Coating processes – Coating remains adhesive or is intended to be made adhesive – Pressure sensitive adhesive
Reexamination Certificate
2002-05-06
2002-12-03
Henderson, Christopher (Department: 1713)
Coating processes
Coating remains adhesive or is intended to be made adhesive
Pressure sensitive adhesive
C427S287000
Reexamination Certificate
active
06488983
ABSTRACT:
This invention relates to an aqueous composition suitable for use when dry as an improved elastomeric coating, caulk, sealant or pressure sensitive adhesive, a method for preparing an aqueous emulsion polymer suitable for use as an improved elastomeric coating, caulk, sealant or pressure sensitive adhesive, and a methods for providing an improved elastomeric coating, caulk or sealant, or pressure sensitive adhesive. More particularly this invention relates to an aqueous composition suitable for use when dry as an improved elastomeric coating, caulk, sealant or pressure sensitive adhesive including a predominantly acrylic aqueous emulsion polymer, the polymer having a glass transition temperature (Tg) from −90° C. to 20° C., the polymer formed by the free radical polymerization of at least one ethylenically unsaturated nonionic acrylic monomer and 0.5-5%, by weight based on the total weight of the polymer, ethylenically unsaturated carboxylic acid monomer, until 90-99.7% of the monomers by weight, based on the total weight of the polymer, has been converted to polymer; and the subsequent polymerization at least half, by weight, of the remaining monomer to polymer in the presence of 0.1-1.0%, by weight based on the total weight of the polymer, t-amyl hydroperoxide.
The present invention serves to provide an aqueous composition suitable for use when dry as an improved elastomeric coating, caulk, or sealant so as to retain its integrity without cracking under stress even at temperatures below 0 C. Elastomeric coatings, caulks, and sealants are frequently applied to buildings and other constructions subjected to outdoor temperature extremes and desirably retain their integrity under such conditions. Also, the present serves to provide an aqueous composition suitable for use when dry as an improved pressure sensitive adhesive having improved tack which may be desirable in itself or, alternatively, provide the basis for enhancement of other adhesive properties such as peel or shear strength with retention of useful levels of tack.
U.S. Pat. No. 5,540,987 discloses emulsion polymers having low residual formaldehyde and providing saturated cellulosic webs having improved. tensile strength. The polymers are formed by the use of an hydrophobic hydroperoxide and ascorbic acid initiator throughout the course of the reaction.
The problem faced by the inventors is the provision of an aqueous composition suitable for use when dry as an improved elastomeric coating, caulk, sealant or pressure sensitive adhesive. Unexpectedly, the inventors found that the use of t-amyl hydroperoxide in the last stages of the polymerization was sufficient to provide polymers which led improved elastomeric coating, caulk, sealant or pressure sensitive adhesives.
In a first aspect of the present invention there is provided an aqueous composition suitable for use when dry as an improved elastomeric coating, caulk, sealant or pressure sensitive adhesive including a predominantly acrylic aqueous emulsion polymer, the polymer having a glass transition temperature (Tg) from −90° C. to 20° C., formed by the free radical polymerization of at least one ethylenically unsaturated nonionic acrylic monomer and 0.5-5%, by weight based on the total weight of the polymer, ethylenically unsaturated carboxylic acid monomer until 90-99.7% of the monomers by weight, based on the total weight of the polymer, has been converted to polymer and subsequently at least half of the remaining monomer is converted to polymer in the presence of 0.1-1.0%, by weight based on the total weight of the polymer, t-amyl hydroperoxide.
In a second aspect of the present invention there is provided a method for preparing an aqueous emulsion polymer suitable for use in an improved elastomeric coating, caulk, sealant or pressure sensitive adhesive including forming a predominantly acrylic aqueous emulsion polymer, the polymer having a glass transition temperature (Tg) from −90° C. to 20° C., by the free radical polymerization of at least one ethylenically unsaturated nonionic acrylic monomer and 0.5-5%, by weight based on the total weight of the polymer, ethylenically unsaturated carboxylic acid monomer until 90-99.7% of the monomers by weight, based on the total weight of the polymer, has been converted to polymer; and subsequently polymerizing at least half of the remaining monomer to polymer in the presence of 0.1-1.0%, by weight based on the total weight of said polymer, t-amyl hydroperoxide.
In a third aspect of the present invention there is provided a method for coating a substrate with an aqueous composition to provide an elastomeric coating on a substrate. In a fourth aspect of the present invention there is provided a method for applying an aqueous caulk or sealant composition to a substrate. In a fifth aspect of the present invention there is provided a method for providing a pressure sensitive adhesive on a substrate.
This invention relates to an aqueous composition suitable for use when dry as an elastomeric coating having improved low temperature elongation including a predominantly acrylic aqueous emulsion polymer, the polymer having a glass transition temperature (Tg) from −90° C. to 20° C., formed by the free radical polymerization of at least one ethylenically unsaturated nonionic acrylic monomer and 0.5-5%, by weight based on the total weight of the polymer, ethylenically unsaturated carboxylic acid monomer until 90-99.7% of the monomers by weight, based on the total weight of the polymer, has been converted to polymer and subsequently at least half of the remaining monomer is converted to polymer in the presence of 0.1-1.0%, by weight based on the total weight of the polymer, t-amyl hydroperoxide.
The predominantly acrylic aqueous emulsion polymer contains at least one copolymerized ethylenically unsaturated nonionic acrylic monomer. By “predominantly acrylic” herein is meant that the polymer contains greater than 50%, by weight, copolymerized units deriving from (meth)acrylic monomers such as, for example, (meth)acrylate esters, (meth)acrylamides, (meth)acrylonitrile, and (meth)acrylic acid. The use of the term “(meth)” followed by another term such as acrylate or acrylamide, as used throughout the disclosure, refers to both acrylates or acrylamides and methacrylates and methacrylamides, respectively.
By “nonionic monomer” herein is meant that the copolymerized monomer residue does not bear an ionic charge between pH=1-14.
The ethylenically unsaturated nonionic acrylic monomers include, for example, (meth)acrylic ester monomers including methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, lauryl acrylate, methyl methacrylate, butyl methacrylate, isodecyl methacrylate, lauryl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate. Other ethylenically unsaturated nonionic monomers which may be incorporated into the polymer with the proviso that the polymer must be predominantly acrylic in composition include, for example, styrene and substituted styrenes; butadiene; vinyl acetate, vinyl butyrate and other vinyl esters; and vinyl monomers such as vinyl chloride, vinylidene chloride. Preferred are all-acrylic, styrene/acrylic, and vinyl acertate/acrylic polymers.
The emulsion polymer contains from 0.5% to 5%, by weight based on total monomer weight, of a copolymerized monoethylenically-unsaturated carboxylic acid monomer, based on the weight of the polymer, such as, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, monomethyl itaconate, monomethyl fumarate, monobutyl fumarate, and maleic anhydride.
The emulsion polymer used in this invention may contain from 0% to 1%, by weight based on monomer weight, copolymerized multi-ethylenically unsaturated monomers such as, for example, allyl methacrylate, diallyl phthalate, 1,4-butylene glycol dimethacrylate, 1,2-ethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, and divinyl benzene.
The glass transition temperature (“Tg”) of the emulsion polymer is from &min
Bakule Ronald D.
Henderson Christopher
Rohm and Haas Company
LandOfFree
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