Coating processes – Direct application of electrical – magnetic – wave – or... – Polymerization of coating utilizing direct application of...
Reexamination Certificate
2001-03-30
2002-10-01
Pianalto, Bernard (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Polymerization of coating utilizing direct application of...
C427S162000, C427S255360, C427S255500, C427S404000, C427S407100
Reexamination Certificate
active
06458428
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of forming aluminum metallized films and protective films—such as silicone plasma polymerized films for protecting the aluminum metallized films—on synthetic-resin base materials through lined up processing stages.
More specifically, the invention relates to a method of forming aluminum metallized films and silicone protective films through the steps of housing and lining up, in a predetermined case, a plurality of synthetic-resin base materials for use in various reflectors—such as reflective mirrors for use in vehicular lamps such as automobiles, two-wheeled automobiles and the like, particularly synthetic-resin base materials of reflectors to be mounted in discharge headlamps—and passing the case successively through an aluminum metallizing chamber and a silicone protective film forming chamber. The invention also relates to a reflector formed by the above-described method.
2. Description of the Related Art
In the lamp chamber of a vehicular lamp—such as a headlamp to be mounted in an automobile, a two-wheeled automobile or the like—a reflector, (such as a reflective mirror) For reflecting light emitted from a light source (such as an electric bulb) to convert the light to what is emitted outside, is disposed in such a manner as to embrace the light source.
The reflector, in a substantially cup (parabolic) form, has an opening oriented to a front lens. There flector is formed with an aluminum metallized film functioning as a reflective surface on the surface layer of synthetic-resin base material mainly made of BMC (Bulk Molding Compound). Further, a protective film, for preventing deterioration of the aluminum metallized film, is formed on the surface layer of the synthetic-resin base material.
In view of environmental problems resulting from the spillage of organic solvents and attempts to reduce raw material cost, a method of forming a silicone polymerized film on each of the base materials is increasingly employed. The method uses a plasma source—by way of a high-frequency induction discharge, a glow discharge, or the like—in place of a technique of forming a protective film by coating, in order to reduce a steamy silicone oil to plasma.
However, such a method still presents the following technical problem, namely, that aluminum metallized films and plasma polymerized films are formed on both sides of synthetic-resin base materials.
First, when a ‘rotating and revolving metallizing system’ is used, the steps of forming aluminum metallized films and plasma polymerized films will have to be followed separately. Separate steps are necessary because the ‘rotating and metallizing system’ is specifically designed for forming metallized films by disposing a plurality of base materials so as to respectively face aluminum metallizing sources arranged along the central axis of a large cylindrical chamber, and then for causing the base materials to rotate on the aluminum metallizing sources. For this reason, these processing steps—for forming metallized films and for forming polymerized protective films—are multi-staged and necessitate a step of conveying the base materials when one step is shifted to the other. Moreover, as the rotating and revolving system is equipped with a rotating mechanism, as an aluminum metallizing system, it is complicated in construction.
There is also known an antenna-type plasma polymerizing system for forming aluminum metallized films and plasma polymerized films in one large chamber. In the antenna-type system, plasma is generated by way of a high-frequency oscillation antenna within a chamber so as to polymerize monomers introduced into the chamber. With the use of such a system, it is possible to form aluminum metallized films and plasma polymerized films through a series of operations.
However, the drawback of the antenna-type system is that: it is a batch production system wherein a large number of predetermined base materials are disposed in a chamber and, after a predetermined time (about 40 minutes) for forming metallized films and plasma polymerized films elapses, all of the base materials are taken out of the chamber; a lead time, necessary for disposing the base materials in the chamber is long; and when any poor quality is found in the relevant lot, many of the base materials will also be found poor in quality.
An additional problem is that the formation of plasma polymerized films by the antenna-type system results in low plasma density in general, and causes not only slow film formation but also uneven film distribution.
The aluminum metallized film sometimes is utilized as a noise shield (electromagnetic shield) when formed on the back surface of a reflector that is used in a discharge headlamp. The problem in this case is, technically, that when a plasma polymerized film (silicone polymerized film) is also formed on the aluminum metallized film on the back surface of the reflector, as in the antenna-type system, the aluminum metallized film may not be grounded.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a film forming technique so devised that aluminum metallized films and plasma polymerized films are formed through a series of lined-up steps, and so that a protective film (silicone polymerized film) is not formed on the back surface of any reflector base material, whereby a protective film may easily be formed even on a reflector to be utilized in a discharge headlamp.
In order to accomplish the above and other objects, the following aspects of the invention are adopted.
In a first aspect of the invention, a plurality of synthetic-resin base materials are placed at predetermined intervals in a frame—like case via jigs. Further, an aluminum metallized film is formed on both sides of each one of the synthetic-resin base materials, and a protective film is formed on the upper layer of the aluminum metallized film, by moving the case by a conveyer, for example, successively through an aluminum metallizing chamber and a plasma polymerized film forming chamber.
With this arrangement, one only needs to install each synthetic-resin base material onto an upwardly-open case. Therefore, the work required to set the base materials can be simplified, and the lead time can also be shortened.
The steps—of forming metallized aluminum and plasma polymerized, films—that have heretofore been separately followed can now be performed in series, whereby the work of conveying synthetic-resin base materials from the aluminum metallizing stage to the plasma polymerized film forming stage can be omitted, which further shortens the lead time.
Further, because the films are formed as the case is passed laterally through an aluminum metallizing chamber and a plasma polymerized film forming chamber, a complicated mechanism for rotating base materials in any metallized-film forming unit can be dispensed with.
A preliminary vacuum chamber, for forming a low vacuum condition in preparation for the metallizing step, is provided in front of the aluminum metallizing chamber, and is kept in a high vacuum condition. Another preliminary vacuum chamber, for returning the high vacuum condition to a low vacuum condition, is provided in the rear of the plasma polymerized film forming chamber.
Moreover, because it is necessary to secure surface smoothness of each base material before the aluminum metallizing step, the surface smoothness of the base material must be secured by providing an undercoat to the synthetic-resin base material, or otherwise devising a special base material.
According to the invention, installation of the case is simplified, even when the undercoat layer is provided to each synthetic-resin base material before the aluminum metallizing step. That is, while one holds the back side (rear top portion side) of the synthetic-resin base material without touching the undercoat layer, it can be moved from the undercoat process to the case in which it will be metallized.
Incidentally, the invention is widely applicable to, for example, fo
Koito Maunfacturing Co., Ltd.
Pianalto Bernard
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