Dynamic Shear Modulus Degradation Limits in High Speed Recyclable UV Resin Formulations
Dynamic shear degradation limits UV resin velocity at 280 m/min to prevent oligomer scission, balancing resin costs against full EPR fee savings.
Alkaline Hydrolysis Repulping
Chemical Dissolution
Industrial fiber separation relies on targeted chemical cleavage of wet-strength resins during paper recovery. The application of alkaline hydrolysis repulping breaks down the cured polyamide-epichlorohydrin crosslinks that hold the fibers together in water-resistant grades. High pH levels accelerate the reaction rate.
The process restores fiber swellability, allowing subsequent mechanical action to defiber the sheet.
Operating Parameter
Process control in this recycling step requires careful balancing of temperature and sodium hydroxide dosage. Raising the slurry temperature to sixty degrees Celsius reduces the time needed for complete fiber liberation. Sodium hydroxide drives the pH to eleven, which destabilizes the wet-strength polymer.
Lower temperatures or weaker alkaline conditions prolong the batch run and raise energy costs.
Substrate Limit
High yield fibers and sensitive coatings restrict the use of this strong chemical environment. Excessive alkalinity causes yellowing in groundwood and mechanical pulps due to lignin darkening. Packaging materials coated with wax or polymer barriers suffer from saponification, which leads to sticky contaminants in the papermaking system.
Operators must therefore bypass this aggressive treatment when processing mechanical or heavily coated stocks. Alkaline damage can weaken recovered fibers, which reduces the burst strength of the final recycled linerboard and limits the grade to low-strength board production.