Window material and translucent roof material

Abstract

Provided are: a window material or a translucent roof material that is capable of autonomously changing the degree of cloudiness thereof according to the temperature, that does not have a complex structure, and is easy to produce; and a building, vehicle, ship, or aircraft provided with said window material and / or translucent roof material.　This window material or translucent roof material is provided with at least one translucent base material layer and at least one tacky layer, wherein: the tacky layer comprises a tacky composition containing 1-100 parts by mass of temperature-sensitive microparticles with respect to 100 parts by mass of a pressure-sensitive adhesive; the refractive index of the temperature-sensitive microparticles decreases with increases in temperature; and the refractive index rate decrease, which is the amount of decrease in refractive index per 1℃, for the temperature-sensitive microparticles is greater near the melting point of the temperature-sensitive microparticles than in temperature ranges that are not near the melting point of the temperature-sensitive microparticles.

Description

Window materials and translucent roofing materials

[0001] The present invention relates to a window material and a light-transmitting roof material, and also to a building, vehicle, ship, or aircraft equipped with the window material and / or the light-transmitting roof material.

[0002] There is a need to reduce direct sunlight during the hot summer months and let in sunlight during the cold winter months in buildings such as office buildings and arcades, as well as in vehicles such as cars, ships, and airplanes. In response to this need, a temperature-sensitive light-control liquid laminate that autonomously changes its opacity in response to temperature stimuli has been proposed as a structure to be installed in windows (Patent Document 1).

[0003] Patent No. 3337810

[0004] However, providing the laminate requires a special structure for maintaining the shape of the temperature-sensitive light-controlling liquid, and the window provided with the laminate has a complex structure, which makes manufacturing it time-consuming.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a window material and a light-transmitting roof material that can autonomously change its opacity in response to temperature, that has a simple structure and is easy to manufacture, and a building, vehicle, ship, or aircraft that is equipped with the window material and / or the light-transmitting roof material.

[0006] A first aspect of the present invention is a window material comprising at least one light-transmitting base layer and at least one adhesive layer, wherein the adhesive layer is made of an adhesive composition containing 1 to 100 parts by mass of thermosensitive microparticles per 100 parts by mass of adhesive, wherein the refractive index of the thermosensitive microparticles decreases with increasing temperature, and the rate of decrease in refractive index of the thermosensitive microparticles, which is the amount of decrease in refractive index per degree Celsius, is greater near the melting point of the thermosensitive microparticles than in any other temperature range other than near the melting point of the thermosensitive microparticles.

[0007] A second aspect of the present invention is a translucent roofing material comprising at least one light-transmitting base layer and at least one adhesive layer, wherein the adhesive layer is made of an adhesive composition containing 1 to 100 parts by mass of thermosensitive microparticles per 100 parts by mass of adhesive, wherein the refractive index of the thermosensitive microparticles decreases with increasing temperature, and the rate of decrease in refractive index of the thermosensitive microparticles, which is the amount of decrease in refractive index per degree Celsius, is greater near the melting point of the thermosensitive microparticles than in any other temperature range other than near the melting point of the thermosensitive microparticles.

[0008] A third aspect of the present invention is a building comprising the window material according to the first aspect and / or the light-transmitting roof material according to the second aspect.

[0009] A fourth aspect of the present invention is a vehicle, ship, or aircraft equipped with the window material according to the first aspect and / or the light-transmitting roof material according to the second aspect.

[0010] A fifth aspect of the present invention is an adhesive composition comprising 1 to 100 parts by mass of thermosensitive microparticles per 100 parts by mass of adhesive, wherein the refractive index of the thermosensitive microparticles decreases with increasing temperature, and the rate of decrease in refractive index of the thermosensitive microparticles, which is the amount of decrease in refractive index per degree Celsius, is greater near the melting point of the thermosensitive microparticles than in any other temperature range other than near the melting point of the thermosensitive microparticles.

[0011] A sixth aspect of the present invention is a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition according to the fifth aspect.

[0012] According to the present invention, it is possible to provide a window material and a translucent roof material that can autonomously change its opacity in response to temperature, that has a simple structure and is easy to manufacture, and a building, vehicle, ship, or aircraft that is equipped with the window material and / or the translucent roof material.

[0013] 1 is a cross-sectional view showing a first window material which is an example of a window material; FIG. 2 is a cross-sectional view showing a second window material which is an example of a window material; FIG. 3 is a cross-sectional view showing an example of a light-transmitting roofing material; FIG. 4 is a graph showing the measurement results of the refractive index of the temperature-sensitive fine particles produced in the examples; FIG. 5 is a schematic explanatory diagram showing a test method for evaluating heat-shielding properties in the examples; FIG. 6 is a photograph showing a test method for evaluating heat-shielding properties in the examples;

[0014] Specific embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the object of the present invention. Note that the drawings shown below are schematic diagrams, and the size and shape of each part are exaggerated or omitted as appropriate to facilitate understanding.

[0015] <<Window Material>> Fig. 1 shows a cross-sectional view of a first window material 10 as an example of a window material. As shown in Fig. 1, the first window material 10 includes a light-transmitting substrate layer 11, an adhesive layer 12, and a substrate sheet 13 laminated in this order. The adhesive layer 12 is composed of an adhesive composition including an adhesive 12a and temperature-sensitive fine particles 12b.

[0016] Figure 2 shows a cross-sectional view of a second window material 20 as another example of a window material. As shown in Figure 2, the second window material 20 has an adhesive layer 22 disposed between two light-transmitting base layers 21a and 21b. The adhesive layer 22 is composed of an adhesive composition containing an adhesive 22a and temperature-sensitive fine particles 22b.

[0017] In Figures 1 and 2, the refractive index of the temperature-sensitive microparticles 12b and 22b decreases with increasing temperature, and the refractive index decrease rate, which is the amount of refractive index decrease per degree Celsius, is greater near the melting point than in other temperature ranges. Therefore, when the temperature of the adhesive layers 12 and 22 increases due to sunlight or air temperature, the difference in refractive index between the temperature-sensitive microparticles 12b and 22b and the adhesive 12a and 22a increases, resulting in a higher haze value. On the other hand, when the temperature of the adhesive layers 12 and 22 decreases, the difference in refractive index between the temperature-sensitive microparticles 12b and 22b and the adhesive 12a and 22a decreases, resulting in a lower haze value. This allows the opacity to autonomously change according to temperature, reducing direct sunlight during high summer temperatures and incorporating sunlight during low winter temperatures. It is also possible to design the temperature-sensitive microparticles 12b and 22b so that the difference in refractive index between the adhesive and the adhesive decreases with increasing temperature. In this case, for example, under conditions of relatively low temperatures and little sunlight, such as in the morning or at night, the window material functions as frosted glass, but when the temperature rises with increased sunlight during the day, the window material becomes transparent, allowing light to enter the room efficiently. Furthermore, when the above-mentioned window material is installed in a position where it is exposed to the outside air, it becomes cloudy or transparent as the outside temperature rises, so it also has the function of visually notifying people spending time in an air-conditioned room of the rise in outside temperature.

[0018] Each layer constituting the first window material 10 and the second window material 20 will be described below.

[0019] [Translucent Substrate Layer] The translucent substrate constituting the translucent substrate layer is not particularly limited as long as it is a substrate that can be used as a window material for buildings, vehicles, ships, and aircraft, and for example, a glass plate or a resin plate can be used. Examples of materials for the glass plate include soda lime glass, borosilicate glass, and high silica glass. Examples of materials for the resin plate include polyalkyl methacrylates such as polymethyl methacrylate, polyalkyl acrylates, polycarbonates, polymethylstyrene, and acrylonitrile-styrene copolymers.

[0020] The thickness of the light-transmitting base layer is not particularly limited, but is, for example, 0.1 mm to 10 mm. The shape of the light-transmitting base layer may be flat, like the first window material 10 and the second window material 20, or curved.

[0021] The light-transmitting substrate layer is composed of at least one layer, and may be composed of a single layer like the first window material 10, or may be composed of two or more layers like the second window material 20. When composed of two or more layers, each layer may be composed of the same type of substrate or different types of substrate. Furthermore, each layer may have the same thickness or different thicknesses.

[0022] [Adhesive Layer] The adhesive layer is a layer made of an adhesive composition containing 1 to 100 parts by mass of thermosensitive fine particles per 100 parts by mass of adhesive, and has the function of autonomously changing its opacity depending on the temperature.

[0023] The thickness of the adhesive layer is not particularly limited, but is preferably 5 μm or more and 1 mm or less, more preferably 10 μm or more and 100 μm or less. Note that the thicker the adhesive layer, the more likely it is that a small amount of thermosensitive fine particles will be added to exhibit the photochromic function. The thinner the thickness, the more likely it is that a large amount of thermosensitive fine particles will be added to exhibit the photochromic function.

[0024] The adhesive layer is composed of at least one layer. The adhesive layer may be composed of a single layer, as in the first window material 10 and the second window material 20, or may be composed of two or more layers. The arrangement of the adhesive layer relative to the light-transmitting base layer is not particularly limited. The adhesive layer may be arranged on the side of the light-transmitting base layer where sunlight is incident, or on the opposite side. When the light-transmitting base layer is composed of two or more layers, the adhesive layer may be arranged between the light-transmitting base layers, as in the second window material 20. The adhesive layer may cover the entire surface where the adhesive layer and the light-transmitting base layer contact, or may cover only a portion of the surface. When the adhesive layer covers only a portion of the surface where the adhesive layer and the light-transmitting base layer contact, the adhesive layer may form letters, symbols, patterns, figures, pictures, etc. on the light-transmitting base layer. In this case, the adhesive layer may form the letters or patterns, or the area surrounded by the adhesive layer may form the letters or patterns. Such a window material has excellent design properties when haze appears or disappears at high temperatures. Furthermore, the adhesive layer may have multiple types of regions with different haze values ​​at high and low temperatures. The haze value of the adhesive layer can be changed by changing the type of adhesive or the temperature-sensitive fine particles, or by changing the amount of the temperature-sensitive fine particles used. For example, by continuously forming multiple adhesive layers with different haze values ​​at high and low temperatures in a strip shape on a translucent substrate, a window material with excellent design properties can be provided, which exhibits a gradation of haze at high and low temperatures.

[0025] The haze value of the adhesive layer at 40°C is preferably 10% or more higher than the haze value at 23°C. This tends to make it easier to visually recognize changes in opacity depending on temperature. In this specification, the haze value of the adhesive layer is a value measured by the method described in the examples below.

[0026] The haze value of the adhesive layer at 23°C is preferably 10% or less, more preferably 5% or less. The lower limit of the haze value at 23°C is not particularly limited. The haze value of the adhesive layer at 40°C is preferably 12% or more, more preferably 20% or more, and even more preferably 30% or more. The upper limit of the haze value at 40°C is not particularly limited, but is, for example, 70% or less, 50% or less.

[0027] The solar transmittance of the adhesive layer at 40° C. is preferably at least 10% lower than the solar transmittance at 23° C. In this specification, the solar transmittance of the adhesive layer is a value measured by the method described in the examples below.

[0028] The solar radiation transmittance of the adhesive layer at 23°C is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. The upper limit of the solar radiation transmittance at 23°C is not particularly limited, but is, for example, 95% or less, 85% or less. The solar radiation transmittance of the adhesive layer at 40°C is preferably 70% or less, more preferably 60% or less, and even more preferably 50% or less. The lower limit of the solar radiation transmittance at 40°C is not particularly limited.

[0029] (Thermosensitive Particles) Figure 4 is a graph showing the change in refractive index with temperature for the thermosensitive particles (melting point 33°C) produced in the Examples described below. As shown in Figure 4, the refractive index of the thermosensitive particles decreases with increasing temperature, and the rate of decrease in refractive index per 1°C is greater near the melting point than in any other temperature range.

[0030] The refractive index of the thermosensitive fine particles at (melting point + 7) ° C. is preferably at least 0.02 lower than the refractive index of the thermosensitive fine particles at (melting point - 10) ° C. This tends to make it easier to visually recognize changes in opacity depending on temperature. Note that in this specification, the refractive index is a value measured by the method described in the Examples below.

[0031] The melting point of the thermosensitive fine particles is preferably 20° C. or higher, more preferably 25° C. or higher. The melting point is preferably 100° C. or lower, more preferably 60° C. or lower, and even more preferably 40° C. or lower. In this specification, the melting point of the thermosensitive fine particles is a value measured by the method described in the Examples below.

[0032] The melting point of the thermosensitive microparticles can be adjusted, for example, by changing the composition of the monomer components constituting the side-chain crystalline polymer contained in the thermosensitive microparticles. Specifically, the melting point can be adjusted by changing the length of the side chain in the side-chain crystalline polymer. The longer the side chain, the higher the melting point of the thermosensitive microparticles tends to be.

[0033] The average particle diameter of the thermosensitive microparticles is preferably 1 μm or more, more preferably 3 μm or more. Furthermore, the average particle diameter is preferably 100 μm or less, more preferably 30 μm or less. In particular, from the viewpoint of easily increasing haze, the average particle diameter is more preferably 3 μm or more and 10 μm or less, and most preferably 3 μm or more and 6 μm or less. In terms of easily suppressing the transmission of solar radiation, the average particle diameter is more preferably 6 μm or more and 14 μm or less, and most preferably 6 μm or more and 10 μm or less. In terms of easily blocking heat, the average particle diameter is more preferably 6 μm or more and 25 μm or less, and most preferably 14 μm or more and 25 μm or less. Furthermore, the D90 particle diameter of the thermosensitive microparticles is preferably equal to or less than the thickness of the adhesive layer, for example, 1 μm or more and 1000 μm or less, or 3 μm or more and 100 μm or less. When the D90 particle diameter is equal to or less than the thickness of the adhesive layer, the surface of the adhesive layer becomes uniform, and the adhesive strength tends to be less likely to be impaired. In this specification, the average particle size and D90 particle size of the thermosensitive fine particles are values ​​measured by the method described in the Examples below.

[0034] The thermosensitive microparticles preferably contain a side-chain crystalline polymer. The side-chain crystalline polymer preferably contains a structural unit derived from a (meth)acrylic monomer having a linear alkyl group with 14 or more carbon atoms. In the structural unit derived from a (meth)acrylic monomer having a linear alkyl group with 14 or more carbon atoms, the linear alkyl group with 14 or more carbon atoms functions as a side-chain crystalline moiety in the side-chain crystalline polymer. In other words, the side-chain crystalline polymer is, for example, a comb-shaped polymer having a linear alkyl group with 14 or more carbon atoms in its side chain. The side chains are aligned into an orderly arrangement by intermolecular forces, etc., causing the side-chain crystalline polymer to crystallize. Note that the (meth)acrylic monomer referred to above refers to an acrylic monomer or a methacrylic monomer. The upper limit of the number of carbon atoms in the linear alkyl group is preferably 50 or less, more preferably 30 or less.

[0035] Examples of (meth)acrylic monomers having a linear alkyl group having 14 or more carbon atoms include cetyl (meth)acrylate, stearyl (meth)acrylate, eicosyl (meth)acrylate, behenyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0036] The ratio of the mass of the structural unit derived from a (meth)acrylic monomer having a linear alkyl group having 14 or more carbon atoms to the mass of the side-chain crystalline polymer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. This ratio may be 100% by mass, but is preferably 95% by mass or less.

[0037] The side-chain crystalline polymer may contain a structural unit derived from another monomer copolymerizable with a (meth)acrylic monomer having a linear alkyl group having 14 or more carbon atoms. Examples of the other monomer include a monofunctional monomer, a polyfunctional monomer, and a refractive index adjusting monomer. That is, the side-chain crystalline polymer may contain a structural unit derived from a monofunctional monomer, a polyfunctional monomer, or a refractive index adjusting monomer.

[0038] Examples of monofunctional monomers include (meth)acrylic monomers having an alkyl group having 1 to 12 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, lauryl (meth)acrylate, and 2-ethylhexyl acrylate. These may be used alone or in combination of two or more. When it is desired to add a function in addition to temperature sensitivity, any monomer that can be copolymerized with a (meth)acrylic monomer having a linear alkyl group having 14 or more carbon atoms and has that function can be freely copolymerized.

[0039] The ratio of the mass of the structural unit derived from the monofunctional monomer to the mass of the side-chain crystalline polymer is preferably 0.1% by mass or more, more preferably 1% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less.

[0040] The polyfunctional monomer can crosslink multiple molecular chains contained in the side-chain crystalline polymer. From the viewpoints of the dispersion state of the thermosensitive microparticles during use, suppression of deformation, and maintaining repeatable function, the side-chain crystalline polymer preferably contains a structural unit derived from the polyfunctional monomer. That is, the thermosensitive microparticles and the side-chain crystalline polymer are preferably crosslinked. The polyfunctional monomer has two or more, preferably two to four, radically polymerizable double bonds in the molecule. Examples of polyfunctional monomers include bifunctional (meth)acrylates, trifunctional (meth)acrylates, and tetrafunctional (meth)acrylates. Specific examples include 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, polyethylene glycol 200 di(meth)acrylate, and ethoxylated bisphenol A di(meth)acrylate. These may be used alone or in combination of two or more. The polyfunctional monomer may be at least one selected from a difunctional (meth)acrylate, a trifunctional (meth)acrylate, and a tetrafunctional (meth)acrylate.

[0041] The ratio of the mass of the structural unit derived from the polyfunctional monomer to the mass of the side-chain crystalline polymer is preferably 0.1% by mass or more, more preferably 1% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less.

[0042] The refractive index adjusting monomer may be a monomer having a refractive index of 1.300 to 1.600. Examples of refractive index adjusting monomers include 2-(O-phenylphenoxy)ethyl acrylate (refractive index: 1.577), 2-propenoic acid (3-phenoxyphenyl) methyl ester (refractive index: 1.566), 1-naphthyl acrylate (refractive index: 1.595), acrylamide (refractive index: 1.515), hydroxyacrylamide (refractive index: 1.515), EO-modified bisphenol A diacrylate (refractive index: 1.537), acrylamide (refractive index: 1.515), 2,2,2-trifluoroethyl acrylate (refractive index: 1.348), and methacryl-modified polydimethylsiloxane (refractive index: 1.408). These may be used alone or in combination of two or more.

[0043] The ratio of the mass of the structural unit derived from the refractive index adjusting monomer to the mass of the side-chain crystalline polymer is preferably 0.1% by mass or more, more preferably 1% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0044] Since the thermosensitive microparticles tend to have good dispersibility in adhesives, it is preferable that they do not contain structural units derived from a reactive emulsifier. A reactive emulsifier is an emulsifier having a polymerizable unsaturated bond such as a vinyl group in its molecule. The reactive emulsifier has emulsifying properties and is a polymerizable monomer having a polymerizable group having an unsaturated bond such as a vinyl group in its molecule and a hydrophilic group.

[0045] In the adhesive composition, the content of the thermosensitive microparticles is 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the adhesive. The content is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 40 parts by mass or more. The content is also preferably 70 parts by mass or less.

[0046] The method for producing the thermosensitive fine particles is not particularly limited, and they can be obtained by a conventionally known polymerization method such as mini-emulsion polymerization or suspension polymerization.

[0047] (Adhesive) The adhesive is not particularly limited, and conventionally known adhesives such as acrylic adhesives, natural rubber adhesives, synthetic rubber adhesives, silicone adhesives, and urethane adhesives can be used, with acrylic adhesives being preferred.

[0048] The polymer constituting the pressure-sensitive adhesive preferably contains a structural unit derived from an adhesive monomer that contributes to adhesiveness or a structural unit derived from a functional group monomer for crosslinking. The polymer constituting the pressure-sensitive adhesive may also contain a structural unit derived from another monomer that is copolymerizable with these monomers. Examples of other monomers include refractive index-adjusting monomers. That is, the polymer constituting the pressure-sensitive adhesive may contain a structural unit derived from a refractive index-adjusting monomer.

[0049] Examples of adhesive monomers include (meth)acrylates having an alkyl group having 1 to 12 carbon atoms, such as ethylhexyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate; (meth)acrylates having an ethylene glycol group, such as 2-ethylhexyl-diglycol (meth)acrylate, methoxyethyl (meth)acrylate, methoxypolyethylene glycol mono(meth)acrylate, and ethoxy-diethylene glycol (meth)acrylate; and ethylenically unsaturated monomers, such as styrene and vinyl acetate. These may be used alone or in combination of two or more. Of these, (meth)acrylates having an alkyl group having 1 to 12 carbon atoms are preferred.

[0050] The ratio of the mass of the structural unit derived from the adhesive monomer to the mass of the polymer constituting the PSA is preferably 50% by mass or more, more preferably 70% by mass or more, and is preferably 99.9% by mass or less, more preferably 90% by mass or less.

[0051] Examples of functional group monomers include (meth)acrylates having a hydroxyalkyl group, such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxyhexyl (meth)acrylate; and ethylenically unsaturated monomers having a carboxyl group, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid. Only one type may be used, or two or more types may be used in combination. Among these, ethylenically unsaturated monomers having a carboxyl group are preferred.

[0052] The ratio of the mass of the structural unit derived from the functional group monomer to the mass of the polymer constituting the adhesive is preferably 0.1 mass% or more, more preferably 1 mass% or more.Furthermore, the ratio is preferably 30 mass% or less, more preferably 20 mass% or less, and even more preferably 10 mass% or less.When it is 0.1 mass% or more, the shape retention tends to be good.When it is 30 mass% or less, the viscosity is not excessively high, and the coating property tends to be good.

[0053] The refractive index adjusting monomer may be a monomer having a refractive index of 1.300 to 1.600. Examples of refractive index adjusting monomers include 2-(O-phenylphenoxy)ethyl acrylate (refractive index: 1.577), 2-propenoic acid (3-phenoxyphenyl) methyl ester (refractive index: 1.566), 1-naphthyl acrylate (refractive index: 1.595), acrylamide (refractive index: 1.515), hydroxyacrylamide (refractive index: 1.515), EO-modified bisphenol A diacrylate (refractive index: 1.537), acrylamide (refractive index: 1.515), 2,2,2-trifluoroethyl acrylate (refractive index: 1.348), and methacryl-modified polydimethylsiloxane (refractive index: 1.408). These may be used alone or in combination of two or more.

[0054] The ratio of the mass of the structural unit derived from the refractive index adjusting monomer to the mass of the polymer constituting the pressure-sensitive adhesive is preferably 0.1 mass% or more, more preferably 1 mass% or more, and even more preferably 10 mass% or more, and is preferably 30 mass% or less.

[0055] The weight average molecular weight of the pressure-sensitive adhesive is preferably 200,000 or more, more preferably 300,000 or more. The weight average molecular weight is preferably 2,000,000 or less, more preferably 1,000,000 or less, and even more preferably 600,000 or less. When it is 200,000 or more, shape retention tends to be good. When it is 2,000,000 or less, the viscosity is not excessively high and coating properties tend to be good. In this specification, the weight average molecular weight of the pressure-sensitive adhesive is a value measured by the method described in the examples below.

[0056] The glass transition temperature (Tg) of the pressure-sensitive adhesive is preferably 25° C. or lower, as this tends to facilitate the exertion of high adhesive strength. In this specification, the glass transition temperature is a value measured by the method described in the examples below.

[0057] The refractive index difference between the adhesive and the thermosensitive microparticles at 23°C is preferably less than 0.015, more preferably less than 0.010. The refractive index difference at 40°C is preferably 0.015 or greater. The upper limit of the refractive index difference at 40°C is not particularly limited, but is, for example, 0.1. In this case, the adhesive layer exhibits high translucency in warm atmospheres where humans and pets can generally live comfortably, while the translucency of the adhesive layer decreases due to the appearance of haze in the adhesive layer in high-temperature atmospheres such as summer. Furthermore, by adjusting the refractive indexes of the adhesive and the thermosensitive microparticles, it is possible to design the adhesive and the thermosensitive crosslinked microparticles so that the refractive index difference between the adhesive and the thermosensitive crosslinked microparticles at 23°C is 0.015 or greater and the refractive index difference at 40°C is less than 0.015. In this case, for example, when the adhesive is applied to window glass, the window glass functions as frosted glass under conditions of relatively low temperatures and low sunlight, such as in the morning or evening, while the window glass becomes transparent when the temperature rises with increased sunlight during the day, allowing efficient lighting into the room. This allows light to easily enter the room only during the day without opening or closing the curtains.

[0058] The ratio of the mass of the pressure-sensitive adhesive to the mass of the solid content of the pressure-sensitive adhesive composition is not particularly limited, but is, for example, 50 mass % or more and 95 mass % or less. In this specification, the solid content of the pressure-sensitive adhesive composition means all components of the pressure-sensitive adhesive composition excluding solvents such as aqueous solvents and organic solvents.

[0059] The method for producing the pressure-sensitive adhesive is not particularly limited, and the pressure-sensitive adhesive can be obtained by a conventionally known polymerization method such as solution polymerization or UV polymerization.

[0060] The pressure-sensitive adhesive composition may contain a crosslinking agent for crosslinking the pressure-sensitive adhesive. That is, the pressure-sensitive adhesive may be crosslinked. Examples of the crosslinking agent include an aziridine-based crosslinking agent, a metal chelate-based crosslinking agent, an epoxy-based crosslinking agent, and an isocyanate-based crosslinking agent.

[0061] The content of the crosslinking agent in the pressure-sensitive adhesive composition is not particularly limited, but is, for example, 0.1 to 10 parts by mass per 100 parts by mass of the pressure-sensitive adhesive. If the content is 0.1 parts by mass or more, shape retention tends to be less likely to be reduced. If the content is 10 parts by mass or less, high adhesive strength tends to be easily exhibited.

[0062] The pressure-sensitive adhesive composition may contain other additives such as a solvent such as an organic solvent, an inhibitor that suppresses the progress of crosslinking, a tackifier, an ultraviolet (UV) absorber, a light stabilizer (HALS), an antioxidant, an infrared absorber, a dye, or a pigment.

[0063] [Substrate Sheet] The window material may or may not include a substrate sheet. The substrate sheet functions as a support when the pressure-sensitive adhesive layer is laminated on the light-transmitting substrate layer, and as a protective layer for the pressure-sensitive adhesive layer.

[0064] The substrate constituting the substrate sheet is not particularly limited as long as it is a light-transmitting substrate, and examples of the substrate that can be used include PET such as corona-treated PET, untreated PET, highly transparent PET, annealed PET, UV-cut PET, heat-shielding PET, anti-fogging PET, hard-coated PET, and blast-treated PET; transparent PI; and the like.

[0065] [Method for Manufacturing Window Material] The method for manufacturing the window material is not particularly limited, and examples include a method in which an adhesive composition is applied to a substrate sheet to form an adhesive sheet, and then the adhesive sheet is laminated to a light-transmitting substrate. An adhesive layer may be formed by directly applying the adhesive composition to the light-transmitting substrate. In this case, it is preferable to cover the exposed surface of the adhesive layer formed on the light-transmitting substrate with a substrate sheet so that the tacky surface of the adhesive layer is not exposed indoors or outdoors. Furthermore, when the light-transmitting substrate layer is composed of two or more layers, as in the second window material 20, a method in which an adhesive layer is disposed between the light-transmitting substrate layers may also be used. In this case, an adhesive composition is applied to one substrate layer to form an adhesive layer, and then another substrate layer is laminated to the exposed surface of the adhesive layer. Alternatively, the second window material 20 having an adhesive layer between light-transmitting substrates can be manufactured by preparing two laminates each including one light-transmitting substrate layer and one adhesive layer so that they are in contact with each other, and then laminating the two laminates together with the exposed surfaces of the adhesive layers.

[0066] [Uses] There are no limitations on the manner in which the above-mentioned window material is used. The manner in which the above-mentioned window material is used can be appropriately selected depending on the purpose. The above-mentioned window material can be suitably used in, for example, buildings such as houses, buildings, warehouses, and arcades, as well as vehicles, ships, and aircraft.

[0067] <<Translucent Roofing Material>> Figure 3 is a cross-sectional view showing an example of a translucent roofing material. As shown in Figure 3, the translucent roofing material 30 comprises a translucent base layer 31, an adhesive layer 32, and a base sheet 33 laminated in this order. The adhesive layer 32 contains an adhesive 32a and temperature-sensitive fine particles 32b.

[0068] In Figure 3, the refractive index of the temperature-sensitive microparticles 32b decreases with increasing temperature, and the refractive index decrease rate, which is the amount of refractive index decrease per degree Celsius, is greater near the melting point than in other temperature ranges. Therefore, when the temperature of the adhesive layer 32 increases due to sunlight or air temperature, the difference in refractive index between the temperature-sensitive microparticles 32b and the adhesive 32a increases, resulting in a higher haze value. On the other hand, when the temperature of the adhesive layer 32 decreases, the difference in refractive index between the temperature-sensitive microparticles 32b and the adhesive 32a decreases, resulting in a lower haze value. This allows the opacity to autonomously change according to temperature, reducing the impact of direct sunlight during high summer temperatures and incorporating sunlight during low winter temperatures. It is also possible to design the refractive index difference between the temperature-sensitive microparticles 32b and the adhesive 32a to decrease as the temperature increases.

[0069] The layers, manufacturing method, and uses of the light-transmitting roofing material, including the light-transmitting base layer, adhesive layer, and base sheet, are the same as those of the window material.

[0070] <<Adhesive Composition>> The adhesive composition contains 1 to 100 parts by mass of thermosensitive fine particles per 100 parts by mass of adhesive.

[0071] The refractive index of the thermosensitive microparticles decreases with increasing temperature, and the rate of decrease in refractive index per degree Celsius is greater near the melting point than in other temperature ranges. Therefore, when an adhesive layer is formed from an adhesive composition, as the temperature of the adhesive layer increases due to sunlight or air temperature, the difference in refractive index between the thermosensitive microparticles and the adhesive increases, resulting in a higher haze value. On the other hand, as the temperature of the adhesive layer decreases, the difference in refractive index between the thermosensitive microparticles and the adhesive decreases, resulting in a lower haze value. Conversely, if the refractive indexes of the thermosensitive microparticles and the adhesive are adjusted to reduce the difference in refractive index between them at high temperatures, the haze value decreases as the temperature of the adhesive layer increases, and increases as the temperature of the adhesive layer decreases. As a result, in the former case, the opacity can be autonomously adjusted according to temperature, reducing direct sunlight during high summer temperatures and incorporating sunlight during low winter temperatures. Furthermore, when an adhesive layer is formed using the adhesive composition so that a design such as letters, symbols, patterns, figures, or pictures is drawn on it, the design can be made to appear or disappear when haze appears or disappears due to a heat source such as lighting, sunlight, or high temperature, which makes it possible to impart excellent display properties (designs such as letters and symbols) and decorative properties (designs such as patterns, figures, or pictures) to an object provided with the adhesive layer.

[0072] (Thermosensitive Fine Particles) The refractive index of the thermosensitive fine particles decreases with increasing temperature, and the refractive index decrease rate, which is the amount of decrease in refractive index per 1° C., is greater near the melting point than in temperature ranges other than near the melting point.

[0073] The refractive index of the thermosensitive fine particles at (melting point + 7) ° C. is preferably at least 0.02 lower than the refractive index of the thermosensitive fine particles at (melting point - 10) ° C. This tends to make it easier to visually recognize changes in opacity depending on the temperature.

[0074] The melting point of the thermosensitive fine particles is preferably 20° C. or higher, more preferably 25° C. or higher, and preferably 100° C. or lower, more preferably 60° C. or lower, and even more preferably 40° C. or lower.

[0075] The melting point of the thermosensitive microparticles can be adjusted, for example, by changing the composition of the monomer components constituting the side-chain crystalline polymer contained in the thermosensitive microparticles. Specifically, the melting point can be adjusted by changing the length of the side chain in the side-chain crystalline polymer. The longer the side chain, the higher the melting point of the thermosensitive microparticles tends to be.

[0076] The average particle diameter of the thermosensitive microparticles is preferably 1 μm or more, more preferably 3 μm or more. Furthermore, the average particle diameter is preferably 100 μm or less, more preferably 30 μm or less. In particular, from the viewpoint of easily increasing haze, the average particle diameter is more preferably 3 μm or more and 10 μm or less, and most preferably 3 μm or more and 6 μm or less. In terms of easily suppressing the transmission of solar radiation, the average particle diameter is more preferably 6 μm or more and 14 μm or less, and most preferably 6 μm or more and 10 μm or less. In terms of easily blocking heat, the average particle diameter is more preferably 6 μm or more and 25 μm or less, and most preferably 14 μm or more and 25 μm or less. Furthermore, the D90 particle diameter of the thermosensitive microparticles is preferably equal to or less than the thickness of the adhesive layer, for example, 1 μm or more and 1000 μm or less, or 3 μm or more and 100 μm or less. When the D90 particle diameter is equal to or less than the thickness of the adhesive layer, the surface of the adhesive layer becomes uniform, and the adhesive strength tends to be less likely to be impaired.

[0077] The thermosensitive microparticles preferably contain a side-chain crystalline polymer, and the side-chain crystalline polymer preferably contains a structural unit derived from a (meth)acrylic monomer having a linear alkyl group with 14 or more carbon atoms. In the structural unit derived from a (meth)acrylic monomer having a linear alkyl group with 14 or more carbon atoms, the linear alkyl group with 14 or more carbon atoms functions as a side-chain crystalline moiety in the side-chain crystalline polymer. That is, the side-chain crystalline polymer is, for example, a comb-shaped polymer having a linear alkyl group with 14 or more carbon atoms in its side chain. The side chains are aligned into an ordered arrangement by intermolecular forces, etc., causing the side-chain crystalline polymer to crystallize. The (meth)acrylic monomer referred to above refers to an acrylic monomer or a methacrylic monomer. The upper limit of the number of carbon atoms in the linear alkyl group is preferably 50 or less, more preferably 30 or less.

[0078] Examples of (meth)acrylic monomers having a linear alkyl group having 14 or more carbon atoms include cetyl (meth)acrylate, stearyl (meth)acrylate, eicosyl (meth)acrylate, behenyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0079] In the side-chain crystalline polymer, the content of structural units derived from (meth)acrylic monomers having a linear alkyl group with 14 or more carbon atoms is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The content of the structural units may be 100% by mass, but is preferably 95% by mass or less.

[0080] The side-chain crystalline polymer may contain a structural unit derived from another monomer copolymerizable with a (meth)acrylic monomer having a linear alkyl group having 14 or more carbon atoms. Examples of the other monomer include a monofunctional monomer, a polyfunctional monomer, and a refractive index adjusting monomer. That is, the side-chain crystalline polymer may contain a structural unit derived from a monofunctional monomer, a polyfunctional monomer, or a refractive index adjusting monomer.

[0081] Examples of monofunctional monomers include (meth)acrylic monomers having an alkyl group having 1 to 12 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, lauryl (meth)acrylate, and 2-ethylhexyl acrylate. These may be used alone or in combination of two or more. When it is desired to add a function in addition to temperature sensitivity, any monomer that can be copolymerized with a (meth)acrylic monomer having a linear alkyl group having 14 or more carbon atoms and has that function can be freely copolymerized.

[0082] The ratio of the mass of the structural unit derived from the monofunctional monomer to the mass of the side-chain crystalline polymer is preferably 0.1% by mass or more, more preferably 1% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less.

[0083] The polyfunctional monomer can crosslink multiple molecular chains contained in the side-chain crystalline polymer. From the viewpoints of the dispersion state of the thermosensitive microparticles during use, suppression of deformation, and maintaining repeatable function, the side-chain crystalline polymer preferably contains a structural unit derived from the polyfunctional monomer. That is, the thermosensitive microparticles and the side-chain crystalline polymer are preferably crosslinked. The polyfunctional monomer has two or more, preferably two to four, radically polymerizable double bonds in the molecule. Examples of polyfunctional monomers include bifunctional (meth)acrylates, trifunctional (meth)acrylates, and tetrafunctional (meth)acrylates. Specific examples include 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, polyethylene glycol 200 di(meth)acrylate, and ethoxylated bisphenol A di(meth)acrylate. These may be used alone or in combination of two or more. The polyfunctional monomer may be at least one selected from a difunctional (meth)acrylate, a trifunctional (meth)acrylate, and a tetrafunctional (meth)acrylate.

[0084] The ratio of the mass of the structural unit derived from the polyfunctional monomer to the mass of the side-chain crystalline polymer is preferably 0.1% by mass or more, more preferably 1% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less.

[0085] The refractive index adjusting monomer may be a monomer having a refractive index of 1.300 to 1.600. Examples of refractive index adjusting monomers include 2-(O-phenylphenoxy)ethyl acrylate (refractive index: 1.577), 2-propenoic acid (3-phenoxyphenyl) methyl ester (refractive index: 1.566), 1-naphthyl acrylate (refractive index: 1.595), acrylamide (refractive index: 1.515), hydroxyacrylamide (refractive index: 1.515), EO-modified bisphenol A diacrylate (refractive index: 1.537), acrylamide (refractive index: 1.515), 2,2,2-trifluoroethyl acrylate (refractive index: 1.348), and methacryl-modified polydimethylsiloxane (refractive index: 1.408). These may be used alone or in combination of two or more.

[0086] The ratio of the mass of the structural unit derived from the refractive index adjusting monomer to the mass of the side-chain crystalline polymer is preferably 0.1% by mass or more, more preferably 1% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0087] Since the thermosensitive microparticles tend to have good dispersibility in adhesives, it is preferable that they do not contain structural units derived from a reactive emulsifier. A reactive emulsifier is an emulsifier having a polymerizable unsaturated bond such as a vinyl group in its molecule. The reactive emulsifier has emulsifying properties and is a polymerizable monomer having a polymerizable group having an unsaturated bond such as a vinyl group in its molecule and a hydrophilic group.

[0088] In the adhesive composition, the content of the thermosensitive microparticles is 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the adhesive. The content is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 40 parts by mass or more. The content is also preferably 70 parts by mass or less.

[0089] The method for producing the thermosensitive fine particles is not particularly limited, and they can be obtained by a conventionally known polymerization method such as mini-emulsion polymerization or suspension polymerization.

[0090] (Adhesive) The adhesive is not particularly limited, and conventionally known adhesives such as acrylic adhesives, natural rubber adhesives, synthetic rubber adhesives, silicone adhesives, and urethane adhesives can be used, with acrylic adhesives being preferred.

[0091] The polymer constituting the pressure-sensitive adhesive preferably contains a structural unit derived from an adhesive monomer that contributes to adhesiveness or a structural unit derived from a functional group monomer for crosslinking. The polymer constituting the pressure-sensitive adhesive may also contain a structural unit derived from another monomer that is copolymerizable with these monomers. Examples of other monomers include refractive index-adjusting monomers. That is, the polymer constituting the pressure-sensitive adhesive may contain a structural unit derived from a refractive index-adjusting monomer.

[0092] Examples of adhesive monomers include (meth)acrylates having an alkyl group having 1 to 12 carbon atoms, such as ethylhexyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate; (meth)acrylates having an ethylene glycol group, such as 2-ethylhexyl-diglycol (meth)acrylate, methoxyethyl (meth)acrylate, methoxypolyethylene glycol mono(meth)acrylate, and ethoxy-diethylene glycol (meth)acrylate; and ethylenically unsaturated monomers, such as styrene and vinyl acetate. These may be used alone or in combination of two or more. Of these, (meth)acrylates having an alkyl group having 1 to 12 carbon atoms are preferred.

[0093] The ratio of the mass of the structural unit derived from the adhesive monomer to the mass of the polymer constituting the PSA is preferably 50% by mass or more, more preferably 70% by mass or more, and is preferably 99.9% by mass or less, more preferably 90% by mass or less.

[0094] Examples of functional group monomers include (meth)acrylates having a hydroxyalkyl group, such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxyhexyl (meth)acrylate; and ethylenically unsaturated monomers having a carboxyl group, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid. Only one type may be used, or two or more types may be used in combination. Among these, ethylenically unsaturated monomers having a carboxyl group are preferred.

[0095] The ratio of the mass of the structural unit derived from the functional group monomer to the mass of the polymer constituting the adhesive is preferably 0.1 mass% or more, more preferably 1 mass% or more.Furthermore, the ratio is preferably 30 mass% or less, more preferably 20 mass% or less, and even more preferably 10 mass% or less.When it is 0.1 mass% or more, the shape retention tends to be good.When it is 30 mass% or less, the viscosity is not excessively high, and the coating property tends to be good.

[0096] The refractive index adjusting monomer may be a monomer having a refractive index of 1.300 to 1.600. Examples of refractive index adjusting monomers include 2-(O-phenylphenoxy)ethyl acrylate (refractive index: 1.577), 2-propenoic acid (3-phenoxyphenyl) methyl ester (refractive index: 1.566), 1-naphthyl acrylate (refractive index: 1.595), acrylamide (refractive index: 1.515), hydroxyacrylamide (refractive index: 1.515), EO-modified bisphenol A diacrylate (refractive index: 1.537), acrylamide (refractive index: 1.515), 2,2,2-trifluoroethyl acrylate (refractive index: 1.348), and methacryl-modified polydimethylsiloxane (refractive index: 1.408). These may be used alone or in combination of two or more.

[0097] The ratio of the mass of the structural unit derived from the refractive index adjusting monomer to the mass of the polymer constituting the pressure-sensitive adhesive is preferably 0.1 mass% or more, more preferably 1 mass% or more, and even more preferably 10 mass% or more, and is preferably 30 mass% or less.

[0098] The weight-average molecular weight of the pressure-sensitive adhesive is preferably 200,000 or more, more preferably 300,000 or more. The weight-average molecular weight is preferably 2,000,000 or less, more preferably 1,000,000 or less, and even more preferably 600,000 or less. When it is 200,000 or more, shape retention tends to be good. When it is 2,000,000 or less, the viscosity is not excessively high, and coating properties tend to be good.

[0099] The glass transition temperature (Tg) of the adhesive is preferably 25° C. or lower, as this tends to facilitate the exertion of high adhesive strength.

[0100] The difference in refractive index between the adhesive and the thermosensitive fine particles at 23° C. is preferably less than 0.015, more preferably less than 0.010. The difference in refractive index at 40° C. is preferably 0.015 or more. The upper limit of the difference in refractive index at 40° C. is not particularly limited, but is, for example, 0.1.

[0101] The ratio of the mass of the pressure-sensitive adhesive to the mass of the solid content of the pressure-sensitive adhesive composition is not particularly limited, but is, for example, 50 mass % or more and 95 mass % or less. In this specification, the solid content of the pressure-sensitive adhesive composition means all components of the pressure-sensitive adhesive composition excluding solvents such as aqueous solvents and organic solvents.

[0102] The method for producing the pressure-sensitive adhesive is not particularly limited, and the pressure-sensitive adhesive can be obtained by a conventionally known polymerization method such as solution polymerization or UV polymerization.

[0103] The pressure-sensitive adhesive composition may contain a crosslinking agent for crosslinking the pressure-sensitive adhesive. That is, the pressure-sensitive adhesive may be crosslinked. Examples of the crosslinking agent include an aziridine-based crosslinking agent, a metal chelate-based crosslinking agent, an epoxy-based crosslinking agent, and an isocyanate-based crosslinking agent.

[0104] The content of the crosslinking agent in the pressure-sensitive adhesive composition is not particularly limited, but is, for example, 0.1 to 10 parts by mass per 100 parts by mass of the pressure-sensitive adhesive. If the content is 0.1 parts by mass or more, shape retention tends to be less likely to be reduced. If the content is 10 parts by mass or less, high adhesive strength tends to be easily exhibited.

[0105] The pressure-sensitive adhesive composition may contain other additives such as a solvent such as an organic solvent, an inhibitor that suppresses the progress of crosslinking, a tackifier, an ultraviolet (UV) absorber, a light stabilizer (HALS), an antioxidant, an infrared absorber, a dye, or a pigment.

[0106] [Uses] The above-mentioned pressure-sensitive adhesive composition is not limited in its mode of use. The mode of use of the above-mentioned pressure-sensitive adhesive composition can be appropriately selected depending on the purpose. When the pressure-sensitive adhesive composition is designed to develop haze at high temperatures, it can soften direct sunlight during high summer temperatures and allow sunlight in during low winter temperatures, making it suitable for use in, for example, window materials and translucent roofing materials. On the other hand, when the pressure-sensitive adhesive composition is designed to develop haze at low temperatures, for example, when the pressure-sensitive adhesive composition is applied to window glass, the window glass functions as frosted glass under conditions with relatively low temperatures and little sunlight, such as in the morning or evening, while when the temperature rises with increased sunlight during the day, the window glass becomes transparent, allowing efficient lighting into the room. Furthermore, when the above-mentioned pressure-sensitive adhesive composition develops or disappears haze due to a heat source such as lighting, sunlight, or high temperatures, it can make designs such as letters, symbols, patterns, figures, and designs appear or disappear, making it possible to impart excellent display properties (designs such as letters and symbols) and decorative properties (designs such as patterns, figures, and designs) to an object having an adhesive layer. Therefore, it can be suitably used for example for decorative purposes such as lighting covers, decorative purposes for light-transmitting substrates such as window materials and light-transmitting roof materials, and displays for light-transmitting substrates such as window materials and light-transmitting roof materials.

[0107] <<Adhesive Sheet>> The adhesive sheet includes an adhesive layer made of an adhesive composition.

[0108] As described above, the temperature-sensitive light-controlling liquid laminate of Patent Document 1 requires a dedicated structure for maintaining the shape of the temperature-sensitive light-controlling liquid. Therefore, when installing it on an existing window or roof, extensive construction work such as replacing the entire window is required, which makes it difficult to install.

[0109] In contrast, adhesive sheets do not require a special structure to maintain their shape, can be easily installed by simply sticking them to existing windows or roofs, and have the advantage of being easily given the function of being able to autonomously change their opacity depending on the temperature.

[0110] The thickness of the adhesive layer is not particularly limited, but is preferably 5 μm or more and 1 mm or less, more preferably 10 μm or more and 100 μm or less. Note that the thicker the adhesive layer, the more likely it is that a small amount of thermosensitive fine particles will be added to exhibit the photochromic function. The thinner the thickness, the more likely it is that a large amount of thermosensitive fine particles will be added to exhibit the photochromic function.

[0111] The haze value of the adhesive layer at 40° C. is preferably 10% or more higher than the haze value at 23° C. This tends to make it easier to visually recognize changes in opacity depending on temperature.

[0112] The haze value of the adhesive layer at 23°C is preferably 10% or less, more preferably 5% or less. The lower limit of the haze value at 23°C is not particularly limited. The haze value of the adhesive layer at 40°C is preferably 12% or more, more preferably 20% or more, and even more preferably 30% or more. The upper limit of the haze value at 40°C is not particularly limited, but is, for example, 70% or less, 50% or less.

[0113] The solar radiation transmittance of the adhesive layer at 40°C is preferably lower than the solar radiation transmittance at 23°C by 10% or more.

[0114] The solar radiation transmittance of the adhesive layer at 23°C is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. The upper limit of the solar radiation transmittance at 23°C is not particularly limited, but is, for example, 95% or less, 85% or less. The solar radiation transmittance of the adhesive layer at 40°C is preferably 70% or less, more preferably 60% or less, and even more preferably 50% or less. The lower limit of the solar radiation transmittance at 40°C is not particularly limited.

[0115] The peel strength of the adhesive layer from stainless steel (SUS) at 23° C. is preferably 1.0 N / 25 mm or more. Also, the peel strength from polyethylene terephthalate (PET) at 23° C. is preferably 1.0 N / 25 mm or more. In this specification, the peel strength is a value measured by the method described in the Examples below.

[0116] The pressure-sensitive adhesive sheet may include a substrate sheet. The substrate constituting the substrate sheet is not particularly limited as long as it is a light-transmitting substrate. For example, PET such as corona-treated PET, untreated PET, highly transparent PET, annealed PET, UV-cut PET, heat-shielding PET, anti-fogging PET, hard-coated PET, and blast-treated PET; transparent PI, etc. can be used as the substrate.

[0117] The adhesive layer may be formed on only one side of the base sheet or on both sides thereof. Alternatively, an adhesive layer may be formed on one side of the base sheet and an adhesive layer other than the above-described adhesive layers may be formed on the other side.

[0118] A release sheet may be laminated on the surface of the adhesive layer, similar to the base sheet.

[0119] The pressure-sensitive adhesive sheet can be produced by a conventional method using the pressure-sensitive adhesive composition, for example, by applying a coating liquid obtained by adding a solvent and / or a crosslinking agent to the pressure-sensitive adhesive composition as needed to a substrate sheet using a coater or the like, and then drying the coating liquid by heating or the like to form a pressure-sensitive adhesive layer.

[0120] Examples of coaters include knife coaters, roll coaters, calendar coaters, comma coaters, etc. Depending on the coating thickness and the viscosity of the coating liquid, gravure coaters, rod coaters, etc. may also be used.

[0121] The present invention will be explained in more detail below by showing examples, but the scope of the present invention is not limited to these examples.

[0122] The various chemicals used in the examples are collectively described below. SA: Blenmer SA (stearyl acrylate) manufactured by NOF Corporation CA: Blenmer CA (cetyl acrylate) manufactured by NOF Corporation A-HD-N: A-HD-N (1,6-hexanediol diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd. NF-13: Hitenol NF-13 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. Perloyl L: Perloyl L (dilauryl peroxide) manufactured by NOF Corporation EHA: 2-ethylhexyl acrylate manufactured by Toagosei Co., Ltd. A-LEN-10: A-LEN-10 (2-(O-phenylphenoxy)ethyl acrylate) manufactured by Shin-Nakamura Chemical Co., Ltd. AA: acrylic acid manufactured by Nippon Shokubai Co., Ltd. Perbutyl ND: Perbutyl ND (t-butylperoxyneodecanoate) manufactured by NOF Corporation Perhexyl PV: Perhexyl PV (t-hexyl peroxypivalate) manufactured by NOF Corporation. PZ33: Chemitite PZ33 (aziridine-based crosslinking agent) manufactured by Nippon Shokubai Co., Ltd.

[0123] [Production of Thermosensitive Microparticles] The side-chain crystalline monomer, polyfunctional monomer, and initiator were added to a reaction vessel in the proportions shown in Table 1. The mixture in the reaction vessel was stirred with a spatula to ensure uniform mixing. Next, an aqueous medium and an emulsifier in the proportions shown in Table 1 were added to the reaction vessel to obtain a mixed solution. Water was used as the aqueous medium. The aqueous medium was added so that the ratio of the mass of the side-chain crystalline monomer to the total mass of the side-chain crystalline monomer and the aqueous medium in the mixed solution was 40% by mass. The mixed solution was then stirred at 7,500 rpm for 5 minutes using an IKA homogenizer (main unit: T 25 digital ULTRA-TURRAX, shaft generator: S25N-25F) to form particles from the monomer component. Finally, nitrogen was introduced into the mixed solution and bubbled to remove air (oxygen) from the mixed solution. The monomer component was then polymerized by heating and stirring at 67°C for 2 hours and at 80°C for 2 hours, respectively. The aqueous medium was then removed from the produced microparticles by suction filtration and vacuum drying, yielding thermosensitive microparticles 1. Thermosensitive microparticles 2 were obtained in the same manner as the manufacturing method of thermosensitive microparticles 1, except that the mixed solution was stirred for 5 minutes at 14,000 rpm using a homogenizer. Thermosensitive microparticles 3 were obtained in the same manner as the manufacturing method of thermosensitive microparticles 1, except that the mixed solution was stirred for 5 minutes at 6,800 rpm using a homogenizer. Thermosensitive microparticles 4 were obtained in the same manner as the manufacturing method of thermosensitive microparticles 1, except that the mixed solution was stirred for 3 minutes at 5,500 rpm using a homogenizer.

[0124] (Average particle size and D90 particle size of thermosensitive microparticles) The particle size distribution of the thermosensitive microparticles was measured using a laser diffraction particle size distribution analyzer "Mastersizer 3000" manufactured by Malvern Instruments. In the particle size distribution, the particle size corresponding to a cumulative volume frequency of 50%, calculated from the smaller particle size of the thermosensitive microparticles, was defined as the "average particle size," and the particle size corresponding to a cumulative volume frequency of 90% was defined as the "D90 particle size." The results are shown in Table 1.

[0125] (Melting Point of Thermosensitive Fine Particles) The melting point of the thermosensitive fine particles was measured from the temperature at the top of the endothermic peak when measuring the temperature range of −30 to 100° C. at a sweep rate of 10° C. / min using a DSC (differential scanning calorimeter) manufactured by Seiko Instruments Inc. The results are shown in Table 1.

[0126]

[0127] [Production of Pressure-Sensitive Adhesive] Monomers were charged into a reaction vessel at the ratios shown in Table 2. A solvent (ethyl acetate / methyl ethyl ketone = 90 / 10 (mass ratio)) was added to the reaction vessel to dilute the monomers to a monomer concentration of 38 mass%. Next, the diluted monomer solution was stirred and heated while nitrogen was introduced into the diluted monomer solution and bubbled. When the liquid temperature reached 55°C, an initiator was added to the diluted monomer solution at the ratios shown in Table 2. The liquid in the reaction vessel was further heated and stirred at 55°C for 4 hours, and then the temperature of the oil bath was raised to 80°C. When the liquid temperature exceeded 70°C, an accelerator was added to the reaction solution at the ratios shown in Table 2. Finally, the mixture was heated and stirred at 80°C for 2 hours to obtain a pressure-sensitive adhesive.

[0128] (Weight-average molecular weight of pressure-sensitive adhesive) The weight-average molecular weight was measured by gel permeation chromatography (GPC), and the obtained measured value was converted into polystyrene equivalent. The results are shown in Table 2.

[0129] (Glass Transition Temperature of Pressure-Sensitive Adhesive) Using a dynamic viscoelasticity measuring device "HAAKE MARS III" manufactured by Thermo Scientific, tan δ (loss tangent) was measured at 20 Hz, 5°C / min, and in a temperature rise process from -100 to 100°C. The glass transition temperature (Tg) was calculated from the peak temperature of the obtained tan δ. The results are shown in Table 2.

[0130]

[0131] [Preparation of Pressure-Sensitive Sheet] The obtained thermosensitive microparticles were added to a solvent (heptane) and stirred with a spatula to obtain a dispersion. The dispersion was then added to the obtained pressure-sensitive adhesive. The thermosensitive microparticles and pressure-sensitive adhesive were added in the proportions shown in Tables 3 and 4, and the solvent was added in a proportion that resulted in a solids concentration of 30% by mass. An inhibitor was added to this pressure-sensitive adhesive composition in the proportions shown in Tables 3 and 4, and the mixture was uniformly stirred with a spatula. Then, a crosslinking agent was added in the proportions shown in Tables 3 and 4. The pressure-sensitive adhesive composition was applied to the corona-treated surface of a PET film (thickness: 100 μm) using a bar coater. The PET film was then heated and dried at 110°C for 3 minutes in a hot air circulating oven to obtain pressure-sensitive adhesive sheets (Examples 1 to 7) having an adhesive layer (thickness: 40 μm) made of the crosslinked pressure-sensitive adhesive composition.

[0132] (Refractive Index of Thermosensitive Microparticles and Adhesive) The refractive indexes of the obtained thermosensitive microparticles and adhesive were measured at 23° C. and 40° C. using an automatic refractometer "Abbemat 350" manufactured by Anton Paar. The results are shown in Tables 3 and 4.

[0133] (Haze value of adhesive layer) The haze value of the adhesive layer of the obtained adhesive sheet was measured at 23°C and 40°C in accordance with ASTM D1003 using a spectrophotometer "CM3600" (light source C) manufactured by Konica Minolta, Inc. ITO glass was used as a reference, and the adhesive sheet was attached to the ITO glass surface to perform the measurement. The results are shown in Tables 3 and 4.

[0134] (Peel Strength) The resulting pressure-sensitive adhesive sheets of Examples 1 to 4 were measured for 180° peel strength against stainless steel (SUS) or polyethylene terephthalate (PET) at 23°C in accordance with JIS Z0237. Specifically, the pressure-sensitive adhesive sheet was attached to the SUS or PET and allowed to stand for 20 minutes, after which it was peeled off at 180° at a rate of 300 mm / min using a load cell. For the SUS, plate-shaped SUS304 was used. For the PET, an untreated film with a thickness of 25 μm was used. The pressure-sensitive adhesive sheet was attached to the SUS or PET by moving a 2 kg roller back and forth five times on the pressure-sensitive adhesive sheet. The results are shown in Table 3.

[0135] (Solar transmittance) For the obtained pressure-sensitive adhesive sheets of Examples 2 and 5 to 7, the solar transmittance was measured at 23°C and 40°C using a spectrophotometer "V770DS" manufactured by JASCO Corporation in accordance with JIS A5759:2016 6.5. However, since the measurement was performed by heating to 40°C, a 1.1 mm thick ITO glass ("GMT-100-12" manufactured by Geomatec Co., Ltd.) was used as the target to which the pressure-sensitive adhesive sheet was attached. Specifically, a test specimen was prepared by attaching the pressure-sensitive adhesive sheet to one side of the ITO glass. At 23°C and 40°C (surface temperature of the ITO glass measured with a contact thermometer), the glass surface of the test specimen was faced toward the light source, and the spectral transmittance at each wavelength of 300 to 2500 nm was measured using a spectrophotometer. As specified in JIS A5759:2016, the solar transmittance was calculated based on the relative spectral distribution of solar radiation. The results are shown in Table 4.

[0136] (Heat Shielding Property) The heat shielding property of the obtained pressure-sensitive adhesive sheets of Examples 2 and 5 to 7 was evaluated as shown in Figures 5 to 7. Specifically, a test specimen was prepared by attaching a pressure-sensitive adhesive sheet 1 to a glass plate 2. The test specimen was placed on a wooden frame 4 measuring 120 mm wide x 200 mm deep x 100 mm high, with the pressure-sensitive adhesive sheet surface facing upward. A thermometer (thermocouple) 3 was installed 10 mm below the glass surface. The sides and bottom of the wooden frame 4 were covered with a polyethylene sheet as a windbreak. The wooden frame 4 on which the test specimen was placed was placed on a metal rack 5 so that its height from the ground 6 was 1,000 mm. The temperature rise value of the thermocouple 3 during solar radiation (sun radiation duration: approximately 360 minutes, average temperature: 32°C) was recorded. A glass plate without a pressure-sensitive adhesive sheet attached was used as a blank test specimen, and the temperature rise value was recorded in the same manner. The difference from the temperature rise value of the blank was calculated. The results are shown in Table 4.

[0137]

[0138] As is clear from Table 3, Examples 1 to 4 show that the adhesive layers of Examples 1 to 4 having the above-described predetermined configurations can autonomously change their opacity in response to temperature. Therefore, Examples 1 to 4 show that window materials and translucent roof materials having the above-described adhesive layers can autonomously change their opacity in response to temperature.

[0139]

[0140] REFERENCE SIGNS LIST 10 First window material 11 Light-transmitting substrate layer 12 Adhesive layer 12a Adhesive 12b Temperature-sensitive fine particles 13 Substrate sheet 20 Second window material 21a, 21b Light-transmitting substrate layer 22 Adhesive layer 22a Adhesive 22b Temperature-sensitive fine particles 30 Light-transmitting roofing material 31 Light-transmitting substrate layer 32 Adhesive layer 32a Adhesive 32b Temperature-sensitive fine particles 33 Substrate sheet

Claims

1. At least one light-transmitting base layer and at least one adhesive layer are provided, the adhesive layer is made of an adhesive composition containing 1 to 100 parts by mass of thermosensitive fine particles relative to 100 parts by mass of an adhesive; The refractive index of the thermosensitive fine particles decreases with increasing temperature, and A window material, wherein a refractive index decrease rate of the thermosensitive particles, which is an amount of decrease in refractive index per 1° C., is greater in the vicinity of the melting point of the thermosensitive particles than in any other temperature range other than the vicinity of the melting point of the thermosensitive particles.

2. 2. The window material according to claim 1, wherein the difference in refractive index between the adhesive and the temperature-sensitive fine particles is less than 0.015 at 23°C and is 0.015 or more at 40°C.

3. 2. The window material according to claim 1, wherein the haze value of the adhesive layer at 40°C is at least 10% higher than the haze value of the adhesive layer at 23°C.

4. the thermosensitive fine particles contain a side chain crystalline polymer, 2. The window material according to claim 1, wherein the side-chain crystalline polymer contains 70 to 100% by mass of a structural unit derived from a (meth)acrylic monomer having a linear alkyl group having 14 or more carbon atoms.

5. 2. The window material according to claim 1, wherein the refractive index of the thermosensitive fine particles at (melting point+7)° C. is lower by 0.02 or more than the refractive index of the thermosensitive fine particles at (melting point-10)° C.

6. At least one light-transmitting base layer and at least one adhesive layer are provided, the adhesive layer is made of an adhesive composition containing 1 to 100 parts by mass of thermosensitive fine particles relative to 100 parts by mass of an adhesive; The refractive index of the thermosensitive fine particles decreases with increasing temperature, and A light-transmitting roofing material in which the refractive index reduction rate of the thermosensitive particles, which is the amount of reduction in refractive index per 1° C., is greater near the melting point of the thermosensitive particles than in any other temperature range near the melting point of the thermosensitive particles.

7. 7. The light-transmitting roofing material according to claim 6, wherein the difference in refractive index between said adhesive and said temperature-sensitive fine particles is less than 0.015 at 23°C and is 0.015 or more at 40°C.

8. The light-transmitting roofing material according to claim 6, wherein the haze value of the adhesive layer at 40°C is 10% or more higher than the haze value of the adhesive layer at 23°C.

9. the thermosensitive fine particles contain a side chain crystalline polymer, 7. The light-transmitting roofing material according to claim 6, wherein the side-chain crystalline polymer contains 70 to 100% by mass of a structural unit derived from a (meth)acrylic monomer having a linear alkyl group having 14 or more carbon atoms.

10. 7. The light-transmitting roofing material according to claim 6, wherein the refractive index of the temperature-sensitive fine particles at (melting point + 7)°C is lower by 0.02 or more than the refractive index of the temperature-sensitive fine particles at (melting point - 10)°C.

11. A building comprising a window material according to any one of claims 1 to 5, and / or a light-transmitting roof material according to any one of claims 6 to 10.

12. A vehicle, ship, or aircraft equipped with a window material according to any one of claims 1 to 5, and / or a light-transmitting roof material according to any one of claims 6 to 10.

13. The adhesive contains 1 to 100 parts by mass of thermosensitive fine particles relative to 100 parts by mass of the adhesive, The refractive index of the thermosensitive fine particles decreases with increasing temperature, and An adhesive composition, in which the refractive index decrease rate of the thermosensitive microparticles, which is the amount of decrease in refractive index per 1°C, is greater near the melting point of the thermosensitive microparticles than in any other temperature range near the melting point of the thermosensitive microparticles.

14. The adhesive composition according to claim 13, wherein the difference in refractive index between the adhesive and the thermosensitive fine particles is less than 0.015 at 23°C and is 0.015 or more at 40°C.

15. the thermosensitive fine particles contain a side chain crystalline polymer, The pressure-sensitive adhesive composition according to claim 13, wherein the side-chain crystalline polymer contains 70 to 100 mass % of a structural unit derived from a (meth)acrylic monomer having a linear alkyl group having 14 or more carbon atoms.

16. The adhesive composition according to claim 13, wherein the refractive index of the thermosensitive fine particles at (melting point + 7)°C is lower by 0.02 or more than the refractive index of the thermosensitive fine particles at (melting point - 10)°C.

17. A pressure-sensitive adhesive sheet comprising an adhesive layer made of the pressure-sensitive adhesive composition according to any one of claims 13 to 16.

18. The pressure-sensitive adhesive sheet according to claim 17 , wherein the haze value of the pressure-sensitive adhesive layer at 40° C. is at least 10% higher than the haze value of the pressure-sensitive adhesive layer at 23° C.