Polymeric Additive Distribution in Paper Stock via Refining
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Solution Overview
Problem
Conventional paper and board manufacturing processes face challenges with the efficient dissolution and distribution of high molecular weight polymeric papermaking additives, leading to issues like incomplete dissolution, surface wet lumps, and reduced paper quality due to deposits and web breakages.
Innovation Solution
Adding polymeric papermaking additives, especially of high molecular weight, to the fibre stock before deflaking and/or refining, either as dry powder or as an aqueous dispersion, allows for more homogeneous distribution and improved interaction with fibre components, enhancing strength and process efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high molecular weight polymeric additives are dissolved in water before addition, then they can be evenly distributed in the paper stock, but they form surface wet lumps and fisheyes due to incomplete dissolution
Solution Approach 1:
The patent applies preliminary action by adding the polymeric additive to the fibre stock before deflaking and refining operations, rather than dissolving it separately beforehand. This allows the polymer to be incorporated into the fibre matrix during the mechanical processing stages, ensuring complete distribution without forming surface lumps or fisheyes.
Solution Approach 2:
The patent changes the physical state parameter of the polymeric additive from requiring complete dissolution in water to being added as a dispersion or slurry that integrates during mechanical processing. This parameter change eliminates the dissolution completeness issue while maintaining uniform distribution through the refining and deflaking processes.
2Reliability
If polymeric additives are added as dry powder, then dissolution issues are avoided, but homogeneous distribution in the stock is difficult to achieve
Solution Approach 1:
The patent uses preliminary action by adding the dry polymeric powder to the fibre stock before the deflaking and refining stages. The mechanical energy from these processes then distributes the powder uniformly throughout the stock, achieving both reliable defect-free processing and homogeneous distribution simultaneously.
Solution Approach 2:
The patent replaces the chemical dissolution mechanism with a mechanical distribution mechanism. Instead of relying on water dissolution to distribute the polymer, the system uses the mechanical action of deflaking and refining equipment to disperse and distribute the dry polymer uniformly throughout the fibre stock.
3Strength
If multiple polymer products are added to achieve targeted paper properties, then paper strength and process efficiency improve, but equipment complexity and operational difficulty increase
Solution Approach 1:
The patent applies universality by using a single polymeric additive that performs multiple functions simultaneously: it provides dry strength, improves wet strength, enhances retention, and aids in dewatering. This multi-functionality eliminates the need for multiple separate polymer addition systems, reducing equipment complexity while maintaining all desired paper properties.
Solution Approach 2:
The patent merges multiple polymer functions into a single polymeric additive product. Instead of adding separate polymers for strength, retention, and dewatering, the invention uses one multifunctional polymer that delivers all these benefits, thereby simplifying the addition system and operational procedures.
4Ease of manufacture
If dry polymers are used to improve transportation efficiency and shelf life, then storage and handling improve, but complete dissolution becomes more difficult and time-consuming
Solution Approach 1:
The patent applies preliminary action by adding the dry polymer to the fibre stock at the beginning of the papermaking process, before deflaking and refining. This eliminates the need for separate dissolution time, as the polymer is incorporated during the normal processing timeline, maintaining both storage efficiency and process speed.
Data Source
AI summary
The present invention provides a process for producing paper or board, comprising slushing a stock of dried fibres in a slushing system comprising a pulper, and/or feeding a stock of never-dried fibres in a fiber line of an integrated paper mill; deflaking and/or refining the stock in a deflaker and/or a refiner, optionally diluting the deflaked and/or refined stock, directing the deflaked and/or refined stock to a headbox, forming a web, and drying the web, wherein a polymeric paper making additive is added to one or more of the stocks of dried fibres and never-dried fibres before deflaking and/or refining of the stock. The present invention further provides paper and board with improved properties.