CH636381A5 - Method for the preparation of fibres with porous structure, porous fibres produced in this way, and their use - Google Patents

Description

The present invention relates to a process for the preparation of porous structure fibers and their use.

These porous structure fibers have a great useful surface development, a good dimensional stability, good mechanical properties, a great ease of conservation and a great versatility of use.

The process for preparing porous structure fibers is characterized in claim 1 above; the use of said fibers is indicated in claim 5 above.

According to the process as defined in claim 1, therefore, a natural or synthetic polymeric material is dissolved in a solvent or melted, depending on the nature of the polymer. To the homogeneous mass is added a non-miscible liquid and a finely divided insoluble solid (dispersed phase). The mixture is homogenized and then spun wet, dry or spun. Thus fibers are obtained which are in the form of textile fibers, but containing a dispersed liquid or solid phase which makes their structure porous. Subsequently the dispersed phase is removed by washing with suitable solvents.

The porous fibers thus prepared have a useful surface development greater than that of the known fibers so far.

They can contain functional groups of any chemical nature, depending on the polymer chosen for their manufacture, the only limitation being the ability of the polymer to give fibers. The functional groups present may be already suitable for the use for which the fibers are intended, or can be transformed, with subsequent chemical reactions, into suitable reactive groups.

The mechanical properties of the fibers prepared with the process defined in claim 1 depend on the selected polymer and the particular spinning conditions. These properties can be varied within wide limits, since the range of polymeric materials that can be usefully used is vast. Furthermore, for a given polymeric material, the conditions for obtaining the porous fibers can also be varied within wide limits. So, in each particular condition, there will correspond a useful surface and particular mechanical properties. They will therefore be chosen according to the specific use for which they are intended.

These fibers can be of considerable use in various application fields, excluding however the textile ones. They are used as a support for chemical reagents.

They can be used as a support for insolubilizing soluble catalysts, especially if enzymes. In this case, insolubilizing catalysts are obtained which have high concentrations of activity with high catalytic yields, even on substrates with high molecular weight.

Example 1

Preparation of porous structure fibers of cellulose triacetate

50 g of cellulose triacetate (a commercial product of the company Montefibre, Pallan-za, Novara) were melted in a 664 g glass flask equipped with a mechanical stirrer in 664 g of methylene chloride. 200 g of glycerin were slowly added to this solution and the whole was stirred at 800 rpm for 15 minutes. The homogenized mixture obtained was cooled to 0oC and poured into a container equipped with a die with 500 holes for 125 micrometers in diameter. It was then spun by applying a nitrogen pressure of 1 atmosphere and collecting the thread on a roller after clotting in a toluene bath at 20 ° C about 80 cm long. The obtained fiber was dried in a stream of dry air at room temperature for two hours and stored in a closed container. It had the following composition by weight:

Cellulose triacetate 18%, glycerin 70% and remaining 12% spinning solvents. The ratio between glycerin and polymer in the fiber was therefore 70/18 = 3.86, while in the spinning mixture it was 4.00. In practice, almost all the glycerin initially present was trapped in the coagulated polymer matrix, making its structure porous.

The fiber can be freed from glycerin by simple washing with water. After having been completely freed from the spinning solvents and from the glycerine, it has an apparent density of 0.253 ± 0.005 g per ml, measured according to the technique described in Example no. 8.

Example 2

Preparation of porous poly-L-f-methylglutamate fibers

290 g of PLG-30 (product Kyowa-Hakko Kogyo Co. Ltd. Tokyo-Japan), 10% solution by weight / volume of poly-LY-methylglutamate, were poured into an 11-necked flask equipped with a mechanical stirrer with molecular weight from 100 000 to 300 000 in symmetric 1,2 dichloroethane. 145 g of symmetrical 1,2-dichloroethane and 58 g of a 50% by weight solution of water and glycerin were added under stirring slowly. Ultimately the mixture contains:

g 23 of poly-L-Y-methylglutamate g 412 of symmetric 1,2-dichloroethane g 28 of water g 23 of glycerin

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This mixture was cooled to 0 ° C and emulsified by applying an 800 rpm stirrer for 30 minutes. It was then poured into a container, cooled to - 6 ° C and equipped with a 48-hole die for 80 micrometers. The mixture was then spun by applying a nitrogen pressure of 0.8 atmospheres and collecting the thread on a roller after clotting in a 40-70 ° C oil ether bath, cooled to - 3 ° C.

The resulting yarn, after drying in a stream of air at room temperature for 1 hour, was kept in a closed container. It had the following composition by weight: poly-L-Y-methylglutamate 25.5%, H2O 26.0%, glycerin 26.0%, spinning solvents 22.5%.

The ratio between the dispersed phase (water and glycerin) and polymer in the fiber was therefore of

26 + 26

= 2.04,

25.5

while in the spinning mixture it was 56/23 = 2.43.

Example 3

Preparation of porous polyvinyl chloride fiber

47.5 g Solvik-523K (Solvik product, Via Filippo Turati 8, Milan), copolymer of vinyl chloride and vinyl acetate containing the 12% by weight of acetate, and 452.5 g of methylene chloride. The mixture was stirred until the copolymer completely dissolved, then 95 g of glycerin was added slowly and under stirring. The mixture was cooled to 10 ° C and emulsified by applying 800 rpm stirring for 15 minutes.

The mass obtained was poured into a thermostat container at 10 ° C and equipped with a chain of 100 holes for 80 micrometers. The spinning was then carried out by applying a pressure of 0.6 atmospheres and collecting the yarn on a roller after clotting in an n-hexane bath at 20aC.

The fiber obtained, after drying in a stream of dry air for two hours, was stored in a closed container. It had the following composition by weight: Solvik-523K copolymer - 29.5%, glycerin = 57.9%, spinning solvents 12.6%.

Also in this case, each g of coagulated polymeric matrix retained 1.96 g of glycerine dispersed in vacuoles which make the structure porous.

Example 4

Use of porous structure fibers of cellulose triacetate as a support for the chemical anchoring of proteins

The following three types of fiber were considered:

A) porous structure fiber, obtained by spinning, with the same technique described in example 1, 50 g of cellulose triacetate in 664 g of methylene chloride and 200 g of glycerine as a dispersed phase, with 500 burrs and a strength of 3.7 denier of the single burr.

B) porous structure fiber, obtained in the same conditions as A, but with 100 g of glycerine as a dispersed phase, with 500 burrs and 3.7 denier strength of the single burr.

C) fiber with a non-porous structure, obtained in the same conditions as A and B but without dispersed phase, with 500 burrs and 3.9 denier strength of the single burr.

(The aforementioned titer is the average value obtained on 10 determinations thus carried out: a 500 burr sample 100 cm long was subjected to 5 consecutive washes with distilled water, using in each wash 50 cc of water and 10 minutes of contact time under stirring at room temperature. The sample washed, dried in an oven at 70 ° C and 0.1 mm of Hg of pressure for 8 hours was then weighed. The titre of the single burr was calculated from the dry weight obtained by applying the dry weight formula. in g X 9000

500

For each type of fiber, a sample was taken such as to contain the same amount of 1.78 g of cellulose triacetate and precisely 9.89 g of fiber A, 5.78 g of fiber B, eg 1.85 of fiber C Each sample was introduced into a 300 cc flask and washed 5 times with 200 cc at a time of distilled water, then treated for 4 hours under gentle stirring at room temperature with 200 cc of aqueous solution of 0.5 M. soda.

This treatment transforms the original polymer into cellulose and is such as to at least partially preserve the pre-existing structure of the fiber, as shown by the following results. After hydrolysis with soda, each sample was then washed with water to neutral PH and treated at room temperature under gentle stirring for 20 hours with 165 cc of aqueous solution of 0.05 M phosphate buffer, pH = 8.0 containing 0.285 g of benzoquinone (this treatment activates the fiber and makes it suitable for chemically binding the protein according to the method described in the Swiss patent No. 676 402 of 5 April 1976 in the name of the same applicant).

After this treatment, each sample was washed alternately with water and with 0.05 M phosphate buffer at pH 8.0 until the washing waters do not contain absorbent substances at 250 manometers and then subjected to the trypsin insolubilization reaction;

each sample was brought into contact with 47 ml of 0.05 M phosphate buffer pH 8.0 cooled to 2 ° C, containing 47 mg of trypsin with a specific activity of 30 BAEE units per mg (one BAEE enzymatic unit is the amount of enzyme which hydrolyzes 1 micromole per minute of N a-Benzoyl - L-Argininmethylester, at pH 8.0 and 25 ° C). The reaction was carried out for 24 hours under gentle stirring at 2 ° C. After the reaction, the three samples were washed alternately with water and with 0.05 M phosphate buffer, pH 8.0 until there was no more detectable enzymatic activity in the washing water.

At the end of the protein insolubilization reaction, the residual enzyme activity in the reaction solution was measured. It was respectively:

Solution in contact with sample A - 7.9 BAEE units / ml Solution in contact with sample B -13.1 BAEE units / ml Solution in contact with sample C - 25.2 BAEE units / ml

While the following data were obtained by measuring the enzymatic activity that remained linked to the fibers:

Fiber A - 650 BAEE units per gram of dry product

Fiber B - 450 BAEE units per gram of dry product

Fiber C - 80 BAEE units per gram of dry product

Example 5

Use of porous cellulose triacetate fibers as a support for the chemical anchoring of proteins

4.94 g of fiber A of the previous example, were washed with water, then hydrolyzed with 100 cc of 0.5 M NaOH,

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then subjected to the activation reaction with benzoquinone with 83 cc of 0.05 M phosphate buffer at pH = 8.0 containing 0.142 g of benzoquinone and then washed.

The modalities of these operations are identical to those used in the previous example. The product obtained was reacted with the penicillin-acylase enzyme under the following conditions: the sample was put in contact and kept under gentle stirring for 24 hours at room temperature with 25 ml of 0.04 M phosphate buffer at pH = 7 , 6 containing 38 units per ml of penicillin-acylase from Escherichia Coli (ATCC-9637) with a specific activity of 5 units per mg of protein. (An enzymatic unit is the amount of enzyme that transforms 1 micromole per minute of penicillin G into 6-amino penicillanic acid and phenylacetic acid under the following conditions: temperature = 37 ° C, pH = 8.0,

phosphate buffer 0.01 M and penicillin G = 2% weight-volume,

total volume 200 ml and from 15 to 30 total enzymatic units present. Under these conditions, the measurement of the initial speed of the enzymatic reaction expressed in micromoles per minute coincides with the enzymatic units themselves).

Finally, the washed sample, in order to remove the unreacted enzyme, in the same way described in the previous example, was subjected to the determination of the enzymatic activity remained bound on the fiber.

It had an activity of 444 micromoles per minute and per g of dry product.

Example 6

Use of porous poly-L-y-methyl glutamate fibers as a support for the chemical anchoring of proteins

3.92 g of poI-Ly-methylglutamate fiber, the preparation of which was described in Example 2, were washed with 50 cc of distilled water 4 times to remove the glycerin, then 5 times with 50 cc at a time of absolute methanol to remove water and finally suspended in 50 cc of absolute methanol containing 2.0 millimoles of hydrazine hydrate. Everything was kept under mild stirring and at room temperature. The reaction was carried out by titrating the disappearance of hydrazine of the reaction solution. After 0.98 millimoles of hydrazine had disappeared from the solution, the reaction was stopped by filtering the methanolic solution and washing the fibrous medium 3 times with 50 cc of methanol. This was then washed with cold water (1 ° C - 2 ° C) and then immersed in 100 cc of 0.5 M aqueous hydrochloric acid cooled in an ice bath. To this mixture, kept under stirring, 1 g of sodium nitrite was added in small portions in about 15 minutes.

After the addition, the whole was left under stirring and cold for 1 hour and then the fibrous support was washed with 0.01 M cold aqueous hydrochloric acid.

Finally, the fiber was immersed in 100 ml of 0.1 M phosphate buffer at 8.5 pyH containing 100 mg of trypsin with a specific activity of 30 BAEE units per mg. The whole was left under stirring for one night at 0 ° C. The fibrous substrate, washed with water until the disappearance of enzymatic activity in the washing waters, subjected to the enzymatic activity test linked, exhibited an enzymatic activity of 350 BAEE units per g of dry product.

Example 7

Use of porous polyvinyl chloride fibers as a support for the chemical anchoring of proteins

3.39 g of fiber, the preparation of which was described in Example 3, were washed 4 times with 50 cc at a time of water and then 15 times with 50 cc at a time of absolute methanol, finally they were immersed in 100 cc of absolute methanol containing 1 cc of concentrated sulfuric acid and boiled under reflux for 6 hours. Then they were filtered and washed twice with 50 cc of methanol and 4 times with 50 cc of toluene. The fiber thus treated was immersed in a solution of 5 g of phosgene in 100 cc of toluene at room temperature and stirred overnight, then freed from the excess of phosgene by washing (5 by 50 cc) with toluene and finally dried at room temperature in a stream of dry nitrogen. The fiber was then immersed in 100 ml of 0.1 M phosphate buffer at pH 7.5, cooled to 0 ° C, and containing 100 mg of trypsin with a specific activity of 30 BAEE units per mg. The whole was kept under cold stirring for 20 hours. Eventually the unreacted enzyme was removed by washing with water until the disappearance of enzymatic activity in the water.

The fibrous material thus obtained exhibited an enzymatic activity of 250 BAEE units per g of dry product.

Example 8

Use of porous structure fibers of cellulose triacetate as a molecular sieve

137 g of cellulose triacetate fiber, the preparation of which was described in Example 1, containing 24.6 g of polymer, were cut into pieces of 0.3-0.6 cm in length and packed in a column of 2.5 cm in diameter up to a height of 34.7 cm so as to occupy a total volume of 170 ml of bed. The fiber thus packed was freed from the air bubbles and washed at the same time eluting it with about 51 of degassed water under vacuum. The column thus obtained has shown to possess molecular sieve properties. In fact subjected to gel-filtration measurement, using as an eluent an aqueous solution of KCl at 13.3 g / 1, it gave for dextran 2000 (produced Pharmacia-Fine Chemicals AB - Upsala - Sweden) with a molecular weight of two million in elution volume of 73 ml. This value was constant in the flow range from 5 ml / hour to 50 ml / hour. While the elution volume of the chromium potassium of molecular weight 294 was variable between 128 ml at 7.5 ml / hour and 118 ml at 45 ml / hour. These data demonstrate the molecular sieve property of the fiber and at the same time provide a method for measuring its apparent density:

170 ml (total bed volume) - 73 ml (empty column volume) = 97 ml. Then 24.6 g of polymer occupied 97 ml of volume, whereby 24.6: 97: 0.253 g / ml was obtained.

All the fiber of the column was then transformed into cellulose, by treatment with 0.5 M aqueous soda at room temperature for eight hours, packed in the same column and returned to the same gel-filtration measures. The results are:

total bed volume = 100 ml Blue-Dextran elution volume 2000 = 38 ml potassium dichromate elution volume = 92 ml

(In this case the elution volume of the potassium dichromate was also constant in the same flow interval).

Finally, the dry weight of the fiber was determined by drying it at 80 ° C under vacuum. It was 14.1 g. Therefore the apparent density of the cellulose fiber thus obtained was found to be:

14.1: (100-38) = 0.227 g / ml.

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Claims (7)

636 381 1. Process for the preparation of fibers with a porous structure comprising the following steps: a) dissolution or melting of a polymer b) homogeneous dispersion in the polymer mass of an immiscible liquid or a finely divided insoluble solid c) spinning of the obtained mixture d) removal of the dispersed phase. 2. Process according to claim 1, characterized in that the polymer referred to in point a) is selected from cellulose, its esters, ethers or nitrates, polyamides, polyesters, polyesteramides, polyimides, polypeptides, polymers and copolymers of acrylonitrile, methacrylonitrile, acrylic and methacrylic esters, vinyl esters and ethers, vinyl chloride polymers, vinylidene chloride, vinyl butyral and styrene. 2 3. Process according to claim 1, characterized in that the spinning referred to in point c) is carried out according to a technique chosen from wet, dry or spun ones. Porous structure fibers obtained by the process according to claim 1. 5. The use of porous-structure fibers, prepared by the process according to claim 1, as a support for chemical reagents. The use according to claim 5, as a support for insolubilized proteins and enzymes. The use according to claim 5, as a support for selective inhibitors of insolubilized enzymes.