Stretchable Film Surface Layer Composition for Heat Resistance
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Solution Overview
Problem
Stretchable films using high-density polyethylene or homopolypropylene for surface layers have insufficient heat resistance and elasticity, leading to deformation or hole formation when adhered with hot melt adhesives, and increased thickness of the elastomer layer results in high rigidity and excessive force required for stretching.
Innovation Solution
A stretchable film configuration with an elastomer layer and a surface layer containing polypropylene-based resins and calcium carbonate, where the calcium carbonate content is 10-75% by mass and the polypropylene-based resin content is 30-70% by mass, with a melting point below 160°C, providing exceptional blocking resistance, heat resistance, and elasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If polyethylene (HDPE) is used for the surface layer, then blocking resistance is improved, but heat resistance becomes insufficient causing deformation or hole formation during hot melt adhesive application
Solution Approach 1:
The patent uses a composite surface layer comprising both polyethylene and polypropylene resins. The polyethylene component (30-70 mass%) provides blocking resistance, while the polypropylene component (30-70 mass%) with melting point 100-160°C provides heat resistance. This composite approach allows both requirements to be satisfied simultaneously without compromising either property.
2Reliability
If homopolypropylene (H-PP) is used for the surface layer, then heat resistance is improved, but elasticity becomes insufficient
Solution Approach 1:
The patent changes the polymer structure parameter by using copolypropylene (random or block) instead of homopolypropylene. The copolymer structure with ethylene units introduces flexibility and elasticity while maintaining the heat resistance properties of polypropylene. The melting point is controlled within 100-160°C to balance heat resistance and elasticity requirements.
3Ease of operation
If the thickness of the elastomer layer is increased to improve elasticity, then elasticity is improved, but rigidity becomes too high requiring strong force for stretching
Solution Approach 1:
The patent applies local quality by providing a surface layer with specific properties (blocking resistance and heat resistance) on the elastomer layer. This allows the elastomer layer thickness to be optimized for elasticity (20-55 μm) without compromising surface performance, while the surface layer compensates for any rigidity issues with its own mechanical properties and the calcium carbonate filler distribution.
4Object-generated harmful factors
If calcium carbonate content in the surface layer is increased to improve blocking resistance, then blocking resistance is improved, but heat resistance may be compromised
Solution Approach 1:
The patent controls the calcium carbonate content within 10-75 mass% of the surface layer and combines it with polypropylene resin having a specific melting point range (100-160°C). This parameter optimization ensures that sufficient calcium carbonate is present for blocking resistance while the polypropylene matrix maintains adequate heat resistance for hot melt adhesive application.
Data Source
AI summary
Provided is a stretchable film including an elastomer layer, and a surface layer provided on any one or both of a first surface and a second surface of the elastomer layer, in which the surface layer contains one or more polypropylene-based resins selected from the group consisting of block polypropylene, which is a copolymer with ethylene, and random polypropylene, which is a copolymer with ethylene, and calcium carbonate, a content of the calcium carbonate in the surface layer is 10% to 75% by mass with respect to a total mass of the surface layer, a thickness of the elastomer layer is 20 μm to 55 μm, and a thickness of the surface layer is 0.4 μm to 5.0 μm.