Product designation 64# Fully-Refined Paraffin Wax identifies a hydrofinished petroleum wax produced from vacuum distillate fractions by solvent dewaxing, deoiling, and catalytic hydrotreating. The designation 64# corresponds to a nominal melting point of 64 °C determined under the cooling curve method of GB/T 2539 or ASTM D87. Fully refined status is defined analytically rather than descriptively: commercial certificates for this material normally report residual oil content at or below 0.5 wt% by ASTM D721 or GB/T 3554, Saybolt colour at +28 minimum by ASTM D156 or GB/T 3555, and odour not above 2 by ASTM D1833 or SH/T 0414. The n-paraffin distribution is concentrated between C20 and C40, with normal paraffin contents of 70–90 % by high-temperature gas chromatography, while branched and cyclic species remain substantially below those of slack wax and microcrystalline wax. The product is supplied as pastilles, slabs, or coarse granules with a solid density of approximately 0.91 g/cm³ at 25 °C. Because oil content is low, surface exudation under compression is reduced; however, the solidified wax is correspondingly harder and less flexible than semi-refined grades, and this trade-off must be managed in films or coatings that undergo creasing at low temperature.

Does Low Oil Content Alter Migration Behaviour in Barrier Coatings?

The oil fraction in petroleum wax is the primary vehicle for low-molecular-weight diffusion into adjacent polymer layers and food simulants under thermal stress. In a fully refined 64# grade, oil content held below 0.5 wt% reduces the concentration of mobile low-viscosity species available at the wax–substrate interface. Migration testing for food-contact packaging is governed in the United States by 21 CFR §178.3710 for petroleum wax permitted in contact with food and in the European Union by Regulation (EU) 10/2011 on plastic materials and articles intended to come into contact with food. The overall migration limit is 10 mg/dm² for many food simulants, but wax-containing coatings require formulation-specific extraction studies because the hydrophobic wax phase responds differently to fatty simulants such as vegetable oil and 95 % ethanol. Published data for this specific configuration is limited; therefore, coated substrates must be validated under the intended time–temperature conditions. The lower oil content of 64# fully-refined wax compared with semi-refined grades reduces visible oil staining on uncoated paper after 24 h storage at 60 °C, but this does not by itself guarantee compliance if coating weight exceeds 12 g/m² or if the substrate lacks a continuous barrier layer. The wax also shows lower fluorescence and lower ultraviolet absorbance than oil-bearing grades, which is relevant in overprint varnishes and white paper coatings.

The needle penetration range reflects the hardness of the solidified wax. Lower penetration values are advantageous for mould release and non-blocking surfaces, but they reduce elongation capacity in flexible laminations. Kinematic viscosity at 100 °C is more useful than the melting point alone for pump and curtain-coating design because the fully refined wax remains in the low-viscosity Newtonian regime; gear pumps, heated filters, and narrow-slot dies require different control settings than polymer melts. Flash point above 230 °C allows handling in closed hot-melt systems up to 180 °C, provided that air ingress and prolonged hold times are controlled.

Molten candle batches formulated with 64# fully-refined paraffin wax are typically blended with 2–5 wt% microcrystalline wax to balance brittleness and shrinkage. This addition increases needle penetration from 12–16 to approximately 18–24 × 0.1 mm under ASTM D1321 and reduces visible cracking in pillar candles formed in water-jacketed moulds. Production-scale continuous moulding lines maintain water-bath temperature at 18–22 °C and adjust cooling water flow to achieve a solidification front velocity of 0.5–1.5 °C/s; above 2 °C/s, radial contraction cracks become detectable after 24 h at 20 °C. Container candle systems using this wax require wick sizing matched to a melt pool diameter of 45–55 mm at 4 h under EN 15493; excessive wick size produces visual sooting under the same test, while undersized wicks leave an unmelted shell that reduces fragrance release. The low oil content also reduces surface tack after the candle is demoulded, which improves automated packaging line throughput but can require higher demoulding force if the mould release coating is insufficient.

During external lubrication of rigid PVC on a twin-screw extruder with L/D 36:1, 64# fully-refined paraffin wax is dosed at 0.3–1.0 phr with calcium stearate and oxidized polyethylene. The wax reduces plate-out and die lip build-up at die temperatures of 180–200 °C; however, addition above 1.2 phr produces haze in transparent profiles because the paraffin is incompatible with the PVC matrix at room temperature, and haze can exceed 15 % under ASTM D1003. Processing torque at 60 rpm typically drops by 5–12 % when the wax is preblended with the dry blend, but the effect is dependent on screw configuration and the stabilizer package.

Processing Window and Rheological Data for Hot Melt Formulations

For EVA-based hot-melt adhesives, 64# fully-refined paraffin wax functions as a low-viscosity diluent and open-time modifier. At 180 °C, the wax phase exhibits a kinematic viscosity of 6.5–8.0 mm²/s by ASTM D445, while a typical ethylene-vinyl acetate copolymer with 28 wt% vinyl acetate and a melt mass-flow rate of 25 g/10 min under ISO 1133-1:2022 contributes higher melt elasticity. The resulting hot-melt viscosity at 180 °C can be adjusted between 800 mPa·s and 2 500 mPa·s by varying wax content from 15 wt% to 30 wt%. On a production-scale twin-screw extruder with L/D 40:1 and barrel zone profile 120/140/160/170/170 °C, the low melt viscosity of the wax-rich phase reduces motor torque but also reduces viscous shear heating, so barrel temperature control becomes the dominant thermal input. Nitrogen blanketing or 100–500 ppm of a hindered phenolic antioxidant is applied when melt temperature exceeds 160 °C because paraffin oxidation increases acid number above 150 °C; acid number should remain below 0.1 mg KOH/g by ASTM D664 to avoid corrosion of downstream die steel. Batch-to-batch variation in normal paraffin concentration, typically 70–85 wt%, shifts open time by 2–5 s in a 120 °C pressure-sensitive adhesive formulation; that variation cannot be eliminated by melt filtration and must be controlled through incoming gas chromatographic screening. The product should not be combined with unsaturated oils or tall oil fatty acid esters at temperatures above 170 °C in air unless a stabilizer package is present, because oxidative breakdown produces aldehydes and acids that increase odour and colour. In low-temperature hot-melt coatings applied at 130–150 °C, the narrow melting range of 64# wax shortens open time relative to microcrystalline wax; this is beneficial for high-speed case sealing but reduces wetting on cold board below 10 °C unless the substrate is preheated.

When 64# Fully-Refined Wax Replaces Semi-Refined Slack Wax in Paper Lamination

The substitution of semi-refined wax with 64# fully-refined paraffin wax changes both melt handling and end-use barrier properties. Curtain-coating and roll-coating lines running at 70–80 °C with a coating pickup of 8–12 g/m² on 40 g/m² kraft paper show lower visible pinholing because the fully refined grade contains fewer polar resins and dark particulates. Water vapour transmission rate, measured by ISO 2528 or ASTM E96 at 23 °C and 50 % RH, is often reduced by 5–15 % relative to semi-refined wax at the same coating weight, but the improvement narrows above 15 g/m² where coating thickness dominates. The harder surface of 64# fully-refined wax also raises blocking resistance in stacked sheets; the onset of blocking is typically 55–60 °C for fully refined wax compared with 50–55 °C for oil-bearing semi-refined grades. However, the lower oil content reduces elongation capacity of the wax layer, so laminates creased or folded below 10 °C may show stress cracking earlier than with microcrystalline-modified systems. A comparative matrix is provided below.

During antiozonant film formation in rubber compounds, 64# fully-refined paraffin wax is loaded at 2–4 phr and migrates to the vulcanizate surface at a rate controlled by the n-paraffin carbon number distribution. The C24–C34 fractions in a 64# grade form a continuous protective film at 25 °C within 24–72 h; ozone protection under ASTM D1149 becomes measurable when the surface film thickness reaches 0.5–1.5 µm. Below that thickness, microcracking is not adequately suppressed in unsaturated elastomers. Wax addition above 4 phr creates a visible white bloom that reduces sidewall gloss and can interfere with adhesion in retreading operations. The fully refined grade contributes less colour to cured EPDM compounds than semi-refined grades and maintains a neutral Saybolt reading in the extrudate. However, the hard paraffin film is less self-healing than microcrystalline wax films, so cyclic strain at 0–50 % elongation may crack the protective layer; a microcrystalline wax modification of 20–40 wt% of the wax system is used when the part is subject to dynamic flexing. Storage of preblended rubber-wax masterbatches above 35 °C can accelerate surface bloom before curing and should be avoided if the masterbatch is not re-dispersed by mixing.