Carbon Printers RPU 130 Rigid Polyurethane is a two-part, dual-cure photopolymer resin formulated for Carbon Digital Light Synthesis (DLS) platforms. The liquid polyurethane precursor is photo-cured layerlessly against an oxygen-permeable membrane and then thermally post-cured in a forced-air oven to complete urethane network formation. Manufacturer-reported representative values for fully cured parts include tensile strength at break of 35 MPa per ASTM D638, flexural modulus of 1.5 GPa per ASTM D790, notched Izod impact of 45 J/m per ASTM D256, and heat deflection temperature at 0.455 MPa of 78 °C per ASTM D648. The measured Shore D hardness is 82 per ASTM D2240. These published figures place RPU 130 in the rigid, impact-resistant segment of the Carbon resin portfolio, with a higher heat threshold and impact tolerance than the standard rigid polyurethane grade, while retaining a layerless DLS surface character and reduced z-plane interface porosity.

Does Dual-Cure Network Development Alter Dimensional Control in RPU 130?

Dual-cure network development in RPU 130 creates a measurable difference between green-state geometry and final post-cured geometry. During UV exposure, acrylate or methacrylate functional groups react to generate a partially crosslinked scaffold, while the thermal post-cure drives remaining isocyanate-hydroxy reactions and promotes microphase separation between hard and soft urethane segments. This sequence causes linear shrinkage after the part leaves the DLS build volume. In production DLS systems, z-axis compensation is typically necessary because the anisotropic release of residual monomer and volumetric relaxation is more pronounced in the z-dimension. Parts with thick sections above 10 mm may exhibit variation in final shrinkage between the outer skin and the thermal center; therefore, oven ramp rate and hold time should be fixed and validated for each build layout. Published data for this specific geometry-dependent shrinkage is limited, but production experience indicates that a capability study with a coordinate measuring machine is required before tolerances tighter than ±0.15 mm are assigned to RPU 130 components.

Support structure design for RPU 130 differs from elastomeric DLS materials because the green part has higher rigidity and lower elongation. Touchpoints should be enlarged on thin vertical ribs, and tapered supports with a contact diameter of 0.5 mm to 0.8 mm reduce cratering during removal. For parts with large flat down-facing surfaces, support density should be increased beyond default settings to prevent separation during lift. Because the resin is more viscous than elastomeric polyurethane grades, peel forces are higher, and support posts below 0.4 mm diameter may stretch or fail before post-cure. These production observations improve dimensional stability and reduce scrap on systems where optical window cleanliness is tightly controlled.

On production DLS equipment with a 75 µm slice interval and 385 nm projection, RPU 130 places higher demand on drainage than lower-durometer polyurethane resins. The liquid precursor has a higher viscosity than elastomeric grades, which affects recoating after each lift cycle and increases the probability of trapped air in recesses below 2 mm diameter. For parts with deep blind pockets, reduced draw speed and extended re-coat dwell are required to avoid starved-layer defects that present as matte down-facing surfaces. Green parts have lower tensile modulus than the fully cured values; therefore, support removal before post-cure should avoid sharp bending loads on thin walls below 1.5 mm. Cutting or sanding before post-cure produces more edge chipping because the urethane network is not yet fully developed. Post-curing in a forced-air oven per the manufacturer-defined schedule raises the part to its published tensile and thermal values. Process behaviour on production DLS systems further indicates that delayed post-cure beyond the manufacturer’s hold time allows green-state creep to alter flatness and datum features, especially on long spans with aspect ratio greater than 10:1.

When RPU 130 Replaces Injection-Molded ABS or Polycarbonate in Low-Volume Functional Prototypes

RPU 130 is applied to snap-fit enclosures, automotive mounting brackets, industrial connector shrouds, and assembly fixtures that experience repeated mechanical loading. In snap-fit arms, the manufacturer-reported elongation at break of 8 % per ASTM D638 should be used as the outer-fiber design limit; this is higher than unfilled rigid epoxy DLS resins but lower than injection-molded polycarbonate, so engagement angles and deflection are reduced accordingly. The notched Izod impact value of 45 J/m per ASTM D256 exceeds that of standard rigid polyurethane but remains below glass-filled polyamide and polycarbonate, meaning that drop-prone housings need corner radii and ribbing rather than relying on material toughness alone. For under-hood brackets, the heat deflection temperature at 0.455 MPa of 78 °C per ASTM D648 permits intermittent exposure but not continuous service above that temperature when the part is under load. Replacing injection-molded ABS is most feasible for volumes where tooling cost dominates, for bracketed geometries with uniform wall thickness near 2 mm to 3 mm, and for assemblies that do not require the surface finish of a textured injection mold. Validation should include falling-weight impact per ASTM D5276 and repeated snap-fit cycling on the production print orientation.

Property Cross-Reference Across Carbon Rigid Resin Grades

The table lists representative manufacturer-reported values for RPU 130 and places them against the broader Carbon rigid resin portfolio by qualitative trade-off. Properties should be re-confirmed on the specific printer platform, build orientation, and lot used for production.

Relative to standard rigid polyurethane, RPU 130 shifts the thermomechanical envelope upward in impact resistance and heat deflection, while remaining a rigid polyurethane. Relative to epoxy DLS grades, RPU 130 offers greater ductility and lower brittle fracture tendency but sacrifices modulus and high-temperature resistance. Relative to cyanate ester DLS resins, RPU 130 cannot match upper service temperature but provides a different balance of impact behaviour and post-cure handling. These trade-offs are material-specific and are not substitutions for application-level testing.

In chemical exposure, RPU 130 behaves as a rigid urethane material. It withstands dilute acids and alkalis at room temperature but softens in prolonged contact with ketones, chlorinated solvents, and polar solvent blends. Water absorption per ASTM D570 is measurable but low; parts intended for humid or outdoor service require dimensional stability testing after conditioning at 50 % RH and 23 °C. The resin is not represented as food-contact compliant under FDA 21 CFR unless a specific regulatory assessment is completed for the final end-use article. The liquid resin should be kept dry and away from amine-based contaminants because free amines can accelerate isocyanate side reactions in the uncured state. Production operators should monitor resin bath temperature and moisture exposure because water reacts with isocyanate-functional intermediates and can alter stoichiometry of the final network.

Thermal Degradation in RPU 130 Is Governed by Urethane Bond Stability

Urethane linkages in the cured network undergo reversible dissociation at elevated temperatures, and RPU 130 is not designed for continuous use above its heat deflection threshold. Short-term exposure above 80 °C may soften the material and reduce load-bearing capacity, while extended exposure above 120 °C accelerates thermo-oxidative degradation and discoloration. Thermogravimetric analysis can be used to separate volatile residuals from primary urethane degradation; published data for this specific RPU 130 formulation is limited, so each production lot should be characterized before use in thermal cycling. Applications that require sustained high temperature should consider cyanate ester or epoxy DLS resins instead. This distinction is why RPU 130 is typically assigned to ambient-temperature impact applications rather than hot-section service.

For incoming quality control, Shore D hardness and part density provide rapid batch acceptance checks on DLS production parts. Destructive tensile or Izod specimens should be pulled from each new resin lot and after any change in post-cure oven loading. Visual inspection for porosity is recommended on parts with wall thickness transitions, because the higher viscosity of RPU 130 increases the likelihood of trapped voids in sharp internal corners. Dimensional inspection on a coordinate measuring machine should compare features normal to the build direction and features parallel to it, since thermal post-cure shrinkage can introduce anisotropic offsets. RPU 130 is not a direct replacement for filled injection-molded thermoplastics in every application. In low-volume production, part consolidation, and structurally complex housings, the different failure envelope of a tough rigid photopolymer must be compared against the target load case and assembly tolerance.