GB2307241A

GB2307241A - Plastic coating composition

Info

Publication number: GB2307241A
Application number: GB9523360A
Authority: GB
Inventors: Stephen Love
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-11-16
Filing date: 1995-11-16
Publication date: 1997-05-21
Also published as: GB9523360D0

Abstract

A coating composition able to provide a plastic coating on a keyed or keyable surface comprising a plastic solubilised in an organic solvent is described. Additives may be included. The coating composition is particularly suitable for coating wooden pallets. The composition may comprise acrylonitrile-butadiene-styrene copolymer, aluminium flake and acetone. A film may be made from the composition.

Description

PLASTIC COATING COMPOSITION The present invention relates to a plastic coating composition.

Plastic coatings are known on e.g. office furniture to provide a sealed top surface.

The plastic coatings can prolong the life of such items. However, such plastic coatings are applied by heat, chemical or adhesion processes such as ultra-violet curing.

According to one aspect of the present invention, there is provided a coating composition able to provide a plastic coating on a keyed or keyable surface comprising a plastic solubilised in an organic solvent.

The plastic may be any suitable plastic that is soluble in an organic solvent.

Preferably, the plastic is a styrene, e.g. polystyrene. More preferably, the plastic is acrylonitrile-butadiene-styrene (ABS). The plastic is such that it is reformed on the surface upon evaporation of the solvent. This is because the plastic is dissolved in the solvent.

The solvent may be suitable organic solvent; preferably ketones, esters and chlorinated solvents; more preferably acetone. Acetone is particularly suitable for the present invention due to its general and good solubilising ability, and its volatile nature allowing it to evaporate relatively quickly at ambient temperature. Acetone is also water tolerant such that a coating composition using acetone can be used to coat articles that are not totally moisture free; any water therein will not prevent the penetration of the coating composition into the surface.

The coating composition of the present invention may include one or more additives. The additive(s) are preferably soluble in the organic solvent used. Any insoluble additive(s) preferably have the same or a similar specific gravity as the plastic solution so that there is no settlement. One insoluble additive is aluminium flake (Al flake), which has a similar specific gravity to an ABS/acetone solution.

Because of its opacity, Al flake helps prevent instability of e.g. an ABS coating due to u-v degradation on exposure to (day)light. Many plastics are susceptible to light stability over time (e.g. brittleness).

The plastic coating is deposited and reformed on a surface following coating of the composition onto the surface and evaporation of the solvent. The bonding of the plastic to the surface is mechanical rather than chemical. For this the surface must be keyed or keyable, that is rough or roughened in some way to allow infiltration or penetration of the composition into or onto the surface. The plastic is thus able to bond to and around the working surface or interface. The keying process can include or be solublisation of the surface by the organic solvent. One particularly suitable surface is bare or rough wood, which has an open surface structure. The possible surface solubility action of the solvent also allows further coats of the plastic to be applied to existing coats (by resolubilisation of the existing top coat).

The coating created by the composition of the present invention is preferably non-stick, possibly by using a plastic which is otherwise known to be non-stick.

The coating composition of the present invention may include a plurality of plastics and/or a plurality of organic solvents when desired or necessary.

The amount of plastic in the solvent may be any suitable amount which still allows the coating composition to be coatable.

The coating composition may be applied by any suitable process, e.g. brush, spray, etc. Preferably, the composition is applied by dipping, that is dipping the surface or article to be treated into a tank of the coating composition. Any items, especially items of complex shape, can be dipped. Such items include pallets and fence posts.

According to a second aspect of the present invention, there is provided a process for coating an article with a plastic coating wherein the article is dipped into a tank of a coating composition comprising a plastic solublised in an organic solvent, removing the article from the tank and allowing the coating to dry.

Excess composition i.e. 'run off, can be drained back into the tank.

Alternatively, and especially in a continuous production line, the article is moved away from the tank to dry, but the (dried) plastic formed from any run-off from the article is reusable by resolubilisation in further solvent. When drying, the articles may be rotated to assist evenness of the coating drying thereon.

Examples of the present invention will now be described by way of example only.

EXAMPLE 1 The following coating composition was prepared 20% ABS 79% Acetone 1% Awl flake by admixing the starting materials. As the Al flake has a similar specific gravity to the ABS/acetone solution, there is little or no settlement.

The composition was placed in a tank, and a wooden pallet dipped into the tank. The open nature of the wood surfaces, notably in the case of rough timber, allows the composition to penetrate thereinto. Once removed from the tank evaporation of the acetone from the pallet allows the ABS to form a coating thereon, bonded by mechanically linking of the plastic with the wood surface. The coating is chemically stable and corrosion-resistant to weak and mild acids and alkalies. The coating is also flexible such that impacts and scratches do not break the coating; it deforms with the wood underneath.

Wooden pallets are robust, as required for the rough wear and tear they undergo. They are also relatively cheap (compared to plastic pallets), but they are unsuitable for use once contaminated, e.g. by fish spillage (due to health regulations).

The coating composition of the present invention improves both the chemical and mechanical wear and tear of the wooden pallets, increasing their possible length of use significantly. Coated wooden pallets thus have similar properties to plastic pallets.

Moreover, wooden pallets are often in need of repair or new sections. Once repaired or rebuilt, the pallet or that new part of it could then be coated as described above by dipping. Such a coat can be applied over a previous or any similar existing plastic coating as the acetone will resolubilise the top of the existing coating to create a working surface to which the new coating can bond. Prior coatings are not therefore problematic.

EXAMPLE 2 A coating composition having the same composition as that in Example 1 is poured onto a plastic sheet. Once the acetone has evaporated, a thin (e.g. several microns) but flexible film of ABS is produced. As the film is non-stick, it is easily removable from the polythene sheet.

The ABS film is a solid, flexible and stable sheet, created without chemical or heat processing.

Variations and modifications can be made without departing from the scope of the invention described above.

Claims

1 A coating composition able to provide a plastic coating on a keyed or keyable surface comprising a plastic solubilised in an organic solvent.

2. A coating composition as claimed in Claim 1 wherein the plastic is a styrene.

3. A coating composition as claimed in Claim 2 where the plastic is acrylonitrilebutadiene-styrene.

4. A coating composition as claimed in any one of Claims 1 to 3 wherein the solvent is a ketone, ester or chlorinated solvent.

5. A coating composition as claimed in Claim 4 wherein the solvent is acetone.

6. A coating composition as claimed in any one of the preceeding Claims wherein the composition includes one or more additives.

7. A coating composition as claimed in Claim 6 wherein any additive insoluble in the organic solvent has the same or a similar specific gravity as the plastic solution.

8. A coating composition as claimed in Claim 6 or Claim 7 wherein the additive is aluminium flake.

9. A coating composition as claimed in any one of the preceding Claims wherein the keyed or keyable surface is partially, substantially or wholly wood.

10. A coating composition as claimed in any one of the preceding Claims wherein the composition is non-stick.

11. A coating composition as claimed in any one of the preceding Claims wherein the composition includes a plurality of plastics and/or a plurality of organic solvents.

12. A coating composition able to provide a plastic coating on a keyed or keyable surface comprising 20% acrylonitrile-butadiene-styrene, 79% acetone and 1% aluminium flake.

13. A process for coating an article with a plastic coating wherein the article is dipped into a tank of a coating composition as claimed in any one of Claims 1 to 12, the article is removed from the tank and the coating allowed to dry.

14. A pallet having a plastic coating derived from a coating composition as claimed in any one or Claims 1 to 12.

15. A coating composition substantially as herein described with reference to the Examples.