JP2560778B2 - Method for manufacturing electric field shield material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a material for shielding an electrostatic field or a dynamic field such as an electromagnetic wave, for example, a method for producing an electric field shield material that can be used as a decorative plate or the like. .

(Prior Art) It is well known that there is no electric field in a perfect conductor, and even if it is not a perfect conductor, the electric field in a metal conductor is significantly smaller than the external electric field. BACKGROUND ART Techniques for blocking an electric field and attenuating an electromagnetic wave by blocking an electric field (dynamic electric field) of the electromagnetic wave are well known.

Since electric and electronic devices such as televisions are affected by external electric fields and generate electromagnetic waves themselves, their cabinets are required to have a function of blocking electric fields and magnetic fields, and they are used as wall materials for homes and offices. Even so, the electric field blocking ability and the designability are similarly required.

Then, as such a decorative material, one using a metal conductor as one of the materials constituting the melamine decorative board is known. Broadly speaking, there are a method of mixing a melamine resin with a metal powder to impregnate a paper material, a method of applying a paint containing a metal powder to any material, and a method of providing a metal foil in its layer structure.

(Problems to be Solved by the Invention) In any of the above methods and methods, it is difficult to obtain a uniform shielding effect because dispersion in resin or coating material or coating amount on material is likely to be uneven. In addition, there was a limit to the usable time of the mixed liquid, and the unused resin liquid had to be discarded. Furthermore, as a result of the presence of the metal powder decreasing the adhesive strength, the original physical properties of the decorative board (adhesive strength of each material) could not be obtained.

According to the other method, since the metal foil has no adhesive strength, the original adhesive strength of the decorative board could not be obtained even by the anchor coating treatment. Further, since it is necessary to handle the metal foil, the workability is extremely poor.

(Means for Solving the Problem) In order to solve the problem, the present invention is to provide a surface of a mixed paper obtained by mixing thermosoftening synthetic resin pulp and metal powder with an impregnated paper impregnated with a thermosetting resin. By hot pressing
Provided is a method for producing an electric field shield material, characterized by increasing the density of a mixed paper by 20% or more while curing and integrating a thermosetting resin.

(Function) The thermosoftening synthetic resin pulp of the mixed paper is softened by heat and pressure and is compressed to increase its density, and as a result, the apparent volume resistance and surface resistance are reduced.

Also, since it takes a certain amount of time to cure the thermosetting resin, the thermosetting resin is once softened by heat and pressure, penetrates into the mixed paper, and then hardens, so that the mixed paper and the impregnated paper are firmly integrated. Turn into.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 of the drawings is an explanatory view showing the time of hot pressing.

In FIG. 1, A is an upper and lower hot press platen, and a backer paper 5, a plurality of core papers 4, a mixed paper 3, an impregnated paper 2 on the lower hot press platen A via a cushion B and a release sheet C. , The overlay paper 1 is superposed in this order, and is heat-pressed by the upper hot-press board A through the mirror surface board D and the cushion B. The conditions of the hot-pressing temperature are 140 to 150 ° C., the pressure is 80 to 100 kg / cm ² , the time is 10 to It is for 30 minutes, and then cooled with cold water for 15 to 30 minutes while being pressurized.

The overlay paper 1 is an impregnated paper obtained by impregnating rayon pulp having a basis weight of 25 to 45 g / m ² with melamine resin in an amount of 40 to 50%, and becomes transparent and becomes a surface protective resin layer after hot pressing.

The impregnated paper 2 is formed by printing a highly designable pattern such as wood grain on titanium paper having a basis weight of 55 to 160 g / m ² , impregnating a thermosetting resin such as melamine, and drying.

The mixed paper 3 is made by mixing metal powder with heat-softening synthetic resin pulp such as polyethylene or polypropylene. The use of the heat-softenable synthetic resin pulp is for holding the metal powder and for softening at the time of hot pressing. In addition to synthetic resin pulp, natural pulp may be included. Metal powder
In addition to copper, silver, aluminum, zinc, etc., high permeability metals such as iron, nickel, etc. can be used. The mixing amount of the metal powder depends on the thickness of the mixed paper, but is preferably 10% by weight or more.

The core paper 4 is a paper having a basis weight of 140 to 180 g / m ² and phenol resin.
It is impregnated with 30 to 60% and dried to a semi-cured state. In order to maintain the dimensional stability of the decorative board and to determine the thickness of the decorative board, several sheets are used in piles. The backer paper 5 serves to prevent warping of the decorative plate.

When hot pressed, the mixed paper 3 is compressed and its density is 20
Apply heat and pressure to increase by more than%. This is because the increase in density improves mechanical strength and conductivity.

(Test Example 1) A mixed paper was manufactured using copper and nickel powders, and a polyolefin-based synthetic resin pulp and natural pulp. The basis weight of the mixed paper is 300 g / m ² , and the content of metal powder is 15% by weight.

Using this mixed paper, as shown in FIG. 1, overlay paper, impregnated paper, core paper and backer paper were overlaid and integrated by hot pressing. The conditions of hot pressure were 150 ° C., 80 Kg / cm ² , and 10 minutes, and then, the pressure was kept constant and cooled with cold water for 20 minutes. In addition,
The density of the mixed paper increased by 20%.

When the shield effect of the conductive field of this decorative plate was measured, it was about 40 dB. Further, the respective materials were firmly integrated with each other and had sufficient adhesive strength.

(Effects) According to the present invention, it is possible to provide a decorative plate that is excellent in the shield effect of electrostatic and dynamic electric fields, and thus can also attenuate electromagnetic waves, has strong adhesion between materials, and is excellent in design. . Needless to say, maintenance of paint and handling of metal foil are unnecessary, and uneven shielding effect does not occur.

[Brief description of drawings]

 FIG. 1 is an explanatory view showing the time of hot pressing. 2 ... Impregnated paper, 3 ... Mixed paper

Claims (1)

(57) [Claims] 1. A thermosetting resin is hardened and integrated by superimposing an impregnated paper impregnated with a thermosetting resin on the surface of a mixed paper obtained by mixing thermosoftening synthetic resin pulp and metal powder, and then thermocompressing the thermosetting resin. In addition, the method for producing an electric field shield material is characterized by increasing the density of the mixed paper by 20% or more.