Resin Packaging Laminate With Controlled Fusion Temperatures
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional packaging materials face challenges in achieving both heat resistance and seal strength when using a single material, leading to issues like poor appearance and processing difficulties during high-temperature heat sealing.
Innovation Solution
A resin laminate for packaging material is developed with a base layer and sealant layer composed of the same resin, where the fusion initiation temperature of the base layer and seal strength reaching temperature of the sealant layer are controlled within specific ranges to ensure high processability and recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a biaxially stretched polypropylene film is used as the base layer and an unstretched polypropylene film is used as the heat seal layer, then heat sealability is improved, but the base layer shrinks at high temperatures causing poor appearance and processing difficulties
Solution Approach 1:
The invention changes the temperature parameter relationship between base layer and sealant layer by controlling their fusion temperatures. The base layer is designed with a fusion initiation temperature at least 50°C higher than the sealant layer, allowing heat sealing to be performed at temperatures where the base layer remains stable while the sealant layer fuses properly. This resolves the contradiction by decoupling the thermal requirements of heat sealing from base layer stability.
Solution Approach 2:
The invention creates a composite laminate structure where the base layer and sealant layer are made of different polypropylene compositions with deliberately different thermal properties. The base layer uses a polypropylene composition with higher melting point and dimensional stability, while the sealant layer uses a polypropylene composition with lower melting point for easy fusion. This composite approach allows each layer to perform its specific function without interfering with the other.
2Strength
If heat sealing is conducted at high temperature to achieve sufficient seal strength, then seal strength is improved, but the biaxially stretched base layer shrinks causing poor appearance
Solution Approach 1:
The invention changes the temperature parameter by creating a significant temperature gap (at least 50°C) between the fusion initiation temperature of the base layer and the sealant layer. This allows heat sealing to be conducted at temperatures sufficient for strong sealing while keeping the base layer temperature below its fusion point, preventing shrinkage and maintaining appearance quality.
3Adaptability or versatility
If the same material is used for both base layer and sealant layer to enable recycling, then recyclability is improved, but it becomes difficult to achieve both heat resistance and seal strength
Solution Approach 1:
The invention applies local quality by using the same general material category (polypropylene) for both layers but with different local compositions and properties. The base layer has specific compositional characteristics for heat resistance and dimensional stability, while the sealant layer has different compositional characteristics for low-temperature fusion and sealing. This allows each layer to have optimized local properties while maintaining overall material compatibility for recycling.
Solution Approach 2:
The invention creates a composite structure using polypropylene-based materials with different compositions for the base layer and sealant layer. This composite approach enables recyclability since both layers are polypropylene-based and can be processed together, while simultaneously achieving different performance characteristics in each layer through compositional variation.
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 laminate achieves high heat resistance, maintains product appearance, and allows for high-speed processing with improved heat seal strength and finish quality, making it suitable for easily recyclable mono-material packaging.
Implementation Method 1
the sealant layer has a seal strength reaching temperature (SRT-S)... 90°C ≤ (SRT-S) ≤ 120°C
Implementation Method 2
the base layer has a fusion initiation temperature (FIT-B)... 160°C ≤ (FIT-B) ≤ 180°C
Data Source
AI summary
An object of the invention is to provide a resin laminate for packaging material containing a base layer and a sealant layer each of which contains the same material with high processability. The resin laminate for packaging material contains at least a base layer and a sealant layer, wherein each of resin compositions for the base layer and the sealant layer contains the same resin (A) as a main component, the base layer has a fusion initiation temperature (FIT-B), and the sealant layer has a seal strength reaching temperature (SRT-S), wherein the temperatures satisfy the following inequalities of from (1) to (3):50° C.≤(FIT-B)−(SRT-S)≤90° C. Inequality (1)90° C.≤(SRT-S)≤120° C. Inequality (2)160° C.≤(FIT-B)≤180° C. Inequality (3).