Polyurethane Nonwoven Press Felt for Reduced Rewetting
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Solution Overview
Problem
The production of press felts with polyurethane fibers has been hindered by processing difficulties and availability issues, making it challenging to reliably produce coverings that utilize the positive properties of polyurethane fibers, especially in existing systems designed for polyamide fibers, and resulting in delayed operational readiness and increased rewetting of fibrous webs.
Innovation Solution
A covering with a non-woven fleece layer comprising a functional zone that combines polyurethane fibers with other polymer fibers, where the polyurethane fibers make up between 10% to 60% by weight, improving processability and enabling faster startup and reduced rewetting, while being compatible with existing machinery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyurethane fibers are used in the nonwoven layer to improve press felt properties, then the operational performance is improved, but the processing difficulty increases and reliable production becomes impossible
Solution Approach 1:
The patent applies composite materials by combining polyurethane fibers with polyamide fibers in a nonwoven layer. The polyurethane content is controlled at 10-60% by weight, creating a composite structure that leverages the advantages of both materials while mitigating their individual drawbacks. This composite approach enables reliable production on existing machinery while maintaining the performance benefits of polyurethane fibers.
2Reliability
If polyurethane fibers are used to achieve positive properties, then the operational properties are improved, but the production time increases due to break-in period
Solution Approach 1:
The patent applies parameter changes by controlling the polyurethane fiber content within a specific range (10-60% by weight) and optimizing the fiber arrangement in the nonwoven layer. This parameter optimization enables the press felt to achieve its operational properties quickly without requiring an extended break-in period, while still maintaining the performance advantages of polyurethane fibers.
3Object-affected harmful factors
If polyurethane fibers are used in the nonwoven layer, then the re-moistening of fiber web is reduced, but the compatibility with existing machinery decreases
Solution Approach 1:
The patent applies local quality by creating a nonwoven layer with specific local characteristics - the polyurethane fibers are distributed at controlled concentrations (10-60% by weight) in specific zones of the press felt. This localized optimization reduces re-moistening of the fiber web in critical areas while maintaining overall compatibility with existing machinery through the balanced composite structure.
Data Source
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AI summary
The invention relates to a paper machine clothing for a machine for producing a fibrous web, in particular a paper, cardboard, tissue or cellulose pulp web, comprising a basic structure having an upper side, a running side and, at least on one side, a nonwoven support, wherein this nonwoven support has a functional zone, which extends over more than 50 µm in the thickness direction of the paper machine clothing and which comprises a first proportion and a second proportion of nonwoven fibres, the nonwoven fibres of the first proportion consisting of or comprising a polyurethane, in particular a thermoplastic polyurethane, whereas the nonwoven fibres of the second proportion consist of a polymer material that does not contain any polyurethane. According to the invention, the first proportion accounts for between 10% by weight and 60% by weight of the functional zone. The invention additionally relates to a production method and a suitable nonwoven fabric.