JP3859271B2 - Manufacturing method of multilayer reflective film by laser deposition - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a reflective film by a laser vapor deposition method.
[0002]
[Prior art and its problems]
Conventionally, multilayer reflection films having various film configurations have been studied on the assumption that it is effective to use aluminum (Al) as a reflection film for reflecting light such as laser light.
As a reflective film using this aluminum (Al), for example, as a practical technique, an acrylic resin is coated on a plastic substrate, this is cured by ultraviolet (UV) irradiation, and further treated with hot air to form a polymer base film. An aluminum reflecting film is formed thereon by vapor deposition, and finally, a protective film is provided by coating a transparent acrylic resin as a surface layer. For this reflective film, it is known that a plastic resin can be used as a substrate, and that the manufacturing process is relatively simple.
[0003]
However, there is a big problem with the structure of the conventional reflective film and the manufacturing method thereof. First of all, when a base film is formed on a plastic substrate by resin coating, since the substrate surface is not smooth, the degree of adhesion between the substrate surface and the coating film is not so high. There was a problem that interface deterioration due to heat caused by light reflection at the time of use was likely to occur, and peeling was easy. The same thing has the problem that it cannot be avoided even between this base film and an aluminum (Al) reflective film.
[0004]
Second, the transparent resin film as a protective film disposed on the aluminum reflective film has a problem in the adhesion strength between the aluminum reflective film and the abrasion resistance of the resin film. However, there is a serious problem in heat resistance, and further, it has been a serious problem that deterioration due to heat during use of the reflective film is inevitable.
In order to deal with the above problems, for example, it is conceivable to replace the resin film formation with a vapor deposition method instead of the coating method. However, the film formation efficiency and uniformity of the film formation and the dense structure of the film formation are also considered. However, the surface protective film is also a resin film, and has problems in terms of heat resistance, weather resistance, durability, and the like.
[0005]
Therefore, the present invention eliminates the above-described problems of the prior art, and is a new aluminum multilayer reflective film that has excellent adhesion strength, heat resistance, durability, etc. as a reflective film for laser light and the like, and also has good productivity. The object is to provide a manufacturing method.
[0006]
[Means for Solving the Problems]
This invention provides the manufacturing method of the multilayer reflecting film by the laser vapor deposition method characterized by performing the following process sequentially as what solves the above subjects.
<1> Laser deposition of polysiloxane is performed on the substrate surface.
<2> A smooth film is formed by heat treatment.
<3> An oxygen radical is introduced and laser deposition of polysiloxane is performed to form a flat and hard film.
<4> An aluminum film is vacuum deposited on the base film formed as described above.
<5> An oxygen radical is introduced to perform laser deposition of polysiloxane to form a cured product protective film.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the present invention is essentially characterized by forming a polymer film as a base film by laser vapor deposition and forming a cured product protective film as a surface protective film.
FIG. 1 shows the process of the present invention. The laser deposition process of FIG. 1 is performed by a technique such as acrylic resin coating in the conventional example.
[0009]
That is, as shown also in FIG. 1, a resin substrate as a base, for example, from various types of resins such as polycarbonate, polyacrylate, polyolefin, polysulfone, polyester, polyamide, polyimide, or further metal or composite A polymer base film is formed by laser deposition on a flat, spherical, or aspherical substrate selected from materials and the like according to the purpose and application.
[0010]
Also for the polymer undercoat at this time, various materials such as polyolefin such as polypropylene, poly (meth) acrylate and polysiloxane are used as raw materials for laser deposition.
After the base film is formed by laser deposition, aluminum is deposited to form a reflective film.
[0011]
Subsequently, a polymer cured product protective film is formed by laser vapor deposition using polysiloxane as a raw material.
Regarding the formation of the base film in the above steps, it is very difficult to realize a flattened hard base film with a single film on a rough resin substrate. It is also effective to use the same apparatus to form a functional gradient. That is, for example, a polymer film having a reflow property is first formed by laser-depositing polymers having different compositions stepwise on an aspherical resin substrate (having large irregularities) having a surface roughness. Then, the hardness of the film is gradually increased to form an optically smoothed base film with a functionally gradient polymer film. It is also effective to anneal after film formation.
[0012]
In the present invention, it is recommended as one of the more specific embodiments that the base film be formed by laser deposition of polysiloxane.
In the case of this polysiloxane, a film having reflowability is first formed by laser vapor deposition, and then a hard film is deposited by laser vapor deposition while introducing oxygen radicals. As a result, a gradient functional base film is formed.
[0013]
Of course, various other modes are possible.
In addition, the formation of a cured film as a protective film is one of the major features of the method of the present invention. In this method, polysiloxane as a target is hardened by laser vapor deposition in the presence of oxygen radicals. An important finding by the inventor of the present invention that it is possible to produce a high-molecular-weight polymer having a dense structure and a silicon oxide film having inorganic physical properties. Based on.
[0014]
There are no particular restrictions on the thickness of the base film, the aluminum reflective film, and the cured product protective film. Usually, each of them is in the range of several hundred to several thousand, and if necessary, it can be formed as a thicker film.
Hereinafter, examples will be shown, and the embodiments of the present invention will be described in more detail.
[0015]
【Example】
Example 1
Laser deposition was performed on a heat-resistant polycarbonate resin substrate having an aspherical curved surface using polysiloxane. As film formation conditions, the substrate temperature was room temperature, the laser output: 5-10 W, the polysiloxane raw material was heated and evaporated, and vapor deposition was performed at a vacuum pressure.
[0016]
Since the polysiloxane raw material has a relatively low evaporation temperature, a higher deposition rate (200 to 300 nm / min) is obtained than other resin raw materials. The obtained film had good adhesion to the substrate and weather resistance / humidity resistance, but the film strength was not always sufficient, and it was a relatively soft film. It softened at almost the same temperature and did not have heat resistance. In addition, when polysiloxane is actually applied to the formation of a reflector base film, if the base substrate surface is not flat, the film formed only by laser deposition largely reflects the unevenness of the base substrate, and the surface is flattened. It has also been confirmed that it becomes difficult. Therefore, heat treatment (softening temperature) was performed after laser deposition to soften the film. This utilizes the fact that reflowability is very good. This is shown by using a substrate simulating irregularities as a base substrate, which is a cross-sectional photograph of the film after laser deposition of polysiloxane (before heat treatment) in FIG. 2, and the film after heat treatment in FIG. FIG. It can be seen that the reflow property is good. Therefore, the surface of the substrate is actually not flat, that is, a smooth film can be formed by forming a film having a good reflow property on a substrate having a rough surface and performing a heat treatment.
[0017]
Next, oxygen radicals were introduced onto the heat-treated film and laser deposition of polysiloxane was performed to form a flat and hard film. The laser vapor deposition by introducing oxygen radicals at this time can be performed by the apparatus and method shown in Example 3 described later. By this vapor deposition, a hard film having a high molecular weight was obtained, and even when heated to 400 ° C. or higher, there was no change, and a base film that was hard and heat resistant and excellent in surface flatness was obtained.
[0018]
Thus, by controlling the amount of oxygen radicals injected during laser deposition of polysiloxane, a film can be formed functionally and a flat base film can be formed on a rough substrate having irregularities. .
Next, an aluminum (Al) film as a reflective film was formed on the obtained base film by a known vacuum deposition method. The aluminum reflective film can be produced by sharing the apparatus main body in laser vapor deposition and evaporating aluminum by heating resistance or the like instead of laser irradiation.
(Example 2)
Instead of laser deposition of polysiloxane in Example 1, polypropylene was laser deposited.
[0019]
In this case, the film was formed at a deposition rate of 10 nm / min or less. Heat treatment after film formation and laser vapor deposition by introducing oxygen radicals were not performed.
Although it was not always sufficient in terms of heat resistance and film strength, a base film having good adhesion to the substrate and surface flatness was obtained.
Similarly, an aluminum reflecting film was formed on the polypropylene laser deposition film.
Example 3
On the aluminum film of the multilayer reflective film obtained in Example 1, polysiloxane was laser deposited to form an oxide protective film.
[0020]
FIG. 4 illustrates the configuration of a film forming apparatus for that purpose.
Polysiloxane was disposed on the target in the chamber, and the multilayer film as a substrate was disposed thereon.
For polysiloxane, a resinous material having a softening temperature of 80 to 90 ° C. was used, and a film was formed under the same deposition conditions.
[0021]
A microwave and oxygen are supplied to a quartz tube inserted from the side of the chamber in FIG. 4, oxygen plasma is generated in the quartz tube, oxygen radicals are introduced into the surface of the substrate, and the substrate is heated using a lamp. Then, the film was formed by irradiating the target surface with cw-CO ₂ laser light through the mirror and the ZnSe window from the upper part of the chamber.
[0022]
FIG. 5 shows the substrate temperature dependence of the deposition rate when film formation is performed while changing the substrate temperature under a laser output of 10 W, an oxygen pressure of 50 mTorr, and a microwave power of 100 W. FIG. The substrate temperature dependence of the elemental component ratio of the generated film is shown. FIG. 5 shows a decrease in the deposition rate with an increase in the substrate temperature, and FIG. 6 shows a decrease in the carbon component (C) of the generated film with an increase in the substrate temperature. Further, as a result of measuring the molecular weight of the film, when laser deposition was performed with the substrate temperature being close to the raw material softening temperature, the resulting film was polymerized with a molecular weight 20 times higher than the molecular weight of the raw material of about 2100. It was a film.
[0023]
From these results, the product film obtained by laser vapor deposition is controlled by controlling the substrate temperature and the amount of oxygen radical injection, so that a soft polysiloxane film having a reflow property is changed to a hard polysiloxane polymer film, and further a carbon component. It can be seen that when the substrate temperature is equal to or higher than the softening point of the raw material, it can be transferred to a silicon oxide film with a small amount.
[0024]
The polysiloxane laser vapor deposition film has good adhesion to the underlying substrate, and when oxygen radicals are introduced to form an oxide film, not only the adhesion but also the film strength is greatly improved. The same was true when the underlying substrate was replaced with Al. Further, the hard protective film obtained by oxygen radical injection is invariable even in a temperature environment of 400 ° C. or higher, has sufficient heat resistance, and is practically satisfactory. Furthermore, as illustrated in FIG. 7, the optical transmission characteristics of the protective film showed a high transmittance exceeding 90% (visible light region).
[0025]
【The invention's effect】
As described above in detail, the laser vapor deposition method in which oxygen radicals are introduced according to the present invention makes it possible to produce a reflecting mirror protective film having excellent properties such as adhesion and heat resistance. A very effective and practical method is provided as a new method for manufacturing a reflective film in combination with the formation of a flattened base film.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram illustrating a process diagram of a method for producing a reflective film according to the present invention.
FIG. 2 is a photomicrograph in place of a drawing exemplifying a state after laser deposition and before heat treatment when forming a base film.
FIG. 3 is a photomicrograph in place of a drawing illustrating the state after heat treatment following the state of FIG. 2;
FIG. 4 is a diagram illustrating a schematic view of a film forming apparatus in the manufacturing method of the present invention.
FIG. 5 is a relationship diagram illustrating the substrate temperature dependence of the deposition rate.
FIG. 6 is a relationship diagram illustrating the substrate temperature dependence of the C / Si ratio.
FIG. 7 is a relationship diagram illustrating the optical transmission characteristics of the outermost cured product protective film.

Claims (1)

The manufacturing method of the multilayer reflective film by the laser vapor deposition method characterized by performing the next process sequentially .
<1> Laser deposition of polysiloxane is performed on the substrate surface.
<2> A smooth film is formed by heat treatment.
<3> An oxygen radical is introduced and laser deposition of polysiloxane is performed to form a flat and hard film.
<4> An aluminum film is vacuum deposited on the base film formed as described above.
<5> An oxygen radical is introduced to perform laser deposition of polysiloxane to form a cured product protective film.

Images