Polyethylene Foam Sheet Extrusion for Low-Contamination Wrapping
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Solution Overview
Problem
Conventional polyethylene-based resin foam sheets contaminate wrapped articles due to residues from inorganic substances and chemical blowing agents, and recycling these sheets leads to fluctuating foaming states and reduced productivity.
Innovation Solution
A method involving extrusion-foaming a foamable resin melt with organic physical blowing agents and nitrogen, eliminating the need for inorganic substances and chemical blowing agents, with specific ratios and amounts of these agents to stabilize foaming and reduce residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic substances and chemical blowing agents are used as cell controlling agents, then the foaming process is effective, but contamination of wrapped articles occurs due to residues
Solution Approach 1:
The patent extracts and removes inorganic substances and chemical blowing agents from the foaming process. By using only organic physical blowing agents (hydrocarbons with 3-5 carbon atoms and dialkyl ethers), the harmful residues that contaminate wrapped articles are eliminated while maintaining effective foaming through controlled bubble nucleation and growth mechanisms
Solution Approach 2:
The patent changes the parameters of the blowing agents from inorganic/chemical types to specific organic physical types with controlled carbon atom numbers (3-5 for hydrocarbons, 1-3 for alkyl groups in dialkyl ethers). This parameter change ensures the agents evaporate completely without residues, solving the contamination problem while maintaining foaming effectiveness
2Ease of repair
If recycled polyethylene-based resin foam sheets are used as raw materials, then material recycling is achieved, but foaming state fluctuates and productivity decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the resin system by eliminating inorganic substances and chemical blowing agents. This creates a homogeneous resin matrix without residual contaminants that would interfere with recycling, allowing recycled material to maintain consistent foaming behavior and production stability across multiple recycling cycles
Solution Approach 2:
The patent achieves homogeneity in the resin system by removing heterogeneous inorganic substances and chemical blowing agents. This homogeneous composition ensures that recycled resin maintains uniform properties, preventing foaming state fluctuations and maintaining high productivity in continuous production
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 produces a foam sheet with reduced contamination risk and stable foaming, suitable for recycling and maintaining cleanliness, especially for wrapping sensitive items like glass panels.
Implementation Method 1
extrusion-foaming a foamable resin melt containing a polyethylene-based resin and a physical blowing agent to produce a polyethylene-based resin foam sheet
Data Source
AI summary
A method for producing a polyethylene-based resin foam sheet and a polyethylene-based resin foam sheet are provided without depending on an inorganic substance and a chemical blowing agent, and the method enables production of a good polyethylene-based resin foam sheet. In a first way of the method including extrusion-foaming a foamable resin melt containing a polyethylene-based resin and a physical blowing agent to produce a polyethylene-based resin foam sheet, one or more organic physical blowing agents selected from hydrocarbons having 3 to 5 carbon atoms and dialkyl ethers having an alkyl group having 1 to 3 carbon atoms and nitrogen are used as a physical blowing agent, and adjustment is performed so that the total (A + B) of the amount A of the organic physical blowing agents added and the amount B of the nitrogen added is 0.5 mol or more and 5 mol or less per kg of a resin component, the amount B of the nitrogen added is 0.1 mol or more and 0.4 mol or less per kg of the resin component, and the ratio (A/B) of the amount A of the organic physical blowing agents added to the amount B of the nitrogen added is 2 or more and 18 or less. The polyethylene-based resin foam sheet of the present invention has a density of 20 kg/m3 or more and 100 kg/m3 or less and an average of the number of cells of 0.5 cells/mm or more and 5 cells/mm or less in the thickness direction, the foam sheet has an ash content of less than 0.1 mass% (including 0), and the ash content includes sodium at a proportion of 10 mass% or less (including 0).