Plastic parts are welded with a true 3D volumetric weld using intersecting multi-beam trace laser welding in which a plurality of spot laser beams having the same wavelength are directed to the so that the laser beams intersect each other at a point along a weld path within one of the plastic parts at an angle in an intersection angle range between ten degrees and ninety degrees. The plurality of laser beams are traced so that the intersection of the plurality of laser beams traces along the weld path to form a weld pattern that is linear, curvilinear, planar or three dimensional along a joint that is inside a volume of plastic. The plastic part in which the laser beams intersect is partially absorptive to laser light at a wavelength and the laser beams have this wavelength.

The invention relates to additive mixtures for plastics containing phosphinic acid salt of formula (I) as component A,

##STR00001##

where R.sub.1 and R.sub.2 mean ethyl, M is Al, Fe, TiO.sub.p or Zn, m means 2 to 3, preferably 2 or 3, and p=(4m)/2 is a compound selected from the group of Al salts, Fe salts, TiO.sub.p salts or Zn salts of ethylbutylphosphinic acid, dibutylphosphinic acid, ethylhexylphosphinic acid, butylhexylphosphinic acid and/or dihexylphosphinic acid as component B, phosphonic acid salt of formula (II) as component C,

##STR00002##

where R.sub.3 means ethyl, Met is Al, Fe, TiO.sub.q or Zn, n means 2 to 3, preferably 2 or 3, and q=(4n)/2, and copper as component D.

The invention relates to a method for welding a connection between a first joining surface of a first molded part and a second joining surface of a second molded part, which by means of a clamping device are moved and braced with their joining surfaces in contact with one another, wherein the first molded part is at least partially transparent for a primary beam of a first radiation source and at least partially absorbent for a secondary beam of a second radiation source, and the second molded part is at least partially absorbent for the primary beam, wherein sequentially the second molded part is irradiated with the primary beam and the first molded part is irradiated with the secondary beam.

A rubber member for laser bonding of the present invention containing a rubber ingredient and silica, wherein the silica has an average particle size of more than 50 nm and 120 nm or less, and the amount of the silica is 10 parts by mass to 50 parts by mass based on 100 parts by mass of the rubber ingredient, the rubber member has a laser light transmittance of 30% or more, provided that the laser light transmittance is a transmittance when the rubber member has a thickness of 2 mm and is irradiated with laser light having a wavelength of 808 nm. The silica preferably includes silica having an average particle size of more than 50 nm and 120 nm or less and silica having an average particle size of 5 nm to 50 nm, and the amount of the silica having an average particle size of more than 50 nm and 120 nm or less is 10 parts by mass to 50 parts by mass based on 100 parts by mass of the rubber ingredient and the amount of the silica having an average particle size of 5 nm to 50 nm is 10 parts by mass to 50 parts by mass based on 100 parts by mass of the rubber ingredient.

A method of joining a metal and a plastic member, a method of joining a CFRP member and a plastic member, a method of joining a metal and a CFRP member through a plastic member, in particular a method of joining members able to join members by a faster joining speed and able to give a joined member excellent in joining strength are provided. A method of joining a metal and a plastic member by overlaying a metal and a plastic member and joining them by firing a laser beam from the plastic member side, comprising overlaying the plastic member and glass through which the laser beam will pass on the metal in that order and firing the laser beam from the plastic member side through the glass at a joining location where the metal and the plastic member are overlaid to join them by a joining speed of 0.5 m to 5.0 m/min.

A method for joining thermoplastics to glass comprising placing a sheet of continuous glass filled thermoplastic composite under glass; applying a predetermined amount of force on the bottom of the composite to achieve adequate contact and compaction between the composite and the glass; using a laser with a predetermined wavelength having a predetermined spot size to apply a predetermined amount of power to a predefined region of the composite and the glass at a predetermined speed, thereby creating a weld between the composite and the glass; cooling the joined materials for a predetermined period of time while still under compaction pressure; and removing the compaction pressure to access the joined materials.

A method for curing an adhesive composition includes: arranging an adhesive composition that transmits laser light of a first wavelength in contact with a surface of a first adherend that contains, at least at its surface, a first light-to-heat conversion material that generates heat by absorbing laser light of the first wavelength; and curing the adhesive composition by irradiating the adhesive composition and the first adherend with laser light of the first wavelength. In a method for manufacturing a bonded structure, a first bonded structure is manufactured by bonding the adhesive composition to the first adherend by using the method for curing an adhesive composition.

An article for laser marking can comprising: a thermoplastic composition comprising a thermoplastic polymer, an active component comprising at least one of a polymeric unit and an additive, wherein the thermoplastic polymer has a visible transmission of greater than or equal to 80% according to ASTM D1003-00, Procedure A, using D65 illumination, 10 degrees observer, and thickness of 1 mm; and a mark produced by chemical rearrangement of the active component generated by a laser of a first wavelength; wherein the mark exhibits at least one of: (i) a change in optical properties in the region 400 nm to 700 nm when exposed to light having a wavelength less than or equal to 500 nm; and (ii) a change in optical properties in the region of 400 nm to 700 nm when exposed to light having a wavelength greater than or equal to the first wavelength.

A laser welding method and system for joining portions of first and second workpieces of thermoplastic material that is partially permeable to a laser beam but absorbs radiation from the laser beam. The first and second workpieces, which are made of material that absorbs radiation from a laser beam, are clamped together. A mask is placed on a first surface of the first workpiece, the first surface being opposite the surface engaging the second workpiece. The mask is impermeable to a laser beam and forms a slot for passing a laser beam to the portion of the first surface of the upper workpiece exposed by the slot, so that heating and melting of the material of the workpieces is limited to the width of the slot. A laser beam is directed onto the slot and moved in a manner to illuminate the slot to melt and join the workpieces.

A laser-welded body includes at least three of resin members, which contain a thermoplastic resin including: a first resin member which is a laser-irradiated subject, has an absorbance a.sub.1 of 0.01 to 0.12; a second resin member which has an absorbance a.sub.2 of 0.1 to 0.9 and includes a butted part where ends of one or more resin members are brought into contact with each other; and a third resin member which has an absorbance a.sub.3 of 0.2 to 3.8, and the absorbances a.sub.2, a.sub.3 exhibited by the second resin member and the third resin member are attributed to the inclusion of nigrosine as a laser beam absorbent therein, and the resin members are overlapped in the above mentioned to form contacted parts at these interfaces, at least a part of the butted part and/or the contacted parts are laser-welded.