RU2504561C2 - Method of producing porous film material - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method involves preparing a solution of a copolymer of ε-caprolactam and polyhexamethylene adipine amide with ratio of components of 40:60-60:40 wt % or a copolymer of polyhexamethylene adipine amide and polyhexamethylene sebacine amide with ratio of components of 60:40 wt %, concentration of 10-30 wt % at T=50-70°C in an alcohol-water mixture with ethanol content of 45-97 vol. %, filtering the solution, deaeration thereof and feeding through a slit-type die onto a substrate, holding the formed solution on air at T=20-40°C for 30-150 s, depositing in water at T=20°C for 1-5 min and drying the obtained film at T=20-70°C. The film is characterised by a homogeneous porous structure with pore size D=5-10 mcm, has thickness of 100 mcm, breaking strength σ=4.4 MPa, elong ε=52%, water permeability B=233 kg/m² h.

EFFECT: material can be used to filter liquid and gaseous media, a base for wound covers, matrices for adhesion and proliferation of mesenchymal stem cells.

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Description

The invention relates to processes for the production of porous film materials with a pore size of the micrometer range from aliphatic copolyamides.

Porous polymeric film materials are used for cleaning liquid and gaseous media, as a basis for wound dressings, matrices for the proliferation of mesenchymal stem cells. Currently, there are several ways to create a porous structure of polymer films.

A film or plate of polymer material is irradiated with a stream of high-energy ions, exposing it to local effects of ionizing radiation. After exposure, the film is treated with alkali, which causes additional destruction of the polymer in places exposed to particles. Thus, through channels are formed in the direction of the passage of ions. In the literature, such materials are called track membranes or nuclear filters [Flerov G.N., Barashenkov B.C. Physics – Uspekhi, vol. 114, v.2, p. 361, 1974].

Another method of manufacturing porous filters involves local irradiation with streams of high-energy particles of the original film and subsequent treatment with an etchant. The method is characterized in that before irradiation, a layer of elastic resist is applied to the initial film, after the irradiation, a shrink operation is performed. Etching is carried out in two steps, through the holes in the resist, through the etching agent that does not affect the initial film, through holes in the film are etched into the second step using the etching agent that does not affect the layer of elastic resist [RF No. 2094104 , 1997].

Obtaining track membranes based on polyimides that differ in the correct, strictly controlled pore geometry with an average size of 0.2 μm, is described in the patent [RF No. 2036204, 1995].

Obtaining a microporous structure by extrusion of a polyethylene film includes extrusion of a polyethylene melt, curing, heat treatment, longitudinal drawing of the preform, and heat setting of the obtained microporous film. The longitudinal stretching of the preform is carried out in one stage at 100-300% at room temperature at a speed of stretching the preform 450-1000% / min. The films have a thickness of 10-15 microns, characterized by a pore size of 0.01-0.08 microns and a total porosity of 40-60% [RF No. 2140936, 1999].

Microporous polyethylene films can serve as separators for separating the anode and cathode spaces in chemical current sources. In addition, they can be used as diaphragms for electrolytic capacitors, and are the basis of two-layer electrolytic membranes. Such films can be used for microfiltration and separation of liquid media, gases, and also used for the manufacture of waterproof, but breathable medical clothing, plasters and dressings.

Filter film materials for the purification of liquid and gaseous substances, materials for encapsulation of repellents, toxic chemicals, aromatic substances were obtained from a composition containing a polymer suspension and a filler. The essence of the invention lies in the fact that the porous material is formed from a composition containing a 2-3% aqueous suspension of cellulose and a powder of a thermoplastic polymer with a particle size of 0.01-1.0 mm or a mixture of it with 5-40 wt.% Mineral filler with a particle size of 0.04-0.5 mm, selected from the group comprising zeolite, shungite, apatite. Subsequent dewatering of the molded material is carried out by vacuum at a pressure of 0.3-1.0 kgf / cm ² . Drying is carried out at 80-90 ° C for 10-20 minutes. Then the material is heat treated with air or steam at a melt temperature of the thermoplastic polymer for 10-20 minutes. One of the sides of the material before drying can be coated with vinyl chloride latex with vinylidene chloride in an amount of 2.7-3.3 wt.% By weight of the material [RF No. 2086576, 1997].

A characteristic feature of the porous structure of materials that can be used to proliferate stem cells is a decrease in pore diameter in a given direction [US 0246865, 2009].

The porous structure of the material for wound dressings with high moisture permeability is characterized by microchannels that provide transport properties of the films. These materials can be used in pharmacology for the surface treatment of dosage forms [US 0318072, 2010].

To create a porous structure, the coagulation method is used. According to this method, polymers, and polyamides in particular, are dissolved in ionic liquids at T = 90-170 ° C; coagulation is carried out by contact of the polymer solution with a liquid precipitation medium: water, alcohols or a water-alcohol mixture. Before immersion in a precipitation bath, the polyamide solution is treated with water vapor for 1-20 minutes. Freeze drying is used to remove the precipitant. The resulting film material is characterized by a porous structure with a pore diameter of D = 40-400 microns.

In the above method for producing a porous film material, polyamides of various chemical structures are used, in particular ε-caprolactam, polyhexamethylene adipinamide, polyhexamethylene sebacinamide, as well as a copolymer of ε-caprolactam and prolhexamethylene adipinamide. The dissolution of these polymers in ionic liquids requires a high temperature (T = 90-170 ° C); the formation of a porous structure occurs when the polymer solution formed through a slotted die is exposed to water vapor. The resulting film material contains pores with sizes of tens to hundreds of micrometers. The specified method is the closest in essence and the achieved result [US 0310853, 2010].

Of greatest interest for the formation of fibers and films are aliphatic copolyamides (SPA): copolymers of polyhexamethylene adipinamide with polyhexamethylene sebacinamide with a component ratio of 60:40 wt.% And ε-caprolactam with polyhexamethylene adipinamide with a component ratio of 40: 60-60: 40 wt.%, They have the best film and fiber-forming properties.

The solvent for these SPA is an alcohol-water mixture, which makes the molding process environmentally friendly. Materials from this polymer do not contain solvent residues unhealthy; they retain their performance in aqueous media for a long time.

An object of the invention and a positive result is the production of a porous film material with a pore size of 5-10 μm from SPA, lowering the dissolution temperature, the use of an environmentally friendly solvent, which allows the use of porous film material as wound coatings, matrices for the adhesion and proliferation of human stem cells and animals.

This is achieved by obtaining at T = 50-70 ° C a SPA solution with a concentration of 10-30 wt.% In an alcohol-water mixture with an ethanol content of 45-97 vol.%, Filtering the solution, dehydrating it and feeding it through a slotted die onto a substrate, holding for air of the molded solution at T = 20-40 ° C for 30-150 sec, precipitation in water at T = 20 ° C for 1-5 min, drying the resulting film at T = 20-70 ° C.

The optimal concentration of a SPA solution in an alcohol-water solvent with a ratio of ethanol / water = 70/30 vol.%, Providing a film material, is 15-20 wt.% (Table 1). The solution at this temperature is stable, because It is located above the phase decomposition temperature and has the necessary viscosity level.

The optimal ratio of ethanol / water in the solvent is 60 / 40-80 / 20 vol.%; solution molding temperature T = 50-70 ° C (Table 2).

The optimal exposure time in air at T = 20 ° C formed through a slotted die on the substrate of the polymer solution is 2 minutes (Figs. 1, 2, 3, 4). The film obtained from an 18 wt.% SPA solution in ethanol / water = 70/30, with a holding time before precipitation of 2 min, has an average pore diameter of D = 7 ± 2 μm.

The maximum water permeability at an excess pressure of P = 1 atm for SPA films aged in air at T = 20 ° C before deposition for t = 2 min (Table 3).

The film strength σ and the elastic modulus E increase with increasing time t, and the strain ε increases (Table 4).

The method is illustrated in graphic material, where:

figure 1 is a micrograph of a film obtained from an 18 wt.% solution of a copolymer of ε-caprolactam and polyhexamethylene adipinamide in a mixture of ethanol / water = 70/30 with a holding time t = 1 min at T = 20 ° C before precipitation in water;

figure 2 is a micrograph of a film obtained from an 18 wt.% solution of a copolymer of ε-caprolactam and polyhexamethylene adipinamide in a mixture of ethanol / water = 70/30 with a holding time t = 2 min at T = 20 ° C before precipitation in water;

figure 3 is a micrograph of a film obtained from an 18 wt.% solution of a copolymer of ε-caprolactam and polyhexamethylene adipinamide in a mixture of ethanol / water = 70/30 with a holding time of t = 6 min at T = 20 ° C before precipitation in water;

figure 4 is a micrograph of a film obtained from an 18 wt.% solution of a copolymer of ε-caprolactam and polyhexamethylene adipinamide in a mixture of ethanol / water = 70/30 with a holding time t = 20 min at T = 20 ° C before precipitation in water;

table 1 shows the viscosity and phase decomposition temperature of solutions of a copolymer of ε-caprolactam and polyhexamethylene adipinamide with a ratio of 40/60 in a mixture of ethanol: water = 70/30;

table 2 shows the viscosity of a 18 wt.% solution of a copolymer of ε-caprolactam and polyhexamethylene adipinamide with a ratio of 40:60 in an ethanol-water mixture at various temperatures;

table 3 - the permeability of the films of the copolymer of ε-caprolactam and polyhexamethylene adipinamide with a ratio of 40/60 in a mixture of ethanol: water = 70/30;

Table 4 shows the mechanical properties of the films of the copolymer of ε-caprolactam and polyhexamethylene adipinamide with a ratio of 40/60 in a mixture of ethanol: water = 70/30.

The method is more fully disclosed by examples of its implementation.

Example 1. A copolymer of ε-caprolactam and polyhexamethylene adipinamide with a ratio of 40:60 (viscosity of a 10% solution in an alcohol-water mixture 70/30 at T = 20 ° C, η = 0.12 Pa · s) is dissolved in an alcohol-water solvent, containing 70 vol.% ethanol, with constant stirring for 1 hour, T = 70 ° C, the concentration of the solution is 18 wt.%. The solution is filtered through two layers of calico at a pressure of 1 bar, then dehydrated at a pressure of 0.1 bar for 1 hour. The solution is molded onto a glass substrate at T = 60 ° C through a slotted die with a slit height of 0.5 mm; incubated at T = 20 ° C for 120 seconds, then the substrate with the solution is placed in a water-alcohol precipitation bath with a ratio of ethanol: water = 0: 100 vol.%. The deposition time in water is 10 minutes, after which the film is dried at T = 70 ° C. The resulting film is characterized by a uniform porous structure, pore size D = 7.0 ± 2 μm, has a thickness of 100 μm, tensile strength σ = 4.4 MPa, elongation ε = 52%, water permeability B = 233 kg / m ² hour.

Example 2. A copolymer of ε-caprolactam and polyhexamethylene adipinamide with a ratio of 40/60 (viscosity of a 10% solution in an alcohol-water mixture 70/30 at T = 20 ° C, η = 0.12 Pa · s) is dissolved in an alcohol-water solvent, containing 70 vol.% ethanol, with constant stirring for 1 hour, T = 50 ° C, the concentration of the solution is 10 wt.%. The solution is filtered through two layers of calico at a pressure of 1 bar, then dehydrated at a pressure of 0.1 bar for 1 hour. The solution at T = 60 ° C through a slotted die with a slit height of 0.5 mm is formed on a glass substrate; incubated at T = 20 ° C for 150 seconds, then the substrate with the solution is placed in a water-alcohol precipitation bath with a ratio of ethanol: water = 30: 70 vol.%. The deposition time in water is 10 minutes, after which the film is dried at T = 70 ° C. The resulting film is homogeneous, characterized by the absence of pores larger than 0.1 μm, has a thickness of 100 μm, tensile strength σ = 4.8 MPa, elongation ε = 38.2% .; water permeability B = 210 kg / m ² hour.

Example 3. A copolymer of polyhexamethylene adipinamide and polyhexamethylene sebacinamide with a ratio of 60/40 wt.% (Viscosity of a 10% solution in an alcohol-water mixture 70/30 at T = 20 ° C, η = 0.22 Pa · s) is dissolved in an alcohol-water solvent containing 70 vol.% ethanol, with constant stirring for 2 hours, T = 70 ° C, the concentration of the solution is 18 wt.%. The solution is filtered through two layers of calico at a pressure of 1 bar, then dehydrated at a pressure of 0.1 bar for 1 hour. The solution at T = 60 ° C through a slotted die with a slit height of 0.5 mm is formed on a glass substrate; incubated at T = 20 ° C for 150 seconds, then the substrate with the solution was placed in a water-alcohol precipitation bath with a ratio of ethanol: water = 0: 100 vol.%. The deposition time in water is 10 minutes, after which the film is dried at T = 50 ° C. The resulting film is homogeneous, characterized by a porous structure with a pore size of D = 12.0 ± 5 μm, has a thickness of 100 μm, tensile strength σ = 4.8 MPa, elongation ε = 382%; water permeability B = 197 kg / m ² hour.

Example 4. A copolymer of ε-caprolactam and polyhexamethylene adipinamide with a ratio of 40:60 (viscosity of a 10% solution in an alcohol-water mixture 70/30 at T = 20 ° C, η = 0.12 Pa · s) is dissolved in an alcohol-water solvent, containing 70 vol.% ethanol, with constant stirring for 1 hour, T = 70 ° C, the concentration of the solution is 30 wt.%. The solution is filtered through two layers of calico at a pressure of 1 bar, then dehydrated at a pressure of 0.1 bar for 1 hour. The solution is molded onto a glass substrate at T = 60 ° C through a slotted die with a slit height of 0.5 mm; incubated at T = 40 ° C for 30 seconds, then the substrate with the solution is placed in a water-alcohol precipitation bath with a ratio of ethanol: water = 0: 100 vol.%. The deposition time in water is 10 minutes, after which the film is dried at T = 70 ° C. The resulting film is homogeneous, characterized by a porous structure with a pore size D = 15.0 ± 5 μm, has a thickness of 100 μm, tensile strength σ = 4.8 MPa, elongation ε = 352%; water permeability B = 397 kg / m ² hour.

Example 5. The copolymer of ε-caprolactam and polyhexamethylene adipinamide with a ratio of 40:60 (viscosity of a 10% solution in an alcohol-water mixture 70/30 at T = 20 ° C, η = 0.12 Pa · s) is dissolved in an alcohol-water solvent, containing 70 vol.% ethanol, with constant stirring for 1 hour, T = 60 ° C, the concentration of the solution is 30 wt.%. The solution is filtered through two layers of calico at a pressure of 1 bar, then dehydrated at a pressure of 0.1 bar for 1 hour. The solution is molded onto a glass substrate at T = 60 ° C through a slotted die with a slit height of 0.5 mm; maintained at T = 30 ° C for 300 seconds, then the substrate with the solution was placed in a water-alcohol precipitation bath with a ratio of ethanol: water = 30: 70 vol.%. The deposition time in water is 10 minutes, after which the film is dried at T = 70 ° C. The resulting film is characterized by a uniform surface, the absence of micron-sized pores, has a thickness of 100 μm, tensile strength σ = 40.5 MPa, elongation ε = 12%, water permeability B = 2.5 kg / m ² hour.

Example 6. The copolymer of ε-caprolactam and polyhexamethylene adipinamide with a ratio of 40:60 (viscosity of a 10% solution in an alcohol-water mixture 70/30 at T = 20 ° C, η = 0.12 Pa · s) is dissolved in an alcohol-water solvent, containing 70 vol.% ethanol, with constant stirring for 1 hour, T = 60 ° C, the concentration of the solution is 30 wt.%. The solution is filtered through two layers of calico at a pressure of 1 bar, then dehydrated at a pressure of 0.1 bar for 1 hour. The solution is molded onto a glass substrate at T = 60 ° C through a slotted die with a slit height of 0.5 mm; incubated at T = 30 ° C for 10 seconds, then the substrate with the solution is placed in a water-alcohol precipitation bath with a ratio of ethanol: water = 10: 90 vol.%. The deposition time in water is 10 minutes, after which the film is dried at T = 70 ° C. The resulting film is characterized by a non-uniform surface, a large pore size spread of D = 5-50 μm, a thickness of 100 μm, tensile strength σ = 4.2 MPa, elongation ε = 220%, water permeability B = 270 kg / m ² hour.

Example 7. The copolymer of ε-caprolactam and polyhexamethylene adipinamide with a ratio of 40:60 (viscosity of a 10% solution in an alcohol-water mixture 70/30 at T = 20 ° C, η = 0.12 Pa · s) is dissolved in an alcohol-water solvent, containing 70 vol.% ethanol, with constant stirring for 1 hour, T = 60 ° C, the concentration of the solution is 5 wt.%. The solution is filtered through two layers of calico at a pressure of 1 bar, then dehydrated at a pressure of 0.1 bar for 1 hour. The solution is molded onto a glass substrate at T = 60 ° C through a slotted die with a slit height of 0.5 mm; maintained at T = 30 ° C for 150 seconds, then the substrate with the solution was placed in a water-alcohol precipitation bath with a ratio of ethanol: water = 0: 100 vol.%. The deposition time in water is 10 minutes, after which the film is dried at T = 70 ° C. The resulting film is characterized by an inhomogeneous surface, a large scatter in pore sizes D = 15-100 μm, has a thickness of 100 μm, tensile strength σ = 5.2 MPa, elongation ε = 345%, water permeability B = 370 kg / m ² hour.

Thus, the above examples demonstrate a method for producing film materials having a uniform porous structure with an average pore size of D = 7 ± 2 μm. Such film materials can be used in cell transplantology for adhesion and proliferation of stem cells, fibro and osteoblasts, in medicine as wound dressings, and in technology for filtering liquid and gaseous media.

Claims (1)

A method of obtaining a porous film material, comprising molding a polymer solution on a substrate and coagulating it in a liquid precipitant, characterized in that the copolymer of ε-caprolactam and polyhexamethylene adipinamide with a ratio of 40: 60-60: 40 wt.% Or a copolymer of polyhexamethylene adipinamide and polyhexamethylene sebacinamide with a ratio of components 60:40 wt.% Dissolved at T = 50-70 ° C in an alcohol-water mixture with an ethanol content of 45-97 vol.%, A solution with a concentration of 10-30 wt.% Is filtered, dehydrated and fed through a slotted die to the substrate , the molded solution is kept at T = 20-40 ° C for 30-150 s, placed in a water-alcohol precipitation bath with an ethanol: water ratio of 0: 100-30: 70 vol.%, washed and dried at T = 20- 70 ° C; the resulting material has pores of 5-10 microns in size.

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