JPS63224767A - Production of heat-resistant film or its similar - Google Patents

Abstract

PURPOSE:To impart sufficient heat resistance to the title film, by forming a thin film of polyimide resin, etc., on a base material consisting of a polyethylene terephthalate resin, drying the film, and then baking the film while keeping the base material unslacked and flat. CONSTITUTION:The thin film of one or >=two kinds selected from polyimide resin, polyamide-imide resin, polyparabanic acid resin, and polyhydantoin resin or the thin film of a soln. of one or >=two kinds of the above-mentioned resins and one or >=two kinds selected from phenolic resin, epoxy resin, and melamine resin is formed on the base material consisting of polyethylene terephthalate resin. The thin film is dried, and then baked at 200-300 deg.C while keeping the base material unslacked and flat. As a result, a thin film exhibiting sufficient heat resistance and flame resistance and further having excellent softness can be obtained, and the adhesion between the coating layer and the base material and resistance to solvents and shrinkage are remarkably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a heat-resistant film or its analogue, in which a coating layer is formed on a base material made of polyethylene terephthalate resin.

[Conventional technology]

Flexible films based on thermoplastic resins and similar sheets (hereinafter collectively referred to as films) have a high degree of freedom in design due to their flexibility. Although it has some degree of insulation, it generally has insufficient heat resistance, so its uses are limited. Among untreated films conventionally used as base materials, polyimide (PI), polyether ether ketone (PEEK), and polyether sulfide (PES) have relatively excellent heat resistance.
There were films made of engineering plastics such as polyphenylene sulfide (PPS), polyparabanic acid (PPA), polyarylate (PAR), etc., but the resins themselves were expensive, and the process of processing them into films required advanced technology. With the addition of new processing techniques, it became even more expensive, making it difficult to expect it to be used for general purposes. Therefore, in recent years, various studies have been conducted on films that have better heat resistance than untreated films made of the base material itself, despite using inexpensive thermoplastic resin for the base material itself. Various such films have also been proposed.

For example, one example is a film based on a composition in which certain additives are mixed with polyvinyl chloride resin (PVC), which is a representative thermoplastic resin that is inexpensive and easily available.

However, in the method of improving the heat resistance of the base material by mixing additives, it is often necessary to mix and adjust various additives in order to obtain the target heat resistance characteristics, and it is difficult to mix the additives. It has been pointed out that the problem is that the transparency and other physical properties change significantly as a result.

On the other hand, by forming a coating layer on a base material made of a thermoplastic resin, it is also possible to obtain a film with heat resistance properties that cannot be obtained from the base material itself. With such a film, the physical properties of the base material itself, such as transparency, are not significantly impaired, and the coating layer may provide heat resistance properties that cannot be obtained from the base material itself. As a method for manufacturing such a film, a method generally considered is to bake the coating layer under low temperature conditions where there is no risk of shrinkage or wrinkles in the base material made of thermoplastic resin. However, since the heat resistance of a film having a coating layer is correlated with the baking temperature of the coating layer, it was assumed that baking at such a low temperature would only result in a relatively small degree of improvement in heat resistance. In addition, there is a heat-resistant film made by impregnating a sheet of heat-resistant fiber or glass fiber with a heat-resistant resin and laminating it onto an existing film, but it is thick and loses flexibility. It was not perfect for applications such as flexible printed wiring boards that require flexibility. Therefore, in any case, it is difficult to say that the conventional films are sufficient as heat-resistant films.

[Problem that the invention seeks to solve]

As mentioned above, it is possible that the heat resistance of the conventionally assumed heat-resistant film may be improved somewhat compared to the untreated film made of the base material itself, but it still has sufficient heat resistance. It is difficult to say that this is the case, and as mentioned above, other existing heat-resistant films have problems in terms of thickness, flexibility, and cost, and when improving heat resistance by incorporating additives, other physical properties are impaired. There was a problem that the film was still insufficient as a heat-resistant film.

The present invention has been made in view of the above circumstances, and has heat resistance such that even if the thin film that becomes the coating layer is baked at a relatively high temperature, the resulting film will not have wrinkles and its performance as a film will not be impaired. The purpose of the present invention is to provide a method for producing a film.

[Failure to solve the problem]

In order to achieve the above object, the method for producing a heat-resistant film of the present invention uses polyethylene terephthalate resin (PET).
The base material consists of polyimide resin (PI), polyamideimide resin (FAI), polyparabanic acid resin (PPA),
A thin film of a solution of one or more selected from polyhydantoin resins (PH), or a solution of one or more of the above resins and one or more selected from phenol resins, epoxy resins, and melamine resins. After drying, the thin film is heated at 200 to 300° while maintaining the base material in a flat shape without causing any slack.
It is characterized by being baked at a temperature of C.

〔Example〕

The present invention will be explained in detail below.

FIG. 1 is a flow sheet for implementing the method of the present invention, in which 1 is a feeding machine for the base material, 2 is a dipping coater for coating solution, 3 is a drying oven, 4 is a baking oven, 5 is a trimming device, and 6 is a It is a winder.

As is clear from the figure, a thin film of coating solution is formed on one or both sides of the base material 100 fed out from the feeding machine 1 while passing through the dipping coater 2 , and while the thin film passes through the drying oven 3 . dried. Thereafter, while the base material 100 passes through the baking furnace 4, the thin film is baked at a predetermined temperature to form a coating layer. After the film thus obtained is trimmed, it is rolled up
is wound up.

−6= In the above, base material 1 before entering dipping coater 2
It is useful to perform a primer treatment or a corona discharge treatment on the base material 100 to increase its surface activity, and to perform a static electricity removal treatment or a dust removal treatment on the base material 100 in order to improve the adhesion of the coating layer.

The base material 100 is made of PET and has excellent tear strength and flexibility. Base material 100%, 1 in terms of workability
It is desirable to have a thickness of about 350 μm. If the thickness is less than 1 μm, it will be difficult to handle and the strength will be insufficient, and if the thickness is more than 350 μm, there is a concern 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 desired.

The coating agent is a solution of one or more selected from PI, PAl, PPA, and PH, or one or more of the above resins and one or more selected from phenol resin, epoxy resin, and melamine resin. A solution of The necessary conditions for the coating solution are that it be varnish-like, harden at a temperature of 200 to 300°C, and have adhesion to the substrate. Specifically, Pl,
, when PAI, PPA, and PH are used alone, when two or more of Pl, PAI, PPA, and PH are used in combination, and when one of Pi PAI, PPA, and PH is used with a phenol resin or an epoxy resin. , a combination of one or more selected from melamine resins, and a combination of two or more of PI PAI PPA, PH, phenol resin, epoxy resin,
This is a case where one kind or a combination of two or more kinds selected from melamine resins are used.

As for PPA, for example, manufactured by Toa Fuel Industry ■, product name XT-
1.There is XT-4. This is a homopolymer or copolymer having the general formula as a basic unit.

Examples of the above Ar include the following. The above PPA uses N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), etc. as the main solvent, and acetone, MEK, MIBK as the diluting solvent.
It is used by preparing a varnish-like solution using a ketone solvent such as. PPA has heat resistance second only to PI and can be suitably used as a coating agent for the heat-resistant film of the present invention.

As the PI, for example, Su-Misodo (TP-'600) manufactured by Kanebo NSC (trade name) can be suitably used.

This PI is a polyisoimide oligomer having an acetylene group at the end, and is represented by the following structural formula.

This product uses DMF, NMP, etc. as a main solvent, and a ketone solvent such as acetone, MEK, MIBK, etc. as a diluent. Further, as the PI, a thermosetting polyimide resin such as bismaleimide-triazine resin (Mitsubishi Gas Chemical Co., Ltd. 91.BT Resin BT-2170) can be used.

As the PAI, for example, Resistherm (^I 133L), manufactured by Bayer AG and represented by the following structural formula, can be used.

The main solvent for this product is NMP', DMAC (dimethylacetamide), etc., and the diluent is acetone, M
Use a ketone solvent such as EK, MIBK, etc.

As the PH, for example, Gistherm (PH20), a trade name manufactured by Sumitomo Bayer Urethane, which is represented by the following structural formula, can be used.

The main solvent for this product is cresol, phenol, etc., and the diluent is acetone or MEK.

Use a ketone solvent such as MIBK.

The phenolic resin may be a straight phenolic resin or a modified phenolic resin. This solvent includes alcohols such as methanol and isopropanol (IPA), acetone,
Ketones such as MEK and cellosolves are used.

In addition, a surfactant or an organic, inorganic, or metal fine powder filler may be appropriately added to the coating solution as necessary. Examples of modified phenolic resins include epoxy-modified, melamine-modified, and inorganic-modified (B202.PzOs) phenolic resins. In particular, when melamine-modified or epoxy-modified phenolic resins are used, high adhesion to the substrate is ensured. Among these three, epoxy-modified phenol resin exhibits particularly high adhesion.

When a FAI solution and an epoxy resin solution are used in combination, the adhesion of the coating layer to the base material is improved, and chemical resistance and water absorption are also improved.

Moreover, when a PI warm solution is combined with an epoxy resin solution, the molding temperature becomes lower. Furthermore, heat resistance is improved when a melamine resin solution is used as a coating layer. The above is just 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, commonly known resins are usually used. Furthermore, each of the phenol resin, melamine resin, and epoxy resin may be used as a modified product or derivative.

The thickness of the thin film after baking is desirably 1 to 10 μm in dry condition, and sufficient heat resistance and flame retardance can be obtained even with such a thickness.

The baking temperature of the thin film formed on the base material 100 is 200 to 300
"C", but if the baking temperature is too high, it not only causes bleeding from the base material 100 and a decrease in other physical properties, but also tends to cause problems such as large shrinkage and wrinkles, and the performance as a film deteriorates. The baking temperature that can maintain the performance as a film is 300°C or lower.If the baking temperature is lower than 200°C, sufficient heat resistance, adhesion, etc. cannot be obtained.In addition, the baking time is 0.5~ It is desirable to leave the baking time for about 5 minutes.It is important to note here that the baking temperature must not only be set within the above range, but also that the base material 100 be kept in a flat shape without causing any slack. When baking with shape retention in this way, the base material is heated to a temperature higher than its melting point, combined with the heat resistance and shape retention of the coating resin formed on the surface. The base material is not deformed even though the film is heated, and a high level of smoothness is imparted to the film surface.In order to improve the smoothness of the film surface, a drum may be used to press the film from above and below.

An example of a device for maintaining the shape-retaining state is shown in FIGS. 2 and 3. This device consists of a pair of left and right endless rotating bodies 1) which are formed by connecting a large number of clip mechanisms 10 in an endless manner as shown in FIG. 1) are attached to the base 12 in such a manner that one end thereof or the other end thereof can be approached and separated from each other individually.

As shown in FIG. 3, the clip mechanism 10 has a bracket 14 provided on the support base 13 at a position where the claw 15 at the tip clips the base material 100 with respect to the support base 13, and from the support base 13. The arm 16 is attached so that it can be displaced between distant positions, and the arm 16 and the bracket 14
A spring 17 is interposed between the claws 15 and the outer periphery of a control rotary plate 18 provided on the winding roller of the endless rotary body 1). The upper end 19 of the arm 16 corresponds to the upper end 19 of the arm 16.

In the above configuration, when the endless rotating body 1) is rotationally driven in the direction of the arrow in the figure, the arm 16 of the clip mechanism 10 is moved by the control rotating plate 18 along the imaginary line in FIG. The claw 15 moves away from the support base 13 by swinging to the position, and the arm 16 returns to the position indicated by the solid line in the same figure in other parts, so that the claw 15 corresponds to the support base 13. Therefore, the base material 100 on which the thin film is formed is connected to the pair of endless rotating bodies 1.
). When the base material is fed into the space between The hold is released at the exit section. Here, a base material 100 made of a thermoplastic resin that expands when heated
For a pair of endless rotating bodies 1). If the interval 1) is made to gradually become wider as it approaches the exit side, and for the base material 100 made of a thermoplastic resin that shrinks when heated, the above interval is made to become gradually narrower as it approaches the exit side. 4, there is no slack in the base material 100, so the base material 100 does not flow, and this base material 1
00 is maintained in a flat and shape-retained state, and the surface smoothness is not impaired. In addition, in FIG. 2, a case where a base material made of a synthetic resin that shrinks when heated is sent is illustrated by imaginary lines.

If the base material is held flat and the thin film is baked as described above, the base material will not shrink or wrinkle, and its performance as a film will not be impaired. In particular, in this invention, since the baking temperature is relatively high, it is of great significance to keep the base material flat.

Next, an experimental example will be explained.

[Experiment example]

Table 1 shows the films produced by the method of the present invention (hereinafter referred to as
It's called an invention. ), and Tables 2 to 8 show the characteristics of Inventions 1 to 7. Also, Table 9 shows PET and PPA.

Various properties of untreated films (hereinafter referred to as comparative products) that do not have a coating layer and are based on each of the PIs are shown.

(Hereinafter, blank space) 78 questions - 63-224767 (9) JP-A-63-2247E; 7 (10) From Tables 2 to 9, the heat resistance of the invented product is that of the untreated film, the film with only PET base material. (Comparative product 1), it has superior heat resistance due to the coating layer, and even though it is based on PET, its heat resistance is lower than that of films that are based only on PPA or PI (Comparative product 2). ．．
3) You can see that the two are close together. For example, even if the invented product is baked at 200°C, which is the lower limit of the baking temperature conditions of the present invention, the heat resistance of the invented product is about 50°C compared to an untreated film made only of PETA material (Comparative Crystal 1). has also improved. Then, set the baking temperature to a high temperature, for example 270°.
The heat resistance of invention products 1 to 7 when the temperature is C or higher approaches that of an untreated film (comparative product 2.3) made only of PPA or PI. From this, it can be seen that the invented product achieves grade amplifier heat resistance compared to the untreated film.

It is therefore clear that the range of applications of these inventions is expanded compared to that of untreated films. Also,
The heat shrinkage rate is very good due to the PET base material itself, and is comparable to that of engineering plastics. This, combined with the above-mentioned tendency to upgrade heat resistance, results in invented products (e.g. baking temperature of 300°C).
The invented product treated with can be used as a substitute for the engineering plastic-based film described at the beginning.

In addition, the higher the baking temperature of the thin film, the better the heat resistance of the invented product, and the flame retardance is equivalent to Comparative Products 2 and 3, and the adhesion between the base material and the coating layer, solvent resistance, alkali resistance, etc. All of the invented products were generally good, and the water absorption rate was much lower than that of Comparative Products 2 and 3. It can also be seen that the alkali resistance is superior to Comparative Product 2.3.

By the way, flexible printed wiring boards (F
PC"), base films for capacitors and transparent electrodes, heat-resistant conductive films, liquid crystal films, IC carrier tapes, and other electronics fields; membranes used in dialysis and diffusion; interior materials for aircraft and automobiles;
Attempts have been made to use the film in fields related to nuclear energy, but when using the above film in these fields, heat resistance and flame retardance are required depending on the processing and usage conditions.

For example, when used as a base film for FPC, it is exposed to high temperatures during soldering, so the soldering temperature is 250°C.
A certain degree of heat resistance and flame retardancy is required.

It is clear from the table above that inventions 1 to 7, which are baked at temperatures of 270°C or higher, can be used to meet this demand, and when these are used, FPC can be applied to curved parts by utilizing their flexibility. This has the advantage of making it possible to deploy In addition, interior materials for aircraft and automobiles are particularly required to be flame retardant, and all of the inventions meet this requirement.

Next, the test method for each item will be explained.

Adhesion: Make grid-like cuts in the coating layer with a razor blade, adhere cellophane tape with a width of 241 mm, and visually observe whether the coating film peels off when the cellophane tape is suddenly peeled off. ○ indicates that there was almost no peeling. All inventions are not exfoliated.

=25= Solvent resistance: According to JIS C-64815, 13, acetone, ME
K.

Immerse in each of toluene and trichlene for 5 minutes at room temperature. 0 indicates a state in which there is almost no peeling or dissolution, and × indicates a state in which peeling or dissolution of the coating film is observed, and it comes off when rubbed with a cloth. The invented product has sufficient solvent resistance, and this shows that it can withstand etching treatments and the like.

Heat resistance: 5 cm x 5 cm of film laminated with copper foil
Cut into pieces and immerse for 10 seconds in an oil bath or solder bath at each temperature indicated in the table.

Flame retardance: This is a determination based on the IJL-94VTM method.

Next, the applicant has developed polyvinyl chloride resin (PVC), polycarbonate resin (PC), polyarylate resin (P
AR), we have devised a heat-resistant film in which a base material selected from PET is coated with phenolic resin. The coating layer of this heat-resistant film is baked at a high temperature of 130"C or higher, and the various properties such as heat resistance and adhesion satisfy the requirements for the above-mentioned FPC. Table 10 shows the various properties. .

' (Hereinafter, blank) From Table 10 and Tables 2 to 8, the invented product has P in terms of heat resistance.
It is even better than films made by coating base materials such as C, PVC, PAR, and PET with phenolic resin. Furthermore, in terms of tensile strength, it is significantly superior to films made of base materials such as PC, PVC, and PAR coated with phenol resin.

〔Effect of the invention〕

As explained above, the heat-resistant film of the present invention maintains the base material in a flat shape without causing any sagging, so it combines with the heat resistance and shape retention of the coating resin formed on the surface. Even if the coating layer is baked at a high temperature of 200 to 300 degrees Celsius, which is higher than the melting point of the base material, the base material will not be deformed, wrinkles will not occur, the film performance will not be impaired, and the surface smoothness will not be impaired. Not possible. Therefore, it is possible to obtain a thin-walled product that exhibits sufficient heat resistance and flame retardancy, as well as excellent flexibility, and has excellent adhesion between the coating layer and the base material, solvent resistance, shrinkage resistance, etc. Because of its excellent properties, it is not only suitable for use as FPCs in manufacturing processes and usage conditions that involve particularly harsh temperature and etching conditions, but also for general use in insulating films, heat-resistant conductive films, membranes, and a variety of other uses. be.

[Brief explanation of drawings]

Fig. 1 is a flow sheet for explaining the method of the present invention, Fig. 2 is a schematic plan view of a device for maintaining the shape of the substrate, and Fig. 3 is a schematic partially cutaway side view of the clip mechanism. It is. 100...Base material.

Claims (1)

[Claims] (1) A thin film of one or more solutions selected from polyimide resin, polyamideimide resin, polyparabanic acid resin, and polyhydantoin resin on a base material made of polyethylene terephthalate resin, or one or more of the above resins and phenol. Forming a thin film of a solution with one or more selected from resin, epoxy resin, and melamine resin,
A method for producing a heat-resistant film or its analogue, characterized in that after drying, the thin film is baked at a temperature of 200 to 300°C while maintaining the base material in a flat shape without causing any slack. .