JPH02276830A - Production of cellulose triacetate film - Google Patents

Abstract

PURPOSE:To efficiently obtain the subject film without scattering of concentration of color, etc., by in-line adding coloring matter solution to cellulose triacetate solution, mixing, measuring concentration of color in pipe line transferring said mixed solution and controlling adding amount. CONSTITUTION:Conditioned dope solution is fed into a static pipe mixer 4 from a storing tank 1a with controlling flow amount by information of supporter speed of a casting device and coloring matter solution fed from a coloring matter solution-storing tank 1b is added to the dope solution at the place and mixed, then concentration of color after mixing is measured by a densitometer 3C (feeding amount of the coloring matter solution is adjusted by a gear pump 2b according to information of concentration of color with the densitometer 3C), thus the dope is shaped to filmy and dried, then wound to afford the aimed film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] 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 methods have been used as a coloring method for producing colored cellulose triacetate films, such as medical X-ray films, general monochrome films, and the like.

(1) A method in which a dye solution dissolved in a solvent is directly added to a pot containing a solution of cellulose triacetate (hereinafter referred to as dope). (2) A method in which a dye solution is applied directly onto an uncolored cellulose triacetate film, or a liquid in which a dye is dispersed in a binder such as gelatin is applied. (3
) A method in which dope and dye solution or dye dispersion are simultaneously cast using a multilayer coextrusion die.

However, each of these methods has the following problems.

That is, in the method (1), the dye concentration may vary from batch to batch. Regarding (2), there is a possibility of uneven coating, and regarding (3), there is a possibility that light piping suppression by coloring only the surface layer may be insufficient. Here, light piping, which is sometimes commonly referred to as char force, refers to a phenomenon in which, for example, in a general film for 35mo+, light passes through the base film from a television cartridge and reaches a certain distance, causing fogging.

This also applies to (2). Furthermore, the methods (2) and (3) require a lot of effort in the manufacturing process, and there are problems with coloring, that is, with the conventional methods, the manufacturing stability of the color density as a colored cellulose triacetate film.

[Purpose of the invention]

In view of the above-mentioned problems, the first object of the present invention is to eliminate variations and unevenness in color density in a colored cellulose triacetate film and to improve production stability.

The second purpose is to shorten the time for changing colors and improve production efficiency.

[Structure of the invention]

In order to solve the above-mentioned problems, an object of the present invention is to add and mix a dye solution to a cellulose triacetate solution in-line when manufacturing a colored cellulose triacetate film, and measure the color density in a pipeline that transports 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 achieve a specified concentration.

The present invention will be explained in detail below.

FIG. 1 is a sectional view showing an example of a manufacturing apparatus according to the present invention. The prepared dope liquid is transferred from the storage tank 1a to the gear pump 2.
a, the amount of which is controlled by information on the support speed of the casting device.

Next, after measuring the dope concentration using a densitometer 3a if necessary, a dye solution sent from a dye solution storage tank 1b via a pump 2b is added to the dope transport piping and mixed by a static in-tube mixer 4. Incidentally, if necessary, the dye concentration may be measured with a densitometer 3b.

Next, after measuring the color density after mixing using a 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, which is controlled by the color density information from the densitometer 30. In the above configuration, it is preferable to install the concentration meters 3a and 3b, but they may not be provided. Also, the series of dye solutions are l
It is not limited to only one series, and may have multiple series.

Casting is carried out using a stainless steel belt 8 stretched between drums 6 and 7.
A mixture of the dope and the dye is applied to the top through a die 5. When it has dried to some extent to form a film, it is stripped off from the belt by rollers 9, dried in a drying device IO, and wound up in 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 recipe. At this time, we compared the concentration unevenness and working time between the conventional method of mixing the dope and dye liquid in a mixing tank and flowing it into a casting die, and the case of manufacturing using the apparatus shown in FIG. 1 of the present invention. Let's go.

Doped cellulose triacetate 100 parts triphenyl 7-osphate 10 parts methylene chloride 400 parts methanol
100 parts dye solution cellulose triacetate 100 parts triphenyl 7-osphate 10ffi methylene chloride 1900 parts methanol
100 parts Dye Nigrosine (CI 504
15) 4 parts of the above prescription dope at IQ/min
A colored base having a thickness of 125 μm was prepared by mixing the dye solution at a flow rate of O, OIQ/win, and controlling the amount of liquid fed so that the color density of the mixed solution became a specified value.

The density was measured for each of 10 batches of colored bases. In addition, 10 batches were prepared using a conventional method, that is, a method of directly mixing Dogu and a dye solution in a mixing pot, and colored bases were similarly created. For both, the average values measured at 10 locations for each batch were further averaged over the IO batches, and the concentrations and variations (j) were compared. The results are shown in Table 1 below. Cells that reduce processing time and improve production efficiency From the results shown in Table 1, the color density was much more stable in the case of the present invention than in the conventional method. Also, the light-piping effect was confirmed by applying a light-sensitive material to the base according to the present invention, and it was found to be sufficiently satisfactory.

Example 2 Using the recipe of Example 1, an experiment was conducted to change the dye solution, that is, change the color, and the time required for the change was measured. As a result, the conventional method required 3 hours and 12 minutes, but with the method of the present invention, the change could be made in 17 minutes, making the change very quick and productivity significantly improved.

〔Effect of the invention〕

EFFECTS OF THE INVENTION According to the present invention, it was possible to eliminate variations and unevenness in coloring density in a colored cellulose triacetate film, improve production stability, and provide a method for producing a color-changeable low triacetate.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a manufacturing apparatus according to the present invention. la: dope storage tank 1b dichromatic storage tank 2a, 2b:
Pumps 3a, 3b, 3c: Density meter 4: Stationary in-tube mixer 5: Die 6, 7: Drum 8 stainless steel belt 9: Roller

Claims (1)

[Claims] When producing a colored cellulose triacetate film, a dye solution is added and mixed in-line to the cellulose triacetate solution, the color density is measured in the pipeline that transports the mixed solution, and the dye solution is added to a specified concentration. A method for producing a cellulose triacetate film that controls the amount.