Heat shielding film, and method for manufacturing heat shielding film

Abstract

To provide a heat shielding film that has a heat shielding property and excellent processability, and is excellent in applicability to a base material having a complex shape, and a method for manufacturing the heat shielding film.SOLUTION: There is provided a heat shielding film, comprising: a first polyvinyl chloride film; and a second polyvinyl chloride film disposed on a back side of the first polyvinyl chloride film, wherein a L value of the first polyvinyl chloride film is 20.0 or less, a L value of the second polyvinyl chloride film is 60.0 or more, the first polyvinyl chloride film contains polyvinyl chloride, a plasticizer, and a pigment, the second polyvinyl chloride film contains polyvinyl chloride, a plasticizer, and a titanium-based pigment, a content of the plasticizer in the first and second polyvinyl chloride films is 5 pts.mass or more and 24 pts.mass or less based on 100 pts.mass of the polyvinyl chloride, and a value of solar reflectance in a wavelength range of 750nm to 1500nm is 30.0% or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a heat shielding film and a method for producing the heat shielding film. [Background technology]

[0002] Conventionally, heat shielding films and sheets that suppress the temperature rise of a substrate due to solar radiation by laminating them on the surface of the substrate have been studied. For example, Patent Document 1 discloses a synthetic resin sheet-like product having a surface layer (A) and a reflective layer (B) that receive solar radiation, the surface layer (A) is a dark-colored layer that has a solar absorptance of 90% or more in the wavelength range of S380 to 720 nm, a solar absorptance of less than 30% in the near-infrared region of 720 to 1500 nm, and a solar transmittance of 50% or more in the near-infrared region of 720 to 1500 nm, the reflective layer (B) is a layer that has a solar reflectance of 85% or more in the wavelength range of 380 to 1500 nm, and the solar reflectance of the sheet-like product obtained by laminating the surface layer (A) and the reflective layer (B) in the near-infrared region of 720 to 1500 nm is 70% or more. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2007 / 145083 Summary of the Invention [Problem to be solved by the invention]

[0004] Windows use a window frame (window sash) to hold the glass in place, and traditionally, window sashes have often been made of metal such as aluminum. In recent years, there has been a demand for window sashes with a high level of design, with desired colors and designs such as wood grain. When a specific color or pattern is to be applied to a window sash, a dark film such as a black film may be attached to the substrate so that the color of the substrate does not show through, and printing or the like may be performed on top of it. However, because window sashes are exposed to direct sunlight, there is a problem that the temperature of the substrate increases when a dark film is attached. In addition, there is also consideration of making window sashes out of resin, which is expected to improve recyclability and reduce costs because there is no need to separate the metal and the film.

[0005] The inventors have considered laminating a bright film such as a white film on the back side of a dark film, but when laminating the two films, the film may wrinkle or crack, so there is room for further consideration. There is also room for further consideration regarding the workability to the substrate. FIG. 5 is a perspective view explaining a window sash as an example of a substrate. As shown in FIG. 5, a window sash has a complex structure and includes a portion that bends 180 degrees, so it requires better workability than when it is attached to a flat surface.

[0006] The present invention has been made in consideration of the above-mentioned current situation, and aims to provide a heat-shielding film that has heat-shielding properties and excellent processability, and is excellent in terms of applicability to substrates having complex shapes, and a method for manufacturing the heat-shielding film. [Means for solving the problem]

[0007] (1) One embodiment of the present invention is a heat shielding film comprising a first polyvinyl chloride film and a second polyvinyl chloride film arranged on a back side of the first polyvinyl chloride film, wherein the first polyvinyl chloride film has an L value of 20.0 or less in an L*a*b* color space and the second polyvinyl chloride film has an L value of 60.0 or more in an L*a*b* color space, the first polyvinyl chloride film contains polyvinyl chloride, a plasticizer, and a pigment, the second polyvinyl chloride film contains polyvinyl chloride, a plasticizer, and a titanium-based pigment, the content of the plasticizer in the first polyvinyl chloride film and the second polyvinyl chloride film is 5 parts by mass or more and 24 parts by mass or less per 100 parts by mass of the polyvinyl chloride, and the solar reflectance in a wavelength region of 750 nm to 1500 nm is 30.0% or more.

[0008] (2) In one embodiment of the present invention, in addition to the configuration of (1) above, the pigment is a heat shielding film containing an organic pigment.

[0009] (3) In one embodiment of the present invention, in addition to the configuration described above in (1) or (2), at least one of the first polyvinyl chloride film and the second polyvinyl chloride film further contains a heat stabilizer.

[0010] (4) In one embodiment of the present invention, in addition to the configuration of (3) above, the heat stabilizer is a heat shielding film including an epoxy compound or a zinc-based heat stabilizer.

[0011] (5) An embodiment of the present invention is a heat shielding film having any one of the configurations (1) to (4) above, wherein the difference between the content of plasticizer contained in the first polyvinyl chloride film and the content of plasticizer contained in the second polyvinyl chloride film is 15 parts by mass or less.

[0012] (6) An embodiment of the present invention is a heat shielding film having any one of the configurations (1) to (5) above, wherein at least one of the first polyvinyl chloride film and the second polyvinyl chloride film further contains an ultraviolet absorbing agent.

[0013] (7) In one embodiment of the present invention, in addition to any one of the configurations (1) to (6) above, the heat-shielding film further comprises a top film on the side of the first polyvinyl chloride film opposite the second polyvinyl chloride film, the top film containing polyvinyl chloride and an ultraviolet absorber, the content of the ultraviolet absorber being 0.5 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the polyvinyl chloride.

[0014] (8) In one embodiment of the present invention, in addition to the configuration of (7) above, the top film further contains a plasticizer, and the plasticizer is a polyester-based plasticizer.

[0015] (9) One embodiment of the present invention is a heat shielding film having any one of the configurations (1) to (8) above, further comprising a design layer on the side of the first polyvinyl chloride film opposite the second polyvinyl chloride film.

[0016] (10) One embodiment of the present invention is a heat shielding film having the configurations (1) to (8) above, and further comprising a top film, a design layer, the first polyvinyl chloride film, and the second polyvinyl chloride film laminated in that order.

[0017] (11) Another embodiment of the present invention is a method for producing a heat shielding film according to any one of (1) to (10) above, comprising: a calendar molding step of forming the first polyvinyl chloride film and the second polyvinyl chloride film by calendar molding, respectively; and a lamination step of heating and bonding the first polyvinyl chloride film and the second polyvinyl chloride film together. Effect of the Invention

[0018] According to the present invention, it is possible to provide a heat shielding film that has heat shielding properties and excellent processability, and is excellent in applicability to substrates having complex shapes, and a method for producing the heat shielding film. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic cross-sectional view of a heat shielding film having a first PVC film and a second PVC film in this order. [Diagram 2] FIG. 2 is a schematic cross-sectional view of a heat shielding film having a top film, a first PVC film, and a second PVC film in this order. [Diagram 3] FIG. 2 is a schematic cross-sectional view of a heat shielding film having a design layer, a first PVC film, and a second PVC film in this order. [Figure 4] FIG. 1 is a schematic cross-sectional view of a heat shielding film having a top film, a design layer, a first PVC film, and a second PVC film in this order. [Diagram 5] FIG. 1 is a perspective view illustrating a window sash as an example of a base material. [Figure 6] 1 is a schematic cross-sectional view of a decorated molded product including a heat shielding film and a substrate according to an embodiment. [Figure 7] FIG. 2 is an explanatory diagram illustrating a method for measuring the warpage of a film. [Figure 8] 8 is a schematic cross-sectional view taken along line X1-X2 in FIG. 7. [Figure 9] FIG. 2 is an explanatory diagram illustrating a method for measuring the width reduction of a film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] [Heat-shielding film] One embodiment of the present invention is a heat shielding film comprising a first polyvinyl chloride film and a second polyvinyl chloride film arranged on a back side of the first polyvinyl chloride film, wherein the first polyvinyl chloride film has an L value of 20.0 or less in an L*a*b* color space and the second polyvinyl chloride film has an L value of 60.0 or more in an L*a*b* color space, the first polyvinyl chloride film contains polyvinyl chloride, a plasticizer, and a pigment, the second polyvinyl chloride film contains polyvinyl chloride, a plasticizer, and a titanium-based pigment, the content of the plasticizer in the first polyvinyl chloride film and the second polyvinyl chloride film is 5 parts by mass or more and 24 parts by mass or less per 100 parts by mass of the polyvinyl chloride, and the solar reflectance in a wavelength region of 750 nm to 1500 nm is 30.0% or more.

[0021] Figures 1 to 4 are all schematic cross-sectional views of a heat barrier film according to an embodiment. Figure 1 is a schematic cross-sectional view of a heat barrier film having a first PVC film and a second PVC film in this order. As shown in Figure 1, the heat barrier film 10 includes a first polyvinyl chloride film (hereinafter, first PVC film) 1 and a second polyvinyl chloride film (hereinafter, second PVC film) 2 disposed on the back surface side of the first PVC film 1.

[0022] The L value (hereinafter simply referred to as L value) in the L*a*b* color space of the first PVC film is 20.0 or less, the L value of the second PVC film is 60.0 or more, and the solar reflectance of the heat shielding film in the wavelength region of 750 nm to 1500 nm is 30.0% or more. By disposing a dark PVC film with low brightness on the front side and disposing a high brightness PVC film containing a titanium-based pigment on the back side thereof, and setting the solar reflectance in the wavelength region of 750 nm to 1500 nm to 30.0% or more, it is possible to obtain excellent heat shielding properties while preventing the substrate from being seen through when the film is attached to a substrate. The front side refers to the viewer side in the usage mode, and the back side refers to the opposite side of the front side.

[0023] If the L value of the first PVC film exceeds 20.0, the shielding property is reduced, and the color of the second PVC film underneath is visible. If the L value of the second PVC film is less than 60.0, the heat shielding property may be reduced. If the L value of the first PVC film is 20.0 or less and the L value of the second PVC film is 60.0 or more, sufficient heat shielding property cannot be obtained, and excellent heat shielding property can be obtained by making the solar reflectance (750 nm to 1500 nm) of the heat shielding film 30.0% or more. The L value of the first PVC film is preferably 15 or less. The L value of the second PVC film is preferably 70 or more, more preferably 80 or more, and even more preferably 90 or more. The solar reflectance (750 nm to 1500 nm) of the heat shielding film is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more.

[0024] The L value represents the lightness in the L*a*b* color space, and can be measured using a spectrophotometer "SE6000" manufactured by Nippon Denshoku Kogyo Co., Ltd.

[0025] The solar reflectance is calculated by measuring the spectral reflectance from 300 to 2500 nm in accordance with the method of JIS K 5602:2008 "Method of determining the solar reflectance of coating film" and multiplying the measured spectral reflectance by the weighting coefficient shown in "Table 1 - Weighting coefficient of standard solar light" of JIS K 5602. Spectral reflectance can be measured using the SolidSpec-3700 ultraviolet / visible / near infrared spectrophotometer manufactured by Shimadzu Corporation. The lower the solar reflectance from 720 to 1500 nm, the higher the heat shielding property.

[0026] The solar reflectance in the range of 750 nm to 1500 nm can be adjusted by the type and amount of pigment added to the first and second PVC films, the thickness of the film, and the like.

[0027] The first PVC film contains polyvinyl chloride, a plasticizer, and a pigment.

[0028] Examples of the polyvinyl chloride include homopolymers of vinyl chloride and copolymers of vinyl chloride and other monomers copolymerizable with vinyl chloride. Examples of the other copolymerizable monomers include vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene, and styrene; alkyl (meth)acrylate esters such as methyl (meth)acrylate, ethyl (meth)acrylate, and methyl (meth)acrylate; maleic acid diesters such as dibutyl maleate and diethyl maleate; fumaric acid diesters such as dibutyl fumarate and diethyl fumarate; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinylidene chloride and vinyl bromide; and vinyl ethers such as methyl vinyl ether and ethyl vinyl ether. These may be used alone or in combination of two or more. In this specification, "(meth)acrylic acid" refers to "at least one of acrylic acid and methacrylic acid".

[0029] The content of the other copolymerizable monomer in the copolymer is usually 50% by mass or less, and preferably 10% by mass or less. Among the polyvinyl chlorides, a homopolymer of vinyl chloride is preferred from the viewpoint of excellent dimensional stability.

[0030] The average degree of polymerization of the polyvinyl chloride is preferably 800 to 1300. In the present invention, the average degree of polymerization of the polyvinyl chloride means the average degree of polymerization measured in accordance with JIS K 6721 "Testing methods for vinyl chloride resins." If the average degree of polymerization exceeds 1300, the elongation of the polyvinyl chloride film may be insufficient.

[0031] The plasticizer is an additive that imparts flexibility to the polyvinyl chloride film, and examples of the plasticizer include phthalic acid plasticizers and polyester plasticizers.

[0032] Examples of the phthalic acid plasticizer include di-2-ethylhexyl phthalate (DOP), dibutyl phthalate, dinonyl phthalate, diundecyl phthalate (DUP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), bis(2-ethylhexyl) terephthalate (DOTP), etc. Among these, in consideration of the impact on the environment, DUP, DINP, and DIDP are more preferable, and DUP is even more preferable because of its excellent weather resistance.

[0033] Examples of the polyester plasticizer include aliphatic ester compounds and alicyclic ester compounds. Examples of the aliphatic ester compounds (non-cyclic aliphatic esters) include adipic acid esters and polyesters in which adipic acid and polyalcohol are bonded. Specific examples of the aliphatic ester compounds include Adeka Cizer (registered trademark) PN-7535 and Adeka Cizer PN-7160 manufactured by ADEKA. Examples of the alicyclic ester compounds include cyclohexane-based carboxylates. Specific examples of the alicyclic ester compounds include HEXAMOLL (registered trademark) DINCH manufactured by BASF. The HEXAMOLL DINCH is a plasticizer containing di-isononyl-cyclohexane-dicarboxylate.

[0034] The pigment may be a suitable mixture of red, yellow, green, blue, and other pigments to express dark colors such as black and brown. The first PVC film preferably uses an organic pigment as the pigment, since this makes it easy to adjust the L value to 20.0 or less and to suppress an increase in solar reflectance (750 nm to 1500 nm).

[0035] Examples of the organic pigment include condensed polycyclic pigments and azo pigments. The condensed polycyclic pigments preferably include at least one of quinacridone pigments, anthraquinone pigments, indigo pigments, perinone pigments, perylene pigments, phthalone pigments, dioxazine pigments, isoindolinone pigments, ditopyrrolopyrrole pigments, and phthalocyanine pigments. Specific examples of the quinacridone pigments include unsubstituted quinacridone, quinacridone red, quinacridone magenta, quinacridone scarlet, and quinacridone maroon. The azo pigments preferably include at least one of β-naphthol, β-oxynaphthoic acid, naphthol AS, acetoacetate arylide, naphthalenesulfonic acid, and pyrazolone. These may be used alone or in combination of two or more.

[0036] The first PVC film may contain a titanium pigment (titanium oxide) and may have a gray color, for example, with an L value in the range of 20.0 or less.

[0037] The content of the pigment in the first PVC film is preferably 5 parts by mass or more and 50 parts by mass or less, and more preferably 10 parts by mass or more, per 100 parts by mass of polyvinyl chloride. The first PVC film may contain carbon black, but the content of carbon black in the first PVC film is preferably 0.5 parts by mass or less, and more preferably does not contain carbon black, per 100 parts by mass of polyvinyl chloride.

[0038] The thickness of the first PVC film is preferably 50 μm or more and 300 μm or less, and more preferably 70 μm or more and 250 μm or less.

[0039] The second PVC film contains polyvinyl chloride, a plasticizer, and a titanium-based pigment. The polyvinyl chloride and the plasticizer may be the same as those exemplified for the first PVC film.

[0040] The content of the titanium-based pigment in the second PVC film is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, per 100 parts by mass of the polyvinyl chloride. Even if 50 parts by mass or more is added, the solar reflectance (750 nm to 1500 nm) does not change significantly, so the content of the titanium-based pigment is preferably 50 parts by mass or less per 100 parts by mass of the polyvinyl chloride.

[0041] When the second PVC film contains only titanium-based pigment (titanium oxide), it becomes a white film. The second PVC film may contain a pigment other than the titanium-based pigment, for example, other pigments may be added to make it a gray film. The other pigment is preferably an organic pigment, and the organic pigments exemplified for the first PVC film may be used.

[0042] When the second PVC film contains a pigment other than a titanium-based pigment, the content of the titanium-based pigment is preferably 0.01 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the polyvinyl chloride. The content of carbon black contained in the second PVC film is preferably 0.5 parts by mass or less per 100 parts by mass of the polyvinyl chloride, and more preferably does not contain carbon black.

[0043] The content of the plasticizer in the first PVC film and the second PVC film is 5 parts by mass or more and 24 parts by mass or less per 100 parts by mass of polyvinyl chloride. By setting the content of the plasticizer in the first and second PVC films within the above range, it is possible to improve the processability, particularly in the lamination step in which the first and second PVC films are laminated and pressure-bonded, and to improve the workability when they are attached to a complex substrate.

[0044] If the content of the plasticizer is less than 5 parts by mass relative to 100 parts by mass of polyvinyl chloride, the first PVC film and the second PVC film become hard, and cracks are likely to occur when the first PVC film and the second PVC film are pressure-bonded by thermal lamination. On the other hand, if the content of the plasticizer exceeds 24 parts by mass relative to 100 parts by mass of polyvinyl chloride, the first PVC film and the second PVC film become too soft, and wrinkles or width reduction occurs during thermal lamination. Since PVC film is easily stretched, when it is molded into a film shape by calendar molding, it is stretched in the flow direction, but the dimension in the width direction shrinks, and the dimension specified by the customer may not be met. Such molding defects in which the dimension in the width direction is reduced are referred to as "width reduction" in this specification. From the viewpoint of obtaining better workability, the content of the plasticizer in the first PVC film and the second PVC film is more preferably 10 parts by mass or more and 20 parts by mass or less relative to 100 parts by mass of polyvinyl chloride.

[0045] If the hardness of the first PVC film and the second PVC film is significantly different, the first PVC film and the second PVC film may warp when they are laminated together. From the viewpoint of suppressing warping of the heat shielding film, the difference between the content of the plasticizer contained in the first PVC film and the content of the plasticizer contained in the second PVC film is preferably 15 parts by mass or less. The difference between the content of the plasticizer contained in the first PVC film and the second PVC film is more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less.

[0046] The thickness of the second PVC film is preferably 50 μm or more and 300 μm or less, and more preferably 70 μm or more and 250 μm or less.

[0047] From the viewpoint of suppressing warping of the heat shielding film, the difference between the thickness of the first PVC film and the thickness of the second PVC film is preferably 80 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. It is particularly preferable that the thickness of the first PVC film and the thickness of the second PVC film are the same, but when the thicknesses are different, the thickness of the thinner film is preferably 50% or more, more preferably 80% or more of the thickness of the thicker film.

[0048] The total thickness difference between the first PVC film and the second PVC film is, for example, preferably 100 μm or more and 500 μm or less, and more preferably 140 μm or more and 300 μm or less.

[0049] At least one of the first PVC film and the second PVC film preferably further contains a heat stabilizer. Since halogen-containing resins such as polyvinyl chloride are prone to thermal decomposition due to dehydrohalogenation during melt kneading or film formation, a heat stabilizer may be added to suppress deterioration during processing. An additive that suppresses deterioration or decomposition during kneading of a resin composition or during film formation is also called a stabilizer, and an additive that specifically suppresses thermal decomposition is also called a heat stabilizer.

[0050] The heat stabilizer is preferably an epoxy compound or a zinc-based heat stabilizer. The first PVC film and / or the second PVC film may use an epoxy compound and a zinc-based heat stabilizer in combination.

[0051] Although the epoxy compound does not have to be added, when it is added, the content of the epoxy compound is preferably 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of polyvinyl chloride. More preferably 5 parts by mass or less, more preferably 3 parts by mass or less. If the content of the epoxy compound is high, the number of defects such as holes and foreign matter contamination may increase in the calendar molding process, and bloom or bleed may occur in the weather resistance test. From the viewpoint of suppressing the occurrence of defects and / or bleed / bloom in the above film, the content of the epoxy compound is more preferably 5 parts by mass or less and more preferably 3 parts by mass or less per 100 parts by mass of polyvinyl chloride.

[0052] Examples of the epoxy compound include those having at least one epoxy group in the molecule, such as epoxidized soybean oil, glycidyl methacrylate (e.g., Metablen P-1901 manufactured by Mitsubishi Chemical Corporation), and glycidyl methacrylate (e.g., Marproof G-0150M manufactured by NOF Corporation).

[0053] Examples of the zinc-based heat stabilizer include barium-zinc-based (Ba-Zn-based) heat stabilizers, calcium-zinc-based (Ca-Zn-based) heat stabilizers, and mixtures of β-diketone and zinc powder.

[0054] Specific examples of the barium-zinc-based heat stabilizer include Adeka STAB (registered trademark) AC-258 manufactured by ADEKA CORPORATION, BND-928 manufactured by NI Chemitech Co., Ltd., and Adeka STAB AC-724 manufactured by ADEKA CORPORATION. Specific examples of calcium-zinc-based heat stabilizers include OW-5301 manufactured by Sakai Chemical Industry Co., Ltd. Examples of the mixture of β-diketone and zinc powder include Adeka STAB SP-83 manufactured by ADEKA CORPORATION.

[0055] The content of the zinc-based heat stabilizer is preferably 0.5 parts by mass or more and 8.0 parts by mass or less, and more preferably 1.5 parts by mass or more and 5.0 parts by mass or less, based on 100 parts by mass of the polyvinyl chloride.

[0056] At least one of the first PVC film and the second PVC film preferably further contains an ultraviolet absorbing agent.

[0057] The ultraviolet absorber has the function of suppressing photodegradation of the polyvinyl chloride resin mainly by absorbing ultraviolet light that hits the surface of the polyvinyl chloride film. Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and triazine-based ultraviolet absorbers.

[0058] The benzotriazole-based ultraviolet absorber may be, for example, Adeka STAB LA-29 manufactured by ADEKA CORPORATION.

[0059] The triazine-based ultraviolet absorber preferably has a 2,4,6-triphenyl-1,3,5-triazine skeleton, and more preferably has only one hydroxyl group bonded to the 2,4,6-triphenyl-1,3,5-triazine skeleton, since this has little steric hindrance and ensures high compatibility with polyvinyl chloride.

[0060] The ultraviolet absorbing agent preferably contains 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]phenol. A specific example is Adeka STAB LA-46 manufactured by ADEKA CORPORATION.

[0061] The ultraviolet absorber preferably contains 2-[4,6-bis(1,1'-biphenyl-4-yl)-1,3,5-triazin-2-yl]-5-[(2-ethylhexyl)oxy]phenol. A specific example is Tinuvin 1600 manufactured by BASF Japan Ltd.

[0062] The content of the ultraviolet absorber is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 2.5 parts by mass, and even more preferably 0.3 to 2.0 parts by mass, per 100 parts by mass of polyvinyl chloride.

[0063] The heat shielding film preferably has an elongation of 200% or more and 500% or less, as measured at 80°C based on a tensile test in accordance with JIS K 6732. If the elongation is less than 200%, the film may not be able to sufficiently conform to the shape of the substrate, and may crack. On the other hand, if the elongation exceeds 500%, the film may be prone to wrinkling when attached to the substrate, and workability may decrease. The elongation is more preferably 300% or more and 400% or less.

[0064] The above-mentioned elongation at 80°C is based on a tensile test in accordance with JIS K6732-1996, and a tensile test is performed under the following conditions by placing a dumbbell test piece in a test room adjusted to 80°C ± 2°C, and the elongation L (%) can be calculated using the following formula. Elongation L(%)=[L1-L0 / L0]×100 (L 0: First gauge length (mm), L 1: Gauge distance when cut (mm) <Test conditions> Test environment temperature: 80±2℃, Sample: Dumbbell No. 1 (lengthwise) Between gauge lines = 40mm Tensile speed = 200 mm / min

[0065] Fig. 2 is a schematic cross-sectional view of a heat barrier film having a top film, a first PVC film, and a second PVC film in this order. As shown in Fig. 2, the heat barrier film 10 may include a top film 3 on the side of the first PVC film 1 opposite to the second PVC film 2. The top film may be disposed on the outermost surface of the heat barrier film.

[0066] The top film preferably contains polyvinyl chloride and an ultraviolet absorbing agent. The polyvinyl chloride and the ultraviolet absorbing agent may be the same as those exemplified for the first PVC film.

[0067] The content of the ultraviolet absorbing agent in the top film is preferably 0.5 parts by mass or more and 5 parts by mass or less, and may be 3 parts by mass or less, based on 100 parts by mass of the polyvinyl chloride.

[0068] The top film further contains a plasticizer, and the plasticizer is preferably a polyester-based plasticizer. The top film is required to have better weather resistance because it is disposed on the front side of the first PVC film. When a plasticizer having an aromatic group such as a phthalic acid-based plasticizer is used, light absorption is large due to the influence of the conjugated double bond of the benzene ring, and weather resistance may be reduced. Therefore, the top film preferably contains a polyester-based plasticizer, which has better weather resistance than a phthalic acid-based plasticizer. As the polyester-based plasticizer, an aliphatic ester compound or an alicyclic ester compound exemplified in the first PVC film can be used. Among them, an aliphatic ester compound is more preferable.

[0069] The top film may be a transparent film. The top film preferably has a total light transmittance of 80% or more, more preferably 90% or more. In this specification, the total light transmittance is a value based on JIS K 7375.

[0070] The thickness of the top film is preferably 50 μm or more and 300 μm or less, and more preferably 70 μm or more and 250 μm or less.

[0071] 3 is a schematic cross-sectional view of a heat barrier film having a design layer, a first PVC film, and a second PVC film in this order. As shown in FIG. 3, the heat barrier film 10 may further include a design layer 4 on the side of the first PVC film 1 opposite to the second PVC film 2.

[0072] The design layer is, for example, a layer expressing a pattern such as a wood grain pattern, a geometric pattern, or a character, or a specific color. By having the heat shielding film have a design layer, it is possible to provide a decorated molded product with a higher design quality. The design layer may be, for example, a printed layer formed by inkjet printing, gravure printing, screen printing, rotary screen printing, flexographic printing, offset printing, electrostatic printing, or the like.

[0073] Fig. 4 is a schematic cross-sectional view of a heat barrier film having a top film, a design layer, a first PVC film, and a second PVC film in this order. As shown in Fig. 4, the heat barrier film 10 may be laminated in the order of the top film 3, the design layer 4, the first PVC film 1, and the second PVC film 2.

[0074] The first and second PVC films and the top film may contain other additives such as lubricants, modifiers, fillers, etc. As these additives, those generally blended with polyvinyl chloride can be used.

[0075] The heat shielding film 10 may further have an adhesive layer on the back side of the second PVC film 2. The adhesive layer has an adhesive function (pressure-sensitive adhesiveness), and examples of the adhesive layer include those containing an adhesive such as an acrylic adhesive, a rubber adhesive, or a silicone adhesive. Among these, acrylic adhesives are preferably used because they are excellent in adhesiveness, processability, heat aging resistance, moisture aging resistance, and weather resistance, and are relatively inexpensive.

[0076] The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably from 5 to 60 μm, and more preferably from 10 to 50 μm.

[0077] Although not shown, the heat shielding film may further have other layers such as a primer layer.

[0078] The heat shielding film may be used as a decorative film to be attached to a substrate, or may be used alone as an agricultural sheet, for example.

[0079] [Method of manufacturing heat shielding film] Another embodiment of the present invention is a method for producing the above-mentioned heat-shielding film, which includes a calendar molding step of forming the first polyvinyl chloride film and the second polyvinyl chloride film by calendar molding, and a lamination step of heating and bonding the first polyvinyl chloride film and the second polyvinyl chloride film together.

[0080] The calendering process is a process for forming the first PVC film and the second PVC film by calendering. The first PVC film and the second PVC film can be obtained, for example, by adding a plasticizer, a pigment, etc. to polyvinyl chloride, mixing (melting and kneading) them while heating using a Banbury mixer or the like to obtain a polyvinyl chloride resin composition, and then forming the polyvinyl chloride resin composition into a film.

[0081] The above-mentioned calendar molding is a molding method in which a resin composition is sandwiched between a pair of calendar rolls and stretched into a film while being heated. The distance between the calendar rolls corresponds to the thickness of the film obtained. Calendar molding is suitable because it can produce even a thin film with excellent thickness accuracy.

[0082] The type of calendar used in the above calendar molding is not particularly limited, and any of the conventionally known types, such as an inverted L type, a Z type, two upright types, an L type, and an inclined three-type, can be used.

[0083] The lamination step is a step of heating and laminating the first PVC film and the second PVC film together. The thermal lamination is, for example, a method of unwinding the first PVC film and the second PVC film, which are wound up separately, and passing the first PVC film and the second PVC film between a pair of rolls (drum rolls) while heating them, thereby laminating them by thermocompression. The PVC films are thermocompression-bonded to each other, and layer separation is unlikely to occur, so it is preferable to laminate them by thermolamination. The temperature of the drum roll is, for example, 150° to 170°.

[0084] By setting the content of the plasticizer in the first PVC film and the second PVC film to 5 parts by mass or more and 24 parts by mass or less per 100 parts by mass of polyvinyl chloride, it is possible to suppress cracking when the first PVC film and the second PVC film are pressure-bonded by thermal lamination, and also to suppress the occurrence of wrinkles and narrowing.

[0085] When the heat shielding film has a top film, the top film may also be laminated to the first PVC film by thermal lamination.

[0086] When a design layer is formed on the surface of the first PVC film, the design layer may be formed either before or after the lamination step.

[0087] When the heat shielding film has a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is preferably formed on the back side of the second PVC film after the lamination process. The pressure-sensitive adhesive layer can be formed, for example, by applying a pressure-sensitive adhesive composition to the surface of the second PVC film opposite to the surface laminated with the first PVC film using a general-purpose film-forming device or film-forming method such as various coating devices, bar coaters, doctor blades, etc., and then drying the layer.

[0088] [Decorative moldings] Fig. 6 is a schematic cross-sectional view of a decorated molded product including a heat shielding film and a substrate according to an embodiment. As shown in Fig. 6, a further embodiment of the present invention may be a decorated molded product 30 including a heat shielding film 10 and a substrate 20 disposed on the back side of the heat shielding film 10 (the side of the second polyvinyl chloride film 2 opposite to the first polyvinyl chloride film 1).

[0089] When the substrate 20 is made of resin, for example, the heat-shielding film 10 can be laminated during molding such as extrusion of the substrate, and the substrate 20 and the heat-shielding film 10 can be melt-pressed together by heat. When melt-pressing, there does not need to be an adhesive layer between the heat-shielding film 10 and the substrate 20. On the other hand, when the heat-shielding film 10 has an adhesive layer on the back side of the second PVC film 2, the heat-shielding film 10 may be attached to the substrate 20 via the adhesive layer.

[0090] Examples of materials for the substrate include resins such as polycarbonate resins, acrylic resins, styrene resins, and vinyl resins, acrylonitrile-butadiene-styrene copolymers (ABS resins), and acrylic-styrene-acrylonitrile (ASA resins); metals such as iron, copper, and aluminum; and alloys.

[0091] Examples of the substrate include decorative panels, building materials, and interior materials used outdoors or indoors in places exposed to sunlight. The heat shielding film according to the embodiment has excellent workability, and therefore can be suitably used for substrates with complex shapes such as window sashes, as shown in Fig. 5. The window sash may be made of metal or resin, and may have a bent portion of, for example, 90° or more. EXAMPLES

[0092] The materials used in the following Examples and Comparative Examples are shown in Tables 1 and 2 below.

[0093] [Table 1]

[0094] [Table 2]

[0095] The heat shielding films of the examples and comparative examples were subjected to the following measurements and evaluations. (1) L value Using a spectrophotometer "SE6000" manufactured by Nippon Denshoku Kogyo Co., Ltd., the L value of each of the first PVC film, the second PVC film and / or the top film was measured.

[0096] (2) Solar reflectance The solar reflectance was calculated by measuring the spectral reflectance from 300 to 2500 nm in accordance with the method of JIS K 5602:2008 "Method of determining the solar reflectance of coating films" and multiplying the measured spectral reflectance by the weighting coefficient shown in "Table 1 - Weighting coefficient of standard sunlight" of JIS K 5602. The spectral reflectance was measured using a UV / Visible / Near-Infrared Spectrophotometer "SolidSpec-3700" manufactured by Shimadzu Corporation.

[0097] (3) Weather resistance The heat shielding films of the Examples and Comparative Examples were placed in an accelerated weather resistance tester (metal weather meter) manufactured by Suga Test Instruments Co., Ltd. and irradiated with light. The light irradiation was carried out under the following conditions in accordance with JIS D 0205. A total of 24 hours was performed under the following irradiation conditions for 20 hours and dark conditions for 4 hours as one cycle, and the presence or absence of discoloration was confirmed by visual inspection. (Measurement conditions) Light source: Metal hydrolamp (wavelength: 300nm~400nm) Irradiation conditions Illuminance: 1.2kW / m 2 Black panel temperature: 53℃ Humidity inside the tank: 40% Duration: 20 hours Rainfall: 10 seconds (once every 15 minutes) Dark conditions (no rain) Illuminance: 0kW / m 2 Tank temperature: 53℃ Humidity inside the tank: 95% Duration: 4 hours (Judgment criteria) ◎: No discoloration was observed even after 400 hours or more of accelerated weather resistance testing. ○: Discoloration was confirmed visually after 400 hours of accelerated weather resistance testing. △: Discoloration was confirmed visually after 300 hours of accelerated weather resistance testing. ×: Discoloration was confirmed visually after 200 hours of accelerated weather resistance testing

[0098] (4) Workability during the calendar molding process As the processability in the calendar molding step of the first PVC film and the second PVC film, the following (4-1) and (4-2) were evaluated.

[0099] (4-1) Film defects The first PVC film and the second PVC film were each visually observed and 2 The number of defects on the film was counted and evaluated according to the following criteria: Film defects refer to holes or foreign matter in the film. (Judgment criteria) ○: 1m for both the first PVC film and the second PVC film 2 The number of defects on the winning piece is 5 or less. △: 1m for both the first PVC film and the second PVC film 2 The number of defects on the winning ball is between 6 and 10. ×: 1 m of at least one of the first PVC film and the second PVC film 2 The number of defects on the winning ball is 11 or more.

[0100] (4-2) Bloom Bleed The first PVC film and the second PVC film of each of the examples and comparative examples were each left to stand for 28 days in an environment with a temperature of 40°C and a humidity of 90%, and both sides of each film were visually inspected for the presence of solid matter (bloom) or liquid (bleed). (Judgment criteria) ◯: No bloom or bleeding was observed on the film surface for both the first PVC film and the second PVC film. △: At least one of the first PVC film and the second PVC film showed signs of blooming or bleeding (roughness, stickiness, or blowouts) in a part of the film. ×: Bloom or bleeding occurred on one surface of at least one of the first PVC film and the second PVC film.

[0101] (5) Processability during lamination The heat shielding films of the examples and comparative examples were evaluated for the following (5-1) to (5-4) regarding processability in the lamination step of bonding the first PVC film and the second PVC film together.

[0102] (5-1) Film warpage FIG. 7 is an explanatory diagram for explaining a method for measuring the warpage of a film. FIG. 8 is a schematic cross-sectional view taken along line X1-X2 in FIG. 7. The heat shielding films of the examples and comparative examples wound into a roll are laid out on a horizontal plane as shown in FIG. 7, and the warpage of both ends P1 and P2 in the width direction is measured. The above P1 and P2 are positioned W1 / 10 (mm) from the end in the machine direction, assuming that the length in the width direction at the end in the machine direction is W1 (mm). As shown in FIG. 8, the vertical distances d1 and d2 from the above horizontal plane to both ends P1 and P2 of the film are measured, and the average value of d1 and d2 is regarded as "warpage" and evaluated according to the following criteria. (Judgment criteria) ○: The warpage of the film edge was less than 0.5 mm. △: The warpage of the film edge was 0.5 mm or more and 10 mm or less. ×: The warp at the film edge exceeds 10 mm.

[0103] (5-2) Wrinkles in the film For the heat shielding films of the examples and comparative examples, 2 The presence or absence of wrinkles on the surface was visually checked and evaluated according to the following criteria. Note that "wrinkles" are defined as wrinkles that are 5 cm or longer in length. (Judgment criteria) 〇: No wrinkles were observed ×: Wrinkles occurred

[0104] (5-3) Film cracking For the heat shielding films of the examples and comparative examples, 2 The presence or absence of cracks at the contact point was visually confirmed and evaluated according to the following criteria. Note that "cracks" refers to molding defects in which one or both of the first and second PVC films did not stretch sufficiently when laminating the two films, resulting in cracks at the locations where they could not follow each other. (Judgment criteria) 〇: No cracks were observed in the film. ×: Whitening of the film was observed as a sign of cracking, or the film was cracked (unable to be processed)

[0105] (5-4) Film width reduction The heat shielding films of the examples and comparative examples were measured for width thinning and evaluated according to the following criteria. Fig. 9 is an explanatory diagram illustrating a method for measuring the width thinning of a film. As shown in Fig. 9, the width direction length at the end in the machine direction is W2, and the width direction length at a position W2 / 300 (mm) from the end in the machine direction is W3, and W3-W2 is defined as the width thinning. (Judgment criteria) ○: Film width reduction is less than 1 cm ×: Film width reduction is 1cm or more

[0106] (6) Film application (80℃) (6-1) Film elongation (80℃) The elongation (%) in the longitudinal direction of the heat shielding films of the examples and comparative examples at high temperature (80°C) was measured as a criterion for determining whether cracks or wrinkles would occur when the films were attached to a substrate bent 180°, such as the sash shown in Figure 5.

[0107] The elongation at 80°C was measured based on a tensile test in accordance with JIS K6732-1996. A tensile test was performed by placing a dumbbell test piece in a test room adjusted to 80°C ± 2°C under the following conditions, and the elongation L (%) was calculated using the following formula. The tensile test was performed five times, and the average value was used as the elongation (%) for each Example and Comparative Example. Elongation L(%)=[L1-L0 / L0]×100 (L 0: First gauge length (mm), L 1: Gauge distance when cut (mm) <Test conditions> Test environment temperature: 80±2℃, Sample: Dumbbell No. 1 (lengthwise) Between gauge lines = 40mm Tensile speed = 200 mm / min (Judgment criteria) ○: The elongation was 300% or more and 400% or less. △ *1 The above elongation was 200% or more and less than 300%. △ *2 The elongation was more than 400% and less than 500%. × *1 The above elongation was less than 200%. × *2 :The above growth rate exceeded 500%

[0108] (6-2) Film wrinkles and cracks (80℃) 1m 2 The film was visually inspected for wrinkles and cracks, and rated according to the following criteria. "Wrinkles" are those that are 5 cm or longer in length. "Cracks" are molding defects in which one or both of the first and second PVC films do not stretch sufficiently when the film is stretched, resulting in cracks at the points where they cannot follow the stretch. (Judgment criteria) ○: No wrinkles or cracks were observed △: Either wrinkles or cracks were observed ×: Both wrinkles and cracks were observed.

[0109] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0110] <Study of pigments> Examples 1 to 5 and Comparative Examples 1 to 6 were prepared by varying the type and content of the pigment as described below, and the L values ​​of the first and second PVC films, and the solar reflectance and weather resistance of the heat shielding film were measured or evaluated. The results are shown in Table 3 below.

[0111] Example 1 To 100 parts by mass of polyvinyl chloride shown in Table 1, 14 parts by mass of DUP as a plasticizer, 3 parts by mass of epoxidized soybean oil as a heat stabilizer, 0.3 parts by mass of a benzotriazole-based UV absorber, 0.1 parts by mass of synthetic hydrotalcite, 0.3 parts by mass of ADK STAB SP-83 and 4 parts by mass of ADK STAB AC-258 as zinc-based heat stabilizers, and 1.5 parts by mass of an acrylic processing aid (Metablen P-550A) were added to obtain a polyvinyl chloride resin composition.

[0112] The pigments shown in Table 2 were added to the polyvinyl chloride resin composition in the formulations shown in Table 3 for the first PVC film and the second PVC film, respectively, and melt-kneaded, and then calendered to form a sheet having a thickness of 70 μm, to produce the first PVC film and the second PVC film. Note that the first PVC film had a black color due to the addition of the pigments shown in Table 3.

[0113] The first PVC film and the second PVC film were overlapped and passed between drum rolls at about 160° C. to bond them together by thermal lamination, thereby producing the heat shielding film of Example 1.

[0114] (Examples 2 to 5) A second PVC film was produced in the same manner as in Example 1, except that the type or amount of pigment added to the second PVC film was changed as shown in Table 3. The same first PVC film as in Example 1 was used, and the first PVC film and each of the obtained second PVC films were thermally laminated to produce the heat shielding films of Examples 2 to 5.

[0115] Comparative Example 1 The single layer film consisting of only the first PVC film of Example 1 was used as the heat barrier film of Comparative Example 1.

[0116] Comparative Example 2 A single-layer film consisting only of the first PVC film was used as the heat-shielding film of Comparative Example 2 in the same manner as Comparative Example 1, except that the type or amount of pigment added to the first PVC film was changed as shown in Table 3.

[0117] (Comparative Examples 3 to 6) The first PVC film used in Comparative Example 2 and the second PVC film used in Examples 1 to 3 and 5 were thermally laminated to prepare the heat shielding films of Comparative Examples 3 to 6.

[0118] [Table 3]

[0119] As shown in Table 3, in all of Examples 1 to 5, the L value of the first PVC film was 20 or less, the L value of the second PVC film was 60.0 or more, and the solar reflectance at 720 to 1500 nm was 30.0% or more, and it was confirmed that the films had excellent heat shielding properties. In addition, excellent weather resistance was obtained in all Examples. From the results of Examples 4 and 5, it was confirmed that the second PVC film on the back side can obtain heat shielding properties not only in white but also in gray. From the results of Example 5, it was found that from the viewpoint of improving heat shielding properties, it is preferable that the second PVC film does not contain carbon black. From the results of Example 4, it was found that sufficient heat shielding properties can be obtained even if the color of the film is gray by adding an organic pigment.

[0120] From Comparative Examples 1 and 2, it was confirmed that a single layer of black film does not provide heat shielding properties. From the results of Comparative Examples 3 to 6, it was found that it is difficult to obtain heat shielding properties by only adjusting the L values ​​of the first and second PVC films. Furthermore, it was found that it is preferable that the first PVC film on the observer side does not contain carbon black.

[0121] <Consideration of film thickness> Examples 6 to 9 were prepared by changing the thickness of the first PVC film and / or the second PVC film, and the L value, solar reflectance, processability in the calendar molding process, and processability in the lamination process were measured or evaluated by the above-mentioned methods, and the results are shown in Table 4 below.

[0122] (Examples 6 to 9) As shown in Table 4, the heat shielding films of Examples 6 to 9 were produced in the same manner as in Example 3, except that the thickness of the first PVC film and / or the second PVC film was changed.

[0123] [Table 4]

[0124] All of Examples 3, 6 to 9 had excellent heat shielding properties, good processability in the calendar molding process, and good evaluations of wrinkles, cracks, width reduction, and weather resistance in the lamination process. On the other hand, Examples 7 and 8 had some warping due to the difference in thickness between the first PVC film and the second PVC film. Note that, as with Example 3, Examples 1, 2, 4, and 5 also had good processability in the calendar molding process and the lamination process.

[0125] <Heat barrier film with top film> Examples 10 to 12 having a top film were produced, and the L value, solar reflectance, processability in the calendar molding step, processability in the lamination step, and weather resistance were measured or evaluated by the above-mentioned methods. The results are shown in Table 5 below.

[0126] Example 10 To 100 parts by mass of polyvinyl chloride shown in Table 1, 25 parts by mass of polyester plasticizer, 1.5 parts by mass of triazine ultraviolet absorber, 0.8 parts by mass of phosphorus-based antioxidant, 4 parts by mass of Ba-Zn stabilizer (ADK STAB AC-724), 1.5 parts by mass of acrylic processing aid (Metablen P-1901 and Metablen P-530A), 0.1 part by mass of wet silica as an additive, and a pigment were added to obtain a polyvinyl chloride resin composition for the top film.

[0127] A top film was produced by forming into a sheet having a thickness of 70 μm by calendaring in the same manner as in the first PVC film of Example 1. The top film, the first PVC film used in Example 3, and the second PVC film used in Example 3 were thermally laminated in this order to produce the heat shielding film of Example 10.

[0128] (Examples 11 and 12) Two types of top films were prepared with different amounts of ultraviolet absorber as shown in Table 5, and the top films, the first PVC film used in Example 3, and the second PVC film used in Example 3 were thermally laminated in this order to prepare the heat-shielding films of Examples 11 and 12.

[0129] [Table 5]

[0130] From the results of Examples 3 and 10, it was confirmed that excellent heat shielding properties and workability in the lamination process could be obtained even when a top film was provided. Furthermore, it was confirmed that even better weather resistance could be obtained in Examples 10 and 12, in which the top film contained a large amount of ultraviolet absorbing agent.

[0131] <Consideration of types of plasticizer> Examples 13 and 14 were prepared by changing the type of plasticizer, and the L value, processability in the calendar molding process, processability in the lamination process, and weather resistance were measured or evaluated by the above-mentioned methods. The results are shown in Table 6 below.

[0132] (Examples 13 and 14) Heat shielding films of Examples 13 and 14 were produced in the same manner as in Example 3, except that the types of plasticizers added to the first PVC film and the second PVC film were changed to DINP and DIDP, respectively.

[0133] [Table 6]

[0134] As shown in Table 6, it was confirmed that Examples 13 and 14, which used different types of plasticizers, had the same heat shielding properties, workability in the calendar molding process, workability in the lamination process, and weather resistance as Example 3. The solar reflectance was not measured because the plasticizer content does not affect the solar reflectance. Furthermore, according to the inventors' studies, it was confirmed that the use of a polyester-based plasticizer as a plasticizer does not affect the solar reflectance, and weather resistance equal to or greater than that of DINP can be obtained.

[0135] <Consideration of the amount of plasticizer> Examples 15 to 19 and Comparative Examples 7 to 10 in which the plasticizer content was changed, and Comparative Example 11 in which the heat stabilizer content was changed were prepared, and the L value, processability in the calendar molding process, processability in the lamination process, weather resistance, and film elongation were measured or evaluated by the above-mentioned methods, and the results are shown in the following Table 7. Note that the solar reflectance was not measured because the plasticizer and heat stabilizer contents do not affect the solar reflectance.

[0136] (Examples 15 to 19, Comparative Examples 7 to 10) The heat shielding films of Examples 15 to 19 and Comparative Examples 7 to 10 were produced in the same manner as in Example 3, except that the plasticizer contents of the first PVC film and the second PVC film were changed as shown in Table 7.

[0137] Comparative Example 11 A heat shielding film of Comparative Example 11 was produced in the same manner as in Comparative Example 7, except that the content of the heat stabilizer was changed as shown in Table 7.

[0138] [Table 7]

[0139] Examples 3 and 15 to 19, in which the amount of plasticizer in the first PVC film and the second PVC film was 5 parts by mass or more and 24 parts by mass or less, showed good processability in the calendar molding step and the lamination step. Considering the elongation of the film, it was found that the content of the plasticizer is preferably 10 to 20 parts by mass per 100 parts by mass of PVC.

[0140] On the other hand, in Comparative Example 7, in which the amount of plasticizer was 4 parts by mass, cracks occurred during the lamination process. On the other hand, in Comparative Example 8, in which the amount of plasticizer was 27 parts by mass, cracks did not occur during the lamination process, but wrinkles and width reduction occurred. In Comparative Examples 9 and 10, in which the amount of plasticizer in either the first PVC film or the second PVC film was 4 parts by mass and the amount of plasticizer in the other film was 27 parts by mass, cracks, wrinkles, and width reduction occurred, and further, warping occurred due to the difference in hardness between the first PVC film and the second PVC film.

[0141] The addition of a plasticizer can reduce film cracking during the lamination process, but a high content of heat stabilizer (epoxidized soybean oil) tends to make the film more susceptible to blooming or bleeding. [Explanation of symbols]

[0142] 1: First PVC film 2: Second PVC film 3: Top film 4: Design layer 10: Heat-shielding film 20: Base material 30: Decorative molding

Claims

1. A first polyvinyl chloride film and a second polyvinyl chloride film disposed on a back surface side of the first polyvinyl chloride film, the first polyvinyl chloride film has an L value in an L*a*b* color space of 20.0 or less; the second polyvinyl chloride film has an L value in an L*a*b* color space of 60.0 or more; The first polyvinyl chloride film contains polyvinyl chloride, a plasticizer, and a pigment, The second polyvinyl chloride film contains polyvinyl chloride, a plasticizer, and a titanium-based pigment, a content of the plasticizer in the first polyvinyl chloride film and the second polyvinyl chloride film is 5 parts by mass or more and 24 parts by mass or less relative to 100 parts by mass of the polyvinyl chloride; A heat shielding film having a solar reflectance of 30.0% or more in the wavelength region of 750 nm to 1500 nm.

2. The heat shielding film according to claim 1 , wherein the pigment comprises an organic pigment.

3. 2. The heat shielding film according to claim 1, wherein at least one of the first polyvinyl chloride film and the second polyvinyl chloride film further contains a heat stabilizer.

4. The heat shielding film according to claim 3 , wherein the heat stabilizer comprises an epoxy compound or a zinc-based heat stabilizer.

5. The heat-shielding film according to claim 1, characterized in that the difference between the content of plasticizer contained in the first polyvinyl chloride film and the content of plasticizer contained in the second polyvinyl chloride film is 15 parts by mass or less.

6. 2. The heat shielding film according to claim 1, wherein at least one of the first polyvinyl chloride film and the second polyvinyl chloride film further contains an ultraviolet absorbing agent.

7. a top film on the side of the first polyvinyl chloride film opposite the second polyvinyl chloride film; The top film contains polyvinyl chloride and an ultraviolet absorber, 2. The heat shielding film according to claim 1, wherein the content of the ultraviolet absorbing agent is 0.5 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the polyvinyl chloride.

8. The top film further comprises a plasticizer, The heat shielding film according to claim 7 , wherein the plasticizer is a polyester-based plasticizer.

9. The heat shielding film according to claim 1, further comprising a design layer on the side of the first polyvinyl chloride film opposite the second polyvinyl chloride film.

10. 2. The heat shielding film according to claim 1, wherein the heat shielding film is laminated in the following order: a top film, a design layer, the first polyvinyl chloride film, and the second polyvinyl chloride film.

11. A method for producing a heat shielding film according to any one of claims 1 to 10, a calendering step of forming the first polyvinyl chloride film and the second polyvinyl chloride film by calendering, respectively; and a lamination step of heating and bonding the first polyvinyl chloride film and the second polyvinyl chloride film together.

Images