Preform Inner Surface Coating for Liquid Blow Molding Transparency
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Solution Overview
Problem
Liquid blow molding of polyester preforms using surfactant-containing or alcohol-containing liquids results in fine unevenness and cloudiness on the inner surface of containers, degrading transparency.
Innovation Solution
A method involving coating the inner surface of the preform with a polyvinyl butyral or polyvinylidene chloride layer having elongation capacity and water insolubility, which protects the surface during liquid blow molding, maintaining transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid blow molding is performed using surfactant-containing or alcohol-containing liquid as pressurized medium, then the production process is simplified and productivity is improved, but fine unevenness and cloudiness occur on the inner surface of the container, degrading transparency
Solution Approach 1:
A coating layer made of polyvinyl butyral or polyvinylidene chloride is applied to the inner surface of the preform as an intermediary barrier. This coating layer prevents direct contact between the polyester preform and the surfactant-containing or alcohol-containing pressurized liquid, thereby preventing fine unevenness and cloudiness while allowing the liquid blow molding process to proceed efficiently
Solution Approach 2:
The preform is constructed with a composite structure consisting of a polyester base material and a coating layer of polyvinyl butyral or polyvinylidene chloride. This composite material approach combines the advantages of polyester (transparency, mechanical properties) with the protective properties of the coating layer (resistance to surfactants and alcohols), resolving the contradiction between productivity and surface quality
2Manufacturing precision
If a coating layer is applied to the inner surface of the preform to protect against surfactant or alcohol, then transparency is maintained, but the device complexity and manufacturing steps increase
Solution Approach 1:
The coating layer materials (polyvinyl butyral or polyvinylidene chloride) are selected based on their specific physical and chemical parameters - particularly their insolubility in surfactant-containing and alcohol-containing liquids, and their elongation capacity. By changing the material parameters rather than the process complexity, transparency is maintained with a relatively simple coating application process
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 coating layer prevents the surfactant or alcohol from affecting the inner surface, ensuring the container's transparency is maintained after molding by stretching with the preform and remaining insoluble in the liquid.
Implementation Method 1
the coating layer having elongation capacity
Implementation Method 2
water insolubility
Data Source
Figure 1
Figure 2
AI summary
By coating an inner surface of a preform (PF), in which at least an inner surface is made of polyester and which has transparency, with a coating layer (S), which has elongation capacity and water insolubility, the inner surface of the preform (PF) is protected against a pressurized liquid (L) by the coating layer (S) when the pressurized liquid (L) is supplied to the preform (PF), and occurrence of cloudiness on an inner surface of a container (C) after molding is prevented even in a case where a liquid having properties of eroding polyester and causing cloudiness on a polyester surface is used as the pressurized liquid (L) during liquid blow molding.