Ethylene Copolymer Plastisol Composition for Low-Migration PVC

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Solution Overview

Problem

Conventional liquid plasticizers used in PVC plastisols have low molecular weights, leading to migration and evaporation issues, resulting in brittle PVC products over time, and existing high molecular weight plasticizers face challenges in processing and stability against aging and UV exposure.

Innovation Solution

A free-flowing plasticized halogenated polymer plastisol composition is developed, comprising a combination of high molecular weight solid ethylene copolymer plasticizers and low molecular weight liquid plasticizers, with the ethylene copolymer being miscible with the halogenated polymer, and the process involves mixing these plasticizers with a nonporous halogenated polymer powder to create a stable and flexible PVC product.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional low molecular weight liquid plasticizers are used, then the PVC becomes flexible and processable, but the plasticizer migrates and evaporates over time causing the product to become brittle

Engineering Contradiction:
Improveflexibility and processabilityVSAvoidlong-term stability against migration and evaporation
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention uses a composite plasticizer system combining low molecular weight liquid plasticizers with high molecular weight polymeric plasticizers (polyester polyols with molecular weights of 10,000-100,000). The liquid plasticizer provides initial flexibility and processing, while the polymeric plasticizer remains stationary and prevents migration and evaporation, creating a synergistic effect that resolves the contradiction between ease of operation and long-term reliability.

Inventive Principle:
Principle #40Composite materials

2Reliability

If high molecular weight polymeric plasticizers are used, then migration and evaporation are reduced, but processing difficulty and instability against aging and UV increase

Engineering Contradiction:
Improveresistance to migration and evaporationVSAvoidprocessing stability and resistance to aging
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The invention merges the advantages of both low and high molecular weight plasticizers into a single composite system. The low molecular weight plasticizer ensures good processing and initial flexibility, while the high molecular weight polymeric plasticizer provides long-term stability and prevents migration. This combination resolves the contradiction by allowing each component to perform its optimal function without the drawbacks of using either alone.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If high molecular weight polymeric plasticizers are used, then plasticizer migration is reduced, but the product shows increased fragility and reduced mechanical properties

Engineering Contradiction:
Improveresistance to migrationVSAvoidmechanical properties and flexibility
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention changes the molecular weight parameter of the plasticizer system by using a broad distribution including both low molecular weight (for flexibility) and high molecular weight (for migration resistance) components. The polymeric plasticizers have molecular weights specifically selected in the range of 10,000-100,000 to optimize the balance between migration resistance and maintaining mechanical properties, resolving the contradiction between reliability and strength.

Inventive Principle:
Principle #35Parameter changes

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 modified plasticizer composition significantly reduces plasticizer migration, enhances chemical resistance, mechanical properties, and improves aging stability, producing flexible PVC products with improved durability and resistance to punctures and tears.

Implementation Method 1

a high molecular weight solid ethylene copolymer plasticizer for halogenated polymer that is miscible with the halogenated polymer

Methodology Applied
Scientific EffectMiscibility:

Implementation Method 2

the solid ethylene-containing copolymer plasticizer is soluble in the liquid plasticizer

Methodology Applied
Scientific EffectSolubility: Solvation

Implementation Method 3

Above the Tg for the composition, the small PVC particles begin to absorb the plasticizer molecules

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentUS10030132B2Ethylene copolymer-modified plastisol
Publication Date: 2018.07.24 DOW GLOBAL TECHNOLOGIES LLC

AI summary

Provided herein is a plastisol composition comprising a halogenated polymer and an ethylene carbon monoxide copolymer that is dispersed or dissolved in a liquid plasticizer. A process for producing the plastisol composition is further provided.