Laminate comprising a synthetic polymer membrane having antibacterial and / or antiviral properties, and method for manufacturing the same.

Abstract

To provide a method for producing a laminate comprising a synthetic polymer film having antimicrobial and / or antiviral properties.SOLUTION: A method for producing a layered article including a synthetic polymer film having antimicrobial and / or antiviral properties comprises: preparing a layered article 50A having a substrate 42 and a synthetic polymer film 34A formed on the substrate, in which the synthetic polymer film has, on a surface thereof, a plurality of protrusions 34Ap having an area equivalent circle diameter in a range of more than 20 nm to less than 500 nm when viewed from a normal direction of the synthetic polymer film; and irradiating the plurality of protrusions in the layered article with light emitted from a xenon lamp such that an amount of irradiation with light in a wavelength range of 300 nm or more to 400 nm or less is 6 MJ / m2 or more.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a laminate comprising a synthetic polymer membrane having antibacterial and / or antiviral properties, and a method for producing the same. [Background technology]

[0002] The applicant has disclosed, for example, in Patent Documents 1 to 4, synthetic polymer films having a moth-eye structure on their surface and possessing a bactericidal surface. The term "synthetic polymer film" is used to distinguish it from natural products (lipid films) such as the wings of cicadas and dragonflies that have a nano-surface structure. All of the disclosures in Patent Documents 1 to 4 are incorporated herein by reference. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2015 / 163018 [Patent Document 2] International Publication No. 2016 / 080245 [Patent Document 3] International Publication No. 2016 / 208540 [Patent Document 4] Japanese Patent Publication No. 2019-051638 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The present invention aims to further improve the bactericidal effect of synthetic polymer membranes. Specifically, the objective is to improve the antibacterial properties and / or antiviral properties as evaluated by methods compliant with JIS Z 2801 and ISO 21702:2019. [Means for solving the problem]

[0005] According to embodiments of the present invention, the following solutions are provided. [Item 1] A method for producing a laminate comprising a synthetic polymer film having antibacterial and / or antiviral properties, A laminate is prepared comprising a substrate and a synthetic polymer film formed on the substrate, wherein the synthetic polymer film has a plurality of protrusions (sometimes referred to as "first protrusions") on its surface, the area circle equivalent diameter being in the range of more than 20 nm and less than 500 nm when viewed from the direction normal to the synthetic polymer film. The irradiation intensity of light in the wavelength range of 300 nm to 400 nm onto the multiple protrusions of the laminate is 6 MJ / m². 2 As described above, the light emitted from the xenon lamp is irradiated and A manufacturing method that includes this. [Item 2] Irradiating with the light emitted from the xenon lamp results in an irradiation light intensity of 22 MJ / m² with a wavelength range of 300 nm to 400 nm. 2 The manufacturing method described in item 1, wherein the light emitted from a xenon lamp is irradiated as follows. [Item 3] The manufacturing method according to item 1 or 2, wherein the irradiation with the emitted light from the xenon lamp is performed in an environment with a relative humidity of 50% or less. [Item 4] The manufacturing method according to any one of items 1 to 3, wherein the irradiation of the surface of the synthetic polymer film with the emitted light from the xenon lamp is performed while continuously blowing air onto the surface. [Item 5] The manufacturing method according to any one of items 1 to 4, wherein the synthetic polymer film is formed of an ultraviolet-curable resin. [Item 6] The manufacturing method according to item 5, comprising irradiating the UV-curable resin with ultraviolet light before irradiating it with the light emitted from the xenon lamp, thereby forming the synthetic polymer film with the UV-curable resin. [Item 7] The manufacturing method according to items 1 to 6, wherein the plurality of protrusions include substantially conical protrusions with a base diameter of more than 20 nm and less than 500 nm. [Item 8] The manufacturing method according to item 7, wherein the substantially oval convex portion includes a convex portion having a height of at least twice the diameter of the bottom surface. [Item 9] A laminate comprising a synthetic polymer film having antibacterial and / or antiviral properties, produced by the manufacturing method according to items 1 to 8. [Item 10] When viewed from the normal direction of the synthetic polymer film, the synthetic polymer film has a plurality of convex portions on its surface within a range where the equivalent diameter of the area circle is more than 20 nm and less than 500 nm. The laminate according to item 9, wherein the plurality of convex portions include a convex portion having a maximum length of the bottom surface exceeding twice the height. [Advantages of the Invention]

[0006] According to an embodiment of the present invention, there are provided a laminate comprising a synthetic polymer film having excellent antibacterial and / or antiviral properties, and a manufacturing method thereof. [Brief Description of the Drawings]

[0007] [Figure 1A] It is a schematic cross-sectional view of a laminate 50A including a synthetic polymer film 34A having a moth-eye structure. [Figure 1B] It is a schematic plan view showing a convex portion 34Ap when viewed from the normal direction of the synthetic polymer film 34A. [Figure 2A] It is a schematic cross-sectional view of a laminate 50B including a synthetic polymer film 34B obtained by irradiating the synthetic polymer film 34A with the emitted light of a xenon lamp.

[0008] [Figure 2B] It is a schematic plan view showing a convex portion 34Bp when viewed from the normal direction of the synthetic polymer film 34B. [Figure 3] It is a view showing a surface SEM image of a synthetic polymer film having a moth-eye structure. [Figure 4] It is a view showing a surface SEM image of the synthetic polymer film after irradiating the synthetic polymer film having the moth-eye structure shown in Fig. 3 with the emitted light of a xenon lamp. [Figure 5]This graph shows the time-dependent change in pH with and without xenon lamp irradiation. [Figure 6] This graph shows the change in antibacterial properties due to xenon lamp irradiation. [Figure 7] This graph shows the change in antiviral activity (influenza virus A) after irradiation with a xenon lamp. [Figure 8] This graph shows the change in antiviral activity (feline calicivirus) after xenon lamp irradiation. [Figure 9] This figure shows the mechanism of auto-oxidation of synthetic polymers. [Modes for carrying out the invention]

[0009] Hereinafter, with reference to the drawings, a laminate comprising a synthetic polymer film having antibacterial and / or antiviral properties according to an embodiment of the present invention and a method for producing the same will be described. The laminate comprising a synthetic polymer film having antibacterial and / or antiviral properties according to an embodiment of the present invention and a method for producing the same are not limited to those exemplified below. Here, "having antibacterial properties" means that the antibacterial activity value obtained by a test method in accordance with JIS Z 2801 standard is 2.0 or higher, and "having antiviral properties" means that the antiviral activity value obtained by a test method in accordance with ISO 21702:2019 standard is 2.0 or higher.

[0010] The applicant has developed a method for manufacturing an anti-reflective film (anti-reflective surface) having a moth-eye structure using an anodized porous alumina layer. By using an anodized porous alumina layer, molds having an inverted moth-eye structure can be manufactured with high mass productivity (Japanese Patent Publication No. 2009-166502, International Publication No. 2011 / 125486, International Publication No. 2013 / 183576). Synthetic polymer films having a moth-eye structure on their surface and possessing a bactericidal surface, as described in Patent Documents 1 to 4, can be manufactured by applying this technology. All disclosures of Japanese Patent Publication No. 2009-166502, International Publication No. 2011 / 125486, and International Publication No. 2013 / 183576 are incorporated herein by reference.

[0011] The present invention provides a method for manufacturing a laminate comprising a synthetic polymer film having antibacterial and / or antiviral properties, comprising the steps of: preparing a laminate comprising a substrate and a synthetic polymer film formed on the substrate, wherein the synthetic polymer film has a plurality of protrusions on its surface, the area circle equivalent diameter of which is in the range of more than 20 nm and less than 500 nm when viewed from the direction normal to the synthetic polymer film; and irradiating the plurality of protrusions of the laminate with light in the wavelength range of 300 nm to 400 nm with a light intensity of 6 MJ / m². 2 The process includes irradiating with the emitted light from a xenon lamp, as described above. The above irradiation light amount is 6 MJ / m 2 If the pH level is not above this level, the effect of improving antibacterial and / or antiviral properties may not be sufficiently obtained. For example, it may not be possible to lower the pH value to 5.0 or below.

[0012] First, with reference to Figures 1A and 1B, we will describe a laminate 50A having a substrate 42 and a synthetic polymer film 34A formed on the substrate 42, wherein the synthetic polymer film 34A has a plurality of protrusions 34Ap on its surface, the area circle equivalent diameter being in the range of more than 20 nm and less than 500 nm when viewed from the direction normal to the synthetic polymer film 34A.

[0013] The laminate 50A shown in Figure 1A comprises, for example, a substrate 42 and a synthetic polymer film 34A formed on the substrate 42. The synthetic polymer film 34A has a plurality of protrusions 34Ap on its surface, and these protrusions 34Ap constitute a moth-eye structure. When viewed from the direction normal to the synthetic polymer film 34A, the two-dimensional size Dp of the protrusions 34Ap is in the range of more than 20 nm and less than 500 nm. Here, the "two-dimensional size" of the protrusions 34Ap refers to the area circle equivalent diameter of the protrusions 34Ap when viewed from the direction normal to the surface. For example, if the protrusions 34Ap are conical, the two-dimensional size of the protrusions 34Ap corresponds to the diameter of the base of the cone, as shown in Figure 1B. Also, the typical adjacent distance Dint of the protrusions 34Ap is more than 20 nm and less than or equal to 1000 nm. As illustrated in Figure 1A, when the convex portions 34Ap are densely arranged and there are no gaps between adjacent convex portions 34Ap (for example, the bases of the cones partially overlap), the two-dimensional size Dp of the convex portions 34Ap is equal to the distance between adjacent portions Dint.

[0014] The typical height Dh of the protrusion 34Ap is 50 nm or more and less than 500 nm. The height Dh of the protrusion 34Ap may be 200 nm or less. The multiple protrusions 34Ap include, for example, substantially conical protrusions with a base diameter greater than 20 nm and less than 500 nm, and the substantially conical protrusions include protrusions whose height is twice or more the diameter of the base. The substantially conical protrusions whose height is twice or more the diameter of the base account for, for example, 60% or more of the total protrusions. Note that the multiple protrusions 34Ap do not have to include substantially conical protrusions whose height is twice or more the diameter of the base. Also, in this embodiment, the multiple protrusions 34Ap do not include protrusions whose maximum base length is more than twice the height, which are included in the multiple protrusions 34Bp described later. There are no particular restrictions on the thickness ts of the synthetic polymer film 34A; it is sufficient if it is greater than the height Dh of the protrusions 34Ap.

[0015] In this specification, the term "moth-eye structure" includes not only nanosurface structures with excellent anti-reflective properties, such as the protrusion 34Ap of the synthetic polymer film 34A shown in Figure 1A, which is composed of protrusions whose cross-sectional area (cross-section parallel to the film surface) increases as it approaches the substrate 42, but also nanosurface structures composed of protrusions with a constant cross-sectional area (cross-section parallel to the film surface). It is preferable to have a conical portion in order to disrupt the cell wall and / or cell membrane of bacteria. However, the tip of the cone may be rounded.

[0016] The synthetic polymer film 34A having a moth-eye structure can be manufactured using the mold having the inverted moth-eye structure described above. The synthetic polymer film 34A is preferably manufactured using an ultraviolet-curable resin. The ultraviolet-curable resin is cured by irradiation with ultraviolet light in the so-called "D-bulb" range (280 nm to 400 nm, peak wavelength 380 nm). Various known ultraviolet-curable resins (e.g., acrylic resins) can be used as the ultraviolet-curable resin. A resin cured by irradiating an ultraviolet-curable resin with ultraviolet light is sometimes called an ultraviolet-cured resin. As the base material 42, various plastic films (e.g., polystyrene, polyurethane, aromatic polyamide, polyester, polycarbonate) can be used. Polycarbonate (PC), which has excellent light resistance and oxidation resistance, is preferred.

[0017] The inventors have found that when multiple protrusions 34Ap of the above-mentioned laminate are irradiated with light in the wavelength range of 300 nm to 400 nm, the light intensity is 6 MJ / m 2 As described above, we found that irradiating with the light emitted from a xenon lamp can improve antibacterial and / or antiviral properties. There is no particular upper limit to the irradiation light intensity, but 22 MJ / m² is recommended. 2 Exceeding this level does not improve antibacterial and / or antiviral properties, and from the standpoint of mass production, the irradiation light dose is 22 MJ / m². 2 The following is acceptable. Furthermore, the above irradiation light intensity is 22 MJ / m². 2When it exceeds this value, the synthetic polymer film may turn yellow. For example, when the intensity of light in the wavelength range of 300 nm or more and 400 nm or less is 60 W / m 2 ², it may be irradiated for 30 to 100 hours. For example, by using a xenon arc lamp (Xenon Weather Meter XL75 manufactured by Suga Test Instruments Co., Ltd.) and irradiating from a position 290 mm away from the synthetic polymer film 44A, light with an intensity of about 60 W / m 2 ² in the wavelength range of 300 nm or more and 400 nm or less can be irradiated.

[0018] When the synthetic polymer film (preferably an ultraviolet-curable resin) is irradiated with light in the wavelength range of 300 nm or more and 400 nm or less, the chemical bonds constituting the synthetic polymer film are broken, and well-known auto-oxidation occurs. The radicals and intermediate products generated by the photoreaction further auto-oxidize to generate radicals and acids. The mechanism of auto-oxidation is represented, for example, as shown in Fig. 9. The generated radicals, etc. attack the proteins on the surface of bacteria and / or viruses, extract hydrogen, and decompose the proteins. Alternatively, the acids generated by the photoreaction can make it difficult for bacteria and / or viruses to survive. In addition, it is known that organic components having aldehyde-based, carboxylic acid-based, and ester-based chemical structures can damage proteins such as DNA, RNA, and enzymes, and ultraviolet-curable resin films and substrates that generate them by photoreaction may also be used.

[0019] In addition, the step of irradiating the emitted light of the xenon lamp is preferably carried out in an environment with a relative humidity of 50% or less. This is because hydrolysis may occur depending on the ultraviolet-curable resin. Further, the step of irradiating the emitted light of the xenon lamp is preferably carried out while continuously blowing air onto the surface of the synthetic polymer film 34A. During this period, the synthetic polymer film 34A is preferably placed in an environment of about 50 °C or less.

[0020] Next, with reference to Figures 2A and 2B, the structure of the laminate 50B having the synthetic polymer film 34B after irradiation with the emitted light from a xenon lamp will be described. Figure 2A is a schematic cross-sectional view of the laminate 50B having the synthetic polymer film 34B obtained by irradiating the synthetic polymer film 34A with the emitted light from a xenon lamp, and Figure 2B is a schematic plan view showing the convex portion 34Bp as seen from the normal direction of the synthetic polymer film 34B.

[0021] As shown in Figure 2A, the multiple protrusions 34Bp of the synthetic polymer film 34B are formed as a result of the decomposition of the multiple protrusions 34Ap of the synthetic polymer film 34A shown in Figure 1A. The height Dh is reduced, and the tops of the protrusions, which were approximately conical, become rounded. Protrusions with flat tops may also be formed. The bottoms of the recesses between adjacent protrusions 34Bp also become rounded. Recesses with flat bottoms may also be formed between adjacent protrusions 34Bp. The variation in the shape and size of the multiple protrusions 34Bp increases. The multiple protrusions 34Bp include protrusions where the maximum length of the base (here Dx) is more than twice the height Dh. The multiple protrusions 34Bp may also include protrusions where the maximum length of the base is three times or more the height Dh. The multiple protrusions 34Bp may or may not include a substantially conical protrusion whose height is at least twice the diameter of its base, which was included in the multiple protrusions 34Ap. The maximum length of the base of a protrusion is the maximum distance between two points on the outer circumference of the base of each individual protrusion.

[0022] Furthermore, as shown in Figure 2B, when viewed from the normal direction of the synthetic polymer film 34B, the maximum length of the bottom surface of the protrusion 34Bp (here, Dx) is approximately equal to the minimum length of the bottom surface (here, the length Dy in the direction perpendicular to Dx), and Dx / Dy is less than 2.0. The shape of the bottom surface of the protrusion 34Bp is approximately circular.

[0023] Refer to Figures 3 and 4 to explain the experimental examples.

[0024] A synthetic polymer film having a moth-eye structure was formed on a polycarbonate base film. A solvent-free resin material was prepared by blending polyethylene glycol diacrylate (M280: manufactured by MIWON SPECIALTY CHEMICAL CO., LTD), trimethylolpropane triacrylate (M300: manufactured by MIWON SPECIALTY CHEMICAL CO., LTD), 2-(2-vinyloxyethoxy)ethyl acrylate (VEEA: manufactured by Nippon Shokubai Co., Ltd.), and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Omnirad2959: manufactured by IGM Resins BV) as a polymerization initiator, in a mass ratio of M280:M300:VEEA:Omnirad = 55:10:35:1. After coating the polycarbonate base film to the desired thickness, a D-valve (320-400 nm, 1200 W / m²) was applied. 2 ) for approximately 15 seconds (22500 J / m³) 2 The sample was irradiated. The moth-eye structure was defined as Dp=Dint=200nm and Dh=200nm.

[0025] Figure 3 shows a surface SEM image of a synthetic polymer film having a moth-eye structure. It can be seen that multiple roughly conical protrusions are densely formed. The multiple protrusions on the surface of the synthetic polymer film shown in Figure 3 have the characteristics of the multiple protrusions 34Ap described with reference to Figure 1A, and include roughly conical protrusions whose height is more than twice the diameter of the base, and these roughly conical protrusions whose height is more than twice the diameter of the base account for more than 60% of the total protrusions, for example. There are also roughly conical protrusions whose height is less than twice the diameter of the base.

[0026] Figure 4 shows the synthetic polymer film having the above-described moth-eye structure exposed to the light emitted from a xenon lamp (60W / m²). 2 ) for 100 hours (approximately 22 MJ / m³) 2Figure 3 shows a surface SEM image of the synthetic polymer film after irradiation. The moth-eye structure seen in Figure 3 has been decomposed, resulting in a reduced height. While some cone-shaped protrusions exist, the tops of many protrusions are rounded. Protrusions with flat tops are also formed. The bottoms of the recesses between adjacent protrusions are also rounded, and recesses with flat bottoms are formed between adjacent protrusions. There is considerable variation in the shape and size of multiple protrusions. Some protrusions have a maximum base length (generally horizontal, sometimes referred to as "width") that is more than twice their height, but generally, the width of the protrusions is between one and two times their height, with many protrusions having a width of 1.0 to 1.5 times their height. However, multiple protrusions may include protrusions where the maximum base length is three times or more their height (for example, the protrusion near the center in Figure 4).

[0027] Next, refer to Figure 5. Figure 5 is a graph showing the time change in pH with and without xenon lamp irradiation. In other words, it evaluates how the surface of a synthetic polymer membrane having a moth-eye structure chemically changes due to xenon lamp irradiation, as measured by the time change in pH. The horizontal axis of the graph represents the time in contact with the test solution. The same synthetic polymer membrane as in Figure 4 was used as the sample. pH was measured using a method equivalent to that used for antiviral testing. Specifically, it was measured as follows.

[0028] 0.1 ml of EMEM dilution (a solution of EMEM diluted 10-fold with sterile distilled water) was dropped onto the moth-eye structured surface of the sample placed in a petri dish, just as it was for the virus suspension. A contact film (polyethylene film) was then placed over the sample and lightly pressed down to ensure the dilution was evenly distributed across the film. The petri dish was then covered and left at 25°C for 24 hours. After that, the contact film was removed, and the pH of the test solution on the sample surface was measured using a flat ISFET pH electrode manufactured by Horiba, Ltd.

[0029] As shown in Figure 5, at 0 hours of contact with the test solution, the pH value of the synthetic polymer film irradiated with a xenon lamp (5.68) is lower than the pH value of the synthetic polymer film not irradiated with a xenon lamp (8.05), placing it in the acidic region. This is thought to be because photochemical reactions occurred on the surface of the synthetic polymer film due to xenon lamp irradiation, generating acidic components. At 24 hours of contact with the test solution, the pH value of the synthetic polymer film not irradiated with a xenon lamp (8.09) remained almost unchanged, while the pH value of the synthetic polymer film irradiated with a xenon lamp (3.60) decreased even further. This suggests that auto-oxidation reactions occurred on the surface of the synthetic polymer film irradiated with a xenon lamp due to radicals and intermediate products generated within the resin by photochemical reactions.

[0030] Figure 6 shows the results of the antibacterial activity evaluation using a method compliant with JIS Z 2801 (ISO 22196). Bacterial solutions were inoculated into xenon lamp irradiated samples and unirradiated samples, respectively. After allowing the samples to come into contact with the bacteria for 24 hours, the number of bacteria on the samples was measured using the plaque assay method, and the antibacterial activity value was calculated by comparing the bacterial loads of the xenon lamp irradiated and unirradiated samples.

[0031] The bacterial species used were Staphylococcus aureus (dotted and solid lines in Figure 6) and Escherichia coli (double-dotted and dashed lines in Figure 6). While the moth-eye structure unirradiated with xenon lamp showed no antibacterial effect against these bacteria, the antibacterial activity value of the synthetic polymer membrane with a moth-eye structure irradiated with xenon lamp was greater than 2.0 for both bacterial species, indicating that xenon lamp irradiation improved antibacterial activity. The antibacterial activity values ​​were determined as follows. Antimicrobial activity value = log(bacterial count after 24-hour culture of untreated product) - log(bacterial count after 24-hour culture of antimicrobial treated product) Staphylococcus aureus activity level ≥ 4.4 = 4.25 - (-0.2) E. coli activity level ≥ 3.9 = 3.7 - (-0.2)

[0032] Note that "-0.2" represents the detection limit.

[0033] Figures 7 and 8 show the results of evaluating antiviral activity using a method compliant with ISO 21702:2019.

[0034] Influenza virus A (enveloped virus) (Figure 7) and feline calicivirus (non-enveloped virus) (Figure 8) were used as the virus species.

[0035] As can be seen from Figures 7 and 8, xenon lamp irradiation improved the antiviral effect, and antiviral activity values ​​of over 2.0 were obtained for all viruses. The antiviral activity values ​​were determined as follows. Antiviral activity value = log(virus count after 24-hour incubation of untreated product) - log(virus count after 24-hour incubation of antiviral treated product) Influenza activity level ≥ 3.4 = 4.16 - 0.8 Feline calicivirus activity level ≥ 2.7 = 5.49 - 2.83

[0036] Here, we have shown an example of irradiating a synthetic polymer film with a moth-eye structure with a xenon lamp. However, even without a moth-eye structure, it is thought that if a resin material is used in which irradiation with a xenon lamp causes chemical reactions such as auto-oxidation, decomposition, and the formation of a fine uneven surface (surface roughening) is achieved, the antibacterial and / or antiviral properties can be improved. The irradiation conditions for the xenon lamp may be the same as those for the synthetic polymer film with the moth-eye structure exemplified. [Industrial applicability]

[0037] A method for producing a laminate comprising a synthetic polymer membrane having antibacterial and / or antiviral properties according to embodiments of the present invention makes it possible to provide a laminate with improved antibacterial and / or antiviral properties compared to conventional methods. According to embodiments of the present invention, a laminate comprising a synthetic polymer membrane having antiviral properties against both enveloped viruses and non-enveloped viruses can be provided. [Explanation of Symbols]

[0038] 34A, 34B Synthetic polymer membrane 34Ap, 34Bp convex part 42 Base material 50A, 50B laminate

Claims

1. A method for producing a laminate comprising a synthetic polymer film having antibacterial and / or antiviral properties, A laminate is prepared comprising a substrate and a synthetic polymer film formed on the substrate, wherein the synthetic polymer film is formed from an ultraviolet-curing resin and has a plurality of protrusions on its surface, the area equivalent diameter of which is in the range of more than 20 nm and less than 500 nm when viewed from the normal direction of the synthetic polymer film, and the plurality of protrusions include substantially conical protrusions whose base diameter is more than 20 nm and less than 500 nm and whose height is more than twice the diameter of the base, When the multiple protrusions of the laminate are irradiated with light in the wavelength range of 300 nm to 400 nm, the light intensity is 6 MJ / m². ２ As described above, the ultraviolet curing resin is irradiated with light emitted from a xenon lamp to cause auto-oxidation. A manufacturing method that includes this.

2. Irradiating with the light emitted from the xenon lamp results in an irradiation light intensity of 22 MJ / m² with a wavelength range of 300 nm to 400 nm. ２ The manufacturing method according to claim 1, wherein the light emitted from the xenon lamp is irradiated in the following manner.

3. The manufacturing method according to claim 1 or 2, wherein the irradiation with the emitted light from the xenon lamp is performed in an environment with a relative humidity of 50% or less.

4. The manufacturing method according to claim 1 or 2, wherein the irradiation of the xenon lamp with light emitted from the xenon lamp is performed while continuously blowing air onto the surface of the synthetic polymer film.

5. The manufacturing method according to claim 1 or 2, comprising irradiating the ultraviolet-curable resin with ultraviolet light before irradiating it with the light emitted from the xenon lamp, thereby forming the synthetic polymer film with the ultraviolet-curable resin.

6. The manufacturing method according to claim 5, wherein the ultraviolet-curable resin is an acrylic ultraviolet-curable resin.

7. The manufacturing method according to claim 6, wherein the acrylic ultraviolet-curable resin comprises polyethylene glycol diacrylate.

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