JPS5815289B2 - Polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for laminating polyester films.

More specifically, polyester stretched immature fixed films are superimposed, and an electric field is applied to the superimposed films on a metal roll, so that the superimposed films are evenly and strongly superimposed, and the superimposed films are further fed to a tenter. The present invention relates to a method for laminating polyester films, which is characterized by strongly adhering the films without using an adhesive or compressing them by heat treatment at a specific temperature.

In recent years, the demand for thick films of 100μ or more has increased for various uses, but in order to create thick films in a series of film manufacturing processes using an extruder, it is necessary to ensure the mechanical strength of each process and the specification range. Therefore, special equipment for thick materials is required.

On the other hand, in conventional methods for adhering films, etc., polyester is crystalline and has an inert surface, so various methods have been proposed to impart surface adhesion, but they do not necessarily pose problems. I don't.

Furthermore, even if the method is considered to be quite good, the processing steps are complicated and troublesome.

For example, a method is generally adopted in which the adhesive is coated, dried, and heated and compressed after being treated with some kind of pretreatment agent such as chemical treatment or solvent treatment.

For this reason, the effects on the human body and the outside world, such as toxicity and flammability, are significant in the treatment of solvents and chemicals.

As a result of intensive research to eliminate these drawbacks, the inventor of the present invention has developed a method of stacking two or more stretched polyester immature fixing films, adhering them to each other by applying an electric field, and then heat-treating them at the specific temperature below to strengthen the films. The present invention was completed based on the discovery that it is possible to adhere the material to the material.

That is, in the present invention, two or more polyester stretched immature fixed films of the same or different types are stacked so that their longitudinal directions match, and after being brought into close contact with each other by applying an electric field to the stacked film surfaces, the film is fed to a tenku, 160℃
This method of laminating polyester films is characterized by heat-setting and fusing at a temperature higher than or equal to (melting point -10C) or lower.

The polyester stretched unheated film referred to in the present invention is
This refers to a film that has been stretched by the conventional tenter method or other methods, and whose orientation has not yet been fixed and which has not yet been subjected to heat treatment.

Of course, the film referred to here includes ribbon tapes, sheets, etc. in addition to the conventionally produced strip-shaped Q film.

The method of the present invention involves stacking a plurality of stretched unheat-treated polyester films of the same or different types so that their longitudinal directions (machine direction) coincide, and then guiding them onto a metal roll, and wire-drawing them at a position 20 mm or less from the film surface. and apply 10kV to the steel wire.
By applying a positive voltage of preferably 2 to 5 kX, air interposed between the stacked films is expelled on the metal roll, and the films are brought into close contact and stacked without causing any damage to the films.

The rail width of the Tenku is set to the same width as the heat-setting part from the supply section, and the stacked films are supplied to the Tenku while maintaining a close stacked state, and the temperature is gradually raised until it reaches the heat-setting part. By heat-setting the laminated films at the usual stretching temperature of Cera 1V and the temperature of the heat-setting part being 160C to (melting point -10)C, it is possible to provide a heat-setting effect and strong adhesion between the films.

If the temperature is lower than 160°C, there is little crystallization of the film, making it difficult to bond sufficiently.

The actual film bonding process involves unwinding a film that has been previously stretched and rolled up into a roll, and then superimposing the film on the film that has just been stretched.

The stacked plurality of films are brought into close contact with each other by applying an electric field, and are then subjected to heat-setting and fusing treatments.

When the stacked films are of the same type, comparing the physical property values of the thick film made in this way with the single layer film made by the conventional method, it is found that the changes in the physical property values due to the stacking of the films are It is possible to obtain a thick film that is no different from a directly formed film.

Further, by subjecting the adhesive surfaces of the stretched immature fixed film according to the present invention to corona treatment and laminating the corona-treated surfaces together, a laminated thick film having stronger adhesive strength can be obtained.

One of the major features of the present invention is that before the films are fed into the tenter, they are passed through a strong electric field with the overlapping films to increase the degree of adhesion between the films, and furthermore, the films adhere to each other in the tenter. At the same time, it is heat-set.

Furthermore, if it is desired to obtain an even stronger bonded state, a thick film with even stronger adhesiveness can be obtained by subjecting the bonded surfaces to corona treatment.

Therefore, compared to direct extrusion, stretching, and heat setting film forming processes,
Since no extra heat is applied during the process and no adhesives or processing agents are used, there is no deterioration in physical properties due to this.

In other words, since no adhesive is used, in addition to the ease of handling mentioned above, for example, since the adhesive used as an electrical insulating material for refrigerators is exposed to the refrigerant (Freon), the film as a whole is There is no possibility of a phenomenon in which the Freon resistance deteriorates, and it is also possible to avoid a situation where the heat deterioration resistance of the film as a whole deteriorates due to the poor heat deterioration resistance of the adhesive.

Furthermore, no deterioration in Freon resistance or heat deterioration resistance was observed due to the corona treatment applied to the adhesive surface of the film to strengthen adhesion.

Another feature of this method is its economy.

That is, a method has recently been known in which a plurality of films are stacked together in an unstretched state and a bonded film is obtained by simultaneously stretching them, as disclosed in Japanese Patent Publication No. 47-38859. Both transverse stretching machines need to have sufficient mechanical strength to stretch thick laminated films, and although there is an advantage in laminating different types of films, it is difficult to use equipment when laminating films of the same type. There is no big difference between owning thick material manufacturing equipment from the beginning.

Furthermore, when overlapping different types of films, it is considered impossible to overlap and stretch because the stretching temperature differs depending on the film.

On the other hand, according to the method of the present invention, thick films can be produced using a longitudinal stretching machine and a tenter for producing thin films, which is very economical, and the thickness of the film can be adjusted after stretching. Therefore, there is an advantage that the thickness of the films after lamination is uniform.

Another feature is its strong adhesiveness.

As described in the present invention, once an electric field is applied to bring the films into close contact with each other, the film is supplied to the tenter without adding any extra heat or chemical processing agent, and the same heat as during direct film formation is applied. When heat setting is carried out at a fixed temperature, the bonded parts remain so firmly adhered that they do not peel off even if the films are pasted together even if delamination occurs even if the films are peeled off from each other.

The film of the present invention can be applied to various uses, especially thick materials,
It can be used as a film, for example, as an electrical insulating material or as an electrical base material, and is well titrated in terms of physical properties.

The present invention will be specifically explained below with reference to Examples.

Example 1 Two sheets of stretched, immature fixed polyethylene 2-6 naphclay 1 film are supplied onto a metal roll in a superimposed state, and a positive voltage of 2.5 kV is applied at the top of the metal roll using a steel wire electrode.

As a result, the film adhered electrostatically and was supplied to Tenku while maintaining its intact state.

Temperature inside Tenku is 135℃ in the first stage, then maximum 210℃
Heat setting was performed at ~235°C for about 25 seconds to obtain a laminated film.

The peel strength of the film thus obtained was 200 g.
It was more than Δcumm.

Example 2 One side of two stretched immature fixed polyethylene 2-6 naphcrate films was subjected to corona treatment under the following conditions.

(Using high-voltage electrodes manufactured by Kasuga Denki Co., Ltd.) The film was corona-treated, passed over a metal roll surface in a manner such that the corona-treated surfaces were bonded together, and a voltage of approximately ■ was applied to 25 near the top of the roll. , the films are brought into close contact with each other electrostatically.

It was supplied to an S tenter that reliably maintains this state.

Heat setting was carried out by gradually increasing the temperature using a normal thermosetting device, and the heat setting zone was heated at a temperature of 210° C. to 235° C. for about 25 seconds, and lamination was carried out at the same time.

The physical properties of the resulting laminated film were as shown below.

Example 3 Two stretched, immaturely fixed polyethylene terephthalate films were corona-treated under the conditions described in Example 2, fed onto a metal roll in such a way that the corona-treated surfaces were in close contact with each other, and left static at the top of the roll. Apply an electric charge to ensure that the films are in close contact with each other electrostatically, and supply it to the tenku.
1st stage: 90℃, gradually increase temperature to 210℃ for 2 heat fixing
This was carried out for about 5 seconds, and a laminated film was obtained.

Example 4 Corona treatment was performed on one side of each of a stretched and heat-set polyethylene 2,6 naphthalate film and a polyethylene terephthalate film under the conditions described in Example 2, and the corona-treated surfaces were stacked so that they were in close contact with each other and rolled on a metal roll. By supplying the film onto the surface and applying an electrostatic charge near the top, the films are brought into close contact with each other electrostatically. While maintaining this state, the film is supplied to the S tenter, and the temperature is gradually raised from the supply section to 210C to 230C. Heat setting was performed for about 25 seconds, and at the same time, different types of films were laminated to obtain a laminated film that did not peel off during the peeling test 1 and caused delamination.

Example 5 One side of two stretched immature fixed polyethylene 2,6 naphcrate films was subjected to the corona treatment according to Example 2, and both sides of one stretched immature fixed film were further corona treated, so that the corona-treated surfaces overlapped with each other. In this manner, an electrostatic charge was applied to the film surface, and then heat setting was carried out to obtain a thick laminated film.

The obtained film had sufficient physical properties and peel strength, and the films could not be peeled off from each other.

Claims (1)

[Claims] 1 Layer two or more polyester stretched immature fixing films of the same or different types so that their longitudinal directions match, apply an electric field to the stacked film surface to bring them into close contact with each other, and then feed it to a tenku and heat it to a temperature of 160C to (melting point - 10C
) A method for laminating polyester films characterized by heat setting and fusion bonding at the same time.