EVA-Propylene Adhesive Resin Heat Resistance Flexibility
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Solution Overview
Problem
Hot melt adhesives based on ethylene/vinyl acetate copolymers face limitations in heat resistance and thermal creep resistance, which restrict their application in high-temperature environments without compromising adhesive strength and flexibility.
Innovation Solution
A resin composition combining ethylene/vinyl acetate copolymer with specific propylene resin compositions, optionally including amorphous poly-α-olefin, functionalized propylene polymer, tackifier, and fluidity modifier, to enhance heat resistance and flexibility while maintaining adhesive strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a crystalline component is added to increase heat resistance, then heat resistance is improved, but flexibility deteriorates due to stress concentration
Solution Approach 1:
The patent applies parameter changes by precisely controlling the melting point (120-170°C) and isotactic pentad fraction (90-99.8%) of the propylene polymer, as well as the vinyl acetate content (10-45 wt%) of the EVA copolymer. These parameter optimizations enable the adhesive to achieve heat resistance without sacrificing flexibility, resolving the contradiction between thermal stability and mechanical柔韧性.
Solution Approach 2:
The patent creates a composite adhesive system combining EVA copolymer with propylene polymer in specific ratios (30-98 wt% EVA, 70-2 wt% propylene). This composite approach allows the synergistic combination of EVA's flexibility and propylene's heat resistance, eliminating the need to choose between the two properties.
2Temperature
If a high-molecular weight component is added to increase heat resistance, then heat resistance is improved, but workability deteriorates due to increased melt viscosity
Solution Approach 1:
The patent optimizes the melt flow rate of the propylene polymer within 0.1-500 g/10 min at 230°C, balancing molecular weight for heat resistance while maintaining adequate flow for workability. This parameter control resolves the contradiction between thermal performance and applicability.
3Shape
If vinyl acetate content in EVA is increased to improve flexibility, then flexibility is improved, but heat-resistant adhesiveness deteriorates
Solution Approach 1:
The patent optimizes the vinyl acetate content within 10-45 wt% of the EVA copolymer, finding the optimal balance point where sufficient flexibility is maintained while heat-resistant adhesiveness is preserved through the synergistic effect of the propylene polymer addition.
Solution Approach 2:
By combining EVA copolymer with propylene polymer in specific proportions, the patent creates a composite system where the propylene component compensates for the heat resistance deficiency of high-vinyl acetate EVA, enabling flexibility improvement without heat resistance sacrifice.
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 adhesive resin compositions exhibit improved heat resistance and flexibility, suitable for high-temperature applications, with enhanced thermal creep resistance and adhesive strength, broadening their use in industrial fields.
Implementation Method 1
the melting point Tm (b) according to differential scanning calorimetry (DSC), wherein the polymer is held at 200°C for 10 minutes in DSC, cooled to -20°C at a temperature decreasing rate of 10°C/min, held at -20°C for 1 minute, and heated again at a temperature increasing rate of 10°C/min, is 120 to 170°C
Implementation Method 2
the isotactic pentad fraction (mmmm) is 90 to 99.8%
Implementation Method 3
the polymer shows a melting point Tm of less than 120°C or shows no melting points according to differential scanning calorimetry (DSC)
Implementation Method 4
these adhesives are unsatisfactory in terms of creep characteristic during prolonged use in a high temperature environment (hereinafter, this characteristic is sometimes abbreviated as 'thermal creep resistance')
Implementation Method 5
adhesive strength at high temperatures (hereinafter, this characteristic is sometimes abbreviated as 'high-temperature bonding properties')
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Object: To provide adhesive resin compositions improved in heat resistance without deteriorations in adhesive strength and flexibility. Solution: An adhesive resin composition comprises 30 to 98 wt% of an ethylene/vinyl acetate copolymer (a) and 70 to 2 wt% of a propylene resin composition (P) described below (wherein the total of the component (a) and the component (P) is 100 wt%). The propylene resin composition (P) comprises 60 to 0 wt% of a propylene polymer (b) having a melting point of 120 to 170°C and a melt flow rate of 0.1 to 500 g/10 min, and 40 to 100 wt% of a propylene polymer (c) having a melting point of less than 120 °C or showing no melting points and having a melt flow rate of 0.1 to 500 g/10 min (wherein the total of the component (b) and the component (c) is 100 wt%).