CN117162628A

CN117162628A - decorative film structure

Info

Publication number: CN117162628A
Application number: CN202310596217.2A
Authority: CN
Inventors: 中见正宏
Original assignee: Bando Chemical Industries Ltd
Current assignee: Bando Chemical Industries Ltd
Priority date: 2022-06-02
Filing date: 2023-05-25
Publication date: 2023-12-05
Also published as: JP2023177681A

Abstract

The invention provides a decorative film structure, which is characterized in that a decorative film is attached to the back surface of a transparent base material, and generation of wrinkles and generation of air clamping are restrained. A decorative film structure comprising a transparent substrate and a decorative film attached to the back surface of the transparent substrate, wherein the transparent substrate has a curved surface portion protruding toward the front surface side and having a radius of curvature of 20mm or more and 100mm or less, the decorative film comprises a substrate film and an adhesive layer, the decorative film is attached to the transparent substrate via the adhesive layer, and the adhesive layer is a cured product of an adhesive composition comprising a main agent and a leveling agent.

Description

Decorative film structure

Technical Field

The following disclosure relates to a decorative film structure.

Background

Conventionally, a decorative film is attached to a molded article to impart a design such as color, pattern, or character to the molded article. In addition, a structure in which a decorative film is attached to the back surface of a base material and the design can be visually recognized from the front surface of the base material has been studied (for example, patent document 1). As a method for producing a decorative molded article, a method of attaching a decorative film using vacuum molding, vacuum-pressure air molding, or the like is known (for example, patent document 2).

Patent document 1 discloses a decorative board, which is characterized by comprising: a substrate having a plate shape, wherein the plate thickness is smoothly graded so that one of the main surfaces is flat and the back surface of the main surface has a concave-convex shape, and the substrate is formed of a colored transparent resin, and the light transmittance is also smoothly graded with the variation of the plate thickness; and a sheet material having a curved plate shape having the same concave-convex shape as the back surface of the base material, wherein the sheet material has a uniform plate thickness, one of the surfaces is printed and bonded in close contact with the back surface of the base material, and the printed surface is visually recognized as a gradation from the flat main surface side of the base material by gradual change of the transmittance of the base material.

Patent document 2 discloses a method for producing a laminated molded article having a lamination step (1), wherein an adhesive sheet having an adhesive layer disposed on one surface of an extensible release film is laminated on the surface of an uneven molded article by vacuum molding, pressure air molding or vacuum-pressure air molding, and the adhesive layer is disposed on the uneven molded article side in the lamination step (1).

[ Prior Art literature ]

[ patent literature ]

Patent document 1 japanese patent laid-open publication No. 2011-5687

[ patent document 2] Japanese patent laid-open No. 2015-196289

Disclosure of Invention

[ problem to be solved by the invention ]

As a method of attaching a decorative film to a substrate and imparting a design, a method of attaching a decorative film from the front side of a substrate is generally used, but a sufficient gloss or a feeling of depth may not be obtained. In the case of providing a design from the back side of a substrate, decoration using a decorative film is easy even if the substrate is flat, but in the case of attaching a decorative film to a substrate having a certain radius of curvature from the back side, wrinkles may occur in the decorative film at the time of decoration molding or air may be interposed between the substrate and the decorative film.

In patent document 1, the plate thickness is smoothly graded so that one of the main surfaces is flat and the back surface of the main surface has a concave-convex shape (claim 1), and the thickness of the plate portion is in the range of 0.15mm to 0.188mm (paragraph [0020 ]), and the concave-convex difference is very small, which is 0.038mm.

The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a decorative film structure in which a decorative film is attached to the back surface side of a transparent base material, and the occurrence of wrinkles and the occurrence of air entrapment are suppressed.

[ means of solving the problems ]

(1) An embodiment of the present invention is a decorative film structure including a transparent substrate and a decorative film attached to a back surface of the transparent substrate, wherein the transparent substrate has a curved surface portion protruding toward a front surface side and having a radius of curvature of 20mm or more and 100mm or less, the decorative film includes a substrate film and an adhesive layer attached to the transparent substrate via the adhesive layer, and the adhesive layer is a cured product of an adhesive composition including a main agent and a leveling agent.

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

(3) In addition, an embodiment of the present invention is a decorative film structure, wherein the adhesive composition contains a polyester compound as the main agent in addition to the structure of (1) or (2).

(4) In addition, an embodiment of the present invention is a decorative film structure, wherein the adhesive composition further comprises an isocyanate-based curing agent in addition to the structure of (3), and the NCO index represented by the following formula (1) is 0.4 to 1.6.

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

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

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

(7) In addition, an embodiment of the present invention is a decorative film structure, wherein the decorative film has the adhesive layer, the base film, and a design layer in this order from the transparent base side in any one of the structures (1) to (6).

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

(9) In addition, an embodiment of the present invention is a decorative film structure, wherein the decorative film has the adhesive layer, the base film, a design layer, a resin film, and a back surface coating layer in this order from the transparent base side in any one of the structures (1) to (6).

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

[ Effect of the invention ]

The present invention provides a decorative film structure in which a decorative film is attached to the back surface of a transparent substrate, and the occurrence of wrinkles and air entrapment is suppressed.

Drawings

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

Fig. 2 is a perspective view of the transparent substrate from the front surface side.

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

Fig. 4 is a schematic cross-sectional view for explaining the height of the transparent substrate.

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

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

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

Fig. 8 is a first schematic view for explaining a decoration process of performing vacuum-pressure forming.

Fig. 9 is a second schematic diagram for explaining a decoration process of performing vacuum-pressure air forming.

Fig. 10 is a third schematic view for explaining a decoration process of performing vacuum-pressure air forming.

Fig. 11 is a fourth schematic view for explaining a decoration process of performing vacuum-pressure forming.

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

[ description of symbols ]

10: transparent substrate

20: decorative film

21: adhesive layer

22: substrate film

23: design layer

24: resin film

24a: first resin film

24b: second resin film

25: back coating

100: vacuum-pressure air forming device

110: upper forming chamber

120: lower forming chamber

130: working table

140: driving device

150: vacuum tank

160: piping arrangement

170: infrared heater

180: and (5) pressing the pot.

Detailed Description

Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the description of the embodiments below, and can be appropriately modified in design within a range satisfying the configuration of the present invention.

Fig. 1 is a schematic cross-sectional view of a first example of a decorative film structure according to an 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 10 via the adhesive layer 21.

(transparent substrate)

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

Examples of the transparent substrate 10 include an acrylic resin such as polymethyl methacrylate, a resin substrate such as polycarbonate, polyethylene terephthalate, and polystyrene, and a glass substrate. Among them, the transparent substrate 10 is preferably a glass substrate in terms of excellent transparency. The glass substrate is also excellent in weather resistance, and therefore is also suitable for use in outdoor applications and the like.

The transparent base material 10 may have transparency to such an extent that the decorative film 20 can be visually recognized from the front surface side through the transparent base material 10, and the total light transmittance is preferably 80% or more, and more preferably 90% or more. In addition, in the present specification, the total light transmittance is a value based on japanese industrial standard (Japanese Industrial Standards, JIS) K7375.

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

The radius of curvature refers to a radius of a circle that approximates the degree of curvature at a certain point of the surface of the transparent substrate 10. The radius of curvature is a value obtained by measuring the surface on the back surface side of the transparent substrate 10. The radius of curvature can be measured by non-contact using a contour shape measuring machine (contour measuring machine) and a laser. As the profile measuring instrument, for example, SV-C3100 manufactured by Sanfeng (Mitutoyo) corporation may be used.

The transparent substrate 10 is preferably a curved plate-like substrate. The area of the transparent base material 10 can be set as appropriate according to the application, and the area of the transparent base material 10 can be 300cm, for example, from the viewpoint of easy attachment of a decorative film by vacuum-pressure air forming or the like ² ～3000cm ² 。

From the viewpoint of obtaining excellent transparency, the transparent substrate 10 is preferably uniform in thickness of the transparent substrate 10. In the case where the thickness of the transparent substrate 10 is uniform, the radius of curvature of the front surface side surface of the transparent substrate 10 may be similar to the radius of curvature of the back surface side surface of the transparent substrate 10. In the present specification, if the allowable error in the thickness of the transparent base material 10 is JIS R3202, for example; 2011 "float glass and polished glass" is so called to have a uniform thickness.

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

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

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

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

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

The arithmetic surface average roughness Ra of the surface (surface on the back side) of the adhesive layer 21 side of the transparent substrate 10 is preferably 0.16 μm or less. When Ra of the back surface side of the transparent substrate 10 is 0.16 μm or less, the adhesion to the adhesive layer 21 can be improved. Therefore, when the decorative film is attached to the transparent substrate 10, the generation of an air layer (air entrapment) between the transparent substrate 10 and the adhesive layer 21 can be more effectively suppressed. When air entrapment occurs, air in the air layer expands when immersed in hot water, and the air layer tends to be easily visually recognized in hot water resistance evaluation, but by suppressing air entrapment, the occurrence of air layer can be suppressed in hot water resistance evaluation. In addition, the design of the decorative film structure as viewed from the front surface side can be improved. The Ra of the back surface side of the transparent substrate 10 is more preferably 0.12 μm or less, and still more preferably 0.06 μm or less. In the present specification, the arithmetic surface average roughness Ra and the maximum height Rz described later can be used in accordance with JIS B0601: 2001. The back surface of the transparent substrate 10 is preferably smooth, that is, has low values of Ra and Rz described later.

The maximum height Rz of the surface (surface on the back surface side) of the adhesive layer 21 side of the transparent substrate 10 is preferably 2.1 μm or less. This is because, when grooves or cracks are formed on the surface of the back surface side of the transparent base material 10, it may be difficult to attach a decorative film by vacuum-pressure forming or the like. In addition, as described above, the adhesion to the adhesive layer 21 can be improved. The Rz of the back surface side of the transparent substrate 10 is more preferably 1.6 μm or less, still more preferably 1.3 μm or less, and particularly preferably 1.0 μm or less.

(substrate film)

The base film 22 is a film that is a base material of the decorative film 20, and preferably includes a thermoplastic resin. Examples of the thermoplastic resin include polyvinyl chloride; polyolefin such as polyethylene and polypropylene; an acrylic resin; a polycarbonate resin; urethane resins, and the like.

The thermoplastic resin is preferably polyvinyl chloride. When the resin film of the present invention is attached to a substrate, the polyvinyl chloride film containing polyvinyl chloride as a main resin component has a good elongation and thus follows the surface shape of the substrate, and is not easily broken. In addition, when the laminate is integrally molded by attaching the laminate to a base material, the laminate can be molded at a relatively low temperature (about 120 ℃). The term "containing polyvinyl chloride as a main resin component" means that the content of polyvinyl chloride in the entire resin component contained in the polyvinyl chloride film is 50% by weight or more. The term "relatively low temperature" means a temperature lower than the molding temperature (more than 130 ℃) at the time of molding a resin other than polyvinyl chloride and an acrylic resin (for example, polyethylene terephthalate).

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

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

The content of the other monomer in the copolymer is usually 50% by weight or less, preferably 10% by weight or less. If the amount exceeds 50% by weight, the film may have a reduced bending resistance. Among the polyvinyl chlorides, homopolymers of vinyl chloride are preferable in terms of obtaining dimensional stability.

The polyvinyl chloride may have an average degree of polymerization of, for example, 750 to 1300. The preferred lower limit of the average polymerization degree is 800. When the average polymerization degree is in the range of 750 to 1300, the moldability at a relatively low temperature is good. In contrast, when the average polymerization degree is less than 750, the film may not be sufficiently stretched and may not follow the shape of the base material when the decorative film of the present invention and the base material are integrally laminated and molded. On the other hand, if the average polymerization degree exceeds 1300, the processability in the calender molding for obtaining a polyvinyl chloride film may be lowered, and the appearance of the film surface may be deteriorated. In addition, the shrinkage of the film after molding increases, and it may be difficult to maintain the shape. The average polymerization degree of polyvinyl chloride means an average polymerization degree measured in accordance with JIS K6721 "polyvinyl chloride test method".

The polyvinyl chloride film preferably comprises a plasticizer. The plasticizer content is preferably 7 parts by weight or more and 35 parts by weight or less with respect to 100 parts by weight of polyvinyl chloride. When the content of the plasticizer is within the above range, flexibility and formability suitable for calender forming and the like can be obtained. In addition, elongation suitable for attaching the decorative film of the present invention to a substrate and performing vacuum-pressure air forming or the like can be obtained. If the plasticizer content is less than 7 parts by weight, the polyvinyl chloride film becomes too hard, and the film 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 handleability may be lowered. The more preferable lower limit of the plasticizer content relative to 100 parts by weight of polyvinyl chloride is 15 parts by weight, and the more preferable upper limit is 30 parts by weight.

Examples of the plasticizer include phthalic acid diesters such as Bis (2-ethylhexyl) phthalate (DOP), diisononyl phthalate (Diisononyl phthalate, DINP), diisodecyl phthalate (Diisodecyl phthalate, DIDP), and di-undecyl phthalate (diundecyl phthalate, DUP); aliphatic dibasic acid diesters such as dioctyl adipate and dioctyl sebacate; triesters of phosphoric acid such as tricresyl phosphate and trioctyl phosphate; epoxy plasticizers such as epoxidized soybean oil and epoxy resin; and high molecular polyester plasticizers. Among them, phthalic diester is preferable. The DUP is preferable in terms of not being limited by various environments, less odor during film forming, less contamination of a forming machine during film forming, and the like.

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. Mu.m, it may be difficult to roll-form the sheet. Specifically, when foreign matter is mixed, or when a resin degradation product is produced during processing, the resin film may be broken or perforated during the roll forming. On the other hand, if the thickness exceeds 150 μm, heat may be insufficient or the processing speed may be lowered when heat lamination with other films or the like is performed. Further, since the thickness of the entire decorative film increases, the workability in 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. Further, the thickness is the thickness of one base film 22.

The base film 22 may be light-transmissive or light-blocking, and when the design layer is disposed on the back surface of the base film 22 as will be described later, the base film 22 is preferably transparent, and for example, the total light transmittance is preferably 70% or more, more preferably 80% or more.

When viewed from the front surface side of the decorative film molded body, the base film 22 preferably has light-shielding properties when no background is visible, and for example, the total light transmittance is preferably 3% or less, more preferably 2.8% or less.

In the case where a color is imparted to the decorative film 20 through the base film 22, the base film 22 may be a colored film including a colorant.

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

The base film 22 may be produced by roll forming. Here, the term "calender molding" refers to a method of calendering and molding a raw material resin (resin composition) by a pair of rolls.

(adhesive layer)

The adhesive layer 21 is a cured product of the adhesive composition, and is a layer for adhering the transparent substrate 10 to the substrate film 22. The adhesive layer 21 is in contact with the transparent substrate 10. The surface of the adhesive layer 21 opposite to the surface contacting the transparent substrate 10 is preferably in contact with the substrate film 22.

The adhesive composition comprises a main agent and a leveling agent. The main agent is a compound exhibiting adhesive force, and the content thereof is 80% or more with respect to the components after the solvent is removed from the adhesive composition.

The leveling agent is also called an antifoaming agent and a surface regulator, and has a surface activity effect. When the adhesive composition is applied to form an adhesive layer, the adhesive composition can be oriented on the surface of the adhesive composition coating film, and the increase in viscosity of the adhesive composition due to the volatilization of the solvent in the adhesive composition can be suppressed. In addition, by orienting the surface of the coating film of the adhesive composition, the surface tension of the adhesive composition can be reduced, the sagging or the dents caused by the low surface tension substance can be eliminated, and the surface of the adhesive layer can be inhibited from becoming uneven.

By including the leveling agent in the adhesive composition, the generation of irregularities on the surface of the adhesive layer 21 can be suppressed, and the adhesion between the adhesive layer 21 and the transparent substrate 10 and between the adhesive layer 21 and the substrate film 22 can be improved. Therefore, when the decorative film is attached from the back surface side of the transparent substrate 10, generation of wrinkles in the decorative film or generation of air entrapment between the substrate and the decorative film can be suppressed. In addition, by including the leveling agent in the adhesive composition, the irregularities are suppressed from being visually recognized between the adhesive layer 21 and the transparent substrate 10, and the aesthetic feeling when the decorative film structure is viewed from the front surface side can be improved.

The air is an air layer generated between the transparent substrate 10 and the adhesive layer 21, which is generated when the decorative film is attached to the transparent substrate 10. The air is generated by peeling off a part of the interface between the transparent substrate 10 and the adhesive layer 21 and mixing air due to insufficient adhesion of the adhesive layer 21 to the transparent substrate 10. The wrinkles are partial depressions of the adhesive surface (surface on the side facing the transparent substrate 10) of the adhesive layer 21. The local dishing of the adhesive surface is caused by the occurrence of the dishing or recess when the surface tension of the adhesive composition applied to the surface of the coating film of the adherend is insufficiently reduced.

As described later, when attaching the decorative film from the back surface side of the transparent base material 10 having the curved surface portion protruding toward the front surface side, in vacuum-pressure forming or the like, the softened decorative film 20 is first brought into contact with the protruding portion on the back surface side of the transparent base material 10, and then attached from the protruding portion toward the center of the transparent base material along the surface on the back surface side of the transparent base material 10. The curved surface portion of the transparent substrate is in contact with the substrate film and the adhesive layer in a stretched state, and when the decorative film structure is cooled, the adhesive force between the transparent substrate and the adhesive layer may be reduced due to the stress of the substrate film, and a part of the adhesive layer may be peeled off (air may be taken in). Therefore, it is preferable to provide an adhesive layer having high adhesion.

Examples of the leveling agent include acrylic polymer-based, silicone-based, and vinyl polymer-based leveling agents. In view of reducing the surface tension while maintaining the adhesion, a leveling agent of a vinyl polymer type is preferable. From the viewpoint of high effect of reducing the surface tension, leveling agents of acrylic polymer type, silicone type, vinyl polymer type may be used. Examples of the vinyl polymer leveling agent include "dap (Dapor) SN-530" manufactured by San Nopco, inc. Of the sannopraceae, and examples of the acrylic polymer leveling agent include "dap (Dapor) SN-348" manufactured by San Nopco, inc. Of the sannopraceae, dapor "Dapor) SN-354", and examples of the silicone leveling agent include "dap (Dapor) SN-359" manufactured by San Nopco, inc.

The content of the leveling agent is preferably 0.03 to 0.6 parts by weight based on 100 parts by weight of the main agent. By setting the content of the leveling agent to the above range, the adhesion between the transparent substrate 10 and the adhesive layer 21 can be further improved, and therefore, generation of wrinkles and air entrapment can be effectively suppressed. In addition, the decrease in hot water resistance due to air entrainment can also be suppressed.

If the content of the leveling agent exceeds 0.6 parts by weight, there is a possibility that the adhesion may be lowered and the hot water resistance may be lowered. The content of the leveling agent is more preferably 0.05 to 0.30 parts by weight.

Examples of the adhesive composition include adhesive compositions of polyester type, acrylic type, rubber type, silicone type, and the like. Among them, the adhesive composition preferably contains a polyester compound as a main agent in terms of excellent adhesion at high temperature and heat resistance. By using a polyester adhesive containing a polyester compound as a main agent, a sufficient adhesive force can be easily obtained even when a decorative film is attached from the back side of a substrate having a large curvature. The adhesive composition may further comprise an organic solvent.

The polyester compound is preferably a copolyester. The copolyester is more preferably a saturated copolyester. Examples of the polyester-based adhesive containing the saturated copolyester include "BX-10 ss" manufactured by Toyo corporation, BYron (registered trademark).

The adhesive composition is preferably a hot melt adhesive. The adhesive is more preferably a polyester-based hot melt adhesive. The adhesive layer using the hot-melt adhesive may be one that exhibits adhesive force at the molding temperature (for example, 110 to 140 ℃) of the decorative film 20.

The adhesive composition preferably further comprises a hardener. The curing agent is preferably an isocyanate curing agent. The isocyanate-based curing agent preferably contains Xylylene Diisocyanate (XDI) such as m-xylylene diisocyanate; hydrogenated xylylene diisocyanate (H6 XDI) such as 1, 4-bis (isocyanatomethyl) cyclohexane; isophorone diisocyanate (isophorone diisocyanate, IPDI); hexamethylene diisocyanate (hexamethylene diisocyanate, HDI); pentamethylene diisocyanate (pentamethylene diisocyanate, PDI) such as 1, 5-pentamethylene diisocyanate, and the like. Among them, an isocyanate-based hardener containing 1, 5-pentamethylene diisocyanate is more preferable. Specific examples of the isocyanate-based curing agent containing 1, 5-pentamethylene diisocyanate include "Starobio (registered trademark) D-370N" manufactured by Sanchi chemical Co., ltd.

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

When the adhesive composition contains a polyester compound as a main agent, the adhesive composition preferably further contains an isocyanate-based hardener, and the NCO index represented by the following formula (1) is 0.4 to 1.6. By setting the NCO index to 0.4 to 1.6, even if air is interposed, the adhesive layer 21 is hard, and therefore 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 ℃ for 1 hour, the generation of an air layer between the transparent substrate and the adhesive layer can be suppressed. The NCO index is more preferably 0.7 to 1.3.

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

The adhesive layer 21 is preferably transparent. The total light transmittance of the adhesive layer 21 is preferably 70% or more, 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 substrate 10 may not be obtained. The thickness is more preferably 35 μm or more and 50 μm or less.

The method for forming the adhesive layer 21 is not particularly limited, and a conventionally known method such as a method of applying an adhesive composition to a separator by a bar coater or the like and drying the same can be used. Then, a decorative film can be produced by bonding a surface opposite to the separator to the base film 22. The separator protects the adhesive layer 21, and is removed when the decorative film is attached to the transparent substrate 10, and the exposed adhesive layer 21 is attached in contact with the back surface of the transparent substrate 10.

The decorative film 20 may further have a design layer 23 on the back surface side of the base film 22. Fig. 5 is a schematic cross-sectional view of a second example of the decorative film structure of 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 this order from the transparent base material 10 side.

(design layer)

The design layer 23 is a layer for imparting a design such as color or pattern to the decorative film, and is obtained by printing with ink or the like, for example. The ink may contain a coloring material, a binder resin, a solvent, etc., and examples of the coloring material include pigments, dyes, inorganic fillers such as titanium oxide, etc. As the binder resin, vinyl acetate, acrylic resin, and the like are exemplified. 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, flexography, screen printing, etc. may be used, and gravure printing is preferable from the viewpoint of good printability to a resin film such as a vinyl chloride resin film.

In the second example, for example, a decorative film can be produced by printing the design layer 23 on one of the surfaces of the base film 22 and bonding one of the surfaces of the base film 22 to the surface of the adhesive layer formed on the separator opposite to the separator. By disposing the base material film 22 between the design layer 23 and the adhesive layer 21, bleeding of ink of the design layer 23 due to components contained in the adhesive layer 21 can be suppressed.

In the second example, the third example, and the fourth example, in which the design layer is disposed on the back surface of the base film 22, the base film 22 is preferably transparent, and for example, the total light transmittance is preferably 70% or more, and more preferably 80% or more, so that the design layer 23 can be seen from the front surface side of the decorative film structure.

The decorative film 20 may further have a resin film 24 on the back surface side of the base film 22. Fig. 6 is a schematic cross-sectional view of a decorative film structure of a third example. Fig. 6 illustrates a case where the decorative film 20 includes an adhesive layer 21, a base film 22, a design layer 23, and a resin film 24 in this order from the transparent base 10 side. 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 this order from the transparent base 10 side.

(resin film)

The resin film 24 is a layer for improving the design of the decorative film, and preferably includes a thermoplastic resin. Examples of the thermoplastic resin include polyvinyl chloride; polyolefin such as polyethylene and polypropylene; acrylic resins, polycarbonate resins, urethane resins, and the like.

The resin film 24 preferably has the same moldability as the base film 22. In the case where 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 in the base film 22 can be used in terms of the average polymerization degree of polyvinyl chloride, the kind or content of plasticizer.

The resin film 24 may be a single-layer film as shown in fig. 6, or a multilayer film in which a first resin film 24a and a second resin film 24b are laminated as shown in fig. 7, which will be described later. In this specification, the first resin film 24a and the second resin film 24b are simply referred to as the resin film 24 without distinction. The resin film 24 is preferably a colored film from the viewpoint of improving the design of the decorative film.

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

The resin film 24 may be light-transmissive or light-blocking. In the case where the resin film 24 is a multilayer film, the resin film disposed on the front surface side may be light-transmissive. In addition, when a back surface coating layer described later is disposed on the back surface side of the resin film 24, the resin film 24 may be light-transmissive. In the case where the resin film 24 is disposed on the back-most surface of the decorative film, the resin film 24 may be light-shielding.

The decorative film 20 may also have a back coating 25 on the back side of the substrate film 22. Fig. 7 is a schematic cross-sectional view of a fourth example of the decorative film structure of the embodiment. Fig. 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 surface coating layer 25 in this order from the transparent base material 10 side.

(Back coating)

The back surface coating layer 25 is a layer for improving weather resistance and scratch resistance of the decorative film 20. The back coating layer 25 is preferably disposed on the back surface of the decorative film 20.

Examples of the material of the back surface coating layer 25 include coating agents containing urethane resins, acrylic resins, polyester resins, and the like. As the urethane-based coating agent, Q-563 manufactured by Sanchi chemical Co., ltd.

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

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

The total light transmittance of at least one layer located on the back surface 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 of the design layer 23, the resin film 24, and the back surface coating layer 25 is more preferably 3% or less.

(decorative film)

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

(method for Forming decorative film)

As a method of attaching the decorative film to the transparent substrate, for example, a method of attaching the decorative film to the transparent substrate by heating is cited. Examples thereof include in-mold molding such as thermoforming, vacuum forming, pressure forming, and vacuum-pressure forming.

Among them, vacuum molding, pressure molding, vacuum-pressure molding (vacuum-pressure molding, etc.) are preferable in terms of easy attachment to a substrate of a complicated three-dimensional shape. Further, for a substrate which is easily broken such as glass, vacuum molding, pressure molding, and vacuum-pressure molding without using a jig are preferable. The vacuum forming is a forming method in which a forming chamber of a forming machine in which a base material and a decorative film are disposed is set to be vacuum, and the decorative film is attached to the base material, and the pressure forming is a forming method in which the forming chamber is pressurized with compressed air to attach the decorative film to the base material. The vacuum-pressure molding is a molding method in which the inside of the molding chamber is evacuated and then pressurized under vacuum conditions to adhere the decorative film to the substrate.

The attaching method by vacuum-pressure forming will be described below with reference to the drawings. Fig. 8 to 11 are first to fourth diagrams for explaining a decoration process of vacuum-pressure forming. As the vacuum-pressure forming apparatus, a three-dimensional surface finishing (Three dimension Overlay Method, TOM) forming machine (NGF-0406-T manufactured by Bruce 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 a molding chamber in an atmospheric pressure state. The vacuum-pressure forming apparatus 100 includes forming chambers (an upper forming chamber 110 and a lower forming chamber 120) up and down. The transparent substrate 10 is set in the work 130 in the lower molding chamber 120, and the decorative film 20 laminated on the transparent substrate 10 is set on the upper surface of the lower molding chamber 120. The transparent base material 10 is disposed so that the back surface side (the surface opposite to the protruding surface) faces the decorative film 20. Then, the upper and lower molding chambers are each hermetically sealed by the driving device 140, and vacuum is applied from the vacuum tank 150 to the upper and lower molding chambers via the pipe 160, respectively, to thereby set the upper and lower molding chambers to a vacuum state (extremely low pressure state).

When the transparent substrate 10 is provided on the stage 130, the transparent substrate 10 is disposed obliquely, and thus air is easily discharged at the time of adhesion, and the adhesion between the adhesive layer and the transparent substrate can be improved.

Then, as shown in fig. 9, the infrared heater 170 is turned on and the decorative film 20 is heated while maintaining the vacuum state. Thereby, the decorative film 20 is softened and can be attached along the surface shape of the transparent substrate 10. The heating temperature is a forming temperature of the decorative film 20. The molding temperature is, for example, 110℃to 140 ℃. In particular, in the case where the substrate is glass, the heating temperature is preferably 120℃to 130 ℃.

Next, as shown in fig. 10, the table 130 in the lower molding chamber 120 is lifted by the driving device 140, and the transparent substrate 10 is brought into contact with the softened decorative film 20. Then, as shown in fig. 11, the vacuum on the upper molding chamber 110 side is opened to be in an atmospheric pressure state (the inside of the lower molding chamber 120 is in a vacuum state), and compressed air is fed from the air tank 180 into the upper molding chamber 110, whereby the decorative film 20 is pressed against the transparent base material 10 and laminated along the shape thereof. Thus, the decorative film 20 is laminated on the back surface of the transparent base material 10.

Then, the inside of the upper molding chamber 110 and the inside of the lower molding chamber 120 are returned to the atmospheric pressure state, respectively, and the upper molding chamber 110 is raised to take out the transparent substrate 10 to which the decorative film 20 is attached. The excess decorative film 20 is cut to obtain a decorative film molded body. Fig. 12 is a schematic cross-sectional view of the decorative film structure after vacuum-pressure forming. As shown in fig. 12, the side surface may be covered with a decorative film 20 in addition to the back surface of the transparent base material 10.

Examples (example)

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

Example 1

A decorative film laminate in which a transparent substrate, an adhesive layer, a substrate film, a design layer, a first resin film, a second resin film, and a back surface coating layer were laminated in this order was produced by the method described below.

Transparent substrate >, a transparent substrate

As the transparent substrate, a transparent substrate (glass substrate) made of glass having a thickness of 5mm and protruding toward the front surface side and having a different radius of curvature was prepared. The thickness of each glass substrate was uniform, and the total light transmittance was 92%. The radius of curvature of the glass substrate was measured by the following method, and the results are shown in table 1.

(measurement apparatus)

Measurement device: surface roughness-profile shape determinator: SV-C3100 manufactured by Sanfeng (Mitutoyo) Co., ltd

Stylus (stylus): stylus SPH-71

(measurement conditions)

Speed of: 0.5mm/sec

Distance of movement: 100mm of

The sampling method comprises the following steps: line segment spacing (0.005 mm)

(calculation method)

Analysis software: "Fomtracesak" manufactured by Mitutoyo corporation "

The average value at the time of 3 measurements was obtained by using a manual 3-point method using software for the curve portion determined by the software to have the largest radius of curvature.

The arithmetic surface average roughness of the back surface side surface of the glass substrate was determined by the method according to JIS B0601:2001, and the results are shown in table 1 below.

(measurement conditions)

Curve: r is R

And (3) a filter: gauss (GAUSS)

Cut-off value λc:0.8mm

Cut-off value λs:2.5 μm

Number of intervals: 15mm of

Running up: has a sequence of

Measuring speed: 0.5 mm/s

< production of film laminate >

A vinyl chloride resin composition was prepared by adding 25 parts by weight of di-undecyl phthalate (DUP) as a plasticizer to 100 parts by weight of polyvinyl chloride having an average polymerization degree of 800. The obtained vinyl chloride resin composition was melt kneaded by a Banbury mixer, and then a base film having a thickness of 90 μm was produced by roll forming. The total light transmittance of the base film was 83.1%.

Pigments were added to the vinyl chloride resin composition to prepare a first resin film and a second resin film having different colors and a thickness of 90 μm.

A design layer having a thickness of 2 μm was printed on one side of the substrate film using an ink and by gravure printing. 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.

A coating agent obtained by adding titanium oxide as a colorant to a urethane-based coating agent (Q-563 manufactured by mitsunobu chemical company, inc.) was applied to the surface of the second resin film opposite to the surface in contact with the first resin film, and a back coating layer having a thickness of 3 μm was laminated, to thereby produce a laminate in which a base film, a design layer, the first resin film, the second resin film, and the back coating layer were laminated.

< preparation of adhesive layer >

Polyester adhesive compositions were prepared by adding a polyester adhesive, an isocyanate curing agent and a leveling agent according to the formulations shown in table 1, using the following materials. The obtained polyester-based adhesive composition was applied to a separator to prepare an adhesive layer having a dry thickness of 40. Mu.m. The content of the isocyanate-based hardener and the content of the leveling agent in table 1 are the contents per 100 parts by weight of the main agent (polyester-based compound). The adhesive layer has a total light transmittance of 80% or more.

(Material)

Polyester adhesive: "Baren (Byron) BX-10ss" (solid content: 30%, hydroxyl value: 8 mgKOH/g) manufactured by Toyo spinning Co., ltd

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

Isocyanate-based hardener: "Star ratio of O (STABiO) D-370N" (solid content: 100%, NCO%: 25%)

Leveling agent: "daper" SN-530 "manufactured by Sannopco, inc"

< preparation of decorative film >)

The surface of the adhesive layer opposite to the separator and the surface of the base film of the film laminate opposite to the design layer are bonded to each other, and a decorative film is produced.

Structure of decorative film

The decorative film structure of example 1, in which the decorative film was attached to the back surface of the transparent substrate, was produced by disposing the adhesive layer of the decorative film from which the separator was peeled so as to face the back surface of the transparent substrate, and performing vacuum-pressure molding at a molding temperature of 125 ℃. Vacuum-pressure forming was performed using a TOM forming machine (NGF-0406-T) manufactured by Broth vacuum Co., ltd.

Example 2 and example 3

The decorative film structures of example 2 and example 3 were produced in the same manner as in example 1, except that the glass substrate of example 1 was used and the structure of the adhesive layer was changed as shown in table 1.

(examples 4 to 6, comparative examples 1 to 3)

Decorative film structures of examples 4 to 6 and comparative examples 1 to 3 were produced in the same manner as in example 1 except that the glass substrates shown in table 1 were used and the structures of the adhesive layers were changed as shown in table 1.

< evaluation test >)

The following evaluation was performed on the decorative film structures of examples and comparative examples, and the results are shown in table 1.

(generation of wrinkles)

The decorative film structure was visually observed from the front surface side while being left in a room (under a normal fluorescent lamp), and evaluated according to the following evaluation criteria. The wrinkles are wrinkles generated on the surface of the adhesive layer due to the depressions of the adhesive layer.

And (2) the following steps: no wrinkles were visible.

X: wrinkles are visible under visual inspection.

(air-clips in)

The decorative film structure was visually observed from the front surface side in a state where the decorative film structure was left in a room where a normal fluorescent lamp was lighted (hereinafter, under a fluorescent lamp), and in a state where the decorative film structure was left in a room (under a normal fluorescent lamp) and further irradiated with light by a light emitting diode (light emitting diode, LED) lamp (hereinafter, LED light irradiation), and evaluated according to the following evaluation criteria. The air layer in the evaluation of air entrapment and the following evaluation of hot water resistance means air entrapment generated between the transparent substrate and the adhesive layer. By locally irradiating the decorative film structure with light using the LED lamp, a finer air layer can be detected. For example, 0.02mm ² The above air layer reflects the LED light and appears to emit light.

And (3) the following materials: the air layer was not visually recognized under the fluorescent lamp and the LED light irradiation.

And (2) the following steps: the air layer was not visually recognized under the fluorescent lamp, but was visually recognized when the LED light was irradiated.

X: the air layer is visually recognized under the fluorescent lamp.

(hot water resistant)

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

X: the air layer is visually recognized under the fluorescent lamp.

Examples 1 to 6 in which the radius of curvature of the transparent substrate was 20mm or more and 100mm or less and the adhesive layer contained a leveling agent, each suppressed the generation of wrinkles and air entrapment. From a comparison of example 5 and example 6, it was confirmed that the smoother the surface of the transparent substrate on the side facing the adhesive layer (the lower Ra and Rz), the more the generation of air entrapment was suppressed. Since the adhesive surface of the adhesive layer is smoothed by containing the leveling agent, the occurrence of air entrapment can be suppressed particularly by attaching the adhesive layer having a smooth adhesive surface to a transparent substrate having a smooth surface. Since air entrapment is suppressed and no minute air (air layer) is present, hot water resistance can be improved.

Comparative examples 1 and 2, in which no leveling agent was added to the adhesive layer, had wrinkles and air entrapment. In comparative example 3, in which the radius of curvature of the transparent substrate was large, wrinkles were generated without adding the leveling agent.

Claims

1. A decorative film structure comprises a transparent base material and a decorative film attached to the back surface of the transparent base material,

the transparent base material has a curved surface portion protruding toward the front surface side and having a radius of curvature of 20mm or more and 100mm or less,

the decorative film comprises a substrate film and an adhesive layer, is attached to the transparent substrate 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 an arithmetic surface average roughness Ra of the adhesive layer-side surface of the transparent base material is 0.16 μm or less.

3. The decorative film structure according to claim 1, wherein the adhesive composition comprises a polyester-based compound as the main agent.

4. The decorative film structure according to claim 3, wherein the adhesive composition further comprises an isocyanate-based hardener,

An 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 isocyanate component contained in isocyanate-based hardener/the number of moles of OH groups derived from polyester contained in polyester-based compound (1).

5. The decorative film structure according to claim 1, wherein the leveling agent is contained in an amount of 0.03 to 0.6 parts by weight based on 100 parts by weight of the main agent.

6. The decorative film structure of claim 1, wherein the transparent substrate is a glass substrate.

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 this order from the transparent base 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 this order from the transparent base 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 surface coating layer in this order from the transparent base side.

10. The decorative film structure according to any one of claims 7 to 9, wherein at least one layer located on the back side of the base film has a total light transmittance of 3% or less.