GB2031301A

GB2031301A - Method of forming a texture pattern

Info

Publication number: GB2031301A
Application number: GB7931776A
Authority: GB
Original assignee: Fuji Photo Film Co Ltd
Current assignee: Fujifilm Holdings Corp
Priority date: 1978-09-20
Filing date: 1979-09-13
Publication date: 1980-04-23
Also published as: JPS6050511B2; JPS5541865A; GB2031301B; DE2935688A1

Abstract

A texture pattern is formed on a surface of a moving support 12 by simultaneously applying a first organic solvent-based coating liquid and a second, similar, but lower viscosity, liquid to form first and second coated film layers 14 and 15 respectively, which together constitute a texture pattern formation film 13, and drying the film 13. The layer 14 serves to control the thickness of the film 13 after drying to a required value, and the layer 15 promotes production of convection cells and determines the size of the cells according to its thickness and viscosity; a texture pattern having a desired surface roughness and a desired thickness is thus formed on the upper surface of the dried film 13. <IMAGE>

Description

SPECIFICATION Method of forming a texture pattern This invention relates to a method of forming a texture pattern on the surface of a belt-shaped support or the surface of a coating layer such as a sensitized layer, a coloring layer, a printing layer or the like which is formed on the surface of the belt-shaped support.

The term "texture pattern" as used herein is intended to generally represent a fine-grain surface, such as a silk surface, a cambric surface, a Linotype surface and a honey-comb surface. Such surfaces are observed when the surface of the support or the surface of the coating film is roughened so that the surface is free from glitter, fingerprints or scratches to make the surface suitable as a viewing surface, or when the surface is lubricative or is free from adhesion as the case may be. The texture pattern is completely different from a pattern formed by a plurality of parallel "grooves".

The following typical conventional methods are available for forming a texture pattern: 1. A method in which the surface of the support or the surface of the coating layer is mechanically roughened with an embossing roll is commonly employed.

2. A method in which the surface is physically and chemically roughened by utilizing convection which during the process of drying, causes disruption of a texture pattern formation film obtained by applying in the form of a single layer an organic solvent group coating liquid to the surface of the coating film.

The former method is disadvantageous in that, since a surface roughening device including the embossing roll must be additionally provided and the surface roughening process is accordingly added, the entire process becomes more complicated.

In the case of the latter method, which utilizes convection cells, it is possible to form the texture pattern efficiently when compared with the former method. In the single layer that is the texture pattern formation film made of the above-described organic solvent group coating liquid, the production of the convection cells, which are provided according to the local density and surface tension gradients attributed to the evaporation of the organic solvent or the like, is accelerated and the size of the convection cells is increased as the thickness of the texture pattern formation film is increased and the viscosity is decreased. However, the increment of the thickness of the texture pattern formation film is necessarily limited because of drying capacity.

Therefore, in order to increase the dried film thickness to more than a certain value, it is necessary to increase the concentration of the coating liquid. However, if the concentration of the coating liquid is increased, then its viscosity is also increased, with the result that it is rather difficult to produce the convection cells. Accordingly, the degree of roughness of the texture pattern and the thickness of the coated film are limited, and furthermore the roughness and the thickness are non-uniform and unstable.

Thus, the latter method suffers from various problems yet to be solved.

The inventors have conducted research on a method utilizing convection cells as in the latter method, to form a texture pattern having excellent uniformity and stability on the surface of the beltshaped support or on the surface of the coating film with the roughness and the thickness thereof selectable as desired in a wide range. The consequences of that research have resulted in this invention.

Accordingly, an object of the invention is to provide a texture pattern forming method in which all of the above-described difficulties accompanying a conventional method have been eliminated.

Another object of this invention is to define a texture pattern forming method where a texture pattern having a desired roughness is provided more uniformly and stably with a desired dried film thickness.

Still another object of this invention is to provide a texture pattern forming process which is as simple as possible.

The foregoing and other subjects of the invention has been achieved by the provision of a method of forming a texture pattern on a surface of a belt-shaped support or on the surface of a coating film applied in the form of a layer on the surface of the belt-shaped support, while continuously feeding the belt-shaped support. In this method, according to the invention, a first organic solvent group coating liquid having a relatively high viscosity and a second organic solvent group coating liquid whose viscosity is lower than that of the first organic solvent group coating liquid are applied simultaneously to the surface of the belt-shaped support or the surface of the coating film on the surface of the beltshaped support.

Application occurs in such a manner that a first coated film and a second coated film are provided in the form of double layers on the surface of the surface of the belt-shaped support or the surface of the coating film, respectively, thereby to provide a texture pattern formation film. During a process of drying the texture pattern formation film, the first coated film serves as an element to control the thickness of the texture pattern formation film to a value which is required when the texture pattern formation film has been dried, while the second coated film serves as an element to accelerate production of convection cells therein because of the low viscosity thereof and to determine the size of the convection cells from the thickness and viscosity thereof.Hence, the texture pattern is provided on the upper part of the dried texture pattern formation film in such a manner that the texture pattern has a desired surface roughness due to the convection cells and a desired thickness when the texture pattern formation film has been dried.

Now, this invention will be described with reference to its preferred embodiment shown in the accompanying drawings in which Fig. 1 is a schematic section showing a coating device for practicing a texture pattern forming method according to this invention; Fig. 2 is a sectional view showing a texture pattern formation film which has been coated on the surface of a support by the coating device according to the method of the invention; Fig. 3 is a sectional view showing a dried film 1 3' which is obtained by drying the texture pattern formation film 13 in Fig. 2; Fig. 4 is a sectional view of an instant print film unit with the dried film 13' shown in Fig. 3; and Fig. 5 is also a sectional view showing a modification of the texture pattern formation film according to the method of the invention.

The coating device 1 comprises a backing roll 2 which is rotated in the direction of the arrow CW at a constant speed, and an extrusion type coating unit 3. The extrusion type coating unit 3 has a pair of pockets 4 and 5 which are provided separately in the lower part and the upper part of the coating unit, respectively, and slots 6 and 7 which communicate with the pockets 4 and 5 at first ends, respectively and are opened to the atmosphere at second ends. Hence, three edges a, b and c of the coating unit 3 are defined. These three edges a, b and c are disposed at very short distances from the outer wall of the backing roll 2.

In the coating device 1 ,the backing roll 2 is rotated in the direction of the arrow OW while carrying a belt-shaped support 12 on its outer wall, so that the direction of advancement of the belt-shaped support 12 is changed at the position of the backing roll 2. First and second organic solvent group coating liquids are injected into the pockets 4 and 5 through different liquid delivering lines which are made up of pumps 8 and 9 and conduits 10 and 1 1, respectively. The two coating liquids are extruded through the slots 6 and 7, so that the liquids strike against the front surface of the support 12 in such a manner that one of the liquids is above the other in the space between the coating unit and the backing roll.More specifically, in this case, the first organic solvent group coating liquid extruded from the slot 6 is bridged onto the surface of the support 1 2 and a first film 1 4 is therefore coated with uniform thickness on the support 12 by the doctoring action of the edge b.

Furthermore, the second organic solvent group coating liquid extruded from the slot 7 bridges to the surface of the first film 14 leaving the edge b, and a second film 1 5 is coated with uniform thickness on the first coated film 14 by the doctoring action of the edge c.

The first and second coating liquid extruding positions, i.e., the outlets of the slots 6 and 7 are disposed vertically adjacent to each other. Therefore, the above-described two layer coating operations are simultaneously carried out without mixing the two coating liquids. As a result, a texture pattern formation film 13 is formed by the first and second coated films 14 and 15.

Fig. 2 is an enlarged sectional view of the texture pattern formation film 13 which has been formed on surface of the support 1. Fig. 3 is also an enlarged sectional view of the texture pattern formation film 13 which is dried, namely a dried film 13'. Fig. 4 is an enlarged sectional view of the aforementioned instant print film unit which is obtained by forming a photographing sensitized element layer 17 including an image receiving layer on one surface of the support 1 2 on the other surface of which the dried film 13' is formed.

According to the intended use of the instant print film unit, the support 12 must be transparent so that the image transferred through diffusion to the image receiving layer by subjecting the photographing sensitized element layer 1 7 to development can be observed through the support from the view surface side V opposite to the photographing sensitized element layer side. Accordingly, the support 12 is made of a plastics film 50 to 200y in thickness, such as a polyethylene terephthalate film, cellulose triacetate film, or the like.

The photographing sensitized element layer 17 is obtained by forming the image receiving layer, a light reflecting layer containing TiO2, etc., a light shielding layer containing carbon black, etc., and a sensitized layer in succession on one surface of the support 12. On the other surface of the support the texture pattern formation film 13, or the dried film 13', according to the invention is formed. The objects, structures and effects of these layers in the context of instant print film are described in detail in the specifications of U.S. Patent Nos. 3,362,821,3,594,1 65, 3,689,262 and 3,721,562.It is apparent from the object and structure of the texture pattern formation film 1 3 or the dried film 1 3' and from Figs. 2 through 4 that during the formation and the development, these layers are not affected by the texture pattern formation film 13 or the dried film 1 3' in chemical reaction and physical properties.

Therefore, the detailed description of the layers in the photographing sensitized element layer 1 7 will be omitted.

Each of the first coated film 14 and the second coated film 1 5 forming the texture pattern formation film 13 is a mixture of from 0 to 10% by weight of a thermoplastic resin, thermosetting resin, reaction type resin, or a mixture of two or more thereof and 90 to 100% by weight of organic solvent. If necessary, a matting agent, surface tension control agent or the like is added to the mixture.

Examples of the thermoplastic resin, having a softening temperature lower than 1 500 C, an average molecular weight 10,000-200,000, and a polymerization 2,000, are vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride copolymer, vinyl chloride acrylonitrile copolymer, acrylate acrylonitrile copolymer, acrylate vinylidene chloride copolymer, acrylate styrene copolymer, methacrylate acrylonitrile copolymer, methacrylate vinylidene chloride copolymer, methacrylate styrene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride acrylonitrile copolymer, butadiene acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivatives (such as cellulose acetate butylate, cellulose diacetate, cellulose triacetate, cellulose propionate, and nitrocellulose), styrene butadiene copolymer, polyester resin, amino resin, various synthetic rubber type thermoplastic resins (such as polybutadiene, polychloroprene, polyisoprene, and styrene butadiene copolymer), and mixtures of them.

The molecular weight of the thermoplastic resin or the reaction type resin is less than 200,000 when it is in the form of a coating liquid; however, it becomes infinite by reaction such as condensation or addition when added after coating and drying. It is preferable that the resin is not softened or molten before it is thermally decomposed.Examples of such a resin are phenol formalin novolak resin, phenol formalin resol resin, phenol furfural resin, xylene formaldehyde resin, urea resin, melamine resin, drying oil-modified alkyd resin, phenolic resin-modified alkyd resin, maleic acid resin-modified alkyd resin, unsaturated polyester resin, epoxy resin and hardener (polyamide, acid anhydride, polyamide resin, or the like), terminal isocyanate polyester moisture setting type resin, polyisocyanate prepolymer (a compound having at least three isocyanate groups in one molecule obtained by the reaction of diisocyanate with low molecular weight triol, trimer or tetra mer), resin having polyisocyanate prepolymer and active hydrogen (polyester polyol, polyether polyol, acrylic acid copolymer, maleic acid copolymer, 2-hydroxyethylmethacrylate copolymer, parahydroxystyrene copolymer, or the like), and mixtures of them.

Examples of the organic solvent used in coating are ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclo-hexanone; alcohols such as methanol, ethanol, propanol and butanol; esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate and glycol monoethyl ether acetate; glycoethers such as ether, glycol dimethyl ether, glycol monoethyl ether, and dioxane; aromatic hydrocarbons, such as benzene, toluene and xylene; and chlorinated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylenechlorohydrin and dichlorobenzene.

Examples of the matting agent are silica, polymethylmethacylate, butyl methacrylate glycidine copolymer and glycidine methacrylate butyl acrylate copolymer.

The surface tension control agent is, for instance, silicon oil. From 0.1 to 20 parts by weight of the matting agent and surface tension control agent are, in general added to the above-described resin 100 parts by weight.

The films 14 and 15 having the liquid compositions as described above can be set to the following different levels by selecting the mixing ratio of the resin to the organic solvent mainly for obtaining suitable viscosities thereof. That is, the viscosity of the coating liquid of the first film 14 is set to higher than 1 00 cp, while the viscosity of the coating liquid of the second film 1 5 is set within the range of 1-20 cp.

The texture pattern formation film 13 obtained by forming the first and second films 14 and 1 5 (as shown in Fig. 2) together with the support 12 is delivered continuously from the backing roll 2 to the drying stage (not shown). In the drying stage, evaporation of the organic solvent from the second film 1 5 is considerably accelerated to give local density gradient and local surface tension gradient to the latter 1 5. As a result, a number of convection cells are produced in the film 1 5; that is, a concaveconvex pattern 1 6 as shown in Fig. 3 is formed on the flat surface of the film as shown in Fig. 2.

The concave-convex patterns are left as the aforementioned texture pattern after the film 1 5 has been dried.

Similarly as in the case of the film 1 5, evaporation of the organic solvent from the first film 14 is also accelerated. However, since the viscosity of the coating liquid of the film 14 is more than five times as great as that of the coating liquid of the film 1 5 as described before, production of the convection cells therein is substantially suppressed although the organic solvent evaporates continuously from the film 14. Thus, after being dried, the second film 15 becomes a second coated film 1 5' having the texture pattern on its surface, while the first film 1 4 becomes a first dried film 14' obtained merely by condensation and drying. As a result, a dried texture pattern formulation film 13' is formed by the first and second films 14' and 15'.

The various layers of the above-described photographing sensitized element layer 17 are successively formed on the other surface of the support 1 2, which is opposite to the surface where the texture pattern formation film 13' has been formed, by using coating units such as an air knife, a slide hopper and an extrusion hopper, to provide the instant print film unit.

By exposing and developing the instant print film unit thus provided, the image is transferred through diffusion to the image receiving layer closest to the support 1 2, and can be viewed through the second dried film 1 5', the first dried film 14' and the support 12 from the view surface side V.

In viewing the image, the texture pattern 16 formed on the second dried film 15' reduces the optical reflection factor of the view surface V to protect the image from glittering. The provision of the texture pattern 16 allows the instant print film unit to be free from fingerprints, scratches and adhesion.

In order to satisfactorily view the image, the surface roughness of the texture pattern 1 6 may be such that the height is 2 to 8 y and the diameter of the convection cells is 300 to 100 y with respect to the thickness 10 to 20 y of the texture pattern formation film 1 3', preferably such that the height is 3 y and the diameter of the convection cells is of the order of 500 y.

Fig. 5 shows another exampler of the instant print film unit acording to the invention, which is different from the above-described one in the relative position of the dried texture pattern formation film 13' and the support 12. In the instant print film unit shown in Fig. 5, a coating film 18 such as a coloring layer, a printing layer or a sensitized layer, and a protecting film 19 provided on the coating film 18 are provided between the dried film 13 and the support 12. That is, the films 18, 19 and 13' are formed on one surface of the support 12. Therefore, the image or colors formed in the coating film 1 8 can be viewed through the protecting film 19, first dried film 14' and second dried film 1 5' without any interference caused by glitter of the view surface.

With the coating film 1 8 having stable properties, the protecting film 1 9 may be eliminated so that the texture pattern formation film 1 3' is formed directly on the surface of the coating film 18.

It is apparent that the support 12 may be an opaque one depending on its use.

The method of the invention described above has the following novel effects: 1. Since the viscosity of the coating liquid of the first coated film 1 4 is higher than the second coated film 15, production of the convection cells is suppressed, and accordingly the first coated film 14 serves as an element controlling the necessary thickness of the dried texture pattern formation film 13'.

It is possible to provide the dried texture pattern formation film 13' uniform in thickness by suitably adjusting the amount of the coating liquid.

2. Since the viscosity of the coating liquid of the second coated film 1 5 is made relatively low, the convection cells are readily produced therein. The height and diameter of the convection cells can be freely changed by suitably selecting the viscosity and the amount of coating liquid of the film 1 5.

Therefore, the texture pattern 16 having a desired surface roughness can be formed on the surface of the film 1 5 in a very wide range, substantially independently of the necessary thickness of the dried texture pattern formation film 13'.

3. In the method of the invention, unlike the conventional method in which the film thickness and surface roughness necessary for the formation of the texture pattern (16) are obtained by a single coated film, the film thickness and the texture pattern are obtained by the first coated film 14 and the second coated film 15, respectively. Therefore, the optimum conditions for stably producing the convection cells can be readily and correctly determined. As a result, the texture pattern 16 and its surface roughness are more uniform.

In order to clarifythe important effects of the method of the invention, an actual example and a comparison example will be described.

ACTUAL EXAMPLE A coating device as shown in Fig. 1 was used. While a support made of a polyethylene terephthalate film 100 #u in thickness was fed at a rate of 20 m/min.; the first and second coating liquids having the following compositions were applied in the form of double layers on the outer surface of the support. Then, these layers were dried by drying air at a temperature of 50 to 1 000C and at a blowing speed of 0.5 to 10 m/sec. to obtain a dried texture pattern formation film as shown in Fig. 3.

FIRST COATING LIQUID COMPOSITION Cellulose acetate 6 to 10 parts by weight Acetone 90 to 94 parts by weight Viscosity: 100 to 1 000 cp (Refer to Table 1 for details) Amount of coating: 110 to 230 cc/m2 (Refer to Table 1 for details) SECOND COATING LIQUID COMPOSITION Cellulose acetate 0 to 5 parts by weight Acetone 95 to 100 parts by weight Viscosity: 1 to 40 cp (Refer to Table 1 for details) Amount of coating: 10 to 60 cJm2 (Refer to Table 1 for details) COMPARISON EXAMPLE The same coating device as that in Actual Example was used (the pocket 4 and the slot 6 of the extrusion type coating unit, provided for forming the first coated film 1 4, being used).A coating liquid having the following composition was applied on the outer surface of a support similar to that in Actual Example to obtain a single layer which was a dried texture pattern formation film. The coating rate and the drying conditions were the same as those in the Actual Example.

LIQUID COMPOSITION Cellulose acetate 5 to 7 parts by weight Acetone 93 to 95 parts by weight Viscosity: 50 to 200 cp (Refer to Table 1 for details) Amount of coating: 120 to 200 cc/m2 (Refer to Table 1 for details) The following are apparent from Table 1: 1. Even when the amount of coating liquid for the first coated film is changed with the viscosity and the amount of coating liquid for the second coated film maintained unchanged, the diameter and height of the convection cells are maintained unchanged with excellent uniformity, as is clear from Samples 1,2 and 3 in Actual Example.

2. When the amount of coating liquid for the second coating film is changed, the diameter and height can be changed, with the thickness of the dried film maintained constant (10 O FL), as is clear from Samples 1,4 and 5 in Actual Example.

3. When the viscosity of the coating liquid for the second coated film is changed, the diameter and height can be changed, with the thickness of the dried film maintained constant (10 y), as is apparent from Samples 1,6 and 7 in Actual Example.

4. With the single layer, it is impossible to control the configuration of the convection cells and the thickness of the dried film independently of each other, and the conditions for forming the texture pattern is strictly limited, as is clear from Samples 1 through 5 in Comparison Example.

Table 1 Condition

2nd coated film tst coated film Amount of Amount of Viscosity coating liquid Viscosity coating liquid (cp) (cc/m ) (cp) (cc/m ) Actual Example Sample- 1 5 50 350 140 2 5 50 , . 120 3 5 50 " 160 4 5 40 " 140 5 5 60 6 3 50 7 10 50 8 20 50 ,. ., 9 40 50 10 1 10 1000 110 11 5 50 100 230 Comparison Example Sample- 1 / 50 200 2 / " 160 3 ,1 120 4 / 100 180 5 / 200 160 Table 1 (continued)

Thickness of Texture pattern surface roughness dried texture pattern for- Convection cell Uniformity mation film diameter Height (visually (F1) (cc) (it) determined) Actual Example Sample- 1 10 500 3 o 2 8 " 3 12 " 4 10 300 2 5 " 600 5 6 " " 7 " 300 2 8 11 200 1 A 9 11 - No co vection ce formed 10 10 300 2 o 11 10 700 6 α Comparison Example Sample- 1 10 - ~ x 2 8 800 7 o 3 6 500 3 o 4 10 - ~ x 5 " - - No convection cell formed.

Note: In the uniformity visual determination result, mark (o) designates "Satisfactory", mark (#) "Rather poor", and mark (x) "Unsatisfactory".

Claims

1. A method of forming a texture pattern on a surface of a support or of a layer coated thereon while continuously feeding said support for coating, comprising the steps of simultaneously applying a first organic solvent group coating liquid and a second organic solvent group coating liquid, whose viscosity is lower than that of said first organic solvent group coating liquid, to said surface to form thereon first and second coated film layers which together constitute a texture pattern formation film, and drying, said first layer serving to control the thickness of said film after drying to a required value, and said second layer serving to promote production of convection cells and to allow their size to be determined according to its thickness and viscosity, whereby a texture pattern having a desired surface roughness and a desired thickness may be provided on the upper surface of the dried film.

2. A method as claimed in Claim 1, wherein said surface is a surface of a belt-shaped support.

3. A method as claimed in Claim 1, wherein said surface is a surface of a layer of coating film applied to a belt-shaped support.

4. A method as claimed in any preceding claim, wherein said first and second organic solvent group coating liquids contain one or more of thermoplastic resin, thermosetting resin and reaction type resin.

5. A method as claimed in Claim 4, wherein said thermoplastic resin has a softening temperature lower than 1 500 C, an average molecular weight of from 10,000 to 200,000, a polymerization degree of from 200 to 2,000 and is selected from vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride copolymer, vinyl chloride acrylonitrile copolymer, acrylate acrylonitrile copolymer, acrylate vinylidene chloride copolymer, acrylate styrene copolymer, methacrylate acrylonitrile copolymer, methacrylate vinylidene chloride copolymer, methacrylate styrene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride acrylonitrile copolymer, butadiene acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivatives, styrene butadiene copolymer, polyester resin, amino resin and synthetic rubber type thermoplastic resins.

6. A method as claimed in Claim 4 or 5, wherein said resin is selected from phenol formalin novolak resin, phenol formalin resol resin, phenol furfural resin xylene formaldehyde resin, urea resin, melamine resin, drying oil-modified alkyd resin, phenolic resin-modified alkyd resin, maleic acid resinmodified alkyd resin, unsaturated polyester resin, epoxy resin and hardener, terminal isocyanate polyester moisture setting type resin, terpolyisocianate prepolymer and resin having polyisocyanate prepolymer and active hydrogen.

7. A method as claimed in Claim 4, 5 or 6, wherein said first and second organic solvent group coating liquids each comprise a mixture of from 0 to 10% by weight of thermoplastic resin, thermosetting resin, reaction type resin or a mixture thereof and from 90 to 100% by weight organic solvent.

8. A method as claimed in any preceding claim, wherein said organic solvent is selected from ketones, alcohols, esters, glycolethers, aromatic hydrocarbons, and chlorinated hydrocarbons.

9. A method as claimed in any preceding claim, wherein said liquids further comprise a matting agent.

10. A method as claimed in Claim 9, wherein said matting agent is selected from silica, polymethylmethacylate, butyl methacrylatre glycidine copolymer and glycidine methacrylate butyl acrylate copolymer.

11. A method as claimed in Claim 9 or 10, wherein said matting agent is present in an amount of from 0.1 to 20 parts by weight per 100 parts by weight of resin.

1 2. A method as claimed in any preceding claim, wherein said liquids further comprises a surface control agent.

13. A method as claimed in Claim 12, wherein said surface control agent is silicon oil present in an amount of from 0.1 to 20 parts by weight per 100 parts by weight of resin.

14. A method as claimed in any preceding claim, wherein the viscosity of said first liquid is greater than 100 cp and the viscosity of said second liquid is from 1 to 20 cp.

1 5. A method as claimed in any preceding claim, wherein said surface is that of a plastics film of a thickness of from 50 to 200 #.

16. A method as claimed in any preceding claim, wherein said texture pattern formation film has a thickness of from 10 to 20 #, the convection cells are from 300 to 1,000 ju in diameter and the pattern height is from 2 to 80 FL.

17. A method as claimed in Claim 16, wherein said convection cells are 500 ju in diameter and the pattern height is 3 y.

18. A method as claimed in Claim 1 and substantially as herein described.

19. A method of forming a texture pattern on a surface, substantially as herein described with reference to Fig. 1, and Figs. 2 and 3, Fig. 4 or Fig. 5 of the accompanying drawings or to the example of the invention.

20. A support having a texture pattern formed on a surface thereof, or of a layer coated thereon, by a method as claimed in any preceding claim.

21. The features as herein disclosed or their equivalents, in any novel selection.