Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Reexamination Certificate
2000-01-14
2002-03-05
Zirker, Daniel (Department: 2854)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
C428S343000, C400S697000
Reexamination Certificate
active
06352770
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to correction tapes having dye migration blocking properties. More specifically, the present invention includes a correction medium layer comprising an opacifying pigment, binding agent, and bleed inhibitor and a transfer layer on a support member to form a correction tape that can be used to mask erroneous markings with improved resistance to ink bleed through.
Correction tape is a commonly used method to correct erroneous markings. The tape typically comprises two parts, a polymeric tape as a base, and a corrective composition that may be multi-layered. The corrective composition may contain pigments, fillers, such as clay, a polymeric binder and dispersant to anchor the pigments to the paper, as well as, a dispersant medium or solvent to maintain fluid viscosity.
A layer of correction medium is deposited onto a tape which is later transferred onto paper once pressure is applied on the tape. The result is a layer of correction medium layer over the erroneous marking.
Correction tapes allow ink dyes to bleed through, or into, the applied correction material. Typically, latex binder polymer emulsions are acrylic copolymers and/or ethylene vinyl acetate copolymers, which minimize the diffusion of underlying ink markings into or through the correction layer which is applied over the ink marks. Such dissolution of the marking causes so-called bleeding or smudging of the marking into the correction fluid, which causes a discoloration of the film and corrected spot. Bleeding means that the white correction layer assumes a bluish or reddish tint or other type of blemish color due to the ink dye penetrating the surface being corrected. This bleeding effect is a major shortcoming of the presently used correction tapes.
European Patent No. 0 647 689 A1 discloses a correction fluid capable of preventing bleedthrough which uses an aminosilane in combination with an acid-functional vinyl polymer to create a correction fluid with effectively fixes the aqueous based ink dyes and prevent them from migrating into white type-out correction fluids.
German Patent No. WO 92/07039 discloses a correction fluid capable of preventing bleeding which contains water or a mixture of water and volatile organic water-miscible solvents as suspension medium, and a cationically active film-forming binder to fix the dyes in the area to be corrected.
PCT patent application WO 94/29393 discloses an aqueous correction fluid with a cationic polymer suitable for application to marks made with water-fast inks. The aqueous correction fluid includes water, an opacifying pigment dispersed in the water, a cationic polymer that inhibits bleeding, and a water insoluble film-forming polymer. The cationic polymer inhibits bleeding of the ink through the corrective coating by hindering the movement of anionic dyes from the ink mark through the corrective coating.
PCT patent application WO 96/01878 discloses a correction fluid with a cationic stain blocking agent which primarily serves as a binder, enabling the correction fluid to effectively bind pigments to paper and form a continuous dry film at room temperature. The correction fluid contains an opacifying agent, which includes a blend of titanium dioxide, and a clay which act in combination with the stain blocking agent to improve the hiding power of the correction fluid.
PCT patent application WO 98/30641 discloses a correction fluid which includes an opacifying agent, a cationic film-forming polymer, a nonionic film-forming agent, and a dispersing agent. The cationic film-forming polymer serves as a binder, enabling the correction fluid to effectively bind to a paper substrate and to form a continuous film on the paper substrate upon drying at room temperature. The opacifying agent comprises of two grades of titanium dioxide. A first grade of titanium dioxide selected to provide hiding power, and a second grade of titanium dioxide selected to provide suspension redispersability, a film-forming layer, and water. Thus, the combination of two types of titanium dioxide allow to maximize the masking ability of the liquid while minimizing the solubility of the masking agent.
Despite these efforts to formulate correction fluids which prevent bleed through, correction tapes having better bleed through resistance are still desired by the industry. As new water and solvent based ink compositions are developed, new compositions and formulations of correction tapes are necessary to maintain good bleed through resistance.
SUMMARY OF THE INVENTION
The present invention is directed to a correction tape comprising a support member, a correction medium layer, and a transfer layer. The support member is typically paper, a thermoplastic film, or metallic foil. The correction medium layer includes an opacifying pigment in an amount sufficient to mask printed or ink matter on a substrate; a bleed inhibitor in an amount sufficient to prevent or reduce ink transmission through the correction medium layer; and a binding polymer for retaining the opacifying pigment and bleed inhibitor in the correction medium layer to facilitate deposition of the layer on the support member and transfer of the layer onto printed or ink matter on a substrate.
Advantageously, the bleed inhibitor comprises at least one of a polyvinyl amine, a phospholipid, a tallow amine, or a mixture thereof. Preferably, the bleed inhibitor includes the combination of the polyvinyl amine and the phospholipid, optionally with the tallow amine, if desired. The bleed inhibitor is typically present in the correction medium layer in an amount between about 0.01% to about 10% by weight.
Generally, the opacifying pigment comprises TiO
2
. The correction medium layer further comprises one or more of a biocide, filler, defoamer, wax emulsion, or surfactant. If desired, at least one toner or coloring agent can be included to impart a color to the correction medium layer.
The transfer layer facilitates the deposition of the correction medium layer onto a surface containing erroneous markings. The transfer layer comprises at least one pressure sensitive adhesive which is applied over the correction medium layer.
DETAILED DESCRIPTION OF THE INVENTION
The present invention resolves the problem of bleed-through of dyes through correction compositions by introducing a chemical additive in the correction medium layer which serves a dual function. The first function is to prevent dye migration, and the second function to prevent smearing of inks written over the correction medium layer.
The present invention provides several benefits. one embodiment of the invention provides a two layered correction tape that increases bleed through resistance. Another advantage of the two-layered tape is that the present invention can be used on conventional machinery, thus not requiring additional equipment for the manufacture of the two-layered tape. Yet another advantage of the present invention is that the bleed inhibitor provides improved ink bleed resistance in the correction tape. Additionally the write-over ability of the correction tapes is improved over the conventional prior art tapes without sacrificing other properties of the correction medium layer such as opacity, film integrity, water resistance, and color.
The invention is directed to two layered correction tapes with a transfer layer and a correction medium layer containing at least one bleed inhibitor additive. The bleed inhibitor has a dual effect; it decreases ink bleed and allows for overwriting without smearing.
The invention features correction medium layers that have good bleed resistance when used to cover marks made with inks. As used herein, the term “inks” means an ink which is either water based or solvent based and which is deposited from writing instruments or printing devices.
The invention preferably comprises a correction tape which includes a support member coated with the correction medium layer which is then coated with a transfer layer. The correction medium layer comprises opacifying pigment, polymer binder, and
Bradley Creg G.
Nienaber Renate
Sastry Shyamy R.
BIC Corporation
Pennie & Edmonds LLP
Zirker Daniel
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