Multilayer EVOH Tube Jacket for Thin-Wall Diffusion Barrier
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Solution Overview
Problem
Plastic tubes used for cosmetics and pharmaceutical products face issues with diffusion of volatile constituents through the material, leading to product degradation and reduced effectiveness over time, while attempts to minimize weight for cost and environmental impact make the tubes potentially unstable and prone to further diffusion.
Innovation Solution
A multilayer tube jacket with an ethylene-vinyl alcohol copolymer (EVOH) barrier layer having an ethylene content of <35 mol % and a thickness ≤25 μm, combined with bonding layers and polyolefin outer and inner layers, to achieve both lightweight stability and effective barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the tube jacket is made thinner to reduce weight, then weight and material consumption are reduced, but the tube becomes potentially unstable and more prone to diffusion of tube contents
Solution Approach 1:
The tube jacket is divided into multiple functional layers: polyolefin outer layer, bonding layer, EVOH barrier layer, bonding layer, and polyolefin inner layer. Each layer serves a specific function - the polyolefin layers provide mechanical strength and stability, the bonding layers ensure adhesion, and the thin EVOH layer provides superior barrier properties. This segmentation allows the use of a thin barrier layer (5-25 μm) without compromising overall tube stability.
Solution Approach 2:
The invention uses a composite multilayer structure combining different materials with complementary properties. Polyolefin provides mechanical strength and chemical resistance, while EVOH provides exceptional barrier properties against diffusion. The bonding layers (e.g., polyamide or polyethylene terephthalate) ensure strong adhesion between layers. This composite approach achieves both weight reduction and maintained reliability.
2Quantity of substance
If a thin barrier layer is used to minimize weight, then material consumption is reduced, but the barrier effect against diffusion may be compromised
Solution Approach 1:
The invention specifies precise parameters for the EVOH barrier layer: ethylene content of 20-35 mol% and thickness of 5-25 μm. These parameter optimizations ensure that the thin layer provides sufficient barrier effect. The controlled ethylene content balances barrier performance with processability and adhesion characteristics.
Solution Approach 2:
Bonding layers are introduced as intermediary layers between the EVOH barrier layer and the polyolefin layers. These bonding layers (such as polyamide or polyethylene terephthalate) ensure strong adhesion and prevent delamination, allowing the use of a thin barrier layer without compromising the integrity of the multilayer structure. The bonding layers mediate the interface between materials with different adhesion characteristics.
3Strength
If bonding layers are added to ensure adhesion between barrier layer and polyolefin, then mechanical stability is improved, but device complexity increases
Solution Approach 1:
The bonding layers serve multiple functions simultaneously: they provide strong adhesion between the EVOH barrier layer and polyolefin layers, prevent delamination during processing and use, and facilitate heat transfer during welding processes. This multi-functionality justifies the additional layer despite increased structural complexity.
Solution Approach 2:
The bonding layers use relatively thin layers (5-25 μm each) of materials that are cost-effective and easily integrated into the extrusion process. While they add layers to the structure, the bonding layers are thin and use materials that are readily available and compatible with standard tube manufacturing processes, minimizing the practical impact of increased complexity.
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 ensures a sufficient barrier effect to maintain product integrity for at least 1 year, while minimizing weight and material usage, with the barrier layer maintaining its properties even at reduced thickness, and the bonding layers enhancing mechanical stability.
Implementation Method 1
the barrier layer consists of an ethylene-vinyl alcohol copolymer (EVOH)... there is the risk that the products stored in the tube or their volatile constituents will diffuse through the plastic
Implementation Method 2
Since ethylene-vinyl alcohol copolymers do not form a mechanically strong bond with certain polyolefins, it is advantageous or necessary to provide bonding layers or adhesion promoter layers between the barrier layer and the polyolefin layers
Data Source
AI summary
A tube for receiving a liquid or pasty product comprising a multilayered tube jacket, the tube jacket having one or more outer layer(s) made of polyolefin, one or more inner layer(s) made of polyolefin and a barrier layer arranged between the outer layer(s) and the inner layer(s), wherein the barrier layer consists of an ethylene-vinyl alcohol copolymer (EVOH), and wherein the ethylene-vinyl alcohol copolymer of the barrier layer has an ethylene content of <35 mol % and the thickness of the barrier layer is ≤25 μm.