Gel coating method and apparatus

Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article

Reexamination Certificate

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Details

C264S299000, C425S093000, C425S117000, C425S270000

Reexamination Certificate

active

06572809

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a method and apparatus for coating with a gelatinizer an object having a growth ability such as a seed, a cell piece or the like having a germinating or rooting ability, and more particularly to a gel coating method and apparatus also capable of gel-coating a heavy seed or a seed having a poor germinating ability.
BACKGROUND ART
Conventionally, a coated object obtained by coating such an object to be sealed as a seed, a cell piece or the like with a macromolecular gel containing nutriments, medicament and the like and being elastic (hereinafter generically, the object to be sealed is called a “seed” and the coated object is called a “coated seed”; and that is, hereinafter in case of referring to a “seed” or a “coated seed”, the “seed” means not only a seed but also any object having a growth ability such as a cell piece having a germinating or rooting ability) is known. The coated seed has many advantages such as that the coated seed is effective to protect the seed from being eaten by animals or sterilize the seed, that it makes it easy to handle the seed by making the seed larger in grain diameter and thereby makes its seeding operation more efficient, and that furthermore it enables to improve its germination rate due to absorbing nutriments in the macromolecular gel.
By the way, as a typical method for automatically manufacturing above-mentioned coated seed, there are a double-cylinder nozzle method and a mold method.
First, a double-cylinder nozzle method is explained with reference to FIG.
7
. This method slightly pressurizes the inside of a gel accommodating portion
3
of a gel accommodating block
2
into which a gelatinizer is supplied from a gelatinizer tank, not shown, by means of an air cylinder, not shown, fills a passage
4
of the gel accommodating portion
3
and a space
5
communicating with the passage
4
with the gelatinizer as well as raises the pressure inside the space
5
, and thereby moves upwardly a cylindrical plunger
6
mounted so as to be moved up and down inside of a nozzle block
1
against the elastic force of a coil spring
7
provided on the top end of the plunger
6
, and slightly opens a valve
8
and discharges the gelatinizer to form a thin film of the gelatinizer on the lower end of the valve
8
. After that, this method throws a seed
9
into a passage
6
a
of above-mentioned plunger
6
and makes above-mentioned thin film hold the seed
9
and then further pressurizes the inside of above-mentioned gel accommodating portion
3
to raise the internal pressure of the space
5
, and thereupon above-mentioned valve
8
is greatly opened and a great amount of gelatinizer is discharged and the gelatinizer wraps the seed
9
in it in cooperation with above-mentioned film, and when a grain-shaped gel-coated seed
9
a
is formed thereby, the gel-coated seed
9
a
is dropped due to its own weight into an lower hardening tank, not shown, containing a hardening agent. The gel part of the gel-coated seed
9
a
is hardened while being conveyed through the hardening tank, and the hardening agent is washed away in a water-washing portion to form a product.
However, such a double-cylinder nozzle method has a disadvantage that in case of gel-coating a heavy seed such as corn, bean and the like, it cannot be gel-coated in some cases because above-mentioned thin film of the gelatinizer is broken by the shock of dropping of the seed. In order to prevent the break of the thin film, it is conceivable to raise the viscosity of the gelatinizer, but a problem has occurred that since the gel coating layer is made harder by doing so, the seed is difficult to germinate. Moreover, there has been a problem that in case of gel-coating a seed having a poor germinating ability, it is necessary to make the viscosity of the gelatinizer as low as possible in order to obtain a sufficiently high germinating ability, but in a double-cylinder nozzle method a spreadable viscosity of the thin film has the lower limit which has sometimes made a gel-coating process impossible. Furthermore, when above-mentioned gel-coated seed
9
a
is dropped due to its own weight into a lower hardening tank, a hardening agent spattered onto the lower end of above-mentioned nozzle block
1
has sometimes made a gel-coating process impossible.
Next, a mold method is a method which throws a seed into a mold whose inner face is spherical and at the same time fills the mold with a gelatinizer and a hardening agent, and takes out the gel-coated seed from the mold after it has been hardened. In this case, since this method does not use a stretched thin film of a gelatinizer to support a seed differently from above-mentioned double-cylinder nozzle method, it has an advantage that the gelatinizer does not need to be made higher in viscosity in order to enforce the seed supporting ability and its viscosity can be freely set to an adequate degree to provide a high efficiency of germination. However, there has been a problem that since a gelatinizer is difficult to be released from a mold, a seed cannot be coated in the shape of a sphere in some cases, and in the worst case a gel-coated seed cannot be released from the mold. Further, there has been a problem that this method is disadvantageous in work efficiency due to necessity of an operation of removing a hardening agent or a gelatinizer stuck to a mold each time a gel-coating process is performed.
DISCLOSURE OF THE INVENTION
The present invention provides a gel coating method obtained by improving above-mentioned mold method, which gel coating method injects a gelatinizer and an object to be sealed into a mold having both a gelatinizer impermeability or a slight gelatinizer impermeability and a hardening agent permeability, allows a hardening agent to permeate throughout the mold by immersing the mold in the hardening agent, and uniformly hardens the gelatinizer, which is around above-mentioned object to be sealed, from its contacting part with the mold, and thereby renders the object to be sealed easily removable as a gel-coated object from the mold. This method can securely coat with gel even a heavy object to be sealed or an object to be sealed having a poor germinating ability since it does not support an object to be sealed with a thin film of a gelatinizer. Moreover, since hardening of a gelatinizer proceeds in order from the contacting part with a mold, no unhardened gelatinizer is stuck to the inner face of the mold and the mold releasability of a gel-coated object is remarkably improved in comparison with a conventional mold method, and it is possible also to suppress remaining of a gelatinizer in a mold.
Moreover, since a thin hardened layer of a gelatinizer is formed beforehand at a contacting part between a gelatinizer and a mold by making above-mentioned mold retain the hardening agent through immersing the mold in the hardening agent and taking out the mold before injecting the gelatinizer and an object to be sealed into the mold, it is possible to further improve a gel-coated object in mold releasability.
The inner face of a mold used in above-mentioned method is composed of a semispherical portion projecting downward and a cylindrical portion set upright on the spherical portion, and the whole depth from the top end of the cylindrical portion to the bottom end of the semispherical portion is made equal to or greater than the diameter of above-mentioned semispherical portion, and therefore a gel-coated object can be surely made sphere-shaped.
Further, in case of using a mold having a slight gelatinizer impermeability as above-mentioned mold, since one that is composed such that it takes a time of one or more seconds for a gelatinizer to permeate through the mold, it is possible to completely prevent the gelatinizer injected into the mold from leaking out before immersing the mold in a hardening agent.
Moreover, it is acceptable also to use a mold made of an elastic material as above-mentioned mold, transform the mold by pressing its lower part from below, and extrude a gel-coated object

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