JP2991241B2 - Method for producing ultrahigh molecular weight thermosensitive polyacrylamide derivative - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a novel ultrahigh molecular weight thermosensitive polyacrylamide derivative. More specifically, the present invention provides a thickener, a light shield, a temperature sensor,
The present invention relates to a method for producing a heat-sensitive polyacrylamide derivative which can be used for an adsorbent, a toy, an interior, an anti-dye paste, a display, a separation membrane, and a mechanochemical material.

2. Description of the Related Art Some water-soluble polymer compounds exhibit a special reversible dissolution behavior in which, in an aqueous solution state, the precipitate becomes cloudy above a certain temperature (transition temperature or cloud point) and dissolves and becomes transparent below that temperature. This is called a heat-sensitive polymer compound or a hydrophilic-hydrophobic thermoreversible polymer compound, and has recently attracted attention as a mechanochemical material, an anti-staining paste, a separation material, and the like.

As such heat-sensitive polymer compounds, saponified polyvinyl acetate, polyvinyl methyl ether, methyl cellulose, polyethylene oxide, polyvinyl methyl oxazolidinone, and polyacrylamide derivatives have been known.

However, the above-mentioned high molecular compounds, including thermosensitive polyacrylamide derivatives, are weak in material strength and exhibit sufficient performance as thickeners and flocculants even when they are used for separation membranes and mechanochemical materials, for example. Sufficient polymer was not obtained, and its application range was limited. In order to improve the strength of a polymer material, it is essential to increase the molecular weight.

Problems to be Solved by the Invention Under these circumstances, the present invention aims to expand the range of use of thermosensitive polyacrylamide-based derivatives. The object of the present invention is to provide a method for producing a thermosensitive polymer having the following.

Means for Solving the Problems The present inventors have conducted intensive studies and as a result, when synthesizing a thermosensitive polymer by polymerizing an acrylamide-based vinyl compound, the homopolymer becomes hydrophilic-hydrophobic thermoreversible. The polymer obtained by radical polymerization of an acrylamide-based vinyl compound exhibiting solubility characteristics in an aqueous solution at a temperature equal to or higher than the cloud point must not be dissolved in cold water or various organic solvents due to a cross-linking structure generated during precipitation polymerization. In addition, it was found that when a cationic surfactant or an anionic surfactant was added to an aqueous solution of a thermosensitive polymer compound, the phase transition phenomenon caused by thermal stimulation became slower as the amount of addition increased. That is, in a system in which a surfactant is added to an aqueous solution of a heat-sensitive polymer compound, the heat-sensitive polymer compound undergoes a phase transition due to an increase in temperature. It is thought that the phase transition phenomenon caused by the apparent rise in temperature appears to be slow because the precipitate is formed. This was applied to the polymerization of thermosensitive polyacrylamide derivatives. A cationic surfactant or an anionic surfactant is added to an aqueous solution or aqueous dispersion containing one or more acrylamide derivatives at a concentration higher than the critical micelle concentration, and radical polymerization is performed at a temperature higher than the cloud point of the polymer. Then, the polymer precipitates and polymerizes in the micelles, and the heat-sensitive polymer precipitates as fine particles in the micelles, thereby producing a polymer emulsion. When this is cooled to a temperature below the cloud point, it undergoes a phase transition and has an intrinsic viscosity of 2.0
It has been found that a polymer having a molecular weight equivalent to 6.0 is produced, and the present invention has been completed.

The acrylamide vinyl compound used in the present invention has a general formula (In the above formula, R ₁ is hydrogen or an alkyl group, and when R ₁ is hydrogen, R ₂ is an alkyl group.)

Examples of the acrylamide-based vinyl compound whose homopolymer exhibits heat sensitivity as an object of the present invention include N-ethylacrylamide, Nn-propylacrylamide, N-isopropylacrylamide, N-cyclopropylacrylamide, and N, N-diethyl. Acrylamide, N-methyl-N-ethylacrylamide, N-methyl-NNn-propylacrylamide, N-methyl-N-isopropylacrylamide, N-acryloylpiperidine, N-acryloylpyrrolidine and the like can be mentioned.

Acrylamide-based vinyl compounds whose homopolymers are water-soluble and do not exhibit heat sensitivity include acrylamide, N-methylacrylamide, N, N
-Dimethylacrylamide, N-methylolacrylamide, N-acryloylmorpholine, N-dimethylaminopropylacrylamide, N-hydroxyethylacrylamide, N-2-methoxyethylethylacrylamide and the like.

Acrylamide-based vinyl compounds whose homopolymers are water-insoluble (lipophilic) which are the object of the present invention include N
-N-butylacrylamide, N-sec-butylacrylamide, N-tert-butylacrylamide, Nn-
Hexylacrylamide, Nn-octylacrylamide, N-tert-octylacrylamide, Nn-butoxypropylacrylamide, N-2-ethylhexyloxypropylacrylamide, N-furfurylacrylamide, N-acryloyl-2,6-dimethyl Morpholine, N-methylthiopropylacrylamide, N-acryloylbenzhydrazide, N-chloropropylacrylamide, N, N-di-n-propylacrylamide,
N, N-di-isopropylacrylamide and the like can be mentioned.

When producing a thermosensitive polymer by a method of polymerization of one or more acrylamide vinyl compounds,
The charge ratio (molar ratio) of the acrylamide-based vinyl compound, in which the aqueous solution of the homopolymer exhibits heat sensitivity, to another vinyl compound,
The ratio is usually from 100: 0 to 10:90, depending on the combination of these vinyl compounds. Preferably it is 100: 0 to 40:60. The charge ratio (molar ratio) of an acrylamide-based vinyl compound whose homopolymer is water-soluble and whose aqueous solution does not exhibit heat sensitivity to another acrylamide-based vinyl compound whose homopolymer exhibits water-insolubility is determined by the ratio of these vinyl compounds. Depending on the combination, but usually from 99: 1 to 40:60, preferably from 80:20 to 50:50
It is.

One or more acrylamide-based vinyl compounds in which the aqueous solution of the homopolymer does not exhibit heat sensitivity and one or more acrylamide-based vinyl compounds in which the homopolymer exhibits water-insolubility
The cloud point of the aqueous thermosensitive polymer solution obtained by the method of polymerization with one or more species can be controlled by the type, combination and composition ratio of the vinyl compound as the structural unit. In that case, in the case of a copolymer in which an aqueous solution of a homopolymer is formed of two or more kinds of acrylamide vinyl compounds exhibiting heat sensitivity, an additive property is established between the cloud point of each homopolymer and its composition. There are many. When the aqueous solution of the homopolymer copolymerizes at least one kind of acrylamide vinyl compound exhibiting heat sensitivity and at least one kind of other copolymerizable vinyl compound, the copolymer is introduced by introducing the vinyl compound. Although the cloud point of an aqueous solution changes, generally, the introduction of a hydrophilic vinyl compound tends to increase the cloud point, while the introduction of a small amount of a lipophilic vinyl compound tends to decrease the cloud point. However, the introduction of a large amount of a lipophilic vinyl compound makes the copolymer water-insoluble, and the introduction of a large amount of a hydrophilic vinyl compound makes the copolymer water-soluble, resulting in a copolymer that does not exhibit both heat sensitivity. . As other vinyl compounds, an acrylamide-based vinyl compound whose homopolymer is water-soluble and does not exhibit heat sensitivity, an acrylamide-based vinyl compound whose homopolymer is water-insoluble, (meth) acrylic acid, methyl ( (Meth) acrylate, ethyl (meth)
Acrylic acid derivatives such as acrylate and butyl (meth) acrylate; acrylonitrile; vinyl acetate; vinyl chloride; styrene;

In the production of a thermoreversible polyacrylamide derivative having an ultrahigh molecular weight, it is necessary to use water as a polymerization reaction medium. Water used in the present invention includes ion-exchanged water, distilled water, and tap water.

As a method of initiating polymerization, irradiation with radiation or an electron beam, heating in the presence of a radical polymerization initiator, or any method known in the art such as light irradiation in the presence of a photosensitizer is used. be able to. As the polymerization initiator used in the present invention, any water-soluble radical initiator can be used. For example, ammonium persulfate,
Redox initiators such as persulfates such as potassium persulfate, hydrogen peroxide and tert-butyl peroxide, sulfites, bisulfites and ceric ammonium nitrate; 2,2'-azobis-2-amidinopropane Hydrochloride, 2,2'-azobis-2,4-dimethylvaleronitrile, 4,4'-azobis-4
Azo compounds such as cyanovaleic acid and salts thereof. In addition, two or more of the above initiators can be used in combination. The amount of the radical polymerization initiator used is usually 0.01 to 10% by weight, preferably 0.05 to 8% by weight, based on the monomer. The polymerization temperature varies depending on the initiator used and the vinyl compound used, but is usually from 0 to 100 ° C. and a temperature higher than the cloud point of the resulting polymer aqueous solution.

As the surfactant used in the present invention, a cationic surfactant and an anionic surfactant are used. Specifically, as the cationic surfactant, trimethylstearyl ammonium chloride [(C ₁₈ H ₃₇ N (CH ₃ ) ₃ ] Cl, trimethylcetyl ammonium chloride [(C ₁₆ H ₃₃ N (CH ₃ ) ₃ ] C
l, trimethylcetyl ammonium bromide [(C ₁₆ H ₃₃ N
(CH ₃ ) ₃ ] Br, trimethyl n-tetradecylammonium chloride [(C ₁₄ H ₂₉ N (CH ₃ ) ₃ ] Cl, etc.) As anionic surfactants, sodium hard dodecylbenzenesulfonate, sodium soft dodecylbenzenesulfonate, sodium 4-n-octylbenzenesulfonate, sodium dioctylsulfosuccinate, sodium dodecyldiphenyletherdisulfonate, dodecyl sulfate It is necessary to use anionic surfactants having a long chain length of C12 or more such as sodium and nonylphenol sulfate sodium salt, etc. One or more of these cationic surfactants, anionic surfactant One or more activators may be used in combination. Among these ionic surfactants, particularly preferred are trimethylstearyl ammonium chloride and sodium dodecylbenzenesulfonate. The compound undergoes a phase transition due to an increase in temperature.At this time, a part of the polymer undergoes a phase transition in the micelle of the surfactant and precipitates as fine particles.
Apparently, it is considered that the phase transition phenomenon caused by the temperature rise becomes slow to the naked eye. Such a phenomenon does not appear in a system in which a short-chain ionic surfactant or a nonionic surfactant is added to an aqueous thermosensitive polymer compound solution. Further, it is not preferable to add a substance capable of significantly changing the cloud point of the heat-sensitive polymer to these surfactants, and a substance which does not significantly change the cloud point may be added.

In a system in which an appropriately selected ionic surfactant is added at a concentration higher than the critical micelle concentration, the water-insoluble vinyl compound and the water-soluble vinyl compound are uniformly solubilized in water. When radical polymerization or radical copolymerization is performed at a temperature equal to or higher than the cloud point, polymerization in micelles occurs, and the heat-sensitive polymer precipitates as fine particles in the micelles. That is, a polymer emulsion or a copolymer emulsion is formed.
Therefore, the viscosity of the polymer emulsion during polymerization is low,
By lowering the temperature to below the cloud point, a phase transition can be performed to provide an aqueous polymer solution or aqueous copolymer solution having an extremely high viscosity, and a heat-sensitive polyacrylamide derivative having a molecular weight equivalent to the intrinsic viscosity of 2.0 to 6.0 can be produced. . However, once the polymer emulsion is cooled below the cloud point, the particulate heat-sensitive polymer undergoes a phase transition to become water-soluble. When this polymer aqueous solution or copolymer aqueous solution is heated to a temperature higher than the cloud point, it undergoes phase transition and thickens and precipitates.

Under the condition that the concentration of the surfactant is equal to or lower than the critical micelle concentration, a sharp phase transition is observed by increasing the temperature of the aqueous solution of the thermosensitive polymer compound. When polymerizing a thermosensitive polyacrylamide-based derivative under such a critical micelle concentration or lower, precipitation polymerization occurs, and the resulting polymer partially has a crosslinked structure. No soluble polymer is obtained.

Effect of the Invention According to the novel method for producing an ultrahigh molecular weight heat-sensitive polyacrylamide-based derivative of the present invention, a heat-sensitive polyacrylamide-based derivative having a molecular weight equivalent to the intrinsic viscosity of 2.0 to 6.0 is produced. In the conventional method, even if it is used for a separation membrane or a mechanochemical material, a polymer having a low strength and a sufficient performance as a thickener / coagulant cannot be obtained. Since the polymer obtained by the method of the present invention has a high molecular weight, the strength of the material is high, and the polymer exhibits sufficient performance as a thickener / coagulant, and is expected to be used in a wide range of applications.

Hereinafter, the present invention will be described with reference examples and examples, but the present invention is not limited thereto.

Reference Example 1 N-isopropylacrylamide 130.08 was placed in a two-branch 21-neck Erlenmeyer flask equipped with a dropping funnel and a capillary stopper.
g and 1000 g of distilled water, and nitrogen gas was passed vigorously for 1 hour.
Then, 30 mg of ammonium persulfate was added, and polymerization was carried out at 60 ° C. for 1 hour while stirring under a nitrogen stream. A white precipitate formed as the polymerization proceeded. This polymer is partially crosslinked and swells in cold water and various organic solvents but is not soluble.

Reference Example 2 N-isopropylacrylamide 1 was placed in a 500 mL Erlenmeyer flask equipped with a dropping funnel and a capillary stopper and having two branches.
0.07 g, distilled water 150 g, trimethyl n-octyl ammonium chloride (the cationic surfactant is represented by the general formula (CH ₃
0.54 g of (CH ₂ ) _n N (CH ₃ ) ₃ ) Cl (n = 7) was added, and nitrogen gas was passed vigorously for 1 hour. Then ammonium persulfate
15.6 mg was added, and polymerization was carried out at 60 ° C. for 1 hour while stirring under a nitrogen stream. As the polymerization proceeded, it solidified like egg white. This polymer is partially crosslinked and swells in cold water and various organic solvents but is not soluble.

Reference Example 3 N-isopropylacrylamide 1 was placed in a 500 ml Erlenmeyer flask equipped with a dropping funnel and a capillary stopper.
0.07 g, distilled water 150 g, trimethyl dodecylammonium chloride (cationic surfactant is represented by the general formula (CH ₃ (C
0.50 g of H ₂ ) _n N (CH ₃ ) ₃ ) Cl (n = 11) was added, and nitrogen gas was passed vigorously for 1 hour. Then 6.0m ammonium persulfate
g is added and polymerization is carried out at 60 ° C. for 2 hours while stirring under a nitrogen stream. It became like a milky colloid with the progress of polymerization. This polymer is partially crosslinked and swells in cold water and various organic solvents but is not soluble.

Example 1 N-isopropylacrylamide 2 was placed in a 500 ml Erlenmeyer flask equipped with a dropping funnel and a capillary stopper.
0.13 g, distilled water 300 g, trimethyl stearyl ammonium chloride (cationic surfactant is represented by the general formula (CH ₃ (C
_{H 2) n N (CH 3} ) 3) Cl (n = 17)) 1 hour with nitrogen gas added 1.02g through vigorously. Then 20mg of ammonium persulfate
And polymerization is carried out at 60 ° C. for 2.5 hours while stirring under a nitrogen stream. As the polymerization proceeded, a pearly polymer emulsion was formed. This polymer emulsion is stable at a temperature higher than the cloud point of poly (N-isopropylacrylamide), but becomes extremely high-viscosity when the temperature is lowered to a temperature lower than the cloud point to make it water-soluble. However, when the high-viscosity liquid is heated to a temperature higher than the cloud point again, poly (N-isopropylacrylamide) precipitates. After the polymerization reaction, 10
After the polymerization reaction was stopped by adding ml of ethanol to the reaction solution, the mixture was washed 5 times with hot water and then freeze-dried.

Yield 18.13 g The viscosity of this polymer was measured at 27 ° C. with a diluent Ubbelohde viscometer using tetrahydrofuran as a solvent.
Intrinsic viscosity = 4.00 This polymer is soluble in cold water and various organic solvents.

Example 2 500 ml with U-tube equipped with dropping funnel and capillary stopper
N-isopropylacrylamide in Erlenmeyer flask
10.28 g, 150.90 g of distilled water and 1.61 g of sulfate salt of sodium salt of a nonylphenol E04 mol adduct (31% aqueous solution) were added, and nitrogen gas was passed vigorously for 30 minutes. Then ammonium persulfate 7.
3 mg was added, and polymerization was carried out at 60 ° C. for 3 hours while stirring under a nitrogen stream. A polymer emulsion having a bluish color was formed as the polymerization proceeded.

Yield = 9.94 g Intrinsic viscosity = 3.32 Example 3 N-n-propylacrylamide 1 in a 500 ml Erlenmeyer flask with a dropping funnel and a two-branch equipped with a capillary stopper
0.12 g, distilled water 150.59 g, trimethyl stearyl ammonium chloride (the cationic surfactant is represented by the general formula (CH ₃
0.50 g of (CH ₂ ) _n N (CH ₃ ) ₃ ) Cl (n = 17) was added, and nitrogen gas was passed vigorously for 1 hour. Then ammonium persulfate
17.7 mg was added, and polymerization was carried out at 60 ° C. for 2 hours while stirring under a nitrogen stream. As the polymerization proceeded, a pearly polymer emulsion was formed. This polymer emulsion is
It is stable at a temperature higher than the cloud point of poly (Nn-propylacrylamide), but becomes extremely viscous when the temperature is lowered to a temperature lower than the cloud point to make it water-soluble. However, when this high viscosity liquid is heated to a temperature higher than the cloud point again, poly (N-
n-propylacrylamide) precipitates. After the polymerization reaction, 10 ml of ethanol was added to the reaction solution to stop the polymerization reaction, followed by washing with hot water five times and freeze-drying.

Yield 9.37 g The viscosity of this polymer was measured at 27 ° C. with a diluent Ubbelohde viscometer using tetrahydrofuran as a solvent.
Intrinsic viscosity = 3.28 This polymer is soluble in cold water and various organic solvents.

Example 4 N-tert-butylacrylamide in a 500 mL Erlenmeyer flask equipped with a dropping funnel and a capillary stopper and having two branches.
00g, N, N-dimethylacrylamide 6.23g, distilled water 15
1.15 g, trimethyl stearyl ammonium chloride (cationic surfactant is represented by the general formula (CH ₃ (CH ₂ ) _n N (C
_{H 3) 3) Cl (n} = 17)) 0.48g was added to After complete dissolution, through vigorously for 1 hour with nitrogen gas. Then, add 20 mg of ammonium persulfate, and stir under nitrogen flow at 60 ° C.
To polymerize for 30 minutes. As the polymerization proceeded, a pearly copolymer emulsion was formed. This copolymer emulsion is stable at a temperature higher than the cloud point of the copolymer, but becomes a highly viscous liquid when the temperature is lowered to a temperature lower than the cloud point to make it water-soluble. However, when the high-viscosity liquid is heated again to a temperature higher than the cloud point, the copolymer precipitates.
After the polymerization reaction, 10 ml of ethanol was added to the reaction solution to stop the polymerization reaction, followed by washing with hot water five times and freeze-drying.

Yield 10.10 g The viscosity of this polymer was measured at 27 ° C. with a diluent Ubbelohde viscometer using tetrahydrofuran as a solvent. Intrinsic viscosity = 4.10 This polymer is soluble in cold water and various organic solvents.

Example 5 N-isopropylacrylamide (50.00) was placed in a two-branch 11-neck Erlenmeyer flask equipped with a dropping funnel and a capillary stopper.
g, stearyl trimethyl ammonium chloride 2.5 g,
450 g of distilled water was added, and nitrogen gas was passed vigorously for 1 hour. Then, 100 mg of ammonium persulfate is added, and polymerization is carried out at 70 ° C. for 5 hours while stirring under a nitrogen stream. As the polymerization proceeded, a pearly polymer emulsion was formed. Table 1 shows the results of measuring the viscosity of this polymer emulsion while gradually lowering the temperature from 60 ° C.

As shown in Table 1, as the temperature of the produced polymer emulsion was lowered, the viscosity rapidly increased from around the transition point, and a high-viscosity aqueous solution was obtained. However, poly (N-isopropylacrylamide) was precipitated even when the temperature of the aqueous solution was raised again to a temperature higher than the transition point.

Example 6 500 ml with a U-tube equipped with a dropping funnel and a capillary stopper
N-isopropylacrylamide in Erlenmeyer flask
13.31 g, 200.08 g of distilled water and 0.70 g of sodium (hard) dodecylbenzenesulfonate were added, and nitrogen gas was passed vigorously for 30 minutes. Then, add 6.6 mg of ammonium persulfate,
The polymerization is carried out at 60 ° C. for 2 hours while stirring under a nitrogen stream. A polymer emulsion having a bluish color was formed as the polymerization proceeded.

Yield = 13.02 g Intrinsic viscosity = 2.62 Example 7 500 ml with U-tube equipped with a dropping funnel and a capillary stopper
N-isopropylacrylamide in Erlenmeyer flask
13.16 g, 200.24 g of distilled water and 1.00 g of sodium di-ethylhexyl sulfosuccinate were added, and nitrogen gas was passed vigorously for 30 minutes. Then, 11.3 mg of ammonium persulfate was added, and polymerization was carried out at 60 ° C. for 3 hours while stirring under a nitrogen stream. As the polymerization proceeded, a bluish-white polymer emulsion was formed.

Yield = 12.73 g Intrinsic viscosity = 2.76 Example 8 500 ml with U-tube equipped with dropping funnel and capillary stopper
N-isopropylacrylamide in Erlenmeyer flask
13.30 g, distilled water 200.23 g, and sodium 4-n-octylbenzenesulfonate 0.74 g were added, and nitrogen gas was passed vigorously for 30 minutes. Then, 21.9 mg of ammonium persulfate was added, and polymerization was carried out at 60 ° C. for 3 hours while stirring under a nitrogen stream.
As the polymerization proceeded, a white polymer emulsion was formed.

Yield = 12.90 g Intrinsic viscosity = 3.34 Example 9 6.0 g of N-isopropylacrylamide, N, N in a 500 ml Erlenmeyer flask equipped with a dropping funnel and a capillary stopper
9.0 g of dimethylacrylamide, 135.0 g of distilled water and 0.75 g of sodium dodecylbenzenesulfonate were added, and nitrogen gas was passed vigorously for 30 minutes. Then ammonium persulfate 30.0
The mixture is added and the polymerization is carried out at 70 ° C. for 5 hours while stirring under a nitrogen stream.

As the polymerization proceeded, a white polymer emulsion was formed.

Yield = 11.1 g Intrinsic viscosity = 2.27 Example 10 In a 500 ml Erlenmeyer flask equipped with a dropping funnel and a capillary stopper, 5.50 g of Nt-butylacrylamide, N, N-
16.50 g of dimethylacrylamide, 418.00 g of distilled water and 2.20 g of sodium dodecylbenzenesulfonate were added, and nitrogen gas was passed vigorously for 30 minutes. Then ammonium persulfate 8
8.0 mg was added, and polymerization was carried out at 70 ° C. for 5 hours while stirring under a nitrogen stream. As the polymerization proceeded, a white polymer emulsion was formed.

Yield = 14.96 g Intrinsic viscosity = 2.85 Example 11 In a 500 ml Erlenmeyer flask equipped with a dropping funnel and a capillary stopper, 3.30 g of Nt-butylacrylamide, N, N-
18.70 g of dimethylacrylamide, 418.00 g of distilled water, and 2.20 g of sodium salt of a sulfuric acid ester of nonylphenol ethylene oxide 4 mol adduct were added, and nitrogen gas was passed vigorously for 30 minutes. Then, 88.0 mg of ammonium persulfate was added, and polymerization was carried out at 70 ° C. for 5 hours while stirring under a nitrogen stream.

As the polymerization proceeded, a white polymer emulsion was formed.

Yield = 14.24 g Intrinsic viscosity = 2.97 Example 12 4.00 g of Nt-butylacrylamide, N, N- in a 500 ml Erlenmeyer flask equipped with a dropping funnel and a capillary stopper
12.00 g of dimethylacrylamide, 304.00 g of distilled water, and 1.60 g of trimethylstearyl ammonium chloride were added, and nitrogen gas was passed vigorously for 30 minutes. Then, 64.0 mg of ammonium persulfate was added, and polymerization was carried out at 70 ° C. for 5 hours while stirring under a nitrogen stream. As the polymerization proceeded, a white polymer emulsion was formed.

Yield = 10.89 g Intrinsic viscosity = 2.65 Example 13 In a 500 ml Erlenmeyer flask equipped with a dropping funnel and a capillary stopper, 10.80 g of N-isopropylacrylamide, 1.20 g of acrylic acid, 0.67 g of sodium hydroxide, and 228.00 of distilled water
g and 1.20 g of sodium dodecylbenzenesulfonate were added, and nitrogen gas was passed vigorously for 30 minutes. Then, 48.0 mg of ammonium persulfate was added, and the mixture was stirred at 70 ° C. for 5 hours under a nitrogen stream.
As the polymerization proceeded for a period of time, a white polymer emulsion was formed.

Yield = 8.52 g Intrinsic viscosity = 3.18

──────────────────────────────────────────────────続 き Continued on front page Examiner Soichi Yuka (58) Field surveyed (Int.Cl. ⁶ , DB name) C08F 2/00-2/60

Claims (3)

(57) [Claims] 1. A polymer having a hydrophilic-hydrophobic thermoreversible dissolving property by polymerizing one or two or more acrylamide-based vinyl compounds whose homopolymer exhibits hydrophilic-hydrophobic thermoreversible dissolving properties. In preparing a coalesced or copolymerized product, a cationic surfactant or an anionic surfactant is added to the aqueous solution of the acrylamide-based vinyl compound at a concentration higher than the critical micelle concentration, and radical polymerization is performed at a concentration higher than the cloud point. A method for producing a thermosensitive polymer having a molecular weight equivalent to an intrinsic viscosity of 2.0 to 6.0 at a temperature of 27 ° C. in a tetrahydrofuran solution. 2. An acrylamide vinyl compound whose homopolymer exhibits hydrophilic-hydrophobic thermoreversible dissolution characteristics, and one or more other vinyl compounds.
In producing a copolymer exhibiting hydrophilic-hydrophobic thermoreversible dissolution characteristics by polymerizing at least one species, a cationic surfactant or an anionic surfactant is added to an aqueous solution or aqueous dispersion of the vinyl compound with a critical micelle concentration. A method for producing a thermosensitive polymer having a molecular weight corresponding to an intrinsic viscosity of 2.0 to 6.0 at a temperature of 27 ° C. in a tetrahydrofuran solution, wherein the polymer is added at the above concentration and subjected to radical polymerization at a temperature not lower than the cloud point of the polymer. 3. An acrylamide vinyl compound whose homopolymer does not exhibit hydrophilic-hydrophobic thermoreversible dissolution properties.
To produce a copolymer having hydrophilic-hydrophobic thermoreversible dissolving properties by polymerizing one or more species or two or more species and one or more acrylamide-based vinyl compounds whose homopolymer is water-insoluble. Limit, characterized in that a cationic surfactant or an anionic surfactant is added to the aqueous solution or aqueous dispersion of the vinyl compound at a concentration higher than the critical micelle concentration and radical copolymerization is performed at a temperature higher than the cloud point of the copolymer. A method for producing a thermosensitive polymer having a molecular weight corresponding to a viscosity of 2.0 to 6.0.