DE1720051A1 - Process for the production of films and foils from film-forming solutions - Google Patents

Description

AGFA-GEVAERTAG

PATENT DEPARTMENT LEVERKUSEN

18. J »

Process for the production of films and foils from film-forming solutions

The invention relates to a process for the production of % films or polien from a film-forming solution. It relates in detail to the material used to produce a high-gloss surface, hereinafter referred to as the casting base, to which the film-forming solution is applied and from which the film is peeled off.

It is known to manufacture films and foils by pouring a film-forming solution, for example a solution of cellulose triacetate on a rotating metal drum or on an endless metal belt in a film casting machine. After evaporation of the solvent or the mixture of solvents, the resulting film adheres firmly to its base, so that it is difficult to to detach the film from it without permanent deformation.

In order to avoid this disadvantage, the drum or the endless belt is coated. The shift can only take off such connections are made after the

109821/1973

AG 20 5

Dry a very smooth and high-gloss surface form. In addition, these compounds are said to be insoluble and resistant to swelling in the organic be solvents that are commonly used for the preparation of the film-forming solutions. Simultaneously should the repellent effect of the casting base against the film-forming system must be relatively large, so that the resulting film can be peeled off easily and without permanent deformation leaves. If the compounds used to produce the casting base have the properties just mentioned do not have by nature, it is necessary to produce them afterwards through a special treatment.

The metal drums or endless belts of film casting machines are usually made with a pouring pad made of cellulose acetate equipped. The cellulose acetate film adheres firmly on the drum or the endless belt and dries with a high-gloss surface. To the casting pad to give the desired repellent properties to the film-forming solution and its solubility and to reduce the tendency to swell in organic solvents, the cellulose acetate layer is superficially treated with alkali hydrolyzed.

If a film-forming solution is applied to a casting substrate treated in this way, then the film has after evaporation of the solvent or the mixture of solvents is not the same thickness over its entire width. As a result of evaporation of the solvent, it pulls itself out the film-forming mass together towards the center of the film so that the edges become thinner. The tension of the film

BATH ORIGINAL

in the moment of separation from the casting base also causes the film to stretch to a greater or lesser extent, which naturally occurs more strongly along the thinner edges. This can cause the film to tear. Furthermore, parts of the film that stick to the casting pad can damage the extremely sensitive surface of the casting pad to the point of uselessness.

The object of the invention is to besehrieben a casting pad, which is free from the disadvantages mentioned, and which through

Applying a very thin layer of a Werner ¹ see chromium complex salt on the hydrolyzed CelVuloseaceat- & layer can be produced.

According to the invention, this object is achieved by a method which consists of a metal carrier with a solution of cellulose triaceate to coat, to evaporate the solvent, the cellulose acetate layer formed in a known manner to hydrolyze on the surface and finally to apply a top coat. This procedure is characterized by that a solution of a Wernertehen chromium complex salt in an organic " Solvent or used in a mixture of water and an organic solvent miscible with Vaeser

- * is, in which the chromium complex salt is a trivalent chromium o

*? atom, to which the carboxyl groups are coordinated _, and the solution is applied to the surface hydrolyzed - »CelIuIοseaceatschicht in such a way that a 0.01 / U co '

up to 5 / U thickness of the top layer and that the top layer

is heated to about 50 ⁰ C to a firm bond of the cover layer to the hydrolyzed cellulose acetate surface AG 205 - 3 -

to make sure.

The Werner * see chromium complex salts, hereinafter referred to as chromium complex salts, are compounds in which a chromium atom is coordinated to a carboxyl group. the Carboxyl group can become a monobasic organic acid include, for example, acrylic acid, methacrylic acid, stearic acid, palm! tinic acid and lauric acid, the long-chain Carboxylic acids give the best results. Other carboxylic acids suitable for complex formation are, for example, substituted carboxylic acids, such as p-aminobenzoic acid, Cyanoacetic acid and mercaptoacetic acid. As an example for a dicarboxylic acid is called maleic acid. Fluorinated aliphatic carboxylic acids can also be used as complexing agents be used. The preparation of such chromium complexes is generally known and is described, for example, in US Pat. No. 2,273,040.

The method according to the invention gives very good results with chromium complex salts in which an acid residue 1 to Chromium groups come.

Suitable solvents for the chromium complex salts are, for example, methanol, ethanol, isopnanol, acetone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether with water.

Although Vasser is a good and cheap solvent for the chromium complex salts, it is the only solution Use some cons. It has such a large surface tension that uniform wetting of the surface hydrolyzing cellulose acetate layer with the chromium

AQ 205 -4- 109821/1973

complex reallocation is not possible. The surface tension causes so-called wetting errors, that is, some areas of the hydrolyzed cellulose acetate surface remain uncovered. To avoid such errors, the solution is mixed with a water-miscible organic solvent, e.g. with methanol, ethanol, isopropanol, acetone, ethylene glycol monomethyl ether and ethylene glycol monoethyl ether. Good results are obtained if the solution is at least 10 Jt contains organic solvent based on the total amount of water and organic solvents. Preferred a mixture of approximately 60 ^ water and 40 Jt organic solvent. The chromium complex salts are expediently used in very low concentrations, that is, less than 0.5 g of chromium complex salt are used per liter of solvent mixture (water / organic Solvent) is used. If higher concentrations are used, the smoothness of the gelulose acetate surface suffers Damage so that the chromium complex layer can no longer be applied with a uniform layer thickness. It is It is therefore advisable to use a very dilute solution of the chromium complex salt as an extremely thin layer on the hydrolyzed cellulose acetate surface to apply. The drying time of such a thin layer is then extremely short, so that

- »Movement of the pests under the influence of the surface

<0 tension of the water is no longer possible and the danger oo

^ The formation of grooves or craters is thus eliminated.

^ j In the manner described here, the high gloss

properties of the hydrolyzed cellulose acetate surface

with the repellent properties of the thin layer of chromium complex salt combine. Optimal results are achieved with 205 _ 5 -

Leakage layers with a thickness between 0.01 / u and 5 / u are achieved.

After the chromium complex salt layer is mounted on the hydrolyzed Celluloseacetatoberfläche, the casting support for a short time is heated to about 50 ⁰ C, to provide a good bond between the hydrolyzed surface of the cover layer and safely au. In most cases the temperature and time used for the trooknur ^ of the sea are sufficient for this. In special cases, however, it may be appropriate to extend the heating time to an hour or more.

The application of the chromium complex solution to the hydrolyzed cellulose acetate surface can usually take place, for example, by rolling on, by dipping or by knife-coating. It is only necessary to ensure that the layer has a thickness of 0.01 / U to 5 / U after drying.

The amount of chromium complex salt applied per unit area naturally depends on the concentration of the salt in the solution and on the amount of the casting solution. In addition, the concentration depends on the coating system used Alze on the speed of> ^T and the routierenden

_ * Drum or endless belt. It also hangs

co from the mutual distance between these two elements and from the

^ Number of layers applied. That means ^ that the Il concentration of the chromium complex solution on the casting machine

-j needs to be matched. If the speed of the VaIze

and the casting machine is small, and if the distance between the two elements is approximately 0.1 mm, then the concentration of the chromium complex salt can be less than AQ 2Qg - 6 -

ale 1 g per liter of solvent mixture. In one case , the coating can be carried out in two to four operations.

The repellent effect of the thin chromium complex layer on the film-forming solution is so strong that the film can be removed from the casting machine with a higher solvent content without the risk of streaking. ER beyond 'the beer described method enables the use of higher-casting speeds.

The beginning and end of the coating process are visibly marked as lines on the layer. In view of the extremely small thickness of the chromium complex layer, these lines cannot be polished away. In order to overcome this disadvantage, the coating process is started with a pure solvent mixture. In the storage container, this pure mixture is gradually * replaced by the chromium complex salt solution. At the end of the coating process, the same measure is repeated in reverse, so that finally a pure solvent mixture is applied. With this method of operation it is no longer possible to recognize a beginning or an end of the chromium complex salt layer. The replacement of the

_ ^ pure solvent mixtures through the chromium complex salt solution

to be increased in concentration with the help of a pump system

N) executed. Once the required solvent concentration

"■" * is reached, the pump system is used to distribute the solution ί2 evenly over the entire width of the casting path and to keep the level of the solution in the path exactly constant.

AG 205 - - 7 -

If the chromium complex layer is specially designed to prevent the edges of the film from being torn out, and when on one If no particular value is attached to the increased repellent effect of the casting base, then it may be sufficient that both sides of the hydrolyzed cellulose acetate surface to be coated with a narrow strip of chromium complex according to the present invention.

The casting pad described below is for manufacturing of films from solutions of film-forming polymeric materials in organic solvents. Such film-forming Materials are cellulose triacetate, polycarbonate, polyphenylene oxide and polyester, such as the copolyester of Isophthalic acid * terephthalic acid and 2,2-bis (4-hydroxyphenyl) propane. The only requirement is that the film-forming polymer Material is soluble in an organic solvent at normal temperature.

Example 1;

On the endless belt of a film casting machine, a C «llulos · - acetate layer attached and hydrolyzed on the surface in a known manner.

It is then applied to the hydrolyzed cellulose acetate surface a mixture of water and ethanol (60t 40). This pure solvent mixture is in the storage container With the help of a pump system, duroh gradually replaces the

-β-

/ ι 01 $ 211 / ft Ό

Solution of a ChPOiHkOmPIeXSaIZeS ₁ in the same solvent mixture of water and ethanol (60:40) in which a chromium atom is coordinated to methacrylic acid. In this case, 1 g of the chromium complex is ^{dissolved in 1000 cm 5 of} the solvent mixture.

The application roller is placed so that about 100 enr the

ρ
Solution to be applied per m. The resulting layer has a thickness of approximately 1 / U, dries quickly and has neither craters nor grooves.

When the endless belt is provided with a layer of the Chromkompltx ·· ™ , the coating solution is applied in stages by the pump system using a pure solvent mixture consisting of water and ethanol. This measure avoids the occurrence of line-shaped markings at the ^AT * f> ^w g ■ and at the end of the chromium complex layer.

The endless belt is finally heated for 2 hours in an air stream at 5O ⁰ C to produce good adhesion between the chromium complex layer and the Celluloseacetatoberfläche. -

If the casting base thus produced is now coated in a known manner with a cellulose triacetate and that

^ Solvent partially evaporated, so the resulting

φ PiIm earlier than usual and without cracks or deformations

Remove Ni again.

co example 2:

The procedure described in Example 1 is repeated with the exception that a p-aminobenzoic acid containing

AG 205 - 9 -. "

Chromium complex is used. 0.5 g of this chromium complex salt dissolve in 1000 cnr of a mixture of water and ethanol p0: 80).

According to this example, a casting pad is obtained from the a cellulose triacetate film without being damaged or to be deformed can be peeled off.

Example 3:

The procedure described in Example 1 is repeated. The chromium complex salt used this time contains mercaptoacetic acid bound chromium and is e.g. a mercaptoacetate chromium (III) chloride. 0.5 g of this complex salt are dissolved in 1000 cnr of a mixture of water and ethanol (60:40) solved.

From the casting base produced according to this example, a cellulotriacetate film can be removed faster than usual and without tear to be deducted.

Example 4:

The procedure described in Example 1 is modified as follows. The solvent used is a mixture of water and ethanol (50:50) and the chromium complex salt a cyanoacrylic acid derivative, e.g. a cyanoacrylatochrome (IH) -

, ν) chloride.

_(JO The Beschiohtungssystem is adjusted so that a layer is obtained yu with a Dioke of about 2 after u> drying. This layer is then heated with hot air for 1 hour at 55 ⁰ C In this case, a die-pad from the calibration results in a AQ 205th - 10 -

Cellulose triacetate pilm faster than usual and without too tear off can be peeled off.

Example 5?

The procedure described in Example 1 is repeated. A stearic acid derivative is used as the chromium complex salt, namely stearatochrome (III) chloride, which can be found in 1000 cm of the solution / agent mixture dissolves.

Is prepared from this LöBung an approximately 1 / U thick layer side and heated it for 1 hour at 50 ⁰ C. From the thus prepared casting support, a cellulose triacetate Piim faster than usual and be withdrawn without tearing.

Example 6;

The procedure described in Example 1 is repeated. A palmitic acid derivative is used as a chromium complex, and 1 g of this is dissolved in 1000 cnr of the solvent mixture. A cellulose triacetate pilm can easily be peeled off this casting base without tearing at the edges.

Example 7t

Example 6 is repeated with palmitatochrome (III) chloride,

- * the one with 0.5 g per 1000 cm in a Waeeer / Athanol-Geaiach ο

<° (50:50) solves. The casting base produced from it is oo

^ Heated to 60 ⁰ C for 30 minutes.

^ j A cellulose triacetate pilm can be made from this casting pad

easily peel off without tearing.

AG 205 - 11 -

Example 8;

On the endless belt of a pilm molding machine a Cellulose acetate layer attached and known Way hydrolyzed on the surface.

In the manner described in Example 1, the solution is now on the hydrolyzed cellulose acetate surface Stearic acid chromium complex salt applied. The hardening the top layer is carried out as described in Example 1.

The solution of a polycarbonate of 2,2-Bie (4-hydroxyphenyl) propane in methylene chloride is applied to the hardened chromium complex layer (50 g of the polymer per 100 cm of solvent).

The chromium complex salt layer causes the film to grow can be removed from the machine without difficulty.

Example 9;

Example 8 is repeated, but this time the chromium complex salt layer is coated with a solution of polyphenylene oxide in chloroform (80 g of the polymer to 100 ca * solvent). The film produced from this does not adhere to the casting base and can easily be peeled off from it

oo be.

- * example 10;

Example 8 is repeated, but this time the chromium complex salt layer is coated with a solution of a copolyester of isophthalic acid and terephthalic acid (75:25) with 2,2-B1 (4 ~

A-G 205 - 12 -

hydroxyphenyl) propane (25 g of the polymer in 100 enr solvent). The film can very easily be peeled off the casting pad.

AG 205 - 13 -

Claims (1)

Expectations; O4 1.) Process for the production of a casting base by coating a metal support with a solution of cellulose acetate, evaporation of the solvent, surface hydrolysis of the cellulose acetate layer and application of a top layer, characterized in that a solution of a Wenertehen chromium complex salt in an organic solvent or for the production of the top layer is used in a mixture of water and a water-miscible organic solvent, wherein the chromium complex salt contains a trivalent chromium atom to which carboxyl groups are coordinated and wherein the solution is applied to the surface hydrolyzed cellulose acetate layer in such a way that an O _f O1 / U bis 5 / U thick top layer is formed and that the top layer is ^{heated to about 50 0} C in order to bring about a firm bond of the top layer to the hydrolyzed cellulose acetate surface. 2.) The method according to claim 1, characterized in that the Wernertehe-Chromkomplexsalζ dissolved in an organic solvent from the G _{r group} methanol, isopropanol, acetone, ethyl englykolmonoäthyl ether and ethyl englykolmonomethyl ether ^ is applied.
ο ro 3.) Method according to claim 1, characterized by the *** application of the Werner tehen-Chromkomplexsal * es, dissolved in a mixture of water and an organic solvent miscible with Va te from the group consisting of methanol, ethanol, Ieopropamol , Acetone, ethyl glycol monoethyl ether and ethylan glykolaonomethyl ether, the mixture at least 10 % 4-G 205 - 14 - * , Ή ZDOSi organic solvent miscible with water
on the total volume of the mixture. 4.) Process according to claims 1 to 3, characterized
by using a solution containing 1 g of the chromium complex salt in 1000 cm of solvent or solvent mixture. AG 205 - 15 - 109821/1973