Low-TVOC Silicone Composite Sheet with Segmented Adhesive Layers
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Solution Overview
Problem
Existing coating technologies for high coat weight applications, such as airbags and artificial leather, fail to meet stringent TVOC release standards of less than 100ugC/g, and require harsh curing conditions to reduce VOCs, which are not practical or effective.
Innovation Solution
A composite sheet with a two-layer structure comprising a silicone adhesive layer containing VOC-releasing additives and a reinforcing layer, where the adhesive layer's coating amount is less than 45 wt%, allowing for reduced TVOC release without harsh curing conditions while maintaining mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high coat weight coating is applied to achieve heat resistance and mechanical properties, then the mechanical strength and heat resistance are improved, but the TVOC release increases and fails to meet the strict regulations of less than 100ugC/g
Solution Approach 1:
The coating is divided into multiple layers with different functions: a first silicone layer containing adhesion promoters for substrate bonding, and a second silicone layer without adhesion promoters for low TVOC release. This segmentation allows each layer to be optimized for its specific function, resolving the contradiction between adhesion strength and TVOC reduction.
Solution Approach 2:
Adhesion promoters are extracted from the second silicone layer and concentrated only in the first silicone layer. This extraction eliminates the source of TVOC emissions from the second layer while preserving the necessary adhesion properties in the first layer, enabling the coating to meet strict TVOC regulations.
2Strength
If traditional single-layer silicone coating is used to ensure adhesion and mechanical properties, then the adhesion strength is maintained, but the TVOC release cannot be reduced below 100ugC/g
Solution Approach 1:
The single-layer coating is segmented into two distinct silicone layers. The first layer contains adhesion promoters for substrate bonding, while the second layer is free of adhesion promoters to minimize TVOC release. This segmentation enables both adhesion strength and low TVOC emissions to be achieved simultaneously.
Solution Approach 2:
Different quality characteristics are assigned to different parts of the coating: the first layer has high adhesion promoter content for strong substrate bonding, while the second layer has zero adhesion promoters for low TVOC release. This local differentiation resolves the contradiction between adhesion and emissions.
3Strength
If adhesion promoters are added to enhance substrate bonding, then the adhesion strength is improved, but the TVOC release increases due to more VOC-releasing additives
Solution Approach 1:
Adhesion promoters are segmented into specific layers where they are needed. The first silicone layer contains adhesion promoters for substrate bonding, while the second silicone layer excludes them to prevent TVOC emissions. This targeted segmentation resolves the contradiction between adhesion enhancement and emissions control.
Solution Approach 2:
Adhesion promoter concentration is optimized locally: high concentration in the first layer for bonding, and zero concentration in the second layer for emissions control. This local quality differentiation allows adhesion strength to be improved without increasing overall TVOC release.
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 composite sheet achieves TVOC release below 100ugC/g, preferably below 70ugC/g, with good adhesion and mechanical properties, using a two-layer structure that minimizes VOC-releasing additives in the adhesive layer.
Implementation Method 1
an organopolysiloxane comprising at least two alkenyl groups, an organopolysiloxane comprising at least two SiH groups, and a hydrosilylation reaction catalyst
Data Source
AI summary
The disclosure relates to a low TVOC release silicone composite sheet, comprising: 1) a substrate layer selected from a fabric or a polymeric film. 2) a silicone adhesive layer coated onto the substrate layer and containing volatile organic compound (VOC) releasing additives, and 3) a reinforcing layer adjacent to the silicone adhesive layer; wherein the coating amount of the silicone adhesive layer is less than 45 wt%, preferably less than 35 wt%, more preferably less than 20 wt%, based on the total coating amount of the silicone adhesive layer and the reinforcing layer. and wherein both silicone adhesive layer and reinforcing layer contain or consist essentially of liquid silicone rubber (LSR) or room temperature vulcanized silicone rubber (RTV), and said reinforcing layer contains one or more coatings comprising A). organopolysiloxane having one or more silicon atom-bonded alkenyl groups on average in one molecule; B). an organohydrogenpolysiloxane; and C). a hydrosilylation reaction catalyst present in any amount effective to cure the composition. Furthermore, it relates also to a method for coating and for reducing TVOC release.