Polypropylene Blend for Low Heat Sealing Initiation Temperature
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polypropylene-based polymer composites face challenges in achieving high hot tack strength, low heat sealing initiation temperature, high melting point, and good optical properties, which are often conflicting requirements in packaging applications.
Innovation Solution
A polymer composite comprising a polypropylene with low comonomer content, a propylene copolymer with higher comonomer content, and a low-crystalline polymer, specifically formulated to have a comonomer content range of 2.5-10 wt.%, a melting temperature above 140°C, and a heat sealing initiation temperature below 110°C, achieved through a combination of these polymers in specific weight ratios and processing methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polypropylene composition is designed to achieve high hot tack strength, then the seal strength at elevated temperature improves, but the heat sealing initiation temperature increases
Solution Approach 1:
The invention changes the compositional parameters by incorporating a low-crystalline polymer component with specific properties (crystallinity below 30%, melting temperature below 120°C) into the propylene copolymer system. This parameter modification enables the composite to achieve both high hot tack strength (through the amorphous low-crystalline phase) and low heat sealing initiation temperature (through the low melting point component), resolving the contradiction between these two thermal properties.
Solution Approach 2:
The invention creates a composite material system combining propylene copolymer with low-crystalline polymer in specific ratios (30-70 wt% low-crystalline polymer). This composite approach allows the synergistic combination of the propylene copolymer's structural integrity with the low-crystalline polymer's low-temperature sealing capability, achieving both high hot tack strength and low heat sealing initiation temperature simultaneously.
2Use of energy by stationary object
If the heat sealing initiation temperature is reduced for lower processing temperature, then energy consumption decreases, but the melting point may be compromised
Solution Approach 1:
The invention modifies the thermal parameters of the polymer system by introducing a low-crystalline polymer with melting temperature below 120°C, which enables heat sealing at lower temperatures (reducing energy consumption) while the overall composite maintains an adequate melting point through the propylene copolymer matrix.
Solution Approach 2:
The invention applies local quality differentiation where the low-crystalline polymer phase provides low-temperature sealing capability in specific regions, while the propylene copolymer matrix maintains the overall structural integrity and higher melting point, allowing different parts of the material to fulfill different thermal functions.
3Temperature
If a low-crystalline polymer is added to reduce heat sealing initiation temperature, then the SIT improves, but the optical properties may deteriorate
Solution Approach 1:
The invention carefully controls the parameters of the low-crystalline polymer component, selecting materials with crystallinity below 30% and melting temperature below 120°C, and optimizes the composition ratio (30-70 wt%) to achieve low heat sealing initiation temperature while maintaining acceptable optical properties through controlled crystallinity levels.
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 composite exhibits enhanced hot tack force, low heat sealing initiation temperature, and improved optical properties, balancing the conflicting requirements of processing and end-use properties.
Implementation Method 1
a low-crystalline polymer (C) having a melting temperature of below 120°C
Implementation Method 2
The inventive composite is preferably obtained by mixing, preferably melt mixing, a mixture (M) comprising the polypropylene (A) and the propylene copolymer (B) with the low-crystalline polymer (C)
Implementation Method 3
the polymer composite has (i) a melting temperature of at least 140°C
Data Source
AI summary
Polymer composite comprising propylene copolymer composition having a comonomer content in the range of 2.5 to 10 wt.-%, the comonomers are C5 to C12 a-olefins, and a low-crystalline polymer having a melting temperature of below 120 °C, wherein further said polymer composite has (i) a melting temperature of at least 140 °C, and (ii) a heat sealing initiation temperature (SIT) of not more than 110 °C.