Propylene Polymer Composition for Low-Temperature Heat Sealing
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Solution Overview
Problem
The challenge is to develop a propylene polymer composition that can form a heat seal layer capable of being heat-sealed at a relatively low temperature while preventing blocking issues in films, which occurs when films with such layers are wound or overlapped, hindering subsequent processing.
Innovation Solution
A propylene polymer composition comprising a propylene polymer (1) with 94% or more of its monomer unit derived from propylene and a propylene-α-olefin copolymer (2) with 60% to 94% of its monomer unit derived from propylene and 6% to 40% from α-olefins, specifically designed to satisfy the condition Wb ≤ -1.7 × Th + 150 in a temperature rising elution fractionation method, ensuring improved heat sealability and blocking resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat seal layer is designed to be heat-sealed at a relatively low temperature, then heat sealability is improved, but blocking occurs between films making subsequent processing difficult
Solution Approach 1:
The invention changes the compositional parameters of the heat seal layer by specifying precise proportions of propylene polymer (1) and propylene-α-olefin copolymer (2), along with controlling the TREF fractionation parameters (Wb ≤ -1.79×Th + 150). This compositional parameter optimization enables the material to achieve both low-temperature heat sealability and blocking resistance simultaneously
Solution Approach 2:
The invention creates a composite material system by combining propylene polymer (1) with specific properties (94% or more propylene content) and propylene-α-olefin copolymer (2) with controlled composition (60-94% propylene, 6-40% α-olefin). This composite structure integrates the advantages of both polymer types to resolve the contradiction between heat sealability and blocking resistance
2Productivity
If the heating time is shortened to accelerate bag forming speed, then productivity is improved, but heat sealing becomes insufficient
Solution Approach 1:
The invention optimizes the thermal parameters of the heat seal layer through controlled composition and TREF fractionation, enabling effective heat sealing at lower temperatures. This parameter optimization allows sufficient heat penetration and bonding within shorter heating times, thus improving productivity without sacrificing heat sealing quality
Data Source
AI summary
An object of the present invention is to provide a propylene polymer composition capable of forming a heat seal layer that can be heat-sealed at a relatively low temperature and suppressing blocking in a film including the heat seal layer. A propylene polymer composition contains the following propylene polymer (1) and the following propylene-α-olefin copolymer (2), in which a content of the propylene polymer (1) is 2% by mass to 25% by mass with respect to 100% by mass of a total content of the propylene polymer (1) and the propylene-α-olefin copolymer (2), and the propylene polymer composition satisfies the following requirement (3):Propylene polymer (1):a polymer containing 94% by mass or more of a monomer unit derived from propylene.Propylene-α-olefin copolymer (2):a copolymer containing 60% by mass or more and less than 94% by mass of a monomer unit derived from propylene and more than 6% by mass and 40% by mass or less of a monomer unit derived from an α-olefin having 4 to 12 carbon atoms.Requirement (3):the following Expression (3-1) is satisfied in a temperature rising elution fractionation method in which ortho-dichlorobenzene is used as a solvent and a temperature range is set to 0° C. to 140° C.Wb≤-1.79×Th+150(3-1)