Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1991-03-20
1995-04-18
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524406, 427 58, 4273882, C08K 310
Patent
active
054079900
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a composition for forming insulating films of improved insulating performance on electrical steel sheets, with which an insulating film excelling not only in insulating performance and weldability but also in such film properties as water resistance, adhesion, punchability and corrosion resistance can be coated and formed on the electrical steel sheets without substantial expansion, and is concerned with a method for forming insulating films on electrical steel sheets with said composition.
BACKGROUND TECHNIQUE
So far, numerous techniques have been disclosed about how to form insulating films on the surfaces of electrical steel steers and compositions for providing such insulating films. Long-established techniques make use of insulating film-forming compositions consisting as the main component of chromates and/or phosphates to form inorganic films. A problem with the inorganic films made of such inorganic materials is that although they excel in heat resistance, yet they are inferior in their water resistance, punchability and adhesion to steel sheets during processing.
Recently, according to techniques attempted in many cases to solve such a problem, a film-forming composition containing a mixture of a film forming-inorganic element such as chromate or phosphate etc. (hereinafter sometimes called the inorganic component) with a film forming-organic resin (hereinafter sometimes referred to as the organic component or simply the resin; said resin being usually a synthetic resin which may hereinafter be also called the "polymer") is applied to an electrical steel sheet to form on it a combined inorganic/organic film (hereinafter often sometimes called the semi-organic film). This semi-organic film is to take full advantage of both the properties of the inorganic film that it excels in weldability and heat resistance and the properties of the organic film that it excels in water resistance, insulating performance, punchability and adhesion. A composition for forming the semi-organic film is generally obtained in the form of a mixture (hereinafter sometimes called the inorganic component-containing mixed emulsion or simply referred to as the mixed emulsion) of an aqueous solution (often used with a view to a working environment and fire prevention) of an inorganic component with an aqueous polymer emulsion in which an organic component is dispersed. However, the technique for forming the semi-organic film of the inorganic component-containing mixed emulsion suffers from various disadvantages. The first disadvantage is a short pot life due to the emulsification and dispersion of the resin (polymer) in the mixed emulsion which are unstable. The second disadvantage is that because the mixed emulsion contains an emulsifier or dispersant used to emulsify and disperse the resin (polymer), foams come to be observed on the resulting film by various coating operations such as stirring etc. to give rise to pinholes in crater-forms or bubble-like defects on the film. This makes the formed film poor in corrosion resistance and insulating performance. The third disadvantage is that when electrical steel sheets with films formed on them are punched out followed by lamination and welding, the organic component decomposes to emit gases and give rise to blow-holes in a beaded region, resulting in a serious degradation of weldability.
Action taken against the second disadvantage will now be explained. In order to reduce as much as possible the expansion of the mixed emulsion to a minimum, a defoamer is generally incorporated in the aqueous polymer emulsion that is one preparatory material for the mixed emulsion. However, this defoamer is likely to lose its effect gradually during the storage of the aqueous polymer solution to which the defoamer was added. Especially when it freezes in a cold district during the winter season, it loses its substantial defoaming effect upon thawing. This then causes the mixed emulsion to foam during preparation or when applied to steel plates
REFERENCES:
patent: 3793073 (1974-02-01), Kitayama et al.
patent: 4032675 (1977-06-01), Irie et al.
patent: 4170671 (1979-10-01), Hirasawa et al.
patent: 4618377 (1986-10-01), Nakamura et al.
patent: 4671825 (1987-06-01), Ishii et al.
patent: 4830877 (1989-05-01), Katayama et al.
patent: 4844753 (1989-07-01), Katayama et al.
Maeda Yasuharu
Masuhara Kenichi
Sakakura Akira
Tanaka Koji
Guarriello John J.
Michl Paul R.
Nisshin Steel Co. Ltd.
Toyobo Co. Ltd.
LandOfFree
Composition and method for forming insulating films on electrica does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Composition and method for forming insulating films on electrica, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composition and method for forming insulating films on electrica will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-67791