Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-09-03
2002-01-29
Mayes, Curtis (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S269000, C156S292000, C156S308400, C156S324000, C156S510000, C156S553000, C156S581000, C053S285000, C053S451000, C053S477000, C053S558000
Reexamination Certificate
active
06342123
ABSTRACT:
GOVERNMENT FUNDING
None
CROSS REFERENCE TO RELATED APPLICATION
None
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a method and apparatus for forming heat seals with films, particularly in pouches with a manually frangible (rupturable) seal. The frangible seal is preferably adjacent to hard seals which are not manually rupturable without destruction of the film. In particular, the present invention relates to a method and apparatus wherein a cooling fluid (gas or liquid) is used to cool portions of a die which forms the frangible seal.
2. Description of Related Art
The production of pouches with frangible seals which can be ruptured manually (by hand) to release or mix the contents of the pouch are well known to those skilled in the art. In particular, dual pouches separated by a frangible seal are well known to those skilled in the art. Illustrative are U.S. Pat. No. 2,932,385 to Bollmeier et al; U.S. Pat. No. 3,074,544 to Bollmeier et al; U.S. Pat. No. 3,608,709 to Pike; U.S. Pat. No. 3,913,789 to Miller; U.S. Pat. No. 4,266,692 to Clark; U.S. Pat. No. 4,312,473 to Hoeller; U.S. Pat. No. 4,462,224 to Dunshee et al; U.S. Pat. No. 4,537,308 to Hollander; U.S. Pat. No. 4,608,043 to Larkin; U.S. Pat. No. 4,805,767 to Newman; U.S. Pat. No. 4,872,556 to Farmer; U.S. Pat. No. 4,890,744 to Lane et al; U.S. Pat. No. 4,986,076 to Kirk et al; U.S. Pat. No. 4,923,095 to Dorfman et al; U.S. Pat. No. 4,952,068 to Flint; U.S. Pat. No. 5,131,760 to Farmer; U.S. Pat. No. 5,209,347 to Fabisiewicz et al; U.S. Pat. No. 5,263,609 to Hoshino; U.S. Pat. No. 5,287,961 to Herran; U.S. Pat. No. 5,364,486 to Falla et al; U.S. Pat. No. 5,423,421 to Inoue et al; U.S. Pat. No. 5,492,219 to Stupar; U.S. Pat. No. 5,494,190 to Boettcher; U.S. Pat. No. 5,616,337 to Kasianovitz et al; and U.S. Pat. No. 5,699,902 to Sperry et al.
The prior art has described the use of a lower temperature in the die to form a weaker seal which is frangible. U.S. Pat. No. 4,759,472 to Strenger discloses such a frangible seal 25 without describing how the frangible seal is produced. Frangible seals are similarly generally described in U.S. Pat. No. 4,890,744 to Lane et al., U.S. Pat. No. 5,100,028 and 5,035,348 to Siefert; and U.S. Pat. No. 5,131,760 to Farmer.
The inventors are unaware of any prior art which describes the use of a cooling fluid (gas or liquid) to cool a portion of the sealing die during the formation of the frangible seal. U.S. Pat. No. 5,502,952 to Wildmoser describes air cooling when the machine is stopped, but not for forming a frangible seal. U.S. Pat. No. 2,948,999 to Schlayer et al uses air to cool a bead formed as part of a hard seal. U.S. Pat. No. 5,441,345 to Garvey et al shows cooling for a timing operation.
The prior art has described a number of different pouch forming and filling apparatus. Illustrative are: U.S. Pat. No. 3,344,576 to Cloud et al; U.S. Pat. No. 3,478,492 to Cloud et al; U.S. Pat. No. 3,563,001 to Cloud et al; U.S. Pat. No. 3,597,898 to Cloud; U.S. Pat. No. 3,821,873 to Benner et al; U.S. Pat. No. 3,908,979 to Cloud et al; U.S. Pat. No. 4,316,566 to Arleth et al; U.S. Pat. No. 5,094,657 to Dworak et al. There is no discussion of frangible seals in these patents.
OBJECTS
It is therefore an object of the present invention to provide a method and apparatus for forming a pressure frangible (rupturable) seal and a hard seal and a hard seal particularly between two sheets of a thermoplastic film in a pouch such that there is a significant differential between the seal strength of various hard and frangible portions of the seal. In particular, it is an object of the present invention to provide an apparatus and method whereby portions of the sealing areas of the pouch are made frangible so as to be pulled apart using novel differential cooling of a die which forms the seal. Further still, it is an object of the present invention to provide an apparatus which is relatively simple to construct and use and which is economical to operate. These and other objects will become increasingly apparent by reference to the following description and the drawings.
SUMMARY OF THE INVENTION
The present invention relates to a die for differentially heat sealing a film to another sealable material which comprises:
(a) a plate having a seal forming portion around a cavity, wherein a part of the seal forming portion of the plate is inletted to provide an opening around the part of the seal forming portion; and
(b) conduit means mounted in the plate for providing a cooling fluid to the part in the opening in the plate for cooling the part of the seal forming portion in the portion of the plate which is inletted.
Also the invention relates to a die which is half of a pair of dies for differentially heat sealing opposed contacting sheets of a plastic film to form a pouch defined by a peripheral seal which comprises:
(a) a plate having a seal forming portion around a cavity for defining an inside of the pouch, wherein a part of the seal forming portion of the plate is inletted to provide an opening around the part of the seal forming portion; and
(b) conduit means mounted in the plate for providing a cooling fluid to the part in the opening in the plate for cooling the part of the seal forming portion in the portion of the plate which is inletted.
In particular, the present invention provides a die which is preferably cooled by a cooling gas, such as air, directed at the part of the sealing area of the die which is to be cooled.
In particular, the present invention relates to an apparatus for differentially heat sealing a plastic film to a sealable material which comprises:
(a) a die for heat sealing which comprises: a plate having a seal forming portion around a cavity, wherein a part of the seal forming portion of the plate is inletted to provide an opening around the part of the seal forming portion; and conduit means mounted in the plate for providing a cooling fluid to the part in the opening in the die for cooling the part of the seal forming portion which is in the portion of the plate which is inletted;
(b) a fluid supply line connected to the conduit means mounted in the die;
(c) heating means in the pair of dies for heating the dies to provide the seal;
(d) motive means for closing the die against the plastic film to form the seal; and
(e) feed means for feeding the plastic film between the dies so that the motive means for closing the die can close the die against the film to provide the seal with the sealable material.
Further, the present invention relates to an apparatus for differentially heat sealing opposed contacting sheets of a plastic film to form an individual pouch defined by a peripheral seal which comprises:
(a) a pair of dies for heat sealing opposed contacting sheets of a plastic film to form a pouch defined by a peripheral seal, one die of which comprises: a plate having a seal forming portion around a cavity defining an inside of the pouch, wherein a part of the seal forming portion of the plate is inletted to provide an opening around the part of the seal forming portion; and conduit means mounted in the plate for providing a cooling fluid to the part in the opening in the die for cooling the part of the seal forming portion which is in the portion of the plate which is inletted;
(b) a fluid supply line connected to the conduit means mounted in the die;
(c) heating means in the pair of dies for heating the dies to provide the seal;
(d) motive means for closing the dies against the plastic film to form the seal;
(e) feed means for feeding the sheets of plastic film between the dies so that the motive means for closing the dies can close the dies to provide the seal; and
(f) shear means for cutting the sheets to separate multiple of the pouches formed in the sheets into individual pouches.
The present invention also relates to a method for differentially heat sealing a plastic material to a sealable material which comprises:
(a) a die for heat sealing which comprises:
a plate having a seal forming portion around a cavity, wherein a part of the seal fo
Rees Blake M.
Rockafellow Brian L.
Mayes Curtis
McLeod Ian C.
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