JP2008251690A - Electromagnetic wave suppressing paper and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic wave suppressing paper with improved conductivity and heat resistance of conductive paint, without causing degradation in the electromagnetic wave absorbing performance. <P>SOLUTION: The electromagnetic wave suppressing paper is coated, in a thickness range of 20-100 μm, with a conductor resin layer containing copper alloy whose main component is copper, acrylic resin with the glass transition temperature being 50°C or lower and a super-high molecular weight 300,000-1,000,000, and acryl resin whose glass transition temperature being 50°C or higher. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electromagnetic wave suppression paper that is easy to process and handle and has excellent electromagnetic wave suppression properties (electromagnetic wave shielding properties), and provides an electromagnetic wave suppression paper that maintains its performance even at a use temperature of 85 ° C. Furthermore, it is related with the manufacturing method of electromagnetic wave suppression paper.

  In recent years, digitalization has progressed in various fields, and high-speed and high-integration has been achieved in the control field of various information communication, medical equipment, precision equipment, etc., and in daily life goods such as electrical appliances and automobiles. Electronic devices are widely used. In particular, as the performance of electronic devices such as computers, mobile phones, and flat-screen TVs has improved dramatically, electromagnetic waves leaking from various electronic devices not only malfunctioning other electronic devices, but also have a negative impact on people's health. Therefore, countermeasures against electromagnetic interference have become indispensable.

  Conventionally, a variety of electromagnetic wave absorbing materials that prevent reflection of these radio waves and electromagnetic waves and change the electromagnetic wave energy to heat energy have been used as countermeasures. Note that the metal plate generally reflects electromagnetic waves on its surface regardless of the thickness, and has no absorption capability. Among them, sheet-shaped electromagnetic wave absorbers are often used in digital devices and the like.

  Plastics, metals, rubbers, films, fibers, and composites thereof are used for the base material (base material) of the electromagnetic wave absorber, but there are problems such as being heavy, thick, and difficult to process. Therefore, the applicant is studying a light, thin, and easy-to-process electromagnetic wave suppressor based on paper and coated with a copper-based conductive paint on the surface of the paper.

  As the conductive paint, there is a conductive paint mainly composed of an ultra high molecular weight special polymer and mixed with copper and special alloy particles. However, copper-based conductive paints are liable to be oxidized in an environment such as heat and temperature, and therefore have a problem that they tend to cause environmental resistance and conductivity deterioration (decrease in electromagnetic wave absorption performance). Such a problem is that the temperature at which the electromagnetic wave absorber is used reaches an unexpectedly high temperature, and deteriorates the electromagnetic wave absorption performance that was high at room temperature. For example, in electronic devices such as personal computers, the amount of heat generated by the CPU increases when the load on the CPU increases as the amount of processing data increases. In microcomputers and the like that are frequently used in automobile control systems, the temperature at which they are used rises. A decrease in electromagnetic wave absorption performance at high temperatures is a serious safety issue because it compromises the normal operation of the microcomputer.

  In order to solve this problem, the following techniques have been conventionally proposed (for example, see Patent Documents 1 to 7).

  That is, the technique of Patent Document 1 treats electrolytic copper powder with an organic carboxylic acid, the technique of Patent Document 2 treats copper powder with a coupling agent, and the technique of Patent Document 3 coats copper powder with silver. The technique of patent document 4 coats copper powder with organic titanate, the technique of patent document 5 coats copper powder with organic aluminum, and the technique of patent document 6 plating copper powder with solder. In other words, the technique of Patent Document 7 proposes coating copper powder with copper oxide.

JP 60-258273 A Japanese Patent Laid-Open No. 60-30200 JP 60-243277 A JP 59-174661 A JP 59-179671 A Japanese Patent Laid-Open No. 57-113505 JP 60-35405 A

  By subjecting the copper powder to the above-described treatment, a certain degree of effect can be obtained with respect to environmental resistance and prevention of deterioration of conductivity. However, the copper powder is not good in rust prevention, and the conductivity and heat resistance of the conductive paint are not sufficient. In particular, the decrease in electromagnetic wave absorption performance was remarkable.

  The present invention has been made based on the above-mentioned background, and its object is to eliminate the drawbacks of the conventional copper powder for conductive paints and conductive paints and to reduce electromagnetic wave absorption performance. The object is to provide an electromagnetic wave suppression paper with improved conductivity and heat resistance of the conductive paint.

  The present invention pays attention to the above-mentioned problems and intends to solve the above-mentioned problems by repeatedly investigating applying a conductive paint to a paper substrate. That is, the electromagnetic wave suppression paper according to the present invention comprises a copper alloy mainly composed of copper and an ultrahigh molecular weight acrylic having a glass transition temperature of 50 ° C. or lower and a molecular weight of 300,000 to 1,000,000 on at least one side of a substrate. A conductive resin layer containing an epoxy resin and an acrylic resin having a glass transition temperature of 50 ° C. or higher is coated with a thickness of 20 to 100 μm.

  In the electromagnetic wave suppression paper according to the present invention, the conductive resin layer includes a copper alloy containing copper as a main component and an ultra high molecular weight acrylic resin having a glass transition temperature of 50 ° C. or less and a molecular weight of 300,000 to 1,000,000. The case where it forms by coating the coating liquid which mixed the acrylic resin whose glass transition temperature is 50 degreeC or more with the electroconductive paint which made it a main body on at least one side of the said base material is included.

  In the electromagnetic wave suppression paper according to the present invention, the conductive resin layer has, on at least one surface of the base material, a copper alloy containing copper as a main component and a glass transition temperature of 50 ° C. or less and a molecular weight of 300,000 to 1,000,000. In the case where it is formed by applying and drying a conductive coating mainly composed of an ultra-high molecular weight acrylic resin, and further applying and drying a liquid containing an acrylic resin having a glass transition temperature of 50 ° C. or higher. There may be.

  In the electromagnetic wave suppression paper according to the present invention, the conductive resin layer is an acrylic resin having a glass transition temperature of 50 ° C. or higher with respect to 100 parts by mass in terms of solid content of the conductive paint. It is preferable that it consists of the composition which added the mass part. Both the conductivity and heat resistance of the conductive resin layer can be sufficiently satisfied.

  In the electromagnetic wave suppression paper according to the present invention, it is preferable that an overcoat layer is provided on the conductive resin layer. The surface roughness is reduced and the occurrence of creases is suppressed. In electronic equipment applications, if the conductive resin layer is rough, or if the powder of the conductive resin layer falls off when it is folded, a short circuit or insulation will occur, adversely affecting the electrical circuit, resulting in a rough surface. It is preferably reduced and has breakability.

  In the electromagnetic wave suppression paper according to the present invention, it is preferable that the conductive resin layer is formed on one surface of the substrate and the pressure-sensitive adhesive layer is formed on the other surface. By providing the pressure-sensitive adhesive layer, the electromagnetic wave suppression paper according to the present invention can be easily attached to a device that generates an electromagnetic wave such as an electronic device.

  In the electromagnetic wave suppression paper according to the present invention, it is preferable that a release paper is stuck on the surface of the pressure-sensitive adhesive layer. By attaching the release paper, the electromagnetic wave suppression paper can be provided in the form of label paper.

  In the electromagnetic wave suppression paper according to the present invention, the base material may be acid paper, neutral paper, alkaline paper, incombustible paper, flame retardant paper, glass paper, single-sided or double-sided coated paper, synthetic paper, or plastic film. preferable. The substrate is not limited to a paper substrate. Here, the glass paper is a paper-like structure made of glass fibers. Manufacture is possible by papermaking as well as paper base. Also, it can be light and bulky.

  In the electromagnetic wave suppression paper according to the present invention, radio waves at a frequency of 2.4543 GHz after heat treatment at 85 ° C. for 1000 hours, measured using the S-parameter method (S-21), which is a near-field radio wave absorption material measurement method. It is preferable that both the absorption rate [dB] and the influence degree [dB] on the circuit are −6 dB or less.

  The method for producing an electromagnetic wave suppression paper according to the present invention is mainly composed of a copper alloy mainly composed of copper and an ultrahigh molecular weight acrylic resin having a glass transition temperature of 50 ° C. or lower and a molecular weight of 300,000 to 1,000,000. An electrically conductive paint is mixed with an acrylic resin having a glass transition temperature of 50 ° C. or higher to prepare a coating solution, and the coating solution is applied to at least one side of the substrate, and the temperature is in the range of 20 to 70 ° C. The conductive resin layer is formed to a thickness of 20 to 100 μm by drying. The electromagnetic wave suppressing effect is exhibited without deteriorating the ultrahigh molecular weight acrylic resin, and the drying time is shortened to improve the productivity.

  The method for producing an electromagnetic wave suppression paper according to the present invention is mainly composed of a copper alloy mainly composed of copper and an ultrahigh molecular weight acrylic resin having a glass transition temperature of 50 ° C. or lower and a molecular weight of 300,000 to 1,000,000. A conductive paint is applied to at least one surface of the substrate, dried in a temperature range of 20 to 70 ° C., and further coated thereon with an acrylic resin-containing liquid having a glass transition temperature of 50 ° C. or higher. The conductive resin layer is formed to a thickness of 20 to 100 μm by drying in a temperature range of ˜70 ° C.

  A conductive coating mainly composed of a copper alloy containing copper as a main component and an ultrahigh molecular weight acrylic resin having a glass transition temperature of 50 ° C. or lower and a molecular weight of 300,000 to 1,000,000 was applied to a base material. In this case, the coating film is inferior in heat resistance under an environmental condition of 60 ° C. or more, and deteriorates the electromagnetic wave absorption performance, that is, the electromagnetic wave suppression effect. However, the electromagnetic wave suppression paper according to the present invention is excellent in heat resistance under an environmental condition of 85 ° C. and does not deteriorate the electromagnetic wave suppression effect.

  Embodiments of the present invention will be described below. However, the embodiments are examples of the configuration of the present invention, and the present invention is not limited to these embodiments.

  The electromagnetic wave suppression paper according to the present embodiment includes a copper alloy containing copper as a main component on at least one surface of a base material, and an ultrahigh molecular weight acrylic resin having a glass transition temperature of 50 ° C. or lower and a molecular weight of 300,000 to 1,000,000. A conductive resin layer containing a resin and an acrylic resin having a glass transition temperature of 50 ° C. or higher is coated with a thickness of 20 to 100 μm. Here, the conductive resin layer is made of a conductive paint mainly composed of a copper alloy containing copper as a main component and an ultrahigh molecular weight acrylic resin having a glass transition temperature of 50 ° C. or lower and a molecular weight of 300,000 to 1,000,000. It includes a form formed by coating a coating liquid in which an acrylic resin having a transition temperature of 50 ° C. or higher is mixed on at least one surface of a substrate.

(Base material)
The paper substrate used in this embodiment is selected from unbleached or bleached chemical pulp obtained by digesting hardwood or softwood, or mechanical pulp such as GP or thermomechanical pulp, or deinked waste paper pulp A paper having a basis weight of about 30 to 250 g / m ² is used, which is obtained by using a single pulp or a multilayer in a known wet paper machine. The papermaking method is not particularly limited, and any of acid paper, neutral paper, or alkaline paper may be used. Moreover, what applied the sizing agent chosen from the well-known starch, polyvinyl alcohol, the sizing agent for external addition, a synthetic resin, etc. with the size press or the roll coater on the paper base material which consists of said paper and paperboard may be used. Furthermore, incombustible paper, flame retardant paper, glass paper (paper-like structure made of glass fiber), single-sided or double-sided coated paper, and the like can also be used as a paper base material for the present embodiment. Furthermore, synthetic paper and plastic film can be used as a base material.

(Formation of conductive resin layer)
The conductive paint used in this embodiment is composed mainly of a copper alloy containing copper as a main component and an ultrahigh molecular weight acrylic resin having a glass transition temperature of 50 ° C. or lower and a molecular weight of 300,000 to 1,000,000. It is a coating liquid in which an acrylic resin having a glass transition temperature of 50 ° C. or higher is mixed with a paint.

  A copper alloy containing copper as a main component is contained in the conductive paint in the form of a metal filler. The composition of the copper alloy containing copper as the main component is 2 to 10% by mass of aluminum, 2 to 5% by mass of nickel, 0.001 to 0.5% by mass of boron and iron. It is a composition containing 0.5-5 mass%, 0.1-3 mass% of manganese, and 0.001-1 mass% of titanium.

  The acrylic resin contained in the conductive paint has an ultra-high molecular weight having a glass transition temperature of 50 ° C. or lower and a molecular weight of 300,000 to 1,000,000. When the glass transition temperature exceeds 50 ° C., there is a problem that the coating layer becomes hard and breaks when broken. In addition, when the molecular weight is less than 300,000, there is a problem that the metal filler is less likely to be incorporated into the three-dimensional graft mold having the stereoregularity of the living polymer, and is easily oxidized or deteriorated. If it exceeds 10,000, the rheological performance is inferior and the fluidity of the conductive paint deteriorates.

  The acrylic resin to be added to the conductive paint has a glass transition temperature of 50 ° C. or higher. The heat resistance temperature of the conductive resin layer is improved by mixing an acrylic resin having a glass transition temperature of 50 ° C. or higher with the above conductive paint, and a copper alloy mainly composed of copper is used as a ladder-like high-functional structure. To prevent oxidation and deterioration. Even if an acrylic resin having a glass transition temperature of less than 50 ° C. is mixed, these effects are insufficient.

  The metal content in the conductive coating is preferably 50 to 500 parts by mass with respect to 100 parts by mass of the ultrahigh molecular weight acrylic resin having a glass transition temperature of 50 ° C. or less and a molecular weight of 300,000 to 1,000,000. If the metal content exceeds 500 parts by mass, the flexibility is inhibited, and if it is less than 50 parts by mass, the electromagnetic wave suppressing effect may not be sufficiently exhibited.

  The conductive resin layer may have a composition in which an acrylic resin having a glass transition temperature of 50 ° C. or higher is added in an amount of 5 to 50 parts by mass in terms of solid content with respect to 100 parts by mass in terms of solid content of the conductive paint. preferable. Both the conductivity and heat resistance of the conductive resin layer can be sufficiently satisfied. Even when less than 5 parts by mass of an acrylic resin having a glass transition temperature of 50 ° C. or higher is mixed, heat resistance may not be sufficiently obtained. Even when an acrylic resin having a glass transition temperature of 50 ° C. or higher is mixed in excess of 50 parts by mass, the electromagnetic wave suppressing effect may not be sufficiently obtained.

  In addition, the electromagnetic wave suppression paper according to the present embodiment may be in the following form in addition to the method using the coating liquid. That is, the conductive resin layer has a copper alloy containing copper as a main component and an ultrahigh molecular weight acrylic resin having a glass transition temperature of 50 ° C. or less and a molecular weight of 300,000 to 1,000,000 on at least one side of the base material. This is a form formed by applying and drying the main conductive coating and further applying and drying a liquid containing an acrylic resin having a glass transition temperature of 50 ° C. or higher. At this time, in both of the two drying steps, the drying temperature is preferably 20 to 70 ° C. in consideration of the electromagnetic wave suppressing effect, as in the case of the drying method after coating of the coating liquid described later. More preferably, it is 60 degreeC. When it exceeds 70 ° C., the ultrahigh molecular weight acrylic resin is decomposed and the electromagnetic wave suppressing effect is deteriorated. Moreover, the liquid containing acrylic resin having a glass transition temperature of 50 ° C. or higher may be applied in an amount of 5 to 50 parts by mass in terms of solid content, assuming that the coating amount of the conductive coating is 100 parts by mass in terms of solid content. preferable.

  In the present embodiment, a known coater such as a pipe coater, a blade coater, an air knife coater, a roll coater, a reverse roll coater, a bar coater, a curtain coater, The coater is selected from a die coater, a gravure coater, a champlex coater, a spray coater and the like, and is applied in one layer or in multiple layers. The conductive resin layer is provided on at least one side of the substrate.

  The thickness of the conductive resin layer is not particularly limited, but is usually about 20 to 100 μm, preferably 50 to 80 μm, and more preferably 60 to 70 μm. If it is less than 20 μm, the electromagnetic wave suppressing effect is inferior, and if it exceeds 100 μm, it is not preferable in terms of productivity and cost.

  The drying method after the application of the conductive paint and after the application of the acrylic resin-containing liquid or after the application of the coating liquid obtained by mixing the conductive resin with the acrylic resin is not particularly limited. However, the following drying methods, that is, hot air drying, infrared drying, room temperature drying and the like can be mentioned, but infrared drying and hot air drying are preferable because of their drying efficiency. The drying temperature is preferably 20 to 70 ° C., more preferably 50 to 60 ° C. in consideration of the electromagnetic wave suppressing effect. When it exceeds 70 ° C., the ultrahigh molecular weight acrylic resin is decomposed and the electromagnetic wave suppressing effect is deteriorated.

(Formation of overcoat layer)
In the present embodiment, it is preferable to provide an overcoat layer on the conductive resin layer for the purpose of improving the roughness of the surface of the conductive resin layer and improving cracks. The resin included in the coating composition for the overcoat layer applied on the conductive resin layer in this embodiment is not particularly limited, and is a polyethylene terephthalate resin, polypropylene resin, vinyl chloride resin, fluororesin, silicone. Resin, acrylic resin, polyurethane resin, polycarbonate resin, polyphenylene oxide resin, polysulfone resin, polyimide resin, thermoplastic polyester resin, phenol resin, urea resin, epoxy resin, melamine resin, sialyl phthalate resin, furan resin, silicon inorganic compound Etc. More preferably, it has heat resistance.

  In this embodiment, to apply the overcoat resin of the coating composition as described above onto the conductive resin layer, it is the same as the coating method for forming the conductive resin layer.

  The thickness of the overcoat layer is not particularly limited, but is usually about 1 to 20 μm, preferably 3 to 10 μm. If the thickness is less than 1 μm, roughness of the conductive resin layer appears and there is no effect of improving the surface property, and if it exceeds 20 μm, it is not preferable in terms of cost.

  The drying method after the application of the coating composition for the overcoat layer is not particularly limited, and examples include the following drying methods: hot air drying, infrared drying, room temperature drying, etc. Hot air drying is preferred. The drying temperature is preferably 20 to 70 ° C., more preferably 50 to 60 ° C. in consideration of the electromagnetic wave suppressing effect. If it exceeds 70 ° C., the ultra-high molecular weight acrylic resin is decomposed and the electromagnetic wave suppression effect is deteriorated.

(Formation of adhesive sheet)
The pressure-sensitive adhesive layer is provided on the back side of the surface provided with the conductive resin layer, and is preferably a pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet is used in a very wide range such as home use, commercial use and industrial use. A specific usage method of the present embodiment is an electromagnetic wave suppression label for various electrical devices. The structure of the pressure-sensitive adhesive sheet is that the pressure-sensitive adhesive layer is provided between the support and the release paper, and the paper base material provided with the conductive resin layer and the overcoat layer of this embodiment is used for the support. Is done.

On the other hand, in this embodiment, it is preferable that release paper is stuck on the surface of the pressure-sensitive adhesive layer. As the release paper, non-coated paper such as high-quality paper, coated paper such as general coated paper and art paper, glassine paper, film using polyethylene resin, polyethylene terephthalate resin, or film laminated paper is used. Depending on the purpose, as a release agent, a silicone resin, a fluororesin, or the like applied and dried at a dry mass of about 0.1 to 3 g / m ² can be used.

  The types of pressure-sensitive adhesive used in the pressure-sensitive adhesive layer in the present embodiment include natural rubber-based, synthetic rubber-based, polyurethane-based, acrylic polymer, vinyl acetate-based polymer, vinyl acetate-acrylate copolymer, vinyl acetate-ethylene. Various adhesives such as copolymers are used depending on the purpose.

  The electromagnetic wave suppression paper according to the present embodiment was measured using the S-parameter method (S-21), which is a near-field radio wave absorption material measurement method, at a frequency of 2.4543 GHz after heat treatment at 85 ° C. for 1000 hours. It is preferable that both the radio wave absorption rate [dB] and the influence degree [dB] on the circuit are −6 dB or less. When the radio wave absorption rate [dB] and the influence degree [dB] on the circuit exceed −6 dB, the electromagnetic wave suppression rate becomes less than 75%, and thus the effect is weak.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited to these Examples. Further, “parts” and “%” in the examples indicate “parts by mass” and “% by mass” unless otherwise specified. In addition, the measuring method of a physical property is as follows.

Example 1
Conductive paint (trade name: Eco Gold PLS-200-US) on one side of a baking paper base (made by Hokuetsu Paper Co., Ltd .: basis weight 49.9 g / m ² , thickness 0.081 mm, density 0.62 g / cm ³ ) Acrylic resin (trade name: Armatex L1092-1, Tg = 60 ° C., solid content 50.8%, Mitsui Chemicals Co., Ltd.) 20.5 parts by mass in terms of solid content (conducting paint: acrylic resin = 80: 20 in terms of mass ratio of the packing chemical) and mixed at a blended ratio to prepare a coating solution, and after drying After coating the coating solution so that the film thickness of the conductive resin layer became 70 μm, it was dried at 60 ° C. for 1 minute with a hot air dryer to obtain the electromagnetic wave suppression paper of Example 1. The conductive paint is mainly composed of a copper alloy containing copper as a main component and an ultrahigh molecular weight acrylic resin having a glass transition temperature of 50 ° C. or less and a molecular weight of 300,000 to 1,000,000.

[Physical property evaluation of electromagnetic wave suppression paper]
In the electromagnetic wave suppression paper obtained in this manner, the thickness of the conductive resin layer, the electromagnetic wave suppression property, and the heat resistance are evaluated according to the following method after conditioning at 23 ° C. and 50% RH, It is shown in Table 1.

[Thickness of conductive resin layer]
The thickness of the base paper and the coated paper was measured by the method specified in JIS P 8118: 1998 “Paper and paperboard—Test method for thickness and density”, and the difference in thickness between the base paper and the coated paper was applied. The thickness of the conductive resin layer was used.

[Electromagnetic wave suppression]
Using a network analyzer (Anritsu 37 series), which is a near-field radio wave absorption material measuring device, the radio wave absorption rate [dB] at a frequency of 2.4543 GHz and the degree of influence on the circuit [dB] are measured by the S-parameter method. did. If both the radio wave absorption rate [dB] and the influence level [dB] on the circuit are −6 dB or less, it is determined that the electromagnetic wave suppression paper can be used. On the other hand, if it is −10 dB (90% electromagnetic wave suppression rate), it is determined that the radio wave absorption rate [dB] is good and the degree of influence [dB] on the circuit is not. Furthermore, the electromagnetic wave suppression rate is 99% for -20 dB, and 99.9% for -30 dB.
The evaluation criteria are as follows.
X: Both the radio wave absorption rate [dB] and the influence level [dB] on the circuit are larger than −6 dB, and cannot be used as electromagnetic wave suppression paper.
Δ: Both the radio wave absorption rate [dB] and the influence level [dB] on the circuit are −6 dB to −10 dB, which is a level that can be used as electromagnetic wave suppression paper.
○: The electromagnetic wave absorption rate [dB] and the influence degree [dB] on the circuit are both less than −10 dB, which is a very good level as an electromagnetic wave suppression paper.

[Heat-resistant]
The radio wave absorptivity [dB] and frequency influence [dB] at a frequency of 2.4543 GHz after heat treatment at 85 ° C. for 1000 hours in a dryer were evaluated by the above measurement method.

(Example 2)
Acrylic resin (trade name: Almatex L1092-1, Tg) with respect to 100 parts by mass in terms of solid content of conductive paint (trade name: Eco Gold PLS-200-US, solid content 62%, manufactured by Hertz Chemical Co., Ltd.) = 60 ° C, solid content 50.8%, manufactured by Mitsui Chemicals Co., Ltd.) 9.1 parts by mass in terms of solid content (conductive paint: acrylic resin = 90: 10 in terms of mass ratio of packing chemicals) An electromagnetic wave suppression paper of Example 2 was obtained in the same manner as Example 1 except that.

(Example 3)
In Example 1, the electromagnetic wave suppression paper of Example 3 was obtained in the same manner as in Example 1 except that the coating liquid was applied so that the thickness of the conductive resin layer after drying was 60 μm.

Example 4
In Example 1, the electromagnetic wave suppression paper of Example 4 was obtained in the same manner as in Example 1 except that the drying condition after application of the conductive paint was changed to 50 ° C. for 1 minute.

(Example 5)
Conductive paint (trade name: Eco Gold PLS-200-US) on one side of a baking paper base (made by Hokuetsu Paper Co., Ltd .: basis weight 49.9 g / m ² , thickness 0.081 mm, density 0.62 g / cm ³ ) 62% solid content (manufactured by Hertz Chemical Co., Ltd.) was applied so that the thickness after drying was 67 μm, dried at 60 ° C. for 1 minute with a hot air dryer, and then an acrylic resin (trade name: Almatex L1092-) 1, Tg = 60 ° C., solid content 50.8%, manufactured by Mitsui Chemicals Co., Ltd.) with a round bar so that the film thickness is 3 μm, and the total thickness of the conductive resin layer after drying is 70 μm. Thus, it dried for 1 minute at 60 degreeC with the hot air dryer, and the electromagnetic wave suppression paper of Example 5 was obtained. The obtained conductive resin layer has a composition in which 20.5 parts by mass of an acrylic resin having a glass transition temperature of 50 ° C. or higher is added to 100 parts by mass of the solid content of the conductive coating.

(Example 6)
In Example 1, glassine paper (trade name: glassine paper for processing, manufactured by Lintec Co., Ltd.) 85 g / m ² was used as a release substrate, and solvent silicone release agent (trade name: KS-776, manufactured by Shin-Etsu Silicone Co., Ltd.) 1 g / m ² , acrylic pressure-sensitive adhesive (trade name: BPS5303-20J1 / BHS8515 = 100 / 1.5, manufactured by Toyo Ink Co., Ltd.), 20 g / m ² each of which was dried and dried on the non-coated surface of the baking paper base paper An electromagnetic wave suppression paper of Example 6 was obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive sheet was produced by bonding.

(Example 7)
In Example 1, an electromagnetic wave suppression paper of Example 7 was obtained in the same manner as in Example 1 except that the coating liquid was applied so that the thickness of the conductive resin layer after drying was 45 μm.

(Example 8)
In Example 1, an electromagnetic wave suppression paper of Example 8 was obtained in the same manner as in Example 1 except that the coating liquid was applied so that the thickness of the conductive resin layer after drying was 90 μm.

Example 9
Acrylic resin (trade name: Almatex L1092-1, Tg) with respect to 100 parts by mass in terms of solid content of conductive paint (trade name: Eco Gold PLS-200-US, solid content 62%, manufactured by Hertz Chemical Co., Ltd.) = 60 ° C., solid content 50.8%, manufactured by Mitsui Chemicals Co., Ltd.) 35.1 parts by mass in terms of solid content (conductive paint: acrylic resin = 70: 30 in terms of mass ratio of packing chemicals) was added The electromagnetic wave suppression paper of Example 9 was obtained in the same manner as Example 1.

(Comparative Example 1)
In Example 1, the electromagnetic wave suppression paper of Comparative Example 1 was obtained in the same manner as in Example 1 except that the conductive resin layer after drying was coated to a thickness of 10 μm.

(Comparative Example 2)
In Example 1, the electromagnetic wave suppression paper of Comparative Example 2 was obtained in the same manner as in Example 1 except that the drying condition after application of the coating liquid composed of the conductive paint and acrylic resin was changed to 105 ° C. for 1 minute. It was.

(Comparative Example 3)
In Comparative Example 2, an electromagnetic wave suppression paper of Comparative Example 3 was obtained in the same manner as Comparative Example 2 except that the drying condition was 125 ° C. for 1 minute.

(Comparative Example 4)
In Example 1, the electromagnetic wave suppression paper of Comparative Example 4 was obtained in the same manner as Example 1 except that the acrylic resin was not added.

(Comparative Example 5)
In Example 2, the electromagnetic wave suppression paper of Comparative Example 5 was obtained in the same manner as in Example 1 except that the conductive resin layer after drying was coated to a thickness of 10 μm.

(Comparative Example 6)
In Example 1, an acrylic resin having a glass transition temperature (Tg) of 25 ° C. (trade name: Armatex L1060, solid content 40%, manufactured by Mitsui Chemicals) was replaced with an acrylic resin having a glass transition temperature (Tg) of 60 ° C. The electromagnetic wave suppression paper of Comparative Example 6 was obtained in the same manner as in Example 1 except that it was added to the above.

(Comparative Example 7)
Acrylic resin (trade name: Almatex L1092-1, Tg) with respect to 100 parts by mass in terms of solid content of conductive paint (trade name: Eco Gold PLS-200-US, solid content 62%, manufactured by Hertz Chemical Co., Ltd.) = 60 ° C., solid content 50.8%, manufactured by Mitsui Chemicals Co., Ltd.) except that 54.6 parts by mass in terms of solid content (conductive paint: acrylic resin = 60: 40 in terms of mass ratio of the packing chemical) was added The electromagnetic wave suppression paper of Comparative Example 7 was obtained in the same manner as Example 1.

  As is clear from the results in Table 1, all of Examples 1 to 9 were excellent in heat resistance because the electromagnetic wave suppressing effect was hardly lowered even when used under environmental conditions of 85 ° C.

On the other hand, in Comparative Example 1 and Comparative Example 5, since the thickness of the conductive resin layer was as thin as 10 μm, the radio wave absorption rate was low and the heat resistance was insufficient. Since the comparative example 2 and the comparative example 3 had high drying temperature, heat resistance was not acquired. In Comparative Example 4, since no acrylic resin having a glass transition temperature of 50 ° C. or higher was added, heat resistance was not obtained. In Comparative Example 6, heat resistance was not obtained because an acrylic resin having a glass transition temperature of 25 ° C. was added to the conductive paint to form a coating solution. In Comparative Example 7, the balance of blending the conductive paint and the acrylic resin having a glass transition temperature of 50 ° C. or higher was uneven, and the heat resistance was not sufficient.

Claims (11)

  On at least one side of the substrate, a copper alloy mainly composed of copper, an ultrahigh molecular weight acrylic resin having a glass transition temperature of 50 ° C. or lower and a molecular weight of 300,000 to 1,000,000, and a glass transition temperature of 50 ° C. or higher An electromagnetic wave suppression paper, wherein a conductive resin layer containing an acrylic resin is coated with a thickness of 20 to 100 μm.   The conductive resin layer has a glass transition to a conductive paint mainly composed of a copper alloy mainly composed of copper and an ultra high molecular weight acrylic resin having a glass transition temperature of 50 ° C. or less and a molecular weight of 300,000 to 1,000,000. The electromagnetic wave suppression paper according to claim 1, wherein the electromagnetic wave suppression paper is formed by coating a coating liquid in which an acrylic resin having a temperature of 50 ° C. or more is mixed on at least one surface of the substrate.   The conductive resin layer is mainly composed of a copper alloy mainly composed of copper and an ultrahigh molecular weight acrylic resin having a glass transition temperature of 50 ° C. or lower and a molecular weight of 300,000 to 1,000,000 on at least one surface of the base material. The conductive paint according to claim 1, which is formed by applying and drying a conductive paint, and further applying and drying a liquid containing an acrylic resin having a glass transition temperature of 50 ° C or higher. Electromagnetic wave suppression paper.   The conductive resin layer has a composition in which an acrylic resin having a glass transition temperature of 50 ° C. or higher is added in an amount of 5 to 50 parts by mass in terms of solid content with respect to 100 parts by mass in terms of solid content of the conductive paint. The electromagnetic wave suppression paper according to claim 1, 2, or 3.   5. The electromagnetic wave suppression paper according to claim 1, wherein an overcoat layer is provided on the conductive resin layer.   6. The electromagnetic wave suppression paper according to claim 1, wherein the conductive resin layer is formed on one surface of the substrate, and an adhesive layer is formed on the other surface. .   The electromagnetic wave suppression paper according to claim 6, wherein a release paper is affixed to a surface of the pressure-sensitive adhesive layer.   The base material is acid paper, neutral paper, alkaline paper, incombustible paper, flame retardant paper, glass paper, single-sided or double-sided coated paper, synthetic paper, or plastic film, The electromagnetic wave suppression paper according to 3, 4, 5, 6 or 7.   Measured using the S-parameter method (S-21), which is a near-field radio wave absorption material measurement method, and the radio wave absorption rate [dB] at a frequency of 2.4543 GHz after 1000 hours of heat treatment at 85 ° C. 9. The electromagnetic wave suppression paper according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein the degree of influence [dB] is -6 dB or less.   A conductive paint mainly composed of a copper alloy containing copper as a main component and an ultrahigh molecular weight acrylic resin having a glass transition temperature of 50 ° C. or less and a molecular weight of 300,000 to 1,000,000 has a glass transition temperature of 50 ° C. or more. The acrylic resin is mixed to adjust the coating solution, and the coating solution is applied to at least one surface of the base material and dried in a temperature range of 20 to 70 ° C., so that the thickness of the conductive resin layer is increased. An electromagnetic wave suppression paper manufacturing method characterized by being formed to 20 to 100 μm.   A conductive paint mainly composed of a copper alloy mainly composed of copper and an ultrahigh molecular weight acrylic resin having a glass transition temperature of 50 ° C. or less and a molecular weight of 300,000 to 1,000,000 is applied to at least one surface of the substrate. And dried in a temperature range of 20 to 70 ° C., and further coated thereon with an acrylic resin-containing liquid having a glass transition temperature of 50 ° C. or higher, and dried in a temperature range of 20 to 70 ° C. A method for producing an electromagnetic wave-suppressing paper, wherein the thickness of the conductive resin layer is 20 to 100 μm.