Repulpable wax

Details Repulpable wax Repulpable wax

2002-05-03

2004-11-02

Brunsman, David (Department: 1755)

Coating processes

With post-treatment of coating or coating material

Heating or drying

C427S392000, C427S393400, C106S220000, C106S222000, C106S224000, C106S244000, C106S245000, C106S252000, C106S270000, C524S270000, C524S274000, C524S313000

Reexamination Certificate

active

06811824

ABSTRACT:

FIELD OF THE INVENTION
The present invention is a vegetable wax comprising triglycerides. Particularly, the present invention is used as an additive in boxboard coatings and adhesives, either by itself or as part of a composition, to render the coating or adhesive dispersible in warm alkaline water.
BACKGROUND OF THE INVENTION
Petroleum waxes, such as paraffin and microcrystalline wax, and synthetic waxes such as Fischer Tropsch (“FT”) and polyethylene, are used extensively in paper coatings to impart moisture resistance and enhanced moisture vapor barrier properties to the paper. Waxes used for this purpose tend to be low viscosity (<1,000 cps @ 284 degrees F) and have relatively low melting temperatures (<302 degrees F).
Large oil companies such as Shell Oil, ExxonMobil and other oil refiners supply petroleum waxes used in these applications. Most of this wax is derived in the process of refining lube oil where the wax is separated from the lube oil stock and refined into various fractions of wax including paraffins, and microcrystalline waxes. Formulators such as Astor Wax, IGI and Moore & Munger also supply wax for these applications that is either resold as is from the oil companies, and/or formulated and repackaged to meet the specific needs of customers. The two largest suppliers of FT waxes are Sasol from South Africa and Shell Oil from Malaysia. The waxes are sometimes formulated with other ingredients to modify their properties for specific applications. Such modifiers include resins to improve strength and toughness or improve flexibility or gloss.
These waxes are also used extensively in adhesives, whose formulations usually incorporate a resin (such as ethylene vinyl acetate “EVA”, or polyethylene) and a tackifier (such as a rosin ester, or tall oil fatty acid derivatives) to provide a coating that can bond or seal paper articles. Waxes are used in adhesive coatings to provide additional functionality to the adhesive coating, such as set speed and thermal stability.
A common characteristic of waxes used in coating paper and formulating adhesives is that they have a relatively low viscosity to enable flow of the coating or adhesive and its penetration of the cellulosic fiber. Typical viscosity ranges of waxes used in these applications are from about 10 SUS (Seybolt method) at 210 F to about 300 SUS at 300 F. In general, the lower the viscosity, the better the penetration into the cellulosic substrate. Better penetration is generally desirable for good adhesion.
Waxes used in coating paper and formulating adhesives can be used alone, but more commonly are formulated with other materials to modify and enhance their properties. Such materials used as additives might include antioxidants (such as butylated hydroxy toluene “BHT”, and other free radical scavenger materials), coupling agents (maleic modified polymers), gloss enhancing agents, and additives for rendering the coating more flexible (ethylene or ethylene vinyl acetate copolymers) are among some of the more commonly used modifiers for wax coatings.
Many different types of cellulosic materials are coated with petroleum and synthetic waxes to impart moisture resistance and adhesive properties. Wax coating techniques are well understood to those skilled in the art. Wax coating can involve immersion of the cellulosic material in a molten bath of the wax. It can also involve cascade and curtain coating where a thin layer of molten wax is allowed to flow onto the cellulosic material. See, for example, Sandvick et al. (U.S. Pat. No. 5,491,190, incorporated by reference herein). Other techniques are also used depending on the desired placement of the wax on the cellulosic material.
Coating and adhesive formulations containing petroleum and/or synthetic waxes present an inherent problem when paper products containing these compounds are recycled to recover the fiber components for reuse. Recycling paper involves mixing the paper to be recycled with warm water, usually with a pH in the alkaline range (>pH7). When wax is present in the recycled paper, the wax does not solubilize but forms what is known in the trade as ‘stickies’. The “stickies” is material that causes paper processing and forming machinery to become dirty and have gum like deposits, which cause maintenance and other problems for paper manufacturers. In addition, the ‘stickies’ deposit on the recycled paper, tending to form unsightly spots and thus causing the recycled paper to have a lower commercial value, and in some cases, not to be useable at all (See, for example, Watanabe et al., U.S. Pat. No. 6,117,563).
Various techniques have been used in attempts to overcome the problem of removing petroleum and synthetic waxes in the process of recycling paper. Various additives to the wax have been tried (U.S. Pat. Nos. 6,273,993, 6,255,375, 6,113,738, 5,700,516, 5,635,279, 5,539,035, 5,541,246, 6,007,910, 5,587,202, 5,744,538, 5,626,945, 5,491,190, 5,599,596). These patents are incorporated here by reference.
For example, Michelman (U.S. Pat. No. 6,255,375 B1) discloses incorporation of at least one chemical compound which is either itself capable of acting as a latent dispersant for the coating, or capable of being chemically modified so as to act as a dispersant, thus rendering the hot melt coating more readily dispersible from the coated product.
Chiu (U.S. Pat. No. 6,113,729) discloses using hydrogen peroxide with various waxes to produce laminated wood products with a light color.
Ma et al. (U.S. Pat. No. 5,635,279) discloses inclusion of a polystyrene-butadiene polymer, in combination with a paraffin or polyethylene wax emulsion, for treating paper products.
Miller et al. (U.S. Pat. No. 5,744,538) disclose a low molecular weight, branched copolyester for use in an adhesive.
Sandvick et al. (U.S. Pat. Nos. 5,491,190, 5,599,696 and 5,700,516) disclose compositions comprising ethylenically unsaturated monocarboxylic acids in combination with either a fatty acid or paraffin wax to render paper products water resistant and repulpable.
Severtsen et al. (U.S. Pat. No. 6,113,738) disclose the addition of plasticizers, dispersants or wetting agents to the recycling mixture to facilitate wax breakdown and dispersion.
Vemula (U.S. Pat. No. 5,891,303) discloses a process using a heated solvent, n-hexane, to remove wax from waste paper, and indicates that both the wax and the paper can be recovered from the recycling process.
In addition there have been mechanical techniques used in an attempt to recycle wax containing paper products through processes such as floating the wax from the slurried paper mix. Heise et al. (U.S. Pat. No. 6,228,212 B1) disclose a method to remove wax from paper during recycling, using a combination of floatation and filtration. They note that the majority of waxes used in the paper industry are petroleum-based waxes. Because none of these techniques are commercially viable, it is still customary in many locations to isolate wax coated paper products and send them to a landfill or to an incinerator in lieu of recycling them (Heise et al., U.S. Pat. No. 6,228,212 B1).
The prior art thus illustrates the use of petroleum derived waxes, synthetic waxes, and certain vegetable waxes for rendering cellulosic articles water resistant, or for their inclusion in adhesives for attachment of cellulosic articles. However, the problem of recycling articles containing these compositions remains. Therefore, there is a need for employing a composition, which has the barrier and physical properties of petroleum derived or synthetic waxes while allowing for the economical recycling of fibrous cellulosic materials, which have incorporated these waxes as coatings and/or adhesives. Due the large volume of waxes consumed in these applications it is also preferred that the compositions be readily available. From both a supply and a natural resource viewpoint, it is preferred that the compositions be obtained from a source that preferably is renewable, such as from plant extracts.
It is also known through experience with synthetic low molecular w

Affiliated with

Also associated with

Rating

Repulpable wax does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Repulpable wax, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Repulpable wax will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3358076