Polysaccharide-based water-compatible wood stain

Abstract

Water-based stains comprise or consist essentially of a polysaccharide resin and a crosslinking agent such as an isocyanate. Upon evaporation of water, the polysaccharide undergoes crosslinking with the isocyanate component, developing water resistance so that it will not redissolve upon application of a water-based or oil-based clearcoat; as a result, lifting is minimized after a drying time of, e.g., two to six hours.

Claims

1. A wood stain composition comprising: an aqueous solution of a crosslinkable polysaccharide having a structure wherein at least one hydroxyl group is bonded to at least one carboxyl group of an alkyd; a crosslinking agent crosslinkable with the polysaccharide upon drying of the aqueous solution; and a pigment dispersion.

2. The composition of claim 1, wherein the crosslinking agent consists essentially of a monomeric aliphatic diisocyanate, a toluene diisocyanate, a hexamethylene diisocyanate, a naphthalene diisocyanate, a methylene bis-cyclohexylisocyanate, or an isophorone diisocyanate.

3. The composition of claim 1, further comprising a thickener.

4. The composition of claim 3, wherein the thickener consists essentially of hydroxyethylcellulose, hydrophobically-modified ethylene oxide-based urethanes, or hydrophobically-modified alkali soluble emulsions.

5. The composition of claim 1, further comprising a defoamer.

6. The composition of claim 1, further comprising an amine.

7. The composition of claim 6, wherein the amine consists essentially of dimethylethanolamine, monoethylethanolamine, trimethylethanolamine, morpholine, or ammonia.

8. The composition of claim 1, further comprising a surfactant.

9. The composition of claim 8, wherein the surfactant is a nonionic surfactant.

10. The composition of claim 9, wherein the surfactant is an octylphenol ethoxylate surfactant.

11. The composition of claim 8, wherein the surfactant has a hydrophile-lipophile balance value between 5 and 15.

Description

DETAILED DESCRIPTION

(1) Polysaccharides are polymers of simple sugar building blocks, and may be crosslinked into hard, three-dimensional polymer networks. Compositions in accordance herewith include an aqueous solution of a crosslinkable polysaccharide and a crosslinking agent crosslinkable with the polysaccharide upon drying of the aqueous solution. These two components are generally packaged separately and combined just prior to application. The crosslinking agent may undergo an addition reaction with hydroxyl groups of the polysaccharide and may be, for example, an isocyanate (e.g., a monomeric aliphatic diisocyanate, a toluene diisocyanate, a hexamethylene diisocyanate, a naphthalene diisocyanate, a methylene bis-cyclohexylisocyanate, and/or an isophorone diisocyanate). Polymer network properties can be tailored by adjusting the concentration of the dissolved polysaccharide and the amount of crosslinking agent.

(2) Suitable generic formulations are as follows:

(3) TABLE-US-00001 Component Weight % Amine 0.1%-2% Thickener 0.1%-2% Defoamer 0.1%-1% Octylphenol ethoxylate 0.1%-5% surfactant Pigment dispersion 2%-15% Polysaccaride solution 5%-40% Isocyanate 3%-20%

(4) The thickener is used to adjust the viscosity of the composition to a desired value. Suitable thickeners include hydroxyethylcellulose, hydrophobically-modified ethylene oxide-based urethanes, hydrophobically-modified alkali soluble emulsions, and/or other alkali-soluble associative thickeners. The amine, in turn, is used to activate the thickener. Suitable amines include dimethylethanolamine, monoethylethanolamine, trimethylethanolamine, morpholine, and/or ammonia. The defoamer is employed break foam generated during formula processing and/or application of the stain onto wood; suitable defoamers include deaerators such as AIREX 900, available from TEGO. All three of these components are optional. The surfactant may have a hydrophile-lipophile balance (HLB) value between 5 and 15.

(5) A suitable polysaccharide is the LPR76 product supplied by Lorama Group Inc., Ontario, Canada, and a suitable isocyanate is the Bayer DESMODUR H (HDI) product. No drying agent is needed. The system can be pigmented using any suitable pigment composition (most common water-based pigments dispersions can be employed) to the desired color space.

(6) The polysaccharide component may be formed by mixing the water, amine, thickener, defoamer, polysaccharide and pigment dispersions in a vessel until homogeneous. Just prior to stain application the isocyanate component is added.

(7) While the invention has been described in conjunction with the specific embodiments thereof, one of ordinary skill in the art will understand that any alternatives, modifications, and variations of the types of the ingredients and/or the amounts thereof contained in the single formula finish are possible and are they within the scope of the present invention.

(8) The terms and expressions employed herein are used as terms and expressions of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof. In addition, having described certain embodiments of the invention, it will be apparent to those of ordinary skill in the art that other embodiments incorporating the concepts disclosed herein may be used without departing from the spirit and scope of the invention. Accordingly, the described embodiments are to be considered in all respects as only illustrative and not restrictive.