Seamless Capsule Shell Composition Using PVA Copolymer
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Solution Overview
Problem
Seamless capsules face issues with uniform shell thickness and the occurrence of 'eyes' (droplets) due to chemical bonding between gelatin and aldehyde-containing materials, leading to delayed content release and insolubilization.
Innovation Solution
A shell composition comprising agar and a specific polyvinyl alcohol copolymer, including polyvinyl alcohol, unsaturated carboxylic acids, and unsaturated carboxylic acid esters, with optional plasticizers like glycerol and sorbitol, is used to create seamless capsules with uniform thickness and prevent 'eyes' through an in-liquid dropping method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gelatin is used as a shell forming material, then the capsule has excellent solubility and rapid disintegration, but the amino group of gelatin chemically bonds to aldehyde groups in the content causing discoloration and insolubilization
Solution Approach 1:
The patent changes the chemical composition parameters of the shell material by replacing gelatin with a specific copolymer containing carboxyl groups, which fundamentally alters the chemical interaction properties with aldehyde-containing materials while maintaining the desired solubility and disintegration characteristics
Solution Approach 2:
The patent uses a composite copolymer material comprising polyvinyl alcohol, unsaturated carboxylic acid, and unsaturated carboxylic acid ester in specific ratios to achieve both solubility and resistance to chemical bonding with aldehyde groups, combining multiple material properties in a single shell formulation
2Manufacturing precision
If an interface tension adjusting agent and gelling accelerator are mixed in the shell composition, then the quality of the capsule is improved by suppressing eyes and thickness deviation, but the manufacturing process complexity increases
Solution Approach 1:
The patent combines the functions of interface tension adjustment and gelling acceleration into a single copolymer material that inherently provides both properties through its specific chemical structure and composition, eliminating the need for separate additive systems
Solution Approach 2:
The copolymer shell material serves multiple functions simultaneously: it acts as the structural base material, provides interface tension control, enables proper gelling behavior, and prevents chemical bonding with content, replacing multiple separate functional components
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution results in high-quality seamless capsules with excellent uniformity of shell thickness and virtually no 'eyes', enhancing their usability in pharmaceuticals, foods, and cosmetics by preventing chemical bonding and ensuring timely content release.
Implementation Method 1
the amino group of gelatin is chemically bonded to the aldehyde group in the content during storage to cause discoloration or insolubilization of the shell
Implementation Method 2
a seamless capsule is one type of soft capsules, which is manufactured by utilizing a tension occurring in the oil-water interface and gelling properties of a shell base material
Implementation Method 3
use of a PVA copolymer as a film coating agent of tablets or granules has been reported
Data Source
AI summary
The present invention addresses a problem of providing a high quality seamless capsule, with excellent uniformity of shell thickness and virtually no eyes in the shell. The problem can be solved by manufacturing a seamless capsule using a shell composition comprising at least one polysaccharide selected from the group consisting of agar, carrageenan and gellan gum, and a PVA copolymer comprising the following structural units: (i) polyvinyl alcohol, (ii) at least one unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid and maleic acid, and (iii) at least one unsaturated carboxylic acid ester selected from the group consisting of compounds represented by formula [I]: H2C=C(R1)-COOR2 [I] (wherein R1 represents a hydrogen atom or a methyl group, and R2 represents an alkyl group having 1 to 4 carbon atoms).