Vibration Welding Polypropylene Elastomer Blend

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Solution Overview

Problem

The variability in weld characteristics such as strength and toughness when welding different polymeric materials poses a challenge, as existing techniques struggle to consistently produce high-quality welds with desirable properties like structural integrity and aesthetics.

Innovation Solution

A polymeric blend composition comprising a highly crystalline thermoplastic polyolefin, such as polypropylene, combined with a polyolefin elastomer, is used for vibration welding, where the thermoplastic polyolefin has a crystallinity greater than 40% and the elastomer is present in a specific weight range, along with optional additives, to form strong and durable welds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional polymeric materials are used for welding, then welding can be performed on various materials, but the weld characteristics such as strength and toughness vary significantly and cannot be consistently controlled

Engineering Contradiction:
Improveconsistency of weld characteristicsVSAvoidweld strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies parameter changes by precisely controlling the crystallinity of the thermoplastic polyolefin component (requiring greater than 40% crystallinity) and specifying the weight ratio of polyolefin elastomer (10% to 50%). These parameter specifications ensure consistent weld characteristics while maintaining high weld strength, directly resolving the contradiction between reliability and strength.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite polymeric blend composition consisting of thermoplastic polyolefin and polyolefin elastomer in specific proportions. This composite material combines the structural integrity provided by the crystalline thermoplastic with the toughness contributed by the elastomer, achieving both high weld strength and consistent performance across different welding applications.

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If polymeric materials with high weldability are used, then ease of welding is improved, but other desirable properties such as structural integrity, ductility, and scratch resistance may be compromised

Engineering Contradiction:
Improveease of weldingVSAvoidstructural integrity
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent maintains ease of welding through appropriate melt flow characteristics enabled by the polyolefin elastomer content (10%-50%), while simultaneously achieving high structural integrity through the thermoplastic polyolefin's high crystallinity (>40%). This parameter balance allows the material to be both easy to weld and structurally sound.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The composite blend of thermoplastic polyolefin and polyolefin elastomer provides a synergistic effect where the thermoplastic component ensures ease of welding and structural integrity, while the elastomer component enhances toughness and ductility. This composite approach resolves the contradiction between ease of manufacture and structural strength.

Inventive Principle:
Principle #40Composite materials

3Strength

If thermoplastic polyolefin with high crystallinity is used, then weld strength and structural integrity are improved, but the material may become more difficult to process and weld

Engineering Contradiction:
Improveweld strengthVSAvoidease of welding
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent balances the high crystallinity requirement (>40% for weld strength) with adequate melt flow properties by controlling the polyolefin elastomer content (10%-50%). This parameter optimization ensures that even with high crystallinity, the material remains processable and easy to weld while maintaining high weld strength.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The composite material combines high-crystallinity thermoplastic polyolefin (providing strength and rigidity) with polyolefin elastomer (providing processability and flexibility). This composition resolves the contradiction between achieving high weld strength through high crystallinity and maintaining ease of welding through adequate melt flow.

Inventive Principle:
Principle #40Composite materials

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 results in welds with enhanced strength, toughness, and aesthetic properties, including scratch resistance, while maintaining structural integrity, by balancing the thermoplastic polyolefin and polyolefin elastomer content, thereby addressing the variability issues in existing welding methods.

Implementation Method 1

heating and softening at least a portion of the polymeric composition of the first member

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

heating and softening at least a portion of the polymeric composition

Methodology Applied
Scientific EffectPhase change: Phase Change

Data Source

PatentEP2125333B1Welding of a polymeric material and structures formed thereby
Publication Date: 2016.10.26 DOW GLOBAL TECHNOLOGIES LLC
  • EP2125333B1 patent drawingFigure 1~1A
  • EP2125333B1 patent drawingFigure 2~2A
  • EP2125333B1 patent drawingFigure 3

AI summary

The present invention is directed to welding of a polymeric material and structures formed by such welding. The material is preferably a thermoplastic material that is a blend of one or more thermoplastic polyolefins and one or more elastomers. One preferred welding technique is vibration welding.