Multilayered Structure Production Using EVOH Regrind

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Solution Overview

Problem

The reuse of multilayered structures containing polyolefin and EVOH layers in melt molding is hindered by thermal degradation, gelation, phase separation, and uneven cloudiness, leading to supply instability and poor workability.

Innovation Solution

A method involving the production of a multilayered structure using a regrind with a resin composition containing polyolefin, saponified ethylene-vinyl acetate copolymers, and an antistatic agent, where the ethylene content and degree of saponification are optimized, and the regrind is sieved to eliminate fine particles, enhancing compatibility and dispersibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If regrind of multilayered structure is reused in melt molding, then waste reduction and economic efficiency are improved, but thermal degradation occurs causing gelation and poor workability

Engineering Contradiction:
Improvewaste reductionVSAvoidworkability
Core Design Contradiction:
Loss of substanceVSReliability

Solution Approach 1:

A master batch containing saponified ethylene-vinyl acetate copolymer and antistatic agent is introduced as an intermediary substance during melt molding of the regrind. This master batch acts as a mediator that prevents direct thermal degradation of the regrind, suppressing gelation and degraded material adhesion to the extruder, thereby enabling continuous production while maintaining waste reduction benefits

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The saponified ethylene-vinyl acetate copolymer and antistatic agent are pre-blended into a master batch before being mixed with the regrind. This preliminary preparation ensures that protective components are already distributed and activated before the regrind undergoes melt molding, preventing thermal degradation from the outset

Inventive Principle:
Principle #10Preliminary action

2Productivity

If regrind is reused in multilayered structure production, then economic efficiency is improved, but degraded material adheres inside extruder reducing continuous production capability

Engineering Contradiction:
Improveeconomic efficiencyVSAvoidcontinuous production duration
Core Design Contradiction:
ProductivityVSDuration of action of stationary object

Solution Approach 1:

The master batch containing saponified ethylene-vinyl acetate copolymer serves as a protective intermediary that coats and separates degraded material particles in the regrind, preventing them from adhering to the extruder interior. This allows continuous production to proceed without interruption from material buildup

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

Fine particles and degraded material are removed from the regrind through sieving with a mesh size of 0.15 mm or larger before mixing with the master batch. This extraction step eliminates the problematic components that would otherwise cause adhesion and interrupt continuous production

Inventive Principle:
Principle #2Taking out (Extraction)

3Loss of substance

If regrind is used in multilayered structure production, then waste reduction is achieved, but fish eye and phase separation foreign matter are generated in molded product

Engineering Contradiction:
Improvewaste reductionVSAvoidproduct quality
Core Design Contradiction:
Loss of substanceVSManufacturing precision

Solution Approach 1:

Fine particles with diameter of 0.15 mm or smaller are extracted from the regrind through sieving before processing. These fine particles are the primary source of fish eye and phase separation defects, and their removal significantly improves product quality while maintaining waste reduction benefits

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The saponified ethylene-vinyl acetate copolymer in the master batch acts as a compatibilizer that prevents phase separation between different resin components. This intermediary substance ensures uniform dispersion and eliminates fish eye defects, maintaining high manufacturing precision

Inventive Principle:
Principle #24Intermediary (Mediator)

4Productivity

If multilayered structure is produced continuously using regrind, then productivity is improved, but uneven cloudiness occurs and worsens reducing supply stability

Engineering Contradiction:
Improvecontinuous production capabilityVSAvoidsupply stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The saponified ethylene-vinyl acetate copolymer in the master batch serves as a dispersing intermediary that maintains uniform distribution of regrind particles throughout continuous production. This prevents aggregation and cloudiness, ensuring consistent composition and supply stability over extended production periods

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The master batch is continuously fed together with the regrind during melt molding, ensuring that the protective and dispersing action is maintained throughout the entire continuous production process. This continuous intervention prevents cloudiness from developing over time

Inventive Principle:
Principle #20Continuity of useful action

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

This approach suppresses the generation and worsening of uneven cloudiness, improving the stability and workability of the multilayered structure, enabling continuous and efficient melt molding.

Implementation Method 1

a saponified ethylene-vinyl acetate copolymer (H) having an ethylene content of from 20 to 65 mol % and having a degree of saponification of vinyl acetate units of 96% or more

Methodology Applied
Scientific EffectCompatibility enhancement through copolymer structure:

Implementation Method 2

gelation occurs due to thermal degradation during the melt molding

Methodology Applied
Scientific EffectThermal degradation:

Implementation Method 3

obtaining a multilayered structure (F) having a layer of a resin composition (E) made by melt kneading the regrind (C) and a polyolefin (D)

Methodology Applied
Scientific EffectMelt molding:

Implementation Method 4

generating a phase separation foreign matter (die build-up) in a molded product thus obtained

Methodology Applied
Scientific EffectPhase separation:

Data Source

PatentUS9457545B2Process for production of multilayered structure
Publication Date: 2016.10.04 KURARAY CO LTD

AI summary

Provided is a method of producing a multilayered structure, comprising the steps of: obtaining a regrind (C) by grinding a multilayered structure (B) having a layer of a resin composition (A), followed by sieving; and obtaining a multilayered structure (F) having a layer of a resin composition (E) made by melt kneading the regrind (C) and a polyolefin (D), wherein the resin composition (A) contains a polyolefin (G), a saponified ethylene-vinyl acetate copolymer (H) having an ethylene content of from 20 to 65 mol % and having a degree of saponification of vinyl acetate units of 96% or more, a saponified ethylene-vinyl acetate copolymer (I) having an ethylene content of from 68 to 98 mol % and having a degree of saponification of vinyl acetate units of 20% or more, and an antistatic agent (J), and a mass ratio (H/I) is from 0.1 to 10. According to this, using a regrind of a multilayered structure having a resin composition layer containing a polyolefin and an EVOH enables to provide a method of producing a multilayered structure that is suppressed in generation and worsening of uneven cloudiness.