Stretchable Paper Laminate for Packaging Reliefs
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Solution Overview
Problem
Traditional paper materials are less suitable for packaging due to low stiffness and dimensional stability, and difficulty in creating exact folding lines with decorative or functional bulges, as they are not as stretchable as plastics.
Innovation Solution
A paper laminate with stretchable outer layers and an intermediate layer of lower stretchability, designed to break at folding lines while the outer layers hold the laminate together, allowing for the formation of reliefs and precise folding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional paper materials are used, then stiffness and dimensional stability are maintained, but stretchability is insufficient for creating decorative or functional reliefs
Solution Approach 1:
The invention uses a composite laminate structure consisting of a first paper layer, a second paper layer, and an intermediate layer between them. The outer paper layers provide stretchability (at least 5% elongation) to enable relief formation, while the intermediate layer provides stiffness and dimensional stability. This composite structure resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The laminate structure assigns different functional qualities to different layers: the outer paper layers are designed with high stretchability for forming reliefs and bulges, while the intermediate layer is designed with lower stretchability (less than 3%) to maintain dimensional stability and provide stiffness. Each layer performs its specific function locally within the composite structure.
2Adaptability or versatility
If highly stretchable paper is used, then formation of decorative or functional reliefs is enabled, but folding lines do not provide exact and straight edges
Solution Approach 1:
The intermediate layer in the laminate acts as a stabilizing element that provides structural support during folding operations. Its lower stretchability (less than 3%) compared to the outer layers ensures that folding lines remain precise and straight, while the outer layers can still stretch sufficiently to form reliefs.
Solution Approach 2:
The intermediate layer is specifically designed with localized properties (lower stretchability) at the folding line regions to ensure precision, while the outer layers maintain high stretchability in the relief formation regions. This spatial differentiation of material properties resolves the contradiction between stretchability and folding precision.
3Adaptability or versatility
If exclusively highly stretchable paper is used, then relief formation is improved, but stiffness and dimensional stability decrease
Solution Approach 1:
The laminate combines paper layers with different stretchability characteristics. The outer layers (first and second paper layers) have high stretchability (at least 5%) for relief formation, while the intermediate layer has low stretchability (less than 3%) to maintain dimensional stability. The combination achieves both requirements simultaneously.
Solution Approach 2:
Different regions of the laminate have different mechanical properties: the outer layers are optimized for stretchability in relief zones, while the intermediate layer is optimized for dimensional stability in the overall structure. This local differentiation allows the material to exhibit both high stretchability where needed and high stability where required.
Data Source
Figure 1a~1d
Figure 2A
Figure 2B
AI summary
A paper laminate comprising a first stretchable paper layer, a second stretchable paper layer and an intermediate paper layer arranged between the first and the second stretchable paper layer, characterized in that the stretchability (ISO 1924/3) of the first and the second stretchable paper layer is at least 5 % in both the machine direction (MD) and the cross direction (CD) and the stretchability (ISO 1924/3) of the intermediate paper layer is less than 4 % in the MD and/or the CD.