Laser-welded article

Abstract

It is an object of the present invention to provide a laser-welded article that workpieces prepared simply can be easily unified by laser in one laser welding process without using complicated processes. Moreover, the laser-welded article has an excellent appearance and sufficient welding strength of the molded workpieces, and does not damage the resin property. The laser-welded article comprises: an integral construction of a single workpiece that at least a part of curled workpiece is overlapped or plural workpieces that at least a part of each workpiece is piled, which is welded by exothermic through irradiating laser, wherein the single laser-transmissible-absorptive molded workpiece or the plural laser-transmissible-absorptive molded workpieces include a thermoplastic resin and a laser-transmissible absorbent to have an absorbance: a ranging from 0.07 to 2.0, and have abilities of absorbing at least partial beam of the laser and transmitting another partial beam of the laser.

What is claimed is: 
     
       1. A laser-welded article comprising:
 an integral construction of a single laser-transmissible-absorptive molded workpiece where at least a part of a bent workpiece is overlapped, or a plurality of laser-transmissible -absorptive molded workpieces where at least a part of each workpiece is piled, 
 the integral construction being welded by heat generated from irradiation with a laser through laser welding by melting overlapped portions of the single laser-transmissible-absorptive molded workpiece, or laser welding by melting piled portions of the plurality of laser-transmissible-absorptive molded workpieces, the laser generating rays having a wavelength ranging from 800 nm to 1600 nm, 
 wherein the single laser-transmissible-absorptive molded workpiece or the plurality of laser-transmissible-absorptive molded workpieces have an absorbance “a” throughout the workpiece or the workpieces ranging from 0.07 to 0.8 converted into an absorbance of the molded workpiece with 1 mm thickness, and have an ability of absorbing at least a partial beam of the laser and transmitting another partial beam of the laser, the single laser-transmissible-absorptive molded workpiece or the plurality of laser-transmissible-absorptive molded workpieces including: 
 a thermoplastic resin selected from the group consisting of polyamide resin, polycarbonate resin, polyphenylene sulfide resin, polybutylene terephthalate resin, and polypropylene resin, and 
 a laser-transmissible absorbent of nigrosine dye, where the content of laser-transmissible absorbent ranges from 0.001 to 0.5 weight % against the thermoplastic resin. 
 
     
     
       2. The laser-welded article according to  claim 1 , wherein the integral construction of the single laser-transmissible-absorptive molded workpiece is welded where edge portions of the single laser-transmissible-absorptive molded workpiece overlap. 
     
     
       3. The laser-welded article according to  claim 1 , wherein the integral construction of the plurality of laser-transmissible-absorptive molded workpieces is welded where edge portions of the piled portions of the plurality of laser-transmissible -absorptive molded workpieces overlap. 
     
     
       4. The laser-welded article according to  claim 1 , wherein the thermoplastic resin is polyamide resin and an absorbance “a” of the laser-transmissible-absorptive molded workpiece ranges from 0.1 to 0.8. 
     
     
       5. The laser-welded article according to  claim 1 , wherein the thermoplastic resin is polycarbonate resin and an absorbance “a” of the laser-transmissible-absorptive molded workpiece ranges from 0.1 to 0.8. 
     
     
       6. The laser-welded article according to  claim 1 , wherein the thermoplastic resin is polypropylene resin and an absorbance “a” of the laser-transmissible-absorptive molded workpiece ranges from 0.1 to 0.8. 
     
     
       7. The laser-welded article according to  claim 1 , wherein the plurality of laser-transmissible-absorptive molded workpieces are used, and a ratio a 1 /a 2  defined by an absorbance “a 1 ” of a first workpiece that the laser irradiates and an absorbance “a 2 ” of a second workpiece that is piled to the first workpiece ranges from 0.8to 1.3. 
     
     
       8. The laser-welded article according to  claim 7 , wherein the ratio a 1 /a 2  is 1. 
     
     
       9. The laser-welded article according to  claim 1 , wherein at least one of C 1 L 1  and C 2 L 2  ranges from 0.01×10 −3  to 4.0×10 −3 , wherein
 C 1 L 1  is a product of a concentration C 1  (weight %) of the laser-transmissible absorbent of a first workpiece of the integral construction of the plurality of laser-transmissible-absorptive molded workpieces, and L 1  (cm) is a thickness of the first workpiece of the integral construction of the plurality of laser-transmissible-absorptive molded workpieces, and C 2 L 2  is a product of a concentration C 2  (weight %) of the laser-transmissible absorbent of a second workpiece of the integral construction of the plurality of laser-transmissible-absorptive molded workpieces, and L 2  (cm) is a thickness of the second workpiece of the integral construction of the plurality of laser-transmissible-absorptive molded workpieces. 
 
     
     
       10. The laser-welded article according to  claim 1 , wherein the single laser-transmissible-absorptive molded workpiece or the plurality of laser-transmissible-absorptive molded workpieces have a thickness ranging from 200 to 5000microns. 
     
     
       11. The laser-welded article according to  claim 1 , wherein the thermoplastic resin is at least one resin selected from the group consisting of polyamide resin, polycarbonate resin and polypropylene resin, and the content of the laser-transmissible absorbent ranges from 0.002 to 0.2 weight % against the thermoplastic resin. 
     
     
       12. The laser-welded article according to  claim 1 , wherein the thermoplastic resin is at least one resin selected from the group consisting of polybutylene terephthalate resin or polyphenylene sulfide resin, and the content of the laser-transmissible absorbent ranges from 0.001 to 0.2 weight % against the thermoplastic resin. 
     
     
       13. The laser-welded article according to  claim 1 , wherein the laser-transmissible-absorbent has an absorption coefficient E d  ranging from 1000 to 8000(ml/g·cm). 
     
     
       14. The laser-welded article according to claim 1, wherein the tensile stress strength of the prepared laser-welded article is 50N or more in accordance with Japanese Industrial Standard K-7113-1995. 
     
     
       15. A laser-welded article comprising:
 an integral construction of a single laser-transmissible-absorptive molded workpiece where at least a part of a bent workpiece is overlapped, or a plurality of laser-transmissible-absorptive molded workpieces where at least a part of each workpiece is piled,   the integral construction being welded by heat generated from irradiation with a laser through laser welding by melting overlapped portions of the single laser-transmissible-absorptive molded workpiece, or laser welding by melting piled portions of the plurality of laser-transmissible-absorptive molded workpieces, the laser generating rays having a wavelength ranging from 800 nm to 1600 nm,   wherein the single laser-transmissible-absorptive molded workpiece or the plurality of laser-transmissible-absorptive molded workpieces have an absorbance “a” throughout the workpiece or the workpieces ranging from 0.07 to 0.8 converted into an absorbance of the molded workpiece with 1 mm thickness, and have an ability of absorbing at least a partial beam of the laser and transmitting another partial beam of the laser, the single laser-transmissible-absorptive molded workpiece or the plurality of laser-transmissible-absorptive molded workpieces including:   a thermoplastic resin selected from the group consisting of polyamide resin, polycarbonate resin, polyphenylene sulfide resin, polybutylene terephthalate resin, and polypropylene resin, and   a laser-transmissible absorbent of nigrosine dye selected from the group consisting of C.I. Solvent Black 5 and C.I. Solvent Black 7, where   the content of laser-transmissible absorbent ranges from 0.001 to 0.5 weight % against the thermoplastic resin.   
     
     
       16. The laser-welded article according to claim 15, wherein the integral construction of the single laser-transmissible-absorptive molded workpiece is welded where edge portions of the single laser-transmissible-absorptive molded workpiece overlap. 
     
     
       17. The laser-welded article according to claim 15, wherein the integral construction of the plurality of laser-transmissible-absorptive molded workpieces is welded where edge portions of the piled portions of the plurality of laser-transmissible-absorptive molded workpieces overlap. 
     
     
       18. The laser-welded article according to claim 15, wherein the thermoplastic resin is polyamide resin and an absorbance “a” of the laser-transmissible-absorptive molded workpiece ranges from 0.1 to 0.8. 
     
     
       19. The laser-welded article according to claim 15, wherein the thermoplastic resin is polycarbonate resin and an absorbance “a” of the laser-transmissible-absorptive molded workpiece ranges from 0.1 to 0.8. 
     
     
       20. The laser-welded article according to claim 15, wherein the thermoplastic resin is polypropylene resin and an absorbance “a” of the laser-transmissible-absorptive molded workpiece ranges from 0.1 to 0.8. 
     
     
       21. The laser-welded article according to claim 15, wherein the plurality of laser-transmissible-absorptive molded workpieces are used, and a ratio a 1 /a 2  defined by an absorbance “a 1 ” of a first workpiece that the laser irradiates and an absorbance “a 2 ” of a second workpiece that is piled to the first workpiece ranges from 0.8 to 1.3. 
     
     
       22. The laser-welded article according to claim 21, wherein the ratio a 1 /a 2  is 1. 
     
     
       23. The laser-welded article according to claim 15, wherein at least one of C 1 L 1  and C 2 L 2  ranges from 0.01×10 −3  to 4.0×10 −3 , wherein C 1 L 1  is a product of a concentration C 1  (weight %) of the laser-transmissible absorbent of a first workpiece of the integral construction of the plurality of laser-transmissible-absorptive molded workpieces, and L 1  (cm) is a thickness of the first workpiece of the integral construction of the plurality of laser-transmissible-absorptive molded workpieces, and
 C 2 L 2  is a product of a concentration C 2  (weight %) of the laser-transmissible absorbent of a second workpiece of the integral construction of the plurality of laser-transmissible-absorptive molded workpieces, and L 2  (cm) is a thickness of the second workpiece of the integral construction of the plurality of laser-transmissible-absorptive molded workpieces. 
 
     
     
       24. The laser-welded article according to claim 15, wherein the single laser-transmissible-absorptive molded workpiece or the plurality of laser-transmissible-absorptive molded workpieces have a thickness ranging from 200 to 5000 microns. 
     
     
       25. The laser-welded article according to claim 15, wherein the thermoplastic resin is at least one resin selected from the group consisting of polyamide resin, polycarbonate resin and polypropylene resin, and the content of the laser-transmissible absorbent ranges from 0.002 to 0.2 weight % against the thermoplastic resin. 
     
     
       26. The laser-welded article according to claim 15, wherein the thermoplastic resin is at least one resin selected from the group consisting of polybutylene terephthalate resin or polyphenylene sulfide resin, and the content of the laser-transmissible absorbent ranges from 0.001 to 0.2 weight % against the thermoplastic resin. 
     
     
       27. The laser-welded article according to claim 15, wherein the laser-transmissible-absorbent has an absorption coefficient ε d  ranging from 1000 to 8000 (ml/gcm).