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Anhui Liwei Chemical Co., Limited.

ELVAX 9756 Ethylene Vinyl Acetate Copolymer

    • Product Name: ELVAX 9756 Ethylene Vinyl Acetate Copolymer
    • Factroy Site: Lingwu, Yinchuan, Ningxia, China
    • Price Inquiry: sales2@liwei-chem.com
    • Manufacturer: Anhui Liwei Chemical Co., Limited.
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    Specifications
    HS Code 408060
    Vinyl Acetate Content 19.5%
    Melt Flow Index 6 g/10 min
    Density 0.937 g/cm³
    Melting Point 85 °C
    Glass Transition Temperature -33 °C
    Tensile Strength At Break 10.3 MPa
    Elongation At Break 600%
    Hardness 85 Shore A
    Softening Point 126 °C
    Flexural Modulus 25 MPa
    Refractive Index 1.500
    Melt Viscosity 1500 cP at 140 °C

    As an accredited ELVAX 9756 Ethylene Vinyl Acetate Copolymer factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.

    Packing & Storage
    Packing ELVAX 9756 EVA copolymer supplied as free-flowing pellets in 25 kg multiwall paper bags, ready for processing.
    Container Loading (20′ FCL) 20′ FCL container loading of ELVAX 9756 Ethylene Vinyl Acetate Copolymer: palletized bags stowed securely, protected from moisture, ensuring stable, full-container transport.
    Shipping ELVAX 9756 is shipped as solid pellets in multi-layer paper bags or FIBCs. Protect from moisture, heat, and direct sunlight. Store in a cool, dry area. Avoid dust accumulation and ignition sources. Non-hazardous under normal transport; keep segregated from strong oxidizers.
    Storage Store ELVAX 9756 Ethylene Vinyl Acetate Copolymer in a cool, dry, well-ventilated area, away from direct sunlight, heat, and ignition sources. Keep the original container tightly sealed when not in use to prevent moisture absorption or contamination. Avoid exposure to oxidizing agents. Under proper conditions, material remains stable with adequate shelf life.
    Shelf Life Typically two years when stored in original containers, kept cool, dry, and protected from direct sunlight.
    Application of ELVAX 9756 Ethylene Vinyl Acetate Copolymer

    In carton-sealing lines running at 5575 m/min, ELVAX 9756 is specified as the polymer backbone in high-viscosity hot melt adhesives applied through slot coaters at 150170 °C. The nominal 18 wt% vinyl acetate level is low enough to limit ester hydrolysis in humid packaging environments but high enough to maintain compatibility with hydrocarbon tackifiers. In production-scale vertical sigma blade mixers of 180 L working capacity, the compound is mixed under N₂ at 0.10.3 bar overpressure for 3550 min, then discharged as 1520 mm pastilles through a water-cooled belt. The formulation window places ELVAX 9756 at 2535 wt%, a C5/C9 hydrocarbon tackifier at 4055 wt%, microcrystalline wax at 1525 wt%, and a hindered phenolic antioxidant at 0.10.5 phr. Packaging converters report that nozzle blocking and adhesive stringing remain controlled when zinc stearate is held below 0.2 wt% and primary amine additives are excluded. Compliance is established under FDA 21 CFR 175.105 for food-contact adhesives, with final-article migration assessed under Regulation (EU) No 10/2011 and its amendments. Finished product classes include corrugated board case sealing, book spine gluing, and paper label attachment. Open time is adjusted through wax level rather than temperature elevation because ester degradation accelerates above 180 °C; published data for this specific configuration is limited when filler loading exceeds 20 wt%.

    Can Aluminum Trihydrate-Filled ELVAX 9756 Compounds Maintain a Balance Between LOI and Elongation at Break in HFFR Wire Jacketing?

    Water-release kinetics from aluminum trihydrate govern the lower processing-temperature boundary in halogen-free flame retardant cable jacketing. ELVAX 9756 is compounded at 3045 wt% of the polymer phase, while ATH or magnesium dihydroxide is loaded at 5565 wt% of the total compound. ATH endothermic decomposition releases approximately 34.6 wt% water over 200320 °C; this limits barrel settings to 110140 °C on a co-rotating twin-screw extruder with L/D 28:1 to 40:1. In jacketing lines, melt is crosshead-extruded onto copper conductors at 120160 °C; die draw-down ratio is kept below 2.5:1 to avoid filler orientation and surface tearing. Production-scale evidence from HFFR lines shows that when screw temperature overshoots 170 °C, residual water from mineral filler creates pitting defects in the jacket and raises melt-pressure fluctuation by more than 15%; corrective action includes reducing screw speed from 250350 rpm to 200280 rpm and increasing feed-zone cooling. Compliance testing is conducted under IEC 60332-1-2 for single-cable flame propagation, IEC 60754-2 for corrosivity of combustion gas, and EN 50575:2014 for construction-product reaction to fire. Representative HFFR compound data are shown in Table 1; grade-specific validation on ELVAX 9756 is required before production lot qualification.

    ATH loading (wt%)ELVAX 9756 in polymer phase (wt%)LOI (%)Tensile strength (MPa)Elongation at break (%)
    55302812.5220
    60353111.0180
    6540349.5140

    The values in Table 1 are reference data from publicly available HFFR compound studies and are not a guaranteed processing specification for ELVAX 9756. Finished cable types include control cable sheathing, building wire bedding, and flame-retardant instrumentation cable. Granulation through a water-ring pelletizer requires inlet water below 40 °C to prevent pellet agglomeration.

    If Dicumyl Peroxide Half-Life Intervenes Before Azodicarbonamide Gas Evolution in Footwear Midsole Injection Molding

    To prevent premature crosslinking, melt temperature is limited to 95115 °C during first-pass compounding of ELVAX 9756 foamable formulations for injection-molded footwear midsoles. The base formulation contains 100 phr ELVAX 9756, 520 phr ethylene-octene elastomer, 0.54.0 phr azodicarbonamide, 0.10.6 phr dicumyl peroxide, 0.20.8 phr antioxidant, and 010 phr calcium carbonate. The one-minute half-life of dicumyl peroxide is near 180 °C, while azodicarbonamide gas evolution peaks at 205215 °C; this narrow thermal overlap forces low-shear mixing in an internal mixer or co-rotating twin-screw extruder before pellets are injection molded at 160175 °C. Multi-cavity midsole tools require clamp force above 150 t, with mold temperature held at 2035 °C to freeze the foam skin. Density reduction is controlled between 1.4× and 1.8× expansion, yielding midsole densities of 0.150.25 g/cm³. Hardness and compression set are tested under ISO 868 and ASTM D395-18, respectively. Restricted substance compliance follows REACH Regulation (EC) No 1907/2006 Annex XVII and the ZDHC MRSL if the foam enters a footwear-manufacturing facility. Residual blowing agent and peroxide by-products are controlled at part level by gas chromatography. Pre-drying at 6070 °C for 4–6 h is required if granulate moisture exceeds 0.05 wt%; failure to do so produces surface pinholes in the molded skin. Finished products include athletic midsoles, sandal footbeds, and work boot cushioning components.

    Directly downstream of the chill roll in tandem extrusion laminating lines running at 120220 m/min, ELVAX 9756 is specified as a sealant skin on aluminum foil or corona-treated films. The resin is blended with low-density polyethylene at 2040 wt% to maintain web dimensional stability; the melt is fed through a slot die onto a primed substrate and quenched on a chill roll at 1218 °C. Seal-layer thickness is controlled to 1535 µm. Heat-seal initiation occurs near 8595 °C, and hot-tack strength is quantified with ASTM F1921. Compliance for monolayer food contact rests on FDA 21 CFR 177.1350 and Regulation (EU) No 10/2011 overall migration limits of 10 mg/dm². On a 1.5 m die, increasing ELVAX 9756 above 50 wt% of the sealant blend produces neck-in beyond 25 mm, raising edge trim loss and requiring deckle adjustment. Lamination line data indicates that moisture uptake above 60% RH before extrusion generates bubble defects; pre-drying at 6570 °C for 4–6 h is therefore mandatory. Finished products are retortable lidding film, high-fat powder sachets, and pharmaceutical blister lidding. Published data for this specific configuration is limited at line speeds above 200 m/min.

    Twin-Screw Masterbatch Carrier Systems for High-Temperature Polyolefin Films

    When a polyolefin film converter requires pigment loadings above 30 wt% without excessive carrier viscosity, ELVAX 9756 is incorporated as a carrier resin in masterbatch manufacturing. The concentrate formulation uses 3060 wt% pigment, 1040 wt% ELVAX 9756 carrier, 520 wt% processing aid, and 010 wt% wax. Compounding is performed on an intermeshing co-rotating twin-screw extruder with L/D 32:1 to 48:1 and barrel temperatures from 100 °C to 150 °C; a screen changer with 100200 mesh filtration captures agglomerates. The high-speed pre-mixer operates at 6001,200 rpm for 512 min to wet pigments before extrusion. In downstream blown-film or cast-film lines, the masterbatch is let down at 25 wt%. Regulatory acceptance for indirect additives in packaging follows FDA 21 CFR 178.3297 and REACH registration; final packaging is assessed under Regulation (EU) No 10/2011. Storage moisture above 60% RH requires pre-drying at 6070 °C for 4–6 h. Finished products are colored blown film, cast film, and sheet for packaging.

    Predicting Density Collapse in Crosslinked Closed-Cell EVA Foam Sheet Under Reduced Press Cure Time

    Batch-to-batch density variation is the central process variable in crosslinked closed-cell EVA foam sheet used for thermal insulation and anti-vibration pads. The compound uses 100 phr ELVAX 9756, 2040 phr ethylene-propylene rubber or metallocene polyethylene, 13 phr azodicarbonamide, and 0.30.7 phr dicumyl peroxide. The mixed slab is calendered to 412 mm thickness and expanded in a steam-heated multi-daylight press at 155170 °C and 4080 kg/cm², then cooled to 25 °C before demolding. Density for roll stock is maintained at 0.080.20 g/cm³; press cure time is controlled to ±20 s because insufficient gel formation allows gas loss and density collapse, while excessive cure increases hardness beyond the targeted 3555 Shore C range. Material performance is classified under ASTM D1056-14 for flexible cellular materials, with flammability of automotive interior end uses evaluated under FMVSS 302. REACH registration and restricted substance documentation under REACH Regulation (EC) No 1907/2006 apply. Finished products include HVAC gaskets, anti-vibration pads, and thermally insulating pipe wraps. Published data for this specific configuration is limited because press cure parameters vary with tool volume; qualification runs on a production press are required.

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    Certification & Compliance
    More Introduction

    ELVAX 9756 ethylene vinyl acetate copolymer is supplied as a pelletized random copolymer in which vinyl acetate comonomer units interrupt the polyethylene crystallite structure. The resulting resin has lower crystalline melting point, lower stiffness, and higher polarity than LDPE homopolymer. Its lot-to-lot consistency is controlled against the nominal values listed in the table below.

    Nominal properties of ELVAX 9756 from supplier technical bulletin
    PropertyMethodNominal value
    Vinyl acetate contentASTM D559418%
    Melt mass-flow rateISO 1133-1:2022, 190 °C/2.16 kg6.0 g/10 min
    DensityISO 1183-1:20190.94 g/cm³

    Incoming-resin qualification should include melt mass-flow rate, vinyl acetate content, density, and visual contamination. Sampling from 3 bags per lot with a clean stainless steel thief is typical before release to production. Melt-flow variation outside ±10% of the supplier’s nominal value has been associated with visible viscosity drift on slot-die coating and wax-coating lines.

    The grade occupies a middle position within the ELVAX line. Relative to ELVAX 40W with nominal 40% vinyl acetate and 52 g/10 min, ELVAX 9756 has lower VA-derived polarity and a lower melt flow rate, so it produces higher melt viscosity at constant addition and less aggressive plasticization of nonpolar wax matrices. Relative to ELVAX 210 with nominal 28% vinyl acetate and 400 g/10 min, ELVAX 9756 disperses more slowly in low-shear blending but contributes less surface tack and less low-temperature adhesion to polar substrates. These differences define the grade’s practical use in compounds where wax compatibility, cohesive strength, and controlled open time take precedence over maximum adhesion to aluminium or polyester.

    What Limits Screw Speed When ELVAX 9756 Is Run on a Twin-Screw Compounder?

    On a 40 mm co-rotating twin-screw extruder with 44 L/D and modular screw geometry, the practical screw-speed ceiling for ELVAX 9756 is set by viscous heating rather than motor torque. Barrel zones from feed to die are typically set at 160 °C, 170 °C, 180 °C, 190 °C, 190 °C, 190 °C, and 180 °C. At screw speeds above 450 min⁻¹, melt temperature can rise to 220–230 °C because energy dissipation in kneading blocks is not removed quickly enough by barrel cooling. Degradation of the vinyl acetate segment begins to release acetic acid and shifts the melt from translucent to yellow; the odor threshold for acetic acid on the shop floor becomes detectable before the melt index rises significantly.

    Melt pressure at the die plate is normally 2–4 MPa at 300 min⁻¹. Die-face pelletizing remains stable when the melt is filtered through a 200 µm breaker plate and the water-ring cutter is set to maintain pellet temperature below 60 °C at the outlet. The same compounding line can process ELVAX 210 at higher throughput with less restrictive screw geometry because its lower melt viscosity reduces shear heating; this difference in viscous heat accumulation is the main reason the two grades are not interchangeable in a fixed screw configuration.

    Thermal stability of ELVAX 9756 in compounding is assessed by melt-flow shift and color development. At melt temperature 210 °C and residence time above 20 min, the melt flow rate can increase by 10–30% relative to virgin pellets because chain scission of the vinyl acetate fraction releases acetic acid. Hindered phenolic antioxidant at 0.1–0.3 phr and phosphite stabilizer at 0.1–0.2 phr are added when regrind ratios exceed 20% by mass. The stabilizer package is selected for low migration in food-contact applications and for compatibility with hydrocarbon tackifiers in hot-melt adhesives.

    Addition of 1–5 wt% ELVAX 9756 to a 58–60 °C paraffin wax is performed in a jacketed vessel equipped with a Cowles disperser. The polymer is added slowly to wax at 120–150 °C under medium shear until a clear solution is obtained, typically 30–60 min. The resulting wax blend has smaller crystal domains and higher viscosity. At 5 wt% loading, congealing point measured by ASTM D938 typically increases by 2–5 °C, and kinematic viscosity at 100 °C by ASTM D445 may rise from 4–6 mm²/s to 12–18 mm²/s depending on the wax distillation range. Published data for this specific configuration is limited to wax-dependent ranges because feedstock composition and oil content control the final rheology more than the polymer grade alone.

    Compared with higher-VA grades such as ELVAX 210, ELVAX 9756 gives better solubility in nonpolar paraffin and less phase separation on cooling, which is important for candle and coating systems that require low surface tack. Compared with lower-VA grades such as ELVAX 770 with nominal 9% vinyl acetate and 0.8 g/10 min, ELVAX 9756 disperses more easily and gives lower final blend viscosity at equivalent addition levels, while providing less hardness reduction.

    Adhesion Build Rate in Slot-Die-Coated Hot-Melt Formulations

    In hot-melt adhesive compounding with hydrocarbon tackifiers and paraffin wax, ELVAX 9756 is often formulated at 30–35 wt% polymer, 40–50 wt% tackifier, 15–25 wt% wax, and 0.5 wt% hindered phenolic antioxidant. The adhesive is applied with a slot-die coater at 175–185 °C and a coat weight of 25–50 g/m². On corona-treated polyethylene terephthalate, T-peel adhesion after 24 h by ASTM D1876 is governed by cohesive failure rather than interfacial debonding when the formulation is within this envelope. The open time on a 23 °C steel panel is typically 5–15 s; adding more high-softening-point tackifier extends open time, while the EVA grade controls the green-strength plateau.

    Shear adhesion failure temperature can be evaluated by ASTM D4498 with a 1.0 kg load and 25 °C/min ramp; values in the range of 60–80 °C are common for wax-containing formulations but are highly dependent on tackifier softening point. Compared with ELVAX 40W, ELVAX 9756 gives lower wetting on aluminium and corona-treated polyester; an additional 2–5 wt% polar tackifier or a lower wax content may be required to match low-temperature adhesion. The trade-off is a reduction in cold-flow tendency and an increase in die-cutting cleanliness for label and tape applications.

    For injection molding of ELVAX 9756, melt temperature is held at 180–200 °C and mold temperature at 10–30 °C because the grade has low crystallinity and cools slowly relative to polypropylene. A clamp force of 3–5 kN/cm² of projected area is sufficient for conventional parts, but full shot weight and hot-runner pressure loss must be evaluated because the high thermal expansion of EVA can cause flash if fill speed is excessive at the end of the stroke. Holding pressure of 40–60 MPa and gate freeze time of 2–4 s reduce sink marks and warpage in sections thicker than 3 mm.

    Mold shrinkage measured by ASTM D955 on a 3.2 mm plaque is typically 1.5–2.5%, which is higher than LDPE homopolymer and must be compensated in tool design. The shear viscosity of ELVAX 9756 at 190 °C and 100 s⁻¹ is typically 800–1200 Pa·s; at 1000 s⁻¹ it falls below 300 Pa·s. These values explain why thin-wall filling requires melt temperature at the upper end of the range and why hot-runner temperature should not exceed 210 °C. The grade is less tacky than high-VA EVA and therefore easier to feed by screw conveyor from a dryer hopper; this is a practical difference from ELVAX 40W on humid production days.

    When Pellet Pre-Drying Is Omitted in Humid Converting Environments

    Moisture-related defects appear first as splay or surface roughness on extruded melt, not as catastrophic hydrolysis. The bulk EVA pellet absorbs little moisture, but condensation on pellets stored in outdoor silos or fed from open hoppers above 60% RH is sufficient to produce gas inclusion in the melt. Pre-drying at 60 °C for 4 h in a desiccant bed dryer with a dew point of −40 °C is the standard corrective action. Karl Fischer titration of a sample drawn after drying should read below 0.05% moisture.

    When pre-drying is omitted, melt-pressure oscillation at the extruder head typically exceeds 0.5 MPa at 300 min⁻¹ and becomes visible as periodic surge at the die. Amine-based additive packages are not recommended in formulations containing vinyl acetate because residual acetic acid from thermal exposure can react to form salts that plate out on calender rolls or chill-roll surfaces; this is not a crosslinking mechanism but a surface-defect source. The same is true for zinc stearate in excess of 0.2 phr, which can generate clogging in screen packs when recycled EVA is processed at 200 °C for extended residence time.

    In blown film extrusion at 40–60 µm gauge, the bubble is more sensitive to draft changes than LDPE because the EVA melt has lower melt strength. A blow-up ratio of 2.0–2.5:1 and a frost line height of 3–6 die diameters are typical starting points at a melt temperature of 170–190 °C. Dart impact measured by ASTM D1709-16A depends on gauge and film age; practical values are 200–400 g for 50 µm film, while Elmendorf tear by ASTM D1922 is generally higher in machine direction than in transverse direction. Film testing is performed after 40 h conditioning at 23 ± 2 °C and 50 ± 5% RH in accordance with ASTM D618.

    The difference from high-VA film grades is lower blocking and lower coefficient of friction after winding, which reduces the need for external slip additives but lowers puncture resistance at −20 °C. Low-temperature flexibility is characterized by dynamic mechanical analysis; EVA with moderate VA content exhibits a loss tangent peak near −20 °C, whereas LDPE homopolymer retains higher modulus at that temperature but has lower clarity. This shift is responsible for lower low-temperature impact toughness of EVA films compared with metallocene LLDPE.

    In extrusion coating onto paper and aluminium foil, ELVAX 9756 is processed at 190–220 °C with coat weights of 10–25 g/m². Adhesion to aluminium foil is improved by corona or ozone treatment; peel strength measured by ASTM D1876 is lower than that of acid copolymer or anhydride-grafted tie resins. The grade is not recommended for aggressive high-temperature retort structures because EVA softens above 70 °C. Compared with ethylene methacrylic acid copolymers, ELVAX 9756 offers lower metal adhesion but better moisture vapor barrier retention and lower corrosive by-product generation.

    Regulatory compliance for ELVAX 9756 follows the EVA copolymer framework. Under EU 1907/2006, ethylene and vinyl acetate monomers are registered as monomers; the polymer itself is exempted from registration but must be supported by a safety data sheet reflecting the supplied pellet form. Under FDA 21 CFR 177.1350, EVA copolymers may qualify for food-contact use when the vinyl acetate portion and total extractives meet the migration limits specified in the regulation; confirmation is required for the specific antioxidant and slip additive package. Under RoHS 2011/65/EU, typical ELVAX 9756 does not contain the six restricted substances above threshold values, but verification against the actual certificate of analysis is required for electrical and electronic applications.