Colour-proofing sheet and production process.

In multi-color printing, a color check is made to allow the correction of the color separation used for the exposure of printing plates in general. The test pattern must be a consistent duplicate of the desired tone or line image and should reflect neither increased nor decreased the tone of colors. The visual color test shall demonstrate the following:<ul><li>1. error in the photomask,</li><li>2. the best color reproduction, which is to be expected when printing in the printing press of the material,</li><li>3. the exact gradation of all hues and whether grays are neutral,</li><li>4. the possible need to mitigate one of the colors and / or instructions for changing the film template before making the printing plates.</li><li>The color proofing for multi-color printing is previously made with the help of color proofs. It all needs to be made also in actual multicolor printing necessary steps. Such color proofing is costly and time consuming, and it has therefore developed alternative color proofing which will match the proofs in quality. Two photographic color proofing processes are known, namely the so-called surprint method (superposition copy) and the so-called overlay process (superimposing).</li></ul>

When Color Check after the overlay method, a single-color image is formed on each of a transparent plastic carrier of each color separation for themselves. several such provided with color separations carriers then are superimposed on a white sheet to manufacture a Farbprüfsatzes. The overlay method has the disadvantage that the superimposed plastic supports making the multicolor image darker.

When tested after surprint process a color proof is prepared by successively producing images are produced in different colors of different color separations on a single receiver sheet. For this purpose, only an opaque support is used, the toner sequentially or light-sensitive layers in the respective colors are applied, as described for example in US-A 3,671,236. The surprint method has the advantage that the color saturation is not influenced by superimposed plastic supports. This method comes closer to the actual pressure and avoids the overlay process color distortion.

In US-A 3,721,557 a method for transferring colored images is described in which a release liner is applied between the photosensitive layer and the support. When the photosensitive layer is exposed and developed, the more soluble parts of the layer are selectively removed, and there is a visible image. The carrier with the image is pressed against a suitable adhesive coated receiver and then made the image transfer by peeling off the support. For each additional image transfer a fresh layer of adhesive is applied to the receiver.

A disadvantage of this surprint color proofing is that the image caused by external influences, such. As fingerprints, scratches, dust, etc. is very easily damaged.

To protect the surface of the surprint color proof can therefore eg. As a thin transparent film, for example of polyester, which is coated with a pressure-sensitive adhesive layer may be laminated to the image layer. Such a process is described in US-A 4,329,420. This known process usually results in the formation of thick, glossy surface layers on the surprint template, by the appearance of the original is adversely changed circumstances. So is in many cases the surface of a Mehrschichtfarbprüfbogens preferably have a matte or gloss-free structure, in order to come close to the pressure conditions in the practical application, where neither a natural a glossy surface produced by coating is still present as possible. It is by this method is not possible to compensate for large differences in height of the image layer if you do not want to walk by temperature and / or pressure increase during lamination risk to distort the picture elements.

It has been tried in various ways to reduce the surface gloss of the above-described surprint Farbprüfvorlagen, but none of the methods used for this purpose was simple and effective enough. The application of pigment powders, pigment sprays, pigment paints or aqueous pigment dispersions to the shiny surface of the template, as described for. Example, in US-A 4,286,046, involves problems in terms of cost, cleanliness, and health with it, and it is also not possible to achieve in this way a matt surface, which has satisfactory properties in terms of uniformity, texture and appearance.

The object of the invention is to provide a color proof, the image layer is effectively protected against mechanical and chemical influences by a protective layer which can be made as thin as desired, that it does not distort the image impression and a flat, matted as desired or glossy surface was having, without the distorted image layer by applying the protective layer or is changed.

The invention relates to a color proof from a substrate, a multi-colored image layer consisting of several sub-color images, and a transparent cover layer.

The color proof according to the invention is characterized in that the covering layer consists of a lower ply of a thermoplastic adhesive layer at room temperature is not sticky and contains at least one thermoplastic polymer, and an upper layer of an anti-blocking layer which, at temperatures up to 50 ° C is not blocks and contains at least an organic polymer.

According to the invention, a method for preparing a color proof is also proposed, in which a flexible substrate successively several partial color images are transferred, so that a multicolor image is formed, and the multicolor image with a transparent cover layer is covered.

The inventive method is characterized in that either on the multicolor image <ul><li>a) a multi-layer film structure made<ul><li>aa) a carrier film,</li><li>ab) a transparent anti-blocking layer which up to 50 ° C does not block at temperatures and contains at least one organic polymer, and</li><li>ac) a thermoplastic transparent adhesive layer which is not tacky at room temperature and contains at least one thermoplastic polymer,</li></ul></li><li>laminated with the free surface of the thermoplastic adhesive layer, and thereafter withdrawing the carrier film of the anti-blocking layer, or</li><li>b) a layer structure of<ul><li>ba) a carrier film and</li><li>bb) a thermoplastic transparent adhesive layer which is not tacky at room temperature and contains at least one thermoplastic polymer,</li></ul></li><li>laminated with the free surface of the adhesive layer, subtracting the carrier film from the adhesive layer, the adhesive layer is a layer structure made <ul><li>bc) a carrier film and</li><li>bd) a transparent anti-blocking layer which up to 50 ° C does not block at temperatures and contains at least one organic polymer,</li></ul></li><li>laminated with the free surface of the anti-blocking layer and the support film is withdrawn from the antiblocking layer.</li></ul>

Under "Block" or "Block" is the well-known tendency of thermoplastic films or layers are understood in the context of this description, to stick on prolonged storage in direct contact with each other.

The thermoplastic adhesive layer is at room temperature not be sticky, but forming at temperatures between 60 and 90 ° C under the pressure of the lamination firm adhesion both to the image layer and to the anti-skid layer.

For performing the method according to the invention, a photosensitive material is used which generally consists of a layer support and a color image formed thereon and is known per se.

In a preferred embodiment consists of the carrier layer from a dimensionally stable and chemically stable polyester film, in particular polyethylene terephthalate, which normally has a thickness of about 25 - 75 microns comprising - 250 microns, before preferably about 50-130 .mu.m and in particular about 50 microns. Suitable films include Hostaphan 3000 (manufacturer American Hoechst Corporation), Mylar D (produced by DuPont) and Melinex in grades 0, 052, 442, 516, and S (manufacturer ICI).

On the substrate surface, a color image is enshrined. This overall picture is preferably comprised of four frames which are übereinanderlaminiert so that faithful color reproduction of an original image is obtained in the primary colors. Typically, each frame is made of a colored light-sensitive material by imagewise exposure and development.

In general, the photosensitive layer of the photosensitive material of a photosensitive compound, a colorant, a resin as a binder and optionally further ingredients, for. Example, plasticizers, acid stabilizers, surfactants, antistatic agents, UV absorbers and solvent residues.

Suitable photosensitive compounds include quinone diazides suitable, for. Example, esters of 1,2-naphthoquinone-2-diazide-5-sulfonic acid and polyhydric phenols, z. B. 2,3,4-trihydroxy-benzophenone or the reaction product of 2 moles of this compound with 1 mole of formaldehyde. Such compounds are described in US-A 4,407,426, 4,266,001 and 3,201,239.

As a photosensitive compound, a diazonium salt polycondensation product is preferably used. Most preferred is a polycondensation product of 3-methoxy-diphenylamine-4-diazonium sulfate and 4,4'-bis-methoxymethyl-diphenyl ether, precipitated as mesitylene sulfonate as described in US-A 3,849,392. Other suitable compounds are mentioned in US-A 4,436,804. The selected diazonium compounds are preferably soluble in organic solvents.

As binders suitable resins are polyvinyl butyral, and styrene / maleic acid half ester copolymers or mixtures thereof. Such resins are, for example Butvar B 72, B 76 and B 90 and Scripset 540 and 550, all of which are manufactured by Monsanto. An important criterion in the choice of resin is that it must have good film-forming properties.

The inventively suitable colorants include various dyes and pigments. In the most preferred embodiment, pigments are used having an average particle size of about 1 micron.

The photosensitive layer may be added to the phthalate or phosphate type optionally plasticizers. Preferred plasticizers are dibutyl phthalate and dimethyl phthalate. Suitable acid stabilizers are, for example, phosphoric acid and p-toluenesulfonic acid.

These components may be dissolved in acceptable solvent such as ethanol, 2-methoxy-ethanol, diacetone alcohol, butyrolactone, propylene glycol monomethyl ether or butanone applied to the support surface, and dried.

The photosensitive layer is preferably anchored by means of a suitable adhesive, eg. As polyvinyl acetate, on the support.

The invention is the force applied to the carrier image prior to use and transport-related damages caused by scratches, dirt particles and. The like. Are protected.

For this purpose, the image layer is to obtain a thin, durable protective layer. Although thickness of protective layers can be easily applied, but it distorts the optical properties of the image. When a thick protection layer is laminated using heat and pressure to the image layer, it is all cases where the thermal expansion of the protective layer is different from the thermal expansion of the composite of image layer and carrier material, a considerable curvature of the provided with the protective layer image layer ,

It is therefore desired to carry out the lamination by application of pressure and at a relatively low temperature, since at too high temperatures there is a risk that the image is deformed and discolored. In addition, the protective layer can not block even after prolonged storage.

According to the invention, the image is protected by a right to the image surface laminated adhesive layer and a coating applied to the surface of the adhesive layer antiblocking layer. For the order of these two layers, there are two courses of action:

The adhesive and the anti-blocking layer may be applied individually or together. When single order, the two layers after lamination of their temporary carrier films have to solve, ie the adhesive force between the adhesive layer and the anti-blocking layer and the respective carrier film must be less than the adhesive force between the image layer and the adhesive layer or between the adhesive layer and the antiblocking layer. You must also be less than the cohesion of the image layer, adhesive layer, antiblocking layer and carrier film. The applied onto a carrier film adhesive layer may be first laminated to the likewise applied to a carrier film antiblocking layer and then the carrier film of the adhesive layer can be peeled off. After lamination, the adhesion between the adhesive layer and its support film must be less than the adhesion between the anti-skid layer and its support sheet. The combination of adhesive layer, antiblocking layer and carrier film is then laminated to the image layer, and such that the adhesive layer is applied directly to the image layer. Then, the carrier film of the anti-blocking layer is peeled off.

Preferably, the adhesive layer and the anti-blocking layer located on a common carrier sheet. The anti-blocking layer is adjacent to the carrier film. You must can be solved after the lamination of the carrier film. The adhesion force between the anti-blocking layer and the carrier film must be less than the adhesive force between the adhesive layer and the anti-blocking layer and also lower than the adhesive force between the adhesive layer and the image layer.

On the individual adhesives and anti-skid layers are against pollution protectors that are withdrawn before the laminating process for protecting. The adhesion force between the adhesive or anti-blocking layer and the respective protective film must be less than the adhesive force between the adhesive or anti-blocking layer and the respective carrier foil. Preferably, the adhesive layer of deposited on a carrier film composite of adhesive and anti-skid layer is covered with the protective film. Before lamination of the composite to the image layer, the protective film is peeled off.

The carrier films preferably consist of a material that retains its shape under laminating, for. Example, from polyester, especially polyethylene terephthalate. They can be transparent or opaque, colorless or colored.

The surface of the support can be structured smooth or matt. Corresponding matting are known from the prior art.

As smooth carrier film suitable for example, sheet of Melinex 5L6, manufacturer ICI.

Suitable frosted films include Melinex 329, 377 and 470. The surface gloss of the final image can be determined by selecting an appropriately matted carrier film for the anti-skid layer.

In order to produce a matt protective layer, the adhesive and the anti-blocking layer can be laminated under pressure and heat to the final image. Then, the carrier film is pulled off with the roughened surface. By the rough surface of the carrier film the finished image gets a matt protective layer. The surface structure of the thus protected by the subsequent image layer may laminating a structured film, which is removed again following the lamination process, to be further modified. The further modification may also occur by a treat- ment with solvents and / or abrasive particles, is removed by the part of the protective layer again.

In all cases the carrier film must have a non-stick surface, that is, the anti-blocking layer must be anchored releasably on her. This is achieved in that a carrier film is used, the surface of which is inherently non-stick and that the support surface is made non-adhesive by an appropriate treatment, or by applying a special separation layer. Such a release layer may for example consist of polyvinyl alcohol.

The adhesive layer has a thickness of 0.5 to 30 microns, preferably from l to 20 .mu.m, and in particular from 5 to 20 microns.

The adhesive layer is composed mainly of a thermoplastic polymer, or of a mixture of thermoplastic polymers which is substantially non-tacky at room temperature. Suitable polymers have a glass transition temperature Tg of 20 to 60 ° C, especially from 25 to 55 ° C. The thermoplastic polymers should be able to form flexible films. They are transparent and colorless. The adhesive layer can also contain plasticizers, UV absorbers, wetting agents and antistatic agents.

Suitable thermoplastic adhesives include polyvinyl how Butvar B 79, from Monsanto; Polyvinyl acetates, such as Mowilith 30, manufacturer American Hoechst Corp .; Polybutylmethacrylate how Elvacite 2044, available from DuPont; Cellulose nitrates, as RS 1/2, manufacturer Hercules; and polyvinyl chloride / polyvinyl acetate copolymers, such as UCAR VYNC, manufacturer UCC. Also novolaks and epoxy resins can be used.

The thickness of the anti-blocking layer is 0.2 to 20 microns, preferably l to l0 microns, especially 1 to 3 micrometers. This layer consists mainly of an organic polymer or from a mixture of organic polymers. The composition of the anti-blocking layer is selected so that it at temperatures b , preferably to 70 ° C, does not block is a maximum of 50 ° C. Blocking is measured by known standard rules for. Example by the method described in ASTM D LL46.

The polymer used in the anti-blocking layer should have a glass temperature above 60 ° C, preferably above 70 ° C, and have, in particular about l00 ° C. You should be able to form flexible films. They are transparent and colorless; they may contain additives such as plasticizers, UV absorbers, wetting agents and antistatic agents. A suitable polymeric plasticizer is z. B. Carboset 525 is an acrylic resin of the BF Goodrich Company.

. When polymers with anti-blocking properties are, for example styrene / maleic anhydride copolymers such as Scripset 540, Monsanto; Polyvinyl how Butvar B 90, from Monsanto; Polymethyl methacrylates, as Elvacite 2008 from DuPont; and vinyl acetate / vinyl chloride copolymers, such as CM Hostaflex L3L, manufacturer American Hoechst Corp. suitable.

The anti-blocking layer and the adhesive layer can be applied in known manner, for. Example, by coating or laminating, to the corresponding temporary carrier films.

The lamination of the composite of carrier film, anti-blocking layer and adhesive layer on the image or the lamination of the composite of carrier film and adhesive layer on the image and then laminating the composite of carrier and anti-blocking layer is under pressure and heat.

For the lamination process, for example, the image in contact with the adhesive layer of the composite is placed, and the two parts are then passed through the nip of a pair of heated laminating rollers by which an appropriate pressure is applied. The lamination temperatures are generally in the range of 60 to 90 ° C, preferably in the range of 75 to 85 ° C. After lamination, the carrier film is removed, which usually takes place manually. The adhesive layer and the anti-skid layer remain back on the fine carrier.

The following examples the invention is explained in detail. All coating weights are in for dry layers.

example l

For the preparation of an antilock mixture the following ingredients are added sequentially in a vessel:     39% ethylene glycol monomethyl ether,     39% methyl ethyl ketone,     l0% butyrolactone,     l0% Scripset 540 (styrene / Monoisobutylmaleinat copolymer; acid number 185; M_n 50,000; Tg = l33 ° C) and     2% Carboset 525 (terpolymer of 32% ethyl acrylate, 58% methyl methacrylate, 10% acrylic acid; SZ 80; MG 260,000)

The second polymer is added only when the first polymer is completely dissolved. The solution is stirred at least one hour until all ingredients are dissolved. Then it is applied to a 0.076 mm thick polyester film with a matte, surface-untreated (Melinex 377) so that a dry layer weight of 3 g / m² results. The film is blown dry at 85 ° C for one minute.

To prepare an adhesive solution, the following ingredients are added sequentially into a clean container:     50% n-butyl acetate and     50% UCAR VYNC (vinyl chloride / vinyl acetate copolymer) in isopropyl acetate (Tg = 5l ° C., manufacturer UCC).

The solution is stirred at least one hour at room temperature and then applied to a dry coating weight of l2 g / m² to the antiblocking layer. The resulting composite on the carrier film is dried at 85 ° C for 90 seconds. It is then placed directly on a four-color image layer with the adhesive layer. The lamination is performed by the two superposed materials are managed under appropriate pressure through the nip of a heated to 75 ° C Laminierwalzenpaares. After lamination, the carrier film is peeled off. The adhesive and the anti-lock layer remain on the four-color image layer. Through the polyester film, the surface of the anti-blocking layer has received a rough structure. Under a load of 0.07 kg / cm² and a temperature of 70 ° C no blocking is detected even after 24 hours.

example 2

For the preparation of an antilock mixture the following ingredients are added sequentially in a vessel:     42% ethylene glycol monomethyl ether,     42% methyl ethyl ketone,     l0% butyrolactone and     6% Butvar B-90 (polyvinyl butyral; Tg = 65 ° C).

The solution is stirred at least three hours until the polymer is completely dissolved. She is on a 0.076 mm thick highly transparent polyester film with a smooth, untreated Oberläche (Melinex 5L6) applied such that a dry layer weight of lg / m² results. The layer is dried at 85 ° C for one minute.

To prepare an adhesive solution, the following ingredients are added sequentially into a clean container:     78% n-butyl acetate,     2l% Mowilith 30 (polyvinyl acetate, MG 110,000; Tg = 28 ° C) and     l% Resoflex R 296th

The solution is stirred for at least four hours at room temperature and then applied to a dry coating weight of l0 g / m² to the antiblocking layer, and dried at 85 ° C for 90 seconds. For protection against contamination, the adhesive layer is of Bauer covered with a liner paper no. 7, which is peeled off prior to lamination. For the lamination, the applied to the carrier film protective layers laminated with the adhesive side is placed directly on a four-color image layer. The lamination is performed by the two superposed materials are managed under appropriate pressure through the nip of a heated to 75 ° C Laminierwalzenpaares. After lamination, the carrier film is peeled off. The adhesive and the anti-lock layer remain on the four-color image layer. Through the polyester film, the surface of the anti-blocking layer has a glossy surface condition. In a further step, a polyester film of the type used in Example 1 (Melinex 377) is laminated and then stripped again to the antiblocking layer of the composite of antilock, adhesive and the image layer. The surface of the protective layer is replaced by a semi-matt appearance. A Block of provided with the protective layer image layer is not detected even at 50 ° C.

example 3

Following the procedure of Example l, a protective layer is applied to an image layer. The material is then laid flat in a dish. A normally used to develop cotton tampon with an aqueous sodium hydroxide solution, the pH of which is L2.5 impregnated. The protected image layer is rubbed under light pressure with the soaked tampon, so as to remove the anti-skid layer partially. Subsequently, the protected image layer is rinsed for 20 seconds using water, placed on nichtfaserndes paper and blotted dry. The treatment with the sodium hydroxide solution and then rinsing with water, the rough structure of the anti-skid surface layer has been partially removed.

example 4

Following the procedure of Example l a composite of adhesive and Antiblockieschicht is produced on a carrier film. A four-color image layer is generated, according to the US A 3 67l 236th The composite is placed with the adhesive side to the image layer, and the two materials are passed at a temperature of 75 ° C and under appropriate pressure between a heated Laminierwalzenpaar while laminated to each other. Then, the carrier film is peeled off. The adhesive and the anti-skid layer remain on the four-color image layer.

example 5

For the preparation of an anti-blocking layer, the following components are successively introduced into a vessel:     85% methyl ethyl ketone and     l5% Hostaflex CM L3L (vinyl chloride / vinyl acetate copolymer; Tg = 75 ° C)

The solution is stirred at least three hours at room temperature until the components are completely dissolved. Then it is applied with a doctor blade to a 0.076 mm thick polyester film hochgeschmeidige with untreated surface (Melinex 470) so that a dry layer weight of 3 g / m² is obtained. Drying takes place at l00 ° C for one minute.

To produce the adhesive layer a solution of the composition shown below by means of a doctor blade onto a 0.1 mm thick, highly transparent polyester film whose surface has been treated with a lubricant (Hostaphan 3000), applied. The coating has a weight of l8 g / m².     78% n-butyl acetate,     2l% Mowilith 30 and     l% Resoflex R296.

The coating is dried at l00 ° C for 3 minutes. The film with the adhesive side is laminated directly to a four-color image layer by the two materials are passed through the nip of a heated Laminierwalzenpaares at 75 ° C and under appropriate pressure. After lamination, the carrier film of the adhesive layer is peeled off. The anti-blocking layer is laminated as previously described directly on the adhesive layer. Then, the carrier film of the anti-blocking layer is peeled off, so that only the adhesive and the anti-skid layer left on the four-color image layer. By Melinex 470 film, the surface of the anti-blocking layer has received a fine structure. At 50 ° C, no blocking of the protected image layer is found.

example 6

The procedure is as in Example l except that the adhesive layer used has the following composition:     64% n-butyl acetate,     l0% Mowilith 30,     l% Resoflex R296 and     25% UCAR VYNC in isopropyl acetate.

The results correspond to those of Example l.

example 7

The procedure is as in Example l except that the anti-skid layer employed has the following composition:     9% butyrolactone,     35% methyl ethyl ketone,     34% ethylene glycol monomethyl ether, 8% Scripset 540,     2% Carboset 525 and     ll% n-butyl acetate.

At 70 ° C, no blocking of the protected image layer is found.

example 8

The procedure is as in Example l except that the coating weight of the anti-skid layer 5 g / m² and the adhesive layer ll g / m². The results correspond to those of Example l.

example 9

For the preparation of an anti-blocking layer, the following components are sequentially mixed results:     20% methyl ethyl ketone,     67% n-butyl acetate,     l2% Hostaflex CM L3L and     l% Resoflex R296.

The solution is stirred for at least 3 hours at room temperature until all components are completely dissolved. Then it is applied with a squeegee on a Melinex 377 film. The coating weight obtained is 5 g / m². The coating is dried at 85 ° C for one minute.

For the preparation of an adhesive layer a solution of the following composition with the aid of a doctor blade is applied to a film of the type Melinex 5L6. The coating weight was l2 g / m².     78% n-butyl acetate,      2l% Mowilith 30 and      l% Resoflex R296.

The layer is dried at 85 ° C for 90 seconds. Then, the film with the adhesive side is laminated directly to a four-color image layer by the two materials are passed through the nip of a heated Laminierwalzenpaares at 75 ° C and under appropriate pressure. After lamination, the carrier film is peeled off from the adhesive layer. The anti-blocking layer is as previously described lamminiert directly to the adhesive layer. Then, the carrier film of the anti-blocking layer is peeled off, so that only the adhesive and the anti-skid layer left on the four-color image layer. By Melinex 377 film, the surface of the anti-blocking layer has received a rough structure.

example l0

The procedure is as in Example 9 except that the anti-blocking layer is applied to a sheet of Melinex 5L6. It can be achieved comparable results, but gives the film the surface of the anti-blocking layer a shiny appearance.

example II

The procedure is as in Example l except that the film is coated with an anti-blocking layer having the following composition and the coating weight was 5 g / m².     65% n-butyl acetate,     20% methyl ethyl ketone,     l% Resoflex R296,     0.4% Mowilith 30 and     l3.6% Hostaflex CM L3L.

To the anti-blocking layer, an adhesive solution of the composition indicated below is applied. The coating weight was l2 g / m².     79% n-butyl acetate,     l% Resoflex R296 and     20% Mowilith 30th

The composite layer is laminated to a multi-color image, and peeled off the carrier film. At a temperature of 50 ° C, no blocking is detected.