Tobacco – Cigar or cigarette making – Tip or mouthpiece applying or forming
Reexamination Certificate
1999-04-26
2003-05-27
Tarazano, D. Lawrence (Department: 1773)
Tobacco
Cigar or cigarette making
Tip or mouthpiece applying or forming
C131S094000, C131S365000, C131S366000, C156S327000, C428S036900, C428S522000
Reexamination Certificate
active
06568399
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to the use of low application temperature hot melt adhesive for cigarette filters. Specifically, the hot melt adhesives of the present invention are used to bond filter wrap seam and to anchor the filter element in place on the rod.
A standard filter tipped cigarette is produced by three different operations: (1) filter or plug manufacture, (2) rod manufacture, and (3) tipping.
The cigarette rod consists of a stream of tobacco wrapped in a paper tube, the paper tube being glued along one longitudinal edge or surface with a suitable adhesive. This operation takes place at speeds varying from 2,000 to 16,000 cigarettes per minute. The weight of the cigarette rod, diameter, and length are all closely monitored for both cost control and tax purposes.
The filter making operation is similar in many respects to the rod manufacture, but the materials and manufacturing equipment used are different. Tobacco smoke filters are most commonly manufactured from a crimped textile tow of cellulose acetate fibers. The tow is then warmed and rolled to produce a material about 9″ wide, and containing an even distribution of fibers. The tow is “bloomed” in a known manner to separate the fibers, and a high boiling point solvent, commonly called a “plasticizer”, i.e., triacetin, is applied by spraying, wicking, or other suitable means. The treated tow is then pulled into a cylindrical form and wrapped with paper. During an interval of time, which can be accelerated by heating, the plasticizer first partially dissolves the surface of the fibers causing them to become sticky and to bond together at points of contact with each other. The plasticizer then migrates into the fiber leaving the surface dry, but the fibers still remain bonded.
The bloomed tow is then formed into a tube, and wrapped in paper or plugwrap, the paper being glued along one longitudinal edge. Before the paper meets the tow material, adhesive is applied to the center and the edge forming the anchor and the seam. During this process, heater bars are used to extend the open time of the adhesive as it meets the tow. The formed filter rod is then passed under chiller plates to set the adhesive. This is necessary as the filter is immediately cut into smaller pieces.
In some applications, such as multi-component or charcoal type filters, a hot melt adhesive is pre-applied onto filter paper and then heat sealed by the filter making machine.
In conventional cigarette filter manufacture, a hot melt adhesive, applied at 350° F. (177° C.), is used for the seam and a second, aqueous adhesive, is used for the anchor. An aqueous adhesive is chosen with triacetin resistance. Because of the nature of the tow, there is a high degree of radial stress upon the glued bond, so any adhesive used must be able to stick almost instantly and hold during storage and use. This has led to the use of hot melt type adhesives, which by formulation are fast setting, and allow very high machine speeds to be used.
Currently polyethylene and ethylene vinyl acetate based hot melt adhesives are used for this filter or plugwrap application. These are preferred since they are relatively non-polar and resist the deteriorative effects of triacetin, the most commonly used plasticizer, which often migrates acting as a solvent for the adhesive causing bond deterioration.
Most commercially available adhesives used in cigarette manufacture are either hot melts which require temperatures of 350° F. (177° C.) or are aqueous to provide triacetin resistance.
However there are problems associated with use of conventional hot melt adhesives, which are applied at elevated temperatures, usually 350° F. These high temperatures increase the operator's risks with respect both to burns and to inhalation of residual volatiles. In addition, the high temperatures require more energy, placing greater demands on the manufacturing facility. The higher temperatures can also cause premature wear and tear on the application equipment i.e., nozzles, hoses and reservoir tanks.
The present invention uses low application temperature hot melt adhesives, which can be applied at temperatures in the range 200 to 300° F. (93° C. to 149° C.). The advantages of using such lower temperatures include reduced number of heater elements required in the adhesive reservoir, reduced volatile emissions, and reduced risk of injury and reduced wear and tear on the application equipment. The use of low temperature hot melt adhesives may also eliminate the need for use of both an aqueous and hot melt adhesive, since some of the hot melt adhesives of the present invention exhibit excellent triacetin resistance. Further, the lower temperatures reduce temperatures in the reactivation section of the machinery and eliminate the need for cooling plates. In addition, the hot melt adhesives of the present invention have a fast set speed, low bleed through, improved cuttability and are comparable or better than 350° F. hot melt adhesives in terms of triacetin resistance.
SUMMARY OF THE INVENTION
It has been found in accordance with the present invention, that low application temperature ethylene copolymer based hot melt adhesives provide unexpected advantages in cigarette filter manufacture.
DESCRIPTION OF THE INVENTION
The present invention is directed to the use of hot melt adhesive compositions, which can be applied at temperatures between 200 to 300° F. (93° C. to 149° C.), in the manufacture of cigarette filters. In particular, the present invention is directed to a process of making cigarette filters, and to cigarette filters, wherein a low application temperature ethylene copolymer based hot melt adhesive is applied to at least one longitudinal edge or surface of porous and/or non-porous plug wrap paper. The adhesives of the present invention are also applicable to multi-component filters or other filters which are prepared by preapplying the hot melt to filter paper, then heating the coated paper on the filter making machine. As used herein, low application temperatures are temperature between 200° F. and 300° F. (93° C. and 149° C.), preferably, 240° F. to 275° F. (115° C. to 135° C.).
The present invention is directed to the process, and to cigarette filters, which comprise any hot melt adhesive which can be applied at temperatures between 200 and 300° F. (93° C. and 149° C.). Adhesives suitable for use herein include the hot melt adhesives prepared from ethylene, ethylene n-butyl acrylate copolymers, ethylene/a-olefin copolymers, and ethylene vinyl acetate copolymers.
I. Ethylene n-butyl acrylate based hot melt adhesives.
The ethylene n-butyl acrylate copolymers (EnBA) useful herein are those containing at least about 10 to 40 weight percent n-butyl acrylate and having a melt index of at least about 40 dg/min, preferably at least about 400 dg/min. The preferred copolymers are available from Exxon under the designation XW 23-AH and comprise approximately 33 to 37 weight percent n-butyl acrylate by weight and have a melt index of about 400 dg/min. The amount of the copolymer present in the adhesive varies from about 5 to 45 weight percent by weight, preferably about 10 to 40 weight percent by weight.
Mixtures of EnBA copolymers may also be used as long as the resultant mixture falls within the described ranges of percent n-butyl acrylate by weight, and melt index. It is therefore possible to mix two ethylene n-butyl acrylate copolymers having different melt indices and different percentages of n-butyl acrylate. In a preferred embodiment, the EnBA copolymers described above may be used alone or as a blend with an EnBA copolymer having a melt index of 40 dg/min.
In addition to the components described above, the adhesive compositions of the present invention may optionally comprise a second EnBA copolymer, specifically one containing about 30 to 35, preferably 33 weight percent by weight of n-butyl acrylate and having a melt index of about 6 to 40 dg/min. The preferred copolymers are available from Elf Autochem under the designation LOTRYL 35BA40 and
Cole Ingrid
Morrison Brian D.
Wieczorek, Jr. Joseph
Foulke Cynthia L.
National Starch and Chemical Investment Holding Corporation
Tarazano D. Lawrence
LandOfFree
Low application temperature hot melt adhesive for cigarette... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Low application temperature hot melt adhesive for cigarette..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Low application temperature hot melt adhesive for cigarette... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3014921