Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
1999-12-17
2004-02-03
Nolan, Sandra M. (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S036910, C522S046000, C522S106000, C524S081000, C524S220000, C524S221000, C524S591000, C525S420000, C525S423000, C525S424000, C525S425000, C525S426000, C525S427000, C525S431000, C528S271000, C528S310000, C528S320000, C528S322000, C528S422000
Reexamination Certificate
active
06686008
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to silicone containing compositions and coatings formed therewith having barrier properties which are useful in packaging applications. In another aspects, the invention relates to a method for the manufacture of a coated substrate having barrier properties and to a packaging container.
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. As 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 Corp. 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 to graft the coating to the film surface and further improve 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 an aminofunctional silane, a multifunctional acrylate 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.
While other patents teach the combination of a mono or multifunctional acrylate with an aminofunctional silane, none teaches the addition of the ethylenically unsaturated acid with an acrylate. For example, U.S. Pat. No. 5,368,941 teaches a deformable, abrasion-resistant coating formulated from at least one multi-functional acrylate monomer, at least one aminofunctional silane, colloidal silica and at least one acrylate-terminated polyalkylene oxide. The acrylate-terminated polyalkylene oxide helps prevent gelling of the coating composition during stripping and also imparts the composition with deformability, without sacrificing abrasion resistance.
Also, U.S. Pat. No. 5,434,007 teaches a silane resin coated on a plastic film, where the silica resin is composed of a monofunctional acrylate and an aminofunctional silane. The composition does not utilize a free radical cure, nor does it incorporate the ethylenically unsaturated acid.
U.S. Pat. Nos. 5,260,350 and 5,374,483 and EP-A-666,290 relate to a silicone coating composition which, when cured on a solid substrate either by ultraviolet or electron beam radiation, provides a transparent abrasion resistant coating firmly adhered thereon. The silicone coating is prepared by reacting at least one multifunctional acrylate monomer with an amino-organofunctional silane, mixing the modified silane with at least one acrylic monomer and thereafter adding colloidal silica. Again however, neither of these compositions teach the addition of an ethylenically unsaturated acid to achieve barrier properties. 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.
The present invention is distinguishable over each of the above cited prior art because none teach the combination of an aminosilane, multifunctional acrylate and ethylenically unsaturated acid to achieve gas barrier properties.
SUMMARY OF THE INVENTION
The invention is a composition made by mixing in any order a multifunctional acrylate with an amino functional silane and an ethylenically unsaturated acid to form a reaction product, optionally dissolved in a solvent, where the multifunctional acrylate has a molecular weight of from about 100 to about 3000, and the aminofunctional silane has at least one molecule of the formula
wherein
0≦a≦4
R
1
is independently hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, arylalkyl, acryl, methacryl, alkylaryl, R
2
—SiR
m
(OR)
3-m
, or an alkylene linking group having 2 to 12 carbon atoms connected to one or two nitrogen atoms, with the proviso that at least one R
1
is a hydrogen atom and at least one R
1
is an R
2
—SiR
m
(OR)
3-m
group, when m is 0, 1 or 2, and R is independently a hydrogen or an alkyl group having from 1 to 6 carbon atoms;
R
2
is independently selected from the group consisting of:
linear or branched alkylene groups having from 1 to 12 carbon atoms;
arylene groups having from 6 to 12 carbon atoms; and
linear or branched hydrocarbon groups having from 1 to 16 carbon atoms and at least one alcohol, alcohol ether, ester, amide, urea, thiourea or polyether group.
In the scope of the present description, molecular weight means number average molecule weight in the case of polymers and exact weight in the case of small molecules or of oligomers. The composition can be coated on a substrate, then optionally exposed to moisture and treated to initiate a free radical reaction. The composition can be applied to a variety of substrates used in packaging applications. The composition can be cured by further heating in the presence of moisture. The free radical reaction can be initiated not only by heating but by electron beam irradiation, ultraviolet radiation, gamma radiation, and/or heat and chemical free radical initiators.
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. As used herein, the terminology “improved barrier” refers to a coating which can reduce oxygen transmission rate of the aforementioned uncoated polypropylene film from 1500 cc/m
2
/day to 250 cc/m
2
/day as measured at ASTM D3985-81 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. It should be understood, however, that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the spirit and scope of the invention and/or claims of the embodiments illustrated.
Aminofunctional Silanes
The aminofunctional silanes are described generally by the formula:
wherein
0≦a≦4
R
1
is independently hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, arylalkyl, acryl, methacryl, alkylaryl, R
2
—SiR
m
(OR)
3-m
, or an alkylene linking group having 2 to 12 carbon atoms connected to one or two nitrogen atoms, with the proviso that at least one R
1
is a hydrogen atom and at least one R
1
is an R
2
—SiR
m
(OR)
3-m
group, where m is 0, 1 or 2, and R is independently a hydrogen or an alkyl group having from 1 to 6 carbon atoms;
R
2
is independently selected from the group consisting of:
linear or branched alkylene groups having from 1 to 12 carbon atoms;
arylene groups having from 6 to 12 carbon atoms; and
linear or branched hydrocarbon groups having from 1 to 16 carbon atoms and at least one alcohol, alcohol ether, ester, amide, urea, thiourea or polyether group.
The most preferred aminofunctional silanes used for the present invention are N-(2-aminoethyl)-3-aminopropyltrimethyoxy silane, and aminopropyltriethoxysilane, an
Branch Karen
Futter Daniel
Merlin Patrick J.
Power Gary
Rangwalla Imtiaz
EG Technology Partners, L.P.
Nolan Sandra M.
Zombeck Alan
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