Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-06-04
2001-06-19
Nakarani, D. S. (Department: 1773)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S501000, C524S507000, C524S820000, C524S823000, C524S824000, C524S827000, C524S831000, C524S832000, C524S833000, C524S839000, C524S840000, C525S374000, C525S375000
Reexamination Certificate
active
06248815
ABSTRACT:
FIELD OF INVENTION
The present invention generally relates to a water based laminating adhesive composition and a method of using thereof in adhesives for manufacturing laminate structures. More particularly, the invention is directed to a water based laminating adhesive composition comprising a first component comprising at least one aqueous water based vinyl polymer dispersion (A) comprising the reaction product of i) at least one ethylenically unsaturated monomer, ii) at least one free radical initiator, and iii) optionally, at least one ethylenically unsaturated oligomer; and a second component comprising at least one water dispersible polyfunctional aziridine crosslinking agent (B). The adhesive compositions optionally comprises at least one aqueous polyurethane polymer dispersion (C). Improved bonded properties of dry laminated flexible film substrates are obtained with the water based laminating adhesive composition.
BACKGROUND OF THE INVENTION
In general, the function of a laminating adhesive is to join together very fine films of different or similar substrates, e.g., polyethylene, polypropylene, polyester, polyamides, metal, paper or cellophane to form composite films used for many different purposes. A suitable laminating adhesive is expected to provide excellent bonds on numerous substrates with only a small application of adhesives.
Acrylic emulsions or dispersions are also used in commercial applications as adhesives or coatings and have been described in U.S. Pat. Nos. 4,558,092, 4,403,003, 4,322,328, 4,609,690, 4,522,973 and 4,525,510.
Guagliardo, U.S. Pat. No. 4,318,833 is directed to a coating composition comprising an ethylenically unsaturated monomer polymerized insitu in the presence of a water soluble polyurethane. Guagliardo does not employ acid, amine or hydroxy functional monomers in the acrylic monomer since it would react with or terminate the isocyanate prepolymer.
Aqueous linear or crosslinked aqueous polyurethane dispersions may be used in a wide range of commercial applications such as coatings and adhesives as shown in several patents including U.S. Pat. Nos. 5,147,926, 5,610,232, 5,637,639, 5,608,000 and 5,334,690.
Meichsner et al., U.S. Pat. No. 5,147,926 disclose crosslinkable aqueous polyurethane dispersion having long shelf life and containing polyurethanes which have carbonyl and polyhydrazides and their use for the preparation of printing inks.
Yasuhiro et al., U.S. Pat. No. 5,01,881 is directed to aqueous coating composition comprising aqueous acrylic resin and urethane resin emulsion in the absence of a crosslinking agent. The coatings are used for plastic substrates.
Mitsuji et al., U.S. Pat. No. 5,281,655 is directed to aqueous coating composition for metallic and plastic substrates. The composition comprising a urethane resin emulsion, a resin for use in aqueous coating composition and a hydrophobic melamine resin as a crosslinking agent. There is no disclosure regarding the use of the composition as a laminating adhesive.
Loewrigkeit et al., U.S. Pat. No. 4,644,030 discloses a process wherein isocyanate-terminated polyurethane dispersions are polymerized using a free radical initiator.
There remains a need for a water based laminating adhesive composition that exhibits excellent adhesion in a variety of film/film and film/foil, etc. lamination applications. The laminating adhesive composition overcomes the drawbacks of the prior art. Surprisingly, the laminating adhesive composition of the present invention provides improved adhesion, bond strength and resistance properties, as well as excellent processability and storage stability as compared to other laminating adhesive compositions.
SUMMARY OF THE INVENTION
The present invention is generally directed to a water based laminating adhesive composition and its use in adhesives for manufacturing laminate structures. In particular, the invention is to a water based laminating adhesive composition comprising:
a) a first component comprising at least one aqueous vinyl polymer dispersion (A) comprising the reaction product of:
i) at least one ethylenically unsaturated monomer;
ii) at least one free radical initiator; and
iii) optionally, at least one ethylenically unsaturated oligomer; and
b) a second component comprising at least one water dispersible polyfunctional aziridine crosslinking agent (B).
Another aspect of the present invention is directed to a water based laminating adhesive composition comprising:
a) a first component comprising at least one aqueous vinyl polymer dispersion (A) comprising the reaction product of:
i) at least one ethylenically unsaturated monomer;
ii) at least one free radical initiator; and
iii) optionally, at least one ethylenically unsaturated oligomer;
b) a second component comprising at least one water dispersible polyfunctional aziridine crosslinking agent (B); and
c) a third component comprising at least one aqueous polyurethane polymer dispersion (C) comprising:
i) at least one polymeric polyol component having at least one carboxylic or sulfonic acid group neutralized with a counter cation selected from the group consisting of quaternary ammonium hydroxide, tetramethyl ammonium hydroxide, ammonium hydroxide, sodium hydroxide and organic amines;
ii) at least one polymeric polyol selected from the group consisting of polyester polyol, polyether polyol, polyesterether polyol, and mixtures thereof; and
iii) at least one polyisocyanate.
It has been discovered that improved bonded properties of dry laminated flexible film substrates, such as laminates comprising films of thermoplastics, such as polyolefin, polyesters and polyamides as well as paper, cellophane, and metals, particularly after exposure to heat and/or humidity are obtained with aqueous vinyl polymer dispersion wherein the bond strength is stabilized with a polyfunctional aziridine employed as the crosslinker of the adhesive system.
Another aspect of the present invention is a dry bonded laminate comprising a pair of flexible film substrates bonded with an adhesive, the laminating adhesive composition comprising an aqueous vinyl polymer, a crosslinker comprising a polyfunctional aziridine compound; and a polyurethane polymer having carboxylic or sulfonic acid groups thereon.
A further aspect of the invention is a curable adhesive prepared by blending the three components of the system at the time of use. The first component comprises at least one aqueous vinyl polymer dispersion (A) comprising the reaction product of i) at least one ethylenically unsaturated monomer; ii) at least one free radical initiator; and iii) optionally, at least one ethylenically unsaturated oligomer; and a second component comprising at least one water dispersible polyfunctional aziridine crosslinking agent (B). A third component comprising an aqueous polyurethane polymer dispersion, the polymer having a plurality of carboxylic or sulfonic acid groups which are neutralized with a counter cation selected from the group consisting of quaternary ammonium hydroxide, tetramethylammonium hydroxide, ammonium hydroxide, sodium hydroxide and organic amines.
A still further aspect of the invention comprises a method of manufacturing a dry bonded laminate comprising:
1) coating a first flexible substrate with a water based laminating adhesive composition comprising
a) a first component comprising at least one aqueous vinyl polymer dispersion (A) comprising the reaction product of:
i) at least one ethylenically unsaturated monomer;
ii) at least one free radical initiator; and
iii) optionally, at least one ethylenically unsaturated oligomer; and
b) a second component comprising at least one water dispersible polyfunctional aziridine crosslinking agent (B); and
c) optionally, an aqueous dispersion of polyurethane polymer having plural carboxylic or sulfonic acid groups thereon which are stabilized with a neutralizing agent;
2) drying the surface of the coated first flexible substrate with forced air and heat to form a dry coated substrate; and
3) applying onto the surface of the dry coated first flexible substrate a second flexibl
Papsin George A.
Rolando Thomas E.
Voss Peter A.
H. B. Fuller Licensing & Financing Inc.
Nakarani D. S.
Quan Nancy N.
LandOfFree
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