JPH01249106A - Hollow yarn module comprising porous regenerated cellulose - Google Patents

Abstract

PURPOSE:To decrease a degree of reduction of diameter of hollow part of a hollow yarn module, to reduce degree of clogging of the hollow yarn, and to attain thus fully exhibited filtration characteristics of the hollow yarn, by maintaining a degree of dispersion of the hollow yarn at >=2.5 in a stage of potting with polyurethane of bundled hollow yarn membrane comprising porous regenerated cellulose. CONSTITUTION:In a stage of potting of a bundled hollow yarn membrane comprising porous regenerated cellulose obtd. from a cupri-ammonium soln. of cellulose at both ends dipped in polyurethane, the degree of dispersion defined by =S/{pi(0.5Do)<2>Xn} is held at >=2.5, wherein S is an area(cm<2>) occupied by a hollow yarn bundle measured at an end face of polyurethane; Do is an outside diameter(cm) of the hollow yarn; n is a number of the hollow yarn. By this constitution, decrease of filtration capacity due to occurrence of reduction of diameter and clogging of a hollow yarn at a part thereof, which have been caused in the conventional process due to increase of volume of hollow yarn bundle having been fixed to an inside of a housing, dipped in water and swelled in a heat-sterilzation stage by being heated in a wet autoclave, is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to porous regenerated cellulose hollow fiber modules.

The "porous hollow fiber" in the present invention refers to a hollow fiber having a water flow rate average pore diameter of 10 to 11,000 nm.

The porous regenerated hollow fiber module obtained in the present invention is useful for separating and removing target components in liquid or gas mixtures containing water, and for concentrating them. It can also be used to remove viruses or bacteria including rickettsia, chlamydia, mycoplasma, etc. dispersed in an aqueous solution that dissolves proteins and electrolytes, or to separate and concentrate proteins from an aqueous solution containing microbial particles.

(Prior technology) Among the technologies for separating substances, research has been actively conducted on membrane separation technology as a means of separating micron-order substances such as ions, low-molecular substances, and suspended solids and fine particles in the liquid phase. It is. The biggest problem preventing commercialization of this type of technology on an economic scale is the low rate of material separation.

Since the substance separation rate depends on the membrane area, as the amount of substances to be treated increases, the membrane area must be increased, and with the normally used flat membrane, the size of the apparatus inevitably increases. This problem can be solved by separating substances using extremely thin hollow fibers, using the fiber wall surrounding the hollow part as a separation membrane, and by bundling a large number of these hollow fibers to form a substance separation part. ! This problem can be solved by increasing the effective membrane area of the membrane and downsizing the device. Fields in which membrane separation systems may become central in the future include: ■ Fields that require concentration, special preparation, and recovery at low temperatures (food, biochemical industries), ■ Fields that require sterility and dust-free operation (pharmaceuticals and Possible applications include: (therapeutic institutions, electronic industry field), ■ Concentrated recovery of trace amounts of expensive substances <W preload, heavy metal field), ■ Special small quantity separation field (pharmaceutical field), ■ Energy-intensive separation field (alternative to distillation), etc. As membranes used in these fields, there is an increasing need for hydrophilic membranes with large pores that are easy to handle.

Regenerated cellulose is a highly hydrophilic material. Regenerated cellulose has excellent organic solvent resistance and mechanical properties,
Also, unlike synthetic polymers, it is less toxic to living organisms. Therefore, the appearance of hollow fibers composed of regenerated cellulose and having a large average pore diameter was expected.

The present inventors first extruded a cellulose copper ammonia solution from an annular spinning spout, and in the process of coagulating, regenerating, and washing with water, the spinning stock solution was introduced from an outer annular spinning spout, and a coagulable liquid was added to a central part of the spinning stock solution. Discharge each from the spinning port,
Furthermore, by causing microphase separation before coagulation, we succeeded in producing porous regenerated cellulose hollow fibers having hollow portions that continuously penetrated the entire length of the fibers.

(Problems to be Solved by the Invention) In order to set this porous regenerated cellulose hollow fiber in a filtration module, first dry the hollow fiber, then use a urethane resin adhesive to The thread bundle must be secured within the housing. The molded filtration module is sterilized and shipped after passing through predetermined performance and safety tests. Sterilization methods include EOG sterilization, high-pressure steam sterilization, γ-ray sterilization, formalin sterilization, etc. However, in the case of regenerated cellulose, sterile water is not used inside the module from the viewpoint of preventing material deterioration and side effects of sterilants. It is most advantageous to autoclave the product in a state where it is filled with water.

However, a cellulose hollow fiber membrane fixed in a housing with an adhesive in a dry state swells during the process of being immersed in water and then heated in a wet autoclave, greatly expanding its volume. It is thought that part of the increased volume due to expansion of the membrane whose outer periphery is fixed in the housing with adhesive will move toward the hollow part, and as a result, the hollow part may shrink or become occluded. be.

The open fixed end of the hollow fiber membrane is a flow part for the liquid to be treated or a flow part for the filtrate, and if the hollow part shrinks or is blocked,
Naturally, the filtration performance as a module is greatly impaired.

This effect is particularly noticeable in liquids containing proteins of various sizes in plasma.

As described above, when a module is formed by bundling dry porous regenerated cellulose hollow fiber membranes and fixing them to a housing with an adhesive such as polyurethane, the relationship between the hollow fiber membranes and the fixing agent is If the hollow fiber membrane is molded by focusing only on adhesive properties and without paying special consideration to the dispersibility of the hollow fiber membrane that is embedded and fixed in the fixing agent, the hollow fiber membrane will swell with water during the wet autoclave sterilization process. Due to the increase in volume caused by this, some of the hollow portions of the hollow fiber bundle were shrunk or blocked, and the filtration performance of the module was greatly reduced.

(Means for Solving the Problems) Therefore, the present inventors focused on the relationship between the dispersibility of the porous regenerated cellulose hollow fiber membrane embedded in the fixing agent and the reduction or occlusion of the hollow part, and As a result of the study, the degree of dispersion of the hollow fiber membrane present in the fixing agent expressed by the following formula (1) was determined to be 2.5.
It has been found that by doing the above, it is possible to obtain a cellulose-featured hollow fiber membrane module with excellent filtration performance without substantially causing shrinkage or blockage of the hollow portions as in the past,
This invention has been made.

Dispersity = (1) π (%
D, )2xn In formula (1), S: Area occupied by the hollow fiber bundle on the urethane end face (Cm
2) (Area of the circle surrounding the hollow fiber bundle)D. = Outer diameter of hollow fiber (cm) n: Number of hollow fibers The reason why the phenomenon of shrinkage or blockage of the hollow portion due to swelling of the hollow fiber membrane with water is eliminated by improving the degree of dispersion is thought to be as follows.

In other words, when a cellulose hollow fiber expands in volume due to swelling, if there are no other hollow fibers in its immediate vicinity, the volume expansion force is evenly distributed and absorbed in the circumferential direction, and the hollow fiber membrane does not deform. do not have.

However, if there are other hollow fibers in the immediate vicinity, it becomes impossible to disperse the swelling force, resulting in deformation of the hollow part, which leads to shrinkage and occlusion. This can be understood from the fact that the hollow fibers at the outer edge of the hollow fiber bundle embedded in the polyurethane fixing agent do not become clogged.

It is also understandable that if the hollow fibers become clogged, the filtration capacity will naturally decrease. Before explaining the present invention with examples, definitions of technical terms (physical property values) used in this specification and methods for measuring them are shown below.

(Water flow rate average pore diameter) A porous hollow fiber module made of cellulose regenerated by the cuprammonium method was created, and in the module state, the amount of water flowing out of the hollow fiber was measured, and the water flow rate average pore diameter was determined from equation (2). Ta.

■(Outflow amount (mu/m1n) T: Thickness at I15 (μm) △P: Pressure difference (mmHg) A: Membrane area (m2) Prp: Porosity (-) μ: Water viscosity (cp) Porosity The ratio Prp was determined by equation (3) from the apparent density ρaw when swollen with water and the density pp of the polymer.

In the case of cellulose, ρ, , = 1561 was used.

Prp (%) = (1-ρaw/ρp)X100
(3) (Example) The present invention will be explained in more detail with reference to Examples below.

Example Cuprammonium method Porous regenerated cellulose hollow fiber membrane (inner diameter 2
50μm, IIiQ25um, II! A bundle of 500 pieces (water flow velocity average pore diameter of 30 nm, length 100 mm) was treated with a two-component mixed epoxy resin to seal the openings at both ends to 5 mm each. At that time, the diameter of the bundle is 8mm, 10mm, 11m.
m, 12 mm, and 14 mm, and the degree of dispersion was changed as shown in Table 1.

The sealed bundle was placed in a housing and embedded and fixed in polyurethane resin (MDI series manufactured by Nippon Polyurethane Co., Ltd.) using a centrifugal molding method. In order to open the sealed hollow fiber membranes at both ends of the housing, a portion of the urethane resin portion was cut with a cutter. Headers with silicone rubber O-rings were attached to both ends of the housing to form a module.

After washing the hollow fibers inside the module with ultrapure water, the module was placed in a sterilization bag while still being filled with ultrapure water, and heat sterilized in an autoclave at 120° C. for 20 minutes.

After the above operations, disassemble the module header and examine the hollow fiber membranes on the urethane cut surfaces at both ends of the housing using a microscope.
Observation was made with 0x magnification. Table 1 shows the ratio of the hollow fiber membranes whose hollow portions were reduced and those whose hollow portions were occluded. Furthermore, the filtration performance of each module was measured and evaluated under the following conditions.

Set the module in a constant temperature bath maintained at 37℃,
The amount of ultrapure water permeated was measured for 5 minutes at a pressure of 00 nmHH. The membrane area was calculated from the dimension of the hollow fibers, and from the amount of ultrapure water permeated, it was converted into a value of (m1/G.Hr-mmHg), which was used as an index of filtration ability. Each sample was conducted with n=10 for one condition. These measured values are also shown in Table 1.

According to the results in Table 1, modules created with a dispersity of 2.5 or higher have less deformation of the hollow fiber membranes and stable filtration performance evaluated as water permeability.

(Effects of the present invention) As described above, the degree of dispersion of the hollow fiber membrane embedded in the fixing agent can be reduced to 2.
．． The porous regenerated cellulose hollow fiber membrane module obtained by increasing the porous regenerated cellulose to 5 or more has less shrinkage and blockage of the hollow portion, and therefore provides a hollow fiber separation membrane module that can fully exhibit the filtration properties of regenerated cellulose. You can.

Claims (1)

[Claims] After both ends of a porous regenerated cellulose hollow fiber obtained from a cellulose copper ammonia solution are adhesively fixed to a housing with a polyurethane molding agent, the polyurethane surface is cut and both end surfaces of the hollow fiber are coated with a polyurethane molding agent. A porous regenerated cellulose hollow fiber module characterized by having an open end face and a dispersity expressed by the following formula (1) of 2.5 or more. Dispersity=S/[π(1/2D_0)^ 2×n] (1) In formula (1), S: area occupied by the hollow fiber bundle on the polyurethane end face (
cm^2) (Area of the circle surrounding the hollow fiber bundle) D_0: Outer diameter of the hollow fiber (cm) n: Number of hollow fibers