GB2078614A

GB2078614A - Decoration of articles

Info

Publication number: GB2078614A
Application number: GB8119664A
Authority: GB
Original assignee: Wedgwood Josiah & Sons Ltd
Current assignee: Wedgwood Josiah & Sons Ltd
Priority date: 1980-06-27
Filing date: 1981-06-25
Publication date: 1982-01-13

Abstract

A method of decorating an article such as an article of ceramic biscuit ware comprises providing a decoration layer and a flexible film of material having the property of adhering directly to the surface of the article at or above the softening temperature of the film material, applying the decoration layer and film to a surface of the article heated to or above the softening temperature of the film material such that the film will cling to the surface, and subsequently subjecting the surface to a firing process to decompose the film and fuse the decoration layer to the surface. The preferred film material is an ethylene oxide homo- or co- polymer.

Description

SPECIFICATION Decoration of articles This invention relates to the decoration of articles and is particularly but by no means exclusively applicable to the decoration of ceramic articles.

Existing methods of decorating ceramic articles by application of decals or transfers suffer from a number of disadvantages. Conventional so called "water-slide" decals or transfers consist of a backing sheet coated with a water soluble gum and supporting upper and lower protective films between which is deposited the pattern or design to be applied to the article. The operative requires to apply moisture to the transfer to release the pattern and protective films from the backing sheet and then position the released elements on the surface of the articles to be decorated in an appropriate position. Care is necessary to ensure that creases or wrinkles do not develop and that air bubbles are not trapped between the surface and the transfer. The operation is time-consuming and laborious and largely dependant on operator skill.

Alternative forms of transfer have been proposed in which the pattern is supported on a backing sheet of release paper and is protected by a cover coat of a nature which permits the cover coat and pattern to be peeled from the backing sheet and applied to the surface.of the ware without requiring wetting, but it is then necessary to dissolve the cover coat by use of an organic solvent which presents health and fire hazards apart from requiring supplies of the appropriate solvent to be stocked.

It is an object of the present invention to provide a means of decorating products by application of transfers which obviates or mitigates these disadvantages of previous proposals.

According to one aspect of the invention there is provided a decorating product in which a pattern or decoration to be applied to a surface of an article to be decorated is supported on a flexible carrier film of a material having the property of adhering directly to the surface of the article at or above the softening temperature of the film material and which will burn off without interfering with the pattern or decoration when the article is fired. Where the surface is glazed the film material must also be such that it will burn off without interfering with the glaze.

Preferably the film is a polymeric material which is hydrophilic, is capable of being formed into a film which exhibits little or no shrinkage on softening and is substantially entirely decomposed on heating into volatilisable material.

According to a further aspect the invention provides a decorating product comprising a pattern or decoration layer of a decorating medium which will withstand ceramic firing temperatures and a flexible film of ethylene oxide polymer. The polymer may be a homopolymer or a co-polymer of ethylene oxide.

The ethylene oxide polymer may be applied in solution to a support surface to which the decoration has been applied whereby to form a film which can subsequently be peeled from the support surface together with the decoration and applied to the article to be decorated. Alternatively the ethylene oxide polymer may comprise a preformed film on to which the desired decoration is printed by any suitable means, following which the film bearing the decoration is applied to the surface of the article to be decorated.

In the case of decoration of ceramic products it is envisaged that decoration supported on a film of ethylene oxide polymer may be applied to the surface of articles to be decorated at any stage during their production, that is either in the "green" clay state, in the partly fired "biscuit" state, in the "raw glazed" state or after glaziny and firing.The manner of application will vary dependant on the nature of the surface concerned, but in one particular technique for use in relation to articles which have been fired to the biscuit state and coated with a glaze medium which has then been allowed to dry, the surface of the article to be decorated is raised to a temperature at or above the softening point of the polymer prior to application of the transfer and this has been found to cause the transfer to "cling" to the surface of the article until the film is volatilised during subsequent firing.

Thus the invention also provides a method of decorating an article comprising providing a decoration layer on a flexible film of material having the property of adhering directly to the surface of the article at or above the softening temperature of the film material, applying the decorating layer and film to a surface of the article heated to or above the softening temperature of the film material such that the film will cling to the surface, and subsequently subjecting the surface to a firing process to decompose the film and fuse the decorating layer to the surface.

Preferably the film comprises an ethylene oxide polymer. Preferably also the surface of the article comprises a ceramic body fired to the "biscuit" state and coated with a raw glaze medium, the pattern or decoration layer comprising a decorating medium which will withstand ceramic firing temperatures in the region of 900-1 3000C and the film material being selected to burn off the raw glazed surface without interfering with the glaze.

In carrying out this particular embodiment of the invention, a paper sheet having one surface coated with a silicone, polythene or other suitable release medium may be used as a support for a pattern or decoration which is applied to the coated surface of the sheet by screen printing or other suitable printing technique. Ethylene oxide polymer which may be in powder form is dissolved in a suitable solvent such as anisole (phenol methyl ether) and is then screened or otherwise applied to the surface of the support sheet to form a cover coat extending over and protecting the decoration. Preferably the solution is applied using a relatively coarse mesh screen at a temperature above 200 C. At about this temperature anisole solutions of polyethylene oxide precipitate to give a creamy suspension.Application of this cream using a relatively coarse screen facilitates the elimination of small bubbles which tend to form using a normal solution and a fine mesh screen.

The resulting product is dried at a temperature of around 50-700C causing the solvent to evaporate thereby depositing the ethylene oxide polymer in the form of a protective film or cover coat.

The transfer so produced may be used to decorate a ceramic article in the biscuit state to which a glaze coating has been applied and allowed to dry to form so called "raw" glaze. The surface of the article is heated to a temperature at or above the softening point of the polymer, generally in the range 65-11 00C and preferably around 700C. Temperatures higher than 11 OOC could be used but the difficulty of handling hot ware gives a practical limit of about 11 OOC and the polymer might soften before contact with the surface which could cause distortion. The polymer cover coat is peeled from the backing sheet as a result of which the decoration becomes detached from the backing sheet and remains attached to the cover coat which may then be applied to the surface of the article.The ethylene oxide polymer is softened on contact with the surface and thereby adapts itself to the surface of the article and "clings" to the surface without requiring rubbing down or similar operations and the article is then fired in a conventional manner in a furnace or kiln. This results in vitrification of the glaze coating to form a glazed surface on the article, the ethylene oxide polymer film decomposes leaving the decoration embedded in the vitrified glaze coating.

In an alternative technique the pattern to be applied to the article may be printed directly on to a pre-formed film of ethylene oxide polymer suitably supported and maintained against distortion during the printing operation. The film may, for example, be supported on a carrier sheet of polyester or other suitable material, following which the ethylene oxide polymer sheet may be cut into suitable sections for direct application to the article to be decorated.

Different grades of ethylene oxide polymer are available commercially which vary as regards their molecular weight. For the purpose of the invention it is preferred that the film forming solution of ethylene oxide polymer should have relatively low viscosity and relatively high solids content.

Ethylene oxide polymer having a molecular weight in the region of 100,000 has been found in experiments to produce the most satisfactory results.

It is desirable to subject the article to a rapid rise in temperature during firing. This is especially so in the case of upright articles which if heated slowly can result in distortion of the decoration.

Distortion can also arise from use of an ethylene oxide polymer film which does not have balanced shrinkage in the longitudinal and transverse directions. The method of manufacture of some films results in substantial differences in longitudinal and transverse shrinkage and this can result in distortion of the design during firing.

Exact balance of shrinkage is not however essential as satisfactory results can be obtained' provided the differential shrinkage is not unduly great. It should be appreciated also that fillers or other materials may be incorporated in the ethylene oxide polymer coating in order to produce background, colour or other benefits.

Care is necessary in the selection of a solvent for the ethylene oxide polymer to avoid over rapid evaporation at the transfer drying stage which could result in formation of blisters or bubbles in the film. Moreover in the case where the film is applied to the transfer by screen printing solvent evaporation could cause blocking of the screen.

Preferably the solvent should have a low vapour pressure at room temperature and give stable solutions of the polymer at room temperature.

In most cases satisfactory results can be obtained using as solvent ethylene dichloride either alone or mixed with cellosolve acetate but great care is required to avoid the above problems.

The preferred solvent for the ethylene oxide polymer is anisole (phenol methyl ether) which has a boiling point of 1 540C. Ethylene oxide polymer is soluble in anisole at room temperature and satisfactory cover coats using this solvent have been applied to silicone release paper by screen printing. It will be appreciated however that any solvent may be used to form the ethylene oxide polymer film-forming solution provided it meets the above criteria and is not toxic or otherwise harmful or dangerous to operatives.

The following is an example of one embodiment of the invention given by way of illustration only.

EXAMPLE A pattern to be applied to an article of ceramic ware was screen printed on to the coated surface of a silicone release paper (such as Paper No.

001 51 5 of Sterling Coated Materials Limited of Duckinfield, Cheshire) which acted as a support.

Ethylene oxide polymer of molecular weight 100,000 in powder form was dissolved in anisole.

preferably at a temperature above 400 C, to form a solution having a solids content of 30-40% by weight and a viscosity of approximately 20 poises, and then applied to the surface of the printed support sheet for form a film-like coating extending over and protecting the pattern. The product was then dried at a temperature of 50-850C causing the solvent to evaporate, the resultant film forming a cover coat over the pattern. The surface of the article of ware was coated with a glaze medium and heated to approximately 700C and the ethylene oxide polymer film was then peeled from the release paper.The pattern came away from the release paper with the film and the polymer carrier sheet was applied to the heated surface of the article with the sheet uppermost so that the pattern was trapped between the surface and the film. The film "clung" to the surface of the article and adapted to its contours without requiring to be rubbed down and thereafter the article was fired at a conventional firing temperature of 1 500 C. The ethylene oxide polymer film decomposed, and the glaze became vitrified leaving the pattern embedded in the vitrified glaze coating.

While reference has been made above to the decoration of ceramic articles it should be appreciated that the invention is applicable to the decoration of a wide range of other articles including articles made of metals, plastics or other materials. When decorating articles of pottery in the unfired "green" state it has been found desirable to first coat the surface to be decorated with a glaze medium which is allowed to dry before application of the transfer according to the invention. This assists adherence of the transfer and reduces or eliminates formation of bubbles in the glaze. Moreover while ethylene oxide polymer is the preferred film forming material, other film forming materials may be utilised provided they have the requisite properties of attaching themselves directly to the surface of the article to be decorated and decomposing on subsequent firing of the article. Where polymers of ethylene oxide are utilised they may be homopolymers or corpolymers with perhaps up to 10% by weight of comonomer.

Claims

1. A decorating product comprising a pattern or decoration layer and a flexible film of a material having the property of adhering directly to the surfaces of an article at or above the softening temperature of the film material and which will burn off without interfering with the pattern or decoration when the article is fired.

2. A decorating product according to claim 1 wherein the pattern or decoration layer comprises a decorating medium which will withstand ceramic firing temperatures.

3. A decorating product according to claim 1 or 2 wherein the film material will burn off the surface of a glazed article without interfering with the glaze.

4. A decorating product according to claim 1, 2 or 3, where the film comprises a polymeric material which is hydrophilic, is capable of being formed into a film which exhibits little or no shrinkage on softening and is substantially entirely decomposed on heating into volatilisable material.

5. A decorating product comprising a pattern or decoration layer of a medium which will withstand a firing temperature of 900-1 3000C and a flexible film of a polymeric material having a softening temperature of 65-11 00C and having the property of adhering directly to the surface of an article without substantial shrinkage at or above the softening temperature, the film material being substantially entirely decomposed into volatilisable material at a temperature of 900-1 3000C whereby to leave the pattern or decoration layer fired to the surface of the article.

6. A decorating product according to claim 4 or 5 wherein the film comprises ethylene oxide polymer.

7. A decorating product comprising a pattern or decoration layer of a decorating medium which will withstand ceramic firing temperatures and a flexible film of ethylene oxide polymer.

8. A decorating product according to claim 6 or 7 wherein the polymer is a homopolymer of ethylene oxide.

9. A decorating product according to claim 6 or 7 wherein the polymer is a copolymer of ethylene oxide.

10. A decorating product according to any of claims 6 to 9 wherein said ethylene oxide polymer has a molecular weight in the region of 100,000.

11. A decorating product according to any of claims 6 to 10 wherein the ethylene oxide film has substantially balanced shrinkage in the longitudinal and transverse directions.

12. A decorating product according to any preceding claim which consists solely of said pattern or decoration layer supported on said film.

1 3. A decorating product according to any of claims 1 to 11 wherein said pattern or decoration layer is releasably supported on a carrier sheet and covered by said film.

14. A decorating product according to claim 13 wherein said carrier sheet comprises release paper.

1 5. A decorating product according to any preceding claim wherein said film incorporates a filler material.

1 6. A decorating product substantially as hereinbefore described in the foregoing Example.

1 7. An article when decorated using a decorating product according to any preceding claim.

1 8. A method of decorating an article comprising applying to a surface of the article a decorating product according to any of claims 1 to 1 6 following heating of the surface of the article to or above the softening temperature of said film material.

1 9. A method of decorating an article comprising providing a decoration layer on a flexible film of a material having the property of adhering directly to the surface of the article at or above the softening temperature of the film material, applying the decorating layer and film to a surface of the article heated to or above the softening temperature of the film material such that the film will cling to the surface and subsequently subjecting the surface to a firing process to decompose the film and fuse the decorating layer to the surface.

20. A method according to claim 19 wherein the article comprises a ceramic body fired to the biscuit state and coated with a raw glaze medium, the pattern or decoration layer comprising a decorating medium which will withstand ceramic firing temperatures and the film material being selected to burn off the raw glazed surface without interfering with the glaze.

21. A method according to claim 19 or 20 wherein the film comprises a polymeric material which is hydrophilic, is capable of being formed into a film which exhibits little or no shrinkage on softening and is substantially entirely decomposed on heating into a volatilisable material.

22. A method according to claim 21 wherein the film comprises ethylene oxide polymer.

23. A method according to any of claims 19 to 22 wherein said film is formed by applying a solution of film forming material to 9 support surface to which the decoration has been applied whereby to form a film which can subsequently be peeled from the support surface together with the decoration and applied to the article to be decorated.

24. A method according to claim 23 wherein the solution comprises the film forming material dissolved in anisole.

25. A method according to claim 24 wherein the solution is applied to the decorated supported surface by screening.

26. A method according to claim 25 wherein the solution is screened at a temperature in the region of 200C using a coarse screen to prevent the formation of bubbles.

27. A method according to any of claims 23 to 26 wherein the resultant product is dried to evaporate the solvent.

28. A method according to claim 27 wherein drying is effected at a temperature 6f 50-850C.

29. A method according to any of claims 19 Lo 22 wherein said film is a pre-formed film on to which the pattern or decoration layer is printed.

30. A method according to claim 29 wherein the film is supported on a carrier sheet during printing.

31. A method according to any of claims 19 to 30 wherein the film has a molecular weight in the region of 100,000.

32. A method according to any of claims 1 9 to 31 wherein the film has substantially balanced shrinkage in the longitudinal and transverse directions.

33. A method of decorating an article substantially as hereinbefore described.

34. An article decorated by a method according to any preceding claim.

35. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.