JPS6244429A - Joining method of synthetic resin material - Google Patents

Abstract

PURPOSE:To join both synthetic resin materials easily without deteriorating strength of them, by a method wherein the synthetic resin materials are piled up each other, a short fiber is mixed with a joining part, against which welding member which is nonabsorbent to laser rays is made to abut, to which the laser rays are directed. CONSTITUTION:Welding members 4a, 4b are set to joining surfaces 3a, 3b, 3c, 3d of plate members 1, 2 composed of different kinds of synthetic resin materials. As for the welding members 4a, 4b, a 15wt% glass short fiber 5 is mixed with a stylene- acrylonitrile copolymer and they have nonabsorbent properties to the laser rays. When YAG laser rays 7 are irradiated to the surface of the molding member 4a, they arrive at the plate members 1, 2 are joining surfaces 3a, 3b composed of synthetic resin having absorbent properties to the YAG laser rays 7 and accumulated as energy. As for the energy, distribution of the same becomes unequal at the time of transmission of the same through the welding material 4a, heating and melting are performed at the joining surfaces 3a, 3b, and entangled joining is generated among both the plate members 1, 2 and the welding member 4a through the glass fibers 5. Irradiation with the laser rays 7 is carried out similarly on a welding member 4b side also.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of overlapping or abutting 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, in the former physical joining method, a heating element such as a metal mesh is used to generate heat at the joining surfaces of the synthetic resin materials to be joined, and the joining surfaces of both synthetic resin materials are melted while being pressurized and cooled. 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 the same type of synthetic resin materials, 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 resin materials, the melting temperatures of the two synthetic resin materials are different and the compatibility is poor.
It is difficult to join both synthetic resin materials. In addition, in the latter chemical joining method, when joining synthetic resin materials of the same type, the material is passed through in the same manner as the former physical joining method, but when joining different kinds of synthetic resin materials, the synthetic resin material The adhesive force of the adhesive decreases depending on the material of the material, 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 resin, in the same way as with different types of synthetic resin materials.

Due to the above-mentioned reasons, many mechanical joining methods are 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 is shown in Figure 5. This will be explained using a method of joining polypropylene and polyethylene.

In FIG. 5, 51 is 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 are disposed. 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, the drawing board member 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 consists of overlapping or abutting synthetic resin materials that are absorbent to laser light, and short fibers are mixed in the joint portion, and the material is made of synthetic resin materials that are absorbent to laser light. By bringing a non-absorbing welding member into contact with the two synthetic resin materials and irradiating laser light from the direction of the welding member, the two synthetic resin materials can be easily joined without reducing their strength.

[Means for solving problems]

That is, in the method for joining synthetic resin materials according to the present invention, when the synthetic resin materials that are absorbent to laser light are overlapped or butted to join them, short fibers are present at the joining site of both synthetic resin materials. A welding member made of a synthetic resin material that is mixed in and does not absorb laser light is brought into contact with the welding member, and the laser light is transmitted and irradiated from the direction of this welding member to both synthetic resin materials to be joined. This is what I did.

Synthetic resin materials that absorb laser light include polyethylene resin with added auxiliary materials such as carbon blank, polypropylene resin, and styrene reinforced with glass fiber and with carbon blank added.
Examples include acrylonitrile copolymers. In addition, synthetic resin materials that are non-absorbent to laser light and are used as welding parts include polypropylene resin reinforced with one or more types of short fibers such as glass fiber, carbon fiber, and metal fiber, and styrene-acrylonitrile resin. Copolymers and the like can be mentioned. The amount of short fibers mixed into the synthetic resin material is preferably 5 to 30% by weight based on the synthetic resin material in order to improve the bonding strength, and 10 to 20% by weight is excellent. If the amount of short fibers mixed in is less than 5% by weight, it will be difficult to obtain the desired bonding strength between the two synthetic resin materials to be bonded, and if it is more than 30% by weight, not only will the bonding strength not improve despite the amount of short fibers mixed in, but the laser The light transmittance may decrease and it may become impossible to heat and melt both synthetic resin materials to be joined.

In addition, lasers used when joining different or similar synthetic resin materials include glass:neodymium laser, Y
AG: neodymium 1+ laser, ruby laser, helium-neon laser, krypton laser, argon laser, N2 laser, N2 laser, etc., among which 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, in terms of laser output, 5W to 100W passes through, and 5W to 3
0W is the best. 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 evaporate or change in quality. Therefore, joining is impossible.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

(First Example) FIG. 1 is a schematic cross-sectional view illustrating a first example of the method for joining synthetic resin materials according to the present invention, and FIG. 2 is an enlarged cross-sectional view of the ellipse of section A in FIG. It shows.

In FIG. 1, 1 is a plate member made of styrene-acrylonitrile copolymer reinforced with glass fibers, and the raw material color of this plate member 1 is black with 0.51iit% of carbon black mixed in. 1.
It has the property of absorbing laser light of 0.06 μm or less.

Further, on the upper part of the plate member 1, a plate member 2 made of polypropylene resin reinforced by adding glass fibers is superimposed on each other with the end surfaces 1a and 2a shifted from each other, and the plate member 1
The upper surface 1b and the end surface 2a of the plate member 2, and the lower surface 2b of the plate member 2 and the end surface 1a of the plate member 1 are bonded to surfaces 3a, 3b, 3c.
, 3d. The raw material color of this plate member 2 is black due to the addition of 0.5% by weight of carbon, and has the property of absorbing laser light of 1.06 μm or less.

When joining the plate members 1.2 made of different types of synthetic resin materials set as shown in FIG.
．． Welding members 4a, 4b having substantially triangular cross sections are brought into contact with and set on the joint surfaces 3a, 3b, 3c, 3d of 2. These welding members 4a, 4b are made of styrene-acrylonitrile copolymer mixed with 15% by weight of short glass fibers 5, the raw material color is milky white, and the diameter is 1.06 μm.
It has non-absorbing properties for the following laser beams.

Next, the irradiation nozzle 6 of a YAG: neodymium laser is brought into contact with the surface of the welding member 4a made of styrene-acrylonitrile copolymer, and the irradiation nozzle 6 emits a laser with a wavelength of 1.06 μm and an output of 20W. The YAG laser beam 7 is passed through the convex lens 6a and irradiated.

At this time, the YAG laser beam 7 is not absorbed by the welding member 4a made of styrene-acrylonitrile copolymer 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 7 is
In synthetic resin materials that do not have a single crystal structure, the light does not travel straight in the direction of the irradiation, but in a scattered state. The YAG laser beam then reaches the joint surfaces 3a, 3b between the welding member 4a and the plate members I, 2 made of styrene-acrylonitrile copolymer and polypropylene resin, which are absorbent to the YAG laser beam, and is stored there as energy. This Mla energy distribution is YAG
The energy distribution that the laser beam 7 had in advance becomes uneven due to scattering when it passes through the welding member 4a. Since the joint surfaces 3a and 3b are heated and melted with such uneven energy distribution, both plate members 1.2 and the welding member 4a are mixed into the welding member 4a. The glass fibers 5 interposed between each other create an intertwined bond.

At this time, while irradiating the YAG laser beam 7 from the irradiation nozzle 6, it is necessary to apply weight from the direction of arrow B as shown in FIG. 1 to keep both plate members 1.2 in close contact with each other. however,
This may be done by separating the irradiation nozzle 6 from the 7g contact member 4a and bringing it into close contact with the drawing board member 1.2 in advance using other means, such as a mechanical clamp.

Thereafter, the irradiation of the YAG laser beam 7 from the irradiation nozzle 6 is stopped, and the irradiation nozzle 6 is separated from the styrene-acrylonitrile copolymer welding member 4a to remove the load on both plate members 1.2.

As a result, as shown in FIG. 2, the melt of both the plate members 1.2 and the welding member 4a and the short glass fibers 5 enter into each other and harden in an entangled state, and the plate member made of styrene-acrylonitrile copolymer l. The plate member 2 made of polypropylene resin and the welding member 4a made of styrene-acrylonitrile copolymer are firmly joined.

Furthermore, if the YAG laser beam 7 is continuously moved along a plane (up and down diagonal directions in Figure 1) while irradiating it, a heating temperature gradient will occur in the direction of movement, and the YAG laser beam The non-uniformity of the energy distribution in No. 5 is further increased, and an even stronger bond can be obtained.

Further, in the same manner as the joining of the welding member 4a side, the welding member 4
The b side is also irradiated with the laser beam 7. As a result, the plate member 1 made of styrene-acrylonitrile copolymer is replaced by the plate member 2 made of polypropylene resin and the styrene-acrylonitrile copolymer.
The welding member 4b made of acrylonitrile copolymer is firmly joined.

(Second Embodiment) FIG. 3 is a schematic sectional view illustrating a second embodiment of the method for joining synthetic resin materials according to the present invention.

This second embodiment is similar to the first embodiment in many respects;
Identical parts will be given the same numbers, explanations thereof will be omitted, and only differences will be described.

The difference in the second embodiment is that the end surfaces 1a and 2a of the plate member 1.2 similar to the first embodiment are brought into contact with each other, and the upper end surfaces 1a and 2a have a joint surface cut out on the side that is open to each other. 3a, 3b are formed, and a welding member 4a similar to that of the first embodiment is brought into contact with the joint surfaces 3a, 3b.
An irradiation nozzle 6 similar to that in the embodiment is positioned above the welding member 4a, and a YAG laser beam 7 with a wavelength of 1.06 μm and an output of 20 W is passed through the convex lens 6a and irradiated in the same manner as in the first embodiment. This is what I did.

As a result, as shown in FIG. 3, both the plate members 1.2 and the melt of the welding member 4a and the glass rectangular fibers 5 of the welding member 4a are joined together in a state that they are embedded in each other, and the plate made of styrene-acrylonitrile copolymer is bonded. The member 1, the plate member 2 made of polypropylene resin, and the welding member 4a made of styrene-acrylonitrile copolymer are firmly joined.

(Third Embodiment) FIG. 4 is a schematic cross-sectional view illustrating a third embodiment of the method for joining synthetic resin materials according to the present invention.

This third embodiment is similar to the first embodiment in many respects;
Identical parts will be given the same numbers, explanations thereof will be omitted, and only differences will be described.

The difference in the third embodiment is that plate members 1.2 similar to those in the first embodiment are stacked, both plate members l and 2 are set upright, and the end surface of the set up plate member 1.2 is 1a, 2a first
After a rectangular welding member 44 made of the same material as in the embodiment is brought into contact, an irradiation nozzle 6 similar to that in the first embodiment is brought into contact with the upper surface of the welding member 44, and the wavelength is 1.06 μm and the output is A 20 W YAG laser beam 7 is passed through a convex lens 6a and irradiated in the same manner as in the first embodiment.

As a result, as shown in FIG. 4, the melt of both the plate members 1.2 and the welding member 44 and the short glass fibers 55 of the welding member 44 are joined together in a state where they are embedded in each other, and the plate made of styrene-acrylonitrile copolymer is bonded. The member I, the plate member 2 made of polypropylene resin, and the welding member 44 made of styrene-acrylonitrile copolymer are firmly joined.

〔Effect of the invention〕

As explained above, in the method for joining synthetic resin materials according to the present invention, synthetic resin materials that are absorbent to laser light are overlapped or butted together, short fibers are mixed in the joined portion, and the laser beam is emitted. Since a non-absorbing welding member is brought into contact with the welding member and the laser beam is irradiated from the direction of the welding member, both synthetic resin materials and the welding member are melted and joined from the joint surfaces of the welding member. This has the effect of allowing both synthetic resin materials to be joined without reducing their strength.

In addition, in the present invention, since the laser beam is irradiated from the direction of the welding member that is in contact with the joint portion of both synthetic resin materials, the molten material of both synthetic resin materials and the welding member is formed into short fibers. Since they enter into each other and become entangled with each other as a mediator, 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 welding member, so the joining of synthetic resin materials is easier than with conventional mechanical joining methods. There is an effect that can be done.

In addition, in the present invention, since the joint ends of the synthetic resin materials can be joined while being sealed by the welding member, there is no fixing means such as screws at the joining site of both synthetic resin materials, and the design effect is improved. There is an effect that can be done.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view illustrating a first embodiment of the method for 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. FIG. 3 is a schematic sectional view illustrating a second embodiment of the method for joining synthetic resin materials according to the present invention. FIG. 4 is a schematic cross-sectional view illustrating a third embodiment of the method for joining synthetic resin materials according to the present invention. FIG. 5 is a schematic cross-sectional view illustrating a conventional method of joining synthetic resin materials. 1----One plate member 2---Plate members 3a, 3b, 3C13d -11--Joint surface 4a, 4b
, 44--Welding member 5.55--Glass short fiber 6--Irradiation nozzle 6a--Convex lens 7--Y A G laser beam Fig. 1 Fig. 2 - 3rd - 40th

Claims (1)

[Claims] When synthetic resin materials that absorb laser light are overlapped or butted to join them, short fibers are mixed into the joining area of both synthetic resin materials, and the synthetic resin is non-absorbent to laser light. A method for joining synthetic resin materials, characterized by bringing a welding member made of the material into contact with the welding member, and transmitting a laser beam to both synthetic resin materials to be joined from the direction of the welding member.