Optimization of the process of calcium-carbonate dispersion stabilization for paper industry needs

Abstract

This paper presents the optimized technological process for obtaining stable calcium carbonate dispersion (CaCO3) in accordance to the standard prescribed in the paper industry. The reason for using CaCO3 in paper production is their low price when compared to the cellulose fibers and its ability to improve the properties of the final product. However, CaCO3 is alkaline filler that has relatively poor chemical stability that may affect the characteristics of the paper. For this reasons it is necessary to optimize the technology for obtaining a stable dispersion of CaCO3 with particles diameter in range 1 mm lt Dsr lt 2 mm, a pH of 9.7 and a viscosity of η lt 300 mPas. Diglycerintereftalate (DGTP) (dispersant - D1) and diethylene glycolterephthalate (DEGTP) (dispenser - D2) were synthesized from the waste poly(ethylene terephthalate) (PET) in addition to commercial - sodium tripolyphosphate (Na-TPP-D3) used in the grinding process. The pH stabilization was established with the addition of glycine/NaOH buffer, which allowed obtaining the dispersion with standard values of particle size, pH, viscosity and stability.

U radu je opisana optimizacija tehnološkog procesa dobijanja stabilne disperzije kalcijum-karbonata (CaCO3) po standardima koje propisuje papirna industrija. Razlog korišćenja CaCO3 u proizvodnji papira je njegova niska cena u odnosu na celulozna vlakna i njegova sposobnost da poboljša svojstva konačnog proizvoda. Međutim, CaCO3 je alkalni punilac koji ima relativno lošu hemijsku stabilnost i može značajno uticati na karakteristike papira. Iz tog razloga je neophodno optimizovati tehnologiju dobijanja stabilne disperzije CaCO3 sa vrednostima srednje veličine čestica u opsegu 1 mm lt Dsr lt 2 mm, pH vrednosti 9,7 i viskoziteta η lt 300 mPas. Sintetisani su dispergatori iz otpadnog poli(etilentereftalata) (PET-a): diglicerintereftalata (DGTP) (dispergator - D1) i dietilenglikoltereftalata (DEGTP) (dispegator - D2) koji su pored komercijalnog - natrijum-tripolifosfata (Na-TPP - D3) korišćeni u procesu mlevenja. Stabilizacija pH vrednosti je uspostavljena sa dodatakom glicin/NaOH - pufera što je omogućilo dobijanje disperzije standardnih vrednosti veličina čestica, pH vrednosti, viskoznosti i stabilnosti.