.
F. to about 350.degree. F.
24. A method as defined in claim 21, wherein said modified silicone
elastomer is selected from the group consisting of phenyl-modified
silicones, vinyl-modified silicones, methyl-modified silicones,
fluoro-modified silicones, alkyl-modified silicones,
alkoxy-modified silicones, alkylamino-modified silicones, and
combinations thereof.
25. A method as defined in claim 24, wherein said modified silicone
elastomer contains a diphenyl modified dimethylsilicone.
26. A method as defined in claim 21, wherein said uncrosslinked
modified silicone elastomer has a solids content of from about 5%
to about 40%.
27. A method as defined in claim 21, wherein said uncrosslinked
modified silicone elastomer has a solids content of from about 10%
to about 35%.
28. A method as defined in claim 21, wherein said uncrosslinked
modified silicone elastomer has a viscosity of from about 300
centipoise to about 7000 centipoise.
29. A method as defined in claim 21, wherein said uncrosslinked
modified silicone elastomer has a viscosity of from about 600
centipoise to about 4000 centipoise.
30. A method as defined in claim 21, wherein said modified silicone
elastomer film has a thickness of from about 0.01 millimeters to
about 0.30 millimeters.
31. A method as defined in claim 21, wherein said modified silicone
elastomer film has a thickness of from about 0.01 millimeters to
about 0.20 millimeters.
32. A method as defined in claim 21, further comprising dipping
said crosslinked, modified silicone-coated former into a liquid
solution of an elastomeric material to form the substrate body.
33. A method as defined in claim 32, wherein said elastomeric
material of said substrate body contains at least one
styrene-ethylene-butylene-styre- ne triblock copolymer.
34. A method as defined in claim 32, further comprising dipping
said former into a liquid solution to apply a donning layer on a
surface of said substrate body.
35. A method as defined in claim 21, wherein the elastomeric
article is a glove.
Description
BACKGROUND OF THE INVENTION
[0001] Elastomeric articles, such as gloves, are often formed from
synthetic polymers. Unfortunately, one problem sometimes associated
with the formation of elastomeric articles from some types of
synthetic polymers is that they tend to dissolve when contacted
with certain chemicals or solvents. The dissolution of the
elastomeric polymer may be especially problematic when used in
certain fields, such as in the medical or automotive field. For
example, a surgeon often wears elastomeric gloves during a
procedure to protect the patient and surgeon from the possible
spread of infection or disease. During the procedure, the surgeon
may be required to utilize various chemicals or solvents, such as
bone cement, that may undesirably dissolve the elastomeric polymer
forming the glove, thereby exposing the surgeon's skin.
[0002] As such, a need currently exists for an improved elastomeric
article that is relatively resistant to various types of chemicals
or solvents.
SUMMARY OF THE INVENTION
[0003] In accordance with one embodiment of the present invention,
an elastomeric article (e.g., glove, condom, etc.) is disclosed
that comprises a substrate body including a layer made of an
elastomeric material and a chemical protection layer covering the
outside surface of the substrate body. The chemical protection
layer includes at least one modified silicone elastomer that has
been crosslinked. For example, in one embodiment, the modified
silicone elastomer is selected from the group consisting of
phenyl-modified silicones, vinyl-modified silicones,
methyl-modified silicones, fluoro-modified silicones,
alkyl-modified silicones, alkoxy-modified silicones,
alkylamino-modified silicones, and combinations thereof.
[0004] The substrate body, as indicated above, contains an
elastomeric material. In some instances, the elastomeric material
of the substrate body is selected from the group consisting of
styrene-ethylene-butylene-s- tyrene block copolymers,
styrene-isoprene-styrene block copolymers,
styrene-polybutadiene-styrene block copolymers, styrene-isoprene
block copolymers, styrene-butadiene block copolymers, natural
rubber latex, nitrile rubbers, isoprene rubbers, chloroprene
rubbers, polyvinyl chlorides, silicone rubbers, and combinations
thereof. For example, in one embodiment, the elastomeric material
of the substrate body contains at least one
styrene-ethylene-butylene-styrene triblock copolymer.
[0005] Besides the layers mentioned above, the elastomeric article
may also contains other layers. In one embodiment, for instance,
the elastomeric article can contain a donning layer overlying the
inside surface of the substrate body. If desired, a lubricant layer
may also overlay the inside surface of the donning layer.
[0006] In accordance with another embodiment of the present
invention, a method for forming an elastomeric article (e.g.,
glove, condom, etc.) is disclosed. In particular, the method
includes furnishing a liquid solution comprising a modified
silicone elastomer and a solvent. A former having the shape of the
elastomeric article is dipped into the liquid solution and
withdrawn therefrom. The solvent is then evaporated from the liquid
solution present on the former so that a modified silicone
elastomer film is formed thereon. To induce crosslinking in the
modified silicone elastomer, it is heated, such as to a temperature
of from about 200.degree. F. to about 400.degree. F., and in some
embodiments, from about 200.degree. F. to about 350.degree. F.
[0007] Various properties of the chemical protection layer may be
varied to achieve an elastomeric article having certain
characteristics. For example, the solids content of the
uncrosslinked modified silicone elastomer can be from about 5% to
about 40%, and in some embodiments, from about 10% to about 35%.
Furthermore, the uncrosslinked modified silicone elastomer can have
a viscosity of from about 300 centipoise to about 7000 centipoise,
and in some embodiments, from about 600 centipoise to about 4000
centipoise. Moreover, the modified silicone elastomer film can have
a thickness of from about 0.001 millimeters to about 0.4
millimeters, in some embodiments, from about 0.01 millimeters to
about 0.30 millimeters, and in some embodiments, from about 0.01
millimeters to about 0.20 millimeters.
[0008] The method can also include dipping the crosslinked,
modified silicone-coated former into a liquid solution of an
elastomeric material (e.g., styrene-ethylene-butylene-styrene) to
form the substrate body. In some embodiments, the former is further
dipped into a liquid solution to apply a donning layer on the
inside surface of the substrate body.
[0009] Other features and aspects of the present invention are
discussed in greater detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] A full and enabling disclosure of the present invention,
including the best mode thereof, directed to one of ordinary skill
in the art, is set forth in the specification, which makes
reference to the appended drawings, in which:
[0011] FIG. 1 is a perspective view of one embodiment of an
elastomeric glove made according to the invention;
[0012] FIG. 2 is a cross-sectional view of the glove illustrated in
FIG. 1 taken along a line 2-2; and
[0013] FIG. 3 is a block flow diagram illustrating one embodiment
of a method for forming an elastomeric article of the present
invention.
[0014] Repeat use of reference characters in the present
specification and drawings is intended to represent the same or
analogous features or elements of the invention.
DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS
[0015] Reference now will be made in detail to various embodiments
of the invention, one or more examples of which are set forth
below. Each example is provided by way of explanation, not
limitation of the invention. In fact, it will be apparent to those
skilled in the art that various modifications and variations can be
made in the present invention without departing from the scope or
spirit of the invention. For instance, features illustrated or
described as part of one embodiment, can be used on another
embodiment to yield a still further embodiment. Thus, it is
intended that the present invention cover such modifications and
variations.
[0016] In general, the present invention is directed to an
elastomeric article that includes a chemical protection layer that
will not substantially dissolve when contacted with certain
chemicals or solvents, such as bone cement. The chemical protection
layer contains at least one crosslinked, modified silicone
elastomer. For example, in one embodiment, the modified silicone
chemical protection layer covers the outer surface of a
styrene-ethylene-butylene-styrene (S-EB-S) block copolymer
substrate body to impart relative chemical resistance to the
resulting elastomeric article.
[0017] Any of a variety of elastomeric articles can be provided
with improved chemical resistance properties in accordance with the
present invention. For example, gloves and condoms, as well as
medical devices, such as dilatation balloons, inflatable cuffs,
external catheters, catheter balloons, instrument covers, and the
like, can be formed according to the present invention. In
addition, it should also be understood that other types of
elastomeric articles may also be formed according to the present
invention. For example, elastomeric materials often used in
automotive applications, such as flexible rubber hoses, can also be
formed with the crosslinked modified silicone elastomer in
accordance with the present invention.
[0018] Referring to FIGS. 1-2, for example, one embodiment of an
elastomeric glove 20 is illustrated that can be placed on the hand
of a user 22. The glove 20 includes a substrate body 24 having the
basic shape of the glove. The substrate body 24 can generally be
formed from any of a variety of natural and/or synthetic
elastomeric materials known in the art. For instance, some examples
of suitable elastomeric materials include, but are not limited to,
S-EB-S (styrene-ethylene-butylene-styren- e) block copolymers,
S-I-S (styrene-isoprene-styrene) block copolymers, S-B-S
(styrene-butadiene-styrene) block copolymers, S-I
(styrene-isoprene) block copolymers, S-B (styrene-butadiene) block
copolymers, natural rubber latex, nitrile rubbers, isoprene
rubbers, chloroprene rubbers, polyvinyl chlorides, silicone
rubbers, and combinations thereof. Other suitable elastomeric
materials that can be used to form the substrate body 24 may be
described in U.S. Pat. No. 6,306,514 to Weikel, et al., which is
incorporated herein in its entirety by reference thereto for all
purposes.
[0019] In one particular embodiment, the substrate body 24 contains
at least one elastomeric block copolymer. Some S-EB-S block
copolymers and methods for forming solutions thereof are described
in U.S. Pat. Nos. 5,112,900 to Buddenhagen, et al.; 5,407,715 to
Buddenhagen, et al.; 5,900,452 to Plamthottam; and 6,288,159 to
Plamthottam, which are incorporated herein in their entirety by
reference thereto for all purposes.
[0020] The polystyrene end blocks of S-EB-S block copolymers
utilized in the present invention typically have a weight average
molecular weight of at least about 15,000 Daltons, and in some
embodiments, from about 18,000 to about 20,000 Daltons. Moreover,
the polystyrene end blocks of the block copolymers typically
constitute from about 25% to about 35% by weight of the total
weight of the S-EB-S polymer, which is generally from about 50,000
to about 300,000 Daltons. When utilizing such a weight average
molecular weight of the polystyrene end blocks, the resulting
elastomeric films can exhibit superior strength properties and have
limited crack formation during drying and fusion.
[0021] If desired, mixtures of two or more S-EB-S copolymers may be
utilized. In some instances, for example, two S-EB-S copolymers are
utilized in which each block copolymer constitutes from about 40%
to about 60% by weight of the mixture. In one embodiment, the first
S-EB-S block copolymer has a solution viscosity of about 6500 cps
at 25% by weight of copolymer in toluene (at 77.degree. F.) and the
second S-EB-S block copolymer has a solution viscosity of about
2000 cps at 10% by weight of copolymer in toluene (at 77.degree.
F.).
[0022] The use of S-EB-S block copolymer(s) in the substrate body
24 can generally provide a number of benefits. For example,
elastomers based upon the S-EB-S block elastomeric block copolymers
are substantially resistant to attack by ozone or by other
oxidative conditions. Moreover, the mechanical properties of the
S-EB-S block copolymers may be selected to provide the desirable
combination of tensile strength, elasticity, and tactility utilized
in some applications. The structure, properties, and some
applications of some S-EB-S elastomers are disclosed in U.S. Pat.
Nos. 3,485,787; 3,830,767; 4,006,116; 4,039,629; 4,041,103;
4,386,179; 4,481,323; 4,511,354; and 4,613,640, which are
incorporated herein in their entirety by reference thereto for all
purposes.
[0023] Some commercially available examples of S-EB-S block
copolymers, such as described above, include, but are not limited
to, Kraton.RTM. G1650, Kraton.RTM. G1651, Kraton.RTM. G1652, which
are available from Kraton Polymers of Houston, Tex. Kraton.RTM.
G1650 is an S-EB-S block copolymer having a styrene/central block
ratio of 28/72 and a Brookfield Viscosity in toluene solution (20%
concentration by weight) at 77.degree. F. of 1500 centipoise.
Kraton.RTM. G1651 is an S-EB-S block copolymer having a
styrene/central block ratio of 33/67 and a Brookfield Viscosity in
toluene solution (20% concentration by weight) at 77.degree. F. of
2000 centipoise. Kraton.RTM. G1652 is an S-EB-S block copolymer
having a styrene/central block ratio of 29/71 and a Brookfield
Viscosity in toluene solution (20% concentration by weight) at
77.degree. F. of 550 centipoise.
[0024] The S-EB-S block copolymer(s) may optionally have end-block
compatible resins added to the polystyrene end blocks. The added
end-block compatible resin increases the glass transition
temperature (T.sub.g) of the S-EB-S block copolymer. The increased
T.sub.g allows the final products to be used at higher
temperatures. For instance, one suitable example of such an
end-block compatible resin is poly alpha methyl styrene.
[0025] A plasticizer (e.g., an oil) can also be mixed with the
S-EB-S block copolymer(s) to enhance the resulting properties of
the elastomeric article. For example, in one embodiment, the
plasticizer can include a mineral oil, such as a refined petroleum
paraffinic hydrocarbon oil, which is described in Entries 6971 and
6972 of the Merck Index, Eighth Edition. The plasticizer can
generally be mixed with the S-EB-S block copolymers in any desired
amount. For example, in some embodiments, the plasticizer comprises
between about 30 to about 80 parts by weight of the total mass of
the S-EB-S block copolymer(s).
[0026] Besides containing a plasticizer, the S-EB-S block
copolymer(s) can also be mixed with a solvent. In particular,
S-EB-S block copolymers are often provided as a solid. In such
instances, a solvent can be utilized to enhance the ability of the
copolymers to be used in a dipping process, as described in more
detail below. Any solvent capable of dissolving one or more S-EB-S
block copolymers can generally be used in the present invention.
For example, some suitable solvents that can be used include
toluene and cyclohexane. Once mixed with the copolymer(s), the
ingredients can be mixed for a sufficient time to reach a
homogeneous solution and then filtered to remove any undesired
particulate matter.
[0027] Regardless of the particular material used to form the
substrate body 24 the glove 20 also includes a chemical protection
layer 36 that covers the outer surface of the substrate body 24
during use. Thus, for example, the chemical protection layer 36 can
form an environment-exposed surface 21 of the glove, or can be
positioned between the substrate body 24 and an additional layer
that forms the environment-exposed surface 21. The chemical
protection layer 36 contains a modified silicone elastomer that is
crosslinked to impart chemical resistance to the glove 20. As used
herein, the term "modified silicone" generally refers to a broad
family of synthetic polymers that have a repeating silicon-oxygen
backbone with organic groups attached to the backbone (pendant
and/or terminating). For instance, some suitable silicones that can
be used in the present invention include, but are not limited to,
phenyl-modified silicones, vinyl-modified silicones,
methyl-modified silicones, fluoro-modified silicones,
alkyl-modified silicones, alkoxy-modified silicones,
alkylamino-modified silicones, and combinations thereof.
[0028] Some suitable phenyl-modified silicones include, but are not
limited to, dimethyldiphenylpolysiloxane copolymers; dimethyl,
methylphenylpolysiloxane copolymers; polymethylphenylsiloxane; and
methylphenyl, dimethylsiloxane copolymers. Phenyl modified
silicones that have a relatively low phenyl content (less than
about 50 mole %) may be particularly effective in the present
invention. For example, the phenyl-modified silicone can be a
diphenyl-modified silicone, such as a diphenylsiloxane-modified
dimethylpolysiloxane.
[0029] For most applications, the phenyl-modified silicones contain
phenyl units in an amount from about 0.5 mole % to about 50 mole %,
in some embodiments in an amount less than about 25 mole %, and in
some embodiments, in an amount less than about 15 mole %. In one
particular embodiment, a diphenylsiloxane-modified
dimethylpolysiloxane can be used that contains diphenylsiloxane
units in an amount less than about 5 mole %, and particularly in an
amount less than about 2 mole %. The diphenylsiloxane-modified
dimethylpolysiloxane can be synthesized by reacting
diphenylsiloxane with dimethylsiloxane.
[0030] As indicated above, fluoro-modified silicones can also be
used in the present invention. For instance, one suitable
fluoro-modified silicone that can be used is a trifluoropropyl
modified polysiloxane, such as a trifluoropropylsiloxane modified
dimethylpolysiloxane. A trifluoropropylsiloxane modified
dimethylpolysiloxane can be synthesized by reacting methyl, 3,3,3
trifluoropropylsiloxane with dimethylsiloxane. The fluoro-modified
silicones can contain from about 5 mole % to about 95 mole %, and
in some embodiments, from about 40 mole % to about 60 mole % of
fluoro groups, such as trifluoropropylsiloxane units. In one
embodiment, a trifluoropropylsiloxane-modified dimethylpolysiloxane
is used that contains 50 mole % trifluoropropylsiloxane units.
[0031] Besides the above-mentioned modified silicone elastomers,
other modified silicone elastomers may also be utilized in the
present invention. For instance, some suitable vinyl-modified
silicones include, but are not limited to, vinyldimethyl terminated
polydimethylsiloxanes; vinylmethyl, dimethylpolysiloxane
copolymers; vinyldimethyl terminated vinylmethyl,
dimethylpolysiloxane copolymers; divinylmethyl terminated
polydimethylsiloxanes; polydimethylsiloxane, mono vinyl, mono
n-butyldimethyl terminated; and vinylphenylmethyl terminated
polydimethylsiloxanes. Further, some methyl-modified silicones that
can be used include, but are not limited to, dimethylhydro
terminated polydimethylsiloxanes; methylhydro, dimethylpolysiloxane
copolymers; methylhydro terminated methyloctyl siloxane copolymers;
and methylhydro, phenylmethyl siloxane copolymers.
[0032] The particular elastomers described above are meant to
include hetero- or co-polymers formed from polymerization or
copolymerization of dimethylsiloxane cyclics and diphenylsiloxane
cyclics or trifluoropropylsiloxane cyclics with appropriate
endcapping units. Thus, for example, the terms "diphenyl modified
dimethylpolysiloxanes" and "copoloymers of diphenylpolysiloxane and
dimethylpolysiloxane" may be used interchangeably.
[0033] If desired, the chemical protection layer 36 can be formed
from two or more separate components. When utilized, the separate
components may contain the same or different types of modified
silicone elastomers. For example, in one embodiment, the chemical
protection layer 36 contains two components, designated herein as
part "A" and "B". In one embodiment, part A contains a
polydimethylsiloxane that is vinyl and methyl terminated. A
platinum catalyst is also included that contains a complex of
platinum with vinyl-containing oligosiloxanes (complex of platinum
and divinyltetramethyldisiloxane with typical levels of active
platinum of 5 to 50 parts per million). Part B is essentially
identical to part A, except that it also includes a crosslinker and
crosslinking inhibitor. The crosslinker can be, for example,
polydimethylsiloxane with hydrogen on the siloxane chain, commonly
called methyl hydrogen. The crosslinker concentration can vary from
about 0.3 to about 4 parts per hundred parts of the mass of
polydimethylsiloxane. The crosslinking inhibitor can, for example,
contain an oligosiloxane with high concentration of
vinyl-containing substituents of any of the class of compounds
known as acetylinic alcohols. For example, one suitable
crosslinking inhibitor is tetravinyl tetramethyl
cyclotetrasiloxane. The inhibitor may be used in concentrations as
low as 0.02 parts per hundred parts to as high as 0.5 parts per
hundred parts. In forming the outer layer 36, parts A and B are
mixed together prior to dipping in a 1:1 ratio by weight.
[0034] Some commercially available diphenyl modified
dimethylsilicones, such as described above, can be obtained from
NuSil Technologies under various trade names including MED 6400,
MED 10-6400, MED 6600, MED 10-6600, MED 6640, and MED 10-6640. For
example, the following Table provides some physical properties for
MED 6400, MED 6600, and MED 6640.
1 MED 6400* MED 6600* MED 6640* Viscosity, cP 600 300 7000 Solvent
Xylene Xylene Xylene Solids Content 35 35 25 Cure System
Platinum-based Platinum-based Platinum-based *MED 6400, 6600, and
6640 contain the same viscosity, solvent, solids content, and cure
system as MED 10-6400, 10-6600, and 10-6640, respectively.
[0035] Other suitable modified silicone elastomers that can be used
in the present invention are believed to be described in U.S. Pat.
Nos. 4,309,557 to Compton, et al.; 6,136,039 to Kristonsson, et
al.; 6,160,151 to Compton, et al.; 6,243,938 to Lubrecht; and WO
01/41700, which are incorporated herein in their entirety by
reference thereto for all purposes. Moreover, the modified silicone
elastomers used in the present invention may also contain fillers,
such as reinforcing silica; processing aids; additives; pigments;
and the like, as is conventional in the art.
[0036] The solids content and/or viscosity of the chemical
protection layer 36 can generally be varied to achieve the desired
chemical resistance. For example, the modified silicone
elastomer(s) used to form the chemical protection layer 36 can have
a solids content of between about 5% to about 40%, and in some
embodiments, between about 10% to about 35%. To lower the solids
content of a commercially available modified silicone elastomer,
for example, additional amounts of solvent can be utilized.
Further, the viscosity of the modified silicone elastomer(s) used
to form the chemical protection layer 36 can range from about 300
centipoise to about 7000 centipoise, and in some embodiments, from
about 600 to about 4000 centipoise. By varying the solids content
and/or viscosity of the chemical protection layer 36, the presence
of the modified silicone elastomer in the glove can be controlled.
For example, to form a glove with a higher level of chemical
resistance, the modified silicone elastomer used in such layer can
have a relatively high solids content and viscosity so that a
greater percentage of the silicone is incorporated into the layer
during the forming process. The thickness of the chemical
protection layer 36 can also vary. For example, the thickness can
range from about 0.001 millimeters to about 0.4 millimeters, in
some embodiments, from about 0.01 millimeters to about 0.30
millimeters, and in some embodiments, from about 0.01 millimeters
to about 0.20 millimeters.
[0037] Besides the chemical protection layer 36 and the substrate
body 24 the glove 20 can also contain other layers. For example, as
shown in FIG. 2, the glove 20 can contain a coating 26 that
contacts the body of the user 22 during use. In this embodiment,
the coating 26 includes a donning layer 30 overlying and contacting
the substrate body 24 and a surfactant layer 32 overlying and
contacting the donning layer 30.
[0038] The donning layer 30 can contain any of a variety of
different elastomeric polymers that are capable of facilitating
donning of the glove. Some examples of suitable materials for the
donning layer 30 include, but are not limited to, polybutadienes
(e.g., syndiotactic 1,2 polybutadiene), polyurethanes, halogenated
copolymers, and the like. For instance, in one embodiment, an
unsaturated styrene-isoprene (SIS) having tri- or radial-blocks can
be utilized. In some embodiments, the SIS block copolymer has a
polystyrene end block content of from about 10% to about 20% by
weight, and particularly from about 15% to about 18% by weight, of
the total weight of the SIS block copolymer. Moreover, the
molecular weight of the polystyrene end blocks is typically at
least about 5,000 grams per mole. Some examples of suitable
mid-block unsaturated SIS block copolymers include, but are not
limited to, Kraton.RTM. D1107 available from Kraton Polymers and
Vector.RTM. 511 and Vector.RTM. 4111 available from Dexco Polymers
of Houston, Tex.
[0039] Another suitable donning material is 1,2 polybutadiene
(e.g., syndiotactic 1,2 polybutadiene). In one embodiment, for
example, the donning layer 30 is formed from a solution that
contains from about 2% to about 7% by weight, and particularly from
about 3% to about 4% by weight of 1,2 polybutadiene in a solvent
(e.g., toluene). For instance, one suitable example of a
polybutadiene material that can be dissolved in toluene to form a
coating solution is "COMPATIBAG", which is available from Presto
Products of Appleton, Wis. and contains syndiotactic 1,2
polybutadiene. The 1,2 polybutadiene can also be formed as an
emulsion to be applied as the donning layer 30. In some
embodiments, for example, the emulsion contains from about 5% to
about 14% by weight, and particularly about 9% by weight of 1,2
polybutadiene in a surfactant mixture. In one embodiment, the
surfactant mixture is sodium dioctyl sulfosuccinate in an amount
from about 10 phr (parts per hundred rubber) to about 100 phr, and
particularly 40 phr in water. Pre-dispersion can be achieved by
dispersing the surfactant mixture and 1,2 polybutadiene solution
using a mixer, such as a high shear mixture. In one embodiment, the
pre-dispersion is then mixed for about 5 minutes in a rotor/stator
(such as a Ross X Series) mixer to generate an average particle
size of less than about 1 micrometer. The resulting emulsion can
then be filtered and the solvent can be removed by vacuum
distillation.
[0040] In addition, polyurethanes may also be utilized as a donning
material. For example, in one embodiment, Hyslip 20022 (available
from Noveon, Inc.) can be utilized. Hyslip 20022 contains
1-methyl-2-pyrrolidone and waterborne polyurethane. Other examples
of donning materials that can be utilized in the donning layer 30
may be described in U.S. Pat. No. 5,792,531 to Littleton, et al.,
which is incorporated herein in its entirety by reference thereto
for all purposes.
[0041] A lubricant layer 32 can also overly the donning layer 30 to
aid in donning the article when the user's body is either wet or
dry. The lubricant layer 32, for example, can include a cationic
(e.g., cetyl pyridinium chloride), an anionic (e.g., sodium lauryl
sulfate), or a nonionic surfactant. For instance, in one
embodiment, the lubricant layer 32 contains a quaternary ammonium
compound, such as Verisoft BTMS (available from Goldschmidt
Chemical Corp. of Dublin, Ohio) and a silicone emulsion (AF-60)
obtained from General Electric Silicone. Verisoft BTMS contains
behnyl trimethyl sulfate and cetyl alcohol, while AF-60 contains
polydimethylsiloxane, acetylaldehyde, and small percentages of
emulsifiers. In another embodiment, the lubricant layer 32 contains
a medical-grade silicone such as Dow Corning 365 silicone, which is
believed to contain water, polydimethylsiloxane, octylphenoxy
polyethoxy ethanol, propylene glycol, and polyethylene glycol
sorbitan monolaurate.
[0042] Further, besides the above-mentioned layers, the glove 20
can also contain additional layers if desired. For example, in one
embodiment, the glove 20 contains a layer 37 that defines an
environment-exposed surface 21 of the glove 20. Although optional,
the layer 37 can be utilized to inhibit blocking between the layers
and to facilitate stripping of the glove 20 from a former. For
example, in one embodiment, the layer 37 can contain
styrene-polybutadiene-styrene (S-B-S) or a polyurethane material.
It should also be understood, however, that the chemical protection
layer 36 can define the environment-exposed surface 21 of the glove
20. In such instances, the layer 37 may or may not be positioned
between the chemical protection layer 36 and the substrate body
24.
[0043] An elastomeric article made in accordance with the present
invention can generally be formed using a variety of processes
known in the art. In fact, any process capable of making an
elastomeric article can be utilized in the present invention. For
example, elastomeric article formation techniques can utilize
dipping, spraying, chlorination, drying, curing, as well as any
other technique known in the art. In this regard, referring to FIG.
3, one embodiment of a method of dip forming a glove will now be
described in more detail. Although a batch process is described and
shown herein, it should be understood that semi-batch and
continuous processes may also be utilized in the present
invention.
[0044] Initially, any well-known former, such as formers made from
metals, ceramics, or plastics, is provided. Although glove-shaped
formers are described herein, it should also be understood that
formers having any other shape (e.g., condom-shaped) can be used in
accordance with the present invention to form articles having
different shapes. The former is dipped into a dip tank containing
the modified silicone elastomer and solvent, such as xylene, water,
etc. (illustrated as numeral 62). A high shear mixer is utilized
for a sufficient time to reach a homogeneous solution prior to
dipping. After dipping, the former is removed slowly from the dip
tank, leaving a thin, uniform layer of the liquid silicone
elastomer solution deposited onto the former. Once removed from the
dip tank, the modified silicone-coated former is then dried to
remove the solvent from the coating (illustrated as numeral 64).
For example, in some embodiments, the modified silicone-coated
former can be air dried at a temperature of from about 100.degree.
F. to about 240.degree. F.
[0045] Once dried, the former is then transferred to a curing
station (e.g., oven) where the modified silicone is cured
(illustrated as numeral 66). The curing station heats the modified
silicone-coated former to a temperature sufficient to achieve the
desired level of crosslinking. For example, in some embodiments,
the curing station heats the modified silicone-coated former to a
temperature ranging from about 200.degree. F. to about 400.degree.
F., and in some embodiments, from about 200.degree. F. to about
350.degree. F. It should be understood that the curing station may
also be used to remove solvent from the chemical protection layer
36. In such instances, the modified silicone-coated former may not
be dried before being transferred to the curing station. For
example, the oven may be divided into two different zones with a
former being conveyed through the zones of increasing temperature.
One example is an oven having two zones with the first zone being
dedicated primarily to drying and the second zone being dedicated
primarily to curing. For example, the first zone can heat the
former to about 220.degree. F. and the second zone can heat the
former to about 350.degree. F. When heated, the catalyst and
crosslinking agent contained in the modified silicone coating of
the former are used to crosslink the silicone by forming a bridge
between silicone chains.
[0046] The dipping procedure is repeated as necessary so that the
chemical protection layer 36 has the desired thickness. By way of
example, the chemical protection layer 36 of a glove produced by
dip forming can have a thickness of from about 0.01 millimeters to
about 0.20 millimeters.
[0047] After the chemical protection layer 36 is formed, the entire
former is then dipped into a dip tank containing the elastomeric
polymer(s) used to form the substrate body 24 (illustrated as
numeral 68). In one embodiment, for example, the former is dipped
into a dip tank that contains at least one
styrene-ethylene-butylene-styrene (S-EB-S) block copolymer, mineral
oil, and a mutual solvent (e.g., toluene). The former is dipped
into a liquid solution of the elastomer a sufficient number of
times to build up the desired thickness on the form. By way of
example, the substrate body 24 can have a thickness of from about
0.004 to about 0.012 inches. The glove is then allowed to dry.
Methods for dip-forming S-EB-S layers are described in more detail
in U.S. Pat. Nos. 5,112,900 to Buddenhagen, et al. and 5,407,715 to
Buddenhagen, et al.
[0048] The glove former is then dipped into a solution to form the
donning layer 30 of the glove (illustrated as numeral 70). In one
embodiment, for example, the glove former is dipped into a solution
of 1,2 syndiotactic polybutadiene and toluene. The glove is then
dried. Once the body of the glove is formed, such as described
above, a bead roll station (not shown) can, in some embodiments, be
utilized to impart a cuff to the glove. For instance, the bead roll
station can contain one or more bead rolls such that the former is
indexed therethrough to be provided with cuffs. The formers may
then be transferred to a stripping station (not shown). The
stripping station can involve automatic or manual removal of the
gloves from the formers. For example, in one embodiment, the gloves
are manually removed from each former by turning each glove
inside-out as it is stripped from its corresponding former.
[0049] After being stripped, the gloves can then be chlorinated, if
desired, using any known chlorination technique, such as described
in U.S. Pat. No. 5,792,531 to Littleton, et al. (illustrated as
numeral 72). Upon chlorination, a lubricant can also be applied to
the donning surface of the glove (illustrated as numeral 74).
Specifically, the lubricant is applied to the donning surface of
the glove using a sponge during a tumbling process. The glove is
then dried in a hot air dryer.
[0050] Although various constructions and techniques for forming
elastomeric articles have been described above, it should be
understood that the present invention is not limited to any
particular construction or technique for forming the article. For
example, the layers described above may not be utilized in all
instances. Additionally, other layers not specifically referred to
above may be utilized in the present invention. Furthermore, the
present invention is also not limited to any particular type of
elastomeric article. For instance, condoms, flexible automotive
hoses, and the like, may all be formed in accordance with the
present invention with improved chemical resistance.
[0051] The present invention may be better understood with
reference to the following example.
EXAMPLE
[0052] The ability of an elastomeric article to be imparted with
chemical resistance in accordance with the present invention was
demonstrated. Initially, a glove-shaped former was dipped into a
tank containing MED 10-6640, a modified silicone elastomer
available from NuSil Technologies. After dipping, the former was
removed from the silicone dip tank and allowed to dry in air at a
temperature of 220.degree. F. to remove the solvent therefrom. Once
dried, the modified silicone-coated former was then transferred to
an oven, where it was crosslinked at a temperature of 350.degree.
F. The resulting modified silicone layer had a thickness of about
0.10 millimeters.
[0053] Upon forming the modified silicone layer, the former was
then dipped into a dip tank that contained an S-EB-S composition.
Specifically, the S-EB-S composition contained 50% by weight
Kraton.RTM. 1650 and 50% by weight Kraton.RTM. 1651. The S-EB-S
composition was combined with mineral oil (67 parts per hundred
rubber) and then dissolved in toluene so that the resulting solids
content was about 20%. After dipping, the former was removed from
the S-EB-S composition and dried in air at a temperature of
220.degree. F. The thickness of the resulting glove was 0.27
millimeters.
[0054] Various glove samples formed in the manner described above
were then tested to determine the chemical resistance of the glove.
The solvents utilized to test the samples are set forth below in
Table 1.
2TABLE 1 Solvents Tested Type Trade Name Manufacturer Bone Cement
PALACOS R RADIOPAQUE.sup.1 Biomet Orthopedics (Washaw, Indiana)
PALACOS R RADIOPAQUE.sup.2 Biomet Orthopedics (Washaw, Indiana)
Glue SUPER GLUE Elmer's Products (Columbus, Ohio) KRAZY GLUE
Elmer's Products (Columbus, Ohio) SUREHOLD PLASTIC Surehold, Inc.
SURGERY (Chicago, Illinois) Tissue Adhesive GLUSTITCH Glustitch,
Inc. (Delta, British Columbia, Canada) DERMABOND.sup.3 Ethicon,
Inc. (Somerville, New Jersey) .sup.1methylmethacrylate stabilized
with hydroquinone, N,N-dimethyl-p-toluidine, and chlorophyll
.sup.2methyl methacrylate-methyl acrylate copolymer containing
chlorophyll, benzoyl peroxide, and zirconium dioxide
.sup.3N-butylcyanoacrylate
[0055] For each solvent tested, a glove was first donned on one
hand. The solvent was placed between the thumb, index, and middle
finger, and a sweeping motion was then made for about 5 minutes
(for bone cement) and about 10 minutes (for glue and tissue
adhesive) with the thumb over the fingers. During the test period,
the glove was visually inspected for irregularities, such as
evidence of granular rubber particles, splits, cracks, dissolved
rubber, increase in tackiness, discoloration, and the like. In
addition to the above-mentioned test, an additional test was also
conducted for the samples applied with glue and tissue adhesive.
Specifically, a drop of the respective solvent was placed on each
sample. The glove was then stretched in the location where the
solvent was applied. After 24 hours, the glove was again stretched
in the same location.
[0056] Upon inspection, no irregularities were visually observed in
any of the glove samples tested.
[0057] While the invention has been described in detail with
respect to the specific embodiments thereof, it will be appreciated
that those skilled in the art, upon attaining an understanding of
the foregoing, may readily conceive of alterations to, variations
of, and equivalents to these embodiments. Accordingly, the scope of
the present invention should be assessed as that of the appended
claims and any equivalents thereto.
* * * * *