JP2717697B2 - Method for producing cellulose triacetate film - Google Patents

Description

The present invention relates to a method for producing a cellulose triacetate film, and more particularly, to a method for coloring a cellulose triacetate film.

[Background of the Invention]

Conventionally, the following method has been used as a coloring method for producing a colored cellulose triacetate film, for example, a medical X-ray film, a black and white general film, and the like.

(1) A method in which a dye solution dissolved in a solvent is directly added to a kettle in which a solution of cellulose triacetate (hereinafter referred to as dope) is dissolved. (2) A method in which a dye solution is applied directly onto a non-colored cellulose triacetate film, or a liquid in which the dye is dispersed in a binder such as gelatin.
(3) A method of simultaneously casting a dope and a dye solution or a dye dispersion using a multilayer simultaneous extrusion die.

However, each of these methods has the following problems.

That is, in the method (1), there is a possibility that the dye concentration changes for each batch. Regarding (2), there is a possibility that the coating is uneven, and as for (3), the suppression of light piping by coloring only the surface layer may be insufficient. Here, the light piping is sometimes referred to as "chaka", but refers to a phenomenon in which, for example, in a 35 mm general film, light passes through a base film from a patrone telem, reaches a certain distance, and causes fogging. This is the same in (2). (2),
In the method (3), the production process is troublesome, and there is a problem in coloring, that is, the production stability of the coloring concentration as a colored cellulose triacetate film in the conventional method.

[Object of the invention]

In view of the above problems, an object of the present invention is to firstly eliminate the unevenness and unevenness of the coloring concentration in the colored cellulose triacetate film and improve the production stability. A second object is to shorten the time for color change of coloring and to improve production efficiency.

[Configuration of the invention]

In view of the above problems, an object of the present invention is to prepare a colored cellulose triacetate film, add a dye solution to a cellulose triacetate solution in-line, and measure the color density in a pipeline for transporting the mixed solution. This is achieved by a method for producing a cellulose triacetate film in which the amount of the dye solution added is controlled to a specified concentration.

 Hereinafter, the present invention will be described in detail.

FIG. 1 is a sectional view showing an example of a manufacturing apparatus according to the present invention. The prepared dope solution is supplied from the storage tank 1a to the gear pump 2a.
, The amount of which is controlled by information on the speed of the support of the casting apparatus. Next, if necessary, the dope concentration is measured by the densitometer 3a, and then the dye solution sent from the dye solution storage tank 1b via the pump 2b is added to the dope transport pipe, and the mixture is mixed by the static type in-pipe mixer 4. If necessary, the dye concentration may be measured by the densitometer 3b. Next, after measuring the color density after mixing by the densitometer 3c, the mixed liquid is sent to a casting device via a die and cast. At this time, the amount of the dye solution is adjusted by the delivery amount of the gear pump 2b controlled by the information of the color density by the densitometer 3c. In the above configuration, the concentration meters 3a and 3b are preferably provided, but need not be provided. The series of the dye solution is not limited to only one series, and may have multiple series.

The casting is a stainless steel belt 8 stretched between drums 6 and 7.
A mixed solution of the above-mentioned dope and the dye is applied through a die 5. When the film has been dried to some extent to form a film, the film is dried by a roller 9 by a peeling and drying device 10 and wound around a winding device 11.

〔Example〕

Hereinafter, the effects of the present invention will be specifically illustrated by examples.

Example 1 A cellulose triacetate film was produced according to the following formulation. At this time, the dope and the dye solution are mixed in a conventional mixing tank, and the mixture is passed through a casting die.
In the case of manufacturing using the apparatus shown in the figure, the density unevenness and the operation time were compared.

Dope Triacetate 100 parts Triphenyl phosphate 10 parts Methylene chloride 400 parts Methanol 100 parts Dye solution Triacetate cellulose 100 parts Triphenyl phosphate 10 parts Methylene chloride 1900 parts Methanol 100 parts Dye Nigrosine (CI 50415) 4 Part Dope of the above formulation 1 / min, dye solution 0.01 / min
, And a coloring base having a thickness of 125 μm was prepared while controlling the amount of liquid supplied so that the color density of the mixed solution became a specified value.

The concentration was measured for each of the 10 batches of the coloring base. In addition, 10 batches were prepared by a conventional method, that is, a method in which a dope and a dye solution were directly mixed in an adjusting pot, and a colored base was similarly prepared. With respect to these two, the average value measured at 10 locations for each batch was compared for the concentration and the variation (σ) averaged for 10 batches. The results are shown in Table 1 below.

From the results shown in Table 1, in the case of the present invention, the color density was remarkably stable as compared with the conventional method. In addition, the light-piping effect was confirmed by applying the photosensitive material to the base according to the present invention, but it was satisfactory.

Example 2 The experiment of changing the dye solution, that is, changing the color, was performed according to the prescription of Example 1, and the required time was measured. As a result, it took 3 hours and 12 minutes in the case of the conventional method, but in the method of the present invention, the change could be made in 17 minutes, the change was made very quickly, and the productivity was remarkably improved.

〔The invention's effect〕

According to the present invention, there is provided a method for producing cellulose triacetate, which eliminates variations and unevenness in coloring concentration in a colored cellulose triacetate film, improves production stability, shortens the color change time of coloring, and improves production efficiency. Was completed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one example of a manufacturing apparatus according to the present invention. 1a: dope storage tank, 1b: dye storage tank 2a, 2b: pump 3a, 3b, 3c: densitometer 4: static type in-tube mixer 5: die, 6, 7, drum 8: stainless steel belt, 9: roller 10: dryer , 11: Winding device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B29L 7:00 C08L 1:00

Claims (1)

(57) [Claims] In producing a colored cellulose triacetate film, a dye solution is added and mixed in-line to a cellulose triacetate solution, and the color density is measured in a pipeline for transporting the mixed solution to obtain a specified density. A method for producing a cellulose triacetate film in which the amount of a dye solution added is controlled.