Weak Cationic Soft Flake ETC

On production-scale soft-flow jet machines and yarn package dyeing vessels, weak cationic soft flake ETC is introduced only after the dyeing cycle, and the bath is first buffered with acetic acid to pH 4.5–5.0. A 10–15 wt% stock dispersion is prepared with a rotor-stator mixer at 55–60 °C for 30 min, then injected into the main circulation pump at a rate equivalent to 1.0–2.5 % o.w.f. of dry fibre mass. Exhaustion proceeds at 40–45 °C for 20–30 min at a liquor ratio of 1:8 to 1:10. Mill data from multi-tube jet vessels show that exceeding 3.0 % o.w.f. does not improve panel hand feel further, but it depresses terry-towel absorbency to below 80 mm/10 min in ISO 9073-6:2003 wicking. The exhausted bath is sampled for ready biodegradability by OECD 301B; cationic softener structures of this class typically mineralise between 60 % and 80 % within 28 d, and undispersed flake solids in the drain stream are a separate operational control point if the stock dispersion is not screened through a 200 µm basket filter before dosing. Combination with strong anionic fixatives or high-affinity direct dye residues should be avoided; precipitation in the bath is evidenced by filter pressure rise across the same 200 µm basket.

Stenter padding is a separate operation with lower add-on. A circulating dosing skid delivers a 5–10 g/L working solution to a horizontal foulard set to 70–80 % pickup on woven cotton. Drying on a multi-zone stenter is controlled with the first zone at 110 °C and the final zone at 150 °C for 45–60 s; fabric surface temperature above 150 °C can yellow the softener film. Tensile strength of the finished fabric is checked with ISO 13934-1:2013, and finish uniformity is inferred from fabric surface pH, which should remain within 4.0–7.5 for OEKO-TEX Standard 100 certified articles. Objective hand data is collected with the Kawabata KES-FB2 bending module; bending stiffness reduction relative to untreated fabric is recorded as the main mechanical output. Relative humidity above 60 % in warehouse storage requires pre-drying of the flake at 45 °C before dispersion; otherwise, moisture pickup creates lumps that blind the 200 µm dosing filters and produce visible spots on dark shades.

What limits dispersion stability in concentrated rinse-cycle softener at 15–20 wt% active?

Concentrated fabric softeners using weak cationic soft flake ETC are manufactured by melting the flake with selected fatty alcohol ethoxylates at 60–70 °C and injecting the melt into a warm acidified water phase. The water phase is adjusted with lactic or formic acid to pH 2.8–3.5 before emulsification; this window is critical because higher pH accelerates ester hydrolysis and lower pH can etch unprotected dosing lines. High-shear rotor-stator mixing at tip speeds of 15–20 m/s produces a vesicular dispersion with median particle size between 80 nm and 200 nm measured by laser diffraction. Viscosity is trimmed with calcium chloride or sodium chloride at 0.05–0.30 % and measured on a Brookfield viscometer at 25 °C with spindle 3 at 20 rpm. Two recurring failure modes appear on filling lines: phase separation at storage temperatures above 35 °C and nozzle plugging when the median particle size exceeds 5 µm; both are controlled by maintaining pH below 3.5 and fully shearing the hot premix before cooling.

Deposition in a front-loading washing machine at 20–30 mL per 6 kg load gives an active rinse concentration of approximately 0.1–0.3 g/L. Under these conditions the softener forms lamellar deposits on cotton and polyester; panel softness is evaluated against a benchmark formula using a 10-point paired-comparison protocol. Because the weak cationic charge is lower than that of conventional dialkyl dimethyl ammonium chloride, detergent carryover precipitation is reduced but not eliminated; residual anionic surfactant above 0.5 g/L in the rinse bath lowers deposition efficiency and increases turbidity. Freeze-thaw cycling from −5 °C to 40 °C is part of the qualification protocol; phase separation is more likely in formulas with nonionic co-surfactant loading above 5 %. The finished product is preserved and tested according to the matrix below.

Hair conditioner lamellar gel network and wet-combing friction

In rinse-off hair conditioners, weak cationic soft flake ETC functions as a weakly cationic conditioning agent that is co-emulsified with cetyl alcohol and stearyl alcohol to form a lamellar gel network. A representative pilot batch combines the flake with fatty alcohols at a quaternary-to-fatty-alcohol ratio of 1:3, heats the oil phase to 75–80 °C, and adds it to an aqueous phase adjusted with citric acid to pH 4.0–4.5. Homogenisation under vacuum at 6000–8000 rpm is maintained for 15–20 min, after which the batch is cooled through the gel-network transition temperature near 45–50 °C. Wet-combing force is measured on a Diastron MTT175 tensile combing rig at 100 mm/min; reduction of the integrated combing force relative to untreated hair is the primary performance endpoint, and the batch is tested for microbial stability under ISO 11930:2019.

The weak cationic charge provides a balance between wet slip and long-term build-up. Repeated wash cycles using a conditioner with 0.5–1.5 % active deposit approximately 200–500 ppm of quaternary on hair fibre surfaces as measured by combustion ion chromatography; overconditioning is observed when surface deposition exceeds 1000 ppm, leading to limpness and reduced dry volume. Incompatibility with anionic rheology modifiers is operationally significant: carbomer-based formulations require separate phase addition and a final pH below 5.0 to avoid destabilising the gel network. Preservation of the finished conditioner is challenging because ester-containing quats can be metabolised by Pseudomonas species isolated from storage tanks; validated preservation per ISO 11930:2019 is therefore mandatory before release. Published data for this specific flake in ethanol-based pump spray leave-on formulations is limited; the material is rarely used at ethanol contents above 30 % because flake re-precipitation may block actuator orifices.

Dry-end tissue softening with weak cationic soft flake ETC is typically performed with a spray boom located between the Yankee dryer and the reel. The flake is predispersed at 1–3 wt% solids in water at 50–55 °C, filtered through a 100 µm in-line strainer, and sprayed onto the moving sheet at a dosage of 0.5–1.5 kg/t conditioned at 23 °C and 50 % RH according to ISO 187:1990. Softness improvement is characterised by bending stiffness reduction using ISO 2493-1:2010 and by panel hand-feel ranking; tensile index is monitored by ISO 1924-2:2008 to ensure that softening chemical application does not weaken the sheet beyond the target specification. Mill records show that softener use above 1.5 kg/t can reduce wet strength by interfering with polyamide-epichlorohydrin wet-strength resins, and the interaction is particularly visible as chalky release on the Yankee surface.

Water hardness above 200 ppm calcium carbonate destabilises the dispersion and leads to nozzle plugging within 4–6 h of continuous running. The feed tank therefore uses softened or deionised water, and the dispersion is continuously circulated from the day tank to the spray bar to prevent sedimentation. Spray application at the dry end avoids interference with wet-end retention aids; trials on Yankee adhesion show no measurable effect at dosages below 1.0 kg/t. Because published mill data for through-air-dried tissue with high crepe ratios is limited, dose-response trials on the specific tissue machine are required before qualifying the flake in a new furnish.

When weak cationic soft flake is applied after anionic fatliquors in leather drumming

In chrome-tanned leather processing, an anionic fatliquor mixture at 8–12 % of wet-blue weight is first applied to the drum at 40 °C. After a 30–40 min penetration phase, weak cationic soft flake ETC is added as a top-fix at 1–2 % of wet-blue weight. The flake dispersion is prepared separately at 40 °C and added slowly through the drum axle to avoid local overcharge. Drum speed is held at 12–16 rpm, and bath pH is maintained at 4.0–4.5 with formic acid. The cationic top-fix collapses the anionic emulsion droplets near the leather surface, causing selective deposition in the grain layer and reducing oil migration that would otherwise produce loose fatliquor and waxy bloom after drying. Softness of crust leather is evaluated by ISO 17235:2015, tear load by ISO 3377-1:2011, and tensile strength by ISO 3376:2020.

Overdosing above 2 % of wet-blue weight flips the surface charge cationic and harms subsequent finishing. Base coat adhesion is measured as dry and wet rub fastness according to ISO 11640:2012; wet rub fastness is the more sensitive indicator and may fall below customer specification when surface charge is not controlled. The top-fix effect can be monitored indirectly as a reduction in Soxhlet-extractable oil; values below 2.0 wt% on dry leather are commonly targeted. The flake should not be premixed with anionic fatliquor in the same stock tank because immediate precipitation produces grain-side spots that are difficult to correct after drying.

Spin finish emulsion stability is governed by specific conductivity

Operators on polypropylene and polyester staple fibre lines dilute weak cationic soft flake ETC with nonionic ethoxylates and phosphate ester antistats into a spin finish concentrate. The diluted emulsion is prepared with deionised water to 0.2–0.5 wt% active solids and applied through a ceramic kiss roll or metered slot at a line speed that delivers 0.3–0.5 mL/min per 100 kg/h fibre throughput. Specific conductivity of the emulsion is controlled between 50 µS/cm and 100 µS/cm at 25 °C; lower conductivity correlates with static accumulation on crimper rolls, while higher conductivity increases the risk of stray-current corrosion on stainless steel guide bars. Fibre surface resistance after finish application is checked by ASTM D257-14 and should fall within the range specified by the downstream nonwoven converter.

If dilution water hardness exceeds 150 ppm, the resulting calcium salt of the phosphate ester co-emulsifier precipitates and produces roll deposits within a single shift. The failure signature is a white deposit on the draw rolls and uneven fibre-to-fibre cohesion in carding. Line trials with a 3 m single-box draw stand indicate that conductivity drift of more than 20 µS/cm over 8 h correlates with finish pump cavitation and uneven crimp. No additional process optimisation is required beyond maintaining water quality and emulsion pH at 4.5–6.0.