DE834752C - Process for the production of films and foils from polymeric N-vinylpyrroles - Google Patents

Description

Process for the production of films and foils from polymeric N-vinylpyrroles The invention relates to the manufacture of sheets, films and foils that consist of polymeric N-vinyl compounds. More specifically, the invention relates to a method of 'facilitating the removal' of such sheets, films and transparencies from the surface on which they are poured.

Polymeric N-vinyl pyrroles of a molecular weight large enough for the production of films and sheets that hold together by themselves, e.g. 13. Polyvinyl carbazole, polyvinyl isopropyl carbazole, polyvinyl tetrahydrocarbazole, polyvinyl indole, polyvinyl prol> yl carbazole, polyvinyl naphthocarbazole and similar compounds are described in US Pat. No. 2072-165. If sheets, films and foils with a thickness of 0.025 to 1.225 mm and of any size are produced from such polymers, the polymeric NV inylpyrrole compound is dissolved in a suitable solvent and a plasticizer is added to make the mixture into a so-called casting solution do. This casting solution is poured onto the surface of a slowly rotating wheel or drum, the wheel or drum having a smooth nickel or chrome plated surface; casting can also be done on the surface of an endless metallic belt. The solvents are then removed from the deposited material using warm air. Finally, when the material has dried and post-treated, it is stripped from the surface on which it was poured in the form of a coherent sheet, which is wound onto a roll for storage and later - recovery, e.g. B. as an insulating film, protective layer and for being coated with emulsions for the production of photographic films. Notwithstanding the fact that most of the solvent is removed from the film by the time it has reached the point at which it is stripped from the surface on which it has been cast, there have been difficulties in removing the material from it the surface on which it has been poured. Regardless of which of the solvents recommended so far is used, such. B. benzene, toluene, xylene, dioxane, ethylene dichloride, etc. or mixtures thereof, the cast film or foil adheres so firmly to all known surfaces, such as stainless steel, Monel metal, chrome-plated material, copper, tin, silver, glass, synthetic resin etc. that it takes considerable force to bring about detachment. The effect of this is (let the film be stripped off in an irregular manner with considerable jerks. This causes vibrations which lead to the formation of cross-wise markings on the surface of the film or the foil, which considerably deteriorates the quality of the product obtained. The sticking is often so large that it causes small portions of the film to be torn away from the body and left on the surface on which the film has been cast.

In order to overcome the aforementioned difficulties, it is proposed the surface to be poured on with water or a wetting agent such as Tools for wiping off, moistening. This additional step in the casting process is not satisfactory because a) the surface in a continuous casting process must be carefully dried for the subsequent casting of the polymers mentioned, b) because an additional drying process of the film is necessary after it has been stripped off is.

One purpose of the present invention is to avoid the mentioned Difficulties and the use of resources through which sheets, films and transparencies with ease and without deteriorating their quality of the surface which they are cast can be stripped off.

Another purpose of the invention is to provide an improved method of stripping of polymeric N-vinyl pyrole compounds from the surface on which they have been poured are.

Further purposes of the invention emerge from the following description: It has been found that the aforementioned purposes of the present invention are thereby achieved can be achieved that a solvent is selected (read not only as Plasticizers for the film-forming polymeric N-V inylpyrrole compounds serves and gives the mentioned plivsical properties for this, but This also applies to the: 11 strips of the cast film or the cast foil useful for drying and finishing. This solvent is chloroform. Halogenated hydrocarbons in general are often used as solvents or Plasticizers have been proposed for various resins and polymeric materials -, been; It is extremely surprising, however. that of all these solvents only chloroform is able to give the polymeric N-vinylpyrrole foils plasticity give and the surface adhesion of such films to the surfaces on which they be cast, so to reduce that de foils of any of the known Surfaces of this type can be easily stripped.

Chloroform, when used alone, is particularly preferred. If chloroform is used alone, it has the combined properties of a solvent, a plasticizer, or an agent to facilitate scraping. When chloroform is used together with aromatic compounds or together with other chlorinated aliphatic compounds, either alone or in admixture with aromatic hydrocarbons. so the desirable plastifizieretiden and stripping facilitating properties are prevented from unfolding. The use of chloroform alone with polymeric N-vinylpyriol compounds results in an extremely useful and continuous method for casting tapes, films and foils, which is impossible to achieve when other solvents or solvent combinations are used.

As mentioned, the polymeric N-vinylpyrrole compounds used are capable of producing coherent films or sheets by themselves when a solution of the polymer is used for casting. In general, the polymers have a K value between 130 and Ido.

In the practice of the invention, any unplasticized polymeric N - @ 'invinpyrrole compound of the type indicated can be used, such as. B. the compounds obtained in the process according to the above-mentioned patent. A solution is prepared by dissolving an appropriate amount of the polymeric N-vinyl pyrrole compound in chlorine form. The amount of chloroform used is 135 to 45 parts by weight for approximately 3 to 8 parts by weight of the polymer. The solution is then filtered by any of the standard filtration methods. thereby obtaining a clear solution free of any extraneous or undissolved particles. Air which may be contained in the solution can be removed by vacuum or by heating the solution to 50 to 60 ° for 1 hour.

The clear solution of the polymeric N-vinylpyrrole compounds is then onto a drum with a smooth surface or onto an endless belt by means of a Funnel applied with a @likrometer setting device for checking the thickness of the film is provided. The drying and the final treatment are brought about by blowing air at low speed at 30 to 60 ° across the poured solution in a direction opposite to the direction of movement of the wheel or belt.

In order to fully understand the nature and purposes of the invention, reference is made to the following examples, which are given for further illustration only and which are not to be considered as limiting. All parts are non-essential. Example i A solution or casting solution is prepared in the following way: polyvinyl carbazole (mean K value approx. 170) 4 parts, chloroform 143 parts.

This solution was poured onto the polished periphery of a drum and formed a layer which, when dried, formed a film approximately 0.2 mm thick formed. The partially dried film was easily removed when it was removed from the guide roller, leading to the drying chamber.

The advantages of the invention will become apparent through comparison of the above process and the following, the effect of the addition of a further solvent to the chloroform solution of the polyvinyl carbazole, which is used for Casting the film was used, illustrated.

Polyvinyl carbazole (mean K value about 170) 4 parts, chloroform 52 parts, toluene 9i parts. This solution was poured in the manner indicated. The partially dried film was removed with difficulty, and those of its surfaces which abutted the surface on which the film was cast showed crisscross marks which decreased the value of the film.

The procedure of the example given above was repeated with with the exception that the same amount of ethylene dichloride was used instead of chloroform became. The partially dried film adhered strongly to the surface in this case, on which it was poured, and could not be stripped to put on the idler pulley, which led to the drying chamber to be placed.

Examples Polyvinylpropylcarbazole (average K value about 130) 8 parts, chloroform 138 parts.

Example 3 Polyvinyl tetrahydrocarbazole (mean K value about 130) 7.5 parts, chloroform 144 parts.

The solutions of Examples 2 and 3 gave very satisfactory results when poured Films that are easily removed from the surfaces on which they were cast and had the same satisfactory properties as the film of the Example i.

It is obvious that the solutions according to the invention. or casting solutions not only can be used for casting on peripheral surfaces, but that they are also capable of being cast on endless metallic belts to make sheets, Films and foils to give that clean from the surface on which they have been poured can be stripped.

While the present invention is detailed with respect to the preferred Method and '.Materials is described, it is understood that the The invention is not limited to this and that numerous variations in the described Measures can be taken. All of these modifications and variations are within the scope of the invention which is defined in the following claims.

Claims (2)

PATENT CLAIMS. - i. Process for the production of sheets and films from polymeric N-vinylpyrrole compounds which can be easily stripped from the casting substrate, characterized in that the N-vinylpyrrole compounds are dissolved in chloroform and the solutions are cast into films in the usual manner. 2. The method according to claim i, characterized ge-1; ennzeiclinet that as a film-forming material Polyvinyl carbazole, polyvinyl isopropyl carbazole or polyvinyl tetrahydrocarbazole are used will.