Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Enzyme component of specific activity or source
Reexamination Certificate
2002-03-19
2003-07-08
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Enzyme component of specific activity or source
C510S438000, C510S442000, C510S446000, C510S530000, C435S187000
Reexamination Certificate
active
06589929
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an enzyme-containing granulate (made up of enzyme-containing granules or particles) with extremely low tendency to dust formation, to a process for producing such a granulate, and to the use of said granulate for a number of industrial applications.
BACKGROUND OF THE INVENTION
The industrial use of enzymes, notably enzymes of microbial origin, has become increasingly common. Enzymes are used in numerous industries, including, for example, the starch-processing industry and the detergent industry. It is well known that the use of enzymes, particularly proteolytic enzymes, in the detergent industry has given rise to industrial hygiene concerns for detergent factory workers, particularly due to the health risks (including the risk of allergy development) associated with any formation of enzyme-containing dust which may occur.
Since the introduction of enzymes into the detergent industry, a lot of effort has been devoted to improving the granulation and coating of enzymes so as to reduce enzyme dust formation.
One type of process for producing an enzyme-containing granule comprises coating the surface of a core with an enzyme followed by an outer layer coating. U.S. Pat. No. 5,324,649 describes coating of the surface of a non-pareil core with an enzyme followed by an outer layer coating. U.S. Pat. No. 4,689,297 and EP 0 532 777 describe a process which comprises applying an enzyme on the surface of a salt crystal based core or a non-pareil core, by spraying the enzyme onto the core in a fluid-bed followed by an outer layer coating.
Yet another type of process essentially comprises: (i) mixing an enzyme with suitable granulation components (preferably as dry matter), such as filler, binder, fibrous material and a granulation agent (e.g. water) in a granulator (e.g. a mixer), and (ii) processing the mixture in a granulating apparatus until the granule has the desired particle distribution and degree of roundness (sphericity).
Numerous references describe processes for making enzyme-containing granules by such a process. Such references include U.S. Pat. No. 4,242,219, U.S. Pat. No. 4,740,469, WO 94/04665, U.S. Pat. No. 4,940,665, EP 564476, EP 168526, U.S. Pat. No. 4,661,452, U.S. Pat. No. 4,876,198, WO 94/16064 and U.S. Pat. No. 4,106,991.
Further, U.S. Pat. No. 5,494,600 and U.S. Pat. No. 5,318,903 describe a process comprising absorption of an enzyme into a porous hydrophobic core (e.g. a porous hydrophobic silica core) followed by coating.
Although granulation techniques have improved, in order to take account of increasing environmental concerns and heightened awareness in the field of industrial hygiene, there remains a continuing need for enzyme-containing, granular compositions exhibiting even lower dust formation than presently available products.
An object of the present invention is to provide such enzyme-containing granular compositions, and improved processes for producing such compositions.
SUMMARY OF THE INVENTION
It has surprisingly been found that extremely low tendency to dust formation by enzyme-containing granules is achievable when the granules are based on suitably selected cores (particles), more specifically cores fulfilling, in particular, certain requirements with respect to liquid-absorption properties.
A first aspect of the present invention thus relates to an enzyme-containing granule comprising:
(a) an enzyme, and
(b) a core which intrinsically is capable of absorbing at least 5% by weight (w/w) of water (relative to the weight of the core).
In keeping with this first aspect of the invention, a further aspect of the invention relates to a process for producing enzyme-containing granules from absorbent cores, the process comprising:
(a) contacting absorbent cores, capable of absorbing at least 5% w/w (based on the weight of the core) of water, with a liquid medium containing an enzyme in dissolved and/or dispersed form, the amount of the liquid medium employed being such that substantially no attendant agglomeration of the resulting product occurs; and
(b) at least partially removing volatile components of the liquid medium from the resulting product.
DETAILED DESCRIPTION OF THE INVENTION
Cores
Cores forming the basis of enzyme-containing granules of the invention (and in the context of processes according to the invention for the preparation of such granules) are cores which, in the absence of a hydrophobicity-reducing substance or surface-tension-reducing substance (such as a surfactant) and of constituents of the enzyme-containing granules (notably the enzyme or enzymes in question) other than those of the core itself, have an intrinsic (i.e. inherent, innate or “native”) ability to absorb at least 5% w/w of water when brought into contact with water (i.e. essentially pure, liquid water).
Cores of relevance in the context of the invention are preferably capable of absorbing at least 10% w/w (based on core weight) of water, more preferably at least 15% w/w and still more preferably at least 20% w/w. Particularly preferable cores are cores capable of absorbing at least 30% w/w of water, such as cores capable of absorbing at least 33% w/w. Certain preferred types of cores have an even greater water-absorption capacity (e.g. about 40% w/w or more of water).
The ability of a particular type of core to absorb water may suitably be determined, for example, by spraying a measured amount of water onto a measured amount of cores with mixing in a mixer [e.g. as described in Example 1 herein (vide infra)] and observing the appearance and behaviour of the cores in the course of spraying; ambient conditions (ambient temperature, pressure etc.) are generally suitable. In general, as long as the amount of cores in question is able to absorb water there is essentially no agglomeration of the wetted cores (i.e. agglomeration to form lumps or the like) and it is possible to remove the resulting individual particles and dry them without significantly changing the overall particle size distribution.
In the context of the invention, a quoted weight percentage of water which a given type of core is capable of absorbing is thus a “macroscopic”, overall value determined using a relatively large amount (and thereby a large number) of cores (particles) of the given type, such as a multi-kilogram quantity (e.g. an amount of about 5, 10, 15 or more kilograms of the given type of core).
If appropriate, smaller quantities of cores may, however, be employed for the determination of water-absorption capacity, provided (i) the number of individual core particles in the sample employed is sufficiently high to be adequately representative of the bulk cores, and (ii) the sample employed is sufficiently large to permit satisfactorily gradual addition of water (preferably by spraying), with adequate mixing, while observing the appearance/behaviour of the cores with respect to surface wetness and tendency to agglomerate.
With a poorly absorbing or non-absorbing core material, agglomeration of the granules will normally occur upon introduction of only a small amount of water, and consequently it will generally not be possible to maintain the initial overall particle size distribution.
An example of a poorly absorbing core material is a conventional sugar/starch-based particle of the so-called nonpareil type. In working examples herein (vide infra) it is shown, inter alia, that a typical nonpareil core product is able to absorb less than 4% of water by weight (relative to the core).
Preferred embodiments of enzyme-containing granules of the invention are granules wherein at least part of the total amount of enzyme present in the granule is absorbed within the core; such granules will often be granules wherein at least part of the total amount of enzyme present in the granule has been absorbed into the core via contact of the outer surface of the core with a liquid medium containing the enzyme in question.
Such embodiments appear [cf. the working examples herein (vide infra)] to be advantageous in relation to achievin
Bonde Michael
Bordin Eder Manzini
De Lima Joao F.
Levring Kirsten Boegh
Marcussen Erik
Garbell Jason
Gupta Yogendra N.
Lambiris Elias
Mruk Brian P.
Novozymes A/S
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