Multilayer Container Polyamide Resin Delamination Control
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Solution Overview
Problem
Multilayered containers with polyester and polyamide resin layers experience delamination issues due to residual stress and moisture content variations during biaxial stretching and blow molding.
Innovation Solution
Adjusting the storage elastic modulus of the polyamide resin to a specific range (1 MPa to 100 MPa) and maintaining a moisture content of 0.5% or less in the polyamide resin layer before biaxial stretching and blow molding, using a xylylenediamine-based polyamide resin with specific structural unit ratios, to reduce delamination risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayered container with polyester resin outer layer and polyamide resin barrier layer is produced using conventional methods, then the container structure is formed, but delamination occurs between layers due to residual stress and moisture content variations during biaxial stretching and blow molding
Solution Approach 1:
The patent applies parameter changes by precisely controlling the storage elastic modulus of the polyamide resin within 1-100 MPa and maintaining moisture content at 0.5% or less before biaxial stretching. These parameter optimizations prevent delamination by ensuring the polyamide resin layer has appropriate mechanical properties and minimal moisture-induced stress during the forming process, thereby improving reliability without complicating manufacturing
Solution Approach 2:
The patent implements preliminary action by pre-adjusting the storage elastic modulus and moisture content of the polyamide resin before the biaxial stretching and blow molding process. This preliminary optimization of material properties ensures that the resin layer is in the optimal state to resist delamination during subsequent manufacturing steps, solving the contradiction between reliability and manufacturing ease
2Strength
If the storage elastic modulus of polyamide resin is increased to improve delamination resistance, then layer bonding strength improves, but the resin becomes too rigid and susceptible to stress-induced shrinkage and cracking
Solution Approach 1:
The patent resolves this contradiction through parameter changes by defining an optimal range for storage elastic modulus (1-100 MPa). This range balances layer bonding strength with resin flexibility, preventing both delamination and stress-induced shrinkage. The lower limit ensures sufficient bonding while the upper limit maintains flexibility to accommodate forming stresses without cracking
Solution Approach 2:
The patent applies partial action by not maximizing the storage elastic modulus beyond what is necessary for delamination resistance. Instead, it optimizes the modulus within a specific range that provides sufficient bonding strength while maintaining the flexibility needed to prevent stress-induced defects, avoiding the harm of excessive rigidity
3Reliability
If moisture content of polyamide resin is reduced to prevent delamination, then delamination resistance improves, but drying process complexity and energy consumption increase
Solution Approach 1:
The patent implements preliminary action by ensuring the polyamide resin has moisture content of 0.5% or less before the biaxial stretching process. This preliminary moisture control, achieved through controlled drying before molding, prevents delamination during forming while minimizing the need for extensive post-processing drying, thereby balancing reliability improvement with energy efficiency
Solution Approach 2:
The patent applies parameter changes by setting a specific moisture content threshold (0.5% or less) that is sufficient to prevent delamination without requiring excessive drying. This optimized parameter achieves the necessary delamination resistance while minimizing drying energy consumption by avoiding over-drying
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 suppresses delamination and enhances the multilayered container's resistance to impact and load, maintaining the storage elastic modulus while preventing excessive stress-induced shrinkage delamination.
Implementation Method 1
biaxially stretching and blow molding a preform having a layer containing a polyester resin as a main component (1) and a layer containing a polyamide resin as a main component (2)
Implementation Method 2
a storage elastic modulus G' of the polyamide resin at the time of the biaxially stretching and blow molding being 1 MPa or more and less than 100 MPa
Implementation Method 3
a moisture content of the layer containing the polyamide resin as the main component (2) in the preform immediately before the biaxially stretching and blow molding being 0.5% or less
Data Source
Figure 1(1)~1(6)
AI summary
To provide a method for producing a multilayered container, which has a layer containing a polyester resin as a main component and a layer containing a polyamide resin as a main component and in which delamination is less likely to occur. The method for producing a multilayered container contains biaxially stretching and blow molding a preform having a polyester resin layer and a polyamide resin layer; a storage elastic modulus G' of the polyamide resin being 5 MPa or more and less than 100 MPa; a moisture content of the polyamide resin layer being 0.5% or less; and the polyamide resin containing a xylylenediamine-based polyamide resin, 70 mol% or more of the structural units derived from diamine being derived from meta-xylylenediamine, from 80 to 97 mol% of the structural units derived from dicarboxylic acid being derived from an α,ω-straight chain aliphatic dicarboxylic acid having from 4 to 8 carbons and from 20 to 3 mol% being derived from aromatic dicarboxylic acid.