JP2626697B2 - Preparation of thermosensitive gel - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a thermosensitive gel capable of reversibly changing its shape, hydrophilicity / hydrophobicity, and transparency in response to a temperature change in the presence of water. It relates to the manufacturing method. More specifically, the present invention relates to mechanochemical materials, such as energy conversion, energy storage, actuators, sensors, water absorbing and dewatering materials, water discharge materials, toys, hydrophilic / hydrophobic changing materials, such as separation membranes, adsorbents, transparency changing As a material, it can be used as, for example, a light-shielding material. A temperature response composed of a crosslinked gel of a polymer that can be reversibly repeated swelling, hydrophilicity, transparency, shrinking at high temperature, hydrophobicity, and opacity in the presence of water. The present invention relates to a method for producing a thermosensitive gel having excellent properties.

2. Description of the Related Art Conventionally, a method for producing a temperature-sensitive gel comprising a crosslinked gel includes copolymerization with a crosslinking agent, for example, ammonium persulfate (starting) in an aqueous solution of N-isopropylacrylamide and N, N'methylenebisacrylamide (crosslinking agent). ) And copolymerization in a micropipette or in paraffin oil [Jar of Chemical Physics, Vol. 81, p. 6379 (1984)
Year)] and crosslinking by irradiation, for example, poly (N-
(Isopropylacrylamide) film is immersed in a saline solution adjusted to maintain its form, irradiated with radiation, or an aqueous solution of poly (N-acryloylpiperidine) is fed into water adjusted to maintain its form. There is a method of forming a polymer molded article and irradiating the polymer in that state with radiation to crosslink (Japanese Patent Application No. 59-61927).

Problems to be Solved by the Invention In the presence of water, a thermosensitive gel capable of reversibly changing its form, hydrophilicity / hydrophobicity, and transparency in response to a temperature change is converted into a mechanochemical material, a hydrophilic / hydrophobic material. When used as a property change material or a transparency change material, the temperature response of the thermosensitive gel becomes a problem. When the thermosensitive gel reversibly changes its form, hydrophilicity / hydrophobicity, and transparency in response to temperature change in the presence of water, it is accompanied by absorption and release of the liquid constituting the gel. The diffusion of this liquid in the gel determines the temperature responsiveness of the material,
It is known that the response speed is proportional to the square of the size of the gel [(Physical Review Letters (Phys.
ical Review Letters), Vol. 55, pp. 2455 (1985
Year)〕.

In other words, thermosensitive gel is converted to mechanochemical material, hydrophilic /
When used as a hydrophobicity changing material or a transparency changing material, its form is thin fibrous, thin film,
Alternatively, small beads are preferred from the viewpoint of responsiveness.

However, in the method of producing by copolymerization with a cross-linking agent, first, in the case of copolymerization in a container, since the shape of the container is limited, a thin fiber, a thin film, or a small bead-like gel is used. Is difficult to produce, and when a bead-like gel is produced by copolymerization in paraffin oil, there is a problem in the separation method.

On the other hand, in the method of producing by crosslinking by irradiation with radiation, first, when a film of a thermosensitive polymer is immersed in an aqueous solution adjusted to maintain its form and then irradiated with radiation to be crosslinked, the film is cast by a casting method. A drying step is required to form, which is not preferable in production. In addition, when an aqueous solution of a temperature-sensitive polymer is introduced into water adjusted to maintain its form, a polymer molded body is formed, and the polymer is irradiated with radiation in that state to perform crosslinking, the temperature-sensitive polymer alone is not used. Even if it is insolubilized at a transition temperature or higher, it is tacky and has a problem that it is difficult to produce a gel in the form of a thin fiber, a thin film, or a small bead.

Means for Solving the Problems The present inventors can use a mechanochemical material, a hydrophilicity / hydrophobicity change material, or a transparency change material,
As a result of intensive studies to obtain a thermosensitive gel having a thin fiber shape, a thin film shape, or a small bead shape and excellent in temperature response, as a result, N-substituted acrylamide polymer (hereinafter referred to as “sensitized gel”) was obtained. A gel preparation solution containing a water-soluble salt of a polymer electrolyte) in a coagulation bath comprising an aqueous solution of a water-soluble metal salt capable of forming a water-insoluble salt with the polymer electrolyte. When introduced in the required shape, the water-insoluble salt of the polymer electrolyte covers the surface of the temperature-sensitive polymer, so that a polymer molded body having almost no tackiness is formed,
It has been found that the polymer moldings maintain a desired form even when they come into contact with each other. The inventor has found that the object can be achieved by crosslinking the thermosensitive polymer by irradiating a gamma ray or an electron beam without drying the polymer molded article, thereby completing the present invention.

That is, the present invention provides a gel preparation containing a water-soluble salt of a thermosensitive polymer and a polymer electrolyte, and an aqueous solution containing a water-soluble metal salt capable of forming a water-insoluble salt with the polymer electrolyte. Into a coagulation bath consisting of a desired shape to form a polymer molded body, and then, without drying the polymer molded body, irradiating the polymer with a gamma ray or an electron beam to thereby form the thermosensitive polymer. It can be used as a mechanochemical material, a hydrophilic / hydrophobicity changing material, or a transparency changing material formed by cross-linking. It has a thin fiber shape, thin film shape, or small bead shape. Provide a thermosensitive gel.

 The present invention will be described in detail.

The temperature-sensitive polymer used in the present invention is reversibly dissolved in water or an aqueous solution containing inorganic salts at a low temperature region and water or an aqueous solution containing inorganic salts at a high temperature region with respect to the respective phase transition temperatures. It has the property of being insoluble,
A crosslinking reaction is caused by irradiation with radiation, for example, poly (N-ethylacrylamide), poly (Nn-propylacrylamide), poly (N-isopropylacrylamide), poly (N-cyclopropylacrylamide), poly (N , N-dimethylacrylamide), poly (N-ethyl-N-methylacrylamide), poly (N
-Methyl-NN-propylacrylamide), poly (N-isopropyl-N-methylacrylamide), poly (N, N-diethylacrylamide), poly (N-acryloylpyrrolidine), poly (N-acryloylpiperidine), poly (N-ethoxyethylacrylamide),
Poly (N-ethyl-N-methoxyethylacrylamide), poly (N-methoxypropylacrylamide),
Poly (N-ethoxypropylacrylamide), poly (N-isopropoxypropylacrylamide), poly (N-methoxyethoxypropylacrylamide), poly (N-tetrahydrofurfurylacrylamide), poly (N-1-methyl-2-methoxy) Ethylacrylamide), poly (N-1-methoxymethylpropylacrylamide), poly [N- (2,2-dimethoxyethyl) -N
-Methylacrylamide], poly [N- (1,3-dioxolan-2-yl) -N-methylacrylamide], poly [N-8-acryloyl-1,4-dioxa-8-azaspiro (4,5) decane ], Poly (N, N-dimethoxyethylacrylamide), poly (N-acryloylmorpholine) and the like. There is no particular limitation on the molecular weight of these thermosensitive polymers, but generally, the molecular weight is 5,000 to 50.
The thing of about 000000 is suitable.

On the other hand, as the water-soluble salt of the polymer electrolyte used in the present invention, sodium alginate, sodium polyacrylate, sodium carboxymethyl cellulose,
And sodium salts of polyvinyl methyl ether / maleic acid copolymer. An aqueous solution of a water-soluble salt of these polymer electrolytes is used as a water-soluble salt of a metal such as barium, calcium, copper, or aluminum, for example, barium chloride, calcium chloride, calcium bromide, calcium nitrate, copper chloride, copper sulfate, copper nitrate. , Forms an insoluble salt in water when introduced into an aqueous solution such as aluminum sulfate. These water-insoluble salts of polyelectrolytes have already been widely used as immobilizing agents by embedding methods such as enzymes and microorganisms.

One feature of the thermosensitive gel of the present invention is that a water-insoluble salt of a polymer electrolyte is used as an embedding material, and since the water-insoluble salt of a polymer electrolyte covers the surface of a thermosensitive polymer, Forming a polymer molded body that shows little property,
Therefore, the desired shapes can be maintained even when the polymer molded bodies come into contact with each other.

In the present invention, in order to produce a thin fibrous, or small bead-shaped thermosensitive gel, a mixture of the aqueous solution of the thermosensitive polymer and the aqueous solution of the water-soluble salt of the polymer electrolyte is passed through a nozzle, or An aqueous solution of a water-soluble metal salt which forms a water-insoluble salt with a polymer electrolyte through a double nozzle with an aqueous solution of a water-soluble salt of the polyelectrolyte as a core liquid using the aqueous solution of the thermosensitive polymer as a core liquid. It is introduced into or into the liquid of the coagulation bath to form a fibrous or bead-like polymer molded body. Then, without drying the polymer molded body, the temperature-sensitive polymer is cross-linked by irradiating a gamma ray or an electron beam and then washed with water as needed, or an acid such as hydrochloric acid, sulfuric acid, or The desired thermosensitive gel can be produced by removing the polymer electrolyte by treating with an alkali such as sodium hydroxide or aqueous ammonia. At this time, the washing temperature is 0
~ 100 ° C is preferable, and the concentration of the acid or alkali aqueous solution is preferably
The content is preferably 0.1 to 30% by weight, and the treatment temperature is preferably 0 to 100C.

Further, in the present invention, in order to produce a thin film-shaped thermosensitive gel, a mixture of the aqueous solution of the thermosensitive polymer and the aqueous solution of the water-soluble salt of the polymer electrolyte is coated on a substrate such as glass, metal, or plastic. Coat on film or
Alternatively, a thin film is poured into a desired container, and then immersed in a coagulation solution comprising an aqueous solution of a water-soluble metal salt which forms a water-insoluble salt with the polymer electrolyte to form a polymer molded body. Subsequently, without drying the polymer molded body, the temperature-sensitive polymer is cross-linked by irradiating a gamma ray or an electron beam, and then, if necessary, treated with water, an acid, or an alkali to polymer electrolyte. By removing, a desired thermosensitive gel can be produced.

In the present invention, the temperature-sensitive polymer may be used alone or as a mixture of two or more kinds, or another temperature-sensitive polymer such as polyvinyl methyl ether may be used together. The concentration of the aqueous solution of the thermosensitive polymer is preferably 1 to 50% by weight, and the concentration of the aqueous solution of the water-soluble salt of the polymer electrolyte is preferably 0.1 to 30% by weight, and the concentration of the mixture is preferably 1 to 50% by weight.

Mixing ratio (weight ratio) of thermosensitive polymer and polymer electrolyte
Is preferably from 1: 0.01 to 100.

In the present invention, the temperature of the coagulation bath is desirably a temperature equal to or higher than the phase transition temperature of the thermosensitive polymer represented by the salt concentration of the coagulation bath. It is also possible to adjust the phase transition temperature by adding a salt which does not form a water-insoluble salt with the polymer electrolyte, such as sodium chloride and sodium sulfate, to the coagulation bath.

The salt concentration in the coagulation bath is preferably from 1 to 80% by weight. Further, the irradiation dose of the gamma ray or the electron beam in the present invention is preferably 1 to 100 Mrad. The temperature of the crosslinking reaction is required to maintain the shape of the polymer molded article, and is preferably in the range of 0 to 100 ° C. The reaction atmosphere is not particularly limited, except that the presence of water or moisture is essential. The crosslinking reaction can be performed in any atmosphere such as in air, in an inert gas, or under reduced pressure.

The temperature-sensitive gel produced according to the present invention shows a phase transition in water or an aqueous solution containing inorganic salts, like the original temperature-sensitive polymer, and constitutes the gel at the phase transition temperature as a boundary. With absorption and release of liquid, swelling, hydrophilicity,
In the transparent and high temperature range, shrinkage, hydrophobicity and opacity can be repeated quickly and reversibly.

EXAMPLES Next, the thermosensitive gel of the present invention will be described in more detail by way of examples. The phase transition temperature (cloud point) in the Examples was determined by dissolving a thermosensitive polymer in water or a saturated saline solution at 1 ° C. using a spectrophotometer equipped with an electronic thermocouple type temperature controller.
The change in transmittance at a wavelength of 500 nm was recorded under a speed of / min, and the change was determined from the temperature at which this became 50% of the initial transmittance.

Example 1. A liquid obtained by sufficiently mixing 200 parts of a 20% by weight aqueous solution of poly (N-isopropylacrylamide) having a phase transition temperature (in water) of 31 ° C and 80 parts of a 5% by weight aqueous solution of sodium alginate was mixed at 35 ° C. Was extruded through a 0.5 mm diameter nozzle into a 10% by weight aqueous solution of calcium chloride maintained in the above-mentioned condition to coagulate into a fibrous form. By irradiating this fibrous polymer molded body with 10 megarads of gamma rays at 35 ° C. without drying, poly (N-isopropylacrylamide) is crosslinked and gelled. Next, this fibrous gel is immersed in a 3% (weight ratio) hydrochloric acid aqueous solution to convert calcium alginate to alginic acid, and then immersed in a 1% (weight ratio) aqueous sodium hydroxide solution to obtain sodium alginate. By washing with water and removing sodium alginate, a crosslinked gel of fine fibrous poly (N-isopropylacrylamide) was produced. This gel undergoes a phase transition near 31 ° C, similar to poly (N-isopropylacrylamide), and shows a length change of about 1.5 times at 20 ° C and 35 ° C. Shrunk. The response time was as short as 5 seconds and the temperature sensitivity was good.

Example 2 10 parts of a 30% by weight aqueous solution of poly (Nn-propylacrylamide) having a phase transition temperature (in water) of 21 ° C. and 2 parts of a 10% by weight aqueous solution of sodium carboxymethylcellulose having a degree of etherification of 0.8 were sufficiently added. Was applied on a glass plate with a coater to a thickness of 0.3 mm, and immediately
It was immersed in a 5% by weight aqueous solution of calcium chloride kept at ℃ to coagulate into a film. Next, the film-shaped polymer molded body is irradiated with an electron beam of 15 megarads at 25 ° C. together with the glass plate, whereby poly (Nn-propylacrylamide) is crosslinked and gelled. Next, the glass plate with the gel attached thereto is immersed in a 3% (weight ratio) aqueous hydrochloric acid solution,
After removing calcium, it is washed with pure water.
% (By weight) of sodium hydroxide to convert carboxymethylcellulose into a sodium salt, and then sufficiently washed with water to remove the carboxymethylcellulose from the gel to obtain a thin film-like poly (N-n-
Propylacrylamide) gel was prepared. This film gel is poly (Nn-propylacrylamide)
Similarly, the transition point is around 21 ° C. At 19 ° C and 23 ° C, the transmittance of light at a wavelength of 500 nm changes from 85% to 5%, and it is reversibly transparent at low temperatures and opaque at high temperatures. become. The response time was about 3 seconds, and the temperature sensitivity was good.

Example 3 A liquid obtained by sufficiently mixing 200 parts of a 20% by weight aqueous solution of poly (N-isopropylacrylamide) having a phase transition temperature (in water) of 31 ° C. and 80 parts of a 5% by weight aqueous solution of sodium alginate at 35 ° C. The solution was dropped through a nozzle having a diameter of 1 mm onto the liquid surface of a 25% by weight aqueous solution of aluminum sulfate kept at a constant temperature to coagulate into beads. By irradiating this bead-shaped polymer molded body with 20 megarad gamma rays at 35 ° C. without drying, poly (N-isopropylacrylamide) is cross-linked and gelled. Next, the beaded gel was thoroughly washed with 5% by weight of ammonia water to remove aluminum alginate, and then sufficiently washed with pure water to produce a beaded gel. This beaded gel is poly (N-
(Isopropylacrylamide) has a transition point at 31 ° C, absorbs nonionic surfactants dissolved in water by heating to 35 ° C or higher, and adsorbs by cooling to 20 ° C or lower. It exhibited a good temperature-sensitive adsorption / desorption effect of releasing the active agent.

Example 4. A liquid obtained by thoroughly mixing 200 parts of a 20% by weight aqueous solution of poly (N-ethoxyethylacrylamide) having a phase transition temperature (in water) of 35 ° C and 80 parts of a 2% by weight aqueous solution of sodium alginate was mixed with 40 parts of It was extruded through a nozzle having a diameter of 0.25 mm into a 10% by weight aqueous solution of calcium chloride maintained at a temperature of not less than ° C., and was coagulated into a fiber. By irradiating this fibrous polymer molded body with 10 megarads of gamma rays at 40 ° C. without drying, poly (N-ethoxyethylacrylamide) is crosslinked and gelled. Next, the fibrous gel is washed with warm water at 50 ° C or higher and cold water at 10 ° C or lower alternately and thoroughly to remove calcium alginate by washing thoroughly.
A crosslinked gel of fine fibrous poly (N-ethoxyethylacrylamide) was produced. This gel undergoes a phase transition around 35 ° C, similar to poly (N-ethoxyethylacrylamide), and shows a length change of about 1.6 times at 20 ° C and 40 ° C,
It elongated at low temperatures and contracted at high temperatures depending on the temperature.
The response time was as short as 5 seconds and the temperature sensitivity was good.

Example 5 100 parts of a 15% by weight aqueous solution of poly (N-acryloylpyrrolidine) having a phase transition temperature (in water) of 56 ° C. and 15 parts of a sodium salt of polyvinyl methyl ether / maleic acid copolymer
A solution obtained by sufficiently mixing 100 parts by weight of an aqueous solution of 100% by weight with a 10% by weight aqueous solution of calcium chloride maintained at 50 ° C. is mixed with a solution having a diameter of 0.5 mm.
And extruded through a nozzle to solidify into a fibrous form. By irradiating this fibrous polymer molded body with 30 megarads of gamma rays at 50 ° C. without drying, poly (N-acryloylpyrrolidine) and polyvinyl methyl ether / maleic acid copolymer are crosslinked and gelled. . Next, the fibrous gel is immersed in a 3% (weight ratio) aqueous solution of hydrochloric acid, then immersed in a 1% (weight ratio) aqueous solution of sodium hydroxide, and further sufficiently washed with water to obtain poly (N-
Acryloylpyrrolidine) and a composite fibrous gel of polyvinyl methyl ether / maleic acid copolymer were produced. This gel, like poly (N-acryloylpyrrolidine), undergoes a phase transition around 56 ° C and shows a length change of about 1.5 times at 30 ° C and 60 ° C. did. The response time was as short as 5 seconds and the temperature sensitivity was good.

Example 6 A 30% by weight aqueous solution of poly (N-isopropylacrylamide) having a phase transition temperature (in water) of 31 ° C. was used as a core liquid, and a 5% by weight aqueous solution of sodium alginate was used as a sheath liquid. Example 1 using a double nozzle having a thickness of 0.5 mm
By performing wet spinning using the same coagulation bath as a spinning bath, irradiating gamma rays under the same conditions as in Example 1, and performing the same post-treatment as in Example 1, fine fibrous poly (N
-Isopropylacrylamide). This gel, like poly (N-isopropylacrylamide), undergoes a phase transition near 31 ° C and shows a length change of about 1.5 times at 20 ° C and 35 ° C. did. The response time was as short as 5 seconds and the temperature sensitivity was good.

Examples 7 to 31 In the same manner as in Examples 1 to 6, using the temperature-sensitive polymers shown in Tables, temperature-sensitive gels having the forms shown in Tables were produced. These thermosensitive gels undergo phase transition near the same temperature as the original thermosensitive polymer, and the response speed was high and the thermosensitivity was good.

Example 32 70 parts of a 25% by weight aqueous solution of poly (N-isopropylacrylamide) having a phase transition temperature (in water) of 31 ° C., and 50% by weight of polyvinyl methyl ether having a phase transition temperature (in water) of 38 ° C.
Aqueous solution 35 parts, 5% by weight aqueous solution of sodium alginate 30
The liquid obtained by sufficiently mixing the parts was extruded through a nozzle having a diameter of 0.9 mm into a 10% by weight aqueous solution of calcium chloride maintained at 40 ° C. or higher, and was coagulated into a fiber. A composite crosslinked gel of thin fibrous poly (N-isopropylacrylamide) and polyvinyl methyl ether was manufactured in the same manner as in Example 4. This gel undergoes a phase transition around 31 ° C
At ℃ and 40 ° C, the length changed about 1.5 times, and reversibly increased at low temperature and contracted at high temperature depending on the temperature. The response time was as short as 10 seconds and the temperature sensitivity was good.

EFFECT OF THE INVENTION In the presence of water, in response to a temperature change, reversibly changes in form, changes in hydrophilicity / hydrophobicity, and changes in transparency, resulting in a thin fiber, thin film with excellent responsiveness, or A small bead-like thermosensitive gel was obtained.

 ────────────────────────────────────────────────── ─── Continuation of the front page Examiner Taizo Nakamura (56) References JP-A-1-34435 (JP, A) JP-A-61-55180 (JP, A) JP-A-56-129208 (JP, A) JP-A 64-34435 (JP, A) JP-A 56-131605 (JP, A) JP-A 63-269 (JP, A) JP-A 1-129064 (JP, A) JP-B-57-44688 (JP-A 57-44688) JP, B2)

Claims (2)

(57) [Claims] 1. A gel preparation solution containing an N-substituted acrylamide polymer and a water-soluble salt of a polymer electrolyte, comprising a water-soluble metal salt capable of forming a water-insoluble salt with the polymer electrolyte. In a coagulation bath composed of an aqueous solution, introduced in the required shape,
Forming a polymer molded body, and then, without drying the polymer molded body, irradiating the N-substituted acrylamide polymer with a gamma ray or an electron beam to crosslink the N-substituted acrylamide polymer. Recipe 2. The polymer electrolyte according to claim 1, wherein the polymer electrolyte is alginic acid, polyacrylic acid, carboxymethyl cellulose, polyvinyl methyl ether / maleic acid copolymer.
Production method of thermosensitive gel described in section