Inner magnetic shielding material and method for production thereof

Abstract

An inner magnetic shielding material, characterized as comprising a cold rolled steel sheet having a surface roughness of 0.2 to 3 mumRa and, formed at least one surface thereof,, an organic resin coating film comprising C and H, or C, H and O, or C, H, O and N and having a thickness of 0.3 to 5 mum; and a method for producing the inner magnetic shielding material which comprises a step of annealing a cold rolled steel sheet, a step of adjusting a surface roughness of the annealed steel sheet to value of 0.2 to 3 mumRa, a step of forming an organic resin coating film comprising C and H, or C, H and O, or C, H, O and N and having a thickness of 0.3 to 5mum at least one surface of the cold rolled steel sheet. The inner magnetic shielding material has good resistance to rust and good degreasing and cleaning properties, is free from the danger of generating a corrosive gas, and also has good press formability.

Description

technical field [0001] The invention relates to a material for an inner magnetic shield, which is a part installed in a cathode ray tube used in a color TV, and to a method of producing such a material. Background of the invention [0002] The basic structure of a cathode ray tube (CRT) used in a color TV consists of an electron gun and a phosphor screen that converts the electron beams into an image. These parts are housed in a glass tube formed by joining the panel part and the funnel part. [0003] In order to prevent the electron beams from being deflected due to the earth's magnetism, a magnetic shield member (hereinafter simply referred to as a magnetic shield) is provided on the cathode ray tube side. The magnetic shield includes an inner magnetic shield installed inside the cathode ray tube and an outer magnetic shield installed outside the cathode ray tube. [0004] The materials used for these inner and outer magnetic shields have to be press-workable in addition...

AI Technical Summary

Problems solved by technology

However, fluctuations in these parameters are unavoidable, and there are cases where the blackening film is too thick and its adhesion is poor

[0017] Second, because the iron oxide film including FeO is extremely hard, various problems occur during press working of the material, such as peeling off of the blackened film in the processed portion, damage to dies for punching or the like, and shortening due to wear The service life of the mold

[0018] Third, if the film thickness is reduced to ensure adhesion, its corrosion resistance is not high enough, during the storage of the inner magnetic shield material or the period before sealing the cathode ray tube with the inner magnetic shield will rust

However, it is also known that the thickness of the obtained diffusion layer is difficult to control, and if the diffusion due to annealing is too large, its corrosion resistance will be reduced.

Specifically, the plating film formed by the above-mentioned Ni plating method is very thin, so it is difficult to prevent its excessive diffusion with certainty.

[0022] Therefore, the above two internal magnetic shield materials that do not require blackening treatment are produced under strict control including annealing conditions, but considering that fluctuations in annealing conditions are inevitable, it is difficult to produce products with stable quality

[0023] Also, in both methods, hematite (rust) may form during the sealing step in air at high temperature, in which case it is not possible to degas the cathode ray tube to required vacuum

[0024] In addition, for the internal magnetic shields in the prior art (including conventional internal magnetic shields that have undergone blackening treatment after press working), the film formed on the surface is a porous film, and the washing step performed before sealing the cathode ray tube In, oil stains adhered after blackening treatment or oils such as anti-rust oil or processing oil coated on the material cannot be completely removed