DE600942C - Process for the production of foils - Google Patents

Description

GREAT

In general, casein has heretofore been found to be unsuitable for making very thin sheets or skins which are made of cellulose, such as cellulose hydrate, cellulose acetate, Celluloid etc. products made with their own transparency, flexibility, tear resistance and should have impermeability to water.

It has already been suggested to casein

ίο by alkalis or acids in solution bring and process the solutions on foils.

According to one method, casein is dissolved in sodium hydroxide solution with the addition of formaldehyde. After the water has evaporated, a relatively transparent and impermeable film is obtained. This movie but cannot be compared with films made of cellulose hydrate or cellulose acetate will; because it cannot be made sufficiently thin without its impermeability and forfeiting homogeneity is not transparent, but rather shows a slightly whitish color Appearance; furthermore it is not flexible and elastic, cannot be broken without breaking fold, loses all of its plasticity when heated and cannot be mechanically Make casting in the form of continuous ribbons.

Another way of working is that casein is dissolved in dilute acids and is then treated with formaldehyde, whereupon the water is poured onto glass plates, optionally using of glycerine as a plasticizer is evaporated. This film is also no substitute for the above Foils, but has essentially the same disadvantages as the one before specified process manufactured product.

Another method is to convert casein into crystallizable acetic acid Addition of benzoic acid (or with the addition of crystallized phenol) and hexamethylenetetramine dissolved as a coagulant. The paste formed is dissolved in chloroform and processed further.

The films produced in this way also have the same disadvantages as that products manufactured by the other two known processes.

The manufacturing process according to the invention allows casein as the base material to produce continuous sheets or ribbons of any length, thin and wide, to which the same physical properties as those made from cellulose mentioned above thin leaves, and which, moreover, give preference to the latter over the latter have that they are hardly combustible.

The method allows any application either of Labcaseins or of Acid caseins or a mixture of these two-

the species, a mixture that often results from poor casein manufacture result.

The production takes place according to the invention in three successive phases:

a) the conversion into colloidal dispersion,

b) the transfer of such solutions into a jelly and their drying and

ίο c) the treatment of the insoluble so obtained Products to improve their water permeability and malleability.

The conversion of the caseins into solution mentioned under a is intended to be as extensive as possible Secure molecular dispersion. For this purpose, the solution takes place in a (hereinafter referred to as dispersion liquid) Low density liquid that evaporates quickly and which, moreover, has a preference offers that the purification of the casein is made much easier by dialysis.

Low boiling alcohols provide what is required for the end result sought Properties.

In addition, the solution of the casein must be done by a chemical means, the one easy elimination of mineral salts and other casein impurities Dialysis permitted. For this purpose a solution of an alkaline salt, e.g. B. from Sodium carbonate is used.

Finally, it is according to the invention and contrary to those previously considered Types of conversion into solutions recognized the usefulness of the following work phases been:

i. violent oxidation at the beginning or in the course of dissolution by action of oxygen in statu nascendi,

2. Making it malleable by adding one at the same time as the oxidation Plasticizer,

3. Progressive and changing addition of the solvent and the dispersion liquid to avoid partial clotting, and

4. Simultaneous temperature increase in the autoclave up to 100 ° C.

The dispersion liquid in which the defatted casein is dissolved, can consist, for example, of the following mixture: 86 parts by volume of ethyl alcohol, 10 parts by volume Methyl alcohol, 3.6 parts by volume propyl alcohol, 0.3 parts by volume pure glycerine and 0.1 part by volume Terpinol.

The solvent can consist of a solution of sodium carbonate in distilled water, in a ratio of 235 g of sodium carbonate to 1 water.

An example of casein dispersion is given:

After washing and drying, ι kg of casein are brought into the water bath of a double-walled, tightly closable mixer with 1.5 l of the dispersion liquid. The mixture is heated to a temperature of 40 ^° C. and stirred for about 5 minutes.

Now is introduced into the mixer 350 cm ³ of the alkaline salt solution, which was brought to a boil, and 10 cm ³ 3o ° / ₀ strength hydrogen peroxide solution.

After about 3 minutes continuous stirring the temperature is raised to 60 ⁰ C, and there are again introduced 1.4 1 of 80 to go ° C heated dispersion liquid, then stirred for 5 minutes and then 0.3 1 'of the boiling alkaline salt solution, and 3 cm ³ 3o ° / ₀ strength hydrogen peroxide solution was added.

At without interruption erfolgendem stirring continues after 3 minutes after the temperature has reached 70 ° C, 1.3 1 of the dispersion liquid of 80 to 90 ⁰ C, and after a further 5 minutes 0.2501 ^S 5 the boiling alkaline salt solution, and 6 cm ³ 30 ° / _o strength hydrogen peroxide solution. The same procedure is followed after about

3 minutes at a temperature of 80 ⁰ C repeated, with 1.2 1 of the dispersion liquid, 0.1 1 of the alkaline salt solution and

4 cm ^{8 of} hydrogen peroxide solution are added.

Finally, at 90 ⁰ C of 1.11 and 0.8501 Disparsionsflüssigkeit distilled boiling water are added.

The mixture is then for about

Heated to 100 ° C for 5 minutes.

The cooling is now carried out by water flowing in the double jacket.

The solution is then withdrawn and clarified by decantation so that a completely transparent one and, if necessary, depending on the type of caseins used results in a slightly yellow or colorless liquid. With another treatment the yellow color can be removed with hydrogen peroxide.

The residue can be nitrated in a centrifugal machine.

The casein solution prepared in this way can be stored in closed containers for any length of time will.

In this form it is for the second manufacturing phase, namely for casting, for the "5 Transfer to a jelly and ready to be hardened by heat.

This second work phase listed under b is characterized by the following:

i. If necessary, the solutions obtained in phase a are electrolyzed, whereby at the same time with a 10- to 200 / oigen

Dehydration of the product a cleaning by precipitation on the cathode and the Adjustment of the hydrogen ion concentration to the. isoelectric point of casein is effected.

2. If a solution of a coagulant such as z. B. of hexamethylenetetramine, formaldehyde, tannic acid and especially trioxymethylene, Introduced in an appropriate alcohol, when the liquid is evaporated, a transparent one is obtained Jelly which slowly hardens on contact with air and drying with heat;

3. This transfer into a jelly can be slowed down or accelerated at will by changing the temperature, the concentration or the branch of the solvent or by adding appropriately selected auxiliaries to the coagulants.

4. The acidification of the liquid before it solidifies ensures that which is produced afterwards Products are more impermeable to water.

The mixture, which slowly solidifies into a jelly, becomes completely smooth Area, e.g. B. on a glass panel or better on a nickel-plated or with a chrome coating provided sheet metal, cast, which performs a progressive movement, this is how it is formed a membrane on the surface as it solidifies, thereby hardening it can be accelerated by placing it in a room of higher temperature on its support can happen in the negative pressure. Then the sheet or the Skin can be separated easily. The thickness of the skin is controlled by the pouring device.

The skin is completely homogeneous, transparent and colorless.

A casting table machine for continuous casting allows continuous casting Tapes.

The addition of possibly soluble colorings or other additives, z. B. the oriental essence, allowed to the original casein solution, skins of any To achieve color tones.

11 of those obtained in the above-mentioned manner For example, casein solution can be treated as follows:

Electrolysis under 12 volts and 0.25 amps for 18 hours and at a temperature of 30 ^° C.

Adding a warm solution of S ° j _o Igei hydrochloric acid - 20 cm ³ - in methyl alcohol.
Dilution of the solution to a density of 0.920 by adding hot methyl alcohol.

Then, addition of 50 cm ³ of a basic solution of trioxymethylene in methyl alcohol (obtained by heating deSl mixture in the presence of a trace of potassium hydroxide), which is 0.1 ° / ₀ glycerol added for the purpose of slowing down the impact.

The mixture thus obtained allows the production of a sufficiently strong skin in one Period of 5 minutes after casting, at a vacuum of 100 mm and one Temperature of 80 ° C.

The skin obtained in this way can then undergo a treatment to ensure water impermeability and moldability, this treatment forming the third manufacturing phase.

This treatment under c is based on the following characteristics:

1. the hardening effect of certain organic liquids, in particular by Butyl alcohol, propyl alcohol, isoamyl alcohol, acetone, gasoline,

2. the partial dissolution of the skin surface by acids, especially by glacial acetic acid,

3. making the treated skin malleable by impregnation with plasticizing agents Substances, for example with acetin, triacetin, eugenol, cyclohexanol, glycerin, go Glycol, amyl acetate, butyl acetate, etc.

The working method is that the skin through a regular mechanical Drive is directed one after the other into the following baths, for example the following Composition have:

I. Acetone.

II. Acieton-5 volumes, acetic acid-4 volumes, glycerin-i volume.

III. Butyl alcohol-8 volumes, formic acid-i Volume, triacetin-i volume.

Baths II and III can be mixed.

The Bad-I, e.g. B. with an acetone content, has the purpose of partially hardening the membrane. If you stay too long in this Bad, the film is easily brittle. The skin pre-hardened in this way then becomes the baths II and III fed, in which it is softened again and superficially dissolved; due to the partial dissolution the skin receives a cohesive, smooth, pore-free surface. The movie will also made impermeable by this treatment. The action of acetone (bath 1) prevents a deeper softening and dissolution of the membrane, which then occur if the film were to be fed immediately to baths II and III without pretreatment in bath I.

The length of time and the amount of time left in the baths depend on the thickness of the skin. At a thickness

of ο, οΐ mm is enough - ι minute for each Bath.

The skin is then completely dried in a stream of hot air, which the im S absorbs excess solvent, etc., so that they can be used again can. When drying, the skin temperature can gradually increase from 30 to 60 ° C will. The drying time is for

ίο a skin 0.01 mm thick for about 5 minutes and increases with it.

The hot calendering of the thin sheets thus obtained allows their To increase strength in water even further.

It also allows the foils of all types with the use of appropriate cylinders to be subjected to pressing and printing work.

Claims (6)

Patent claims: i. Process for the production of films from a casein solution based on. one The surface is poured out and solidified, characterized in that the appropriately previously washed, taking defatted and dried casein in a low boiling alcohol Addition of a plasticizer and an alkaline salt, in particular sodium carbonate, optionally under gradual increase in temperature, is dissolved, whereupon the precipitates that may have arisen z. B. separated by filtration. 2. The method according to claim 1, characterized in that alcohol and alkaline salt can be applied repeatedly and alternately. 3. The method according to claims 1 and 2, characterized in that the alcoholic casein solution with oxidizing agents, especially hydrogen peroxide, is treated. 4. Process according to claims 1 to 3, characterized by the addition a coagulating agent for the alcoholic casein solution, which prevents the formation of the jelly after partial evaporation of the Alcohol, whereby a substance regulating the rate of solidification, e.g. an acid, can be added. 5. The method according to claims 1 • to 4, characterized in that the alcoholic casein solution is electrolyzed. 6. Aftertreatment of the films obtained according to claims 1 to 5, thereby characterized in that one successively baths of a curing agent, a solvent and a plasticizer allowed to act.