Polyester Dispersants for Paper Recycling Stickies
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Solution Overview
Problem
In paper recycling processes, adhesives and resin components cause hydrophobic deposits leading to 'stickies' and 'white pitch', which adhere to machine parts and reduce paper quality, and existing solutions like terpolymers with antimony trioxide are unsatisfactory due to environmental concerns.
Innovation Solution
Polyesters obtained by polymerizing dimethyl terephthalate, ethylene glycol, 1,2-propylene glycol, and polyalkylene glycols with specific molecular weights, optionally with crosslinking compounds, are used to increase surface tension and make hydrophobic surfaces more hydrophilic, reducing adhesive deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanical cleaning efforts are increased to remove adhesives, then cleaning effectiveness is improved, but energy consumption and process complexity increase
Solution Approach 1:
The patent introduces polymeric dispersants as intermediary substances that chemically interact with adhesive contaminants, converting them into hydrophilic forms that can be easily removed by water. These dispersants act as mediators between the hydrophobic adhesives and the aqueous environment, enabling effective removal without complex mechanical cleaning systems.
Solution Approach 2:
The invention changes the chemical parameters of adhesive contaminants by adding polymeric dispersants that modify the surface properties of stickies, transforming them from hydrophobic to hydrophilic. This parameter change allows the adhesives to be removed through simple washing processes rather than requiring intensive mechanical cleaning.
2Object-affected harmful factors
If polyethylene glycol with low molecular weight is used, then wettability improvement is enhanced, but water solubility increases leading to premature dissolution
Solution Approach 1:
The patent optimizes the molecular weight parameter of polyethylene glycol to fall within the specific range of 1,000-2,000 g/mol. This parameter optimization achieves a balance where the polymer is large enough to maintain stability and resist premature dissolution, yet small enough to effectively adsorb at interfaces and improve wettability of hydrophobic surfaces.
Solution Approach 2:
The invention creates a composite polymer system by combining polyethylene glycol with other polymer components to form copolymers and blends. This composite approach allows the material to exhibit both good wettability properties and enhanced stability in aqueous environments, compensating for the limitations of individual polymer components.
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 polyesters significantly reduce adhesive deposition on hydrophobic surfaces, improving wettability and dispersing properties, and are environmentally friendly without using potentially carcinogenic substances.
Implementation Method 1
The polyesters described above adsorb at the water-hydrophobic surface interface and increase the surface tension of the hydrophobic surfaces, for example of polyester fabrics, felts, sieves and rollers, in such a way that the surfaces become more hydrophilic
Implementation Method 2
the polyesters described above adsorb at the water-hydrophobic surface interface and increase the surface tension of the hydrophobic surfaces
Implementation Method 3
They can also be used as dispersants for hydrophobic particles in aqueous media
Implementation Method 4
The polyesters described above are suitable for use as dispersants for hydrophobic particles in aqueous media, in particular in the form of aqueous dispersions
Data Source
AI summary
The invention relates to the use of polyesters for increasing the surface tension and for improving the hydrophilic behavior of hydrophobic surfaces. The invention is characterized in that the polyesters can be obtained by polymerizing a) one or more sulfogroups of free, aromatic dicarboxylic acids and/or the salts thereof and/or the anhydrides thereof and/or the esters thereof, b) ethylene glycol, c) 1,2 propylene glycol, d) one or more polyalkylene glycols, and e) one or more compounds of the formula (1) R1O(CHR2CHR3O)nH (1), wherein R1 represents a linear or branched, saturated or unsaturated alkyl group with 1 to 22 C atoms, preferably methyl; R2 and R3 independently of each other represent hydrogen or an alkyl group with 1 to 4 carbon atoms, preferably hydrogen and/or methyl; and n is a number from 1 to 50 , f) either in the presence or the absence of one or more crosslinking compounds with 3 to 6 functions capable of polycondensation, in particular acid, alcohol, or ester functions, with the proviso that the components d) are used in quantities by weight < 80% based on the quantity by weight of the polyesters obtained by means of the polymerization process.