Synthetic Resin Container Shoulder Crystal Orientation Control
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Solution Overview
Problem
Synthetic resin containers with significantly inclined shoulders (>120°) experience increased contraction and volume decrease due to biaxial stretch-blow molding, leading to deformation and reduced capacity.
Innovation Solution
Producing synthetic resin containers with a shoulder inclined at an angle greater than 120° using liquid blow molding, where the shoulder has a crystal orientation in the machine direction of less than 1, maintaining the shape and preventing contraction by controlling the crystal structure through specific processing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the shoulder is inclined at an angle greater than 120° with respect to the axis of the mouth, then the container achieves a desired shape for functionality and aesthetics, but the draw ratio in the machine direction increases, causing the shoulder to undergo contraction after molding, leading to volume decrease and deformation
Solution Approach 1:
The patent applies parameter changes by controlling the crystallization conditions during blow molding, specifically maintaining the shoulder crystal orientation in the machine direction at less than 1. This involves adjusting processing parameters such as molding temperature, blow pressure, and cooling rate to achieve the desired crystal structure that prevents contraction while maintaining the >120° shoulder inclination angle
Solution Approach 2:
The patent applies local quality by creating different crystal orientations in different parts of the container. Specifically, the shoulder region is controlled to have crystal orientation in the machine direction of less than 1, while other portions of the container can have different crystal orientations appropriate for their functional requirements. This localized control of crystal structure prevents shoulder contraction while maintaining overall container integrity
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 method effectively reduces the degree of contraction of the shoulder, preventing volume loss and deformation in synthetic resin containers with inclined shoulders, ensuring consistent shape and functionality.
Implementation Method 1
supplying, to a preform that has been formed by thermoplastic resin in a bottomed tubular shape, a liquid heated to a predetermined temperature at a predetermined pressure to liquid blow mold the preform
Implementation Method 2
a liquid heated to a predetermined temperature at a predetermined pressure to liquid blow mold the preform
Implementation Method 3
the shoulder has a crystal orientation in a machine direction of less than 1
Data Source
Figure 1
Figure 2
AI summary
Provided is a synthetic resin container (1) having a bottle shape including a tube-shaped mouth (2), a tube-shaped trunk (4) having one end closed by a bottom (3), and a shoulder (5) through which another end of the trunk (4) is connected to the mouth (2). The shoulder (5) is inclined at an angle greater than 120° with respect to an axis of the mouth (2), and the shoulder (5) has a crystal orientation in a machine direction of less than 1.