LG EVA 19150 Copolímero de acetato de vinilo de etileno

LG EVA 19150 is an ethylene-vinyl acetate random copolymer produced by LG Chem under CAS registry 24937-78-8, with a nominal vinyl acetate content of 19 wt% and a melt index of 15 g/10 min when determined under ASTM D1238 at 190 °C with a 2.16 kg load. The product is supplied as translucent pellets with a density of approximately 0.940 g/cm³ by ASTM D792, a Shore A hardness of approximately 92 under ISO 868, a tensile strength in the range of 13–14 MPa under ASTM D638, and a peak melting temperature near 84 °C under ISO 11357-3. These values are nominal characterizations rather than batch specification limits. The copolymer occupies a mid-range position in the producer’s EVA portfolio: the 19 wt% acetate content suppresses enough polyethylene crystallinity to improve flexibility and stress-crack resistance, while retaining greater stiffness and surface hardness than grades at 28 wt% vinyl acetate. The grade is used primarily in injection moulding, foam expansion, and compounding, where the combination of mid-range comonomer content and a moderate melt index allows fast cavity filling without the extreme melt temperature sensitivity seen in higher-vinyl-acetate materials.

Does the 19 wt% Vinyl Acetate Content Alter the Property Gradient Relative to Lower-VA and Higher-VA EVA Grades?

The position of LG EVA 19150 in the vinyl acetate gradient is defined by crystallinity, polarity, and stiffening response. With 19 wt% acetate, the polymer retains a crystalline melting peak near 84 °C, whereas a 15 wt% vinyl acetate grade of similar melt index retains a higher melting point and harder surface. The increased acetate content in 19150 reduces long crystallizable ethylene sequences, lowering density and flexural modulus, while increasing the polar surface energy available for adhesion to polar substrates such as polyurethane injection intermediates and polar fillers. Compared with a 28 wt% vinyl acetate grade, 19150 has higher hardness, higher tensile strength, and lower surface tack, but less compatibility with high loadings of polar processing aids and lower ultimate low-temperature flexibility. The difference between these grades is not linear; the largest property changes occur as vinyl acetate content passes from about 18 wt% to 20 wt% because crystallite size distributions collapse through that range. For 19150, continuous service under load above 70 °C is not recommended unless the part is crosslinked or supported, because creep recovery deteriorates as the ambient temperature approaches the crystalline melting range. Published comparative data for direct tensile-property transitions across the exact LG Chem EVA portfolio are limited to producer technical bulletins; batch certification values should be used for specification limits.

On conventional hydraulic or toggle injection moulding machines with screw L/D ratios of 20:1 to 25:1 and compression ratios of 2.5:1 to 3.5:1, LG EVA 19150 is processed with rear barrel zones from 160 °C to 180 °C, center zones from 180 °C to 190 °C, and a nozzle temperature of 180 °C to 200 °C. Mould temperature is typically held at 20 °C to 35 °C. The melt index of 15 g/10 min permits injection velocities of 60 mm/s to 120 mm/s for wall sections below 4 mm; higher velocities can create jetting when the gate land length is less than 1.5 mm, while lower velocities cause visible flow marks in multi-cavity tools. Shot capacity should remain below 65% of the barrel inventory to prevent excessive residence time. For melt pressure at transfer between 60 bar and 100 bar, projected cavity area is multiplied by an estimated cavity pressure of 30 MPa to 45 MPa to calculate clamp force; most thin-wall tools with shot weights below 500 g operate on machines from 80 to 150 tonnes clamp force. If pellets have been cold-stored or exposed to relative humidity above 70%, drying at 60 °C to 70 °C for 2 h in a dehumidified hopper dryer is applied. Melt residence time above 200 °C should be limited to 15 min; prolonged high-temperature residence accelerates deacetylation and releases acetic acid, which corrodes unprotected mould steel and contributes to splay.

Rheological Response and Filler Dispersion on Co-Rotating Twin-Screw Lines

Compounding of LG EVA 19150 with calcium carbonate, talc, or colour concentrates is performed on co-rotating twin-screw extruders with L/D ratios of 40:1 or greater. The screw configuration typically includes a solids-conveying section, two high-shear kneading zones separated by a vent, and a low-shear discharge zone. In a filler-masterbatch formulation with 40 wt% calcium carbonate, barrel temperatures are set between 130 °C and 170 °C, and screw speed is maintained at 250 rpm to 350 rpm to keep melt temperature below 190 °C at the die. Under these conditions, the melt viscosity of 19150 is sufficiently low to wet filler surfaces but high enough to prevent excessive pressure generation in the mixing zones. Dispersion quality is monitored by pressure-rise testing through a 20 μm screen pack rather than by visual pellet inspection alone. Excessive shearing caused by severe back-conveying elements or screw speeds above 400 rpm can initiate local deacetylation even when the barrel setpoint is moderate; therefore, kneading-block angles are limited and melt-temperature probes are positioned at the exit of each mixing zone. Batch-to-batch melt index variation is generally narrow enough to maintain stable die pressure, but filler moisture changes often have a larger effect on surface roughness than resin lot variation.

For chemically blown injection moulding of low-density EVA foams, formulations based on LG EVA 19150 typically combine azodicarbonamide blowing agent with dicumyl peroxide crosslinking initiator. The processing conflict is defined by the decomposition kinetics of the two additives: azodicarbonamide gas liberation accelerates near 200 °C to 210 °C, whereas dicumyl peroxide has a half-life of approximately 1 min at 170 °C to 180 °C. Barrel zone settings for foam expansion are therefore held lower than in compact injection moulding, commonly 90 °C to 120 °C in the rear zones and 120 °C to 150 °C in the front zones, with the nozzle at 150 °C to 170 °C. Mould temperature is set between 20 °C and 45 °C. In this window, the 19 wt% vinyl acetate content supplies melt strength for cell nucleation, while the 15 g/10 min melt index keeps cavity-fill pressure low in multi-cavity sole tools. Blowing agent loadings of 0.5 phr to 1.5 phr and peroxide loadings of 0.4 phr to 0.8 phr are typical starting points, but final formulations depend on mould geometry and desired foam density. Compared with a 28 wt% vinyl acetate grade, 19150 produces a slightly firmer foam with higher compression set and reduced surface tack. Compared with a nominal 4 g/10 min flow grade, 19150 permits thinner walls and shorter fill times but requires more precise nozzle shutoff to limit drool after plastication.

When 19150 Replaces LDPE in Thin-Wall Sealing Layers, What Changes at the Die and in the Seal?

The replacement of low-density polyethylene with LG EVA 19150 in thin-wall sealing layers shifts the sealing-temperature window downward and increases adhesion to polar substrates. LDPE typically initiates heat-seal formation at temperatures above 100 °C, whereas the vinyl acetate groups in 19150 allow seal initiation to occur at lower temperatures because chain mobility and polar wetting increase. The reduction in crystalline melting point also means that process control at the die must compensate for lower melt strength: neck-in and draw resonance can be more pronounced on cast-film lines with a chill roll gap below 0.5 mm unless lip lands are reduced or air-knife positioning is adjusted. For thicker extruded profiles, the grade’s 15 g/10 min melt index allows stable output on single-screw extruders with L/D ratios of 24:1 to 30:1, but barrel zone temperatures should be set 20 °C to 30 °C lower than typical LDPE profiles to prevent melt temperature overshoot. The resulting sealant or gasket layer has lower modulus and greater flexibility at low temperature, but the operational boundary is heat resistance: continuous exposure above 70 °C without crosslinking can cause deformation and seal failure earlier than LDPE in the same part design.

In hot-melt adhesive compounding, LG EVA 19150 is used as a viscosity modifier and adhesion promoter in formulations containing tackifying resins, waxes, and antioxidants. The 19 wt% vinyl acetate content provides polar interaction with metals, coated papers, and polyvinyl chloride, while the 15 g/10 min melt index allows lower application viscosity than low-flow EVA grades. Mixing is carried out in a temperature-controlled sigma-blade or vertical intensive mixer at 140 °C to 170 °C; the resin pellets are added after the tackifier and oil have melted to prevent localized overheating. Thermal stabilizers are required to limit deacetylation during prolonged pot hold times above 160 °C. Compared with an EVA grade with a melt index of 150 g/10 min, 19150 yields higher cohesive strength and longer open time, but increases application viscosity; compared with a 28 wt% vinyl acetate grade, it yields lower adhesion to highly polar surfaces such as aluminium foil but better resistance to creep in warm environments.

Relative to ethylene-ethyl acrylate and ethylene-butyl acrylate copolymers of similar comonomer content, EVA 19150 offers higher stiffness at ambient temperature and greater scuff resistance, but lower thermal stability because the acetate group undergoes deacetylation at elevated processing temperatures. Ethylene-butyl acrylate copolymers remain more flexible at low temperature and are often selected when low-temperature impact below -40 °C is required. The acrylic and butyl acrylate comonomers do not release acetic acid upon degradation, so they are favoured when extended high-temperature processing or hot-water contact is expected. These differences are relevant in sealant and footwear applications where melt stability and mould corrosion are more critical than initial material cost.

Regulatory evaluation of LG EVA 19150 depends on the finished article and jurisdiction. Ethylene-vinyl acetate copolymers intended for food-contact applications may be evaluated under FDA 21 CFR 177.1350, provided the final article meets the specified extractive limitations for the intended food type and use temperature. Because additive packages and processing aids affect final extractives, compliance cannot be assumed from resin composition alone; a finished-article extraction study under the relevant conditions is required. Under European Union requirements, the resin supplier’s safety data sheet and REACH registration status should be confirmed for the specific commercial lot. RoHS compliance is generally assessed for homogeneous materials under Directive 2011/65/EU; EVA homopolymer does not inherently contain lead, mercury, cadmium, hexavalent chromium, PBB, or PBDE above common restriction limits, but filler or colour masterbatches must be verified separately. Process safety boundaries include avoiding melt temperatures above 220 °C for extended periods and avoiding contamination with strong acids or oxidizing agents that accelerate deacetylation. Scrap recovery is technically feasible at up to 20 wt% in compact injection moulding when the reclaimed material is dry and free of degraded material, but higher addition levels can increase viscosity variation and surface defect rates. This product is not designed for long-term implantable medical use or for continuous load-bearing service above 70 °C without crosslinking.