Clumping animal litter and method of making same

#This invention relates to cellulose-based animal litter products, and in particular to clumping-type animal litters comprising cellulose-based core particles that are covered with specially designed water-permeable coatings.

#American families increasingly prefer cats, with their independent natures and reduced need for care, as compared with dogs. Domesticated animals such as cats are provided in homes with litter boxes, where they dispose of their biological waste. The performance of the litter product in the litter box can vary greatly, depending upon the precise nature of the product. Key attributes of a litter product that are of importance to cat owners are odor control and litter care convenience (that is, supply and removal).

#Originally litter products were relatively unsophisticated, and of the type known today as “non-clumping”. More recently, clumping type cat litters have been introduced. Both types are essentially equivalent with respect to the removal of solids. With both types, solid excretions are scooped out of the litter box daily or at least frequently. However, clumping litters provide great advantages with respect to the way in which urine excretion is handled. Non-clumping litters absorb the urine and hold it until ammonia-type malodors develops, at which time the entire content of the litter box is removed and replaced. Clumping litters, however, are designed to gel when wetted by urine, and the urine soaked granules agglomerate into clumps whose mechanical strength facilitates their removal in the same manner as solid waste is removed, leaving the remaining litter fresh and urine-free.

#The present invention will be more fully understood from the detailed description give hereinbelow and by reference to the accompanying drawings. The drawings are provided by way of illustration only and are not intended to limit the invention.

#FIG. 1 schematically depicts a cross-section of a coated litter granule of the present invention.

#FIG. 2 is a block diagram of an overall manufacturing process for making the coated litter granules of the present invention.

#The products of the present invention are clumping animal litters composed of a plurality of discrete, dual-component, artificial granules. The coated litter granules of this invention are depicted schematically in FIG. 1, which shows a cross-section of a granule 10 that comprises a core 11 surrounded by a coating 12. The granules of this invention deliver excellent levels of malodor absorption, adsorption, and prevention. They agglomerate with neighboring granules when wet, forming cohesive clumps that are strong enough mechanically to be easily scooped away from a litter box for disposal.

#This invention provides an animal litter granule that has the form of a coated core. The core component is made up of 15-45 weight-% dry cellulose fine fibers, 40-80 weight-% dry mineral filler, and 0.5-10 weight-% binder. The coating component contains 65-99 weight-% clumping agent, 1-25 weight-% zeolite, and/or 1-3 weight-% of a urease inhibitor, which is generally a boron compound such as boric acid. The coating component may also contain up to 30 weight-% dry cellulose fine fibers. In the granules of the present invention, the coating component has a mass that may range from half to twice the mass of the core. Typically, however, the mass of the coating component in a granule is very roughly approximately equal to the mass of the core component in the granule.

#The term “granule,” as used herein, refers to any particulate form of matter such as particles, chips, pellets, and the like. The granules of the present invention generally have a mean particle size in the range of about 0.25 to about 4.75 millimeters, that is, from about 60 mesh to about 4 mesh, U.S. Sieve Series. For a tabulation of U.S. Sieve Series screen nomenclature, see Perry's Chemical Engineering Handbook, 6th Ed., McGraw-Hill, Inc., New York, N.Y. (1984), p. 21-15 (Table 21-6).