Hydroxyl-Terminated Polyester Resin for Isocyanate Powder Coatings
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Solution Overview
Problem
Current hydroxyl-terminated polyester resins for isocyanate cured powder coatings have high hydroxyl values, leading to increased curing agent dosage and costs, poor mechanical stability, and inadequate weather resistance, limiting market adoption and requiring the development of a resin with a low hydroxyl value and improved properties.
Innovation Solution
A hydroxyl-terminated polyester resin is formulated with specific components such as diol, dibasic acid, glycidyl tertcarbonate, hydroxylation reagent, catalyst, and antioxidant, with controlled hydroxyl and acid values, and a vacuumizing process to achieve a hydroxyl value of 20-30 mgKOH/g, melt viscosity of 9,000-13,000 mPa·s, and optimized glass transition temperature, enhancing mechanical properties and weather resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hydroxyl value of polyester resin is increased to improve coating performance, then the mechanical property and weather resistance are improved, but the curing agent dosage increases and cost increases
Solution Approach 1:
The patent optimizes the hydroxyl value parameter to a specific range (20-30 mgKOH/g) through controlled polycondensation and hydroxylation processes. This parameter optimization achieves the best balance between coating performance (weather resistance, mechanical properties) and curing agent consumption, avoiding both excessive hydroxyl values (which increase cost) and insufficient values (which poor performance).
Solution Approach 2:
The patent uses a composite formulation combining polyester resin with specific curing agents (isocyanate, polyamide, or amine) in optimized ratios. This composite approach ensures complete reaction and optimal coating performance while controlling curing agent dosage, resolving the contradiction between performance and cost.
2Strength
If the hydroxyl value of polyester resin is increased to improve coating performance, then the mechanical property is improved, but the curing agent dosage increases and cost increases
Solution Approach 1:
The patent controls the hydroxyl value within the optimal range of 20-30 mgKOH/g through optimized polycondensation and hydroxylation processes. This parameter control achieves sufficient mechanical strength (impact resistance ≥40 cm, adhesion ≥4B) while minimizing curing agent consumption, thereby reducing cost.
Solution Approach 2:
The patent replicates the successful formula and process parameters from industrial practice (using proven catalysts like monobutyl tin oxide, specific temperature ranges of 230-240°C for polycondensation and 215-230°C for hydroxylation) to achieve consistent mechanical properties and performance without requiring excessive curing agents.
3Ease of operation
If the Tg of polyester resin is decreased to improve flexibility, then the processability is improved, but the storage stability deteriorates
Solution Approach 1:
The patent optimizes the glass transition temperature (Tg) to the range of 53-59°C through selection of diol and dibasic acid components and control of molecular weight. This Tg range provides optimal balance: low enough for good processability (flow, leveling) but high enough to ensure storage stability and prevent premature curing or degradation.
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 solution reduces curing agent consumption, improves mechanical stability, and achieves excellent weather resistance, resulting in a high-performance coating with stable mechanical properties and superior light fastness.
Implementation Method 1
carrying out polycondensation reaction of diol, dibasic acid, glycidyl tertcarbonate and a catalyst
Implementation Method 2
carrying out hydroxylation reaction until the acid value of the product obtained by hydroxylation reaction is 1-8 mgKOH/g and the hydroxyl value of the product is 20-30 mgKOH/g
Implementation Method 3
0.08-0.3 parts of a catalyst
Implementation Method 4
0.2-0.5 parts of an antioxidant
Data Source
AI summary
A hydroxyl-terminated polyester resin, a preparation method therefor and use thereof. The hydroxyl-terminated polyester resin is composed of the following raw materials in parts by mass: 25-50 parts of a diol, 40-70 parts of a dibasic acid, 0.1-2 parts of glycidyl tertcarbonate, 0.5-4 parts of a hydroxylation reagent, 0.08-0.3 parts of a catalyst and 0.2-0.5 parts of an antioxidant. The acid value of the polyester resin is 1-8 mgKOH/g, the hydroxyl value is 20-30 mgKOH/g, the melt viscosity at 200° C. is 9000-13000 mPa·s, the reactivity at 180° C. is 410-520 s, the glass transition temperature is 53-59° C., and the softening point is 101-106° C.