JPH11279234A - Heat sensitive polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat sensitive polymer comprising a usual hydrophilic monomer capable of freely setting the insolubilizing temperature to water, excellent in economics by using a copolymer of a hydrophilic monomer and a hydrophobic monomer as the essential constituents and constituting it to insolubilize to water by heating. SOLUTION: For this heat sensitive polymer, a copolymer of (A) a hydrophilic monomer (preferably; N-vinyl acetamide) and (B) a hydrophobic monomer (e.g.; styrene) are used as the essential constituents, and the copolymer is insolubilized in water by heating. The preferable solubility of the constituent (A) to water at 20 deg.C is 10 g/100 g or more. The preferable solubility of the constituent (B) to water is 0.1 g/100 g or less. A desirable clouding point of the copolymer is 10 to 60 deg.C. The copolymer is preferably obtained by radical polymerization. The copolymer can be used by dissolving in water when the obtained copolymer is solid state and directly used when the copolymer is dissolved in an aqueous solution. The preferable concentration of this material in aqueous solutions is >=500 ppm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a thermosensitive polymer material. More specifically, the present invention relates to a heat-sensitive polymer material containing a copolymer of a hydrophilic monomer and a hydrophobic monomer.

[0002]

2. Description of the Related Art Conventionally, as a heat-sensitive polymer material which is insoluble in water by heating in an aqueous solution, that is, becomes opaque due to turbidity upon heating, polyethylene oxide or a copolymer of ethylene oxide and propylene oxide, Methyl cellulose, polymethyl vinyl cellulose and the like are known. However, when these heat-sensitive materials are produced, there are various problems such as the need for special equipment or technology for handling and polymerization of the raw material monomers, and the requirement of a reaction under severe conditions.

[0003] Further, it has been reported that a polymer of a certain (meth) acrylamide derivative, for example, a polymer of N-isopropylacrylamide, becomes turbid and insolubilized by heating in an aqueous solution. MACROMOL. SCI. −
CHEM. A2, 1441-1455 (1968)
), And a similar technique is disclosed in J. et al. Poly
mer Sci. , Polym. Symp. 66 volumes, 2
09-219 (1979), JP-A-58-1744.
08, JP-A-58-179256, JP-A-58-2
No. 06654 and diethyl acrylamide are disclosed in JP-A-58-206655.
Further, a hydrophobic monomer, i.e., a monomer whose homopolymer is insoluble in water, is copolymerized with a (meth) acrylamide derivative, which is a polymer monomer having a temperature of about 20 to 40 [deg.] C., which is insoluble in water and becomes cloudy by the above heating. Japanese Patent Application Laid-Open No. 60-168706 discloses that the temperature at which water is insolubilized by heating can be controlled in a relatively wide temperature range. However, at present, polymers that can be used for heat-sensitive polymer materials are limited to special (meth) acrylamide derivatives.

[0004]

According to the present invention, the polymer which can be used for the conventional heat-sensitive polymer material is limited to a special (meth) acrylamide derivative monomer, and furthermore, a hydrophobic polymer which can control the temperature at which it is insolubilized in water can be controlled. As for the copolymerization of the water-soluble monomer, the temperature at which the polymer is insoluble in water and becomes cloudy by the above-mentioned heating is limited to a polymer monomer having a temperature of about 20 to 40 ° C., which is very economical. The temperature at which water is insolubilized can be freely controlled by using a water-soluble monomer,
The objective is to develop a thermosensitive polymer material that is economical and good.

[0005]

Means for Solving the Problems The present inventors have developed a copolymer of a hydrophilic monomer whose homopolymer is water-soluble in water and a hydrophobic monomer, ie, a monomer whose homopolymer is insoluble in water. The present inventors have found that a heat-sensitive polymer material can be suitably obtained by using a copolymer capable of freely controlling the temperature at which it is insolubilized in water, and have reached the present invention.

That is, the present invention relates to the following matters. 1) A heat-sensitive polymer material comprising a copolymer of a hydrophilic monomer and a hydrophobic monomer as an essential component, wherein the material is insoluble in water by heating. 2) The above 1 wherein the cloud point of the copolymer is in the range of 0 ° C to 70 ° C.
The heat-sensitive polymer material described in the above. 3) The thermosensitive polymer material according to 1 or 2 above, wherein the cloud point of the copolymer is in the range of 10 ° C to 60 ° C. 4) at least one hydrophilic monomer selected from N-vinyl compound derivatives, (meth) acrylamide derivatives, (meth) acrylate derivatives, hydrolysates of vinyl carboxylate (vinyl alcohols), ionic monomers and salts thereof 4. The heat-sensitive polymer material according to any one of the above 1 to 3, which is a kind of hydrophilic monomer. 5) A hydrophilic monomer represented by the following general formula (1): CH ₂ ＣＨCH—NR ¹ —COR ² (1) (wherein R ¹ and R ² independently represent a hydrogen atom or a methyl group). 5. The thermosensitive polymer material according to any one of the above items 1 to 4, which is a hydrophilic monomer. 6) The thermosensitive polymer material as described in 5 above, wherein the hydrophilic monomer represented by the general formula (1) is N-vinylacetamide. 7) The hydrophobic monomer is a (meth) acrylate derivative, N
-Alkyl (meth) acrylamide derivatives, styrene,
7. The heat-sensitive polymer material according to any one of the above 1 to 6, which is at least one hydrophobic monomer selected from acrylonitrile, ethylene, propylene, vinyl chloride, vinylidene chloride, butene-1 and 4-methylpentene-1. In the present invention, “(meth) acryl” refers to both “acryl” and “methacryl”.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The hydrophilic monomer in the present invention means that the solubility of the monomer itself in water at 20 ° C. is 1 g.
/ 100 g or more and the homopolymer is water-soluble, that is, the solubility in water at 20 ° C. is 0.5 g / 100 g.
The above-mentioned monomers are referred to. Examples of the hydrophilic monomer used in the present invention include N-vinyl-2-pyrrolidone, N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylformamide, N-methyl-N-vinylformamide and the like. N-vinyl compounds,
(Meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N
-(Meth) acrylamide derivatives such as ethyl acrylamide and diacetone acrylamide, (meth) acrylate derivatives such as hydroxyethyl acrylate, hydroxypropyl acrylate, various methoxypolyethylene glycol methacrylates, (meth) acrylic acid, vinyl sulfonic acid, allyl sulfonic acid , Methallylsulfonic acid, styrenesulfonic acid, 2-acrylamide-2-phenylpropanesulfonic acid, 2-acrylamide-2-
Ionic hydrophilic monomers such as acids such as methylpropanesulfonic acid and salts thereof, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl ( Examples thereof include polymerizable unsaturated group-containing amide compounds such as (meth) acrylamide and salts thereof. In addition, vinyl acetate, glycidyl (meth) acrylate, etc.
Although the homopolymer of the monomer is not water-soluble, the monomers that show water solubility when the polymer is hydrolyzed, various (meth) acrylates, (meth) acrylamides, acrylonitrile, etc. Monomers that exhibit water solubility when imparted are also included in the hydrophilic monomers of the present invention. That is, a copolymer having a structure in which a homopolymer of the hydrophobic monomer of the present invention is partially hydrolyzed, resulting in copolymerization of a hydrophilic monomer and a hydrophobic monomer, is also a copolymer of the present invention. is there.

[0008] Of these hydrophilic monomers, N-vinyl compounds such as N-vinyl-2-pyrrolidone are preferably used, and more preferably N-vinyl compounds represented by the general formula (1). Specific examples include N-vinylformamide, N-vinylacetamide, N-vinylpropionamide, N-vinyl-isobutyric acid amide, N-methyl-N-vinylformamide, N-methyl-N-vinylacetamide and the like. However, among them, N-vinylacetamide is most preferred. The hydrophilic monomer of the present invention has a solubility of 1 g in water at 20 ° C. of the monomer.
/ 100 g or more, but a monomer having a solubility of 5 g / 100 g or more is preferable in consideration of the efficiency in producing the copolymer, the performance as a hydrophilic monomer, and the like. More preferably, the monomer is 10 g / 100 g or more.

The hydrophobic monomer in the present invention means that the solubility of the monomer itself in water at 20 ° C. is 1 g / 100.
Less than 1 g of the monomer and the monomer itself have a solubility of 1 g.
/ 100 g or more, the homopolymer is hydrophobic, that is, the solubility of the homopolymer in water at 20 ° C. is 0.
It refers to a monomer of less than 5 g / 100 g, and examples of the hydrophobic monomer used in the present invention include styrene, acrylonitrile, ethylene, propylene, butene-1, 4-methylpentene-1, 2-hydroxyethyl methacrylate, and chloride. Vinyl, vinylidene chloride, N,
N-diethyl methacrylamide, N, N-di-n-propylacrylamide, Nn-butyl (meth) acrylamide, N-tert-butyl (meth) acrylamide, Nn-hexyl (meth) acrylamide, Nn
N-alkyl (meth) acrylamide derivatives such as -octyl (meth) acrylamide, N-tert-octylacrylamide, Nn-dodecyl (meth) acrylamide, ethyl (meth) acrylate, methyl (meth) acrylate, butyl (meth) Examples thereof include (meth) acrylate derivatives such as acrylate, lauryl (meth) acrylate, 2-ethyl (meth) acrylate, and glycidyl (meth) acrylate. As described above, as the hydrophobic monomer of the present invention, 20 ° C.
Is less than 1 g / 100 g, preferably less than 0.5 g / 100 g, more preferably less than 0.1 g / 100 g.

A specific method for producing the copolymer used for the heat-sensitive polymer material of the present invention by polymerizing the above-mentioned hydrophilic monomer and hydrophobic monomer is, for example, (1) diluting the monomer with a solvent. (2) solution polymerization of monomers in a solvent such as water and use of the polymer solution as it is; (3) solution polymerization of the monomers in a solvent and distilling off the solvent from the polymer solution Alternatively, a generally known method such as a method of obtaining a polymer by filtering a precipitated polymer, a method of obtaining a polymer as a particulate polymer by suspension polymerization, and a method of obtaining a polymer latex by emulsion polymerization is adopted. it can. At that time, it is economically advantageous to carry out the polymerization by radical polymerization in the same manner as a usual (meth) acrylic compound, vinyl compound or N-vinyl compound.

The polymerization initiator used in the production of the above-mentioned copolymer includes conventionally known peroxides, organic and inorganic peracids or salts thereof and azobis compounds, or various polymerization initiators and reducing agents thereof. Redox-based ones and the like in combination with azobisisobutyronitrile and azobis (2-
Azobis-based polymerization initiators such as (amidinopropane) dihydrochloride. The amount of the polymerization initiator to be used is preferably 5 × 10 ^{−4 to} 5 mol% based on the amount of the copolymerization component. The polymerization initiation temperature is usually about −10 to 120 ° C., and the reaction time is usually about 0.5 to 30 hours, but is not particularly limited as long as the desired copolymer can be obtained.

The copolymer thus prepared can be obtained in the form of a block, latex, granule, powder, solution, or the like, depending on the polymerization method and polymerization conditions. These copolymers of various shapes can be converted into a shape that can be easily used by an optional treatment method. That is, block-like, latex-like copolymers are pulverized by pulverization, or are melted into granules, flakes, fibers, films, etc., latex-like copolymers, solution-like copolymers, etc. Can be formed into a shape which can be easily applied to a desired application by impregnating coating or filming a fibrous substance such as cloth or paper. When it is obtained in a solution state and contains water, it can be used as it is as the heat-sensitive polymer material of the present invention. Of course, the obtained copolymer can be directly dissolved in a solvent containing water and used as the thermosensitive polymer material of the present invention.

As described above, the produced copolymer is
When it is solid, it can be dissolved in an aqueous solution, and when it is dissolved in an aqueous solution, it can be used as it is as the heat-sensitive polymer material of the present invention. The heat-sensitive polymer material of the present invention is insolubilized by heating while being dissolved in an aqueous solution, and the insolubilizing temperature is expressed as a cloud point. The specific method of insolubilization by heating differs depending on the type of material and is not uniformly described.Therefore, the copolymer composition and molecular weight of the copolymer are not uniformly described. Depending on the temperature, the whole solution becomes white and translucent first and then becomes cloudy. The temperature range from translucent to cloudy at that time varies depending on the concentration and type of the polymer, but is generally less than 5 ° C. This cloudy liquid generally has the same appearance as the emulsion aqueous solution and is white and opaque. When the temperature is maintained at the cloud point or higher, it is stably present without phase separation or the like. However, after cloudiness depending on the concentration and type of polymer,
Further, as the time elapses, the cloudy substances may associate with each other to form a spherical or string-like precipitate, or may adhere to a vessel wall or the like and cause phase separation. Naturally, the higher the concentration, the higher the opacity and the easier the phase separation depending on the type of the polymer. On the other hand, as described above, when the solution that has become white and opaque by heating is cooled, the solution becomes transparent near the cloud point. This process can be repeated any number of times.

Next, the concentration of the heat-sensitive polymer material of the present invention in an aqueous solution is not generally described depending on the type of polymer and its molecular weight, but is preferably 100 ppm or more, more preferably 500 ppm or more. Is the concentration of As a matter of course, when the concentration of the polymer becomes low, the turbidity when heated becomes small, and the polymer becomes translucent. On the other hand, the upper limit of the polymer concentration may be a state in which fluidity is lost as long as the polymer contains water, and is about 80% by weight. Exceeding this is not preferable because the coloring property is deteriorated.

The heat-sensitive polymer material of the present invention produced by dissolving the above polymer may be any medium containing water, and most preferably uses water itself. As the water, tap water, industrial water, ion-exchanged water, distilled water, and the like can be used. Further, generally used organic solvents can also be used for producing the thermosensitive polymer material of the present invention. Preferably a solvent that is miscible with water, specifically methanol,
Alcohols such as ethanol, ketones such as acetone,
Glycols such as ethylene glycol and propylene glycol, cyclic ethers such as dioxane and tetrahydrofuran, amide solvents such as N, N-dimethylacetamide and N, N-dimethylformamide, nitriles such as acetonitrile, and glimes such as tetraglyme , Dimethyl sulfoxide and the like. In addition, even if it is a lipophilic solvent that does not mix arbitrarily with water, a solvent that mixes with water in the presence of a solvent having affinity for both water and the lipophilic solvent can be used. Specifically, toluene, xylene, hexane, hydrocarbon solvents such as hexane, methylene chloride, halogenated hydrocarbon solvents such as chloroform, ether solvents such as diethyl ether,
Ester solvents such as ethyl acetate and n-butyl acetate are exemplified.

The heat-sensitive polymer material of the present invention has a coloring agent, a heat stabilizer, an ultraviolet absorber, various reinforcing materials, a filler, a thickener, and the like in order to exhibit desired material properties and functions.
Surfactants, antibacterial agents, medicines, animal feeds, various ionic compounds, water-soluble polymer compounds and the like can also be added.

As a means for observing the phenomenon of insolubilization by heating, there is a method of directly detecting turbidity accompanying insolubilization by visual observation, a turbidity meter, an ultraviolet or visible absorption photometer, or the like. On the other hand, indirectly, the method of measuring the solution viscosity of the aqueous polymer solution by changing the temperature, the method of detecting the change of other physical properties accompanying insolubilization by measuring the spread of molecules by changing the temperature by light scattering method, etc. Can also be done.

In the present invention, the cloud point of the copolymer can be controlled between 0 ° C. and 100 ° C. by copolymerizing a hydrophilic monomer and a hydrophobic monomer. The cloud point generally means a temperature at which a transparent aqueous solution starts to become turbid when the temperature of the surfactant aqueous solution is increased (described in the 4th edition of RIKEN, Iwanami Shoten, 1989). The temperature at which the transparent aqueous solution starts to become cloudy when the temperature of the aqueous solution is increased similarly in the aqueous solution of the polymer material instead of the surfactant is called a cloud point. As a specific method of controlling the cloud point,
First, when it is desired to lower the cloud point, copolymerization with a relatively large amount of a hydrophobic monomer may be performed. In that case, the content of the hydrophobic monomer may be adjusted according to the difference in polarity of the hydrophobic monomer. On the other hand, when it is desired to raise the cloud point to a high temperature, copolymerization with a relatively small amount of a hydrophobic monomer may be performed.
In such a case, the content of the hydrophobic monomer may be adjusted according to the difference in polarity of the hydrophobic monomer. In the case of performing accurate control, it is preferable to confirm in various combinations. The copolymerization ratio of the hydrophilic monomer and the hydrophobic monomer is
As described above, it can be arbitrarily set according to various conditions, but is preferably in the range of 90:10 to 10:90 (molar ratio). The preferred cloud point of the copolymer used in the thermosensitive polymer material of the present invention varies depending on the purpose and cannot be unconditionally specified, but is generally selected from the range of 0 to 100 ° C. Preferably it is in the range of 0 to 70 ° C, more preferably 10 to 60 ° C.

Next, as a specific method for insolubilizing the heat-sensitive polymer material in water by heating, basically, the heat-sensitive material is dissolved in water, and then heated to a temperature higher than the cloud point. It can be performed by contacting the medium or irradiating a heat ray. Upon heating, the solution becomes cloudy and the thermosensitive material becomes insoluble. More specifically, the heat-sensitive material is placed in an ordinary container, sandwiched between plate-like or film-like bodies such as plates, sheets, films, and the like, placed in a tube, sandwiched between double tubes, and the like. Fix it by a method, expose it to sunlight, ultraviolet rays, visible light, infrared rays, far infrared rays, laser beams, etc., contact it with a heating medium such as hot water, steam, etc., or blow those media into an aqueous solution. By heating, the heat-sensitive material can be insolubilized, and as a result, the aqueous solution becomes cloudy and becomes opaque.

Specific examples of the application of the heat-sensitive polymer material of the present invention include light-shielding materials that exhibit light-shielding properties at a certain temperature or higher, such as greenhouses, greenhouses, residential window glasses, and solar water heater lids. Recording materials, reproducible display materials, heat-sensitive switches, temperature sensors, heat-sensitive soaps, heat-sensitive adhesives, dehydration improvers for polymer flocculants, polymer materials for tertiary oil recovery, raw materials for adsorption and separation resins, antifoggants , Wall materials, oil separators, and the like.

[0021]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. (Example 1) 4 equipped with a nitrogen introduction pipe, a thermometer and a cooling pipe
175 g of N-vinylacetamide as a hydrophilic monomer, 75 g of methyl methacrylate as a hydrophobic monomer, and 2250 g of ethyl acetate as a solvent were charged into a three-liter separable flask having a neck, and nitrogen was introduced into the system at 200 ml / min. The system was introduced for about 1 hour to replace the inside of the system with nitrogen. Thereafter, 1.25 g of a polymerization initiator azobisisobutyronitrile dissolved in 100 ml of ethyl acetate was added, the temperature in the system was raised to 60 ° C., and the system was stirred at 200 rpm for 30 minutes.
After allowing to cool, the precipitated content was washed with ethyl acetate, filtered, and the solid content was vacuum-dried at 50 ° C. for 6 hours. The obtained dried product was pulverized to obtain a copolymer. The yield was about 20%. The ratio of the units derived from the hydrophilic monomer and the hydrophobic monomer in the copolymer was determined by ¹ H-NMR. Table 1 shows the obtained results. 20 mg of the above copolymer was dissolved in 20 ml of distilled water to obtain an aqueous solution of a thermosensitive polymer material. This was put into a sample bottle having an inner diameter of 20 mm, a standard thermometer was inserted therein, the sample bottle was immersed in a thermostat, and the temperature of the thermostat was gradually heated. At 17.0 ° C., cloudiness started (this temperature is the cloud point), and at 18.5 ° C., the cloud became cloudy so that the mercury bulb of the thermometer disappeared. Even when the aqueous solution was further heated, the aqueous solution maintained a stable cloudy state. On the other hand, as the aqueous solution was cooled, it became transparent below the cloud point temperature.

Examples 2 to 18 Polymerization was carried out in exactly the same manner as in Example 1 except that the combinations of monomers shown in Table 1 were used to obtain copolymers. The yield was about 20 to 40%. The ratio of units derived from a hydrophilic monomer and a hydrophobic monomer in the copolymer was determined by ¹ H-NMR. Table 1 shows the obtained results. An aqueous solution of a heat-sensitive polymer material was prepared in the same manner as in Example 1 using the copolymer thus obtained, and the cloud point was measured. Table 1 shows the obtained results. In each case, the cloudy liquid returned to colorless and transparent when cooled below the cloud point.

[0023]

[Table 1] NVA: N-vinylacetamide AM: acrylamide VP: N-vinyl-2-pyrrolidone AA: acrylic acid MMA: methyl methacrylate AN: acrylonitrile HEMA: 2-hydroxyethyl methacrylate

(Comparative Examples 1 to 4) Polymerization was carried out in exactly the same manner as in Example 1 except that the monomers shown in Table 2 were used and the amount of the monomers was changed to 250 g. An aqueous solution of a thermosensitive polymer material was prepared in exactly the same manner as in Example 1, and the cloud point was measured. Table 2 shows the obtained results.

[0025]

[Table 2]

[0026]

The thermosensitive polymer material of the present invention is a copolymer obtained by copolymerizing a hydrophilic monomer whose homopolymer is water-soluble and a hydrophobic monomer whose homopolymer is insoluble in water. A polymer that is an essential component, can freely control the temperature at which it is insolubilized in water, shows light-shielding properties at a predetermined temperature or higher, and is a light-shielding material such as a greenhouse, a greenhouse, and a window glass for a house. It can be used as a recording material, a reproducible display material, a temperature sensor, a heat-sensitive adhesive, a heat-sensitive polymer coagulant, a heat-sensitive antifogging agent, and the like.

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Claims (7)

[Claims] 1. A heat-sensitive polymer material comprising a copolymer of a hydrophilic monomer and a hydrophobic monomer as an essential component, and insoluble in water by heating. 2. The heat-sensitive polymer material according to claim 1, wherein the cloud point of the copolymer is in the range of 0 ° C. to 70 ° C. 3. The heat-sensitive polymer material according to claim 1, wherein the cloud point of the copolymer is in the range of 10 ° C. to 60 ° C. 4. The hydrophilic monomer is selected from N-vinyl compound derivatives, (meth) acrylamide derivatives, (meth) acrylate derivatives, hydrolysates of vinyl carboxylate (vinyl alcohols), ionic monomers and salts thereof. The heat-sensitive polymer material according to any one of claims 1 to 3, which is at least one hydrophilic monomer. 5. The hydrophilic monomer is represented by the following general formula (1): CH ₂ ＣＨCH—NR ¹ —COR ² (1) (wherein R ¹ and R ² independently represent a hydrogen atom or a methyl group). 5. A hydrophilic monomer to be used.
A heat-sensitive polymer material according to any one of the above. 6. The heat-sensitive polymer material according to claim 5, wherein the hydrophilic monomer represented by the general formula (1) is N-vinylacetamide. 7. The method according to claim 1, wherein the hydrophobic monomer is a (meth) acrylate derivative, an N-alkyl (meth) acrylamide derivative,
Styrene, acrylonitrile, ethylene, propylene,
The heat-sensitive polymer material according to any one of claims 1 to 6, which is at least one kind of hydrophobic monomer selected from vinyl chloride, vinylidene chloride, butene-1 and 4-methylpentene-1.