FIELD

The present invention is directed to cat or animal litter, and more particularly to an extruded self-clumping cat litter.

BACKGROUND

Many attempts have been made in the past to try to make lightweight cat or animal litter. One type of sorbent commonly used in cat or animal litter is clay-based, typically made of bentonite granules. Conventional clay-based cat or animal litters typically have a density greater than 40 pounds per cubic feet, making them not only relatively costly to ship but relatively challenging to carry because litter containers tend to be rather heavy.

Conventional clay-based litter is typically made of granules of smectite, typically smectite or swelling clay(s), like bentonite clay(s), which frequently includes other components like calcium carbonate, silica, fragrances or scents, and odor controllers. While many attempts have been made in the past to produce lighter weight clay-based litters having bulk densities less than 40 pounds per cubic feet, these attempts have had limited success. Quite often litter performance is either adversely impacted or the weight reduction not all that significant.

While many attempts to produce lighter weight clay-based litter by adding lighter weight components are limited by the fact that such litters still require at least 70% swelling clays, typically bentonite, to still perform adequately as litter. This typically is because the lighter weight components added to reduce weight and bulk density are nothing more than fillers as they typically are not absorbent nor facilitate clumping. Because such litter still requires so much bentonite to adequately perform as a result, there is a limit to how much its weight and bulk density can be reduced.

One problem with a clay-based litters and clay-based sorbents in general is the fact that clay is not biodegradable. This requires spent clay-based litters to be put in the garbage for landfill disposal. For clay-based and other similar mineral or inorganic-based sorbents used to pick up oil, remediate chemical spills on land and in water, as well as treat oil spills on land and in water, disposal is a lot more complicated and costly. Expensive high temperature treatment in a kiln is typically required, which even then does not completely dispose of everything. While ash, pebbles and rocks leftover can be used in small percentages in concrete, it still needs to be handled and transported adding to overall disposal costs.

Other attempts have been made to produce litter from extruded pellets. Unfortunately past attempts have been heretofore unsuccessful as such extruded pellets were poorly absorbent, needed to be crushed in order to work, needed bentonite in the admixture, would not stick or clump when wetted, and/or would not form clumps that stay together among other deficiencies.

What is needed is an improved lightweight cat litter that does not suffer from at least one or more of these drawbacks.

SUMMARY

The present invention is directed to self-clumping litter formed of extruded sorbent litter pellets extruded from a starch-containing admixture at an extruder temperature and extruder pressure and/or extruder die pressure high enough to form water-soluble binder from starch in the admixture sufficient for pellets in a litter box to self-clump together when wetted. In a preferred litter, each pellet is extruded an admixture containing one or more cereal grains, with water-soluble binder formed in the extruded pellet from starch in the admixture during pellet extrusion sufficient to solubilize when wetted and at least become tacky enough to stick wetted pellets together forming clumps of pellets having a relatively high clump retention rate and which possess high crush strength.

In a preferred litter, extruded pellets have sufficient water soluble binder that pellet wetting solubilizes enough binder to at least make a portion of each wetted pellet tacky enough to stick to at least a plurality of other pellets clumping them together. In one such preferred litter, extruded pellets have sufficient water soluble binder that pellet wetting solubilizes enough binder to cause at least some of the binder to form a flowable adhesive with the wetting liquid, e.g., water or urine, which flows from the wetted pellet and around a plurality of pellets clumping them together. Where flowable adhesive is formed by wetting of extruded litter pellets with liquid, such as water, e.g., 2% saline solution, or urine, the flowable adhesive rapidly increases in viscosity after wetting from a viscosity of at least 200 centipoise within one second after wetting, increases to at least 300 centipoise after one second and within five seconds after wetting, increases to at least 400 centipoise after five seconds and within 10 seconds of wetting, and increases to at least 1000 centipoise after 10 seconds and within 30 seconds of wetting such that the liquid, e.g., water, in solubilizing water-soluble binder forms a relatively high viscosity flowable adhesive gel that relatively rapidly adheres together the at least plurality of pairs of wetted pellet forming a clump having a desirably high clump retention rate of at least 90% and which is preferably at least 92%.

Such a preferred litter is formed of extruded litter pellets each having a sufficient amount of water-soluble binder formed in each pellet during extrusion to self-clump when wetted. In one preferred extruded self-clumping, pellets are extruded having a water soluble content of at least 15% by pellet weight and a water soluble binder content of at least 7.5% by pellet weight. In another preferred extruded self-clumping litter, pellets are extruded having a water soluble content of at least 15% by pellet weight and a water soluble binder content of at least 10% by pellet weight. In still another preferred extruded self-clumping litter, pellets are extruded with a water soluble binder content of at least 15% by pellet weight. In another preferred extruded granular absorbent, pellets are extruded having a water soluble content of at least 20% by pellet weight and a water soluble binder content of at least 10% by pellet weight. In a further preferred extruded self-clumping litter, pellets are extruded having a water soluble content of at least 20% by pellet weight and a water soluble binder content of at least 15% by pellet weight. Such water soluble binder preferably is a cold water soluble binder, preferably a cold water soluble amylopectin binder, and more preferably an amorphous cold water soluble amylopectin binder, formed by physical modification of starch or starches, preferably by physical modification of amylopectin, in their original form in the admixture extruded to form each self-clumping litter pellet.

Litter formed of such extruded pellets advantageously self-clump when wetted forming clumps each having a desirably high clump retention rate of at least 90% and which is preferably at least 92%. Litter formed of such extruded pellets advantageously self-clump when wetted forming clumps each having a clump crush strength of at least 15 pounds per square inch, preferably at least 20 pounds per square inch, and more preferably at least 25 pounds per square inch when each clump is dried.

Extruded litter pellets of extruded self-clumping litter form clumps that shrink after formation at least 3%, preferably at least 5%, and more preferably at least 10% helping to produce clumps having such a high clump retention rate and/or high crush strength. Litter formed of such extruded pellets of the present invention produce clumps when the cat litter is wetted that shrink and advantageously condense through absorption and drying thereby causing the clump to pull away from any solid surface in contact with the clump minimizing clump adhesion with the solid surface helping prevent any portion of the clump from sticking thereto. As a result, such cat litter formed of extruded litter pellets of the present invention form clumps that shrink when wetted also thereby produce clumps that are of nonstick construction advantageously forming “clean” “non-stick” litter clumps in accordance with another aspect of the invention.

In addition to litter composed of extruded litter pellets of the present invention forming clean clumps when wetted, such litter composed of at least a plurality of extruded litter pellets per cubic inch volume of the litter used in their as extruded form advantageously produce de-dusting litter by each extruded pellet used in its as-extruded form acting as a dust magnet. Without being wetted, each extruded pellet used in extruded form in litter of the present invention has sufficient water-soluble material on and in an exterior surface of each pellet to cause dust in the litter to adhere to the water-soluble material of an outer pellet surface contacting the dust preventing such dust from becoming airborne. In a preferred embodiment, without being wetted, water soluble binder present in the outer surface of each extruded pellet used in extruded form in such a low-dust litter of the invention is dust attracting causing dust in the litter to stick to the water-soluble binder of extruded uncoated pellets in the litter, while the binder is dry, preventing such dust from becoming airborne. Such de-dusting extruded self-clumping litter composed of uncoated extruded litter pellet dust-magnets in accordance with the present invention enable retail bags or containers filled with such litter to contain less than 5% dust, preferably less than 3% dust and preferably less than 1% dust by litter weight.

In one preferred extruded self-clumping cat litter, the litter is formed of a mixture of extruded pellets having a plurality of different sizes that prevent liquid, e.g., water or urine, being absorbed from channeling downwardly between pellets thereby forming clumps on top of the litter which are generally horizontally oriented making such clumps easy to scoop out of the litter and dispose of. In such a preferred extruded litter, the litter has at least a plurality of pairs, i.e., at least three, of larger sized extruded litter pellets per cubic inch of litter volume of a first size range, and at least another plurality of pairs, i.e. at least three, of more finely sized extruded litter pellets per cubic inch of litter volume, e.g. fines, of a second size range smaller than the first size range. A preferred extruded self-clumping litter has at least 15% fines, preferably has at least 20% fines, with the remainder of the extruded pellets being larger sized pellets. Another preferred extruded self-clumping litter has at least 5% fines and preferably has between 5% and 40% fines, with the remainder of the extruded pellets being larger sized pellets. Still another preferred extruded self-clumping litter has at least 5% fines and preferably has between 10% fines and preferably has between 10% and 30% fines, with the remainder of the extruded pellets being larger sized pellets.

In one such preferred extruded self-clumping cat litter, the litter is formed of a mixture of at least a plurality of pairs, i.e., at least three, of larger sized extruded pellets per cubic inch of litter volume of a first size range, and at least another plurality of pairs, i.e. at least three, of more finely sized extruded pellets per cubic inch of litter volume, e.g. fines, of a second size range smaller than the first size range. Such fines preferably are formed of smaller sized extruded pellets having a size falling within the second size “fines” range but also can be formed of pieces of extruded pellets having a size falling within the second size “fines” range. Such an extruded self-clumping litter formed of a mixture of differently sized pellets has at least 5% fines, preferably at least 10% fines, more preferably at least 15% fines, with the remainder of the pellets of the litter being larger sized extruded pellets. Another preferred extruded self-clumping litter has at least 5% fines and preferably has between 5% and 40% fines, with the remainder of the extruded pellets being larger sized pellets. Still another preferred extruded self-clumping litter has at least 5% fines, preferably has between 5% fines and 35% fines, and more preferably has between 10% and 30% fines, with the remainder of the extruded pellets being larger sized pellets.

In a preferred litter embodiment, each litter pellet is extruded from an admixture not containing any smectite nor any binder additive and is used in uncoated form. In another preferred litter embodiment, each litter pellet is extruded from an admixture not containing any smectite nor any binder additive and is used without any smectite, e.g., bentonite, coating. In still another preferred litter embodiment, each litter pellet is extruded from an admixture not containing any smectite nor any binder additive and is used in its as-extruded form.

These and other objects, features and advantages of this invention will become apparent from the following detailed description of the invention and accompanying drawings.

