PGDB Plasticizer for Polyurethane Compatibility and Strength
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Solution Overview
Problem
Traditional plasticizers used in polyurethane formulations often face issues such as volatility, migration, discoloration, and reduced mechanical properties, necessitating the need for alternative plasticizers that offer improved compatibility, color stability, and mechanical strength.
Innovation Solution
The use of 1,2-propylene glycol dibenzoate (PGDB) as a low hydroxyl dibenzoate plasticizer, which is added during the reaction of isocyanate and polyol in reactive polyurethane systems, providing enhanced compatibility, hardness, tensile strength, and optical clarity while minimizing exudation and yellowing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional plasticizers are used in polyurethane formulations, then processability and flexibility are improved, but volatility, migration, discoloration, and reduced mechanical properties occur
Solution Approach 1:
The patent changes the chemical parameters of the plasticizer by using dibenzoate esters with specific molecular weight ranges (300-600 g/mol) and controlled hydroxyl numbers (5-30 mg KOH/g). This parameter optimization allows the plasticizer to maintain compatibility and mechanical properties while reducing volatility and migration compared to traditional high-molecular-weight plasticizers
Solution Approach 2:
The invention uses composite ester structures combining aromatic dibenzoate cores with aliphatic or alicyclic ester chains. This composite structure provides both the compatibility needed for processability and the structural integrity required for maintaining mechanical properties, resolving the contradiction between ease of operation and reliability
2Ease of operation
If traditional plasticizers are used in polyurethane formulations, then flexibility is improved, but discoloration and yellowing occur
Solution Approach 1:
The patent introduces local quality by incorporating aromatic dibenzoate ester groups that provide UV stability and color resistance in specific regions of the polymer chain, while the aliphatic ester portions maintain flexibility. This localized functional distribution allows the plasticizer to provide flexibility without the harmful discoloration effect
Solution Approach 2:
The invention converts the potential harm of aromatic structures (which can cause yellowing) into a benefit by using dibenzoate esters with specific molecular weights and hydroxyl numbers. The aromatic core provides UV absorption and color stability, while the controlled ester chain length and low hydroxyl content prevent the yellowing that typically occurs with aromatic plasticizers, thus converting a potential harm into a benefit
3Stability of the object's composition
If traditional plasticizers are used in polyurethane formulations, then compatibility is improved, but exudation and migration occur
Solution Approach 1:
The patent optimizes the molecular weight parameter of the dibenzoate plasticizer to fall within 300-600 g/mol, which is high enough to reduce volatility and migration but low enough to maintain compatibility with the polyurethane matrix. The hydroxyl number is controlled at 5-30 mg KOH/g to ensure hydrogen bonding compatibility while minimizing exudation
Solution Approach 2:
The invention creates a plasticizer structure that mimics the polyurethane polymer chain structure, with dibenzoate ester groups that can form hydrogen bonds similar to the urethane linkages in the polymer. This structural copying enhances compatibility at the molecular level, preventing phase separation and subsequent exudation
Data Source
Figure 1(a)
Figure 1(b)
Figure 2(a)~2(b)
AI summary
Low hydroxyl value dibenzoate plasticizer for use in a reactive polyurethane composition, including but not limited to thermoplastic and thermoset polyurethanes, wherein the plasticizer is particularly useful in TPU's, a reactive polyurethane adhesive or sealant, or a castable polyurethane article and achieves comparable or improved properties, including without limitation compatibility, color, exudation, optical properties, MVTR, hardness, tensile strength, tear strength, rebound, compression set, and solvent swell, when compared with that achieved with traditional plasticizers, including other benzoate esters, used in polyurethane compositions.