JPS6246621A - Joint of synthetic resin material - Google Patents

Abstract

PURPOSE:To join two synthetic resin materials without lowering their strengths by a method wherein the mating surface of synthetic resin non-absorptive to laser beams and of that absorptive thereto are treated by irradiation with plasma and, after that, mated to each other and finally irradiated with laser beams from the direction of the synthetic resin non-absorptive to laser beams. CONSTITUTION:The joint surfaces 3a and 3b of a sheet member 1 which is reinforced by adding glass fibers and made of styrene-acrylonitrile copolymer absorptive to laser beams, and of a sheet member 2 made of polypropyrene resin which is non-absorptive to laser beams are treated with low-temperature plasma and, after that, mated to each other so as to irradiate YAG laser beams over the top surface of the sheet member 2 in the state that both the sheet members 1 and 2 are brought into close contact with each other by being loaded in the direction indicated with the arrow B. The YAG laser beams 5 pass through the sheet member 2, proceed in scattered state and finally reach the joint surfaces 3a and 3b of the sheet member 1 and of the sheet member 2 so as to be stored in heat energy in order to heat and melt both the sheet members. The joining is produced in the state that the melts of both the sheet members 1 and 2 entangle with each other at the joining surfaces 3a and 3b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of superimposing different or the same types of synthetic resin materials and bonding them together using a laser beam.

[Prior art]

Conventionally, when joining synthetic resin materials, a physical joining method in which heat is applied to weld them, and a chemical joining method in which they are joined together using an adhesive have been widely used.

In other words, the former physical joining method involves heating a heating element such as a metal mesh on the joining surfaces of the synthetic resin materials to be joined, melting the joining surfaces of both synthetic resin materials, and pressurizing and cooling them. This is a method of joining resin materials. In addition, the latter chemical bonding method involves interposing an adhesive such as hot melt on the bonding surfaces of the synthetic resin materials to be bonded.
In this method, high frequency or ultrasonic waves are applied to the surface of one synthetic resin material to heat and melt the adhesive, and then both synthetic resin materials are cooled while being pressurized to join both synthetic resin materials.

However, in the former physical joining method, when joining synthetic resin materials of the same type, both synthetic resin materials have the same melting temperature and are compatible, so both synthetic resin materials are However, when joining different types of synthetic TXT resin materials, it is difficult to join the two synthetic resin materials because their melting temperatures are different and their compatibility is poor. .・In addition, the latter chemical bonding method is as suitable as the former physical bonding method when bonding synthetic resin materials of the same type, but synthetic resin is suitable for bonding different types of synthetic resin materials. The adhesive force of the adhesive decreases depending on the quality of the materials, making it difficult to firmly join both synthetic resin materials. Furthermore, even if the synthetic resin materials are of the same type, it is difficult to firmly bond synthetic resin materials with poor compatibility such as polypropylene in the same way as with different types of synthetic resin materials.

For the reasons described above, mechanical joining methods are often used when joining synthetic resin materials of poor compatibility, such as polypropylene, even if they are of the same or different types. A typical example thereof is not shown in FIG. 4, and will be explained using a method of joining polypropylene and polyethylene.

In FIG. 4, reference numeral 51 denotes a plate member made of polypropylene resin, and a plate member 52 made of polyethylene resin is disposed at the bottom of this plate member 51, and this plate member 52 of polyethylene resin and polypropylene resin Through-holes 53a and 53b are formed in opposing parts of the plate member 51.
is formed. Then, screws 55 are screwed into the through holes 53a and 53b of both plate members 51 and 52 from above with a packing 54 interposed therebetween, thereby joining both plate members 51 and 52.

[Problem that the invention seeks to solve]

However, in such mechanical joining methods,
Through holes 53a and 53b are formed in both plate members 51 and 52,
The screws 55 must be screwed together, which makes the joining work more complicated than the above-mentioned physical joining method and chemical joining method.
, 53b, both plate members 51
．． There is a problem that the strength of 52 is reduced.

Therefore, the present invention has been made to solve the above-mentioned problems, and among the synthetic resin materials to be bonded, one of them is made non-absorbent and the other is made absorbent, and at least one After plasma irradiation treatment is applied to the overlapping surfaces of the synthetic resin materials, laser light is irradiated from the direction of the non-absorbing synthetic resin material to easily join the two synthetic resin materials without reducing their strength. There is a particular thing.

[Means for solving problems]

That is, in the method for joining synthetic resin materials according to the present invention, when different or the same types of synthetic resin materials are overlapped and the two are joined together, one of the different or the same types of synthetic resin materials is exposed to a laser beam. one to make it non-absorbent, and the other one to make it absorbent to laser light,
After plasma irradiation treatment is applied to the overlapping surface of at least one of the synthetic resin materials, the two synthetic resin materials are overlaid, and the laser beam is irradiated from the direction of the synthetic resin material that does not absorb the laser beam. This is what I did.

Examples of synthetic resin materials that do not absorb laser light include polyethylene resin, polypropylene resin,
Examples include styrene-acrylonitrile copolymer, etc. Synthetic resin materials that absorb laser light include polyethylene resin, polypropylene resin, and glass fiber reinforced with auxiliary materials such as carbon blank, and Examples include styrene-acrylonitrile copolymer to which carbon black is added.

These synthetic resin materials can be freely selected and bonded in combinations of those that do not absorb laser light and those that do absorb laser light.

In addition, the plasma treatment equipment that processes the overlapping surfaces of synthetic resin materials can be used as is, and the irradiation conditions do not need to be specially set (as has been done in the past). It can be adopted as is.

In addition, a suitable plasma irradiation time is 1 to 10 seconds; if the irradiation time is less than 1 second, the activation of the overlapping surfaces to be bonded will be insufficient, resulting in wetting during bonding. However, if the irradiation time is longer than 10 seconds, the workability decreases, which leads to an increase in costs. There's a problem.

In addition, the lasers used when joining different or similar synthetic resin materials include glass: neodymium 3+ laser,
YAG: Neodymium 3''' laser, ruby laser, helium-neon laser, krypton laser, argon laser, H2 laser, N2 laser, etc.
Among these, YAG:Neodymium 3+ laser is particularly suitable.

In addition, the wavelength of the laser used when joining different or similar synthetic resin materials needs to be compatible with the synthetic resin materials to be joined, and a wavelength of 1.06 μm or less is best; In the above case, it is impossible to melt and join the joint surfaces of different or similar synthetic resin materials to each other. In addition, the output of the laser is 5W to 100W, preferably 5W to 100W.
It is W to 30W. If the output is less than 5W, the joint surfaces of different or the same types of synthetic resin materials cannot be melted together, and if the output is more than 100W, the different or the same types of synthetic resin materials may sprout or deteriorate. Therefore, joining is impossible.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

Fig. 1 is a schematic sectional view illustrating the method of joining synthetic resin materials according to the present invention, Fig. 2 is an enlarged sectional view of the ellipse of section A in Fig. 1(d), and Fig. 3 is a schematic sectional view illustrating the method of joining synthetic resin materials according to the present invention. 1 shows a schematic diagram of a plasma irradiation device used in the method.

In Figures 1 to 3, ■ is a plate member made of styrene-acrylonitrile copolymer reinforced by adding glass fiber, and the plate member 1 has a thickness of 15 cm. , the upper surface thereof is a flat joint surface 3a. The raw material color of this plate member 1 is black due to carbon black being mixed therein.1.
It has the property of absorbing laser light of 0.6 μm or less.

Further, the plate member 2 is made of polypropylene resin.

This plate member 2 is 1. Q111, and its lower surface has a flat joint surface 3b so as to be in contact with the plate member 1.
It is said that The raw material color of this plate member 2 is milky white, and has the property of not absorbing laser light of 1.06 μm or less.

Both plate members 1.2 are set in a processing chamber 22 of a commonly used plasma irradiation device 21 so that the bonding surfaces 3a and 3b are located upward.

Then, an output of 2 is applied to the joint surfaces 3a and 3b of both plate members 1.2.
00W oxygen plasma gas 23 is irradiated for 5 seconds to subject the bonding surfaces 3a and 3b of the picture plate member 1.2 to low-temperature plasma treatment.

In the figure, 24 is a vacuum pump, 25 is a microwave oscillator, 26 is an isolator, 27 is a three-stub tuner, 28 is an oxygen gas cylinder, and 29 is a flow meter.

Next, the bonding surfaces 3a and 3b of both plate members 1.2 which have been subjected to plasma treatment are overlapped as shown in FIG. 1(a). Thereafter, as shown in FIG. 1(b), the YAG:2Odium L+ laser irradiation nozzle 4 is brought into contact with the upper surface of the polypropylene resin plate member 2, and the wavelength is 1.06 μm and the output is emitted from the irradiation nozzle 4. A YAG laser beam 5 having a power of 20 W is passed through a convex lens 4a and irradiated.

At this time, the YAG laser beam 5 is not absorbed by the plate member 2 made of polypropylene resin due to the relationship between its wavelength and the absorption spectrum of the synthetic resin material, and is therefore transmitted. At this time, the YAG laser beam 5 does not travel straight in the irradiation direction, but in a synthetic resin material that does not have a single crystal structure, it travels in a scattered state. Then, styrene, which also has absorption properties for the YAG laser beam 5, is used.
Plate member 1 and plate member 2 made of acrylonitrile copolymer
It reaches the joint surfaces 3a and 3b, where f
MM is done. This accumulated energy distribution is
With respect to the energy distribution that the YAG laser beam 5 had in advance, scattering during transmission through the plate member 1 results in an uneven energy distribution.

Both bonding surfaces 3a and 3b are activated by plasma treatment and their wettability is improved, and heating and melting with such non-uniform energy distribution is performed to bond both plate members l. , 2 are intertwined with each other at the bonding surfaces 3a and 3b to form a bond.

At this time, while irradiating the YAG laser beam 5 from the irradiation nozzle 4, it is necessary to apply weight from the direction of arrow B as shown in FIG. 1(c) to keep both plate members 1.2 in close contact. be. However, instead of using the irradiation nozzle 4, other means such as a mechanical clamp may be used to bring the drawing board members 1 and 2 into close contact with each other in advance.

After the YAG laser beam 5 is irradiated for a predetermined period of time to heat and melt the joint surfaces 3a and 3b of the drawing board member 1.2, the irradiation nozzle 4 is emitted as shown in FIG. 1(d). Y
At the same time as stopping the irradiation of the AG laser beam 5, the irradiation nozzle 4 is moved away from the polypropylene resin plate member 2, and the load on both plate members 1.2 is removed. As a result, as shown in FIG. 2, the melts of the drawing board members 1.2 enter into each other and become entangled and harden, and the board member 1 made of styrene-acrylonitrile copolymer and the board member 2 made of polypropylene resin are separated. Strongly bonded.

Furthermore, if the YAG laser beam 5 is continuously moved along the surface of the plate member 2 while irradiating it, a heating temperature gradient will be generated in the direction of movement, and the energy distribution of the YAG laser beam 5 will change. The non-uniformity is further increased and an even stronger bond can be obtained.

Although this example has been explained using a method of joining different types of synthetic resin materials, the present invention is not limited to this example. Materials can also be joined. In this case, it is necessary to add a reinforcing material such as carbon black to one of the synthetic resin materials to make it absorbent to laser light. In addition, in this embodiment, the overlapping surfaces of both plate members 1.2 (joint surfaces 3a, 3b
), but in the present invention, only the overlapping surfaces of one of the synthetic resin materials can be bonded by plasma treatment.

〔Effect of the invention〕

As explained above, in the method of joining synthetic resin materials according to the present invention, one synthetic resin material is made non-absorbent to laser light, and the other synthetic resin material is made to be non-absorbent to laser light. After plasma irradiation treatment was applied to the overlapping surface of at least one of the synthetic resin materials, the laser beam was irradiated from the direction of the non-absorbing synthetic resin material, so that the overlapping surface of both synthetic resin materials Since the compatibility of certain bonding surfaces is improved and they are melted and bonded to each other, there is an effect that the two synthetic resin materials can be bonded without reducing their strength.

In addition, in the present invention, the compatibility of the overlapping surfaces is improved by plasma treatment, and the laser beam is irradiated from the direction of the non-absorbing synthetic resin material for bonding. Since they penetrate into each other and become entangled, they have the effect of making the bond stronger.

In addition, in the present invention, both synthetic resin materials are joined by irradiating laser light from the direction of the non-absorbing synthetic resin material, so compared to conventional mechanical joining methods, the synthetic resin material This has the effect of making joining easier.

Further, in the present invention, when the synthetic resin materials are joined, there is no fixing means such as screws at the joined portion of the two synthetic resin materials, so there is an effect that the design effect can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view illustrating a method of joining synthetic resin materials according to the present invention. FIG. 2 is an enlarged cross-sectional view of the ellipse of section A in FIG. 1(d). FIG. 3 is a schematic diagram of a plasma irradiation device used in the bonding method of the present invention. FIG. 4 is a schematic cross-sectional view illustrating a conventional method of joining synthetic resin materials. 1 - Plate member 2 - - - Plate members 3 a, 3 b - - - One joint surface (overlapping surface) 4 - Irradiation nozzle 4 a --- One convex lens s --- Y A c laser Hikari 21---Plasma irradiation device Applicant Toyota Motor Corporation (C) (d)
Figure 1 1' Figure 2 Figure 4 Figure 3

Claims (1)

[Claims] When overlapping synthetic resin materials and joining them, one of the synthetic resin materials is made non-absorbent to laser light, and the other is made absorbent to laser light, and at least one of the synthetic resin materials is made non-absorbent to laser light. After plasma irradiation treatment is applied to the overlapping surfaces of the synthetic resin materials, the two synthetic resin materials are overlaid, and the laser beam is irradiated from the direction of the synthetic resin material that does not absorb the laser beam. A method for joining synthetic resin materials.