Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
1999-07-15
2002-06-04
Gallagher, John J. (Department: 1733)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C156S273700, C156S331100, C156S331800, C528S392000
Reexamination Certificate
active
06399171
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to polyamine containing coatings having both barrier and adhesive properties which are useful in packaging applications.
BACKGROUND OF THE INVENTION
It is well known that coatings containing silane compounds and itaconic acid improve the gas, oil, and flavor barrier performance of organic polymer film substrates. Moreover, the adhesion of the coating to the film surface, as well as the improved barrier characteristics provided by the silane coating, are greatly enhanced by exposing the coated film to electron beam radiation.
A particularly useful barrier composition is described in U.S. Pat. No. 5,215,822, which teaches a methanol solution of a vinyl benzyl amine silane (Dow Corning Z-6032), itaconic acid, and water; coating this solution on a corona treated low density polyethylene film, drying, and then subjecting the coated film to electron beam radiation grafts the coating to the film surface further improves the barrier properties of the silane coating. However, while this coating gives excellent gas barrier properties at low to moderate relative humidity values, the gas permeability increases drastically at very high relative humidity values.
The present inventors have surprisingly discovered that the combination of a polyamine and an ethylenically unsaturated acid gives excellent gas barrier properties at low to moderate relative humidity values, as well as excellent gas barrier properties at very high relative humidity values. The acid group and the amine form an amine salt which imparts excellent barrier properties to the composition. The composition may be crosslinked to further improve barrier.
None of the prior art teaches the present invention. For example, U.S. Pat. No. 4,761,435 claims UV curable polyethylenically unsaturated compositions in combination with a polyamine resin, which use an aryl ketone photosensitizer. The '435 patent teaches that acid functionality in the compositions is undesirable (col. 5, line 24). The patentees indicate that the formation of amine salts is to be avoided, because the photosensitizer reacts only with an amine, and not an amine salt. This is in contrast to the present invention, which teaches that the formation of acid salts is desirable and results in superior barrier properties.
Another example, U.S. Pat. No. 4,943,600, teaches the combination of a tertiary amine containing resin, allyl terminated resin, and a maleate functional resin. Likewise the patentee teaches that the compositions are formulated to minimize or eliminate carboxyl functionality, which contrasts directly with the present invention.
U.S. Pat. No. 5,017,406 claims UV curable compositions which contain reactive unsaturated compounds, but does not teach the use of a polyamine or an unsaturated acid as does the present invention.
JP (Kokai) publication 7-18221 published on Jan. 20, 1995 teaches a surface treatment composition for gas barrier comprising an aminosilane and a compound having an aromatic ring or hydrogenated ring. The present invention is distinguishable, however, because it does not require the addition of cyclic compounds having an aromatic ring, nor does the reference teach the addition of an ethylenically unsaturated acid.
The present invention is distinguishable from the prior art because none teach the addition of an ethylenically unsaturated acid to achieve gas barrier properties, nor do they teach a composition having both barrier and adhesive characteristics.
SUMMARY OF THE INVENTION
The present invention relates to a method of laminating two substrates by coating at least one side of a substrate with a laminating adhesive, bringing a coated side of said substrate into contact with a second substrate to form a three layer film, and treating said three layer film with a free radical initiator, wherein said laminating adhesive is formed by mixing an ethylenically unsaturated acid and a polyamine, wherein said polyamine optionally has a crosslinker reacted therein, and wherein said polyamine has four or more A, B, or C units, where:
A is an —R
2
—N(R
1
)
2
unit, B is an R
1
—N(R
2
—)
2
unit, and C is an (—R
2
)
3
N— unit, where:
R
1
is independently selected from
hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, arylalkyl, and alkylaryl, and
R
2
is independently selected from the group consisting of:
linear or branched alkylene groups or substituted alkylene groups having from 1 to 18 carbon atoms, and arylene groups or substituted arylene groups having from 6 to 18 carbon atoms.
The invention can be used to laminate a variety of substrates for use in packaging applications. A composition according to the present invention may be employed to provide a barrier layer which improves resistance of the material to transmission of gases and aromas therethrough. For example, a 30 micron uncoated biaxially oriented, corona treated polypropylene film is generally found to have a permeability to oxygen of 1500 cc/m
2
/day as measured at ASTM D3985-81 measured at 80% relative humidity. With the present coatings, the oxygen transmission rate of the same film can be reduced to less than 250 cc/m
2
/day as measured at 80% relative humidity.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
While the invention is susceptible of embodiment in many different forms there is described herein in detail preferred and alternate embodiments of the invention.
Polyamines
The polyamines of the present invention are polymeric, homopolymeric or copolymeric polyamines having four or more A, B, or C units, where:
A is an —R
2
—N(R
1
)
2
unit, B is an R
1
—N(R
2
—)
2
unit, and C is an (—R
2
)
3
N— unit, where:
R
1
is independently selected from
hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, arylalkyl, and alkylaryl, and
R
2
is independently selected from the group consisting of:
linear or branched alkylene groups or substituted alkylene groups having from 1 to 18 carbon atoms, and arylene groups or substituted arylene groups having from 6 to 18 carbon atoms.
For example, R
1
or R
2
can be substituted with hydroxyl groups.
The amines of the present invention preferably have molecular weights of from about 150 to about 2,000,000, with about 400 to about 400,000 preferred, and most preferred being from about 600 to about 80,000. The high degree of polymerization of the amine provides a lower degree of tackiness in the final composition. The lower molecular weight polyamines can be further polymerized to form higher molecular weight polyamines by methods well known in the art, such as by reaction with dialkyl halides (i.e. ethylene dichloride), diisocyanates (e.g. tolydiisocyanate, hexamethylene diisocyanate), di(meth)acrylate esters (e.g. hexene diol diacrylate pentaerythritol diacrylate), diepoxides (ethylene glycol diglycidyl ether).
Examples of polyamines useful for the invention include polyvinyl amines, aminofunctional polyacryl amides, poly-DADMAC's polyvinyl pyrrolidene copolymers, polyethylenimine and the reaction product of ethylene diamine and epichlorohydic copolymers.
A preferred polyamine that can be used to achieve varying degrees of tackiness is the class of polyamines referred to as polyalkylenimines, such as polyethylenimine, which is readily available in a wide range of molecular weights and different degrees of branching. Polyethylenimines consist of a large family of water-soluble, i.e. hydrophilic, polyamines of varying molecular weight and degree of chemical modification. It is generally known that the polymerization of ethylenimine does not result in a polymer that is completely composed of units having a linear structure, but also a degree of branching depending on the acid concentration and the temperature during polymerization. This degree of branching may, for example, vary between 12 and 38 percent. The formula of polyethylenimine can be represented in the form of A, B, or C units, where A is an —R
2
—N(R
1
)
2
unit, B is an R
1
—N(R
2
—)
2
unit, and C is an (—R
2
)
3
N— unit, where R
1
is hydrogen R
2
is an —CH
2
CH
2
— group. The ratio of A to B to C units can be
Branch Karen
Futter Daniel
Merlin Patrick J.
Power Gary
Rangwalla Imtiaz
Dow Corning Corporation
Gallagher John J.
Gearhart Richard
Zombeck Alan
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