Stock material or miscellaneous articles – Layer or component removable to expose adhesive
Reexamination Certificate
1998-08-31
2002-05-21
Ahmad, Nasser (Department: 1772)
Stock material or miscellaneous articles
Layer or component removable to expose adhesive
C283S081000, C428S040200, C428S041500, C428S041600, C428S041700, C428S042100, C428S202000, C428S204000, C428S346000, C428S480000, C428S500000, C428S522000, C428S913000
Reexamination Certificate
active
06391415
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates generally to label systems and, more particularly, to a heat activated label system for transferring a preprinted label and a protective coating in a single step from label stock to a substrate, such as a plastic crate or glass bottle.
(2) Description of the Prior Art
Containers, such as glass bottles, are currently labeled in several different ways. The predominant method is printed paper labels glued to the container at the time of filling and sealing. Such labels offer almost unlimited art potential and are commonly used on food and both returnable and non-returnable beverage containers. This is the lowest cost technique, but offers little resistance to label damage. Also, the glue systems used are a constant source of problems in high speed bottle filling operations.
A second, more recently developed, container labeling technique is of applying a thin styrofoam label to cover the container from shoulder to heel, with the decorative and/or informational material being printed on the more dense outer skin of the styrofoam label. This is widely used on lighter-weight, one-way bottles common in the beverage industry. It offers some impact resistance and a large surface area for printing product information and instructions, as well as company logos. Unfortunately, it covers a majority of the container and prevents visual inspection of the contents by the consumer. In addition, it is more costly than the paper label, has little durability and becomes easily soiled. Also, because the printing surface is relatively rough, high definition printing is not possible. The styrofoam label also becomes a contaminate at the glass recycling center as well as at the glass plant when remelting the container.
A third container labeling technique is printing ceramic ink directly on the container surface using a screen printing technology. While the label appearance is generally good, the technique is typically limited to two or three colors due to cost considerations. A recent development is the preprinting of a ceramic ink decal which is then transferred to the glass container surface. This permits high definition printing and offers greater opportunities for color and art variety. Fired ceramic inks are extremely durable and will survive the alkali washing processes required of a returnable container. However, both the direct printing ceramic ink and ceramic ink decal techniques require subsequent high cost, high temperature firing to fuse the ink to the glass substrate. In addition, while the preprinted ceramic ink label reduces the technical problems somewhat, both techniques require extreme attention to detail and a high level of maintenance and are run off-line at slower speeds, with high labor costs. Due to these higher costs, ceramic inks are the least commonly used labeling technique.
Another, more recent, technique is disclosed in U.S. Pat. No. 5,366,251, issued to Brandt. Brandt teaches a label comprising an opaque or clear film substrate, which has preferably been coated on both sides with acrylic to serve as a compatible interface bond with the other materials used in the process and also to provide a high gloss surface. Graphics are printed on the acrylic layer, preferably using a solvent-based acrylic ink. The graphics can be reverse printed when the film is clear, which gives the appearance of the “fired on” label. When the film is opaque, the graphics are front surface printed using the opaque film as a background or part of the graphics. The label is then provided on its container side with a two-layer, heat-activatable adhesive, activatable on contact with the heated container. A clear coat may be subsequently applied to protect the label during use, however, this requires a separate step.
U.S. Pat. Nos. 5,650,028 and 5,458,714, also issued to Brandt, disclose other embodiments of this technique and machinery to carry out the application of the label to the container. All three of these patents are hereby incorporated by reference in their entirety.
These techniques have also been considered for applying replaceable labels to polyethylene beer crates. However, the label must be sufficiently durable to pass scuff and water soak resistance tests while, at the same time, be removable by a weak caustic solution to enable a new label to be added. Because the label must be easily removed, the label can not use a conventional protective, clear coat to provide the necessary protection to the label.
Thus, there remains a need for a new and improved heat activated label system for transferring a preprinted label and a protective, clear coat in a single step from the label stock to a substrate, such as a plastic crate or glass bottle while, at the same time, selectively providing removability for crates or permanence for bottles and with improved scuff and water soak resistance.
SUMMARY OF THE INVENTION
The present invention is directed to a label system having an unique label stock. The label stock includes a water reducible ink system for forming a water resistant ink label. In the preferred embodiment, the ink system includes a color coat layer comprised of a first carboxylic acid functional resin selected from the group consisting of urethane, epoxy and acrylic carboxylic acid functional resins; and a protective, clear coat layer including a second carboxylic acid functional resin. For bottle applications, hydrophobic fumed silica is added to improve scuff and water resistance. A label carrier, formed from non-absorbent paper or plastic, receives the water resistant ink label.
The protective, clear coat layer is located between the surface of the label carrier and the color coat layer but becomes the outer layer of the label when the label is transferred to a substrate, such as a bottle or plastic carton. In the preferred embodiment, a silicon release finish is added between the protective, clear coat layer and the label carrier to aid in the release of the label from the label carrier surface. Also, a conventional, clear release coating may be added between the release finish and the label to provide additional protection for the label after transfer. As used herein, a release finish substantially stays with the label carrier and a release coating transfers with the label to the substrate.
In the preferred embodiment, a heat-activated adhesive is applied to the surface of the color coat layer for transferring the label from the label carrier to the substrate. The heat-activated adhesive has an activation temperature less than the distortion temperature of the label carrier so as to not distort the image during transfer. Preferably, the activation temperature of the heat-activated adhesive is less than about 350° F. and, most preferably is about 150° F.
In the preferred embodiment, the heat-activated adhesive is an acrylic emulsion system which includes an adhesive agent, an anti-tacking agent, a viscosity stabilizer, and the balance water and further may include a plasticizer and a wetting agent to reduce “spider webbing” in some applications.
Also, in the preferred embodiment, the label stock further includes an intermediate, clear, primer coat between the adhesive and the water resistant ink label which provides improved removal of the label from the label carrier to the substrate. In addition, it has been discovered that the use of the intermediate, clear, primer coat also improves removability for crate applications over just ink alone. Apparently, the inks do not become resoluble as quickly as the clear, primer coat does.
Finally, a heat-activated, cross-linking agent may be added in at least one of the color coat and the protective, clear coat to improve water soak resistance for bottles or other applications where the label is not removable. The heat-activated, cross-linking agent preferably is selected from the group consisting of urea and melamine formaldehyde. The heat-activated, cross-linking agent has an activation temperature of greater than the activation temperature of the adhesiv
McCurry Charles Douglas
Redman Edward George
,MacCord Mason PLLC
Ahmad Nasser
Environmental Inks and Coatings Corporation
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