Polybutylene terephthalate resin composition for fusion bonding with laser and molded article

Abstract

A laser weldable PBT-series resin composition comprises a polybutylene terephthalate (PBT)-series resin (A), and at least one resin (B) selected from the group consisting of a polycarbonate-series resin (b1), a styrenic resin (b2), a polyethylene terephthalate-series resin (b3) and an acrylic resin (b4). The PBT-series resin (A) may be a PBT homopolyester, or a PBT-series copolymer modified with not more than 30 mol % of a copolymerizable monomer (e.g., a bisphenol compound or an adduct thereof with an alkylene oxide, and an asymmetrical aromatic dicarboxylic acid). The ratio (weight ratio) of the resin (B) relative to the PBT-series resin (A) [the former / the latter] is about 0.1 / 1 to 1.5 / 1. The resin composition may comprise a glass fiber. The resin composition is excellent in laser weldability, and can improve in welding strength of a shaped article formed from the resin composition.

Description

TECHNICAL FIELD [0001] The present invention relates to a polybutylene terephthalate-series resin composition having a high laser weldability and being excellent in shaping processability (or moldability), and a shaped article using the same. BACKGROUND ART [0002] A polybutylene terephthalate (PBT)-series resin is excellent in various properties such as heat resistance, chemical resistance, electric properties, mechanical properties and shaping processability (or moldability), and is used for a number of applications. Specific examples of the applications include a variety of automotive electrical components or parts (e.g., various control units, various sensors, and ignition coils), connectors, switch parts, relay parts, and coil parts. For producing these components, a plurality of shaped components or parts are bonded (or joined) to each other with the use of a bonding (or joining) means such as an adhesive, a screw cramp, a snap fit, a hot plate welding, and an ultrasonic weldin...

AI Technical Summary

Benefits of technology

"The present invention is a resin composition that improves laser weldability and maintains a high weld strength. The composition includes a polybutylene terephthalate-series resin and at least one resin selected from the group consisting of polycarbonate-series resin, styrenic resin, polyethylene terephthalate-series resin, and acrylic resin. The ratio of the resin (B) to the polybutylene terephthalate-series resin (A) is about 0.10 / 1 to 1.5 / 1. The composition may also include a reinforcer and has a light transmittance of not less than 15% for a wavelength of 800 to 1110 nm at a thickness of 3 mm in a shaped article formed from the resin composition by injection molding. The shaped article formed from the resin composition can be bonded to a counterpart shaped article through a welding by a laser."

Problems solved by technology

Regarding these bonding means, however, some problems have been pointed out.

For example, in the case of using an adhesive, the waste of time up to curing of the adhesive, or the burden on the environment becomes an issue.

Moreover, in a means using a screw cramp, the labor or the cost required for fastening increases, and in a hot plate welding or an ultrasonic welding, there is fear that a product receives a damage due to heat, vibration, and others.

However, it is pointed out that, in the case of bonding a PBT-series resin with a laser welding, the resin cannot be substantially welded because of carbonization or others due to a low transmittance of a laser beam.

In this composition, however, it is necessary to use the graft resin in order to improve welding strength of the composition, and the use of the graft resin tends to deteriorate mechanical strength, heat resistance or others of the composition.

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