Material Profile: Engineering Flame Retardant FR940 Resin for SLA / LCD 3D
Phrozen SLA / LCD Resin Technical Report Series
Compiled from Phrozen official datasheets, SDS documents, and third-party technical reviews
Abstract—Phrozen Engineering FR940 (Gray) is a flame-retardant SLA resin meeting UL 94 V-0 self-extinguishing performance — the most stringent flammability rating commonly required for consumer electronics enclosures, automotive interior components, and aviation interior applications. Combines flame retardancy with engineering-grade mechanical properties (UTS 55–70 MPa, modulus 2.2–2.8 GPa).
Index Terms—additive manufacturing, SLA, LCD, engineering resin, flame retardant, UL 94 V-0, electronic enclosures.
I. MATERIAL IDENTIFICATION
This section establishes the canonical names and commercial designations under which the resin is supplied.
A. Designation
Trade name: Phrozen Engineering Series — Flame Retardant FR940 Resin. Color: Gray.
B. Resin Family
Flame-retardant-modified engineering acrylate photopolymer; 405 nm UV cure. Halogen-free flame-retardant additives.
C. Aliases and Alternative Designations
|
Alias |
Origin / Usage |
|
FR940 |
Standard engineering-series designation |
|
Engineering Flame Retardant FR940 Gray |
Color variant |
|
UL 94 V-0 SLA |
Performance descriptor |
II. COMPOSITION AND PHOTOPOLYMER CHEMISTRY
A. General Resin Family
Generic photo-polymerisation: monomers (multi-functional acrylates / urethane-acrylates) + photoinitiator (e.g., TPO / BAPO) + 405 nm UV → crosslinked thermoset network. Exact formulation is proprietary. Halogen-free flame-retardant additives produce intumescent self-extinguishing behavior.
Fig. 1. Photopolymer crosslinking schematic for the resin family.
Fig. 2. SLA / LCD print → wash → post-cure process flow.
B. Composition Breakdown
TABLE I COMPOSITIONAL BREAKDOWN OF ENGINEERING FLAME RETARDANT FR940 RESIN (TYPICAL / PER SUPPLIER DATASHEET)
|
Constituent |
Mass fraction |
Function |
|
Acrylate / urethane-acrylate matrix |
≈ 60–75 wt% |
Photopolymer network |
|
Halogen-free flame-retardant additives |
≈ 15–25 wt% |
Phosphorus / nitrogen-based; intumescent self-extinguishing |
|
Photoinitiator |
≈ 1–3 wt% |
Absorbs 405 nm UV |
|
Stabilisers, gray pigment |
≈ 2–4 wt% |
Color, surface flow, shelf life |
|
Total |
100 wt% |
— |
III. MECHANICAL PROPERTIES
FR940 maintains engineering-grade mechanical properties despite the flame-retardant loading — typical FR materials sacrifice 10–20% of strength vs unfilled equivalents.
TABLE II MECHANICAL PROPERTIES OF ENGINEERING FLAME RETARDANT FR940 RESIN (POST-CURE, ISO 527 / ASTM D638)
|
Property |
Value |
Test method / source |
|
Density |
≈ 1.15–1.25 g/cm³ |
ASTM D792 |
|
Viscosity (uncured liquid) |
≈ 400–600 cP @ 25 °C |
Brookfield viscometer |
|
Surface hardness |
≈ Shore D 82–86 |
ASTM D2240 |
|
Tensile strength, ultimate (UTS) |
≈ 55–70 MPa |
ASTM D638 / ISO 527 |
|
Tensile (Young's) modulus |
≈ 2200–2800 MPa |
ASTM D638 |
|
Elongation at break |
≈ 5–10 % |
ASTM D638 |
|
Flexural strength |
≈ 80–100 MPa |
ASTM D790 |
|
Izod impact, notched (23 °C) |
≈ 30–45 J/m |
ASTM D256 |
IV. RECOMMENDED PRINT PARAMETERS
Values below are the manufacturer-recommended starting points for compatible Phrozen LCD printers; specific machines may require ±10–20% adjustment based on LCD age and ambient temperature.
TABLE III RECOMMENDED PRINT AND POST-PROCESS PARAMETERS FOR ENGINEERING FLAME RETARDANT FR940 RESIN
|
Parameter |
Value / range |
Notes |
|
UV wavelength |
405 nm |
Standard for Phrozen LCD printers |
|
Compatible printers |
Sonic Mini 8K / 8K S, Sonic Mighty 8K / 12K, Sonic Mega 8K |
Best paired with the indicated resolution class |
|
Layer thickness |
0.025–0.050 mm (typical 0.030 mm) |
Thinner layers improve detail at the cost of print time |
|
Normal exposure (per layer) |
≈ 2.0–3.0 s @ 8K resolution |
Test-tower validation recommended |
|
Bottom exposure |
≈ 25–35 s × 6 layers |
First-layer adhesion to build plate |
|
Lift distance / speed |
≈ 6–8 mm @ 60–100 mm/min |
Slower for fine geometries |
|
Wash medium |
Isopropyl alcohol (IPA) or 95% ethanol |
30–60 s wash; do not over-soak |
|
Post-cure |
405 nm UV box, 60–120 min depending on size |
Phrozen Cure Mega S or equivalent |
V. GLASS TRANSITION TEMPERATURE (TG)
Reported / typical Tg: ≈ 75–85 °C.
Standard engineering-grade Tg; FR additives do not affect glass transition substantially.
VI. HEAT DEFLECTION TEMPERATURE (HDT)
HDT defines the temperature at which a 1.27 mm-thick standardised bar deflects 0.25 mm under the specified flexural load. Two test loads are reported per ASTM D648 / ISO 75.
TABLE IV HEAT DEFLECTION TEMPERATURE OF ENGINEERING FLAME RETARDANT FR940 RESIN
|
Test load |
HDT |
Test method / source |
|
0.45 MPa |
≈ 80–95 °C |
ASTM D648 |
|
1.82 MPa |
≈ 70–85 °C (estimate) |
ASTM D648 |
VII. DISTINGUISHING CHARACTERISTICS AND STANDARDS
A. UL 94 V-0 flame-retardancy
Meets the most stringent UL 94 self-extinguishing rating: vertical-burn test passes with no flaming drips and < 10 s extinguishment after 10-s ignition. The benchmark for consumer electronics, automotive, and rail interior parts.
B. Halogen-free flame-retardant chemistry
Phosphorus / nitrogen-based FR chemistry instead of brominated compounds — meets RoHS / REACH environmental requirements without the bromine-containing FR limitations.
C. Engineering-grade mechanical envelope
UTS 55–70 MPa and modulus 2.2–2.8 GPa make FR940 suitable for functional flame-retardant enclosures, not just compliance demonstration parts.
D. Electronic / automotive interior compliance
Suitable for prototypes that must demonstrate UL 94 V-0 prior to injection-mould tooling commitment — useful in IEC 60695-11-10 and similar test programs.
VIII. REPRESENTATIVE APPLICATIONS
Engineering Flame Retardant FR940 Resin is typically deployed in the following applications:
1) Consumer electronic enclosures: Audio / video / appliance enclosures requiring UL 94 V-0 compliance.
2) Automotive interior components: Glove-box covers, dashboard inserts, ducting requiring flame-retardancy.
3) Aviation interior fittings (non-flight-critical): Ground-test fixtures, cabin accessory mounts.
4) Industrial control panels: DIN-rail enclosures, junction-box covers in commercial / industrial environments.
5) Rail / mass-transit interior accessories: Cable holders, panel covers requiring fire-test compliance.
IX. REFERENCES
[1] Phrozen Technology, “FR940 Product Page,” 2024. Available: https://us.phrozen3d.com/products/flame-retardant-fr940-resin
[2] Phrozen Technology, “Engineering FR940 SDS,” 2024. Available: https://cdn.shopify.com/s/files/1/0436/6965/1618/files/SDS-Phrozen-Engineering_Series_Resin__Flame_Retardant_FR940_Gray.pdf
[3] UL 94, “Tests for Flammability of Plastic Materials,” Underwriters Laboratories, 2018.
[4] IEC 60695-11-10, “Fire hazard testing — Part 11-10: Test flames — 50 W horizontal and vertical flame test methods,” IEC.
[5] ASTM D638-14, “Standard Test Method for Tensile Properties of Plastics,” ASTM International.
[6] ASTM D2240-15, “Standard Test Method for Rubber Property — Durometer Hardness,” ASTM International.
[7] ASTM D648-18, “Standard Test Method for Deflection Temperature of Plastics Under Flexural Load,” ASTM International.
(Image Source : Phrozen)