SINOPEC Sanren EVA 12/0.5

In coextruded blown-film structures for frozen food and industrial liner markets, SINOPEC Sanren EVA 12/0.5 is introduced as the sealant layer component. The grade carries a vinyl acetate content of 12% by weight and a melt flow rate of 0.5 g/10 min under 190°C and 2.16 kg load per ISO 1133-1:2022. The sealant layer accounts for 15% to 20% of total film thickness. The low MI provides high melt tension; on a 55 mm barrier screw extruder with an L/D of 30:1, bubble diameter remains stable at blow-up ratios of 2.0:1 to 2.4:1 and frost line heights of 8 to 12 times die diameter. The vinyl acetate comonomer depresses seal initiation temperature to approximately 85°C to 95°C, compared with 100°C to 110°C for LDPE-rich sealants. Extrusion temperature zones are set from 150°C to 180°C, with die temperature held at 185°C to 195°C and die gap at 1.2 mm to 1.8 mm. Residence time should not exceed 15 min at 200°C because acetic acid elimination from vinyl acetate can corrode downstream equipment. Pre-drying at 70°C to 80°C for 4 h is required when storage humidity exceeds 60% RH. Seal strength of an 80 µm sealant layer reaches 2.5 N/15 mm to 4.0 N/15 mm after a 0.5 s dwell at 120°C and 2 bar jaw pressure when tested according to ASTM F88/F88M-21. Compliance for food-contact use rests on FDA 21 CFR 177.1350 and EU No 10/2011, with overall migration below 10 mg/dm² per EN 1186-1. Terminal articles include frozen vegetable pouches, vertical form-fill-seal films, and heavy-duty PE/EVA liners.

Why does 12/0.5 raise foam hardness without lifting compound MI?

Compounding trials on a 55 L internal mixer show that SANREN EVA 12/0.5 serves as a hardness modifier and melt-strength donor in crosslinked foam sheet compounds based on EVA 18/3. The grade is normally charged at 20 phr to 30 phr against 70 phr to 80 phr of a higher-MI EVA matrix. Because the SANREN grade has an MI of 0.5 g/10 min, it raises compound green strength and final Shore A hardness without reducing the mixture below the flow level required for mill sheeting. Mixing follows a defined thermal sequence: chamber preheat to 100°C, flux for 2 min, addition of zinc oxide and zinc stearate, batch discharge at 105°C to 110°C. Azodicarbonamide at 2.5 phr to 4.0 phr and dicumyl peroxide at 0.6 phr to 0.9 phr are added on a two-roll mill held below 100°C to prevent premature decomposition. Press foaming and crosslinking are performed at 165°C to 175°C for 8 min to 12 min. Dicumyl peroxide half-life data define the processing window: approximately 30 min at 140°C, 5 min at 160°C, and 1 min at 170°C.

Foam density after cooling is typically 0.12 g/cm³ to 0.18 g/cm³, Shore A hardness 45 to 60, tensile strength 1.5 MPa to 2.5 MPa, and elongation at break 150% to 250% when tested per ASTM D3575-20. Gel content measured by xylene extraction under ASTM D2765-16 is controlled at 65% to 75%. The compound is not suitable for injection-molded sole units because MI is below 1 g/10 min and cavity filling would require excessive shear heating. Terminal articles are die-cut sports mats, anti-fatigue mats, protective padding, and midsole reinforcement components.

When 12/0.5 is metered into polymer-modified bitumen at low shear

Torch-applied roofing membranes based on oxidised bitumen require a polymer modifier that raises softening point without making the membrane brittle at sub-zero temperatures. SANREN EVA 12/0.5 is metered at 3 wt% to 6 wt% based on bitumen mass into a vertical low-shear paddle mixer holding bitumen at 170°C to 185°C. Mixing continues for 1.5 h to 2.5 h until the mixture is optically free of polymer particles. The low MI of 0.5 g/10 min yields high-molecular-weight chains that form a swollen network in the bitumen matrix; the 12% vinyl acetate content moderates phase separation and improves low-temperature flexibility. Process temperature is constrained by two boundaries: above 190°C, vinyl acetate degradation can release acetic acid; below 160°C, the polymer does not fully disperse at practical shear rates. If the mixer is operated above 190°C, a nitrogen blanket is applied. Softening point measured by ASTM D36 increases by approximately 15°C to 25°C at 5 wt% addition in a 70/100 penetration-grade base bitumen, but published data for SANREN 12/0.5 in this specific configuration is limited and the actual shift depends on bitumen source and oxidation level. Penetration at 25°C per ASTM D5 is maintained at 60 dmm to 70 dmm, and low-temperature flexural performance is checked by ASTM D5147 at ≤−10°C on a 1 mm coating. Viscosity at 180°C is controlled according to ASTM D4402 to remain below the maximum pumpable limit of the coating line. Terminal products are polyester-reinforced torch-applied waterproofing sheets, self-adhesive roof underlayments, and bridge-deck membrane systems. Compliance is assessed under REACH, EN 13707 for reinforced roofing sheets, and ASTM D6222 for polyester-reinforced materials.

Halogen-free flame-retardant cable jacket compounds that place SANREN EVA 12/0.5 at the base-resin position are prepared on twin-screw extruders with an L/D of 40:1 and screw diameters from 50 mm to 75 mm. A typical formulation uses 100 phr EVA, 120 phr to 150 phr aluminium trihydroxide, 20 phr to 40 phr magnesium dihydroxide, 3 phr to 5 phr of a maleic anhydride-grafted polyolefin coupling agent, and 0.3 phr to 0.6 phr of a phenolic antioxidant. Barrel temperature is held between 140°C and 170°C; screw speed is set from 250 rpm to 400 rpm; water-strand pelletizing is used to prevent pellet agglomeration. The melt temperature must not exceed 175°C because aluminium trihydroxide begins to release water above 180°C to 190°C. Cable extrusion uses a 90 mm single-screw extruder with an L/D of 25:1, barrel temperatures from 130°C to 165°C, head pressures of 100 bar to 250 bar, and a compression screw with a mixing torpedo. Finished jacket tensile strength is targeted at ≥9 MPa and elongation at break ≥125% after aging 7 d at 100°C per IEC 60811-501. Flame spread is assessed by IEC 60332-1-2; acidity and conductivity are evaluated by IEC 60754-2, with pH above 4.3 and conductivity below 10 µS/mm. Halogen acid gas content is kept below 0.5% according to IEC 60754-1. The formulation is incompatible with halogenated flame retardants and amine-based additives, which antagonize the acid-scavenging function of ATH. Terminal products include control cable sheaths, building wire jackets, and outdoor data-cable outer jackets.

Extruded sheet gauge uniformity and melt strength requirements

For extruded sheet between 0.5 mm and 3.0 mm, SANREN EVA 12/0.5 is run on a single-screw extruder with a barrier screw and an L/D of 30:1, using a flat die with adjustable lip gap from 0.8 mm to 3.2 mm and a three-roll polishing stack set at 65°C to 85°C. The low melt index of 0.5 g/10 min increases drawdown stability and reduces edge-neck-in at sheet widths above 1200 mm. Barrel temperatures are profiled from 150°C to 175°C, with die temperature at 180°C to 190°C; melt temperature should remain below 200°C. Resin must be pre-dried at 70°C to 80°C for 4 h when storage humidity exceeds 60% RH; otherwise pinholes occur in thin sheet. Output rates below 180 kg/h on a 75 mm extruder are typical for this low-MI grade. Sheet gauge variation is controlled within ±5% by adjusting roll gap and puller speed. When blocking is problematic, a coextruded LDPE cap layer at 5% to 10% of total sheet thickness is specified. The sheet is subsequently thermoformed into industrial trays, automotive door-panel water barriers, and chemical-resistant inner liners. Thermoforming conditions require preheating the sheet to 100°C to 120°C before vacuum forming at 0.6 bar to 0.9 bar. The thermoformed parts are not intended for continuous contact with ketones, esters, or aromatic hydrocarbons. Compliance for non-food industrial use falls under the manufacturer's REACH registration; food-contact sheet must be separately certified according to EU No 10/2011 and FDA 21 CFR 177.1350.