Coating processes – With post-treatment of coating or coating material – Heating or drying
Reexamination Certificate
1998-12-08
2001-04-17
Cameron, Erma (Department: 1762)
Coating processes
With post-treatment of coating or coating material
Heating or drying
C427S388100, C427S389700, C427S393000, C427S393500, C427S393600, C427S397000, C530S500000
Reexamination Certificate
active
06217942
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to methods for preparing coatings through enzymatic reactions with components of wood. More particularly, the present invention relates to the enzymatic polymerization of lignin based compositions with phenol oxidizing enzymes.
It has been estimated that nearly 20% of the chemical pulp and dissolving pulp provided worldwide is produced by the sulfite process. Moreover, the significance of this process has grown with the large-scale employment of modifiable magnesium bisulfite pulping. Nonetheless, although there exist a number of uses for lignin sulfonates produced by these processes, it has been difficult to find commercially feasible and desirable means of disposing of this large waste stream for useful purposes. As described in U.S. Pat. No. 4,432,921, the use of spent sulfite liquor as an adhesive for paper, wood and other lignocellulosic materials is well known in the art, and is facilitated by enzymatic activation of the lignin using a phenol oxidizing enzyme. U.S. Pat. No. 5,505,772 describes a method of preparing particle boards by conglutinating wood fragments having middle lamella lignin with a phenol oxidizing enzyme, the process having the advantage that it is necessary to add no additional binder. Further, it has been shown that laccase and other oxidoreductase enzymes, such as peroxidases, can be used as polymerization or curing catalysts for lignin (PCT Publication No. WO/98/31761; EP 648 242).
PCT Publication No. 93/23477 discloses the production of a solution or gel of lignin at high concentrations free of solids by treating the lignin at a high pH and then lowering the pH to a desired value. A binder can be made by subsequently treating with a phenolic oxidase.
PCT Publication No. 95/07604 discloses a method of producing fibreboard, the method comprising the sequential steps of (a) providing an aqueous slurry or suspension of lignin-containing wood fiber material; (b) adding a phenol oxidizing system to the fiber slurry; (c) forming the fiber slurry into a mat of the wood fiber material; and (d) pressing the formed mat by applying heat and pressure to produce the fiberboard.
PCT Publication Nos. 98/31761, 98/31762, 98/31763 and 98/31764 further disclose lignin based adhesives and methods of producing such adhesives for the production of fiberboards.
PCT Publication No. 98/31728 discloses intermediates for the production of polymers from lignin derivatives from the pulp industry, produced by processing lignin derivatives with phenol oxidizing enzymes in the presence of oxidation agents. The invention is characterized in that the lignin derivatives are (a) subjected to enzyme treatment for more than 3 hours in the presence of air; (b) subjected to enzyme treatment for more than 10 minutes while air or oxygen is passed through them; or (c) are oxidized by treatment with chemical oxidation agents. The intermediate is used for the production of polymers of lignin derivatives from the pulp industry, of fiber reinforced duroplastic composite materials from plant fibers, of water proof papers and cardboards, as well as duroplastics from lignin derivatives.
Thus, there has been much activity in the field of using phenol oxidizing enzymes to produce adhesives from lignin. However, other uses of lignin and sulfite spent liquors are necessary to economically dispose of the large quantity of waste material produced by the pulp and paper industry.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide for a method of producing a coating for use in the protection, beautifying or otherwise treating an object.
It is a further object of the invention to provide for a method of producing such a coating from the waste liquors produced by the pulp and paper industry.
According to the present invention, a method is provided for producing a coated article comprising: (a) preparing a solution of lignin; (b) mixing the lignin solution with a phenol oxidizing enzyme; (c) incubating the mixture from said step (b) under conditions and for a time sufficient to form a solution of a desired viscosity; (d) contacting or spreading the mixture from the step (c) on an article to be coated; and (e) allowing the film to set onto the article by subjecting the article to conditions and for a time sufficient to form a film on the surface of the article. In a preferred embodiment, the phenol oxidizing enzyme is a catechol oxidase, laccase, bilirubin oxidase, monophenol monooxygenase or peroxidase. Also preferably, the laccase is derived from Aspergillus, Bacillus, Neurospora, Podospora, Botrytis, Collybia, Fomes, Lentinus, Pleurotus, Trametes, Rhizoctonia, Coprinus, Psatyrella, Myceliophthora, Schytalidium, Phlebia or
Coriolus
. Further preferably, the solution of lignin comprises lignin sulfonate. Also preferably, the lignin solution further comprises a copolymerization agent, for example, acrylic acid.
In another embodiment of the invention, a coated article is provided, wherein the coated article comprises a film comprising lignin and a phenol oxidizing enzyme.
In yet another embodiment of the invention, the coated article is not a lignocellulosic, wood or paper based product.
An advantage of the present invention is that it is possible to prepare a useful item, i.e., a coated article, from the waste product of the pulp and paper industry.
Yet another advantage of the present invention is that it is possible to produce a coated object using an environmentally safe process comprising enzymes and lignin.
Yet another advantage of the present invention is that it is possible to produce a coated object from lignin, wherein the coated object is not a lignocellulosic material or derivative there of itself.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
“Phenol Oxidase” means an enzyme system which is capable of using hydrogen peroxide or oxygen to oxidize oxygen containing phenolic groups. If the phenol oxidizing enzyme requires a source of hydrogen peroxide, the source may be hydrogen peroxide or hydrogen peroxide precursor for in situ production of hydrogen peroxide, e.g., percarbonate or perborate, or a hydrogen peroxide generating enzyme system, e.g., an oxidase and a substrate for the oxidase, or an amino acid oxidase and a suitable amino acid, or a peroxycarboxylic acid or a salt thereof Hydrogen peroxide may be added at the beginning of or during the process. If the phenol oxidizing enzyme requires oxygen, atmospheric oxygen is usually sufficient, or alternatively, oxygen or air can be added to the system by percolating oxygen gas through the mixture. Phenol oxidizing enzymes can be catechol oxidases (EC 1.10.3.1), laccases (EC1.10.3.2), bilirubin oxidases (EC 1.3.3.5), monophenol monooxygenases (EC 1.14.18.1) or peroxidases (EC 1.11.1.7). Laccases are especially preferred and are known from microbial and plant origins. Preferred microbial laccases are from fungi or bacteria and include those from
Aspergillus, Bacillus, Neurospora, Podospora, Botrytis, Collybia, Fomes, Lentinus, Pleurotus, Trametes, Rhizoctonia, Coprinus, Psatyrella, Myceliophthora, Schytalidium, Phlebia
and
Coriolus
. In a most preferred embodiment, the laccase is derived from
Trametes, Coprinus, Pleurotus, Stachybotrys
or
Coriolus
.
“Lignin solutions” means an aqueous solution of lignin. Generally, it is possible to obtain suitable lignin solutions from the effluent produced during the process of pulping wood fiber and the production of papers, particularly the spent sulfite liquors. Examples of suitable lignin solutions include lignin sulfonates (also known as lignin sulfonates and sulfite lignins) which are the product of sulfite pulping, kraft lignins (also called sulfate lignins) which are obtained via the kraft pulping process, and lignins obtained from other technologies using organic solvents or high pressure steam treatments to remove lignins from plants. However, one of ordinary skill in the art would recognize lignins which are suitable.
According to the process of the invention, the lignin solution is contacted with the phenol
Aehle Wolfgang
Bolle Rob
Cameron Erma
Genencor International Inc.
Stone Christopher L.
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