Biaxially Oriented Laminated Sheet for Uniform Large-Area Rigidity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing laminated polypropylene sheets face issues with insufficient adhesion between layers, leading to air incorporation, warping, waviness, and difficulty in applying them to large-area molded articles, which lack homogenized in-plane rigidity and surface smoothness.
Innovation Solution
A biaxially oriented laminated sheet is created by alternately laminating a biaxially oriented polypropylene film with an olefin-based resin, ensuring uniform tensile modulus in both directions and minimal surface roughness, using a continuous pressing device with multiple heating and cooling zones to achieve high rigidity and smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If roll forming machine is used to laminate and bond polypropylene films, then the bonding process can be performed, but adhesion between layers is insufficient leading to air incorporation and warping
Solution Approach 1:
The patent replaces the roll forming machine's mechanical pressing system with a vacuum pressing system. The vacuum press applies uniform pressure across the entire sheet surface through vacuum suction, ensuring complete contact between layers and eliminating air pockets. This substitution resolves the adhesion problem by providing consistent pressure distribution that mechanical rolls cannot achieve.
Solution Approach 2:
The patent changes the bonding parameters by using a vacuum pressure of 5 to 80 kPa in combination with controlled heating temperature and time. This parameter optimization ensures sufficient adhesion without causing the films to stick to the heating plate, resolving the contradiction between achieving good bonding and preventing unwanted adhesion to equipment.
2Reliability
If heating roll temperature is increased to ensure bonding, then adhesion improves, but wrinkles form on the surface layer
Solution Approach 1:
The patent replaces radiant heat from rolls with conductive heat from a controlled heating plate, combined with vacuum pressing. This system provides uniform heat distribution without the localized high-temperature spots that cause wrinkles, while the vacuum ensures uniform pressure to maintain surface smoothness during bonding.
Solution Approach 2:
The patent optimizes the heating temperature to a specific range and controls the heating time, combined with vacuum pressure parameters. This parameter control achieves sufficient adhesion while preventing surface wrinkles, resolving the contradiction between bonding quality and surface smoothness.
3Reliability
If sheet is fed slowly to ensure bonding, then adhesion improves, but wrinkles form due to radiant heat from roll
Solution Approach 1:
The patent replaces the roll forming machine's radiant heating system with a heating plate system that provides uniform conductive heat. This eliminates the localized overheating that causes wrinkles during slow feeding, while the vacuum pressing ensures consistent bonding quality throughout the process.
4Strength
If multiple layers are laminated to increase rigidity, then mechanical strength improves, but air incorporation and warping increase
Solution Approach 1:
The patent replaces mechanical roll pressing with vacuum pressing, which applies uniform pressure across the entire multi-layer structure. This ensures complete contact between all layers and eliminates air pockets, achieving high rigidity without warping or waviness that would result from uneven mechanical pressure distribution.
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 laminated sheet exhibits excellent rigidity and surface smoothness over large areas, suitable for large molded articles with minimal mechanical property variations and uniformity.
Implementation Method 1
a heating step of heat-fusing the laminated sheet precursor with a heating plate
Implementation Method 2
heat-fusing in a vacuum pressing device
Implementation Method 3
pressing with a planar mold
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
It is possible to provide a laminated sheet that is applicable to large molded articles, exhibits excellent rigidity, particularly excellent homogeneity of in-plane rigidity when formed into a large area, and has minimal variation in mechanical properties. The laminated sheet of the present invention has a structure in which layer a, comprising a biaxially oriented polypropylene film, and layer b, comprising an olefin-based resin with a melting point of 110 to 160°C, are alternately laminated. When one side direction of the laminated sheet is defined as an x-direction and a direction perpendicular thereto as a y-direction, a tensile modulus of elasticity in the x-direction and a tensile modulus of elasticity in the y-direction at three positions-namely, a center position in the y-direction, and two positions located 200 mm from this center position in the y-direction-are all within a range of 2000 to 5000 MPa.