JP2000001612A - Nylon composition, nylon porous membrane and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition of nylon and a polyester, having a cocontinuous phase separation structure, and useful for a hydrophilic separation membrane, a filter, a wrapping film, a separator for a battery, or the like. SOLUTION: The objective composition of a nylon and a polyester has a cocontinuous phase separation structure and 0.01-10 μm diameter of polyester phase. The nylon 6 or the like obtained by a ring-opening polymerization of ε-caprolactam is cited as the nylon, and the average molecular weight of the nylon is preferably 10,000-30,000. The polyester obtained by carrying out the ring opening polymerization of a cyclic ester such as propiolactone is cited as the polyester, and the average molecular weight of the polyester is preferably 1,500-20,000. The weight ratio of the nylon to the polyester mixed therewith is preferably (30-70):(70-30). A casting method comprising preparing a mixed solution of the nylon and the polyester, and forming the mixed solution into a film by casting, is cited as the mixing method of the composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a nylon composition,
The present invention relates to a nylon porous membrane and a method for producing the same.

[0002]

2. Description of the Related Art Polyamide (nylon) porous membranes are produced by methods such as a dry method and a drawing method. For example, nylon 6 and nylon 66 have a problem that hollow fibers are difficult to produce. there were. Methods for producing a porous membrane include a phase-inversion method, a stretching method, and a radiation method, and the phase-inversion method is used.
Law is often used. Examples of the phase-inversion method include a dry method, a wet method, a polymerization method, and a temperature change method.

[0003] The dry method is the following method. That is, this is a production method in which a system comprising a polymer, a solvent and a non-solvent (pore forming agent) is cast, and the solvent and the non-solvent are evaporated to form a porous film. Formic acid (77.5% to 100%) or trifluoroethanol is used as the solvent. Although the production method is simple, usable solvents are limited. However, the boiling point of the non-solvent is higher than that of the solvent and usually has a difference of about 30 to 40 ° C. Non-solvents are not required in the above systems for polymers such as nylon, where the polymer-polymer interaction is unusually strong and gelation occurs with the formation of microcrystals that can be considered as practically strong crosslinks. Since this method cannot increase the polymer concentration, this method is disadvantageous for a hollow fiber that requires a certain degree of viscosity in the system. In such a case, it is necessary to increase the molecular weight of the polymer or to add a thickener.

[0004] The wet method is the following method. This method involves casting a system composed of a polymer and a solvent, partially evaporating the solvent, and then immersing the system in a non-solvent gelling bath to make it porous. The immersion in the gelling bath is intended for the exchange of solvent and non-solvent, during which the system changes from a polymer and solvent system to a polymer, solvent and non-solvent.

[0005] The polymerization method is the following method. Casting a system consisting of monomer, solvent and non-solvent, polymerizing the monomer by irradiation of light (ultraviolet light, visible light, etc.) or electron beam to convert the system to polymer, solvent and non-solvent system, then dry or wet method Is used for some membranes.

The temperature change method is the following method. This method uses a substance that can be called a latent solvent that becomes a solvent at a high temperature but becomes a non-solvent at a low temperature, and uses a change in the state of the system due to a change in temperature to make it porous. This is a manufacturing method for polypropylene. Other Phase-inversio
In the n method, the anisotropy of the film increases as the thickness of the film increases, whereas the film obtained by this method has an isotropic microporous structure with respect to a cross section in the thickness direction. .

In the stretching method, a stress concentration portion is intentionally formed in a system, and craze generated from the portion by the stretching is used as a hole. This method applies to the following systems: Oriented crystallization system (polypropylene, high density polyethylene), spherical inorganic filler filled system (polyethylene), polymer blend system with sea-island structure (acid-modified polypropylene / nylon 66)

As a radiation method, a film or a hollow fiber is irradiated, and traces of the flying particles are used as holes by chemical etching. The path of the through-holes formed in this way is straight and significantly different from other membranes with extremely complex paths. Polycarbonate and polyester membranes are produced in this way.

Japanese Patent Application Laid-Open No. Sho 56-8441 discloses a method for producing a wet porous membrane for extracting a halide of an alkaline earth metal diffused in the membrane.

Also, POLYMER vol 36 25
97p (1995) describes a porous nylon 6 film from a polyamide solution in a calcium chloride-methanol mixture.

[0011]

SUMMARY OF THE INVENTION The present invention provides a nylon and polyester composition having a novel phase structure, a nylon porous membrane having through holes of a specific diameter useful as a separation membrane, and a method for producing the same. is there.

[0012]

The present invention has a bicontinuous phase-separated structure of a nylon and a polyester composition, and the diameter of the polyester phase is 0.01 to 10 μm, preferably,
The present invention relates to a nylon and polyester composition having a thickness of 0.05 to 3 μm. The present invention also relates to a nylon porous membrane having a diameter of about 0.01 to 10 μm, preferably 0.05 to 3 μm. Further, the present invention relates to the above-mentioned method for producing a nylon porous membrane, comprising treating a composition comprising nylon and polyester with an organic solvent.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The nylon of the present invention is a polyamide resin having an acid amide bond (-CONH-) in a molecule.

Ε-caprolactam, 6-aminocaproic acid, ω-enantholactam, 7-aminoheptanoic acid, 1
Examples thereof include polymers and copolymers obtained from 1-aminoundecanoic acid, 9-aminononanoic acid, α-pyrrolidone, α-piperidone, and the like.

Nylon 6 by ring-opening polymerization of ε-caprolactam, Nylon 66 by polycondensation of hexanemethylenediamine and sebacic acid, Nylon 610 by polycondensation of hexanemethylenediamine and sebacic acid, ring-opening polymerization of ω-laurolactam or 12-aminododecanoic acid Nylon 12 and copolymerized nylon having two or more of the above components.

Also, meta-xylene diamine (MXDA)
Nylon MXD6, which is a crystalline thermoplastic polymer obtained from and adipic acid. Nylon 46 obtained from 1,4-diaminebutane and adipic acid is exemplified. Another example is a methoxymethylated polyamide in which hydrogen of an amide bond of a nylon resin is substituted with a methoxymethyl group.

[0017] These nylons or polyamides are tougher than other thermoplastics. Also,
Low coefficient of friction. Lighter and stronger than metal. Excellent moldability and high mass productivity. It has a high melting point, has a usable temperature range up to + 100 ° C, and has excellent heat and cold resistance. It has a lower elastic modulus than metal materials, and absorbs shocks and vibrations, thus reducing noise. It is particularly excellent in oil resistance and alkali resistance and has corrosion resistance compared to metal materials.

Although the molecular weight of nylon is not particularly limited,
An average molecular weight of 8,000 to 50,000, especially 10,000
The thing of 00-30,000 is preferable.

Examples of the polyester include ordinary polyesters and polylactones obtained by ring-opening polymerization of lactones. Examples of the polylactone include those obtained by ring-opening polymerization of a cyclic ester such as propiolactone (β-lactone), butyrolactone (γ-lactone), and δ-valerolactone (δ-lactone).

The molecular weight of the polyester is not particularly limited, but preferably has an average molecular weight of 1,000 to 50,000, particularly preferably 1,500 to 20,000.

The mixing ratio of nylon and polyester is not particularly limited, but nylon: polyester = 25-7.
5:75 to 25 (% by weight), especially 30 to 70:70 to 3
0 (% by weight) is preferred.

If the ratio is out of the above range, the dispersion state of the composition comprising nylon and polyester deteriorates, and there is a problem that the pores of the nylon porous membrane produced using this composition are difficult to penetrate.

As a method for mixing the composition of nylon and polyester, an ordinary method such as a wet method such as a casting method can be adopted.

As the casting method, for example, there is a method of preparing a mixed solution of nylon and polyester, casting and forming a film.

As the solvent of the above mixed solution, hexafluoroisopropanol, trifluoroethanol, acetic acid, m-cresol, formic acid, sulfuric acid, chlorophenol,
Trichloroacetic acid, ethylene carbonate, phosphoric acid, hexamethylphosphoric triamide and the like.

The concentration of the casting solution is usually 20 to 50
wt%. The casting temperature is usually room temperature in the case of hexafluoroisopropanol, but may be higher depending on conditions. The composition can be produced by coating thinly on glass or the like, and preferably drying at room temperature. When drying, it may be left upside down.

Also, mixing can be performed by a dry method such as melt kneading using a usual kneader. Examples of the kneading machine include a single-screw extruder, a twin-screw extruder, a mixing roll, and a Banbury mixer. It can be melt-kneaded and obtained as pellets. This pellet is injection molded, blow molded,
It is formed into an arbitrary shape such as a molded product, a film, a pipe, and a tube by extrusion molding or the like.

As long as the properties of the composition of the present invention are not impaired, thermosetting resins such as phenolic resins, melamine resins, silicone resins and epoxy resins, glass fibers, carbon fibers, boron fibers, silicon carbide fibers, asbestos fibers, A reinforcing agent such as a metal fiber, or one or more of an antioxidant, a heat stabilizer, an ultraviolet ray inhibitor, a flame retardant, a pigment, an antistatic agent, a colorant, and the like may be added.

The nylon porous membrane of the present invention preferably comprises
It can be produced by treating a composition comprising nylon and polyester with an organic solvent.

Examples of the organic solvent for treating the composition comprising nylon and polyester include aromatic hydrocarbon solvents such as benzene, toluene and xylene, and aliphatic solvents such as acetone.

As a method of treating with an organic solvent, there is a method of treating a composition comprising nylon and polyester with the above-mentioned heated organic solvent to extract polyester. In addition, a method using a Soxhlet extractor, a method in which a composition comprising nylon and polyester is put into the above organic solvent, and the composition is extracted by applying ultrasonic waves, may be used.

[0032]

EXAMPLES Example 1 Polycaprolactone having a molecular weight of 2,000 (1.2 g) and nylon 6 having a molecular weight of 13,000
(1.8 g) in about 5 m of hexafluoroisopropanol
L was prepared, applied thinly on glass, left standing at room temperature overnight, and cast. Thereafter, vacuum drying was performed at room temperature for 8 hours to obtain a blend film of polycaprolactone and nylon 6. 8 polycaprolactone from this film
After extracting with xylene at 0 ° C. for 90 minutes, washing with acetone,
Observation by SEM of the product dried under vacuum for 8 hours revealed that a porous film having a hole having a diameter of about 0.5 μm was obtained.

(Example 2) Polycaprolactone having a molecular weight of 10,000 (1.2 g) and nylon 6 having a molecular weight of 13,000 (1.8 g) were dissolved in about 5 mL of hexafluoroisopropanol to prepare a thin film, which was thinly coated on glass and overnight. The cast was allowed to stand at room temperature. Thereafter, vacuum drying was performed at room temperature for 8 hours to obtain a blend film of polycaprolactone and nylon 6. Polycaprolactone was extracted from the film with xylene at 80 ° C. for 90 minutes, washed with acetone, and vacuum-dried for 8 hours. Observation by SEM showed that a porous film having a hole having a diameter of about 0.2 μm was obtained. I understood.

Example 3 Polycaprolactone having a molecular weight of 10,000 (4 g) and nylon 6 having a molecular weight of 13,000
(6 g) was made into a hexafluoroisopropanol solution having a concentration of 32.6%, applied thinly on glass, turned upside down and left overnight at room temperature to obtain a blend film of polycaprolactone and nylon 6. Polycaprolactone was extracted from this film with xylene at 80 ° C. for 60 minutes, washed with acetone, and vacuum-dried for 8 hours. Observation by SEM showed that a porous film having a hole having a diameter of about several μm was obtained. understood. When methanol was dripped from the upper surface of the porous membrane, the lower surface was in a state of permeation, indicating that the porous membrane had through holes.

[0035]

Industrial Applicability The nylon porous membrane of the present invention is useful as a hydrophilic separation membrane and the like because nylon has hydrophilicity. Other, for example, filters, packaging sheets,
It can be applied to applications such as battery separators, gas separation membranes, filtration membranes, photographic films, microfilms, artificial leather, and insulating materials.

[Brief description of the drawings]

FIG. 1 is an electron micrograph (× 2,500) showing the surface structure of a nylon porous film of Example 1 of the present invention.

FIG. 2 is an electron micrograph (at a magnification of 5,500) showing a cross-sectional structure of a nylon porous film of Example 1 of the present invention.

FIG. 3 is an electron micrograph (× 400) showing a cross-sectional structure of a nylon porous film of Example 3 of the present invention.

FIG. 4 is an electron micrograph (× 5,000) showing a cross-sectional structure of a nylon porous film of Example 3 of the present invention.

Claims (3)

[Claims] 1. A nylon-polyester composition having a co-continuous phase separation structure, wherein the polyester phase has a diameter of 0.01
Nylon and polyester composition having a size of from 10 to 10 μm. 2. A nylon porous membrane having a through hole having a diameter of about 0.01 to 10 μm. 3. The method for producing a nylon porous membrane according to claim 2, wherein the composition comprising nylon and polyester is treated with an organic solvent.