Thickeners — Cellulose ethers and their derivatives

Hydroxyethyl cellulose (HEC) was first produced industrially by Union Carbide in 1932, and has been in production for more than 70 years. At present, cellulose ethers and their derivatives thickeners mainly include hydroxyethyl cellulose (HEC), methyl hydroxyethyl cellulose (MHEC), ethyl hydroxyethyl cellulose (EHEC), methyl hydroxypropyl cellulose (MHPC), methyl cellulose (MC) and xanthan gum, etc. These are all non-ionic thickeners, while belonging to the non-conjugated water-phase thickeners. The most commonly used in emulsion paints are HECs, such as Natrosol 250 from Aqualon and Cellusize QP from Union Carbide.

Hydrophobically modified cellulose (HMHEC) is the introduction of a small number of long-chain hydrophobic alkyl groups on the hydrophilic backbone of cellulose, thus becoming a connective thickener, such as Natrosol Plus Grade 330, 331, Cellosize SG-100, Bermocoll EHM-100. its thickening effect can be comparable to the much larger molecular weight of cellulose ether thickener species . It improves the viscosity and leveling of ICI and reduces the surface tension, such as HEC with a surface tension of about 67 mN/m and HMHEC with a surface tension of 55-65 mN/m.

A hydroxy-based acrylic resin is combined with three polymer dispersants to disperse the red pigment HE UCO 316600 from the German HEUBACH company. As shown in Table 2-10. The compatibility of these three dispersants with acrylic resins is different. The experimental results show that if the compatibility paraffin wax with ptfe is not good, the dispersion effect is not as good as that without adding dispersant.

It can be clearly seen from the experiment that compatibility has a great influence on pigment dispersion. This conclusion was further confirmed in another set of experiments. The same use of 2* dispersant and an acrylic hydroxyl-containing resin with good compatibility resulted in completely different results from the above conclusions. At the same time, the dispersion fineness can reach 5pm. Made into two-component PU paint, Koyo reached 96.7%, finger rub color difference value 0.49, lightness value-1.15, all showing excellent condition,
Regarding the compatibility test, the most commonly used method is to mix the dispersant and the resin base at 91 and observe the compatibility of the mixture. Clear and transparent is better. In some cases, Red Devil mill can be used to disperse for 1h (addition of glass beads and the mixture 111), and observe its compatibility. This kind of experiment can pre-test the deflocculation, gloss and anti-floating condition.