Yingkou Tianyuan TB-05TS

Yingkou Tianyuan TB-05TS is compounded into EVA/LDPE-based low-smoke zero-halogen cable insulation and sheathing at filler loadings between 50 wt% and 65 wt%. The product is supplied as a surface-treated magnesium hydroxide with a median particle size near 5 μm; the organic coating reduces equilibrium torque during co-rotating twin-screw compounding compared with unmodified magnesium hydroxide of equivalent particle size, but the exact coating chemistry should be confirmed against the manufacturer’s technical datasheet. On production-scale cable lines, the extruder typically uses a two-stage feeding arrangement: polymer, antioxidant masterbatch, and processing aid enter the main feed throat, while TB-05TS is introduced through a side feeder after the first kneading zone. Screw configurations with L/D ratios of 36–44 are common. Barrel temperature profiles are normally set between 140 °C and 180 °C, with the melt temperature held below 190 °C for EVA grades containing 19–28% vinyl acetate. The upper temperature limit is not governed by the filler—dehydration onset is above 330 °C—but by acetic acid elimination from the EVA matrix and possible degradation of the surface treatment. When melt temperature consistently reaches 190 °C or higher, surface pitting and strand foaming are observed, particularly at vacuum levels below -0.06 MPa. In cable jacket extrusion, filler loadings above 63–65 wt% produce low melt elongation, die lip build-up, and unstable strand pelletizing unless a low-molecular-weight processing aid is present. A representative compound containing 100 phr EVA/EVA-g-MAH blend, 120–150 phr TB-05TS, 5–10 phr zinc borate, and 2–4 phr silicone masterbatch can reach a limiting oxygen index above 35% under ISO 4589-2. Halogen acid gas emission is limited, with pH ≥ 4.3 and conductivity ≤ 10 μS/mm measured according to IEC 60754-2. Smoke transmittance is commonly above 60% under IEC 61034-2, while single-wire flame propagation per IEC 60332-1-2 remains within the char-height threshold of 425 mm when the cable construction includes a ceramic-forming separator tape.

How Does TB-05TS Change Melt Rheology and Impact Behaviour in Polypropylene Copolymer at 50 wt% Loading?

In polypropylene copolymer compounds for extruded conduit, profile, sheet, and injection-molded electrical enclosures, TB-05TS is added at 40–60 wt% to achieve UL 94 V-0 at 3.0 mm thickness without halogenated synergists. The melt flow rate of the final compound under ISO 1133-1:2022 is usually controlled between 2 g/10 min and 10 g/10 min; filler loadings at the upper end reduce melt flow unless a maleic anhydride grafted polypropylene coupling agent is included at 2–5 wt%. Impact modification with ethylene-octene copolymer at 10–15 wt% is required because the notched Izod impact strength under ISO 180:2023 falls sharply when filler volume fraction exceeds 0.30–0.35. The critical processing risk is shear heating during compounding: high-shear kneading blocks can raise local melt temperature to 230–240 °C, where the surface coating may degrade and the polypropylene matrix begins thermo-oxidative degradation. Production-scale co-rotating twin-screw extrusion with L/D 40–48 and a temperature profile of 170/180/190/200/200/190 °C maintains stable strand pelletization when the side feeder is placed after 40–50% of barrel length. Tensile properties are measured according to ASTM D638-14; the expected effect of raising filler loading from 40 wt% to 60 wt% is a proportional reduction in elongation at break and a loss of tensile strength that is strongly matrix-dependent. Published comparative data for TB-05TS in high-melt-flow PP homopolymer is limited; therefore, production trials must verify the drop in elongation before specifying the grade for thin-wall conduit. Pre-drying at 80 °C for 2 h is necessary when the filler or compound has been stored at relative humidity above 60%, because surface moisture causes micro-voids and silver streaks in extruded profiles.

Peroxide-cured EPDM compounds containing TB-05TS are processed in internal mixers with ram pressure 0.6–0.7 MPa and dump temperature below 120 °C to avoid scorch before cure. In cable bedding and hose applications, the filler loading is typically 30–50 phr, sometimes with 5–10 phr zinc borate and 1–2 phr silane coupling agent. TB-05TS does not interfere with dicumyl peroxide cure as strongly as untreated magnesium hydroxide; the hydrophobic coating limits moisture uptake during open-mill storage and reduces the risk of porosity in thick sections. Cure kinetics on a moving die rheometer per ISO 6502:2016 show a small increase in minimum torque, with T90 at 170 °C often between 8 min and 12 min depending on peroxide half-life and coagent selection. The main production issue is not venting or porosity—water release begins above 330 °C—but severe mill sticking at low shear when filler loading exceeds 60 phr. In sulfur-donor systems, the acid-scavenging behaviour of the magnesium oxide formed during decomposition can alter vulcanization rate; therefore, sulfenamide accelerator doses are often raised by 10–20% compared with equivalent carbon black formulations.

Vapour-Phase HCl Scavenging and Smoke Suppression in Flexible PVC

Flexible PVC uses TB-05TS as a secondary flame retardant and smoke suppressant at 5–20 phr, not as the primary filler. PVC decomposes through dehydrochlorination beginning near 180 °C depending on stabilizer type; TB-05TS remains stable until above 330 °C, so it does not release water during normal two-roll milling at 160–175 °C. Its function is to provide magnesium oxide after the polymer has begun burning; the oxide reacts with hydrogen chloride vapour and reduces smoke density when combined with zinc borate or molybdenum trioxide. However, because magnesium hydroxide is basic, it can consume hydrogen chloride generated during compounding and accelerate heat stabilizer depletion. Calcium-zinc stabilizer systems at 4–6 phr are preferred over lead-based systems in European formulations due to REACH restrictions; use of TB-05TS in lead-stabilized PVC is technically possible but uncommon. The operational boundary is set by thermal dwell time: on a calendering line, stock temperatures above 180 °C for more than 5 min cause early colour shift from white to pale yellow. For this reason TB-05TS is not recommended at high loading in rigid PVC pipe extrusion, where the additional shear heating and longer residence time narrow the stabilizer margin. In flexible cable compounds, the filler also reduces the amount of antimony trioxide needed to meet oxygen index targets under ISO 4589-2; replacement ratios are resin-dependent and require pilot verification.

If ATH Is Replaced by TB-05TS in Unsaturated Polyester Molding Compounds

Sheet molding compound and bulk molding compound recipes commonly contain aluminum trihydrate at 100–150 phr as a low-cost flame retardant, but ATH decomposition begins near 190–220 °C, which restricts molding temperature. TB-05TS has a higher dehydration onset above 330 °C, which permits press molding at 170–200 °C without the water blistering associated with ATH. This temperature advantage is offset by three effects. First, the hydroxide surface interacts with carboxyl-terminated unsaturated polyester; without silane treatment, thickening with magnesium oxide paste accelerates and the compound may reach a maturation viscosity of 20–40 million cP before mold filling is complete. The manufacturer’s surface treatment reduces this acceleration, but maturation trials are still required because batch-to-batch variation in resin acid number changes thickening response. Second, the oil absorption of magnesium hydroxide is higher than ATH of comparable particle size, so resin demand increases at equal filler weight. Third, the endothermic decomposition provides a later heat sink than ATH, which can improve flame retardancy at higher heat fluxes but may delay char front formation in thin sections. Published comparative data for TB-05TS in SMC at 180 °C press molding is limited; compounders usually run pilot rheology and spiral flow trials before converting from ATH. In pultrusion, die zone temperatures of 160/180/190 °C are used for profiles containing 20–40 phr TB-05TS, and the filler remains thermally inactive during cure because the die temperature stays well below the decomposition range.

Thermoplastic elastomer compounds based on propylene-ethylene copolymers for automotive grommets, cable bushings, and appliance connectors are produced with TB-05TS at 35–45 wt% to meet flammability requirements while retaining low hardness. Injection molding uses barrel temperatures of 180–210 °C and back pressure of 0.5–1.0 MPa; excessive hold pressure or high shear in a cold runner can cause surface splay if the mineral absorbs atmospheric moisture after drying. Pre-drying at 80 °C for 2–3 h is standard when the material has been exposed to relative humidity above 60%. The performance target in appliance connectors is usually UL 94 V-0 at 1.5 mm thickness, which requires a combination of TB-05TS and a char-forming phosphorus-nitrogen synergistic package. Without the synergistic package, mineral-filled TPEs often fail the required 10 s afterflame time under vertical burn testing. Tensile elongation after oil ageing is measured according to ISO 37:2017, and adding TB-05TS above 45 wt% can reduce elongation below the 150% commonly specified for automotive grommets. The principal field failure mode is not combustion but stress whitening at sharp bends due to high filler volume fraction; this is controlled by using an impact modifier at 15–20 wt% and limiting filler loading to 35 wt% in parts with tight radii.