Crosslinkable Composition for EVOH Retort Resistance
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Solution Overview
Problem
Existing crosslinkable compositions for polyvinyl alcohol type polymers, such as EVOH, face issues with bleeding out of crosslinking agents during high-temperature and high-humidity retorting processes, leading to compromised retort resistance and interlayer adhesiveness in multilayered structures, particularly in food packaging applications.
Innovation Solution
A crosslinkable composition comprising a polymer with a solubility parameter (SP) value of 9.5 to 16.5 cal/cm^3 and a crosslinking agent with polar groups containing oxygen and nitrogen atoms, but not in aromatic rings, and two or more polymerizable groups, which improves miscibility and prevents bleeding out, enhancing retort resistance and interlayer adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional crosslinking agents (e.g., triallyl cyanurate, triallyl isocyanurate, polyfunctional allylic compounds) are used to crosslink EVOH, then crosslinking efficiency is improved, but bleeding out of the crosslinking agent occurs during retorting, compromising hygienic safety and interlayer adhesiveness
Solution Approach 1:
The patent changes the chemical structure parameters of the crosslinking agent by introducing polar groups (carboxyl, hydroxyl, amide, carbonyl) to enhance compatibility with EVOH. The crosslinking agent formula specifies polar groups containing oxygen and nitrogen atoms not in aromatic rings, which fundamentally alters the chemical properties to prevent bleeding while maintaining crosslinking efficiency
Solution Approach 2:
The patent creates a composite crosslinking system by combining multiple functional groups (carboxyl, hydroxyl, amide, carbonyl) within the crosslinking agent structure. This composite approach ensures both high crosslinking efficiency and excellent compatibility with EVOH, preventing bleeding out during retorting
2Reliability
If EVOH is crosslinked using conventional crosslinking agents, then retort resistance is improved, but interlayer adhesiveness in multilayered structures deteriorates due to bleeding out
Solution Approach 1:
The patent modifies the crosslinking agent's chemical parameters to include polar groups that enhance interfacial compatibility between EVOH layers. The carboxyl, hydroxyl, amide, and carbonyl groups create strong intermolecular interactions that prevent bleeding and maintain interlayer adhesiveness during high-temperature retorting
3Reliability
If specialized extruders are used to modify EVOH as described in Patent Document 5, then crosslinking performance is improved, but device complexity and versatility are reduced
Solution Approach 1:
The patent introduces a specially designed crosslinking agent as an intermediary substance that enables crosslinking through conventional extrusion equipment. The crosslinking agent acts as a mediator between EVOH molecules, facilitating crosslinking reactions without requiring specialized extruders, thus maintaining equipment versatility while achieving high crosslinking performance
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 effectively suppresses bleeding out of the crosslinking agent, resulting in a crosslinked product with superior retort resistance and interlayer adhesiveness, suitable for use in multilayered structures like food packaging containers, while eliminating the need for specialized equipment for production.
Implementation Method 1
the crosslinking agent (B) has a solubility parameter (SP value) of no less than 11.0 (cal/cm3)1/2, and the difference between an SP value of the polymer (A) and an SP value of the crosslinking agent (B) is no greater than 2 (cal/cm3)1/2
Implementation Method 2
irradiating with an electron beam to permit crosslinking of EVOH
Implementation Method 3
crosslinking of EVOH
Data Source
AI summary
Providing a crosslinkable composition and a crosslinking agent is objected to, which are capable forming a crosslinked product that is superior in retort resistance, with suppressed bleeding out from the crosslinked product, and that has favorable interlayer adhesiveness when formed into a multilayered structure crosslinked product. The present invention provides a crosslinkable composition containing (A) a polymer having an SP value of no less than 9.5 (cal/cm3)1/2 and no greater than 16.5 (cal/cm3)1/2, and (B) a crosslinking agent having one or more polar groups that include an oxygen atom and a nitrogen atom not constituting an aromatic ring, and two or more polymerizable groups. The difference between the SP value of the polymer (A) and the SP value of the crosslinking agent (B) is preferably no greater than 2 (cal/cm3)1/2, and more preferably no greater than 1 (cal/cm3)1/2. A decomposition temperature of the crosslinking agent (B) is preferably no less than 240°C, and a melting point of the crosslinking agent (B) is preferably no greater than 220°C.