Polyamide-Modified Polyolefin Barrier Layer for Gas Permeation
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Solution Overview
Problem
Existing injection-molded containers made from polyolefins lack sufficient barrier properties against gases like oxygen, leading to unsuitable preservation conditions for food and drugs, especially under high-temperature conditions, and often suffer from poor appearance and heat resistance due to inadequate adhesion between layers and the use of expensive modified polyolefins.
Innovation Solution
A multilayer injection molded article structure incorporating a specific polyamide resin with a diamine unit derived from m-xylylenediamine and a dicarboxylic acid unit from C4 to C20 α,ω-linear aliphatic dicarboxylic acid and isophthalic acid, combined with modified polyolefins, which enhances barrier properties, adhesion, and heat resistance while maintaining a favorable appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If polyolefins are used as the main material for injection molded containers, then flowability and heat resistance during molding are improved, but barrier property against gases deteriorates
Solution Approach 1:
The invention uses a composite material system consisting of a polyolefin matrix (providing heat resistance and processability) combined with a barrier layer containing polyamide resin and inorganic filler particles (providing gas barrier property). This composite structure allows each material to contribute its advantageous properties to the final container.
Solution Approach 2:
The barrier layer is positioned specifically at the portion of the container wall where gas barrier function is most critical, rather than requiring the entire container to have enhanced barrier properties. This localized approach maintains overall heat resistance while providing targeted gas protection.
2Object-affected harmful factors
If barrier material such as polyamide is blended in polyolefins to improve barrier property, then gas barrier property is improved to some extent, but appearance deteriorates due to local presence of polyamides near surface
Solution Approach 1:
The invention separates the barrier function from the surface layer by creating a distinct barrier layer positioned beneath the outer surface. The inorganic filler particles are distributed within this barrier layer rather than at the surface, allowing the surface to maintain its aesthetic quality while the underlying layer provides gas barrier protection.
Solution Approach 2:
The invention introduces an inorganic filler component as an intermediary substance within the barrier layer. This filler acts as a barrier to gas permeation while being distributed in a way that does not affect the surface appearance, mediating between the need for barrier property and surface quality.
3Strength
If multilayer structure with adhesive layer is used to ensure adhesion between polyolefin and barrier layer, then adhesion is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention extracts and eliminates the adhesive layer from the multilayer structure by using a compatibilizer during the injection molding process. The compatibilizer enables direct bonding between the polyolefin layer and barrier layer without requiring a separate adhesive layer, thereby simplifying the overall structure.
Solution Approach 2:
The invention changes the chemical parameters of the interface between layers by introducing a compatibilizer that modifies the surface properties of the polyolefin or barrier layer. This parameter change enables adequate adhesion without requiring additional adhesive materials or complex layering.
4Strength
If modified polyolefin is used to enhance adhesion between polyolefin layer and barrier layer, then adhesion is improved, but heat resistance deteriorates due to addition of modified polyolefin
Solution Approach 1:
The invention introduces a compatibilizer as an intermediary substance that facilitates adhesion between the polyolefin layer and barrier layer. This compatibilizer acts as a chemical bridge, enabling strong interfacial bonding without requiring the modification of the polyolefin's thermal properties, thereby preserving heat resistance.
Solution Approach 2:
Instead of modifying the polyolefin itself to improve adhesion, the invention uses a separate compatibilizer compound that replicates the adhesion-enhancing function without affecting the polyolefin's heat resistance properties. The compatibilizer copies the necessary bonding function while leaving the original polyolefin's thermal characteristics intact.
Data Source
AI summary
A method of providing an oxygen barrier for a product includes placing a product in an injection molded article which includes 10 to 60% by mass of a polyamide resin (A) and 40 to 90% by mass of a mixed polyolefin (E), wherein the polyamide resin (A) includes a diamine unit 70 mol % or more of which is one or more m-xylylenediamine units and a dicarboxylic acid unit 70 mol % or more of which is one or more dicarboxylic acid units including a C4 to C20 α,ω-linear aliphatic dicarboxylic acid and isophthalic acid at a molar ratio of from 30:70 to 100:0, the mixed polyolefin (E) includes 40 to 100% by mass of a polyolefin (C) and 0 to 60% by mass of a modified polyolefin (B), and at least a portion of the polyamide resin (A) is dispersed in a layered state.