Stock material or miscellaneous articles – Hollow or container type article – Nonself-supporting tubular film or bag
Reexamination Certificate
1999-04-27
2003-01-21
Tarazano, D. Lawrence (Department: 1773)
Stock material or miscellaneous articles
Hollow or container type article
Nonself-supporting tubular film or bag
C428S036600, C428S078000, C428S192000, C428S194000, C428S520000, C428S522000, C428S532000, C053S051000, C053S053000, C053S459000
Reexamination Certificate
active
06509072
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a multi-layer, water-soluble or dispersible film having a periodic barrier coating suitable for forming into a container, a method of making such film, a method of packaging a substance in such film, and a container comprising such film. More particularly, the present invention relates to a multi-layer, water-soluble or dispersible film having a continuous water-soluble layer, a barrier coating applied intermittently to discrete areas of the continuous layer, leaving a plurality of uncoated intervals on the continuous layer where the film can be formed into a bag for holding substances that adversely affect the continuous layer of the bag and where the barrier coating is less susceptible or reactive with the substance to be packaged than the continuous layer. The invention also relates, in particular, to a method of making the water-soluble film comprising applying a barrier coating to discrete areas of a continuous water-soluble layer so as to leave a plurality of uncoated intervals on the continuous layer. The invention also relates, in particular, to a method of packaging a substance, where the method comprises forming the aforedescribed multi-layer, water-soluble film into a container, filling the container, and sealing the container, such that the barrier coating forms the inner surface of the container where it prevents the packaged substance from contacting the outer continuous layer, which is more reactive with the packaged substance.
BACKGROUND OF THE INVENTION
Various types of materials, including non-toxic and potentially hazardous or toxic compounds can be sold in a concentrated form to be dispersed in water or other organic material prior to use. These compounds include, for example, agrichemicals such as herbicides, pesticides, fungicides, insecticides, and fertilizers. Containers are needed for conveniently and safely distributing, selling, and utilizing such materials.
One such container that offers numerous commercial advantages for the packaging of potentially harmful materials is a water-soluble or dispersible container—e.g., a bag, pouch, package, or related enclosure formed from film. First, via its seal, a water-soluble bag protects the user from accidentally ingesting or otherwise contacting the contents of the package. Second, the precisely measured quantities of the chemical in the bag prevent waste through over charging and minimize accidents. Finally, as the bag dissolves completely in water and the solubilized bag material is biodegradable, there is no potentially hazardous or environmentally destructive packaging material to be discarded.
A variety of cold water-soluble films can be used for the purpose of packaging potentially harmful compounds. A polymeric barrier coating can be affixed to the water-soluble film to minimize or prevent the active material being packaged from chemically or physically interacting with the film surface. When applied onto the water-soluble film, the barrier coating minimizes changes in the properties of the film, protects the activity of the packaged material over the storage life of the package, and provides satisfactory solubility of the film.
One potential problem, however, that could be encountered with multi-layer, water-soluble films is that the presence of continuous coating in the seal-forming area impairs the ability of the film to be heat-sealed. As a result, heat seals formed between two continuous layers of barrier coating are generally weak, peelable, or nonexistent.
Other attempts to address this problem have included the development of a three-layer packaging film comprising a first layer of cold water-soluble film, a second layer of barrier material, and a third layer of cold water-soluble film for forming the heat seal. Use of this film for packaging, however, may present the following concerns: (1) whether the heat-seal layer would insufficiently disperse under various conditions; (2) whether the bond between the third (heat-sealing) layer and the second (barrier) layer would be maintained after sealing; (3) whether a three-layer film is economically feasible; and (4) whether a three-layer film will dissolve in a timely manner.
Consequently, there exists a need for a water-soluble or water-dispersible, multi-layer film that can be used to produce a well-sealed package for materials that adversely affect one or more layers of the film, particularly the layer that forms the outer portion of the package. There also exists a need for a method for making such film and a method of packaging substances in such film.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a multi-layer, cold water-soluble or dispersible film is provided. The multi-layer film comprises: (1) a continuous, cold water-soluble or dispersible material suitable for forming an outer layer of a bag for containing a material therein and having sufficient thickness and strength for use as the bag for containing the material, which may be a solid or a liquid; and (2) a discontinuous barrier coating, suitable for forming an inner layer of a bag, affixed to discrete areas of the continuous layer with areas of the continuous layer being uncoated by the barrier layer. The barrier coating is termed “discontinuous” because it does not cover at least those areas of the continuous layer that will be formed into a seal or seals when formed into a package or bag. However, the barrier coating is preferably a continuous coating where it is intended to be present since generally its function is to protect the continuous layer from contact with the material contained within the bag or container when the continuous layer forms the outer layer (or at least not the inner layer) of the bag. The discontinuous barrier coating is less reactive than the continuous coating with respect to the substance or material to be packaged, whether a liquid or a solid. Generally, the barrier layer or coating also lacks sufficient structural integrity and strength to contain the contents of the bag once the outer layer is dissolved or dispersed. Thus, the barrier layer is not a structural layer.
In one embodiment, the discontinuity of the barrier coating defines a plurality of uncoated areas, including areas occurring at repeating distances on the continuous layer, which define the seal-forming areas when the film is constructed into a bag. The uncoated area should correspond at least to the areas which will form the bag seal, which may depend on the particular sealing machine that may be utilized. Typically, the outer layer of the bag should have sufficient strength to contain liquids of a specific gravity of about one or more and in a bag volume that contains up to about eight fluid ounces or more, for example, such as up to about two liters.
For example, in accordance with one aspect of the present invention, the uncoated areas may occur along at least one longitudinal end of the continuous layer and at repeating distances spaced apart longitudinally at transverse locations across the continuous layer and are especially useful for a vertical form, fill and seal packaging equipment.
Preferably, the multi-layer, water-soluble film has indicia means for identifying the locations of uncoated areas so as to form the seal-forming areas when the film is used to construct the bag.
The invention is particularly useful for containing materials, whether solid or liquid that attack or degrade or adversely affect the continuous layer.
As used herein, the term “chemical” includes all types of chemicals, including potentially hazardous chemical materials, including organic chemicals such as, but not limited to, agrichemicals, detergents, dyes, pigments, water treatment chemicals and additives, including for concrete, paint and coatings, for example. The term “agrichemicals” includes, for example, agronomically useful chemicals from the following classes: plant nutrients, plant growth regulators, plant protection agents such as pesticides (e.g., herbicides, insecticides, nematocides, fungicides), activity promo
Bening P. Scott
Jouffreau Christian
Verrall Andrew P.
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