Method of sealing containers and lids by melt adhesion by laser

Patent metadata

Field	Value
Publication number	US-9550596-B2
Application number	US-201314387063-A
Country	US
Kind code	B2
Filing date	Mar 8, 2013
Priority date	Mar 29, 2012
Publication date	Jan 24, 2017
Grant date	Jan 24, 2017

Abstract

A method of sealing a container and a lid by melt adhesion by laser. Either the container or the lid has a thermoplastic resin that permits the laser beam to transmit through and the other one has a resin composition of the thermoplastic resin containing a heat-generating substance. Further, the laser beam applies a rectangular beam having a uniform intensity distribution. The upper-limit of temperature is not lower than a melting point of the thermoplastic resin but lower than a thermal decomposition start temperature thereof in the melt adhesion interface between the container and the lid, and the temperature reaches the upper-limit in a heating time t (msec) represented by the following formula (1),

t (msec)= L/S   (1)

where L is the length (mm) of the rectangular beam in the scanning direction, and S is the rate of laser scanning (mm/msec) of not higher than 1.65 mm/msec.

First claim

The invention claimed is:

1. A method of sealing a container and a lid by melt adhesion by a laser beam, wherein
said container is a cup type container having a bottom portion, a body portion and a flange portion, said lid is a lid formed in a dented shape, said container comprising a thermoplastic resin that permits the laser beam to transmit therethrough, said lid comprising a resin composition of the thermoplastic resin containing a heat-generating substance that generates heat upon absorbing the laser beam;
the method comprising applying the laser beam to a contacting surface of the flange portion and a circumferential portion of the lid from a lower side of the container in a state where the container and the lid are being pushed and closely contacted to each other by use of a pushing jig, wherein
said laser beam is capable of applying a rectangular beam having a uniform intensity distribution,
an upper-limit of temperature that is elevated by the application of the laser beam lies in a range of not lower than a melting point of said thermoplastic resin but lower than a thermal decomposition start temperature thereof in a melt adhesion interface between said container and said lid, and
the temperature reaches said upper-limit in a heating time t (msec) represented by the following formula (1),
t (msec)= L/S   (1)

wherein L is the length (mm) of the rectangular beam in the scanning direction, and S is the rate of laser scanning (mm/msec) of not higher than 1.65 mm/msec.

2. The sealing method according to claim 1 , wherein said thermoplastic resin is any one of a styrene resin, an olefin resin or a polyester resin.

3. The sealing method according to claim 1 , wherein the rate of laser scanning is 1.40 to 1.65 mm/msec.

Assignees

• Toyo Seikan Group Holdings Ltd

Inventors

• Sawada Makoto
• Shinozaki Kiyotaka
• Shinagawa Yoshiaki
• Yamasaki Jun

Classifications

• B29C65/1635 Primary

  at least passing through one of the parts to be joined, i.e. laser transmission welding · CPC title

• B29C66/91411

  of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account · CPC title

• B29K2023/18

  Polymers of hydrocarbons having four or more carbon atoms, e.g. polymers of butylene, e.g. PB, i.e. polybutylene · CPC title

• B29K2995/0027

  for light outside the visible spectrum · CPC title

• B29C66/542

  joining hollow covers or hollow bottoms to open ends of container bodies · CPC title