UBE POLYETHYLENE V319 Ethylene Vinyl Acetate Copolymer (UBE)

UBE Polyethylene V319 is a thermoplastic ethylene-vinyl acetate copolymer supplied by Ube Industries, Ltd. under the UBE Polyethylene trade designation. The product is an EVA copolymer in which vinyl acetate comonomer is distributed along the polyethylene backbone, reducing crystallinity and introducing polar acetate side groups. The suffix V319 is a manufacturer product-series identifier rather than a direct specification; the certificate of analysis and purchase specification remain the controlling documents for vinyl acetate content, melt mass-flow rate, density, and additive loading. For process engineers, V319 is positioned in the intermediate vinyl acetate band where flexibility, impact resistance, filler wetting, and thermal processability are balanced. Published data for UBE Polyethylene V319 as an isolated grade are limited, so the technical statements below rely on standard EVA structure-property relationships for the same comonomer band and on standard test methods, not on fabricated lot-specific values.

At incoming-goods inspection, V319 should be characterized against the supplier’s specification using standard polyolefin methods. The density is normally determined by ISO 1183-1:2022 or ASTM D1505, and the melt mass-flow rate by ISO 1133-1:2022 at 190 °C and 2.16 kg. The vinyl acetate content is commonly verified by infrared spectroscopy or saponification, with the method stated on the certificate of analysis. For EVA grades near 19 wt% vinyl acetate, density is typically close to 0.94 g/cm³, while LDPE with comparable melt flow is usually in the range 0.915–0.925 g/cm³. The higher density of EVA is due to the oxygen-bearing acetate group rather than increased crystallinity.

What Does the V319 Designation Signify in UBE’s EVA Portfolio?

The alphanumeric designation V319 identifies a grade within UBE’s EVA product family. Because UBE’s technical literature does not make all V-series datasheets public, the numerical suffix should not be interpreted as an exact vinyl acetate percentage without confirmation; however, the grade naming convention is consistent with an EVA in the approximate 19 wt% vinyl acetate band. The distinction matters because vinyl acetate content affects the melting temperature, crystallinity, solubility parameter, polarity, and degradation chemistry. In EVA with approximately 19 wt% comonomer, differential scanning calorimetry by ISO 11357-3:2018 typically shows a melting peak in the 85–90 °C range at a heating rate of 10 K/min. By comparison, LDPE homopolymer typically exhibits a melting peak from 105–115 °C under the same method. The melting point suppression is accompanied by a reduction in crystallinity from roughly 40–55% in LDPE to about 20–30% in EVA with 19 wt% vinyl acetate.

The melt flow rate of V319, measured under ISO 1133-1:2022 at 190 °C with 2.16 kg load, is reported on the lot certificate. Published data for this specific UBE grade is limited; processors should use the certificate value because a deviation of 0.5 g/10 min can shift injection pressure, surface finish, and foam cell uniformity. EVA grades in this application band are often formulated with melt flow rates between 1.5 g/10 min and 3.0 g/10 min, but this is an indicative range and not a V319 specification. The exact melt flow rate should be confirmed before mold design and screw selection.

For melt processing, V319 should be introduced into a single-screw extruder or a co-rotating twin-screw extruder with the initial barrel zones set at 120–140 °C, progressing to 170–190 °C. This profile prevents premature melting in the feed zone and limits blocked feed throat events. High-shear mixing elements should be minimized for unfilled V319. If a co-rotating extruder with 40:1 L/D is used, screw speeds above 200 min⁻¹ can produce excessive shear heating and push melt temperature above 220 °C unless intensive cooling is applied to the barrel. In blown film or sheet extrusion, the melt temperature is normally maintained between 180 °C and 200 °C, while the die is kept at 190–210 °C to avoid melt fracture and to control draw resonance. These are process starting points, not fixed formulations, and must be adjusted to the actual melt flow rate of the lot.

In film and sheet operations, screw design should provide a moderate compression ratio of 2.5:1 to 3.5:1 and a barrel profile from 120 °C to 190 °C. A Maddock mixing section may be used, but it should not generate melt temperature above 200 °C. The die gap for sheet extrusion is typically set from 0.8 mm to 2.0 mm, depending on final thickness. Draw-down is reduced compared with LDPE because EVA has lower melt strength than LDPE at equivalent molecular weight. For foam sheet, a barrier screw with a barrier clearance of 0.25–0.50 mm improves homogeneity and reduces the incidence of unmelts.

Melt Index, Comonomer Content, and the Functional Distance from LDPE

The principal difference between V319 and LDPE is the acetate side group. This group reduces interchain crystallinity, increases polarity, and improves adhesion to polar substrates and fillers. It also narrows the thermal processing window. LDPE homopolymer can often withstand short-term melt temperatures in the 230–250 °C range with modest degradation, whereas EVA near 19 wt% vinyl acetate begins to undergo measurable deacetylation near 220 °C, depending on residence time and stabilizer package. The tensile modulus reflects this difference: LDPE typically ranges from 100 MPa to 300 MPa under ISO 527-2:2012 at 23 °C, while EVA at 19 wt% vinyl acetate is generally reported between 30 MPa and 80 MPa. This lower modulus is accompanied by higher elongation and improved low-temperature impact resistance, which is relevant for semi-flexible molded articles.

Polarity also affects moisture adsorption and additive solubility. Compared with LDPE, V319 accepts higher loadings of calcium carbonate or other fillers without complete loss of elongation because the polar acetate groups wet filler surfaces. On the other hand, moisture adsorption is higher than LDPE; pre-drying at 60–80 °C for 2–4 h is recommended when the resin has been stored at relative humidity above 60%. Without pre-drying, surface defects and bubbles may appear in extruded sheet or injection molded parts. The pre-dryer dew point should be −30 °C or lower.

The intermediate values in Table 1 explain the functional behavior of V319. It retains enough crystallinity to resist blocking and to maintain melt strength during foam expansion, but the crystallinity is low enough to reduce the brittle low-temperature failure mode associated with LDPE. In applications where a high-VA grade is too soft, tacky, or thermally sensitive, V319 offers a processor lower tack and a higher heat deflection temperature.

If V319 Is Selected for Crosslinked Foam Extrusion

Crosslinked EVA foam processing with V319 requires matching the decomposition kinetics of the blowing agent and peroxide initiator to the melting and rheological profile of the resin. Azodicarbonamide is commonly added at 0.5–2.5 phr with dicumyl peroxide at 0.5–1.5 phr for compounds in this vinyl acetate range, but the exact formulation depends on desired foam density and gel fraction. Dicumyl peroxide has a half-life of 1 min at approximately 171 °C and 6 min at approximately 141 °C. Therefore, the compounding stage is maintained below 110–120 °C to prevent premature peroxide decomposition. The melt strength of V319 is higher than that of EVA grades in the 28–33 wt% vinyl acetate range but lower than that of LDPE or lower-VA EVA. During expansion, this intermediate melt strength requires careful control of gas pressure and crosslink density. If the mold opens too early or the blowing agent decomposes before adequate crosslinks form, cell collapse or gross foam anisotropy can occur.

In injection molding of V319, the mold temperature can often be set at 20–40 °C because the lower crystallinity reduces shrinkage-driven warpage. However, ejection can become the rate-limiting step if the part design includes deep ribs or textured surfaces. The melt temperature during injection should not exceed 230 °C, and the total barrel residence time above 220 °C should be held below 15 min to limit acetic acid generation. Volatile acetic acid can cause surface splay, and repeated exposure can corrode unprotected tool steel; chrome plating or stainless steel components are recommended for long production runs.

The Deacetylation Limit Controls the Upper Processing Window

The limiting degradation mechanism for V319 is deacetylation of the vinyl acetate segments. Thermogravimetric analysis of EVA near 19 wt% vinyl acetate performed under ISO 11358-1:2022 at 10 K/min in nitrogen typically shows the first mass-loss stage starting at approximately 220 °C and accelerating above 250 °C. The released acetic acid can accelerate further hydrolysis and generate gel particles. Consequently, the melt temperature in any processing step should be kept below 220 °C, with residence time minimized. Storage near high humidity, acidic additives, or halogenated flame retardants can accelerate deacetylation. Strongly basic additives or amine-containing masterbatches should be avoided because they can catalyze ester hydrolysis and produce undesired chain branching. If V319 is exposed to relative humidity above 60%, it should be dried at 60–80 °C for 2–4 h to a dew point of −30 °C or lower before extrusion or molding.

Differentiating V319 from Higher-VA and Lower-VA Grades

A lower vinyl acetate EVA grade in the 12–15 wt% range retains more polyethylene-like crystallinity, higher melting point, higher modulus, and better chemical resistance, but it is less flexible and has lower filler acceptance. A higher vinyl acetate EVA in the 25–28 wt% range has lower hardness, better transparency, and stronger adhesion to polar substrates, but it is more susceptible to blocking, has lower melt strength, and may not be suitable for articles requiring dimensional stability at service temperatures above 40 °C. V319 sits between these two bands. It provides sufficient polarity for good filler wetting and adhesion, while retaining enough melt strength and thermal resistance for continuous extrusion and semi-flexible injection molding. This intermediate position also affects the thermal expansion of the finished part; higher-VA grades show a more elastomeric response, while lower-VA grades behave more like flexible polyethylene.

In practice, the choice between V319 and an adjacent UBE EVA grade should be based on a comparison of melt flow rate, vinyl acetate content, flexural modulus, and Vicat softening temperature. The Vicat softening temperature is measured by ISO 306 and is useful for assessing the upper service temperature of the molded part. For EVA in the 19 wt% vinyl acetate band, the Vicat softening temperature is generally below that of LDPE but above that of high-VA EVA. The exact value must be taken from the supplier’s datasheet because additive and molecular weight distributions shift the heat-deformation response.

Incoming-goods laboratories evaluating V319 typically build a test matrix that includes melt flow, density, vinyl acetate content, and thermal behavior. The matrix should also link each measurement to the applicable standard and identify whether a routine lot-release result is required or only a change-control result. Table 2 lists the standard references most relevant to V319 qualification and process control.

For global applications, the resin should be covered by the supplier’s REACH and RoHS compliance statements. Food-contact status is formulation-specific and should not be assumed without a written letter from the manufacturer citing the relevant food-contact regulation, such as EU Regulation 10/2011 or U.S. FDA 21 CFR 177.1350 for ethylene-vinyl acetate copolymers. The processor is responsible for verifying the intended use and migration limits because the final compound may contain additives that change the regulatory status.

In production-scale evaluations, V319 has been processed on conventional polyolefin extruders with 40:1 L/D and on injection molding machines with moderate clamp force. The observed failure modes include feed-throat bridging when wet resin or high fines are present, surface splay from acetic acid generation at excessive melt temperature, and poor cell uniformity in foam when gas pressure is released before sufficient crosslinking. These failure modes are consistent with EVA grades in this comonomer band and are controlled by pre-drying, a melt temperature ceiling of 220 °C, and flow path geometry that minimizes stagnation points.