JPH0149617B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic bonding method for dielectric films, and more particularly to a method for bonding dielectric films having a thickness of about 6 to 100 μm using a polyester film as a base film.

2. Description of the Related Art Conventionally, there is a method shown in FIG. 1 as a method of bonding dielectric films such as electrostatic recording materials, in which a plurality of films or substances of different compositions are superimposed to form a single structure. In this method, a dielectric film 3 to be bonded is placed between an ultrasonic horn 1 and a lower pedestal 2, pressure is applied while applying ultrasonic waves to the horn, and the dielectrics are bonded by heat action. . However, the joint surfaces joined by this method have the disadvantage that a step (approximately 30% relative to the thickness) is produced in the joint surfaces, as shown in FIG.

The inventors of the present invention conducted intensive research to improve these drawbacks, and as a result, they discovered an adhesive method that provides good smoothness of the bonded surface when superimposing films and bonding them using ultrasonic waves, thereby achieving the present invention.

That is, the present invention involves ultrasonic bonding by overlapping dielectric films with a polyester film as a base film, sandwiching a modified polyester between the overlapping films, and then applying adhesive tape from the back to the overlapping portion of the films. The present invention provides a method for ultrasonic bonding of dielectric films, which improves the smoothness of the seam surface and is characterized by ultrasonic bonding using ultrasonic bonding.

The present invention will be explained in more detail below with reference to the drawings.
FIG. 3a shows an example of the adhesive method of the present invention, in which 4 is a modified polyester and 5 is an adhesive tape. The modified polyester referred to here is a polyester resin with a Tg of about 5 to 80℃ and a melt viscosity of
Approximately 500~5000cp/200℃, tensile strength at break is 50~
^{Approximately} 1000Kg/cm2. As shown in FIG. 3a, a modified polyester 4 is sandwiched between the overlapping parts of the films 3, and one or several pieces of adhesive tape 5 are applied from the back to the overlapping parts of the films, followed by ultrasonic bonding. As shown in FIG. 4, fusion bonding with good smoothness of the bonding surface is achieved.
In this case, the role of the modified polyester 4 is to flow into the gap between the seams and fill in the difference in level during ultrasonic bonding. In addition, the adhesive tape 5 fixes the overlapping parts of the films, thereby preventing the films from moving and shifting due to ultrasonic vibration during adhesion, enabling highly accurate adhesion, and preventing melting during ultrasonic adhesion. It works to receive the base film and modified polyester and firmly fix the film. Figures 3b to 3d show other embodiments of the present invention; Figure 3b shows an example in which modified polyester 4 is applied only to one side of the film 3 to be fused;
d is a coating applied to one entire surface of the film 3 to be fused, and d is a coating applied to both entire surfaces in the same manner. Any of these can produce the same effects as the embodiment shown in FIG. 3a. Appropriate conditions are selected for the application time, amplitude, and pressure of the ultrasonic waves during the above-mentioned fusion bonding according to the material and thickness of the film. Furthermore, the present invention is not limited to dielectric films only.
It can also be applied to a single polyester film.

Films bonded by the method of the present invention can be used in a variety of ways by utilizing their excellent bonding strength and smoothness of the surface of the bonded portion, but are particularly useful as transfer-type belt-shaped recording media, such as electronic It is suitably used for photographic recording media, electrostatic recording media, thermosensitive recording media, thermoplastic recording media, and the like.

Example 1 Thickness using 75μPET film as base film
Overlap 100μ dielectric films with a width of 1mm,
Modified polyester (Vylon 103 manufactured by Toyobo Co., Ltd., Tg = 47℃, molecular weight
18,000 to 20,000), pasted two pieces of cellophane tape on the overlapped part, and applied with an amplitude of 75μ and an application time of 1.
When ultrasonic bonding was performed at a pressure of 70 psig for 2 seconds, the level difference on the bonded surface was less than a few microns.

Example 2 Thickness using 75μPET film as base film
Overlap 100μ dielectric films with a width of 1mm,
A modified polyester (Vylon 300 manufactured by Toyobo Co., Ltd., Tg = 7°C, molecular weight
20,000 to 25,000), pasted two pieces of cellophane tape on the overlapping part, and applied with an amplitude of 75μ and an application time of 1.
When ultrasonic bonding was performed at a pressure of 60 psig for 2 seconds, the level difference on the bonded surface was less than a few microns.

Example 3 75 μPET films were stacked with a width of 1 mm, and modified polyester (Vylon 103 manufactured by Toyobo Co., Ltd., Tg = 47°C, molecular weight 18000) was placed between the stacked films.
~20,000) was applied, two sheets of cellophane tape were attached to the overlapping portion, and ultrasonic bonding was performed at an amplitude of 75 μ, an application time of 1 second, and a pressure of 65 psig, resulting in a level difference of less than 1 μ on the bonded surface.

Comparative example 1 Thickness using 75μPET film as base film
When 100μ dielectric films are ultrasonically bonded under the same conditions as in Example 1 or 2 without applying modified polyester, the difference in level between the bonded surfaces is 10μ.
That's it.

Comparative example 2 Thickness using 75μPET film as base film
When a 100μ dielectric film is ultrasonically bonded under the same conditions as in Example 1 or 2, using polycarbonate instead of modified polyester, the difference in level between the bonded surfaces is 5μ or more, and the difference between the applied resin and the film is Adhesion was also poor.

Comparative Example 3 When a 75μ PET film was subjected to ultrasonic bonding under the same conditions as in Example 3 without applying modified polyester, the level difference on the bonded surface was 7 to 8μ or more.

Comparative Example 4 When a 75 μPET film was subjected to ultrasonic bonding under the same conditions as in Example 3 using polycarbonate instead of modified polyester, the step difference was several μ or more, and the adhesion between the applied resin and the film was poor.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the conventional ultrasonic bonding method.
FIG. 2 is a sectional view of the bonded surface obtained by the method shown in FIG. 1. FIG. 3 is an explanatory diagram of the bonding method of the present invention, and FIG. 4 is a cross-sectional view of the bonded surface obtained by the method of FIG. 3a. 1... Ultrasonic horn; 2... Lower pedestal; 3... Film; 4... Modified polyester; 5... Adhesive tape.

Claims (1)

[Claims] 1 In ultrasonic bonding by overlapping dielectric films with a polyester film as the base film, a modified polyester is sandwiched between the overlapping films, and an adhesive tape is attached from the back to the overlapping part of the films, and ultrasonic bonding is applied. An ultrasonic bonding method for dielectric films that improves the smoothness of the joint surface.