Recycled Polyvinyl Butyral With Higher Melt Flow for Film Formation
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Solution Overview
Problem
Recycled polyvinyl butyral (rPVB) faces issues with unsatisfactory reprocessability and adhesion strength due to low melt flow index (MI) and plasticizer content, limiting its applications beyond laminated safety glass.
Innovation Solution
A method involving a mixture of rPVB with an antiblocking agent and a free radical initiator, such as azo compounds or organic peroxides, to increase the MI of rPVB, allowing for improved reprocessability and adhesion, including the use of unsaturated resins like LDPE and PMMA to enhance molecular weight and crosslinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If virgin PVB is used to maintain sufficient rigidity and lower melt flow index, then the material maintains structural stability and resistance to deformation, but it accumulates on hot metal elements and has poor reprocessability
Solution Approach 1:
The patent applies parameter changes by modifying the melt flow index of rPVB through chemical treatment with free radical initiators. The MI is increased from conventional levels (≤2 g/10min) to greater than 7 g/10min at 190°C, which fundamentally changes the flow characteristics and reprocessability of the material while maintaining its rigidity and structural stability.
Solution Approach 2:
The patent replaces mechanical mixing and physical processing with chemical modification using free radical initiators. Instead of relying on mechanical methods to improve reprocessability, the invention uses chemical reactions (azo compounds or organic peroxides) to alter the molecular structure and increase MI, thereby enabling better reprocessability without sacrificing rigidity.
2Strength
If rPVB contains plasticizer to adjust adhesion between interlayer film and glass, then adhesion between PVB and glass is improved, but adhesion strength to non-glass surfaces such as textiles or polymer films deteriorates
Solution Approach 1:
The patent extracts and removes plasticizers from the rPVB composition. By eliminating plasticizer-containing rPVB and using only plasticizer-free rPVB in the composition, the invention resolves the adhesion contradiction: the material maintains good adhesion to glass through the chemical modification (increased MI) while gaining improved adhesion to non-glass surfaces like textiles and polymer films, thereby expanding versatility.
Solution Approach 2:
The patent changes the compositional parameter by eliminating plasticizers and instead achieving the desired adhesion through chemically modified rPVB with MI > 7 g/10min. This parameter change in molecular structure and flow properties enables universal adhesion performance across different substrates without the negative effects of plasticizer contamination.
3Ease of manufacture
If conventional rPVB is used directly, then the production process is simple, but the material has unsatisfactory reprocessability and limited application breadth
Solution Approach 1:
The patent applies parameter changes by chemically modifying rPVB to achieve MI > 7 g/10min through free radical initiation. This single parameter change (increasing MI) simultaneously improves reprocessability and enables diverse film formation methods (extrusion, blow molding, stretch blowing, injection molding), thereby expanding application breadth while maintaining manufacturing simplicity.
Solution Approach 2:
The patent creates a composite material system by combining plasticizer-free rPVB with specific free radical initiators (azo compounds or organic peroxides) and optionally antiblocking agents. This composite approach enables controlled chemical modification during processing, achieving superior reprocessability and versatile applications while keeping the formulation and process relatively simple.
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 reprocessed rPVB exhibits a higher MI, enabling broader film formation applications and adherence to environmental sustainability standards, suitable for hot melt adhesives and composite material films.
Implementation Method 1
the free radical initiator is added into the first mixture to undergo a reaction, so as to obtain the reprocessed material of the rPVB; wherein the free radical initiator comprises an azo compound, an organic peroxide or a combination thereof
Data Source
AI summary
Provided are a reprocessed material of recycled polyvinyl butyral and the method for producing the same. The method comprises steps (A) and (B); step (A): heating a first mixture comprising recycled polyvinyl butyral and an antiblocking agent; and step (B): adding a free radical initiator into the first mixture to undergo a reaction to obtain the reprocessed material of recycled polyvinyl butyral; wherein the free radical initiator comprises an azo compound, an organic peroxide or a combination thereof, the reprocessed material of recycled polyvinyl butyral has a MI of greater than 7 g/10 min at 190° C. and under 2.16 kg of load. The reprocessed material of recycled polyvinyl butyral has excellent reprocessability, so it is applicable to make a hot adhesive and a composite material film.