JPS59169508A - Precise filter membrane - Google Patents

Abstract

PURPOSE:A precise filter membrane having excellent characteristics, obtained by forming a membrane from polyester urethane obtained by reacting polyester with an everage M.W. of about 1,000-3,000 and diisocyanate in the presence of a main chain extender. CONSTITUTION:Polyester with an average M.W. of 2,000 such as polyethylene adipate is dried under vacuum in a separable flask. In the next step, hydroquinone diethylol ether being a main chain extender and dehydrated dimethylformamide are added to polyester and the resulting mixture is stirred under cooling. Subsequently, 4,4'-diphenylmethane diisocyanate is added to said flask which is, in turn, heated to 80 deg.C to generate polymerization and reaction to prepare a polyester urethane-containing solution. This solution is cast on a glass plate and allowed to stand in the air to be gelled to prepare a precise filter membrane having about 1X10<8>-5X10<8> per 1cm<2> of pores of which the max. pore size is about 1.0mum.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a precision oral membrane. More specifically, the present invention relates to a precision oral membrane that is significantly improved in various properties.

Currently, commercially available membranes with a maximum pore diameter of approximately 1 μm include celluloses such as nitrocellulose and acetylcellulose, polyolefins, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, and polycarbonate. The number of pores is about 1 x 107 to 5 x 10' per surface area, and the stiffness is about 1.5 to 2.5 z7&rf-at.
Corresponds to m・hr. However, this amount of water permeation is still insufficient for precision membranes for which improvement in processing capacity is currently desired.

These precision membranes, especially precision membranes made of cellulose, are brittle and must be handled with care, and these characteristics impede operability during installation and cleaning. It doesn't look good from the point of view of willpower. Furthermore, these precision oral membranes have poor biocompatibility and are not suitable for use as materials for artificial skin, which is one of the applications of precision oral membranes. Furthermore, precision filtration membranes made of cellulose cannot be used for oil-containing industrial wastewater treatment, which is one of the applications of precision filtration membranes.

As a result of intensive research to solve the drawbacks and problems seen in conventional precision mouth membranes, the present inventor has developed a precision mouth membrane made from a specific polyester urethane. Effectively 11: (I found out that it is possible.

Therefore, the present invention includes 1. This precision [1]
In the presence of the main face lengthening agent, the average molecular weight is about 4i 10
00 to 3000 polyester and di-r-socyanate can be obtained by reaction, and a film can be formed from polyester urethane.

For example, in the operation of separating yeast from an aqueous yeast solution (approximately 3 to 4/'/c while ensuring a fractionation rate of 100%).
Significant improvements in precision filtration processing ability can be seen, with high water permeability rates of trl, atm, and hr.

The polyester urethane forming the precision membrane is obtained by reacting a polyester having an average molecular weight of about 1,000 to 3,000 with a diincyanate in the presence of a main chain extender.

Examples of polyesters used include daryethylene adipate, polyethylene butylene adipate, polyhexylene adipate, and polycaprolactone. These polyesters used as active hydrogen compounds are
It has a hydroxyl group at the end and has an average molecular weight of about 10
00 to 3000 is used. When a polyester with an average molecular weight within this range is used, a precision membrane with a maximum pore diameter of about 1.0 μm, generally about 0.7 to 1.0 μ7 nm, is finally obtained, which is suitable for yeast, etc. It enables complete separation by mouth-passing. On the other hand, polyesters with average molecular weights outside this range? When used, the maximum pore diameter of the obtained oral membrane becomes larger than about 1.0 μm,
For example, if a polyester with an average molecular weight of 500 or 4000 is used, the maximum pore diameter of the membrane will be 1.5 μm or 1.6 μm, respectively, and the membrane will no longer be able to function adequately as a precision membrane.

As the diisocyanate, for example, 4,4'-diphenylmethane diisocyanate, toluylene diisocyanate, toluidine diisocyanate, 1°5-naphthylene diisocyanate, etc. are used. Further, as the main chain extender, for example, hydroquinone diethylol ether, 1,4-butanediol, etc. are used.

The production of ester urethane from each of these reaction raw materials is carried out according to a conventional method. Generally, polyester, which is an active hydrogen compound, and diisocyanate are reacted in equimolar ratios in the presence of a main chain extender, and finally, Heat treatment is performed to complete the reaction.

To form a film from such polyester urethane, dissolve it in an appropriate solvent, cast the prepared dope solution onto a substrate such as a glass plate, and contact it with water after a certain evaporation time to gel it. This is done by The obtained membrane is generally a flat membrane with a thickness of about 0.1 to 1 inch, and its pore size is determined by the concentration of the dope, addition of swelling agent, temperature, air volume during evaporation,
It can be adjusted by the evaporation time, the composition of the gelling bath, etc.

The precision membrane formed from polyester urethane in this way has the following characteristics. (1) When the surface of the precision membrane is observed by electronic classification, the maximum pore diameter is approximately 1. .0 μm pores per surface area of approximately 1 crd
It is recognized that there are ×108 to 5 ×108,
This corresponds to a water permeability of about 3.0 z/am-atm·hr. This amount of water permeation is larger than that of commercially available precision filtration membranes, and greatly contributes to improving the processing capacity of precision filtration.

(2) Since polyurethane is manufactured using polyester as an active hydrogen compound, the precision membrane has oil resistance and biocompatibility. Furthermore, since polyurethane is a viscoelastic material, it has no brittleness and therefore has extremely good operability.

(3) Because it has the above-mentioned favorable properties, it can be used to remove microorganisms (Entamoeba histolytica, chlorella, beer yeast, sake yeast, etc.), toxoplasma, red blood cells, wine, sugar solutions, etc., fine particles from alcohol solutions, Backwash mouth filtration, particle fractionation,
It can be effectively used for filtering oil-containing factory wastewater, removing artificial skin materials, heavy metals such as lead, filtering airborne particles, and removing particulate catalysts in the organic chemical industry.

Next, the present invention will be explained with reference to examples.

Example 10 g (5 mmol) of polyethylene adipate (hydroxyl groups at both ends, average molecular weight f!2000) was charged into a 14,500 ml separable flask equipped with a stirrer and vacuum-dried at 90° C. for 2 hours. Next, 19 ('5 mmol) of hydroquinone diethylol ether and 100 q of dimethylformamide dehydrated with a molecular sheep were added, stirred until uniform, and cooled with water. Then, while stirring, 2.5 g (10 mmol) of 4,4'-diphenylmethane diisocyanate was added. When the heat generated by addition subsides, the temperature is 80°C.
The polymerization reaction was continued at this temperature for an additional 2 hours to obtain a solution containing 13.59% of the desired polyester urethane.

Similarly, polyester urethane was produced using polyethylene adipate having an average molecular weight of 500 or 4000, respectively.

Film formation of polyester urethane A predetermined amount (for example, 21.59 for polyester urethane using polyester having an average molecular weight of 2000) of dimethylformamide was further added to the polyester urethane solution to prepare a 10% solution of polyester urethane. This solution was cast using a glass rod onto a glass plate with spacers 2 mm thick on both sides, left in air at 9°C and 30% relative humidity for 30 seconds, and then immersed in water. gelatinized.

The properties of the surface of the obtained film-like material (observed by electron microscopy) are shown in Table 1 below.

Table 1 Polyester average molecular weight 500 2 (100
4000 Maximum pore diameter (μm>1.5 1.0
1.6 holes (individual holes) 4 cutting 071 cutting 083X1
0' Yeast Mouth Passage Test An aqueous solution of Saccharomyces cerevitense yeast having a concentration of 0.1971 is passed through a membrane attached to an ultra-straight mouth tester under an operating pressure of 3~ to measure the separation rate of yeast. At the same time, water permeability was also measured. The results obtained are shown in Table 2 below.
is shown.

Table 2 Polyester average molecular weight 500 2000
4000 water permeability (z/7-atm-hr) 4.
5 3.0 5.0 Yeast separation rate (%)
0 100 0 Comparison with commercially available membranes The properties and performance of the precision membrane according to the present invention and a commercially available precision membrane are compared as shown in Table 3 below.

Table 3 Item Invention membrane Large pore diameter of commercially available membrane
(μm> 1.0 1.0 hole i (a
/d) lX108~5X1082X10' Mercury permeability (fall ・atm -hr) 3.02.5 Yeast separation rate □□□) 100 100 Attorney Yoshi 1) Toshio

Claims (1)

[Claims] 1. Presence of active extension II, 1, average molecular weight of about 1000
~3 (1) Precision membrane formed from polyester urethane obtained by reacting polyester of OO with diisocyanate. 2.11 Extended iAI; Precision filter membrane according to claim 1, which is formed from a polyester urethane obtained by reacting polyethylene adipate and 4,4'-diphenyl diisocyanate. 3. Pores with a maximum pore diameter of about 1.0 μm. The precision oral membrane according to claim 1 or 2, having about 1 x 108 to 5 x 108 membranes per crd of surface area.