Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-07-08
2001-12-04
Nakarani, D. S. (Department: 1773)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S307300, C156S329000
Reexamination Certificate
active
06325885
ABSTRACT:
TECHNICAL FIELD
The invention pertains in general to pressure sensitive adhesives and more particularly to a temporary pressure-sensitive adhesive which provides a temporary bond between an article and a horizontal surface. The adhesive is particularly suitable for temporarily attaching an article such as a vase to a substantially flat surface, such as a glass shelf or fireplace mantel. Once attached the article remains on the surface during an earthquake or other physical movement, thus providing protection for the article.
BACKGROUND ART
Previously many different types of products have been developed for temporarily attaching various articles to a flat surface. Securing articles consists of maintaining an object, such as glassware and statuary, and insuring that the article is secure in the event of an external physical force, such as an unplanned movement, wind or an earthquake that could cause the article to move and subsequently fall and break.
In the past, people have utilized adhesive tape, glue, waxes, putty blends and other like substances to provide a securing means.
Unfortunately, these types of products offered not enough or too much adhesion. Adhesive tape provides good holding strength for paper and other relatively thin, light-weight items but is ineffective for holding articles with more substantial weight. Glue provides an excellent holding and securing means for most articles but, after most glues have dried and set, it is at best difficult if not impossible to move the article without damage to the shelf and/or the article.
Waxes, putty blends and other chemical mixtures attempt to provide a high-strength, non-permanent adhesive for use on many different surfaces. One such adhesive was derived from a pseudoplastic substance, which, when applied to an article, would allow an adhesive bond to form between two surfaces. Initially this type of adhesive appeared to be effective, however after prolonged or repeated use it was determined that the adhesive would lose a substantial amount of its adhesive properties and after an extended period of time become ineffective.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention, however, the following U.S. patents are considered related:
U.S. Pat. No.
INVENTOR
ISSUED
5,566,031
Meyr, et at
Oct. 15, 1996
5,473,005
Columbus, et al
Dec. 5, 1995
5,328,696
Noel
July 12, 1994
4,460,371
Abber
July 17, 1984
4,016,328
Horning
April 5, 1977
The U.S. Pat. No. 5,566,031 discloses a silicone gel composed of crosslinking two-part silicone rubbers causing vulcanization. The gel is used as a transparent sealing tape adhesive for electrical components which permits the sealing of two materials with very different coefficients of thermal expansions improving the adhesion strength due to the elasticity of the gel.
The U.S. Pat. No. 5,473,005 discloses the use of an adhesive gel based on polyvinyl alcohol, which has thixotrophic characteristics for adhering porous and semiporous substrates such as paper, cloth and wood.
The U.S. Pat. No. 5,328,696 discloses a hot-melt silicone pressure sensitive adhesive compositions containing waxes, silicate resins and silicone fluids. It was disclosed that the addition of an organic wax having a melting point between 30° C. and 150° C. decreased the dynamic viscosity of the adhesive at temperatures equal to or below 200° C.
The U.S. Pat. No. 4,460,371 provides a pressure sensitive adhesive formed from a crosslink polymerization of methyl/phenyl siloxane gum, dimethyl siloxane gum and a polysiloxane resin. The resulting product is suitable for adhering a large number of surfaces and has particular utility as an adhesive between plastic film and human skin demonstrating liquid permeability and release characteristics.
The U.S. Pat. No. 4,016,328 discloses a pressure sensitive tape using a silicone resin, silicone gum and a curing agent to produce superior peel strengths. The patent utilizes an admixture of silicone resin and a hydroxyl heat-cured octamethylcyclotetrasiloxane gum, or a chemically-cured dimethylpolysiloxane gum solubilized in xylene to form solutions between 55% to 65% solids. The only similarity between this patent and the instant application is the incorporation of a similar silicone gum, known as dimethylpolysiloxane, which is cited as a component in one of the 25 examples of the adhesive solutions. The performance of the adhesive solution is based on its chemical interaction, whereby the dimethylpolysiloxane gum is “cured” and the adhesive solution is coated onto a two mil etched polytetrafluoropolyethylene film which acts as a carrier for the adhesive to be applied to a surface. In contrast, the applicant's adhesive is based on the inherent adhesive properties of the “uncured” form of the silicone gum, dimethylpolysiloxane, without further additives either chemically or physically. Additionally due to its physical properties, no carrier is necessary for the applied adhesive.
DISCLOSURE OF THE INVENTION
The temporary pressure-sensitive adhesive functions with a polyorganosiloxane gum which inherently offers thixotropic properties. Due to the thixotropic nature of the polyorganosiloxane gum, which is used without any chemical modification, the viscosity of the adhesive will breakdown as it is exposed to gravity and will continue to flow as pressure is exerted. When pressure is released, the adhesive does not return to its original form, and thus on a horizontal surface will flow to form a gel film with adhesive properties for porous, semi-porous and non-porous substrates. The adhesive gel is particularly suitable for securing an article such as a vase to a horizontal surface, such as a shelf or mantle. A bond is produced by the adhesive gel that is sufficient to prevent the article (first substrate) from moving from the horizontal surface (second substrate).
The adhesive gel is transparent and exhibits a wet tack with a low rate of set. This feature allows the first substrate which is in position with the second substrate on a horizontal plane to be repositionable for a limited time prior to the formation of the adhesive bond. The temporary adhesive bond forms with time between the two substrates. Firm pressure on the first or upper substrate ensures good initial adhesion, initiates the viscosity breakdown of the polyorganosiloxane gum, and decreases the time required to achieve a final adhesive bond which temporarily holds the two substrates together.
The adhesive bond is temporary and can be broken by physical stress or a shearing force applied to the first substrate. The adhesive gel can easily be removed from the second substrate surface by rubbing mechanically with a finger of applying adhesive residue with a small quantity of the adhesive.
In view of the above disclosure, it is the primary object of the invention to provide a thixotrophic, adhesive gel based on a polyorganosiloxane gum that provides strong, temporary bond between two substrates of similar or different compositions. It is also an object of the invention to provide a temporary adhesive that:
allows the temporary bond to be broken by physical stress,
can be reused,
is in the form of a transparent gel which exhibits a wet tack with a low rate of set,
can be formed into any shape manually, such as a ball, disc or rod, for application to the substrates,
is non-toxic and is not an irritant to the skin and eyes as defined in the Federal Hazardous Substances Act (FHSA),
allows surfaces utilizing the adhesive gel to be cleaned with common household cleaners without affecting the adhesive strength, and
is cost effective from both a manufacturer's and consumer's point of view.
These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4016328 (1977-04-01), Horning
Lewis, D'Amato, Brisbois & Bisgaard LLP
Nakarani D. S.
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