JPH078544B2 - Method for producing heat-resistant film or its analogue - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a heat-resistant film or an analogue thereof.

[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 untreated films used as a substrate, engineering plastics such as polyimide (PI) film have been known to have relatively excellent heat resistance, but the film itself is expensive and It was hard to expect that it would be used for a long time.
Therefore, in recent years, various studies have been conducted on a film having heat resistance superior to that of an untreated film made of the base material itself, even though an inexpensive thermoplastic resin is used for the base material itself, and Various such films have also been proposed.

For example, forming a coating layer on a base material made of a thermoplastic resin is considered as one of them. According to such a film, the physical properties such as transparency of the base material itself are not significantly impaired, and the coating layer has plasticity capable of obtaining 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 a low temperature condition where shrinkage and wrinkles are not likely to occur is 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 only a relatively small degree of improvement in heat resistance. . There is a heat-resistant film obtained by impregnating heat-resistant resin into a sheet of heat-resistant fiber or glass fiber and laminating it on the existing film, but it is thick and loses flexibility, especially thin and flexible. It was not perfect for applications such as flexible printed wiring boards that require flexibility. 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 difficult to say that other existing heat-resistant films are in terms of thickness, flexibility and cost as described above, and when heat resistance is improved by mixing additives, other physical properties are impaired. However, 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 when subjected to a heat treatment at a relatively high temperature, there is no wrinkle in the obtained film, without impairing the performance as a film,
Moreover, it is an object of the present invention to provide a method for producing a heat-resistant film having higher heat resistance than that of an untreated film.

[Means for solving problems]

In order to achieve the above object, the method for producing a heat-resistant film of the present invention, a substrate made of polyethylene terephthalate resin, without applying a tensile force, and in the state of flattened without causing slack It is characterized in that it is maintained and heat-treated at a temperature of 130 ° C. or higher.

〔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, 2 is a base material feeding device, 4 is a heating furnace, 5 is a trimming device, and 6 is a winder. As is clear from the figure, the substrate 100 delivered from the delivery machine 2 is heat-treated at a predetermined temperature while passing through the heating furnace 4. The film thus obtained is trimmed and then wound up by the winder 6.

In the above, it is useful to perform the dust removal treatment of the base material 100 before entering the heating furnace 4.

The thermoplastic resin for forming the base material 100 is a polyethylene terephthalate resin (PET), which has excellent tear strength and is highly flexible. The substrate 100 preferably has a thickness of about 1 to 1000 μ from the viewpoint of workability.

The heating temperature of the base material 100 needs to be 130 ° C. or higher, but if the heating temperature is lower than 130 ° C., sufficient heat resistance and adhesiveness cannot be obtained. If the baking temperature is too high, not only the other physical property values are lowered, but also problems such as large shrinkage and wrinkles are likely to occur, and the performance as a film is impaired.
The heating temperature that can maintain the performance as a film is about 300 ℃
It is the following. Moreover, it is desirable that the heating time is set to about 0.5 to 5 minutes. Here, it should be noted that the heat treatment is not limited to setting the temperature condition in the above range,
That is, the base material 100 is maintained in a flat shape without applying tensile force and without causing slack. By the way, if a tensile force is positively applied to the base material 100 during the heat treatment to prevent loosening, the base material 100 is forcibly stretched and it becomes difficult to maintain its shape. But,
It is theoretically possible, but practically impossible, to keep the shape of the base material 100 in a state where no tensile force is applied to the base material 100 during the progress of the heat treatment, and further, slack does not occur. . Therefore, in the method of the present invention, the substrate 10 is subjected to heat treatment.
When the base material 100 is flattened so as not to cause slack without positively applying the tensile strength to 0, it is possible that the base material 100 is eventually applied with the tensile force. In that case, it is within the scope of the method of the present invention.

An example of a device for maintaining such a shape retention state is shown in FIGS. 2 and 3. This device is based on a pair of left and right endless rotating bodies 11 and 11 formed by connecting a large number of clip mechanisms 10 shown in FIG. 3 in an endless manner so that one end portion or the other end portion can individually approach and separate from each other. It is attached to the stand 12. As shown in FIG. 3, in the clip mechanism 10, the bracket 14 provided on the support base 13 has a claw 15 at the tip thereof.
The arm 16 is attached so as to be displaceable between a position where the base material 100 is sandwiched with respect to and a position separated from the support base 13, and the claw 15 is provided between the arm 16 and the bracket 14. An upper end 19 of the arm 16 is made to correspond to an outer peripheral portion of a control rotary plate 18 provided on a winding roller of the endless rotary body 11 by interposing a spring 17 that constantly urges it toward the retracted position side. ing.

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 into the space between the pair of endless rotating bodies 11, 11, both ends of the base material are the clip mechanism 10 at the entrance portion of the device.
After being supported as shown by the solid line in FIG. 3, it reaches the outlet portion of the same apparatus as it is, and the holding is released at this outlet portion. Here, regarding the base material 100 made of a thermoplastic resin that expands by heating, a pair of endless rotating bodies 11, 11 is used.
Is gradually widened toward the outlet side, and for the base material 100 made of a thermoplastic resin that shrinks by heating, the heating furnace 4 is set so that the distance is gradually narrowed toward the outlet side. During passing, even if tensile force may be applied to the base material 100 as a result, positive tensile force is not applied, and slack does not occur.
Is kept flat. In FIG. 2, a case where a base material made of a synthetic resin that shrinks by heating is fed is illustrated by a virtual line.

As described above, when the shape of the base material is held flat and heat-treated, shrinkage and wrinkles of the base material do not occur, and the performance as a film is not impaired. In particular, in the present invention, since the heating 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]

The following table compares the characteristics of the film produced by the method of the present invention (hereinafter referred to as the invention product) with the characteristics of the untreated film composed of the substrate itself. In this table, PET
Indicates the type of thermoplastic resin forming the substrate, and an untreated film made of the substrate itself is shown as a conventional product. In addition,
As a comparative example, a film obtained by baking a coating layer on a PET substrate is also shown as a coating film.

From this table, it is understood that the heat resistance of the invention product is improved as compared with that of the untreated film, and further, the higher the heating temperature is, the higher the heat resistance is. Also, it is comparable to the coating film in terms of heat resistance, tensile strength, heat shrinkage, and the like. For example, the heat resistance of the invention product heat-treated at 300 ° C. shows a high temperature of 250 ° C., and this heat resistance temperature is equivalent to that of the coating film. From this, it can be said that the invention product can be used as a substitute for the coating film because the heat resistance of the untreated film has been upgraded. Therefore, it is clear that the application range of the invention product is expanded as compared with the use of the untreated film. For example, the heat resistance of the invention product treated at a heating temperature of 300 ° C. is based on the engineering plastic as the base material described above. Can also be used as a substitute for

By the way, by utilizing the flexibility of a film based on a thermoplastic resin, the flexible printed wiring board (FP
C), capacitors and base films for transparent electrodes, liquid crystal films, IC carrier tapes and other electronics fields, interior materials for aircraft and automobiles, nuclear power related fields, etc. have been tried. When used, heat resistance and flame retardancy are required according to the processing conditions and usage conditions. For example, when it is used as a base film for FPC, it is exposed to high temperatures during soldering, and therefore heat resistance at a soldering temperature of about 250 ° C. is required.
From the above table, it is clear that the invention products that have been heat-treated at 270 ° C or higher can be used to meet this demand, and by using them, the flexibility can be utilized to deploy FPCs on curved surfaces, etc. There is an advantage that can be.

Next, a test method for 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.

Solvent resistance: In accordance with JIS C-6481 5.13, soak 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 immerse it in a solder bath at each temperature shown in the table for 30 seconds.

〔The invention's effect〕

As described above, the heat-resistant film of the present invention, without imparting a tensile force, and, since maintaining the base material made of PET in a flat shape without causing slack, the base material Even when heat-treated at a high temperature of 130 ° C. or higher, wrinkles do not occur and film performance is impaired. Therefore, while using inexpensive PET as the substrate shows sufficient heat resistance, yet, it is possible to obtain a thin one having excellent flexibility, and since it is excellent in solvent resistance, shrinkage resistance, etc., In particular, it is not only suitable for use as an FPC under the manufacturing process and use conditions of severe temperature conditions and etching conditions, but also can be generally used for insulating films or sheets and various other uses.

[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 the shape of a substrate, and FIG. 3 is a schematic partial cutaway side view of a clip mechanism. Is. 100 ... Base material.

Claims (1)

[Claims] 1. A base material made of polyethylene terephthalate resin is heat-treated at a temperature of 130 ° C. or higher while maintaining a flat shape without applying tensile force and without causing slack. A method for producing a heat-resistant film or a similar product.