JPS60170609A - Temperature-sensitive copolymer - Google Patents

Abstract

PURPOSE:The titled copolymer, obtained by copolymerizing two or more unsaturated amide compounds having a specific structure, having a sharp cloud point which is a temperature for insolubilizing the copolymer in water, and capable of controlling the cloud point with high sensitivity, and insolubilizing in water by heating. CONSTITUTION:A copolymer obtained by copolymerizing two or more unsaturated amide compounds of the formula (R1 is H or methyl; R2 is H or ethyl; R3 is ethyl or propyl, provided that R2 is H and R3 is propyl when R1 is methyl), e.g. combination of N,N-diethylacrylamide and N-n-propylarylamide, preferably by the radical polymerization method with a polymerization initiator. USE:Reproducible recording materials, temperature-sensitive switches, temperature sensors, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to temperature-sensitive copolymers. More specifically, the present invention relates to a temperature-sensitive copolymer obtained by copolymerizing specified unsaturated amide compounds.

Conventionally, temperature-sensitive polymers that become insolubilized in water by heating in an aqueous solution, that is, specifically, become cloudy and opaque, include polyethylene oxide or a copolymer of ethylene oxide and propylene oxide, methylcellulose, and polymethyl. Vinyl cellulose and the like are known. However, when producing these polymers, there are problems such as the need for special equipment or technology for handling and polymerization of raw material monomers, and the need for quiet reactions that require reactions under harsh conditions. .

In recent years, it has been reported that certain polymers of acrylamide or methacrylamide derivatives (hereinafter abbreviated as (meth)acrylamide derivatives), such as N-propylacrylamide polymers, become cloudy and insolubilized when heated in an aqueous solution. 0MACROMOL, SCI,
-CHEM, , A vol. 2, pp. 1441-1455 (1
968), and a similar technique has recently been disclosed in J. Polymer Sci, Polym.

Symp, Vol. 66, pp. 209-219 (published in 1979), JP-A-58-174408, JP-A-8-179
No. 256, JP-A-58-206654, and regarding diethyl acrylamide, JP-A-58-2066.
It is disclosed in No. 55.

These (meth)acrylamide derivatives are generally in the form of powder or liquid with a high boiling point, so they are easy to handle and have the advantage of being easily polymerized by methods such as radical polymerization.

However, as shown in the comparative examples described below, 3 (where R is hydrogen or a methyl group, a horse is hydrogen or an ethyl group, and a bird is an ethyl group or a propyl group) is represented by the following general formula of the present invention. When R is hydrogen, either hydrogen is a propyl group, or both R and R are ethyl groups.When k is a methyl group, R is hydrogen and an island is a group. is a propyl group.) The temperature at which a homopolymer of an unsaturated amide compound becomes insolubilized in water by heating (hereinafter abbreviated as the image point) is not necessarily all sensitive, and furthermore, the temperature at which the homopolymer of an unsaturated amide compound becomes insolubilized in water by heating is not necessarily sensitive, and furthermore, the There was no technology to set the points with good sensitivity, so it was not practical.

The term "sensitivity" or "sensitivity" as used herein means that the temperature difference between the cloudiness onset temperature and the cloudiness temperature in the tables of Examples and Comparative Examples described later is relatively small.

In view of the above-mentioned actual situation, the present inventors have made extensive studies and have discovered that by copolymerizing two or more types of unsaturated amide compounds, it is possible to make the image point sharp and set the image point with good sensitivity. We have arrived at the present invention.

That is, the present invention is based on the general formula (R+ is hydrogen or a methyl group, hydrogen is hydrogen, f is an ethyl group, and R3 is an ethyl group or a propyl group. (Hydrogen and R3 is a propyl group, or R2 and the horse are ethyl groups. When the turtle is a methyl group, the horse is hydrogen and the horse is a propyl group.) Two or more unsaturated amide compounds represented by It is a temperature-sensitive copolymer that becomes insoluble in water when heated.

Examples of the unsaturated amide compound represented by the above general formula that can be used in the present invention include N,N-diethylacrylamide, N-n-propylacrylamide, N-isopropylacrylamide, N-n-propylmethacrylamide, and the like. When selecting and copolymerizing two or more monomers from the above unsaturated amide compounds, the combination of monomers is, for example, N,N-diethylacrylamide-N-n-propyl. Acrylamide, N
, N-diethylacrylamide-N-isopropylacrylamide, N,N-diethylacrylamide-N -
n-propylmethacrylamide, N-n-propylacrylamide-N-isopropylacrylamide, N-n
-Propylmethacrylamide-N -n-propylmethacrylamide, N-isopropylacrylamide-N
-n-propyl methacrylamide and the like. Furthermore, it is also possible to copolymerize the above combinations in combination with one or more monomers.

Specific methods for producing a temperature-sensitive polymer by polymerizing the above-mentioned unsaturated amide compound include (1) a method in which a monomer is directly polymerized without diluting with a solvent to produce a polymer block ( 2) In the method of obtaining a polymer by polymerization in a solvent, there are cases in which the solvent is distilled off from the polymer solution or separation of the precipitated polymer to obtain the polymer, and cases in which the polymer solution is used as it is. A method of obtaining a particulate polymer by polymerization, a method of (4) obtaining a polymer latex by emulsion polymerization, etc. can be adopted. At this time, the polymerization mode is normal N
- It can be carried out by radical polymerization and anionic polymerization similarly to substituted (meth)acrylamide.

Among these, radical polymerization is preferable because polymerization methods in various forms can be easily employed.

As a method for initiating polymerization, a method using a polymerization initiator, a method using light or heat, or a method of irradiating high energy rays such as radiation, electron beam, plasma, etc. can be adopted. Among the above methods, the method using a polymerization initiator is particularly preferred because it simplifies the polymerization operation and makes it easier to control the polymerization. The polymerization initiator is not limited as long as it has the ability to initiate radical polymerization, examples include inorganic peroxides, organic peroxides, combinations of these peroxides and reducing agents, and azo compounds. be. Specifically, ammonium persulfate, potassium persulfate, hydrogen fluoride, tert, -butyl peroxide, benzoyl peroxide, cumene hydroxy peroxide, tert.

-butylperoxy-2-ethylhexanoate, butyl perbenzoate, etc. Reducing agents that can be combined with these include sulfites, bisulfites, salts with low ionic valences such as iron, copper, and cobalt, Examples include organic amines such as aniline, and reducing sugars such as aldose and ketose.

Examples of azo compounds include azobisisobutyronitrile, 2
, 21-azobis-2-amidinopropane hydrochloride, 2.
2-Azohis-2,4-dimethyl(leronitrile, 4
, 4-azobis-4-cyanochloric acid, etc. can be used. It is also possible to use two or more of the above polymerization initiators in combination.

In this case, the amount of the polymerization initiator to be added is sufficient to be within a commonly employed quantitative range, for example, from 0.01 to 5 parts by weight, preferably from 0.05 to 2 parts by weight, per monomer.

Among the copolymers obtained in this way, block-shaped ones and copolymers obtained by distilling off the solvent or separating the precipitated copolymers can be crushed into powder, or melted into granules or flakes. The copolymer can be formed into a fiber or film, and the particulate copolymer can be used as it is, and the latex copolymer can be impregnated and coated on fibrous materials such as cloth and paper or made into a film. The temperature-sensitive copolymer can be provided in the form of a liquid product by dissolving the polymer in an aqueous solution.

When the temperature-sensitive copolymer produced as described above is in solid form, it can be dissolved in an aqueous solution, or when it is dissolved in an aqueous solution, it can be used as it is. The temperature-sensitive copolymer of the present invention becomes insolubilized by heating while dissolved in an aqueous solution, and the temperature at which it becomes insolubilized is expressed as a sigh. Whether this is true or not depends on the type of copolymer and cannot be stated uniformly. However, generally, upon heating, the entire solution first becomes white and translucent, and then becomes cloudy. At that time, the temperature range from translucency to cloudiness varies depending on the concentration and type of polymer, but is generally below 2.3°C. This cloudy liquid generally has a similar appearance to an aqueous emulsion solution, being white and opaque, and is accompanied by phase separation when the temperature is maintained above the image point.

It exists stably. However, depending on the concentration and type of the polymer, after the cloudiness, the cloudiness may associate with each other over time, forming spherical or string-shaped precipitates, or even adhesion to the vessel wall, etc., resulting in phase separation. There are cases where Of course,
The higher the concentration, the higher the opacity, and depending on the type of polymer, phase separation becomes easier.

On the other hand, if a solution that has become white and opaque due to heating as described above is cooled, it becomes transparent near the image point.

This process can be repeated any number of times.

Next, the concentration of the polymer in the aqueous solution at which the above phenomenon occurs varies depending on the type of polymer and its molecular weight, and cannot be generalized. The concentration is 000 ppm or more.

As a matter of course, when the concentration of the polymer becomes dilute, the turbidity upon heating decreases, the image becomes translucent and the image point increases.

On the other hand, the upper limit of the polymer concentration is approximately 70%, which may be in a state where fluidity has been lost as long as it is in a water-containing state.

Further, the aqueous solution in which the above polymer is dissolved may be any medium containing water, and water itself is most preferable. Various types of water can be used, such as tap water, industrial water, ion exchange water, and distilled water. The solvent that can be used miscibly with water may be any solvent as long as it is miscible with water, such as delcols such as methanol and ethanol, ketones such as acetone, glycols such as ethylene glycol and fluoropylene glycol, dioxane, These include cyclic ethers such as tetrahytronane, amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide, nitriles such as acetonitrile, glymes such as tetraglyme, dimethyl sulfoxide, and the like.

As a means for observing the above phenomenon of insolubilization due to heating, there are methods of directly detecting the cloudiness caused by insolubilization using a turbidity meter, an ultraviolet or visible absorption photometer, or the like.

On the other hand, indirect methods include methods of measuring the solution viscosity of an aqueous polymer solution by changing the temperature, and methods of detecting changes in other physical properties due to insolubilization, such as measuring the spread of molecules by changing the temperature using a light scattering method. It can also be done by

In the case of the copolymer of the present invention, the temperature of the goldfish in the aqueous polymer solution measured as described above is usually in the range of 10'C to 40'C, and the temperature of the goldfish can be set with good sensitivity. That is, as described above, the temperature range in which the aqueous polymer solution changes from translucent to cloudy by heating is less than 2.3°C, and insolubilization occurs sharply.

Normally, goldfish are in the temperature range of homopolymer goldfish of each copolymer component, but they are not necessarily in the temperature range between the image points of each component in all cases, and may be slightly outside that range. can also occur. In any case, it is preferable to check various combinations.

Next, the specific method of making the above temperature-sensitive copolymer insolubilized in water by heating is basically to dissolve the above copolymer in water, and then apply it to a heating medium having a temperature above the image point. All you have to do is make contact. Due to the contact, the solution becomes cloudy and the polymer becomes insolubilized. More specifically, the polymer aqueous solution may be placed in an ordinary container, sandwiched between plate-like or membrane-like bodies such as plates, sheets, or films, placed in a tube, sandwiched between double tubes, or beaded. Fix the microspheres by a method such as making them into microspheres, and expose them to sunlight, ultraviolet rays, visible light, infrared rays, far infrared rays, laser beams, etc.; Contact them with a heating medium such as hot water or steam; or The polymer can be insolubilized by heating it by blowing it into the solution, and as a result, the aqueous solution becomes cloudy and becomes white and opaque.

Specific application examples of the temperature-sensitive polymer of the present invention include greenhouses,
Light-shielding materials that block light at certain temperatures for greenhouses, residential window glass, solar water heater lids, etc., renewable recording materials, renewable display materials, temperature-sensitive switches, temperature sensors, temperature-sensitive soaps Examples include temperature-sensitive adhesives, dehydration improvers for polymer flocculants, polymer raw materials for tertiary petroleum recovery, adsorption separation resin raw materials, antifogging agents, wall materials, oil separators, and the like.

The temperature-sensitive copolymer of the present invention has the effect that goldfish can be set with good sensitivity in the temperature range of 10 to 40°C.

The present invention will be explained in more detail below with reference to examples.

Example 1 47.5 g of distilled water, 0.63 g of N-n-propylacrylamide, and 1.88 g of N-n-propyl methacrylamide were added to a 100 TLl 4-hole round bottom flask while stirring under nitrogen gas flow. did. Then ammonium persulfate Oj5'9 and sodium bisulfite 0
．． 11 g was added and polymerized at 15-30°C for 4 hours.

The above polymer aqueous solution was placed in a test tube with an inner diameter of 15 mm, a standard temperature tube was inserted into the tube, and the tube was gradually heated while being stirred using a constant temperature underwater thermometer. It started becoming cloudy at 32°C, and became so cloudy that the mercury bulb on the thermometer could no longer be seen at 33°C. Even when this aqueous solution was further heated, it maintained a stable cloudy state. On the other hand, as the aqueous solution was cooled, it became transparent below the cloudy temperature.

Comparative Examples 1 to 2 The monomers listed in Table 1 were used, and the procedure was exactly the same as in Example 1, except that the amount of ammonium persulfate and hydrogen sulfite added was twice that of Example 1. Polymerization was carried out. Using the polymer thus obtained, the cloudiness onset temperature and cloudiness temperature were measured in exactly the same manner as in Example 1, and the results are shown in Table 1. However, the cloudiness starting temperature is the temperature at which the temperature starts to become cloudy due to heating, and the cloudiness temperature is the temperature at which the mercury bulb of the thermometer becomes invisible due to the cloudiness.

In both cases, the cloudy liquid became colorless and transparent upon cooling.

Examples 2 to 10 Polymerization was carried out in exactly the same manner as in Example 1, except that the monomer combinations shown in Table 2 were used. Using the aqueous polymer solution thus obtained, the cloudiness onset temperature and cloudiness temperature were measured in exactly the same manner as in Example 1, and the obtained results are shown in Table 2.

Claims (1)

[Claims] General formula (R,, is hydrogen or a methyl group, R2 is hydrogen or a ethyl group, and R2 is an ethyl group or a propyl group. However, when 几 is hydrogen, is hydrogen and horse is a propyl group, or koshi and toriguchi-ethyl groups.When horse is a methyl group, gourd is hydrogen and bird is a propyl group.) Two types of unsaturated amide compounds shown by A temperature-sensitive copolymer that is made of the above copolymer and becomes insoluble in water by heating.