JP2021059033A - Transfer film - Google Patents

Abstract

To provide a transfer film in which adhesion between a base material film and a transfer layer is excellent, and detachability of the base material film after transfer is excellent.SOLUTION: Provided is a transfer film having transfer layers on a base material film, the transfer layers at least including a first transfer layer, the first transfer layer being a layer nearest to the base material film in the transfer layers, and the first transfer layer containing an acrylic polymer and a melamine compound.SELECTED DRAWING: None

Description

The present invention relates to a transfer film. More specifically, the present invention relates to a transfer film for transferring a transfer layer to an adherend.

A transfer layer including a hard coat layer and a decorative layer is transferred for surface protection or decoration of a resin molded product such as a home electric appliance or an automobile interior part (Patent Documents 1 and 2).

Further, in order to protect an electronic circuit from electromagnetic waves, an electromagnetic wave shield layer (electromagnetic wave shield film) including an insulating layer and a conductive layer is transferred to a circuit board by a heating press (Patent Documents 3 to 5). ..

The transfer layer described above may be required to have a matte appearance, and it has been proposed to impart fine irregularities to the surface of the transfer layer. Further, in the above-mentioned transfer film, a transfer layer is laminated on the base film via a release layer in order to improve the peelability of the transfer layer.

Japanese Unexamined Patent Publication No. 2011-148103 Japanese Unexamined Patent Publication No. 2015-214032 Japanese Patent No. 5796690 Japanese Patent No. 6014680 Japanese Patent No. 6426865

Generally, a transfer layer such as a hard coat layer or an electromagnetic wave shield layer is transferred to an adherend via an adhesive layer. In this transfer step, it is often heat pressed. After the transfer layer of the transfer film is transferred to the adherend, the base film constituting the transfer film is peeled off. At this time, it is desirable that the base film is relatively easily peeled off. On the other hand, it is desirable that the transfer film has a relatively high adhesion between the transfer layer and the base film so that the transfer layer does not easily peel off from the base film in the manufacturing process or the processing process.

That is, it is desirable that the transfer film as described above has good adhesion between the base film and the transfer layer, and the base film can be relatively easily peeled off from the transfer layer after transfer.

As described above, in the conventional transfer film, the transfer layer is generally laminated on the base film via the release layer, and the peelability of the base film after transfer is relatively good. The adhesion between the base film of the transfer film and the transfer layer was insufficient.

On the other hand, when the transfer layer is directly laminated on the base film without interposing a release layer or the like, the adhesion between the base film and the transfer layer is relatively high, but the peelability of the transfer layer tends to be poor. is there.

Therefore, an object of the present invention is to provide a transfer film having good adhesion between the base film and the transfer layer and good peelability of the base film after transfer.

The above object of the present invention has been achieved by the following invention.
[1] A transfer film having a transfer layer on a base film, wherein the transfer layer includes at least a first transfer layer, and the first transfer layer is a layer closest to the base film among the transfer layers. A transfer film in which the first transfer layer contains an acrylic polymer and a melamine compound.

According to the present invention, it is possible to provide a transfer film having good adhesion between the base film and the transfer layer and good peelability of the base film after transfer.

According to a preferred embodiment of the present invention, a good matte appearance can be imparted to the transfer layer. Further, according to a preferred embodiment of the present invention, the adhesion when joining another member to the transfer layer transferred to the adherend via the adhesive layer (adhesive sheet) is improved.

The transfer film of the present invention is for transferring a transfer layer provided on a base film to an adherend, for example, an adherend such as a home electric appliance, an automobile interior component, or a circuit board. After the transfer layer of the transfer film is transferred to the adherend, the base film is peeled off.

The transfer film of the present invention has a transfer layer on the base film, the transfer layer includes at least the first transfer layer, and the first transfer layer is the layer closest to the base film among the transfer layers. 1 The transfer layer contains an acrylic polymer and a melamine compound.

When the first transfer layer contains the acrylic polymer and the melamine compound, the adhesion between the base film and the first transfer layer is improved, and the peelability of the base film after transfer is improved.

[First transfer layer]
The first transfer layer contains at least an acrylic polymer and a melamine compound.

Examples of the acrylic polymer used for the first transfer layer include a homopolymer of (meth) acrylic acid ester and a copolymer containing at least one compound copolymerizable with (meth) acrylic acid ester. Here, the (meth) acrylic acid ester is a general term including an acrylic acid ester and a methacrylic acid ester. Further, in the following description, (meth) acrylate is a general term including acrylate and methacrylate.

Examples of the homopolymer of the (meth) acrylic acid ester include homopolymers of methyl (meth) acrylate and homopolymers of butyl (meth) acrylate.

Examples of the compound copolymerizable with the (meth) acrylic acid ester include vinyl group-containing monomers such as N-vinylpyrrolidone, N-vinylcaprolactone, vinylimidazole, vinylpyridine, and styrene, lauryl (meth) acrylate, and stearyl (meth). ) Acrylate, Butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, phenoxyethyl acrylate, paracumylphenoxy Ethyl (meth) acrylate, nonylphenoxy polyethylene glycol (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl methacrylate, N, N-dimethyl (meth) acrylamide, N, Examples thereof include (meth) acrylic acid ester monomers such as N-dimethylaminopropyl (meth) acrylate and acryloylmorpholin, and (meth) acrylamide derivatives.

The weight average molecular weight of the acrylic polymer is preferably 7,000 to 150,000, more preferably 10,000 to 130,000, and particularly preferably 12,000 to 100,000. By using such an acrylic polymer, the first transfer layer tends to have an appropriate film hardness, the adhesion between the base film before transfer and the first transfer layer tends to be good, and the base film after transfer is peeled off. It tends to be good. That is, when the film hardness of the first transfer layer is low, the peelability of the base film after transfer tends to be poor, while when the film hardness of the first transfer layer is high, the base film before transfer and the first transfer are performed. Although the adhesion to the layer tends to be poor, by setting the weight average molecular weight of the acrylic polymer in the above range, the first transfer layer can easily satisfy the above-mentioned contradictory properties at the same time.

As the acrylic polymer, it is preferable to use a plurality of types of acrylic polymers having different weight average molecular weights in combination. As a result, the film hardness of the first transfer layer can be finely adjusted, and the adhesion between the base film before transfer and the first transfer layer and the peelability of the base film after transfer are improved. Further, the adhesion between the first transfer layer transferred to the adherend and the adhesive layer (adhesive sheet) is likely to be improved. The adhesion between the first transfer layer and the adhesive layer (adhesive sheet) will be described in detail later.

Regarding the combined use of a plurality of types of acrylic polymers having different weight average molecular weights, specifically, an acrylic polymer (1) having a weight average molecular weight of less than 30,000 and an acrylic polymer (2) having a weight average molecular weight of 30,000 or more are used in combination. It is preferable to do so.

The weight average molecular weight of the acrylic polymer (1) is preferably 25,000 or less, more preferably 20,000 or less. The lower limit is preferably 7,000 or more. The weight average molecular weight of the acrylic polymer (2) is preferably 35,000 or more, more preferably 40,000 or more. The upper limit is preferably 100,000 or less.

The combined ratio of the acrylic polymer (1) and the acrylic polymer (2) is preferably 90:10 to 10:90, more preferably 80:20 to 20:80, and particularly 75:25 to 25:75 in terms of mass ratio. preferable.

A commercially available product can be used as the acrylic polymer. Examples of commercially available products include "Acryt (registered trademark)" 0502TC, 0404TA-P, 0403KA, 0404TB, 0KW-005, etc. of Taisei Fine Chemicals Co., Ltd.

The melamine compound used for the first transfer layer will be described in detail. A melamine compound is a compound obtained by subjecting various modifications to the amino group of so-called melamine [1,3,5-triazine-2,4,6-triamine] in which an amino group is bonded to each of the three carbon atoms of the triazine ring. It is a general term for, and includes those in which a plurality of triazine rings are condensed.

As the type of modification, a methylolated melamine compound in which at least one of the six hydrogen atoms of the three amino groups is methylolated is preferable, and a methylolated melamine compound in which all six hydrogen atoms are methylolated is preferable. More preferably, an alkyl etherified melamine compound obtained by partially or completely etherifying the methylol group of the methylolated melamine compound with a lower alcohol having 1 to 4 carbon atoms is more preferable, and a partially etherified alkyl etherified melamine compound is preferable. Especially preferable. That is, a partially alkyl etherified melamine compound in which the methylol group of the methylolated melamine compound in which all six hydrogen atoms are methylolated is partially etherified is particularly preferable.

As the alkyl of the above alkyl etherified melamine compound, an alkyl group having 1 to 4 carbon atoms is preferable, and a butyl group is particularly preferable.

The degree of etherification of the above partially alkyl etherified melamine is preferably 10 to 95%, more preferably 15 to 90%, and particularly preferably 20 to 80%. Here, the degree of etherification is the ratio of the molar amount of etherified methylol groups to the total molar amount of etherified methylol groups and non-etherified methylol groups. The degree of etherification can be controlled, for example, by adjusting the amount of alcohol added for etherification.

Examples of the alcohol used for etherification include methyl alcohol, ethyl alcohol, propyl alcohol and butyl alcohol.

Commercially available products can be used as the melamine compound. Examples of commercially available products include "Super Beccamin (registered trademark)" L-105-60, J-820-60, J-821-60, J-1090-65, and J of DIC Co., Ltd. -110-60, J-117-60, J-127-60, J-166-60B, J-105-60, G840, G821, Mitsui Chemicals, Inc. "Uban (registered trademark)" ) "20SB, 20SE60, 21R, 22R, 122, 125, 128, 220, 225, 228, 28-60, 2020, 60R, 62, 62E, 360. , 165, 166-60, 169, 2061, Sumitomo Chemicals Co., Ltd. "Sumimar (registered trademark)" M-100, M-40S, M-55, M-66B, Nippon Cytec Industries "Simel (registered trademark)" 303, 325, 327, 350, 370, 235, 202, 238, 254, 272, 1130, Sanwa Chemicals Co., Ltd. Registered trademarks) "MS17, MX15, MX430, MX600, Harima Kasei Co., Ltd.'s Vancemin SM-975, SM-960, Hitachi Kasei Co., Ltd.'s" Melan (registered trademark) "265, 2650L, etc. Can be mentioned.

Regarding the content ratio of the acrylic polymer and the melamine compound in the first transfer layer, the content of the melamine compound is preferably 10 to 100 parts by mass with respect to 100 parts by mass of the acrylic polymer, and is 15 to 80 parts by mass. Is more preferable, and 20 to 75 parts by mass is particularly preferable.

The first transfer layer may contain a resin other than the acrylic polymer, and examples thereof include an alkyd resin, an epoxy resin, a polyester resin, and a polyether resin. Of these, alkyd resin is preferable.

Examples of the alkyd resin include those obtained by modifying a condensate of a polybasic acid and a polyhydric alcohol with a fat or fatty acid. Here, the polybasic acid also includes an anhydride of the polybasic acid.

Examples of the polybasic acid include phthalic anhydride, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, tetrahydrophthalic anhydride, and hexahydro. Phthalic anhydride, 1,4-cyclohexanedicarboxylic acid, hetic anhydride, malonic acid, ethylmalonic acid, dimethylmalonic acid, succinic acid, dimethylsuccinic anhydride, succinic anhydride, alkenyl succinic anhydride, glutaric acid, adipic acid, pimerin Examples thereof include acids, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic anhydride, itaconic acid, hymic anhydride, trimellitic anhydride, pyromellitic anhydride, methylcyclohexylhexcentricarboxylic anhydride and benzophenonetetracarboxylic acid. , These can be used alone or in combination of two or more.

Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, butylene glycol, hexanediol, neopentyl glycol, octanediol, butylethylpropanediol, bisphenol A, and hydrogen. Bisphenol A, Bisphenol F, Glycerin, Diglycerin, Triglycerin, Trimethylol Ethan, Trimethylol Propane, Pentaerythritol, Dipentaerythritol, Mannitol, Sorbitol, etc., which may be used alone or in combination of two or more. be able to.

Examples of fats and oils include flaxseed oil, millet oil, safflower oil, soybean oil, tall oil, nuka oil, palm oil, sunflower oil, dehydrated sunflower oil, sunflower oil, palm oil, and the like. Two or more types can be used in combination.

Examples of fatty acids include the above-mentioned fatty acids derived from fats and oils, the following synthetic fatty acids, and the like, and these can be used alone or in combination of two or more.

Examples of synthetic fatty acids include caproic acid, caprylic acid, caproic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, ricinolic acid, linoleic acid, linolenic acid, eleostearic acid, arachidic acid, and arachidonic acid. , Bechenic acid, basatic acid (manufactured by Shell) and the like, and these can be used alone or in combination of two or more.

Further, the alkyd resin may be modified with various resins. Examples of such alkyd resins include amino-modified alkyd resins, rosin-modified alkyd resins, phenol-modified alkyd resins, epoxy-modified alkyd resins, acrylicized alkyd resins, and urethane-modified alkyd resins.

Commercially available products can be used as the alkyd resin. Examples of commercially available products include "Archidia (registered trademark)" 1307-60-EL, 1308-E, ER-3653-60, ER-4005-60, and EZ-3065-P of DIC Corporation. , EZ-3509-60, EZ-3801-60, OD-E-198-50, OD-E-230-70, OD-E-230-70-E, J-524-IM -60, Arakawa Chemical Industry Co., Ltd. "Arakid (registered trademark)" IA-120-60L, 1782-60, 3101X-60, Harima Chemicals Group "Hariftal (registered trademark)" 732-60, 915- Examples thereof include 60L, COG40-50T, SB-7150X, SB-7540, Hitachi Chemicals Co., Ltd. "Tessfine (registered trademark)" 303, 305, and 314.

Regarding the content ratio of the acrylic polymer and the alkyd resin in the first transfer layer, the content of the alkyd resin with respect to 100 parts by mass of the acrylic polymer is preferably 1 to 50 parts by mass, more preferably 5 to 40 parts by mass, and 7 to 25 parts by mass. The part is particularly preferable.

By using the acrylic polymer and the alkyd resin in combination, the adhesion between the first transfer layer transferred to the adherend and the adhesive layer (adhesive sheet) can be easily improved.

The first transfer layer preferably contains an acid catalyst in order to accelerate the curing of the melamine compound. Examples of the acid catalyst include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, p-toluenesulfonic acid and the like. Among these, p-toluenesulfonic acid is preferably used.

When the first transfer layer contains an acid catalyst, the content of the acid catalyst is preferably in the range of 1 to 25 parts by mass, more preferably in the range of 2 to 20 parts by mass, with respect to 100 parts by mass of the melamine compound. The range of ~ 15 parts by mass is particularly preferable.

The first transfer layer is preferably formed by applying a coating composition (coating liquid) containing at least an acrylic polymer and a melamine compound onto a base film, drying, and heat-curing. That is, the coating composition for forming the first transfer layer is preferably a thermosetting composition. The coating composition preferably contains the above-mentioned acid catalyst.

The conditions (heating temperature, time) for curing the coating composition (thermosetting composition) are not particularly limited, but the heating temperature is preferably 70 ° C. or higher, more preferably 100 ° C. or higher, and particularly preferably 150 ° C. or higher. .. The upper limit is about 300 ° C. The heating time is preferably 3 to 400 seconds, more preferably 5 to 300 seconds, and particularly preferably 10 to 200 seconds.

The coating composition (coating liquid) can be applied, for example, on a base film by a wet coating method. Examples of such a wet coating method include a reverse coating method, a spray coating method, a bar coating method, a gravure coating method, a rod coating method, a die coating method, a spin coating method, an extrusion coating method, a curtain coating method and the like.

The first transfer layer may be laminated on the base film via another layer, for example, a release layer, but is preferably laminated directly on the base film. By directly laminating the first transfer layer on the base film, the number of laminating can be reduced to improve productivity and material cost, and since the release layer does not intervene, the first transfer layer The release component does not transfer to. When the release component is transferred to the first transfer layer, post-processing after transfer, for example, when the adherend to which the first transfer layer is transferred and another member are adhered via the first transfer layer. Adhesion may be reduced, but this problem can be avoided.

Further, by directly laminating the first transfer layer on the base film, when the base film has fine irregularities on the surface as described later, the irregularities are efficiently transferred to the first transfer layer. , It is preferable because it can give an effective matte appearance to the first transfer layer.

Even when the first transfer layer is directly laminated on the base film, the base film and the first transfer layer are appropriately adhered to each other because the first transfer layer contains the acrylic polymer and the melamine compound. Moreover, the peelability of the base film after transfer is improved.

It is preferable that the outer surface of the first transfer layer transferred to the adherend (the surface opposite to the adherend side of the first transfer layer) is imparted with a matte appearance. That is, it is preferable that the first transfer layer is a matte layer. This can be achieved, for example, by forming a fine concavo-convex structure on the surface of the base film on which the first transfer layer of the transfer film is laminated on the side of the first transfer layer. The details of the fine uneven structure of the base film will be described later.

The degree of matte appearance of the outer surface of the transferred first transfer layer can be expressed by a glossiness of 60 degrees. The 60-degree glossiness of the outer surface of the transferred first transfer layer is preferably less than 30, more preferably less than 20.

The peeling position between the first transfer layer and the base film after transfer may be the interface between the first transfer layer and the base film (interfacial peeling), or within the layer of the first transfer layer (intra-layer peeling). ) May be. Here, the intra-layer peeling of the first transfer layer means that a part of the first transfer layer is peeled off to the base film side without being peeled cleanly at the interface between the first transfer layer and the base film. means.

The thickness of the first transfer layer is preferably relatively large, preferably 0.5 μm or more, preferably 0.7 μm, in consideration of the above-mentioned in-layer peeling and the case of imparting a matte appearance. The above is more preferable, and 1.0 μm or more is particularly preferable. The thickness is preferably 10.0 μm or less, more preferably 7.0 μm or less, and particularly preferably 5.0 μm or less, from the viewpoint of peelability of the base film after transfer.

[Transfer layer]
The transfer layer in the present invention may be composed of only the first transfer layer, or may be composed of the first transfer layer and the second transfer layer. The second transfer layer is laminated on the first transfer layer laminated on the base film. The second transfer layer may be composed of a single layer or a plurality of layers. In the present invention, the transfer layer preferably includes a first transfer layer and at least one second transfer layer.

The second transfer layer is preferably a functional transfer layer having various functions. The second transfer layer having functionality is not particularly limited, but for example, a hard coat layer, a primer layer, a decorative layer, a protective layer, an insulating layer, a metal layer, a conductive layer, a concealing layer, an adhesive layer, and a conductive adhesive. Examples thereof include functional layers such as an agent layer, and these second transfer layers may be a single layer or a laminated layer of two or more layers.

The transfer film of the present invention is suitable for producing an electromagnetic wave shielding film for a circuit board such as a flexible printed wiring board. The electromagnetic wave shielding film is usually composed of an insulating layer, a metal layer, a conductive adhesive layer, and the like. That is, when the transfer film of the present invention is applied to the production of an electromagnetic wave shielding film, the second transfer layer preferably contains at least one layer selected from the group consisting of an insulating layer, a metal layer and a conductive adhesive layer. .. Further, the second transfer layer preferably includes an insulating layer and a conductive adhesive layer in this order from the first transfer layer side.

Conventionally, as a transfer film for producing an electromagnetic wave shielding film, an insulating layer (protective layer) is laminated on a base film (usually including a release layer), and a metal layer or a conductive adhesive layer is laminated on the insulating layer. Are known to be laminated. The first transfer layer in the transfer film of the present invention can also serve as an insulating layer, but it is preferable that the insulating layer is laminated on the first transfer layer separately from the first transfer layer as the second transfer layer. In this case, as described above, it is preferable that no release layer is interposed between the base film and the first transfer layer.

Regarding the insulating layer (protective layer), the metal layer, and the conductive adhesive layer, for example, Japanese Patent No. 5796690, 6014680, 6426865, 2018-41962, 2018-129472. , 2018-166166, 2018-166180, and the like can be used.

The second transfer layer is laminated, for example, by applying the coating liquid of the second transfer layer on the first transfer layer of the base film on which the first transfer layer is laminated by a wet coating method, and drying and if necessary. It can be formed by curing.

[Base film]
The base film is not particularly limited, and various plastic films can be used. For example, polyester film such as polyethylene terephthalate film, polybutylene terephthalate film, polyethylene naphthalate film, polyolefin film such as polypropylene film and polyethylene film, cellulose film such as diacetyl cellulose film and triacetyl cellulose film, polysulfone film and polyether. Examples thereof include ether ketone film, polyether sulfone film, polyphenylene sulfide film, polyetherimide film, polyimide film film, polyamide film, acrylic film, cyclic olefin film, polycarbonate film and the like.

Among these plastic films, a polyester film having good heat resistance and solvent resistance is preferable, a polyethylene terephthalate film is more preferable, and a biaxially stretched polyethylene terephthalate film is particularly preferable.

As described above, it is preferable that the outer surface of the first transfer layer transferred to the adherend (the surface opposite to the adherend side of the first transfer layer) is imparted with a matte appearance. For example, it can be realized by forming a fine concavo-convex structure on the surface of the base film on which the first transfer layer of the transfer film is laminated on the side of the first transfer layer.

The fine uneven structure of the surface on the side where the first transfer layer of the base film is laminated can be represented by the arithmetic mean roughness Ra. The arithmetic mean roughness Ra of the surface on the side where the first transfer layer of the base film is laminated is preferably 0.20 μm or more, more preferably 0.30 μm or more, and particularly preferably 0.35 μm or more. If the arithmetic average roughness Ra becomes too large, the coatability and peelability of the first transfer layer may deteriorate. Therefore, the arithmetic average roughness Ra is preferably 1.00 μm or less, more preferably 0.90 μm or less. , 0.80 μm or less is particularly preferable.

As a method of forming a fine concavo-convex structure having an arithmetic mean roughness Ra of 0.25 μm or more on the surface of the base film, a method of containing particles in the base film, a method of sandblasting the surface of the base film, and a method of sandblasting the surface of the base film are used. Examples include a method of embossing the film and a method of chemically treating the surface of the base film. Among these, a method of sandblasting the surface of the base film is preferable.

The base film may be colored to prevent forgetting to peel it off. Examples of the coloring method include a method of incorporating a coloring pigment in the base film and a method of laminating a coloring pigment layer on the transparent base film. As the coloring pigment, a white pigment having an average particle size of less than 1 μm, for example, a white pigment such as titanium dioxide or barium sulfate is preferably used.

As the base film, a polyethylene terephthalate film colored in white that has been sandblasted (sandblasted white PET film) is particularly preferably used.

The thickness of the base film is preferably 20 μm or more, more preferably 30 μm or more, and particularly preferably 40 μm, considering the case of forming a fine concavo-convex structure. The thickness of the base film is preferably 150 μm or less, more preferably 100 μm or less, and particularly preferably 80 μm or less from the viewpoint of processability.

[Application example of transfer film]
The transfer film of the present invention is, for example, as a transfer film for transferring a transfer layer including a hard coat layer and a decorative layer for surface protection or decoration of a resin molded product such as a home electric appliance or an automobile interior part. Alternatively, it can be applied as a transfer film for producing an electromagnetic wave shield fill. In particular, it is suitable as a transfer film for producing an electromagnetic wave shield fill.

As a structure of the transfer film for transferring the transfer layer including the hard coat layer and the decorative layer, for example, the base film / the first transfer layer / the second transfer layer (hard coat layer or the decorative layer / adhesive) Layer).

The structure of the transfer film (transfer film for electromagnetic wave shielding film) for producing the electromagnetic wave shielding film is, for example, a base film / first transfer layer / second transfer layer (insulating layer / metal layer / conductive adhesive layer). ), Or a base film / first transfer layer / second transfer layer (insulating layer / conductive adhesive layer).

Further, the first transfer layer in the transfer film of the present invention has an advantage that it has good adhesion to an adhesive layer (adhesive sheet). For example, after transferring the first transfer layer and the second transfer layer of the above-mentioned transfer film for electromagnetic wave shielding film to a circuit board and laminating the electromagnetic wave shielding film on the circuit board, the electromagnetic wave shielding film and the reinforcing plate are further bonded to each other. May be pasted together. In the present invention, since the first transfer layer has good adhesion to the adhesive layer (adhesive sheet), it is also useful in the post-process of manufacturing the circuit board.

[Preferable Aspects of the Present Invention]
Preferred embodiments of the present invention are shown below.
[1] A transfer film having a transfer layer on a base film, wherein the transfer layer includes at least a first transfer layer, and the first transfer layer is a layer closest to the base film among the transfer layers. A transfer film, wherein the first transfer layer contains an acrylic polymer and a melamine compound.
[2] The transfer film according to [1], wherein the first transfer layer contains 10 to 100 parts by mass of the melamine compound with respect to 100 parts by mass of the acrylic polymer.
[3] The transfer film according to [1] or [2], wherein the acrylic polymer has a weight average molecular weight of 7,000 to 150,000.
[4] The transfer film according to any one of [1] to [3], wherein the melamine compound is alkyl etherified melamine.
[5] The transfer film according to any one of [1] to [4], wherein the first transfer layer contains 1 to 50 parts by mass of an alkyd resin with respect to 100 parts by mass of the acrylic polymer.
[6] The transfer film according to any one of [1] to [5], wherein the arithmetic average roughness Ra of the surface of the base film on the transfer layer side is 0.20 m or more.
[7] The transfer film according to any one of [1] to [6], wherein the first transfer layer is directly laminated on the base film.
[8] The transfer film according to any one of [1] to [7], wherein the base film is a polyester film.
[9] The transfer film according to any one of [1] to [8], wherein the base film contains a white pigment.
[10] The transfer film according to any one of [1] to [9], wherein the first transfer layer is a matte layer.
[11] The transfer film according to any one of [1] to [10], wherein the transfer layer includes a first transfer layer and at least one second transfer layer.
[12] The transfer film according to [11], wherein the second transfer layer includes at least one layer selected from the group consisting of an insulating layer, a metal layer and a conductive adhesive layer.
[13] The transfer film according to [11] or [12], wherein the second transfer layer contains an insulating layer and a conductive adhesive layer in this order from the first transfer layer side.
[14] A transfer film for an electromagnetic wave shielding film comprising the transfer film according to [12] or [13].

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

[Measurement method and evaluation method]
(1) Measurement of Arithmetic Mean Roughness Ra of Base Film The measurement was performed using a surface roughness measuring machine (“Surftest SJ-400” manufactured by Mitutoyo Co., Ltd.) in accordance with JIS B0601 (2001).
<Measurement conditions>
・ Radius of stylus tip; 2 μm
-Measuring power: 0.75 mN
・ Cut-off value; λc = 0.8mm
-Measurement speed: 0.5 mm / sec-Measurement length: 4 mm.

(2) Adhesion between the base film of the transfer film and the transfer layer Rubber-based adhesive tape (Nichiban Co., Ltd. "Cellotape (registered trademark)" No. 405 (for industrial use) on the surface on which the transfer layer of the transfer film is laminated ) Was strongly attached with finger pressure, and then the adhesive tape side was rapidly peeled off at 175 ° to visually confirm the detached state of the transfer layer. The adhesive area between the transfer layer and the adhesive tape is 25 mm in width × 200 mm in length.
A; not peeled off at all B; partially peeled off C; the entire surface is peeled off.

(3) Peelability of the base film after transfer The peelability of the base film after the transfer layer of the transfer film was attached to an adherend (polyimide film) by a heat press was evaluated.

<Heating press>
A polyimide film ("Kapton (registered trademark)"100H; thickness 25 μm of Toray DuPont Co., Ltd.) was laminated on the transfer layer of the transfer film to prepare a laminate. This laminate was inserted into a heating press device (2ton vacuum heater press model number MKP-150TV-WH manufactured by Mikado Technos Co., Ltd.) and pressed at a press temperature of 180 ° C. and a press pressure of 2 MPa for 30 minutes. Then, the laminate was taken out and left at room temperature for 1 hour.

<Measurement of peeling force>
With respect to the laminate prepared above, the peeling force between the base film of the transfer film and the first transfer layer was measured by the following method and evaluated according to the following criteria.

The laminate was cut into a width of 50 mm and a length of 70 mm to prepare a sample for measurement. For this measurement sample, the peeling force when the base film side was peeled to 180 ° at a speed of 300 mm / min was measured with a tensile tester.
A (best); peeling force is less than 5N / 50mm.
B (good); peeling force is 5N / 50mm or more and less than 10N / 50mm.
C (possible); peeling force is 10 N / 50 mm or more and less than 15 N / 50 mm.
D (impossible); peeling force of 15 N / 50 mm or more E (not measurable); when the base film is broken.

(4) Evaluation of Matte Appearance of First Transfer Layer The 60-degree glossiness of the exposed surface of the first transfer layer exposed by peeling off the base film in (3) above was measured by the following method.

<Measurement of 60 degree glossiness>
The measurement was performed using a digital variable angle gloss meter UGV-5D manufactured by Suga Test Instruments Co., Ltd. according to the method specified in JIS-Z-8741 (1997). The measurement was performed 5 times, and the average value excluding the maximum value and the minimum value was adopted and evaluated according to the following criteria.
A; 60 degree glossiness is less than 20 B; 60 degree glossiness is 20 or more and less than 30 C; 60 degree glossiness is 30 or more.

(5) Adhesion between the first transfer layer and the adhesive sheet In the same manner as in (3) above, the transfer film and the adherend are bonded together by a hot press, and then the base film is peeled off to adhere the transfer layer. Transferred to the body. Polyimide film Toray DuPont Co., Ltd. is placed on the surface of the first transfer layer exposed by peeling the base film in this way via an adhesive sheet (“Nikaflex (registered trademark)” SAF of Nikkan Kogyo Co., Ltd.). ) "Kapton (registered trademark)"100H; thickness 25 μm), and then inserted into a heating press device (2ton vacuum heater press model number MKP-150TV-WH manufactured by Mikado Technos Co., Ltd.), and the press temperature is 160 ° C. , Pressed at a press pressure of 2 MPa for 30 minutes. Then, the test sample was taken out and left at room temperature for 1 hour, and then the peeling force between the first transfer layer and the adhesive sheet was measured by the following method.

<Measurement of peeling force>
The test sample was cut out to a width of 10 mm and a length of 70 mm. The peeling force of this test sample when peeled at 90 ° at a speed of 50 mm / min was measured with a tensile tester, and the adhesion was evaluated according to the following criteria.

<Evaluation of adhesion>
S; Peeling force is 13N / 10mm or more.
A; Peeling force is less than 13N / 10mm and 10N / 10mm or more.
B; Peeling force is less than 10N / 10mm and 5N / 10mm or more.
C; Peeling force is less than 5N / 10mm.

(6) Measurement of Weight Average Molecular Weight of Acrylic Polymer The solution was measured as a solution in tetrahydrofuran by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

[Acrylic polymer used for the first transfer layer]
-Acrylic polymer a1; "Acryt (registered trademark)" 0502TC (weight average molecular weight; 14,000) manufactured by Taisei Fine Chemicals Co., Ltd.
-Acrylic polymer a2; "Acryt (registered trademark)" 0404EA-P (weight average molecular weight; 42,000) manufactured by Taisei Fine Chemicals Co., Ltd.
-Acrylic polymer a3; "Acryt (registered trademark)" 0404TB (weight average molecular weight; 11,000,000) manufactured by Taisei Fine Chemicals Co., Ltd.

[Melamine compound used for the first transfer layer]
-Melamine b1; partially alkyl etherified melamine ("Uban (registered trademark)" 28-60 manufactured by Mitsui Chemicals, Inc .; alkyl = butyl)
-Melamine b2; partially alkyl etherified melamine (“Super Beccamin®” L-105-60; alkyl = methyl, manufactured by DIC Corporation).

[Acid catalyst used for the first transfer layer]
-P-Toluenesulfonic acid (“Tayca Cure®” AC-707 manufactured by TAYCA CORPORATION).

[Alkyd resin used for the first transfer layer]
-Alkyd resin; "Alkydia (registered trademark)" OD-E-230-70-E manufactured by DIC Corporation.

[Base film]
-Film 1; White polyester film with a thickness of 50 μm ("Lumirror (registered trademark)" E20 manufactured by Toray Co., Ltd.) sandblasted (Type D manufactured by Kaisei Kogyo Co., Ltd.) -Film 2; Thickness 50 μm white polyester film (“Lumilar®” E20 manufactured by Toray Co., Ltd.) sandblasted (Type S manufactured by Kaisei Kogyo Co., Ltd.) ・ Film 3; Polyester film with a thickness of 50 μm (Toray Co., Ltd.) "Lumirror (registered trademark)" X42 manufactured by Co., Ltd .; Particle-kneaded PET film)
-Film 4 (silicone release film); the following silicone release agent layer (dry thickness 100 nm) is applied to the sandblasted surface of film 1.

<Silicone release agent>
40 parts by mass of KS847H (manufactured by Shin-Etsu Chemical Co., Ltd.), which is an addition reaction type curable silicone resin, and 0.4 parts by mass of PL-50T (manufactured by Shin-Etsu Chemical Co., Ltd.), which is a curing agent, is 500 parts by mass of toluene. , N-Heptane mixed in 500 parts by mass-Film 5 (silicone release film); polyester film with a thickness of 50 μm (“Lumilar®” S10 manufactured by Toray Co., Ltd.) similar to film 4. A silicone release agent layer is provided.

[Example 1]
A transfer film was prepared by sequentially laminating a first transfer layer and a second transfer layer on film 1 in the following manner.

<Lamination of the first transfer layer>
The following coating liquid p1 (thermosetting composition) for the first transfer layer is applied to the sandblasted surface of the film 1 with a gravure coater, and dried and heated at 160 ° C. for 30 seconds to laminate the first transfer layer. did. The thickness of this first transfer layer was 1.3 μm.

<Coating liquid p1>
-Acrylic polymer a1; 100 parts by mass in terms of solid content-Melamine b1; 25 parts by mass in terms of solid content-Acid catalyst; 1.9 parts by mass in terms of solid content-Mixed solvent (toluene: methyl ethyl ketone: isopropyl alcohol: cyclohexanone = 40) It was prepared so that the solid content concentration was 15% by mass at a ratio of 40:10:10 (mass ratio).

<Lamination of the second transfer layer>
The following insulating layer and conductive adhesive layer were laminated in this order as the second transfer layer.

<Lamination of insulation layer>
The following coating material for an insulating layer was applied to the surface of the first transfer layer so as to have a dry thickness of 10 μm, and dried at 120 ° C. to form an insulating layer.

<Paint for insulating layer>
Bisphenol A type epoxy resin (Mitsubishi Chemical Corporation, "jER (registered trademark)" 828) 100 parts by mass, curing agent (Mitsubishi Chemical Corporation, "jER Cure (registered trademark)" ST12) 40 parts by mass, and carbon black (MA100, manufactured by Mitsubishi Chemical Corporation) 5 parts by mass was prepared with methyl ethyl ketone so that the solid content concentration was 40% by mass.

<Lamination of conductive adhesive layer>
The following paint for a conductive adhesive layer was applied to the surface of the insulating layer so that the dry thickness was 7 μm, and dried at 100 ° C. to form a conductive adhesive layer.

<Paint for conductive adhesive layer>
100 parts by mass of epoxy thermosetting adhesive (EXA-4816 manufactured by DIC), 20 parts by mass of curing agent (PN-23 manufactured by Ajinomoto Fine Techno), and conductive particles (average particle diameter 7.5 μm) 40 parts by mass of copper particles) was dissolved or dispersed in 200 parts by mass of methyl ethyl ketone.

[Example 2]
A transfer film was produced in the same manner as in Example 1 except that the coating liquid was changed to p2 below.

<Coating liquid p2>
-Acrylic polymer a2; 100 parts by mass in terms of solid content-Melamine b1; 25 parts by mass in terms of solid content-Acid catalyst; 1.9 parts by mass in terms of solid content-Mixed solvent (toluene: methyl ethyl ketone: isopropyl alcohol: cyclohexanone = 40) It was prepared so that the solid content concentration was 15% by mass at a ratio of 40:10:10 (mass ratio).

[Example 3]
A transfer film was produced in the same manner as in Example 1 except that the coating liquid was changed to p3 below.

<Coating liquid p3>
-Acrylic polymer a3; 100 parts by mass in terms of solid content-Melamine b1; 25 parts by mass in terms of solid content-Acid catalyst; 1.9 parts by mass in terms of solid content-Mixed solvent (toluene: methyl ethyl ketone: isopropyl alcohol: cyclohexanone = 40) It was prepared so that the solid content concentration was 15% by mass at a ratio of 40:10:10 (mass ratio).

[Example 4]
A transfer film was produced in the same manner as in Example 1 except that the coating liquid was changed to p4 below.

<Coating liquid p4>
-Acrylic polymer a1; 25 parts by mass in terms of solid content-Acrylic polymer a2; 75 parts by mass in terms of solid content-Melamine b1; 25 parts by mass in terms of solid content-Acid catalyst; 1.9 parts by mass in terms of solid content-Mixed It was prepared so that the solid content concentration was 15% by mass in a solvent (toluene: methylethylketone: isopropyl alcohol: cyclohexanone = 40: 40: 10: 10 (mass ratio).

[Example 5]
A transfer film was produced in the same manner as in Example 1 except that the coating liquid was changed to p5 below.

<Coating liquid p5>
-Acrylic polymer a1; 50 parts by mass in terms of solid content-Acrylic polymer a2; 50 parts by mass in terms of solid content-Melamine b1; 25 parts by mass in terms of solid content-Acid catalyst; 1.9 parts by mass in terms of solid content-Mixed It was prepared so that the solid content concentration was 15% by mass in a solvent (toluene: methylethylketone: isopropyl alcohol: cyclohexanone = 40: 40: 10: 10 (mass ratio).

[Example 6]
A transfer film was produced in the same manner as in Example 1 except that the coating liquid was changed to p6 below.

<Coating liquid p6>
-Acrylic polymer a1; 75 parts by mass in terms of solid content-Acrylic polymer a2; 25 parts by mass in terms of solid content-Melamine b1; 25 parts by mass in terms of solid content-Acid catalyst; 1.9 parts by mass in terms of solid content-Mixed It was prepared so that the solid content concentration was 15% by mass in a solvent (toluene: methylethylketone: isopropyl alcohol: cyclohexanone = 40: 40: 10: 10 (mass ratio).

[Example 7]
A transfer film was produced in the same manner as in Example 1 except that the coating liquid was changed to p7 below.

<Coating liquid p7>
-Acrylic polymer a2; 100 parts by mass in terms of solid content-Melamine b2; 25 parts by mass in terms of solid content-Acid catalyst; 1.9 parts by mass in terms of solid content-Mixed solvent (toluene: methyl ethyl ketone: isopropyl alcohol: cyclohexanone = 40) It was prepared so that the solid content concentration was 15% by mass at a ratio of 40:10:10 (mass ratio).

[Example 8]
A transfer film was produced in the same manner as in Example 1 except that the coating liquid was changed to p8 below.

<Coating liquid p8>
-Acrylic polymer a2; 100 parts by mass in terms of solid content-Melamine b1; 10 parts by mass in terms of solid content-Acid catalyst; 0.8 parts by mass in terms of solid content-Mixed solvent (toluene: methyl ethyl ketone: isopropyl alcohol: cyclohexanone = 40) It was prepared so that the solid content concentration was 15% by mass at a ratio of 40:10:10 (mass ratio).

[Example 9]
A transfer film was produced in the same manner as in Example 1 except that the coating liquid was changed to p9 below.

<Coating liquid p9>
-Acrylic polymer a2; 100 parts by mass in terms of solid content-Melamine b1; 50 parts by mass in terms of solid content-Acid catalyst; 3.8 parts by mass in terms of solid content-Mixed solvent (toluene: methyl ethyl ketone: isopropyl alcohol: cyclohexanone = 40) It was prepared so that the solid content concentration was 15% by mass at a ratio of 40:10:10 (mass ratio).

[Example 10]
A transfer film was produced in the same manner as in Example 1 except that the coating liquid was changed to p10 below.

<Coating liquid p10>
-Acrylic polymer a2; 100 parts by mass in terms of solid content-Melamine b1; 70 parts by mass in terms of solid content-Acid catalyst; 5.3 parts by mass in terms of solid content-Mixed solvent (toluene: methyl ethyl ketone: isopropyl alcohol: cyclohexanone = 40) It was prepared so that the solid content concentration was 15% by mass at a ratio of 40:10:10 (mass ratio).
[Example 11]
A transfer film was produced in the same manner as in Example 1 except that the coating liquid was changed to p11 below.

<Coating liquid p11>
-Acrylic polymer a2; 100 parts by mass in terms of solid content-Melamine b1; 100 parts by mass in terms of solid content-Acid catalyst; 7.6 parts by mass in terms of solid content-Mixed solvent (toluene: methyl ethyl ketone: isopropyl alcohol: cyclohexanone = 40) It was prepared so that the solid content concentration was 15% by mass at a ratio of 40:10:10 (mass ratio).
[Example 12]
A transfer film was produced in the same manner as in Example 1 except that the coating liquid was changed to p12 below.

<Coating liquid p12>
-Acrylic polymer a1; 100 parts by mass in terms of solid content-Melamine b1; 25 parts by mass in terms of solid content-Alkyd resin; 15 parts by mass in terms of solid content-Acid catalyst; 1.9 parts by mass in terms of solid content-Mixed solvent (Toluene: Methylethylketone: Isopropyl alcohol: Cyclohexanone = 40:40:10: 10 (mass ratio), so that the solid content concentration was 15% by mass.

[Example 13]
A transfer film was produced in the same manner as in Example 1 except that the film was changed to film 2.

[Example 14]
A transfer film was produced in the same manner as in Example 1 except that the film was changed to film 3.

[Comparative Example 1]
A transfer film was produced in the same manner as in Example 1 except that the coating liquid was changed to p13 below.

<Coating liquid p13>
-Acrylic polymer a1; 100 parts by mass in terms of solid content-Prepared so that the solid content concentration was 15% by mass in a mixed solvent (toluene: methyl ethyl ketone: isopropyl alcohol: cyclohexanone = 40:40:10:10 (mass ratio)). ..

[Comparative Example 2]
A transfer film was produced in the same manner as in Example 1 except that the coating liquid was changed to p14 below.

<Coating liquid p14>
-Melamine b1; 100 parts by mass in terms of solid content-Acid catalyst; 7.5 parts by mass in terms of solid content-Solid in a mixed solvent (toluene: methyl ethyl ketone: isopropyl alcohol: cyclohexanone = 40:40:10:10 (mass ratio)) It was prepared so that the component concentration was 15% by mass.

[Comparative Example 3]
A second transfer layer (insulating layer / conductive adhesive layer) is laminated and transferred in the same manner as in Example 1 without providing the first transfer layer on the release agent layer surface of the film 4 (silicone release film). A film was made.

[Comparative Example 4]
A transfer film was prepared by laminating a second transfer layer (insulating layer / conductive adhesive layer) on the sandblasted surface of the film 1 in the same manner as in Example 1 without providing the first transfer layer.

[Comparative Example 5]
The second transfer layer (insulating layer / conductive adhesive layer) is laminated and transferred in the same manner as in Example 1 without providing the first transfer layer on the release agent layer surface of the film 5 (silicone release film). A film was made.

[Evaluation]
Table 1 shows the results of measurement and evaluation of the transfer films of Examples and Comparative Examples obtained above according to the above-mentioned measurement methods and evaluation methods.

Claims (1)

A transfer film having a transfer layer on a base film, wherein the transfer layer includes at least a first transfer layer, and the first transfer layer is a layer closest to the base film among the transfer layers, and the first transfer layer is described. A transfer film in which the transfer layer contains an acrylic polymer and a melamine compound.