TW201803434A - Electromagnetic-wave shield film - Google Patents

Abstract

This electromagnetic-wave shield film is provided with an insulation protection layer 110 and a shield layer 120. A surface of the insulation protection layer 110 has an arithmetic average inclination of 30 DEG or greater.

Description

Electromagnetic wave shielding film

The invention relates to an electromagnetic wave shielding film.

In recent years, there is an increasing demand for high-speed transmission of large-capacity data such as smart phones and tablet information terminals. To transmit large-capacity data at high speed requires the use of high-frequency signals. However, if a high-frequency signal is used, the signal circuit provided on the printed wiring board will emit electromagnetic noise, which may easily cause the peripheral equipment to malfunction. In order to prevent the above-mentioned malfunction, it is important to shield the electromagnetic wave and prevent the printed wiring board from interference.

In order to shield the printed wiring board from interference by shielding electromagnetic waves, a method has been proposed in which an electromagnetic wave shielding film including an insulating layer and a shielding layer is attached to the printed wiring board (for example, refer to Patent Document 1).

In addition, in order to hide the circuit pattern, an electromagnetic wave shielding film has been proposed in which an insulating protective layer is dyed to a black color (for example, refer to Patent Document 2).

In addition, in order to improve the visual clarity of the white characters printed on the surface of the electromagnetic wave shielding film, it has been proposed to adjust the hue of the insulating protective layer of the electromagnetic wave shielding film (for example, refer to Patent Document 3).

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2004-095566

[Patent Document 2] Japanese Patent Application Laid-Open No. 2014-078574

[Patent Document 3] Japanese Patent No. 5796690

In the process of assembling an electronic device, in order to manage a printed wiring board, a symbol or the like is printed on the surface of an electromagnetic wave shielding film attached to the printed wiring board with white ink. However, the conventional electromagnetic wave shielding film has the following disadvantages: it is easy to bleed when printing with white ink, resulting in lower productivity of the process of printing with white ink.

In addition, information terminals, etc. equipped with an electromagnetic wave shielding film are required to be lightweight and miniaturized. Therefore, along with this demand, the size of the electromagnetic wave shielding film has become smaller and smaller, and the characters printed on the electromagnetic wave shielding film have become more and more popular. small.

The printed text becomes smaller, making the previously printed text on the electromagnetic wave shielding film difficult to read. This effect becomes greater especially in higher light rooms.

In addition, if screen printing is used to print characters and symbols on the previous electromagnetic wave shielding film, the following problems will occur: the ink will bleed between the screen printing plate and the electromagnetic wave shielding film, resulting in reduced printing accuracy and smaller characters Hard to recognize. Even if the hue of the insulating protective layer is adjusted and the contrast is improved, it is difficult to fundamentally improve the problem of reduced visual clarity caused by bleeding.

The object of the present invention is to realize an electromagnetic wave shielding film, which can not only make small characters and the like easy to recognize, but also can print on the surface with high accuracy.

An aspect of the electromagnetic wave shielding film includes an insulating protective layer and a shielding layer, and the arithmetic mean slope of the surface of the insulating protective layer is above 30 °.

According to the electromagnetic wave shielding film of the present invention, small characters and the like can be easily recognized, and high-precision printing can be performed.

110‧‧‧Insulation protective layer

120‧‧‧shield

130‧‧‧Adhesive layer

140‧‧‧Isotropic conductive adhesive layer

FIG. 1 is a cross-sectional view showing an electromagnetic wave shielding film according to an embodiment.

2 is a cross-sectional view showing an electromagnetic wave shielding film according to a modification.

The electromagnetic wave shielding film of the present invention will be specifically described below. However, the present invention is not limited to the following embodiments, and appropriate changes can be made and applied without changing the gist of the present invention.

(Electromagnetic wave shielding film)

FIG. 1 is a schematic cross-sectional view schematically showing an electromagnetic wave shielding film according to this embodiment. As shown in FIG. 1, the electromagnetic wave shielding film includes an insulating protection layer 110 and a shielding layer 120. An adhesive layer 130 may be provided on the surface of the shielding layer 120 on the side opposite to the insulating protection layer 110 as needed. By providing an adhesive layer, an electromagnetic wave shielding film can be easily bonded to a printed wiring board.

(Insulation protective layer)

The insulating protection layer 110 is provided to protect the shielding layer. In the electromagnetic shielding film of this embodiment, the arithmetic mean inclination of the insulating protective layer 110 is 30 ° or more.

By setting the arithmetic mean inclination of the insulating protective layer 110 to 30 ° or more (preferably 35 ° or more, more preferably 40 ° or more), the surface area of the insulating protective layer 110 will increase, and the ink absorbency will be reduced. It is improved, and it is possible to suppress ink bleeding during screen printing. In this way, the efficiency of the printing operation can be improved.

From the viewpoint of reducing bleeding, the value of the arithmetic mean tilt is preferably large. From the viewpoint of the productivity of the insulating protective layer 110, the arithmetic mean tilt is preferably 80 ° or less, and more preferably 70 ° or less.

In addition, the arithmetic mean inclination of this invention can be measured based on JIS B 0601 (2001).

The Root mean square slope of the insulation protection layer can be above 35 °, more preferably above 40 °, and even more preferably above 45 °. Because root mean square tilt The inclination is 35 ° or more, so the surface area of the insulating protective layer 110 is large, and the absorbency of the ink is improved, so that the bleeding of the ink during screen printing can be suppressed. In this way, the efficiency of the printing operation can be improved.

In addition, the root mean square inclination in the present invention can be measured in accordance with JIS B 0601 (2001).

A method of forming an insulating protective layer having an arithmetic mean inclination and a root mean square inclination in a predetermined range is not particularly limited, and a known method can be used. Such well-known methods include, for example, imparting an uneven shape to a release film by embossing, coating the surface of the release film with a resin composition forming an insulating protective layer, and drying, thereby transferring the uneven shape of the release film to the insulating protective layer. Method; coating a resin composition containing fine particles on the surface of the shielding layer and drying to form an insulating protective layer having a concave-convex shape; a method of spraying dry ice on the surface of the insulating protective layer; etc .; applying active energy ray curing on the surface of the shielding layer A method of pressing a mold having a concave-convex shape onto the surface of the shielding layer after curing the composition, and curing the cured composition layer, and a method of peeling the mold.

Among the above methods, from the viewpoint of productivity, a preferable method is a method of applying a resin composition containing fine particles and drying to form an insulating protective layer having an uneven shape. At this time, the fine particles added to the insulating protective layer 110 are not particularly limited, and for example, resin fine particles or inorganic fine particles can be used. As the resin fine particles, acrylic resin fine particles, polyacrylonitrile fine particles, polyurethane fine particles, polyimide fine particles, polyimide fine particles, and the like can be used. As the inorganic particles, calcium carbonate particles, calcium silicate particles, clay, kaolin, talc, silica particles, glass particles, diatomaceous earth, mica powder, alumina particles, magnesium oxide particles, zinc oxide particles, barium sulfate particles, Aluminum sulfate particles, calcium sulfate particles, and magnesium carbonate particles. The resin fine particles and the inorganic fine particles may be used alone or in combination. From the viewpoint of improving the abrasion resistance of the insulating protective layer, inorganic fine particles are preferred.

From the viewpoint of generating moderate unevenness on the surface of the insulating protective layer and making the arithmetic mean tilt and the root mean square tilt larger, the 50% average particle diameter of the particles is preferably 2 μm or more, more preferably 4 μm or more, and 10 μm or more It's better. In order to suppress whitening of the insulating protective layer, a 50% average particle diameter is preferably 30 μm or less, and more preferably 20 μm or less.

From the viewpoint of making the arithmetic mean inclination and the root-mean-square inclination larger, the amount of particles added to the insulating protective layer 110 is preferably 3% by mass or more, and more preferably 5% or more. From the viewpoint of suppressing whitening of the insulating protective layer, the amount of particles added to the insulating protective layer 110 is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 17% by mass or less.

A black-based colorant can be added to the insulating protective layer 110. By adding a black-based colorant, the L * value of the insulating protective layer 110 can be reduced, and the visual clarity of characters can be further improved. When the text printed on the insulating protection layer 110 is white, it is better to let the L * value be 20 or less, and more preferably 18 or less. It should be noted that the L * value in the present invention can be measured in accordance with JIS Z 8781-4 (2013).

The black-based colorant may be a ocher pigment or a mixed pigment obtained by subtracting and mixing a plurality of pigments to become black. The ocher pigment can be any one or a combination of the following: carbon black, Ketjen Black, carbon nanotube (CNT), perylene black, titanium black, iron black, aniline black, etc. . The mixed pigment may be, for example, pigments such as red, green, blue, yellow, purple, Cyan, and magenta.

The particle size of the black-based colorant is only required to achieve a desired L * value, but from the viewpoints of dispersibility and reduction of the L * value, the average primary particle size is preferably 20 nm or more and 100 nm or less. The average primary particle diameter of the black-based colorant can be determined from the average particle diameter of about 20 primary particles that can be observed on an image magnified by a transmission electron microscope (TEM) at about 50,000 to 1 million times.

From the viewpoint of making the L * value small, the amount of the black-based colorant added to the insulating protective layer 110 is preferably 0.5% by mass or more, and more preferably 1% by mass or more. However, the black-based colorant may be added as needed, or may not be added.

Let the 60 ° glossiness of the insulating protection layer 110 be less than 3% (preferably less than 2%, and more preferably less than 1%), so that a moderate light scattering will occur on the surface of the insulating protection layer 110, and the gloss feeling will be Will get moderate suppression. In this way, the visual clarity of printed text can be improved. The 85 ° gloss of the insulating protective layer 110 is preferably below 10%, more preferably below 3%, and even more preferably below 1%.

It should be noted that the 60 ° gloss and 85 ° gloss in the present invention can be measured according to the method shown in the examples.

The insulating protective layer 110 preferably has desired insulation properties, and meets prescribed mechanical strength, chemical resistance, and heat resistance.

The resin material constituting the insulating protective layer is not particularly limited as long as it has sufficient insulation properties. For example, a thermoplastic resin composition, a thermosetting resin composition, an active energy ray-curable composition, and the like can be used.

The thermoplastic resin composition is not particularly limited, and a styrene-based resin composition, a vinyl acetate-based resin composition, a polyester-based resin composition, a polyethylene-based resin composition, a polypropylene-based resin composition, and an imine-based resin can be used. A resin composition, an acrylic resin composition, and the like. The thermosetting resin composition is not particularly limited, and a phenol-based resin composition, an epoxy-based resin composition, a urethane-based resin composition, a melamine-based resin composition, an alkyd-based resin composition, and the like can be used. The active energy ray-curable composition is not particularly limited, and for example, a polymerizable compound containing at least two (meth) acryloyloxy groups in a molecule can be used. The said composition may be used individually by 1 type, and may use 2 or more types together.

The insulating protective layer 110 may include the above-mentioned fine particles and a colorant, as well as Contains curing accelerators, tackifiers, antioxidants, pigments, dyes, plasticizers, UV absorbers, defoamers, levelers, fillers, flame retardants, viscosity modifiers, and anti-adhesives (anti- blocking) agent.

The thickness of the insulating protective layer 110 is not particularly limited, and may be appropriately set according to need. However, from the viewpoint of sufficiently protecting the shielding layer, the thickness of the insulating protective layer 110 is preferably 1 μm or more, and more preferably 4 μm or more. From the viewpoint of ensuring the flexibility of the electromagnetic wave shielding film, the thickness of the insulating protective layer 110 is preferably 10 μm or less, and more preferably 5 μm or less.

(Shield)

The shielding layer 120 in this embodiment may be a metal layer. The shielding layer 120 may use a metal layer formed of any one of the following metals or an alloy including two or more of the following: nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, and zinc. The material and thickness of the metal layer need only be appropriately selected according to the required electromagnetic shielding effect and resistance to repeated bending and sliding wear. From the viewpoint of obtaining a sufficient electromagnetic shielding effect, the thickness of the metal layer is preferably 0.1 μm or more. From the viewpoints of productivity and bendability, the thickness of the metal layer is preferably 8 μm or less. It should be noted that the metal layer can be formed by a plating method, an electroless plating method, a sputtering method, an electron beam evaporation method, a vacuum evaporation method, a CVD method, an organic metal chemical vapor deposition method, and the like. The metal layer may be formed of a metal foil, metal nano particles, scaly metal particles, or the like.

(Adhesive layer)

The electromagnetic wave shielding film of the present embodiment may include an adhesive layer 130 on the opposite side of the shielding layer 120 from the insulating protection layer 110. The adhesive layer 130 can be formed of a resin composition having adhesiveness. The adhesive resin composition is not particularly limited, and it can be used: a styrene-based resin composition, a vinyl acetate-based resin composition, a polyester-based resin composition, a polyethylene-based resin composition, a polypropylene-based resin composition, and adiabatic resin. Amine resin composition, amidine resin composition, acrylic resin Thermoplastic resin composition such as composition; thermosetting resin composition such as phenol resin composition, epoxy resin composition, urethane resin composition, melamine resin composition, alkyd resin composition, etc. . The said composition may be used individually by 1 type, and may use 2 or more types together.

The adhesive layer 130 can be formed as a layer having isotropic conductivity or anisotropic conductivity as needed. To form the adhesive layer 130 as a conductive layer, it is only necessary to add conductive fine particles to the adhesive resin composition.

The conductive fine particles are not particularly limited, and metal fine particles, carbon nanotubes, carbon fibers, metal particles, and the like can be used. For example, metal particles such as silver powder, copper powder, nickel powder, solder powder, and aluminum powder can be used. It is also possible to use silver-coated copper powder formed by plating copper powder with silver, metal-coated polymer particles or metal-coated particles formed of glass beads or the like. Among them, copper powder or silver-coated copper powder which can be obtained at low cost is preferred from the viewpoint of flexibility.

The 50% average particle diameter of the conductive particles is not particularly limited, but from the viewpoint of achieving good conductivity, the 50% average particle diameter of the conductive particles is preferably 0.5 μm or more. From the viewpoint of making the conductive adhesive layer thin, the 50% average particle diameter of the conductive particles is preferably 15 μm or less.

The shape of the conductive particles is not particularly limited, and can be appropriately selected from shapes such as a spherical shape, a flat shape, a scaly shape, and a dendritic shape.

The thickness of the adhesive layer 130 can be adjusted according to need. From the viewpoint of achieving good adhesion, it is preferable to make the thickness of the adhesive layer 130 be 0.5 μm or more. From the viewpoint of making the electromagnetic wave shielding film thin, it is preferable to make the thickness of the adhesive layer 130 be 20 μm or less.

The configuration in which the electromagnetic wave shielding film has the insulating protective layer 110, the shielding layer 120, and the adhesive layer 130 has been described above, but as shown in FIG. The configuration of the insulating protective layer 110 and the isotropic conductive adhesive layer 140.

The insulating protective layer 110 may have the same configuration as the electromagnetic wave shielding film shown in FIG. 1. The isotropic conductive adhesive layer 140 may be formed of the same resin composition and conductive fine particles as the adhesive layer 130. The isotropic conductive adhesive layer 140 functions as a shielding layer.

(Manufacturing method of shielding film)

The electromagnetic wave shielding film can be produced by a known production method. One example is shown below.

First, a conductive adhesive layer 130 is formed on a base film whose surface is subjected to a release treatment. Specifically, the solution of the adhesive layer composition containing the material constituting the adhesive layer 130 is applied to the surface of the base film and dried to form the adhesive layer 130.

Next, a shielding layer 120 is formed on the surface of the adhesive layer 130. Specifically, the following method can be adopted: a method of bonding a metal foil having a predetermined thickness to the adhesive layer 130; and a method of forming a metal layer on the surface of the adhesive layer 130 by vapor deposition or wet plating method.

Next, an insulating protection layer 110 is formed on the surface of the shielding layer 120. Specifically, a method may be adopted in which a solution of an insulating protective layer composition containing a material constituting the insulating protective layer 110 is applied to the surface of the shielding layer 120 and dried.

Then, by peeling the base film, an electromagnetic wave shielding film can be obtained.

It should be noted that the adhesive layer 130 may also be used as the isotropic conductive adhesive layer 140, and an insulating protection layer 110 may be formed on the surface of the isotropic conductive adhesive layer 140.

In order to adjust the arithmetic mean inclination and the root mean square inclination of the surface of the insulating protective layer 110, the surface of the insulating protective layer 110 may also be processed by sandblasting or the like.

The example in which the electromagnetic wave shielding film is formed from the side of the adhesive layer 130 has been described above, and the electromagnetic wave shielding film may be sequentially formed from the side of the insulating protective layer 110. At this time, the base film with a fine pattern is used to transfer the fine pattern to the surface of the adhesive layer 130, so that the arithmetic mean tilt and the root mean square tilt of the surface of the adhesive layer 130 can also be performed. Adjustment.

[Example]

Hereinafter, the present invention is described in detail through examples. It should be noted that the following embodiments are merely examples and do not limit the present invention in any way.

<Characteristic evaluation>

[Bleeding Evaluation]

On the surface of the insulating protective layer of the electromagnetic wave shielding film, English letters and numbers of 1 mm × 2 mm were printed with a screen printing plate, and the shapes of the English letters and numbers were observed with a microscope to evaluate the presence or absence of bleeding. If bleed cannot be confirmed, it is recorded as ○, if bleed is confirmed, and contour deformation and ink coloring unevenness (cissing) are caused, it is recorded as ×.

[Evaluation of visual clarity]

The visual clarity was evaluated by observing the 45 ° regular reflection. In a dark room, set an LED lamp (made by SUPRABEAM) at a height of 10 cm on the table, so that the irradiation port of the LED lamp is approximately 45 ° from the vertical direction, and place the above electromagnetic wave shielding film 10 cm away from the irradiation port in a horizontal direction. Location. Then, from the position where the electromagnetic wave shielding film was placed 10 cm away from the horizontal direction and 10 cm away from the vertical direction, three English letters and numbers (0.5 mm in length, 0.2 mm in width, Observation was performed at intervals of 0.1 mm) to evaluate the ease of identification. When all the outlines of the printed characters can be clearly observed, they are marked as ○, and when the printed characters cannot be clearly observed, they are marked as ×.

[Measurement of Arithmetic Mean Tilt and Root Mean Square Tilt]

A laser microscope (VK-X200, manufactured by KEYENCE CORPORATION, 50x objective lens) was used to observe any 5 fields of view on the surface of the insulating protective layer, and the average values of the arithmetic mean tilt and the root mean square tilt were performed in accordance with JIS B 0601 (2001). measuring. The reference length is 280 μm.

[Measurement of L * value]

The L * value was measured with an integrating sphere spectrophotometer (manufactured by X-Rite, Ci64, tungsten filament lamp).

〔Measurement of gloss〕

The 60 ° gloss and 85 ° gloss were measured with a BYK-Gardner gloss meter (portable gloss meter).

(Example 1)

-Preparation of conductive adhesive layer-

100 parts by mass of bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER1256), 0.1 parts by mass of curing agent (manufactured by Mitsubishi Chemical Corporation, ST14), and 47 parts by mass of spherical were added to toluene The silver-clad copper powder having an average particle diameter of 10 μm ensures a solid content of 20% by mass, and is stirred and mixed to prepare a conductive adhesive layer composition. The prepared adhesive layer composition is coated on a PET film having a release treatment on its surface, and dried by heating to form an adhesive layer on the surface of the base film.

-Preparation of shielding layer-

A silver-plated layer having a thickness of 0.1 μm was formed on the surface of the prepared adhesive layer by a vapor deposition method.

-Preparation of insulation protection layer-

100 parts by mass of bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER1256), 0.1 parts by mass of curing agent (manufactured by Mitsubishi Chemical Corporation, ST14), and 15 parts by mass of black are added to toluene. Colorants are carbon particles (Tokai Carbon Co., Ltd., TOKABLACK # 8300 / F), 10 parts by mass of fine particles, ie, urethane resin particles having an average particle diameter of 6 μm, with a solid content of 20% by mass, to prepare an insulating protective layer composition. This composition was applied to the prepared shielding layer, followed by heating and drying to prepare the electromagnetic wave shielding film of Example 1.

The arithmetic mean slope of the surface of the prepared insulating protective layer is 43 °, the root mean square slope is 50 °, the L * value is 18, the 60 ° gloss is 0.2%, and the 85 ° gloss is 0.3%. The presence or absence of bleeding was evaluated. No unevenness in coloring of the ink was observed, and no bleeding was confirmed. The visual clarity of printed text is also good.

(Example 2)

Example 2 was the same as Example 1 except that the microparticles added to the insulating protective layer composition were changed to 10 parts by mass of urethane resin particles having an average particle diameter of 2 μm. The arithmetic mean slope of the surface of the prepared insulating protection layer was 32 °, the root mean square slope was 39 °, the L * value was 20, the 60 ° gloss was 1.1%, and the 85 ° gloss was 2.3%. The presence or absence of bleeding was evaluated. No unevenness in coloring of the ink was observed, and no bleeding was confirmed. The visual clarity of printed text is also good.

(Example 3)

Example 3 was the same as Example 1 except that the microparticles added to the insulating protective layer composition were changed to 10 parts by mass of urethane resin particles having an average particle diameter of 5 μm. The arithmetic mean slope of the surface of the prepared insulating protection layer was 46 °, the root mean square slope was 52 °, the L * value was 21, the 60 ° gloss was 0.3%, and the 85 ° gloss was 2.6%. The presence or absence of bleeding was evaluated. No unevenness in coloring of the ink was observed, and no bleeding was confirmed. The visual clarity of printed text is also good.

(Example 4)

Example 4 was the same as Example 1 except that the microparticles added to the insulating protective layer composition were changed to 13 parts by mass of styrene-acrylonitrile resin particles having an average particle diameter of 5 μm. The arithmetic mean inclination of the surface of the prepared insulating protection layer is 35 °, root mean square inclination is 43 °, L * value is 18, gloss at 60 ° is 0.8%, gloss at 85 ° is 2.1%. The presence or absence of bleeding was evaluated, and the visual clarity of the printed text was good.

(Comparative example 1)

In Comparative Example 1, the black-based colorant added to the insulating protective layer composition was changed to 5 parts by mass, and fine particles were not added. The surface of the base film is subjected to a mold release treatment and has a concave-convex shape. The insulating protective layer composition is coated on the surface of the base film and dried. After the base film and the shielding layer are bonded, the base film is peeled off from the surface of the insulating protective layer, thereby forming uneven movement Printed on its own insulating protective layer. The other conditions are the same as in Example 1. The arithmetic mean slope of the surface of the prepared insulating protection layer was 22 °, the root mean square slope was 31 °, the L * value was 28, the 60 ° gloss was 2.0%, and the 85 ° gloss was 43.4%. The presence or absence of bleeding was evaluated to confirm that the ink was unevenly colored. Printed text cannot be recognized under the cover of reflected light.

(Comparative example 2)

Comparative Example 2 was the same as Example 1 except that the black-based colorant added to the insulating protective layer composition was changed to 5 parts by mass and no fine particles were added. The surface of the insulation protective layer obtained had an arithmetic average inclination of 16 °, a root mean square inclination of 25 °, an L * value of 27, a gloss of 60 ° of 11.1%, and a gloss of 85 ° of 36.7%. The presence or absence of bleeding was evaluated to confirm that the ink was unevenly colored. Printed text cannot be recognized under the cover of reflected light.

(Comparative example 3)

Comparative Example 3 was the same as Example 1 except that the black-based colorant added to the insulating protective layer composition was changed to 5 parts by mass and no fine particles were added. The surface of the insulating protective layer has an arithmetic average inclination of 23 °, a root mean square inclination of 30 °, an L * value of 25, a 60 ° gloss of 4.2%, and an 85 ° gloss of 33.1%. The presence or absence of bleeding was evaluated to confirm that the ink was unevenly colored. Typography in reflection It cannot be discerned under the cover of light.

(Comparative Example 4)

Comparative Example 4 was the same as Comparative Example 1 except that a film having a surface roughness of 0.6 μm was used as the base film. The arithmetic mean slope of the surface of the prepared insulating protection layer was 13 °, the root mean square slope was 19 °, the L * value was 28, the 60 ° gloss was 8.0%, and the 85 ° gloss was 43.1%. Printed text cannot be recognized under the cover of reflected light.

(Comparative example 5)

Comparative Example 5 was the same as Example 1 except that the microparticles added to the insulating protective layer composition were changed to 3 parts by mass of urethane resin particles having an average particle diameter of 7 μm. The surface of the prepared insulating protective layer has an arithmetic average inclination of 14 °, a root mean square inclination of 20 °, an L * value of 26, a 60 ° glossiness of 6.1%, and an 85 ° glossiness of 36.9%. Printed text cannot be recognized under the cover of reflected light.

Table 1 shows a list of the composition and characteristics of the insulating protective layer in each of Examples and Comparative Examples.

【Table 1】

The arithmetic mean inclination of the surface of the insulating protective layer of Examples 1 to 3 is 30 ° or more. All of the above insulating protective layers were confirmed to have no uneven ink coloring and printability. good. Compared with the insulating protective layer of the comparative example, the insulating protective layers of Examples 1 to 3 did not bleed and had good visual clarity.

[Industrial availability]

The electromagnetic wave shielding film of the present invention can print small characters and the like with high accuracy, and is useful as an electromagnetic wave shielding film for electronic devices and the like.

110‧‧‧Insulation protective layer

120‧‧‧shield

130‧‧‧Adhesive layer

Claims (1)

An electromagnetic wave shielding film includes an insulating protective layer and a shielding layer, characterized in that the arithmetic average inclination of the surface of the insulating protective layer is above 30 °.