JPS6297912A - Porous polypropylene hollow fiber - Google Patents

Abstract

PURPOSE:Porous polypropylene hollow fiber that has pores of average diameter in a prescribed range with a narrow distribution, thus showing high separation efficiency and high flux and reduced hemolysis, because of its reduced activation of blood complement, when it is used as a membrane for treating blood. CONSTITUTION:The objective porous polypropylene hollow fiber has 2,500-15,000Angstrom of the primary average pore diameter of fine through-holes which are innumerably formed on the walls and 1-1.15 of the average ratio of the secondary moment average diameter to the primary moment diameter in the fine pores. The drawing is carried out at 110-145 deg.C and 10%/min drawing speed to give the objective porous polypropylene hollow fiber of narrow pore diameter.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to porous hollow fibers obtained by drawing polypropylene hollow fibers, and more specifically, the present invention relates to porous hollow fibers that are obtained by drawing polypropylene hollow fibers, and more specifically, have excellent separation efficiency and filtration performance, and improve blood complement activity and This invention relates to a porous polypropylene hollow fiber with a narrow pore size distribution of fine pores, which has excellent performance in terms of low hemolysis.

[Conventional technology]

Porous membranes, which have a structure in which many fine pores are formed in the peripheral wall of hollow fibers made of polymeric materials, are used in various fields, such as plasma separation membranes in the medical field, filtration membranes for water purification, and separation membranes. ing.

By the way, the performance of such a separation membrane is the separation efficiency (
(Efficiency for separating substances with a specific pore size or larger depending on the purpose)
It is desirable that the amount of permeation (the amount of a specific substance to be permeated depending on the purpose) is good.

Furthermore, when used as a blood processing membrane in the medical field, it is desirable to have a membrane that has little influence on blood complement activity and has little destruction of red blood cells, ie, less hemolysis.

1. As a manufacturing method for porous hollow fibers, a polymer membrane material is dissolved in a mixed solvent system of a solvent and a swelling agent or a non-solvent to form a homogeneous solution, which is then used as a stock solution, and this stock solution is cast into a film shape. After partially or completely evaporating the volatile solvent,
Phase transformation methods such as immersion in a coagulation bath to extract and remove the solvent to form a porous membrane, or methods such as forming a film by mixing the substance to be eluted with the polymer membrane material and then removing the substance to be eluted from the membrane. There are known methods such as an extraction method in which a porous membrane is obtained by elution, and a method in which unstretched hollow fibers are spun and then stretched under specific conditions and/or in a specific medium to make them porous.

[Problem that the invention seeks to solve]

However, with the phase inversion method and the extraction method, it is extremely difficult to obtain a porous membrane that not only achieves good performance as a separation membrane but also has desirable performance as a blood treatment membrane. However, the manufacturing process itself was complicated.

Furthermore, since these methods use a solvent, there is also the problem that post-treatment of the solvent remaining in the membrane is troublesome.

On the other hand, although the stretching method does not have the problem of residual solvent, it is still extremely difficult to obtain a porous membrane having the desired performance described above.

[Means for solving problems]

As a result of intensive research aimed at improving the conventional porous membranes mentioned above, the present inventors found that a porous polypropylene hollow fiber membrane with a narrow distribution of micropore diameters has improved both separation efficiency and permeation amount. It is an excellent product, and when used as a plasma separation membrane in the medical field, it has excellent separation efficiency and permeation amount, as well as low activation of blood complement and low hemolysis. They discovered this and arrived at the present invention.

That is, according to the present invention, in a porous polypropylene hollow fiber in which a large number of fine pores are formed in the peripheral wall part,
The moment average pore diameter of some of the fine pores is 2.500 to 1.
5,000 people, and the ratio (Rw/πn) of the second moment average radius (Rw) to the partial moment average radius (W n ) of the fine through hole is 1.1.15.
A porous polypropylene hollow fiber is provided within the range of . Mercury intrusion method is a typical method for measuring the pore size distribution of porous membranes. This is the radius (R) of the sample hole diameter.
The pore diameter (R) is measured by using the following relationship R = -2δcosθ/P between , represents the amount of pore size present, and therefore, by changing the pressure (P) and measuring the amount of mercury flowing into the sample, the pore size distribution can be measured. Note that here, θ is the contact angle of mercury, and δ is the surface tension of mercury.

By the way, the average pore diameter (radius) is: Wn = ΣR1Ni / ΣNi Average radius (-moment or length average radius) π- = ΣRi"Ni / ΣR1Ni Average radius (secondary moment or area) length average radius) π2=ΣR4
'Ni /ΣRi''Nj Average radius (third moment or body area average radius) π2=ΣR4'Ni /
The average radius (fourth moment or weighted average radius) is expressed as ΣR4'Ni, and the average radius from various metric distributions.

Here, πn −Ww, π2. πy indicates the average radius from each measurement standard distribution, and Ri and Ni indicate that the number of pore diameters with a radius of Ri in the pore diameter distribution is Ni.

In the mercury intrusion method, Ni is defined as the percentage of the volume of mercury corresponding to the volume of the hole with radius Ri and the total volume of all the holes.

On the other hand, the ratio of the -th moment to the second moment, the ratio of the -th moment to the third moment, and the ratio of the -th moment to the fourth moment each indicate the breadth or narrowness of the distribution. In other words, π-/Un, π2/πn, Wy/πn are 1
The closer the ratio is to the narrower the distribution (the larger the ratio, the wider the distribution).

In the present invention, the ratio (W'w/in) of the average radius of second order moment π- and the average partial moment radius πn is 1 to
1.15, preferably l-containing, in the range of 10,
It is necessary to use a porous membrane with a narrow pore size distribution. When the ratio (Rw/W n ) exceeds 1.15, the separation efficiency decreases;
Not only will the amount of permeation be inferior, but the performance as a blood processing membrane will also be inferior. In the present invention, the average pore size (diameter) of the microscopic pores is preferably 2,500 to 15,000, preferably 3,000 to 3,000.
It also needs to be in the range of 0 to 10,000 people. If the average pore diameter is outside this range, the object of the present invention described above cannot be achieved.

The porous polypropylene hollow fiber of the present invention is produced, for example, as follows.

When drawing a polypropylene hollow fiber to form a large number of fine pores in the hollow fiber peripheral wall, the drawing process is carried out at a temperature range of 110°C to 145°C and at a drawing strain rate of less than 10%/min, thereby improving the pore size distribution. Narrow porosity polypropylene hollow fibers can be obtained.

Further, the porous polypropylene hollow fiber of the present invention can be drawn in a medium selected from the group consisting of nitrogen, oxygen, argon, -carbon oxide, methane, and ethane, and at a drawing temperature of -100°C or lower. By carrying out the drawing process at a temperature that is between the freezing point of the medium and 50°C higher than the boiling point of the medium, and furthermore, after the drawing process, the hollow fibers are drawn at a temperature that is 90 to 5°C lower than the melting temperature of polypropylene. It can be obtained by hot stretching within a temperature range.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples.

[Example 1] Porous polypropylene hollow fibers were prepared by mercury intrusion method (measurement was carried out using PORO3IMETR series manufactured by CARLOERBA (Italy)).
The test was carried out using O3ERIES) 1500. (The same applies hereafter) The partial moment average radius is 5.190 angstroms, and the ratio of 10-/πn is 1.05 (the pore size distribution is shown as curve A in the drawing).Outer diameter is 400 microns, inner diameter is 300 microns. A module with a membrane area of 0.0047 m was fabricated using porous hollow fibers with a porosity of 72%, and a 0.1% aqueous solution of 0.109 micron styrene latex (manufactured by Dow Chemical Company) was fabricated. make use of,
When the separation efficiency at an initial volume of 20 ml was measured at a shear rate of 800C11-,' using a light scattering device (Model 42000 M manufactured by FICA (France)), no leakage of styrene latex was observed. Furthermore, when the separation efficiency was measured using Mycoplasma, which is an indicator bacteria of 0.1 micron, no leakage of bacteria was observed.

Also, the water permeability of this membrane is 471/min・m′・kg/, d
Met.

[Comparative Example 1] A porous polypropylene hollow fiber, the partial moment average radius measured by mercury intrusion method was 3.490 angstroms, and the ratio of W w /πn was 1.22 (the pore size distribution is shown in the drawing). (shown as curve B), a module with a membrane area of 0.0047 m was fabricated using porous hollow fibers with an outer diameter of 520 microns, an inner diameter of 320 microns, and a porosity of 64.2%. Using a 0.1% aqueous solution of styrene latex, the separation efficiency was measured using a light scattering device in the same manner as in Example 1. As a result, 96.4% of styrene latex leaked, and leakage of mycoplasma was observed. Ta. In addition, the water permeability of this membrane is 4
6i/min・M・kg/n (was.

Although Comparative Example 2 has a smaller moment average radius than Example 1, its pore size distribution is wider;
The separation efficiency is poor.

C Example 2] Using the porous polypropylene hollow fiber membrane of Example 1, a plasma separator (module) with a membrane area of 0.4 M (effective length 1
Using a 10-13 kg mongrel adult, the blood was removed from the carotid artery at a rate of 100 m1/min, passed through a test module, separated and regenerated in the atmosphere, and then returned to the carotid vein. .

UFR (ultrafiltration rate) after 3 hours is 6600 mZ
/hr-n (, SC (sieving coefficient) of total protein is 0.9
8. The SC of T-globulin is 0.96, and changes in white blood cells in the blood that indicate complement activity are observed over the test time (3 hours).
There was little moderation. In addition, the amount of hemoglobin in the blood, which is an indicator of hemolysis, was measured at IO! If/d1 or less.

[Comparative Example 2] A plasma separator was manufactured in the same manner as in Example 2 using the porous polypropylene hollow fiber membrane of Comparative Example 1, and a plasma separation test was conducted in the same manner as in Example 2.

UFR after 3 hours is 5800 d/hr-cd
The SC of S total protein is 0.99, and the SC of γ-globulin is 0.99.
C was 0.96, and changes in white blood cells in the blood indicating complement activity showed little change during the test period (3 hours).

However, the amount of hemoglobin in the blood, which is an indicator of hemolysis, was 20 μ/d after 1.3 hours with a test time of 30 minutes.
It became 0■/d1.

〔Effect of the invention〕

As explained above, the porous polypropylene hollow fiber of the present invention has an average pore size within a predetermined range and has a narrow pore size distribution of fine pores, so it not only has excellent separation efficiency and i3 excess, but also has excellent properties for blood treatment. When used as a membrane, it exhibits excellent performance with less activation of blood complement and less hemolysis.

[Brief explanation of drawings]

The drawings are graphs showing the pore size distributions of porous Bolib and Robylene hollow fibers used in Example 1 and Comparative Example 1, respectively.

Claims (3)

[Claims] (1) In a porous polypropylene hollow fiber in which a large number of fine pores are formed in the peripheral wall, the first moment average pore diameter of the fine pores is in the range of 2,500 to 15,000, and the fine pores have a Average radius of first moment of hole (@
Second moment average radius (@R@_n)
w) ratio (@R@_w/@R@_n) is 1 to 1.15
A porous polypropylene hollow fiber characterized by being in the range of. (2) The first moment average pore diameter of microscopic pores is 3,000
12,000 porous polypropylene hollow fibers according to claim 1. (3) Average radius of first moment of fine holes (@R@_n
) The porous polypropylene hollow fiber according to claim 1, wherein the ratio (@R@_w/@R@_n) of the average radius of second moment (@R@_w) to ) is in the range of 1 to 1.10. .