Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-06-10
2001-05-15
Hoke, Veronica P. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C005S655300, C427S245000, C427S412300, C524S446000, C524S448000, C524S447000, C524S791000, C524S836000
Reexamination Certificate
active
06232389
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to novel barrier coatings and their use in the manufacture of articles requiring reductions in gas, chemical and vapor permeability.
BACKGROUND OF THE INVENTION
Barrier coatings which prevent, or reduce, contact of a selected substrate with a gas, vapor, chemical and/or aroma have been widely described, and such coatings are used in a variety of industries, e.g., the packaging industries, automobile industries, paint industries, tire industries etc. Some of these barrier mixtures or coatings have been proposed to contain plate-like structures to reduce permeability. See, for example, E. L. Cussler et al,
J. Membrane Sci.,
38:161-174 (1988); W. J. Ward et al,
J. Membrane Sci.,
55:173-180 (1991); U.S. Pat. Nos. 4,528,235; 4,536,425; 4,911,218; 4,960,639; 4,983,432; 5,091,467; and 5,049,609; and International Patent Application No. WO93/04118, published Mar. 4, 1993, among others.
Despite the numerous disclosures of barrier coatings mixtures, most of the coatings useful in the industry either do not optimally reduce permeability or tend to be brittle and non-flexible. For example, attempts to improve the gas permeability of butyl rubber as well as retain its elasticity and fatigue resistance, have involved coating butyl rubber in tires with a polymer containing a platelet filler. See, e.g., U.S. Pat. Nos. 4,911,218 and 5,049,609. Only minimal decreases in permeability were achieved by this process.
Other attempts to increase the gas barrier properties of rubber used in tires have included compositions of rubber having layered silicate platelets dispersed within the rubber composition. See e.g. U.S. Pat. No. 4,857,397; WO97/00910 and G. J. van Amerogen, “Diffusion in Elastomers”,
Rubber Chem Tech
37, pp 1065-1152 (1964). Exfoliated layered silicate material has been used to improve the gas barrier properties of rubber. See, e.g. U.S. Pat. No. 5,552,469.
Several references have been made to the orientation of platelet materials in rubber and polymeric compositions. Specific perpendicular orientation of the platelets to the direction of gas diffusion has been found to decrease gas permeability of rubber compositions containing layered silicate platelets, while not adversely affecting the flexibility of the rubber. See e.g. U.S. Pat. Nos. 5,576,372; 5,576,373; and 5,665,183. Puncture resistance is increased in polymeric sheet material comprising discrete platelets which are oriented substantially parallel to the plane of the sheet material in an overlapping interrelation. See, e.g., U.S. Pat. No. 5,665,810.
Most of the coatings useful in the industry which contain platelet type fillers are prepared by melt processing, in which solid polymer and solid filler are melted together and mixed at high shear rates. Such melt-processed coatings have 100% solids, and usually use less than about 3% by weight of the platelet fillers. Such coatings do not optimally reduce permeability.
Various improvements have been described in the manufacture or treatment of tires or tire components to decrease permeability of the inner tire surface or the interfaces between the tire layers or components to gases, vapors and chemicals. In the tire industry, for example, it has been conventional to add fillers, e.g., carbon black, up to about 30% by volume (or 100 parts per hundred) to innerliners, or to use coatings to improve impermeability of butyl rubber. However, such attempts have not been found to optimally reduce permeability. Tires with integral innerliners are disclosed in U.S. Pat. No. 5,178,702, wherein the tire has a top layer and multiple layers of rubber laminate in which at least two layers are barrier layers comprising a sulfur cured rubber composition having 100 parts by weight rubber, 100 parts by weight acrylonitrile/diene polymer and about 25-150 parts by weight of platy filler of unspecified width and thickness. These compositions are stated to reduce the costs of the innerliners while maintaining flexibility and barrier performance.
An additional application for barrier coatings utilizing elastomers with fillers is as a coating or bladders or other surfaces in pneumatic devices or any device under pressure such as sport balls, etc. Many sport balls use a bladder to hold air or other gas inside the ball. Sport ball bladders are currently made using natural or butyl rubber or polyurethane. The choice of these materials is determined by the trade-off between mechanical properties, air barrier properties, and cost. The use of standard, non-flexible barrier coatings to reduce the loss of air or the thickness of the bladder is not acceptable due to the flexibility requirements of the application.
There remains a need in the art for barrier coating mixtures and flexible and elastomeric articles with improved permeability characteristics useful in a variety of industries. More particularly, there is a need in the art for barrier coating mixtures to improve the air retention and/or reduce the thickness of the innerliner in sport balls and any other device under pressure, such as soccer balls, basketballs, tennis balls, toy balls, inflatable boats, inflatable mattresses or beds, etc.
SUMMARY OF THE INVENTION
The present invention solves the problems of the prior art by providing a coating composition which contains substantially dispersed exfoliated layered silicates in an elastomeric polymer. This coating, when dried, results in an elastomeric barrier with a high effective aspect ratio and improved permeability characteristics, i.e., a greater increase in the reduction of permeability of the coating. This coating has multiple applications, including, for example, tires, sport balls, and articles in which an internal air pressure must be maintained.
In one aspect, the present invention provides a coated article comprising an elastomeric substrate that contains air or a gas under pressure, and having on an interior or exterior surface of said substrate a barrier coating formed by applying to said surface a mixture comprising in a carrier liquid: (a) an elastomeric polymer; (b) a dispersed exfoliated layered platelet filler having an aspect ratio greater than 25; and (c) at least one surfactant. The solids content of said mixture is less than 30% and the ratio of polymer (a) to filler (b) is between 20:1 and 1:1. The coating is dried on the coated surface, wherein said dried barrier coating has the same polymer to filler as in said mixture and provides an at least 5-fold greater reduction in gas, vapor, moisture or chemical permeability than a coating formed of said unfilled polymer (a) alone. The coated article comprises any elastomeric substrate that contains air or another gas under pressure, or an elastomeric substrate that requires the exclusion of air, water, or other gas or vapors. Such coated articles include, e.g., sports balls, such as tennis balls, basketballs, etc., as wells as golf balls (for moisture resistance), inflatable boats and air mattresses and other inflatable beds, and the like.
In one preferred embodiment, the article is coated with a barrier coating mixture, which contains the polymer at between about 1 to 30% in liquid form and between about 45% to about 95% by weight in the dried coating. The dispersed layered filler is present in the liquid coating mixture at between about 1 to about 10% by weight, and in the dried coating formed thereby, at between about 5% to about 55% by weight. The dried coating, in which the filler exhibits an effective aspect ratio of greater than about 25, and preferably greater than about 100, reduces the gas, vapor or chemical permeability greater than 5-fold that of the dried, unfilled polymer alone.
In another preferred embodiment, the invention provides an elastomeric article coated with a preferred barrier coating mixture which has a solids contents of between about 5 to about 15% by weight, and comprises in its dried state between about 65% to about 90% by weight of a butyl rubber latex, between about 10% to about 35% by weight of a layered filler, desirably vermiculite, and between
Farrell Michele
Feeney Carrie A.
Goldberg Harris A.
Grah Michael D.
Lu Mengshi
Hoke Veronica P.
Howson and Howson
InMat, LLC
LandOfFree
Barrier coating of an elastomer and a dispersed layered... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Barrier coating of an elastomer and a dispersed layered..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Barrier coating of an elastomer and a dispersed layered... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2501474