HANWHA EVA 1125

Among low-vinyl-acetate ethylene-vinyl acetate copolymers, HANWHA EVA 1125 is classified by a nominal vinyl acetate content of 11 wt% and a melt flow index of 25 g/10 min at 190 °C under a 2.16 kg load, measured according to ISO 1133-1:2022. The pelletized resin has a typical density of 0.934 g/cm³ under ISO 1183-1:2019, a melting endotherm near 91 °C by ISO 11357-3:2018, and a Vicat softening temperature of approximately 64 °C under ISO 306:2022 using the A/120 method. The grade is supplied in pellet form and is used in hot-melt adhesives, foam extrusion, masterbatch carriers, and flexible wire-and-cable compounds. Its low vinyl acetate content distinguishes it from higher-VA grades by increasing stiffness, tensile strength, and heat resistance while reducing tack, polarity, and elongation at break.

On commercial polyolefin conversion lines, the material is typically processed as a modifier or carrier resin rather than as a stand-alone film resin. Because the melt flow index is high, line operators often reduce barrel temperatures by 10–20 °C relative to LDPE grades with equivalent melt flow index to avoid overplasticization and head-pressure instability.

The grade belongs to the low-VA segment of the EVA family and is therefore closer in mechanical behavior to low-density polyethylene than to elastomeric high-VA copolymers. This positioning affects dispersibility in hot-melt adhesives, dimensional stability in foamed sheet, and polarity-dependent adhesion in coextruded structures.

Molecular Composition and Melt Rheology Boundaries

The 11 wt% vinyl acetate comonomer introduces polar acetate side groups along the polyethylene backbone, lowering crystallinity and melting point compared with low-density polyethylene homopolymer. The 25 g/10 min melt flow index places the material in a low-viscosity regime suitable for adhesive application and filler wetting. Capillary rheometry under ISO 11443:2021 at 180 °C and a shear rate of 10³ s⁻¹ typically produces apparent viscosity below 50 Pa·s, which allows high filler loadings and thin die lips without excessive backpressure. The shear-thinning index between 10² s⁻¹ and 10³ s⁻¹ is moderate; melt temperature changes above 200 °C reduce viscosity more strongly than further increases in screw speed. The manufacturer does not publish complete molecular weight distribution data for this grade, so rheological control on the shop floor is normally based on melt flow index and melt pressure.

For incoming inspection, batch-to-batch melt flow index variation is typically controlled within ±2 g/10 min to maintain adhesive pot life and extrusion output. A variation greater than ±2 g/10 min shifts the required gear-pump suction pressure and can change coat weight in slot-die adhesive application.

Thermal stability in air is typically monitored by thermogravimetric analysis at 10 °C/min; onset of mass loss normally occurs above 300 °C, but melt processing is limited by oxidation rather than by pyrolysis. Addition of antioxidant masterbatch at 0.1–0.3 wt% is common in adhesive formulations intended for prolonged hot-melt tank residence.

What Limits Throughput in Hot-Melt Adhesive Compounding?

In hot-melt adhesive production, throughput is limited less by melt viscosity than by filler wetting and thermal degradation. On a co-rotating twin-screw extruder with a 40:1 L/D ratio and segmented screw elements, barrel settings from 120 °C at the feed throat to 160 °C at the die are used to maintain melt temperatures below 180 °C. If melt temperature exceeds 200 °C, oxidative chain scission accelerates and the melt flow index increases, producing viscosity drop and char formation at the die lip. Adhesive compounds containing 30–40 wt% resin-extended hydrocarbon tackifiers can be processed without exceeding 70% of drive torque, but die pressure becomes unstable when filler loading exceeds 40 wt% at screw speeds above 350 min⁻¹. Nitrogen blanketing or desiccant drying is required when ambient relative humidity exceeds 60%; moisture above 0.05 wt% produces surface voids and reduces peel adhesion in the applied adhesive.

The processing window is narrow when tackifiers with softening points above 110 °C are added; the practical melt temperature range is ±5 °C around 160 °C because lower temperatures produce unmelted gel flecks and higher temperatures begin to degrade the tackifier. Operators using gear pumps typically set suction pressure below 20 bar to avoid cavitation at high screw speeds.

Tackifier compatibility should be checked by film clarity after compression molding at 160 °C and by ring-and-ball softening point retention under ASTM D36-09. A drop in softening point greater than 5 °C after 72 h at 180 °C indicates resin aging.

Limitations: EVA 1125 should not be combined with amine-based antistatic additives or unneutralized basic fillers because residual basic species can catalyze deacetylation at processing temperatures above 200 °C, releasing acetic acid and corroding downstream equipment. Pre-drying at 60 °C for 4 h in a desiccant dryer with a dew point of −40 °C is recommended before extrusion when moisture content exceeds 0.05 wt%.

For cross-linked foam extrusion, EVA 1125 is blended with chemical blowing agents such as azodicarbonamide or oxybis(benzenesulfonyl hydrazide). The decomposition temperature of azodicarbonamide is approximately 205 °C, which requires a barrel profile no higher than 170 °C in the compression zone to avoid premature nucleation. On a 65 mm single-screw extruder with a 30:1 L/D barrier screw, a typical profile is 130 °C feed, 150 °C compression, 165 °C metering, and 160 °C die. Lower vinyl acetate content compared with an 18 wt% VA foam grade reduces polar adhesion to metal surfaces, which can reduce screw fouling but also reduces moisture uptake and can lower the solubility of polar blowing agents. Published data for this specific configuration is limited; gel content after peroxide crosslinking should be measured by ASTM D2765-16 and is typically controlled between 60% and 70% for foam closure and compression set resistance.

Foam density variations on a 65 mm line have been observed when die pressure deviates more than 5 bar from the set point, because gas nucleation is pressure-dependent. A melt pump upstream of the die is used to reduce pressure pulsation and maintain cell size uniformity. When the melt temperature at the die exceeds 175 °C, the blowing agent decomposes before leaving the die and surface blistering occurs.

When used as a masterbatch carrier, the low melt viscosity of EVA 1125 permits carbon black concentrations up to 40 wt% on a co-rotating twin-screw extruder with a 40:1 L/D geometry. Melt temperatures are maintained between 170 °C and 190 °C; exceeding 220 °C causes thermal degradation and increased volatiles. The carrier is let down at ratios between 2% and 5% in polyolefin films. Film-blowing lines with 1.5 mm die gaps should not exceed 220 °C melt temperature to prevent gel formation. In injection molding of masterbatch-containing polypropylene, clamp force requirements are normally governed by the base resin, not by the EVA carrier.

Pigment dispersion quality should be assessed by pressure rise on a 14 µm extruder screen pack. A pressure increase above 5 bar/h indicates undispersed agglomerates and requires adjustment of screw configuration or masterbatch letdown ratio.

When EVA 1125 Replaces a Higher-VA Grade in Wire and Cable Jacketing

Substitution of EVA 1125 for a 28 wt% VA grade raises tensile strength and hardness but reduces elongation and low-temperature flexibility. Under ASTM D638-14 Type IV testing at 50 mm/min, tensile strength at break is approximately 15 MPa and elongation at break is approximately 700%; the higher-VA reference exhibits tensile strength near 8 MPa and elongation above 800%. Hardness is approximately 93 Shore A under ASTM D2240-15, which improves crush resistance but limits installation flexibility below −20 °C. The lower vinyl acetate content reduces dielectric constant to approximately 2.4 at 1 MHz under IEC 60250, whereas a 28 wt% VA grade may show 2.8. Adhesion to copper and aluminum conductors is lower; a tie layer or primer is required when jacket integrity under wet aging is specified by UL 44 or IEC 60502-1.

For extrusion jacketing on a 60 mm single-screw extruder with a 24:1 L/D polyethylene screw, barrel temperatures from 140 °C to 175 °C produce a smooth jacket surface. Above 180 °C, oxidative degradation can create surface roughness and color shift; below 140 °C, backpressure rises and conductor adhesion becomes inconsistent. The material is not a direct drop-in replacement for higher-VA grades in applications requiring UL 62 low-temperature flexibility or flame-retardant formulations containing high loadings of melamine cyanurate because the lower polarity reduces filler incorporation stability.

For flame-retardant insulation, the resin can be compounded with 60–70 wt% mineral fillers such as aluminum hydroxide or magnesium hydroxide, but the coil life of the cable line may decrease because the low VA content provides less adhesion between filler particles and matrix. In such formulations, elongation retention after 7 days at 121 °C should be measured using ASTM D638-14 and is often below 50% unless coupling agents are used.

Storage and regulatory handling are governed by the same boundary conditions. Store pellets below 30 °C and below 60% RH. If surface moisture exceeds 0.05 wt%, pre-drying at 60 °C for 4 h in a desiccant dryer with −40 °C dew point is required. Do not expose the resin to direct sunlight for prolonged periods because UV-induced surface oxidation can shift the melt flow index. The neat resin is typically registered under REACH and is not classified as hazardous under CLP Regulation (EC) No 1272/2008. For food-contact use, finished-article testing under EU Regulation 10/2011 and FDA 21 CFR 177.1520 is required because process additives and degradation products determine final compliance. Directive 2011/65/EU RoHS restrictions apply to the finished article; a neat olefinic copolymer generally does not contain Pb, Cd, Hg, Cr(VI), PBB, or PBDE above the maximum concentration values, but analytical verification is required.

Incompatibility: Avoid combinations with amine-based stabilizers or basic fillers above 200 °C because deacetylation may generate acetic acid and reduce molecular weight. The product is not recommended for continuous exposure above 80 °C without crosslinking or antioxidant stabilization. Processing equipment with long residence times above 30 min at melt temperatures above 180 °C should be avoided because viscosity can drift out of specification.