JP2005057062A - Method of manufacturing electromagnetic-wave shielding body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an electromagnetic-wave shielding body which has a sufficient aperture ratio by narrowing a pattern without spoiling the visibility of a transparent board, and is improved simultaneously in both translucency and shielding properties. <P>SOLUTION: A black layer 34 is formed on the transparent glass 30A of high rigidity by drying out a black ink applied on the glass 30A, a conductive layer 35 having a prescribed pattern is formed on the black layer 34 by printing a conductive ink on the black layer 34, the exposed region 36 of the non-patterned part of the black layer exposing out of the conductive layer 35, is removed through a solvent 37 dissolving the black layer but undissolving the conductive layer, and then the conductive layer 35 is turned conductive through a thermal treatment to serve as an electromagnetic-wave shielding layer 31. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing an electromagnetic wave shield that shields electromagnetic waves radiated from a display screen such as a plasma display panel (hereinafter referred to as PDP) or a field emission display (hereinafter referred to as FED).

  There are various types of color televisions. In recent years, the color PDP 1 shown in FIG. The PDP 1 includes a panel main body (not shown) that is a light emitting unit, and a front panel 3 that is mounted on the front surface of the panel main body to protect the panel main body and has a function of shielding electromagnetic waves. The frame 2 is attached and has a feature that it is excellent in viewing angle, response speed, and sharpness.

As shown in FIG. 6, the front panel 3 has an electromagnetic wave shielding layer 31 and an antireflection treatment layer 32 sequentially laminated on the surface of the transparent substrate 30, and a near infrared absorption layer 33 is formed on the back surface of the transparent substrate 30. Yes. The transparent substrate 30 is formed with an electromagnetic wave shielding layer 31 that shields electromagnetic waves and suppresses adverse effects on surrounding electronic / electrical devices, human bodies, and the like. A method is employed in which a screen layer is formed by screen printing with a conductive ink on the surface of the substrate 30 and a transparent protective layer is screen-printed on the screen layer (see Patent Document 1).
JP-A-9-283777

  As described above, in the conventional electromagnetic wave shielding layer 31, the net layer is simply screen-printed with the conductive ink on the transparent substrate 30. However, as the pattern is formed, the electromagnetic wave shielding body 40 is clouded as a whole due to irregular reflection due to the pattern. There is a big problem of impairing the important visibility held by the electromagnetic wave shield 40. In recent years, a narrow width of 30 μm or less is required for the pattern, but a simple screen printing has a width of 100 μm or more, which is sufficient. The aperture ratio cannot be obtained. Furthermore, if a sufficient aperture ratio is to be ensured, the shielding performance is adversely affected, and there is a high possibility that both the translucency and the shielding performance cannot be achieved.

  The present invention has been made in view of the above, and it is possible to obtain a sufficient aperture ratio by narrowing the pattern without impairing the visibility of the transparent substrate, and at the same time satisfy both the light-transmitting property and the shielding property. It aims at providing the manufacturing method of the electromagnetic wave shield body which can do.

  In this invention, it is a manufacturing method of the electromagnetic wave shield body for solving the said subject, A black layer is formed in the single side | surface of a transparent substrate with the black ink containing the resin binder (A) and the coloring agent which exhibits black. Then, after forming a conductive layer in a desired pattern with a conductive ink containing a resin binder (B) different from the resin binder (A) contained in the black ink and a conductivity-imparting filler, a resin binder (A ) Is dissolved, but the exposed black layer is dissolved and removed with a solvent that does not dissolve the resin binder (B).

  The resin binder (A) is water-soluble (including acidic water and alkaline water), the resin binder (B) is water-insoluble, and the conductive layer is formed by a screen printing method. It is characterized by that.

  Here, as the transparent substrate in the claims, for example, an acrylic substrate or the like is used in addition to the tempered glass and the semi-tempered glass as long as the problem of distortion does not occur. In addition to the electromagnetic wave shielding layer, an antireflection treatment layer and a near infrared absorption layer can be appropriately formed on the transparent substrate. The electromagnetic wave shielding layer, the black layer, and the conductive layer are finally patterned into a lattice shape, a stripe shape, and other geometric patterns. There is no particular question as to whether the black layer is electrically conductive. Moreover, although the screen printing method is mainly used for pattern formation of the conductive layer, an offset printing method or the like can also be used. Furthermore, the electromagnetic wave shield according to the present invention is used as a part of the front panel of the PDP, but is not limited to this. For example, it can be used for other devices such as an FED. The PDP includes a DC type, an AC type, and a hybrid type, but is not particularly limited.

  According to the present invention, it is possible to obtain a good aperture ratio by narrowing the pattern without impairing the visibility of the transparent substrate, and to achieve both the light-transmitting property and the electromagnetic wave shielding property. is there.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. A method for manufacturing an electromagnetic wave shielding body in the present embodiment applies a black ink to a transparent transparent glass 30A as shown in FIGS. A black layer 34 is formed by drying, and a conductive layer 35 is printed on the black layer 34 with a conductive ink to form a pattern. The conductive layer 35 is dissolved by a solvent 37 that dissolves the black layer 34 but does not dissolve the conductive layer 35. After removing the exposed region 36 which is a non-pattern part of the black layer exposed from 35, heat treatment is performed to make the conductive layer 35 conductive, thereby forming the electromagnetic wave shield layer 31.

  The transparent glass 30A is made of, for example, a substantially rectangular glass plate that is reinforced and has excellent heat resistance and translucency. As this transparent glass 30A, for example, flat soda lime glass, low alkali glass, non-alkali glass, quartz glass, or the like is used. The thickness of the transparent glass is not particularly limited, but it is preferably thinner from the viewpoints of weight, visibility, and translucency. However, considering the mechanical strength, 0.05 to 5 mm, preferably 1. It is formed to a thickness of about 5 to 3 mm.

  The black layer 34 is composed of a black ink containing a resin binder (A) and a colorant such as a black pigment or dye, and the viscosity is adjusted by an appropriate solvent, and a curing agent, a crosslinking agent, a polymerization inhibitor, a leveling agent, and a dispersant. An antifoaming agent, a thickening agent, a suspending agent, an anti-aging agent, an ultraviolet absorber and the like are added as necessary, and are formed on the entire surface of one side of the transparent glass 30A.

  The resin binder (A) used here needs to be dissolved in an appropriate solvent that does not dissolve the resin binder (B) constituting the conductive ink described later. In consideration of workability and harmlessness, it is preferable to use an aqueous, acidic, neutral, alkaline, or hot water-based resin as a solvent for removing the exposed region 36 of the black layer 34, and such a water-soluble resin. Examples of the binder (A) include polyvinyl alcohol and an acid polymer having an acid value of about 80 to 500 mgKOH.

  As a component constituting the black layer, the resin component insoluble in the solvent for removing the exposed area is removed as a whole for the purpose of improving adhesion to the conductive layer, improving mechanical properties, improving durability, and improving reliability. It is possible to add to the extent which does not impair property, The addition amount in this case is 0.1-30 mass parts with respect to 100 mass parts of soluble resin, Preferably it is 0.5-20 mass parts, Preferably it is the range of 1-10 mass parts.

  The conductive layer 35 is formed by screen-printing a conductive ink containing a resin binder (B) different from the resin binder (A) contained in the black ink and a conductivity-imparting filler on the black layer 34. As the conductivity-imparting filler, it is preferable to use silver particles having excellent availability, cost, conductivity, and oxidation resistance. The conductive ink is adjusted to the optimum properties by adding a solvent or the like according to the processing method.

  Silver particles used for the conductive ink have an average particle diameter of 0.05 to 1 μm, preferably 0.07 to 0.8 μm. This is because when the average particle size is less than 0.05 μm, it tends to agglomerate, and it is necessary to add a large amount of a dispersant to suppress this agglomeration, and this dispersant is likely to adversely affect the conductivity. This is because if the particle diameter exceeds 1 μm, the drop of silver particles or the protrusion of the silver particles greatly affects the linearity of the pattern edge, making it difficult to obtain a fine pattern.

As the resin binder (B) constituting the conductive ink, it is necessary to use an insoluble resin in the solvent for removing the exposed region of the black layer. In particular, if the resin binder used in the black ink is water-soluble for the reasons described above, it is easy to make it water-insoluble by selecting a resin with relatively little polarity. For the purpose of improving the adhesion with the black layer, it is possible to add a soluble resin to such an extent that the insolubility is not impaired, and the amount added in this case is 100 parts by mass of the insoluble resin, It is 0.1-30 mass parts, Preferably it is 0.5-20 mass parts, More preferably, it is the range of 1-10 mass parts.
Furthermore, in order to improve the adhesion between the black layer and the conductive layer, it is preferable to have a combination having the same type of solvent in which both of them are dissolved. In order to do so, specifically, When an acrylic group-containing acid polymer having an acid value of 100 mgKOH is selected as the resin binder (A) for the black ink, it can be dissolved in a polar solvent such as methoxybutyl acetate and carbitol acetate, Examples of the resin binder (B) to be used include a combination of selecting water-insoluble polyvinyl butyral that is soluble in the above-described polar solvent.

  In the above, when the electromagnetic wave shield 40 is manufactured, first, a transparent glass 30A having a predetermined thickness is prepared (see FIG. 1), and black ink is applied and dried on the entire surface of one side of the transparent glass 30A. 34 is formed, and silver ink is screen-printed on the entire black layer 34 to pattern the conductive layer 35 (see FIG. 2). In forming the black layer 34, for example, a roll coater or a curtain coater can be used.

  The black layer 34 preferably has a thickness of 1 to 5 μm after drying. This is because, when the thickness of the black layer is less than 1 μm, the solvent absorption capability of the silver ink is insufficient, and the conductive pattern spreads in the width direction, in other words, the pattern is liable to occur. On the other hand, when the thickness exceeds 5 μm, the black layer covered with the conductive pattern is easily eroded from the lateral direction in the process of removing the exposed area of the black layer, and the pattern is significantly lost, and only the exposed area is stably stabilized. This is because it may be difficult to remove. As described above, the black layer 34 functions to absorb the solvent of the silver ink and effectively prevent the pattern from spreading in the width direction, that is, the sagging of the pattern.

  Next, the exposed region 36 of the black layer 34 exposed from the conductive layer 35 was removed with a predetermined removal solvent 37 by a method such as spraying or dipping (see FIG. 3), and the black layer 34 was patterned in the same manner as the conductive layer 35. Form an intermediate. When the intermediate is formed in this way, the intermediate is put in an oven or the like and heat-treated at a temperature of 200 to 600 ° C., and the heat treatment is maintained for a predetermined time to contract and make the conductive layer 35 conductive. By cooling and taking out from the oven, a translucent electromagnetic wave shield 40 can be obtained (see FIG. 4).

  The line width of the pattern in the electromagnetic wave shielding layer 31 is preferably 2 to 40 μm. This is because, when the line width is less than 2 μm, the electromagnetic wave shielding characteristics deteriorate, and there is a possibility that the pattern may be disconnected. Conversely, when the line width exceeds 40 μm, the translucency is obtained. This is because it is necessary to widen the line spacing in order to maintain the transparency, and it becomes difficult to achieve both transparency and shielding characteristics, and the pattern itself can be recognized with the naked eye, which may deteriorate the visibility of the display body. .

  When the electromagnetic wave shielding body 40 is manufactured, the near-infrared absorbing layer 33 is adhered to the back surface of the transparent glass 30A with a transparent adhesive, and the non-reflective treatment layer 32 is adhered to the electromagnetic wave shielding layer 31 with a transparent adhesive. Can be obtained. The antireflection treatment layer 32 can be omitted as appropriate if not necessary. Moreover, it is also possible to affix the film material in which the near-infrared absorption layer 33 and the antireflection process layer 32 were formed.

  According to the above, the conductive layer 35 is not directly formed on the transparent glass 30A, but the achromatic black layer 34 that absorbs the light is interposed between the transparent glass 30A and the conductive layer 35. 40 is not clouded by irregular reflection. Therefore, the visibility required for the electromagnetic wave shield 40 can be remarkably improved. Further, since the exposed region 36 of the black layer 34 exposed from the conductive layer 35 is removed and the electromagnetic wave shielding layer 31 is patterned, it is necessary to position and overlap the patterned black layer 34 and the conductive layer 35 with high accuracy. There is no. As a result, the pattern line width can be reduced to 40 μm, preferably 30 μm, and more preferably about 20 μm, and the line width of the pattern, which was impossible with the conventional method, can be reduced.

  In addition, since the conductive layer 35 made of highly conductive silver is formed, good shielding properties can be obtained, and heat treatment in an air atmosphere is possible. In addition, since the conductive layer 35 is formed not by a photolithography method but by a highly productive screen printing method, it is possible to form the conductive layer 35 only in a necessary portion, thereby eliminating waste of materials. . Further, since the intermediate composed of the black layer 34 and the conductive layer 35 is heat-treated, when a thermosetting resin binder is used as the black layer, the reliability is improved by crosslinking, and the conductivity of the conductive layer 35 is greatly improved. I can expect.

(Example 1)
A composition (blending ratio 5: 1) comprising an alkali-soluble resin (acid value 105 mgKOH) of an acrylic group-containing styrene-maleic anhydride copolymer system and polyethylene glycol dimethacrylate (crosslinkable monomer) is used as a resin binder (A), To 100 parts by mass of resin binder (A), 3 parts by mass of “Perhexa 25B” manufactured by NOF Corporation as a crosslinking agent, 10 parts by mass of graphitized carbon as a black colorant, and 300 parts by mass of methoxybutyl acetate as a solvent for adjusting viscosity A black ink was prepared, and a black layer having a thickness of 3 μm (after drying) was formed on the entire surface of one side of a semi-tempered soda lime glass having a thickness of 2.5 mm, a length of 582 mm and a width of 982 mm using a roll coater.

  Polyvinyl butyral “S-REC BM-SZ” (trade name, manufactured by Sekisui Chemical Co., Ltd.) is used as a resin binder (B), and about 100 parts by mass of resin binder (B), approximately spherical silver powder having a weight average particle diameter of 0.3 μm is 1500 mass. Part, 400 parts by mass of methoxybutyl acetate as a viscosity adjusting solvent was prepared to produce a conductive ink, and after forming a conductive layer on the black layer by screen printing, drying was performed in an oven at 100 ° C. for 30 minutes. It was. The screen used for printing uses a mesh of SUS # 380, has an emulsion thickness of 10 μm, and has a grid-like opening pattern with a line width of 20 μm, a pitch of 300 μm, and a bias of 15 ° in a rectangular area of 530 mm × 930 mm. In addition, an opening (in communication with the internal lattice pattern) for forming a grounding electrode portion having a width of 25 mm is provided on the entire outer periphery.

Next, the exposed region of the black layer was removed by a spray method using a 2.38% TMAH aqueous solution, and heat treatment was performed in an oven at 250 ° C. for 60 minutes to obtain an electromagnetic wave shield by the production method of the present invention.
The obtained electromagnetic shielding body was cut into a length of 20 cm and a width of 20 cm, and the electromagnetic wave attenuation rate (dB) in the frequency range of 0.1 MHz to 1 GHz was measured by the Advantest method to evaluate the electromagnetic shielding effect in the frequency range. As a result, the electromagnetic wave shielding property exceeding 50 dB over the entire region was shown. Furthermore, when the spectral transmittance of visible light (wavelength of 400 to 700 nm) was measured for the obtained electromagnetic wave shield, it was found that it exhibited very excellent translucency exceeding 80% over the entire region. When the visibility of the display image was evaluated by visual inspection after installing the 5 mm gap on the front of the panel body as the front panel of the PDP with the electromagnetic shielding pattern inside, there was no unevenness or mesh at all. The contrast was remarkably high and a very good image was obtained.

(Comparative Example 1)
In Example 1, the formed black layer is not formed, and the electromagnetic wave shielding is performed by a manufacturing method in which the conductive layer is formed directly on the transparent glass using the conductive ink and apparatus used in Example 1 under the same conditions and heat-treated. Got the body.

  The electromagnetic wave shielding property was good at 40 dB or more over the entire region, but the pattern was remarkably widened, the translucency was 40% or less, and the visibility was very poor because unevenness and mesh were seen over the entire surface. .

It is a schematic cross section explanatory drawing which shows the transparent glass in embodiment of the manufacturing method of the electromagnetic wave shield which concerns on this invention. It is a schematic cross-section explanatory drawing which shows the state which forms a black layer in the transparent glass in embodiment of the manufacturing method of the electromagnetic wave shield which concerns on this invention, and forms a conductive layer on this all black layer. It is a schematic cross section explanatory drawing which shows the state which removes the exposed area | region of the black layer in a solvent in embodiment of the manufacturing method of the electromagnetic wave shield which concerns on this invention. It is a schematic cross-section explanatory drawing which shows the electromagnetic wave shield body by which the electromagnetic wave shield layer in embodiment of the manufacturing method of the electromagnetic wave shield body which concerns on this invention was made into the conductive pattern. It is a whole perspective explanatory view showing a plasma display. It is a schematic cross-section explanatory drawing which shows a front panel.

Explanation of symbols

1 PDP
2 Frame 3 Front panel 30 Transparent substrate 30A Transparent glass (transparent substrate)
31 Electromagnetic wave shielding layer 32 Non-reflective treatment layer 33 Near infrared absorption layer 34 Black layer 35 Conductive layer 36 Exposed area 37 Solvent 38 Spray 40 Electromagnetic wave shield

Claims (3)

A black layer is formed on one side of the transparent substrate with the resin binder (A) and a black ink containing a black colorant, and a resin binder (A) different from the resin binder (A) contained in the black ink is formed thereon. After the conductive layer is formed into a desired pattern with a conductive ink containing B) and a conductivity-imparting filler, the exposed black layer is dissolved with a solvent that dissolves the resin binder (A) but not the resin binder (B). A method for producing an electromagnetic wave shielding body, comprising removing the electromagnetic wave shielding body. 2. The method for producing an electromagnetic wave shielding body according to claim 1, wherein the resin binder (A) is water-soluble and the resin binder (B) is water-insoluble. The method for producing an electromagnetic wave shielding body according to claim 1 or 2, wherein the conductive layer is formed by a screen printing method.

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