Acrylic Polyvinyl Acetal Films with Segmented Layers
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Solution Overview
Problem
Current films comprising multiple layers with (meth)acrylic and polyvinyl acetal polymers face challenges in achieving optimal film properties such as transparency, low haze, and high transmission due to incompatibilities in polymerized units and monomer compositions, leading to variations in glass transition temperatures and mechanical properties.
Innovation Solution
A film structure is developed with a first layer comprising a (meth)acrylic polymer and polyvinyl acetal polymer, incorporating specific monomers and crosslinkers to achieve a balanced glass transition temperature and mechanical strength, while a second layer with a higher glass transition temperature ensures compatibility and improved film performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single layer comprising (meth)acrylic polymer and polyvinyl acetal polymer is used, then film formation is simplified, but incompatibilities between polymerized units lead to poor film properties including high haze and low transparency
Solution Approach 1:
The film is divided into multiple layers with distinct compositions. The first layer contains (meth)acrylic polymer and polyvinyl acetal polymer, while the second layer contains only (meth)acrylic polymer. This segmentation allows each layer to be optimized independently, with the first layer providing adhesion and the second layer providing optical clarity, thereby resolving the incompatibility issues that would exist in a single mixed-layer structure.
Solution Approach 2:
Different regions of the film have different compositions tailored to their specific functions. The first layer is designed for adhesion to substrates like glass or plastic, while the second layer is designed for optical performance. This local differentiation of material properties allows each region to perform optimally without compromising the other.
2Adaptability or versatility
If polymerized units with different glass transition temperatures are combined in one layer, then film flexibility is improved, but mechanical properties and transparency deteriorate due to incompatibility
Solution Approach 1:
The film is segmented into two distinct layers: the first layer contains both (meth)acrylic polymer and polyvinyl acetal polymer with different glass transition temperatures, providing flexibility and adhesion; the second layer contains only (meth)acrylic polymer with uniform composition, providing mechanical strength and optical clarity. This segmentation allows each layer to be optimized for its specific function without the detrimental effects of incompatibility.
Solution Approach 2:
The first layer functions as a composite material combining (meth)acrylic polymer and polyvinyl acetal polymer to achieve desired flexibility and adhesion properties. The second layer is a homogeneous (meth)acrylic polymer layer providing structural integrity. This composite approach allows the film to exhibit both flexibility and strength simultaneously.
3Strength
If (meth)acrylic polymer and polyvinyl acetal polymer are mixed in one layer, then adhesion is improved, but optical properties including transparency and transmission are reduced due to incompatibility
Solution Approach 1:
The film is segmented into an first layer for adhesion and a second layer for optical performance. The first layer contains both (meth)acrylic polymer and polyvinyl acetal polymer to maximize adhesion to substrates. The second layer contains only (meth)acrylic polymer to ensure high optical transparency and light transmission. This segmentation eliminates the optical defects caused by mixing incompatible polymers while maintaining adhesion through the first layer.
Solution Approach 2:
The first layer is locally optimized for adhesion properties by incorporating polyvinyl acetal polymer, while the second layer is locally optimized for optical properties by using homogeneous (meth)acrylic polymer. This local quality differentiation allows the film to simultaneously achieve strong adhesion and high light transmission without the compromises required in a single mixed layer.
Data Source
AI summary
A film is described comprising a first film layer having a Tg ranging from 30° C. to 60° C. The first film layer comprises a (meth)acrylic polymer and polyvinyl acetal polymer composition. The film further comprises a second layer proximate the first film layer. The second layer is different than the first film layer. The second may be a cured (meth)acrylic polymer film or coating; a backing such as thermoplastic polymer, woven or nonwoven fabrics, metal foils, paper, foams; or a coverfilm such as a fluoropolymer.