JPH0427942B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to a method of manufacturing a decorative board with enhanced surface conductivity. Conventional technology The discharge of static electricity gives a shock to the human body, the discharge sparks cause explosions and fires, and furthermore, the electrostatic attraction promotes the adhesion of dust to records and other plastic products, generating noise. It has been known for a long time that this can cause various inconveniences, such as causing damage and spoiling the aesthetic appearance. Static electricity is generated simply when materials come into contact with each other, and always involves three elementary processes: charge transfer, charge separation, and charge relaxation.For materials with high electrical resistance, such as plastics, charge relaxation is extremely slow, so the charging phenomenon occurs. will appear. Static electricity hazards in the field of building interior materials mainly appear in the form of shocks to the human body due to static electricity generated due to friction between flooring materials and pedestrians, and in factories that handle flammable materials, static electricity caused by the same cause can cause fires. It can also be a cause. Therefore, as a countermeasure, the use of rubber flooring materials kneaded with carbon powder, or the use of carpets woven from fibers containing antistatic agents or woven with conductive fibers, have been used for a long time. There is. On the other hand, when it comes to wall covering materials, furniture boards, etc., there is a problem in that wallpaper and decorative boards with plastic-treated surfaces become electrostatically charged and absorb dust and cigarette smoke in the air, making them easy to stain. To avoid causing such serious damage, simple measures such as spraying antistatic agents on the surface or incorporating them into the material were taken. However, in recent years,
As digital electronic devices incorporating a large number of ICs and LSIs become widespread in factories, offices, medical institutions, and even ordinary homes, wall mounting is required to prevent element damage and equipment malfunction due to static electricity. There is a need to strengthen antistatic measures for all interior materials, including interior materials. For this reason, one of the measures considered for decorative boards is to use electrically conductive paper as a decorative paper to be attached to a base material such as plywood or particle board. As conductive paper, it is common practice to use paper in which conductive fibers such as carbon fibers and metal fibers are added during papermaking (Utility Model Publications No. 58-38438, No. 58-48435, etc.). . However, as a conductive paper, the surface resistivity is on the order of
Even if you use a material with a diameter of ¹⁰⁴ or less that has no fear of being charged, the surface resistivity of the decorative board will be on the order of ^{103 or} more because it is impregnated with thermosetting synthetic resin when it becomes a decorative board. Therefore, the charging tendency is not improved much. In addition, since both carbon fiber and metal fiber are black or highly colored, using conductive paper is extremely disadvantageous in terms of design, and the problem of color tone can be resolved by printing on the entire surface with ink with strong hiding power. However, this will further reduce the conductivity. Problems to be Solved by the Invention An object of the present invention is to solve the above-mentioned problems when manufacturing a conductive decorative board using conductive paper, and to solve the problems described above when manufacturing a conductive decorative board using conductive paper. The object of the present invention is to provide a method for manufacturing a highly conductive decorative board having a resistivity of about 10 ⁷ Ω or less. Means for Solving the Problems The means adopted in the present invention to solve the above problems is to print on one side of conductive paper into which conductive fibers have been printed for surface concealment. It is characterized by subjecting printing paper to resin impregnation treatment using a thermosetting resin containing conductive inorganic powder, and then stacking the resulting resin-impregnated paper on a base material for decorative laminate and hot-pressing molding. be. The method for producing a conductive decorative board according to the present invention includes a method using an ink mixed with conductive inorganic powder as the ink used in the printing process. The conductive paper used in the production method of the present invention is not particularly limited, and commercially available conductive paper containing conductive fibers such as carbon fibers, metal fibers, and metallized glass fibers can be used. Preferably, the surface resistivity is less than 10 ⁵ Ω. This conductive paper may be one mixed with titanium oxide, white clay, or the like. The ink used for printing for surface hiding can be selected from ordinary inks with strong hiding power, but it is recommended to use conductive inorganic powder at 5 to 20%.
By using ink with a certain degree of contamination, a product with a particularly low surface resistivity and a stable value can be obtained. Conductive powders mixed into ink include various metal powders, carbon black, graphite powder, conductive metal oxide powders, conductive mineral powders, non-conductive fine particles coated with conductive substances, etc. Select the type of ink that has a value of approximately 100 Ω or less (measured when compressed at a pressure of 500 kg/cm ² or more) that does not significantly deteriorate the basic characteristics of the ink and does not cause any problems in terms of color tone. Select accordingly. Many conductive powders such as those mentioned above are commercially available, and examples of special ones include conductive zinc oxide (Honjo Chemical; zinc oxide doped with a trace amount of metal), conductive fine powder (Mitsubishi Metals; titanium with a tin oxide coating). Even if ink containing conductive powder is used, if the ink layer is too thick, the conductivity will drop significantly, so whether the ink contains conductive powder or not, printing should hide the conductive fibers. It is desirable that the printed surface resistivity be no higher than 10 ⁶ Ω. Printing can be done more than once if necessary, or it can be done to form a pattern, in which case a part of the surface of the conductive paper is left unprinted to form the pattern. It may be a part of it. The printing paper obtained as described above is subjected to a resin impregnation treatment using a thermosetting resin to which conductive inorganic powder has been added, and the conductive powder used in this case is also exemplified as something that can be mixed into the ink. Depending on the type of resin, one is selected from among those similar to those used above, which have no inconvenience in terms of color tone and do not adversely affect the basic properties of the resin, especially the curing properties. The higher the amount of conductive powder added, the lower the surface resistivity of the product can be obtained, but there is a limit to the amount that can be added without impairing the original effect of resin impregnation, so the preferred addition rate is conductive powder. It is necessary to confirm experimentally depending on the combination of powder and resin. The resin for impregnation is not particularly limited, but diallyl phthalate resin (or a mixture thereof with unsaturated polyester resin), which has been most commonly used in the production of decorative laminates, or melamine resin can be used in the production method of the present invention. gives the most favorable results. The impregnation process using a thermosetting resin containing conductive powder and the process of stacking the resin-impregnated paper obtained by the impregnation on a base material for decorative laminates and hot-pressing molding are carried out in accordance with the usual methods for manufacturing decorative laminates. There are no restrictions on the material of the base material. Examples Hereinafter, the present invention will be explained with reference to Examples and Comparative Examples. The conductive paper used in each example was carbon fiber mixed paper “Carbon CF” (Kojin; surface resistivity
3.4×10 ⁴ Ω), and the surface resistivity was measured using a Takeda Riken Kogyo digital multimeter TR6843. Examples 1 to 8, Comparative Examples 1 to 4 Full-surface printing was performed twice on one side of conductive paper using a normal printing ink containing titanium oxide as a pigment or an ink mixed with conductive powder.
The resulting printing paper was impregnated with a resin liquid having the following composition. Diaryl phthalate resin prepolymer 60 parts by weight Unsaturated polyester resin 40 Peroxide catalyst 3 Conductive zinc oxide 20 Solvent 50 Internal mold release agent 0.5 Thereafter, the resulting resin-impregnated paper was stacked on plywood and heat-pressed by a conventional method. It was molded (Examples 1 to 8). For comparison, Comparative Example 1 was the same as above except that no conductive powder was added to either the ink or the impregnating resin, and Comparative Examples 2 to 4 were the same as above except that no conductive powder was added to the impregnating resin. was carried out. Table 1 summarizes the manufacturing conditions and the surface resistivities of the printing paper, which is an intermediate product, and the product.

[Table] Effects of the Invention According to the present invention, when manufacturing a conductive decorative board using conductive paper, it is possible to sufficiently hide black or dark-colored conductive fibers and perform arbitrary surface printing. This results in a conductive decorative board that is similar in design to a normal (non-conductive) decorative board. Moreover, the surface resistivity of the product is
It is less than 10 ⁷ Ω and exhibits sufficient conductivity for practical use, so it can be used not only in general homes and offices, but also in electronic equipment installation rooms, semiconductor manufacturing plants, and handling workplaces where antistatic requirements are particularly strict. Even if used in a location, it will not cause static electricity hazards.

Claims (1)

[Scope of Claims] 1. Printing is applied to one side of conductive paper into which conductive fibers have been made for surface concealment, and the resulting printed paper is
Manufacture of conductive decorative laminate, characterized by performing resin impregnation treatment using thermosetting resin to which conductive inorganic powder is added, and stacking the obtained resin-impregnated paper on a base material for decorative laminate and hot-pressing molding. Law. 2. Claim 1 in which printing is performed so that the surface resistivity of the printed surface of the printing paper does not become higher than 10 ⁶ Ω.
Manufacturing method described in section. 3 Printing is performed on one side of conductive paper containing conductive fibers using ink mixed with conductive inorganic powder, and the resulting printed paper is heated with conductive inorganic powder added. A method for producing a conductive decorative board, which comprises performing a resin impregnation treatment using a curable resin, stacking the obtained resin-impregnated paper on a base material for a decorative board, and hot-pressing molding.