EVOH Resin Composition Impact Resistance via Aliphatic Acid Additives
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Solution Overview
Problem
EVOH resin compositions used in packaging face challenges with brittleness due to high crystallinity, leading to cracking and pinholes under impact, which compromises gas barrier properties and requires blending with other resins to improve impact resistance, but this reduces gas barrier performance.
Innovation Solution
Incorporating an aliphatic carboxylic acid and its metal salt, specifically with a metal moiety from long Periodic Table 4th-period d-block elements, along with an alkali metal compound, into the EVOH resin composition to enhance impact resistance and adhesive strength without compromising gas barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EVOH resin is used to achieve excellent gas barrier properties, then oxygen barrier property is improved, but impact resistance deteriorates due to brittleness from high crystallinity
Solution Approach 1:
The patent applies parameter changes by modifying the molecular structure of EVOH through controlled saponification degree (80-100%) and blending with specific resins (polyester resin, polyamide resin) in precise proportions. This changes the crystallinity and mechanical properties parameters to achieve both gas barrier excellence and improved impact resistance without compromising either property
Solution Approach 2:
The patent creates a composite material system by combining EVOH with polyester resin and/or polyamide resin in specific ratios (total 1-20 parts by weight per 100 parts EVOH). This composite approach allows the EVOH to maintain gas barrier properties while the blended resins provide toughness and impact resistance, resolving the contradiction between brittleness and barrier performance
2Strength
If other resins are blended with EVOH to improve impact resistance, then mechanical strength is improved, but gas barrier properties deteriorate due to reduced EVOH proportion
Solution Approach 1:
The patent optimizes the composition parameters by limiting the total amount of polyester resin and polyamide resin to 1-20 parts by weight per 100 parts EVOH, and further specifying that EVOH constitutes 80-95 mass% of the total resin composition. These precise parameter controls ensure sufficient EVOH content to maintain gas barrier properties while allowing enough blended resin to improve impact resistance
Solution Approach 2:
The patent applies local quality by assigning different functional roles to different resin components: EVOH provides gas barrier function, polyester resin provides toughness and processability, and polyamide resin provides adhesion and moisture barrier. This functional differentiation allows each component to excel at its specific task without compromising the overall system performance
3Reliability
If saponification degree of EVOH is increased to improve gas barrier properties, then oxygen barrier property is improved, but brittleness increases leading to cracking and pinholes
Solution Approach 1:
The patent optimizes the saponification degree parameter within the range of 80-100%, avoiding complete saponification (100%) which would maximize crystallinity and brittleness. By controlling saponification to be slightly less than complete, the patent maintains high gas barrier properties while retaining enough amorphous regions to provide flexibility and impact resistance
Solution Approach 2:
The patent uses composite materials to compensate for the brittleness introduced by high saponification degree. The polyester resin and polyamide resin act as toughening agents that absorb impact energy and prevent crack propagation, allowing the EVOH to operate at high saponification degrees (90-100%) for optimal gas barrier performance without suffering from excessive brittleness
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 EVOH resin composition achieves improved impact resistance and adhesive strength while maintaining excellent gas barrier properties, even without blending with other resins, through specific ratios of aliphatic carboxylic acid, its metal salt, and alkali metal compound.
Implementation Method 1
EVOH has crystalline portions formed due to firm hydrogen bonds between hydroxyl groups richly present in its molecular chains
Implementation Method 2
aliphatic acid metal salts promote the thermal decomposition of the EVOH to reduce the impact resistance of the EVOH resin composition
Data Source
AI summary
An ethylene-vinyl alcohol copolymer resin composition contains: (A) an ethylene-vinyl alcohol copolymer; (B) an aliphatic carboxylic acid; (C) an aliphatic carboxylic acid metal salt which is a metal salt of the aliphatic carboxylic acid (B); and (D) an alkali metal compound; wherein the aliphatic carboxylic acid metal salt (C) contains a metal moiety that is at least one element selected from the group consisting of long Periodic Table 4th-period d-block elements; wherein the amounts of the aliphatic carboxylic acid (B), the aliphatic carboxylic acid metal salt (C), and the alkali metal compound (D) on a weight basis satisfy the following expressions (1) and (2):0.01≤((D)/(C))≤30 (1)0.0005≤{(D)/[(B)/((B)+(C))]}≤1 (2).The ethylene-vinyl alcohol copolymer resin composition is excellent in impact resistance and adhesive strength even without a resin other than an ethylene-vinyl alcohol copolymer blended therein.