JP6098692B1 - Electromagnetic shielding sheet and printed wiring board - Google Patents

Abstract

An electromagnetic wave shielding sheet having an insulating layer excellent in printing visibility, printing ink adhesion, and ink resistance, having excellent insulation reliability and low repulsion when bonded to an FPC The purpose is to provide. The object is to laminate an insulating transparent resin layer, a black layer, and a conductive adhesive layer (I) in this order, and the surface of the transparent resin layer has a contact angle with water of 60 to 110 °. The problem is solved by an electromagnetic wave shielding sheet. [Selection] Figure 2

Description

  The present invention relates to an electromagnetic wave shielding sheet that shields electromagnetic waves generated from electronic components such as printed wiring boards.

  A flexible printed wiring board (hereinafter referred to as FPC) has flexibility, and its narrow and complex structure is required to meet the demand for higher performance and miniaturization of recent office automation equipment, communication equipment, mobile phones and the like. It is often used to incorporate an electronic circuit inside a casing made of With such downsizing and high frequency of electronic circuits, countermeasures against unnecessary electromagnetic noise generated therefrom are becoming more and more important. Thus, conventionally, an electromagnetic wave shielding sheet for shielding electromagnetic noise generated from an electronic circuit is laminated on the FPC. In addition to the electromagnetic wave shielding property, the electromagnetic wave shielding sheet is required to have thinness and excellent bending resistance so as not to impair the bending resistance of the bonded FPC as a whole. Therefore, the structure which provided the electroconductive adhesive layer and the black layer is widely known for the electromagnetic wave shield sheet on the thin base film.

  For example, Patent Document 1 discloses an electromagnetic wave shield sheet in which an adhesive layer, a cover film, a metal thin film layer, and a conductive adhesive layer are sequentially laminated. Patent Document 2 discloses an electromagnetic wave shielding sheet in which a base film, a metal thin film layer, and a conductive adhesive layer are sequentially laminated. Patent Document 3 discloses an electromagnetic wave shielding sheet in which a cover film, a metal thin film layer, and a conductive adhesive layer are sequentially laminated.

  Usually, after affixing an electromagnetic wave shielding sheet to a large-sized wiring board, it is cut into a predetermined shape to produce a printed wiring board having a size that can be mounted on an electronic device. At this time, in order for the manufacturer to grasp the production lot, the product name and lot number are often printed in white on the black layer of the electromagnetic shielding sheet on the printed wiring board by screen printing or the like. Since the printing area is small, the size of characters is usually small.

JP 2003-298285 A JP 2004-273577 A JP 2004-95566 A

  Conventionally, FPC prints a product number or a lot number on a black layer of a laminated electromagnetic wave shielding sheet. However, in such an electromagnetic wave shielding sheet, bleeding of commonly used printing ink occurs. Therefore, when a small character is printed, there is a problem of printing visibility that an operator hardly recognizes the printing. In addition, due to the low adhesion of the printing ink, if the printing peels off due to contact with other members, or if the resistance to the solvent contained in the printing ink is low, the hardness of the coating film decreases and the printability Ink resistance problems such as lowering of ink and film strength may occur. Further, when the carbon concentration of the black layer is increased in order to improve the printing visibility, there is a problem that conductivity is imparted to the surface of the electromagnetic wave shielding sheet and insulation reliability is deteriorated. Moreover, when the film thickness of the black layer is increased, the repulsive force of the FPC to which the electromagnetic wave shielding sheet is attached becomes stronger, and there is a problem that handling properties deteriorate when mounting.

  The present invention provides an electromagnetic wave shielding sheet having an insulating layer excellent in printing visibility, printing ink adhesion, and ink resistance, and having excellent insulation reliability and low repulsion when bonded to an FPC. For the purpose.

  As a result of intensive studies, the inventors have laminated an insulating transparent resin layer, a black layer, and a conductive adhesive layer (I) in this order, and the surface of the insulating transparent resin layer is in contact with water. It has been found that the above-mentioned problems can be solved by an electromagnetic wave shielding sheet having a specific angle in the range, and the present invention has been achieved.

  That is, in the present invention, an insulating transparent resin layer, a black layer, and a conductive adhesive layer (I) are laminated in this order, and the surface of the transparent resin layer has a contact angle with water of 60 to 110 °. The present invention relates to a characteristic electromagnetic wave shielding sheet.

  The present invention also relates to the electromagnetic wave shielding sheet, wherein the L * value in the L * a * b * color system measured from the insulating transparent resin layer side is 10 to 30.

  Moreover, this invention relates to the said electromagnetic wave shielding sheet characterized by the 85 degree glossiness measured from the insulating transparent resin layer side being 15-50.

In addition, the present invention relates to the electromagnetic wave shielding sheet, wherein the surface resistance value measured from the insulating transparent resin layer side is 1 × 10 ⁵ to 1 × 10 ¹⁴ Ω / □.

  The present invention also relates to the electromagnetic wave shielding sheet, wherein the insulating transparent resin layer is formed from a transparent resin composition containing a photocurable resin, an initiator, and a surface conditioner.

  In the present invention, the electromagnetic wave is characterized in that the insulating transparent resin layer is formed of a transparent resin composition containing a thermosetting resin (A1), a curing agent (A2), and a surface conditioner. It relates to the shield sheet.

  In the electromagnetic wave shielding sheet according to the invention, the black layer is formed of a black resin composition containing a thermosetting resin (B1), a curing agent (B2), and a black colorant. About.

  Further, the present invention is characterized in that the conductive adhesive layer (I) is formed from a conductive adhesive containing a thermosetting resin (C1), a curing agent (C2), and a conductive filler. The present invention relates to the electromagnetic wave shielding sheet.

  In addition, the present invention relates to the electromagnetic wave shielding sheet, wherein the conductive adhesive layer (I) is anisotropically conductive and further includes a conductive layer that is isotropically conductive.

  Further, the present invention is characterized in that the electromagnetic wave shielding sheet, the cover coat layer, and a wiring board having a signal wiring and an insulating base material, wherein the insulating transparent resin layer of the electromagnetic wave shielding sheet is printed. It relates to a printed wiring board.

  The present invention also relates to the printed wiring board, wherein printing is white.

  According to the present invention, an electromagnetic wave shielding sheet having an insulating layer excellent in printing visibility, adhesion of printing ink, and ink resistance, and having excellent insulation reliability and low repulsion when bonded to an FPC. Can be provided.

Cross section of electromagnetic shielding sheet Cross section of printed wiring board

<< Electromagnetic wave shielding sheet >>
The electromagnetic wave shielding sheet of the present invention is laminated in the order of an insulating transparent resin layer, a black layer, and a conductive adhesive layer (I), and the surface of the insulating transparent resin layer has a contact angle with water of 60 to 110. It is characterized by °. By having such an insulative transparent resin layer, when printed on the insulative transparent resin layer, the ink has good wettability, no smearing, and excellent electromagnetic wave shielding capable of printing. It can be a sheet.
Further, the conductive adhesive layer (I) may be either isotropic conductive or anisotropic conductive, and anisotropic conductive is preferable because the cost can be reduced.

  Moreover, it is preferable that the L * value in the L * a * b * color system of the electromagnetic wave shielding sheet measured from the insulating transparent resin layer side is 10-30. When the L * value is in this range, the print visibility becomes better.

Specifically, as such an electromagnetic wave shielding sheet, for example, a first embodiment including an insulating transparent resin layer, a black layer, and a conductive adhesive layer (I) having isotropic conductivity, or insulating transparent The second embodiment includes a resin layer, a black layer, a conductive layer having isotropic conductivity, and a conductive adhesive layer (I) having anisotropic conductivity.
In applications where particularly high electromagnetic shielding properties are required, the second embodiment is preferred.

[L * value of electromagnetic shielding sheet]
In the electromagnetic wave shielding sheet of the present invention, the L * value in the L * a * b * color system measured from the insulating transparent resin layer side is preferably 10-30. When the L * value is 10 to 30, light is absorbed on the surface of the black layer, and for example, characters printed in white can be clearly recognized.
Incidentally, L * a * b * values, Ru axes der representing the color space. a * and b * mean complementary color dimensions. When the L * value is high, the jetness is low . Conversely, when the L * value is low, the jetness is high, so that the print visibility is good.

  In order to obtain such an L * value, for example, the black colorant is preferably blended in an amount of 2 to 50% by weight, more preferably 4 to 40% by weight, in the black layer. Needless to say, the means for adjusting the L * value to 10 to 30 is not limited to the black colorant. When secondary aggregation occurs in the black colorant, the L * value can be adjusted to 10 to 30 by crushing with a sand mill or the like as necessary.

  By setting the L * value to 10 or more, the viscosity stability of the black resin composition can be further improved. Further, when the L * value is 30 or less, the print visibility is further improved.

  Moreover, since the L * value in the L * a * b * color system of the electromagnetic wave shield sheet is 10 to 30, the L * value in the L * a * b * color system of the black layer is 10 to 30. It is preferable that it is, and it is more preferable that it is 20-30. When the L * value of the black layer is 10 to 30, the L * of the electromagnetic wave shielding sheet can also be set to the range of 10 to 30, and the visibility can be improved.

[85 ° glossiness of electromagnetic shielding sheet]
The electromagnetic wave shielding sheet of the present invention preferably has an 85 ° gloss of 15 to 50 measured from the insulating transparent resin layer side. When the 85 ° glossiness is in this range, the print visibility becomes better.

In order to give predetermined glossiness to the surface of the insulating transparent resin layer of the electromagnetic wave shield sheet, for example, the following method can be used.
Unevenness is formed in advance on the release surface of the release sheet by sandblasting or the like. By coating the surface with the insulating transparent resin composition, the unevenness of the peelable sheet is transferred to the insulating transparent resin layer, and appropriate glossiness can be imparted.
As another method, the glossiness can be adjusted by subjecting the formed insulating transparent resin layer to a treatment such as mechanical polishing.
Alternatively, the gloss value on the surface of the insulating transparent resin layer can be adjusted by adding an additive such as a suitable matting agent to the insulating transparent resin composition, regardless of these methods.

[Reflectance of electromagnetic shielding sheet]
In the electromagnetic wave shielding sheet of the present invention, the reflectance at 400 nm to 780 nm measured from the insulating transparent resin layer side is preferably 10% or less. When the reflectance at 400 nm to 780 nm of the electromagnetic wave shielding sheet is in this range, the print visibility becomes better.

[Surface resistance value of electromagnetic shielding sheet]
In the electromagnetic wave shielding sheet of the present invention, the surface resistance value of the insulating layer measured from the insulating transparent resin layer side is preferably 1 × 10 ⁵ or more. When the surface resistance value of the electromagnetic wave shielding sheet is 1 × 10 ⁵ Ω / □ or more, the insulation reliability is further improved.

[Martens hardness of electromagnetic shielding sheet]
Moreover, it is preferable that the electromagnetic shielding sheet of this invention is 20-300 in the Martens hardness measured from the insulating transparent resin layer side. When the Martens hardness is 20 to 300, the ink resistance is improved and the repulsive force is reduced.

  The measurement of these L * values, glossiness, reflectance, surface resistance value, and Martens hardness are values obtained by measuring from the insulating transparent resin layer side using an electromagnetic shielding sheet after thermosetting. The method will be described later.

<< Method for producing electromagnetic wave shielding sheet >>
The electromagnetic wave shielding sheet of the present invention can be produced by a known method and is not particularly limited.
In the case of the first embodiment, for example, the conductive adhesive layer (I) produced on the peelable sheet and the insulating transparent resin layer are separately coated on the peelable sheet, dried, exposed and cured. A black layer is applied to the surface to form a layer. Thereafter, the black layer and the conductive adhesive layer (I) are bonded together.
In the case of the second embodiment, for example, a metal layer which is a conductive layer having isotropic conductivity is formed on a peelable sheet, and an anisotropic conductive conductive adhesive layer (I) is separately formed on the peelable sheet. Is formed on the metal layer surface, and then peeled off and bonded to the black layer separately prepared in the same manner as described above.

In addition to the above layer configuration, the electromagnetic wave shielding sheet of the present invention can be laminated with other functional layers other than conductivity and insulation reliability.
The other functional layer is a layer having functions such as water vapor barrier property, oxygen barrier property, low dielectric constant, high dielectric constant or heat resistance, for example.

  Moreover, it is preferable that the electromagnetic wave shielding sheet of this invention exists in the state (B stage) in which the crosslinkable functional group of the thermosetting resin and the functional group of the hardening | curing agent reacted partially. And when using an electromagnetic wave shield sheet, for example, it piles up on FPC, or after affixing, it is often hardened | cured by a thermocompression-bonding process (C stage), and desired adhesive strength is obtained in many cases.

  The peelable sheet preferably uses a paper or plastic substrate, and a sheet having a known release treatment on one side of the substrate or a pressure sensitive adhesive layer instead of the release treatment is used. It is a formed sheet.

  In many cases, the electromagnetic wave shielding sheet is stored in a state in which a peelable sheet is attached until just before use in order to facilitate the protection and handling of the conductive adhesive layer (I) or the insulating transparent resin layer.

  The electromagnetic wave shielding sheet of the present invention can be used for various applications where electromagnetic waves need to be shielded. For example, rigid printed wiring boards can be used for flexible printed wiring boards, COFs, TABs, flexible connectors, liquid crystal displays, touch panels, and the like. Moreover, it can also be used as a member for shielding electromagnetic waves from a case of a personal computer, a building material such as a wall of a building material and a window glass, a vehicle, a ship, and an aircraft.

<Insulating transparent resin layer>
Since the insulating transparent resin layer of the present invention is located on the outermost surface of the electromagnetic wave shielding sheet and becomes a surface to be printed, adhesion of printing ink, insulation reliability, and ink resistance are required. Moreover, the contact angle with water of the surface of a transparent resin layer is 60-110 degrees. Thereby, the wettability of the ink is improved, and the characters printed on the insulating transparent resin layer have no blur and can be firmly adhered to the surface of the insulating transparent resin layer.
The term “transparent” in the present invention means that the spectral transmittance in the entire wavelength region of wavelength 400 to 700 nm is 30% or more in the actually used film thickness. The spectral transmittance is preferably 40% or more, and more preferably 50% or more.
If the spectral transmittance is 30% or more, even a light yellow or milky white resin layer can be used.
When the spectral transmittance of the insulating transparent resin layer is within this range, the black color of the black layer described later is reflected, so that an electromagnetic wave shielding sheet with good visibility can be obtained.

Moreover, it can be set as the thing excellent in insulation reliability because the surface resistance value measured from the insulating transparent resin layer side is 1 * 10 < ⁵ > -1 * 10 < ¹⁴ > ohm / square.

  The thickness of the insulating transparent resin layer can be appropriately designed according to the use, but is preferably 1 to 10 μm, and more preferably 3 to 8 μm. By setting the thickness of the insulating transparent resin layer to 1 to 10 μm, ink resistance and insulation reliability can be improved, and the repulsive force of the FPC to which the electromagnetic wave shielding sheet is attached can be reduced.

The insulating transparent resin layer can be formed using an insulating transparent resin composition, and the contact angle with water on the surface of the insulating transparent resin layer depends on the composition of the transparent resin composition and the insulating properties described later. It can be controlled by the surface roughness (surface roughness Ra) of the transparent resin layer.
The insulating transparent resin layer can be formed of a transparent resin composition containing a photocurable resin, a thermosetting resin (A1), a curing agent (A2), an initiator, a surface conditioner, and the like.
Among them, the insulating transparent resin layer is a transparent resin composition containing a photocurable resin, an initiator, and a surface conditioner, or a thermosetting resin (A1), a curing agent (A2), and a surface. An electromagnetic wave shielding sheet formed from a transparent resin composition containing a regulator is preferred.

  The insulating transparent resin layer can be formed, for example, by coating a transparent resin composition on a peelable sheet. Or it can form by extruding a transparent resin composition to a sheet form with an extruder, such as T-die.

  Coating, for example, gravure coating method, kiss coating method, die coating method, lip coating method, comma coating method, blade method, roll coating method, knife coating method, spray coating method, bar coating method, spin coating method, dip coating method A known coating method such as can be used. When applying, a drying step may be provided as necessary. For the drying, a known drying device such as a hot air dryer or an infrared heater can be used.

  When the insulating transparent resin layer contains a photocurable resin and an initiator, a curing reaction proceeds by irradiating the transparent resin layer with light of 200 nm to 450 nm after drying to increase the strength of the coating film. The light irradiation may be from the coated surface of the transparent resin layer, but when the peelable sheet has a spectral transmittance of 70% or more at 200 nm to 450 nm, the light can also be irradiated from the peelable sheet surface.

[Water contact angle of insulating transparent resin layer]
The insulating transparent resin layer of the electromagnetic wave shielding sheet of the present invention has a water contact angle of 60 to 110 °, and more preferably 70 to 100 °. When the water contact angle is 60 to 110 °, the wettability of the ink is improved, and the characters printed on the insulating transparent resin layer do not bleed and adhere firmly to the surface of the insulating transparent resin layer.
When the water contact angle is 60 ° or more, the wettability of the ink is improved, and there is no bleeding and printing with good visibility becomes possible. Moreover, when glossiness becomes 110 degrees or less, the ink coating-film adhesiveness to the insulating transparent resin layer surface improves more. In addition, a water contact angle is a value after the thermosetting of an electromagnetic wave shield sheet, and a measuring method is mentioned later.

[Dynamic friction coefficient of insulating transparent resin layer]
The coefficient of dynamic friction of the insulating transparent resin layer of the electromagnetic wave shielding sheet of the present invention is preferably 0.01 to 0.5, and more preferably 0.05 to 0.4. Since the coefficient of dynamic friction is 0.01 to 0.5, the wettability of the ink is improved, and the characters printed on the insulating transparent resin layer have no blur and adhere to the surface of the insulating transparent resin layer. Visibility is improved. In addition, a dynamic friction coefficient is the value of the insulating transparent resin layer surface after thermosetting of an electromagnetic wave shield sheet, and a measuring method is mentioned later.

"Transparent resin composition"
Subsequently, a photocurable resin, an initiator, and a thermosetting resin (A1), a curing agent (A2), a surface conditioner, and the like that constitute a transparent resin composition for forming a transparent resin layer, Each will be explained.

The transparent resin composition can be obtained by mixing and stirring a photocurable resin, an initiator, a surface conditioner, and additives as required.
Alternatively, it can be obtained by mixing and stirring the thermosetting resin (A1), the curing agent (A2), the surface conditioner, and additives as necessary.
For the stirring, a known stirring device can be used, and a disperse mat or a homogenizer is preferable.

(Photo-curing resin)
The photocurable resin may be a resin having at least one unsaturated bond that causes a crosslinking reaction by light, for example, acrylic resin, maleic acid resin, polybutadiene resin, polyester resin, polyurethane resin, epoxy resin. Examples include resins, oxetane resins, phenoxy resins, polyimide resins, polyamide resins, phenolic resins, alkyd resins, amino resins, polylactic acid resins, oxazoline resins, benzoxazine resins, silicone resins, and fluorine resins.
Moreover, the photocurable resin may have a functional group that can be used for a crosslinking reaction by heating.

(Initiator)
As initiators, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl Phenylketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1- Acetophenone photopolymerization initiators such as ON, 1,2-octadion-1- [4- (phenylthio)-, 2- (o-benzoyloxime)], ethanone, 1- [9-ethyl-6- (2- Oximes such as methylbenzoyl) -9H-carbazol-3-yl]-, 1- (o-acetyloxime) Benzoin photopolymerization initiators, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyldimethyl ketal and other benzoin photopolymerization initiators, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxy Benzophenone photopolymerization initiators such as benzophenone, acrylated benzophenone, 4-benzoyl-4′-methyldiphenyl sulfide, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-diisopropyl Thioxanthone photopolymerization initiators such as thioxanthone, 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2 (P-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-tolyl) -4,6-bis (trichloromethyl) -s-triazine, 2-piperonyl-4,6 -Bis (trichloromethyl) -s-triazine, 2,4-bis (trichloromethyl) -6-styryl-s-triazine, 2- (naphth-1-yl) -4,6-bis (trichloromethyl) -s -Triazine, 2- (4-methoxy-naphth-1-yl) -4,6-bis (trichloromethyl) -s-triazine, 2,4-trichloromethyl- (piperonyl) -6-triazine, 2,4- Triazine photopolymerization initiators such as trichloromethyl (4′-methoxystyryl) -6-triazine, borate photopolymerization initiators, carbazole photopolymerization initiators, or imidazoles Photopolymerization initiator and the like are used. These photopolymerizable compounds can be used singly or in combination of two or more at any ratio as required.

  Of these, acetophenone-based photopolymerization initiators and oxime ester-based photopolymerization initiators are preferable because yellowing is less during the heating step and the transmittance is increased. Specific examples of the acetophenone photopolymerization initiator include Irgacure 907 (manufactured by BASF), Irgacure 379 (manufactured by BASF), Irgacure 379EG (manufactured by BASF), and the like.

  Among them, the oxime ester photopolymerization initiator is particularly preferable because it has high sensitivity and can reduce the addition amount. These may be used alone or in combination.

  Among the oxime ester photopolymerization initiators, 1,2-octadion-1- [4- (phenylthio) phenyl-, 2- (o-benzoyloxime)], ethanone, 1- [9-ethyl-6- ( 2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (o-acetyloxime)) is less yellowed during the heating step and has a high transmittance as a coating film, particularly in the vicinity of a wavelength of 400 nm. Since a photosensitive composition having high transmittance can be provided, it is more preferable. These may be used alone or in combination. Specifically, Irgacure OXE01 (manufactured by BASF), Irgacure OXE02 (manufactured by BASF) and the like.

  The initiator is preferably used in an amount of 0.5 to 10% by weight in the total solid content of 100% by weight of the transparent resin composition, and used in an amount of 0.5 to 5% by weight from the viewpoint of printing resistance. Is more preferable.

The transparent resin composition of the present invention further includes α-acyloxy ester, acylphosphine oxide, methylphenylglyoxylate, benzyl, 9,10-phenanthrenequinone, camphorquinone, ethylanthraquinone, as a sensitizer. Compounds such as 4,4′-diethylisophthalophenone, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, 4,4′-diethylaminobenzophenone can be used in combination.
The sensitizer can be used in an amount of 0.1 to 150 parts by weight with respect to 100 parts by weight of the initiator.

(Thermosetting resin (A1))
The thermosetting resin (A1) is a resin having a plurality of functional groups that can be used for a crosslinking reaction by heating.
Examples of the functional group include a hydroxyl group, a phenolic hydroxyl group, a carboxyl group, an amino group, an epoxy group, an oxetanyl group, an oxazoline group, an oxazine group, an aziridine group, a thiol group, an isocyanate group, a blocked isocyanate group, and a silanol group. .
The thermosetting resin (A1) having the above functional group is, for example, an acrylic resin, a maleic acid resin, a polybutadiene resin, a polyester resin, a condensation type polyester resin, an addition type polyester resin, a melamine resin, a polyurethane resin, or a polyurethane urea resin. , Epoxy resin, oxetane resin, phenoxy resin, polyimide resin, polyamide resin, polyamideimide resin, phenolic resin, alkyd resin, amino resin, polylactic acid resin, oxazoline resin, benzoxazine resin, silicone resin, fluorine resin, etc. . Among these, polyurethane resin, polyurethane urea resin, addition-type polyester resin, polyamide resin, polyimide resin, and polyamideimide resin are preferable from the viewpoint of repulsive force and ink resistance.

In the present invention, a thermoplastic resin can be used in combination with the thermosetting resin (A1).
As thermoplastic resins, polyolefin resins, vinyl resins, styrene / acrylic resins, diene resins, terpene resins, petroleum resins, cellulose resins, polyamide resins, polyurethane resins, polyester resins that do not have the above curable functional groups. , Polycarbonate resin, polyimide resin, fluorine resin and the like.
The polyolefin resin is preferably a homopolymer or copolymer such as ethylene, propylene, and α-olefin compound. Specific examples include polyethylene propylene rubber, olefinic thermoplastic elastomer, α-olefin polymer, and the like.
The vinyl resin is preferably a polymer obtained by polymerization of vinyl ester such as vinyl acetate or a copolymer of vinyl ester and olefin compound such as ethylene. Specific examples include ethylene-vinyl acetate copolymer and partially saponified polyvinyl alcohol.
The styrene / acrylic resin is preferably a homopolymer or copolymer composed of styrene, (meth) acrylonitrile, acrylamides, (meth) acrylic acid esters, maleimides and the like. Specific examples include syndiotactic polystyrene, polyacrylonitrile, acrylic copolymer, ethylene-methyl methacrylate copolymer, and the like.
The diene resin is preferably a homopolymer or copolymer of a conjugated diene compound such as butadiene or isoprene and a hydrogenated product thereof. Specific examples include styrene-butadiene rubber and styrene-isoprene block copolymer. The terpene resin is preferably a polymer composed of terpenes or a hydrogenated product thereof. Specific examples include aromatic modified terpene resins, terpene phenol resins, and hydrogenated terpene resins.
The petroleum resin is preferably a dicyclopentadiene type petroleum resin or a hydrogenated petroleum resin. The cellulose resin is preferably a cellulose acetate butyrate resin. The polycarbonate resin is preferably bisphenol A polycarbonate. The polyimide resin is preferably a thermoplastic polyimide, a polyamideimide resin, or a polyamic acid type polyimide resin.

(Curing agent (A2))
The curing agent (A2) has a plurality of functional groups that can react with the functional groups in the thermosetting resin (A1). The curing agent is preferably an epoxy compound, an acid anhydride group-containing compound, an isocyanate compound, an aziridine compound, an amine compound such as dicyandiamide, an aromatic diamine, or a phenol compound such as a phenol novolac resin.

  The curing agent (A2) is preferably contained in an amount of 1 to 50 parts by weight, more preferably 3 to 30 parts by weight, and even more preferably 3 to 20 parts by weight with respect to 100 parts by weight of the thermosetting resin (A1).

  The photocurable resin and the thermosetting resin can be used alone, but it is preferable to use them together from the viewpoint of further improving the ink resistance and the insulation reliability.

(Surface conditioner)
In order to adjust the wettability of the surface of the transparent resin composition, it is preferable to add a surface conditioner. Examples of the surface conditioner include waxes, leveling agents, surfactants, silane coupling agents, and inorganic fillers. Waxes, leveling agents, silane coupling agents, and inorganic fillers are preferable, and waxes, leveling agents, and inorganic fillers are preferable. More preferred. Although the said surface treating agent may be used independently, it is preferable to use 2 or more types together. Specifically, a combination of a wax and an inorganic filler or a leveling agent and an inorganic filler is preferable. The transparent resin composition of the present invention can easily adjust the contact angle with water on the surface of the transparent resin layer to 60 to 110 ° by adding a surface conditioner, and the print visibility and ink adhesion are improved. .

As the wax, for example, natural wax such as candelilla wax, carnauba wax, rice wax, wax wax, jojoba oil and other animal waxes, beeswax, lanolin, whale wax and other animal waxes, montan wax, ozokerite, cecilen, etc. Petroleum waxes such as mineral wax, paraffin wax, microcrystalline wax, petrolatum, synthetic waxes such as Fischer-Tropish wax, synthetic hydrocarbons such as polyethylene wax, montan wax derivatives, paraffin wax derivatives, microcrystalline wax derivatives, etc. Hydrogenated wax such as modified wax, hydrogenated castor oil, hydrogenated castor oil derivative, fatty acid such as lanolinic acid, palmitic acid, myristic acid, stearic acid, 12-hydroxystearic acid There is.
These waxes have a melting point of 30 to 140 ° C., preferably 60 to 120 ° C. When the melting point of the wax is less than 30 ° C., contamination is likely to occur due to the bleed out of the wax. If the melting point of the wax exceeds 140 ° C., the adhesion of the printing ink is difficult to improve.

  The blending ratio of the photocurable resin or thermosetting resin and the wax used in the present invention is preferably 0.5 to 40 parts by weight of wax with respect to 100 parts by weight of the resin, and 1 to 20 parts by weight. More preferably. If the amount of wax is less than 0.5 parts by weight with respect to 100 parts by weight of the resin, the effect on the wear resistance cannot be expected so much. On the other hand, if the amount of wax is more than 40 parts by weight, bleeding out occurs. The physical properties may be degraded.

  As the leveling agent used in the present invention, a polyether structure, a polyester structure, an aralkyl structure, a polysiloxane having an acrylic group, and an acrylic copolymer can be used in the main chain. Specific examples of dimethylsiloxane having a polyether structure in the main chain include FZ-2110, 2122, 2130, 2166, 2191, 2032, 2207, manufactured by Toray Dow Corning, BYK-330, BYK-323, BYK manufactured by BYK Chemie. -348 and the like. Specific examples of dimethylsiloxane having a polyester structure in the main chain include BYK-310 and BYK-370 manufactured by BYK Chemie. Specific examples of polymethylsiloxane having an aralkyl structure in the main chain include BYK-322 and BYK-323 manufactured by BYK Chemie. Specific examples of polydimethylsiloxane having an alkyl group in the main chain include BYK-3500, BYK-3505, BYK-3530, BYK-3570 and the like manufactured by BYK Chemie. Specific examples of the acrylic copolymer system include BYK-350, BYK-354, BYK-355, BYK-358, BYK-381, BYK-392, BYK-394, and BYK-3441 manufactured by BYK Chemie.

In general, anionic, nonionic, zwitterionic, and cationic surfactants are known as the surfactant used in the present invention, but any of them can be used.
Examples of the anionic surfactant include alpha sulfo fatty acid methyl ester salts, alkylbenzene sulfonates, alkyl sulfate esters, alkyl ether sulfate esters, monoalkyl phosphate esters, alpha olein sulfonates, alkane sulfonates. Etc.
Nonionic surfactants include, for example, glycerin fatty acid ester, sucrose fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acid ester, fatty acid alkanolamide, polyoxyethylene alkyl ether, alkyl glucoside, poly Examples thereof include oxyethylene alkylphenyl ether.

Examples of zwitterionic surfactants include alkylamino fatty acid salts, alkylbetaines, and alkylamine oxides.
Examples of the cationic surfactant include alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, N-methylbishydroxyethylamine fatty acid ester hydrochloride, and the like.
In addition, reactive surfactants such as fluorine-based surfactants and allyl-based reactive surfactants, and polymer surfactants such as cationic cellulose derivatives, polycarboxylic acids, and polystyrene sulfonic acids can also be used. These are also commercially available as wetting and dispersing agents. 101, Disperbyk-108, Disperbyk-130 (above, manufactured by Big Chemie Japan Co., Ltd.) and the like.
One of these surfactants may be used alone, or two or more thereof may be used in combination, or a surfactant and a compound other than the surfactant may be used in combination.

  Examples of the silane coupling agent include vinyl silane coupling agents, epoxy silane coupling agents, amino silane coupling agents, vinyl silane coupling agents, methacrylic coupling agents, thiol coupling agents, and isocyanates. A silane coupling agent or the like can be used.

  Examples of the vinyl silane coupling agent include vinyltrimethoxysilane and vinyltriethoxysilane.

  Examples of the epoxy silane coupling agent include 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3- Examples thereof include glycidoxypropylmethyldiethoxysilane and 3-glycidoxypropyltriethoxysilane.

  Examples of amino silane coupling agents include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and 3-aminopropyltrimethoxysilane. Examples include methoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, and N-phenyl-3-aminopropyltrimethoxysilane.

  Examples of the vinyl silane coupling agent include vinyltrimethoxysilane and vinyltriethoxysilane.

  Examples of the methacrylic silane coupling agent include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane.

  Examples of the thiol-based silane coupling agent include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane.

  Examples of the isocyanate-based silane coupling agent include 3-isocyanatopropyltriethoxysilane.

  The mixing ratio of the resin and the silane coupling agent is preferably 0.1 to 25 parts by weight, and more preferably 0.5 to 15 parts by weight with respect to 100 parts by weight of the resin.

  Examples of the inorganic filler include inorganic substances such as silica, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, calcium carbonate, titanium oxide, zinc oxide, antimony trioxide, magnesium oxide, talc, montmorolinite, kaolin, and bentonite. Compounds.

  The ratio of the weight of the resin component of the photocurable resin and thermosetting resin (A1) in the transparent resin composition and the surface modifier is preferably 100: 0.01 to 100: 10, and 100: More preferably, it is 0.05-100: 5. By setting it as the above ratio, drying unevenness after coating the transparent resin composition on the peelable sheet can be suppressed and coating can be performed more uniformly, so that the printing visibility and the insulation reliability are improved. Moreover, it is preferable because ink resistance is improved.

  The transparent resin composition is a photocurable monomer, a photocurable oligomer, a rust inhibitor, a reducing agent, an antioxidant, a tackifier resin, a plasticizer, an ultraviolet absorber, an antifoaming agent, and leveling adjustment as other components. An agent, a filler, a flame retardant, etc. can be mix | blended. Further, pigments, dyes and the like may be included as long as the transparency is not impaired.

《Black layer》
As the black layer of the present invention, a conventionally known black layer can be used, but it is formed of a black resin composition containing a thermosetting resin (B1), a curing agent (B2), and a black colorant. A black resin layer is preferred. As a result, it is possible to visually recognize the characters printed on the surface of the insulating transparent resin layer with excellent visibility and with high visibility, particularly when the printing is white. .

  In addition, the black layer may be conductive or insulative as long as the black layer is a black colored layer and can improve printing visibility by being black with high jetness. Since the electromagnetic wave shielding sheet of the present invention has an insulating transparent resin layer having a specific contact angle on the outermost surface, carbon black is used as the black colorant for the black layer, and the case is conductive. However, the transmission characteristic of the flexible wiring board is good, and an electromagnetic wave shielding sheet excellent in insulation reliability can be obtained.

  Further, in order to obtain an electromagnetic wave shielding sheet with more excellent insulation reliability, it is also preferable that the black layer has an insulating property. At this time, the content of the black colorant is preferably 2 to 30% by weight and more preferably 4 to 20% by weight in 100% by weight of the solid content of the black layer.

Further, the surface resistance value of the black layer is preferably 1 × 10 ⁵ to 1 × 10 ¹⁴ Ω / □ because it can be excellent in insulation reliability.

  The black layer of the present invention refers to a case where the spectral transmittance in the entire wavelength region of a wavelength of 400 to 700 nm is less than 30% in the actually used film thickness. The spectral transmittance is preferably less than 20%, and more preferably less than 10%. Moreover, when a part of spectral transmittance in wavelength 400-700nm shows the transmittance | permeability of 30% or more, and it is a colored layer other than black, it does not correspond to the black layer in this invention.

  Although the thickness of a black layer can be suitably designed according to a use, 0.5-20 micrometers is preferable and 1-15 micrometers is more preferable. By setting the thickness of the black layer to 0.5 to 20 μm, it is possible to improve the printing visibility and reduce the repulsive force of the FPC to which the electromagnetic wave shielding sheet is attached.

"Black resin composition"
The black resin composition preferably contains a thermosetting resin (B1), a curing agent (B2), and a black colorant. The black resin composition may contain other additives as necessary.

  Here, the thermosetting resin (B1) and the curing agent (B2) can be appropriately selected from the thermosetting resin (A1) and the curing agent (A2) described in the transparent resin layer.

(Black colorant)
A black layer can improve the visibility of the printed character by including a black colorant. The black colorant is preferably a black color pigment and a mixed colorant containing a plurality of pigments such as red, green, blue, yellow, purple, cyan and magenta. The mixed colorant can obtain black color by subtractive color mixing of a plurality of pigments.
Examples of the black pigment include carbon black, ketjen black, carbon nanotube (CNT), perylene black, titanium black, iron black, and aniline black.

  The black colorant preferably has an average primary particle size of 10 to 200 nm, more preferably 20 to 100 nm. By using the black colorant having the average primary particle diameter, the black layer can be colored black with high jetness without color unevenness, and the visibility of characters is further improved. By setting the average primary particle diameter to 10 nm or more, the viscosity of the black resin composition can be easily maintained at a level suitable for coating. Moreover, jet blackness of a black layer improves by making an average primary particle diameter 200 nm or less, and printing visibility improves more. In addition, when the particle shape of the black colorant has an average aspect ratio (major axis length / minor axis length) of 1.5 or more, the average primary particle diameter is obtained by averaging the major axis lengths.

  The average primary particle diameter of the black colorant can be determined from an average value of about 20 primary particles that can be observed from an image magnified 10,000 to 1,000,000 times with a transmission electron microscope (TEM).

  The content of the black colorant is preferably 2 to 50% by weight and more preferably 4 to 40% by weight in 100% by weight of the solid content of the black layer. By including 2 to 40% by weight of the black colorant, the black layer can easily achieve both good print visibility and the optimum coating viscosity of the black colorant.

  The following pigments can be used as the mixed black colorant. “CI” means a color index (CI).

  Examples of red pigments and magenta pigments include C.I. I. Pigment Red 7, 14, 41, 48: 1, 48: 2, 48: 3, 48: 4, 57: 1, 81, 81: 1, 81: 2, 81: 3, 81: 4, 122, 146, 168, 176, 177, 178, 184, 185, 187, 200, 202, 208, 210, 242, 246, 254, 255, 264, 270, 272, and 279.

  Examples of the green pigment include C.I. I. Pigment green 1, 2, 4, 7, 8, 10, 13, 14, 15, 17, 18, 19, 26, 36, 45, 48, 50, 51, 54, 55 and 58.

  Blue pigments and cyan pigments are exemplified by C.I. I. Pigment Blue 1, 1: 2, 9, 14, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17, 19, 25, 27, 28, 29, 33, 35, 36, 56, 56: 1, 60, 61, 61: 1, 62, 63, 66, 67, 68, 71, 72, 73, 74, 75, 76, 78, 79 and the like.

  Examples of yellow pigments include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 10, 12, 13, 14, 15, 16, 17, 18, 24, 31, 32, 34, 35, 35: 1, 36, 36: 1, 37, 37: 1, 40, 42, 43, 53, 55, 60, 61, 62, 63, 65, 73, 74, 77, 81, 83, 93, 94, 95, 97, 98, 100, 101, 104, 106, 108, 109, 110, 113, 114, 115, 116, 117, 118, 119, 120, 123, 126, 127, 128, 129, 138, 139, 147, 150, 151, 152, 153, 154, 155, 156, 161, 162, 164, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 179, 180, 181, 82,184,185,187,188,193,194,198,199,213 and 214, and the like.

  Examples of purple pigments include C.I. I. Pigment Violet 1, 1: 1, 2, 2: 2, 3, 3: 1, 3: 3, 5, 5: 1, 14, 15, 16, 19, 23, 25, 27, 29, 31, 32, 37, 39, 42, 44, 47, 49, 50 and the like.

  The black resin composition contains pigments and dyes other than black colorants, as well as dispersants, antioxidants, tackifier resins, plasticizers, ultraviolet absorbers, antifoaming agents, fillers, flame retardants, etc. as necessary. Can be included.

  The black resin composition can be obtained by mixing the thermosetting resin (B1) solution obtained by dispersing the black colorant with the other thermosetting resin (B1), the curing agent (B2), and the like and stirring them. it can. For the stirring, a known stirring device can be used, and a disperse mat or a homogenizer is preferable.

  The black layer can be formed, for example, by coating a black resin composition on a peelable sheet. Alternatively, the black resin composition can be formed by extruding it into a sheet shape by an extruder such as a T-die.

  Coating, for example, gravure coating method, kiss coating method, die coating method, lip coating method, comma coating method, blade method, roll coating method, knife coating method, spray coating method, bar coating method, spin coating method, dip coating method A known coating method such as can be used. When applying, a drying step may be provided as necessary. For the drying, a known drying device such as a hot air dryer or an infrared heater can be used.

<< Conductive adhesive layer (I) >>
The conductive adhesive layer (I) can be formed of a thermosetting resin (C1), a curing agent (C2), and a conductive adhesive (i) containing a conductive filler. The conductive adhesive layer (I) has adhesiveness because it is affixed to a cover film, an insulating substrate or the like formed on the printed wiring board.

  The conductive adhesive layer (I) can be appropriately selected from an isotropic conductive adhesive layer or an anisotropic conductive adhesive layer. The isotropic conductive adhesive layer has conductivity in the vertical direction and the horizontal direction with the electromagnetic wave shielding sheet placed horizontally. The anisotropic conductive adhesive layer has conductivity only in the vertical direction with the electromagnetic wave shielding sheet placed horizontally.

  The conductive adhesive layer (I) can be produced in the same manner as described for the black layer using the conductive adhesive (i).

  The thickness of the conductive adhesive layer (I) is preferably 1 to 100 μm, more preferably 3 to 50 μm, and still more preferably 4 to 15 μm. It becomes easy to make electroconductivity and other physical properties compatible because thickness exists in the range of 1-100 micrometers.

"Conductive adhesive (i)"
Next, the conductive adhesive (i) for forming the conductive adhesive layer (I) will be described. A conventionally well-known thing can be used for conductive adhesive (i), for example, thermosetting resin (C1), hardening | curing agent (C2), a conductive filler, and other additives as needed, etc. It is a conductive adhesive contained.

  Here, the thermosetting resin (C1) and the curing agent (C2) can be appropriately selected from the thermosetting resin (A1) and the curing agent (A2) described in the transparent resin layer.

(Conductive filler)
The conductive fine particles which are conductive fillers are preferably conductive metals such as gold, platinum, silver, copper and nickel, alloys thereof, and conductive polymer particles. In addition, composite fine particles in which a metal or a resin is used as a nucleus instead of fine particles having a single composition and a coating layer covering the surface of the nucleus is formed of a highly conductive material is preferable from the viewpoint of cost reduction.
The nucleus is preferably selected from nickel, silica, copper and resin, and more preferably a conductive metal and an alloy thereof.
The covering layer may be a material having excellent conductivity, and is preferably a conductive metal or a conductive polymer. Examples of the conductive metal include gold, platinum, silver, tin, manganese, indium, and the like, and alloys thereof. Examples of the conductive polymer include polyaniline and polyacetylene. Among these, silver is preferable from the viewpoint of conductivity.
The conductive fine particles can be used alone or in combination of two or more.

  The composite fine particles preferably have a coating layer at a ratio of 1 to 40 parts by weight, and more preferably 5 to 30 parts by weight with respect to 100 parts by weight of the nucleus. Covering with 1 to 40 parts by weight can further reduce the cost while maintaining conductivity. In the composite fine particles, it is preferable that the coating layer completely covers the core. However, in practice, a part of the nucleus may be exposed. Even in such a case, if the conductive material covers 70% or more of the surface area of the nucleus, it is easy to maintain conductivity.

  The shape of the conductive fine particles is not limited as long as desired conductivity is obtained. Specifically, for example, a spherical shape, a flake shape, a leaf shape, a dendritic shape, a plate shape, a needle shape, a rod shape, and a grape shape are preferable. The conductive fine particles generally have isotropic conductivity when flaky fine particles are used, and anisotropic conductivity is obtained when spherical or dendritic fine particles are used.

The average particle diameter of the conductive fine particles is D50 average particle diameter, preferably 1 to 100 μm, more preferably 3 to 50 μm.
The D50 average particle size is a numerical value obtained by measuring conductive fine particles with a tornado dry powder sample module using a laser diffraction / scattering particle size distribution measuring device LS13320 (manufactured by Beckman Coulter, Inc.). The cumulative value in the cumulative particle size distribution is a particle size of 50%. The refractive index was set to 1.6.

  When forming the isotropic conductive adhesive layer, the conductive fine particles are preferably blended in an amount of 100 to 1500 parts by weight, more preferably 200 to 1000 parts by weight, with respect to 100 parts by weight of the thermosetting resin (C1). preferable. When forming an anisotropic conductive adhesive layer, it is preferable to mix | blend 10-200 weight part with respect to 100 weight part of thermosetting resins (C1), and 20-150 weight part is more preferable.

  The conductive adhesive (i) further includes a silane coupling agent, a rust inhibitor, a reducing agent, an antioxidant, a pigment, a dye, a tackifier resin, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling regulator, and a filling. An agent, a flame retardant, etc. can be mix | blended.

  The conductive adhesive (i) can be obtained by mixing and stirring the conductive filler and the thermosetting resin (C1). For the stirring, a known stirring device can be used, and a disperse mat or a homogenizer is preferable.

<< Conductive layer >>
As a second embodiment, when the transparent resin layer, the black layer, and the conductive adhesive layer (I) further have a conductive layer, the conductive adhesive layer (I) has anisotropic conductivity, and the conductive layer Is isotropically conductive.
This second embodiment is preferred for applications that require particularly high electromagnetic shielding properties.
Examples of the isotropic conductive layer (isotropic conductive layer) include a metal layer or a conductive adhesive layer (II). A metal layer is preferable in terms of improving electromagnetic shielding properties and transmission characteristics against high frequency signals of 100 MHz to 20 GHz. On the other hand, the conductive adhesive layer (II) is preferable in terms of heat resistance such as solder reflow.

The metal layer can be selected from a metal foil, a vapor deposition film, a sputtering film, and a metal plating film. The metal foil is preferably a conductive metal foil such as aluminum, copper, silver, or gold, more preferably copper, silver, or aluminum, and even more preferably copper in terms of shielding properties and cost.
For example, rolled copper foil or electrolytic copper foil is preferably used as the copper, and when the thickness of the metal layer is pursued, a rolled copper foil or an electrolytic copper foil is more preferable. In the case of a metal foil, the thickness is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.
The vapor deposition film, the sputtering film, and the metal plating film are preferably formed of a conductive metal material such as aluminum, copper, silver, or gold, and more preferably copper, silver, or aluminum. The thickness of the deposited film is preferably 0.1 to 3 μm. The thickness of the sputtering film is preferably 10 to 1000 nm. As for the thickness of a metal plating film, 0.5-5 micrometers is preferable normally.

As the thermosetting resin or the like constituting the conductive adhesive layer (II), the same one as that having isotropic conductivity in the description of the conductive adhesive layer (I) can be used.
The conductive adhesive layer (II) can be formed of a conductive adhesive (ii), and the conductive adhesive (ii) is a conventionally known one as well as the conductive adhesive (i). For example, it is a conductive adhesive containing the thermosetting resin described in the conductive adhesive (i), a curing agent, a conductive filler, and other additives as necessary.

The conductive filler in the conductive adhesive layer (II) is preferably blended in an amount of 300 to 2000 parts by weight and more preferably 500 to 1500 parts by weight with respect to 100 parts by weight of the thermosetting resin.
The thickness of the conductive adhesive layer (II) at this time is preferably 2 to 15 μm, more preferably 3 to 10 μm.
The shape of the conductive filler used for the conductive adhesive layer (II) is preferably a flake shape or a dendritic shape. By using a flaky or dendritic conductive filler, high conductivity can be expressed with a thinner film thickness, and the repulsive force can be reduced.

<< Printed wiring board >>
The printed wiring board of the present invention includes the electromagnetic wave shielding sheet of the present invention and a wiring board including a cover coat layer, signal wiring, and an insulating substrate.
In particular, when printing is performed on the insulating transparent resin layer of the electromagnetic wave shielding sheet, even when using a printing ink that is usually used, when a small character is printed without causing bleeding, the operator It is easy to visually recognize the print and can be excellent in print visibility.
In particular, when the printing is white, the printing visibility can be improved, which is preferable.

The printed wiring board of the present invention will be described with reference to FIG. 2 by taking the second embodiment as an example.
The electromagnetic wave shielding sheet 11 includes an insulating transparent resin layer 1 and a black layer 2, a conductive layer 4 having isotropic conductivity, and a conductive adhesive layer (I) 3 having anisotropic conductivity.
In addition, although not shown in figure, the structure of the 1st embodiment in which the electromagnetic wave shield sheet has the insulating transparent resin layer 1, the black layer 2, and the electroconductive adhesive layer (I) 3 is also preferable. The conductive adhesive layer (I) at this time is preferably isotropic conductive.

  The cover coat layer 6 is an insulating material that covers the signal wiring of the wiring board and protects it from the external environment. The cover coat layer 6 is preferably a polyimide cover lay film with an adhesive, a thermosetting or ultraviolet curable solder resist, or a photosensitive cover lay film, and more preferably a photosensitive cover lay film for fine processing.

The signal wiring includes a ground wiring 8 for grounding and a wiring circuit 9 for sending an electric signal to the electronic component. Both are generally formed by etching a copper foil.
When the insulating substrate 7 is a flexible printed wiring board (FPC), a bendable plastic such as polyester, polycarbonate, polyimide, or polyphenylene sulfide is preferable, and polyimide is more preferable. When the wiring board is a rigid wiring board, the constituent material of the insulating substrate 7 is preferably glass epoxy. By providing the insulating base material 7 as described above, the wiring board can have high heat resistance.

  Generally, the thermocompression bonding between the electromagnetic shielding sheet 11 and the wiring board is performed under conditions of a temperature of about 150 to 190 ° C., a pressure of about 1 to 3 MPa, and a time of about 1 to 60 minutes. The conductive adhesive layer (I) 3 and the cover coat layer 6 are brought into close contact with each other by thermocompression bonding, and the conductive adhesive layer (I) 3 flows and fills the hole 10, thereby conducting electrical continuity with the ground wiring 8. I can take it. Further, the thermosetting resin and the curing agent react by thermocompression bonding. In order to accelerate curing, post-curing may be performed at 150 to 190 ° C. for 30 to 90 minutes after thermocompression bonding. In addition, an electromagnetic wave shield sheet may be called an electromagnetic wave shield layer after thermocompression bonding.

"Printing ink"
Examples of the printing ink include silk screen ink or inkjet ink, and are composed of a colorant, a binder resin, an additive, and a solvent. The solvent is an organic solvent having a boiling point of 40 to 140 ° C. from the viewpoint of printability. It is selected appropriately.
Moreover, it is preferable that it is white printing ink from a viewpoint of printing visibility.

  After thermocompression bonding, the lot number or product number can be printed on the surface of the insulating transparent resin layer 1 of the electromagnetic wave shielding sheet by printing ink by silk screen printing, ink jet printing or the like. The size of characters to be printed is usually 1 to 10 points. After printing, the print is cured by being dried in an oven at 100 to 170 ° C., and is in close contact with the insulating transparent resin layer 1. Where the black layer 2 is black, the color of printing is preferably white in order to improve visibility.

  The printed wiring board of the present invention is preferably provided in an electronic device such as a notebook PC, a mobile phone, a smartphone, and a tablet terminal in addition to a liquid crystal display and a touch panel.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the examples do not limit the scope of rights of the present invention. In the examples, “part” represents “part by weight” and “%” represents “% by weight”.

The thermosetting resins (A1, B1, C1), curing agents (A2, B2, C2), conductive fillers, photocurable resins, initiators, and surface conditioners used in the examples are shown below.
[Thermosetting resin (A1, B1, C1)]
Thermosetting resin 1: Thermosetting polyurethane resin (acid value = 5 mg KOH / g, Tg = 0 ° C.) Thermosetting resin manufactured by Toyochem 2: Thermosetting polyamide resin (acid value = 20 mg KOH / g, Tg = 20 ° C.) ) Thermosetting resin 3 manufactured by Toyochem Co., Ltd .: Thermosetting addition type ester resin (acid value = 10 mg KOH / g, Tg = 10 ° C.) Thermosetting resin 4: Thermosetting polyester resin manufactured by Toyochem Co., Ltd. (acid value = 10 mg KOH / g, Tg = −10 ° C.) manufactured by Toyochem [curing agents (A2, B2, C2)]
Hardener 1: Bisphenol A type epoxy resin “JER828” (epoxy equivalent = 189 g / eq) Hardener made by Mitsubishi Chemical Corporation: Aziridine compound “Chemite PZ-33” manufactured by Nippon Shokubai Co., Ltd. [Monomer]
DPHA: dipentaerythritol hexaacrylate [photocurable resin]
Photocurable resin 1: Urethane acrylate resin “UV6300B” (molecular weight Mw = 3700) manufactured by Nippon Synthetic Chemical Co., Ltd. [Initiator]
Initiator 1: 1-hydroxy-cyclohexyl-phenyl-ketone

[Surface conditioner]
Surface modifier 1: Amide wax “CERAFLOUR 994 (average particle size D50: 5 μm, melting point: 145 ° C.)” Surface modifier 2: Big polyethylene wax “CERAFLOUR 961 (average particle size D50: 3.5 μm, melting point: 140) "Surface conditioner 3: BYK350" manufactured by BYK Chemie Co., Ltd. "BYK350", a surface conditioner manufactured by BYK Chemie Co., Ltd .: Polyether-modified polydimethylsiloxane-based leveling agent "BYK300", surface adjuster 5 manufactured by BYK Chemie Co., Ltd .: Polypropylene wax "CERAFLOUR970" (Average particle diameter D50: 9 μm, melting point: 160 ° C.) “Surface conditioner 6 manufactured by Big Chemie”: PTFE “CERAFLOUR 981 (average particle diameter D50: 3 μm)” Surface conditioner 7 manufactured by BYK Chemie: Hydrophobic silica “AEROSI” RY200S "EVONIK Co. surface conditioner 8: hydrophilic silica" AEROSIL 130 "EVONIK Co.

[Conductive filler]
Conductive fine particles 1: Composite fine particles (dendritic fine particles in which 10 parts by weight of silver is coated on 100 parts by weight of core copper) Average particle diameter D50: 11.0 μm manufactured by Fukuda Metal Foil Powder Industry

[Black colorant]
Table 1 shows the black colorants.

[Example 1]
(4-layer structure; insulating transparent resin layer / black layer / metal layer (electrolytic copper foil) / conductive adhesive layer (I))
100 parts of thermosetting resin 2, 30 parts of conductive fine particles 1, 30 parts of curing agent 1 and 2 parts of curing agent 2 are charged into a container, and toluene: isopropyl alcohol (weight) so that the nonvolatile content concentration is 40% by weight. The mixed solvent of the ratio 2: 1) was added and stirred with a disper for 10 minutes to obtain a conductive adhesive. Next, the conductive adhesive was coated on the peelable sheet using a bar coater so that the dry thickness was 10 μm, and further dried in an electric oven at 100 ° C. for 2 minutes to thereby form a conductive adhesive layer ( I) was obtained.

Separately, methyl ethyl ketone was added to 20 parts of thermosetting resin 3, 1 part of surface conditioning agent 1 and 2 parts of surface conditioning agent 8 to prepare a nonvolatile content concentration of 30.0% by weight. The mixture was stirred with a disper and then dispersed with an Eiger mill (manufactured by Eiger Japan) using zirconia beads to obtain a dispersion. To 20 parts of the thermosetting resin (A1) in the resulting dispersion, 75 parts of photocurable resin 1, 5 parts of dipentaerythritol hexaacrylate (DPHA) as a monomer, and 5 parts of initiator 1 were added. A transparent resin composition was obtained by stirring with a disper for 10 minutes. This transparent resin composition was applied to the release surface of a transparent release sheet using a bar coater so that the dry thickness was 4 μm, and further dried in an electric oven at 100 ° C. for 3 minutes, and the exposure amount was 30 mJ / cm. ^A transparent resin layer was obtained by curing by irradiating ultraviolet rays under the condition of ² .
At this time, the spectral transmittance of the transparent resin layer measured using a spectrophotometer was 70% or higher in the entire wavelength region of 400 nm to 700 nm.

  Separately, methyl ethyl ketone was added to 100 parts of thermosetting resin 3 and 10 parts of black colorant 1 as a black colorant to prepare a nonvolatile content concentration of 30.0% by weight. The mixture was stirred with a disper and then dispersed with an Eiger mill (manufactured by Eiger Japan) using zirconia beads to obtain a dispersion. A black resin composition is prepared by adding 30 parts of curing agent 1 and 2 parts of curing agent 2 as a curing agent to 100 parts of the thermosetting resin (B1) in the obtained dispersion and stirring with a disper for 10 minutes. Obtained. By coating this black resin composition on the surface of the electrolytic copper foil with carrier on the side of the electrolytic copper foil using a bar coater to a dry thickness of 3 μm, and further drying in an electric oven at 100 ° C. for 3 minutes. A black layer was formed.

  After peeling off the carrier copper foil and pasting the conductive adhesive (I) on the exposed electrolytic copper foil surface, the transparent resin layer is pasted on the black layer surface to obtain "Releasable sheet / insulating transparent resin layer / black An electromagnetic wave shielding sheet consisting of “layer / metal layer (electrolytic copper foil) / conductive adhesive layer (I) / peelable sheet” was obtained.

[Examples 2 to 25, Comparative Examples 1 to 4]
An electromagnetic wave shielding sheet was obtained in the same manner as in Example 1 except that the type and blending amount (parts by weight) of the raw material in Example 1 were changed as shown in Tables 2 to 5.
However, Examples 1, 5 , 13, 14 , 20 and 34 are reference examples.

[Example 26]
(4-layer structure; insulating transparent resin layer / black layer / metal layer (metal vapor deposition layer) / conductive adhesive layer (I))
100 parts of thermosetting resin 2, 30 parts of conductive fine particles 1, 30 parts of curing agent 1 and 2 parts of curing agent 2 are charged into a container, and toluene: isopropyl alcohol (weight) so that the nonvolatile content concentration is 40% by weight. The mixed solvent of the ratio 2: 1) was added and stirred with a disper for 10 minutes to obtain a conductive adhesive. Next, the conductive adhesive was coated on the peelable sheet using a bar coater so that the dry thickness was 10 μm, and further dried in an electric oven at 100 ° C. for 2 minutes to thereby form a conductive adhesive layer ( I) was obtained.

Separately, methyl ethyl ketone was added to 20 parts of the thermosetting resin 3, 1 part of the surface conditioner 3 and 1 part of the surface conditioner 7 to prepare a nonvolatile content concentration of 30.0% by weight. The mixture was stirred with a disper and then dispersed with an Eiger mill (manufactured by Eiger Japan) using zirconia beads to obtain a dispersion. To 20 parts of the thermosetting resin (A1) in the obtained dispersion, 75 parts of photocurable resin 1, 5 parts of dipentaerythritol hexaacrylate (DPHA) as a monomer, and 5 parts of initiator 1 are added. Then, a transparent resin composition was obtained by stirring with a disper for 10 minutes. This transparent resin composition was applied to the release surface of a transparent release sheet using a bar coater so that the dry thickness was 4 μm, and further dried in an electric oven at 100 ° C. for 3 minutes, and the exposure amount was 30 mJ / cm. ^The insulating transparent resin layer was obtained by irradiating with ultraviolet rays and curing under the condition of ² .
At this time, the spectral transmittance of the transparent resin layer measured using a spectrophotometer was 70% or higher in the entire wavelength region of 400 nm to 700 nm.

  Separately, methyl ethyl ketone was added to 100 parts of thermosetting resin 3 and 10 parts of black colorant 1 as a black colorant to prepare a nonvolatile content concentration of 30.0% by weight. The mixture was stirred with a disper and then dispersed with an Eiger mill (manufactured by Eiger Japan) using zirconia beads to obtain a dispersion. Black resin composition by adding 30 parts of curing agent 1 and 2 parts of curing agent 2 as a curing agent to 100 parts of thermosetting resin (B1) in the obtained dispersion and stirring with a disper for 10 minutes. Got. The black resin composition was applied to a 0.1 μm thick copper vapor-deposited surface formed on the release-treated surface of a PET film using a bar coater so as to have a dry thickness of 3 μm, and further in an electric oven at 100 ° C. A black layer was formed by drying for 3 minutes.

  After pasting the transparent resin layer on the black layer surface, the copper-deposited PET film is peeled off, and the conductive adhesive (I) is pasted on the exposed copper-deposited surface to form a “peelable sheet / insulating transparent resin layer / An electromagnetic wave shielding sheet consisting of “black layer / metal layer (metal vapor deposition layer) / conductive adhesive layer (I) / peelable sheet” was obtained.

[Examples 27 to 29]
An electromagnetic wave shielding sheet was obtained in the same manner as in Example 26 except that the type and blending amount (parts by weight) of the raw material in Example 26 were changed as shown in Tables 2 to 5.

[Example 30]
(4-layer structure; insulating transparent resin layer / black layer / conductive adhesive layer (II) / conductive adhesive layer (I))
100 parts of thermosetting resin 2, 30 parts of conductive fine particles 1, 30 parts of curing agent 1 and 2 parts of curing agent 2 are charged into a container, and toluene: isopropyl alcohol (weight) so that the nonvolatile content concentration is 40% by weight. The mixed solvent of the ratio 2: 1) was added and stirred with a disper for 10 minutes to obtain a conductive adhesive. Next, the conductive adhesive is coated on the peelable sheet using a bar coater so that the dry thickness is 10 μm, and further dried in an electric oven at 100 ° C. for 2 minutes to have anisotropic conductivity. A conductive adhesive layer (I) was obtained.

Separately, methyl ethyl ketone was added to 20 parts of the thermosetting resin 3, 1 part of the surface conditioner 3 and 1 part of the surface conditioner 7 to prepare a nonvolatile content concentration of 30.0% by weight. The mixture was stirred with a disper and then dispersed with an Eiger mill (manufactured by Eiger Japan) using zirconia beads to obtain a dispersion. To 20 parts of the thermosetting resin (A1) in the obtained dispersion, 75 parts of photocurable resin 1, 5 parts of dipentaerythritol hexaacrylate (DPHA) as a monomer, and 5 parts of initiator 1 are added. Then, a transparent resin composition was obtained by stirring with a disper for 10 minutes. This transparent resin composition was applied to the release surface of a transparent release sheet using a bar coater so that the dry thickness was 4 μm, and further dried in an electric oven at 100 ° C. for 3 minutes, and the exposure amount was 30 mJ / cm. ^The insulating transparent resin layer was obtained by irradiating with ultraviolet rays and curing under the condition of ² .
At this time, the spectral transmittance of the transparent resin layer measured using a spectrophotometer was 70% or higher in the entire wavelength region of 400 nm to 700 nm.

  Separately, methyl ethyl ketone was added to 100 parts of thermosetting resin 3 and 10 parts of black colorant 1 as a black colorant to prepare a nonvolatile content concentration of 30.0% by weight. The mixture was stirred with a disper and then dispersed with an Eiger mill (manufactured by Eiger Japan) using zirconia beads to obtain a dispersion. Black resin composition by adding 30 parts of curing agent 1 and 2 parts of curing agent 2 as a curing agent to 100 parts of thermosetting resin (B1) in the obtained dispersion and stirring with a disper for 10 minutes. Got. Coating was performed using a bar coater so as to have a dry thickness of 3 μm, and further, drying was performed in an electric oven at 100 ° C. for 3 minutes to form a black layer.

  Separately, 100 parts of thermosetting resin 1, 850 parts of conductive fine particles, 30 parts of curing agent 1 and 2 parts of curing agent 2 are charged into a container, and toluene: isopropyl alcohol (40% by weight) so that the nonvolatile content concentration becomes 40% by weight. A mixed solvent having a weight ratio of 2: 1) was added and stirred with a disper for 10 minutes to obtain a conductive adhesive. Next, the conductive adhesive is coated on the peelable sheet using a bar coater so as to have a dry thickness of 3 μm, and further dried in an electric oven at 100 ° C. for 2 minutes to have isotropic conductivity. A conductive adhesive layer (II) was obtained.

  The conductive adhesive layers (I) and (II) are bonded together, the peelable sheet of the conductive adhesive layer (II) is peeled off, and the black layer and the transparent resin layer are bonded together. An electromagnetic wave shielding sheet comprising “resin layer / black layer / conductive adhesive layer (II) / conductive adhesive layer (I) / peelable sheet” was obtained.

[Example 31]
(Three-layer structure; insulating transparent resin layer / black layer / conductive adhesive layer (I))
100 parts of thermosetting resin 2, 450 parts of conductive fine particles 1, 30 parts of curing agent 1 and 2.0 parts of curing agent 2 are charged in a container, and toluene: isopropyl alcohol so that the nonvolatile content concentration is 40% by weight. A conductive solvent (I) was obtained by adding a mixed solvent (weight ratio 2: 1) and stirring with a disper for 10 minutes. Next, the conductive adhesive was coated on the peelable sheet using a bar coater so that the dry thickness was 10 μm, and further dried in an electric oven at 100 ° C. for 2 minutes to thereby form a conductive adhesive layer ( I) was obtained.

Separately, methyl ethyl ketone was added to 20 parts of the thermosetting resin 3, 1 part of the surface conditioner 3 and 1 part of the surface conditioner 7 to prepare a nonvolatile content concentration of 30.0% by weight. The mixture was stirred with a disper and then dispersed with an Eiger mill (manufactured by Eiger Japan) using zirconia beads to obtain a dispersion. To 20 parts of the thermosetting resin (A1) in the resulting dispersion, 75 parts of photocurable resin 1, 5 parts of dipentaerythritol hexaacrylate (DPHA) as a monomer, and 5 parts of initiator 1 were added. A transparent resin composition was obtained by stirring with a disper for 10 minutes. This transparent resin composition was coated on the transparent release surface of the peelable film using a bar coater so as to have a dry thickness of 4 μm, and further dried in an electric oven at 100 ° C. for 3 minutes, and the exposure amount was 30 mJ / cm. ^The insulating transparent resin layer was obtained by irradiating with ultraviolet rays and curing under the condition of ² .
At this time, the spectral transmittance of the transparent resin layer measured using a spectrophotometer was 70% or higher in the entire wavelength region of 400 nm to 700 nm.

  Separately, methyl ethyl ketone was added to 100 parts of thermosetting resin 3 and 10 parts of black colorant 1 as a black colorant to prepare a nonvolatile content concentration of 30.0% by weight. The mixture was stirred with a disper and then dispersed with an Eiger mill (manufactured by Eiger Japan) using zirconia beads to obtain a dispersion. A black resin composition is prepared by adding 30 parts of curing agent 1 and 2 parts of curing agent 2 as a curing agent to 100 parts of the thermosetting resin (B1) in the obtained dispersion and stirring with a disper for 10 minutes. Obtained. Coating was performed using a bar coater so as to have a dry thickness of 3 μm, and further, drying was performed in an electric oven at 100 ° C. for 3 minutes to form a black layer.

  By attaching a black layer and a transparent resin layer to the conductive adhesive layer (I), it consists of “peelable sheet / insulating transparent resin layer / black layer / conductive adhesive layer (I) / peelable sheet”. An electromagnetic wave shielding sheet was obtained.

[Example 32]
(4-layer structure; insulating transparent resin layer / black layer / metal layer (electrolytic copper foil) / conductive adhesive layer (I))
100 parts of thermosetting resin 2, 30 parts of conductive fine particles 1, 30 parts of curing agent 1 and 2 parts of curing agent 2 are charged into a container, and toluene: isopropyl alcohol (weight) so that the nonvolatile content concentration is 40% by weight. The mixed solvent of the ratio 2: 1) was added and stirred with a disper for 10 minutes to obtain a conductive adhesive. Next, the conductive adhesive was coated on the peelable sheet using a bar coater so that the dry thickness was 10 μm, and further dried in an electric oven at 100 ° C. for 2 minutes to thereby form a conductive adhesive layer ( I) was obtained.

Separately, methyl ethyl ketone was added to 100 parts of thermosetting resin 1, 1 part of surface conditioning agent 3 and 1 part of surface conditioning agent 7 to prepare a nonvolatile content concentration of 30.0% by weight. The mixture was stirred with a disper and then dispersed with an Eiger mill (manufactured by Eiger Japan) using zirconia beads to obtain a dispersion. A transparent resin composition is obtained by adding 10 parts of the curing agent 1 and 0.5 part of the curing agent 2 to 100 parts of the thermosetting resin (A1) in the obtained dispersion and stirring with a disper for 10 minutes. It was. The transparent resin composition is applied to the release surface of a transparent release sheet using a bar coater so that the dry thickness is 4 μm, and further dried in an electric oven at 100 ° C. for 3 minutes to thereby produce an insulating transparent resin. A layer was obtained.
At this time, the spectral transmittance of the transparent resin layer measured using a spectrophotometer was 70% or higher in the entire wavelength region of 400 nm to 700 nm.

  Separately, methyl ethyl ketone was added to 100 parts of thermosetting resin 3 and 10 parts of black colorant 1 as a black colorant to prepare a nonvolatile content concentration of 30.0% by weight. The mixture was stirred with a disper and then dispersed with an Eiger mill (manufactured by Eiger Japan) using zirconia beads to obtain a dispersion. A black resin composition is prepared by adding 30 parts of curing agent 1 and 2 parts of curing agent 2 as a curing agent to 100 parts of the thermosetting resin (B1) in the obtained dispersion and stirring with a disper for 10 minutes. Obtained. By coating this black resin composition on the surface of the electrolytic copper foil with carrier on the side of the electrolytic copper foil using a bar coater to a dry thickness of 3 μm, and further drying in an electric oven at 100 ° C. for 3 minutes. A black layer was formed.

  After peeling off the carrier copper foil and pasting the conductive adhesive (I) on the exposed electrolytic copper foil surface, the transparent resin layer is pasted on the black layer surface to obtain "Releasable sheet / insulating transparent resin layer / black An electromagnetic wave shielding sheet consisting of “layer / metal layer (electrolytic copper foil) / conductive adhesive layer (I) / peelable sheet” was obtained.

[Examples 33 to 34]
An electromagnetic wave shielding sheet was obtained in the same manner as in Example 32 except that the type and blending amount (parts by weight) of the raw material in Example 32 were changed as shown in Tables 2 to 5.

  Physical properties were measured and evaluated according to the following evaluation items. The results are shown in Tables 2-5.

<Test piece production>
The obtained electromagnetic wave shielding sheet was prepared to have a width of 60 mm and a length of 60 mm, and then the conductive adhesive layer (I) exposed by peeling off the peelable sheet on the conductive adhesive layer (I) side, A 125 μm thick polyimide film (“Kapton 500H” manufactured by Toray DuPont) was thermocompression bonded under the conditions of 150 ° C., 2 MPa, and 30 min. Next, the peelable sheet of the insulating transparent resin layer was peeled off and used as a test piece.

<Water contact angle of insulating transparent resin layer>
The water contact angle of the insulating transparent resin layer was measured using “automatic contact angle meter DM-501 / analysis software FAMAS” manufactured by Kyowa Interface Science Co., Ltd. with respect to the transparent resin layer surface of the test piece. The liquid method was used as the measurement method.

<85 ° glossiness>
The 85 ° glossiness of the test piece is measured from the insulating transparent resin layer side by BYK. The measurement was performed at a measurement angle of 85 ° using a micro-TRI-gloss surface gloss meter manufactured by GARDNER.

<L * value measurement>
The L * a * b * value of the test piece was measured from the insulating transparent resin layer side using a “color difference meter CR-400” manufactured by KONICA MINOLTA.

<Measurement of reflectance>
The reflectance of the test piece was measured from the insulating transparent resin layer side using a “UV-visible spectrophotometer (V-570)” manufactured by Jasco.

<Martens hardness>
The hardness of the electromagnetic shielding sheet was measured with a Fischer scope H100C (Fischer Instruments) type hardness tester. The measurement was performed on the insulating transparent resin layer surface of the test piece using a Vickers indenter (opening angle: 136 ° diamond square pyramid) in a constant temperature room at 25 ° C. with an entry depth of 1 μm and an entry time of 30 seconds. The values obtained by repeatedly measuring the same cured film surface at 10 random locations were averaged to obtain the Martens hardness value.

<Dynamic friction coefficient>
The dynamic friction coefficient of the test piece was measured with HEIDON (manufactured by Shinto Kagaku Co.). The measurement is performed by applying a weight of 100 g supported by three steel balls to the insulating transparent resin layer of the test piece and pulling on the insulating transparent resin layer at a speed of 60 cm / min. Was measured. The average value of the measured values at five different locations was taken as the dynamic friction coefficient.

<Visibility of printing>
The test piece was printed on the insulating transparent resin layer surface by screen printing using white ink (manufactured by Toyo Ink Co., Ltd.). The printing size was 5 points. A 60 W LED light was applied to the printing unit in the dark room, and a distance of 50 cm from the printing was opened at an angle of 20 °, 45 °, and 90 ° with respect to the horizontal plane, and it was confirmed whether the printing was visible. The evaluation criteria are as follows.

A: 20 °, 45 °, and 90 ° are all visible. Very good results.
○: Visible at 45 ° and 90 ° Good results.
Δ: Visible at 90 ° No problem in practical use.
×: Not visible at all angles Not practical

<Ink adhesion>
White silk screen ink “SS16 611 (manufactured by Toyo Ink)”, cyclohexanone and curing agent “SSUR110B (manufactured by Toyo Ink)” are mixed at a ratio of 10: 11: 1, and solid printing is performed on the surface of the insulating transparent resin layer of the test piece. And then dried in an oven at 130 ° C. for 10 minutes. A cross-cut test was performed on the printed surface according to JIS K 5600 to confirm the adhesion of the insulating layer of the ink coating to the insulating transparent resin layer. The evaluation criteria are as follows.

◎: No lattice separation is observed, which is a very good result.
○: Small peeling of the coating film at the intersection of cuts. Clearly not exceed 5%. It is a good result.
(Triangle | delta): The coating film has peeled partially and entirely along the cut line. 5% or more and less than 35% No problem in practical use.
×: Large peeling occurred on the entire surface. Not practical.

<Ink resistance>
The test piece was immersed in cyclohexanone for 10 minutes in an environment of 25 ° C. and 50%. The test piece was taken out, the solvent was removed with air, and the pencil hardness of the surface of the insulating transparent resin layer was measured according to JIS K 5600. The evaluation criteria are as follows.

A: H Very good result.
○: F Good results.
Δ: HB No problem in practical use.
×: HB or less Not practical.

<Insulation reliability>
The surface resistance value of the insulating transparent resin layer surface of the test piece was measured at an applied voltage of 10 V using a ring probe URS of “Hiresta UP” manufactured by Mitsubishi Chemical Analytech. The evaluation criteria are as follows.

A: 1 × 10 ⁹ Ω / □ or more Very good result.
○: 1 × 10 ⁷ Ω / □ or more and less than 1 × 10 ⁹ Ω / □ Good results.
Δ: 1 × 10 ⁵ Ω / □ or more and less than 1 × 10 ⁷ Ω / □ No problem in practical use.
×: Less than 1 × 10 ⁵ Ω / □ Not practical.

<Repulsive force>
An electromagnetic wave shielding sheet was prepared with a width of 1 cm and a length of 6 cm as a sample. The peelable sheet on the side of the conductive adhesive layer (I) was peeled off, and the exposed conductive adhesive layer (I) was prepared to have a width of 1 cm and a length of 6 cm, and a 25 μm thick polyimide (“Kapton 100H” Toray After being pressure-bonded under the conditions of 150 ° C., 2 MPa, 30 min, the peelable sheet on the insulating transparent resin layer side is peeled off, and the stiffness is applied under the test conditions described in JPCA-TMJ002 8.4.1. ) The value was measured. The results were evaluated according to the following criteria. If the repulsive force is too high, for example, when the FPC is bent and stored inside the electronic device, there is a demerit that the signal wiring of the FPC is burdened and may be disconnected.

A: Repulsive force is less than 50 mN / mm. Very good result.
○: Repulsive force is 50 mN / mm or more and less than 100 mN / mm. It is a good result.
(Triangle | delta): Repulsive force is 100 mN / mm or more and less than 150 mN / mm. There is no problem in practical use.
X: Repulsive force is 150 mN / mm or more. Not practical.

  From the results of Tables 2 to 5, the electromagnetic shielding sheet of the present invention, which is laminated in the order of the insulating transparent resin layer, the black layer, and the conductive adhesive layer (I) in the examples, An electromagnetic wave shielding sheet that has good ink adhesion and good ink resistance, excellent print visibility, low repulsive force, good production yield, and reduced production costs when the contact angle with water is 60 to 110 °. It was confirmed that it was possible to provide.

1 Insulating transparent resin layer 2 Black layer 3 Conductive adhesive layer (I)
4 isotropic conductive layer 5 printed wiring board 6 cover coat layer 7 insulating substrate 8 ground wiring 9 signal circuit 10 hole 11 electromagnetic wave shielding sheet

Claims (8)

The insulating transparent resin layer, the black layer, and the conductive adhesive layer (I) are laminated in this order,
An electromagnetic wave shielding sheet printed on the insulating transparent resin layer,
The insulating transparent resin layer is formed from a transparent resin composition containing a thermosetting resin (A1) and a curing agent (A2),
The thermosetting resin (A1) is any one selected from the group consisting of polyurethane resin, polyurethane urea resin, addition type polyester resin, polyamide resin, polyimide resin, and polyamideimide resin,
The surface of the insulating transparent resin layer has a contact angle with water of 70 to 100 °,
The thickness of the insulating transparent resin layer, Ri 1~12μm der,
An electromagnetic wave shielding sheet having an L * value in the L * a * b * color system measured from the insulating transparent resin layer side of 10 to 30 and an 85 ° gloss value of 15 to 50 . The surface resistance measured from the insulative transparent resin layer side, an electromagnetic wave shielding sheet according to claim 1 Symbol mounting, characterized in that ^{1 × 10 5 ~1 × 10 14} Ω / □ is. The insulating transparent resin layer, an electromagnetic wave shielding sheet according to claim 1 or 2, wherein the containing surface modifier. The said black layer is formed from the black resin composition containing a thermosetting resin (B1), a hardening | curing agent (B2), and a black colorant, The any one of Claims 1-3 characterized by the above-mentioned. The electromagnetic wave shielding sheet of description. The conductive adhesive layer (I) is formed from a conductive adhesive (i) containing a thermosetting resin (C1), a curing agent (C2), and a conductive filler. Item 5. The electromagnetic wave shielding sheet according to any one of Items 1 to 4 . Conductive adhesive layer (I) is an anisotropic conductive, electromagnetic wave shielding sheet according to any one of claims 1-5, characterized in that it comprises a conductive layer is further isotropically conductive. Claim 1-6 electromagnetic wave shielding sheet according to any one of the cover coat layer, and includes a wiring board having a signal wire and the insulating substrate, it has been printed on the insulating transparent resin layer of the electromagnetic wave shielding sheet A printed wiring board characterized by that. 8. The printed wiring board according to claim 7 , wherein the printing is white.