JPS62115034A - Production of regenerated cellulose film - Google Patents

Abstract

PURPOSE:To produce a regenerated cellulose film having a well-controlled fractionation MW, by casting cellulose acetate dissolved in a solvent mixture of a poor solvent and a specified good solvent and removing acetic acid from the resulting film. CONSTITUTION:A poor solvent (e.g., formamide) is mixed with a good solvent mixture of acetylacetone and other good solvent (e.g., 1,4-dioxane) in a weight ratio of 1:0-1:9 in such a proportion as to give a weight ratio of 4:1-1:9 to obtain a solvent mixture. A soln. of 10-30wt% cellulose acetate in said solvent mixture is cast on a support having a mirror surface in a given casting thickness, and coagulated in an immersion bath to obtain a cellulose acetate film. The film is peeled from the support, wounded around a support such as a PP sheet, a PE sheet, etc., and acetic acid is removed. The film is washed with water and dried.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) More specifically, the present invention relates to a method for producing a regenerated cellulose membrane characterized by the solvent used during regeneration.

(Conventional technology) Regenerated cellulose membranes are hydrophilic and have excellent organic solvent resistance.
Membranes for the food industry as separation membranes with low adsorption properties.

Used as a medical separation membrane.

The method for producing this cellulose membrane involves dissolving cellulose in a cupric ammonia solution and casting it onto a mirror-like support.
There is a copper ammonia cellulose method in which cellulose is coagulated in an alkaline bath and thoroughly washed with acid and water to regenerate it into cellulose, or cellulose acetate is added with a plasticizer, melted into a film, extracted with the plasticizer, and then deaceticated. There is a method to obtain a regenerated cellulose membrane.

The cuprammonium cellulose method uses a highly concentrated solution (20 to 50
wt%) and it is difficult to form a membrane with a small pore size. Furthermore, cellulose cupric ammonia solutions have the disadvantage of being unstable unless they are protected from air and light and stored at low temperatures.

(Objective of the invention) In a method of obtaining a regenerated cellulose membrane by dissolving it in a mixed solvent with a solvent, forming a membrane, and then deaceticating it, it is possible to easily adjust the molecular weight cut-off by changing the type of acetylacetone added as a good solvent. The objective is to provide a regenerated cellulose membrane that can be controlled.

(Structure of the Invention) The present invention provides a method for forming a cellulose acetate membrane, deacetating it, and obtaining a regenerated cellulose membrane. By changing the amount of acetylacetone added as a good solvent, it is possible to easily achieve desired fractionation performance. An object of the present invention is to provide a regenerated cellulose membrane having the following properties.

The method of the present invention will be described below. First, cellulose acetate is dissolved in a mixed solvent of a good solvent and a poor solvent, left to stand, and degassed. At this time, a good solvent is acetylacetone or
Indicates a mixed solvent of acetylacetone and a good solvent other than acetylacetone.

Here, the cellulose acetate concentration is 10 wt% to 50 wt
% is appropriate; if the concentration is increased more than this, the water permeability will deteriorate and the membrane performance will deteriorate. Along with acetylacetone, 1,4-dioxa7,N is a good solvent that can be added.
-Methylpyrrolidone, tetrahydrofuran, acetone,
Dimethyl sulfoxide, etc. In particular, 1,4-dioxane and N-methylpyrrolidone are preferred in terms of boiling point, solubility, and the like. Poor solvents include formamide and ethyl cellosolve.

Water, ethyl alcohol, methyl alcohol are suitable.

The ratio of poor solvent to good solvent is preferably 4:1 to 1:9 by weight, and the ratio of acetylacetone to other good solvents is preferably 1:0 to 1: by weight. 9 is desirable. According to the present invention, it has become possible to easily control the molecular weight cutoff of the membrane in the range of about 10,000 to about 100,000. As the ratio of acetylacetone increases, a regenerated cellulose membrane with a smaller molecular weight fraction is produced.For example, the molecular weight fraction is fiI
In order to obtain a regenerated cellulose membrane with a diameter of φ or less, the h amount ratio of the poor solvent to the good solvent is 2:3 to 1:4, and the weight ratio of acetylacetone to other good solvents is between 20 and 1:1. That's fine.

Next, the dissolved and degassed cellulose acetate solution is cast onto a support on a mirror surface to a desired film thickness, and coagulated in a dipping bath to obtain a cellulose acetate film.

Here, suitable supports include glass plates, polypropylene sheets, and polyethylene sheets. B. Peel the obtained cellulose acetate membrane from the support, wrap it around a support such as a polypropylene sheet or polyethylene sheet, then deacetate the cellulose acetate membrane to obtain a regenerated cellulose membrane, wash with water, and dry to obtain a regenerated cellulose membrane. be able to.

(Effects of the Invention) As explained above, according to the present invention, asymmetric regenerated cellulose membranes with different molecular weight cutoffs can be obtained by changing the amount of acetylacetone added.

(Examples) The present invention will be further explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Cellulose acetate (manufactured by Eastman Kodak Company, degree of acetylation 398 α5%) 10009 formamide 1
After dissolving and degassing in a mixed solution of 600g and 1200g of acetylacetone and 12009g of 1,4-dioxane,
On a polypropylene sheet, the thickness is 1. It was cast at room temperature (25°C) so that it became OL, and then poured into pure water (water temperature 23°C).
to obtain a cellulose acetate membrane. This cellulose acetate membrane was peeled off from the polypropylene sheet and washed in pure water for 24 hours. After completion of washing, deacetic acid reaction was carried out in 1375% sodium hydroxide 200 for 48 hours, and after completion of the reaction, the product was washed again with pure water for 48 hours. After washing, it was immersed in a 10% glycerin solution for 24 hours. After glycerin treatment,
The membrane was dried to obtain a regenerated cellulose membrane. The physical properties of the obtained membrane are shown below.

Membrane thickness: 260 μm to 280 ttm Pure water permeation flow rate: 2 [L7 to 35.8 t/rrs”hrl Pressure: 1° Okg/1y4JJ) Toyo Filter Paper UHP-43 was used to measure the pure water permeation flow rate.

Rejection performance f) Chromium 0. IM, W, 1100)99
．． 9% inhibition vitamin B, +M, W, 130G)
&5% axis Example 2 Cellulose acetate (manufactured by Eastman Kodak, acetylated L59.B ± 15%) 2009 was dissolved in formamide 4
After dissolving and degassing in 00 g, acetylacetone 2009 and 1,4-dioxane 4009, a regenerated cellulose membrane was formed on a polypropylene sheet in the same manner as in Example 1. The physical properties of the obtained membrane are shown below.

Membrane thickness: 250μm~260μm Pure water permeation flow rate:
55.6~4591/w? -hr (pressure to kq/c
r@) Blocking performance; Albumin 1M, W, 68000)
100% inhibition cytochrome O+M, W, 13000)
750% inhibition of vitamin B1. +M, W, 1300)
50% Inhibition Example 5 After dissolving 200 g of cellulose acetate (manufactured by Eastman Kodak ■, degree of acetylation 39.8±α5%) in ethyl cellosolve 4009, acetylacetone' 500 g, and 1,4-dioxane 3009 and degassing it. , Examples 1 and 2
A regenerated cellulose membrane was formed by performing the same operation as above. The physical properties of the obtained membrane are shown below.

Membrane thickness: 260μm~270μm Pure water permeation flow rate:
IS, 5-21.5 t/rr/・hr (at pressurization of 1.0 to 9/c!) Closing performance: Alpmin (M, w
, 1OOQ) foo'R1JIJ:.

Cytochrome G (M, W, 130QQ) 95.5 (Vitami", Y stone (M, W, 1300) a2 Mosquito Example 4 Cellulose acetate (manufactured by Eastman Kodak ■, degree of acetylation 39.8 ± 15%) 20g formamide 40
9. After dissolving in acetylaceto Y609 and degassing, the same operations as in Examples 1.2 and 3 were performed to form a regenerated cellulose membrane. The physical properties of the obtained membrane are shown below.

Claims (1)

[Claims] (1) Adding a poor solvent and a good solvent to cellulose acetate,
The method of producing a regenerated cellulose membrane consists of mixing and dissolving the mixture, casting it on a support on a mirror surface, coagulating it in an immersion bath to obtain a cellulose acetate membrane, and then deacetating this membrane to obtain a regenerated cellulose membrane. A method for producing a regenerated cellulose membrane, the method comprising using acetylacetone or a mixed solvent of acetylacetone and a good solvent other than acetylacetone as a good solvent.