JPH09220765A - High frequency thermal bonding method of non-polar resin and its laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mutually strongly bond non-polar resins without interposing a polar resin by irradiating the surface of a non-polar resin with ultraviolet rays having a peak within a specific wavelength range and subsequently applying an electric field thereto and allowing the ultraviolet irradiated surface to generate heat to fuse the non-polar resin. SOLUTION: The surface of a non-polar resin 10 showing characteristics such that a dielectric power factor is 0.006 or less at frequency of 1kHz-1MHz is irradiated with ultraviolet rays having a peak within a wavelength range of 380nm or less to be modified. Next, a pair of non-polar resin sheets 10, 10 are arranged so as to hold a non-polar resin sheet 10 of which both surfaces are brought to ultraviolet irradiated surfaces 10A therebetween and an electric field with frequency of 1-300MHz is applied to the non-polar resin sheets 10 by a high frequency heating apparatus consisting of upper and lower electrodes 11, 12 to perform high frequency thermal bonding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency heat-bonding method for a non-polar resin, which has been said to be incapable of being fused by high-frequency heating of 300 MHz or less, and a laminate of non-polar resin sheets produced by the bonding method. .

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 51-11977, No. 55-59921, and No. 55-150321 disclose techniques for applying a high-frequency electric field to a nonpolar resin to fuse or bond it by heating. JP-A-62-297137
And Japanese Patent Application Laid-Open No. 5-269853. Further, as to a technique for irradiating a polyester resin which is a non-polar resin with ultraviolet rays to modify the surface, see Japanese Patent Laid-Open No.
185177 and JP-A-4-146262.

[0003]

Since the non-polar resin does not generate heat even when a high frequency electric field of 300 MHz or less is conventionally applied, it cannot be fused or adhered even if high frequency heating is applied. For example, the applied frequency f required for high frequency heating is represented by the following formula. f = Pv / (0.566 × ε × tan θ × E ² × 1
0 ^-12 ) In the formula, Pv is the amount of heat required per unit time per unit volume,
ε is the dielectric constant, tan θ is the dielectric power factor, and E is the voltage between the electrodes.

Here, the specific gravity is 1.5 and the specific heat is 0.5 calories.
The amount of heat Pv required for a unit time per unit volume of a thermoplastic resin having a deformation temperature of 150 ° C./gram·° C. is 470 watts, and when the applied voltage between electrodes is 10 kilovolts / cm, it is non-polar. Dielectric constant (ε) of resin = 2,
When the dielectric power factor (tan θ) = 0.0005, the applied frequency required from the above formula is a very high frequency of 8450 MHz. Therefore, high frequency heating has been limited to polar resins such as vinyl chloride resin, vinylidene chloride resin, nylon resin and urethane resin having a dielectric power factor of 0.01 or more.

In any of the disclosed inventions, the nonpolar resin is adhered by a technique in which a polar resin is sandwiched in the middle to apply a high-frequency electric field to heat the polar resin to melt the nonpolar resin. That is, the high-frequency heat-bonding of the nonpolar resin is performed with the polar resin interposed.

In such high-frequency heat bonding, a strong adhesive force cannot be obtained unless the polar resin and the non-polar resin melt and are compatible with each other at the interface. However, resins with different polarities are not compatible with each other, so they are easily peeled off from the interface between the nonpolar resin and the polar resin, and because the fusion-bonded part is incompatible, it becomes opaque or semitransparent and transparent to the resin. It causes the inconvenience that the beautiful appearance is impaired.

Although a technique of irradiating with ultraviolet rays is disclosed as a method of surface modification of a polyester resin which is one of the non-polar resins, it is disclosed in Japanese Patent Laid-Open No. 3-18517.
No. 7 is for improving the dyeability of a polyester molded article, and JP-A-4-146262 is only for the purpose of improving the adhesiveness between a polyester resin and a rubber or resin in a prepreg sheet.

The object of the present invention is to bond high-frequency non-polar resins firmly to each other without interposing a polar resin, and to ensure high-frequency heat-bonding that can ensure an aesthetic appearance without impairing the transparency of the resins themselves. A method and a laminate thereof are provided.

[0009]

In order to achieve the above-mentioned object, the high-frequency heat-bonding method for a nonpolar resin according to the present invention comprises:
Irradiate the surface of non-polar resin with a dielectric power factor of 0.006 or less at a frequency of 1 kilohertz to 1 megahertz with ultraviolet rays having a peak at a wavelength of 380 nanometers or less, and then apply an electric field with a frequency of 1 to 300 megahertz. Then, a method is adopted in which the surface irradiated with the ultraviolet rays is heated and fused.

Further, the laminate according to the present invention has a dielectric power factor of 0.00 at a frequency of 1 kilohertz to 1 megahertz.
380 on one or both sides of a non-polar resin sheet of 6 or less
Irradiate with ultraviolet rays having a peak at a wavelength of nanometer or less,
Next, at least two or more of the non-polar resin sheets are laminated and an electric field having a frequency of 1 to 300 MHz is applied,
The UV-irradiated surface is heated and fused.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The non-polar resin used in the present invention means a resin having a dielectric power factor of 0.006 or less at a frequency of 1 kilohertz to 1 megahertz. The resin is polyethylene resin, polypropylene resin, polyisobutylene resin, polystyrene resin, polyester resin,
Examples thereof include polycarbonate resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), and resins of these copolymers. Since the polyolefin resin has an extremely low dielectric power factor, a polyester resin, a polycarbonate resin, a polyacetal resin, or an ABS resin is preferable as the nonpolar resin of the present invention. Polyethylene terephthalate resin or polybutylene terephthalate resin is particularly preferable.

The dielectric constant (ε) and dielectric power factor (t) of polar resin and non-polar resin at 1 kHz and 1 MHz.
The characteristic value of an θ) is shown in FIG.

By the way, the surface of the non-polar resin can be modified by irradiating it with ultraviolet rays having a peak at a wavelength of 380 nanometers or less. It is not clear how the surface of the resin is modified by ultraviolet rays, but the ultraviolet rays change oxygen into ozone, and the active oxygen generated from this ozone forms carbon-carbon bonds or carbon-hydrogen on the surface of the irradiated object. It is presumed that, by reacting with the bond, a carboxyl group, a carbonyl group or a hydroxyl group is formed on the surface and a polar group is formed only on the surface of the non-polar resin.

The wavelength of ultraviolet rays is 254 at which ozone generation is high.
Far ultraviolet rays such as nanometers or 185 nanometers are preferable, and irradiation with a low pressure mercury lamp is preferable.
Further, the total irradiation amount of ultraviolet rays varies depending on the wavelength of the ultraviolet rays, but in the present invention, it is usually 60 mJ / cm ² to 5000 mJ / cm ^2.
2 is preferred.

Since the activation of the surface of the non-polar resin after irradiation with ultraviolet rays decreases with time, it is necessary to perform high frequency heating together with the adherend of another non-polar resin as soon as possible after irradiation with ultraviolet rays. Although the time for maintaining the activity of the surface of the non-polar resin after irradiation with ultraviolet rays varies depending on the type of resin or the irradiation amount of ultraviolet rays, the maximum retention time is empirically about 4 hours.

After the ultraviolet irradiation, the non-polar resin is subjected to high-frequency heat bonding by applying an electric field having a frequency of 1 to 300 MHz together with an adherend of another non-polar resin. The preferred applied frequency in the present invention is 100 or less, and particularly preferably 30 to 80, which is the same as that of the high frequency heating device for vinyl chloride resin.
Megahertz. If it exceeds 300 megahertz, it is difficult to control the heat generation temperature of the non-polar resin, and if it is less than 1 megahertz, the application time for heating the non-polar resin becomes long. The application time differs depending on the irradiation amount of the ultraviolet rays, the type of resin and the thickness of the molded body, and the voltage between the electrodes, but the usual application of several seconds to ten and several seconds is sufficient.

In the present invention, the non-polar resin does not generate heat at 300 MHz, but only the surface activated by the irradiation of ultraviolet rays generates heat and melts, so that the non-polar resin can be adhered to another non-polar resin adherend. In this case, it is preferable that the adhesion surface of the adherend of the other non-polar resin is also subjected to ultraviolet irradiation treatment, and the ultraviolet irradiation surfaces are adhered to each other for high frequency heating.

The high-frequency heat-bonding method of the present invention is suitable for manufacturing a laminate by laminating nonpolar resin sheets. Especially,
It is suitable for bonding a laminate of three or more sheets, and also suitable for producing a transparent laminate in which polyester resin sheets of polyethylene terephthalate resin or polybutylene terephthalate resin are laminated. In the present invention, since only the resin of the same kind is melted and compatibilized without adhering the resin of the other kind to the adhesive surface, a laminate having a strong adhesive force while maintaining transparency can be obtained. It can also be applied to thin layer plates such as polycarbonate.

In the present invention, as shown in FIG. 2, a pair of non-polar resin sheets 10 and 10 are arranged with a non-polar resin sheet 10 whose both surfaces are UV irradiation surfaces 10A sandwiched therebetween, and an upper electrode 11 and A laminated body can be formed by bonding with a high-frequency heating device including the lower electrode 12. In addition, as shown in FIG. 3A, the ultraviolet irradiation surface 10A is formed on the relative surface of the pair of non-polar resin sheets 10.
3B, the ultraviolet irradiation surface 1 is provided only on one of the nonpolar resin sheets 10, as shown in FIG. 3B.
As shown in FIG. 3C, which is based on the mode of FIG. 3A and the mode of FIG. 3A, the non-polar resin sheet 10 having no ultraviolet irradiation surface is sandwiched in the middle and mutually bonded. What can be done can be illustrated.

[0020]

【Example】

Examples 1 to 5 and Comparative Examples 1 to 25 Width 25 mm, thickness 100 μm, melting temperature 255 ° C., one surface of a polyethylene terephthalate resin sheet having a dielectric power factor of 0.003 to 0.006 at 1 MHz, 25
Ultraviolet irradiation was performed with an ultraviolet irradiation device of a low pressure mercury lamp having peaks of 4 nanometers and 185 nanometers. Further, the other side was also similarly irradiated with ultraviolet rays to prepare a polyethylene terephthalate resin sheet in which both sides were irradiated with ultraviolet rays. 2 kg / cm ² of pressure is applied by a high-frequency heating device that uses a projection-shaped upper electrode and a flat-plate-shaped lower electrode, sandwiching the resin sheet that has been irradiated with ultraviolet light with two sheets of the same type of polyethylene terephthalate resin sheet that have not been irradiated with ultraviolet light. On the other hand, an electric field was applied under five conditions to bond with high frequency heating.
The peel strength of the laminated polyethylene terephthalate resin sheet was measured according to the peel strength measurement method of JIS K 6850. As a comparative example, three polyethylene terephthalate resin sheets which were not irradiated with ultraviolet rays were laminated and similarly subjected to high frequency heating under three kinds of conditions. FIG. 4 shows the results of the peel strength, the irradiation amount of ultraviolet rays, and the conditions of application.

Examples 6 to 9 Sheets or lamina of four kinds of nonpolar resins having a width of 25 mm, a thickness of 100 μm and a dielectric power factor of 0.006 or less at 1 MHz, have peaks of 254 nanometer and 185 nanometer. A predetermined amount of ultraviolet irradiation was performed with an ultraviolet irradiation device of a low pressure mercury lamp. Further, another resin sheet or thin layer plate of the same kind was similarly irradiated with ultraviolet rays. An electric field of 80 MHz is applied for 1 to 5 seconds while applying a pressure of ² to 5 kg / cm ² with a high frequency heating device that uses two resin sheets or thin layer plates together and has a protruding upper electrode and a flat lower electrode. Then, they were bonded by high frequency heating. The peel strength of the laminated resin sheet or thin layer plate was measured according to the peel strength measurement method of JIS K 6850. Results are shown in FIG.

[0022]

As described above, the non-polar resin, which was conventionally considered to be incapable of high-frequency heating adhesion, can be bonded by high-frequency heating by irradiating ultraviolet rays in advance, and the non-polar resin can also be bonded. Since there is no adhesive sheet of polar resin on the adhesive surface, a uniform layer is formed on the adhesive surface when fusion is performed by high frequency heating to obtain a strong adhesive force, and the transparency of the resin is impaired. It is possible to provide a high-frequency heat-bonding method for a non-polar resin and a laminate thereof, which has an unprecedented excellent effect of ensuring or maintaining an unprecedented aesthetic appearance.

[Brief description of drawings]

FIG. 1 is a chart showing characteristic values of dielectric constant and dielectric power factor of polar resin and nonpolar resin.

FIG. 2 is a schematic configuration diagram showing a molding aspect of a laminate according to the present invention.

3A to 3C are cross-sectional views showing a bonding mode of a nonpolar resin sheet.

FIG. 4 is a chart showing test conditions and results of Examples 1 to 5 and Comparative Examples 1 to 3.

FIG. 5 is a table showing test conditions and results of Examples 6 to 9.

[Explanation of symbols]

 10 Non-polar resin 10A UV irradiation surface

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Claims (3)

[Claims] 1. A surface of a nonpolar resin having a dielectric power factor of 0.006 or less at a frequency of 1 kilohertz to 1 megahertz is irradiated with ultraviolet rays having a peak at a wavelength of 380 nanometers or less, and then a frequency of 1 to 300 megahertz. The high-frequency heat-bonding method for a non-polar resin, characterized in that the ultraviolet-irradiated surface is heated and fused by applying the electric field. 2. The non-polar resin is a polyester resin,
The high-frequency heat-bonding method for a nonpolar resin according to claim 1, which is selected from any of a polycarbonate resin, a polyacetal resin, and an acrylonitrile-butadiene-styrene copolymer resin. 3. A nonpolar resin sheet having a dielectric power factor of 0.006 or less at a frequency of 1 kilohertz to 1 megahertz is irradiated with ultraviolet rays having a peak at a wavelength of 380 nanometers or less, and then the nonpolar resin sheet. A laminate of non-polar resin sheets, characterized in that at least two sheets are laminated and an electric field having a frequency of 1 to 300 MHz is applied to heat the ultraviolet irradiation surface to fuse the sheets.