LG EVA 28150 EVA resina de copolímero,28% VA,150 MI,Grado adesivo de fusão quente

LG EVA 28150 is an ethylene-vinyl acetate copolymer resin designated as a hot-melt adhesive feedstock. The typical vinyl acetate content is 28% by mass, and the melt mass-flow rate is 150 g/10 min measured at 190 °C under 2.16 kg in accordance with ISO 1133-1:2022 or ASTM D1238-23. The supplied form is normally translucent pellets with a density of 0.95 g/cm³ at 23 °C and a residual moisture level below 0.1% by mass. Application areas include case and carton sealing, food packaging, bookbinding, profile wrapping, and general assembly adhesives where low melt viscosity, rapid wet-out, and adequate adhesion to polar substrates are required. The grade is not a structural adhesive raw material; it is intended for thermoplastic hot-melt formulations in which the copolymer is compounded with tackifiers, waxes, and stabilizers.

What Is the Technical Significance of 28% VA and 150 MI in Hot-Melt Formulations?

Vinyl acetate content is the primary polarity and crystallinity regulator in EVA copolymers. At 28% VA, the polyethylene segments retain limited crystallinity; differential scanning calorimetry on this VA class typically shows a broad endothermic event in the 60–75 °C range. The reduction in crystallite thickness lowers the melting point, increases optical clarity, and improves adhesion to cellulose, aluminium, polyester-coated board, and poly(vinyl chloride) relative to 18% VA grades. The polar vinyl acetate units also increase compatibility with rosin ester tackifiers, aromatic hydrocarbon resins, and polar adhesion promoters.

The melt index of 150 g/10 min describes short-chain architecture with lower entanglement density. Under low shear, the resin exhibits a relatively low complex viscosity; in a formulated hot-melt, this contributes to application viscosities commonly within 500–1500 mPa·s at 180 °C, depending on tackifier level. However, low chain entanglement also reduces cohesive strength, tensile elongation at break, and creep resistance compared with grades having melt indices below 25 g/10 min. The resin therefore functions best when the adhesive formulation contains a tackifier system that raises green strength without forcing melt temperature beyond the thermal stability limit.

At the molecular level, VA content also affects degradation chemistry. The ester side groups are thermally labile above 200 °C; acetic acid evolution can accelerate polymer degradation and corrode downstream metal surfaces. For this reason, melt temperatures should be maintained below 180 °C, and residence time in melters should be as short as possible. Nitrogen blanketing of melt tanks and addition of phosphite antioxidant at 0.2–0.5 wt% are common practices.

Processing Windows, Equipment Parameters, and Thermal Boundaries for LG EVA 28150

Bulk handling of LG EVA 28150 normally requires standard pellet conveying and hopper systems. The high melt index of the resin does not require special drying under normal storage conditions. Storage is recommended below 35 °C and below 60% relative humidity to avoid surface moisture and pellet blocking. If pellets are exposed to humid ambient conditions and gloss or bubble formation occurs in the melt, desiccant drying at 50–60 °C for 2–4 h is sufficient. Air temperatures above 80 °C may cause pellet cluster formation in the hopper and should be avoided.

Compounding is typically performed on a co-rotating twin-screw extruder with an L/D ratio of 40:1 to 52:1. Barrel settings generally range from 120 °C in the feed zone to 160 °C near the die, with die head temperature controlled at 140–170 °C. The low melt viscosity reduces motor amperage demand relative to low-MI grades, which is advantageous on torque-limited production lines. Screw speeds of 200–300 rpm are usually sufficient for dispersion; higher speeds may generate local frictional heat and must be balanced with adequate cooling in the extruder barrel zones. Vacuum venting is commonly used to remove trace moisture and low-molecular-weight volatile by-products.

In hot-melt application equipment, the resin is processed in bulk melters, tank melters, or drum melters fitted with gear pumps. The working temperature is generally 160–180 °C. At these temperatures, the final formulated adhesive may be applied by roller, slot-die, or spiral-spray systems. Spiral-spray application with narrow orifice nozzles often requires viscosity reduction to approximately 300–800 mPa·s at 180 °C, while roller and slot-die systems accept higher viscosity ranges up to 1500 mPa·s. The high melt index of LG EVA 28150 supports low-temperature application and short open time; however, set speed and heat resistance must be adjusted with wax and tackifier selection rather than by relying only on the copolymer.

Thermal processing above 200 °C should be avoided. Prolonged exposure at elevated temperature can produce acetic acid, increase color development, form gel particles, and reduce bond strength. Local exhaust ventilation is required at melters and coating heads. Equipment should not use copper or brass components in prolonged contact with molten EVA, because copper ions may accelerate oxidative degradation. Stainless steel, aluminium, or nickel-plated surfaces are preferred.

When purging after processing, low-melt-index polyethylene or a commercial EVA purge grade is recommended. The resin should not be melted in equipment containing residues of chlorinated polymers or strong acidic contaminants. No intentional addition of amine-based additives is recommended, because some amines can accelerate ester degradation and color formation in EVA hot-melt systems.

When LG EVA 28150 Is Compounded with Tackifiers and Waxes

Hot-melt formulations based on LG EVA 28150 generally use 30–50 wt% polymer, 40–60 wt% tackifying resin, 5–20 wt% wax or diluent, and 0.3–1.0 wt% antioxidant. The final ratios depend on open time, viscosity, adhesion, and heat resistance requirements. Rosin ester tackifiers and aromatic modified hydrocarbon resins are usually compatible with this VA level. Aliphatic C5 resins may show limited compatibility and can produce phase separation if used at high loadings. A preliminary compatibility check by heated-stage microscopy or differential scanning calorimetry is advised before scale-up.

Wax selection has a strong effect on set speed and cohesive strength. Fischer-Tropsch waxes with melting points of 80–105 °C are commonly used because they reduce melt viscosity and shorten open time. Microcrystalline waxes improve low-temperature flexibility but may reduce heat resistance. Excessive wax levels, particularly above 20 wt%, can produce brittle bonds, poor adhesion to coated board, and reduced peel strength. The high VA content of LG EVA 28150 generally permits good wet-out on low surface energy coatings after corona or primer treatment, but the resin alone does not guarantee adhesion on fluorine-modified or silicone-treated substrates.

Mineral fillers such as calcium carbonate can be incorporated up to approximately 20 wt% for cost reduction. Filler loading raises high-shear viscosity, reduces tack, and may require higher application temperature. It is usually limited in high-speed packaging adhesives where nozzle clogging and pump wear are critical. For clean hot-melt lines, filler particle size should be below 10 µm and moisture content below 0.2%.

Bond performance is evaluated using T-peel adhesion according to ASTM D1876-08, lap shear adhesion according to ASTM D1002-10, and heat-fail temperature according to ASTM D4498-07. Melt viscosity is measured by ASTM D3236-15 or ISO 2555:2018 using a Brookfield thermosel geometry at 180 °C. On coated board and paperboard, LG EVA 28150 has been used in case-sealing and bookbinding lines where fast fiber-tearing bond formation is required at low coating weights. The resin is also applicable to profile wrapping edge-bonding where adhesion to PVC edge banding or impregnated paper is needed.

Regulatory support for adhesive formulators is typically based on FDA 21 CFR §175.105 for the finished adhesive and, where applicable, §177.1350 for ethylene-vinyl acetate copolymers as a component of food-contact articles. REACH registration status and RoHS Directive 2011/65/EU Annex II restrictions should be confirmed with the supplier’s safety data sheet. Published data for this specific product relative to site-specific environmental certifications may be limited; adequacy for food contact must be validated on the finished article under end-use conditions.

In comparison with a conventional EVA having 18% VA and a similar 150 g/10 min melt index, LG EVA 28150 typically lowers the application temperature, increases adhesion to coated paper and polar plastics, and improves low-temperature flexibility. However, it also reduces resistance to nonpolar oils and may increase hot-melt stringing. In comparison with a 28% VA grade having an MI below 25 g/10 min, LG EVA 28150 reduces melt viscosity and improves penetration into porous substrates, but it gives lower cohesive strength and lower high-temperature creep resistance. In creep-sensitive assembly applications, a small addition of a higher-molecular-weight EVA or styrenic block copolymer can partially restore cohesive strength, although this may reduce clarity and specific adhesion.

On high-speed carton sealing lines, the low melt viscosity of LG EVA 28150 enables thin bond lines and rapid substrate penetration, but the final formulation must be adjusted for set speed because the low-molecular-weight polymer alone may remain soft or sticky after compression belts. In bookbinding side-glue applications, the resin can provide acceptable adhesion to uncoated paper and thin coated cover stock, while spine glue formulations may require combination with higher-viscosity EVA to maintain binding strength during repeated opening cycles. In profile wrapping, the resin is generally used in primer-free systems only when the substrate and edge material have been surface-activated; otherwise, a diluted primer or an atmospheric plasma treatment is required.

Thermal-oxidative stability during storage and application should be confirmed by oven aging of the formulated adhesive at 150 °C for 24 h, followed by color and viscosity measurement. A color increase above 3 Gardner units or a viscosity drift above 10% from initial value indicates insufficient stabilizer loading or unacceptable residence time in the melter. These operational boundaries are specific to the final formulation and cannot be assigned to the resin alone. The resin has a limited operating window in high-temperature assembly adhesives; it is not a substitute for polyamide or polyurethane hot-melt grades in structural or load-bearing applications where service temperatures exceed 80 °C.