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
2001-02-20
2003-04-29
Wu, David W. (Department: 1713)
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...
C524S457000, C524S425000, C524S610000, C229S245000
Reexamination Certificate
active
06555615
ABSTRACT:
The present invention relates to a coating composition that can be applied to the surface of a substrate to form a coating that provides protection to that surface against a variety of adverse environmental conditions, yet is easily removable as a continuous sheet. The present invention further relates to a method of preparing the coating, as well as the use of the coating as a removable coating when applied to the surface of such substrates as metal, glass, plastic, coated metal, coated glass, coated plastic, fiberglass, ceramics, mica, paper, and wood.
A variety of coatings are known in the art. Many of these coatings are polymer based, and are applied to the surfaces of substrates such as metal, glass, and plastic which may or may not already be coated with one or more coating compositions. While many of these coatings are intended to be permanent, there is also a need for coatings that, for a period of time, provide protection to surfaces against deterioration due to adverse environmental conditions, such as, for example, contact with sharp objects, with objects bearing transferable color bodies, and with acid rain and other airborne and waterborne contaminants. Although the time interval during which the coating must provide protection may be as long as months, or even years, it is further desirable that such temporary coatings be removable when the level of protection they provide is no longer needed, or perhaps no longer desired.
The need for removable protective coatings exists, for example, during the production, storage, and distribution of vehicles, appliances, computers, furniture, sporting equipment, and the parts from which they are manufactured, as well as building material. An example of an industry having stringent requirements for peelable coatings is the automotive industry. In the automotive industry, a need exists for a removable protective coating to protect the automobile against weathering, contamination from the atmosphere, chemical attack or accidental damage during manufacturing, handling, storage and transit. Absent protective coating, the vehicle's paint is vulnerable to significant in-house mutilation and physical damage on the assembly line. During assembly of the vehicle, the paint finish may be inadvertently dinged, chipped and scratched as the workers use their tools to assemble the various parts of the vehicle. When such damage occurs, the vehicle's paint finish must undergo costly and time consuming touch-up procedures. Therefore, it is very advantageous to have the vehicle's paint finish protected by a coating. In a similar manner, the glass surfaces (e.g., windows) and plastic surfaces (e.g., tail lights and dashboards) require protection to minimize costs associated with remediation of damage, or even rejection by wholesalers, retailers, and the ultimate customers.
Because it is acceptance by the ultimate customer that is at stake, it is not enough to protect an automobile on the assembly line. Vulnerable surfaces of automobiles, and other vehicles must also be protected during prolonged outdoor storage and transportation. During such storage and transportation, the coating must be highly resistant to the onslaught of a host of deleterious environmental factors, including rain, acid rain, flying objects, ultraviolet (UV) radiation, and a variety of airborne and waterborne contaminants. To maintain its high degree of resistance, the protective coating must not be easily penetrable or swellable by water. To maintain a “just off the assembly line” appearance to the coated vehicle, the coating should resist dirt pick-up. Finally, when the time comes to reveal the still pristine surface, it is highly desirable to be able to quickly and smoothly remove the entire coating, leaving no residue, without recourse to labor intensive processes, use of any additional materials (e.g., solvents, acids, bases, and aqueous detergents), or generation of waste streams.
Although the automotive industry was chosen to illustrate the needs and requirements for removable coatings, these same needs and requirements also exist to a greater or lesser degree in industries dealing with, for example, other vehicles, appliances, computers, furniture, sporting equipment, building material, and the parts from which those finished products are manufactured.
When outdoor exposure is not at issue, the performance requirements for the peelable coating may be less stringent. If, for example, it is desired that an existing floor be protected while workers are carrying out construction activities in an interior space, it is advantageous to provide the floor with a peelable coating. Here, acid rain is not an issue and it is desirable to have a coating composition that provides a non-tacky protective surface, at low cost.
One early attempt to provide a temporary protective coating was the use of a wax coating on a painted automobile body. Wax provided a weatherproof and, to some extent, damage-resistant layer. However, the application of wax can be time consuming and difficult and its removal typically requires the use of organic solvents, creating hazardous conditions in the workplace as well as in the general environment.
Another type of removable, protective film composition is disclosed in U.S. Pat. No. 5,010,131. This film is disclosed for use in paint spray booths to protect the booth and equipment therein from paint overspray. The thermally releasable coating composition comprises water, a film-former, a filler, an alkaline source, and a blowing agent. Film-formers disclosed are selected from the group consisting of vinyl acetate copolymer emulsions, sugar, soap, certain organic salts, and polyvinyl alcohol. The film is sprayed onto a surface and allowed to dry. After the film has become contaminated with paint overspray, it is removed by action of a pressurized spray of hot water (at least 88° C.). The action of the hot water activates the blowing agent which helps to release the film from substrates. Thus, the film is not peelable without recourse to taking special measures. Further, the removal process results in the presence of potentially hazardous particulate waste material in process water. This creates significant waste removal problems for the practitioner.
A protective coating removable by re-wetting with water is disclosed in U.S. Pat. No. 5,604,282, for application to the surfaces of automobiles, airplanes, and counter tops. The aqueous coating composition includes poly(alkyl acrylate), for film forming and water resistance, and poly(vinyl alcohol) for water penetration. Release agents such as silicon polymers and hydrocarbon waxes are also present, along with surfactants, dispersants, and plasticizers. While the coatings derived from these compositions resist water penetration initially, they are specifically designed to be penetrated during prolonged contact with water such that they can be swollen to some degree and removed. The removal step, therefore, is time consuming. The release agents are not water soluble, necessitating the use of detergents in the water wash during removal, leading to creation of waste streams that must be treated. Further, the penetration of water through the coating over time provides a pathway for waterborne contaminants to contact the surfaces ostensibly being protected. In particular, acid rain penetration to a surface exposes that surface to corrosion and other chemical reactions that cause permanent damage.
Japanese patent JP87047463 discloses paper labels bearing pressure sensitive adhesive that may be removed cleanly from substrates and that resist becoming increasingly difficult to remove with aging. The polymers used in the adhesive composition are acrylic emulsion polymers. The polymers have glass transition temperatures of 0° C. or lower, and are not crosslinked. The adhesive composition further includes a plasticizer. An amphoteric surfactant may also be present and is described as improving anchoring power of the adhesive to the paper label so that transfer of the adhesive from the paper to the substrate
Cheung William K
Clikeman Richard B.
Rohm and Haas Company
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