1. Field of the Invention
This invention relates to a method for avoiding lump formation when hydrophilic gums are dispersed in aqueous systems and to compositions resulting therefrom.
2. The Prior Art
Hydrophilic gums are widely used in industry. They are formulated into pharmaceuticals, cosmetics, personal care products, papers and other diverse compositions. Their functions include acting as thickeners, binders, stabilizers, protective colloids, suspending agents and rheology or flow control agents. Generally, gums are blended directly into aqueous solutions. Upon contact with water, these materials swell and convert to viscous gel-like sols.
Rapid addition of hydrophilic gum to water is highly desirable. Unfortunately, rapid contact with water frequently results in lumping. More controlled addition only partially circumvents the problem. The lumps are gel-like substances, wet on the outside, dry in the center. Lumps usually resist dispersion even upon vigorous agitation or cooking. Once formed, extraordinary efforts are needed to effect their removal. Not only time, but considerable material is lost during removal.
Commercially, lumping has been avoided by pre-swelling the dry gums prior to addition into aqueous systems. Slow, careful wetting of gum with minor amounts water accomplishes the pre-swelling. Yet lumping is seldom totally avoided. The wetting process is time consuming. Production rates of end-product must be slowed to the rate limiting step, i.e., the pre-swell process.
Numerous patents record attempts to solve the problem by designing more readily dispersible gums. For instance, U.S. Pat. No. 2,662,882 modifies the gum by pre-wetting with water, agglomerating, regrinding and drying at room temperature. Dry-mixing gum with sodium bicarbonate or carbonate and an acid such as sodium bisulfite yields readily dispersible powders according to U.S. Pat. No. 2,807,591. In U.S. Pat. No. 4,309,535, sodium carboxymethyl cellulose, hereinafter referred to as CMC, was treated with aluminum chloride dissolved in aqueous isopropanol; drying afforded easily dispersible particles. British Pat. No. 926,409 disclosed that treatment of CMC with a fine water spray in a pulsating trough yielded a power of 5% moisture content with improved dispersibility. Other easily dispersible powders have been reported obtainable where CMC has undergone treatment either with aqueous sodium sulfate, been sprayed with aqueous Sorbit, or been stirred with aqueous mono- and di-glycerides, see Japanese Patent Nos. 78:45,358, 78:65,489 and 80:61,928, respectively. In Japanese Patent No. 73:52,848 cellulose derivatives were swelled with approximately an equivalent weight of water containing a small amount polyethylene glycol. After drying, gum granules were obtained that upon dissolution in water afforded lump-free solutions.
All the aforementioned art has pertained to modifying gum powders to enhance their water solubility. In contrast, the literature is relatively silent concerning direct methods to improve processing of hydrophilic gums into aqueous consumer products. Even with modified powders, blending difficulties are often noted. New techniques are still needed to increase gum-water blending efficiency that avoids lumping.
It is an object of this invention to present a process for dispersing hydrophilic gums swiftly into water containing formulations while avoiding the lumping problem.
It is a further object to provide lump-free compositions comprising hydrophilic gums, water and alcohol.