Multilayer Resin Preform Blow Molding for Stable Color Gradation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for manufacturing resin containers with gradation patterns face challenges in precise control of layer thickness and pattern reproduction, particularly in hot parison blow-molding, leading to instability in forming desired color patterns.
Innovation Solution
A manufacturing method involving two-stage injection molding to create multilayer preforms, where a first layer is formed with a specific resin material, followed by a second layer with a different color, and blow-molding is performed while residual heat is maintained, allowing for precise control of thickness distribution and color gradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If coextrusion is used to form multilayer preform with gradation pattern, then color pattern can be formed in resin container, but it is very difficult to precisely control change in thickness in each layer and some patterns fail to be reproduced
Solution Approach 1:
The preform is divided into multiple layers with different resin materials, where each layer can be independently controlled for thickness and color. This segmentation allows precise control of thickness distribution in each layer to achieve desired gradation patterns, while the modular layer structure simplifies the manufacturing process compared to attempting to create complex patterns in a single layer through coextrusion.
2Strength
If pieces are not sufficiently cooled down to have certain degree of hardness, then two pieces fail to be fitted into each other to form preform, but cooling and reheating steps increase production time
Solution Approach 1:
The injection molding and cooling processes are merged into a single continuous operation where the preform is molded and cooled within the mold before being directly transferred to the blow-molding stage. This eliminates separate cooling and reheating steps, reducing production time while ensuring the preform achieves sufficient hardness for handling and assembly.
Solution Approach 2:
The manufacturing process maintains continuous useful action by immediately transferring the preform from injection molding to blow-molding without intermediate cooling or reheating steps. The residual heat from injection molding is utilized for the blow-molding process, ensuring continuous production flow and maximizing productivity while maintaining necessary material properties.
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
This method enables stable formation of desired color patterns in resin containers, enhancing aesthetic appeal and reducing production time by avoiding cooling and reheating steps, thus improving manufacturing efficiency.
Implementation Method 1
a first injection molding process for injection-molding a first layer of a preform having a bottomed cylindrical shape by using a first resin material
Implementation Method 2
a second injection molding process for injecting a second resin material having a color that is different from a color of the first resin material, and laminating a second layer on an outer peripheral side or an inner peripheral side of the first layer
Implementation Method 3
a blow-molding process for blow-molding a preform that includes multiple layers and has been obtained in the second injection molding process in a state where residual heat at a time of injection molding is contained
Data Source
AI summary
A manufacturing method of a resin container includes: a first injection molding process for injection-molding a first layer of a preform having a bottomed cylindrical shape by using a first resin material; a second injection molding process for injecting a second resin material having a color that is different from a color of the first resin material, and laminating a second layer on an outer peripheral side or an inner peripheral side of the first layer; and a blow-molding process for blow-molding a preform that includes multiple layers and has been obtained in the second injection molding process in a state where residual heat at a time of injection molding is contained, and manufacturing the resin container having a color pattern that corresponds to a thickness distribution of the first layer and the second layer.