JP2013014641A - Thermally responsive polyurethane, thermally responsive polyurethane sheet, and dimming member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substance thermally excellent in the optical aspect and thermally responsive, and a sheet and a dimming member utilizing the heat responsibility.SOLUTION: A thermally responsive polyurethane is prepared by reacting a polyester polyol having a melting point of 40 to 70°C and a number-average molecular weight of 800 to 10,000 with a tri- or more functional isocyanate, and exhibits reversible thermal responsibility to light transmittance wherein when the polyurethane is heated to a temperature equal to or higher than the melting point of the polyester polyol, light transmittance increases, and when being cooled to lower than the melting point, the light transmittance decreases.

Description

  The present invention relates to a heat-responsive polyurethane, a heat-responsive polyurethane sheet, and a light control member.

Conventionally, it is reversible with respect to temperature so that it is a solid at room temperature, and when it is heated above a certain temperature, it becomes a clay and easily deforms, and when it is cooled to room temperature again, it becomes the original solid state Thermally responsive substances that change their properties are used in various applications.
For example, Patent Document 1 listed below provides easy deformability by heating for fixing a part of a human body such as a cast, for fixing earth and sand in road construction, and for fixing and protecting transported goods in article transportation. The use of heat-responsive polyurethane that can be described is described.

  The thermoresponsive substance can be changed in its properties by a simple operation such as heating / cooling, and therefore has a wide range of applications. Not only mechanical characteristics as shown in Patent Document 1, but also electrical characteristics and optical characteristics. Development of materials that exhibit thermal responsiveness is expected.

For example, in Patent Document 2 described below, it is described that a daylighting window having a blindfold effect is formed of a milky white resin plate. However, light transmittance is thermal responsiveness in a temperature range that can be reached by irradiation with sunlight. If a substance showing the above can be obtained, a blindfold sheet is formed with the substance and attached to the window glass, etc., and in the daytime, transparency is exhibited by the temperature rise accompanying sunlight irradiation, and the indoor state is visually recognized from the outside. At night when it is easy to occur, it can cause cloudiness and naturally exhibit a blinding effect.
In addition, if a member exhibiting thermal responsiveness in such light transmittance is obtained, a light adjusting member capable of adjusting the amount of transmitted light can be combined with a temperature adjusting mechanism for adjusting the temperature of the member.

Furthermore, if a heat-responsive substance that is opaque at normal temperature and exhibits transparency at high temperature is obtained, it is expected to be applied not only to the above dimming use but also to various uses.
For example, when a member for fixing an object such as a cast of Patent Document 1 is formed of a material exhibiting optical thermal response as described above, the member for fixing is simply removed without removing the fixing member. It is possible to observe the inside by simply heating.

  However, no material exhibiting such excellent thermal responsiveness in terms of optical properties has been found, and no thermoresponsive material suitable for dimming or fixing members has been found. No.

Table 97/003130 Japanese Patent Laid-Open No. 05-017595

  An object of the present invention is to solve the above-described problems, provide a material exhibiting excellent thermal responsiveness in terms of optical properties, and a sheet or a light control member using such thermal responsiveness. It is an issue to provide.

  The present inventor has intensively studied to solve the above-mentioned problems, and found that polyurethane obtained by reacting a predetermined polyol and isocyanate exhibits excellent heat responsiveness in light transmittance, and completed the present invention. It is what led to it.

  That is, in order to solve the above problems, the present invention relating to a thermoresponsive polyurethane is obtained by reacting a polyester polyol having a melting point of 40 to 70 ° C. and a number average molecular weight of 800 to 10,000 with a polyfunctional isocyanate having three or more functions. The heat which shows reversible heat responsiveness to light transmission, increases light transmission when heated to a temperature higher than the melting point of the polyester polyol, and decreases light transmission when cooled below the melting point. It is characterized by having responsiveness.

  In addition, the present invention relating to a heat-responsive polyurethane sheet is obtained by reacting a polyester polyol having a melting point of 40 to 70 ° C. and a number average molecular weight of 800 to 10,000 with a trifunctional or higher polyfunctional isocyanate, thereby making it light transmissive. It exhibits reversible thermal responsiveness, has increased light transmission when heated to a temperature equal to or higher than the melting point of the polyester polyol, and has reduced heat transmission when cooled below the melting point. It is characterized by comprising a heat-responsive polyurethane.

  Furthermore, the present invention relating to the light control member comprises a polyester polyol having a melting point of 40 to 70 ° C. and a number average molecular weight of 800 to 10,000, and a trifunctional or higher polyfunctional isocyanate, which is reversible in light transmittance. It exhibits excellent thermal responsiveness, and the light responsiveness increases when heated to a temperature equal to or higher than the melting point of the polyester polyol, and the light responsiveness decreases when cooled below the melting point. A heat-responsive polyurethane layer made of a heat-responsive polyurethane and a transparent heat generating layer for adjusting the temperature of the heat-responsive polyurethane layer are laminated, and through the transparent heat-generating layer and the heat-responsive polyurethane layer, The light transmission is performed by the temperature adjustment.

In the present invention, a polyester polyol having a relatively small number average molecular weight and having a melting point within the range of 40 to 70 ° C. is employed as a component for forming a thermoresponsive polyurethane.
The polyester polyol as described above generally exhibits wax-like properties, and becomes a highly transparent liquid at a temperature equal to or higher than the melting point while being opaque and opaque at a temperature lower than the melting point.
The polyester polyol as described above retains transparency at a temperature equal to or higher than the melting point although fluidity at a temperature equal to or higher than the melting point is suppressed by reaction with the polyfunctional isocyanate.
That is, the heat-responsive polyurethane of the present invention exhibits reversible heat responsiveness to light transmission, and the light transmission increases when heated to a temperature equal to or higher than the melting point of the polyester polyol, and is cooled below the melting point. In this case, since the thermal responsiveness that reduces light transmittance is exhibited, the thermal responsiveness can be used effectively for a light control member or the like.
Further, the heat-responsive polyurethane sheet of the present invention can be effectively used as a blindfold sheet because the heat-responsive polyurethane used for the formation thereof exhibits excellent thermal response in terms of optical properties.
Furthermore, since the light responsive polyurethane as described above is used for the light control member of the present invention, the amount of transmitted light and the like can be easily adjusted by adjusting the temperature of the heat responsive polyurethane.

  Hereinafter, a light control member in which a heat-responsive polyurethane layer is formed of a heat-responsive polyurethane sheet will be described as an example of the embodiment of the present invention.

The heat-responsive polyurethane sheet of the present embodiment has a predetermined thickness by a heat-responsive polyurethane in which a polyester polyol having a melting point of 40 to 70 ° C. and a number average molecular weight of 800 to 10,000 is reacted with a trifunctional or higher polyfunctional isocyanate. The light transmittance is reversible and shows a reversible thermal response, and the light transmittance increases when heated to a temperature higher than the melting point of the polyester polyol, and the light transmittance when cooled below the melting point. It shows the thermal responsiveness that decreases.
First, raw materials for forming the thermoresponsive polyurethane sheet will be described.

  The polyester polyol used for forming the heat-responsive polyurethane sheet of the present embodiment is not particularly limited, and examples thereof include terephthalic acid, isophthalic acid, 1,5-naphthalic acid, 2,6-naphthalic acid, and succinic acid. Polyvalent carboxylic acid such as dicarboxylic acid such as acid, glutaric acid, adipic acid, picric acid, suberic acid, azelaic acid, sebacic acid, decamethylene dicarboxylic acid, dodecamethylene dicarboxylic acid, ethylene glycol, propylene glycol, 1,3 -Polyester polyols obtained by reaction with polyols such as propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol; open ε-caprolactam Ring polymerization Polycaprolactone polyols obtained Te and the like.

  Among these, as the polyester polyol used in the heat-responsive polyurethane sheet of the present embodiment, polycaprolactone polyol is preferable, and as the polycaprolactone polyol, for example, among those commercially available as “PLACCEL 200 series” from Daicel Chemical Industries, A bifunctional polycaprolactone diol having a melting point of 40 to 70 ° C. can be employed, and “PLACCEL 210” (manufacturer published molecular weight: 1000), “PLACCEL 220” (manufacturer published molecular weight: 2000), “PLACCEL 230” (manufacturer published molecular weight: 3000), “PLACCEL240” (manufacturer published molecular weight: 4000), and the like.

In this embodiment, a polyester polyol having a melting point of 40 to 70 ° C. is used as a component of the thermoresponsive polyurethane because the melting point of the polyester polyol causes the thermoresponsive polyurethane tape to exhibit thermal responsiveness. This is because it becomes substantially equal to the temperature.
That is, the melting point of this polyester polyol is set to 40 ° C. or more. When the melting point is less than 40 ° C., the temperature range showing the thermal response becomes too close to room temperature and the light responsiveness of the heat-responsive polyurethane sheet is lowered. This is because it may be necessary to separately provide a cooling mechanism.
The polyester polyol has a melting point of 70 ° C. or higher because, if the melting point exceeds 70 ° C., a large amount of heat may be required to improve the light transmittance of the heat-responsive polyurethane sheet. It is.

In the present embodiment, the polyester polyol having a number average molecular weight of 800 to 10,000 is employed as a component of the thermoresponsive polyurethane. Generally, the number average molecular weight of the polyester polyol reacts with the polyester polyol and isocyanate. The strength of the resulting polyurethane and the viscosity in the molten state of the polyester polyol tend to show a positive correlation, so that sufficient strength can be imparted to the thermoresponsive polyurethane sheet and an appropriate melt viscosity can be exhibited. This is because the workability during the production of the heat-responsive polyurethane sheet can be improved.
The melting point of the polyester polyol can be confirmed by the method described in JIS K7122: 1987 “Method of measuring the transition heat of plastic”, and the number average molecular weight of the polyester polyol is 800 to 10,000. It can be confirmed by GPC (gel permeation chromatography).

Examples of the trifunctional or higher polyfunctional isocyanate for constituting the thermoresponsive polyurethane together with the polyester polyol include, for example, a general bifunctional isocyanate as a main starting material, and a trimer of a bifunctional isocyanate ( Biuret, allophanate or isocyanurate), adducts with trifunctional alcohols such as trimethylolpropane, adducts with trifunctional phenols such as phloroglysine, or formalin condensates of benzene isocyanate (polymethylene polyphenylene polyisocyanate), Examples thereof include polymers of isocyanate compounds having a polymerizable group such as methacryloyloxyethyl isocyanate, lysine triisocyanate, and the like.
In addition, as a bifunctional isocyanate used as the starting material of a trifunctional or higher polyfunctional isocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4 ′ -Diphenylmethane diisocyanate, 4,4'-diphenylpropane diisocyanate, 4,4'-diphenylhexafluoropropane diisocyanate, 1,4-naphthalene diisocyanate, 3,3'-dimethoxybiphenyl diisocyanate, 3,3'-dimethyldiphenylmethane-4, Aromatic bifunctional isocyanates such as 4′-diisocyanate; 1,3-trimethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, 1,6-hexamethyl Diisocyanate, cyclohexylene 1,2-diisocyanate, cyclohexylene 1,3-diisocyanate, cyclohexylene 1,4-diisocyanate, isophorone diisocyanate, m-xylylene diisocyanate, hydrogenated m-xylylene diisocyanate, p-xylylene diisocyanate, Examples thereof include aliphatic bifunctional isocyanates such as hydrogenated p-xylylene diisocyanate, hydrogenated 4,4′-diphenylmethane diisocyanate, 4-chloroxylylene-1,3-diisocyanate, 2-methylxylylene diisocyanate, and norbornane diisocyanate. .

In the present embodiment, such a trifunctional or higher polyfunctional isocyanate is used because a thermoresponsive polyurethane obtained after the reaction with the polyester polyol has a three-dimensional structure due to the presence of three or more functional groups. This is because it is easy to impart and it is easier to improve the degree of crosslinking of the thermoresponsive polyurethane.
This is because it is possible to easily impart mechanical strength, chemical resistance, and the like to the heat-responsive polyurethane sheet.
In such a point, among the polyfunctional isocyanates as described above, isocyanurate which is a trimer of diisocyanate in that it is easy to impart excellent mechanical strength and flexibility to the thermoresponsive polyurethane sheet. Modified polyisocyanates are preferred.

The heat-responsive polyurethane sheet according to the present embodiment can be formed by a heat-responsive polyurethane obtained by reacting the polyfunctional isocyanate and the polyester polyol, but the functional group of the polyester polyol and the polyfunctional isocyanate. When the ratio of the isocyanate group and the hydroxyl group (hereinafter also referred to as “NCO / OH value”) becomes excessively high, the free isocyanate group reacts with moisture to generate a volatile component, or the heat responsiveness. There is a risk that polyurethane may become brittle.
On the other hand, if the “NCO / OH value” is an excessively low value, the crosslink density of the heat-responsive polyurethane becomes insufficient, and the heat-responsive polyurethane sheet may not be able to maintain the sheet shape when heated.
For these reasons, the “NCO / OH value” is preferably 0.5 or more and less than 0.95 in that moderate strength and flexibility can be imparted to the heat-responsive polyurethane sheet.

In order to produce a heat-responsive polyurethane sheet by reacting the polyester polyol and the polyfunctional isocyanate, a method similar to that for producing a general polyurethane member can be employed. The polyester polyol and the polyfunctional isocyanate are mixed and stirred in a reaction vessel equipped with a stirring device after adding a polymerization catalyst such as a metal oxide, an organometallic compound, or an amine catalyst, if necessary. A method of pouring the obtained mixed liquid into a predetermined mold and forming it into a sheet can be employed.
More specifically, a predetermined amount of polyester polyol is put into a reaction vessel, and a temperature higher than the melting point of polyester polyol (for example, 40 to 90 ° C., preferably 50 ° C. to 70 ° C.) with a heater that can be controlled to achieve a uniform temperature. The polyester polyol is sufficiently melted and stirred under reduced pressure or while blowing dry nitrogen into the reaction vessel, and then a predetermined amount of polyfunctional isocyanate and a polymerization catalyst are added. The mixture is sufficiently stirred, and this mixed solution is poured into a mold or the like and allowed to react at 50 to 100 ° C., preferably 60 to 90 ° C. in a stationary state, to produce a heat-responsive polyurethane sheet.

The heat-responsive polyurethane sheet is preferably used as a light-adjusting sheet in order to adjust the light transmission using the heat-responsive property, but when used in such applications, the heat-responsive polyurethane sheet The total light transmittance measured at 23 ° C. was 55 to 80%, the haze was 80 to 99.9%, and the sheet was all measured at a temperature equal to or higher than the melting point of the polyester polyol (for example, 60 ° C.). It is preferable to adjust so that the light transmittance is 80 to 99.9% and the haze is 0 to 40%.
Such light transmittance can be adjusted by further adding additives such as an inorganic filler and a colorant to the heat-responsive polyurethane sheet, in addition to the method of adjusting by the thickness of the heat-responsive polyurethane sheet. .

When adjusting the light transmittance of the heat-responsive polyurethane sheet by this thickness, if the thickness is excessively reduced, the strength of the heat-responsive polyurethane sheet may become extremely low. Even if heated to be high, there is a possibility that sufficient transparency may not be exhibited.
From such a viewpoint, the heat-responsive polyurethane sheet preferably has a thickness of 0.1 mm to 5 mm, more preferably 0.2 mm to 4 mm, and a thickness of 0.3 mm to 3 mm. It is particularly preferable to do this.
In addition, when adjusting light transmittance with additives, such as the said inorganic filler, glass fiber, glass bead, metal powder, talc, mica, a silica, etc. can be contained as this inorganic filler.

  Further, in order to adjust various properties, as other additives, various stabilizers, flame retardants, antistatic agents, fungicides, plasticizers, viscosity imparting agents, thermoplastic resins, curable oligomers, and the like of the present invention. As long as the effect is not significantly impaired, it can be appropriately contained in the heat-responsive polyurethane sheet.

The heat-responsive polyurethane constituting the heat-responsive polyurethane sheet is capable of changing its light transmittance in the vicinity of the melting point of the polyester polyol. Changes are often abrupt.
Therefore, when the light control sheet is composed of a single heat-responsive polyurethane sheet, highly accurate temperature control is required in order to control the light transmittance with high accuracy.

For this reason, for example, the overall light transmittance may be adjusted by laminating and integrating a plurality of types of heat-responsive polyurethane sheets having different melting points of the polyester polyol to form a light control sheet.
For example, the transparent heat generating layer having a total light transmittance of 90% to 99.9% is prepared with two transparent heaters formed on the surface of the transparent glass substrate having a higher total light transmittance than the transparent heat generating layer, A dimming sheet is prepared by laminating three heat-responsive polyurethane sheets each having a different melting point of the polyester polyol used, and the dimming sheet having the three heat-responsive polyurethane layers is used as the transparent heating layer. A light control member having a laminated structure of a total of 7 layers of glass substrate / transparent heat generating layer / 3 heat-responsive polyurethane layer / transparent heater layer / glass substrate sandwiched between the two transparent heaters so as to be inside Can be made.

  Then, the temperature of each of the transparent heaters can be individually controlled, for example, so that only one of the three heat-responsive polyurethane layers has a melting point higher than that of the polyester polyol used for forming the heat-responsive polyurethane. On the contrary, the two thermoresponsive polyurethane layers are made higher than the melting point of the polyester polyol and only one layer is left cloudy, or all the three layers are made higher than the melting point of the polyester polyol, or the melting point The light transmittance of the light control member using the light control sheet can be finely adjusted by setting the temperature to less than that.

  In this case, it is also possible to attach a design film with a pattern or design to one side of the central heat-responsive polyurethane sheet and control the visibility of the design film from the outside by temperature control. is there.

Furthermore, the light control sheet | seat which gave the design property can also be formed combining the heat-responsive polyurethane sheet of several sheets from which the temperature which shows heat-responsiveness differs.
For example, one or a plurality of locations that are punched into a heart shape or a star shape are provided in a single heat-responsive polyurethane sheet, and the heat-responsive polyurethane exhibits heat response at a higher temperature than the heat-responsive polyurethane sheet. The sheet is fitted into this punched part to make a light control sheet, and it is transparent throughout the day, but when the temperature drops at night, a white heart shape or star shape floats in the transparent sheet It is also possible to form a light control sheet that is in a state.
Conversely, a heat-responsive polyurethane sheet that exhibits thermal responsiveness at low temperatures is cut into a star shape or a heart shape and fitted into the punched portion to form a light control sheet. When heated, this heart shape portion or star shape portion You may form the light control member which only shows transparency.

  In addition, as a transparent heater used for forming the said light control member with a heat-responsive polyurethane sheet, a commercial item can be employ | adopted, for example, a commercially available thing from U-COrporation company, or a transparent product made by Eiko Electric Co., Ltd. A glass heater (trade name “GES-FIL meal”), a transparent heater manufactured by Honeywell (trade name “78000 series”), and the like can be used.

Such a light control member can adjust light transmittance such as total light transmittance depending on heating conditions, indoor windows, ceiling windows, daylighting windows such as terraces, roofs and side walls of greenhouses, automobile sunroofs, etc. Can be used for
In addition, it cannot be overemphasized that the thermoresponsive polyurethane of this invention can be utilized for various uses, without being limited to the said illustration.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
First, measurement methods and evaluation methods for various characteristics in Examples and Comparative Examples will be described.

(Measurement method of number average molecular weight)
“Number average molecular weight (Mn)” means the number average molecular weight in terms of polystyrene (PS) measured by gel permeation chromatography (GPC).
Specifically, 25 mg of a sample was dissolved in 5 mL of tetrahydrofuran (THF) (permeation time: 6.0 ± 0.5 hr (complete dissolution)), filtered through a non-aqueous 0.45 μm chromatodisc, and then chromatographed. And measured under the following measurement conditions.
And the number average molecular weight of a sample can be calculated | required from the calibration curve of the monodispersed standard polystyrene which was measured beforehand and created.

Equipment used: Shimadzu Corporation, trade name “Shimadzu High Performance Liquid Chromatograph Prominence System”
Basic configuration: LC-20AD, DGU-20A3, CTO-20A, SIL-20A, RID-10A, CBM-20A, LCsolution Ver. 1.25, GPC option soft guard column: manufactured by Shimadzu Corporation, trade name “SHIMAZU Shim-pack GPC-800P” (4.6 mm ID × 10 mm)
Column: One manufactured by Shimadzu Corporation, trade name “SHIMAZU Shim-pack GPC-803” (8 mm ID × 300 mm), one “SHIMAZU Shim-pack GPC-804” (8 mm ID × 300 mm)
Column temperature: 40 ° C
Detector cell temperature: 40 ° C
Mobile phase: Tetrahydrofuran (THF)
Mobile phase flow rate: 1.0 mL / min
Detector: RI
Sample concentration: 0.5 wt%
Injection volume: 50 μL
Measurement time: 30 min

In addition, as a monodisperse standard polystyrene sample for a calibration curve, trade name “shodex” average molecular weights 631000, 365000, 118000, 54000, 17000, 7660, 3250, 1320 manufactured by Showa Denko KK were used.
Specifically, the monodisperse standard polystyrene for the calibration curve is grouped into A (631000, 118000, 17000, 3250) and B (365000, 54000, 7660, 1320), and the total of each of the four types of monodisperse standard polystyrene. A calibration curve was prepared based on the results obtained by dissolving in THF to a concentration of 0.05 wt% and injecting 50 μL of the solution.
That is, a calibration curve (third order equation) was created from these retention times, and the average molecular weight was measured.

(Melting point measurement (DSC measurement))
The melting point was measured in accordance with the method described in JIS K7122: 1987 “Method for measuring the transition heat of plastic”.
That is, using a measuring device (differential scanning calorimeter device DSC 6220 type (manufactured by SII Nano Technology Co., Ltd.)) The melting point was measured at a heating rate of / min.
The melting point was a value obtained from the peak top of the endothermic peak of the obtained DSC curve.

(Total light transmittance measurement)
The total light transmittance was measured by the method described in JIS K7361-1: 1997 "Plastics-Test method for total light transmittance of transparent material-Part 1: Single beam method".
That is, a 50 × 50 mm test piece was measured using a haze meter HM-150 type (manufactured by Murakami Color Research Laboratory Co., Ltd.).

(Haze)
Haze was measured by the method described in JIS K7136.
That is, a 50 × 50 mm test piece was measured using a haze meter HM-150 type (manufactured by Murakami Color Research Laboratory Co., Ltd.).

(Thermal response)
The thermal responsiveness was judged according to the following criteria for the difference in physical properties between normal temperature (23 ° C.) and high temperature (60 ° C.).
○: Hard and does not have rubber elasticity at normal temperature, has rubber elasticity at high temperature, and a state change from white turbidity to transparency is seen, which changes reversibly.
X: Almost no difference in elasticity and transparency at normal temperature and high temperature.

Example 1
The thermoresponsive polyurethane was polymerized by the method described below.
20 g of polycaprocactol polyol (manufactured by Daicel Chemical Industries, trade name “Placcel 240”, number average molecular weight 4000, melting point 60 ° C., hydroxyl value 28 (KOHmg / g)) was placed in a 100 ml flask, and the flask was filled with nitrogen. Replaced and stirred at 60 ° C. until evenly dissolved.
Next, 1.47 g of polyfunctional isocyanate (isocyanurate type polyisocyanate of hexamethylene diisocyanate trimer) (product name “Duranate TPA-100” (isocyanate, NCO% = 23.1) manufactured by Asahi Kasei Chemicals), catalyst As an organic zirconia compound (1.0 g, K-CAT 4205 manufactured by KING Industries) was added and sufficiently mixed and stirred, the mixture was degassed under reduced pressure, and siliconized 100 μm thick polyethylene terephthalate release film A heat-responsive polyurethane sheet was produced by allowing the reaction to stand at 70 ° C. for 6 hours.
In the reaction between the release films, a 1 mm thick silicone spacer was sandwiched between the films to adjust the thickness of the heat-responsive polyurethane sheet to 1 mm.

(Example 2)
A thermally responsive polyurethane sheet was prepared in the same manner as in Example 1 except that the silicone spacer used was changed to a 0.5 mm thick one and a 0.5 mm thick thermally responsive polyurethane sheet was produced.

(Example 3)
A thermoresponsive polyurethane sheet was prepared in the same manner as in Example 1 except that the silicone spacer used was changed to a 0.3 mm thick one and a 0.3 mm thick thermoresponsive polyurethane sheet was produced.

Example 4
A heat-responsive polyurethane sheet was prepared in the same manner as in Example 1 except that the silicone spacer used was changed to a 3 mm-thick and a 3 mm-thick heat-responsive polyurethane sheet was prepared.

(Example 5)
20 g of polycaprocactol polyol was changed to “Placcel 220” (number average molecular weight 2000, melting point 56 ° C., hydroxyl value 56 (KOHmg / g)) manufactured by Daicel Chemical Industries, Ltd., polyfunctional isocyanate (trade name “Duranate TPA”) A thermoresponsive polyurethane sheet having a thickness of 1 mm was prepared in the same manner as in Example 1 except that the amount of -100 ") was changed to 2.92 g.

(Example 6)
20 g of polycaprocactol polyol was changed to “Placcel 210” (number average molecular weight 1000, melting point 48 ° C., hydroxyl value 112 (KOHmg / g)) manufactured by Daicel Chemical Industries, Ltd., polyfunctional isocyanate (trade name “Duranate TPA”) A heat-responsive polyurethane sheet having a thickness of 1 mm was produced in the same manner as in Example 1 except that the amount of -100 ") was changed to 5.81 g.

(Comparative Example 1)
20 g of polycaprocactol polyol was changed to “Placcel 220AL” (number average molecular weight 2000, melting point 0 to 5 ° C.) manufactured by Daicel Chemical Industries, and the amount of polyfunctional isocyanate (trade name “Duranate TPA-100”) A thermoresponsive polyurethane sheet having a thickness of 1 mm was produced in the same manner as in Example 1 except that the amount was changed to 3.65 g.

(Comparative Example 2)
20 g of polycaprocactone polyol was changed to “Placcel 205” (number average molecular weight 530, melting point 35 ° C., hydroxyl value 213 (KOHmg / g)) manufactured by Daicel Chemical Industries, Ltd., polyfunctional isocyanate (trade name “Duranate TPA”) A thermoresponsive polyurethane sheet having a thickness of 1 mm was prepared in the same manner as in Example 1 except that the amount of -100 ") was changed to 11.02 g.
The evaluation results of the above heat-responsive polyurethane sheet are shown in Tables 1 and 2 below.

In Examples 1 to 6, the white turbid state at 23 ° C. and the transparent state at 60 ° C. show the heat responsiveness.
On the other hand, Comparative Example 1 and Comparative Example 2 have almost no change in appearance at 23 ° C. and 60 ° C.

(Evaluation of light control member (light control window))
A dimming window was prepared and evaluated by the following method.

(Preparation of light control window)
The heat-responsive polyurethane sheet of Example 1 and Comparative Example 1 was cut into 50 mm × 50 mm, and a transparent glass heater (Rated: 48V-24W, external dimensions: 140 mm (w) × 110 mm (h ) × 3 mm (t), heat generation surface: 110 mm × 85 mm) to form a light control window.

(Evaluation method)
When each heat-responsive polyurethane sheet was used as a light control sheet and the transparent glass heater was heated to 60 ° C., the appearance change of the light control sheet was visually confirmed.
The results were determined according to the following criteria and are shown in Table 3 below.
○: It is “cloudy” at room temperature and becomes “transparent” when heated.
X: Change by temperature is not seen.

From the above, it can be confirmed that the heat-responsive polyurethane sheet of Example 1 can be used as a light control sheet.
In addition to the results so far, according to the present invention, it is possible to provide a substance exhibiting excellent thermal responsiveness in terms of optical properties, and to provide a sheet or a light control member utilizing thermal responsiveness. Recognize.

Claims (6)

  A polyester polyol having a melting point of 40 to 70 ° C. and a number average molecular weight of 800 to 10,000 is reacted with a trifunctional or higher polyfunctional isocyanate, and exhibits reversible thermal responsiveness to light transmittance. The heat-responsive polyurethane, which has the heat-responsive property of increasing light transmittance when heated to a temperature equal to or higher than a melting point and decreasing light transmittance when cooled to a temperature lower than the melting point.   The heat-responsive polyurethane according to claim 1, wherein the polyester polyol is a polycaprolactone polyol.   A polyester polyol having a melting point of 40 to 70 ° C. and a number average molecular weight of 800 to 10,000 is reacted with a trifunctional or higher polyfunctional isocyanate, and exhibits reversible thermal responsiveness to light transmittance. It is characterized by comprising a heat-responsive polyurethane that has the above-mentioned thermal responsiveness that increases light transmittance when heated to a temperature equal to or higher than the melting point and decreases light transmittance when cooled below the melting point. Thermoresponsive polyurethane sheet.   The heat-responsive polyurethane sheet according to claim 3, which has a thickness of 0.2 mm or more and 4 mm or less.   The heat-responsive polyurethane sheet according to claim 3 or 4, wherein the heat-responsive polyurethane sheet is used as a light control sheet whose light transmittance is adjusted by changing the temperature of the heat-responsive polyurethane.   A polyester polyol having a melting point of 40 to 70 ° C. and a number average molecular weight of 800 to 10,000 is reacted with a trifunctional or higher polyfunctional isocyanate, and exhibits reversible thermal responsiveness to light transmittance. A heat-responsive polyurethane layer comprising the heat-responsive polyurethane having the heat-responsive property that increases light transmittance when heated to a temperature equal to or higher than the melting point and decreases light transmittance when cooled below the melting point. And a transparent heat generating layer for adjusting the temperature of the heat-responsive polyurethane layer, and light transmission through the transparent heat-generating layer and the heat-responsive polyurethane layer is performed by the temperature adjustment. The light control member characterized by the above-mentioned.