BPA-Free Polyhydroxy Ether Coating for Food Containers
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Solution Overview
Problem
Existing coatings for food and beverage containers based on polyglycidyl ethers of bisphenol A pose health concerns due to potential endocrine-disrupting compounds, necessitating the development of coatings free from bisphenol A and its reaction products while maintaining commercially acceptable properties.
Innovation Solution
A coating composition using a polyhydroxy ether polymer prepared from reacting epichlorohydrin with a polyhydric phenol, specifically a phenol with a substituted phenylene ring, and a curing agent, which is free from detectable epoxy functionality, ensuring the absence of bisphenol A and its derivatives, and is applied to the interior surface of containers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyglycidyl ethers of bisphenol A are used as coating compositions, then excellent adhesion and coating properties are achieved, but endocrine-disrupting compounds are released into food or beverage
Solution Approach 1:
The patent extracts and removes the harmful bisphenol A component from the coating system while retaining the functional polyhydroxy ether polymer structure. This is achieved by using alternative phenolic compounds that do not contain bisphenol A, thereby eliminating the source of endocrine-disrupting compounds while maintaining coating performance
Solution Approach 2:
The patent uses alternative phenolic compounds that are safer and more suitable for food contact applications, replacing the problematic bisphenol A-based systems. These alternative polymers provide the necessary coating properties without the long-term health risks associated with BPA exposure
2Object-affected harmful factors
If biphenolic compounds with alkyl substitution are used to prepare polyhydroxy ethers, then the coating is free from bisphenol A, but steric hindrance deactivates hydroxyl group reactivity and limits coating properties
Solution Approach 1:
The patent changes the chemical parameters of the phenolic compound by selecting specific structures where alkyl groups are positioned at ortho and meta positions relative to phenolic hydroxyl groups. This structural modification reduces steric hindrance while maintaining bisphenol A-free status, enabling effective chain extension reactions
Solution Approach 2:
The patent applies local quality by strategically positioning alkyl substituents at specific locations (ortho and meta positions) on the phenylene ring. This localized substitution pattern minimizes interference with hydroxyl group reactivity while still providing the desired bisphenol A-free composition
3Ease of manufacture
If the percentage of biphenolic compound in polyhydroxy ether is limited due to poor reactivity, then steric hindrance is reduced, but coating properties become unacceptable
Solution Approach 1:
The patent optimizes the molecular weight and structural parameters of the polyhydroxy ether polymer to achieve the desired balance between reactivity and coating performance. By controlling the polymerization process and selecting appropriate phenolic compounds, the patent achieves both high reactivity and excellent coating properties
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 provides a coating that does not exhibit endocrine-disrupting activities and maintains excellent adhesion and performance, suitable for high-speed application and food contact, with the polyhydroxy ether polymer comprising at least 70% of the coating composition by weight, ensuring safety and effectiveness.
Implementation Method 1
reacting epichlorohydrin with a polyhydric phenol having the following structure (I)
Implementation Method 2
a curing agent for the polyhydroxy ether
Data Source
AI summary
The present invention relates to a package or a portion thereof having an interior food-contacting surface and a coating composition being substantially free of bisphenol A and reaction products thereof applied to the interior surface; wherein the coating composition comprises a polyhydroxy ether and a curing agent for the polyhydroxy ether and in which the polyhydroxy ether is prepared from reacting epichlorohydrin with a polyhydric phenol having the following structure (I), as shown in claim 1; where R1 is independently an organic group having a molecular weight of at least 15 Daltons or R1 can optionally join together with another R1 to form a fused aromatic ring that is similarly substituted with the R1 organic group; y = 4, x = 1 to 2; each of the arylene groups in structure (I) includes at least one R1 attached to the arylene ring at the ortho and/or meta position relative to the phenolic hydroxyl group; m is 0 to 1; R2 if present is a divalent organic group; n is 0 to 1 with the proviso that if n is 0, m is 0; the polyhydroxy ether having an Mn of from 2000 to 10,000 and containing at least 70 percent by weight of groups of the structure (II), as shown in claim 1, based on weight of the polyhydroxy ether.