Thermoplastic Film Web Production via Differential Polymer Heating
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Solution Overview
Problem
Conventional processes for producing hygiene films struggle to meet mechanical and haptic requirements at film thicknesses below 25 μm, limiting the trend towards thinner films due to puncture resistance and processing constraints on high-speed machines.
Innovation Solution
A process involving a starting film web of thermoplastic polymer material with a polyethylene matrix and polypropylene, where the polyethylene is warmed to a molten state but not the polypropylene, allowing for film thickness reduction to below 20 μm while maintaining desired properties through controlled temperature and processing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If film thickness is reduced to below 25 μm, then material usage and weight are improved, but puncture resistance and mechanical strength deteriorate
Solution Approach 1:
The patent uses a composite material system consisting of a polyethylene matrix (5-50 parts by weight) combined with polypropylene (50-95 parts by weight). This composite structure enables the film to achieve below 25 μm thickness while maintaining adequate puncture resistance and mechanical strength through the synergistic properties of the two polymers.
Solution Approach 2:
The patent applies controlled thermal parameter changes by warming the polyethylene matrix to its melting point to achieve a molten state for improved processability and film formation, while carefully controlling the temperature to remain below the melting point of polypropylene. This differential heating approach enables precise control over film thickness and mechanical properties.
2Quantity of substance
If film thickness is reduced to below 25 μm, then material usage is improved, but processing on high-speed machines becomes difficult
Solution Approach 1:
The patent utilizes temperature parameter changes to transform the polyethylene matrix into a molten state during processing. This phase change improves the material's flow and processing characteristics, enabling successful manufacturing on high-speed machines even at reduced film thicknesses below 25 μm.
3Shape
If polypropylene content is increased to improve stiffness, then rigidity is improved, but impact and tear strength deteriorate
Solution Approach 1:
The patent controls the thermal processing parameters by warming the polyethylene matrix to its melting point while keeping the temperature below the polypropylene melting point. This differential heating approach allows the polypropylene to maintain its crystalline structure and provide stiffness, while the molten polyethylene matrix improves processability and maintains impact and tear strength.
Solution Approach 2:
The patent employs a composite material system where polypropylene (50-95 parts by weight) provides stiffness and structural integrity, while polyethylene matrix (5-50 parts by weight) contributes to impact and tear strength. The synergistic combination balances rigidity with toughness.
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
Enables the production of commercially viable film webs with improved thermostability and mechanical properties, ensuring softness, low noise, and puncture resistance, even at reduced thicknesses, facilitating effective processing and user acceptance.
Implementation Method 1
the starting film web is warmed until the molten state of the polyethylene matrix material, but not until the molten state of the polypropylene
Implementation Method 2
passed through a cooled roll nip
Data Source
AI summary
The invention relates to a method for producing a film web during which an initial film web made of thermoplastic polymer material with a polyethylene matrix, in which 1 to 70 parts by weight of polypropylene, with regard to 100 parts by weight of polyethylene matrix, are contained, is, after being heated, guided through a cooled roll gap (7, 8), whereby the initial film web is heated only until the polymer matrix material melts but not to a temperature at which the polypropylene melts.