JP2537356B2 - Method for producing heat-resistant film or its analogue - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a heat-resistant film having a coating layer formed on a substrate made of polyethylene terephthalate resin, or a similar product.

[Conventional technology]

A flexible film having a thermoplastic resin as a base material or a sheet similar thereto (hereinafter collectively referred to as a film) has a high degree of freedom in design because of the flexibility provided therein. Moreover, although it has a certain degree of insulation, its use is generally limited due to insufficient heat resistance. Conventionally, among the untreated films used as a base material, polyimide (PI), polyether ether ketone (PEEK), polyether sulfide (PES), polyphenylene sulfide (PPS) have relatively high heat resistance. ), Polyparabanic acid (PP
There were films made of engineering plastics such as A) and polyarylate (PAR), but the resin itself is expensive, and more advanced processing technology is added to process this into a film, making it more expensive. It was difficult to expect that it would be used universally. Therefore, in recent years, various researches have been conducted on a film having heat resistance superior to that of an untreated film made of a base material itself, even though an inexpensive thermoplastic resin is used for the base material itself. Various such films have also been proposed.

For example, a film having a base material of a composition in which a predetermined additive is mixed with polyvinyl chloride resin (PVC), which is a typical thermoplastic resin that is inexpensive and easily available, is one of them.
However, in the method of improving the heat resistance of the base material by mixing the additive material, it is often necessary to adjust various additives by mixing them in order to obtain the target heat resistance property. It has been pointed out that the transparency and other physical properties also change significantly.

On the other hand, by forming a coating layer on a base material made of a thermoplastic resin, it may be possible to obtain a film having heat resistance characteristics that cannot be obtained by the base material itself. According to such a film, the physical properties such as transparency of the base material itself are not significantly impaired, and the coating layer may provide heat resistance characteristics that cannot be obtained by the base material itself. As a method for producing such a film, generally, a method of baking the coating layer on a base material made of a thermoplastic resin under low temperature conditions in which shrinkage and wrinkles are not likely to occur can be considered. However, since the heat resistance of a film having a coating layer correlates with the baking temperature of the coating layer, it was assumed that baking at such a low temperature would result in a relatively small degree of improvement in heat resistance.
Also, there is a heat resistant film obtained by impregnating a heat resistant resin into a sheet of heat resistant fiber or glass fiber and laminating it on an existing film, but it is thick, loses flexibility and is particularly thin. It has not been perfect for applications such as flexible printed wiring boards where flexibility is required. Therefore, it is difficult to say that the conventional film is still a sufficient heat-resistant film in any case.

[Problems to be solved by the invention]

As described above, the heat-resistant film that has been assumed in the past may have some improved heat resistance as compared with the untreated film composed of the base material itself, but it still has sufficient heat resistance. It is hard to say that other existing heat-resistant films are in terms of thickness, flexibility and cost as described above, and other physical properties are impaired when heat resistance is improved by admixture of additives, etc. There is a problem that it is still insufficient as a heat resistant film.

The present invention has been made in view of the above circumstances, even if the thin film to be the coating layer is baked at a relatively high temperature, there is no wrinkle in the obtained film and heat resistance without impairing the performance as a film. It is an object to provide a method for producing a film.

[Means for solving problems]

In order to achieve the above object, the method for producing a heat-resistant film of the present invention is a polyethylene terephthalate resin (PET)
A thin film of one or more solutions selected from polyimide resin (PI), polyamideimide resin (PAI), polyparabanic acid resin (PPA), and polyhydantoin resin (PH), or one of the above resins. Alternatively, a thin film of a solution of two or more kinds and one or more kinds selected from a phenol resin, an epoxy resin, and a melamine resin is formed, and after the thin film is dried, the base material is held between a pair of endless rotating bodies, The endless rotary member is characterized in that it is baked at a temperature of 200 to 300 ° C. by gradually widening or narrowing the interval toward the outlet side and maintaining the above-mentioned base material in a flat shape without causing slack.

〔Example〕

 Examples of the present invention will be described below.

FIG. 1 is a flow sheet for carrying out the method of the present invention, wherein 1 is a substrate feeding device, 2 is a coating solution dipping coater, 3 is a drying oven, 4 is a baking oven, 5 is a trimming device, and 6 is It is a winder. As is clear from the figure, the substrate 100 fed from the feeding machine 1 is coated with a thin film of the coating solution on one or both surfaces while passing through the dipping coater 2, and while the thin film passes through the drying oven 3. To be dried. After that, while the base material 100 is held between the endless rotating bodies 11 and passes through the baking oven 4, the thin film is baked at a predetermined temperature to form a coating layer. The film thus obtained is trimmed and then wound up by the winder 6.

In the above, the base material before entering the dipping coater 2
It is useful to increase the surface activity of the base material 100 by subjecting it to a primer treatment or corona discharge treatment, and to subject the base material 100 to an electrostatic removal treatment or a dust removal treatment in order to enhance the adhesion of the coating layer.

The base material 100 is PET, which has excellent tear strength and is highly flexible. The base material 100 is 1 to 350 μ in terms of workability.
It is desirable to have a certain thickness. If the thickness is less than 1μ, the handling will be poor, the strength will be insufficient, and the thickness will be 350μ.
If it is thicker, there is a risk that the degree of freedom in design will be insufficient. This thickness is not limited to the above range, and may be thicker if only heat resistance is pursued.

The coating agent, PI, PAI, PPA, one or more kinds of solutions selected from PH, or one or more kinds of each of the above resins and one or more kinds selected from phenol resin, epoxy resin, melamine resin and Solution is used.
The conditions required for the coating solution are varnish,
It is to be cured at a temperature of 0 to 300 ° C. and have adhesiveness to a substrate. Specifically, one of PI, PAI, PPA, PH is used alone, or two or more of PI, PAI, PPA, PH are used in combination, or PI, PAI, PPA, PH is used. When one is used in combination with one or more selected from phenol resin, epoxy resin and melamine resin, and when used in combination with two or more of PI, PAI, PPA, PH and phenol resin, epoxy resin, melamine This is a case of using one kind or a combination of two or more kinds selected from resins.

As PPA, for example, Toa Fuel Co., Ltd. product, each XT
-1, XT-4. This is a general formula Is a homopolymer or a copolymer having as a basic unit. the above
As Ar, Etc. The above PPA is N, N-dimethylformamide (DM
F), N-methylpyrrolidone (NMP) or the like as a main solvent, and a ketone solvent such as acetone, MEK or MIBK as a diluting solvent to prepare a varnish-like solution for use. PPA has heat resistance next to PI and can be suitably used as a coating agent for the heat resistant film of the present invention.

As PI, for example, Kanebo NSC Co., Ltd., trade name THERMID (IP-600) can be preferably used. This P
I is a polyisoimide oligomer having an acetylene group at the terminal and is represented by the following structural formula.

This solvent uses DMF, NMP, etc. as a main solvent and a ketone solvent such as acetone, MEK, MIBK, etc. as a diluent. As a PI, thermosetting polyimide resin such as bismaleimide / triazine resin (Mitsubishi Gas Chemical Co., Ltd., BT
Resin BT-2170) can be used.

As PAI, for example, a product surface resist therm (AI 133L) manufactured by Bayer and represented by the following structural formula can be used.

The solvent for this product is NMP, DMAC (dimethylacetamide), etc. as the main solvent and acetone, MEK, MIB as diluents.
Use a ketone solvent such as K.

As the PH, for example, Sumitomo Bayer Urethane Co., Ltd., trade name Registherm (PH20) represented by the following structural formula can be used.

Cresol, phenol and the like are mainly used as the solvent, and ketone solvents such as acetone, MEK and MIBK are used as diluents.

The phenol resin may be a straight phenol resin or a modified phenol resin. This solvent includes alcohols such as methanol and isopropanol (IPA), acetone, M
Ketones such as EK and cellosolves are used. In addition, a surfactant and a fine powder filler of organic, inorganic, or metal may be appropriately added to the coating solution as needed. Modified phenolic resins include phenolic resins such as epoxy-modified, melamine-modified, and inorganic-modified (B ₂ O ₃ , P ₂ O ₅ ). Especially, when melamine-modified or epoxy-modified phenolic resin is used, high adhesion to the substrate is achieved. Sex is secured. Of these two, the epoxy-modified phenolic resin exhibits particularly high adhesion.

When the PAI solution and the epoxy resin solution are used in combination, the adhesion of the coating layer to the substrate is improved, and the chemical resistance and water absorption are also improved. Also, the combination of the PI solution and the epoxy resin solution lowers the molding temperature.
Furthermore, when a melamine resin solution is used as a coating layer, heat resistance is improved. The above is an example, and the solution for forming the coating layer should be appropriately selected in consideration of its properties and suitable for the purpose of use of the film to be produced. Further, as the melamine resin and the epoxy resin, generally known ones are used.
Further, each of the phenol resin, melamine resin and epoxy resin may be used as a modified product or derivative.

It is desirable that the thickness of the thin film after baking is 1 to 10 μ in dry, and sufficient heat resistance and flame retardancy can be obtained even with such a thickness.

The baking temperature of the thin film formed on the base material 100 needs to be 200 to 300 ° C. However, if the baking temperature is too high, not only bleeding from the base material 100 and other physical property values decrease, but also large shrinkage and Inconveniences such as wrinkles are likely to occur and the performance as a film is impaired. The baking temperature capable of maintaining the performance as a film is 300 ° C or lower. If the baking temperature is lower than 200 ° C, sufficient heat resistance and adhesion cannot be obtained. Further, it is desirable that the baking time is set to about 0.5 to 5 minutes. Here, it should be noted that not only the temperature condition for baking is set in the above range, but also the base material 100 is held in an endless rotating body to maintain a flat shape without causing slack. Is to be done. When shape-retaining and baking are performed in this way, the base material deforms despite the heat resistance and shape retention of the coating resin formed on the surface, even though the base material is heated at a temperature higher than its melting point. Without
A high degree of smoothness is given to the film surface. In order to further enhance the smoothness of the film surface, a drum may be used to press the film from above and below.

FIGS. 2 and 3 show an example of an apparatus for maintaining the shape retention state.
It is shown in the figure. This device is composed of a pair of left and right endless rotating bodies which are formed by connecting a large number of endless clip mechanisms 10 shown in FIG.
11, 11 are attached to the base 12 so that one ends thereof or the other ends thereof can individually approach and separate from each other. As shown in FIG. 3, in the clip mechanism 10, the bracket 14 provided on the support base 13 includes a position where the claw 15 at the tip of the base material 100 sandwiches the support base 13 from the support base 13. An arm 16 is attached so as to be displaceable from a distant position, and a spring 17 for constantly urging the pawl 15 toward the pinched position side is interposed between the arm 16 and the bracket 14. The upper end portion 19 of the arm 16 corresponds to the outer peripheral portion of the control rotary plate 18 provided on the winding roller of the endless rotary body 11.

In the above configuration, when the endless rotary body 11 is rotationally driven in the direction of the arrow in the figure, the arm 16 of the clip mechanism 10 is moved to the position of the phantom line in FIG. The claw 15 swings away from the support base 13, and at other portions, the arm 16 returns to the position shown by the solid line in the figure, and the claw 15 corresponds to the support base 13. Therefore, when the base material 100 on which the thin film is formed is fed between the pair of endless rotating bodies 11, 11,
Both ends of the base material are clipped at the entrance of the device.
After being supported by 10 as shown by the solid line in FIG. 3, it reaches the outlet portion of the same device as it is, and the holding is released at this outlet portion. Here, for the base material 100 made of a thermoplastic resin that expands by heating, a pair of endless rotating bodies 11,
Make the interval of 11 gradually wider as it approaches the exit side,
Regarding the base material 100 made of a thermoplastic resin that shrinks by heating, the above-mentioned interval is gradually narrowed toward the outlet side so that the base material 100 is loosened without passing tension during passing through the baking furnace 4. Instead, the flat shape is maintained and the surface smoothness is not impaired. In FIG. 2, a case where a base material made of a synthetic resin that shrinks by heating is fed is illustrated by an imaginary line.

As described above, when the substrate is held flat and the thin film is baked, the substrate does not shrink or wrinkle, and the performance of the film is not impaired. Particularly, in the present invention, since the baking temperature is relatively high, it is significant to keep the shape of the base material flat.

 Next, an experimental example will be described.

[Experimental example]

Table 1 shows the type and thickness of the coating layer of the film produced by the method of the present invention (hereinafter referred to as the invention product), and Tables 2 to 8 show the characteristics of the invention products 1 to 7.
In addition, Table 9 shows various properties of the untreated film (hereinafter referred to as comparative product) having no coating layer having PET, PPA, and PI as a base material.

From Tables 2 to 9, the heat resistance of the invention product was significantly improved as compared with the untreated film only the PET substrate (Comparative product 1), and the coating layer had excellent heat resistance. Heat resistance is PPA even though PET is used as the base material
It can be seen that the film is approaching a film (comparative products 2 and 3) using only PI and PI as a base material. For example, the heat resistance of the invention product is about 50 ° C compared to the untreated film made of only the PET substrate (Comparative product 1) even if it is baked at 200 ° C which is the lower limit of the baking temperature condition of the present invention. Is also improving. The invention product 1 when the baking temperature is high, for example, 270 ° C. or higher
The heat resistance of ~ 7 is close to that of the untreated film consisting of PPA and PI only (Comparative products 2 and 3). From this, it is understood that the invention product achieves the upgrade of the heat resistance property with respect to the untreated film. Therefore, it is apparent that the application range of these invention products is expanded as compared with the application of the untreated film. Also, the heat shrinkage is
The PET base material itself makes it very excellent, and is comparable to engineering plastics. In combination with this and the above-mentioned tendency to upgrade the heat resistance, the invention product (for example, the invention product treated at a baking temperature of 300 ° C.) can be used in place of the engineering plastic-based film described at the beginning.

In addition, the invention product has better heat resistance as the baking temperature of the thin film is higher, the flame retardancy is equivalent to that of the comparative products 2 and 3, and the adhesion between the base material and the coating layer, solvent resistance, alkali resistance, etc. Each of the invention products is generally good, and the water absorption rate is much smaller than that of the comparative products 2 and 3. It is also found that the alkali resistance is superior to that of the comparative products 2 and 3.

By utilizing the flexibility of thermoplastic resin-based films, flexible printed wiring boards (FPCs), capacitors and transparent electrode base films, heat-resistant conductive films, liquid crystal films, IC carrier tapes. In the electronics field such as, membranes used for dialysis and diffusion, interior materials for aircraft and automobiles, nuclear power related fields, etc. Also, heat resistance and flame retardancy are required according to the usage conditions. For example, when it is used as a base film for FPC, it is exposed to a high temperature during soldering, and therefore it is required to have heat resistance and flame retardancy of about 250 ° which is the solder temperature. In order to meet this requirement, it is clear from the above table that invention products 1 to 7 baked at 270 ° C or higher can be used. By using them, the flexibility can be utilized to make FPCs on curved surface parts. There is an advantage that can be deployed. Further, the interior materials of aircrafts and automobiles are required to have flame retardancy, which is satisfied by all the invention products.

 Next, a test method and the like of each item will be described.

Adhesion: 24mm with a leather blade on the coating layer
A cellophane tape having a width is attached, and the presence or absence of peeling of the coating film when the cellophane tape is rapidly peeled off is visually observed. O indicates that there was almost no peeling. All of the invention products were not peeled off.

Solvent resistance: According to JIS C-6481 5.13, dip each in acetone, MEK, toluene and trichlene for 5 minutes at room temperature. O indicates that peeling or dissolution was hardly observed, and X indicates that peeling or dissolution of the coating film was observed and the coating film was released by rubbing. The invention product has sufficient solvent resistance, which means that it can sufficiently withstand etching treatment and the like.

Heat resistance: Cut a film with copper foil stuck on it to a size of 5 cm x 5 cm and put it in an oil bath or solder bath at each temperature shown in the table.
Soak for a second.

Flame retardance: Judgment by UL-94 VTM method.

Next, the applicant of the present invention has found that polyvinyl chloride resin (PVC), polycarbonate resin (PC), polyarylate resin (PA
We proposed a heat-resistant film in which a base material selected from R) and PET was coated with phenolic resin. The coating layer of this heat-resistant film is baked at a high temperature of 130 ° C. or higher, and various properties such as heat resistance and adhesion satisfy those required for the FPC. Table 10 shows its characteristics.

From Table 10 and Tables 2-8, the invention products are
It is even better than a film made by coating a phenolic resin on a base material such as C, PVC, PAR or PET. In addition, regarding tensile strength, it is significantly superior to films made by coating phenolic resins on substrates such as PC, PVC, and PAR.

〔The invention's effect〕

As described above, the heat-resistant film of the present invention holds the base material on which the thin film is formed between the endless rotary bodies and gradually widens or narrows the interval of the endless rotary bodies toward the outlet side without causing slack. Since the shape is kept flat, the temperature is higher than the melting point of the base material, which is higher than the melting point of the base material, which is 200-300 ℃, combined with the heat resistance and shape retention of the coating resin formed on the surface.
Even when the coating layer is baked at a high temperature, the substrate does not deform, wrinkles and the like do not impair the film performance, and the surface smoothness is not impaired. Therefore, a thin product with sufficient heat resistance and flame retardancy and excellent flexibility can be obtained, and the adhesion between the coating layer and the substrate, solvent resistance, shrinkage resistance, etc. Because it is excellent, it is not only suitable for use as an FPC under the manufacturing process and use conditions of harsh temperature conditions and etching conditions, but also versatile for insulating films, heat-resistant conductive films, membranes and various other applications. is there.

[Brief description of drawings]

FIG. 1 is a flow sheet for explaining the method of the present invention, FIG. 2 is a schematic plan view of an apparatus for maintaining a shape of a substrate, and FIG. 3 is a schematic partial cutaway side view of a clip mechanism. Is. 100 ... Base material.

Claims (1)

(57) [Claims] 1. A substrate made of polyethylene terephthalate resin, a thin film of one or more solutions selected from polyimide resins, polyamideimide resins, polyparabanic acid resins and polyhydantoin resins, or one or more of the above resins. A thin film of a solution of one or more selected from phenol resin, epoxy resin, and melamine resin, the thin film is dried, and then the base material is held between a pair of endless rotating bodies. A heat-resistant film or a heat-resistant film characterized by being baked at a temperature of 200 to 300 ° C. while maintaining the flat shape of the substrate without causing slack by gradually widening or narrowing the interval toward the outlet side. Manufacturing method of analogues.