Propylene Copolymer Composition for Low-Temperature Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polypropylene materials face challenges in achieving high hot tack strength, low heat sealing initiation temperature, broad processing window, and low stickiness, which are essential for applications like food packaging, where temperature control and economic efficiency are critical.
Innovation Solution
A propylene copolymer composition with a high comonomer content, specifically 1-hexene, is developed, comprising two fractions with different comonomer contents, where the comonomer-rich fraction is dominant, to achieve improved hot tack strength, low heat sealing initiation temperature, and a broad processing window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the comonomer content is increased to improve hot tack strength and lower heat sealing initiation temperature, then the sealing window broadens, but the melting temperature decreases causing stickiness and blocking during film manufacture
Solution Approach 1:
The propylene copolymer is segmented into two distinct fractions with different comonomer contents: Fraction A (1.0-2.0 wt.-% comonomer) providing high melting temperature and structural stability, and Fraction B (4.0-10.0 wt.-% comonomer) providing low heat sealing initiation temperature and high hot tack strength. This segmentation allows each fraction to fulfill specific functional requirements without compromising the other.
Solution Approach 2:
Different regions of the polymer composition have different comonomer concentrations tailored to specific functions: the comonomer-poor Fraction A provides thermal stability and high melting point properties, while the comonomer-rich Fraction B provides low-temperature sealing capability. This local quality differentiation resolves the contradiction between low sealing temperature and high melting temperature.
2Use of energy by stationary object
If the heat sealing initiation temperature is lowered to reduce energy consumption and protect the article, then the sealing window broadens, but the hot tack strength may be compromised
Solution Approach 1:
The composition utilizes parameter changes in comonomer content to achieve both low heat sealing initiation temperature and high hot tack strength. Fraction B with 4.0-10.0 wt.-% comonomer provides the low-temperature sealing capability (reducing energy consumption), while the presence of Fraction A with higher crystallinity and melting point ensures adequate hot tack strength during the sealing process.
3Productivity
If a single propylene copolymer composition is used to simplify the material system, then the processing parameters become difficult to control, but multiple fractions increase manufacturing complexity
Solution Approach 1:
The polymer is segmented into two fractions that can be produced in sequence using the same catalyst system and reactor configuration. This segmentation provides a broad sealing window (improving productivity) while maintaining a relatively simple manufacturing process (avoiding excessive complexity). The sequential production in the same reactor system minimizes the need for additional equipment.
4Ease of operation
If the comonomer content is increased to broaden the sealing window and reduce temperature control requirements, then the processing becomes easier, but the melting temperature decreases causing stickiness
Solution Approach 1:
Different portions of the polymer composition have different comonomer concentrations optimized for different temperature ranges: Fraction A (low comonomer) maintains high melting temperature for structural integrity, while Fraction B (high comonomer) provides low-temperature sealing capability. This local quality approach broadens the sealing window while preventing stickiness.
Data Source
AI summary
Propylene copolymer composition comprising a propylene copolymer (A) having a comonomer content in the range of equal or more than 0.5 to equal or below 2.0 wt.-%, the comonomers are C5 to C12 α-olefins, and a propylene copolymer (B) having a comonomer content in the range of equal or more than 4.0 to equal or below 10.0 wt.-%, the comonomers are C5 to C12 α-olefins, wherein further the propylene copolymer composition has a comonomer content in the range of equal or more than 3.5 to equal or below 7.0 wt.-%, the comonomers are C5 to C12 α-olefins, and the weight ratio of the propylene copolymer (A) to the propylene copolymer (B) is in the range of 20/80 to below 55/45.