JP5214541B2 - Visible light transmitting electromagnetic wave absorbing film and visible light transmitting electromagnetic wave absorber using the same - Google Patents

Description

  The present invention relates to an inexpensive visible light transmissive electromagnetic wave absorbing film excellent in electromagnetic wave noise absorbing ability and a visible light transmissive electromagnetic wave absorber using the same.

  Electronic devices and communication devices such as mobile phones, personal computers and televisions; RFID (Radio Frequency Identification) systems using IC tags, contactless IC cards, etc .; Leakage of electromagnetic noise and intrusion prevention and information leakage in wireless LAN systems, etc. Shielding materials are used for the purpose of prevention, but shielding materials used for building windows, transparent partitions, and the like are required not only to have shielding properties but also to transmit visible light.

  Japanese Patent Laid-Open No. 9-148782 (Patent Document 1) forms an aluminum vapor deposition film on both surfaces of a plastic film and etches one aluminum vapor deposition film to form a large number of linear patterns with a width of 100 μm or less in a non-conductive state. In addition, a transparent electromagnetic wave absorbing shield material is proposed in which the other aluminum vapor deposition film is etched to form a mesh pattern with a diameter of 500 μm or less for each eye. The linear pattern is arranged in a plurality of different directions. This is considered to reduce the anisotropy of electromagnetic wave absorption ability. However, the line pattern and the mesh pattern specifically exemplified are regular, and the regular pattern cannot sufficiently absorb electromagnetic noise having various frequencies. In addition, forming such a fine pattern by etching is expensive and impractical.

Japanese Patent Laid-Open No. 9-148782

  Accordingly, an object of the present invention is to provide an inexpensive visible light transmitting electromagnetic wave absorbing film excellent in electromagnetic wave noise absorbing ability and a visible light transmitting electromagnetic wave absorber using the same.

  As a result of diligent research in view of the above object, the present inventor has various frequencies when irregularly forming a large number of parallel and intermittent linear marks on a metal thin film having visible light permeability formed on a plastic film. The inventors have found that a visible light-transmitting electromagnetic wave absorbing film capable of sufficiently absorbing electromagnetic noise can be obtained, and have arrived at the present invention.

That is, the first visible light transmitting electromagnetic wave absorbing film of the present invention comprises a plastic film and a substantially rectangular or square visible light transmitting metal thin film arranged in a large number in a state insulated from each other on at least one surface thereof. A plurality of substantially parallel and intermittent linear traces are formed in at least one direction with irregular length, width and interval on the metal thin film, and the linear traces have an average of 1 to 100 μm. At least one side direction of the metal thin film having a width and an average interval of 1 to 100 μm, 90% or more of the linear traces having a width in a range of 0.1 to 1,000 μm , and having the linear traces The electrical resistance at is 377 ± 250Ω. The metal thin film is preferably made of aluminum, nickel or an alloy thereof.

The second visible light transmissive electromagnetic wave absorbing film of the present invention comprises a plastic film and a visible light transmissive metal thin film having a large number of light transmitting openings provided on at least one surface thereof. A number of substantially parallel and intermittent linear traces are formed in at least one direction with irregular length, width and spacing, the linear traces having an average width of 1 to 100 μm and an average of 1 to 100 μm An electrical resistance in the direction of at least one side of the metal thin film having an interval, 90% or more of the linear traces having a width in the range of 0.1 to 1,000 μm, and the linear traces is 377 ± 250Ω It is characterized by being. The metal thin film is preferably made of aluminum, nickel or an alloy thereof.

Third visible light transmissive electromagnetic wave absorption film of the present invention, (1) and the plastic film, (2) provided on at least one surface of the plastic film, a visible light-transmissive metal thin film having a large number of Toruhikariyo opening If, (3) the and a substantially visible light-transmissive metal thin rectangular or square shape which are arranged so as to be insulated to KakuToru light within the opening in at least one surface of the plastic film, the magnetic At least one of the metal thin film having an opening for light and the rectangular or square metal thin film has a number of substantially parallel and intermittent linear traces at least in one direction with an irregular length, width and interval. The linear traces have an average width of 1-100 μm and an average interval of 1-100 μm, 90% or more of the linear traces have a width in the range of 0.1-1,000 μm, and The rectangular or square shape having the linear marks The electrical resistance in at least one side direction of the metal thin film is 377 ± 250Ω. The metal thin film having the opening and the rectangular or square metal thin film are preferably independently made of aluminum, nickel, or an alloy thereof.

  The first visible light transmissive electromagnetic wave absorber of the present invention is characterized in that a plurality of the visible light transmissive electromagnetic wave absorbing films are laminated with or without a space therebetween. The visible light transmitting electromagnetic wave absorber comprises at least one first visible light transmitting electromagnetic wave absorbing film (a) and at least one second visible light transmitting electromagnetic wave absorbing film (b). Is preferred. More preferably, the metal thin film of the first electromagnetic wave absorbing film (a) is made of a magnetic metal, and the metal thin film of the second electromagnetic wave absorbing film (b) is made of a nonmagnetic metal. Preferably, the magnetic metal is nickel and the non-magnetic metal is aluminum.

  The second visible light transmitting electromagnetic wave absorber of the present invention is (1) at least one selected from the group consisting of the first to third visible light transmitting electromagnetic wave absorbing films, and (2) (i) the above A first linear mark non-forming visible light transmitting electromagnetic wave absorbing film that is the same as the first visible light transmitting electromagnetic wave absorbing film except that the linear film is not formed on the metal thin film, (ii) A second linear mark non-visible visible light transmitting electromagnetic wave absorbing film which is the same as the second visible light transmitting electromagnetic wave absorbing film except that no linear marks are formed, and (iii) a metal thin film having the opening. And from the third linear-light-transmitting electromagnetic wave-absorbing film that is the same as the third visible-light-transmitting electromagnetic wave-absorbing film except that no linear traces are formed on the rectangular or square-shaped metal thin film. A space between at least one selected from the group Characterized in that formed by laminating not be or provided provided.

  The second visible light transmissive electromagnetic wave absorber comprises at least one second visible light transmissive electromagnetic wave absorbing film (b) and at least one first linear mark-free visible light transmissive electromagnetic wave absorber. The film (c) is preferred. The metal thin film of the second visible light transmitting electromagnetic wave absorbing film (b) is made of a nonmagnetic metal, and the metal thin film of the first linear mark non-forming visible light transmitting electromagnetic wave absorbing film (c) is made of a magnetic metal. Is more preferable. Preferably, the magnetic metal is nickel and the non-magnetic metal is aluminum.

  The visible light transmitting electromagnetic wave absorbing film of the present invention absorbs electromagnetic noise having various frequencies because a large number of parallel and intermittent linear marks are irregularly formed on a metal thin film having visible light transmittance. Excellent performance. Therefore, when a visible light transmitting electromagnetic wave absorbing film is placed on a building window, transparent partition, etc., electronic devices and communication devices that operate at high frequencies without blocking visible light; RFID systems, wireless LAN systems, etc. With respect to the communication system, it is possible to prevent electromagnetic noise and information leakage, or prevent electromagnetic noise from entering. The first and second visible light transmissive electromagnetic wave absorbers of the present invention, which are formed by laminating a plurality of visible light transmissive electromagnetic wave absorbing films, absorb much higher than the electromagnetic wave noise absorbing ability of each electromagnetic wave absorbing film. Has a synergistic effect.

It is a top view which shows the visible light transmissive electromagnetic wave absorption film by one Example of this invention. FIG. 2 is an AA cross-sectional view of FIG. FIG. 2 is an enlarged plan view showing a portion A in FIG. FIG. 3 is a BB end view of FIG. 1 (c). FIG. 2 is an enlarged end view showing a portion B ′ in FIG. 1 (d). It is sectional drawing which shows the visible light transmissive electromagnetic wave absorption film by another Example of this invention. It is a top view which shows partially the visible light transmissive electromagnetic wave absorption film by another Example of this invention. It is a top view which shows partially the visible light transmissive electromagnetic wave absorption film by another Example of this invention. It is a top view which shows partially the visible light transmissive electromagnetic wave absorption film by another Example of this invention. It is a top view which shows partially the visible light transmissive electromagnetic wave absorption film by another Example of this invention. It is a top view which shows partially the visible light transmissive electromagnetic wave absorption film by another Example of this invention. FIG. 5 is a CC end view of FIG. 4 (a). It is sectional drawing which shows the visible light transmissive electromagnetic wave absorption film by another Example of this invention. It is a top view which shows the visible light transmissive electromagnetic wave absorption film by another Example of this invention. FIG. 7 is a DD cross-sectional view of FIG. 6 (a). It is sectional drawing which shows the visible light transmissive electromagnetic wave absorption film by another Example of this invention. It is a top view which shows the visible light transmissive electromagnetic wave absorption film by another Example of this invention. FIG. 9 is an EE cross-sectional view of FIG. 8 (a). It is sectional drawing which shows the visible light transmissive electromagnetic wave absorption film by another Example of this invention. It is a perspective view which shows an example of the apparatus which forms a linear trace in a composite film. FIG. 11 is a plan view showing the linear trace forming apparatus in FIG. 10 (a). FIG. 11 is a sectional view taken along line FF in FIG. 10 (b). It is a partial enlarged plan view for demonstrating the principle in which the linear trace inclined with respect to the advancing direction of a plastic film is formed. FIG. 11 is a partial plan view showing the inclination angles of the pattern roll and the presser roll with respect to the plastic film in the linear trace forming apparatus of FIG. 10 (a). It is a fragmentary sectional view which shows schematically another example of the apparatus which forms a linear trace in a composite film. It is a perspective view which shows another example of the apparatus which forms a linear trace in a composite film. It is a perspective view which shows another example of the apparatus which forms a linear trace in a composite film. It is a perspective view which shows another example of the apparatus which forms a linear trace in a composite film. It is a perspective view which shows another example of the apparatus which forms a linear trace in a composite film. It is a top view which shows the state which has arrange | positioned the electrode on the test piece of an electromagnetic wave absorption film in order to measure sheet resistance. It is the schematic which shows the structure of the apparatus used for the measurement of return loss. It is a graph which shows the relationship between the frequency in the electromagnetic wave absorption film of Examples 1-3, and a return loss.

[1] Visible light transmissive electromagnetic wave absorbing film
(1) First Visible Light Transmitting Electromagnetic Wave Absorbing Film FIGS. 1 (a) to 1 (e) show an example of the first visible light transmitting electromagnetic wave absorbing film. In this electromagnetic wave absorbing film, a plurality of substantially square conductive composite film pieces 1a each having a visible light transmissive metal thin film 11a provided on a plastic film 10b are arranged on one surface of the plastic film 10a in a state of being insulated from each other. A large number of substantially parallel and intermittent linear marks 12 are formed on the entire surface of the metal thin film 11a of each conductive composite film piece 1a so as to be orthogonal. For the sake of explanation, in FIG. 1 (a), the length, width and interval of the linear marks 12 are exaggerated from the actual values. A transparent adhesive layer 14 is provided between the plastic film 10a and the plastic film 10b of the conductive composite film piece 1a. The plastic films 10a and 10b may be fused. The metal thin film 11a side of the conductive composite film piece 1a may be bonded to the plastic film 10a. The arrangement of the conductive composite film pieces 1a and the orientation of each conductive composite film piece 1a are not limited to the illustrated example, and may be random, for example.

  FIG. 2 shows another example of the first visible light transmitting electromagnetic wave absorbing film. In this electromagnetic wave absorbing film, instead of the conductive composite film piece 1a, a large number of substantially square-shaped visible light transmissive metal thin films 11a are directly provided on one surface of the plastic film 10a, and the transparent adhesive layer 14 is provided. Except for this, it is the same as that shown in FIG.

  The square-shaped metal thin film 11a having the linear trace 12 has an electric current of 377 ± 250Ω close to the characteristic impedance (377Ω) of free space in at least one, preferably both sides X and Y (see FIG. 1 (a)). It is formed to have resistance. Therefore, the first electromagnetic wave absorbing film has an excellent electromagnetic wave absorbing ability. This electrical resistance is preferably 377 ± 200Ω. However, the metal thin film 11a is not limited to a square shape, and may be a rectangular shape as long as it has an electrical resistance of 377 ± 250Ω in at least one side direction. The electric resistance of the metal thin film 11a can be adjusted by selecting the material, the thickness, the width, the interval, the length, and the like of the metal thin film 11a.

Electrical resistance is measured by the DC two-terminal method. The electric resistances R _X (Ω) and R _Y (Ω) in the side directions X and Y of the square metal thin film 11a are respectively the sheet resistances Rs _X (Ω / □) and Rs _Y (Ω / Equal to □). The electric resistances R _X (Ω) and R _Y (Ω) of the rectangular metal thin film 11a are respectively expressed by the formulas: R _X = Rs _X × L _X / L _Y [where L _X and L _Y are the sides of the metal thin film 11a, respectively. Represents the length in the directions X and Y], and the formula: R _Y = Rs _Y × L _Y / L _X

(a) Plastic film The resin forming the plastic films 10a and 10b is not particularly limited as long as it has insulating properties and sufficient strength, flexibility and processability. For example, polyester (polyethylene terephthalate, etc.), polyarylene sulfide (polyphenylene) Sulfide, etc.), polyamide, polyimide, polyamideimide, polyethersulfone, polyetheretherketone, polycarbonate, acrylic resin, polystyrene, polyolefin (polyethylene, polypropylene, etc.) and the like. Each of the plastic films 10a and 10b may have a thickness of about 10 to 100 μm.

(b) Visible light transmissive metal thin film The metal forming the visible light transmissive metal thin film 11a is not particularly limited as long as it has conductivity, but aluminum, copper, nickel, cobalt, silver, and alloys thereof from the viewpoint of corrosion resistance and cost. In particular, aluminum, nickel, and alloys thereof are preferable. The thickness of the metal thin film 11a is preferably 10 to 100 nm. If this thickness is less than 10 nm, the uniformity of the film is poor and the electromagnetic wave absorption ability is low. On the other hand, if it exceeds 100 nm, the visible light transmittance is poor. In the case of a nickel film, the thickness is more preferably 20 to 70 nm. In the case of an aluminum film, the thickness is more preferably 30 to 100 nm. The visible light transmissive metal thin film 11a is preferably a deposited film. In order to obtain an excellent electromagnetic wave absorbing ability, the total area ratio of the metal thin film 11a is preferably 70% or more, and more preferably 80% or more.

(c) Linear traces As can be seen from FIGS. 1 (c) and 1 (d), the micrographs are formed so that a number of substantially parallel linear traces 12 are perpendicular to the metal thin film 11a. Has been. For the sake of explanation, FIG. 1 (d) shows only the cut line cut at right angles to the orientation direction of the linear trace 12 in one direction, and exaggerates the depth of the linear trace 12 from the actual one. Yes. The lengths, widths, and intervals of the line marks 12 are irregular, and are irregularly arranged at various intervals from a very thin line mark to a very thick line mark. As shown in FIG.1 (d) and FIG.1 (e), the linear scar 12 has a non-conductive portion 121 penetrating through the metal thin film 11a and is relatively deep but not penetrating. In some cases, a high resistance portion 122 is formed. As shown in FIG. 1 (e), the bottom of the linear high resistance portion 122 preferably reaches a depth T ₂ corresponding to at least about 50% of the thickness T ₁ of the metal thin film 11, and about 70 It is more preferable that the depth T ₃ corresponding to% is reached. In this example, both the linear non-conducting portion 121 and the linear high resistance portion 122 are formed, but only one of them may be formed. That is, it can be seen that the irregular conductors separated by the linear non-conducting portion 121 and / or the linear high resistance portion 122 are irregularly connected. FIG. 1 (c) shows an example (G) of the connection part of the irregular conductor. Due to such irregular connection of the irregular conductors, electromagnetic noises of various frequencies can be efficiently absorbed.

  As will be described later, the linear marks 12 are formed by sliding a metal thin film on a plastic film with a pattern roll having random high hardness particles. Accordingly, as shown in FIGS. 1 (c) to 1 (e), not only the linear scars 12 are irregularly distributed, but the metal thin film is partially plastically deformed when the linear scars 12 are formed. The linear trace 12 not only has a tapered cross section, but also swells on both sides thereof, so the width and interval of the linear trace 12 differ depending on the position in the thickness direction. In order to enable an objective comparison, the width W of the linear trace 12 is obtained at a position intersecting the original surface S, and the interval I between the adjacent linear traces 12 is obtained at a position intersecting the original surface S. .

  As shown in FIG. 1 (e), there is a relatively shallow linear mark 12 ', but its width W' is significantly smaller than the width W. In addition, unusually wide linear traces may be formed. As a result of cross-sectional observation of the metal thin film 11a, it was found that the extremely narrow linear trace 12 'and the unusually wide linear trace were less than 10% of the total number of linear traces. Accordingly, the range of the width W may be obtained for 90% or more of the linear marks. As a result, it has been found that 90% or more of the linear marks 12 preferably have a width W in the range of 0.1 to 1,000 μm. The linear scar 12 having a width of less than 0.1 μm or more than 1,000 μm hardly contributes to electromagnetic wave noise absorption. The width W of 90% or more of the linear marks 12 is more preferably in the range of 0.1 to 100 μm, and most preferably in the range of 0.1 to 20 μm. Further, the interval I of 90% or more of the linear scar 12 is also preferably in the range of 0.1 to 1,000 μm, more preferably in the range of 0.1 to 100 μm, and most preferably in the range of 0.1 to 20 μm. preferable.

  The average width Wav and the average interval Iav of the linear marks 12 are values obtained by averaging the width and the interval in the above range of 0.1 to 1,000 μm, respectively. The average width Wav of the linear marks 12 is preferably 1 to 100 μm, more preferably 1 to 20 μm, and most preferably 1 to 10 μm. The average interval Iav of the linear marks 12 is preferably 1 to 100 μm, more preferably 1 to 20 μm, and most preferably 1 to 10 μm. When the average width Wav and the average interval Iav are less than 1 μm or more than 10 μm, respectively, sufficient electromagnetic noise absorption ability cannot be obtained.

  Since the length L of the linear mark 12 is determined by the sliding contact conditions (mainly the relative peripheral speed of the pattern roll and the film and the winding angle of the film on the pattern roll), the length L is largely determined unless the sliding contact conditions are changed. Are approximately the same (approximately equal to the average length). The average length Lav of the linear marks 12 is not particularly limited, and may be about 1 to 100 mm practically.

  3 (a) to 3 (d) show other examples of the pattern of the linear marks 12, respectively. The linear scar 12 is usually formed on a long composite film (a plastic film in which a metal thin film is formed on at least one surface). However, by appropriately setting the number of pattern rolls and the axial direction, FIG. As shown in FIG. 3 (d), various patterns of linear marks 12 having different orientation directions and numbers are obtained. In particular, as shown in FIG. 1 (c) and FIG. 3 (a) to FIG. 3 (c), when linear traces 12 are formed in a plurality of directions, an electromagnetic wave absorbing film having substantially no anisotropy in electromagnetic wave absorbing ability is obtained. can get.

(d) Fine hole FIGS. 4 (a) and 4 (b) show still another example of the first visible light-transmitting electromagnetic wave absorbing film. In this example, a large number of fine holes 13 are randomly provided in addition to the linear marks 12 in the metal thin film 11a. In the illustrated example, the fine hole 13 penetrates the metal thin film 11a, but the fine hole 13 does not necessarily penetrate the metal thin film 11a. The fine holes 13 are formed by pressing a pattern roll having high-hardness fine particles on the surface against the metal thin film as in the case of the linear marks 12. In order to form a through hole, the average diameter of the high-hardness fine particles needs to be at least about twice the thickness of the metal thin film. In practice, the average diameter of the high-hardness fine particles is sufficiently larger than the thickness of the metal thin film. .

The opening diameter D of the fine hole 13 is obtained at a position intersecting the original surface S. Depending on the thickness of the metal thin film 11a, generally, the opening diameter D of the fine hole 13 is preferably 90% or more in the range of 0.1 to 1,000 μm, and more preferably in the range of 0.1 to 500 μm. The average opening diameter Dav of the fine holes 13 is preferably in the range of 0.5 to 100 μm, and more preferably in the range of 1 to 50 μm. The upper limit of the average opening diameter Dav is more preferably 20 μm, and most preferably 10 μm. The average density of the fine holes 13 is preferably 500 pieces / cm ² or more, more preferably 1 × 10 ^{4 to} 3 × 10 ⁵ pieces / cm ² , and 1 × 10 ⁴ to 2 × 10 ⁵ pieces / cm ^2. Most preferred is cm ² .

(e) Protective Layer As shown in FIG. 5, a plastic protective layer 10c may be formed so as to cover the surface of the electromagnetic wave absorbing film having the visible light transmissive metal thin film 11a. The plastic protective layer 10c can be formed by adhering a plastic film to the surface of the electromagnetic wave absorbing film having the visible light transmissive metal thin film 11a by a heat laminating method or the like. The thickness of the plastic protective layer 10c is preferably 10 to 100 μm.

(f) Embossing In order to further improve the ability to absorb electromagnetic wave noise, the visible light-transmitting electromagnetic wave absorbing film may be subjected to a number of embossments such as a conical shape and a spherical shape. The emboss diameter and depth are each preferably 100 μm or more, more preferably 150 to 250 μm. The area ratio of embossing is preferably 20 to 60%.

(2) Second Visible Light Transmitting Electromagnetic Wave Absorbing Film FIGS. 6 (a) and 6 (b) show an example of the second visible light transmitting electromagnetic wave absorbing film of the present invention. In this electromagnetic wave absorbing film, a lattice-shaped conductive composite film 1b having a visible light-transmitting metal thin film 11b on a plastic film 10d and having a large number of light-transmitting openings 15 is used instead of the conductive composite film piece 1a. The electromagnetic wave absorbing film is the same as the electromagnetic wave absorbing film shown in FIGS. 1 (a) to 1 (e) except that it is provided on one surface of the plastic film 10a and the linear marks 12 are formed on the entire surface of the metal thin film 11b.

  FIG. 7 shows another example of the second visible light transmitting electromagnetic wave absorbing film. In this electromagnetic wave absorbing film, instead of the conductive composite film 1b, a lattice-like visible light transmissive metal thin film 11b is directly provided on one surface of the plastic film 10a, except that the transparent adhesive layer 14 is not provided. This is the same as the electromagnetic wave absorbing film shown in (a) and FIG. 6 (b).

  In order to achieve both excellent visible light transparency and electromagnetic wave absorption capability, the area ratio of the visible light transmissive metal thin film 11b is preferably 40 to 80%. The visible light transmissive metal thin film 11b is not limited to a lattice shape, and may have an arbitrary shape as long as it has a large number of light transmitting openings 15. The linear scar 12 may be the same as the first visible light transmitting electromagnetic wave absorbing film. The second visible light transmitting electromagnetic wave absorbing film may also have the fine holes 13, the plastic protective layer 10c and the emboss. These may be the same as those described for the first visible light transmissive electromagnetic wave absorbing film.

  Sheet resistance of the metal thin film 11b (electrical resistance in both sides of a sample obtained by cutting the electromagnetic wave absorbing film at an arbitrary size so that the metal thin film 11b is square). Measured by the DC two-terminal method. □ is preferable, and 377 ± 200Ω / □ is more preferable.

(3) Third Visible Light Transmitting Electromagnetic Wave Absorbing Film FIGS. 8 (a) and 8 (b) show an example of the third visible light transmitting electromagnetic wave absorbing film of the present invention. This electromagnetic wave absorbing film has a large number of conductive composite film pieces 1a and conductive composite films 1b, and each conductive composite film piece 1a is located in each opening 15 of the conductive composite film 1b and insulated. 1 is the same as the electromagnetic wave absorbing film shown in FIGS. 1 (a) to 1 (e). In the illustrated example, the linear trace 12 is formed on both the conductive composite film piece 1a and the conductive composite film 1b (hereinafter collectively referred to as “conductive composite films 1a and 1b”). May be formed only on one of the conductive composite films 1a and 1b.

  FIG. 9 shows another example of the third visible light transmitting electromagnetic wave absorbing film. In this electromagnetic wave absorbing film, instead of the conductive composite films 1a and 1b, a visible light transmissive metal thin film 11b having a square or rectangular visible light transmissive metal thin film 11a and an opening 15 on one surface of the plastic film 10a. Are directly provided, and are the same as those shown in FIGS. 8A and 8B except that the transparent adhesive layer 14 is not provided.

  In order to efficiently absorb electromagnetic wave noise, one of the metal thin films 11a and 11b may be formed of the magnetic metal, and the other may be formed of the nonmagnetic metal. A preferred combination is nickel and aluminum. In order to obtain an excellent electromagnetic wave absorbing ability, the total area ratio of the metal thin films 11a and 11b is preferably 70% or more, and more preferably 80% or more. The linear scar 12 may be the same as the first visible light transmitting electromagnetic wave absorbing film.

  The third visible light transmitting electromagnetic wave absorbing film may also have the fine holes 13, the plastic protective layer 10c and the emboss. These may be the same as those described for the first visible light transmissive electromagnetic wave absorbing film.

[2] Manufacturing method of visible light transmitting electromagnetic wave absorbing film
(1) Indirect method As shown in FIGS. 1 (a) to 1 (e), the first visible light transmitting electromagnetic wave absorbing film having the conductive composite film piece 1a includes a visible light transmitting metal thin film 11A and a plastic film. A conductive composite film 1A composed of 10B is formed, linear marks are formed on the conductive composite film 1A, and the conductive composite film 1A ′ with linear marks is cut to form a square or rectangular conductive composite film piece 1a. Then, the conductive composite film piece 1a can be manufactured by an indirect method in which it is disposed on at least one surface of the plastic film 10a and laminated.

  6 (a) and 6 (b), the second visible light transmissive electromagnetic wave absorbing film having the conductive composite film 1b is a conductive composite made of a visible light transmissive metal thin film 11B and a plastic film 10D. Form film 1B, form linear traces on conductive composite film 1B, cut conductive composite film 1B ′ with linear traces to form conductive composite film 1b having openings 15, and conductive composite film 1b made of plastic It can be manufactured by an indirect method in which the film 10a is disposed on at least one surface and laminated.

  The third visible light transmitting electromagnetic wave absorbing film having the conductive composite film piece 1a and the conductive composite film 1b as shown in FIG. It can manufacture by combining the manufacturing method of a transparent electromagnetic wave absorption film.

(a) Formation of conductive composite film
(i) Formation of metal thin film Metal deposition is performed by, for example, physical vapor deposition such as vacuum vapor deposition, sputtering, or ion plating, chemical vapor deposition such as plasma CVD, thermal CVD, or photo-CVD. It can be carried out.

(ii) Formation of linear marks
(ii-1) Linear trace forming apparatus Linear traces 12 oriented in a plurality of directions as shown in FIGS. 1 (c) and 3 (a) to 3 (c) are formed on a plastic film 10B (10D). The metal thin film 11A (11B) can be formed by using a device that has a large number of high-hardness fine particles on the surface and makes a plurality of pattern rolls having different axial directions in sliding contact with each other.

  FIG. 10 (a) to FIG. 10 (e) show an example of an apparatus for forming orthogonal linear marks as shown in FIG. 1 (c) and FIG. 3 (c). This linear mark forming apparatus is, in order from the upstream side, (1) a reel 21 for unwinding a composite film 1A (1B) in which a metal thin film 11A (11B) is formed on one surface of a plastic film 10B (10D), and (2) A plurality of guide rolls 22 and (3) a first having a large number of hard particles on the surface and arranged on the metal thin film 11A (11B) side in a direction different from the width direction of the composite film 1A (1B) The pattern roll 2a, (4) the first presser roll 3a disposed on the opposite side of the metal thin film 11A (11B) on the upstream side of the first pattern roll 2a, and (5) a large number of high-hardness fine particles. A second pattern roll 2b on the surface, disposed opposite to the first pattern roll 2a with respect to the width direction of the composite film 1A (1B) and on the metal thin film 11A (11B) side, (6) A second presser roll 3b disposed on the opposite side of the metal thin film 11A (11B) on the downstream side of the second pattern roll 2b, and (7) the first and Between the second pattern rolls 2a and 2b, electrical resistance measuring means 4a disposed on the metal thin film 11A (11B) side, and (8) on the downstream side of the second pattern roll 2b, the metal thin film 11A (11B ), (9) a plurality of guide rolls 23, and (10) a reel 24 for winding the composite film 1A ′ (1B ′) on which linear traces are formed. The pattern rolls 2a and 2b are supported by backup rolls 5a and 5b in order to prevent minute bending. The backup rolls 5a and 5b are preferably rubber rolls so as not to adversely affect the pattern rolls 2a and 2b.

As shown in FIG. 10 (c), the vertical direction of each presser roll 3a, 3b so that the metal thin film 11A (11B) of the composite film 1A (1B) is slidably contacted with each pattern roll 2a, 2b. The position is lower than the sliding contact position between the composite film 1A (1B) and each pattern roll 2a, 2b. Table respective presser rolls 3a while satisfying this condition, by adjusting the longitudinal position of the 3b, each pattern roll 2a of the metal thin film 11A (11B), as well as adjust the pressing force to 2b, the center angle theta ₁ The sliding contact distance can be adjusted.

  FIG. 10 (d) shows the principle that the linear marks 12a are formed obliquely with respect to the traveling direction of the composite film 1A (1B). Since the pattern roll 2a is inclined with respect to the traveling direction of the composite film 1A (1B), the movement direction (rotation direction) a of the hard fine particles on the pattern roll 2a and the traveling direction b of the composite film 1A (1B) Different. Therefore, as shown by the triangle X, if the hard fine particles at the point A on the pattern roll 2a come into contact with the metal thin film of the composite film 1A (1B) at any point in time and a mark B is formed, the hard fine particles will be formed after a predetermined time. Moves to point A ′ and trace B moves to point B ′. While the hard fine particles move from the point A to the point A ′, the traces are continuously formed, so that the linear trace 12 a extending from the point B ′ to the point A ′ is formed.

The directions of the first and second linear trace groups 12A and 12B formed by the first and second pattern rolls 2a and 2b and their crossing angles are determined by the composite film 1A (1B) of each pattern roll 2a and 2b. And / or the peripheral speed of each pattern roll 2a, 2b with respect to the traveling speed of the composite film 1A (1B). For example, when the peripheral speed a of the pattern roll 2a is increased with respect to the traveling speed b of the composite film 1A (1B), the linear trace 12a is represented by a line segment C′D ′ as indicated by a triangle Y in FIG. And 45 ° with respect to the traveling direction of the composite film 1A (1B). Similarly, changing the inclination angle theta ₂ of the pattern roll 2a in the width direction of the composite film 1A (1B), it is possible to change the peripheral speed a of the pattern roll 2a. The same applies to the pattern roll 2b. Therefore, by adjusting both the pattern rolls 2a and 2b, the direction of the linear marks 12a and 12b can be changed as illustrated in FIG. 1 (c) and FIG. 3 (c).

Since each pattern roll 2a, 2b is inclined with respect to the composite film 1A (1B), the composite film 1A (1B) receives a force in the width direction due to sliding contact with each pattern roll 2a, 2b, and may meander There is. In order to prevent meandering of the composite film 1A (1B), it is preferable to adjust the vertical position and / or angle of the presser rolls 3a and 3b with respect to the pattern rolls 2a and 2b. For example, if the crossing angle θ ₃ between the axis of the pattern roll 2a and the axis of the presser roll 3a is appropriately adjusted, a widthwise distribution of the pressing force is obtained so as to cancel the force in the widthwise direction, thereby preventing meandering. it can. Further, adjustment of the distance between the pattern roll 2a and the presser roll 3a also contributes to prevention of meandering.

  In order to prevent meandering and breakage of the composite film 1A (1B), the rotation direction of the first and second pattern rolls 2a and 2b is preferably the same as the traveling direction of the composite film 1A (1B).

As shown in FIG. 10 (b), each electrical resistance measuring means (roll) 4a, 4b has a pair of electrodes 41, 41 at both ends via an insulating portion 40, and a linear trace between the electrodes 41, 41. The electric resistance of the metal thin film 11A (11B) having 12a and 12b is measured. The electric resistance value measured by the electric resistance measuring rolls 4a and 4b is compared with the target electric resistance value, and the operating condition is adjusted according to the difference therebetween. The operating conditions to be adjusted are the traveling speed of the composite film 1A (1B), the rotational speed and inclination angle θ _{2 of} the pattern rolls 2a and 2b, the longitudinal position of the press rolls 3a and 3b, the distance from the pattern rolls 2a and 2b, And the inclination angle θ ₃ from the pattern rolls 2a and 2b.

As shown in FIG. 11, when the third presser roll 3c is provided between the pattern rolls 2a and 2b, the force with which the metal thin film 11A (11B) of the composite film 1A (1B) is pressed against the pattern rolls 2a and 2b increases. in addition to, the sliding distance of the metal thin film 11A (11B) is increased as represented by the center angle theta _1, linear scratches 12a, the depth and width of 12b increases. In addition, it contributes to the prevention of meandering of the composite film 1A (1B).

  FIG. 12 shows an example of an apparatus for forming linear traces oriented in three directions as shown in FIG. 3 (a). This apparatus is shown in FIGS. 10 (a) to 10 (e) except that a third pattern roll 2c arranged in the width direction of the composite film 1A (1B) is provided on the downstream side of the second pattern roll 2b. It is the same as the apparatus shown. The rotation direction of the third pattern roll 2c may be the same as or opposite to the traveling direction of the composite film 1A (1B). The third pattern roll 2c arranged in the width direction forms a linear mark 12c extending in the traveling direction of the composite film 1A (1B). The third presser roll 30b may be upstream or downstream of the third pattern roll 2c. Of course, an electrical resistance measuring roll 4c may be provided downstream of the third pattern roll 2c.

  FIG. 13 shows an example of an apparatus for forming linear traces oriented in four directions as shown in FIG. 3 (b). This apparatus is provided with a fourth pattern roll 2d between the second pattern roll 2b and the third pattern roll 2c, and a fourth presser roll 3d provided upstream of the fourth pattern roll 2d. This is the same as the apparatus shown in FIG. By slowing down the rotation speed of the fourth pattern roll 2d, the direction of the line mark 12a ′ (line segment E′F ′) is changed to the composite film 1A (1B) as shown by the triangle Z in FIG. Can be in the width direction.

  FIG. 14 shows another example of an apparatus for forming orthogonal linear marks as shown in FIG. 3 (c). This linear scar forming apparatus is basically different from the apparatus shown in FIGS. 10 (a) to 10 (e) in that the second pattern roll 32b is arranged in the width direction of the composite film 1A (1B). . Therefore, only the parts different from the apparatus shown in FIGS. 10 (a) to 10 (e) will be described below. The rotation direction of the second pattern roll 32b may be the same as or opposite to the traveling direction of the composite film 1A (1B). The second presser roll 33b may be on the upstream side or the downstream side of the second pattern roll 32c. As shown by the triangle Z in FIG. 10 (d), this apparatus sets the direction of the line mark 12a ′ (line segment E′F ′) to the width direction of the composite film 1A (1B), and FIG. 3 (c) Suitable for forming the linear traces shown.

  FIG. 15 shows an example of an apparatus for forming linear traces oriented in one direction as shown in FIG. 3 (d). This linear trace forming apparatus is the same as the apparatus shown in FIG. 14 except that it has only the pattern roll 42 arranged in the width direction of the composite film 1A (1B). The pattern roll 42 forms a linear mark 12b ′ extending in the traveling direction of the composite film 1A (1B). The presser roll 43 may be upstream or downstream of the pattern roll 42. Electrical resistance measuring rolls 44a and 44b may be provided upstream and downstream of the pattern roll 42.

(ii-2) Operating conditions As well as the inclination angle and crossing angle of the linear traces, the operating conditions for determining the depth, width, length and interval of these are the traveling speed of the composite film, the rotational speed of the pattern roll, and The inclination angle θ ₂ , the tension of the composite film (determined by the longitudinal position of the press roll, the distance from the pattern roll, the inclination angle θ ₃ from the pattern roll, etc.) and the like. The traveling speed of the composite film is preferably 5 to 200 m / min, and the rotational speed (peripheral speed) of the pattern roll is preferably 10 to 2,000 m / min. The inclination angle θ ₂ is preferably 20 ° to 60 °, and particularly preferably about 45 °. The tension of the composite film is preferably 0.05 to 5 kgf / cm width.

(ii-3) Pattern roll The pattern roll used in the linear trace forming apparatus is preferably a diamond roll described in JP-A-2002-59487. Since the width of the linear mark is determined by the particle size of the fine particles, 90% or more of the diamond fine particles preferably have a particle size in the range of 1 to 1,000 μm, and more preferably in the range of 10 to 200 μm. The diamond fine particles are preferably attached to the roll surface at an area ratio of 50% or more.

(iii) Formation of fine holes A large number of fine holes 13 can be formed in the metal thin film 11A (11B) by the method described in Japanese Patent No. 2063411. For example, a first roll in which a large number of fine particles having a Mohs hardness of 5 or more having sharp corners adhere to the surface (may be the same as the above-mentioned linear trace forming roll), and a smooth second roll pressed against the first roll The composite film 1A (1B) is passed through the gap with the metal thin film 11A (11B) facing the first roll. The average opening diameter, average area ratio, and depth of the fine holes 13 can be adjusted by the particle diameter and area ratio of the fine particles of the first roll, the pressing force, and the like.

(b) Cut of conductive composite film with linear traces Cut conductive composite film 1A ′ (1B ′) with linear traces by punching or the like to form a conductive composite film piece 1a having a substantially square or rectangular shape, and / or Alternatively, the conductive composite film 1b having the opening 15 is formed.

(c) Lamination The conductive composite film piece 1a and / or the conductive composite film 1b are laminated on the plastic film 10a by using the transparent adhesive layer 14 or by fusing.

(d) Formation of Protective Layer The plastic protective layer 10c can be formed by adhering the plastic film to the conductive composite film piece 1a and / or the conductive composite film 1b by a thermal laminating method or the like.

(e) Embossing After the above lamination process is performed and a protective layer 10c is provided as necessary, embossing is performed using a roll having a large number of conical or spherical protrusions.

(2) Direct method As shown in FIGS. 2, 7 and 9, the visible light transmitting electromagnetic wave absorbing film in which the visible light transmitting metal thin film 11a and / or 11b is directly provided on the plastic film 10a is: (a) plastic The metal thin film 11A (11B) is uniformly formed by vapor deposition on at least one surface of the film 10a, and the shape of the intended metal thin film 11a (square or rectangular shape) and / or the shape of the intended metal thin film 11b (for example, After applying a photoresist to form a (lattice) and etching after exposure, a linear mark 12 is formed, or (b) a portion of the plastic film 10a where the metal thin film 11a is not formed and / or the metal thin film 11b After the photoresist is applied to the portion not to be formed (the portion where the transparent opening 15 is to be formed), and after exposure, the metal thin film 11a and / or 11b is formed by vapor deposition, and the photoresist layer is removed The direct method of forming a linear scratches 12 can be formed. The formation of line marks, fine holes, protective layers, and embossing may all be the same as described above.

[3] Properties of Visible Light Transmitting Electromagnetic Wave Absorbing Film The first to third electromagnetic wave absorbing films having visible light transmissivity of the present invention have various frequencies due to a large number of intermittent irregular traces. Electromagnetic noise can be absorbed. In particular, the electromagnetic wave absorbing film in which the linear traces 12 are formed in a plurality of directions (preferably orthogonally) has little anisotropy in electromagnetic wave noise absorption capability and has excellent electromagnetic wave noise absorption capability.

[4] visible light transmissive electromagnetic wave absorber
(1) Structure
(a) First visible light transmissive electromagnetic wave absorber The first visible light transmissive electromagnetic wave absorber of the present invention is laminated with or without a plurality of visible light transmissive electromagnetic wave absorber films. Do it. When laminating without providing a space, it may be adhered as necessary. The combination of a plurality of visible light-transmitting electromagnetic wave absorbing films includes a plurality of first electromagnetic wave absorbing films, a plurality of second electromagnetic wave absorbing films, and a plurality of third electromagnetic waves. A case comprising an absorption film, a case comprising a combination of at least one first electromagnetic wave absorption film and at least one second electromagnetic wave absorption film, and at least one first electromagnetic wave absorption film and at least one sheet. A combination of a third electromagnetic wave absorbing film, a case of a combination of at least one second electromagnetic wave absorbing film and at least one third electromagnetic wave absorbing film, and at least one first electromagnetic wave absorbing film. It may be a combination of a film, at least one second electromagnetic wave absorbing film, and at least one third electromagnetic wave absorbing film.

  The first electromagnetic wave absorber is preferably composed of a combination of at least one first electromagnetic wave absorbing film and at least one second electromagnetic wave absorbing film. In order to efficiently absorb electromagnetic wave noise, it is preferable that one of the metal thin film 11a of the first electromagnetic wave absorbing film and the metal thin film 11b of the second electromagnetic wave absorbing film is formed of a magnetic metal and the other is formed of a nonmagnetic metal. More preferably, the metal thin film 11a is formed of a magnetic metal, and the metal thin film 11b is formed of a nonmagnetic metal. The magnetic metal and nonmagnetic metal may be the same as described above. A preferred combination is nickel and aluminum.

  In the case of an electromagnetic wave absorber in which a plurality of electromagnetic wave absorbing films are arranged in parallel, the distance between the electromagnetic wave absorbing films is preferably 0.2 to 10 mm, and more preferably 1 to 8 mm, in order to obtain excellent electromagnetic wave noise absorbing ability.

(b) Second visible light transmissive electromagnetic wave absorber The second visible light transmissive electromagnetic wave absorber of the present invention is (i) at least one selected from the group consisting of first to third electromagnetic wave absorbing films. (Ii) a first linear scar non-visible visible light transmitting electromagnetic wave absorbing film that is the same as the first electromagnetic wave absorbing film except that the metal thin film 11a is not formed with linear traces, and a linear trace on the metal thin film 1b. The second electromagnetic wave absorbing film that is the same as the second electromagnetic wave absorbing film except that no linear mark is formed, and the third film except that no linear mark is formed on the metal thin films 11a and 11b. At least one selected from the group consisting of a third linear scar-unformed visible light transmitting electromagnetic wave absorbing film which is the same as the electromagnetic wave absorbing film is laminated with or without a space in between. The sheet resistance of the metal thin film of the first to third linear scar-free visible light transmitting electromagnetic wave absorbing film is not particularly limited.

  The second electromagnetic wave absorber is preferably composed of a combination of at least one second electromagnetic wave absorbing film and at least one first linear mark non-forming electromagnetic wave absorbing film. In order to efficiently absorb electromagnetic wave noise, the metal thin film 11b of the second electromagnetic wave absorbing film is formed of a nonmagnetic metal, and the metal thin film 11a of the first electromagnetic film having no linear mark formed is formed of a magnetic metal. Is more preferable. The magnetic metal and nonmagnetic metal may be the same as described above. A preferred combination is nickel and aluminum. The interval between the electromagnetic wave absorbing films when a plurality of electromagnetic wave absorbing films are arranged in parallel may be the same as described above.

(2) Characteristics The visible light transmitting electromagnetic wave absorbing film slightly reflects and transmits electromagnetic noise, but the reflected and transmitted electromagnetic noise is different from the visible light transmitting electromagnetic wave absorbing film or the visible light transmitting electromagnetic wave that does not form a linear mark. Since it is absorbed by the absorbing film, the first and second visible light transmissive magnetic wave absorbers of the present invention have an extremely high electromagnetic noise absorption capability.

[5] Applications The first to third electromagnetic wave absorbing films and the first and second electromagnetic wave absorbers having visible light transmittance according to the present invention are electronic devices and communication devices such as mobile phones, personal computers, and televisions; RFID Suitable for prevention of leakage and intrusion of electromagnetic wave noise and information leakage in communication systems such as systems, wireless LAN systems, etc., and placed in electronic / communication equipment housings, building walls and windows, transparent partitions, etc. be able to. In particular, when it is arranged in a building window, a transparent partition or the like, it is possible to obtain electromagnetic wave absorption ability without blocking visible light.

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

Example 1
(1) Production of Composite Film A 50 nm thick aluminum layer was formed on one surface of a 12 μm thick biaxially stretched PET film by a vacuum deposition method to produce a composite film.

(2) Formation of linear traces Using the apparatus shown in FIG. 13, pattern rolls 2a to 2d electrodeposited with diamond fine particles having a particle size distribution of 50 to 80 μm and an aluminum layer on the pattern rolls 2a to 2d side By sliding the composite film 1B and appropriately setting the operating conditions (travel speed of the composite film, rotation speed and inclination angle θ _{2 of the} pattern rolls 2a to 2d _, film winding angle θ ₁ and tension of the composite film) Then, linear traces oriented in the four directions shown in FIG. 3 (b) were formed. The width of the linear trace of the obtained film is in the range of 0.5 to 5 μm, the average width of the linear trace is 2 μm, the interval of the linear trace is in the range of 2 to 10 μm, and the average interval of the linear trace Was 5 μm, and the average length of the line marks was 5 mm.

(3) Measurement of surface resistance The surface resistance was measured by the DC two-terminal method. As shown in Fig. 16, four copper electrodes (length 3cm x width 1cm) 6 are arranged on both ends of the test piece obtained by cutting the composite film formed with linear marks into 15cm x 15cm. The resistance value between the four pairs of electrodes 6 and 6 was measured and averaged to obtain the surface resistance. As a result, it was 377Ω / □.

(4) Production of electromagnetic wave absorbing film A composite film having linear traces was punched out to form a conductive composite film having a large number of square openings (5 cm on a side). A second electromagnetic wave absorption similar to that shown in FIGS. 6 (a) and 6 (b) except that a biaxially stretched PET film (thickness 16 μm) is fused on both sides of the conductive composite film and a plastic protective layer is provided. A film was prepared. The area ratio of the metal thin film of this electromagnetic wave absorbing film was 50%.

(5) Evaluation of electromagnetic wave noise absorbing ability The electromagnetic wave absorbing ability of the electromagnetic wave absorbing film was evaluated by the following method. As shown in FIG. 17, a device having a sample table 7 made of polystyrene foam, a transmitting antenna 81, a receiving antenna 82, and a network analyzer 8 to which the antennas 81 and 82 are connected is placed on the sample table 7 as a blank. The aluminum plate (length 60 cm x width 60 cm x thickness 5 mm) was irradiated with an electromagnetic wave of 1 to 6 GHz at an incident angle θ of 7 degrees at intervals of 0.25 GHz from an antenna 81 at a distance of 3 m, and the reflected wave at an antenna 82 , And the reflected power was measured by the network analyzer 8. The test piece S (length 60 cm × width 60 cm) of the electromagnetic wave absorbing film was placed on the sample stage 7, and the reflected power was measured in the same manner as the blank. Assuming that the reflected power of the blank is equal to the incident power, the reflection coefficient RC (ratio of the reflected power and the incident power measured for the electromagnetic wave absorbing film) is obtained, and the formula: R (dB) = -20log (1 / RC) The return loss R (dB) was obtained. The results are shown in FIG.

Example 2
A 30 nm thick nickel layer was formed on one side of a 16 μm thick biaxially stretched PET film by a vacuum deposition method to produce a composite film. The composite film was punched to form a large number of square-shaped composite film pieces (12.5 cm on a side. Composite film pieces 1a shown in FIGS. 1 (a) to 1 (e)). The sheet resistance of the composite film piece was 15Ω / □ in both side directions. Each composite film piece is sandwiched between two biaxially stretched PET films (thickness 16μm) and fused so that each composite film piece is placed in a state of being insulated from each other. A first linear mark non-formed visible light transmitting electromagnetic wave absorbing film (total area ratio of metal thin film 90%) which is the same as that shown in FIGS. 1 (a) and 5 was produced.

  A test piece (60 cm long x 60 cm wide) of the first linear mark-free visible light transmitting electromagnetic wave absorbing film and a second electromagnetic wave absorbing film test piece (60 cm long x horizontal) as in Example 1 60 cm) was evaluated for electromagnetic wave noise absorption ability. The results are shown in FIG.

Example 3
A 50 nm thick nickel layer was formed on one side of a 16 μm thick biaxially stretched PET film by a vacuum deposition method to produce a composite film. Except for using this composite film (sheet resistance: 10Ω / □), a first linear scar-free visible light transmitting electromagnetic wave absorbing film (total area ratio of metal thin film 90%) was prepared in the same manner as in Example 2. .

  Using the apparatus shown in FIG. 12, the composite film is slid in contact with the pattern rolls 2a to 2c electrodeposited with diamond fine particles having a particle size distribution of 50 to 80 μm, with the aluminum layer facing the pattern rolls 2a to 2c. By appropriately setting the conditions, linear traces oriented in the three directions shown in FIG. 3 (a) were formed. The width of the linear trace of the obtained film is in the range of 0.5 to 5 μm, the average width of the linear trace is 2 μm, the interval of the linear trace is in the range of 2 to 10 μm, and the average interval of the linear trace Was 5 μm, and the average length of the line marks was 5 mm. The sheet resistance of the composite film having the linear marks was 200Ω / □. A second electromagnetic wave absorbing film (metal thin film area ratio 70%) was produced in the same manner as in Example 1 except that this linear scar-forming composite film was used.

  A test piece (60 cm long x 60 cm wide) of the first linear scar-free visible light transmitting electromagnetic wave absorbing film and a test piece (60 cm long x 60 cm wide) of the second electromagnetic wave absorbing film. The laminate was evaluated for the ability to absorb electromagnetic noise. The results are shown in FIG.

  As is clear from FIG. 18, both the electromagnetic wave absorbing film of Example 1 and the electromagnetic wave absorbers of Examples 2 and 3 had an absorption capacity of 5 dB or more with respect to electromagnetic waves of 1 to 6 GHz. In particular, the electromagnetic wave absorbers of Examples 2 and 3 had an absorption capacity of 10 dB or more for electromagnetic waves of 1 to 6 GHz. The electromagnetic wave absorbing film of Example 1 has a maximum absorption amount of 43 dB at a frequency of 3.75 GHz, and the electromagnetic wave absorber of Example 2 has a maximum absorption amount of 36 dB at a frequency of 3.75 GHz. The electromagnetic wave absorber had a maximum absorption of 28 dB at a frequency of 4.0 GHz.

  Although the present invention has been described with reference to the accompanying drawings, the present invention is not limited thereto, and various modifications may be made within the scope of the technical idea of the present invention.

1a, 1b ... Cut conductive composite film with linear marks
10a, 10b, 10c, 10d ... Plastic film
11a, 11b ・ ・ ・ Metal thin film
12, 12a, 12a ', 12b, 12b', 12c, 12 '... linear marks
121 ・ ・ ・ Non-conductive part
122 ・ ・ ・ High resistance part
12A, 12B ... Linear traces
13 ... Micro hole
14 ... Transparent adhesive layer
15 ... Translucent opening
1A, 1B ... Conductive composite film
1A ', 1B' ... Conductive composite film with linear marks
11A, 11B ... Metal thin film
10B, 10D ... Plastic film
2a, 2b, 2c, 2d, 32b, 32c, 33b, 42 ... Pattern roll
3a, 3b, 3c, 3d, 30b, 43 ... Presser roll
4a, 4b, 4c, 4d, 44a, 44b ... Electric resistance measurement means (roll)
40 ・ ・ ・ Insulation part
41 ... Electrodes
5a, 5b, 35a ... Backup roll
21, 24 ... reel
22, 23 ... Guide roll

Claims (5)

A visible light transmissive electromagnetic wave absorbing film comprising a plastic film and a substantially rectangular or square visible light transmissive metal thin film arranged in a large number in a state of being insulated from each other on at least one surface thereof. Substantially parallel and intermittent linear traces are formed in at least one direction with irregular length, width and interval, the linear traces having an average width of 1 to 100 μm and an average interval of 1 to 100 μm 90% or more of the linear traces have a width in the range of 0.1 to 1,000 μm , and the electric resistance in at least one side direction of the metal thin film having the linear traces is 377 ± 250Ω. A visible light-transmitting electromagnetic wave absorbing film characterized by being. A visible light transmitting electromagnetic wave absorbing film having a plastic film and a visible light transmitting metal thin film having a plurality of light transmitting openings provided on at least one surface thereof, wherein the film is substantially parallel to the metal thin film. The intermittent traces are formed in at least one direction with irregular length, width and interval, and the linear traces have an average width of 1 to 100 μm and an average interval of 1 to 100 μm, 90% or more of the linear traces have a width in the range of 0.1 to 1,000 μm, and the electric resistance in at least one side direction of the metal thin film having the linear traces is 377 ± 250Ω. Visible light transmissive electromagnetic wave absorbing film. (1) each transparent plastic film, (2) provided on at least one surface of the plastic film, a visible light-transmissive metal thin film having a large number of Toruhikariyo opening, at least one surface of (3) the plastic film a visible light transmissive electromagnetic wave absorbing film substantially arranged so as to be insulated in use opening and a visible light-transmissive metal thin rectangular or square shape, having the Toruhikariyo opening At least one of the metal thin film and the rectangular or square metal thin film has a number of substantially parallel and intermittent line marks formed in irregular length, width and interval in at least one direction, The linear traces have an average width of 1 to 100 μm and an average interval of 1 to 100 μm, 90% or more of the linear traces have a width in the range of 0.1 to 1,000 μm, and have the linear traces The rectangular or square metal A visible light transmitting electromagnetic wave absorbing film, wherein an electrical resistance in at least one side direction of the thin film is 377 ± 250Ω. A visible light transmissive electromagnetic wave absorber comprising a plurality of visible light transmissive electromagnetic wave absorbing films according to any one of claims 1 to 3 laminated with or without a space therebetween. The visible light transmissive electromagnetic wave absorber according to claim 4, which is the same as the visible light transmissive electromagnetic wave absorber film according to claim 1 , except that (i) the linear scar is not formed on the metal thin film. A visible light transmissive electromagnetic wave absorbing film without a first linear mark, (ii) The same as the visible light transmissive electromagnetic wave absorbing film according to claim 2 , except that no linear mark is formed on the metal thin film. Non-linear trace non-visible visible light-transmitting electromagnetic wave absorbing film, and (iii) A metal thin film having the transparent opening and a rectangular or square metal thin film except that no linear trace is formed at least one selected from the third linear scratches non-forming group consisting of visible light transmissive electromagnetic wave absorbing film which is the same as the visible light transmissive electromagnetic wave absorption film according to claim 3, provided or a space is provided between It is characterized by being laminated without That the visible light transmissive electromagnetic wave absorber.

Images