JPH01119662A - Manufacturing method of organic thin film - Google Patents

Abstract

PURPOSE:To manufacture a thin film of organic matter free from pinholes and having superior adhesive strength to a substrate by forming a film of an organic matter on a substrate by a vacuum vapor deposition method and then heating the resulting film under specific conditions. CONSTITUTION:In a vacuum chamber of <=about 10<-2>Torr, preferably about 10<-6>-10<-2>Torr, degree of vacuum, an organic matter 1 (e.g. PTFE, PPS) material held in an evaporation cell 2 is heated to the prescribed temp. by means of a heater 3, by which the above organic matter 1 is evaporated and deposited onto the surface of a substrate 4 disposed in a manner to be opposed to the evaporation cell 2 to undergo film formation. At this time, it is desirable that film formation is carried out while keeping the temp. of the above substrate 4 at room temp. so as to prevent the reevaporation of the thin vapor-deposited film. The resulting thin film of <=1mum thickness formed on the substrate 4 is heated under >=10<-4>Torr pressure within a temp. range of (the melting point of the above organic matter 1) + or -50 deg.C. By this method, the dense thin film of organic matter excellent in adhesive strength to the substrate 4 and free from pinholes can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing organic thin films using vacuum evaporation, and more particularly, to methods for producing organic thin films on substrates such as metals, ceramics, other inorganic materials, or organic materials. The present invention relates to a method for producing a thin film of an organic material that has desired properties and excellent adhesion to a substrate.

BACKGROUND OF THE INVENTION It is a well-known technique to form thin coatings of various organic materials on solid surfaces to provide surface properties similar to those of the organic materials. Conventionally, various methods have been used to form a thin film of organic material on a substrate, such as solution coating method, thermal spraying method, plasma polymerization method, electric field separation method, vacuum evaporation method, sputtering method that is a further modification of vacuum evaporation method, and ion blating method. method is known. Although each of these methods has its own unique advantages, on the other hand, there are many drawbacks, and many research problems remain to be solved technically.

For example, the solution coating method is a method in which a solution of a polymeric substance is applied onto a substrate and then the solvent is dried and removed to form a film of the polymeric substance, and is a simple method that has been used in the past. , the need for post-treatment of drying the solvent, and the environmental hygiene problems associated with evaporation of the solvent;
There are drawbacks such as the tendency to cause uneven film thickness such as foaming and avatars, and furthermore, it is difficult to improve the adhesion to the substrate.

As a method that does not use solvents, there is a thermal spraying method in which thermoplastic resin is melted with high-voltage arc sparks and sprayed onto the substrate to form a coating layer, but this method tends to contain pinholes during film formation and does not produce a dense film. The disadvantage is that it is difficult to form.

The plasma polymerization method is a method in which a monomer gas is supplied as a raw material into a plasma atmosphere to form a polymer film on a substrate. For example, the substrate is placed on an electrode inside a plasma reaction chamber, When a high frequency wave is applied between the electrode and the counter electrode while flowing tetrafluoroethylene (TFE) at a pressure of 0.47 orr, the TFE is excited to generate plasma and form a polymer on the substrate surface. Although this plasma polymerization method can form a thin film with relatively high adhesive strength, it is difficult to control the polymerization reaction.
Another drawback is that it is not possible to form a polymer substance with a regular molecular structure.

Recently, to overcome the shortcomings of these thin film manufacturing techniques,
A method has been proposed to form a VJ film using an electric field separation method that extracts the organic material as particles while controlling the decomposition of the organic material as a raw material. has the disadvantage of insufficient adhesion to the substrate.

Incidentally, a vacuum evaporation method is known as a method for producing a thin film in a gas phase. The vacuum evaporation method is a method in which a material is heated and evaporated in a vacuum chamber, and deposited as a thin film on a substrate. When applying this method to forming thin films from organic materials, there is a method of heating the substrate in order to improve adhesion to the substrate, but if the film is formed while heating the substrate, re-evaporation of precipitates may occur. There is a drawback that the film formation rate is slow.

Problems to be Solved by the Invention The purpose of the present invention is to improve the shortcomings of conventional methods for forming organic thin films, and to provide a method for producing organic thin films that are free from pinholes and have good adhesion to a substrate. Our goal is to provide the following.

More specifically, an organic thin film is formed on a substrate using a vacuum evaporation method, and the formed film is heated and melted in a vacuum or under pressure to improve adhesion to the substrate.
The object of the present invention is to provide a method for manufacturing a dense organic thin film without pinholes.

The gist of the present invention is to form a film of a raw material organic material on a substrate by a vacuum evaporation method, and then heat the organic material at a temperature of 50°C above or below the melting point of the organic material under a pressure of 10-4τart or more. A method for producing an organic thin film characterized by heating at a temperature within the range of .

Hereinafter, the constituent elements of the present invention will be explained in detail.

(Vacuum evaporation method) The vacuum evaporation method used in the present invention is a method in which a raw material is heated in a vacuum, evaporated, and deposited in the form of a film on a substrate. Method 1: For example, when polytetrafluoroethylene (hereinafter abbreviated as PTFE) is heated to 500°C or higher at a pressure of 1 x 10-6 to 10-4 Torr, PTFE depolymerizes and evaporates, and its vapor is is repolymerized on a cold substrate in the system to 0.1~
A thin film with a thickness of about 0.5 Pm is formed. in this way,
Vacuum deposition methods disperse materials in the form of atoms and molecules.

This is a method of forming a film. Further, vacuum evaporation methods include methods such as resistance heating evaporation, electron beam evaporation, and laser evaporation depending on the heating source.

In the present invention, the degree of vacuum is desirably less than I 0-27 or τ, and a range of 10-6 to 10-2 τ is particularly suitable.

In the present invention, since a vacuum evaporation method is used, a thin film of organic matter having a thickness of 1Bm or less can be easily manufactured.

In the present invention, the film obtained by the vacuum evaporation method is heated in the air or vacuum to a temperature around the melting point of the raw organic material to melt it, thereby improving the adhesion with the substrate and making it possible to form pinholes. Form a dense thin film with no cracks. Furthermore, since it is not necessary to heat the substrate during vacuum deposition in order to improve the adhesion of the thin film, re-evaporation of precipitates does not occur and the film formation rate does not slow down.

The method of the present invention will be explained in more detail with reference to the drawings.

FIGS. 1 and 2 are diagrams schematically showing an example of an apparatus used in the manufacturing method of the present invention.

In Figure 1, the evaporation cell (2) is a raw material organic material (1
) is stored and heated by a heater (3). The substrate (4) is placed opposite to and above the evaporation cell. The substrate (4) is held by a suitable support device 1
Usually, these evaporation cells and substrates are placed in a position where the molecules evaporated from the organic substance into the gas phase and released are likely to precipitate.Although not shown in the figure, these evaporation cells and substrates are placed in a vacuum chamber.In this case, The inside of the vacuum chamber is 10-2T as mentioned above.
orr or less, preferably I x 10-6 to 10-2T
The vacuum is kept at about 10.0 m or more, and there is no need to raise the temperature of the substrate; room temperature is sufficient.

Molecules of the organic substance evaporated into the gas phase and liberated are deposited on the substrate to form a thin film. The time for vacuum deposition depends on the desired thickness of the organic thin film deposited on the substrate, but is usually 2.
It takes about 0 to 60 minutes. Of course, these operating conditions can be modified as appropriate by those skilled in the art, depending on the type of organic substance used, desired surface characteristics, etc.

Next, the precipitate of organic material deposited on the substrate is 10-
Under a pressure of 4 Torr or more, preferably 1o-4 to 10i
It is subjected to heat treatment under a pressure of about Torr. The reason why the heat treatment is performed under a pressure of 10 −4 Torr or higher, which may be under atmospheric pressure, is to avoid re-evaporation of precipitates. The heating temperature needs to be within a range of 50° C. above and below the melting point of the raw organic substance. At low temperatures below this range, the effect of heat treatment on imparting adhesion will be poor, and at too high a temperature, the precipitated organic substances will decompose or re-evaporate, both of which are unfavorable. , about 1 to 5 minutes is sufficient.

In the present invention, this heat treatment is used to bake a thin film made of an organic substance onto the substrate and make it strong.

By the method of the present invention, organic thin films can be continuously produced. FIG. 2 is an example showing a method for continuously producing an organic thin film.

The continuous film forming apparatus shown in the second drawing consists of a film forming chamber (5), a heat treatment (baking) chamber (6), and a differential exhaust chamber (13). ) is configured to be continuously supplied from the film forming chamber to the baking chamber using a winder. A differential pumping chamber (13) adjusts the degree of vacuum in the film forming chamber and the baking chamber to a predetermined atmospheric pressure, respectively. Organic substances stored in the evaporation cell (7)
is heated by a heater (9). The evaporated organic substance is deposited on the surface of the substrate (lO).Then, the substrate with the thin film of organic substance sent to the baking chamber (6) is heated by a heater (12).

(Organic Substance) The organic substance used in the present invention includes many substances that have been conventionally used in manufacturing thin films of organic substances, and is not particularly limited. It can be suitably applied to. Among them, if polymers with particularly excellent heat resistance, water repellency, and moisture resistance are used, such as polyphenylene sulfide, polytetrafluoroethylene, and poly-4-methylpentene-1, it is possible to coat them on the substrate surface. This is preferable because it can impart the characteristics that organic substances have.

(Substrate) Various solid materials may be used as the substrate, including various metals such as stainless steel plates and aluminum foil, and plastics. The shape of the substrate is not particularly limited.

(Organic substance thin film) The organic substance S film obtained on the substrate by the production method of the present invention is
It has a thickness of about 0.1 to 5 pm, and is a dense film without pinholes or bubbles. Moreover, this thin film has excellent adhesion to the substrate.

and 1, for example, polytetrafluoroethylene (PTF
The substrate coated with the thin film E) exhibits water repellency comparable to that of PTFE, and is dense and moisture-proof. As described above, by providing a film of an organic substance on the surface, the characteristics of the organic substance can be imparted to the surface of the substrate (various solid articles). It can be used in a wide range of industrial fields.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited only to these Examples.

Example 1 As shown in Figure 1, the raw material organic material had a melting point of 27.
Polyphenylene sulfide (hereinafter abbreviated as PPS) at 0° C. is used and held in a raw material evaporation cell (2). After setting the inside of the vacuum chamber to 10 −4 Torr, the raw material evaporation cell is heated to 300° C. using a heater (3).

An aluminum foil (4), which is a substrate (4), was placed facing this raw material evaporation cell, and after 15 minutes, the film thickness on the aluminum foil was 5000A.
A thin film of PPS was obtained.

This substrate was taken out into the atmosphere and heated to 280°C on a heater, and then an adhesion test was performed using a peeling tape, and the number of peeled pieces was 0/100 (pieces). It can be seen that the material has excellent adhesion to the substrate.

Here, the adhesion test was conducted as follows. First, 100 base holes of 1 mm square are made on the R film using a knife or cutter. Apply peeling tape firmly to the entire base, and then remove the tape.
It was determined how many base layers were peeled off by the tape.

Comparative Example 1 A PPS thin film was created under exactly the same conditions as in Example 1, except that no heat treatment was performed in the atmosphere. When the adhesion of this PPS thin film before heating in the atmosphere was examined using peeling tape, the results were as follows: Zoo/Zoo (bond)
The adhesion was extremely poor.

Example 2 An organic thin film was continuously produced using the continuous film forming apparatus shown in FIG. 2. This apparatus is equipped with a film forming chamber (5) and a baking chamber (6) as described above. . Polytetrafluoroethylene (hereinafter abbreviated as PTFE) with a melting point of 315° C. is used as the raw material organic material, and is held in a raw material evaporation cell (8), which is connected to a heater (9).
to evaporate the PTFE. At this time, the aluminum foil serving as the substrate (lO) is placed facing the raw material evaporation cell, moved at a speed of in/min, and continuously supplied from the film forming chamber to the baking chamber. The baking chamber is kept at 350°C, and the aluminum foil is continuously wound up by the winder (11).The vacuum degree of the film forming chamber is 10-4 Torr.
The temperature of the baking chamber was set at 10-3 Torr.The PTFE III thus produced had a thickness of about 500 OA, had good water repellency, and had good adhesion to the substrate.

Effects of the Invention By the method for producing an organic thin film of the present invention, it is possible to obtain a dense organic thin film without pinholes, which has much better adhesion to a substrate than conventional methods.

(Margin below)

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams schematically showing an example of an apparatus used in the manufacturing method of the present invention. 1. Raw material organic substance 8. Evaporation cell 2, evaporation cell 9. heater 3, heater 1
0. Substrate 4, substrate 110 winder 5, film forming chamber
12. Heater 8, baking chamber 1
3. Differential exhaust chamber 7, raw material organic material

Claims (2)

[Claims] (1) After forming a film of a raw material organic material on a substrate by a vacuum evaporation method, it is heated at a temperature within a range of 50° C. above and below the melting point of the organic material under a pressure of 10 −4 Torr or more. Method for producing organic thin films. (2) The method for producing an organic thin film according to claim (1), wherein the substrate temperature during film formation is maintained at room temperature.