IL35205A - Embossing rollers and method for their production - Google Patents

Description

The present invention' relates to a new and improved: embossed roller,, plate or die which is ob-tained by eloctropolishing the surface of an engraved, roller in order to enhance the sharpness of the features of the engraving, electroplating a deposit of a suitable metal having a high or medium^ levelling. effect, such as copper, over the entire surface of the roller and a second plating with a metal having a lesser : levelling effect such as chromium, as a finishing coating. The new and improved , oller thus obtained ' is capable of reproducing fine and delicate designs from an original pattern 'thereby providing high fidelity in the reproduction operation.

DESCRIPTION OP THE PRIOR ART For many years, the embossing industry has searched for new methods and procedures to create and reproduce faithfully, embossing and graining rollers, plates or dies so as to impart, on suit-able substrates such as paper, leather, artificial leather, synthetic materials such as thermoplastic materials, synthetic fibers, vinyl fabrics, metal foil, and the like, relief patterns or textures of the highest quality and appearance. Unfortunately, these attempts have met with limited success since the copy or result is not generally as detailed or as fine a high fidelity reproduction as desired.

Thus, details of objects of nature such as leaves, flowers, etc. become obscure or obliterated, or, in other instances, in reproducing smooth-sur face articles such as kidskin or patent leather, the copy is not as smooth or the texture is not of the quality comparable to the original material. In many instances, additional steps are required such as, for example, buffing or other finishing steps but even such added efforts do not create a repro-duction comparable to or simulating the texture, appearance, or quality of the original material.

When relatively minute details are involved, reproductions are most unsatisfactory.

Conventional procedures whereby the industry attempted to impart embossing effects on different materials included, for example, machine engraving and electroforming . Machine engraved embossing rollers do not however possess the surface finish quality which is required,, for instance, to impart the brilliance and richness of fine leather grains on vinyl fabric material. Electroforming , on the other hand, has not yet developed the mold-making technique that would assure a successful and accurate reproduction of a seamless embossing roller or cylinder which is required to emboss faithfully the delicate grains on vinyl fabrics. Up to the present time, it was not. possible to reproduce faithfully embossing and graining plates to impart on substrates such as paper, leather, artificial leather, plastics, metal foil, and the like, relief patterns or textures of a high and delicate quality.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a new and useful procedure for modifying embossing rollers, plates or dies so as to produce articles having the desired surface patterns or designs which are characterized by exceptional fidelity in every dimension. Using the modified roller of the present process there is obtained a reproduction so accurate and complete in every detail that it is difficult to distinguish the reproduction from the original design. The reproduction is so faithful that even "weavers' imperfections" are duplicated with exact fidelity 4 when the master original involves a cloth or like material. The embossing roller obtained by the process of the present invention can thus reproduce articles so faithfully that there is scarcely any limitation with respect to the type of design or pattern which the master original may have. Any conventional design or any new design or pattern found in nature or made by man, in whatever fashion, can be reproduced not only in appearance but also in feel and textural reflexion. The modified embossed roller obtained by the process of this invention may also reproduce, in a 2- or 3- dimensional configuration, any design or pattern such as that found on the surface of a drapery material, upholstery, table-cloth fabric, leather, reptile or animal skin, wood, tapestry, carpeting, crinkle foil, linoleum, and the like .

In accordance with the process of the present invention, there is obtained a new and improved embossed roller by subjecting a machine engraved or electroformed roller to a combination of steps invo.lv- ing (1) an electropolishing step followed by (2) a bright metal plating step with a metal characterized by a high or medium levelling effect, to produce a combined brightening and smoothing effect on the roller. Illustrative metals are copper, iron, nickel, and the like. There is thus obtained a deposit a metal having the aforesaid smoothing and brightening effect over the entire surface of the embossing roller. This is followed by (3) a second plating step which is used as a finishing coating for the roller and the second plating is suitably effected by the use of a metal having a relatively lower levelling effect such' as chromium or nickel. The second plating step provides a hard coating surface which is resistant to corrosion and erosion while at the same time enhancing 35205/2 - 9 - ■ the textured pattern of the end desired product. 1 The order of the aforesaid steps is not J critical as the electroplating with a metal having a low levelling effect can precede the electroplat -ing step wherein a metal having a high levelling effect is used. These steps can then be followed by the electropolishing step. ( Planographic printing plates comprising a base sheet, a first ink adhering smooth layer of copper bonded to the base sheet and having an outer smooth^chromium > protective layer, are known in the printing art, e»g. from US Patent Specification No. 3,280,736. The printing art, while similar to some degree to the engraving or ' i \ embossing art of the present invention, has different requirements and is therefore not; analogous in many critical respects. For example, in the printing art it is most desirable, if not essential, to have sharp, well defined edges on the surfaces of the printing cylinder. This means ' that a rough surface with peaks, ridges, and recesses is 1 undesirable (note particularly, column 1, line 58 to column :2 line 18 of US Patent 3,280,736). In direct contrast to the ( aforenoted teachings of US Patent 3,280,736 showing that rough surfaces are undesirable in the printing art, this is I exactly what is desired in the instant invention. The printing art requires smooth surfaces comprised of letters or characters having perpendicular or undercut edges whin are capable of transferring ink to the paper without smearing or unevenness. This is true whether the technique employed is intaglio, offset, planographic or otherwise. In the engraving art, as discussed earlier, sharp, well defined edges are not desired. In particular, with respect to reproducing leather grains , the surface must contain the abnormalities or unevenness of the leather itself. Con-sequently, perpendicular edges that are suitable for printing rollers would be entirely unsuitable for engraving leather grains. Therefore, since US Patent 3,280,736 relates to the printing art rather than t*¾ engraving art, and uses an approach in direct contrast to that of U instant invention, its teachings would not have been applied to the p roblems J solved by the present invention. j The shape and configuration of the embos- 1 sing rollers, plates or dies employed in conjunction '| ■Ί with the new method of the present invention is not critical and it is to be understood that any roller, plate or die of practically any shape suitable for imparting the desired grain or texture to the material which is to be embossed is acceptable for use in conjunction with the present process. The roller, plate o die can be made of a wide variety of materials including ferrous or non-ferrous metals such as aluminum and aluminum alloys. The advantages of aluminum rollers are that such rollers are characterized by better heat transfer, easier machining and less weight than steel rollers.

Further, it is also possible to utilize effectively plastic rollers having a metal coating on the surfac and illustrative plastic rollers are those fabricated from polyvinyl chloride, rigid urethanes, and the like.

The procedures used in engraving embossing rollers, dies, plates and the like, are conventional and the particular method employed for engraving is not critical to the success or operabil ity of the present process. Thus, the embossing rol lers, plates or dies, can be engraved by many procedures and illustratively, by hand, by machine, chemical or photochemical techniques.

Using the present procedure, quite surprisingly, it is now possible to obtain a modified rolle plate or die which can successfully impart a natural grain to paper, aluminum foil, synthetic materials such as polypropylenes , urethanes, cellulose, synthetic fabrics, and the like, and even to a material such as wood. Surprisingly, the modified rollers obtained by the present process can be applied to any material that can be embossed whether such material is a synthetic or a natural substance. Thus, for example, modified rollers of the present process when applied, for example, to the reproduction of kidskin, the resulting product is characterized by a glossy and shiny brilliance, an excellent "feel" or "touch"; the product looks like a skin which has actually been blended in.

Where an electropolishing step was used, in prior procedures, in an attempt to improve the appearance of products obtained by conventional embossing rollers, there was some improvement in the appearance of the product but still, where an attempt was made, for example, to simulate the appearance of natural leather, the resulting electropolished product still did not possess the desired gloss, shiny brilliance or "touch" of natural leather. Furthermore, such electropolished products also did not possess the desired fine figures or details characterizing the natural kid- skin.

The present invention accordingly represents an important improvement in the art since it avoids the disadvantages associated with the use of conventional embossed rollers. The new and improved process of the present invention involves a combination of steps including (1) electropolishing the embossed roller, modifying the roller with (2) a bright metal plating and (3) a second metal plating step. In the first plating step, the metal used is generally ductile and bright having a high or medium levelling effect on the surface of the roller. Suitable metals include for example, copper, nickel or iron. It has been found that the use of copper is most suitable. In the second plating step, generally a metal having a relatively lower levelling effect such as, for example, chromium or nickel, is used.

The electropolishing step is a conventional orie involving an anodic treatment over the roller thus producing both a smoothing and brightening effect. The electroplating procedures used are also conventional and involve utilizing the roller as the cathode in an electrolytic bath. The electroplating enhances the surface characteristics of the roller, plate or die so that said roller imparts to the material to be embossed, a lustrous leatherlike finish. Any suitable or conventional electrolyte can be used in the electroplating bath. As indicated above, a plurality of electroplating steps is employed in order to secure the desired surface characteristics comparable to those of the original material. Thus, for example, in the production of an embossed vinyl material possessing the characteristics of a smooth kid leather which is highly desirable, for example, in the footwear industry, the first electroplating step is effected by use of a metal having a high or medium levelling effect such as copper followed by a second electroplating step using a metal having a relatively lower levelling effect such as chromium.

By use of the process of the present invention, there is obtained a modified roller, plate or die which is capable of reproducing unusual textured effects and especially those requiring fine and delicate designs, on various substrates such as, for example, vinyl fabrics. It is thus possible to obtain, for the first time, a reproduction of any textured surface characterized by great fidelity and extreme dimensional accuracy.

Further, the reproduction capacity of the modified roller obtained by the present process exceeds the limits of machine engraving as there is no limitation with respect to shape, size, design or pattern.

In order that the invention may be more fully understood, the following Example is given by way of illustration only.

Example A 6-foot embossing roller was engraved with the best smooth kid grain available. The embossing effects previously obtained on a polyvinyl chloride fabric were unsatisfactory since the fabric was characterized by a dull-plastic look and there were tool marks noted on the fabric including parallel lines. While there was some improvement in the texture of the fabric by subjecting it to electro-polishing, the fabric still did not compare favorably with the natural grain or texture of kid grain.

The embossed roller composed of a conventional steel such as SAE 1035 was stripped of metals previously plated. The roller was then hung in a tank which was steel lined, said tank functioning as a cathode while the roller functioned as the anode.

While the preferred electrolyte contained phosphoric acid and chromic acid, any electrolyte suitable for electropolishing steel, aluminum or copper can be used depending upon the cylinder metal or material.

The electropolishing of the roller is effected by subjecting said roller to the following composition under the indicated conditions: Sulfuric acid 15% Phosphoric acid 65% Chromic acid 6% Water 14% Specific Gravity 1.74 Anode Current Density 50-1000 Amp/sq.ft, Temperature 80-180°F Treatment time (mia) 5-20 (or as required) The micro roughness of the roller plate was reduced and some of the high points of the metal surface were removed.

After the electrolytic treatment, the roller was subjected to a copper flash from a cyanide bath having the following composition and under the following conditions: Copper cyanide 3.0 oz/gal Sodium cyanide 4.5 - " Sodium carbonate 2.0 " Sodium hydroxide to a pH of 12 to 12.6 Cu by analysis 2.1 oz/gal Free cyanide 1.0 Temperature 90-110 °F.

Cathodic current density 10-15 Amp/sq.ft.

Plating thickness 0.05-0.1 thousands of an inch On this copper flash, a bright acid copper was electrodeposited and the composition of the plating bath as well as the conditions are as follows: Copper sulfate 30 oz/gal Sulfuric acid 5.5 fl. oz/gal Chloride ion 30 mg/1 UBAC Make-up additive 0.75% (by wt) UBAC-R1 Additive 0.25% (by wt) Temperature 90° F Cathode current density 100 Amp/sq.ft.

Agitation: Air 1-2 cfm per sq.ft. of soln. surface Plating thickness: 1-2 mills (for our roller) The electrolyte was subjected to a moderate agitation as, by stirring, in order to keep the deposit surface free from hydrogen bubbles.

It should be noted that for practical pur¬ poses only a thin layer of copper is required.

A' final chromium plate is deposited on the bright copper surface and a standard hard chromium bath was used having the following composition and under the indicated conditions: Chromic acid 33.0 oz/gal Sulfuric acid 0.33 Bath ratio CrO^/H5SO 100: 1 Temperature 110-120° F Cathode Current Density 0.7-1.5 Amp/sq.ft.

Plating thickness 0.5 mills (for our roller) The plating bath determines the levelling effect i.e., the ability to deposit in recessed areas.

The product obtained by use of a modified roller prepared by the foregoing combined electro-polishing and electroplating steps is characterized by a glossy, shiny brilliance possessing the "touch" and feel of kidskih. The product is also characterized by an elegant appearance and simulates, in every detail, the appearance and texture of kidskin leather.

It is, of course, to be understood that the present invention is by no means limited to the particular methods and devices set forth above, but also comprises any modifications within the scope of the intended claims. Thus, the rollers, dies, and the like, can be made of any material having a conductive surface.

Further, the embossing rollers, molds or dies can be used on many material substrates such as synthetic ma erials, paper, wood, metal, and the like. Still further, as electrolytes, various substances can be suitably employed.

Claims (2)

1. I 35205/2 - 22 - - CLAIMS . 1, A method of treating an engraved master surface to reproduce a fine or textured pattern, in high fidelity, on a suitable substrate material, by subjecting said master surface to a combination of steps comprising electropolishing said master surface, subjecting the master surface to a plating with a brightening metal having a high to medium levelling effect and a plating step with a metal having a relatively lower levelling effect.

2. A method of treating an engraved master surface to reproduce a fine. or textured pattern, in high fidelity, on a suitable substrate material, according to Claim 1, which comprises , I L. n 9. An engraved roller capable of reproducing a fine or textured pattern in high fidelity on a substrate material, said roller having been obtained by a method according to any one of Claims 1 to 8. For the Applicants DR D:BH