DE2109752A1 - Clear film having anti - newton and antistatic properties - suitable eg for protecting photographic transparencies (slides) - Google Patents

Abstract

The film comprises a transparent film (e.g. PS, PVC, polyamide, PPO) coated at least on one side with a coating contg. a binder, comprising or contg. a lower mol. wt. polyester resin, formaldehyde condensate, gelatin, cellulose deriv.; a practically colourless pigment contg. SiO2 and pref. comprising amorphous or highly disperse silicic acid, silica gel powder, quartz powder, glass powder; and an antistatic agent, e.g., a quaternary ammonium salt. Film so coated is suitable e.g., for protecting photographic transparencies, or in mfre. of large-scale montages in gravure printing or cliches.

Description

The film and method for making the same are subject of the present invention Invention is a transparent film with anti-Newton and anti-static properties, which are used, for example, as a protective film for the opening in front of slides can.

In particular, the invention relates to transparencies, di by a Surface coating have obtained the desired properties and have a ' effective permanent protection against electrostatic charge and opto-physical Have interference fringes (Newton rings). It is known to be electrostatic Charges in the manufacture, processing and use of plastic films, especially in the graphics industry and with protective films, have a very detrimental effect, because the electrostatic charge attracts dust particles and the Dirty foils.

The electrostatic charging of foils is a surface phenomenon, which takes place in the first upper molecular layers. The strength of this charge depends on a number of factors such as the surface resistance, the relative humidity, the surface properties and the chemical Structure of the film material, for example a polymer material. Aim of the anti The static equipment of the foils is to reduce the surface resistance by 4-5 powers of ten reduce so that the electrical resistance of the foils to about 101 °, in particular Drops by 10 ohms or less. A surface resistance 1 around or below 109 ohms, is in fact generally sufficiently low to avoid a disturbing electric avoid static electricity.

Newtonian rings or interference figures arise when polychromatic Light falls on a layer of air that is between a flat layer, for example a glass plate, and a slightly curved second layer on top, or for example, a film of a second glass plate is located.

The colored interference phenomena are based on the fact that, as a result the small and uneven spacing between the layers, for example between the glass plates, certain wavelengths of light due to interference are extinguished and the corresponding complementary colors as interference figures become visible.

The Newtonian interferon figure has a particularly disruptive effect in the ticfprint copy, in the halftone screen and in the projection of between two protective layers: for example glass plates, made of transparencies. It is known from glass that a surface roughness leads to the formation of the Newtonian interference figures can largely be avoided.

The present invention relates to a film with anti-Newton and anti-static properties which is characterized by having a clear Foil has a coating on at least one of its sides that contains a binding agent, contains a practically colorless pigment and an antistatic agent. The surface layer can be on either or both sides of the slide.

As a practically colorless pigment that gives the anti-Newton finish is achieved, an inorganic pigment can in particular 0.3 to 0.2 of a diameter from 0.05 to 5 \ p can be used, as well as organic materials, for example Starch, cellulose, cellulose derivatives and plastic powder, but with the Use of organic materials care must be taken to ensure that these are in the Binders are not completely soluble.

A material containing SiO2, in particular, is preferred as the pigment amorphous or highly dispersed silica, silica gel powder, glass powder or quartz powder used. When the pigment is out very small particles (in proportion to the light wavelength), the light scattering is very small, but it increases proportional to the particle diameter, but only up to a certain size, in order to then decrease again proportionally with the specific surface of the particles. The location and the height of the maximum depend on the refractive index of the pigment and in particular on the difference between the refractive index of the pigment and the refractive index of the binder in which the pigment is incorporated. If you look at the refractive index of the pigment in the correct proportion to the refractive index of the binder and the Selects the substrate and bases the particle size of the pigment on this ratio, however, a minimum value was observed to maintain the anti-Newton effect then colorless pigments and those on the film become invisible Coating appears colorless, clear and transparent.

The binder used in the coating of the films according to the invention should expediently have certain hydrophilic properties, this being the case for example can be achieved by using a polymer material as a binder, which has hydrophilic groups, for example COOH groups or hydroxyl groups, or a hydrophilic component is added to the binder. Examples of usable Binding agents or components of binding agent systems are polyester resins and polyurethane resins, formaldehyde condensation products, condensation products from ketones and Aldehydes, epoxy resins, aerylic acid homopolymers, and copolymers, homopolymers and copolymer of Acrylic acid derivatives, vinyl homopolymers e and copolymers, cellulose derivatives, water-soluble primers and gelatin. One Requirement 1 that the natural binder must meet is that it has both the film material as well as the pigment is compatible.

By using binders with a certain amount of hydrophilic. properties it is achieved that the Antistatic-Ant Newton coating also has a good absorption capacity for water-soluble colors (masking colors) or ink and Indian ink.

Paints that are dissolved in organic solvents can also are used, in general only when using alcohol as Solvent care is required.

Another advantage of the coating of the films according to the invention is that they can be made to give the coating a has medium adhesion to adhesive tapes. The preferred according to the invention Films have such an adhesion compared to the adhesive tapes customary in the trade on that when an adhesive tape is applied to the layer and after its de) There are no visible traces of adhesive left on the layer. The layers are also suitable for anchoring assembly adhesives.

Various additives can be used as antistatic agents, including natural substances also fall. Be mentioned as examples of antistatic agents that can be used Substituted primary, secondary or tertiary amines, quaternary ammonium salts, imines, in particular alkaline neutral or acidic polyimines, polyols and polyglycol derivatives, derivatives of pyrrolidone, imidazole and pyrimidine, carboxamides and nitriles and organic Phosphoric acid esters.

It has been found to have particularly durable anti-static properties can be achieved when the pigment is impregnated with the antistatic and this combination of anti-Newton component and antistatic component to manufacture the layer is used. The layer applied to the film material can have a strength of 0.5 to 5 / a, in particular from 1 to 2 @ µ iu. Both added pigments, grain sizes of 0.1 to 1 / u are preferred, and when used of amorphous silica as a pigment, a material is preferably used which has a surface area of 200-400 m2 per gram, especially about 300 per gram, The invention also relates to a method for producing the inventive Foil, which is characterized by the fact that the foil material is mixed with a solution coated of the binder, which contains the pigment and the antistatic agent, and after the coating evaporates the solvent.

Another object of the invention is a coating mixture to carry out this process, which is characterized by the fact that it contains a solvent, the organic Binder containing pigment and antistatic agent.

There must be certain requirements on the layer carrier, i.e. the foil material. The material has to be transparent and it should The material should have very good dimensional stability and flatness preferably be colorless and it should enable a homogeneous coating. at When selecting the film material, the intended use should also be taken into account for the finished cling film with anti-Newton and anti-static properties is provided. Examples of well usable types of film are: polyester, Polycarbonate, polystyrene, polyvinyl chloride and both the homopolymers as well as copolymers of these materials, as well as cellulose derivatives, in particular Cellulose triacetate and gelulose acetobutyrate. Other film materials in The following are considered: polyphenylene oxide, polysulfone and polyamides with new acid components, and also polybeterocycles, such as polybenzimidozene, which itself has a low Has electrostatic chargeability and therefore in the manufacture of foils with optimal antistatic properties can be advantageous.

The films of the invention are because of their anti-nenton and anti-static properties and also because they are generally in addition to these properties have advantageous medium adhesions for adhesive tapes and adhesives as well as a good absorption and adhesion of inks, India ink and colors in watery or organic solution, excellent for many areas of application suitable.

Another object of the invention is the use of the inventive Films as protective film for framing slides.

As further important areas of application for the films according to the invention are to be mentioned: large-scale assembly in gravure printing, assembly in cliché production, the assembly for recopying as well as for the production of color separations, coloring and masking work in the original assembly.

In order to apply the coating to the foils, as before was mentioned, a solution of ces binder, the antistatic and the pigment contains, applied. Coating can be used in the photographic industry customary subbing machines are used. In the coating mixture can in addition to the solvent or the solvent mixture, contain further components be, for example, substances that allow the coating solution to spread evenly enable on the slide. The pigment content of the finished coating solution is generally 0.01 to 0.2% by weight of pigment, based on the finished formulation, including the solvent. Particularly preferred, in particular then, when silica is used as the pigment, the content is in the range of 0.03 to 0.1, in particular about 0.05 wt.

Pigment, based on the finished coating mixture.

The invention will now be explained in more detail with reference to the following examples.

Example 1 There was a basic formulation of the following composition produced 240 g of a synthetic melamine-based resin, 3000 ml of methylene chloride or methyl ethyl ketone or methyl acetate, then 1500 ml of methyl glycol added 6000 ml of methanol added when melamine completely dissolved 120 g of acetobutyrate under strong Stir entered 60 g of p-toluenesulfonic acid.

The pot life is 24 hours. Then this mixture was called Pigment of high-purity amorphous silica with a mean particle size of about 0.9 m / u mixed in with a BET surface area of 290 m2 / g. Mixing in the silica is advantageously carried out in such a way that initially part of the basic recipe given above is removed and mixed with the total amount of silica and then this Pour concentrate into the remaining amount of the gun recipe. As an antistatic agent a quaternary ammonium salt was used, the antistatic being either after can be added to the silica or already contained in the basic mixture can be. The film obtained had very good antistatic and anti-Newton properties on.

If you use the above recipe instead of silica with a particle size of 0.9 / u even finer silica with medium particle sizes 0.3 or 0.5 used, then one also obtained very good anti-Newton properties. Other commercially available antistatic agents have been used in place of the quaternary ammonium salts used in the concentration specified for these agents, namely organic Derivatives of phosphoric acid, polyimines and mixtures of these substances. Even when in use films with very good antistatic properties were obtained from these antistatic agents Game 2 A coating formulation of the following composition was prepared 34 ml of a low molecular weight polyester primer to 8.5% in a ternary solvent mixture pre-dissolved 34 ml methyl ethyl ketone 136 ml dichloroethane 68 ml methyl ethyl ketone 0.135 g of a highly disperse silica Q, 07% of a higher molecular weight polyglycol ether Commercial antistatic agents in the specified concentrations.

this coating mix was applied at machine speed from 2 m / min. applied to the polyester film and it became a dry temperature of 9000 complied with. A draft of 20 m3 / m2 was maintained during the drying process obtain.

Example 3 The same recipe was used as in Example 2, however, the antistatic and silica were not used in the preparation of the recipe added separately, instead the porous silica was first mixed with a solution soaked in the antistatic, and then the solvent was evaporated.

This silica> on which the antistatic is already absorbed, is then added to the casting recipe. Then, as described in Example 2, the film is coated.

The films obtained in this way had a particularly permanent antistatic Equipment. When the foils were repeatedly cleaned with light petrol, there was no decrease the antistatic equipment.

Example 4 The procedures of Examples 1 and 2 were repeated, However, instead of the highly disperse silica, a mixture of silica gel powder was used with quartz powder ocer a mixture of silica gel powder with glass powder, each in one Mixing ratio 3: 1 used. By using of the pigment with the coarser proportions of the glass powder or quartz powder the anti-Newton effect can be increased. Due to the presence of the fine pigment on the other hand, the appearance and the transparency of the coating was very homogeneous,

Claims (14)

P a t e n t a n s p r ü c h e 1.) Foil with anti-Newton and antistatic Properties, characterized in that a transparent film on at least one of its sides bears a coating that is a binder, a handy Contains colorless pigment and an antistatic agent. 2.) Film according to claim 1, characterized in that the binder contains a hydrophilic component or a material with at least a low level of hydrophilicity Properties is. 3.) Film according to claim 2, characterized in that the binder contains or consists of a synthetic resin binder, a cellulose derivative or gelatin consists. 4.) Film according to claim 3, characterized in that the synthetic resin binder a low molecular weight polyester resin, a formaldehyde condensation product, pin ketone-aldehyde condensation product, an epoxy resin, an aerylic acid polymer or copolymer, or a Contains or consists of vinyl mono- or copolymer. 5.) Film still one of claims 1 to, characterized by, that the colorless pigment contains silicon oxide and preferably an amorphous or highly dispersed silica, silica gel powder, glass powder or Cuerz powder is. 6.) Film according to one of claims 1 to 5, characterized in that that the antistatic is a local derivative of phosphoric acid, a quaternary Ammonium salt, a polyimine or a mixture of several of these substances. 7.) Film according to one of claims 1 to 6, characterized in that that they are a polyester homopolymer or copolymer, a polycarbonate Polystyrene, a polyvinyl chloride homopolymer or copolymer, a cellulose derivative, a polyphenylene oxide, polysulfone or polyamide or a polyheterocycle, in particular Contains or consists of polybenzimidazole. 8.) Film according to one of claims 1 to 7, characterized in that that the antistatic is absorbed on the particles of the pigment. 9.) A method for producing a film according to one of the claims 1 to 8, characterized in that the film material with a solution of Coated binder, which contains the pigment and the antistatic, and that Solvent evaporates. 10.) The method according to claim 9, characterized in that one a solution of the resin in a solvent and in any order the antistatic agent is added and the pigment is dispersed, and with this solution the film material coated. 11.) The method according to claim 9, characterized in that one prepares a solution of the binder and disperses a pigment in this solution, on that to which the antistatic is absorbed and with this solution uas film material coated. 12.) Method according to one of claims 9 to 11, characterized in that that the solvent is a chlorinated hydrocarbon, a ketone, an ester, contains an alcohol or a mixture of two or more of these components. 13.) The method according to claim 12, characterized in that the Solvent a lower chlorohydrogen, a ketone with up to 5 carbon atoms, a lower alkyl ester of a lower monocarboxylic acid, a lower one or dihydric alcohol or a mixture of one or more of these components contains. 14.) The method according to any one of claims 8 to 13, characterized in that that the coating solution also contains a component that is responsible for wetting the film with the solution facilitated, in particular a polyalkylene oxide or a Sulfonate,