GB2174315A

GB2174315A - Manufacture of pre-coated metal sheet

Info

Publication number: GB2174315A
Application number: GB08511308A
Authority: GB
Inventors: Derek John Crawford; John Robert Blower
Original assignee: COOPER COATED COIL Ltd
Current assignee: COOPER COATED COIL Ltd
Priority date: 1985-05-03
Filing date: 1985-05-03
Publication date: 1986-11-05
Also published as: EP0201268A2; DE3666000D1; GB8511308D0; ES8706484A1; ES554622A0; EP0201268B1; EP0201268A3; GB2174315B

Abstract

Pre-coated metal sheet for use in the manufacture of bakeware and other products intended to be used at high temperatures is first given a coating, on one or both sides, of a material, e.g. a lacquer, polyethylene sulphonate or a non-stick material, capable of withstanding temperatures of at least 250 DEG C, baked at 350-450 DEG C to dry the coating, and then has a printing medium compatible with the coating material applied to, and cured on, the coating as decoration. The sheet may be coiled between the coating and decoration steps, and may be coiled again after the decoration has been cured. Preferably the coating is applied by the reverse roll method and the decoration is printed on the coating by the forward roll method.

Description

1 GB 2 174 315 A 1

SPECIFICATION sulphonate (PES) for flame and very high

Improvements relating to pre-coated metal sheet temperature resistance, and non-stick materials suitable for use in the manufacture of bakeware and such as Fluon, Nuon, Teflon and Xylan (registered other products intended for use at high trade marks). Different coating materials may be temperatures 70 used on the two sides of the sheet. For example, for use in the manufacture of some bakeware products This invention relates to pre-coated metal sheet the side of the sheet which will be at the exterior of a suitable for use in the manufacture of bakeware and product may be coated with PES and the opposite other products intended for use at high side may be coated with a non- stick material.

temperatures, being metal sheet which is provided 75 The coating may be opaque, translucent or with a coated finish before the sheet is used in the metallic.

manufacture of such products. In general the examples of coatings mentioned Such pre-coated metal sheet is used in the will withstand usual pressing and forming production of bakeware and other products by operations to which the coated sheet may be various manufacturing methods including: 80 subjected in the manufacture of a product. PES and pressing; stamping; roll-forming and deep the non-stick materials will withstand more difficult drawings. It avoids the necessity of applying a forming and deep drawing operations. For extreme coated finish to the product after the manufacturing conditions of manufacture involving rough handling process which for some products can present and severe forming, or where the surface finish of a difficulties both in the application of a coated finish 85 product made from the coated sheet is particularly and in the obtaining of an acceptable finish. critical a protective strippable film, for example of Hitherto the pre-coated metal sheet which has polyethylene, may be applied to the coated sheet been produced for use in the manufacture of after the printing medium has been applied. That bakeware and other products intended for use at film will be removed afterthe product has been high temperatures has had a plain finish; it has not go formed.

had patterns, printing or other surface decoration on The printing medium which is applied to the it. The present invention provides pre-coated metal coating must be compatible with the coating sheet which has a surface decoration. material. Generally it will contain the same base According to the present invention there is constituent as the coating material although provided a process of producing pre-coated metal 95 concentrations of that constituent and of solvent sheet having a surface decoration and suitable for and pigment will vary to suit the application of the use in the manufacture of bakeware and other printing medium by the roller means.

products intended for use at high temperatures, Typically the coating will be applied to the sheet which process comprises the steps of cleaning a raw to a thickness of 0. 25 to 1.00 mm when the sheet is metal sheet, applying to at least one surface of the 100 of steel or upto 1.5 mm if the sheet is of aluminium, sheet by roller means a coating of a material and the printing medium will be applied to a capable of withstanding temperatures of 250'C or thickness which is about a quarter of that of the higher, baking the coated sheet at a temperature of coating.

350'C to 450'C to dry the coating, and applying as a The sheet may be of mild or stainless steel, decoration on the dried coating and printing 105 aluminium or its alloys, or possibly other metals, medium compatible with the coating, followed by including clad metals such as Hi-Top or aluminized curing to dry the printing medium and subsequent steel.

cooling. An embodiment of the invention will now be The coated sheet may be produced in flat form but described by way of example with reference to the preferably it is coiled. By applying the coating by the 110 accompanying drawings in which, reverse roll method, that is by having the roller Figures 1 and2 are schematic layouts respectively means and sheet moving in opposite directions of a coil-coating line for carrying out on strip metal where they make contact for the application of the sheet the coating stage of the process according to coating to the sheet, the deposition of the coating on the present invention, and a line for carrying out the the sheet can be closely controlled, which assists in 115 stage of applying the printing medium to the coated obtaining a good quality coated finish on the sheet. strip metal sheet, and - Applying the coating without opposition of Figure 3 is a plan view of a portion of the strip movement between the roller means and sheet is metal sheet after the printing medium has been possible but the deposition of the coating on the applied to it.

sheet maybe more difficult to control. 120 For convenience the process will be described as The printing medium may be applied by roller applied to the production of pre-coated steel or means or possibly by silk screen printing means. aluminium sheet in strip form which is intended to The coating may be applied to both sides of the be used forthe manufacture of bakeware products sheet. When the coating is applied to both sides the capable of withstanding high temperatures of 250C printing medium may also be applied to both sides 125 and higher.

or just to one of them, depending upon the Referring to Figure 1, raw steel or aluminium strip manufacture in which the coated sheet is intended 1, which initially is in a coil 2, is wound off the coil to be used. and taken through a series of tensioning rollers 3 to Some examples of suitable materials for the a degreasing station 4 at which a hot alkali coating are heat resistant lacquers, a polyethylene 130 clegreasing agent is sprayed on to the two sides of 2 GB 2 174 315 A 2 the strip to remove soluble foreign matter. From the other decoration, may be printed on the coated degreasing station 4 the strip passes between strip, as desired.

abrasive brushing rollers 5 which remove insoluble The resultant coated and printed strip is ready for contaminants from the strip. It then passes on to a 65 use in the manufacture of bakeware products by washing station 6 at which it is rinsed with hot water known pressing or other forming operations.

to wash away the alkali and contaminants loosened Instead of being coiled between the coating and by the brushing rollers 5. Next the cleansed strip has printing stages, the coated strip, after having been a chemical bonding agent applied to it by rollers 8 passed through the baking oven and cooled, could before entering an oven 7 where any moisture 70 pass directly on to the printing station for the remaining on the strip is driven off. From the oven application of the printing medium, and from there the strip is directed overvarious rollers 9 to a through the curing oven and further cooling station coating station 10 at which coatings are applied to before being wound into a coil.

both surfaces of the strip by respective sets of If a protective strippable film is required to be applicating rollers 11 and 12 which operate on the 75 added to the coated and printed strip before the reverse roll method. To one surface is applied a strip is subjected to the product manufacturing coating of PES (such as that supplied by Crown operations, the film may be applied to the strip by Decorative Products Limited under the name Crown rollers after the curing oven and the final cooling Nuon 500 which is solvent based and available in a station.

variety of colours), and to the other a coating of a 80

Claims

non-stick material such as one of those previously CLAIMS mentioned herein

is applied. Afterthe coating 1. A process of producing pre-coated metal sheet station 10 the strip is taken through a baking oven 13 having a surface decoration and suitable for use in at a peak oven temperature of 400-4300C for 60 the manufacture of bakeware and other products seconds to dry off solvents of the coatings and bake 85 intended for use at high temperatures, comprising the coatings. From the baking oven the coated strip the steps of cleaning a raw metal sheet, applying to passes through a cooling station 14 where it is at least one surface of the sheet by roller means a cooled by water jets before being taken through a coating of a material capable of withstanding series of rollers 15 and being wound back into a temperatures of 2WC or higher, baking the coated coil 16. 90 sheet at a temperature of 350-450'Cto drythe Each of the coatings on the strips is plain and coating, and applying as a decoration on the dried extends over the full surface of the side of the strip coating a printing medium compatible with the to which it is applied. coating, followed by curing to dry the printing For the next stage of the method reference is to be medium and subsequent cooling.

had to Figure 2 of the accompanying drawings. The 95
2. A process according to claim 1 wherein the coated strip is subsequently wound off the coil 16, coating material is a polyethylene sulphonate.

taken through tensioning rollers 17 and on by way
3. A process according to claim 1 or claim 2 of other guide rollers 18 to a printing station 19. At wherein the raw material sheet is wound from a coil the printing station 19 a printing medium is applied, prior to the cleaning step, and the coated sheet with for example as a decorative pattern, to the PES 100 the printing medium applied to it is wound into a coating of the strip by means of a suitably coil after the curing and subsequent cooling steps.

embossed roller 20 which operates on the forward
4. A process according to any preceding claim roll method, that is it is rotating in the direction of wherein the coated sheet is wound into a coil after movement of the strip, the speed of travel of the the baking and first- mentioned cooling steps, and is strip and the rotational speed of the roller being 105 subsequently wound off that coil for the application synchronised to ensure good definition in the of the printing medium.

pattern printed on the strip. A suitable printing
5. A process according to any preceding claim medium is that supplied by Crown Decorative wherein in the step of applying the coating to the Products Limited underthe name Crown Coilprint sheet the sheet is moved in a direction opposite to 500. From the printing station 19 the coated and 110 that in which the roller means is turning as it applies printed strip is taken through a curing oven 21 the coating to the sheet.

where the printing medium is cured. Typically when
6. A process according to any preceding claim Crown Coilprint 500 is applied as the printing wherein the printing medium is applied to the medium the strip is heated in the curing oven at a coating by roller means, the sheet being moved peak metal temperature of 400-43TC for 60 115 during the step of applying the printing medium in seconds. Upon leaving the curing oven 21 the the direction of rotation of the roller means.

coated and printed strip is cooled at a cooling
7. A process of producing pre-coated metal sheet station 22 by water jets and passed round a series of having a surface decoration, substantially as rollers 23 before finally being wound into a coil 24 described herein with reference to the again. 120 accompanying drawings.

A portion of the coated strip with the pattern
8. Pre-coated metal sheet made by the process as printed on it is shown in Figure 3. Other patterns, or claimed in any preceding claim.

Printed for Her Majesty's Stationery Office by Courier Press, Leamington Spa, 1111986. Demand No. 8817356. Published by the Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.