JP7610858B2 - Heat-shielding composite sheet - Google Patents

Description

The present invention relates to a heat-shielding composite sheet used primarily as a material for tent membrane structures, and to a technology for improving its durability, i.e., extending its useful life, and more specifically to a heat-shielding tarpaulin with light-gathering properties for use in tent membrane structures, and improving the weather resistance of heat-shielding canvas. The heat-shielding tent membrane structure obtained by the present invention achieves an indoor temperature that is 3 to 5°C lower than the outdoor air temperature in summer, thereby saving a corresponding amount of energy for air conditioning and cooling, and by having appropriate light-gathering properties, energy for lighting is also saved, thereby contributing to efforts to prevent global warming, and by extending the useful life, this contribution can be made more sustainable.

Enclosed tent membrane structures include those that are primarily intended for entertainment (people), such as indoor sports (tennis, futsal, bouldering, etc.), exhibition halls, event pavilions, traveling circuses, video projection domes, and glamping, and those that are primarily intended for the storage and stockpiling of factory materials and the distribution of products (goods), such as tent warehouses. All of them use a synthetic fiber fabric such as polyester fiber fabric as the base material, covered on both sides with a thermoplastic resin layer such as soft polyvinyl chloride resin, as a tarpaulin, or waterproof canvas. Enclosed tent membrane structures have entrance doors and opening/closing windows that form an enclosed space when closed. On the other hand, the open type, as opposed to the enclosed type, is an open-ceiling structure that is primarily made of a roof structure, and specific examples include sunshade monuments in parks and theme parks, garden terrace roofs installed in the spaces between buildings, and pergola shades. Although closed-type tent membrane structures protect people and goods from wind and rain, they have the disadvantage that the heat from solar radiation in summer tends to build up inside because they are made of semi-transparent membrane materials to allow light in. On the other hand, open-type structures are well ventilated, but are not suitable for protecting people and goods from wind and rain. And while closed-type tent membrane structures that are primarily used for entertainment (people) are equipped with air conditioning and heating/cooling equipment, tent warehouses that are primarily used for logistics (goods) rarely have such equipment. However, the heat builds up inside tent warehouses in summer, making them harsh environments, so heatstroke prevention measures such as electric fans and spot coolers are essential for employees who manage and take in and out the storage and stockpiling of factory materials.

In order to reduce the heat inside such a tent warehouse, it is effective to make the tent membrane (tarpaulin, waterproof canvas) a reflective color such as white or silver. In particular, it is known that titanium oxide pigments have a high refractive index and therefore a high light scattering power, which results in a high solar reflectance (heat shielding rate). However, the greater the light scattering power, the higher the concealment power becomes, and the light gathering ability of the tent membrane is hindered, so that the inside of the tent warehouse becomes an environment where lighting is required even during the day. In response to this dilemma, the applicant previously proposed a membrane material (Patent Document 1) for a tent (warehouse) that combines a heat-blocking effect and light gathering ability, in which the thermoplastic resin coating layer of the membrane contains 0.3 to 30 mass% of amorphous inorganic compound particles (titanium oxide) with a refractive index of 1.8 or more, a particle size distribution of 0.3 to 3.0 μm, and an aspect ratio of 1.0 to 3.0. In this embodiment, a heat shielding rate of 38 to 65% and daylighting with a light transmittance of 4 to 45% can be obtained, and it is expected that the effect of reducing the power consumption of air conditioning in the summer and the power consumption of lighting throughout the year can be expected. However, in exchange for the daylighting with a light transmittance of 4 to 45%, the risk of discoloring the tent membrane (thermoplastic resin coating layer) due to ultraviolet damage caused by light transmission and cracking on the surface, which shortens the service life of the membrane material, is high. As one of the recent efforts of the SDGs, a tent membrane material that can be used for a long time is desired. This is because by extending the service life of the tent membrane material by several years, the replacement cycle of the tent membrane material can be extended, reducing the consumption of petrochemical resources that are the raw materials for synthetic fiber fabrics and thermoplastic resins used to manufacture the tent membrane material, and further contributing to society by reducing carbon dioxide emissions. At the time when the tent membrane material with both heat shielding effect and daylighting of Patent Document 1 was considered, there was no global effort to reduce the consumption of petrochemical resources and stop global warming.

Specifically, as a means for improving the service life of industrial heat-shielding composite sheets made of soft polyvinyl chloride resin, the applicant has previously considered a method of blending an ultraviolet absorbing agent into a soft polyvinyl chloride resin layer (Patent Document 2) and a method of providing a coating layer containing a high molecular weight ultraviolet absorbing agent on the surface of a heat-shielding composite sheet (Patent Document 3). In addition, a recent proposal was made to form a heat-shielding composite sheet from an organic polymer or an organic/inorganic condensate and to contain (modified) cellulose nanofibers (Patent Document 4) as a method for obtaining a heat-shielding composite sheet that does not easily crack, wear out, or fall off the heat-shielding layer of the tarpaulin, and has long-lasting heat-shielding properties. However, due to the need to lengthen the replacement cycle of light-gathering and heat-shielding tent membrane materials, and for the sake of protecting the global environment, there is a need to further extend the service life.

JP 2007-055177 A Japanese Patent Application Publication No. 59-41249 JP 2001-225423 A JP 2021-66122 A

The problem to be solved by this invention is to improve the weather resistance (reduction of ultraviolet degradation) of the light-gathering and heat-shielding membrane material that constitutes the tent membrane structure, i.e., to provide a membrane material (composite sheet such as tarpaulin or canvas) for tent membrane structures that has excellent light-gathering, heat-shielding, and weather resistance. In addition, the object of this invention is to contribute to the conservation of the global environment by extending the service life of the membrane material (heat-shielding composite sheet) for tent membrane structures, thereby reducing the frequency of disposal (i.e. replacement) and the amount of membrane material to be disposed of.

As a result of considering these points and carrying out extensive research, the present invention has found that the heat-shielding composite sheet of the present invention is a composite sheet in which a thermoplastic resin layer is laminated on a fabric, the thermoplastic resin layer contains at least surface-treated titanium oxide particles, a keto/enol type tautomer, and an N-OR type hindered amine, the surface-treated titanium oxide particles have a primary average particle size of 0.4 to 1.2 μm, the keto/enol type tautomer is one or more selected from benzotriazole-based tautomers, triazine-based tautomers, and diphenyl ketone-based tautomers, and further a thin film layer containing zinc oxide or a mixture of titanium oxide and zinc oxide is formed on the thermoplastic resin layer. and the zinc oxide and titanium oxide have a coating layer on the surface of the particles and have a primary average particle size of 10 to 50 nm , thereby making it possible to obtain a membrane material for tent membrane structures (a composite sheet such as tarpaulin or canvas) having excellent light-collecting, heat-shielding and weather resistance, and the improved weather resistance (reduced ultraviolet light deterioration) makes it possible to extend the service life of the light-collecting and heat-shielding composite sheet, which results in a reduction in the frequency of disposal (i.e., replacement) and a reduction in the amount of membrane material to be discarded, and at the same time, a reduction in the amount of membrane material produced, which suppresses the consumption of petrochemical resources that cause carbon dioxide emissions, thereby contributing to the conservation of the global environment, and thus the present invention has been completed with this conviction.

In the heat-shielding composite sheet of the present invention, the keto/enol tautomer is preferably one or more selected from benzotriazole tautomers, triazine tautomers, and diphenyl ketone tautomers. This keto/enol tautomer repeats mutual conversion between the enol isomer and the keto isomer in nanosecond units when stimulated by sunlight (ultraviolet rays), so that the enol and keto isomers coexist in equilibrium within the thermoplastic resin layer, and the ultraviolet energy received is converted into thermal energy of molecular vibrations during the mutual conversion and released outside the system, thereby reducing damage caused by ultraviolet rays through the manifestation of an energy attenuation effect.

In the heat shielding composite sheet of the present invention, the benzotriazole-based tautomer is preferably an enol type isomer (Ia) [Chemical formula 1] having a skeleton of a C-N bond between one benzene ring (which may have one or two types selected from an alkyl group, a branched alkyl group, and an alkyl-substituted benzyl group) having a hydroxyl group (1 to 2 groups)/ketone group (0 groups) and a benzotriazole ring (which may have a substituent), or a keto type isomer (IIa) [Chemical formula 2] having a skeleton of a C-N bond between one benzene ring (which may have one or two types selected from an alkyl group, a branched alkyl group, and an alkyl-substituted benzyl group) having a hydroxyl group (0 to 1 groups)/ketone group (1 group) and a benzotriazole ring (which may have a substituent). When stimulated by sunlight (ultraviolet rays), this benzotriazole tautomer repeatedly undergoes interconversion between the enol isomer (Ia) [Chemical formula 1] and the keto isomer (IIa) [Chemical formula 2] on a nanosecond basis. As a result, the enol and keto isomers coexist in equilibrium within the heat-shielding layer, and the ultraviolet light energy received is converted into thermal energy of the molecular vibrations involved in the interconversion and released outside the system, thereby exerting an energy attenuation effect and reducing damage caused by ultraviolet light.
R is at least one selected from the group consisting of a hydroxyl group, an alkyl group, a branched alkyl group, and an alkyl-substituted benzyl group.
R is at least one selected from the group consisting of a hydroxyl group, an alkyl group, a branched alkyl group, and an alkyl-substituted benzyl group.

In the heat shielding composite sheet of the present invention, the triazine-based tautomer is preferably an enol isomer (Ib) [Chemical formula 3] having as a main skeleton a C-C bond between 1 to 3 benzene rings (which may have an alkyloxy group) having 1 to 2 hydroxyl groups/0 ketone groups and a 1,3,5-triazine ring (which may have an alkyl-substituted phenyl group and/or a hydroxyl-substituted phenyl group), or a keto isomer (IIb) [Chemical formula 4] having as a main skeleton a C-C bond between 1 to 3 benzene rings (which may have an alkyloxy group) having 1 to 2 hydroxyl groups/1 ketone group and a 1,3,5-triazine ring (which may have an alkyl-substituted phenyl group and/or a hydroxyl-substituted phenyl group). When stimulated by sunlight (ultraviolet rays), this triazine tautomer repeatedly undergoes interconversion between the enol isomer (Ib) [Chemical formula 3] and the keto isomer (IIb) [Chemical formula 4] on a nanosecond basis. As a result, the enol and keto isomers coexist in equilibrium within the heat-shielding layer, and the ultraviolet light energy received is converted into thermal energy through molecular vibrations during the interconversion and released outside the system, thereby exerting an energy attenuation effect and reducing damage caused by ultraviolet light.
R ₁ is a hydroxyl group and/or an alkyloxy group, R ₂ and R ₃ are alkyl-substituted phenyl groups and/or hydroxyl-substituted phenyl groups.
R ₁ is a hydroxyl group and/or an alkyloxy group, R ₂ and R ₃ are alkyl-substituted phenyl groups and/or hydroxyl-substituted phenyl groups.

In the heat shielding composite sheet of the present invention, the diphenyl ketone tautomer is preferably an enol type isomer (Ic) [Chemical formula 5] having a main skeleton in which two benzene rings of hydroxyl group (1 to 2)/ketone group (0)/alkyloxy group (0 to 1) are linked by a C=O bond, or a keto type isomer (IIc) [Chemical formula 6] having a main skeleton in which one benzene ring of hydroxyl group (0 to 1)/ketone group (1)/alkyloxy group (0 to 1) and one benzene ring of hydroxyl group (1 to 2)/ketone group (0)/alkyloxy group (0 to 1) are linked by a C=O bond. When stimulated by sunlight (ultraviolet rays), this diphenyl ketone tautomer repeatedly undergoes interconversion between the enol isomer (Ic) [Chemical formula 5] and the keto isomer (IIc) [Chemical formula 6], resulting in the enol and keto isomers coexisting in equilibrium within the heat-shielding layer. The ultraviolet energy received is converted into thermal energy through molecular vibrations that are interconverted on a nanosecond basis, and then released outside the system, thereby exerting an energy attenuation effect and reducing damage caused by ultraviolet rays.
R ₁ and R ₂ each represent a hydroxyl group and/or an alkyloxy group.
R ₁ and R ₂ each represent a hydroxyl group and/or an alkyloxy group.

In the heat-shielding composite sheet of the present invention, the N-OR type hindered amine preferably has, at the N-position of the hindered amine structure, one or more substituents selected from an alkoxy group having 2 to 18 carbon atoms and a cycloalkoxy group having 5 to 12 carbon atoms. This allows the N-OR type hindered amine compound to capture peroxide radicals (ROO.) generated from the thermoplastic resin layer due to ultraviolet damage at the N-OR moiety, render them harmless as alcohols or ketones, and release them, while converting itself to a nitroxy radical (N-O.), capture alkyl radicals (R.) generated from the thermoplastic resin layer due to ultraviolet damage, and return to the N-OR type hindered amine compound, repeating this cycle on a nanosecond basis, thereby making it possible to inhibit the chain reaction of bond cleavage in the thermoplastic resin due to the attack of harmful radicals.
R ₁ , R ₂ , R ₃ and R ₄ each independently represent: a) a hydrogen atom; b) a linear or branched alkyl group having 1 to 20 carbon atoms; c) one or more -O-, -S-,
-SO-, -SO ₂ -, -CO-, -COO-, -OCO-, -CONR-,
an alkyl group of the above b) containing -NRCO- or -NR-; d) an alkenyl group having 3 to 20 carbon atoms; e) an aryl group having 6 to 10 carbon atoms; and f) an alkyl group having 1 to 20 carbon atoms.
An aryl group having 1 to 3 substituents selected from a cycloalkyl group having 5 to 12 carbon atoms and a phenylalkyl group having 7 to 15 carbon atoms. R ₅ is an alkyl group having 2 to 18 carbon atoms or a cycloalkyl group having 5 to 12 carbon atoms.

In the heat-shielding composite sheet of the present invention, the thermoplastic resin layer preferably further contains zinc oxide or a mixture of titanium oxide and zinc oxide, and the zinc oxide and titanium oxide have a primary average particle diameter of 0.3 μm or less and a coating layer on the particle surface. This allows zinc oxide or zinc oxide and titanium oxide particles with a primary average particle diameter of 0.3 μm or less (0.1 μm to 0.3 μm) to enter the gaps between the surface-treated titanium oxide particles with a primary average particle diameter of 0.4 to 1.2 μm contained in the thermoplastic resin layer, and the zinc oxide and titanium oxide particles with this particle diameter can scatter ultraviolet rays that penetrate into the thermoplastic resin layer and block the transmission of ultraviolet rays. In particular, zinc oxide has an excellent UVA (ultraviolet A wave) blocking effect, and titanium oxide has an excellent UVB (ultraviolet B wave) blocking effect, so it is preferable to use a mixture of titanium oxide and zinc oxide. The zinc oxide and titanium oxide particles used in the present invention are ultraviolet blocking agents that do not deteriorate the thermoplastic resin layer whose photocatalytic activity has been sealed by surface treatment.

In the heat-shielding composite sheet of the present invention, a thin film layer containing zinc oxide or a mixture of titanium oxide and zinc oxide is formed on the thermoplastic resin layer, and the zinc oxide and titanium oxide preferably have a primary average particle size of 10 to 50 nm and a coating layer on the particle surface. Due to the presence of this thin film layer, ultraviolet rays penetrating the thermoplastic resin layer are scattered by the zinc oxide and/or titanium oxide particles having a primary average particle size of 10 to 50 nm, blocking the transmission of ultraviolet rays, and the light resistance of the thermoplastic resin layer can be further improved by the synergistic effect with the keto/enol tautomer and the N-OR hindered amine. In particular, zinc oxide has an excellent UVA (ultraviolet A wave) blocking effect, and titanium oxide has an excellent UVB (ultraviolet B wave) blocking effect, so it is preferable to use a mixture of titanium oxide and zinc oxide. The zinc oxide and titanium oxide particles used in the present invention do not deteriorate the thermoplastic resin layer in which the photocatalytic activity is sealed by surface treatment.

In the heat-shielding composite sheet of the present invention, a thin film layer mainly composed of an organosilicate compound or a sol-gel condensate of a silanol group-containing organic silane compound is formed on the thermoplastic resin layer, and it is preferable that the thin film layer contains one or more photocatalytic metal oxides selected from titanium oxide, titanium peroxide, zinc oxide, tin oxide, strontium titanate, tungsten oxide, bismuth oxide, and iron oxide. By disposing such a thin film layer on the thermoplastic resin layer, the photocatalytic metal oxide contained in the thin film layer exhibits photocatalytic activity by ultraviolet excitation. This photocatalytic activity contributes to the long-term durability of the thermoplastic resin layer by acting as a self-cleaning action to remove attached foreign matter such as soot and dust stains. At this time, the ultraviolet light received by the heat-shielding composite sheet of the present invention penetrates the thin film layer and reaches the thermoplastic resin layer, but in the thin film layer, a part of the ultraviolet light energy that penetrates is consumed by the activation of the photocatalytic metal oxide, so that the ultraviolet light energy that reaches the thermoplastic resin layer located below is attenuated. Therefore, placing a thin film layer on a thermoplastic resin layer protects the thermoplastic resin layer and can contribute to extending the service life of the heat-shielding composite sheet.

The present invention makes it possible to obtain a membrane material (composite sheet such as tarpaulin or canvas) for tent membrane structures that has excellent lighting, heat insulation, and weather resistance, and by extending the service life of the membrane material (heat-shielding composite sheet) for tent membrane structures, the frequency of disposal (i.e., replacement) is reduced, and the amount of membrane material to be disposed of is reduced. At the same time, the amount of membrane material produced is reduced, which reduces the amount of petrochemical resources used, and contributes to the conservation of the global environment by reducing carbon dioxide emissions. Specifically, this membrane material is ideal for long-term (10 to 15 years) tent structures such as indoor sports facilities, event pavilions, traveling circuses, planetariums, and tent warehouses, and can also be used for applications lasting less than 10 years, such as architectural protection (soundproofing) sheets, pergola shades (membrane ceilings), facade sheets, lift-up sheet shutters, partition sheets, truck canopies, open-air waterproof sheets, and roofed tents.

The heat-shielding composite sheet of the present invention is a composite sheet in which a thermoplastic resin layer is laminated on a fabric, and includes an embodiment in which the thermoplastic resin layer contains at least surface-treated titanium oxide particles, a keto/enol tautomer (one or more selected from benzotriazole-based tautomers and triazine-based tautomers), and an N-OR hindered amine; an embodiment in which the thermoplastic resin layer further contains a specific zinc oxide or a mixture of a specific titanium oxide and a specific zinc oxide; an embodiment in which a thin film layer containing a specific zinc oxide or a mixture of a specific titanium oxide and a specific zinc oxide is formed on the thermoplastic resin layer; and an embodiment in which a thin film layer mainly composed of a sol-gel condensate is formed on the thermoplastic resin layer, and a photocatalytic metal oxide is contained within this thin film layer.

The thermoplastic resin constituting the thermoplastic resin layer of the heat shielding composite sheet of the present invention is a thermoplastic resin having a Shore A hardness of about 35 to 85, such as soft vinyl chloride resin (blended with plasticizer), vinyl chloride copolymer resin, chlorinated vinyl chloride resin, olefin resin (PE, PP), olefin copolymer resin, ethylene-vinyl acetate copolymer resin (EVA), ethylene-(meth)acrylic acid (ester) copolymer resin, urethane resin, vinyl acetate copolymer resin, styrene copolymer resin, polyester copolymer resin, or fluorine-containing copolymer resin, or an elastomer. Two or more of these may be blended in a compatible or semi-compatible state, or two or more may be used as a multi-layer film or multi-layer coating. An elastomer is a block copolymer resin made of two or more monomers, and is a flexible resin in which each block component constitutes a hard segment and a soft segment. Tarpaulin for tent membrane structures is a flexible fiber composite with a thickness of 0.5 to 1.5 mm, in which a thermoplastic resin composition film is laminated as a thermoplastic resin layer on both sides of a fabric, and the thermoplastic resin composition film is most preferably made of soft polyvinyl chloride resin (mixed with plasticizer) because of its excellent processability, flexibility, abrasion resistance, weather resistance, and flame resistance. Canvas for tent membrane structures is a flexible fiber composite with a thickness of 0.3 to 0.8 mm, in which a liquid thermoplastic resin composition is impregnated and coated on both sides of a fabric, and then solidified into a film, and the thermoplastic resin composition is most preferably made of soft polyvinyl chloride resin (paste sol mixed with plasticizer) because of its excellent processability, flexibility, abrasion resistance, weather resistance, and flame resistance.

The primary average particle size of the surface-treated titanium oxide particles contained as an essential component in the thermoplastic resin layer is preferably 0.4 to 1.2 μm. Titanium oxide as a white pigment has a particle size of 0.2 to 0.4 μm, which is about half the wavelength of light, to maximize scattering in the visible light region (400 to 700 nm), thereby obtaining high concealment properties. On the other hand, by increasing the particle size to 0.4 to 1.2 μm, the concealment properties decrease, but the reflection effect in the near-infrared region (780 to 2500 nm), which accounts for about 50% of solar energy, is increased, resulting in a heat shielding effect superior to that of pigment titanium oxide. The preferred primary average particle size is 0.9 to 1.1 μm, and the shape of these surface-treated titanium oxide particles is approximately spherical, egg-shaped, bale-shaped, potato-shaped, etc., with an aspect ratio of 1:1 to 1:2. Surface-treated titanium oxide particles having a minor axis diameter of 0.4 to 0.8 μm, a major axis diameter of 2.0 to 4.0 μm, and an aspect ratio of 1:5 to 1:10, such as rod-shaped or square-shaped particles, can also be used in combination. If the surface treatment is not performed, the photocatalytic activity will cause radical attack on the thermoplastic resin of the thermoplastic resin layer, resulting in deterioration. The surface treatment performed on the titanium oxide particles is for preventing aggregation, improving dispersibility, and sealing the photocatalytic activity of the titanium oxide particles, and is a surface treatment with one or more metal oxides (7 options) selected from aluminum oxide, zirconium oxide, silicon oxide, and aluminum hydroxide. In addition to the surface treatment with these metal oxides, a multi-layer surface treatment may be performed in which a silane coupling agent, saturated alkyl titanate, saturated alkyl silane, polysiloxane, acrylic silicone, and metal soap (metal salt of long-chain fatty acid such as stearic acid or lauric acid and metal such as barium or zinc) are applied in one layer or two layers. Such surface treatment further improves aggregation prevention and dispersibility. The amount of surface-treated titanium oxide particles contained in the thermoplastic resin layer is 3 to 20 parts by mass, preferably 5 to 12 parts by mass, per 100 parts by mass of the thermoplastic resin.

The amount of the keto/enol tautomer contained in the thermoplastic resin layer as an essential component is 0.1 to 10 parts by mass, preferably 0.2 to 5 parts by mass, based on 100 parts by mass of the thermoplastic resin constituting the thermoplastic resin layer, and the keto/enol tautomer is at least one selected from benzotriazole tautomers, triazine tautomers, and diphenyl ketone tautomers. The use of multiple keto/enol tautomers herein includes combinations of different systems and variations of combinations in the same system. The keto/enol tautomer is an organic compound that can be reversibly converted between R ₂ -CH-(C═O)-R ₁ (keto isomer) and R ₂ -C═CH(OH)-R ₁ (enol isomer). Benzotriazole tautomers exist in enol and keto forms. The enol isomer (Ia) is an organic compound [Chemical Formula 1] having a skeleton of a C-N bond between one benzene ring (which may have one or two groups selected from a C1-C10 alkyl group, a C4-C10 branched alkyl group, and an alkyl-substituted benzyl group) having hydroxyl groups (1 to 2)/ketone groups (0) and a benzotriazole ring (which may have a chlorine group), specifically a structure having a hydroxyl group at the 2-position of the benzene ring, a structure having hydroxyl groups at the 2-position and any one of the 3-5-positions of the benzene ring, or a structure having a hydroxyl group at the 2-position of the benzene ring and one or two groups selected from an alkyl group, a branched alkyl group, and an alkyl-substituted benzyl group at the 3-position and/or the 5-position. The keto type isomer (IIa) is an organic compound [Chemical formula 2] having a main skeleton of one benzene ring (which may have any of a C1-C10 alkyl group, a C4-C10 branched alkyl group, or an alkyl-substituted benzyl group) having hydroxyl groups (0-1)/ketone groups (1), and a C-N bond between a benzotriazole ring (which may have a chlorine group), specifically a structure having a ketone group at the 2-position of the benzene ring, a structure having a ketone group at the 2-position of the benzene ring and a hydroxyl group at any of the 3-5-positions, or a structure having a ketone group at the 2-position of the benzene ring and an alkyl group, a branched alkyl group, or an alkyl-substituted benzyl group at the 3- and/or 5-positions. Both the keto type and the enol type isomers are repeatedly converted to each other, and both isomers coexist in equilibrium. Benzotriazole compounds having a molecular weight in the range of 250 to 700, particularly hydroxyphenylbenzotriazole derivatives, are preferred as the enol type. In the thermoplastic resin layer, the benzotriazole tautomers are repeatedly converted into the enol isomer (Ia) [Chemical formula 1] and the keto isomer (IIa) [Chemical formula 2] by the excitation of sunlight (ultraviolet light) energy, and the ultraviolet light energy is converted into molecular vibration energy of the conversion and released outside the system, thereby attenuating the deterioration damage caused by ultraviolet light. This ultraviolet light attenuation effect of the thermoplastic resin layer greatly contributes to the extension of the service life of the heat-shielding composite sheet of the present invention. Here, the alkyl-substituted benzyl group means a benzyl group "C ₆ H ₆ -CH ₂ -" substituted with an alkyl group "C ₆ H ₆ -CR ₁ R ₂ -" (R ₁ and R ₂ are C1 to C10 alkyl groups). The benzotriazole tautomers can be used by grafting them to the side chains of acrylic polymers.
R is at least one selected from the group consisting of a hydroxyl group, an alkyl group, a branched alkyl group, and an alkyl-substituted benzyl group.
R is at least one selected from the group consisting of a hydroxyl group, an alkyl group, a branched alkyl group, and an alkyl-substituted benzyl group.

In addition, triazine tautomers exist in enol and keto forms, and the enol isomer (Ib) is an organic compound [Chemical Formula 3] having a main skeleton of a C-C bond between 1 to 3 benzene rings (which may have a C1 to C10 alkyloxy group) having 1 to 2 hydroxyl groups/0 ketone groups and a 1,3,5-triazine ring (which may have an alkyl (1 to 2) substituted phenyl group and/or a hydroxyl (1 to 2) substituted phenyl group), specifically a structure having a hydroxyl group at the 2-position of the benzene ring, a structure having hydroxyl groups at the 2-position and an alkyloxy group at the 4-position of the benzene ring, the alkyl (1 to 2) substituted phenyl group being at the 2-position or the 4-position, or the 2-position and the 4-position, and the hydroxyl (1 to 2) substituted phenyl group being at the 2-position or the 4-position or the 2-position and the 4-position. The keto isomer (IIb) is an organic compound [Chemical Formula 4] having a skeleton of a C-C bond between 1 to 3 benzene rings (which may have a C1 to C10 alkyloxy group) having 0 to 1 hydroxyl group/1 ketone group and a 1,3,5-triazine ring (which may have an alkyl (1 to 2) substituted phenyl group and/or a hydroxyl (1 to 2) substituted phenyl group), specifically, a structure having a ketone group at the 2-position of the benzene ring, a structure having a ketone group at the 2-position and a hydroxyl group at the 4-position of the benzene ring, a structure having a ketone group at the 2-position and an alkyloxy group at the 4-position of the benzene ring, the alkyl (1 to 2) substituted phenyl group at the 2-position or the 4-position, and the hydroxyl (1 to 2) substituted phenyl group at the 2-position or the 4-position or the 2-position and the 4-position. The keto and enol isomers are repeatedly converted to each other, and the two isomers coexist in an equilibrium state. In particular, a triazine compound having a molecular weight in the range of 250 to 700 is preferred, and as the enol type, a hydroxyphenyl-1,3,5-triazine derivative is particularly preferred. Inside the heat shielding layer, the triazine tautomers are repeatedly converted to the enol isomer (Ib) [Chemical formula 3] and the keto isomer (IIb) [Chemical formula 4] by excitation with solar light (ultraviolet light) energy, and the ultraviolet light energy is converted into molecular vibration energy of the conversion and released outside the system, thereby attenuating the deterioration damage caused by ultraviolet light. The ultraviolet light attenuation effect of the thermoplastic resin layer greatly works to extend the service life of the heat shielding composite sheet of the present invention. Specifically, the alkyloxy group is a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a tert-butyl group, a pentyloxy group, etc. In addition, the triazine tautomers can be used by grafting them onto the side chains of an acrylic polymer.
R ₁ is a hydroxyl group and/or an alkyloxy group, R ₂ and R ₃ are alkyl-substituted phenyl groups and/or hydroxyl-substituted phenyl groups.
R ₁ is a hydroxyl group and/or an alkyloxy group, R ₂ and R ₃ are alkyl-substituted phenyl groups and/or hydroxyl-substituted phenyl groups.

Diphenyl ketone tautomers exist in enol and keto forms, and the enol isomer (Ic) is an organic compound [Chemical Formula 5] having a main skeleton in which two benzene rings, each having a hydroxyl group (1 to 2), a ketone group (0), and an alkyloxy group (0 to 1), are linked by a C=O bond. Specific examples include a structure having a hydroxyl group at the 2-position of the benzene ring, a structure having hydroxyl groups at the 2- and 4-positions of the benzene ring, and a structure having a hydroxyl group at the 2-position and an alkyloxy group at the 4-position of the benzene ring. Also, the keto-type isomer (IIc) is an organic compound [Chemical Formula 6] having a main skeleton in which one benzene ring (A) having a hydroxyl group (0 to 1 group), a ketone group (1 group), and an alkyloxy group (0 to 1 group) and one benzene ring (B) having a hydroxyl group (1 to 2 groups), a ketone group (0 group), and an alkyloxy group (0 to 1 group) are linked by a C=O bond. Specific examples include a structure having a ketone group at the 2-position of the benzene ring (A), a structure having a ketone group at the 2-position and a hydroxyl group at the 4-position of the benzene ring (A), a structure having a ketone group at the 2-position and an alkyloxy group at the 4-position of the benzene ring (A), a structure having a hydroxyl group at the 2-position of the benzene ring (B), a structure having hydroxyl groups at the 2-position and the 4-position of the benzene ring (B), and a structure having a hydroxyl group at the 2-position and an alkyloxy group at the 4-position of the benzene ring (B). A diphenyl ketone compound having a molecular weight of 200 to 400, in which both the keto and enol isomers are repeatedly converted to each other and coexist in an equilibrium state, is preferably a hydroxydiphenyl ketone derivative, particularly an enol type. Inside the thermoplastic resin layer, the diphenyl ketone tautomer is repeatedly converted to the enol isomer (Ic) [Chemical formula 5] and the keto isomer (IIc) [Chemical formula 6] by the energy of sunlight (ultraviolet rays), and the ultraviolet energy is converted into molecular vibration energy of the conversion and released outside the system, thereby attenuating the deterioration damage caused by ultraviolet rays. The ultraviolet attenuation effect of the thermoplastic resin layer greatly works to extend the service life of the heat-shielding composite sheet of the present invention. Specifically, the alkyloxy group is a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a tert-butyl group, a pentyloxy group, etc. In addition, the diphenyl ketone tautomer can be used by grafting it to the side chain of an acrylic polymer.
R ₁ and R ₂ each represent a hydroxyl group and/or an alkyloxy group.
R ₁ and R ₂ each represent a hydroxyl group and/or an alkyloxy group.

The amount of the N-OR type hindered amine contained in the thermoplastic resin layer as an essential component is 0.1 to 10 parts by mass, and preferably 0.2 to 5 parts by mass, per 100 parts by mass of the thermoplastic resin constituting the thermoplastic resin layer, and is particularly effective in improving the light resistance stability of the vinyl chloride resin. The N-OR type hindered amine compound used has at least one, preferably two, or preferably four, or preferably six hindered amine structures in its molecular structure, and the N-position of the hindered amine structure shown in the following formula [Chemical Formula 7] has one or more substituents selected from an alkoxy group having 2 to 18 carbon atoms or a cycloalkoxy group having 5 to 12 carbon atoms, and the molecular weight of the compound is 200 to 400 (one hindered amine structure), 400 to 700 (2 to 3 hindered amine structures), 700 to 1000 (4 to 5 hindered amine structures), or 1000 to 2500 (6 or more hindered amine structures), which are excellent in terms of residual retention in the thermoplastic resin layer and are therefore preferred.
In the above [Chemical Formula 7], R1, R2, R3 and R4 are each independently a) a hydrogen atom, b) a straight chain alkyl group or branched alkyl group having 1 to 20 carbon atoms, c) the alkyl group of b) containing one or more -O-, -S-, -SO-, -SO ₂ -, -CO-, -COO-, -OCO-, -CONR-, -NRCO- or -NR-, d) an alkenyl group having 3 to 20 carbon atoms, e) an aryl group having 6 to 10 carbon atoms, f) an aryl group having 1 to 3 substituents selected from an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, and a phenylalkyl group having 7 to 15 carbon atoms, and the like. However, it is particularly preferred that the N-OR type hindered amine compound used in the heat shielding composite sheet of the present invention has an embodiment in which R ₁ , R ₂ , R ₃ and R ₄ are all hydrogen or all methyl groups. _R5 is i) an alkyl group having 2 to 18 carbon atoms, i.e., one in which the N-position of the hindered amine structure is substituted with an alkoxy group having 2 to 18 carbon atoms, particularly preferably an alkoxy group having 6 to 12 carbon atoms, or ii) a cycloalkyl group having 5 to 12 carbon atoms, i.e., one in which the N-position of the hindered amine structure is substituted with a cycloalkoxy group having 5 to 12 carbon atoms, preferably a cycloalkoxy group having 5, 6 or 8 carbon atoms, particularly preferably a cyclohexyloxy group.

Specific examples of these N-OR type hindered amine compounds are compounds having at least one substituent R ₅ selected from an alkyl group having 2 to 18 carbon atoms or a cycloalkyl group having 5 to 12 carbon atoms at the N-position of the hindered amine structure [Chemical Formula ₇ ], and these _include bis(1-undecaoxy-2,2,6,6-tetramethylpiperidin-4-yl)carbonate, a polycondensate of 4,4'-hexamethylene-bis(N-OR ₅ -2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-tert-octylamino-s-triazine; a polycondensate of 1-(2-hydroxyethyl)-N-OR ₅ -2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid: N,N',N'',N'''-tetrakis[4,6-bis(butyl-(N-OR ₅ -2,2,6,6-tetramethylpiperidin-4-yl)amino)-s-triazin-2-yl]-1,10-diamino-4,7-diazadecane; polycondensate of 4,4'-hexamethylene-bis(N-OR ₅ -2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-morpholino-s-triazine; poly[methyl 3-(N-OR ₅ -2,2,6,6-tetramethylpiperidin-4-yloxy)propyl]siloxane; bis(N-OR ₅ -2,2,6,6-tetramethylpiperidin-4-yl)cyclohexylenedioxydimethylmalonate; bis(N-OR ₅ -2,2,6,6-tetramethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate; bis(N-OR ₅ -2,2,6,6-tetramethyl-4-piperidyl)sebacate; 1,3,5-tris{N-cyclohexyl-N-[2-(N-OR ₅ -2,2,6,6-tetramethylpiperazin-3-one-4-yl)ethyl]amino-s-triazine; polycondensates of 4,4'-hexamethylene-bis(N-OR ₅ -2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-cyclohexylamino-s-triazine; and poly{N-[4,6-bis(butyl-(N-OR ₅ -2,2,6,6-tetramethylpiperidin-4-yl)amino)-s-triazin-2-yl]-1,4,7-triazanonane}-ω-N″-[4,6-bis(butyl-(N—OR ₅ -2,2,6,6-tetramethylpiperidin-4-yl)amino)-s-triazin-2-yl]amine, and the like can be exemplified.

The light stabilization by N-OR type hindered amines begins when the N-OR type hindered amines are oxidized by oxygen, ultraviolet light, peroxides, etc. and converted into nitroxy radicals (NO.), which then capture alkyl radicals (R.) generated by the photodegradation of the thermoplastic resin in the thermoplastic resin layer and convert them into amino ethers (NOR). The N-OR part then captures the peroxide radicals (ROO.) generated by the reaction of the alkyl radicals (R.) with oxygen in the air, which are then detoxified into alcohols and ketones and released, and the N-OR part itself returns to the original nitroxy radical (N-O.). By repeating this cycle in nanoseconds, it is possible to suppress the chain reaction of bond cleavage in the thermoplastic resin caused by the attack of harmful radicals. This radical detoxification cycle is the same for NH type hindered amines and N-alkyl type hindered amines, but N-OR type hindered amines are the most preferable for stabilizing the light resistance of vinyl chloride resins. In the present invention, it is also possible to use an N-OR type hindered amine in combination with an NH type hindered amine, or an N-OR type hindered amine in combination with an N-alkyl type hindered amine, with the combination ratio being 10:1 to 10:10, and particularly preferably 10:2 to 10:5. If the ratio of N-OR type hindered amine used in a blend system mainly composed of vinyl chloride resin is low, a significant improvement in light resistance may not be obtained. In addition, the combination ratio of the essential component keto/enol type tautomer and N-OR type hindered amine is preferably 10:1 to 10:5, and particularly preferably 10:3 to 10:4. If the ratio of keto/enol type tautomer used is low, a significant improvement in light resistance may not be obtained.

In addition, as an embodiment of the heat-shielding composite sheet of the present invention, the thermoplastic resin layer may further contain zinc oxide or a mixture of titanium oxide and zinc oxide as an ultraviolet shielding material. The zinc oxide and titanium oxide preferably have a primary average particle diameter of 0.3 μm or less and a coating layer on the particle surface. This allows zinc oxide or zinc oxide and titanium oxide particles with a primary average particle diameter of 0.3 μm or less (0.1 μm to 0.3 μm) to enter the gaps between the surface-treated titanium oxide particles with a primary average particle diameter of 0.4 to 4.0 μm contained in the thermoplastic resin layer, and the surface area of the zinc oxide and titanium oxide particles with such particle diameters is increased, scattering ultraviolet rays that penetrate into the thermoplastic resin layer and effectively shielding the transmission of ultraviolet rays. This ultraviolet shielding effect further improves the light resistance of the thermoplastic resin layer through the synergistic effect with the keto/enol tautomer and the N-OR hindered amine. In particular, zinc oxide has an excellent UVA (ultraviolet A wave) shielding effect, and titanium oxide has an excellent UVB (ultraviolet B wave) shielding effect, so it is preferable to use a mixture of titanium oxide and zinc oxide with a mass ratio of 10:6 to 6:10, and particularly a mixture of 10:10. The zinc oxide and titanium oxide particles used in the present invention are preferably those whose photocatalytic activity has been sealed by surface treatment. If the surface treatment is not performed, the thermoplastic resin of the thermoplastic resin layer will be deteriorated by radical attack due to the photocatalytic activity. The surface treatment performed on the zinc oxide particles and titanium oxide particles is for preventing aggregation, improving dispersibility, and sealing the photocatalytic activity of the titanium oxide particles, and is a surface treatment with one or more metal oxides selected from aluminum oxide, zirconium oxide, and silicon oxide (7 options). In addition to the surface treatment with these metal oxides, a multi-layer surface treatment may be used in which a single layer of one type or two layers of two types of silane coupling agents, saturated alkyl titanates, saturated alkyl silanes, polysiloxanes, acrylic silicones, and metal soaps (metal salts of long-chain fatty acids such as stearic acid and lauric acid and metals such as barium and zinc) are applied as a further surface treatment. Such surface treatments further improve the prevention of aggregation and dispersibility. The amount of surface-treated zinc oxide and/or surface-treated titanium oxide particles with a primary average particle size of 0.3 μm or less (0.1 μm to 0.3 μm) contained in the thermoplastic resin layer is 3 to 20 parts by mass, preferably 5 to 12 parts by mass, per 100 parts by mass of the thermoplastic resin.

In addition, as an embodiment of the heat-shielding composite sheet of the present invention, a thin film layer containing zinc oxide or a mixture of titanium oxide and zinc oxide and having a layer thickness of 3 to 20 μm can be formed on a thermoplastic resin layer. The zinc oxide and titanium oxide have a primary average particle size of 10 to 50 nm and a coating layer on the particle surface, and the content of zinc oxide or a mixture of titanium oxide and zinc oxide in the thin film layer is preferably 10 to 50 mass %, particularly preferably 15 to 35 mass %. Such ultrafine zinc oxide and titanium oxide are far from the particle size suitable for white pigments, so that the hiding power is reduced and the thin film layer becomes transparent, and at the same time, the surface area (specific surface area) per unit mass is increased due to the ultrafine particles, so that the UVA (ultraviolet A wave) shielding effect of zinc oxide and the UVB (ultraviolet B wave) shielding effect of titanium oxide are dramatically improved. It is preferable to use ultrafine zinc oxide and ultrafine titanium oxide in a mixture with a mass ratio of 10:6 to 6:10, particularly a mixture with a mass ratio of 10:10. For the same reason, it is preferable that the photocatalytic activity of ultrafine particles of zinc oxide and titanium oxide is blocked by the surface treatment described in paragraph [0026]. The thin film layer is mainly composed of an organosilicate compound or a sol-gel condensate of a silanol group-containing organic silane compound. The organosilicate compound is a tetrafunctional hydrolyzable silane compound represented by the chemical formula Si _n O _n-1 (OR) _{2 (n+1)} , in which R is an alkyl group having 1 to 10 carbon atoms (particularly a lower alkyl group having 1 to 3 carbon atoms) or an aryl group (particularly a phenyl group), and n is the degree of polymerization (n-mer) representing the number of condensed molecules of the tetrafunctional hydrolyzable silane compound and is an integer of 1 or more. Examples of compounds in which n is 1 include tetramethoxysilane "Si(OCH ₃ ) ₄ ," tetraethoxysilane "Si(OC ₂ H ₅ ) ₄ ," tetrapropoxysilane "Si(OC ₃ H ₇ ) ₄ ," tetrabutoxysilane "Si(OC ₄ H ₉ ) ₄ ," tetraphenoxysilane "Si(OC ₆ H ₆ ) ₄ ," and dimethoxydiethoxysilane "Si(OCH ₃ ) ₂ (OC ₂ H ₅ ) ₂ ". Compounds with n of 2 or more are polymers formed by condensation of two or more molecules by the reaction between silanol groups formed by hydrolysis of a tetrafunctional hydrolyzable silane compound, and the degree of polymerization represented by n means the number of Si atoms contained in one molecule of the polymer. In the present invention, it is preferable to use a silanol group-containing silane compound obtained by hydrolysis of tetramethoxysilane or tetraethoxysilane having a degree of polymerization of 2 to 10, preferably 4 to 6, since the structure of the sol-gel condensate is finely densified. The concentration of the hydrolysis product of organosilicate contained in the coating liquid (water/alcohol) for forming the thin film layer is preferably in the range of 5 to 50 mass%, particularly 10 to 40 mass%. In addition, this coating liquid may contain cellulose nanofibers in an amount of 1 to 10 mass% relative to the concentration of the hydrolysis product of organosilicate in order to impart flexibility and bendability to the thin film layer. The cellulose nanofibers used are short fibers having an average aspect ratio (average fiber length/average fiber diameter) of 10 to 50, an average fiber diameter of 3 nm to 100 nm, and an average fiber length of 100 μm or less, particularly 300 nm to 500 nm, and these may be chemically modified with a silane coupling agent, a boric acid compound, a phosphoric acid compound, a silicic acid compound, or the like.

In addition, as an embodiment of the heat-shielding composite sheet of the present invention, a thin film layer mainly composed of an organosilicate compound or a sol-gel condensate of a silanol group-containing organic silane compound can be formed on a thermoplastic resin layer. This thin film layer preferably contains at least one photocatalytic metal oxide selected from titanium oxide, titanium peroxide, zinc oxide, tin oxide, strontium titanate, tungsten oxide, bismuth oxide, and iron oxide. This photocatalytic metal oxide preferably has an average particle size of 50 nm or less, particularly 20 nm or less, and with this particle size, the specific surface area becomes large and sufficient photocatalytic activity is exhibited, thereby decomposing oily soot and dust stains and allowing self-cleaning removal by rainfall. This allows the heat-shielding effect of the heat-shielding composite sheet of the present invention to be stably maintained for a long period of time. To form this thin film layer, a photocatalytic metal oxide in a sol state is preferably used, and is preferably contained in an amount of 10 to 50 mass% relative to the thin film layer. Metals and metal oxides such as Pt, Rh, _RuO2 , Nb, Cu, Sn, NiO, etc. can be added to these photocatalytic metal oxides as synergistic agents. The ultraviolet light received by the heat-shielding composite sheet of the present invention passes through the thin film layer and then through the thermoplastic resin layer, but in the thin film layer, a part of the ultraviolet energy passing through is consumed for activating the photocatalytic metal oxide, so that the ultraviolet energy reaching the thermoplastic resin layer located below is attenuated. Therefore, disposing the thin film layer on the thermoplastic resin layer protects the thermoplastic resin layer, and thus contributes to extending the service life of the heat-shielding composite sheet. Since the photocatalytic metal oxide has the function of decomposing organic matter by oxidation-reduction due to photocatalytic activity, the thin film layer is mainly composed of an organosilicate compound or a sol-gel condensate of a silanol group-containing organosilane compound, and improves the resistance of the thin film layer to abrasion load, enabling the heat-shielding composite sheet to be used for a long time. In addition, the thin film layer contains 1 to 10 mass % of a silane coupling agent (aminosilane, vinylsilane, epoxysilane, methacrylsilane, acrylicsilane, chlorosilane, mercaptosilane, isocyanurate silane, isocyanate silane, etc.), and the hydrolyzate of the silane coupling agent is bonded and interposed between the sol-gel condensate and the photocatalytic metal oxide, thereby further improving the bending resistance and resistance to abrasion load of the thin film layer. The thin film layer has a thickness of 3 to 15 μm, and the amount of photocatalytic metal oxide contained in the thin film layer is 10 to 50 mass %, preferably 5 to 35 mass %. In addition, self-cleaning is an effect in which organic residues such as dirt (soot, tar), mold, and algae decomposed by photocatalytic activity are washed away by rainfall, thereby restoring the appearance before the dirt and the like were attached. The thin film layer is mainly composed of the organosilicate compound described in paragraph [0027] or a sol-gel condensate of a silanol group-containing organosilane compound, and may contain 1 to 25 mass % of an inorganic colloid (silica sol, antimony sol, alumina sol, zirconia sol, etc.) relative to the concentration of the organosilicate hydrolysis product in order to further extend the abrasion resistance and durability of the thin film layer.

The thermoplastic resin layer of the heat-shielding composite sheet of the present invention may contain any additives as necessary. Additives that contribute to improving weather resistance include antioxidants (hindered phenols, phosphites, sulfur, vitamin E, etc.), matting agents such as silica, calcium silicate, magnesium silicate, and aluminum silicate, colorants such as organic pigments, inorganic pigments, aluminum luster pigments, pearl pigments, and dyes, antistatic agents such as surfactants, ionic liquids, conductive carbon, carbon nanotubes, and fullerenes, flame retardants such as sepiolite, montmorillonite, and smectite, abrasion resistance enhancers such as isocyanates, acrylates, epoxies, silane coupling agents, and silicone oils, and other antibacterial agents, antifungal agents, and antiviral agents. The thermoplastic resin layer can be obtained, for example, by melt-rolling (stretching) a soft polyvinyl chloride resin compound to a thickness of 0.1 mm to 1.0 mm using a calendar method or a T-die extrusion method. For example, a soft polyvinyl chloride resin paste sol can be coated or dipped, then heated to gel, forming a film with a thickness of 0.05 mm to 0.5 mm.

The fabric used in the heat-shielding composite sheet of the present invention is preferably a woven fabric, and contains one or more types of yarn selected from multifilament yarn, staple fiber spun yarn, and covering yarn, and is either 1) a woven fabric made of warp yarn and weft yarn, or 2) a triaxial fabric made of warp yarn and upper left/upper right bias yarn, or 3) a quadriaxial fabric made of warp yarn, weft yarn, and upper left/upper right bias yarn. In particular, plain weave fabrics made of warp and weft threads, twill fabrics (regular twill weaves such as 2x2, 3x3, and 4x4, and irregular twill weaves such as 3x2, 4x2, 4x3, 5x3, 2x3, 2x4, 3x4, and 3x5), twill fabrics (having a minimum structural unit of at least three warp and weft threads: 3-sheet twill, 4-sheet twill, 5-sheet twill, 6-sheet twill, etc.), satin fabrics (having a minimum structural unit of at least five warp and weft threads: regular twill with 2 jumps, 3 jumps, 4 jumps, 5 jumps, etc.), and other imitation gauze fabrics and twisted fabrics (sha fabrics, ro fabrics) can be used. In particular, when a triaxial or quadriaxial woven fabric is used, the intersections between the threads become complex and dense, and the network that spreads in the multiaxial direction increases the propagation of external stress such as bending and fluttering applied to the heat-shielding composite sheet, dispersing and deflecting the stress over a wide area, mitigating damage and at the same time increasing resistance to external forces such as tearing. The fabric weight is 100 to 500 g/ ^m2 , and the porosity (the total occupancy rate of the space generated by the entanglement of the threads) is preferably about 6 to 25% for tarpaulin and about 0 to 10% for canvas. These fabrics can also be used after undergoing known dyeing and finishing processes such as scouring, bleaching, dyeing, softening, water repellency, mildew resistance, flame resistance, and calendaring. Tarpaulin is a form in which a thermoplastic resin film is laminated on both sides of a fabric, and canvas is a form in which a liquid thermoplastic resin composition is impregnated and coated on both sides of a fabric and then coated with the composition.

The yarns constituting the woven fabric (cloth) can be any type of fiber, including synthetic fibers, natural fibers, semi-synthetic fibers, inorganic fibers, and mixed fibers consisting of two or more of these. Generally, however, one or more types of yarns selected from 1) multifilament yarns, 2) staple spun yarns, and 3) and covering yarns made of synthetic fibers such as polypropylene fibers, polyethylene fibers, polyvinyl alcohol fibers, polyester (polyethylene terephthalate: PET, polybutylene terephthalate: PBT, polynaphthalene terephthalate: PNT, etc.) fibers, nylon fibers, and mixed fibers (mixed and twisted) of these fibers can be used. The multifilament yarn may be a long fiber spun bundle (50 to 500 filament bundle) obtained by extruding a thermoplastic resin such as nylon or polyester from a spinneret and spinning the long fiber raw yarn 3 to 5 times, which is either untwisted or twisted 10 to 200 times/m to obtain a yarn having a fineness of 125 to 2000 denier (139 to 2222 dtex). These multifilament yarns include bulky processed yarns such as taslan yarn and woolly yarn. The short fiber spun yarn is a roving (coarse yarn) obtained by stretching a sliver by opening and kneading a long fiber spun bundle (which may be stretched) obtained by extruding a thermoplastic resin such as nylon or polyester from a spinneret and spinning the long fiber spun bundle (which may be stretched) into a length of about 3.8 to 5.8 mm, which is then drafted and twisted to a predetermined count to produce a tow spinning. Examples of twisted yarns include single yarns or two single yarns that are aligned and twisted in an S (right) or Z (left) direction, and two-ply yarns that are aligned and twisted in a first twist, each of which is a single yarn or two single yarns that are aligned and twisted in a second direction. The number of twists of these twisted yarns is about 200 to 2000 times/m. Examples of covered yarns include covered yarns in which the short fibers are wrapped around the outer circumference of the multifilament yarn bundle, and in this application, core-sheath composite yarns are also included in the covered yarns.

In particular, special fabrics (woven materials) can be used to improve the tensile breaking strength, tear strength, explosion-proof pressure resistance, heat resistance, and fire resistance of the heat-shielding composite sheet of the present invention. For this fabric, a fabric design based mainly on multifilament yarns such as fluororesin fibers, wholly aromatic polyester fibers, and wholly aromatic polyamide fibers, or a combined design with yarns made of the above-mentioned general-purpose synthetic fibers (insertion of a ripstop structure) is suitable. In addition, for applications as non-flammable materials certified by the Minister of Land, Infrastructure, Transport and Tourism (non-flammable membrane materials for tent structures), fabrics based mainly on inorganic multifilament yarns such as glass fibers, silica fibers, alumina fibers, silica alumina fibers, carbon fibers, and mixed fibers thereof (mixed and twisted). In particular, in order to dramatically improve the tensile breaking strength, tear (cut) strength, explosion-proof pressure resistance, heat resistance, and fire resistance, it is suitable to design a textile mainly containing yarns (multifilament yarns, staple spun yarns, covered yarns) made of one or more aromatic heterocyclic polymer fibers selected from the group consisting of polybenzimidazole (PBI)-based, polybenzoxazole (PBO)-based, polybenzothiazole (PBT)-based, and copolymers thereof (benzimidazole-benzoxazole copolymers, benzimidazole-benzothiazole copolymers, benzoxazole-benzothiazole copolymers, benzimidazole-benzoxazole-benzothiazole copolymers, and the above copolymers containing an aromatic polyamide component), or to use the textile in combination with yarns made of the above general-purpose fibers (insertion of a ripstop structure). The ripstop structure is, for example, a plain weave fabric having polyester fiber yarns as warp and weft, in which yarns made of aromatic heterocyclic polymer fibers are regularly or randomly arranged at arbitrary positions of the warp and weft, and is suitable for a woven fabric, triaxial fabric, or quadraxial fabric that forms a lattice pattern (or irregular lattice pattern) in appearance. Specifically, in the yarn arrangement 1, 2, 3, 4, 5...n (n is an integer) of warp and weft groups, aromatic heterocyclic polymer fiber yarns are inserted every multiple of 10 (10, 20, 30...) to form a lattice pattern. In addition, in a four-axis woven fabric, any or all of the warp, weft, upper left bias yarn, and upper right bias yarn can be aromatic heterocyclic polymer fiber yarns. Specifically, the warp and weft can be aromatic heterocyclic polymer fiber yarns, and the upper left bias yarn and upper right bias yarn can be other fiber yarns, or the upper left bias yarn and upper right bias yarn can be other aromatic heterocyclic polymer fiber yarns, and the warp and weft can be other fiber yarns.

The tarpaulin embodiment of the heat-shielding composite sheet of the present invention can be a film (sheet) having a thickness of 0.1 mm to 1.0 mm, particularly 0.15 mm to 0.3 mm, which is obtained by hot kneading a thermoplastic resin composition (particularly preferably vinyl chloride resin/plasticizer, etc.) and melt rolling it by a calendar method or a T-die extrusion method. The resin processing of the woven fabric is performed using a laminator having one or two continuous heat roll/rubber roll compression units, a cooling roll unit, and a winding unit, and the resulting resin-processed woven fabric is hot melt-pressed by a single pass or two passes through the laminator. Tarpaulin is produced by thermocompressing a film obtained by calendar molding onto both sides of an open-mesh fabric using a laminator, and the embodiment of "(thin film layer)/thermoplastic resin layer/fabric (multifilament yarn)/thermoplastic resin layer" having a thickness of 0.5 to 1.5 mm and a mass of 500 to 2000 g/m can be used for membrane structures such as large tents (pavilions), circus tents, tent warehouses, membrane roofs (ceilings) for architectural spaces, and sunshade tents. The embodiment of canvas is a resin-processed fabric produced by impregnating and coating the surface and interior of a fabric with a solution-type thermoplastic resin composition (particularly preferably a paste of vinyl chloride resin/plasticizer, etc.) by a coating method such as knife coating or clearance coating, and then thermally drying or heat-gelling the fabric, or by immersing the fabric in a liquid bath filled with a solution-type thermoplastic resin composition (particularly preferably a vinyl chloride resin paste), and simultaneously pulling it out and squeezing it between a pair of rubber rolls, followed immediately by thermal drying or heat-gelling the fabric by a dipping method. The canvas is produced by a dipping method using a paste of polyvinyl chloride resin/plasticizer, etc., and a "(thin film layer)/thermoplastic resin layer/fabric (short fiber spun yarn)/thermoplastic resin layer" configuration with a thickness of 0.3 to 0.8 mm and a mass of 400 to 1000 g/m is suitable for applications such as truck canopies, truck bed sheets, rooftop tents, and sheet houses. In this paragraph, "(thin film layer)/" is an optional additional layer, but is the best configuration of the heat-shielding composite sheet of the present invention in terms of extending the service life.

Specific examples and performance of the heat shielding composite sheet of the present invention will be further described with reference to the following examples and comparative examples.
Accelerated weathering test
In accordance with JIS K5600-7-7 "General coating test methods (Part 7) Long-term durability of coating film," the discoloration of the sheet pieces was evaluated in terms of color difference ΔE (JIS Z8729) after 1000 hours, 2000 hours, 2500 hours, and 3000 hours of exposure to a weathering accelerator (based on the sheet pieces before acceleration).
ΔE = 0 to 2.9: 1 = No coloring allowed (compliant)
ΔE = 3 to 5.9: 2 = slight coloring is observed (compliant)
ΔE = 6 to 11.9: 3 = Discoloration to light brown (affects appearance)
ΔE=12-19.9: 4=discolored to brown (abnormal appearance)
ΔE=20~: 5=discolored to blackish brown (abnormal appearance)
<Flexural durability after accelerated weathering test>
Using sheet pieces exposed to the weathering accelerator for 1000 hours, 2000 hours, 2500 hours, and 3000 hours, a load of 1 kgf was applied to the sheet pieces by bending and kneading 500 times according to JIS L1096, Section 8.19 "Abrasion strength method B (Scott method)". The abrasion state of the thermoplastic resin layer and the presence or absence of cracks were evaluated by observing a 100x magnified image of the thermoplastic resin layer using a digital microscope (VHX-1000: Keyence Corporation).
1: No abnormality was found in the thermoplastic resin layer (compliant)
2: Minor cracks are observed in the thermoplastic resin layer, but no peeling or falling off is observed (Compliant)
3: Numerous cracks have occurred in the thermoplastic resin layer, affecting the appearance. 4: Numerous cracks have occurred in the thermoplastic resin layer, with cracked pieces peeling off and falling off. 5: The thermoplastic resin layer has deteriorated and fallen off, exposing the fabric. <Heat shielding rate (%)>
An infrared lamp simulating sunlight was used, and the rate at which the sheet material blocks radiant heat was taken as the heat shielding rate of the sheet, and was measured according to the following test method.
Test environment
An infrared lamp (100V, 125W, iR type: Iwasaki Electric Co., Ltd.) was attached to the center of the ceiling of a box-shaped structure with an inner diameter of 60cm high x 70cm wide x 70cm long, which has outside air temperature insulation and airtightness, and a base (8cm high) with a heat flow meter (Shothrm HFM heat flow meter: Showa Denko Co., Ltd.) sensor attached was configured in the center of the bottom surface inside the test box. At this time, the distance from the ceiling to the tip of the infrared lamp was 22cm, and the distance from the tip of the infrared lamp to the sensor was 30cm. (22cm + 30cm + 8cm = 60cm) The lamp was turned on in this environment, and the heat flow (kcal/ ^m2h ) was measured every minute, and the heat flow qn (kcal/ ^m2h ) after 30 minutes was measured. After the temperature inside the box-shaped structure was returned to 20°C, a test sheet piece (10 cm long x 10 cm wide) was placed on the base on which the sensor was attached, and a 3.5 mm thick transparent glass plate was placed on top of it. The lamp was then turned on and the heat flow (kcal/ ^m2h ) was measured every minute. The heat flow qc (kcal/ ^m2h ) after 30 minutes was measured, and the heat shielding rate pf (%) was calculated according to equation (2).
Heat shielding rate pf (%) = [(qn - qc) / qn] x 100 ... (1)
The higher the heat shielding rate pf (%), the higher the heat shielding effect is judged to be. (Light transmittance (%))
The measurement was performed in accordance with JIS Z8722 (condition g) using a spectrophotometer CM-36dGV manufactured by Konica Minolta, Inc.

[Example 1]
<Fabric (1)>
The warp and weft groups were made of 1000 denier (1111 dtex) polyethylene terephthalate (PET) fibers (192 filaments) and S-twisted 50 T/m of PET multifilament yarn, with the warp group having a weave of 16 threads per inch and the weft group having a weave of 16 threads per inch, forming a plain weave fabric. The mass of this fabric (1) was 150 g/ ^m2 , and the void ratio (total of open areas) was 14%.
<Tarpaulin>
This fabric (1) was used as a substrate, and on both sides thereof, a 0.2 mm-thick calendar-molded film made of the soft vinyl chloride resin composition shown in [Formulation 1] below was used as a front and back thermoplastic resin layer, and melt-laminated by thermocompression bonding with a laminator to obtain a tarpaulin (1) having a thickness of 0.7 mm and a mass of 830 g/ ^m2 .
[Formulation 1]: Soft polyvinyl chloride resin composition (compound)
Vinyl chloride resin (degree of polymerization 1300) 100 parts by weight Diisononyl phthalate (plasticizer: Mw 419) 55 parts by weight Tricresyl phosphate (flame retardant plasticizer) 10 parts by weight Epoxidized soybean oil (stabilizer and plasticizer) 5 parts by weight Barium/zinc composite stabilizer 2 parts by weight Antimony trioxide (flame retardant) 10 parts by weight Surface-treated titanium oxide particles (average primary particle size 1 μm) 10 parts by weight * Surface treatment with aluminum oxide (outermost layer stearic acid treatment)
Hindered phenol antioxidant 0.5 parts by weight Benzotriazole tautomer 3 parts by weight *As an enol type, in [Chemical formula 1], the 1st C of one benzene ring (5th tert-butyl group) with 2-hydroxyl group (1 group) / ketone group (0 groups) and the benzotriazole ring (no substituent)
Organic compound of MW267 formed by C-N bond with hydroxyl group (0)/2-ketone group (1) in [Chemical formula 2] as keto type, C-N bond between 1-C of one benzene ring (5-tert-butyl group) and benzotriazole ring (no substituent) (MW267)
*1st, 2nd, and 5th positions indicate the carbon positions of the benzene ring. N-OR type hindered amine 1 part by mass *Bis(1-undecaoxy-2,2,6,6-tetramethylpiperidin-4-yl)
Carbonate (MW 681)
In the formula 7, R ₁ to R ₄ are all methyl groups, and R 5 is an undecyl group (-C ₁₁ H ₂₃ ).

[Example 2]
A tarpaulin (2) having a thickness of 0.7 mm and a mass of 830 g/m2 was obtained in the same manner as in Example 1, except that [Blend 2] was used in which 3 parts by mass of the benzotriazole tautomer in [Blend 1] of Example ¹ was replaced with 3 parts by mass of a triazine tautomer.
*Triazine tautomers are organic compounds with MW367 in the enol form (chemical formula 3) consisting of the 1st C of each of the three benzene rings (butoxy group at 4th position) with 1 hydroxyl group at 2nd position/0 ketone group at 2nd position and the C-C bond at 2, 4, and 6th positions of the 1,3,5-triazine ring. *Keto form (chemical formula 4) consisting of the 1st C of each of the three benzene rings (butoxy group at 4th position) with 0 hydroxyl group/1 ketone group at 2nd position and the C-C bond at 2, 4, and 6th positions of the 1,3,5-triazine ring (MW367).
* The 1st, 2nd, and 4th positions represent the carbon positions of the benzene ring, the 2nd, 4th, and 6th positions of the triazine ring represent the carbon positions, and the 1st, 3rd, and 5th positions represent the nitrogen positions.

[Example 3]
A tarpaulin (3) having a thickness of 0.7 mm and a mass of 830 g/m2 was obtained in the same manner as in Example 1, except that [Blend 3] was used in which 3 parts by mass of the benzotriazole tautomer in [Blend 1] of Example ¹ was replaced with 3 parts by mass of a diphenyl ketone tautomer.
*Diphenyl ketone tautomers are organic compounds with MW296 in the enol form [Chemical formula 5], in which the 1st C of one benzene ring (no other substituents) with 2-hydroxyl group (1), ketone group (0), and 4-octoxy group (1) is bonded to the benzene ring (no other substituents) via a C=O. *In the keto form [Chemical formula 6], the 1st C of one benzene ring (no other substituents) with hydroxyl group (0), 2-ketone group (1), and 4-octoxy group (1) is bonded to the benzene ring (no other substituents) via a C=O (MW296).
*1st, 2nd, and 4th positions represent the carbon positions of the benzene ring.

[Example 4]
A tarpaulin (4) having a thickness of 0.7 mm and a mass of 833 g/m2 was obtained in the same manner as in Example 1, except that [Blend 4] was used in which 1 part by mass of titanium oxide particles (surface-treated with aluminum hydroxide/outermost layer-treated with stearic acid) having a primary average particle diameter of 0.2 μm and 1 part by mass of zinc oxide particles (surface-treated with aluminum hydroxide/outermost layer-treated with stearic acid) having a primary average particle diameter of 0.2 μm was added to [Blend 1] in Example ¹ .

[Example 5]
A tarpaulin (5) having a thickness of 0.7 mm and a mass of 833 g/m2 was obtained in the same manner as in Example 2, except that [Blend 5] was used in which 1 part by mass of titanium oxide particles (surface-treated with aluminum hydroxide/outermost layer-treated with stearic acid) having a primary average particle diameter of 0.2 μm and 1 part by mass of zinc oxide particles (surface-treated with aluminum hydroxide/outermost layer-treated with stearic acid) having a primary average particle diameter of 0.2 μm was added to [Blend 2] in Example ² .

[Example 6]
A tarpaulin (6) having a thickness of 0.7 mm and a mass of 833 g/m2 was obtained in the same manner as in Example 3, except that [Blend 6] was used in which 1 part by mass of titanium oxide particles (surface-treated with aluminum hydroxide/outermost layer-treated with stearic acid) having a primary average particle diameter of 0.2 μm and 1 part by mass of zinc oxide particles (surface-treated with aluminum hydroxide/outermost layer-treated with stearic acid) having a ^primary average particle diameter of 0.2 μm was added to [Blend 3] in Example 3.

[Example 7]
A tarpaulin (7) having a thickness of 0.7 mm and a mass of 835 g/m2 was obtained in the same manner as in Example 1, except that a thin film layer (1 to 3 μm) of a sol-gel condensate containing titanium oxide particles having a primary average particle size of 10 nm (surface treated with aluminum hydroxide/outermost layer treated with stearic acid) and zinc oxide particles having a primary average particle size of 10 nm (surface treated with aluminum hydroxide/outermost layer treated with stearic acid) in a 1:1 mass ratio was added to ^one surface of the tarpaulin (1) of Example 1. The thin film layer was formed by using a solution of [Blend 7] with a 120 mesh gravure roll coater.
[Formulation 7]: Thin film layer
Ethyl silicate (Si(OC ₂ H ₅ ) ₄ : 40% by mass in terms of SiO ₂ )
* _{Tetraethoxysilane} pentamer of [ _{Si5O4 ( OC2H5} ) ₁₂ ] 100 parts by weight Hydrolysis catalyst: 2% hydrochloric acid 5 parts by weight Titanium oxide (particle diameter 10 nm) 2 parts by weight Zinc oxide (particle diameter 10 nm) 2 parts by weight Vinyl silane coupling agent (vinyltrimethoxysilane) 5 parts by weight Boric acid ester modified cellulose nanofiber (2% aqueous solution) 100 parts by weight *A modified product in which an aqueous solution of 3% boric acid + 78% ethyl cellosolve reacts with the carboxymethyl groups of carboxymethylated cellulose nanofiber (the primary and secondary hydroxyl groups (2, 3, and 6 positions of cellulose) are carboxymethylated): fiber width 3-10 nm; fiber length 30
~100μm

[Example 8]
A tarpaulin (8) having a thickness of 0.7 mm and a mass of 835 g/m2 was obtained in the same manner as in Example 2, except that a thin film layer of the same sol-gel condensate as in Example 7 was added to one surface of the tarpaulin (2) of Example ² .

[Example 9]
A tarpaulin (9) having a thickness of 0.7 mm and a mass of 835 g/ ^m2 was obtained in the same manner as in Example 3, except that a thin film layer of the same sol-gel condensate as in Example 7 was added to one surface of the tarpaulin (3) of Example 3.

[Example 10]
A tarpaulin (10) having a thickness of 0.7 mm and a mass of 834 g/m2 was obtained in the same manner as in Example 1, except that a thin film layer (1 to 3 μm) of a sol-gel condensate containing photocatalytic titanium oxide (untreated) with a primary average particle size of ^{10 nm was added to one} surface of the tarpaulin (1) of Example 1. The thin film layer was formed by using a solution of [Blend 8] with a 120 mesh gravure roll coater.
[Formulation 8]: Thin film layer
Ethyl silicate (Si(OC ₂ H ₅ ) ₄ : 40% by mass in terms of SiO ₂ )
* _{Tetraethoxysilane} pentamer of [ _Si5O4 ( _{OC2H5 ) 12} ] 100 parts by weight Hydrolysis catalyst: 2% hydrochloric acid 5 parts by weight Photocatalytic titanium oxide sol 50 parts by weight *Nitric acid acid: Particle diameter 10 nm: 30% solids in ethanol solution Vinyl silane coupling agent (vinyltrimethoxysilane) 5 parts by weight Silica sol (particle diameter 12 nm: 30% solids in ethanol solution) 50 parts by weight

[Example 11]
A tarpaulin (11) having a thickness of 0.7 mm and a mass of 834 g/m2 was obtained in the same manner as in Example 2, except that a thin film layer of the same sol-gel condensate as in Example 10 was added to one surface of the tarpaulin (2) of Example ² .

[Example 12]
A tarpaulin (12) having a thickness of 0.7 mm and a mass of 834 g/ ^m2 was obtained in the same manner as in Example 3, except that a thin film layer of the same sol-gel condensate as in Example 10 was added to one surface of the tarpaulin (3) of Example 3.

The tarpaulins (1) to (3) of Examples 1 to 3, which are formed with a thermoplastic resin layer containing surface-treated titanium oxide particles (average primary particle size 1 μm), keto/enol tautomers, and N-OR hindered amine as essential components, are excellent in heat shielding properties and weather resistance, and in particular, the improved weather resistance (reduction of ultraviolet degradation) makes it possible to extend the service life, as revealed by comparison with the sheets obtained in Comparative Examples 1 to 3. In particular, the sheet of Comparative Example 1, which uses surface-treated titanium oxide particles (primary particle size 0.2 μm), has excellent weather resistance but does not provide a sufficient heat shielding effect, while the sheet of Comparative Example 2, which omits the keto/enol tautomers, has excellent heat shielding effects but does not provide sufficient weather resistance, and the sheet of Comparative Example 3, which omits the N-OR hindered amine, also has excellent heat shielding effects but does not provide sufficient weather resistance. Furthermore, the tarpaulins (4) to (6) of Examples 4 to 6, in which surface-treated titanium oxide particles having an average primary particle size of 0.2 μm and surface-treated zinc oxide particles having an average primary particle size of 0.2 μm were added in a 1:1 mass ratio to the thermoplastic resin layer of the heat-shielding composite sheets of Examples 1 to 3, showed improved ultraviolet shielding effect (ultraviolet-A and ultraviolet-B waves) in the thermoplastic resin layer, excellent heat shielding properties and weather resistance, and in particular, improved weather resistance (reduction of ultraviolet degradation) enabled further extension of the service life, as revealed by comparison with the sheets of Examples 1 to 3. Furthermore, the tarpaulins (7) to (9) of Examples 7 to 9, in which a thin film layer made of a sol-gel condensate containing surface-treated titanium oxide particles having an average primary particle size of 10 nm and surface-treated zinc oxide particles having an average primary particle size of 10 nm in a 1:1 mass ratio was added onto the thermoplastic resin layer of the heat-shielding composite sheets of Examples 1 to 3, showed an improved ultraviolet shielding effect (ultraviolet-A and ultraviolet-B waves) for the thermoplastic resin layer, excellent heat shielding properties and weather resistance, and in particular, improved weather resistance (reduction of ultraviolet degradation) enabled a further extension of the service life, as revealed by a comparison with the sheets of Examples 1 to 3. In addition, the tarpaulins (10) to (12) of Examples 10 to 12, which have a thin film layer of a sol-gel condensate containing photocatalytic titanium oxide with a primary average particle size of 10 nm added to the thermoplastic resin layer of the heat-shielding composite sheets of Examples 1 to 3, exhibit a self-cleaning effect in the thermoplastic resin layer, and are excellent in heat-shielding properties and weather resistance, and in particular, the improved stain resistance makes it possible to further extend the service life, as revealed by comparison with the sheets of Examples 1 to 3. As a result, the frequency of disposal (replacing and replacing the membrane structure) is reduced, reducing the amount of membrane material (tarpaulin) to be disposed of, and at the same time, the production volume of the membrane material (tarpaulin) is reduced, thereby reducing the consumption of petrochemical resources that cause carbon dioxide emissions and contributing to the conservation of the global environment.

[Comparative Example 1]
A tarpaulin (13) having a thickness of 0.7 mm and a mass of 830 g/m2 was obtained in the same manner as in Example 1, except that 10 parts by mass of the surface-treated titanium oxide particles (primary average particle diameter 1 μm) in the thermoplastic resin layer [blending 1] of Example 1 was replaced with 10 parts by mass of surface-treated titanium oxide particles (primary particle diameter ^0.2 μm). By omitting the use of the surface-treated titanium oxide particles having a primary average particle diameter of 1 μm, which have a high reflectivity in the near-infrared region (780 to 2500 nm), the heat insulation property of the tarpaulin (13) was inferior to that of the tarpaulin (1). However, the weather resistance was equivalent to that of the tarpaulin (1).

[Comparative Example 2]
A tarpaulin (14) having a thickness of 0.7 mm and a mass of 830 g/m2 was obtained in the same manner as in Example 1, except that 3 parts by mass of the benzotriazole-based tautomer was omitted from the thermoplastic resin layer [blending 1] of Example 1, and ¹ part by mass of the N-OR type hindered amine was changed to 3 parts by mass [blending 10] was used. By omitting the use of the tautomer, which is highly effective in converting and releasing ultraviolet energy into molecular vibration energy, the weather resistance of the tarpaulin (14) was inferior to that of the tarpaulin (1), and it was not durable for long-term use. However, the heat shielding property was equivalent to that of the tarpaulin (1).

[Comparative Example 3]
A tarpaulin (15) having a thickness of 0.7 mm and a mass of 830 g/m2 was obtained in the same manner as in Example 1, except that [blending 11] was used, which was obtained by omitting 1 part by mass of the N-OR ^type hindered amine from the thermoplastic resin layer [blending 1] of Example 1. By omitting the use of the N-OR type hindered amine, which is highly effective in inhibiting the chain progression of attacks by harmful radicals generated by damage from ultraviolet rays, the weather resistance of the tarpaulin (15) was inferior to that of the tarpaulin (1) and was not durable for long-term use. However, the heat insulation property was equivalent to that of the tarpaulin (1).

[Comparative Example 4]
A tarpaulin (16) having a thickness of 0.7 mm and a mass of 830 g/m 2 was obtained in the same manner as in Example 1, except that 1 part by mass of the N-OR type hindered amine in the thermoplastic resin layer [blending 1] of Example 1 was replaced with 1 part by mass of bis(2,2,6,6-tetramethyl- ⁴ -piperidyl)sebacate (MW481), which is an N-H type hindered amine, was used [blending 12]. By omitting the use of the N-OR type hindered amine, which is highly effective against vinyl chloride resin, and changing it to an N-H type hindered amine, the free chlorine radical (Cl.) generated from the vinyl chloride resin due to ultraviolet degradation inhibits the radical detoxification cycle of the N-H type hindered amine, making it impossible to obtain sufficient weather resistance, and it was not able to withstand long-term use like the tarpaulin (1) of Example 1, and the evaluation rank of the color difference ΔE after 3000 hours of accelerated weather resistance was "4", and the evaluation rank of the bending kneading was "3". However, the heat insulation property was 60.2%, which is the same as that of tarpaulin (1).

The present invention makes it possible to obtain a composite sheet (composite sheet of tarpaulin, canvas, etc.) for tent membrane structures with excellent lighting, heat shielding, and weather resistance, and by extending the service life of the membrane material (heat shielding composite sheet) for tent membrane structures, the frequency of disposal (i.e., replacement) is reduced, and the amount of membrane material to be disposed of is reduced. At the same time, the amount of membrane material produced is reduced, which reduces the amount of petrochemical resources used, and contributes to the conservation of the global environment by reducing carbon dioxide emissions. Specifically, this membrane material is ideal for long-term (10 to 15 years) tent structures such as indoor sports facilities, event pavilions, traveling circuses, planetariums, and tent warehouses, and can also be used for applications lasting less than 10 years, such as architectural protection (soundproofing) sheets, pergola shades (membrane ceilings), facade sheets, lift-up sheet shutters, partition sheets, truck canopies, outdoor waterproof sheets, and rooftop tents.

Claims (6)

A heat shielding composite sheet comprising a fabric and a thermoplastic resin layer laminated thereon, the thermoplastic resin layer containing at least surface-treated titanium oxide particles, a keto/enol tautomer, and an N-OR hindered amine, the surface-treated titanium oxide particles having an average primary particle size of 0.4 to 1.2 μm, the keto/enol tautomer being one or more selected from a benzotriazole tautomer, a triazine tautomer, and a diphenyl ketone tautomer, and further comprising a thin film layer containing zinc oxide or a mixture of titanium oxide and zinc oxide formed on the thermoplastic resin layer, the zinc oxide and titanium oxide having a coating layer on the particle surface and an average primary particle size of 10 to 50 nm. The heat shielding composite sheet according to claim 1, wherein the benzotriazole tautomers are an enol isomer (Ia) [Chemical formula 1] having a skeleton formed of a C-N bond between one benzene ring (which may have one or two types selected from an alkyl group, a branched alkyl group, and an alkyl-substituted benzyl group) having a hydroxyl group (1 to 2 groups)/ketone group (0 groups) and a benzotriazole ring (which may have a substituent); and a keto isomer (IIa) [Chemical formula 2] having a skeleton formed of a C-N bond between one benzene ring (which may have one or two types selected from an alkyl group, a branched alkyl group, and an alkyl-substituted benzyl group) having a hydroxyl group (0 to 1 groups)/ketone group (1 group) and a benzotriazole ring (which may have a substituent).
R is at least one selected from the group consisting of a hydroxyl group, an alkyl group, a branched alkyl group, and an alkyl-substituted benzyl group.
R is at least one selected from the group consisting of a hydroxyl group, an alkyl group, a branched alkyl group, and an alkyl-substituted benzyl group. The heat shielding composite sheet according to claim 1, wherein the triazine-based tautomers are an enol-type isomer (Ib) [Chemical formula 3] having a main skeleton of a C-C bond between 1 to 3 benzene rings (which may have an alkyloxy group) having 1 to 2 hydroxyl groups/0 ketone groups and a 1,3,5-triazine ring (which may have an alkyl-substituted phenyl group and/or a hydroxyl-substituted phenyl group), and a keto-type isomer (IIb) [Chemical formula 4] having a main skeleton of a C-C bond between 1 to 3 benzene rings (which may have an alkyloxy group) having 1 to 2 hydroxyl groups/ 1 ketone group and a 1,3,5-triazine ring (which may have an alkyl-substituted phenyl group and/or a hydroxyl-substituted phenyl group).
R ₁ is a hydroxyl group and/or an alkyloxy group, R ₂ and R ₃ are alkyl-substituted phenyl groups and/or hydroxyl-substituted phenyl groups.
R ₁ is a hydroxyl group and/or an alkyloxy group, R ₂ and R ₃ are alkyl-substituted phenyl groups and/or hydroxyl-substituted phenyl groups. The heat shielding composite sheet according to claim 1, wherein the diphenyl ketone tautomers are an enol type isomer (Ic) [Chemical formula 5] having a main skeleton in which two benzene rings of hydroxyl group (1 to 2 groups)/ketone group (0 groups)/alkyloxy group (0 to 1 group) are linked by a C=O bond, and a keto type isomer (IIc) [Chemical formula 6] having a main skeleton in which one benzene ring of hydroxyl group (0 to 1 groups)/ketone group (1 group)/alkyloxy group (0 to 1 group) and one benzene ring (which may have other substituents) of hydroxyl group (1 to 2 groups)/ketone group (0 groups)/alkyloxy group (0 to 1 group) are linked by a C=O bond.
R ₁ and R ₂ each represent a hydroxyl group and/or an alkyloxy group.
R ₁ and R ₂ each represent a hydroxyl group and/or an alkyloxy group. The heat shielding composite sheet according to any one of claims 1 to 4, wherein the N-OR type hindered amine has, at the N-position of the hindered amine structure, one or more substituents selected from an alkoxy group having 2 to 18 carbon atoms and a cycloalkoxy group having 5 to 12 carbon atoms , and is represented by the following [Chemical Formula 7] :
R ₁ , R ₂ , R ₃ and R ₄ each independently represent: a) a hydrogen atom; b) a linear or branched alkyl group having 1 to 20 carbon atoms; c) one or more -O-, -S-,
-SO-, -SO ₂ -, -CO-, -COO-, -OCO-, -CONR-,
the alkyl group of the above b) containing —NRCO— or —NR—;
e) an aryl group having 6 to 10 carbon atoms; f) an aryl group having 1 to 3 substituents selected from an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, and a phenylalkyl group having 7 to 15 carbon atoms. R ₅ is an alkyl group having 2 to 18 carbon atoms, or a cycloalkyl group having 5 to 12 carbon atoms. 2. The heat shielding composite sheet according to claim 1, wherein the thermoplastic resin layer further contains zinc oxide or a mixture of titanium oxide and zinc oxide, and the zinc oxide and titanium oxide have a coating layer on the particle surface and have an average primary particle size of 0.3 μm or less.