Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Patent
1997-11-25
2000-06-20
Thibodeau, Paul
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
428331, 428461, 428500, 428515, B32B 516, B32B 1508, B32B 2700, B32B 2708
Patent
active
060776021
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a heat sealable film.
Thermoplastic films suitable for packaging products are often required to exhibit a variety of properties, including heat sealability, tensile strength, transparency, machinability and barrier properties.
BACKGROUND OF THE INVENTION
In most processes for packaging products, such as potato chips, nuts, candy, biscuits, spices and similar foods, hardware such as nuts, bolts, screws and nails, the package is formed and filled by creating a heat-seal between two opposed layers of film to form a pocket and almost simultaneously sliding or dropping the product into the pocket. In these form and fill packaging techniques a continuous flat web of packaging film is fed around a form which shapes it into a tube, the tube is slipped over a hollow form and the free edges of the tube are sealed together. The tube so formed is then passed between a pair of hot sealing jaws which create a series of discrete packages by collapsing the film onto itself and forming a seal by the application of heat and pressure. The product is introduced into each package through the hollow form in the interval between the heat seals. During high operating speeds, the product is dropped into the package while the sealing jaws, which form the seal, are closed. With both vertical and horizontal form and fill sealing applications the heat seal should be strong enough to support and retain the product after the sealing jaws open to release the film. It is often desirable to release the sealing jaws soon after the seal is formed so a film which accomplishes this by exhibiting a high "hot tack" is very useful.
Additionally, in packaging applications there is a great demand for heat sealable films which can be subjected to temperatures high enough to seal the films without causing the substrate to cockle or pucker. One approach for achieving this is by coating a film substrate with a layer of heat sealable material which adheres strongly to the substrate and which can be melted at a temperature below the softening temperature of the substrate. Heat-sealable coatings with low melting temperatures are often preferred because the substrate is less likely to be damaged during heat sealing.
In the preparation of films useful for packaging purposes, the outside of the film or the side of the film which comes in direct contact with the hot sealer surfaces should have good hot slip and jaw release characteristics. Additionally, the film should have good machinability so that the wrapped product can be conveyed easily through the overwrapping machine without sticking to adjacent packages or the parts of the machine with which it comes into contact, which can cause production delays. The film should also have barrier properties. Acrylic-containing coatings which offer these properties are known. The acrylic-containing coating is applied to one side of the film substrate and another heat sealable coating, such as polyvinylidene chloride (PVDC), or another acrylic coating, is coated on the other side. Acrylic-containing coating formulations provide the film with a good coefficient of friction which contributes to good machinability characteristics. These acrylic-based coatings also provide the film with good barrier characteristics which improve flavor and aroma protection. Such coatings are described in U.S. Pat. Nos. 4,058,649 and 4,058,645. The PVDC coating or other type of acrylic coating is usually on the inside of the film and provides high seal strength, good hot tack characteristics and barrier properties. These heat sealable coatings have glass transition ("Tg") temperatures which are higher than room temperature. Such a coated film is disclosed in U.S. Pat. No. 4,403,464.
In the film packaging art, materials which can contribute to film damage by causing the film to pucker are often found either in the packaging materials themselves or in the packaged products. It has been found that oriented polypropylene films having acrylic and ethylene-acrylic acid copolymer-containing co
REFERENCES:
patent: 2795564 (1957-06-01), Conn et al.
patent: 3365410 (1968-01-01), Wesslau et al.
patent: 3753769 (1973-08-01), Steiner
patent: 3822175 (1974-07-01), Yuan
patent: 4058645 (1977-11-01), Steiner
patent: 4058649 (1977-11-01), Steiner
patent: 4265948 (1981-05-01), Hayes et al.
patent: 4299748 (1981-11-01), Hashizume et al.
patent: 4403464 (1983-09-01), Duncan
patent: 4478972 (1984-10-01), Conrady
patent: 4629657 (1986-12-01), Gulati et al.
patent: 4695503 (1987-09-01), Liu et al.
patent: 5017430 (1991-05-01), Chu et al.
patent: 5093194 (1992-03-01), Touhsaent et al.
patent: 5268209 (1993-12-01), Hunt et al.
patent: 5486426 (1996-01-01), McGee et al.
patent: 5567773 (1996-10-01), McGee et al.
patent: 5843582 (1998-12-01), McGee
Liestman David August
McGee Dennis Emmett
Ahmed Sheeba
Mobil Oil Corporation
Santini Dennis P.
Thibodeau Paul
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