JPS62204884A - Film coating method - Google Patents

Abstract

PURPOSE:To attain the shortening of a coating work time and the lowering in drying temp., by coating a solid substance by a two-step process wherein a low viscosity gel dispersion of a water-soluble polymer is applied at first and water and/or an org. solvent or a polymer solution is subsequently applied before drying. CONSTITUTION:In applying coating for moistureproofing, deodorizing and elution control to a drug, cosmetics and feed, etc., the surface of a solid substance is coated with a low viscosity dispersion of a water-soluble polymer such as a hydroxyalkyl derivative of cellulose in a first process. The surface of the dried coating is coated with water and/or a solution of an org. solvent such as ethanol or methylene chloride or a polymer such as a cellulose derivative or PVA in a second process and the coating layer is dried. As a result, rapid low temp. drying can be performed because the hydration of the gel dispersion of the water-soluble polymer in the first process is lost and surface smoothness is enhanced because the film in the first process can be wetted in the second process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for film coating a solid material using a water-soluble polymer, and more particularly, to a method for film coating a solid material using a low-viscosity gel dispersion of a water-soluble polymer. The present invention relates to a water-based film coating method.

The film coating method for solid materials of the present invention includes pharmaceuticals,
It can be used for film coating of solid agents in fields such as cosmetics, food, feed, and agricultural chemicals.

[Conventional technology]

Until now, solid preparations for pharmaceuticals, cosmetics, foods, feeds, agricultural chemicals, and the like have been coated with various films using Th polymers for the purposes of moisture proofing, deodorizing, preventing changes over time, and controlling elution.

As a film coating method using a -C polymeric substance, a coating liquid prepared using a solvent has been used to improve workability by increasing drying properties and shortening coating time.

However, in recent years, coating methods using water as a solvent have been actively researched due to problems such as pollution, toxicity of residual solvents, and handling of hazardous materials.

When water is used as a solvent for a coating liquid, its drying properties are poor compared to organic solvents, and the formed coating film is sticky, so various additives are used to improve these problems.

For example, in the pharmaceutical field, there is a method using a coating liquid (dispersion) prepared by emulsifying and dispersing higher fatty acids or their metal salts and waxes in an aqueous solution (hydrosol) of a water-soluble film coating base. 26
It is disclosed in Publication No. 125.

Also, water-soluble polymer water? @I! 1. A method using a coating liquid (dispersion liquid) obtained by mechanically dispersing oil by adding oil to a hydrosol) is described in Japanese Patent Application Laid-Open No. 1985-851), in which an aqueous solution containing liquid paraffin, silicone, vegetable oil, etc. A method for preparing and using a dispersion liquid is described in JP-A-58-1.
It is disclosed in Japanese Patent No. 71451.

[Problem that the invention seeks to solve]

Film coating methods that use water as the coating solution solvent are safe if pollution, toxicity, flammability, etc. Compared to hydrogen-based solvents, it has a high boiling point and poor drying properties for coating films, so solid substances tend to stick together during coating operations.

Therefore, in the conventional technology, it is necessary to perform coating by slowing down the supply speed of the coating liquid or increasing the drying temperature, so the coating operation takes a long time and requires a large amount of drying energy. There are several issues.

An object of the present invention is to provide an aqueous film coating method that enables shortening of coating operation time and lowering of drying temperature, and improves the smoothness of the coating film.

[Means for solving problems]

In the present invention, the surface of a solid substance is coated with a low-viscosity gel dispersion of a water-soluble polymer and dried (hereinafter referred to as the "first step").
This method of film coating a solid material is characterized in that the coated surface is then further coated with water and/or a solvent or polymeric substance solution, and dried (hereinafter referred to as "second step").

The low-viscosity gel dispersion of water-soluble polymer (hereinafter simply referred to as "gel dispersion") used in the first step of the present invention is a hydrosol of water-soluble polymer (hereinafter simply referred to as "hydrosol"). It is produced by heating and/or adding a gelling agent, such as a water-soluble electrolyte or a water-soluble polysaccharide, to the hydrosol. The water-soluble polymer used here is not particularly limited as long as it reduces the viscosity when the hydrosol is gelled by the above method. Hydroxyalkyl derivatives of cellulose can be preferably used as water-soluble polymers from which a uniform gel dispersion can be prepared relatively easily, and more preferably hydroxypropyl cellulose (hereinafter referred to as rHPCJ), hydroxypropyl hydroxybutyl cellulose (Hereinafter, rHPHBCJ
It is written as ) etc. are used.

In addition, for the purpose of improving the drying properties and strength of coating films, common film coating bases such as methylcellulose (hereinafter referred to as rMCJ) and hydroxypropyl methylcellulose (hereinafter referred to as rHPMCJ) are used.
Hydroxypropyl methyl cellulose phthalate (I
IPMCP), shellac, cellulose acetate phthalate (CAP), ethyl cellulose nyl alcohol (PVA), polyvinyl acetal diethylamino acetate (^EA), carboxymethyl ethyl cellulose (CMEC), etc. are mixed within a range that does not significantly increase the viscosity of the gel dispersion. can be used.

The gel dispersion is prepared in a concentration range such that the viscosity of the gel dispersion is 1,000 cp or less, preferably 250 cp or less. If the viscosity of the gel dispersion is too high, the drying properties of the coating film will decrease and the surface tackiness will increase; however, when coating by spraying,
The delivery of the gel dispersion liquid becomes irregular, the spray droplets become non-uniform, and the workability of coating deteriorates significantly.

The low viscosity gel dispersion is prepared by: (1) a method of heating a hydrosol to a temperature higher than its gelling temperature;

(2) A method of adding a water-soluble electrolyte to a hydrosol.

(3) A method of adding a water-soluble multi-Ti compound to a hydrosol.

However, if there is a limit on the gelation temperature or the amount of electrolyte or polysaccharide added, by using these methods in combination as appropriate, a gel dispersion with a viscosity below the limit value can be produced. can be manufactured. In the case of HPC, which is a typical example of water-soluble polymer, the hydrosol is heated at 35°C.
By heating above, a gel dispersion with a viscosity below the limit value can be obtained, but under various practical conditions, e.g.
Moisture evaporation rate, stability of coating chemicals, etc.
Considering the smoothness of the coating film, etc., 50
It is preferable to heat the gel to a temperature in the range of 90°C to 90°C. Depending on the type of water-soluble polymer, the resulting gel dispersion may be
The dispersion state of the gel may become unstable, such as the gel not dispersing uniformly and separating, or the gel particle size becoming non-uniform, so separate the gel by adding a surfactant, stirring at low speed, stirring at high speed, etc. Prevention and uniform dispersion of gel can be measured.

Depending on the practical purpose, additives such as a plasticizer to impart flexibility to the coating film, a pigment for coloring, and other inorganic fillers may be added to the gel dispersion obtained by the above method. Can be added. Also, the evaporation rate of the gel dispersion (drying rate of the coating film)
In order to speed up the process, an organic solvent may be added to the hydrosol in advance to the extent that it does not inhibit gel formation of the water-soluble polymer.

On the other hand, the organic solvent used in the second step is not particularly limited as long as it dissolves or swells the water-soluble polymer used in the first step, and includes alcohols such as methanol and ethanol, and methylene chloride. Chlorinated solvents and the like can be preferably used, and ethanol is more preferably used. In addition, there are no particular restrictions on the polymeric substance used in the second step, as long as it swells or is compatible with the known polymeric substance used for film formation or the water-soluble polymer used in the first step. For example, cellulose derivatives, shellac, PVP, PVA, AEA, sugars, polysaccharides, plasticizers, waxes, etc. can be used, and these polymeric substances can be used alone or in combination with water and/or 4! ! ? 1
) is used by dissolving or dispersing it in an agent.

In the first step and the second step, the best method for coating the solid substance with the coating liquid is a spray method, but a dropping method, a dipping method, etc. may also be used. Moreover, various nozzles such as an -iA body nozzle and a two-fluid nozzle can be used in the spray method.

The coating film coated on the solid substance can be dried by ventilation drying, natural drying, etc., and there are no particular restrictions on the drying method. As long as the drying temperature is higher than room temperature, it can be up to a temperature limited by the solid matter to be coated, additives, etc., but it is preferably in the range of room temperature to 70°C, and when RPC is used, it is 40 to 70°C. A temperature range of 60°C is preferably employed.

The gel dispersion coating (2) in the first step is appropriately selected depending on the purpose of coating, the type and concentration of the gel dispersion used, and the like. On the other hand, the amount of coating in the second step may be minimal since the purpose is to improve the smoothness of the film surface.

Solid objects to be coated are not particularly limited, but tablets, pills, and granules that are used in the fields of medicine, cosmetics, food, agricultural chemicals, feed, etc., due to the price, properties, and purpose of coating of water-soluble polymers. tablet, granules, flakes, etc., and there are no particular restrictions on shape or size.

[Effect]

As a result of intensive research into improving the workability of water-based film coating, the present inventors found that water-soluble polymers, such as bitroxyalkyl derivatives of cellulose, have hydroxyalkyl groups that facilitate hydration and dissolve in water. However, due to the gelation of the hydrosol, the hydration is disrupted, and the hydroxyalkyl derivative of cellulose precipitates to form a gel, which lowers the viscosity and forms a gel dispersion, so it is used as a coating liquid. In this case, the present invention was completed by noting that the solid content concentration in the gel dispersion can be increased and the coating time for forming a coating film of a predetermined thickness can be shortened.

In the present invention, in the first step, the gel dispersion of the water-soluble polymer has already lost its hydration, so the drying speed after being coated on the solid material is reduced by the water-soluble polymer simply dissolving in water. Compared to the hydrosol coating film in the state where it is applied, it is significantly faster and the tackiness of the coating film is also lower.

Therefore, immediately using low temperature drying air,
It can be dried, and as a result, it is possible to prevent the films from sticking together.

In the second step, the water-soluble polymer film obtained in the first step is coated with a small amount of water and/or a solution of an organic solvent or polymer substance that swells or is compatible with the film, thereby improving the surface of the film on the solid agent. Improves smoothness.

〔Example〕

The present invention will be explained in more detail by way of examples.

However, the scope of the present invention is not limited to the same extent by the following examples.

(1) Preparation of coating liquid Using the following water-soluble polymer, water and/or organic solvent, prepare a low-viscosity gel dispersion for the first step and a coating liquid for the second step having the composition and viscosity shown in Table 1. Prepared.

HPC: Hydroxypropoxyl group molar substitution degree 3.3 (
Nippon Soda side type product name 1 (PC-SL) HPHBC: Hydroxypropoxyl group molar substitution degree 3.3 Hydroxybutoxyl group molar substitution degree 0.36 (manufactured by Nippon Soda ■) HPMC: Hydroxypropoxyl group molar substitution degree 0.2
4 Molar substitution degree of methoxy group 1.87 (trade name, TC-5E, manufactured by Shin-Etsu Chemical Al) PVA:
Saponification degree 86.5-89.0-E/L/% 4% aqueous solution viscosity 30 cps (@20°C) (Nippon Gosei Kagaku Kogyo ■ type open product name: Gohsenol (EG-30)) (2) Film coating of tablets 300 g of lens-shaped tablets with a diameter of 8 mm were placed in a vented coating pan with a 0.7 mm diameter two-fluid nozzle for tablets (manufactured by Freund Sangyo ■), and the pan rotation speed was 36 rpm, the drying air supply rate was 800 It/min, and the temperature inside the pan was adjusted. In the first step, a predetermined amount of the gel dispersion shown in Table 1 was applied under the conditions of 45 to 55°C, and then in the second step, a predetermined amount of the coating solution shown in Table 1 was applied under the same conditions as above. It was coated on a film formed in one step.

The amount of coating in the first step and the second step was adjusted so that the final coverage was in the range of 4 to 5%.

Table 1 shows the results of scanning electron microscope observation of the coating time, coverage, and surface smoothness of the coating film formed on the tablet under the above coating conditions.

〔Effect of the invention〕

In the first step of the present invention, by using a low viscosity gel dispersion obtained by gelling a hydrosol of a water-soluble polymer as the coating liquid, the solid content of the coating liquid is as shown in Table 1 above. The concentration can be increased significantly and the drying properties of the coating film are improved. As a result, compared to the conventional method using a water-soluble polymer hydrosol coating liquid, it is possible to shorten the coating time and lower the drying air temperature, and also prevent coating films from sticking together.

Furthermore, in the second step, the surface of the coating film formed in the first step is swollen or dissolved to obtain a coating film with a smooth surface.

The present invention provides a film coating method capable of forming a coating film with a smooth surface and improved thermal energy consumption and workability, and has extremely great industrial significance.

Claims (5)

[Claims] (1) A solid substance is coated with a low-viscosity gel dispersion of a water-soluble polymer and dried, and then the coated surface is further coated with water and/or an organic solvent or a polymer substance solution and dried. A film coating method for solid materials. (2) The solid film according to claim (1), wherein the low-viscosity gel dispersion of the water-soluble polymer is a gel dispersion obtained by gelling a hydrosol of hydroxypropyl cellulose or hydroxypropyl hydroxybutyl cellulose. Coating method. (3) A solid product according to claim (1) or (2), which is produced by heating a hydrosol of a water-soluble polymer to gel a low-viscosity gel dispersion of a water-soluble polymer. film coating method. (4) The method for film coating a solid material according to claim (1), wherein the organic solvent is an alcohol or a chlorinated solvent. (5) The polymer substance solution is cellulose derivative, shellac,
Claim No. 1, which is a solution of polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetal diethylaminoacetate, sugars, polysaccharides, plasticizers and/or waxes in water and/or an organic solvent.
) A film coating method for solid materials as described in section 2.