CN117162628A - decorative film structure - Google Patents

Abstract

The present invention provides a decorative film structure in which a decorative film is attached to the back of a transparent base material to suppress the occurrence of wrinkles and air entrapment. A decorative film structure, including a transparent base material and a decorative film attached to the back of the transparent base material. In the decorative film structure, the transparent base material has a surface protruding to the front surface side and a radius of curvature of For a curved surface of 20 mm or more and 100 mm or less, the decorative film includes a base film and an adhesive layer, and is attached to the transparent base material through the adhesive layer. The adhesive layer includes a main agent and a leveling agent. The cured product of the adhesive composition.

Description

decorative film structure

Technical field

The following disclosure relates to a decorative film structure.

Background technique

In the past, designs such as colors, patterns, patterns, and characters were given to molded products by attaching decorative films to them. In addition, a structure in which a decorative film is affixed to the back side of the base material so that the design can be visually recognized from the front side of the base material is also being studied (for example, Patent Document 1, etc.). As a method of manufacturing a decorative molded article, a method of attaching a decorative film using vacuum forming or vacuum-pressure forming is known (for example, Patent Document 2, etc.).

Patent Document 1 discloses a decorative plate, which is characterized in that it includes a base material and has a plate shape, and the thickness of the plate is smoothed so that one main surface is flat and the back surface of the main surface has an uneven shape. The gradient is formed of colored and transparent resin, and the light transmittance also gradually changes smoothly with the change of the plate thickness; and the sheet is a curved plate shape having the same concave and convex shape as the back surface of the base material, the plate The thickness is uniform, and printing is performed on one of the surfaces and is in close contact with the back surface of the base material. Due to the gradation of the transmittance of the base material, the surface on which the printing is performed changes from the flat main surface of the base material. The sides are visually identifiable as grayscale.

Patent Document 2 discloses a method for manufacturing a laminated molded article having a lamination step (1) in which a stretchable layer is formed by vacuum forming, pressure forming, or vacuum-pressure forming. An adhesive sheet in which an adhesive layer is disposed on one surface of a release film is laminated on the surface of the concave-convex molded article so that the adhesive layer is disposed on the concave-convex molded article side.

[Prior art documents]

[Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2011-5687

[Patent Document 2] Japanese Patent Application Publication No. 2015-196289

Contents of the invention

[Problem to be solved by the invention]

As a method of attaching a decorative film to a base material and imparting a design, a method of attaching the decorative film from the front side of the base material is generally used. However, sufficient gloss or depth may not be obtained in some cases. When applying a design from the back side of a base material, decoration using a decorative film is easy if the base material is flat. However, when attaching a decorative film from the back side to a base material with a certain radius of curvature, Sometimes, the decorative film may wrinkle during decoration molding, or air may be trapped between the base material and the decorative film.

Furthermore, in Patent Document 1, the thickness of the plate is smoothly graded so that one of the main surfaces is flat and the back surface of the main surface has an uneven shape (claim 1), and the thickness of the plate portion is 0.15 mm to 0.188 mm. Within the range (paragraph [0020]), the concave and convex difference is very small, 0.038mm.

The present invention was made in view of the current situation, and an object thereof is to provide a decorative film structure in which a decorative film is affixed to the back side of a transparent base material and the occurrence of wrinkles and air entrapment is suppressed.

[Technical means to solve problems]

(1) One embodiment of the present invention is a decorative film structure including a transparent base material and a decorative film attached to the back surface of the transparent base material. In the decorative film structure, the transparent base material has an orientation direction. A curved portion with a protruding front surface side and a curvature radius of 20 mm or more and 100 mm or less, the decorative film includes a base film and an adhesive layer, and is attached to the transparent base material through the adhesive layer, and the adhesive The layer is a hardened product of an adhesive composition containing a main agent and a leveling agent.

(2) In addition, one embodiment of the present invention is a decorative film structure, wherein in the structure of (1), the arithmetic surface of the surface of the transparent base material on the adhesive layer side The average roughness Ra is 0.16 μm or less.

(3) In addition, one embodiment of the present invention is a decorative film structure in which, in addition to the structure of (1) or (2), the adhesive composition contains a polyester-based compound as the Describe the main ingredient.

(4) In addition, one embodiment of the present invention is a decorative film structure, wherein, in addition to the structure of (3), the adhesive composition further contains an isocyanate-based hardener, the following formula ( 1) The indicated NCO index is 0.4 or more and 1.6 or less.

NCO index=Number of moles of NCO groups derived from the isocyanate component contained in the isocyanate-based hardener/Number of moles of OH groups derived from the polyester contained in the polyester-based compound (1)

(5) In addition, one embodiment of the present invention is a decorative film structure, in which, based on any one of the structures (1) to (4), relative to 100 parts by weight of the main component The leveling agent content is 0.03 to 0.6 parts by weight.

(6) In addition, one embodiment of the present invention is a decorative film structure, wherein in the structure of any one of (1) to (5), the transparent base material is a glass base material.

(7) In addition, one embodiment of the present invention is a decorative film structure, in which the decorative film is formed from the transparent base material based on any one of the structures (1) to (6). There are the adhesive layer, the base film, and the design layer in order from the side.

(8) In addition, one embodiment of the present invention is a decorative film structure, wherein based on any one of the structures (1) to (6), the decorative film is formed from the transparent base material There are the adhesive layer, the base film, the design layer, and the resin film in this order from the side.

(9) In addition, one embodiment of the present invention is a decorative film structure, wherein based on any one of the structures (1) to (6), the decorative film is formed from the transparent base material There are the adhesive layer, the base film, the design layer, the resin film, and the back coating in order from the side.

(10) In addition, one embodiment of the present invention is a decorative film structure, in which, based on any one of the structures (1) to (9), a decorative film structure is located on the back side of the base film. The total light transmittance of at least one layer on the side is 3% or less.

[Effects of the invention]

According to the present invention, it is possible to provide a decorative film structure in which a decorative film is attached to the back of a transparent base material, thereby suppressing the occurrence of wrinkles and air entrapment.

Description of drawings

FIG. 1 is a schematic cross-sectional view of a first example of the decorative film structure according to the embodiment.

FIG. 2 is a perspective view of the transparent base material viewed from the front surface side.

FIG. 3 is a perspective view of the transparent base material viewed from the back side.

FIG. 4 is a schematic cross-sectional view for explaining the height of the transparent base material.

5 is a schematic cross-sectional view of a second example of the decorative film structure according to the embodiment.

6 is a schematic cross-sectional view of a third example of the decorative film structure according to the embodiment.

7 is a schematic cross-sectional view of a fourth example of the decorative film structure according to the embodiment.

FIG. 8 is a first schematic diagram for explaining the decoration process of vacuum-pressure forming.

FIG. 9 is a second schematic diagram for explaining the decoration process of vacuum-pressure forming.

FIG. 10 is a third schematic diagram for explaining the decoration process of vacuum-pressure forming.

FIG. 11 is a fourth schematic diagram for explaining the decoration process of vacuum-pressure forming.

Figure 12 is a schematic cross-sectional view of the decorative film structure after vacuum-pressure forming.

[Explanation of symbols]

10: Transparent substrate

20: Decorative film

21: Adhesive layer

22: Base film

23: Design layer

24: Resin film

24a: First resin film

24b: Second resin film

25: Back coating

100: Vacuum-pressure forming device

110: Upper forming room

120: Lower forming room

130: Workbench

140: Drive device

150: Vacuum tank

160: Piping

170: Infrared heater

180: Pressure empty tank.

Detailed ways

Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the contents described in the following embodiments, and design changes can be appropriately made within the scope of the structure that satisfies the present invention.

FIG. 1 is a schematic cross-sectional view of a first example of the decorative film structure according to the embodiment. As shown in FIG. 1 , the decorative film structure of the first example includes a transparent base material 10 and a decorative film 20 attached to the back surface of the transparent base material 10 . The decorative film 20 includes a base film 22 and an adhesive layer 21, and is attached to the transparent base material 10 via the adhesive layer 21.

(transparent substrate)

FIG. 2 is a perspective view of the transparent base material viewed from the front surface side. FIG. 3 is a perspective view of the transparent base material viewed from the back side. As shown in FIG. 2 , the transparent base material 10 protrudes toward the front surface side.

Examples of the transparent base material 10 include acrylic resins such as polymethyl methacrylate, resin base materials such as polycarbonate, polyethylene terephthalate, and polystyrene, and glass base materials. Among them, the transparent base material 10 is preferably a glass base material in terms of excellent transparency. The glass base material also has excellent weather resistance, so it is also suitable when the decorative film structure is used for outdoor use.

The transparent base material 10 only needs to be transparent enough to allow the decorative film 20 to be visually recognized from the front surface side through the transparent base material 10 . The total light transmittance is preferably 80% or more, and more preferably the total light transmittance is 80% or more. More than 90. In addition, in this specification, the total light transmittance is a value based on Japanese Industrial Standards (JIS) K 7375.

The transparent base material 10 has a curved surface portion with a curvature radius of 20 mm or more and 100 mm or less. If the curvature radius of the curved portion is less than 20 mm, air will easily remain when the decorative film is attached from the back side of the transparent base material 10 . On the other hand, if the radius of curvature of the curved portion exceeds 100 mm, the three-dimensional effect of the decorative film structure will be insufficient. The radius of curvature is preferably 30 mm or more and 80 mm or less.

The radius of curvature refers to the radius of a circle that approximates the degree of curvature at a certain point on the surface of the transparent base material 10 . The radius of curvature is a value measured on the surface on the back side of the transparent base material 10 . The curvature radius can be measured non-contactly using a laser beam using a profile shape measuring machine (Contracer). As the profile measuring instrument, for example, SV-C3100 manufactured by Mitutoyo Corporation can be used.

The transparent base material 10 is preferably a curved plate-shaped base material. The area of the transparent base material 10 can be appropriately set according to the use. From the viewpoint of easily attaching a decorative film by vacuum-pressure molding or the like, the area of the transparent base material 10 can be, for example, 300 cm ² to 3000 cm ² .

From the viewpoint of obtaining excellent transparency, the thickness of the transparent base material 10 is preferably uniform. In the case where the thickness of the transparent base material 10 is uniform, the curvature radius of the surface on the front surface side of the transparent base material 10 may be similar to the curvature radius of the surface on the back surface side of the transparent base material 10 . In this specification, if the allowable error of the thickness of the transparent base material 10 is, for example, within the allowable error of JIS R 3202; 2011 "Float Flat Glass and Polished Flat Glass", the thickness can be said to be uniform.

In addition, the transparent base material 10 only needs to include a curved portion protruding toward the front surface side and having the predetermined radius of curvature, and the entire base material does not need to be a curved surface. The transparent base material 10 may have a curved surface with a curvature radius of less than 20 mm and more than 100 mm, and a part of the transparent base material 10 may protrude toward the back side.

The curvature radius of the curved portion in at least one of the first direction and the second direction orthogonal to the first direction may be 20 mm or more and 100 mm or less. For example, as shown in FIG. 3 , let any direction along the back surface of the transparent base material 10 be the first direction X, and let any direction orthogonal to the first direction X be the second direction Y.

The transparent base material 10 may be a base material bent in both the first direction X and the second direction Y. That is, the radius of curvature in the first direction X and the radius of curvature in the second direction Y of the curved portion may be 20 mm or more and 100 mm or less. For a base material that is curved in both the first direction X and the second direction Y, it is preferable to attach the decorative film by vacuum-pressure molding or the like that is excellent in following the shape of the base material.

FIG. 4 is a schematic cross-sectional view for explaining the height of the transparent base material. FIG. 4 is a schematic cross-sectional view along the Z line shown in FIG. 2 . The height H of the transparent base material 10 refers to the maximum length of a perpendicular line from the ground surface when the transparent base material 10 is placed on a flat surface to the surface on the back side of the transparent base material 10 . The height of the transparent base material 10 may be, for example, 40 mm to 100 mm. As will be described later, in vacuum-pressure molding or the like, the softened decorative film first comes into contact with the portion protruding toward the back surface side of the transparent base material 10 and is then attached to the portion protruding toward the front surface side. Therefore, the higher the height of the transparent base material 10 , the more the decorative film is attached in an elongated state. Therefore, air can easily enter between the adhesive layer and the transparent base material 10 at the portion protruding toward the front surface side. In this embodiment, a decorative film can also be attached from the back side to a transparent base material with a height of 120 mm or more.

The thickness of the transparent base material 10 is preferably 2 mm or more and 8 mm or less. If the thickness of the transparent base material 10 is less than 2 mm, when the decorative film structure is viewed from the front surface side, a sufficient sense of depth may not be obtained. On the other hand, if the thickness of the transparent base material 10 exceeds 8 mm, the weight increases, and handling may become difficult. The thickness of the transparent base material 10 is more preferably 3 mm or more and 7 mm or less.

The arithmetic average surface roughness Ra of the surface on the adhesive layer 21 side (surface on the back side) of the transparent base material 10 is preferably 0.16 μm or less. If the Ra of the back surface of the transparent base material 10 is 0.16 μm or less, the adhesive force with the adhesive layer 21 can be improved. Therefore, when the decorative film is attached to the transparent base material 10, the generation of an air layer (air entrapment) between the transparent base material 10 and the adhesive layer 21 can be more effectively suppressed. When air entrapment occurs, the air in the air layer expands when immersed in hot water, and the air layer tends to be easily visually recognized in the hot water resistance evaluation. However, by suppressing air entrapment, the hot water resistance is improved. The generation of air layers can also be suppressed during evaluation. In addition, the designability of the decorative film structure viewed from the front surface side can be improved. The Ra of the surface on the back side of the transparent base material 10 is more preferably 0.12 μm or less, and further preferably 0.06 μm or less. In this specification, the arithmetic mean surface roughness Ra and the maximum height Rz described below can be measured using the method based on JIS B 0601:2001. It is preferable that the surface of the back side of the transparent base material 10 is smooth, that is, the numerical values of the above-mentioned Ra and the below-mentioned Rz are low.

The maximum height Rz of the surface on the adhesive layer 21 side (surface on the back side) of the transparent base material 10 is preferably 2.1 μm or less. The reason for this is that when grooves or cracks are formed on the back surface of the transparent base material 10 , it may be difficult to attach the decorative film by vacuum-pressure molding or the like. In addition, as described above, the adhesive force with the adhesive layer 21 can be improved. The Rz of the surface on the back side of the transparent base material 10 is more preferably 1.6 μm or less, further preferably 1.3 μm or less, and particularly preferably 1.0 μm or less.

(Substrate film)

The base film 22 is a film serving as a base material of the decorative film 20 and preferably contains a thermoplastic resin. Examples of the thermoplastic resin include polyvinyl chloride; polyolefins such as polyethylene and polypropylene; acrylic resins; polycarbonate resins; urethane resins and the like.

As the thermoplastic resin, polyvinyl chloride is preferred. When the resin film of the present invention is attached to a base material, a polyvinyl chloride film containing polyvinyl chloride as a main resin component has good elongation, so it follows the surface shape of the base material and is less likely to break. In addition, when attached to a base material and laminate-integrated molding is performed, molding can be performed at a relatively low temperature (approximately 120°C). Containing polyvinyl chloride as the main resin component means that the content of polyvinyl chloride is 50% by weight or more in the total resin components contained in the polyvinyl chloride film. In addition, "relatively low temperature" means a lower temperature than the molding temperature (more than 130°C) when molding resins other than polyvinyl chloride and acrylic resin (for example, polyethylene terephthalate).

Examples of the polyvinyl chloride include homopolymers of vinyl chloride and copolymers of vinyl chloride and other monomers.

Examples of the other monomers include vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene, and styrene; and (meth)acrylic acids such as methyl acrylate, ethyl acrylate, and methyl methacrylate. Esters; maleic acid diesters such as dibutyl maleate and diethyl maleate; fumaric acid diesters such as dibutyl fumarate and diethyl fumarate; acrylonitrile, methacrylonitrile, etc. Acrylonitrile; vinyl halides such as vinylidene chloride and vinyl bromide; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, etc. These may be used individually or in combination of 2 or more types.

The content of the other monomers in the copolymer is usually 50% by weight or less, preferably 10% by weight or less. If it exceeds 50% by weight, the bending resistance of the film may decrease. Among the polyvinyl chloride, a homopolymer of vinyl chloride is preferred from the viewpoint of obtaining dimensional stability.

The average degree of polymerization of the polyvinyl chloride may be, for example, 750 to 1,300. The preferred lower limit of the average degree of polymerization is 800. If the average degree of polymerization is in the range of 750 to 1300, the formability at a relatively low temperature will be good. On the other hand, when the average polymerization degree is less than 750, when the decorative film of the present invention and the base material are laminated and integrated, the film may not be fully stretched and may not be able to follow the shape of the base material. On the other hand, if the average degree of polymerization exceeds 1,300, the processability in calendering for obtaining a polyvinyl chloride film decreases, and the appearance of the film surface may deteriorate. In addition, the shrinkage rate of the film after molding becomes large, making it difficult to maintain the shape. The average degree of polymerization of polyvinyl chloride means the average degree of polymerization measured based on JIS K6721 "Testing Methods for Polyvinyl Chloride".

The polyvinyl chloride film preferably contains a plasticizer. The content of the plasticizer is preferably not less than 7 parts by weight and not more than 35 parts by weight relative to 100 parts by weight of polyvinyl chloride. By setting the content of the plasticizer within the above range, flexibility or formability suitable for calendering and the like can be obtained. In addition, an elongation rate suitable for attaching the decorative film of the present invention to a base material and performing vacuum-pressure molding or the like can be obtained. If the content of the plasticizer is less than 7 parts by weight, the polyvinyl chloride film becomes too hard and may break during molding. On the other hand, if it exceeds 35 parts by weight, the polyvinyl chloride film may become too soft and the workability may decrease. A more preferable lower limit of the plasticizer content is 15 parts by weight and a more preferable upper limit is 30 parts by weight relative to 100 parts by weight of polyvinyl chloride.

Examples of the plasticizer include Bis(2-ethylhexyl)phthalate (DOP), Diisononyl phthalate (DINP), Diisodecyl phthalate (DIDP), diundecyl phthalate (DUP) and other phthalate diesters; dioctyl adipate, sebacic acid Aliphatic dibasic acid diesters such as dioctyl ester; phosphate triesters such as tricresyl phosphate and trioctyl phosphate; epoxy plasticizers such as epoxidized soybean oil and epoxy resin; high molecular polyester plasticizers wait. Among these, phthalic acid diesters are preferred. DUP is suitable because it is not subject to various environmental restrictions, has less odor during film forming, and causes less contamination of the forming machine during film forming.

The thickness of the base film 22 is preferably 50 μm or more and 150 μm or less. If the thickness is less than 50 μm, roll molding may be difficult. Specifically, when foreign matter or resin deterioration products generated during processing are mixed in, the resin film may be cracked or have holes during calendering. On the other hand, if the thickness exceeds 150 μm, heat may be insufficient or the processing speed may be reduced during thermal lamination with other films or the like. In addition, since the thickness of the entire decorative film increases, the processability when laminating and integrating the decorative film 20 and the transparent base material 10 may be reduced. The thickness is more preferably 80 μm or more and 100 μm or less. In addition, the thickness is the thickness of one base film 22 .

The base film 22 may be light-transmitting or light-shielding. As will be described later, when a design layer is disposed on the back side of the base film 22, the base film 22 is preferably transparent. For example, the total light transmittance It is preferably 70% or more, and more preferably 80% or more.

When the background is not visible when viewed from the front surface side of the decorative film formed body, the base film 22 is preferably light-shielding. For example, the total light transmittance is preferably 3% or less, and more preferably 2.8% or less.

When the base film 22 is used to impart color to the decorative film 20 , the base film 22 may be a colored film containing a colorant.

The base film 22 may be a single layer or multiple layers. When the base film 22 is multi-layered, a light-shielding film may be laminated on the back surface of the light-transmitting film.

The base film 22 can be produced by calendering. Here, calendering refers to a method of calendering and shaping raw resin (resin composition) with a pair of rollers.

(adhesive layer)

The adhesive layer 21 is a cured product of the adhesive composition, and is a layer that adheres the transparent base material 10 and the base film 22 to each other. The adhesive layer 21 is in contact with the transparent base material 10 . It is preferable that the surface of the adhesive layer 21 opposite to the surface in contact with the transparent base material 10 is in contact with the base film 22 .

The adhesive composition includes a main agent and a leveling agent. The main ingredient refers to a compound that exhibits adhesive force, and its content is 80% or more relative to the components after removing the solvent from the adhesive composition.

The leveling agent is also called a defoaming agent and a surface conditioner and has a surface-active effect. When the adhesive composition is applied to form an adhesive layer, the surface of the coating film of the adhesive composition can be oriented to suppress an increase in the viscosity of the adhesive composition due to volatilization of the solvent in the adhesive composition. In addition, by orienting the surface of the coating film of the adhesive composition, the surface tension of the adhesive composition can be reduced, dents or pits caused by low surface tension substances can be eliminated, and the surface of the adhesive layer can be suppressed from becoming uneven.

By including the leveling agent in the adhesive composition, the occurrence of unevenness on the surface of the adhesive layer 21 can be suppressed, and the friction between the adhesive layer 21 and the transparent base material 10 and between the adhesive layer 21 and the base film 22 can be improved. Adhesion. Therefore, when the decorative film is attached from the back side of the transparent base material 10, it is possible to suppress the occurrence of wrinkles in the decorative film or the occurrence of air trapping between the base material and the decorative film. In addition, since the adhesive composition contains a leveling agent, visual recognition of unevenness in the adhesive layer 21 and the transparent base material 10 can be suppressed, thereby improving the aesthetics of the decorative film structure when viewed from the front surface side.

In addition, the air entrapment is an air layer generated between the transparent base material 10 and the adhesive layer 21 when the decorative film is attached to the transparent base material 10 . The air entrapment occurs because the adhesive force of the adhesive layer 21 with respect to the transparent base material 10 is insufficient, so that a part of the interface between the transparent base material 10 and the adhesive layer 21 is peeled off and air is mixed in. The wrinkles refer to local depressions on the adhesive surface of the adhesive layer 21 (the surface on the side facing the transparent base material 10 ). The local depression of the adhesive surface is caused by the occurrence of the depression or pit when the surface tension of the coating film surface of the adhesive composition applied to the adherend is insufficiently reduced.

As will be described later, when a decorative film is attached from the back side of the transparent base material 10 having a curved portion protruding from the front surface side, the softened decorative film 20 is first combined with the transparent base material by vacuum-pressure molding or the like. The protruding portions on the back side of the transparent base material 10 are in contact with each other, and then are attached from the protruding portions toward the center of the transparent base material along the surface of the back side of the transparent base material 10 . The curved portion of the transparent base material contacts the base film and the adhesive layer in a stretched state. When the decorative film structure is cooled, the adhesive force between the transparent base material and the adhesive layer decreases due to the stress of the base film. Lower, sometimes part of it will peel off (enter air). Therefore, it is preferable to provide an adhesive layer with high adhesive force.

Examples of the leveling agent include acrylic polymer-based, silicone-based, and vinyl polymer-based leveling agents. From the viewpoint of reducing surface tension while maintaining adhesion, vinyl polymer-based leveling agents are preferred. From the viewpoint of high surface tension-reducing effect, acrylic polymer-based, silicone-based, or vinyl polymer-based leveling agents can also be used. Examples of the vinyl polymer-based leveling agent include "Dapor SN-530" manufactured by San Nopco Co., Ltd., and the acrylic polymer-based leveling agent. Agents include "Dapor SN-348" and "Dapor SN-354" manufactured by SanNopco Co., Ltd. As the silicone-based leveling agent, Examples include "Dapor SN-359" manufactured by San Nopco Co., Ltd.

The content of the leveling agent relative to 100 parts by weight of the main agent is preferably 0.03 to 0.6 parts by weight. By setting the content of the leveling agent within the above range, the adhesive force between the transparent base material 10 and the adhesive layer 21 can be further improved, so that the occurrence of wrinkles and air entrapment can be effectively suppressed. In addition, the reduction in hot water resistance caused by air entrapment can also be suppressed.

If the content of the leveling agent exceeds 0.6 parts by weight, the adhesive force may decrease and the hot water resistance may decrease. The content of the leveling agent is more preferably 0.05 to 0.30 parts by weight.

Examples of the adhesive composition include polyester-based, acrylic-based, rubber-based, silicone-based, and the like adhesive compositions. Among them, the adhesive composition preferably contains a polyester-based compound as a main ingredient in terms of excellent adhesiveness and heat resistance at high temperatures. By using a polyester-based adhesive containing a polyester-based compound as a main ingredient, sufficient adhesion can be easily obtained even when the decorative film is attached from the back side of a base material with a large curvature. The adhesive composition may further include an organic solvent.

The polyester-based compound is preferably a copolymerized polyester. The copolyester is more preferably a saturated copolyester. Examples of the polyester-based adhesive agent containing saturated copolymerized polyester include "Byron (registered trademark) BX-10ss" manufactured by Toyobo Co., Ltd. and the like.

The adhesive composition is preferably a hot melt adhesive. The adhesive is more preferably a polyester-based hot melt adhesive. The adhesive layer using a hot melt adhesive only needs to exhibit adhesive force at the molding temperature of the decorative film 20 (for example, 110° C. to 140° C.).

The adhesive composition preferably further contains a hardener. As the hardening agent, an isocyanate-based hardening agent is preferred. The isocyanate hardener preferably contains xylylenediisocyanate (XDI) such as isocyanate; hydrogenated xylylene such as 1,4-bis(isocyanatomethyl)cyclohexane; H6XDI; isophorone diisocyanate (IPDI); hexamethylene diisocyanate (HDI); 1,5-pentamethylene diisocyanate and other pentamethylene diisocyanates (pentamethylene diisocyanate, PDI) etc. Among these, an isocyanate-based hardener containing 1,5-pentamethylene diisocyanate is more preferred. Specific examples of the isocyanate-based hardener containing 1,5-pentamethylene diisocyanate include "STABiO (registered trademark) D-370N" manufactured by Mitsui Chemicals Co., Ltd.

The content of the hardener is preferably 1.0 to 3.5 parts by weight relative to 100 parts by weight of the main agent. If the content of the hardener is less than 1.0 parts by weight, heat resistance may become insufficient. The content of the hardener is more preferably 1.4 to 2.5 parts by weight.

When the adhesive composition contains a polyester-based compound as a main ingredient, the adhesive composition preferably further contains an isocyanate-based hardener, and the NCO index represented by the following formula (1) is 0.4 or more and 1.6 the following. By setting the NCO index to 0.4 to 1.6, even if air is trapped, since the adhesive layer 21 is hard, the thermal expansion of the air layer can be suppressed and hot water resistance can be improved. Specifically, when the decorative film structure is immersed in hot water at 100° C. for 1 hour, the generation of an air layer between the transparent base material and the adhesive layer can be suppressed. The NCO index is more preferably 0.7 to 1.3.

NCO index=Number of moles of NCO groups derived from the isocyanate component contained in the isocyanate-based hardener/Number of moles of OH groups derived from the polyester contained in the polyester-based compound (1)

The adhesive composition may further include a silane coupling agent. By including a silane coupling agent, adhesion can be improved. The content of the silane coupling agent relative to 100 parts by weight of the main agent is preferably 0.2 to 0.8 parts by weight, and more preferably 0.4 to 0.5 parts by weight.

The adhesive layer 21 is preferably transparent. The total light transmittance of the adhesive layer 21 is preferably 70% or more, and more preferably 80% or more.

The thickness of the adhesive layer 21 is preferably 20 μm or more and 60 μm or less. If the thickness is less than 20 μm, sufficient adhesion to the transparent base material 10 may not be obtained. The thickness is more preferably 35 μm or more and 50 μm or less.

The method of forming the adhesive layer 21 is not particularly limited. For example, a conventionally known method such as a method of applying an adhesive composition on a separator using a bar coater and drying the adhesive composition can be used. Then, the decorative film can be manufactured by bonding the surface opposite to the partition to the base film 22 . The barrier protection adhesive layer 21 is removed when the decorative film is attached to the transparent base material 10, and the exposed adhesive layer 21 is made to contact the back surface of the transparent base material 10 for attachment.

The decorative film 20 may further have a design layer 23 on the back side of the base film 22 . 5 is a schematic cross-sectional view of a second example of the decorative film structure according to the embodiment. FIG. 5 illustrates a case where the decorative film 20 has an adhesive layer 21, a base film 22, and a design layer 23 in order from the transparent base material 10 side.

(design layer)

The design layer 23 is a layer that imparts a design such as color or pattern to the decorative film, and is obtained by printing using ink or the like, for example. The ink may contain a colorant, a binder resin, a solvent, etc. Examples of the colorant include pigments, dyes, inorganic fillers such as titanium oxide, and the like. Examples of the binder resin include vinyl acetate, acrylic resin, and the like. The thickness of the design layer 23 is, for example, 1 μm to 10 μm.

The printing method is not particularly limited, and gravure printing, offset printing, flexographic printing, screen printing, etc. can be used. From the viewpoint of good printability on resin films such as vinyl chloride resin films, gravure printing is preferred.

In the second example, for example, the design layer 23 is printed on one surface of the base film 22 , and one surface of the base film 22 and the adhesive layer formed on the barrier are on the opposite side to the barrier. The surface can be laminated to make a decorative film. By disposing the base film 22 between the design layer 23 and the adhesive layer 21 , it is possible to suppress the ink from bleeding out of the design layer 23 due to components contained in the adhesive layer 21 .

In the second example, the third example, and the fourth example described below in which the design layer is arranged on the back surface of the base film 22, in order that the design layer 23 can be visually recognized from the front surface side of the decorative film structure, the base film 22 is preferably Transparent, for example, the total light transmittance is preferably 70% or more, more preferably 80% or more.

The decorative film 20 may further have a resin film 24 on the back side of the base film 22 . FIG. 6 is a schematic cross-sectional view of the decorative film structure of the third example. In FIG. 6 , a case where the decorative film 20 has an adhesive layer 21, a base film 22, a design layer 23, and a resin film 24 in order from the transparent base material 10 side is illustrated. In addition, the decorative film 20 may not have the design layer 23, but may have the adhesive layer 21, the base film 22, and the resin film 24 in order from the transparent base material 10 side.

(resin film)

The resin film 24 is a layer that improves the design of the decorative film and preferably contains a thermoplastic resin. Examples of the thermoplastic resin include polyvinyl chloride; polyolefins such as polyethylene and polypropylene; acrylic resins, polycarbonate resins, and urethane resins.

The resin film 24 preferably has the same formability as the base film 22 . When the base film 22 is a polyvinyl chloride film, the resin film 24 is also preferably a polyvinyl chloride film. As the resin film 24, the same polyvinyl chloride film as described for the base film 22 can be used in terms of the average polymerization degree of the polyvinyl chloride and the type and content of the plasticizer.

The resin film 24 may be a single-layer film as shown in FIG. 6 , or a multi-layer film in which a first resin film 24 a and a second resin film 24 b are laminated as shown in FIG. 7 to be described later. In this specification, when the first resin film 24a and the second resin film 24b are not specifically distinguished, they are simply called the resin film 24. From the viewpoint of improving the designability of the decorative film, the resin film 24 is preferably a colored film.

The thickness of one resin film 24 is preferably 50 μm or more and 150 μm or less, and more preferably 80 μm or more and 100 μm or less.

The resin film 24 may be light-transmitting or light-shielding. When the resin film 24 is a multilayer film, the resin film disposed on the front surface side may be translucent. In addition, when a back surface coating layer to be described later is disposed on the back surface side of the resin film 24, the resin film 24 may be translucent. When the resin film 24 is arranged on the backmost surface of the decorative film, the resin film 24 may have light-shielding properties.

The decorative film 20 may further have a back coating layer 25 on the back side of the base film 22 . 7 is a schematic cross-sectional view of a fourth example of the decorative film structure according to the embodiment. 7 illustrates a case where the decorative film 20 has an adhesive layer 21, a base film 22, a design layer 23, a resin film 24, and a back coating layer 25 in order from the transparent base material 10 side.

(back coating)

The back coating layer 25 is a layer that improves the weather resistance and damage resistance of the decorative film 20 . The back coating layer 25 is preferably disposed on the rearmost surface of the decorative film 20 .

Examples of materials for the back coat layer 25 include coating agents containing urethane resin, acrylic resin, polyester resin, and the like. As the urethane coating agent, Q-563 manufactured by Mitsui Chemicals Co., Ltd., etc. can be used.

The back coating 25 may further include polyethylene resin, polytetrafluoroethylene (PTFE), or the like.

The thickness of the back coat layer 25 is preferably 1 μm or more and 30 μm or less, and more preferably 3 μm or more and 10 μm or less.

The total light transmittance of at least one layer located on the back side of the base film 22 is preferably 3% or less. In the second example, the total light transmittance of the design layer 23 is more preferably 3% or less. In the third example, the total light transmittance of at least one of the design layer 23 and the resin film 24 is more preferably 3% or less. In the fourth example, the total light transmittance of at least one layer among the design layer 23, the resin film 24, and the back coating 25 is more preferably 3% or less.

(decorative film)

The total thickness of the decorative film is preferably 100 μm to 450 μm, and more preferably 240 μm to 350 μm.

(How to form decorative film)

An example of a method for attaching a decorative film to a transparent base material is a method of heating the decorative film and attaching it to the transparent base material. Examples include in-mold forming such as thermoforming, vacuum forming, pressure forming, and vacuum-pressure forming.

Among them, vacuum molding, pressure molding, and vacuum-pressure molding (vacuum-pressure molding, etc.) are preferable in terms of easy adhesion to a base material with a complex three-dimensional shape. In addition, for a base material such as glass that is easily broken, vacuum forming, pressure forming, or vacuum-pressure forming without using a jig is suitable. Vacuum forming is a molding method in which the molding chamber of the molding machine equipped with a base material and decorative film is set to a vacuum, and the decorative film is attached to the base material. Pressure forming is a molding chamber that uses compressed air to pressurize the decorative film. A forming method that adheres to the base material. Vacuum-pressure molding is a molding method in which the molding chamber is evacuated and then pressurized under vacuum conditions to attach the decorative film to the base material.

The following diagram explains the attachment method using vacuum-pressure forming. 8 to 11 are first to fourth schematic diagrams for explaining the decoration process of vacuum-pressure forming. As a vacuum-pressure forming device, a three-dimensional overlay method (TOM) molding machine (NGF-0406-T manufactured by Busch Vacuum Co., Ltd.) or the like can be used.

First, as shown in FIG. 8 , the transparent base material 10 and the decorative film 20 are placed in the molding chamber under atmospheric pressure. The vacuum-pressure forming apparatus 100 includes upper and lower forming chambers (an upper forming chamber 110 and a lower forming chamber 120). The transparent base material 10 is placed on the workbench 130 in the lower forming chamber 120 , and the decorative film 20 laminated on the transparent base material 10 is placed on the upper surface of the lower forming chamber 120 . The transparent base material 10 is arranged so that the back side (the surface opposite to the protruding surface) faces the decorative film 20 . Then, the driving device 140 sets the upper and lower molding chambers in an airtight state, and vacuums the upper and lower molding chambers from the vacuum tank 150 through the pipe 160 to bring them into a vacuum state (an extremely low pressure state).

When the transparent base material 10 is installed on the workbench 130, by arranging the transparent base material 10 obliquely, air can be easily discharged during attachment, and the adhesion between the adhesive layer and the transparent base material can be improved.

Then, as shown in FIG. 9 , while maintaining the vacuum state, the infrared heater 170 is turned on to heat the decorative film 20 . Thereby, the decorative film 20 is softened and can be attached along the surface shape of the transparent base material 10 . The heating temperature is the forming temperature of the decorative film 20 . The molding temperature is, for example, 110°C to 140°C. Especially when the base material is glass, the heating temperature is preferably 120°C to 130°C.

Next, as shown in FIG. 10 , the workbench 130 in the lower forming chamber 120 is raised by the driving device 140 to bring the transparent base material 10 into contact with the softened decorative film 20 . Then, as shown in FIG. 11 , the vacuum on the upper forming chamber 110 side is released to the atmospheric pressure state (the inside of the lower forming chamber 120 is in a vacuum state), and compressed air is further sent from the pressure tank 180 into the upper forming chamber 110 . This presses the decorative film 20 to the transparent substrate 10 and stacks it along its shape. Thereby, the decorative film 20 is laminated|stacked on the back surface of the transparent base material 10.

Then, the inside of the upper molding chamber 110 and the lower molding chamber 120 are respectively returned to the atmospheric pressure state, the upper molding chamber 110 is raised, and the transparent base material 10 with the decorative film 20 attached is taken out. By cutting the excess decorative film 20, a decorative film formed body is obtained. Figure 12 is a schematic cross-sectional view of the decorative film structure after vacuum-pressure forming. As shown in FIG. 12 , in addition to the back surface of the transparent base material 10 , the side surfaces may also be covered by the decorative film 20 .

[Example]

Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not limited only to these Examples.

(Example 1)

Using the method shown below, a decorative film laminate in which a transparent base material, an adhesive layer, a base film, a design layer, a first resin film, a second resin film, and a back coating layer were laminated in this order was produced.

＜Transparent substrate＞

As a transparent base material, a glass transparent base material (glass base material) with a thickness of 5 mm that protruded toward the front surface side and had different curvature radii was prepared. The thickness of each glass substrate is uniform, and the total light transmittance is 92%. The radius of curvature of the glass base material was measured using the following method, and the results are shown in Table 1.

(Measuring equipment)

Measuring equipment: Surface roughness-contour shape measuring machine: SV-C3100 manufactured by Mitutoyo Corporation

Stylus: Stylus SPH-71

(Measurement conditions)

Speed: 0.5mm/sec

Moving distance: 100mm

Sampling method: line segment spacing (0.005mm)

(calculation method)

Analysis software: "Formtracepak" manufactured by Mitutoyo Corporation

For the curve portion judged by the software to have the largest radius of curvature, the average value of three measurements was obtained using the manual three-point method using the software.

The arithmetic mean surface roughness of the surface on the back side of the glass base material was measured under the following measurement conditions using the method based on JIS B0601:2001, and the results are shown in Table 1.

(Measurement conditions)

Curve: R

Filter: Gaussian (GAUSS)

Cutoff value λc: 0.8mm

Cutoff value λs: 2.5μm

Number of intervals: 15mm

Run-up: in order

Measuring speed: 0.5mm/second

＜Preparation of film laminate＞

To 100 parts by weight of polyvinyl chloride with an average degree of polymerization of 800, 25 parts by weight of di-undecyl phthalate (DUP) was added as a plasticizer to prepare a vinyl chloride resin composition. The obtained vinyl chloride resin composition was melt-kneaded using a Banbury mixer, and then calendered to produce a base film having a thickness of 90 μm. The total light transmittance of the base film is 83.1%.

Pigments were added to the vinyl chloride resin composition, respectively, to prepare first resin films and second resin films of different colors with a thickness of 90 μm.

A design layer with a thickness of 2 μm was printed on one side of the base film by gravure printing using ink. The base film, the first resin film, and the second resin film are thermally laminated so that the design layer is in contact with the first resin film.

The surface of the second resin film opposite to the surface in contact with the first resin film was coated with a urethane coating agent (Q-563 manufactured by Mitsui Chemicals Co., Ltd.) with titanium oxide added thereto. A coating agent obtained by using a colorant, and a back coating layer with a thickness of 3 μm was laminated to produce a laminate in which a base film, a design layer, a first resin film, a second resin film, and a back coating layer were laminated.

＜Preparation of adhesive layer＞

The following materials were used, and a polyester-based adhesive, an isocyanate-based hardener, and a leveling agent were added according to the formula shown in Table 1 to prepare a polyester-based adhesive composition. The obtained polyester-based adhesive composition was applied to the separator to prepare an adhesive layer with a dry thickness of 40 μm. In addition, the content of the isocyanate-based hardener and the content of the leveling agent in Table 1 are the content relative to 100 parts by weight of the main agent (polyester-based compound). The total light transmittance of the adhesive layer is 80% or more.

(Material)

·Polyester-based adhesive: "Byron BX-10ss" manufactured by Toyobo Co., Ltd. (solid content: 30%, hydroxyl value: 8 mgKOH/g)

The solid content is the content of the main agent (saturated copolyester) contained in the polyester-based adhesive.

·Isocyanate hardener: "STABiO D-370N" manufactured by Mitsui Chemicals Co., Ltd. (solid content: 100%, NCO%: 25%)

·Leveling agent: "Dapor SN-530" manufactured by San Nopco Co., Ltd.

＜Production of decorative film＞

A decorative film was produced by bonding the surface of the adhesive layer on the opposite side to the separator and the surface of the base film of the film laminate on the opposite side to the design layer to each other.

＜Decorative film structure＞

The adhesive layer of the decorative film from which the partition was peeled was arranged so that it faced the surface of the back side of the transparent base material, and vacuum-pressure molding was performed at a molding temperature of 125°C to produce a product that was attached to the back side of the transparent base material. The decorative film structure of Example 1 having a decorative film. Vacuum-pressure forming was performed using a TOM forming machine (NGF-0406-T) manufactured by Busch Vacuum Co., Ltd.

(Example 2 and Example 3)

Decorative film structures of Examples 2 and 3 were produced in the same manner as Example 1 except that the structure of the adhesive layer was changed as shown in Table 1 using the same glass base material as Example 1. .

(Example 4 to Example 6, Comparative Example 1 to Comparative Example 3)

Examples 4 to 6 and Comparative Examples 1 to Comparative Examples were produced in the same manner as Example 1, except that the structure of the adhesive layer was changed as shown in Table 1 using the glass base material shown in Table 1. The decorative film structure of Example 3.

＜Evaluation test＞

The decorative film structures of Examples and Comparative Examples were evaluated as follows, and the results are shown in Table 1.

(production of wrinkles)

The decorative film structure was visually observed from the front surface side in a state of leaving it still indoors (under normal fluorescent lighting), and evaluated according to the following evaluation criteria. The wrinkles are wrinkles generated on the surface of the adhesive layer due to depressions in the adhesive layer.

〇: No wrinkles are visible visually.

×: Wrinkles are visible visually.

(air entrapment)

From the front surface side, the decorative film structure is placed in a state where a normal fluorescent lamp is lit indoors (hereinafter, under a fluorescent lamp), or a light emitting diode (light emitting diode, LED) is further used in a state where the decorative film structure is left still in a room (under a normal fluorescent lamp). The decorative film structure was visually observed in a state where the decorative film structure was irradiated with light (hereinafter, LED light irradiation), and evaluated based on the following evaluation criteria. The air layer in the evaluation of air entrapment and the evaluation of hot water resistance described below refers to the air entrainment generated between the transparent base material and the adhesive layer. By irradiating the decorative film structure with light locally using LED lights, finer air layers can be detected. For example, an air layer ^above 0.02mm reflects LED light and appears to glow.

◎: The air layer cannot be visually recognized under fluorescent lights or LED light.

〇: The air layer cannot be visually recognized under fluorescent lights, but the air layer can be visually recognized when illuminated by LED light.

×: The air layer is visually recognized under fluorescent light.

(hot water resistance)

The decorative film structure was immersed in hot water at 100° C. for 1 hour, and then visually observed from the front surface side, and evaluated according to the following evaluation criteria.

◎: The air layer cannot be visually recognized under fluorescent lights or LED light.

〇: The air layer cannot be visually recognized under fluorescent lights, but the air layer can be visually recognized when illuminated by LED light.

×: The air layer is visually recognized under fluorescent light.

Examples 1 to 6 in which the radius of curvature of the transparent base material was 20 mm or more and 100 mm or less, and the adhesive layer contained a leveling agent, all suppressed the occurrence of wrinkles and air entrapment. Comparison between Example 5 and Example 6 confirmed that the smoother the surface of the side facing the adhesive layer of the transparent base material (the lower Ra and Rz), the more the occurrence of air entrainment can be suppressed. By including a leveling agent, the adhesive surface of the adhesive layer becomes smooth. Therefore, by attaching the adhesive layer with a smooth adhesive surface to a transparent base material with a smooth surface, the occurrence of air entrapment can be particularly suppressed. Since air entrainment is suppressed and there is no tiny air (air layer), hot water resistance can also be improved.

Comparative Examples 1 and 2 in which a leveling agent was not added to the adhesive layer caused wrinkles and air entrapment. Even in Comparative Example 3 in which the transparent base material has a large radius of curvature, wrinkles occur unless a leveling agent is added.

Claims (10)

1. A decorative film structure, including a transparent base material and a decorative film attached to the back side of the transparent base material. In the decorative film structure, The transparent base material has a curved portion protruding toward the front surface side and having a curvature radius of 20 mm or more and 100 mm or less, The decorative film includes a base film and an adhesive layer, and is attached to the transparent base material through the adhesive layer, The adhesive layer is a cured product of an adhesive composition containing a main agent and a leveling agent. 2. The decorative film structure according to claim 1, wherein the arithmetic mean surface roughness Ra of the surface of the transparent base material on the adhesive layer side is 0.16 μm or less. 3. The decorative film structure according to claim 1, wherein the adhesive composition contains a polyester compound as the main ingredient. 4. The decorative film structure according to claim 3, wherein the adhesive composition further contains an isocyanate-based hardener, The NCO index represented by the following formula (1) is 0.4 or more and 1.6 or less: NCO index=the number of moles of NCO groups derived from the isocyanate component contained in the isocyanate-based hardener/the number of moles of OH groups derived from polyester contained in the polyester-based compound (1). 5. The decorative film structure according to claim 1, wherein the content of the leveling agent is 0.03 to 0.6 parts by weight relative to 100 parts by weight of the main agent. 6. The decorative film structure according to claim 1, wherein the transparent base material is a glass base material. 7. The decorative film structure according to claim 1, wherein the decorative film has the adhesive layer, the base film, and a design layer in order from the transparent base material side. 8. The decorative film structure according to claim 1, wherein the decorative film has the adhesive layer, the base film, a design layer, and a resin film in order from the transparent base material side. 9. The decorative film structure according to claim 1, wherein the decorative film has the adhesive layer, the base film, a design layer, a resin film, and a back coating in order from the transparent base material side. layer. The decorative film structure according to any one of claims 7 to 9, wherein the total light transmittance of at least one layer located on the back side of the base film is 3% or less.