JP6187632B2 - Adhesive film for vehicle stickers - Google Patents

Description

  The present invention relates to an adhesive film for a vehicle sticker used for advertisement in a vehicle such as a railway vehicle.

  2. Description of the Related Art Conventionally, vehicle stickers used for in-vehicle advertisements such as railway vehicles have been required to have high light shielding properties because the appearance of printing may deteriorate if the light shielding properties of the base material are poor. In particular, when sticking to a vehicle window, both sides of the sticker are visually recognized, and therefore, there is a problem that when the light passes through the base material, the printing on the opposite side can be seen through, and thus high light shielding is required.

  As a sticker with high concealability and high light-shielding property, by adding a fine powder such as an inorganic substance to a plastic film and stretching it, a number of fine pores are formed inside to improve whiteness and light-shielding property. Stickers using foamed substrates are widely used in general. However, the sticker using the stretched foam base material has a poor removability because the base material is easily broken between the layers at the time of peeling. In addition, depending on the type of adherend to be attached, there is a problem in combustion resistance, and combustion may occur in a railway vehicle material combustion test.

  For such a problem, a printing base material in which two base base materials are laminated via a concealing layer was used as an adhesive film for a sticker having high concealing property and light shielding property and improved removability. An adhesive film is disclosed (see Patent Document 1). The pressure-sensitive adhesive film achieves excellent concealing properties, light shielding properties, and excellent removability by using a printing substrate having the above-described configuration and having certain characteristics. However, in recent years, there has been an increasing demand for safety in vehicles, and in addition to the above characteristics, it is desirable to achieve flame resistance under severe combustion test conditions in adhesive films used for vehicle stickers. Yes.

  In order to solve the above problems, Patent Documents 2 to 5 disclose a method of laminating an overlaminate layer subjected to a flame retardant treatment on the surface. However, such special overlaminate layers often have low transparency (visible light transmittance), which impairs the design of the sticker design printing layer and cannot avoid significant cost increases.

JP 2005-068214 A JP 2002-356073 A JP 2003-033976 A JP 2003-048270 A JP 2003-048378 A

  The problem to be solved by the present invention is to provide a pressure-sensitive adhesive film for a vehicle sticker that has high concealment and light shielding properties, is less likely to cause substrate destruction at the time of peeling, and has excellent flame resistance under flame contact. It is to be realized at low cost.

  In the present invention, it is a concealable base material having a concealing layer on at least one surface of a white resin film layer, and the white resin film layer has a titanium dioxide content of 5 to 30% by mass and a thickness of 25 to 100 μm. By using a stretched film, it is possible to realize excellent combustion resistance as well as high concealing properties, light shielding properties, and good removability.

  Since the adhesive film for vehicle stickers of the present invention has high concealment and light shielding properties, and whiteness, the appearance of the printed surface is good when advertisement printing such as coloring or design is provided to form a vehicle sticker. In addition, when the both sides are visually recognized, the coloring of the viewing surface, the design, and the like can be suitably visually confirmed. Further, since the sticker is hardly broken when the vehicle sticker is replaced, the replacement operation can be performed satisfactorily. In addition, since it is difficult to burn even under flame contact, it is difficult to burn even when it comes into contact with a fire type such as a lighter or cigarette, and safety is high.

  In addition, when realizing flame retardancy, it is not necessary to form a special flame retardant treatment layer on the surface, and it is possible to use a general material on the surface as an overlaminate layer, so the design of the sticker is impaired. There is no. Moreover, since a general material can be used, raw material procurement is easy and the cost is low. Moreover, since it is not flame retardant, it can be incinerated after using the sticker (sticker peeling). Since no polyvinyl chloride resin-based material is used, the halogen element content is considered to be low. Therefore, the possibility of generating harmful gases during incineration is low, so it is considered that there is little impact on the environment and human health.

It is a schematic diagram of a railway vehicle combustion test apparatus.

The adhesive film for a vehicle sticker of the present invention is an adhesive film used for a vehicle sticker attached in a vehicle, and has a concealable base material having at least a white resin film layer and a concealing layer, and an adhesive layer. The white resin film layer is an adhesive film made of an unstretched resin film having a titanium dioxide content of 5 to 30% by mass and a thickness of 25 to 100 μm, and is nonflammable in the following combustion test. The nonflammability standards are as shown in the table below.
<Combustion test>
A B5-size test material (182mm x 257mm) with an adhesive film affixed to a melamine resin decorative board is held at an angle of 45 ° so that the adhesive film surface is on the flame contact side, and the center of the bottom of the fuel container is the test material Put it on a base made of a material with low thermal conductivity such as cork so that it is 25.4 mm (1 inch) vertically below the center of the bottom surface, put 0.5 cc of pure ethyl alcohol and ignite, and the fuel will burn out Leave until.

[White resin film layer]
A white unstretched resin film that has not been stretched is used for the white resin film layer used in the present invention. In the present invention, the white color ensures high concealment, and the use of an unstretched film makes it difficult for shrinkage to occur when the resin softens during flame contact, resulting in large pores (diameter 5 mm or more). Hard to occur. When a large hole occurs in the sticker during flame contact, combustion proceeds rapidly from the periphery of the hole, but the unstretched film used in the present invention is less likely to cause such combustion and thus has excellent combustion resistance. it can.

Examples of the resin that forms the unstretched resin film include polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polymethyl methacrylate, 66 nylon, 6 nylon, polyimide, polystyrene, ABS resin, and AS resin. Among them, since a whitened non-stretched resin film can be easily obtained at low cost, a white resin film containing at least one of polyethylene, polypropylene, or polybutylene terephthalate as a main resin component can be preferably used. A white resin film having a main resin component can be particularly preferably used because of its high versatility. In addition, those that do not contain vinyl chloride as a resin component can suppress the generation of harmful gases (HCl, Cl ₂ ) and harmful substances (dioxins, etc.) from the standpoint of environmental pollution measures (during disposal, etc.) and flame contact Therefore, it can be used preferably with little influence on the human body. Further, these non-stretched resin films are preferably those which are not subjected to foaming treatment because they are less likely to cause substrate destruction during peeling.

  Among them, an unstretched resin film made of polyethylene, polypropylene, or polybutylene terephthalate as a resin component, particularly a non-stretched polypropylene film has a good flexibility even if it contains a small amount of a white colorant in a thin thickness. Therefore, it is possible to realize a vehicle sticker that can be suitably used as a sticker and hardly causes interlayer cracks at the time of peeling.

  An unstretched resin film whitened with titanium dioxide is used for the white resin film layer. Content of the titanium dioxide in a white resin film layer is 5-30 mass%, Preferably it is 7-25 mass%, More preferably, it is 10-20 mass%. By setting it as the said content, high concealment property and low transparency can be implement | achieved with the concealment ink layer to laminate | stack, and the softness | flexibility of a film is not impaired. Moreover, since a large heat capacity can be secured, combustion resistance can be suitably realized.

  The thickness of the white resin film layer is 25 to 100 μm, preferably 50 to 100 μm, more preferably 80 to 100 μm. By setting the thickness, an appropriate strength and rigidity required at the time of sticker processing or at the time of sticking work or peeling work when used as a sticker can be obtained, and a necessary light shielding property can be ensured.

  The white resin film layer preferably has a total light transmittance (τt) of 20% or less, more preferably 15% or less, and particularly preferably 10% or less according to the measurement method defined in JIS K 7361-1. . Furthermore, a particularly high light-shielding property can be realized by providing a concealing layer.

  In the white resin film layer, the whiteness of the surface layer is preferably 75% or more, and particularly preferably 80% or more. By setting it as the said whiteness, the visibility of the printing surface of the vehicle sticker obtained can be improved suitably.

[Hidden layer]
As the concealing layer used in the present invention, a colored ink layer or a metal thin film layer can be used. The colored ink layer is not particularly limited as long as it can impart light-shielding properties, but it is preferable to use a colored ink layer composed of black or dark ink as a concealing layer because light-shielding properties are easily imparted. Specifically, for example, black ink containing carbon black as a colorant can be preferably used. In addition, titanium dioxide and various inorganic and organic pigments can be used for adjusting the color tone. Further, as the binder resin of the ink used for the concealing layer, a urethane resin system is preferable, and it has an appropriate flexibility and adhesion to the substrate. Moreover, when winding up in roll shape after printing a concealment layer, in order to prevent a surface decorative layer and blocking, it does not interfere at all even if it adds antiblocking agents, such as a silica. The ink used for the concealing layer is appropriately selected depending on the printing method, but if an example is given, when a gravure printing method is selected, a polyurethane resin system is suitable, and as a polyurethane resin ink, For example, “Hilamic” which is a gravure ink manufactured by Dainichi Seika Kogyo Co., Ltd., “Univia NT” manufactured by DIC Graphics Co., Ltd. and the like can be mentioned.

  The total light transmittance of the concealing layer is preferably less than 5%, more preferably less than 1%. When black ink is used as the masking layer, the total light transmittance can be suitably reduced by appropriately adjusting the content percentage of carbon black in the ink in the range of 0.1% to 10%.

  The thickness of the concealing ink layer varies depending on the pigment concentration of the ink used, but is 1 to 10 μm, preferably 2 to 8 μm, more preferably 4 to 6 μm. By setting the thickness of the ink layer to 1 μm or more, it is easy to ensure light shielding properties, and by setting the thickness to 10 μm or less, it is easy to obtain suitable application workability without damaging the flexibility of the film.

  Moreover, as a metal thin film layer used as a concealing layer, a metal vapor deposition layer formed by metal vapor deposition or sputtering, a metal foil layer made of a thin metal foil, or the like can be used. The metal used for the metal thin film layer is not particularly limited as long as the necessary light shielding properties are obtained, but aluminum, chromium, gold, silver, copper, nickel, stainless steel, etc. can be used, especially Aluminum is more preferable in terms of weight and economy. Examples of the metal foil include “Super Foil” 6 to 15 μ made by Toyo Aluminum Co., Ltd.

[Concealment substrate]
The concealable substrate used in the present invention is a substrate having at least the white resin film layer and the concealing layer. The lamination of the white resin film layer and the hiding layer may be appropriately adjusted according to the material used and the hiding layer to be provided. For example, when providing the white resin film layer with a concealing layer made of a colored ink layer directly, it can be provided by printing colored ink on one or both sides of the white resin film layer by an offset printing method or a gravure printing method. Moreover, when laminating a concealing layer made of colored ink on the white resin film layer, surface treatment such as corona discharge treatment, plasma discharge treatment, ultraviolet ray or electron beam irradiation is applied to the surface of the white resin film layer as necessary. You may go.

  Moreover, when providing the concealing layer which consists of a metal thin film layer directly in a white resin film layer, you may adhere | attach a metal vapor deposition layer on one surface or both surfaces of a white resin film layer by vapor deposition or sputtering. Alternatively, a metal foil may be used, and the metal foil may be bonded to the white resin film layer by a dry lamination method or a hot melt method using an adhesive.

  Moreover, when laminating a concealing layer on a white resin film layer, a commercially available resin film provided with a concealing layer may be laminated with the white resin film layer to form a concealing substrate. For example, a commercially available film with a deposited film having a thickness of 20 to 80 nm (200 to 800 mm), for example, an aluminum deposited film such as Metaline (ML) film CP grade “CPWA-25” manufactured by Mitsui Chemicals, Inc. It is good also as a concealment base material by pasting a non-stretched film with the said white resin film by the dry lamination method or the heat seal method.

  When a commercially available resin film provided with a concealing layer is laminated with a white resin film layer, it is preferable to use a resin film having the same composition as the white resin film layer to be bonded from the viewpoint of preventing curling of the laminate film. .

  The structure of the concealable substrate is a decoration in which at least one surface is a white resin film layer, particularly when one surface is a white resin film layer and the other surface is a concealing layer as a sticker. It is preferable because the layer is easy to provide and the visibility of the decorative layer is improved. In addition, a configuration having two or more white resin film layers is preferable because high concealability is easily obtained.

  Examples of preferable configuration of the concealing substrate include, for example, (1) a configuration having a concealing layer on one side of the white resin film layer, (2) a configuration having concealing layers on both sides of the white resin film layer, and (3) a white resin. A structure having a concealing layer on one side of the film layer, and further having a white resin film layer on the concealing layer, (4) a base material having a concealing layer on one side of the white resin film layer, The other white resin film layer is laminated so that the other white resin film layers are laminated, and (5) the white resin film layers or the white resin film layers are laminated to each other on the one side of the white resin film layer. Examples of such a configuration are as follows. Among these, (1) the configuration having the concealing layer on one side of the white resin film layer is preferable because the configuration is simple, and (4) one of the substrates having the concealing layer on one side of the white resin film layer is concealed. A structure in which the layer and the other white resin film layer are laminated together is preferable because particularly excellent light shielding properties can be easily realized. In these concealing substrates, the configuration having the concealing layer on one or both sides of the white resin film layer may be directly laminated as described above or the resin film having the concealing layer may be laminated on the white resin film layer. Although it is good, it is preferable to use a layer in which a concealing layer is directly laminated on the surface of the white resin film layer by applying colored ink, metal deposition, or attaching a metal foil with an adhesive.

  The concealable substrate used in the present invention preferably has a total light transmittance (τt) specified in JIS K 7361-1 of 5% or less, more preferably 3% or less, and more preferably 1%. The following is particularly preferable. By setting it as the said light transmittance, also when a vehicle sticker is used with the form visually recognized from both surfaces, the visibility of a printing surface can be improved.

  The thickness of the concealable base material is 25 to 250 μm, preferably 70 to 220 μm, more preferably 100 to 170 μm. With this thickness, when processing into sticker processed products, when using processed stickers, appropriate base material strength and rigidity (waist) can be secured, making processing easy, and workability for pasting and use during use. The subsequent peeling operation can be performed efficiently. In addition, necessary and sufficient light shielding properties can be ensured.

[Adhesive layer]
The pressure-sensitive adhesive layer used in the present invention is not particularly limited, but acrylic acid is suitable because it is easy to obtain weather resistance, adhesive strength, re-peelability after use, combustion resistance, etc. suitable for vehicle sticker applications. A pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive composition mainly composed of a copolymer of (meth) acrylic acid ester monomers such as esters and methacrylic acid esters is preferred.

  As the acrylic pressure-sensitive adhesive composition, (a) a (meth) acrylic acid alkyl ester monomer having an alkyl group having 1 to 14 carbon atoms (adhesive monomer (a homopolymer having a low Tg)), (b ) A polar group-containing vinyl monomer (cohesive monomer), (c) Acrylic copolymer containing a vinyl monomer having a functional group that reacts with a crosslinking agent as an essential component, and a crosslinking agent added to the adhesive main component Is preferred. The acrylic copolymer as described above is suitable for removability.

  As the adhesive monomer (a), a (meth) acrylic acid ester having an alkyl group having 1 to 14 carbon atoms such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isooctyl (meth) acrylate, 2-ethylhexyl ( Examples include meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, and dodecyl (meth) acrylate. It is preferable to use at least one monomer selected from these in an amount of 50% by mass or more based on the total amount of monomers.

  Examples of the polar group-containing vinyl monomer (b) include a carboxyl group-containing vinyl monomer and a nitrogen-containing vinyl monomer. Examples of the carboxyl group-containing vinyl monomer include α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid. Examples of the nitrogen-containing vinyl monomer include N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, N, N-dimethylacrylamide, dimethylaminoacrylate and the like. Other cohesive vinyl monomers include maleic anhydride, acrylonitrile, and the like.

In the vinyl monomer (c) having a functional group that reacts with the crosslinking agent, examples of the functional group that reacts with the crosslinking agent include a hydroxyl group, an amino group, and a glycidyl group.
Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl acrylate, 2-hydroxypropyl (meth) acrylate, and the like. Examples of amino group-containing monomers include acrylamide and N-methylolacrylamide. Furthermore, examples of the glycidyl group-containing monomer include glycidyl methacrylate. A particularly suitable monomer is 2-hydroxyethyl (meth) acrylate.
As other monomers, monomers having a high Tg homopolymer can be used as necessary. Examples of such monomers include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, styrene, vinyl acetate and the like.

  When the acrylic copolymer is 100 parts by mass, the amount of the (meth) acrylic acid alkyl ester monomer (a) having an alkyl group having 1 to 14 carbon atoms is 50 parts by mass or more, and the polar group-containing vinyl monomer (b) The blending amount of the vinyl monomer (c) having a functional group that reacts with the crosslinking agent is 0.01 to 5 parts by mass. When the amount of the (meth) acrylic acid alkyl ester (a) having 1 to 14 carbon atoms is 50 parts by mass or more, it is easy to obtain suitable initial adhesiveness, and the amount of the highly polar vinyl monomer (b) is set to 0.00. By setting it to 1 part by mass or more, a cohesive force can be easily obtained, and adhesive residue is hardly generated when the adhesive film is peeled off from the adherend. Moreover, it becomes easy to acquire favorable low-temperature adhesiveness by the compounding quantity of a highly polar vinyl monomer (b) being 5 mass parts or less. In addition, by setting the blending amount of the vinyl monomer (c) having a functional group that reacts with the crosslinking agent to 0.01 parts by mass or more, crosslinking reactivity is likely to be suitable, and the acrylic copolymer can be sufficiently crosslinked, By making 5 mass parts below, the pot life of the pressure-sensitive adhesive solution is particularly suitable, and the handleability of the pressure-sensitive adhesive solution is improved.

  It is preferable to appropriately set the amount of the monomer so that the glass transition temperature of the pressure-sensitive adhesive main agent produced by copolymerizing the monomer is -70 ° C to -20 ° C. Various known methods can be used as a method for producing the pressure-sensitive adhesive main agent, and for example, it can be produced by radical polymerization of a monomer in an organic solvent. Examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, and ketones such as methyl ethyl ketone and cyclohexanone. Examples of the polymerization catalyst used include 2,2'-azobisisobutyronitrile (AIBN) and benzoyl peroxide.

  In addition, in order to improve adhesion, it is generally practiced to add tackifiers (tackifier resins) such as rosin resins, terpene resins, petroleum resins, styrene resins, and xylene resins. In the invention, when the pressure-sensitive adhesive film is peeled off, it is preferable not to use a tackifying resin because the pressure-sensitive adhesive may remain on the adherend or cause adhesion of contaminants.

  A crosslinking agent is added to the above-mentioned pressure-sensitive adhesive main agent in order to improve cohesive strength and anchorage with the substrate. Examples of the crosslinking agent include isocyanates, metal chelates, epoxies, and melamines. Particularly preferred is an isocyanate system, and more preferred is a polyfunctional isocyanate, for example, a trimethylolpropane adduct of tolylene diisocyanate. The amount of the cross-linking agent used is not particularly limited, but if the amount of the cross-linking agent added is small, the cross-linking is insufficient, resulting in an increase in adhesive force and a residual adhesive during re-peeling. Moreover, when there is much addition amount, bridge | crosslinking will become excessive and will cause the adhesion film to float. Therefore, it is preferable that the addition amount of a crosslinking agent is 0.2-5.0 mass parts with respect to 100 mass parts of adhesive main ingredients. More preferably, it is 0.5-2.0 mass parts.

  The pressure-sensitive adhesive has a gel fraction of 50% or more, a loss tangent (tan δ) peak temperature of −20 ° C. or lower, and a loss tangent within a temperature range of 10 to 40 ° C. of 0.2 to 0.8. In addition, the adhesive strength to the adherend is preferably 5 to 20 N / 25 mm, and more preferably 10 to 15 N / 25 mm. When the gel fraction is 50% or more, an appropriate cohesive force is obtained in the pressure-sensitive adhesive, and it is difficult for adhesive to remain even at high temperatures (40 ° C.). When the peak temperature of tan δ is −20 ° C. or lower, good adhesiveness can be maintained even at a low temperature. If the loss tangent within the temperature range of 10 to 40 ° C. is within the range of 0.2 to 0.8, the dynamic viscoelastic properties at the operating temperature (10 to 40 ° C.) will be optimal, and adhesion and It becomes what has releasability. Furthermore, if the adhesive strength to the adherend is within the range of 5 to 20 N / 25 mm, preferably 10 to 15 N / 25 mm, it has sufficient adhesiveness to support the sticker at the time of use, and at the time of replacement work Also, it has re-peeling performance that does not impair the peelability.

The application amount of the pressure-sensitive adhesive layer is preferably in the range of 10 to 40 g / m ² , particularly preferably 23 to 33 g / m ² . When it is 10 g / m ² or more, it is easy to obtain a suitable adhesive force, and when it is 40 g / m ² or less, it is difficult for the adhesive to stick out during printing of the decorative layer or die cutting, and good workability can be obtained. Cheap.

[Vehicle sticker adhesive film]
The adhesive film for vehicle stickers of the present invention is an adhesive film in which an adhesive layer is provided on one surface of the concealing base material. In the case where one surface of the concealing substrate is a concealing layer and the other surface is a white resin film layer, it is preferable to provide an adhesive layer on the concealing layer side. The adhesive film for vehicle stickers of the present invention can realize high concealment property, low total light transmittance, good removability, and excellent combustion resistance, so that it can be used for in-car advertisements such as railway vehicles. It can be used suitably for a vehicle sticker to be used, and in particular, it can be suitably used for a vehicle sticker attached to a vehicle window portion or a vehicle inner wall (melamine resin decorative board) visually recognized from both sides. In particular, the melamine resin decorative board suitably used for the vehicle inner wall is less resistant to combustion than an adherend such as glass, but the adhesive film for a vehicle sticker of the present invention is a melamine resin decorative board. Combustion resistance suitable for an adherend can also be realized.

  The pressure-sensitive adhesive film for vehicle stickers of the present invention is used as a vehicle sticker by providing a decorative layer printed with coloring, characters, designs, etc. on one surface of a concealing base material. When the concealable substrate has a surface composed of a white resin film layer, it is preferable to provide a decorative layer on the white resin film layer side. The decoration layer can be formed by printing appropriate characters and designs by an offset printing method, a gravure printing method, a silk screen printing method, or the like. Moreover, when providing a printing layer on both surfaces and making it a vehicle sticker visually recognized from both surfaces, it should just provide a decorating layer similarly on the other surface (surface which provides an adhesive layer). .

  In addition, in order to improve the adhesion of the decorative layer to the concealing substrate, the white resin film layer surface or concealing ink layer surface of the concealing substrate is subjected to corona discharge treatment, electron beam irradiation treatment, plasma discharge treatment, etc. These surface treatments may be applied or an anchor coating agent may be applied. Examples of the anchor coating agent include chlorinated polyolefin resins such as chlorinated polyethylene and chlorinated polypropylene, modified polyolefin resins, polyacrylamine resins, polyethyleneimine resins, polyurethane resins, and the like. To those containing no chlorine atom.

  Furthermore, in order to improve the adhesiveness of the adhesive layer to the concealing layer of the concealing substrate or the decorative layer provided on the surface of the concealing layer, an anchor coating agent may be applied to these surfaces.

  In the present invention, the decoration layer used as a vehicle sticker can use a printing method and printing ink used for normal printing. Moreover, although an overlaminate layer may be provided on the surface of the decorative layer as necessary, the overlaminate layer is also produced by a commonly used biaxial stretching method and has a thickness of 20 to 40 μm. A polypropylene (OPP) film, a polyester (PET) film having a thickness of 12 to 25 μm, a polymethacrylic resin (PMMA) film having a thickness of 25 to 50 μm, and a thickness of 25 to 25 when weather resistance and antifouling properties are required. Laminate films such as 50 μm fluororesin (ethylene-tetrafluoroethylene copolymer resin film, polyvinylidene fluoride (acrylic alloy) resin film) can be laminated. According to the pressure-sensitive adhesive film of the present invention, suitable flame resistance can be realized even with a decorative layer made of these ordinary printing inks or a general overlaminate layer.

  The thickness of the overlaminate layer is not particularly limited as long as it is a range usually used as a sticker application, but a thickness of 100 μm or less, preferably 80 μm or less is preferable because particularly suitable combustion resistance can be easily obtained.

  The thickness of the adhesive film for vehicle stickers of the present invention is preferably in the range of 35 to 300 μm, and particularly preferably 100 to 200 μm. By making the total thickness of the pressure-sensitive adhesive film within the above range, it is preferable because raw material costs can be reduced and it is easy to obtain suitable workability and peeling workability for the adherend.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the examples, “parts” and “%” are based on mass unless otherwise specified.

[Formation of concealment layer]
<Concealing ink 1 (black)>
The ink was prepared using the following composition. 100 parts of gravure ink “Hiramic” 795R black ink manufactured by Dainichi Seika Kogyo Co., Ltd., 5 parts of NT-Himirak anti-blocking agent, 3 parts of NT-Himirac hardener, Himirac No. 10 parts by weight of two solvents were added, and the mixture was sufficiently stirred with a dispersion stirrer until the contents were uniformly mixed.

<Concealing ink 2 (beige)>
The ink was prepared using the following composition. 100 parts of gravure ink "Hiramic" 701R White manufactured by Dainichi Seika Kogyo Co., Ltd. 0.3 parts of 795R ink, 0.5 parts of 722R yellow, 0.2 parts of 902R red, NT-Himirak anti-blocking agent 5 parts, NT-Himirak Hardener 3 parts, Himirac No. Two solvents (5 parts by weight) were added, and the mixture was sufficiently stirred with a dispersion stirrer until the contents were uniformly mixed.

[Preparation of dry laminate adhesive D]
90 parts by mass of an adhesive main agent (DIC Graphics LX-901 manufactured by DIC Graphics Co., Ltd.) and 10 parts by mass of a curing agent (manufactured by DIC Graphics Co., Ltd., trade name: KW75) are mixed with 10 parts by mass of ethyl acetate. A dry laminate adhesive D was prepared by diluting and stirring well.

[Creation of concealable substrate]
<Concealing base material 1>
Corona discharge-treated surface of white unstretched polyethylene (PE) film “Toughper TKP ADI 0.08” (thickness 80 μm, total light transmittance (τt) 17.6%) manufactured by Tatsuno Chemical Co., Ltd. as a white resin film layer On the side, the concealing ink 1 was applied using a wire bar so that the thickness of the concealing layer after drying was 4 μm and dried at 80 ° C. for 1 minute to form the concealing layer 1 to obtain the concealing substrate 1. .

<Concealing base material 2>
A concealing base 2 was obtained by forming a concealing layer 2 in the same manner as the concealing base 1 except that the concealing ink 2 was used.
<Concealing base material 3>
Corona discharge-treated surface of white unstretched polyethylene (PE) film “Toughper TKP ADI 0.08” (thickness 80 μm, total light transmittance (τt) 17.6%) manufactured by Tatsuno Chemical Co., Ltd. as a white resin film layer On the side, an aluminum vapor deposition film was formed to a thickness of 45 ± 5 nm by depressurization and vapor deposition of 10-2 Pa.

<Concealing base material 4>
As white resin film layer, white unstretched polyethylene (PE) film manufactured by Tatsuno Chemical Co., Ltd. “Toughper TKP ADI 0.08” (thickness 80 μm, total light transmittance (τt) 17.6%) corona discharge treated surface side The adhesive D was applied so that the coating amount after drying was 2 ± 1 g / m ^2, and after drying by heating at 80 ° C. for 1 minute, 12 μm of aluminum foil “Super Foil” manufactured by Toyo Aluminum Co., Ltd. was pasted. Cured for 48 hours.

<Concealing base material 5>
The white resin film layer was concealed except that a white unstretched polypropylene (CPP) film “Art Ply W” (thickness 80 μm, total light transmittance (τt) 15.2%) manufactured by Mitsubishi Plastics Co., Ltd. was used. A concealable substrate 5 was obtained in exactly the same manner as the substrate 1.

<Concealing base material 6>
The white resin film layer was concealed except that a white unstretched polypropylene (CPP) film “Art Ply W” (thickness 80 μm, total light transmittance (τt) 15.2%) manufactured by Mitsubishi Plastics Co., Ltd. was used. A concealable substrate 6 was obtained in exactly the same manner as the substrate 2.

<Concealing base material 7>
Except for using “white unstretched polybutylene terephthalate (PBT) film” (thickness 100 μm, total light transmittance (τt) 13.7%) manufactured by Toyo Kohan Co., Ltd. Thus, a concealable base material 7 was obtained.

<Concealing base material 8>
Apply to the coating surface side of the masking ink 1 of the masking substrate 1 so that the coating amount after drying dry lame adhesive D is 2.0 ± 1.0 g / m ^2, and heat-dry at 80 ° C. for 1 minute. Then, after the opposite surface side of the concealing layer 2 of the concealing base material 2 was bonded, it was cured at 40 ° C. for 48 hours to obtain the concealing base material 8.

<Concealing base material 9>
After coating the concealable ink 5 on the surface of the concealable ink 5 so that the coating amount after drying dry lame adhesive D is 2.0 ± 1.0 g / m ² , heat drying at 80 ° C. for 1 minute. Then, after the opposite surface side of the concealing layer 2 of the concealing base 6 was bonded, it was cured at 40 ° C. for 48 hours to obtain the concealing base 9.

<Concealing base material 10>
A concealable base material 2 except that a foamed expanded polypropylene (foamed PP) film “YUPO SGS80” (thickness 80 μm, total light transmittance (τt) 17.8%) manufactured by YUPO Corporation is used as a white base material. The concealable base material 10 was obtained in exactly the same manner as above.

<Concealing base material 11>
Concealable base material 2 except that Toyobo Co., Ltd. foamed stretched polyester film (foamed PET) “Crisper K2411” (thickness 50 μm, total light transmittance (τt) 13.4%) was used as the white base material. The concealable base material 11 was obtained in exactly the same manner as above.

<Concealing base material 12>
The white resin film layer was concealed except that Nakamoto Pax Co., Ltd. expanded polypropylene (foamed PP) film “Carle TNRK” (thickness 70 μm, total light transmittance (τt) 18.0%) was used. A concealable substrate 12 (a) was obtained in exactly the same manner as the substrate 1.

  The white resin film layer was concealed except that Nakamoto Pax Co., Ltd. expanded polypropylene (foamed PP) film “Carle TNRK” (thickness 70 μm, total light transmittance (τt) 18.0%) was used. A concealable substrate 12 (b) was obtained in exactly the same manner as the substrate 2.

The concealable base material 12 (a) is coated on the concealing ink 1 side of the concealing ink 1 so that the coating amount after drying dry lame adhesive D is 2 g / m ^2, and after heat drying at 80 ° C. for 1 minute, the concealing property After the opposite surface side of the masking layer 2 of the base material 12 (b) was bonded, it was cured at 40 ° C. for 48 hours to obtain the masking base material 12.

<Concealing base material 13>
The concealing group was the same as the concealing base material 2 except that a biaxially stretched polypropylene (OPP) film “OP U-1” (thickness 50 μm) manufactured by Mitsui Chemicals, Inc., Cello Co., Ltd. was used as the resin film. Material 13 was obtained.

<Preparation of acrylic copolymer>
In a reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel, and a nitrogen gas inlet, 100 parts by mass of the monomer mixture blended in the combination of Table 2 and 2,2′-azobis as a polymerization initiator 0.2 parts by mass of isobutylnitrile was dissolved in 100 parts by mass of ethyl acetate and polymerized at 80 ° C. for 8 hours to obtain solutions of acrylic copolymers A and B.
In addition, the meaning of the abbreviation of the monomer used in Table 2 is as follows.

2EHA: 2-ethylhexyl acrylate BA: n-butyl acrylate MA: methyl acrylate VA: vinyl acetate AA: acrylic acid HEA: 2-hydroxyethyl acrylate

<Preparation of adhesive agent solutions A and B>
Adhesive main agents A and B in Table 3 were obtained by mixing 100 parts by mass of an acrylic copolymer with toluene and diluting to obtain an adhesive main agent solution having a solid content of 45%.

<Creation of adhesive film>
An isocyanate-based cross-linking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate L-45) is added as shown in Table 3 to the solution of the pressure-sensitive adhesive main agents A and B, followed by stirring and coating after drying. By coating on release paper (Separate 110EPS (P) (3) Blue) manufactured by Oji Paper Co., Ltd.) that has been release-treated so that the amount is 28 g / m ^2, and drying at 80 ° C. for 2 minutes, A pressure-sensitive adhesive layer composed of pressure-sensitive adhesives A1 and B1 was formed.
Furthermore, as shown in Tables 4-5, the adhesive films 1-13 (Example 1) are obtained by laminating the release paper coated with the adhesive layers A1, B1, in combination with the concealing base materials 1-9. To 9 and Comparative Examples 1 to 4) were obtained.

  The evaluation of the concealable base material, the adhesive film, and the vehicle sticker was performed by the following test. The obtained results are shown in each table.

<Total light transmittance (τt) measurement method>
The total light transmittance of the concealable substrate was measured according to JIS K 7361-1. The measuring device was measured using a haze transmittance measuring device “HR-100” manufactured by Murakami Color Research Laboratory.

<Whiteness measurement method>
The whiteness of the concealing substrate was measured according to JIS P 8148 using an ISO whiteness / opacity measuring instrument “WMS-1” manufactured by Murakami Color Research Laboratory.

<Measurement of weight average molecular weight>
The average molecular weights of the adhesive main agents A and B are in terms of polystyrene using a GPC device (manufactured by Tosoh Corp., product number SC-8020) and a high molecular weight column (manufactured by Tosoh Corp., product number TSKgelGMHR-H) with tetrahydrofuran as the mobile phase. The weight average molecular weight of the acrylic copolymer was measured.

<Measurement of dynamic viscoelasticity>
Adhesive layers A1 to B1 obtained by adding a crosslinking agent to the adhesive main agent were laminated to a thickness of 5 mm to prepare test pieces. A viscoelasticity tester (manufactured by Rheometrics, trade name: Ares 2KSTD) is fitted with a 7.9 mm parallel plate, and a test piece is sandwiched between the storage elastic modulus (G ′) from −50 ° C. to 150 ° C. at a frequency of 1 Hz Loss modulus (G ″) was measured to obtain a tan δ peak temperature and a tan δ value of 10 to 40 ° C. The loss tangent tan δ was calculated from the following calculation formula.
Loss tangent tan δ = G ″ / G ′

<Measurement of gel fraction>
A test piece was prepared by providing a pressure-sensitive adhesive layer obtained by adding a crosslinking agent to a pressure-sensitive adhesive main agent on a polyester film (exfoliated) so that the thickness after drying was 25 μm. The test piece was cut into a size of 20 mm × 100 mm, the polyester film was peeled off, and the weight a before toluene extraction was measured. Next, after the same test piece was immersed in toluene for 24 hours, the gel was taken out and dried at 100 ° C. for 2 hours, and the weight b after toluene extraction was measured. The gel fraction was calculated from the following formula.
Gel fraction (%) = (b / a) × 100

<Measurement of adhesive strength>
About each adhesive film, the adhesive force with respect to various to-be-adhered bodies was affixed in the environment of 23 degreeC and 50% RH according to the conditions of 2000 version of JISZ0237, and measured 1 hour afterward. As the adherend, a melamine resin decorative board (ALH-8725S manufactured by Hitachi Chemical Co., Ltd.) was used.

<Removability evaluation method>
A sample 25 mm wide × 100 mm long was cut out from each adhesive film and applied to various adherends (same as those used in the measurement of adhesive strength) in a room temperature environment (23 ° C. × 50% RH). Reciprocate with a 2 kg roller and crimp. Then, after standing in an environment of 40 ° C. for 168 hours, the adhesive film was peeled off by the state of glue residue when peeled off at a speed of 20 m / min in the direction of 90 ° with respect to the adherend using a tensile tester. The removability was visually evaluated according to the following criteria.
A: No adhesive residue left (less than 5% adhesive residue)
○: There is glue residue at the end of peeling or at the end of peeling (less than 5% and less than 10%)
Δ: Slightly adhesive residue (from 10% to less than 20%)
×: Adhesive residue is present over a wide area (adhesive residue is 20% or more)
XX: Interlaminar fracture of substrate

<Combustion test method>
The combustion test was performed as follows according to the railway vehicle combustion test method, and evaluated according to the criteria.
As shown in FIG. 1, a B5-size specimen (182 mm × 257 mm) is held at a 45 ° inclination, and the center of the bottom of the fuel container is vertically 25.4 mm (1 inch) below the center of the bottom of the specimen. Then, place it on a base of low heat conductivity such as cork, put 0.5 cc of pure ethyl alcohol, ignite, and let it stand until the fuel is burned out.
Combustion judgment is divided into alcohol combustion and after combustion. During combustion, the specimen is observed for ignition, ignition, smoke generation, flame condition, etc. After combustion, afterflame, residual dust, Investigate carbonization and deformation state.
The conditions in the test chamber are 15 ° C. to 30 ° C. and 60% to 75% humidity.
The judgment criteria are shown in Table 1.

Preparation of test specimen sample for combustion test The test specimen sample of the vehicle sticker used for the test is appropriately subjected to multicolor printing design by UV offset printing on the surface of each of the above adhesive films (Examples 1 to 9 and Comparative Examples 1 to 3). After that, a biaxially stretched polypropylene (OPP) film “OPU-1” (20 μm) manufactured by Mitsui Chemicals Tosero Co., Ltd. was used with an adhesive D (coating amount 1.0 ± 0.5 g / m ² after drying). And used a laminated material.
As the adherend used for the test, ALH-8725S (melamine resin decorative board; t = 1.4 mm) manufactured by Hitachi Chemical Co., Ltd. was used. The pressure-sensitive adhesive film was affixed to the entire surface of the adherend having the specified size with a clean surface so as not to leave as much air as possible, and tested after curing at room temperature for 24 hours or more.

As described above, the films of Examples 1 to 9 all maintained high light shielding properties, and no substrate destruction or adhesive residue occurred during peeling. In addition, since non-stretched film was used, it showed non-flammability in the results of the rail car material combustion test. Furthermore, it does not use polyvinyl chloride-based materials or flame retardants, which can contribute to reducing environmental impact.
Since all of Comparative Examples 1 to 4 used a stretched film as the base film of the concealable base material, they were moderately flammable in the railway vehicle combustion test. Moreover, in Comparative Examples 1-2, the interlaminar fracture was caused during the removability test, and in Comparative Example 4, good total light transmittance was not obtained.

1 Test piece 2 Alcohol container 3 Container cradle

Claims (13)

An adhesive film used for a vehicle sticker to be affixed in a vehicle,
A concealable base material having at least a white resin film layer and a concealing layer, and an adhesive layer;
The white resin film layer is made of an unstretched resin film having a titanium dioxide content of 5 to 30% by mass and a thickness of 25 to 100 μm,
An adhesive film for vehicle stickers which is nonflammable in the following combustion test.
<Combustion test>
A B5-size test material (182mm x 257mm) with an adhesive film affixed to a melamine resin decorative board is held at an angle of 45 ° so that the adhesive film surface is on the flame contact side, and the center of the bottom of the fuel container is the test material Put it on a base made of a material with low thermal conductivity such as cork so that it is 25.4 mm (1 inch) vertically below the center of the bottom surface, put 0.5 cc of pure ethyl alcohol and ignite, and the fuel will burn out Leave until. The pressure-sensitive adhesive film for a vehicle sticker according to claim 1, wherein the concealable base material is a concealable base material having two layers of the white resin film layer.   The pressure-sensitive adhesive film for a vehicle sticker according to claim 1, wherein the concealable substrate is a concealable substrate having a concealing layer on one side of a white resin film layer, and further having a white resin film layer on the concealing layer. .   The pressure-sensitive adhesive film for a vehicle sticker according to claim 1, wherein the concealable base material is a concealable base material laminated in the order of a white resin film layer / a concealment layer / a white resin film layer / a concealment layer. The adhesive film for a vehicle sticker according to any one of claims 1 to 4, wherein the white resin film layer has a total light transmittance of 20% or less. The pressure-sensitive adhesive film for a vehicle sticker according to any one of claims 1 to 5, wherein the concealable substrate has a total light transmittance of 5% or less and a whiteness of at least one surface of 75% or more. The said white resin film layer consists of a resin film which uses at least 1 type of a polyethylene resin, a polypropylene resin, or a polybutylene terephthalate resin as a main resin component, and does not contain a polyvinyl chloride resin. Adhesive film for vehicle stickers. The adhesive film for a vehicle sticker according to any one of claims 1 to 7, wherein the concealing layer is a colored ink layer. The pressure-sensitive adhesive film for a vehicle sticker according to any one of claims 1 to 8, wherein the concealable base material has a thickness of 25 to 220 µm. The pressure-sensitive adhesive film for a vehicle sticker according to any one of claims 1 to 9 , wherein the pressure-sensitive adhesive layer has a gel fraction of 50 to 80%. The vehicle sticker which has a decorating layer in at least one surface of the concealable base material of the adhesive film for vehicle stickers in any one of Claims 1-10 . The vehicle sticker according to claim 11 , wherein a biaxially stretched film is over-laminated on the surface of the decorative layer. A vehicle sticker sticking method comprising sticking the vehicle sticker according to claim 11 or 12 to a vehicle inner wall made of a melamine resin decorative board.

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