Resin Container Preform Strength Distribution for Inconspicuous Shrinkage
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Solution Overview
Problem
Existing resin containers with shrinkage-inducing structures are conspicuous, affecting their aesthetic appearance, especially when transparent.
Innovation Solution
A method for manufacturing a resin container with a two-layer structure, where the outer layer is made of a high-melting-point resin and the inner layer is made of a lower-melting-point resin, featuring air introducing holes and high-strength portions to allow controlled shrinkage without visibility of the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shrinkage inducing structure is formed in the container by conventional blow molding methods, then the container can shrink in proportion to discharge of contents, but the shrinkage inducing structure part becomes conspicuous and affects the aesthetic appearance
Solution Approach 1:
The patent applies local quality by creating a thickness distribution where only specific circumferential portions of the container have thinner wall sections that can shrink, while other portions maintain normal thickness for structural integrity and aesthetic appearance. This allows the shrinkage function to be localized to specific areas rather than requiring visible structures throughout the entire container.
Solution Approach 2:
The patent transitions from two-dimensional surface structures (protrusions and recesses on the container surface) to a three-dimensional thickness variation approach. By controlling the wall thickness distribution in the circumferential direction, the invention achieves shrinkage functionality without visible surface structures, effectively moving the structural feature from the surface dimension to the depth dimension of the container wall.
2Shape
If the container is made transparent to enhance aesthetic appearance, then the shrinkage inducing structure part becomes more visible and conspicuous
Solution Approach 1:
The patent applies local quality by creating a thickness distribution where only specific circumferential portions of the container have thinner wall sections that can shrink, while other portions maintain normal thickness for structural integrity and aesthetic appearance. This allows the shrinkage function to be localized to specific areas rather than requiring visible structures throughout the entire container.
Solution Approach 2:
The patent transitions from two-dimensional surface structures (protrusions and recesses on the container surface) to a three-dimensional thickness variation approach. By controlling the wall thickness distribution in the circumferential direction, the invention achieves shrinkage functionality without visible surface structures, effectively moving the structural feature from the surface dimension to the depth dimension of the container wall.
3Reliability
If a thickness distribution is created in the preform to induce shrinkage, then the container can shrink regularly, but the structure for inducing shrinkage becomes conspicuous
Solution Approach 1:
The patent applies local quality by creating a thickness distribution where only specific circumferential portions of the container have thinner wall sections that can shrink, while other portions maintain normal thickness for structural integrity and aesthetic appearance. This allows the shrinkage function to be localized to specific areas rather than requiring visible structures throughout the entire container.
Solution Approach 2:
The patent transitions from two-dimensional surface structures (protrusions and recesses on the container surface) to a three-dimensional thickness variation approach. By controlling the wall thickness distribution in the circumferential direction, the invention achieves shrinkage functionality without visible surface structures, effectively moving the structural feature from the surface dimension to the depth dimension of the container wall.
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 shrinkage-inducing structure is made inconspicuous, maintaining the container's aesthetic appeal while allowing controlled shrinkage in response to content discharge.
Implementation Method 1
a resin container that shrinks in proportion to discharge of contents
Implementation Method 2
outer layer is made of a high-melting-point resin and the inner layer is made of a lower-melting-point resin
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(b)
Figure 3
AI summary
There is provided a method for manufacturing a resin container, the method including: an injection molding step of performing injection molding to form a bottomed cylindrical resin preform having a strength distribution which varies along a circumferential direction; and a blow molding step of performing blow molding on the preform in a state of having residual heat from the injection molding to manufacture a container. In the injection molding step, the preform is formed to have a region which starts from a corresponding position of a projection portion and has a higher strength than other parts in a circumferential direction of a bottom portion due to changing at least one of a flow velocity and a temperature of a resin having passed through the projection portion by using an injection mold in which the projection portion is partially formed in the circumferential direction of the bottom portion.