DE1158481B - Process for coating particles with a coating material in a fluidized bed - Google Patents

Description

The invention relates to a method for coating particles, such as. B. tablets and the like., With a coating material in a fluidized bed to achieve a uniform coating on the Particles.

It is known to produce tablets in an over a sieve by a single stream of a gas To provide fluidized bed with coatings, the particles in the fluidized bed, however, a turbulent or indiscriminate movement is given without ensuring a controlled cyclic flow movement. In another method of bringing solids into contact with liquids and gases If a pipe in the bottom of a tower enters air through a heaped up layer of solid particles only in the form of a single jet at a single speed and sweeps upwards, with for Achieving the desired flow effect the line for the inlet of the air is relatively small in comparison to the diameter of the reactor.

It has also been proposed to use the coating material in atomized or similar form to add the solid particles in suspension gas stream, such as air (German patent application W 27750 IVa / 30 h).

According to the invention, when particles are being coated in a fluidized bed, two gas streams are generated different speeds are used, with a gas stream sweeping through a coarse-meshed sieve at a higher speed and the gas flow passing through a fine-meshed sieve at a lower speed Speed comes into play. So there is a stronger air flow to a part of the fluidized bed fed for whirling up than the other part, causing the good a rotating movement is given within the fluidized bed, the dissolved or suspended in a liquid medium Coating material is atomized in the stronger air stream before entering the fluidized bed.

This results in a regulated cyclical flow movement in a treatment tower while achieving a ensures a uniform coating layer. By varying the gas velocities it is achieved that the particles are lifted without touching each other until the coating is practically dry then move downwards in the other part of the tower and towards the high-speed tower part to return.

In this way of working, a uniform coating is created with the formation of a smooth surface a large range of particles that are prevented from agglomerating. This also avoids

with a coating material

in a fluidized bed

Applicant:

Wisconsin Alumni Research Foundation,
Madison, Wis. (V. St. A.)

Representative; Dr.-Ing. H. Ruschke, patent attorney,
Berlin 33, Auguste-Viktoria-Str. 65

Claimed priority:

V. St. v. America of November 9 and December 21, 1959 (No. 851 498 and No. 861 063)

Dale Erwin Wurster, Madison, Wis. (V. St. A.),
has been named as the inventor

possible smearing or abrasion of the load.

A random particle movement that occurs in fluidized beds does not guarantee a proper one Coating of large particles or tablets, just as little is uniform drying achieved.

The figures are intended to explain the invention in more detail.

Fig. 1 shows a cross section of the lower portion of the device,

Fig. 2 is a cross section (2-2 of Fig. 1) and - ^

FIG. 3 shows an alternative arrangement of the grid shown in FIG.

The device includes (Fig. 1) a tower 10, a line for air supply and a line for Feeding the coating material. The vertical tower 10 is made of a rigid, hard material, such as B. steel or aluminum, or a clear synthetic resin or a similar material constructed. At its lower end, the tower 10 comprises a frustoconical end section 12. Section 12 is followed by a longitudinally stretched one Nozzle section 14, which merges into a pipe part 16 and 26, supplied through the air will. A grid 18 in the form of a pair of sieves 20 and 22 is arranged in the upper end of the nozzle section 14.

309 767/394

3 4

arranges. The sieves can on a frame part 24 z. B. aqueous sugar solutions or non-aqueous Löbefestigt be. sings, such as B. film-forming solutions in one

Alternatively (FIG. 3) the grid 18 without the organic solvents and the like in the middle of a continuous support 24 can be designed, _R. -I ₁

that the Grobmaschensieb20 'the entire opening 5 example ι

covered and the fine-meshed sieve 22 'on the polyethylene glycol 6000 70 g

The fine-meshed cellulose acetate phthalate 30 g

Sieve 22 covers only part of the opening. That , ,

Sieve 22 'can e.g. B. form a semicircle. The sieve of powdered cane sugar 800 g

20 is relatively coarse-meshed (e.g. mesh size for acetone 900 ecm

2.0 mm) and is directly above the nozzle 30. Ethanol 900 ecm

arranges. The sieve 22 is fine-meshed and preferably consists of several layer sections after the film-forming substances have dissolved Sieve material, e.g. B. with an opening of 0.074 mm. (Polyethylene glycol and cellulose ester) in the orga-Das Fine-meshed sieve 22 offers the air flow 15 niche solvents (acetone-ethanol mixture) considerably greater resistance, so that the over-cane sugar is used as an inert bulking agent The majority of the solution incorporated into the feed line 26 with stirring until a If air is diverted to the coarse mesh side, stable suspension is added. This slurry and here in the tower 10 with greater speed it is then ready for use in the one above occurrence. 20 described working procedures.

The upper section of tower 10 can be equipped with a. . ₁

Separation device of known design example l

be seen. The air supplied can be 70 g in known polyvinyl alcohol

Way regulated in their moisture content and- ethyl cellulose 30 g

get heated. 25 _. _n ' . _nn

The cane sugar dissolved in a volatile liquid and / powdered cane sugar 400 g

or dispersed coating materials are under isopropyl alcohol 500 ecm

suitable pressure through tube 28 of an atomizer chloroform 500 ecm

30 passed into the lower end of the nozzle section 14. This system includes a further one in the 30 The materials are processed as in Example 1 using an atomizer 30 extending tube 32 for compressed. This composition can be like that of mated air. The nebulizer is off-center in example 1 also, by adding pharmaceutical Section 14 and is located under the colorant, water soluble waxes, plasticizing grid section with the larger passages. means etc. can be modified.

The feed item of 35 that is brought into the tower 10.

to be coated particles, such as. B. tablets, example 3

retained on the grid 18. Through the inlet fertilizer-urea pellets were in a gas nozzle 26 is gas, e.g. As warm air, is introduced, men air flow kept in suspension and whose speed is controlled so with that the thin wax coating suspensions as a very finely atomized LOE-feed section 12 as a fluidized bed solution _4Q, 80 g of paraffin wax diert per 1000 cc of chloroform will. The tablets contained T with a diameter, coated. The coating solution was moved in, for example, 9.5 mm at a rate of 600 cc / min. at a relatively rapid air inlet speed, for example 0.609m per temperature of 46 ° C and an outlet temperature of about 27 ° C in the ascending branch of the fluidized bed. The covered urinals. 45 material pellets ensure the slow release of the

Once the desired coating thickness has been reached, nitrogen is added to the soil, feeding of coating materials into the nozzle

section 14 ended. The supporting air flow becomes Example 4

graduated, the bed collapses on the lattice, Small glass spheres were in a warm

and the coated tablets are kept in suspension from the pre-50 (57 ° C) air stream and with direction removed by known methods. a resin polymer of monochlorotrifluoroethylene

One can use different means of varying and covering. The resin was made as a finely atomized Lö-rules the speed of the carrying gas stream solution, which contained 100 g resin per 2000 ecm acetone, apply to a cyclical flow pattern of the attached. The coated beads are used wrote. Kind of achieve. So z. B. 55 in the manufacture of reflective tapes. Also given lead powder Grating by conventional slider ver can be coated with the resin in a similar manner or similar sliding plates for regulation.

of the gas flow or used in combination Example 5

will. One can also have the air supply in several

Gas flows at different speeds 60 freshly roasted peanuts were carried out in one ward, in order to emulate the cyclical flow pattern, the air flow is suspended and with a thin are sufficient. The sieves described, coated with zein, are preferably used. The coating was called possibly with the modification that the finely atomized solution, the * 100 g zein in 1000 ecm Section of the sieve immediately above the nozzle 30 had dissolved isopropyl alcohol containing 10% water completely absent and the nozzle contained the same amount as 65 and 20 g sorbitan monolaurate, attached, the sieve or higher. The coating was applied in an amount of 100 ecm /

The minutes used for coating in this process with one supply air at 3 ° C and one outlet Materials can be conventional, such as air applied at 29 ° C. The coated peanuts

turned out to be very durable without developing a rancid taste.

Claims (1)

PATENT CLAIM: A method for coating particles with a coating material in a fluidized bed, characterized in that a stronger air flow is fed to one part of the fluidized bed for fluidization than the other part, whereby the material is given a rotating movement within the fluidized bed, this being in a liquid medium dissolved or suspended coating material is atomized in a stronger air stream before entering the fluidized bed. Considered publications:
U.S. Patent Nos. 2799 241, 2786 280. 1 sheet of drawings