This invention relates to an improved absorbent material and a process for making it. More particularly it relates to an animal litter which is composed of a particular combination of ingredients and is made by an agglomeration process.
Most such absorbent materials in the prior art are made by mere mixing of ingredients, the use of a pellet mill or an extrusion process, or the material is used per se. As is well known, the use of a pellet mill requires pressure for compaction and is a "dry" process wherein the amount of moisture cannot be more than about 17 or 18%. An extrusion process is a so-called "wet" process wherein about 30 to 50% moisture can be included with the ingredients and, following extrusion, the material is cut into pellets and dried.
The first animal litter absorbent products which achieved commercial success were based on the use of particular types of moisture-absorbent clay, that is diatomaceous earths. These materials were primarily constituted solely of various such clays and so were relatively heavy and increased shipping and handling costs were involved. Furthermore, such clays being of a special nature are found only in a few areas and have to be shipped long distances. Dust is also a problem with the clay-based animal litters, which dust can cause allergies in people and animals. Furthermore such materials do not absorb or neutralize odours.
Other animal litters which have been suggested for livestock and poultry, and in some cases for animals such as cats and dogs, rabbits and the like, are peat moss, a waste material from sugar plantations known as bagasse, treated cotton seed hulls, acidified cellulosic material, ground peanut hulls which may be pelletized, ground paper, finely divided calcium hydrosilicate, sand and the like as the main ingredients. However, none of these materials have been used or suggested for use in any agglomeration process. Sand is heavy and cannot be granulated by itself. Of the other materials, even when they are pelletized they tend to disintegrate in the presence of liquid animal waste. Even though they may have satisfactory adsorptive capacity they are dusty and too light to serve as satisfacory animal litters, particularly for cats, as they are too easily scattered about. Furthermore, some of these materials are regional products and even seasonal, leading to an unsure source of supply. None provide an all-purpose product and are generally impractical for use as a cat litter.
Still other animal litters which have been developed are generally made by the use of a pellet mill or an extrusion process and are based on the use of materials such as fibrous materials, as for example alfalfa, and also materials such as vermiculite, and other lightweight materials. However these litters are also of low density which, despite the claims for such products, is not an advantage in that they tend to adhere to the animal and get tracked around the house or surroundings. Also cats, for example, like to scratch and cover their excrement and with such light materials scattering occurs. In fact, this is one of the main reasons why these materials have not replaced the clay based products on the market.
Alfalfa and other grasses have been considered for animal litters particularly because of the presence of chlorophyll therein which provides odour control. However such products are more expensive than clay products and possess other disadvantages. These pelletized or formed products are often soluble to some extent in liquid animal wastes, and decompose and/or clump after use as the pellets disintegrate on the absorbtion of moisture. This nullifies the effectiveness of the product. Odour control is, furthermore, not always satisfactory and sometimes the composition itself has an unpleasant odour.
An agglomeration process has been suggested in the art for the manufacture of an animal litter. U.S. Pat. No. 3,789,797 of Brewer relates to a method of preparing an animal litter for household use. The process relates to the mixing of ground and screened alfalfa with bentonite and then tumbling the particles in an agglomeration process and drying the non-compacted pellets. A moistened binder is added to the powder, the binder being for example molasses, wood molasses, modified starches or a non-toxic glue. The liquid material is disclosed as being added to the agglomerator by pouring. Because of this the product would be fairly soft, light and of large pellets which would have to be ground to smaller particles to serve as a cat litter. Furthermore, despite the allegations in this patent, it would appear from the materials and the proportions used that the litter would be light in weight and would in fact be tracked away from the litter area by the animal. Also this litter would be subject to microbial degradation, and when the binder is water-soluble, the litter would be subject to ever further degradation on contact with moisture.