U.S. patent application number 14/480709 was filed with the patent office on 2015-02-19 for method for producing thin film gloves using the cutting and sealing process and glove produced therefrom.
The applicant listed for this patent is Foodhandler, Inc.. Invention is credited to Jian Tao.
Application Number | 20150047097 14/480709 |
Document ID | / |
Family ID | 50383823 |
Filed Date | 2015-02-19 |
United States Patent
Application |
20150047097 |
Kind Code |
A1 |
Tao; Jian |
February 19, 2015 |
METHOD FOR PRODUCING THIN FILM GLOVES USING THE CUTTING AND SEALING
PROCESS AND GLOVE PRODUCED THEREFROM
Abstract
A single use disposable glove having two or more layers with a
thickness which can range from 0.02 mm to 0.04 mmm for food
handling with satisfactory formfitting and durability, all the way
up to about 0.10 mm and above for heavy duty applications while
still maintaining comfort like that of natural and synthetic
rubbers. Materials such as styrene-ethylene-butadiene-styrene
(SEBS) or styrene-isoprene-styrene (SIS) may be used to produce
single use disposable gloves employing the cutting and sealing
method. The use of these compositions could have a thickness
between about 0.02 mm and about 0.1 mm or above. More importantly,
the use of these compositions in the cutting and sealing process
would yield a glove having better elasticity. The film quality
using the various extrusion techniques would outperform a glove
produced by the dipping process, not only in integrity (pinhole
rate) but also in a thickness profile (uniformity).
Inventors: |
Tao; Jian; (Reno,
NV) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Foodhandler, Inc. |
Reno |
NV |
US |
|
|
Family ID: |
50383823 |
Appl. No.: |
14/480709 |
Filed: |
September 9, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14039702 |
Sep 27, 2013 |
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14480709 |
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12923198 |
Sep 8, 2010 |
8572765 |
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14039702 |
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Current U.S.
Class: |
2/167 |
Current CPC
Class: |
Y10T 156/1054 20150115;
A41D 19/0006 20130101; A41D 19/0068 20130101; A41D 19/0055
20130101; A41D 19/02 20130101 |
Class at
Publication: |
2/167 |
International
Class: |
A41D 19/02 20060101
A41D019/02; A41D 19/00 20060101 A41D019/00 |
Claims
1. A single use disposable glove, comprising: at least one top
layer comprising at least one layer film in the form of a hand; at
least one bottom layer comprising a layer of film in the form of a
hand, wherein a portion of the periphery of said at least one
bottom layer is sealed to a portion of the periphery of said at
least one top layer to form a glove; wherein an opening is provided
between said at least one top layer and said at least one bottom
layer for the insertion of a human hand between said at least one
top layer and said at least one bottom layer, wherein at least one
of said top layer and said bottom layer consists of between about
70% and 90% ethylene or propylene components.
2. The glove of claim 1, wherein a thickness of said at least one
top layer and said at least one bottom layer is between 0.03 mm and
0.06 mm
3. The glove of claim 1, wherein deformation of said glove is
between 10% and 30% after a 100% stretch.
4. The glove of claim 1 wherein the weight of the glove is between
1.5 grams and 3.1 grams
5. The glove of claim 1 wherein a weight of at least one of said
top layer and bottom layer is approximately 30%-70% of the total
glove weight.
6. The glove of claim 1 wherein the thickness of one of the top
layer and bottom layer is thicker than the other of said
layers.
7. The glove of claim 1 wherein the thickness of the top layer and
bottom layer is approximately the same.
8. The glove of claim 1 wherein at least one of the top layer and
bottom layer consists of at least polyvinyl chloride.
9. The glove of claim 9 wherein at least one of said top layer and
bottom layer include DEHP, citrates, adipates, azelates,
phosphates, trimellitates, chlorinated paraffin, or polyesters as a
plasticizer.
Description
RELATED APPLICATION DATA
[0001] This application is a continuation of U.S.
Continuation-in-Part patent application Ser. No. 14/039,702, filed
Sep. 27, 2013, and claims priority to and the benefit of U.S.
Non-Provisional patent application Ser. No. 12/923,198, filed Sep.
8, 2010, which are incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention is directed to a method of producing a
single use disposable glove using the cutting and sealing
process.
BACKGROUND OF THE INVENTION
[0003] The most widely used element to protect an individual's hand
during work or other endeavors would be a glove. Historically,
gloves were produced utilizing a large number of different
processes as well as various sorts of materials depending on the
variety of applications.
[0004] For example, gloves used in gardening and in sports which
would require the use of a heavy duty material would be made by
sewing pieces of these materials together. These materials would
include, but are not limited to leather, fabric, non-woven cloth
and various combinations of these materials. Furthermore, these
types of gloves were made to last through a number of repetitive
usages. Additionally, the purpose of these types of gloves was to
protect the user's hand and not necessarily other individuals.
[0005] Single use disposable gloves have been produced for
utilization in, but not limited to medical procedures as well as
for use in the food service industry. These types of single use
gloves are employed to protect both the user as well as other
individuals from contact with various germs or pathogens.
Generally, these types of single use disposable gloves are
manufactured using a dipping method or a cutting and heat sealing
method.
[0006] The dipping method would employ a three dimensional hand
shaped former which is introduced into a forming liquid compound. A
portion of the forming liquid compound would adhere to the hand
shaped former to produce a thin layer of film thereon. After this
thin layer of film solidifies, the thin layer film would be
stripped from the former, thereby producing a glove. This type of
process is generally utilized to produce medical examination and
surgical gloves, due to the fact that the combination of the three
dimensional former would yield a glove which is relatively form
fitting on the user's hand. This is due in part to the effective
elasticity of the materials used during the dipping process. This
form fitting characteristic of gloves produced by the dipping
process is measured by applying stress to the glove for the purpose
of deforming the glove and then releasing the glove from the
stress. A measurement is then made as to whether the glove fully
recovered to its original shape after being released from the
stress. For example, utilizing a rubber glove formed from the
dipping process, the deformation after a 100% stretch is less than
10%.
[0007] The dipping process employs a wide range of plastic and
rubber polymers such as, but not limited to, natural rubber latex
(NRL), carboxylated acrylonitrile butadiene copolymer (Nitrile),
polyisoprene (PI), polychloroporene (Neoprene), polyurethane (PU),
polyvinyl chloride (PVC) etc., as well as the various combinations
produced via blending and copolymerization of these materials. A
combination of these materials can be used from a blend of two or
more of these compounds in a single dipping step. Conversely, a
multiple dipping process producing a structured film provided with
multiple layers can be employed. Generally, medical gloves produced
by the dipping process would have a thickness of at least 0.08 mm
for natural rubber latex or at least 0.05 mm for the aforementioned
compounds. This parameter is required by the FDA and/or ASTM.
Additionally, it is noted that it would be extremely difficult, if
not impossible, to use the dipping process to produce films having
a thickness of less than 0.05 mm without compromising the integrity
of the produced film. Among the aforementioned materials, NRL,
Nitrile and PVC would account for at least 95% of all commercially
produced medical examination gloves. Table 1 lists the major
attributes of these gloves.
TABLE-US-00001 TABLE 1 Typical properties of dipped PVC, NRL and
Nitrile medical examination gloves Properties PVC NRL Nitrile
Tensile Strength (MPA) 11~15 18~25 25~40 Elongation (%) 300~400
~800 ~600 Deformation after 100% stretch (%) 8~15 ~5 5~10 Thickness
range (mm) 0.05~0.10 0.08~0.12 0.05~0.12 Weight (grams) 3.5~10 3~10
2.5~10
[0008] While the physical properties of these gloves are quite
different in terms of tensile strength and elongation, they also
share quite some common characteristics such as thickness, weight,
and deformation; after all, the application is the same, for
medical examination.
[0009] Due to the fact that the combination of the three
dimensional former and the minimal deformation, all these materials
could yield very good form fitting articles. To characterize the
form fitting parameter, a specimen is stressed to deform the
article and is then the form is released to measure if the article
could fully recover to its original shape. Quantitatively, the
dumbbell specimen is stretched to 100% elongation and is held for
ten seconds. The specimen is released and the length is immediately
measured, as well as within ten seconds of the release. As the data
in Table 1 is demonstrated, all the gloves have a deformation less
than 15%, demonstrating that these gloves are form fitting
gloves.
[0010] Another common characteristic is the fact that all of these
gloves are thicker than 0.05 mm. On one hand, it is required by FDA
regulations and ASTM standards for medical devices. On the other
hand technically, it is also extremely difficult, if not impossible
to dip films at thickness less than 0.05 mm without compromising
film integrity severely.
[0011] Dipped gloves are mainly used as medical devices as well as
commonly seen in food service industries. However, the majority of
food service gloves are made via a cutting and sealing process. The
prior art cutting and sealing process would utilize polymers
extruded by, but not limited to, blowing, casting or calendaring
the polymers into thin films. Two films would be laid upon each
other on a flat surface. If a glove is to be produced, a metallic
hand shaped knife constructed from, but not limited to, copper or
stainless steel would be applied to the top of the first film to
cut through both film layers. Since the hand shaped knife is also
heated, the layers would be welded together along the cutting line
as the films are cut to form one glove.
[0012] Table 2 illustrates the properties of a typical prior art
food service glove manufactured by polyethylene (PE) using the
cutting and sealing method.
TABLE-US-00002 TABLE 2 Typical properties of cut and sealed PE food
service glove Properties PE Tensile Strength (MPa) 11~15 Elongation
(%) ~600 Deformation after 100% stretch (%) 30~50 Thickness range
(mm) 0.01~0.02 Weight (grams) <2
[0013] Disposable gloves used in the food service industry are
generally manufactured using this process. The most common material
for this process is polyethylene. Due to the combination of
producing the gloves using a two dimensional flat former and the
plastic nature of polyethylene, in contradistinction to the gloves
formed by the dipping process, the gloves produced by the cutting
and sealing process are much less form fitting to the user's hand.
As a matter of fact, these gloves are very baggy and clumsy for
task performance. In terms of deformation after a 100% stretch of
the produced gloves, in contrast to the 10% recovery of the
materials generally used in the dipping process, the use of
polyethylene would exhibit a deformation of 30%, or even 50%.
Furthermore, since these gloves could have a thickness of less than
0.02 mm, the durability of these gloves is poor. Technically, to
exclude thicker films is not a problem, but such a thick
polyethylene glove would be very uncomfortable to wear and would be
difficult to perform the required tasks needed in the food handling
industry.
SUMMARY OF THE INVENTION
[0014] The deficiencies of the prior art are addressed by the
present invention which describes a process of producing a single
use disposable glove using the cutting and sealing process. In a
first embodiment, this process would produce a glove having two or
more layers with a thickness in the range of 0.02 mm to 0.06 mm. A
second embodiment would produce a glove having two or more layers
with a thickness which can range from 0.02 mm to 0.04 mmm for food
handling with satisfactory formfitting and durability, all the way
up to about 0.10 mm and above for heavy duty applications while
still maintaining comfort like that of natural and synthetic
rubbers.
[0015] In the first embodiment, a number of polymeric materials
would be used in place of the prior art use of polyethylene to
produce single use disposable gloves employing the cutting and
sealing method. These materials would include, but are not limited
to, polyvinyl chloride, a polyolefin copolymer such as ethylene
propylene copolymer. The use of these compositions would have a
thickness between 0.02 mm to 0.06 mm and would have a much improved
durability than the 0.02 mm polyethylene film produced by the prior
art. More importantly, the use of these compositions in the cutting
and sealing process would yield a glove having better elasticity
than plastic polyethylene. This deformation would be between
10%-30% and, in some cases, even less than 10%, comparable to that
of the rubbery articles produced by the dipping method. The film
quality using the various extrusion techniques would outperform a
glove produced by the dipping process, not only in integrity
(pinhole rate) but also in a thickness profile (uniformity).
[0016] In the second embodiment, materials such as
styrene-ethylene-butadiene-styrene (SEBS) or
styrene-isoprene-styrene (SIS) may be used in place of the prior
art use of polyethylene to produce single use disposable gloves
employing the cutting and sealing method. The use of these
compositions would could have a thickness between about 0.02 mm to
about 0.1 mm or above, and would have a much improved durability
than the 0.02 mm polyethylene film produced by the prior art. More
importantly, the use of these compositions in the cutting and
sealing process would yield a glove having better elasticity than
plastic polyethylene. This deformation would be between 5% and 30%,
and more preferably between 5% and 15%, comparable to that of the
rubbery articles produced by the dipping method. The film quality
using the various extrusion techniques would outperform a glove
produced by the dipping process, not only in integrity (pinhole
rate) but also in a thickness profile (uniformity).
[0017] While in theory a dipping process could also yield multiple
layered structures via multiple dipping steps, in reality in the
marketplace, it is rare to find a commercially viable glove that is
made of two layers of different materials, or use different
formulations. As a matter of fact, almost all gloves made via a
double dipping process do not use different materials, or different
formulations. This is because different materials may require quite
different mechanisms and conditions to cure, but the dipping line
conditions are always the same. In the case that a double dipping
process employed two different formulations or materials, those
would form the inner and outer surface of the resulted glove. Since
the dipped article forms one piece, there is no way to have such a
case that the palm and the back are made from different
formulations or materials.
[0018] This invention can produce gloves 1 that have much more
complicated structures than a dipping process. First of all, it is
easy to create multiple layered structured films using coextrusion.
For a thin film, it is common to have triple layers or more, not to
mention only two layers. Secondly, since the glove seals two
separate films, 10 and 15, upon each other with one side 15 being
the palm and the other side 10 being the back, one can produce a
glove with the palm and back made from different materials.
Furthermore, due to the fact that two separate films, 10 and 15,
could be produced in different machines, one can easily produce a
glove 1 having the palm of one thickness and the back of another
thickness. Therefore, one can increase the palm thickness for
durability improvement whereas lower the thickness of the back for
cost reduction. Consistent with the fact that the thicknesses of
the two separate films are different, the weight of each of the
films could also be different. For example, one of the layers could
account for 50%.about.70% of the total glove weight, whereas the
second layer would encompass 30%.about.50% of the total glove
weight.
[0019] In terms of thickness control, the dipping process usually
yields a broad range of thicknesses. For most of the glove, if the
palm or cuff thickness is desired to be 0.06 mm, the entire
thickness profile over the surface of the glove could be anywhere
between 0.05 mm to 0.10 mm. This should be compared to the extruded
film utilized in the cutting and sealing process which would allow
the thickness control position to be much better. If the desired
thickness is 0.06 mm, the glove can easily be manufactured having a
profile narrower than 0.055 to 0.065 mm, or even .+-.0.002 mm,
which could not be produced using the prior art dipping
process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 shows the glove in the shape of a hand; and
[0021] FIG. 2 shows a cross-sectional view of the glove along the
line A-A.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention overcomes the poor plastic deformation
after stress produced by the prior art cutting and sealing process
employing polyethylene to produce the multiple layers of the glove.
In a first embodiment, this is accomplished by utilizing a family
of thermoplastic elastomers such as, but not limited to, polyvinyl
chloride, polystyrene, polyurethane, polybutene, styrene-butadiene
copolymers, ethylene-propylene copolymers, their mixtures as well
as their blends. The use of these compositions for one, both, or
additional film layers would produce a glove having a thickness in
the range of 0.02 mm to 0.05 mm with excellent film integrity, but
also good elasticity, thereby reducing hand fatigue. With improved
hand shape, not only would the glove be classified as truly form
fitting, but it would also exhibit improved durability as well as
increased thickness without increasing the weight.
[0023] Comparing the materials used in the present invention with
the dipping technology, in addition to film quality and reduced
thickness, the utilization of the cutting and sealing process
employing the films produced by the above-listed compositions,
would provide for a more versatile film structure, as well as glove
material selection. For example, utilizing polyvinyl chloride to
make a plastisol compound suitable for the manufacture of a glove
using the dipping process, very limited choices on plasticized
selections can be made. This is true, for example, since the
dipping compound must be liquid at room temperature. More
critically, the material that is utilized must have a viscosity at
a certain range for thickness and film tensile strength
optimization. Using the cutting and sealing approach, the film
forming extrusion process could be produced but not limited to
blowing, casting or calendaring. Since the extrusion machine would
be able to utilize a solid resin, there is no limit on the
viscosity, since one can even utilize non-liquid form
plasticizers.
[0024] The following examples would illustrate the present
invention as compared to a prior art glove using polyvinyl chloride
in the dipping process as well as the prior art glove produced by
polyethylene using the cutting and sealing process.
EXAMPLE 1
Polyvinyl Chloride and Phthalates Plasticizer
[0025] Traditionally, utilizing a polyvinyl chloride liquid
compound that is suitable for producing a glove employing the
dipping process, viscosity and boiling point requirements
prohibited the choices of plasticizers tremendously. Among the many
families of plasticizers, dialkyl phthalates are most widely
adopted. This is a very highly controversial situation since there
are concerns about their effect on health and food contact, most
noticeably utilizing diethylhexyl phthalate (DEHP). However, using
an extruder to produce films employed in the cutting and sealing
process, the requirement for plasticizers is much more flexible.
Not only can one choose a non-conventional plasticizer such as
citrates, adipates and polyesters, even for the same plasticizers,
the use of extrusion to produce the film layers could adopt a much
wider plasticizer range because of no limit on the viscosity. As a
result of that, a polyvinyl chloride glove produced by the cutting
and sealing process could be more flexible or durable depending
upon its intended application.
[0026] As one of the most widely used thermoplastic materials,
polyvinyl chloride has been used far beyond the medical examination
glove industry. However, whether used in the glove industry or not,
the most widely plasticizer used with polyvinyl chloride is
diethylhexyl phthalate (DEHP) or dioctyl phthalate (DOP) family.
This combination shows excellent heat sealability used in the
cutting and sealing process. Table 3 illustrates the properties of
heat sealed PVC/DEHP gloves. This table shows the use of different
thicknesses of the glove. However, the composition of each of the
gloves is the same.
TABLE-US-00003 TABLE 3 Properties of cut and heat sealed PVC/DEHP
gloves Properties PVC 1 PVC2 Tensile Strength (MPa) ~15 ~15
Elongation (%) ~340 ~340 Deformation after 100% stretch (%) ~11 ~11
Thickness range (mm) 0.040 .+-. 0.002 0.060 .+-. 0.002 Weight
(grams) 2.7 3.5 Phthalates Content (%) 50 50
[0027] It is certainly not surprising that the characteristics of
the gloves illustrated in Table 3 showed almost the identical
tensile strength, elongation and deformation of the gloves
illustrated in Table 1 produced by the dipping method. This is due
to the fact that these properties are largely influenced by the
particular formulations. Film formation process has little impact
on these parameters. This is obviously true with the PVC glove
shown in Table 1. However, it is quite important that the gloves
shown in Table 3 are noticeably lighter than the gloves shown in
Table 1. Even at a thickness of 0.060 mm, the gloves shown in Table
3 are much lighter than the gloves shown in Table 1. The PVC glove
illustrated in Table 1 is greater than 5 grams. This is contrasted
to the PVC gloves illustrated in Table 3 having a weight of 2.7 or
3.5 grams. It would be impossible to produce an overall weight of
3.5 grams for a PVC glove using the dipping process. Clearly it
would be even more difficult to produce a PVC glove from the
dipping process having a weight of 2.7 grams without compromising
film integrity. Furthermore, since the PVC gloves shown in Table 3
are lighter than the PVC as well as NRL and Nitrile gloves shown in
Table 1, less material is used, producing a savings in the cost of
producing the glove. It is noted that the formulation of the PVC1
and PVC2 gloves in Table 3 area identical. The only differences
between these two gloves are the amount of material in one or more
layers of film to produce gloves having different thicknesses or
weight.
[0028] Even comparing with conventional polyvinyl chloride gloves,
the gloves produced by the present invention is more
environmentally friendly. There is no fusing at high temperature
needed, resulting in only a small amount of plasticizers released
into the atmosphere, thereby creating a more energy efficient
system. Additionally, the polyvinyl glove produced by the present
invention insures a more healthy working environmental condition to
the worker's using the gloves as well as reducing fire hazard
dangers. Furthermore, since the PVC gloves shown in Table 3 were
much lighter than those gloves shown in Table 1, they will be more
comfortable when used by the workers.
EXAMPLE 2
Polyvinyl Chloride without Phthalates Plasticizers
[0029] As previously described in Example 1, DEHP has been used as
a plasticizer with polyvinyl chloride. However, since there are
concerns about the use of DEHP as a plasticizer, Example 2 employs
a polyvinyl chloride liquid compound without phthalate
plasticizers. Even though PVC glove manufacturers using the dipping
method have steadily migrated from the use of DEHP, the plasticizer
choices are still confined to the phthalates family mostly using
diisononyl phthalate (DINP) as the alternative to DEHP.
[0030] Using a film forming extrusion process such as, but not
limited to blowing, casting or calendaring, the requirement for
plasticizers is more flexible. Various non-conventional
plasticizers such as, but not limited to adipates, citrates,
azelates, phosphates, trimellitates, chlorinated paraffin as well
as their combinations via mixing can be used. Even for the same
plasticizers, extrusion could adopt a much wider plasticizer range
because of no limit on viscosity. As a result, a polyvinyl chloride
glove made from the cutting and sealing process could be more
flexible or durable dependent upon the intended applications. Table
4 lists the properties of two PVC gloves produced by the cutting
and sealing process without the use of phthalates.
TABLE-US-00004 TABLE 4 Properties cut and heat sealed phthalates
free PVC gloves Properties PVC 3 PVC 4 Tensile Strength (MPa) 15 20
Elongation (%) 340 278 Deformation after 100% stretch (%) 11 12
Thickness range (mm) 0.040 .+-. 0.002 0.040 .+-. 0.002 Weight
(grams) 2.7 2.7 Phthalates Content (%) N/A N/A
[0031] Without the limitation on the viscosity of plasticizer
choices, it is possible to produce a PVC glove with tensile
strength that is comparable with that of natural rubber latex at 20
MPa. Furthermore, since no phthalates have been used, this glove is
more environmentally friendly as well as less hazardous to the
user. A standard thermal stabilizer is always used in a PVC glove.
However, the thermal stabilizer does not have any impact on the
sealing procedure. Generally, the thermal stabilizer would be
approximately 1 or 2% of the composition. For example, PVC3 uses a
trimellitate family of plasticizers and PVC4 used an adipate family
of plasticizers.
EXAMPLE 3
Ethylene Propylene Copolymer (EPC)
[0032] Generally, as previously described, gloves used in the food
service industry are predominantly constructed from polyethylene.
These films are formed using either a blowing or casting process
prior to employing the cutting and sealing process. Typically, the
thickness of these gloves is purposely controlled to be less than
0.02 mm. If the glove is thicker than 0.02 mm, plastic polyethylene
can be quite tough. Not only is it impossible to form the
application as desired, but it could also quickly cause hand
fatigue. As a result of thin thickness, the polyethylene gloves
produced by the cutting and sealing process were not durable. As a
matter of fact, most of these gloves were disposed in several
minutes.
[0033] The present invention utilizing a glove produced by an
ethylene propylene copolymer film is almost as flexible as the
glove produced by rubbery materials. Additionally, at a thickness
of between 0.030 and 0.060 mm, it is soft and comfortable without
causing finger fatigue after one hour of use, as well as being
durable.
[0034] Table 5 shows a comparison of the present invention using
two ethylene propylene copolymers produced by the cutting and
sealing process.
TABLE-US-00005 TABLE 5 Properties of EPC cut and sealed gloves
Properties EPC 1 EPC 2 Tensile Strength (MPa) 22 21 Elongation (%)
577 618 Deformation after 100% stretch (%) 11 12 Thickness range
(mm) 0.045 .+-. 0.002 0.060 .+-. 0.002 Weight (grams) 2.5 3.1
[0035] Comparing the two EPC gloves shown in Table 5 with a
conventional polyethylene glove formed by the cutting and sealing
process, the glove produced by the present invention is more
environmentally friendly. Approximately the same amount of
materials would be used to produce the EPC glove according to the
present invention with respect to the polyethylene glove. However,
the glove according to the present invention has a greater
thickness than the conventional polypropylene glove thereby
creating a glove which is more durable. EPC1 and EPC2 have a high
propylene content of between 70 and 90%. The difference between
EPC1 and EPC2 is the amount of material used in one or more of the
films, thereby producing a glove (EPC2) which is thicker and
heavier than EPC1.
EXAMPLE 4
Ethylene Propylene Copolymer (EPC)
[0036] By choosing a variety of ethylene propylene copolymers (EPC)
with different ethylene to propylene ratios, it is possible to
produce a glove having vastly different performance
characteristics. In terms of thickness deformation, a glove can be
produced having as low as less than 10% deformation after 100%
stretch which is comparable to rubbery materials to almost 30%
completely plastic materials. It is possible to produce a glove
having a thickness of 0.04 mm which is still comfortable to be
utilized. Properties of additional EPC gloves produced by
additional EPC copolymers are shown in Table 6. EPC3 and EPC4 have
a high ethylene content of between 70 and 90%. The difference
between EPC3 and EPC4 is the amount of material used in one or more
of the films. More material is used in the EPC3 gloves, thereby
producing a glove which is thicker and heavier than the EPC4
glove.
TABLE-US-00006 TABLE 6 Properties of EPC cut and sealed gloves
Properties EPC 3 EPC 4 Tensile Strength (MPa) 16 15 Elongation (%)
725 688 Deformation after 100% stretch (%) 20 28 Thickness range
(mm) 0.040 .+-. 0.002 0.025 .+-. 0.002 Weight (grams) 2.5 1.5
[0037] Comparing these EPC gloves with a conventional polyethylene
glove, the EPC gloves are more environmentally friendly and use
virtually the same amount of materials while producing a more
durable glove. EPC gloves to not include either a thermal
stabilizer or a plasticizer.
[0038] Comparing the present invention utilizing an ethylene
propylene copolymer with that of polyvinyl chloride using the
dipping process, this embodiment of the present invention is
certainly more environmentally friendly since no phthalate
plasticizer is being used. Additionally, with almost the same
amount of materials used, the present invention would last much
longer than the glove produced by the cutting and sealing process
employing polyethylene.
[0039] A second embodiment of the present invention also overcomes
the poor plastic deformation after stress produced by the prior art
cutting and sealing process employing polyethylene to produce the
multiple layers of the glove. In the second embodiment, this is
accomplished by utilizing thermoplastic elastomers such as, but not
limited to, SEBS and SIS, their mixtures as well as their blends.
The use of these compositions for one, both, or additional film
layers would produce a glove having a thickness in the range of
0.03 mm to 0.1 mm with excellent film integrity, but also good
elasticity, thereby reducing hand fatigue. With improved hand
shape, not only would the glove be classified as truly form
fitting, but it would also exhibit improved durability as well as
increased thickness without increasing the weight.
EXAMPLE 5
Styrene-Ethylene-Butadiene-Styrene ("SEBS")
[0040] The elasticity of SEBS comes from its butadiene segment,
which is the same segment which gives Nitrile gloves their
elasticity. Thus, gloves made from SEBS can be manufactured to be
as comfortable as Nitrile gloves, and potentially more comfortable
at higher thicknesses. In additional, as SEBS is a thermoplastic
elastomer unlike Nitrile, it does not need a vulcanization process.
Thus, SEBS is more environmentally friendly than is Nitrile. It is
recognized that the tensile strength of SEBS is lower than that of
Nitrile due to its thermoplastic nature. However, the tensile
strength of SEBS is at comparable to that of latex, and it is even
stronger than vinyl gloves.
[0041] Additionally, the ethylene segment of SEBS provides
compatibility to many plastics and paraffin materials in
substantially any ratio. By taking advantage of both plastic and
rubbery materials, a wide range of products can be formulated for a
variety of applications, as desired. Table 7 illustrates several
variations of SEBS materials and their properties.
TABLE-US-00007 TABLE 7 Properties of SEBS Formulations Properties
SEBS I SEBS II SEBS III SEBS IV Tensile Strength (MPa) 15 13 12 22
Elongation (%) 590 624 603 555 Deformation after 100% 5 10 15 30
stretch (%) Thickness range (mm) 0.07 0.04 0.04 0.04 Weight (grams)
3.5 2.5 2.5 2.5
[0042] In Table 7, SEBS I is substantially pure SEBS. SEBS II is a
SEBS/mineral oil formulation with a ratio of about 2:1. SEBS III is
a SEBS/mineral oil formulation with a ratio of about 1:1. SEBS IV
is a SEBS/PE formulation with a ratio of about 1:2
[0043] As can be seen, SEBS I-III demonstrate a fairly low change
in elongation after being stretched (i.e., plastic deformation).
Thus, the varying ration of SEBS to mineral oil changed the
elasticity of the formulations relatively little. The addition of
mineral oil can impact costs, but lowers the tensile strength--and
thus film integrity--of the materials. Further, SEBS IV, in which
plastic polyethylene was added, shows a dramatic improvement in
tensile strength and costs less, but the elasticity is
compromised.
EXAMPLE 6
Styrene-Isoprene-Styrene ("SIS")
[0044] The elasticity of SIS comes from its isoprene segment, which
is the same segment which gives natural rubber latex its
elasticity. Thus, gloves made from SIS can be manufactured to be
extremely elastic. Even at thicknesses as high as 0.1 mm, which
exceed FDA and ASTM requirements for medical examination to provide
satisfactory protection in unknown circumstances, SIS gloves are
comfortable to wearers. Table 8 illustrates two variations of SIS
materials and their properties.
TABLE-US-00008 TABLE 8 Properties of SIS Formulations Properties
SIS I SIS II Tensile Strength (MPa) 6.5 14.1 Elongation (%) 1300
924 Deformation after 100% stretch (%) 5 5 Thickness range (mm)
0.10 .+-. 0.05 0.10 .+-. 0.05 Weight (grams) 5.5 5.5
[0045] As can be seen, the SIS I formulation showed extreme
elasticity, but SIS II is much more balanced with respect to
strength and elasticity. Both SIS I and SIS II formulations are
substantially comprised of SIS copolymer. However, the two
formulations have different copolymer grades. SIS I contains only
about 17% of styrene and 83% of isoprene, whereas SIS II contains
about 27% of styrene and 73% of isoprene. As the result of these
composition difference, the morphologies of these formulations are
also slight different. The micro-phase of styrene domain in SIS I
is spheres, but the micro-phase of SIS II is hexagonally packed
cylinders. The different compositions and micro-phases give SIS II
a higher tensile strength.
[0046] The process of producing a single use disposable glove
employing the cutting and sealing process with the inventive
compositions will now be explained. The films used to produce the
glove using the cutting and sealing process will be produced by an
extrusion process such as, but not limited to, blowing, casting and
calendaring. The films would be planar in nature and each of the
films would be placed on top of one another on a flat surface.
Although two films are generally used to produce the single use
disposable glove, it is possible to use a plurality of films. Once
the planar films are placed on top of one another, a template knife
in the shape and size of the glove is placed on the top surface and
pressure is applied to cut these films in the shape of the applied
template and, since the template is heated, the two or more layers
would be welded together to form the glove. As can be appreciated,
the cuff of the glove would not be welded together allowing an
opening for the placement of the user's hand within the produced
glove.
[0047] As can be appreciated, each film layer can be produced by
the different compositions, blends or mixtures of the materials to
be used in the cutting and sealing process as previously described.
The determination of the composition of each of the films would be
based upon the use to which each glove would be directed.
[0048] While particular embodiments and applications of the present
invention have been illustrated and described, it is to be
understood that the invention is not limited to the precise
construction and compositions disclosed herein and that various
modification, changes, and variations may be apparent from the
foregoing descriptions without departing from the spirit and scope
of the invention as defined in the appended claims.
* * * * *