U.S. patent application number 14/911902 was filed with the patent office on 2016-06-30 for a latex article with static dissipating property.
The applicant listed for this patent is DIPPED PRODUCTS PLC. Invention is credited to Hasini Dangalla, K.A.L.S. Fernando, Lakshman Nethsinghe.
Application Number | 20160183611 14/911902 |
Document ID | / |
Family ID | 52468094 |
Filed Date | 2016-06-30 |
United States Patent
Application |
20160183611 |
Kind Code |
A1 |
Dangalla; Hasini ; et
al. |
June 30, 2016 |
A LATEX ARTICLE WITH STATIC DISSIPATING PROPERTY
Abstract
An elastomeric article, specifically an unsupported glove with
two layers where the outer layer has ESD properties and its method
of manufacturing is described here. The outer layer is especially
formulated with a combination of fillers to reduce the surface
resistance and volume resistance and helps to dissipate static
charge which builds up as a result of triboelectric action. The
wearer of this glove will not get any shock due to static charge
which is experienced when wearing a conventional nitrile glove
specially in applications such as spray painting
Inventors: |
Dangalla; Hasini; (Colombo,
LK) ; Nethsinghe; Lakshman; (Colombo, LK) ;
Fernando; K.A.L.S.; (Colombo, LK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DIPPED PRODUCTS PLC |
Colombo |
|
LK |
|
|
Family ID: |
52468094 |
Appl. No.: |
14/911902 |
Filed: |
July 22, 2014 |
PCT Filed: |
July 22, 2014 |
PCT NO: |
PCT/IB2014/063291 |
371 Date: |
February 12, 2016 |
Current U.S.
Class: |
2/168 |
Current CPC
Class: |
A41D 19/0058 20130101;
A41D 31/26 20190201; A41D 19/0055 20130101; A41D 2400/52
20130101 |
International
Class: |
A41D 19/00 20060101
A41D019/00; A41D 31/00 20060101 A41D031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 12, 2013 |
LK |
17292 |
Claims
1. A dipped elastomeric article made of a latex monolayer, the said
layer having static charge dissipating property.
2. The article according to claim 1 in which the said latex
monolayer is provided with a filler of conductive materials.
3. The article according to claim 1 wherein it can be made out of
elastomers made of nitrile rubber, natural rubber, neoprene, its
blends or any other rubbers, SBR, Butyl, PVC, Silicon rubber,
flouroelastomers.
4. The article according to claim 1 wherein the elastomeric latex
monolayer consists of nitrile latex which is a copolymer of
butadiene and acrylonitrile.
5. The article according to claim 1 in which the elastomeric latex
monolayer consists of nitrile latex, standard
accelerator/sulfur/zinc oxide compositions, compositions which
include non-sulfur/accelerator compositions and thermoplastic
elastomers along with electrically conductive material.
6. The article according to claim 1 in which of electrically
conductive material comprises at least one carbon composite.
7. The article as claimed in claim 5 wherein the carbon composite
is added as dispersion to the latex compound similar to any other
solid material added to a latex composition
8. An article according to claim 1 in which the said article is
unlined.
9. The article according to claim 1 in which the said article is a
glove.
10. The article as claimed in claim 8 wherein the said article is a
disposable glove, flocklined gloves or a fabric supported
glove.
11. Use of the article according to claim 8 characterized in that
the said article is used for applications where static electricity
is formed through triboelectric actions on articles which handle
during spraying techniques or other techniques in order to
dissipate static electricity.
12. The article according to claim 1 characterized in that the
whole article, or the compounds used to make this article used to
make conducting base and/or conductive pads or conductive pens for
touch screen gloves.
13. The glove according to claim 1 characterized by the following
properties. Surface resistance : 7.81.times.104 .OMEGA./sq Static
charge decay time : <0.01 Sees Tensile Strength : 25-27 Modulus
at 50% : 2.0-2.2% Modulus at 100% : 3.0-3.2%
Description
FIELD OF THE INVENTION
[0001] The invention relates latex articles specifically, gloves
which have the ability to dissipate static charge. Industrially
electrostatic dissipating gloves are used in automotive industries,
in spray painting and electronic industry. Gloves that are
currently in the market for the spray paint industry are mostly
supported gloves most commonly with a polyurethane coating or
gloves which have an electrical wire and other metal attachments
that disperse electrical charge. Many of these gloves are
cumbersome to the wearer due to the presence of external parts
attached to it and some gloves are not quite comfortable to the
wearer.
[0002] The gloves used in the electronics industry are much thinner
and are normally polyurethane coated nylon or dyneema gloves.
BACKGROUND
[0003] Static electricity is generated whenever dissimilar
materials move or abrade against another object. The capacity to
generate static electricity of a substance depends on the condition
of the surface material the objects are made out of, the dielectric
constant, surface resistance and relative humidity. Further, since
charge capacity is directly proportional to surface resistivity, a
material with a higher surface resistivity will generate a greater
static charge. Therefore in situations where static charge is
generated to dissipate the charge a material with low surface
resistance would be needed. The aim was to develop a product which
has a lower surface resistance which will subsequently dissipate
static charge. Electrostatic property can be incorporated to a
glove in three ways, either by incorporating chemical additives,
conductive fillers or by incorporating an inherent dissipating or
conductive polymers.
[0004] The chemical additives added are usually antistatic agents;
these can be either external or internal antistatic agents.
External antistatic agents can be sprayed or coated into the
finished article, while internal antistats are partially or
completely dissolved in the latex compound. The antistat slowly
"blooms" or migrate to surface and becomes electrically active.
Generally antistatic agents have two halves of opposite chemical
nature--a hydrophilic head and a hydrophobic tail. The hydrophobic
tail avoids water but interacts with polymer. The hydrophilic head
stays above surface, so antistat remains half submerged and half
exposed. The hydrophilic end attracts moisture from the environment
onto the plastic surface and forms a conductive layer on the
surface. The conductive layer allows electric charge to flow and
helps static dissipation. Although this is a cheap and an efficient
way to introduce conductivity to latex articles this has a
disadvantage that it could leach out during processing or remove by
rubbing and washing overtime. The conductivity occurring this way
varies with humidity, further due to the greasy feel on the surface
antistatic agents incorporated articles may not be suitable for
cleanroom applications due to the chemical contamination it could
impart. Antistatic agents are used in applications such as vinyl
and rubber work surfaces, polyethylene bags, polypropylene
containers/trays and rubber mats.
[0005] The second method of introducing electrical conductivity to
latex articles is by incorporating a conductive filler. Conductive
fillers can be metal particles, metal coated glass, carbon fibers,
silver powder, carbon powder or other carbonaceous materials such
as graphite. When using conductive fillers the factors to be
considered are particle conductivity, loading level and particle
shape. At low filler loading, the composite properties remain
undisturbed as the filler loading reaches a critical point, the
resistivity suddenly drops. The critical point is called the
percolation threshold where majority of filler particles are in
contact with at least two of their nearest neighbors, thereby
forming a continuous chain or network. Electrical charge passes
through the composite via this network.
[0006] Usage of inherently dissipating or conducting polymers is
the third method that can be used to incorporate static dissipation
to an article. Inherently static dissipating polymers are generally
blended with a host polymer. When blended the inherently
dissipating polymers form a separate interpenetrating network
within the host polymer. The advantage of using inherently
dissipating polymers is its less likeness to migrate or leach out,
hence can be used in clean room applications. These type of
polymers are independent of atmospheric humidity unlike the
antistatic agents. When using inherently conductive polymers, the
polymer chain provides the conductive path for the electrons. This
happens as a result of the dramatic changes on the polymer
architecture such as double bonds, conjugation and doping which can
change the electronic structure by oxidation and reduction. The
disadvantages of using conductive polymers are the loss of
stability and conductivity under ambient conditions, having poor
mechanical properties and poor processability. Examples of such
polymers are polyanilene, polypyrrole and polythiophene. Inherently
conductive polymers are used for coating materials for films and
electronic packaging.
[0007] This patent refers to use of special fillers to impart the
ESD properties (electrostatic charge dissipating properties) to a
glove.
PRIOR ART
[0008] U.S. Pat. No. 2,008,007 refers to a static dissipative
article which had been made with a coating that comprises a surface
functionalized nanoparticle component having quaternary ammine
groups which acts as antistatic agents on the surface of the
nanoparticles. Since the quaternary amine groups are bound to the
nanoparticles migration and blooming found in typical antistatic
agents is not there.
[0009] Another patent U.S. Pat. No. 5,609,969 refers to a static
dissipative packaging article comprising a coating containing
vanadium pentoxide, a polymer latex having a hydrophilic
functionality and a nonsulfonated protective binder, this acts as
an antistatic coating over an insulative polymer resin.
[0010] U.S. Pat. No. 4,828,756 refers to an electrically conductive
composite comprising a conductive composite polyacetylene moiety, a
nonconductive high nitrile resin and a dopant. The electrically
conductive composite is prepared by insitu polymerization, it
comprises the reactive products of the high nitrile resin and
conductive organic polymer.
[0011] U.S. patent application 200803006200A1 refers to elastomeric
articles specifically gloves made from a nitrile/natural rubber
blend the surface resistance below 10.sup.4 .OMEGA./sq and static
decay time of less than 60 seconds. Natural rubber has been used to
provide good softness and tactile sensitivity properties, however
Natural Rubber does not exhibit good static resistivity. It has an
outer layer that possesses antistatic properties and an inner layer
that provides desired comfort and feel. Nitrile rubber is
considered as a non-leachable polymeric antistatic agent, natural
rubber is blended with nitrile rubber to make the polymer blend to
provide antistatic property.
[0012] U.S. Pat. No. 4,769,856 refers to a antistatic fabric
supported glove made with a cutout of thin antistatic polyvinyl
chloride film. The cutout is adhered to the fabric using an
adhesive or by stitching. The cut out covers the palm, inner thumb
and finger areas of the hand This glove can be used to handle vinyl
phonograph records and other objects which can be damaged by static
electricity.
[0013] U.S. Pat. No. 3,594,222 relates to latex articles that uses
lithium chloride as an antistatic agent in rubber latex. This is
particularly used for carpets the face of which is made from
fibrous textile material which tends to accumulate static charge as
a result of friction on its surface. The charge can be dissipated
and greatly reduced due to the antistatic agent in the latex.
BRIEF SUMMARY OF THE INVENTION
[0014] It is an objective of the present invention to provide for
an elastomeric article, particularly a glove, which overcomes the
drawbacks of the above cited articles according to the state of the
art, and particularly for allowing to provide for an article and a
method for its fabrication which are fast, cheap and easy to carry
out. Furthermore the elastomeric article is stable relating to its
mechanical and antistatic properties and easy to dress and
wear.
[0015] The present invention refers to a latex article specifically
a glove made of nitrile rubber which has the ability to dissipate
static charge. The nitrile rubber can be made according to a
standard mix of sulphur/accelerator/zinc oxide formulation.
According to a first feature of the present invention the
elastomeric article and in particularly the glove is formed by an
unlined elastomeric layer of a composition comprising a nitrile
rubber, particularly according to the above known standard mixture
and a conductive filler.
[0016] The article and particularly the glove can be fabricated by
using conventional dipping technology.
[0017] The unlined nitrile glove, according to the invention and
which helps to reduce the surface conductivity of the glove and
subsequently help the dissipation of static charge which could
accumulate due to triboelectric action thanks to the conductive
filler. Apart from being static dissipative this glove is
economical, comfortable to the wearer and has good chemical
resistance. This fully dipped unlined nitrile glove can be
specially used in industries where paint is sprayed where static
charge builds up while holding the appliance due to triboelectric
action. The glove has been formulated to dissipate static charge as
it forms along the glove and allowed to be earthed through human
body.
DETAILED DESCRIPTION OF THE INVENTION
[0018] According to a first generic non limiting example the static
dissipative nitrile article and particularly the glove is made
using nitrile rubber, standard sulphur/accelerator/zinc oxide
formulations with a conductive filler composed of carbon and
carbonaceous materials.
[0019] The said conductive filler is provided in a quantity of 2.1%
to 7.4% in weight of the standard mixture of nitrile rubber,
standard sulphur/accelerator, zinc oxide, preferably in the range
of 6.7% to 7.1% in weight. Typical carbon and carbonaceous
materials which can be used alone or in combination are carbon
composites and graphite.
[0020] A typical non limiting example of a formulation of the said
nitrile rubber mixture is: [0021] Nitrile rubber 100% in weight of
the glove [0022] sulphur 1.3% in weight of the glove [0023]
Accelerator 1.14% in weight of the glove [0024] zinc oxide 4.4% in
weight of the glove
[0025] The article is obtained using a coagulant dipping process
which is followed by leaching and curing cycles. In this process a
clean, preheated mold, more specifically a former is dipped into a
coagulant that comprises of calcium nitrate and dried. Then the
coagulant coated former is dipped into a latex compound that is has
been compounded with all the necessary ingredients to form a glove.
Then glove is cured and subsequently leached to remove the salt,
dried and chlorinated.
[0026] Then the surface resistance and the static charge decay time
of the glove was measured. The term "surface resistivity" is
defined as the resistance measured on the surface of a material.
Electrodes are placed on the surface of the material, a voltage is
applied and resistance between the electrodes is measured. The
ability of a material to discharge static electricity is classified
according to its static resistivity. Static charge decay time
measures the ability of a grounded material to dissipate a charge
induced on its surface. As per the standard EN 1149 an
electrostatic dissipative material should have a static decay time
less than 4 seconds and a surface resistance less than or equal to
2.5.times.10.sup.9. The glove developed met the above requirements
and complies with EN 1149.
* * * * *