Coating processes – Medical or dental purpose product; parts; subcombinations;... – Particulate or unit-dosage-article base
Reexamination Certificate
1996-08-22
2001-08-14
Pianalto, Bernard (Department: 1762)
Coating processes
Medical or dental purpose product; parts; subcombinations;...
Particulate or unit-dosage-article base
C427S002180, C427S004000, C427S213310, C427S348000, C427S420000, C427S424000
Reexamination Certificate
active
06274190
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to apparatus for coating or pelletizing particulate, and more particularly to an improved seed coating apparatus having interchangeable oscillating air permeable trays.
BACKGROUND OF THE INVENTION
It has been known for many years to coat small particles, such as seeds and pharmaceutical products. Generally, a coating which increases the weight of the seed up to 25% is defined as a film coating. A coating which increases the weight of the seed more than 25% is referred to as pelletizing. Pelletizing provides uniformity of size to the particles. Depending on the extent of coating applied, pelletizing may provide a spherical shape to the particles which are normally elongated or irregularly shaped.
There are three primary reasons for providing a coating to such particles. First, a protective coating is often applied to seeds so as to prevent dust-off of prior treatments that have been applied. For example, a film of biological material may be applied to the seed to increase the viability of the seed, and a protective coating is needed to prevent the film from being worn away from the seed during handling. The protective coating allows for a reduction in the amount of film treatment that needs to be applied, thus reducing costs to the seed company. The protective coating also increases the effectiveness of the film treatment by encapsulating the film on the seed. Also, the protective coating reduces environmental hazards of the film treatment.
Another purpose of providing a coating to seeds and small pharmaceutical products is to increase the size of the particle, particularly for seeds which are too small to be mechanically planted. Such an increase in size allows small seeds to be planted mechanically, rather than manually, thereby resulting in significant labor savings, both during the planting and by eliminating manual thinning. Mechanical planting also reduces the seed population required for planting, thereby providing further cost savings.
A third benefit provided by seed coatings is to increase the visibility of the seeds during planting. Therefore, more accurate and less wasteful planting results.
In prior art pelletizing operations, a binder material in a solution was applied by spray, and then a bulking agent, such as clay or wood fibers, was manually applied to the seeds. After the two-step binding and bulking operations were completed, the coated seeds were then taken to an over to bake dry. Thus, the prior art multiple-step process was slow, time consuming, and labor intensive.
SUMMARY OF THE INVENTION
Therefore, a primary objective of the present invention is the provision of an improved method and means for coating particulate material, such as seeds.
Another objective of the present invention is the provision of a method and means for continuously coating seeds, wherein the coating solution is applied and dried on an oscillating bed.
A further objective of the present invention is the provision of a method and means for coating seeds wherein multiple layers of different coatings can be applied to the seeds in a continuous process.
Still another objective of the present invention is the provision of a method and means for continuously pelletizing seeds wherein a binder and bulking agent are applied simultaneously in a solution.
Yet another objective of the present invention is the provision of a continuous pelletizing machine having an oscillating bed which is vented for substantially instantaneous drying of the seeds as the seeds are coated.
Still another objective of the present invention is the provision of a method and means for continuously coating particulate material wherein the flow rate of the material through a coating chamber is selectively adjustable by the use of interchangeable oscillating beds or trays.
Yet another objective of the present invention is the provision of a method and means for coating particulate material in an oscillating bed chamber which is maintained at a negative pressure.
A further objective of the present invention is the provision of a means for continuously coating particulate material which is economical to manufacture, and efficient and durable in use.
These and other objectives will become apparent form the following description of the invention.
The apparatus for coating seeds and particulate material of the present invention includes an elongated tray operably mounted on a support frame with a motor for oscillating the tray to move particulate material from a rearward end to a forward end therealong. The tray includes a perforated support surface with a saw-toothed cross-sectional shape such that the particulate climbs the inclined tread of each sawtooth and drops from the forward end of one tread to the rearward end of an adjacent tread to form a “curtain”. A plurality of spray nozzles are located over the tray to direct coating solution onto the seeds as they move along the tray. Preferably, the nozzles direct spray towards the curtain of falling seeds between the treads. An upper housing on the support frame includes an air plenum which directs air downwardly onto the seeds on the support surface and through the perforated support surface to a second air plenum formed under the support surface. A flexible seal connects the tray to the upper housing to form an air seal yet permit oscillating movement of the tray. An exhaust fan is connected to the second air plenum to exhaust air from the coating apparatus and create a negative pressure within the coating apparatus. Preferably, air provided to the housing is heated, to enhance drying of the coating sprayed on the particulate material.
REFERENCES:
patent: 2799241 (1957-07-01), Wurster
patent: 3533829 (1970-10-01), Quanquin
patent: 3894508 (1975-07-01), Burgess
patent: 4640218 (1987-02-01), Motoyama et al.
patent: 4808424 (1989-02-01), Wadell
patent: 5299366 (1994-04-01), Maier et al.
patent: 5470603 (1995-11-01), Staniforth et al.
Barber Donald E.
Long, Jr. Richard L.
Coating Machinery Systems, Inc.
Pianalto Bernard
Zarley McKee Thomte Voorhees & Sease
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