WO2010079680A1

WO2010079680A1 - Heat-responsive polymer gel film

Info

Publication number: WO2010079680A1
Application number: PCT/JP2009/071136
Authority: WO
Inventors: 隆行荒井; 十志和高田
Original assignee: リンテック株式会社
Priority date: 2009-01-07
Filing date: 2009-12-18
Publication date: 2010-07-15
Also published as: TWI485190B; JP2010159337A; JP5683072B2; TW201035186A

Abstract

Disclosed is a heat-responsive polymer gel film which is characterized in that the difference of the total light transmittance before and after thermal stimulation is not less than 50%. The heat-responsive polymer gel film changes in the degree of transparency by thermal stimulation. The temperature of the thermal stimulation is preferably not less than room temperature but not more than 100˚C. The heat-responsive polymer gel film preferably contains not less than 10% by mass of water, and a material constituting the heat-responsive polymer gel film preferably contains a rotaxane structure.

Description

Thermoresponsive polymer gel film

The present invention relates to a thermoresponsive polymer gel film in which a thermoresponsive polymer gel is formed into a film, and more particularly to a thermoresponsive polymer gel film whose transparency is changed by thermal stimulation.

In recent years, thermoresponsive polymer gels whose dimming characteristics are changed by thermal stimulation have been proposed. For example, Patent Document 1 discloses a functional polymer gel in which fine particles serving as crosslinking points are uniformly dispersed, and Patent Document 2 discloses a polymer that interacts with each other. It contains two kinds of polymer compounds forming a complex and a liquid, one of the polymer compounds forms a three-dimensional crosslinked body, and the other has an ionic functional group and dissolves in the liquid. In addition, a polymer gel composition characterized in that it is inherent in a three-dimensional crosslinked body is disclosed. Patent Document 3 discloses a stimulus-responsive polymer gel and the stimulus-responsive polymer gel dispersed and fixed. A polymer gel fixing resin composition, the polymer gel fixing resin composition comprising a crosslinkable polymer having a weight average molecular weight of 100,000 or more and a crosslinking agent. A polymer gel composition is disclosed.

JP 2006-36811 A JP 2006-249258 A JP 2007-146000 A

The conventional thermoresponsive polymer gel is all finely divided and dispersed in a liquid, and therefore cannot be held unless sealed in a sealing member described in Patent Document 2 or 3, for example. . The polymer gel thus finely divided and dispersed in the liquid cannot be formed into a film, and the polymer gel encapsulated in a sealing member or the like has a problem of low versatility.

The present invention has been made in view of such a situation, and an object thereof is to provide a thermoresponsive polymer gel film whose transparency is changed by thermal stimulation.

In order to achieve the above object, the present invention provides a thermoresponsive polymer gel film characterized in that the difference in total light transmittance before and after thermal stimulation is 50% or more (Invention 1). .

More specifically, the present invention relates to a case where a gel film having a dry thickness of 1000 μm (1.0 mm) is adjusted to a moisture content of 20 mass% and heated from room temperature (preferably 23 ° C.) to 60 ° C. When the total light transmittance according to JIS K7105 is 0 to 30% (preferably 0 to 20%, more preferably 0 to 10%) at room temperature (preferably 23 ° C.), 70% is heated by heating to 60 ° C. Provided is a thermoresponsive polymer gel film that changes to ˜99% (preferably 80 to 99%, more preferably 85 to 99%), and the difference between the total light transmittances is 50% or more.

In the above invention (Invention 1), the temperature of the thermal stimulation is preferably not less than room temperature and not more than 100 ° C. (Invention 2).

In the above inventions (Inventions 1 and 2), the thermoresponsive polymer gel film preferably contains 10% by mass or more of moisture (Invention 3).

In the above inventions (Inventions 1 to 3), the material constituting the thermoresponsive polymer gel film preferably contains a rotaxane structure (Invention 4).

In the above invention (Invention 4), an inclusion complex can be formed with the polymer having two or more cyclic moieties, and a polymer having a blocking functional group at one end and a polymerizable functional group at the other end. It is obtained by copolymerizing the linear molecule and a thermoresponsive component via the polymerizable functional group of the linear molecule of the polymer crosslinking precursor obtained by mixing the linear molecule. It is preferable to contain a crosslinked polymer (Invention 5).

In the above invention (Invention 5), the cyclic portion of the polymer is at least one selected from the group consisting of α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin, or a cyclic polyether, a cyclic polyester and a cyclic polyether It is preferably at least one selected from the group consisting of amines and cyclic polyamines (Invention 6).

In the above inventions (Inventions 5 and 6), the thermoresponsive component is preferably a polymerizable compound having an N-isopropylamide group (Invention 7).

According to the present invention, a thermoresponsive polymer gel film whose transparency is changed by thermal stimulation can be obtained.

It is a schematic diagram which shows the manufacturing process of the thermoresponsive polymer crosslinked body which concerns on one Embodiment of this invention. It is a schematic diagram which shows the structure of the thermoresponsive polymer crosslinked body which concerns on one Embodiment of this invention. It is a figure explaining the manufacturing method of the gel-like film of a thermoresponsive polymer crosslinked body (E) in an Example. It is a photograph which shows the state in room temperature (23 degreeC) before the thermal stimulation of the thermoresponsive polymer gel film of Example 1. FIG. It is a photograph which shows the state in 60 degreeC after the heat stimulation of the thermoresponsive polymer gel film of Example 1. FIG.

Hereinafter, embodiments of the present invention will be described.
The thermoresponsive polymer gel film according to this embodiment has a difference in total light transmittance before and after thermal stimulation of 50% or more, preferably 60% or more, more preferably 70 to 99%. . The total light transmittance refers to a value measured according to JIS K7105. Thus, a thermoresponsive polymer gel whose total light transmittance is changed by a considerable amount by thermal stimulation and formed into a film has not been known.

Here, the temperature of the thermal stimulation is preferably room temperature (preferably 23 ° C.) or more and 100 ° C. or less, particularly preferably 40 to 100 ° C., and more preferably 60 ° C.

The thickness of the thermoresponsive polymer gel film varies depending on the water content, but is usually 50 to 5000 μm, preferably 100 to 2000 μm, and particularly preferably 150 to 1500 μm. The thermoresponsive polymer gel film of the present embodiment may satisfy the above characteristics at any of the above thicknesses, but more specifically, the thickness of the dry thermoresponsive polymer gel film not containing water. It is particularly preferable that the above characteristics are satisfied in a state where a predetermined amount of water described later is contained in a sample having a thickness of 1000 μm (1.0 mm).

The above characteristics define the degree of change in the transparency of the thermoresponsive polymer gel film. For example, in the case of the present embodiment, by applying a heating stimulus to the thermoresponsive polymer gel film, the thermoresponsive polymer gel film changes from transparent or translucent to white, that is, the total light transmittance is Therefore, the difference in total light transmittance is calculated by subtracting the total light transmittance after thermal stimulation from the total light transmittance before thermal stimulation. Specific measurement conditions are shown in the test examples described later.

The thermoresponsive polymer gel constituting the thermoresponsive polymer gel film according to the present embodiment contains a thermoresponsive polymer component and moisture, but moisture in the thermoresponsive polymer gel The content is preferably 10% by mass or more, particularly preferably 15 to 99% by mass, and further preferably 20% by mass. When the water content in the thermoresponsive polymer gel is 10% by mass or more, the above-described transparency change characteristic is effectively exhibited.

More specifically, for example, in the present embodiment, a gel film having a dry thickness of 1000 μm (1.0 mm) is adjusted to a water content of 20 mass%, and the room temperature (preferably 23 ° C.) to 60 When heated to ℃, the total light transmittance according to JIS K7105 is 0 to 30%, preferably 0 to 20%, more preferably 0 to 10% at room temperature (preferably 23 ° C). The heat-responsive polymer gel film changes from 70 to 99%, preferably from 80 to 99%, more preferably from 85 to 99%. The difference in total light transmittance at both temperatures is as described above. The rate of change of the total light transmittance (%) is not particularly limited, but is preferably within 5 minutes.

A preferable thermoresponsive polymer component contained in the thermoresponsive polymer gel is a thermoresponsive polymer crosslinked product (E) produced by the method schematically shown in FIG. Hereinafter, the manufacturing method of a thermoresponsive polymer crosslinked body (E) is demonstrated.

First, a polymer having two or more cyclic moieties (hereinafter referred to as “polymer (A)”) and a linear molecule having a blocking group at one end and a polymerizable functional group at the other end (hereinafter referred to as “polymer (A)”) (Referred to as “linear molecule (B)”) (see FIG. 1).

The cyclic part of the polymer (A) can include the linear molecule (B) and can move on the linear molecule (B) in this state. In the present specification, “cyclic” of the “cyclic portion” means substantially “cyclic”, and if the cyclic portion is movable on the linear molecule (B), the cyclic portion is completely May not be closed, for example, may have a helical structure. Further, the polymer (A) is a multimer having a cyclic molecule having a relatively large molecular weight as a constituent part as described later, and its own molecular weight becomes enormous even if the number of repetitions is small. The polymer (A) is a convenient name used for this purpose, and includes those having a repeating number of oligomer regions of about 2 to 10 mer.

The molecules constituting the cyclic portion (cyclic molecules) include cyclodextrins such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin, or cyclic polyether, cyclic polyester, cyclic polyetheramine, cyclic polyamine, and cyclodextrin. A cyclic molecule such as a fan is preferable, and two or more kinds of these cyclic molecules are mixed in the polymer (A) or the polymer cross-linking precursor (C) described later or the heat-responsive polymer cross-linked product (E) described later. It may be.

When the cyclic molecule is a cyclodextrin, a polymer chain and / or a substituent that can improve the solubility of the polymer (A) in the linear molecule (B) is introduced into the hydroxyl group of the cyclodextrin. It may be. Examples of such a polymer chain include an oxyethylene chain, an alkyl chain, and an acrylate chain. On the other hand, examples of the substituent include an acetyl group, an alkyl group, a trityl group, a tosyl group, a trimethylsilane group, and a phenyl group.

Specific examples of the cyclic molecule other than cyclodextrin include crown ether or derivatives thereof, cyclic lactone or derivatives thereof, calixarene or derivatives thereof, azacyclophane or derivatives thereof, thiacyclophane or derivatives thereof, cryptand or derivatives thereof, etc. Is mentioned.

As the cyclic molecule, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, and crown ether are preferable because linear molecules are easy to penetrate in a skewered manner. Α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin are particularly preferred because they form a complex.

The number of cyclic molecules in the polymer (A) is 2 or more, preferably 3 to 50, particularly preferably 3 to 5. By having two or more cyclic molecules, a plurality of linear molecules (B) can thereby be included, and the linear molecules (B) are polymerized by polymerizing the linear molecules (B). A plurality of (co) polymers included in the structural unit are bonded to each other via the polymer (A) to form a crosslinked structure. Three or more cyclic molecules are more preferable because the cross-linked structure becomes dense and the strength can be improved without impairing the stress relaxation property of the obtained thermoresponsive polymer crosslinked product (E).

The structure of the polymer (A) is preferably a structure in which two or more cyclic molecules are linked by a linking moiety. The raw material compound (linking molecule) serving as the linking moiety is preferably a molecule that does not form or is difficult to form an inclusion complex with a cyclic molecule. By using such a linking molecule, when the polymer (A) is synthesized, the cyclic molecule can be linked without closing the opening of the cyclic molecule.

Such a linking molecule may be linear or branched, but preferably has a side chain that is somewhat bulky. For example, when the cyclic molecule is α-cyclodextrin, it preferably has a side chain that is bulkier than a methyl group. That is, from the viewpoint of not forming an inclusion complex with the cyclic molecule, preferred linking molecules include polypropylene glycol, polyacrylic acid ester, polydimethylsiloxane, polyisoprene and the like, and among them, polypropylene glycol is particularly preferable.

The number average molecular weight (Mn) of one linking molecule is preferably 100 to 100,000, and particularly preferably 500 to 10,000. If the number average molecular weight of the linking molecule is less than 100, the openings of the cyclic molecules of the formed polymer (A) are too close to each other so that it is difficult to form a cross-linked structure and the effect based on the interlock structure is sufficiently exerted. There is a risk that it will not be. On the other hand, if the number average molecular weight of the linking molecule exceeds 100,000, the compatibility with the linear molecule (B) or the like may be deteriorated and it may be difficult to form a crosslinked structure.

Note that the interlock structure refers to a mechanical coupling structure that uses neither a non-covalent bond nor a covalent bond. The interlock structure of the present embodiment is the main body of each linear molecule of two different polymers having the linear molecule (B) as a structural unit at the opening of at least two cyclic molecules of the polymer (A). Each part (described in detail later) penetrates, and each terminal side of the main body part is protected by a blocking group, so that the main body part cannot be pulled out from the opening (rotaxane structure). The two polymers cannot be separated. Due to the interlock structure, the polymer (A) can move through the opening of the cyclic molecule along the main body portion of the linear molecule (B) of the polymer. Compared with the conventional crosslinked structure by covalent bond, it has a binding property of the same strength as that of the covalently crosslinked structure, although the degree of freedom of the crosslinked part is large.

The mass average molecular weight (Mw) of the polymer (A) depends on the kind of the cyclic molecule, but is usually preferably 1,000 to 1,000,000, particularly 3,000 to 100,000. It is preferable. When the mass average molecular weight of the polymer (A) is less than 1,000, the number of cyclic molecules is often less than 2, and there is a possibility that an interlock structure cannot be formed. Since the parts are very close to each other, the effect based on the interlock structure may not be sufficiently exhibited. On the other hand, when the mass average molecular weight of the polymer (A) exceeds 1,000,000, the compatibility with the linear molecule (B) or the like may be deteriorated and it may be difficult to form a crosslinked structure.

Polymer (A) can be synthesized by a conventional method. For example, the polymer (A) is obtained by reacting a cyclic molecule having a functional group with a linking molecule having a reactive group capable of reacting with the functional group of the cyclic molecule at the terminal. Specifically, when synthesizing the polymer (A) in which the cyclic molecule is α-cyclodextrin and the linking molecule is polypropylene glycol, α-cyclodextrin and polypropylene glycol having a reactive group at the terminal are mixed. The polymer (A) can be obtained by adding a catalyst if desired and reacting both.

As the functional group of the cyclic molecule bonded to the linking molecule, for example, a hydroxyl group, a carboxyl group, an amino group, a thiol group and the like are preferable, and as the reactive group at the terminal of the linking molecule, for example, an isocyanate group, an epoxy group, an aziridine Groups etc. are preferred. Examples of the linking molecule include isocyanate compounds such as xylylene diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, isophorone diisocyanate, and epoxy compounds such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and 1,6-hexanediol glycidyl ether. A compound having an aziridine compound such as N, N-hexamethylene-1,6-bis (1-aziridinecarboxamide) at the terminal can be used.

The linear molecule (B) is a linear molecule or substance that is included in the cyclic molecule of the polymer (A) and can be integrated by a mechanical bond rather than a chemical bond such as a covalent bond. And having a blocking group at one end and a polymerizable functional group at the other end. In the present specification, “linear” of “linear molecule” means substantially “linear”. That is, as long as the cyclic molecule of the polymer (A) can move on the linear molecule (B), the linear molecule (B) may have a branched chain.

As a molecule constituting the portion (main body portion) excluding the blocking group and the polymerizable functional group corresponding to both ends of the linear molecule (B), it penetrates through the opening of the cyclic molecule of the polymer (A). It is sufficient that the molecule has a size that can be obtained. For example, when the cyclic molecule of the polymer (A) is α-cyclodextrin, polyethylene glycol, polytetrahydrofuran, polyethylene, polycaprolactone and the like are preferable, and the linear molecule (B) having a main body portion composed thereof is Two or more kinds may be mixed in the polymer cross-linking precursor (C) or the thermoresponsive polymer cross-linked product (E).

The number average molecular weight (Mn) of the molecules constituting the main part of the linear molecule (B) is preferably from 100 to 300,000, particularly preferably from 200 to 200,000, more preferably from 300 to Preferably it is 100,000. When the number average molecular weight is less than 100, the amount of movement of the cyclic molecule on the linear molecule (B) becomes small, and the resulting thermoresponsive polymer crosslinked product (E) does not have sufficient flexibility. There is a fear. Moreover, when a number average molecular weight exceeds 300,000, there exists a possibility that the solubility to a solvent may worsen.

The blocking group is not particularly limited as long as the cyclic molecule of the polymer (A) that includes the linear molecule (B) does not leave and can maintain the form of the inclusion complex. Examples of such groups include bulky groups and ionic groups.

As the blocking group, for example, dialkylphenyl groups, dinitrophenyl groups, cyclodextrins, adamantane groups, trityl groups, fluoresceins, pyrenes, anthracenes and the like are preferable. Or 2 or more types may be mixed in the polymer crosslinked body. As a capping agent that forms a blocking group by binding to one end of the linear molecule (B), for example, dimethylphenyl isocyanate, tritylphenyl isocyanate, 2,4-dinitrofluorobenzene, adamantaneamine and the like are preferably used. .

The polymerizable functional group is not particularly limited as long as it can copolymerize the linear molecule (B) and the thermoresponsive component (D) described later via the polymerizable functional group. As such a polymerizable functional group, for example, (meth) acryloyl group, vinyl group, epoxy group, acetylene group, oxetanyl group and the like are preferable.

The linear molecule (B) can be synthesized by a conventional method. For example, a linear molecule having a polymerizable functional group at one end, or a linear molecule having a different polymerizable functional group at both ends, and a capping agent for a blocking group are reacted, and one end is A linear molecule (B) can be obtained by leaving the above-mentioned polymerizable functional group and adding a blocking group to the other end.

As an example, a linear molecule having a hydroxyl group at one end and a (meth) acryloyl group at the other end and a dialkylphenyl group having an isocyanate group are mixed, and if desired, a catalyst is added and both are reacted. Thus, a linear molecule (B) having a dialkylphenyl group as a blocking group at one end and a (meth) acryloyl group as a polymerizable functional group at the other end is obtained.

When the polymer (A) and the linear molecule (B) described above are prepared, the polymer (A) and the linear molecule (B) are mixed to form an inclusion complex for all or part of the polymer (A) and the linear molecule (B). A polymer crosslinking precursor (C) is produced. That is, one opening of the cyclic molecule of the polymer (A) is penetrated like a skewer with the linear molecule (B), and at least one of the remaining openings of the cyclic molecule of the polymer (A) A polymer cross-linking precursor having a structure in which two or more linear molecules (B) are included in a plurality of cyclic molecules of the same polymer (A), penetrating by another linear molecule (B) (C) is manufactured (see FIG. 1).

The polymer cross-linking precursor (C) has a structure in which the above-mentioned inclusion complex is formed, but all the openings of the cyclic molecule of the polymer (A) are in such a state. You don't need to be. That is, in the polymer (A) as a mixture, the structure in which the linear molecule (B) is penetrated in only one of the openings of the cyclic molecule, and further the cyclic molecule of the polymer (A) The opening may have a structure in which the linear molecule (B) is not penetrated in a skewered manner, or the linear molecule (B) as a mixture not included in the polymer (A) May be included.

The polymer crosslinking precursor (C) as described above is prepared by mixing the polymer (A) and the linear molecule (B) in a solvent, for example, water, aqueous sodium hydroxide, dimethylformamide (DMF) and water. In a mixed solution of methanol and water or the like (for example, by adding the linear molecule (B) to the polymer (A) solution) and stirring the solution. it can. The fact that the polymer crosslinking precursor (C) has been obtained can be judged by an increase in the viscosity of the solution.

撹拌 There is no particular limitation on the stirring method, and stirring can be performed by a method such as mechanical stirring treatment or ultrasonic treatment at room temperature or an appropriately controlled temperature. In particular, stirring by ultrasonic treatment is preferable. The stirring time is preferably performed under conditions of several minutes to 1 hour. There are no particular limitations on the ultrasonic irradiation conditions, but it is preferably performed at a frequency of 20 to 40 kHz.

Once the polymer cross-linking precursor (C) is produced as described above, the linear molecule is introduced via the polymerizable functional group of the linear molecule (B) included in the cyclic molecule of the polymer (A). (B) and a thermoresponsive component (D) are copolymerized to obtain a thermoresponsive polymer crosslinked product (E) (see FIG. 1). This thermoresponsive polymer crosslinked product (E) includes a rotaxane structure as an interlock structure.

As the thermoresponsive component (D), it exhibits the thermal response of (1) or (2) above and is copolymerized with the linear molecule (B) via the polymerizable functional group of the linear molecule (B). Possible monomers, oligomers or polymers are selected.

A preferred thermoresponsive component (D) is preferably a polymerizable compound having an N-isopropylamide group. The polymerizable compound may be a monomer, or an oligomer or polymer as long as it has a polymerizable functional group. When the polymerizable compound is a polymer, the mass average molecular weight (Mw) is preferably 1,000,000 or less, particularly preferably 100,000 or less. If the mass average molecular weight (Mw) is too large, the compatibility with other components is poor, resulting in a decrease in polymerizability and film-forming property, and there is a possibility that the stimulus response speed also decreases.

The polymerizable functional group of the polymerizable compound is not particularly limited as long as it is copolymerizable with the linear molecule (B). Examples of the polymerizable functional group include a (meth) acryloyl group, a vinyl group, an epoxy group, an acetylene group, and an oxetanyl group, and a (meth) acryloyl group in consideration of the speed of polymerization and availability. A vinyl group is particularly preferred.

Considering the above, N-isopropylacrylamide is most preferable as the thermoresponsive component (D).

Thermal responsiveness in which water or the like is contained in the thermoresponsive polymer crosslinked product (E) using the polymerizable compound having N-isopropylamide group (preferably N-isopropylacrylamide) as the thermoresponsive component (D). The polymer gel changes remarkably from transparent or translucent to white by heat stimulation, and exhibits the above-described transparency change characteristics.

An example of a thermoresponsive polymer crosslinked product (E) using N-isopropylacrylamide as the thermoresponsive component (D) is schematically shown in FIG. However, the thermoresponsive polymer gel of the present invention is not limited to the embodiment of FIG. In the thermoresponsive polymer crosslinked product (E) shown in FIG. 2, a polymer BD ₁ obtained by copolymerizing a linear molecule (B) and N-isopropylacrylamide which is a thermoresponsive component (D), It is composed of BD ₂ and polymer A _X in which two or more cyclic molecules are bonded by a linking molecule. Then, _{B X} and _{B Y} derived from a linear molecule of the polymer _BD 1, _BD ₂ (B) are each polymer _{A X} through the opening of separate cyclic molecule, and the _{B X} and _{B Y} It has a structure (interlock structure) that cannot be removed by a blocking group present at the end. Incidentally, FIG. 2 in the heat-responsive component (D) has been shown in a state of being incorporated into the main chain of the polymer _BD 1, BD _2, may be present in the side chain of the polymer _BD 1, BD _2, it may be present in the polymer a _X.

The polymerization reaction may be carried out by a conventional method, and is usually carried out by radical polymerization. For example, if desired, a photopolymerization initiator is added to the solution containing the polymer crosslinking precursor (C) and the thermoresponsive component (D) and irradiated with ultraviolet rays, or a thermal polymerization initiator is added. When heated, the linear molecule (B) and the thermoresponsive component (D) are copolymerized.

The photopolymerization initiator is not particularly limited as long as it is usually used, for example, benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, Methyl benzoin benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyldiphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β- Chloranthraquinone, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, (2,4,6-trimethylbenzyldiph Yl) phosphine oxide, 2-benzothiazole -N, can be used N- diethyldithiocarbamate and the like. In addition, a photoinitiator may be used individually by 1 type and may use 2 or more types together.

The ultraviolet rays are obtained with a high-pressure mercury lamp, a fusion H lamp, a xenon lamp or the like, and the irradiation amount is usually 100 to 500 mJ / cm ² .

On the other hand, the thermal polymerization initiator is not particularly limited as long as it is usually used, and for example, benzoyl peroxide, azobisisobutyronitrile (AIBN) and the like can be used. The heating temperature in the case of using the thermal polymerization initiator may be appropriately selected depending on the decomposition temperature of the thermal polymerization initiator, but is usually about 0 to 130 ° C.

Purification of the thermoresponsive polymer crosslinked product (E) may be performed by a conventional method, for example, sequentially washed with water, tetrahydrofuran and dimethylformamide.

According to the above method, the polymer (A) and the linear molecule (B) are simply mixed and stirred without passing through the isolation and purification of the pseudorotaxane, so that the polymer crosslinked precursor (C) can be easily produced. In addition, the obtained polymer cross-linking precursor (C) includes a rotaxane structure having an interlock structure by copolymerizing the linear molecule (B) and the thermoresponsive component (D). The thermoresponsive polymer crosslinked product (E) can be easily produced.

In order to obtain the thermoresponsive polymer gel film according to this embodiment, for example, the polymer cross-linking precursor (C) and the thermoresponsive component (D) are mixed and poured into a mold, or rolled to -A film-like thermally responsive polymer crosslinked body (E) is formed by coating on a substrate by a roll method, and then copolymerizing by heating or ultraviolet irradiation, and the film-like thermally responsive polymer. What is necessary is just to include the predetermined amount of moisture described above in the crosslinked body (E).

The obtained thermoresponsive polymer gel film changes from transparent or translucent to white by thermal stimulation, and can satisfy the change characteristic of the total light transmittance. This heat-responsive polymer gel film is expected to be used for heat-sensitive sensors, temperature control films, heat-responsive light-shielding films, and the like.

The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

Hereinafter, the present invention will be described more specifically with reference to examples and the like, but the scope of the present invention is not limited to these examples and the like.

[Example 1]
(1) Synthesis of polymer (A) 5 g of α-cyclodextrin (manufactured by Nacalai Tesque) was dissolved in 50 ml of dimethylformamide, and to this solution was added tolylene 2,4-diisocyanate-terminated polypropylene glycol (manufactured by Aldrich, Mn: 1,000). ) 3.4 g and 200 mg of dibutyltin dilaurate (manufactured by Tokyo Chemical Industry Co., Ltd.), which is a tin catalyst, were added and stirred overnight at room temperature.

The above reaction solution is poured into ether and precipitated, and the collected solid is dried, washed with water and dried again, and has α-cyclodextrin as a cyclic molecule and polypropylene glycol as a linking molecule, via a linking molecule. Thus, 4.6 g of polymer (A) having 3 to 5 cyclic molecules connected thereto was obtained.

(2) Synthesis of linear molecule (B) 5 g of polyethylene glycol (manufactured by Wako Pure Chemical Industries, Mn: 1000) was dissolved in 50 ml of methylene chloride, and 3,5-dimethylphenyl isocyanate (manufactured by Aldrich) was dissolved in this solution. 1.6 g and 200 mg of dibutyltin dilaurate (manufactured by Tokyo Chemical Industry Co., Ltd.) as a tin catalyst were added and stirred overnight at room temperature.

Next, 1.7 g of 2-methacryloyloxyethyl isocyanate (manufactured by Showa Denko KK, Karenz MOI) and 100 mg of dibutyl tin dilaurate (manufactured by Tokyo Kasei Co., Ltd.) as a tin catalyst were added to the above solution and further stirred overnight at room temperature. .

The resulting solution was concentrated and then precipitated by pouring into diethyl ether cooled to −75 ° C., and the precipitate was collected. Thus, 3.8 g of polyethylene glycol (MA-PEG-DPI; linear molecule (B)) having a blocking group consisting of a 3,5-dimethylphenyl group at one end and a methacryloyl group at the other end Got.

(3) Production of polymer cross-linking precursor (C) 300 mg of polymer (A) was dissolved in 1 ml of 0.4 wt% sodium hydroxide aqueous solution, and 112 mg of linear molecule (B) was added to this solution mechanically. When ultrasonic irradiation (35 Hz) was performed for 300 seconds with stirring, the solution became cloudy and the viscosity increased. Such a cloudy substance having an increased viscosity is considered to be a polymer crosslinking precursor (C) in which the cyclic molecule of the polymer (A) includes the linear molecule (B).

(4) Production of thermoresponsive polymer crosslinked product (E) To the above cloudy substance considered to be a polymer crosslinked precursor (C), 2.0 g of N-isopropylacrylamide was added as a thermoresponsive component (D) and homogeneous Stir until. Next, 40 μl of a 1: 1 eutectic mixture of 1-hydroxy-cyclohexyl-phenyl-ketone and benzophenone (manufactured by Ciba Specialty Chemicals, IRUGACURE 500), which is a photopolymerization initiator, was added, and after deaeration with a vacuum pump Went. Thereafter, as shown in FIG. 3, the mixed solution obtained by the above operation is poured inside the silicone rubber mold (thickness 1 mm) on the glass plate, and the glass plate is covered so that air does not enter, A gel-like film was obtained by irradiating ultraviolet rays for 3 minutes (irradiation conditions: illuminance: 3.0 mW / cm ² , light amount: 300 mJ / cm ² ).

The obtained gel-like film is thermally responsive to the linear molecule (B) via the polymerizable functional group (methacryloyl group) of the linear molecule (B) in the polymer crosslinking precursor (C). Thermally responsive polymer crosslinked product (E) obtained by copolymerization with component (D) (polymer (A) is encapsulated with a polymer side chain having a blocking group at its end, and is thermally responsive. It is considered that the polymer of the component (D) is a thermoresponsive polymer crosslinked product (E)) comprising the polymer main chain.

The obtained thermoresponsive polymer cross-linked product (E) comprising a gel-like film is taken out by removing the upper glass plate shown in FIG. 3, and then washed by immersing in water, tetrahydrofuran and dimethylformamide in turn. It was dried to obtain a transparent thermoresponsive polymer crosslinked product film (thickness: 1.0 mm, non-stretched).

Furthermore, a transparent thermoresponsive polymer gel film is obtained by adding moisture to the thermoresponsive polymer crosslinked film at room temperature (23 ° C.) so that the moisture content is 20% by mass. Obtained.

[Comparative Example 1]
Except for using 44 mg of polyethylene glycol diacrylate (corresponding to a crosslinking agent) in place of the polymer (A) in Example 1, a thermoresponsive polymer crosslinked film (thickness: 1.0 mm, Non-stretched). Furthermore, a transparent thermoresponsive polymer gel film is obtained by adding moisture to the thermoresponsive polymer crosslinked film at room temperature (23 ° C.) so that the moisture content is 20% by mass. Obtained.

[Test Example 1] (Measurement of total light transmittance)
About the thermoresponsive polymer gel films obtained in Examples and Comparative Examples, in accordance with JIS K7105, using an integrating sphere type light transmittance measuring device (NDH-2000, manufactured by Nippon Denshoku Industries Co., Ltd.), room temperature ( 23 ° C.) and 60 ° C., and the total light transmittance was measured. The measurement of the total light transmittance after heating to 60 ° C. was performed within 5 minutes from the start of heating.

The difference in total light transmittance was calculated by subtracting the total light transmittance at 60 ° C. after thermal stimulation from the total light transmittance at room temperature (23 ° C.) before thermal stimulation measured as described above. The results are shown in Table 1. Moreover, the photograph of the state in the room temperature (23 degreeC) before thermal stimulation of the thermoresponsive polymer gel film of Example 1 is shown in FIG. 4, and the photograph of the state in 60 degreeC after thermal stimulation is shown in FIG.

From Table 1, it can be seen that the heat-responsive polymer gel film of Example 1 is significantly lower in total light transmittance by heating than the film of Comparative Example 1, and satisfies the requirements of the present invention. Moreover, it can be understood more clearly from the photographs of FIGS. 4 and 5 that the change in the total light transmittance due to thermal stimulation is large in the thermoresponsive polymer gel film of Example 1.

The heat-responsive polymer gel film according to the present invention is expected to be used for heat-sensitive sensors, temperature control films, heat-responsive light-shielding films, and the like.

Claims

A thermoresponsive polymer gel film characterized in that the difference in total light transmittance before and after thermal stimulation is 50% or more.
The heat-responsive polymer gel film according to claim 1, wherein the temperature of the thermal stimulation is not less than room temperature and not more than 100 ° C.
The thermoresponsive polymer gel film according to claim 1 or 2, wherein the thermoresponsive polymer gel film contains 10% by mass or more of moisture.
4. The heat-responsive polymer gel film according to claim 1, wherein the material constituting the heat-responsive polymer gel film includes a rotaxane structure.
Obtained by mixing a polymer having two or more cyclic moieties and a linear molecule capable of forming an inclusion complex with the polymer having a blocking group at one end and a polymerizable functional group at the other end. Containing a crosslinked polymer obtained by copolymerizing the linear molecule and a thermoresponsive component via a polymerizable functional group of the linear molecule of the obtained polymer crosslinking precursor. The heat-responsive polymer gel film according to claim 4.
The cyclic portion of the polymer is at least one selected from the group consisting of α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin, or from the group consisting of cyclic polyether, cyclic polyester, cyclic polyetheramine and cyclic polyamine. The thermoresponsive polymer gel film according to claim 5, which is at least one selected.
The thermoresponsive polymer gel film according to claim 5 or 6, wherein the thermoresponsive component is a polymerizable compound having an N-isopropylamide group.