Polyethylene Chemical Container Surface Control for Low Elution

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Solution Overview

Problem

Existing polyethylene resin containers for high purity chemicals fail to adequately suppress elution of fine particles and metal impurities, particularly in small-sized containers, due to insufficient control of ash content and catalyst component residues, leading to contamination issues.

Innovation Solution

A polyethylene resin container with a developed interfacial area ratio of 1.10 or less, maximum roughness Rz of 10.0 µm or less, and specific molecular weight and density properties, produced using a two-step polymerization process with a high activity catalyst, to minimize fine particle and metal impurity elution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a tetrafluoroethylene-based copolymer is used for container material, then chemical purity is improved, but manufacturing cost increases

Engineering Contradiction:

Improvechemical purityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameters by specifying precise density (0.940-0.970 g/cm³) and molecular weight ratio (Mw/Mn: 5.0-7.9) ranges for polyethylene resin, optimizing these parameters to achieve chemical purity comparable to expensive tetrafluoroethylene copolymers while maintaining cost-effectiveness

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite solution by combining polyethylene resin with specific catalyst component control (ash content ≤ 50 ppm) and surface treatment (developed interfacial area ratio), achieving high purity through material composition optimization rather than using inherently more expensive materials

Inventive Principle:

Principle #40Composite materials

2Reliability

If polyethylene resin with conventional properties is used, then fine particle elution increases, but manufacturing simplicity is maintained

Engineering Contradiction:

Improvefine particle suppressionVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces specific parameter controls including density (0.940-0.970 g/cm³), molecular weight ratio (Mw/Mn: 5.0-7.9), and developed interfacial area ratio (≤ 1.10), transforming the manufacturing process from simple to precisely controlled while achieving superior fine particle suppression

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary actions by controlling catalyst component residues (ash content ≤ 50 ppm) and low molecular weight components (≤ 1000 ppm) during resin synthesis, preventing fine particle generation before the container is even used

Inventive Principle:

Principle #10Preliminary action

3Reliability

If container surface is made smoother, then fine particle elution is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improvefine particle elution controlVSAvoidsurface finish precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent quantifies surface smoothness using developed interfacial area ratio (≤ 1.10) and maximum roughness Rz (≤ 10.0 μm), providing measurable parameters that guide manufacturing to achieve optimal surface finish for minimizing fine particle elution

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP4685064A1Polyethylene resin container for high-purity chemical

Publication Date: 2026.01.28 TOSOH CORP

AI summary

To provide a container for high purity chemicals made of a polyethylene resin, from which eluates derived from the polyethylene resin and elution of contaminants such as degraded substances into a chemical stored in the container are suppressed as far as possible. A container for high purity chemicals, which is made of a polyethylene resin, and the inner surface of which has a developed interfacial area ratio of 1.10 or less.