Ateva 1070 EVA resina de copolímero, 9% VA, 2,8 MI, fio e cabo grau

Ateva 1070 EVA Copolymer Resin, 9% VA, 2.8 MI, Wire & Cable Grade, is a low-vinyl-acetate ethylene-vinyl acetate copolymer resin designed for use as a compounding feedstock in thermoplastic and crosslinkable wire and cable formulations. The product is specified at 9 wt% vinyl acetate comonomer and a melt flow index of 2.8 g/10 min determined at 190 °C under a 2.16 kg piston load in accordance with ASTM D1238 or ISO 1133-1:2022. The low vinyl acetate content places Ateva 1070 closer to the semicrystalline polyethylene end of the EVA property range than to flexible EVA elastomers. Compared with EVA grades containing 18 wt% or 28 wt% vinyl acetate, the 9 wt% grade exhibits lower polarity, lower equilibrium moisture uptake, higher crystalline melting point, higher stiffness, and reduced room-temperature tack. In wire and cable compounds these characteristics make the resin more suitable as a modifier in blends than as a standalone flexible jacket material. The material is commonly evaluated for use in halogen-free flame-retardant systems, crosslinkable polyolefin insulation bases, and as a processing modifier for linear low-density polyethylene and metallocene polyethylene compounds. Published data for the specific electrical performance of this grade in final cable compounds is limited; furnace carbon black, mineral filler, silane, peroxide, and antioxidant packages alter the final dielectric properties. Users should obtain the manufacturer’s lot certificate and safety data sheet for batch-specific moisture, residual catalyst, and additive concentrations.

What processing and compounding boundaries apply to Ateva 1070 in wire and cable compounds?

The resin is supplied as pellets and should be stored in dry conditions. When the material has been exposed to relative humidity above 60%, pre-drying in a desiccant dryer at 60–70 °C for 2–4 h is typical before extrusion. Moisture in EVA copolymers can contribute to surface defects and hydrolytic ester cleavage at elevated processing temperatures, releasing acetic acid and reducing melt stability. Loss-on-drying moisture values are commonly determined by ASTM D6869 or ISO 15512:2019; the target residual moisture for continuous compounding is generally below 0.05 wt%. Because the 9 wt% vinyl acetate content is low, water absorption is lower than that of higher-VA EVA grades, but outdoor or humid storage in torn bags remains a process risk.

Compounding of Ateva 1070 on twin-screw extruders with length-to-diameter ratios from 24:1 to 44:1 is performed with barrel set temperatures in the range of 150–190 °C, with the homogeneous polymer melting zone usually not exceeding 190 °C. The melt flow index of 2.8 g/10 min produces a moderately viscous melt; screw configurations with intensive kneading blocks may raise melt temperature through viscous dissipation. Melt temperature measured at the die should be kept below 200 °C in standard formulations because prolonged residence time above 200 °C can induce deacetylation of the vinyl acetate comonomer. Deacetylation is indicated by an acetic acid odor, pressure fluctuation, and discoloration. The extruder should be purged with low-density polyethylene or linear low-density polyethylene before shutdown to avoid long residence of EVA in dead zones.

In cable compound production, screen packs are typically 40/80/120 mesh in breaker-plate assemblies, varying with filler loading. Gear pump assisted extrusion is preferred for stable melt pressure and for removing downstream gauge variation. The resin’s moderate rheology permits blending in both continuous twin-screw compounding and batch internal mixers, but batch mixer torque should be monitored through specific energy input; specific energy in twin-screw compounding is commonly in the range of 0.15–0.25 kW·h/kg for unfilled polyolefin compounds and higher for mineral-filled systems. Processing setpoints should be derived from lot-specific melt flow and torque-rheometer data rather than from nominal grade-only values.

In halogen-free flame-retardant cable jacket compounds, Ateva 1070 is evaluated as a partial replacement for LDPE or LLDPE to improve wetting and dispersion of magnesium hydroxide or alumina trihydrate fillers while limiting the increase in dielectric constant and moisture absorption associated with higher-VA EVA grades. Addition levels from 10 wt% to 30 wt% of the organic phase are typical when filler loadings are in the range of 50–65 wt% of total formulation mass; the exact level is adjusted against tensile elongation, low-temperature impact, and hot-set performance. Because the resin contains only 9 wt% vinyl acetate, its polarity is insufficient to fully encapsulate high-surface-area mineral flame retardants without additional compatibilizers such as maleic anhydride-grafted polyethylene or amino-silane-treated filler. Its value in such compounds is therefore primarily as a processing aid and as a crystallinity-reducing modifier that improves elongation retention compared with brittle LDPE-rich systems. The final compound must be tested to IEC 62631-3-1 for dielectric constant and dissipation factor, IEC 62631-3-2 or ASTM D257 for volume resistivity, and ASTM D2863 or ISO 4589-2 for limiting oxygen index when flame-retardant performance is claimed.

Differentiation of Ateva 1070 from higher-vinyl-acetate EVA grades in electrical insulation applications.

Higher-vinyl-acetate EVA copolymers are used in cable jackets when flexibility, adhesion to polar substrates, oil resistance, and filler compatibility are dominant. Increasing vinyl acetate from 9 wt% to 18 wt% or 28 wt% reduces the crystalline melting point from the range of approximately 95–108 °C to below 80 °C, lowers Shore hardness, raises elongation at break, and significantly increases polarity. The 9 wt% grade retains a higher crystalline fraction, which contributes to higher modulus, better resistance to deformation at elevated service temperatures, lower surface tack, and lower dielectric constant. This is a critical difference in insulation applications where capacitance and signal attenuation must be minimized. The dielectric constant of EVA rises with vinyl acetate content because the acetate dipole is polar; low-VA grades are typically closer to the nonpolar polyethylene range of 2.2–2.4, while more polar grades approach and exceed 3.0 at 1 MHz depending on measurement standard and filler content.

The melt flow index of 2.8 g/10 min is intermediate within the EVA pellet range. It is lower than high-flow grades used for injection molding and compounding ease, but higher than low-flow film and sheet grades that require high melt strength. In wire and cable extrusion, this melt flow index is suitable for profile extrusion and for compounding operations where filler dispersion is required without excessively reducing molecular weight. If the resin is blended at levels above 30 wt% in unfilled insulation compounds, the final melt flow index may become too high for some tube-on extrusion lines, and melt fracture or draw-down instability can occur. Conversely, if it is blended at levels below 5 wt%, the influence on filler dispersion and surface quality may be negligible.

When Ateva 1070 is blended with metallocene LLDPE in silane-crosslinkable insulation

In silane-grafted moisture-crosslinked cable insulation, Ateva 1070 can be used as a rheology modifier and as a carrier for silane-grafting reactions, provided that the peroxide and vinyl silane ratios are controlled for the combined polymer blend. The vinyl acetate comonomer at 9 wt% introduces a limited number of polar acetate groups, which can participate in hydrogen-bond-like interactions with moisture and silanol species but does not contain the high concentration of polar groups found in high-VA grades. When the blend is processed in a twin-screw extruder, the peroxide half-life at the selected melt temperature must be considered; dialkyl peroxides commonly used for silane grafting have 10-hour half-life temperatures in the range of 120–140 °C, but extrusion temperatures for adequate melt flow are often higher, so the peroxide is metered carefully and supported by a thermal stabilizer package. The processor should monitor gel content after accelerated water bath curing at 80–95 °C for 4–8 h in accordance with ASTM D2765 or ISO 10147:2023 and hot-set elongation under load per IEC 60811-507. Ateva 1070 may reduce the maximum attainable gel content compared with a pure mLLDPE silane compound because the vinyl acetate side groups can consume part of the initiator and because residual polar monomers alter crosslink density. Published data for this specific mLLDPE-Ateva 1070 silane configuration is limited, so pilot-scale trials are required before production.

The lower vinyl acetate content of Ateva 1070 compared with higher-VA EVA is expected to maintain a lower dissipation factor in a silane-crosslinked blend, but the final value depends on crosslinking byproducts, humidity, and antioxidant loading. Dielectric measurements should be taken after conditioning at 23 °C and 50% relative humidity for 48 h according to ASTM D150 at frequencies of 50 Hz and 1 MHz. If the insulation is intended for medium-voltage applications, partial discharge and long-term water treeing tests must be performed; the low-VA resin is not a substitute for dedicated water-tree-retardant insulation compounds.

Incoming inspection of Ateva 1070 at a cable manufacturing plant typically includes melt flow index confirmation, vinyl acetate content verification by infrared spectroscopy, pellet moisture measurement, and visual inspection for fines, discolored pellets, or contamination. Lot-to-lot variability in melt flow index should be controlled within the producer’s specification range; large shifts in melt flow index can alter extruder screw fill length, melt pressure, and final insulation shrinkback behavior. The resin should not be blended with amine-based stabilizers or flame retardants that can accelerate ester hydrolysis or deacetylation at melt temperatures. Equipment cleaning between runs is simpler than for high-VA EVA grades because the lower surface tack of Ateva 1070 reduces pellet clustering and feed-throat bridging. However, long extrusion campaigns at high screw speed may still generate low-level acetic acid volatile emissions, and local exhaust ventilation is required in enclosed compounding areas.