JPH01284516A - Heat-responsive material - Google Patents

Abstract

PURPOSE:To make it possible to form a heat-responsive material having a water absorptivity which reversibly changes with temperature and being capable of releasing the absorbed water by contraction when heated even in the presence of a large excess of water by copolymerizing a specified vinyl compound with a crosslinking agent and, optionally, other copolymerizable monomers. CONSTITUTION:This heat-responsive material consists of a copolymer of a vinyl compound (A) of formula I (wherein R is hydrogen atom or a methyl group, n is a real number >=2, and m is 0 or a positive real number) with a crosslinking agent (C) and, optionally, other copolymerizable monomers (B). Examples of component B include hydrophilic monomers, ionic monomers, oleophilic monomers and a mixture of at least two of them. Examples of component C which can be used desirably include bis(meth)acrylamide, a di- or poly-ester of a polyol with an unsaturated monocarboxylic acid and allyloxyalkane.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermoresponsive monthly rate. More specifically, it relates to a heat-responsive material that has a water absorption capacity that reversibly changes depending on temperature, and that shrinks and releases absorbed water even in the presence of a large excess of water by heating.

[Prior art] Thermoresponsive hydrogels that reversibly swell and contract with temperature are expected to be applied to temperature sensors, adsorbents, separation materials, toys, etc.; Only a few compounds are known, such as the specified polyN-alkylacrylamide crosslinked product.

[Problems to be solved by the invention] However, conventional compounds have problems such as being difficult to crosslink or being expensive, which inevitably limits the scope of their use. .

[Means for Solving the Problems] In view of the above problems, the present inventors conducted extensive studies to find a new heat-responsive material that is inexpensive and has a simple manufacturing method, and as a result, developed a specific cross-linked polymer. However, it was discovered that the material swells upon absorption of water at low temperatures and shrinks upon release of water at high temperatures, leading to the present invention.

That is, the present invention is based on the general formula (wherein R is hydrogen or a methyl group, n is a real number of 2 or more,
ni is 0 or a positive real number. ), a crosslinking agent (C), and, if necessary, other copolymerizable monomers (B). .

In general formula CI), '11 is preferably a real number from 2 to 10. When n is less than 2, thermal responsiveness may not be exhibited. m is preferably 0-5.

Further, the relationship between n and m is preferably n>m.

Moreover, the order of OC2Ha and 0CaHe does not matter.

The connection format may be random, block, etc., and is not particularly limited.

The vinyl compound (8) represented by the general formula (1) can be obtained by an esterification reaction between an acryloyl group-containing compound and a glycol, or by conventional methods such as hydroxyethyl methacrylate and/or It can be obtained by a method of reacting hydroxyethyl acrylate with ethylene oxide and/or propylene oxide in the presence of a catalyst (acid or alkali catalyst), usually at 50 to 60°C.

In the present invention, examples of the copolymerizable monomer (B) include hydrophilic monomers, ionic monomers, lipophilic monomers, and mixtures of two or more of these monomers.
Examples of hydrophilic monomers include acrylamide, methacrylamide, N-methylacrylamide, hediacetone acrylamide, and N-vinylpyrrolidone. Examples of ionic monomers include acid group-containing monomers such as carboxylic acid group-containing polymerizable monomers, sulfonic acid group-containing polymerizable monomers, and phosphoric acid group-containing polymerizable monomers. mer and their salts. Polymerizable monomers containing carboxylic acid groups include unsaturated mono- or polycarboxylic acids [(meth)acrylic acid (acrylic acid and/or methacrylic acid).

The same description will be used below. ), ethacrylic acid, crotonic acid, sorbic acid, maleic acid, itaconic acid, cinnamic acid, and their anhydrides [such as maleic anhydride].

Examples of polymerizable monomers containing sulfonic acid groups include aliphatic or aromatic vinylsulfonic acids (vinylsulfonic acid, allylsulfonic acid, vinyltoluenesulfonic acid, styrenesulfonic acid, etc.), (meth)acrylsulfonic acid [ Sulfoethyl (meth)acrylate, sulbopropyl (meth)acrylate, etc.], (meth)acrylamide sulfonic acid [2-acrylamido-2-methylpropanesulfonic acid, etc.], and the like.

As the polymerizable monomer containing a phosphoric acid group, (meth)acrylic acid hydroxyalkyl phosphate monoester [2-
Hydroxyethyl (meth)acryloyl phosphate-1.
, phenyl-2-acryloyloxyethyl phosphate-1
・etc.]. These acid group-containing monomers may be used alone, or two or more types (Jf may be used).

These salts include alkali metal salts (salts of sodium, potassium, lithium, etc.), alkaline earth metal salts (salts of calcium, magnesium, etc.), ammonium salts and amine salts (salts of methylamine, I-limethylamine, etc.). Examples include salts of alkanolamines; salts of alkanolamines such as 10-jetanolamine and jetanolamine), and two or more thereof. Among these, preferred are acids such as acrylic acid, methacrylic acid, vinylsulfonic acid, allylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and salts thereof;
Examples include amines such as N-diethylaminoethyl acrylate, N,N-diethylaminoethyl methacrylate-1, and salts thereof.

Examples of the lipophilic monomer include N-argyl (meth)acrylamide derivatives such as N-n-butylacrylamide and N-n-hexylacrylamide; (meth)acrylate derivatives such as ethyl acrylate and methyl methacrylate-1; Examples include acrylonitrile, methacrylonitrile, vinyl acetate, styrene, butadiene, and isoprene.

The crosslinking agent (C) includes (1) a compound having two polymerizable double bonds and (2) a compound having at least one polymerizable double bond and having at least one functional group reactive with the monomer. Examples include compounds that have individual properties.

Examples of the compound (1) include the following.

(2) Bis(meth)acrylamide: N,N'-alkylene (CI-C6) bis(meth)acrylamide, such as N,N'-methylenebisacrylamide.

■Di- or polyester of polyols and unsaturated mono- or polycarboxylic acids: Polyols [ethylene glycol, trimethylolpropane, glycerin, polyoxyethylene glycol,
Di- or tri-(meth)acrylic esters of polyoxypropylene glycol, etc.: unsaturated polyesters [obtained by reaction of the above polyols with unsaturated acids such as maleic acid] and di- or tri-(meth)acrylates
Acrylic esters [obtained by the reaction of polyepoxide and (meth)acrylic acid, etc.].

■Carbamyl ester: Polyisocyanate-1/[Tolylene diisocyanate!・、
Hegisamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate and an NCO group-containing prepolymer (f, lj by reaction of the above polyisocyanate with an active hydrogen atom-containing compound).

Carbamyl ester obtained by the reaction of hydroxyethyl (meth)acrylate and hydroxyethyl (meth)acrylate.

■Di- or polyvinyl compounds such as divinylbenzene, divinyltoluene, divinylxylene, divinyl ether, divinyl ketone, I-divinylbenzene, etc.

■ Di- or poly(meth)allyl ether of polyols: Polyols [alkylene gelate kohl, glycerin, polyalkylene kohl, polyalkylene polyol,
carbohydrates, etc.], such as di- or poly-(meth)allyl ethers such as polyethylene glycol diallyl ethers and allylated starches, allylated celluloses.

■ Di- or poly-allyl ester of polycarboxylic acid: diallyl phthalate, diallyl adipate, etc.

(meth)acrylic acid ester of polyethylene glycol monoallyl ether, etc., ester of unsaturated mono- or 7jυ carboxylic acid and mono(meth)allyl ether of polyol;

■Allyloxyalkanes: such as tetraallyloxyethane.

Examples of compound (2) include (meth)acrylic acid and/or
or ethylenically unsaturated compounds containing groups reactive with other copolymerizable monomers, such as carboxyl groups and groups reactive with carboxylic anhydride groups (hydroxyl groups, epoxy groups, cationic groups, etc.). . Specifically, unsaturated compounds containing nonionic groups, such as hydroxyl group-containing unsaturated compounds [N-methylol (meth)acrylamide, etc.] and epoxy group-containing unsaturated compounds [glycidyl (
meth)acrylate] and cationic group-containing unsaturated compounds, such as quaternary ammonium base-containing unsaturated compounds [N, N, Nl-limethyl-N-(meth)acryloyloxyethyltrimethylammonium chloride, N, N, N- Examples include 1-liethyl-N-(meth)aqualyloxyethylammonium chloride, and unsaturated compounds containing a tertiary amino group [dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc.].

Among the crosslinking agents, preferred are bis(meth)acrylamide, di- or polyesters of polyols and unsaturated monocarboxylic acids, and allyloxyalkanes, and particularly preferred are N,N'-methylenebisacrylamide, These are ethylene glycol diacrylate, trimethylolpropane triacrylate and tetraallyloxyethane.

Although there is no particular restriction on the molar ratio of the monomer ([3) in the polymer, it is preferable that it does not exceed the ratio of the vinyl compound (A).

The amount of the crosslinking agent is usually 0.001 to 20%, based on the total amount of the monomer (B) that can be copolymerized with the vinyl compound (A).
Preferably it is 0.01 to 10%.

A known method may be used to polymerize the copolymer, for example, adding a monomer aqueous solution and a crosslinking agent to starch, if necessary.
In the aqueous solution polymerization method or graft polymerization method in which polymerization is carried out in the presence of polysaccharides such as cellulose, monomers and crosslinking agents are dissolved in an aqueous solvent to form an aqueous solution, and then a hydrophobic solvent (hexane) is added in the presence of a dispersant if necessary. , cyclohexane, toluene, chlorobenzene, etc.) and the so-called reverse N suspension polymerization method. Further, known methods of initiating polymerization using radiation, electron beams, ultraviolet rays, etc. are also possible.

In addition, as an example of its manufacturing method, for example, Japanese Patent Publication No. 4943
No. 395, Special Publication No. 53-46199, Special Publication No. 53-1
No. 3495, JP-A-55-84304, JP-A-56-
No. 36504 and is described in each publication.

The heat-responsive material thus obtained has the function of absorbing water and swelling at low temperatures, and releasing water and contracting at high temperatures even in the presence of a large amount of water.

Therefore, for example, the heat-responsive material of the present invention may be used in temperature sensors, concentration and separation agents for water-soluble organic substances, mechanochemical device materials, toy regulators, anti-condensation agents, and the like.

[Examples] Hereinafter, the present invention will be further explained with reference to Examples, but the present invention is not limited thereto. In the following, parts and % indicate parts by weight and % by weight, respectively. The evaluation method was as follows. That is, 1g of sample is 50ml
The mixture was placed in a graduated cylinder, 50 ml of ion-exchanged water was added, and the mixture was allowed to swell at room temperature (21°C) for 1 hour. The graduated cylinder was then immersed in a water bath at 60''C for 30 minutes.The volume occupied by the sample at room temperature and at 60°C was read from the graduations on the graduated cylinder.

Example 1 30 parts of a vinyl compound represented by CH2=C(CHs)Co (OC2H4) 40H, 0.3 parts of N,N'-methylenebisacrylamide, and 150 parts of water were placed in a stainless steel Dewar bottle and replaced with nitrogen gas. Thereafter, a solution prepared by dissolving 0.15 parts of ammonium persulfate in 10 parts of water and a solution prepared by dissolving hydrogen sulfite Litrilim o, 7m+< in 10 parts of water were added simultaneously, and the aqueous solution was adiabatically polymerized.

The obtained gel was cut into pieces, dried, and further crushed to obtain a heat-responsive material L. A section of 32 to 100 meshes was collected and used as an evaluation sample. The evaluation results are shown in Table-2.

Note that the thermal response was reversible.

Examples 2 to 7 A thermally responsive material was obtained in the same manner as in Example 1, except that the compositions of the vinyl compound (8) and the monomer (B) were changed as shown in Table 1. Table 2 shows the results of collecting and evaluating 32,100 mesh sections. In addition, the thermal responsiveness of Examples 2 to 7 was reversible. □ Table-1 Table-2 [Effects of the Invention] The heat-responsive material of the present invention absorbs water and swells in a low temperature range of usually 40 to 50°C or less and retains 10 times or more of its own weight in water. In high temperature ranges above °C, water is released and the volume contracts, and this has a reversible thermal response that can be repeated.In addition, compared to conventional compounds, it has a cheaper and simpler manufacturing method. There is.

Applications of the heat-responsive material of the present invention include temperature sensors, concentration and separation agents for water-soluble organic substances, mechanochemical element materials M'
4. Possible applications and uses include toy humidity conditioners and anti-condensation agents.

Claims (1)

[Claims] 1. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ [I] (In the formula, R is hydrogen or a methyl group, n is a real number of 2 or more,
m is 0 or a positive real number. 1. A heat-responsive material comprising a copolymer of a vinyl compound (A) represented by (A), a crosslinking agent (C), and, if necessary, another copolymerizable monomer (B). 2. The thermally responsive material according to claim 1, wherein n is a real number of 2 to 10 and m is a real number of 0 to 5.