Carbon Printers EPX 82 Epoxy, Dry is a rigid epoxy photopolymer supplied in low-moisture condition for digital light synthesis platforms operating at 405 nm. The model designation EPX 82 identifies a high-modulus epoxy system; the suffix “Dry” refers to the controlled residual moisture content of the liquid resin, not a powder or solid format. The material is supplied in sealed, light-opaque cartridges for direct integration with Carbon DLS printers and is intended for layerwise photopolymerization through an oxygen-inhibited dead zone.

The uncured resin is classified under Regulation (EC) No 1272/2008 as a skin and respiratory sensitizer; handling must follow the safety data sheet and the printer manufacturer’s ventilation requirements. RoHS status is assessed under Directive 2011/65/EU, Annex II, as amended by Commission Delegated Directive (EU) 2015/863. Lot-specific certificates report viscosity, residual moisture, and photoinitiator activity. Published data for this specific configuration is limited outside the manufacturer’s material datasheet and application notes.

Does Dry-Grade EPX 82 Require Modified Recoat and Storage Conditions?

The recoat and storage boundary of the Dry grade is narrower than that of standard epoxy photopolymers. Vat temperature is maintained at 35 °C to 38 °C, and the recoat blade is set to 35 mm/s for 100 μm layers. At relative humidity above 60%, an opened cartridge should be returned to a dry-air cabinet or consumed within 8 h; otherwise moisture absorption increases equilibrium viscosity and raises the probability of recoat-related surface defects. The lot release limit for residual water is typically 0.05% by mass as determined by Karl Fischer titration in accordance with ISO 760. When residual moisture exceeds 0.08%, the post-cure conversion curve shifts and heat deflection temperature may fall below the supplier’s lower control limit.

Green parts are rinsed with isopropyl alcohol, dried at 40 °C for 2 h, and post-cured in a forced-air oven ramped at 0.5 °C/min to 120 °C for 2 h. On production-scale DLS cells with vat volumes of 10 L to 12 L, recoat force is the primary process signal for viscosity drift. Excursions above the supplier-listed upper control limit correlate with incomplete layer coalescence and trigger a resin dehydration cycle. Batch-to-batch variation is monitored through in-line near-infrared moisture analysis before cartridge filling.

The dry formulation suppresses void formation during long vat dwell periods. In environments where the vat remains idle for more than 72 h, surface moisture uptake increases the dissolved oxygen concentration and broadens the dead-zone thickness. This can alter first-layer adhesion and produce edge curl in down-facing features. The Dry grade is therefore returned to sealed storage when the printer is offline, and the vat surface is purged with dry nitrogen at 0.5 bar in qualified production cells.

Mechanical property data for dry-post-cured EPX 82 are summarized in Table 1. The values are extracted from supplier-published datasheets and represent production-batch central tendencies; they are not lot-release limits unless stated in the certificate of analysis.

These values assume thermal post-cure at the supplier-specified temperature. If post-cure is interrupted or humidity exceeds the dry-storage boundary, flexural modulus can shift by more than 10% due to plasticization by absorbed water and incomplete epoxide conversion. Published data for this specific configuration is limited for high-humidity aging beyond 500 h. The dry-grade formulation exhibits a modulus-to-density ratio that places it between rigid polyurethane and cyanate ester systems.

When EPX 82 Epoxy, Dry Replaces Glass-Filled Nylon or Acrylonitrile Butadiene Styrene in Fixture Work

Compared with machined glass-filled nylon, EPX 82 Dry removes the hygroscopic dimensional change associated with polyamide conditioning. Retained feature resolution is typically 0.5 mm for vented geometries with 100 μm layers. The material is used in form-, fit-, and function jigs where repetitive clamp force exceeds the compressive creep limit of acrylonitrile butadiene styrene. In low-run injection molding, conformal cooling inserts printed in EPX 82 are operated at mold temperatures of 80 °C to 110 °C when ejection force is distributed through steel or aluminum backing plates.

Compared with Carbon’s EPU 40 elastomeric photopolymer, EPX 82 exhibits higher flexural modulus and lower elongation at break, making it unsuitable for impact-absorbing or snap-fit designs requiring more than 10% strain. Compared with CE 221 cyanate ester, EPX 82 has lower continuous-use temperature and shorter post-cure time. Flexural fatigue testing per ASTM D7774 is recommended for snap-fit designs; cyclic loading above 10,000 cycles may initiate microcracks at stress concentrations.

Table 2 provides comparative property indicators against adjacent Carbon resin grades. The data are supplier-reported and are not to be used as design allowables.

The property spread indicates that EPX 82 is positioned for rigid tooling and moderately elevated temperature service. Selection for dynamic or impact-loading applications should be supported by component-level testing because the notched Izod value is sensitive to layer orientation and post-cure uniformity.

Solvent Resistance and Continuous Service Limits

Immersion testing per ASTM D543 is recommended before specifying EPX 82 in chemical-handling fixtures. In ketone solvents such as methyl ethyl ketone, swelling of cured EPX 82 can exceed 8% after 24 h at 23 °C. Strong alkaline solutions above pH 10 reduce surface hardness and should be avoided for continuous contact. The material is not recommended for wet steam service above 80 °C without stress relief.

Aminofunctional silane coupling agents and amine-based antistatic concentrates are incompatible with vat processing of EPX 82 because they initiate premature epoxy crosslinking at machine operating temperature. Mixing of any solvent or flexibilizer is not specified and voids the supplier’s lot-performance statement. No statement of food-contact suitability under 21 CFR 177 is made without separate validation under the final printed and post-cured condition.

Storage life in unopened cartridges is stated by the manufacturer as 12 months at 20 °C to 25 °C in the original light-blocked packaging. Cartridges exposed to direct sunlight or heated storage above 30 °C should be quarantined and tested for viscosity and photoinitiator activity before use. The dried resin should not be returned to the main vat after exothermic shear stirring without recertification because the rheological profile may fall outside the printer’s recoating window.