JP2008119839A - Laser welding method for resin material and resin component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To mutually subject laser absorbable resins to butt welding while ensuring stable and sufficient welding depth without sacrificing productivity. <P>SOLUTION: Laser absorbable resin materials 11 and 12 containing a nigrosine dye being one of black colorants are abutted on each other and the abutted parts 13 of them are irradiated with a laser beam La to subject both resin materials to butt welding. The laser absorption of the irradiated surfaces of both resin materials is suppressed low by selecting the nigrosine dye as the black colorant and the laser beam La reaches the regions deep from the surfaces of the resin materials to obtain the welded part 14 having a welding depth D of 0.4 mm or above. In a case adapted to the manufacture of an electronic part housing case, sufficient sealability can be ensured. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser welding method in which resin materials are welded together by irradiating a laser beam, and a resin component manufactured by applying this laser welding method.

  Conventionally, laser welding between resin materials is generally performed by superimposing a laser-transmitting resin material that is transparent to laser light and a laser-absorbing resin material that is absorbing to laser light, to form a laser-transmitting resin. Laser beam is irradiated to the mating surface of both resin materials through the material, and the laser transmitting resin material is also heated by the heat generation of the laser absorbing resin material to fuse the mating portions. As the laser-absorbing resin material, a material containing carbon black is often used, but recently, a material containing nigrosine dye, aniline black, or the like is also used (for example, see Patent Document 1). .

  FIG. 3 shows an example in which the laser welding method described above is applied to the manufacture of a storage case for a vehicle-mounted electronic component. In this case, the case body 1 is made of a laser-absorbing resin material and the cover 2 is made laser-transmissive. Each is formed by a resin material, and welding is performed by irradiating a laser beam La from above the cover 2 in a state where the cover 2 is superimposed on the case body 1.

  By the way, since the storage case for the above-described vehicle-mounted electronic component is placed in an environment where temperature change and humidity change are large, high sealing performance (watertightness, airtightness) that can withstand environmental changes is required. However, as described above, in the laser welding method in which the resin materials are overlapped and welded, the heating and melting states change due to the variation in the transmittance of the laser-transmitting resin material, and the unwelded, foamed, burned (burned) There was a problem that problems such as these are likely to occur. In particular, in resin molding of large products (for example, 80 mm x 30 mm) such as the cover 2 of the above storage case, a multi-point gate arrangement is adopted for reasons such as restricting resin fluidity and ensuring dimensional stability. However, in this case, since a weld is formed in the molded body, a significant change in the transmittance is unavoidable, and the occurrence of the above-described problems becomes significant. In addition, in this type of storage case, polybutylene terephthalate (PBT) or polyphenylene sulfide (PPS) is used in consideration of strength, heat resistance, moldability, etc. These resin materials are polyethylene (PE), Since the transmittance is lower than that of polypropylene (PP), the output of the laser beam must be set high, there is a risk of foaming due to overheating, and a resin part having a desired sealing property can be stably obtained. There was also a problem that it was difficult.

  On the other hand, as a laser welding method, there has been conventionally known a method in which laser-absorbing resin materials are butted together and a laser beam is irradiated to the butted portion so that both resin materials are butted and welded. According to this butt welding method, since the laser beam is directly irradiated to the butt portion between the resin materials, if this is applied to the manufacture of the storage case, there is a problem of occurrence of defects due to variation in transmittance and weld formation. This is expected to be prevented. When the butt welding method is applied to the production of the storage case, as shown by the one-dot chain line in FIG. 3, the laser beam La from the side with respect to the joint portion of the case body 1 and the cover 2. Will be irradiated. However, when laser-absorbing resin materials are actually butt-welded, most of the energy of the laser beam is absorbed by the irradiated surface, so that the penetration depth is extremely shallow and the desired sealing property is ensured. It was difficult. If the laser beam output is simply increased in order to increase the penetration depth, the irradiated surface explosively overheats to cause foaming or burning, making welding impossible.

Therefore, for example, Patent Document 2 proposes that the output of the laser light applied to the abutting portion between the laser-absorbing resin materials is reduced, and the scanning of the laser light is repeated a plurality of times. However, according to such measures, since the scanning of the laser beam is repeated a plurality of times, it takes a long time for welding, and a reduction in productivity is inevitable when welding around the entire circumference is required as in the case described above. It becomes like this.
JP 2003-320588 A JP 2005-246692 A

  The present invention has been made in view of the technical background described above, and the problem is that the laser-absorbing resin material can be stably and sufficiently penetrated without sacrificing productivity. It is an object to provide a laser welding method capable of ensuring butt welding and providing a resin part manufactured by applying the method.

  In order to solve the above-mentioned problems, a laser welding method for a resin material according to the present invention is a laser welding method in which laser-absorbing resin materials are butted together and both resin materials are butted and welded. It is characterized by ensuring depth. Thus, a desired sealing performance can be ensured by setting the penetration depth to at least 0.4 mm.

  In the following, some aspects of the present invention will be illustrated and described. In addition, the laser absorptive resin material in the following description means a resin having absorptivity with respect to near infrared laser light having a wavelength of about 1000 nm.

  (1) In a laser welding method in which laser-absorbing resin materials containing a black colorant are butted together, and the butted portion is irradiated with laser light, and both resin materials are butted and welded, the black colorant A resin welding method for a resin material, wherein a penetration depth of at least 0.4 mm is secured by selecting a specific colorant.

  In the laser welding method performed in this way, by selecting a colorant that suppresses laser absorption lower than that of carbon black as a black colorant to be included in the laser-absorbing resin material, The penetration depth is expanded and a penetration depth of at least 0.4 mm can be ensured. Therefore, a sufficiently high sealing performance can be ensured even if the resin materials having laser absorptivity are butt-welded. In addition, since it is not affected by variations in the transmittance of the laser-transmitting resin material unlike the overlap welding, it is possible to stabilize the welding of PBT or PPS having a relatively low transmittance as well as the welding of a resin material having a weld. Can be done. Furthermore, since laser absorption is suppressed to a low level, overheating on the irradiated surface is suppressed, and it is not necessary to perform laser scanning a plurality of times with a particularly low output of laser light, so that productivity is not sacrificed. .

  (2) The nigrosine dye is selected as the black colorant, and the resin material laser welding method according to item (1).

  In the present laser welding method, the black colorant contained in the resin material is not particularly limited as long as the laser absorption is lower than that of carbon black, but the nigrosine dye is useful as such a colorant. It is. Since the resin material containing this nigrosine dye has been used in the field of superposition welding as described in Patent Document 1, it is easy to obtain and is suitable as a resin material used in this laser welding method. It is.

  (3) A resin part manufactured by applying the laser welding method described in the above item (1) or (2), wherein the welding depth from the surface is 0.4 mm or more. Resin parts to be used.

  (4) The resin component according to item (3), which is configured as a storage case for electronic components.

  (5) The resin component as described in (3) or (4), wherein the laser-absorbing resin is polybutylene terephthalate (PBT) or polyphenylene sulfide (PPS).

  In the resin parts described in the items (3) to (5), since the welding depth from the surface is 0.4 mm or more, not only the strength but also the sealing property is sufficient, and the application is versatile. Expanding.

  According to the laser welding method of the present invention, the laser-absorbing resin materials can be butt-welded while ensuring a sufficient penetration depth without sacrificing the productivity of the resin welded portion. , Its utility value is great.

  Moreover, according to the resin component which concerns on this invention, not only intensity | strength but sufficient sealing performance becomes sufficient, and a use expands to many fields.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows one embodiment of a laser welding method according to the present invention. In this laser welding method, two resin materials 11 and 12 having laser absorptivity are abutted, and laser light (near-infrared laser light) La is irradiated from a laser torch (not shown) to the abutting portion 13. Both the resin materials 11 and 12 are butt-welded.

  Here, as the resin materials 11 and 12 having laser absorptivity, those containing a nigrosine dye, which is one of the black colorants, are used. In this case, the type of resin containing the nigrosine dye is arbitrary, and even if polyethylene (PE) or polypropylene (PP) with high transmittance is used, polybutylene terephthalate (PBT) or polyphenylene sulfide (PPS) with low transmittance is used. It may be. In addition, the combination of the resin material 11 and the resin material 12 may be a combination of different types of resins as long as they are compatible with each other. However, in order to improve the homogeneity of the welded portion, the same types of resins are combined. Is desirable.

  The type of the laser beam La applied to the butting unit 13 is arbitrary as long as it is a near-infrared laser beam. YAG laser, helium-neon laser, semiconductor laser, glass-neodymium laser, ruby laser, krypton laser, argon laser A hydrogen laser, a nitrogen laser, or the like can be used.

  At the time of laser welding, after the resin material 11 and the resin material 12 are abutted, a laser beam La having a predetermined output is irradiated from the laser torch toward the abutting portion 13, and the abutting portion 13 is irradiated with the laser light La. Are scanned at a predetermined speed along the alignment line. At this time, the scanning with the laser beam La may be performed by moving the laser torch while fixing the positions of the resin materials 11 and 12 or by moving the resin materials 11 and 12 while fixing the position of the laser torch. By this scanning of the laser beam La, the butted portions 13 of the resin materials 11 and 12 are continuously welded, whereby a predetermined resin component is completed.

  In the laser welding performed as described above, since the two resin materials 11 and 12 to be butt welded both contain the nigrosine dye, the laser absorption on the irradiated surface can be suppressed low, and the laser beam La is It reaches from the surface to a deep part. Thereby, the penetration depth (welding depth) in the butt portion 13 becomes a sufficient depth that satisfies the strength and the sealing performance. In FIG. 1, reference numeral 14 denotes a welded portion formed in the butt portion 13, and the weld depth D is 0.4 mm or more. Incidentally, when resin materials containing carbon black, which is the same black colorant, are bonded together by laser light, most of the laser light is absorbed by the laser light irradiation surface, so the depth of the welded portion is In this case, there are problems in terms of strength and sealability.

  The case main body 1 and the cover 2 constituting the electronic component storage case shown in FIG. 3 are molded using various resins described later, and the cover 2 is aligned with the case main body 1 as shown in FIG. Then, a laser beam La was irradiated from both the lateral direction and the upward direction to the mating portion of both, and both were welded all around by a butting method or a superposing method to complete a storage case. An air blowing port 3 is provided in advance at the bottom of the case body 1, and after the storage case is completed, an air tube 4 communicating with the air blowing port 3 is joined to the bottom surface of the case body 1. Here, as for the overall size of the storage case, the length L is 80 mm, the width in the direction perpendicular to the paper surface is 30 mm, and the height H is 16 mm. The case body 1 constituting the storage case has a wall thickness t of 2.0 mm and a height h of 15 mm, while the cover 2 has a plate thickness T of 1.0 mm.

  As resin of case body 1 and cover 2, PBT and PPS are selected, and as shown in Table 1, nigrosine dye (N) and carbon black (C) are added in various proportions as coloring agents. A colored one (laser-absorbing resin) and an uncolored one (laser-transmitting resin) to which no colorant was added were prepared, and these resins were molded separately for the case body 1 and the cover 2. The cover 2 is formed under two conditions: a condition in which a weld is formed at an intermediate portion in the longitudinal direction and a condition in which a weld is not formed. As shown in Table 1, there are two types of covers with and without a weld. 2 was prepared.

  The case body 1 and the cover 2 prepared as described above were welded in various combinations as shown in Table 1. The welding was performed under the condition that the irradiation diameter of the laser beam La on the mating portion was set to 1.5 mm, and the output of the laser beam La was variously changed as shown in Table 1 to scan at a speed of 30 mm / second. . And after welding, while performing the leak test about the completed storage case and confirming sealing performance, the destructive test was finally done and the welding depth (penetration depth) was measured. In the leak test, the storage case is stored in a cooling / heating cycle tank, and a cooling / heating cycle of −40 ° C. × 30 minutes to 140 ° C. × 30 minutes is repeated. The air was blown into the interior at an air pressure of 0.2 MPa, and leakage from the welded portion was observed visually. Table 1 shows the results of the leakage test and the destructive test described above.

  From the results shown in Table 1, as described in categories 1 to 6, both the case main body 1 and the cover 2 are combined with those molded with a laser-absorbing resin containing nigrosine dye (N), and a butt system In the case of welding, no leakage occurs even if the cooling cycle is repeated 1000 times, and the sealing performance is very good. In addition, in the combinations of sections 1 to 6, the penetration depth of the welded portion is 0.4 mm or more, and the above-described good sealing performance is brought about by the deep penetration depth. It is estimated to be. Further, from comparison between Category 1 and Category 2 and Category 3-6, the greater the content of nigrosine dye (N), the more the penetration depth tends to become shallower. However, a penetration depth of at least 0.40 mm is obtained, and it can be said that there is no problem in terms of sealing properties. Furthermore, it is clear from the comparison in the sections 1 to 6 that the resin type of PBT and PPS and the presence or absence of the weld in the cover 2 hardly affect the penetration depth and the sealing performance.

  On the other hand, when the case main body 1 and the cover 2 are combined by molding with a laser-absorbing resin containing a nigrosine dye (N) and welded by a superposition method, the laser light La is irradiated inside the cover 2. Since it does not permeate, it cannot be welded as a matter of course as described in the sections 7 and 8. In addition, when lap welding is performed by combining the cover 2 molded with an uncolored laser transmitting resin and the case main body 1 molded with the laser absorbing resin containing the nigrosine dye (N), the classification 9 10 and sections 13 and 14, if there is a weld in the cover 2, leakage will occur even if it is welded (cycle 0), and this combination is not applicable to the manufacture of electronic component storage cases. I found it possible. In addition, even when there was no weld in the cover 2, it became clear that leakage occurred after repeated 500 cycles of cooling and heating, and there was concern about application to the production of the storage case. This is presumed to be due to variations in the transmittance of the laser transmissive resin constituting the cover 2.

  On the other hand, when the case main body 1 and the cover 2 are combined by molding with a laser-absorbing resin containing carbon black (C) and welded by the butt method, the sections 11 and 12 and the sections 15 and 16 are combined. As noted, leaks occurred while still welded (cycle 0). This is because the penetration depth was shallow at 0.18 mm or less, and the irradiated surface was explosively overheated to cause burning, and the application of these combinations to the manufacture of electronic component storage cases is substantially It's impossible.

It is a schematic diagram which shows one Embodiment of the laser welding method of the resin material which concerns on this invention. It is a schematic diagram which shows the Example of this invention which aimed at the storage case of the electronic component. It is a schematic diagram which shows the conventional welding method for the storage case of the electronic component.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case main body 2 Cover 11, 12 Laser absorptive resin material 13 Butt | matching part La Laser beam

Claims (5)

  In a laser welding method in which laser-absorbing resin materials containing a black colorant are butted together and irradiated with laser light to butt-weld both resin materials, a specific color is used as the black colorant. A method for laser welding a resin material, wherein a penetration depth of at least 0.4 mm is secured by selecting an agent.   The method for laser welding a resin material according to claim 1, wherein a nigrosine dye is selected as the black colorant.   A resin part manufactured by applying the laser welding method according to claim 1 or 2, wherein a welding depth from the surface is 0.4 mm or more.   The resin component according to claim 3, wherein the resin component is configured as an electronic component storage case.   The resin component according to claim 3 or 4, wherein the laser-absorbing resin is polybutylene terephthalate or polyphenylene sulfide.

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