Propylene-Based Polymer Composition for Pressure-Sensitive Adhesives

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Solution Overview

Problem

Propylene-based polymers used as pressure-sensitive adhesives often contaminate adherends over long periods and have poor pellet handling properties, leading to blocking issues and reduced adhesion performance.

Innovation Solution

Developing propylene-based polymers with a specific composition of 65-80 mol% propylene, 5-10 mol% ethylene, and 15-25 mol% C4-20 α-olefin units, which exhibit a heat of crystal fusion of 5-45 J/g, high triad tacticity, and suitable crystallinity, along with propylene-based polymer compositions that improve adhesion and prevent contamination when used as pressure-sensitive adhesives.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If propylene-based polymer is used as pressure-sensitive adhesive, then initial adhesion is achieved, but contamination occurs over long term

Engineering Contradiction:
Improveinitial adhesionVSAvoidcontamination of adherend
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the compositional parameters of the propylene-based polymer by incorporating specific amounts of ethylene (5-10 mol%) and C4-20 α-olefin (15-25 mol%) units, and controlling the heat of crystal fusion (5-45 J/g). This parameter optimization resolves the contradiction by achieving both good initial adhesion and long-term non-contamination performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite propylene-based polymer structure containing multiple monomer units (propylene, ethylene, and C4-20 α-olefin) with specific compositional ratios. This composite structure combines the adhesive properties of propylene with the flexibility and stability provided by ethylene and α-olefin copolymer units, resolving the contradiction between initial adhesion and long-term non-contamination.

Inventive Principle:
Principle #40Composite materials

2Reliability

If propylene-based polymer is used as pressure-sensitive adhesive, then adhesion performance is achieved, but pellet handling properties deteriorate due to blocking

Engineering Contradiction:
Improveadhesion performanceVSAvoidpellet handling properties
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent optimizes the thermal parameters of the polymer by controlling the heat of crystal fusion to 5-45 J/g through specific copolymer composition. This parameter change prevents pellet blocking during storage and handling while maintaining the adhesion performance required for pressure-sensitive adhesive applications.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If propylene-based polymer with high crystallinity is used, then handling properties improve, but adhesion performance deteriorates

Engineering Contradiction:
Improvehandling propertiesVSAvoidadhesion performance
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent precisely controls the heat of crystal fusion parameter to 5-45 J/g through optimized copolymer composition (65-80 mol% propylene, 5-10 mol% ethylene, 15-25 mol% C4-20 α-olefin). This parameter optimization achieves the balance between handling properties and adhesion performance by preventing both pellet blocking and adhesion failure.

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 propylene-based polymers and compositions demonstrate excellent handling properties, preventing blocking and maintaining desired initial adhesion over long periods, making them suitable for surface protection films and enhancing the pressure-sensitive adhesion of other thermoplastic resins or elastomers.

Implementation Method 1

the propylene-based polymer (A) has a heat of crystal fusion of 5 to 45 J/g as measured by DSC

Methodology Applied
Scientific EffectCrystallisation: Crystallisation

Implementation Method 2

the propylene-based polymer (A) has a heat of crystal fusion of 5 to 45 J/g as measured by DSC

Methodology Applied
Scientific EffectPhase Change: Phase Change

Data Source

PatentUS8288479B2Propylene-based polymer, propylene-based polymer composition, pellet and pressure-sensitive adhesive
Publication Date: 2012.10.16 MITSUI CHEMICALS INC

AI summary

Propylene-based polymers (A) are provided which, when used as pressure-sensitive adhesives to various adherends, show a desired initial adhesion and will not contaminate the adherends and which have excellent pellet handling properties. Pellets of the invention contain the propylene-based polymers (A). Pressure-sensitive adhesives of the invention contain the propylene-based polymers (A). The propylene-based polymer (A) includes 65 to 80 mol % of a structural unit derived from propylene, 5 to 10 mol % of a structural unit derived from ethylene and 15 to 25 mol % of a structural unit derived from a C4-20 α-olefin (wherein these percentages are calculated based on 100 mol % of the total of the structural unit derived from propylene, the structural unit derived from ethylene and the structural unit derived from a C4-20 α-olefin) and has a heat of crystal fusion of 5 to 45 (J/g) as measured by DSC. Compositions of the invention contain the propylene-based polymers (A).