Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1998-03-30
2001-02-27
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S348000, C526S352000, C383S120000, C493S189000, C493S243000, C493S934000, C525S240000
Reexamination Certificate
active
06194533
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to liner films for containers used for bulk transportation, and more particularly to films for producing liners installed bulk containers to transport or store granular or particulate chemicals or plastics, foods such as sugar and grains, etc.
The present invention also relates to liners for bulk container (BCL).
DESCRIPTION OF THE RELATED ART
Liner films for bulk containers are generally prepared by molding synthetic resins into tubular shape by an inflation molding method. Because the bulk containers are usually in the shape of rectangular parallelepiped, the liner films are sealed at both ends to the sizes of the containers to prepare bags, whereby container liners are produced. The liner is gusseted and folded to stock. Through the gusseting, the tubular films are provided with fold. The fold is called “gusset centerline portion”. In the gusseted films, the portion other than the gusset centerline portion is generally called “original film portion”.
As the liner film for a large-sized bulk container having a length of 20 feet (about 6.1 m) or 40 feet (about 12.2 m), for example, a single-layer or multi-layer film with a thickness of about 140 to 200 &mgr;m, which is formed from an ethylene/vinyl acetate copolymer having a vinyl acetate content of 1 to 5%, has been conventionally employed.
When the bulk container liners are filled with contents such as granular or particulate chemicals or foods (e.g., sugar, grains), overlapped portion of the both ends of the film of the liner are generally heat-sealed to seal. As for the conventional liner films for bulk containers, however, the adhesive strength of the heat-sealed portions is not always sufficient, and there remains insecurity of practical use. Therefore, the heat-sealed portions are reinforced by attaching adhesive tapes thereto. The conventional liner films are thick and have a thickness of about 140 &mgr;m, and the liners made of the films become heavy, so that it is not easy to fit the liners into the bulk containers. Further, since the liner films have a melting point of about 90° C., it is impossible to fill the liners made of the films with the high temperature contents at the temperature of as they are. For the filling, the contents must be cooled to, for example, not higher than 50° C.
As described above, the conventional liner films for bulk containers and the container liners have various problems in the practical use, and improvements of the liner films and the container liners have been eagerly desired.
The present invention is intended to solve such problems associated with the liners as described above, and it is an object of the invention to provide a liner film for bulk container, which can reduce the weight of liner by decreasing the film thickness, which shows such a high heat-sealing strength that the heat-sealed portion is not broken even if no adhesive tape is attached thereto, and which can produce a liner having heat resistance as capable of being filled with a content kept at a higher temperature than the conventional temperature.
It is another object of the invention to provide a bulk container liner, which is lightweight, has a high heat-sealing strength and is capable of being subjected to high-temperature filling.
SUMMARY OF THE INVENTION
The liner film for bulk container according to the invention is a film comprising a polyethylene (A) prepared by the use of a single site olefin polymerization catalyst, said polyethylene (A) having:
(i) a density of 0.920 to 0.940 g/cm
3
,
(ii) a melt flow rate (ASTM D-1238, 190° C., load of 2.16 kg) of 0.1 to 3.0 g/10 min, and
(iii) a melting point (Tm) of 115 to 135° C.
The bulk container liner according to the invention is obtained by shaping an inflation film, which comprises the above-mentioned polyethylene (A) prepared by the use of a single site olefin polymerization catalyst, into a bag.
REFERENCES:
patent: 5459217 (1995-10-01), Todo et al.
patent: 5511681 (1996-04-01), Podd
patent: 5580914 (1996-12-01), Falla et al.
patent: 5618254 (1997-04-01), Derby
patent: 5710224 (1998-01-01), Alt et al.
patent: 5770664 (1998-06-01), Okumura et al.
patent: 5874513 (1999-02-01), Watanabe et al.
patent: 0587365 (1993-09-01), None
patent: 587365A2 (1994-03-01), None
patent: 0764679 (1997-03-01), None
patent: 0769523 (1997-04-01), None
patent: 769523A2 (1997-04-01), None
patent: 0781789 (1997-07-01), None
patent: 781789A2 (1997-07-01), None
patent: 9414855 (1994-07-01), None
patent: 9510566 (1995-04-01), None
patent: WO95/10566 (1995-04-01), None
Hiraoka Takashi
Inoue Hiroshi
Nishimura Toshihiro
Tsuji Yoichiro
Mitsui Chemicals Inc.
Rabago R.
Wu David W.
LandOfFree
Liner film for bulk container and container liner does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Liner film for bulk container and container liner, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liner film for bulk container and container liner will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2567389