Stock material or miscellaneous articles – Composite – Of polyester
Reexamination Certificate
2002-12-17
2004-06-01
Chen, Vivian (Department: 1773)
Stock material or miscellaneous articles
Composite
Of polyester
C428S3550AC, C428S480000, C428S522000, C526S287000, C526S318000, C526S318300, C526S318400, C526S318410, C526S318440, C526S318500, C526S319000, C526S328000, C526S329000, C526S329500, C526S329700, C525S206000, C525S221000, C525S222000, C525S227000, C525S228000, C525S230000
Reexamination Certificate
active
06743520
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is concerned with a primer composition for a polymeric film and a primed polymeric film suitable for use in the preparation of an anti-fouling surface.
The pollution of the environment, and in particular air pollution, represents a problem for exterior surfaces exposed to the atmosphere. The materials used in the construction of the exterior surfaces of, for example, buildings, vehicles and other man-made structures, may become contaminated as a result of pollutants present in the atmosphere. Particulate material present in the atmosphere, such as dust, combustion products and inorganic material (for example clay particles), is deposited on the outer surfaces of buildings and vehicles. Upon exposure to rainfall, such deposits, as well as particles present in rainwater, flow with the rainwater across these outer surfaces. The deposits may become ingrained in the material of the exterior surface of the building and the building becomes soiled. Such contamination is particularly problematic for constructions that are in close proximity to vehicular traffic and also for the exterior surfaces of the vehicles themselves. The fouling of the exterior surfaces of the windows and mirrors of vehicles is a particular problem.
Various means of combating this problem have previously been disclosed. For instance, EP-0903389-A discloses an anti-fouling composition having a hydrophobic component and a hydrophilic component. The hydrophilicity is induced by a photocatalyst component. In one embodiment, EP-0903389-A discloses a composition comprising a photocatalytic oxide such as titanium dioxide, a silicone resin or silica and a water-repellent fluororesin. The composition may be coated onto the surface of a substrate, such as metal, ceramic, glass, plastic, wood, stone, cement, concrete, fibres and fabrics, in accordance with known coating techniques for the purpose of imparting an anti-fouling property to the substrate.
For reasons of economy and convenience, it is usually desirable to prepare the anti-fouling composition at a location that is remote from the article to which it is to be applied. For this reason it is desirable to provide a film structure comprising the anti-fouling composition as a coating on a base film. The coated base film would then be transported to the location of the article or surface to be protected, which may comprise any of the surfaces mentioned above, and the film laminated or adhered thereto. However, it is difficult to obtain a satisfactory and long-lasting adhesion between the base film and the anti-fouling coating composition, which is often silicone-based. In addition, known films often suffer from poor weatherability and, over time, may become brittle and/or show deterioration in optical properties and/or colour. Thus, on ageing a film may develop microcracks as a result of weathering which will accelerate film degradation, increase haze, promote brittleness and cause a deterioration in inter-layer adhesion.
It is an object of this invention to provide a primer composition for coating onto a film substrate for improving the adhesion characteristics between the film substrate and an anti-fouling coating composition. It is a further object of this invention to provide a film which exhibits improved adhesion to an anti-fouling composition. It is a further object of this invention to provide a film substrate suitable for use as a base film for an anti-fouling composition. It is a further object of this invention to provide a film which exhibits improved UV stability and weatherability.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, there is provided a composition comprising:
(i) a copolymer of (a) 35 to 40 mole % alkyl acrylate, (b) 35 to 40% alkyl methacrylate, (c) 10 to 15 mole % of a comonomer containing a free carboxyl group, and (d) 15 to 20 mole % of an aromatic sulphonic acid and/or salt thereof;
(ii) an acrylic and/or methacrylic polymeric resin; and
(iii) a cross-linking agent.
The composition is suitable for use as a primer coating on a polymeric film substrate, particularly a film substrate for an anti-fouling coating composition. The primer layer performs the function of compatabilising the substrate layer and any subsequent layers, i.e. the anti-fouling coating or any intermediate layer(s), in order to provide good adhesion. The primed film of the present invention exhibits improved adhesion in relation to known films. It is believed that the primer coating is more hydrophilic than known coatings and that this increases adhesion to the anti-fouling composition. It is not, however, intended that the invention be limited by this theory. The primed film of the present invention also exhibits excellent weatherability and UV stability.
DETAILED DESCRIPTION OF THE INVENTION
In a preferred embodiment, the composition of the present invention is suitable for improving adhesion between a polymeric film substrate, particularly a polyester film substrate, and a silicone-based anti-fouling composition, particularly one having a hydrophilic component therein.
In a preferred embodiment of the invention, the primer composition of the present invention is a dispersion of components (i), (ii) and (iii) in water. In an alternative embodiment, the composition is a solution or suspension of components (i), (ii) and (iii) in an organic solvent.
Preferably, component (i) is present in amounts from about 0.1 to about 15%, and preferably from about 2 to about 6%, by weight of the total solids present in the composition. Preferably, component (ii) is present in amounts of about 0.1 to about 10%, and preferably about 1 to about 5%, by weight of the total solids present in the composition. Preferably, component (iii) is present in amounts of about 0.01 to about 3%, and preferably about 0.2 to about 1%, by weight of the total solids present in the composition.
Preferred copolymers of component (i) are as follows.
The alkyl group of monomer (a) is preferably a lower alkyl group, for example an alkyl group containing up to six carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, terbutyl, and hexyl. Ethyl acrylate is a particularly preferred monomer (a).
The alkyl group of monomer (b) is preferably a lower allyl group, for example an alkyl group containing up to six carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, terbutyl, and hexyl. Methyl methacrylate is a particularly preferred monomer (b).
Monomer (c) containing a free carboxyl group, i.e. a carboxyl group other than those involved in the polymerisation reaction by which the copolymer is formed, suitably comprises a copolymerisable unsaturated carboxylic acid, and is preferably selected from acrylic acid, methacrylic acid, maleic acid, and/or itaconic acid; with acrylic acid and itaconic acid being particularly preferred.
The aromatic sulphonic acid monomer (d) may be present in the copolymer as the free acid and/or a salt thereof, for example as the ammonium, substituted ammonium or alkali metal (such as lithium, sodium or potassium) salt. The sulphonate group does not participate in the polymerisation reaction by which the copolymer is formed. The use of non-aromatic sulphonate-containing monomers can result in poor antistatic properties of the coated film, and also in destabilisation of the copolymer emulsion during polymerisation, rendering the water sensitivity of the copolymer unacceptable. The aromatic sulphonic acid polymer is preferably p-styrene sulphonic acid and/or a salt thereof.
Component (i) is preferably a copolymer comprising comonomers (a) 35 to 37.5 mole % alkyl acrylate, (b) 35 to 37.5 mole % allcyl methacrylate, (c) 10 to 15 mole % of a monomer containing a free carboxyl group, and (d) 15 to 20 mole % of an aromatic sulphonic acid and/or a salt thereof. A particuLlarly preferred copolymer comprises ethyl acrylate/ruethyl methacrylate/itaconic acid/p-styrene sulphonic acid and/or a salt thereof in a ratio of 35/35/15/15 mole %, and especially in a ratio of 37.5/37.5/10/15 mole %.
Campbell Jane Constance
Fujieda Yasuo
Lovatt Allan
Street Andrew
Takeuchi Hikaru
Chen Vivian
DuPont Teijin Films US Ltd. Partnership
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