Method for molding capsules

• US 4,591,475 A
• Filed: 04/29/1983
• Issued: 05/27/1986
• Est. Priority Date: 03/26/1982
• Status: Expired due to Term

• Current Assignee: Warner-Lambert Company (Pfizer Inc.)
• Original Assignee: Warner-Lambert Company (Pfizer Inc.)
• Inventors: Tomka, Ivan, Wittwer, Fritz
• Primary Examiner(s): Anderson, Philip
• Application Number:
  US06/490,057
• Time in Patent Office: 1,124 Days
• Field of Search: 426/515, 426/576, 264/328.17, 264/328.14, 264/40.1, 264/40.4, 425/550, 425/551, 425/564, 425/568, 425/572, 424/37
• US Class Current: 264/328.14
• CPC Class Codes: A61J 3/07 into the form of capsules or similar small containers for oral use
• CPC Class Codes: B29C 45/00 Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor injection blow-moulding B29C49/06
• CPC Class Codes: B29C 45/231 Needle valve systems therefor
• CPC Class Codes: B29C 45/50 Axially movable screw
• CPC Class Codes: B29C 45/76 Measuring, controlling or regulating measuring in general G01; controlling or regulating in general G05
• CPC Class Codes: B29K 2089/00 Use of proteins, e.g. casein, gelatine or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2093/00 Use of natural resins, e.g. shellac, or derivatives thereof, as moulding material B29K2001/00, B29K2003/00, B29K2005/00, B29K2007/00 and B29K2089/00 take precedence
• CPC Class Codes: B29L 2031/7174 Capsules
• CPC Class Codes: C08B 30/12 Degraded, destructured or non-chemically modified starch , e.g. mechanically, enzymatically or by irradiation; Bleaching of starch preparation of chemical derivatives of starch C08B31/00

Abstract

A method of producing capsules of a moldable hydrophilic polymer composition, preferably gelatin, using a combination of an injection molding device with a microprocessor to precisely control the conditions of time, temperature, pressure and water content of the hydrophilic polymer composition, in a cyclic molding process.

Claims

1. The method of manufacturing a shaped product from a hydrophilic polymer and water mixture having no phase separation of the water from the hydrophilic polymer-water mixture at a water content of between about 5 and 25% by weight of the hydrophilic polymer and having a certain glass transition temperature range, comprising the steps of:

(a) mixing the polymer with water in a predetermined amount between about 5 and 25% by weight of the hydrophilic polymer;

(b) heating the hydrophilic polymer with said water while maintaining said predetermined water content to form a melt;

(c) further heating the hydrophilic polymer melt and water to a temperature to dissolve the melt in the water and achieve a homogeneous dispersion on a molecular level while maintaining said predetermined water content;

(d) injecting the dissolved hydrophilic polymer melt into a mold cavity while maintaining said predetermined water content;

(e) cooling the hydrophilic polymer melt in said mold to form a molded product at a temperature below the glass transition temperature range of the hydrophilic polymer while maintaining said predetermined water content; and

(f) ejecting the molded product of said hydrophilic polymer from said mold.

5. The method according to any one of claims 1-4 wherein:

(a) the predetermined water content is maintained at a value between 10 and 20% by weight of the hydrophilic polymer;

(b) the temperature of the hydrophilic polymer melt and water is raised to a value of between about 50° and

190°

C. during the heating thereof;

(c) the hydrophilic polymer melt and water is subjected during heating to a pressure of between about 600×

10⁵ and 3000×

10⁵ newtons per square meter; and

(d) the hydrophilic polymer melt is cooled in said mold to an ambient temperature of about 20°

C.

6. The method according to claim 5 wherein:

(a) the water content is maintained at a value between 12 and 18% by weight of the hydrophilic polymer; and

(b) the temperature of the hydrophilic polymer melt and water is raised to a value of between about 70° and

170°

C. during the heating thereof.

13. The method according to claim 6 including the step of:

(a) forming the shaped product into the shape of a capsule part in the injection mold cavity.

2. The method of manufacturing a shaped product from a hydrophilic polymer and water mixture having no phase separation of the water from the hydrophilic polymer-water mixture at a water content of between about 5 and 25% by weight of the hydrophilic polymer and having a certain glass transition temperature range, comprising the steps of:

(a) heating the hydrophilic polymer with water of a predetermined amount between about 5 and 25% by weight of the hydrophilic polymer to form a melt;

(b) maintaining said predetermined water content during said heating;

(c) further heating the hydrophilic polymer melt and water to a temperature to dissolve the melt in the water and achieve a homogeneous dispersion on a molecular level while maintaining said predetermined water content;

(d) injecting the dissolved hydrophilic polymer melt into a mold cavity while maintaining said predetermined water content;

(e) cooling the hydrophilic polymer melt in said mold to form a molded product at a temperature below the glass transition temperature range of the hydrophilic polymer while maintaining said predetermined water content; and

(f) ejecting the molded product of said hydrophilic polymer from said mold.

3. The method according to claim 2 wherein:

(a) the hydrophilic polymer melt is cooled in said mold to ambient temperature; and

(b) the predetermined water content is maintained at a value which is correlated with the temperature of the hydrophilic polymer melt whereby the glass transition temperature range of said hydrophilic polymer is above ambient temperature when the hydrophilic polymer melt contains said value of water content.

4. The method according to claim 3 wherein:

(a) the predetermined water content is maintained at the temperature to which the hydrophilic polymer is heated by subjecting the hydrophilic polymer melt and water to sufficient pressure to prevent evaporation of said water.

7. The method of manufacturing a shaped product from a gelatin and water mixture having no phase separation of the water from the gelatin-water mixture at a water content of between about 5 and 25% by weight of the gelatin and having a certain glass transition temperature range comprising the steps of:

(a) feeding the gelatin with a predetermined amount of water of between about 5 and 25% by weight of the gelatin into the input end of an extruder;

(b) heating the gelatin while maintaining said predetermined water content to form a melt;

(c) further heating the gelatin melt and water as it moves toward the exit end of the extruder to a temperature above the glass transition temperature range of the gelatin to dissolve the gelatin melt in the water and achieve a homogeneous dispersion on a molecular level while maintaining said predetermined water content;

(d) injecting the dissolved gelatin melt directly into the cavity of an injection mold while maintaining said predetermined water content;

(e) cooling the gelatin melt in said mold to form a molded product at a temperature below the glass transition temperature range of the gelatin while maintaining said predetermined water content; and

(f) ejecting the molded product of said gelatin from said mold.

8. The method according to claim 7 wherein:

(a) the gelatin melt is cooled in said mold to ambient temperature; and

(b) the predetermined water content is maintained at a value which is correlated with the temperature of the gelatin melt whereby the glass transition temperature range of said gelatin-water mixture is above ambient temperature when the gelatin melt contains said value of water content.

9. The method according to claim 8 wherein:

(a) the gelatin melt is cooled in said mold to an ambient temperature of about 20°

C.; and

(b) the predetermined water content is maintained at a value between 12 and 18% by weight of the gelatin.

10. The method according to any one of claims 7-9 wherein:

(a) the predetermined water content is maintained at the temperature to which the gelatin melt is heated by subjecting the gelatin and water to sufficient pressure to prevent evaporation of said water.

11. The method according to claim 10 wherein:

(a) the temperature of the gelatin melt and water is raised to a temperature of between about 50° and

190°

C. during the heating thereof.

12. The method according to claim 11 wherein:

(a) the gelatin melt and water is maintained at a pressure of between about 600×

10⁵ and 3000×

10⁵ newtons per square meter.

14. The method according to claim 9 further comprising the step of:

(a) mixing one or more plasticizers with the gelatin-water mixture, said plasticizers being selected from polyethylene glycol and low-molecular-weight organic plasticizers including glycerol, sorbitol, dioctylsodium sulfosuccinate, triethyl citrate, tributyl citrate, 1,2 propyleneglycol and mono-, di- and tri-acetates of glycerol, in an amount in the range from 0.5 to 10% based upon the weight of the hydrophilic polymer.

15. The method according to claim 12 including the step of:

(a) forming the shaped product into the shape of a capsule part in the injection mold cavity.

16. The method of manufacturing a shaped product from a hydrophilic polymer and water mixture having no phase separation of the water from the hydrophilic polymer-water mixture at a water content of between about 5 and 25% by weight of the hydrophilic polymer and having a certain glass transition temperature range, comprising the steps of:

(a) mixing the polymer with water in a predetermined amount between about 5 and 25% by weight of the hydrophilic polymer;

(b) heating the hydrophilic polymer in said water while maintaining the water content between said 5 and 25% to form a melt;

(c) further heating the hydrophilic polymer melt and water to a temperature to dissolve the melt in the water and achieve a homogeneous dispersion on a molecular level while maintaining the water content between said 5 and 25%;

(d) injecting the dissolved hydrophilic polymer melt into a mold cavity while maintaining the water content between said 5 and 25%;

(e) cooling the hydrophilic polymer melt in said mold to form a molded product at a temperature below the glass transition temperature range of the hydrophilic polymer while maintaining the water content between said 5 and 25%; and

(f) ejecting the molded product of said hydrophilic polymer from said mold.