EVOH Resin Surface Roughness Control for Torque Reduction
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Solution Overview
Problem
Conventional EVOH resin pellets exhibit high surface roughness and friction, leading to increased torque during processing, which complicates the production of films and multilayer structures, necessitating improved surface uniformity and reduced torque output.
Innovation Solution
The development of an ethylene-vinyl alcohol copolymer (EVOH) resin composition with controlled surface roughness parameters, including root mean square gradient (Sdq) between 0.0005 and 13, and the incorporation of boron and alkali metal compounds, along with slip agents, to enhance processing efficiency and film uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional EVOH resin pellets are used with high surface roughness, then the resin maintains its inherent oxygen barrier properties, but the friction between pellets increases leading to extremely high torque during processing
Solution Approach 1:
The invention changes the surface roughness parameter of EVOH pellets by controlling the storage conditions (temperature and humidity) to reduce surface roughness from conventional high levels to Sdq ≤ 13 μm. This parameter change reduces friction between pellets and between pellets and screw, thereby reducing torque during processing while maintaining the resin's oxygen barrier properties
Solution Approach 2:
The invention replaces mechanical surface treatment methods with a storage-condition-based approach. By controlling storage temperature (20-40°C) and humidity (40-70% RH) over time (1-12 months), the surface roughness is reduced without mechanical intervention, avoiding additional mechanical stress on the pellets
2Strength
If conventional EVOH resin pellets with high surface roughness are used, then the resin maintains its structural integrity, but the surface uniformity of the resulting film deteriorates
Solution Approach 1:
The invention changes the surface roughness parameter of the resin pellets through controlled storage conditions, which directly improves film surface uniformity. The reduced surface roughness (Sdq ≤ 13 μm) of pellets translates to better surface uniformity in the extruded film, achieving Sa ≤ 0.5 μm and Sdq ≤ 1.3 μm without compromising structural integrity
3Ease of operation
If the surface roughness of EVOH pellets is reduced to improve processing, then the torque output decreases, but additional control of storage conditions and additives is required
Solution Approach 1:
The invention uses storage condition parameters (temperature, humidity, time) to control surface roughness and torque. By establishing specific ranges for these parameters, the method provides a systematic approach to reducing torque while managing the complexity through defined control limits
Solution Approach 2:
The invention introduces storage conditions as an intermediary between the resin's inherent properties and its processing behavior. The storage environment acts as a mediator that modifies surface roughness, which in turn affects torque, providing an indirect but effective control mechanism
Data Source
AI summary
The present invention relates to an ethylene-vinyl alcohol copolymer (EVOH) resin composition, an EVOH film formed therefrom, and a multilayer structure containing the same. The surface roughness of the EVOH resin composition is the root mean square gradient (Sdq) between 0.0005 and 13. The EVOH of the invention can reduce the torque output during processing, and make the appearance of the EVOH film highly uniform.