JP3427398B2 - Laminate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-modified polyester film useful in the fields of electromagnetic fields and packaging materials.

[0002]

2. Description of the Related Art Conventionally, polyester films, which have advantages of light weight, excellent mechanical strength, and excellent workability, are stably supplied at an appropriate price, and thus have been widely used in industry.

In addition, many products have been made highly functional by forming a thin film of a metal or a metal oxide on the surface of a polyester film by taking advantage of these advantages.

For example, a transparent conductive film in which a ceramic thin film made of indium oxide and tin oxide is formed on the surface of a polyester film and a gas barrier film in which a ceramic thin film made of silicon oxide is formed are put on the market. Application development and application proposals have been made in the packaging material field.

In order to put the above-mentioned film having a ceramic thin film (hereinafter referred to as a ceramic film) into practical use, it is important to firmly integrate the ceramic thin film exhibiting the function and the polyester film as the base material. is there. However, the combination of a polyester film and a ceramic thin film, that is, an organic substance and an inorganic substance is, for example,
The thermal expansion coefficient and mechanical properties differ greatly, and the combination is physically and chemically different.

Therefore, even if the ceramic thin film is directly formed on the polyester film, the adhesion is poor, so that the ceramic thin film is peeled off by a slight scratch, and the flexibility is poor, so that the ceramic thin film follows the deformation during processing or use. However, there is a drawback that cracks occur in the ceramic thin film, causing interfacial peeling between the ceramic thin film and the polyester film.

Further, during the formation of the ceramic thin film, the energy given to the surface of the polyester film causes impurities such as oligomers and solvents remaining in the polyester film to seep out to the surface (hereinafter referred to as bleed-out), An impurity layer (hereinafter referred to as WBL) is formed. WBL has a drawback that it causes a decrease in adhesion between a ceramic thin film and a polyester film, and causes interfacial peeling.

In order to make up for this drawback, for example, a polyester film having a modified layer formed by coating a resin (organic substance) and a silane coupling agent (inorganic substance) separately or in a mixture (Japanese Patent Publication Nos. 62-29226 and 59-59). -1334
No. 1, JP-B 2-130139, etc.) and a polyester film having a modified layer coated with a thermosetting resin (organic material) (JP-B-63-25614, JP-A-61-162).
No. 337) has been proposed.

However, the above conventional technique has the following problems. In the case of a modified layer that is applied by organic substance alone or by mixing organic substance and inorganic substance separately or as a mixture, the smoothness of the surface is incomplete and unevenness occurs on the surface after the ceramic thin film is formed, resulting in peeling. And so on.
Further, in the coating method, it is difficult to provide a highly polymerized and highly crosslinked modified layer, and the modified layer lacks denseness. Therefore, WB due to bleed-out of residual impurities in the polyester film
L cannot be prevented from occurring. Therefore, due to the generation of WBL, the adhesion between the ceramic thin film and the polyester film cannot be sufficiently improved. Furthermore, the modified layer is W
It may become a source of BL.

Further, in the case of a modified layer obtained by mixing and coating an organic substance and an inorganic substance, the adhesiveness at the interface with the polyester film is not sufficient, and an attempt is made to improve the adhesiveness by providing a mixed layer of the organic substance and the inorganic substance at the interface. However, it is difficult to provide a uniform treated surface, and the adhesiveness at the interface between the polyester film and the modified layer varies.

From the above circumstances, it is extremely difficult to obtain a ceramic film excellent in adhesion and flexibility by using the conventional polyester film whose surface is modified.

[0012]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the problems of the above-mentioned known polyester film, and a thin film made of various metals or metal oxides is formed to provide adhesion and flexibility. It is an object of the present invention to provide a surface-modified polyester film that makes it possible to obtain a highly functional ceramic film.

[0013]

The invention according to claim 1 is
A ceramic thin film is formed on a surface-modified polyester film characterized in that it has a polymer layer containing Si in a structural unit and formed by a plasma polymerization method on at least one side of a plasma-treated polyester film.
It is a laminated body characterized by being laminated .

According to a second aspect of the present invention, the surface of the polymer layer is oxidized, and the surface oxidation state is SiO 2.
_The ceramic thin film is laminated on the surface-modified polyester film according to claim 1, which is _1.5 or more .
It is a laminated body characterized by the above.

[0015]

According to the first aspect of the present invention, the surface-modified layer of the surface-modified polyester film is an organic-inorganic composite in which the polymer layer contains Si in its structural unit. That is, a layer having properties close to those of ceramics and having both mechanical properties of the ceramic thin film and the polyester film formed in a later step is present. Therefore, the polymer layer plays a role as a cushioning material, so that the ceramic thin film can be prevented from being broken when the polyester film is bent.

Further, since the polymer layer is formed by the plasma polymerization method, the layer itself is highly crosslinked and dense, and is excellent in mechanical strength. Therefore, bleeding out of residual impurities such as oligomers and solvents generated from the polyester film can be considerably prevented. Further, since a chemically strong bond is formed at the interface with the polyester film, the adhesion is good. Further, the plasma polymerization method has a wide selection range of monomers and polymerization conditions and is excellent in structure controllability, so that a polymer layer having arbitrary mechanical properties can be obtained.

According to the second aspect of the present invention, the surface of the polymer layer is further oxidized to increase the amount of siloxane bonds, so that the gas barrier property is excellent and bleed-out can be prevented. That is, it is possible to suppress the occurrence of WBL that deteriorates the adhesion of the ceramic thin film. Furthermore, since a surface having the same level of thermal expansion coefficient and elastic modulus as the ceramic thin film to be formed in a later step can be realized, interfacial shear force due to thermal stress and internal stress does not occur, and the adhesion of the ceramic thin film is secured. It

The present invention will be described in detail below. The polyester film referred to in the present invention is a polyester that can be melt-molded and stretched, and typical examples thereof include polyethylene terephthalate alone and a crystalline copolymer or mixed polymer mainly containing polyethylene terephthalate.

Further, in the present invention, a polymer layer containing Si in a structural unit and formed by a plasma polymerization method on at least one surface of the polyester film as described above (hereinafter simply referred to as a polymer layer). Have.

The plasma polymerization method used for forming the polymer layer is a method in which a raw material gas is introduced into a vacuum container and the film-forming particles activated by electric energy are subjected to polymerization / film-forming. As a method for generating plasma, a DC or AC power source is used and energy in a high frequency band or a low frequency band is applied. Further, in order to increase the density of plasma, various means such as applying a magnetic field are added. In the present invention, the method of generating the plasma state is not limited as long as the raw material gas can be excited in a vacuum to carry out the polymerization.

In the plasma polymerization method, the chemically activated film-forming particles are used for the polymerization, so that the obtained layer has a three-dimensionally highly crosslinked and dense structure and is excellent in mechanical strength. Therefore, bleed-out of residual impurities can be considerably prevented. Further, it is considered that during plasma polymerization, the surface of the polyester film also becomes chemically active due to the influence of plasma. Therefore, a chemically strong bond is formed between the film-forming particles and the surface of the polyester film, and the effect of increasing the adhesiveness between them is expected. Further, with respect to the raw material gas, a polymerization initiator and the like are not necessary, and therefore, one of the advantages is that the selection range of the monomer is wider than that in the usual liquid phase polymerization.

In the present invention, the polymer layer must contain Si in the structural unit. As a raw material gas for forming such a polymer layer, in principle, all organosilane-based substances can be used. It is also possible to use them in combination with two or three types. Particularly, when it is desired to impart flexibility to the polymer layer to be formed, a monomer having a vinyl group may be used, or when imparting heat resistance, a monomer having a benzene ring may be used.

Further, the thickness of the polymer layer may be such that the uniform layer adheres to the surface of the polyester film with a chemical bond and is flexible enough to follow the bending of the polyester film. ~ 2500Å
The degree is desirable. If it is too thin, the uniformity of the layer is insufficient, and if it is too thick, the internal stress of the layer itself causes cracking or peeling of the layer, which is not preferable.

Further, in the invention according to claim 2, the surface portion of the polymer layer on which the ceramic thin film is formed is oxidized so as to have characteristics closer to those of the ceramic thin film, and the amount of siloxane bond is the most on the surface of the polymer layer. Control to increase. As a method for this, a method of oxidizing the surface in the plasma space after forming the polymer layer is conceivable, but unevenness may occur in the oxidation state depending on the conditions. Is particularly preferable.

That is, oxygen is mixed with the raw material gas for forming the polymer layer to control the amount and energy of plasma to continuously control the oxidation state on the surface of the polymer layer. According to this method, a layer having a uniform surface oxidation state can be obtained, and the composition controllability in the thickness direction is excellent. Furthermore, not only the composition of the polymer layer, but also the mechanical properties can change continuously. This suggests that the polymer layer can follow the bending of the polyester film and has excellent adhesion, which is consistent with the gist of the present invention.

The thickness of the oxidized portion of the polymer layer may be about 5 to 100 Å. With such a thickness, bleeding out of residual impurities from the polyester film can be prevented. If the surface oxidation state is SiO _1.5 or more, the effect of preventing bleeding out of residual impurities is practically sufficient. If the entire polymer layer is completely oxidized, the flexibility will deteriorate.

The oxidation state of the polymer layer can be examined by X-ray photoelectron spectroscopy in combination with depthwise etching. A surface-modified polyester film with a polymer layer formed was prepared by gradually increasing the amount of oxygen mixed with the raw material gas, and the cross-sectional composition of the polymer layer was investigated.The presence of silicon and oxygen on the polymer layer surface was confirmed. The binding energy spectrum peaks shown are obtained, and it can be seen that the carbon peaks gradually increase and the oxygen peaks decrease in the inner direction of the polymer layer. The composition of the polymer layer can be determined from the peak area, and the thickness of the oxidized polymer layer can be determined from the etching time and the change with time of the spectrum.

[0028]

【Example】

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of the surface-modified polyester film 1 of the present invention, in which a polyester film 2 has a polymer layer 3 on at least one surface.

A polyester film having a thickness of 50 μm (manufactured by Teijin Ltd.) was placed in a vacuum container and the pressure was reduced to 10 ⁻⁴ Pa. After that, Ar was injected to obtain 2 × 10 ⁻² Pa. Next, 100 W of RF (13.56 MHz) power was input and plasma treatment was performed for 30 seconds to generate dangling bonds on the surface of the polyester film.

Next, after stopping the injection of Ar, evacuation was carried out, and in order to form the polymer layer 2, 5 Pa of vinyltrimethylsilane was first injected, RF power of 100 W was input, and 600 Å was formed.

Thus, using the surface-modified polyester film as a base material, ITO was further formed as a ceramic thin film 4 in a thickness of 500 Å as shown in FIG. 2 to obtain a ceramic film.

The following tests were carried out in order to evaluate the flexibility, adhesion and ability to prevent the precipitation of residual impurities of the ceramic film prepared.

Bending Test A ceramic film was cut into a strip having a width of 10 mm and a length of 100 mm, wound around a stainless rod having a diameter of 10 mm, and the state of crack generation on the surface was observed. The results are shown in Table 1.

When an infinite number of cracks were generated, x, when the number of cracks was counted, Δ, when slight cracks were observed, ○; when no cracks were generated, ◎ Expressed as

[0035]

[Table 1]

Adhesion Test A ceramic film was cut into a 50 mm square, and the surface was scanned with a scratching needle using a surface property measuring instrument HEIDON-14 type (made by Haydon Co., Ltd.). The conditions are as follows.

Scratch needle: Sapphire made 0.05mmR Load: 1, 3, 5, 10 gr. Scanning speed: 25mm / min

After scratching the ceramic film under each of the above conditions, the surface was observed with a scanning electron microscope to examine the load when the ceramic thin film started to peel. The results are shown in Table 1. The larger the load, the better the adhesion.

Test for Preventing Residual Impurity Precipitation After the surface-modified polyester film was placed in an oven at 150 ° C. for 1 hour, the surface was observed with a scanning electron microscope.
The results are shown in Table 1.

When an infinite number of oligomers are deposited, it is represented by x, when oligomers are counted to a certain extent, Δ, when a small amount of oligomers is recognized, it is represented by ◯, and when oligomers are not produced at all, it is represented by ⊚. did.

Example 2 A polyester film having a thickness of 50 μm (manufactured by Teijin Ltd.) was placed in a vacuum container and 10 ⁻⁴ P was added.
The pressure was reduced to a. After that, Ar is injected to obtain 2 × 10 ^-2 P
a. Next, 100 W of RF power was input and plasma treatment was performed for 30 seconds to generate dangling bonds on the surface of the polyester film.

Next, after stopping the injection of Ar, evacuation was performed, and in order to form the polymer layer 2, vinyl trimethylsilane was first injected at 5 Pa, RF power of 100 W was input, and a film of 500 Å was formed. Further, a gas mixed with vinyltrimethylsilane 1 and oxygen 4 at a ratio of 5 Pa was injected to further form a 100 Å film. When the composition of the surface (10 to 50 Å) of this surface-modified polyester film was measured by X-ray photoelectron spectroscopy, the oxidation state was SiO _1.8 or higher.

As described above, the surface-modified polyester film is used as a base material, and further ITO is used as the ceramic thin film 50.
A 0Å film was formed to obtain a ceramic film.

The same test as in Example 1 was conducted on the ceramic film thus prepared. The results are shown in Table 1.

Example 3 The surface of the surface-modified polyester film of Example 1 was oxidized by exposing it to an oxygen plasma atmosphere. The conditions of the oxygen plasma atmosphere are
O ₂ gas pressure-2 × 10 ^-2 Pa, RF input-50 W, 10
Seconds.

The same test as in Example 1 was conducted on the ceramic film thus prepared. The results are shown in Table 1.

Comparative Example 1 A ceramic film having the structure shown in FIG. 3 is prepared. A polyester film 2 (manufactured by Teijin Ltd.) having a thickness of 50 μm was placed in a vacuum container and 10 ⁻⁴ Pa
The pressure was reduced to. After that, Ar is injected to obtain 2 × 10 ^-2 Pa.
And Next, 100 W of RF power was input and plasma treatment was performed for 30 seconds to generate dangling bonds on the surface of the polyester film.

An ITO film was formed as a ceramic thin film 4 thereon by 500 Å to produce a ceramic film.

The same test as in Example 1 was conducted on the ceramic film thus prepared. The results are shown in Table 1.

Comparative Example 2 A ceramic film having the structure shown in FIG. 4 is prepared. A polyester film 1 (manufactured by Teijin Ltd.) having a thickness of 50 μm was used as a base material, and a silane coupling agent solution was applied thereon to form a modified layer 5. ITO was deposited on the modified layer as a ceramic thin film 4 to a thickness of 500 Å to manufacture a ceramic film.

The same test as in Example 1 was conducted on the ceramic film thus prepared. The results are shown in Table 1.

As can be seen from the above table, the configuration of Example 2 gave the best results in each test item. Further, as can be seen from the comparison between Example 1 and Examples 2 and 3, it can be seen that oxidizing the surface is effective in terms of adhesion and ability to prevent precipitation of residual impurities. In the adhesion test,
Peeling occurred between the ceramic thin film and the polyester film in Comparative Example 1, and between the ceramic thin film and the modified layer in Comparative Example 2. It is considered that this is because generation of WBL could not be prevented due to the absence of the polymer layer, the strength of that portion was reduced, and strain was generated due to the coefficient of thermal expansion between the ceramic thin film and the modified layer.

[0053]

According to the surface-modified film of the present invention, the surface-modified layer of the surface-modified polyester film is an organic-inorganic compound composite in which the polymer layer contains Si in the structural unit. That is, a layer having properties close to those of ceramics and having both mechanical properties of the ceramic thin film and the polyester film formed in a later step is present. Therefore, the polymer layer plays a role as a cushioning material, so that the ceramic thin film can be prevented from being broken when the polyester film is bent.

Further, since the polymer layer is formed by the plasma polymerization method, the layer itself is highly crosslinked and dense, and is excellent in mechanical strength. Therefore, bleeding out of residual impurities such as oligomers and solvents generated from the polyester film can be considerably prevented. Further, since a chemically strong bond is formed at the interface with the polyester film, the adhesion is good. Further, the plasma polymerization method has a wide selection range of monomers and polymerization conditions and is excellent in structure controllability, so that a polymer layer having arbitrary mechanical properties can be obtained.

Further, by oxidizing the surface of the polymer layer, the amount of siloxane bonds increases, so that the gas barrier property is excellent and bleed-out can be prevented. That is, WB that deteriorates the adhesion of the ceramic thin film
Generation of L can be suppressed. Furthermore, since a surface having the same level of thermal expansion coefficient and elastic modulus as the ceramic thin film to be formed in a later step can be realized, interfacial shear force due to thermal stress and internal stress does not occur, and the adhesion of the ceramic thin film is secured. It

Therefore, by using the surface-modified polyester film of the present invention as a substrate and forming a ceramic thin film expressing various functions, it is possible to obtain a functional ceramic film excellent in adhesion and flex resistance. Becomes

[0057]

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of the layer constitution of the surface-modified polyester film of the present invention.

FIG. 2 is an explanatory diagram showing a layer structure of a ceramic film using the surface-modified polyester film of the present invention as a substrate.

3 is an explanatory diagram showing a layer structure of a ceramic film used in Comparative Example 1. FIG.

FIG. 4 is an explanatory diagram showing a layer structure of a ceramic film used in Comparative Example 2.

[Explanation of symbols]

1 Surface modified polyester film 2 polyester film 3 polymer layer 4 Ceramic thin film 5 Modified layer (prior art)

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08J ⁷ /00-7/18 B32B 18/00, 27/00-27/42

Claims (2)

(57) [Claims] 1. A surface-modified polyester comprising a plasma-treated polyester film, and a polymer layer containing Si in a structural unit and formed by a plasma polymerization method on at least one surface of the polyester film. Sera on film
A laminated body characterized by laminating Mick thin films . 2. A are surface oxidation of the polymer layer, and the surface modified polyester film of claim 1 in which the oxidation state of the surface is equal to or is SiO _1.5 or higher
A laminated body characterized by laminating ceramic thin films .