Avicor 384

Avicor 384, a styrenated unsaturated polyester resin, is introduced as the continuous binder phase in high-filler solid surface casting where aluminum trihydrate (ATH) constitutes between 55 wt% and 70 wt% of the compounded mass. The resin is pre-promoted for room-temperature cure with methyl ethyl ketone peroxide; production-scale additions fall between 1.0 phr and 1.5 phr, with gel time at 25 °C typically maintained between 8 min and 16 min after pigment and ATH have been dispersed. The pre-promotion system, normally cobalt octoate, requires the organic peroxide to be added as a separate component; direct mixing of methyl ethyl ketone peroxide with the concentrated cobalt promoter before resin dilution is prohibited because the decomposition reaction is immediate and highly exothermic. ATH moisture content is held below 0.3 wt%; when the filler exceeds this limit, it is pre-dried at 120 °C for 12 h because surface hydroxyl groups compete with the cobalt promoter and extend gel time unpredictably. Mixing is carried out in vacuum-equipped high-shear planetary dispersers at residual pressures below 80 mbar to remove entrained air from the highly viscous mineral dispersion; the same vacuum phase is held for 5 min to 10 min under agitation. The filled compound is transferred into polished glass or acrylic molds, vibrated at 50 Hz for 10 min to 20 min, and left to exotherm until the core temperature reaches 45 °C to 55 °C before demolding. Post-cure is performed in forced-air ovens at 60 °C to 80 °C for 3 h to 5 h to minimize residual styrene and complete the second-stage network formation. Cured sheets are conditioned at 23 °C and 50 % relative humidity for 24 h and then evaluated for Barcol hardness and water absorption; slabs cast with this resin are normally referenced against ASTM D2583 and ASTM D570, with acceptance thresholds set at Barcol 45 and water absorption below 0.5 % for solid surface material classified under ISO 19712-1. End products include vanity tops, laboratory work surfaces, and integrally cast washbasins.

What Restricts Resin Dosage in Vacuum Vibrocompacted Quartz Slab Production?

In Breton-type vacuum vibrocompaction lines, engineered stone slab production with Avicor 384 operates at resin binder fractions between 8 wt% and 12 wt% relative to total batch mass. The lower boundary is limited by the need for continuous matrix coverage around angular quartz particles with a median diameter from 0.1 mm to 7 mm, while the upper boundary is controlled by exotherm accumulation during 90 °C to 110 °C accelerated curing; resin-rich regions above 12 wt% generate local exotherms that cause differential cure shrinkage and surface waviness. The dispersion sequence is performed in high-speed forcing mixers with two counter-rotating paddles; silane-treated quartz, mirror glass, and pigment are dry-blended for 60 s to 120 s before the resin is introduced. Under vacuum of 40 mbar to 60 mbar, the loose mix is compacted at 0.3 MPa to 0.5 MPa and vibrated at 45 Hz to 55 Hz for 90 s to 150 s to achieve the consolidated density required by ISO 19712-1 for engineered stone slabs. Vibration frequency outside this ±5 Hz band reduces compaction efficiency: lower frequencies leave large air pockets near the slab core, while higher frequencies create particle segregation at the top face. Cured slabs are gauged, calibrated, and polished with diamond abrasives; edge profiles and sink cutouts must be sealed with siloxane penetrants because the machined surfaces expose quartz-resin interfaces that can retain water under intermittent wet service. Compliance testing for stain resistance and thermal shock follows ISO 19712-1 procedures, with slab format dimensions typically 3050 mm × 1650 mm and thicknesses from 12 mm to 30 mm.

Precision machine tool foundation blocks are cast with Avicor 384 filled with graded quartz and granite aggregates in a resin-to-aggregate ratio of 9:100 to 11:100 by mass. The aggregate blend is dried to a moisture content below 0.1 wt% before the resin is added, because residual surface water inhibits wetting and leaves microvoids at the aggregate-matrix interface. Vibrating table compaction at 30 Hz to 50 Hz is applied for 20 min to 40 min, followed by ambient gelation and a controlled ramp to 70 °C over 2 h to avoid thermal runaway in sections thicker than 100 mm. In pours exceeding 100 mm, embedded thermocouples are placed at the geometric core and near the mold face; if the measured temperature gradient exceeds 15 °C between core and mold face, the ramp rate must be reduced or the section re-designed to avoid cure-induced microcracking. The resulting polymer concrete provides high damping capacity and is used for machine bases, coordinate measuring machine foundations, and pump plinths where dimensional stability is specified according to DIN 51290-1 or equivalent internal OEM standards. The principal production risk in thick sections is exothermic temperature rise exceeding 120 °C, which can cause internal cracking; batch size and mold configuration are therefore matched to heat transfer models before serial casting.

When Open-Mold Cultured Marble is Pigmented with High-Dose Inorganic Oxides

In cultured marble open-mold operations, Avicor 384 is sprayed or poured as a gel coat and backup matrix onto glass-fiber chopped strand mat or continuous veil with ATH loadings between 50 wt% and 65 wt%. Pigment pastes based on iron oxide, titanium dioxide, or chromium oxide are added at 0.5 wt% to 5.0 wt% of the resin mass; higher loadings of carbon black or fine iron oxide retard the MEKP decomposition path through radical scavenging and shift gel time by 30 % to 60 %. Cure initiation with methyl ethyl ketone peroxide is therefore adjusted in the catalyst range 1.2 phr to 2.0 phr, and exotherm is moderated by limiting pour thickness to 12 mm to 25 mm per layer. Pigment pastes must be styrene-based rather than acrylic-carrier systems, because acrylic carriers reduce intercoat adhesion and create visible haze at the gel coat-backup interface in translucent veils. The open-mold process requires local exhaust ventilation and styrene monitoring because styrene emission from the exposed casting surface can exceed workplace action limits if the pour area is not ventilated at a minimum face velocity of 0.5 m/s. Post-cure at 60 °C for 4 h reduces residual styrene below the odor threshold required for bathroom fixture acceptance. Finished vanities, shower wall panels, and molded basins are tested under ANSI Z124.3 and ISO 19712-1 for cleanability and resistance to hot-cold cycles.

Sanitary Ware Backup Resin and Glass-Reinforced Laminate Chemistry

Spray-up of Avicor 384 as a rigid backing layer for acrylic and gel-coated bathtub shells uses fiberglass roving at a fiber fraction of 25 wt% to 35 wt%. The resin is formulated with paraffin wax at 0.1 wt% to 0.3 wt% or with surface film-forming additives to eliminate air inhibition on the exposed laminate face. Laminating rollers are used after each gun pass to consolidate the sprayed laminate and remove entrapped air before the peroxide-initiated gel front reaches the interface. Spray equipment is set at a resin output of 3.5 kg/min to 5.0 kg/min with catalyst injection at 1.5 % to 2.0 %, yielding a wet lamina thickness of 0.8 mm to 1.2 mm per pass. When ambient temperature falls below 18 °C or rises above 28 °C, the catalyst injection line must be recalibrated because the MEKP decomposition rate changes and the gel front can outrun the roll-out sequence. The backed shell is cured for 2 h at ambient temperature, then post-cured at 60 °C for 3 h to stabilize the laminate behind acrylic sheets that can reach 60 °C during hot-water filling. Shower trays and bathtubs produced in this procedure are evaluated for impact resistance and load-bearing capacity under EN 14527 or equivalent regional standards.

Cast polymer concrete drainage channels and trench drains are produced from Avicor 384 filled with silica sand at resin contents of 10 wt% to 13 wt%, demolded after 24 h and checked for aggregate exposure according to EN 1433.