Polyethylene Sealant Composition for Hot Tack and Heat Sealing
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Solution Overview
Problem
Conventional polyethylene compositions for packaging applications face a tradeoff between hot tack initiation temperature, heat seal initiation temperature, and density, with lower density compositions exhibiting lower processing characteristics and higher density compositions having higher initiation temperatures, necessitating a need for improved compositions that balance these properties.
Innovation Solution
Polyethylene compositions comprising two polyethylene fractions with specific temperature ranges and percentages in the iCCD analysis, achieving a density of 0.905 g/cm3 to 0.918 g/cm3, melt index of 0.7 g/10 minutes to 3.5 g/10 minutes, and a melt index ratio of I10/I2 < 7.0−1.2 log (I2), which enhance hot tack window and heat seal initiation temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional polyethylene compositions with lower density are used, then hot tack initiation temperature and heat seal initiation temperature are reduced, but processing difficulty increases due to low melting point and tacky nature
Solution Approach 1:
The patent changes the molecular weight distribution parameters by blending polyethylene fractions with specific iCCD temperature ranges (40-75°C and 85-110°C), which modifies the melting behavior and processing characteristics while maintaining low initiation temperatures
Solution Approach 2:
The patent creates a composite polyethylene composition by combining multiple polyethylene fractions with different molecular weights and comonomer distributions, achieving a balance between low initiation temperature and improved processing characteristics
2Ease of manufacture
If conventional polyethylene compositions with higher density are used, then processing characteristics improve, but hot tack initiation temperature and heat seal initiation temperature increase
Solution Approach 1:
The patent optimizes the density parameter to a specific range (0.905-0.918 g/cm³) and combines it with controlled molecular weight distribution to achieve both good processing characteristics and acceptable initiation temperatures
3Strength
If polyethylene composition density is increased, then film strength and blocking properties improve, but hot tack window and heat seal initiation temperature worsen
Solution Approach 1:
The patent creates different regions within the polyethylene composition with different molecular weights and comonomer distributions, where lighter fractions provide low initiation temperature and hot tack window, while heavier fractions provide strength and blocking properties
Solution Approach 2:
The patent formulates a composite material with multiple polyethylene fractions that have complementary properties, combining the benefits of low-density fractions (hot tack window) with high-density fractions (strength)
Data Source
AI summary
Embodiments of a polyethylene composition are provided, which may include a first polyethylene fraction comprising at least one peak in a temperature range of from 40 C to 75 C in an elution profile via improved comonomer composition distribution (iCCD) analysis method, where a first polyethylene area fraction is an area in the elution profile from 40 C to 75 C, and where the first polyethylene fraction area comprises from 45% to 65% of the total area of the elution profile; and a second polyethylene fraction comprising at least one peak in a temperature range of from 85 C to 110 C in the elution profile, where a second polyethylene area fraction is an area in the elution profile from 85 C to 110 C, and where the second polyethylene fraction area comprises from 15% to 35% of the total area of the elution profile, wherein the polyethylene composition has a density of 0.905 g/cm3 to 0.918 g/cm3, a melt index (I2) of 0.7 g/10 minutes to 3.5 g/10 minutes, and wherein the composition has a melt index ratio (I10/I2) that meets the following equation: I10/I2<7.0-1.2 log (I2).