Pigment Red 177 (PR177) — Anthraquinone Red for High-Performance Coatings

Product Overview

Short answer: Pigment Red 177 (PR177, C.I. 65300, CAS 4051-63-2) is a high-performance anthraquinone red, and HP RED 2160 is our grade of it. It is a red powder rated in its TDS (FEB 2024) for heat stability to 300 °C (10-minute stoving, full shade and reductions), light fastness 8 (full shade) / 8 (tint) on the 1–8 Blue Wool scale and weather resistance 5 / 5 on the 1–5 grey scale. The same TDS rates it recommended (Y) for decorative solvent-based and water-based paints, industrial paints, decorative universal stainers and powder coatings; for polyolefin, polystyrene, PVC, EVA and ABS plastics; and for metal-decorative, polyamide-base, NCPU, vinyl, CLPP-base, PU and NCPA printing inks. It is not recommended (N) for spun fibres (PP, nylon, PET), inkjet inks of any type, or electrophotographic toners.

PR177 is an anthraquinone pigment, a chemistry chosen for durability rather than economy. Its colour is a red with a bluish undertone, and the grade TDS states that it develops that tone cleanly in white reductions. The practical consequence of the chemistry is where the pigment sits in a process: the anthraquinone chromophore is the reason this C.I. carries a 300 °C stoving rating and 5/5 weather resistance on the 2160 grade, which is what places it in industrial and powder coatings, engineering plastics and quality printing inks rather than in economy interior work.

This page covers our PR177 (HP RED) grade family: HP RED 2160, HP RED 2628, HP RED 26246 and HP RED 2645. All four carry the same colour index — Pigment Red 177 (C.I. 65300, CAS 4051-63-2) — and differ chiefly in the heat window stated on their own technical data sheets, so the selection notes below are written to help you match grade to process.

Selection & Positioning: Which PR177 (HP RED) Grade to Use

All four grades are Pigment Red 177. They are not interchangeable: each carries its own TDS heat window, and HP RED 2160 is the highest-stoving grade. Match the grade to the process temperature first, then confirm shade and strength by drawdown in your own system.

Practical rule (TDS-based): for stoving or processing up to the 200 °C window, the 2628 / 26246 / 2645 grades cover the stated TDS rating; where the process runs hotter — the powder- and coil-coating class of cure — start from HP RED 2160, whose TDS states 300 °C. Crystal form is stated on those sheets as A2B (HP RED 26246) and A3B (HP RED 2628, HP RED 2645); the HP RED 2160 TDS does not state a crystal form. Where a system sits between the two figures, the TDS is the reference and a drawdown of both grades in your own resin is the decision test. This is a grade-to-process match, not a performance ranking; we publish no ranking we cannot support with a TDS line.

Technical Specifications

Product information and physical properties below are taken from the grade TDS (HP RED 2160, issue FEB 2024); the SDS (Jan 2024) is the source for the safety, inventory and decomposition data.

Measurement notes (TDS): light fastness is rated on the 1–8 Blue Wool scale (1 = poor, 8 = high); heat stability is the maximum temperature at which the pigment can be stoved for 10 minutes in full shade and in reductions without a significant shade change; oil absorption is determined to EN ISO 787-5 in g linseed oil per 100 g pigment; the resistance ratings use a 1–5 grey scale (5 = no change). Values depend on concentration, resin and test method — validate in your own system.

Application Matrix (TDS)

The matrix below follows the HP RED 2160 TDS (FEB 2024), where Y = recommended, O = suitable and N = not recommended.

Read the matrix as a starting screen, not a guarantee: Y means the TDS lists the system as recommended, O means suitable, and N means the TDS excludes it. For systems the TDS does not list, ask for a sample and confirm by drawdown before you commit a production batch.

Weathering & Light Fastness

Two independent lines of evidence sit behind the durability claim. The first is the TDS rating itself: light fastness 8 (full shade) / 8 (tint) on the 1–8 Blue Wool scale and weather resistance 5/5 on the 1–5 grey scale for HP RED 2160 (TDS, FEB 2024). The second is measured outdoor exposure on the A3B grade of the same colour index.

An independent 15-month outdoor exposure test was run on red topcoat panels at a sub-tropical site (south-facing, 20° to the ground, Hainan, China), from December 2003 to March 2005. The report (issued by the Hainan Automotive Test Institute, report QS-05/RP-02) applied GB/T 9754-88 for 20° specular gloss, GB/T 11186-89 for colour measurement, GB 1764-79 for film thickness and GB/T 1766-95 for ageing rating. For the A3B (Pigment Red 177 A3B) panels the report concludes colour change ΔE*ab below 0.5 units after 15 months, with gloss loss of 7.3–8.7% (about 91–93% gloss retention) rated grade 1 loss-of-gloss, and no colour change to the eye; the second panel set finished below 1.2 units ΔE*ab.

Source note: the exposure figures above are quoted from that third-party 15-month outdoor report on the PR177 A3B topcoat panels; the fastness ratings in the tables above are from our grade TDS. Outdoor results are site- and formulation-specific. For a documented service life in your own coating or plastic, we will quote the TDS figures and, where you need project evidence, arrange exposure or accelerated-weathering testing on your formulation.

Handling, Storage & Documentation

• Packaging and shelf life (TDS): 10 kgs/bag, 400 kgs per pallet; shelf life 5 years. Packaging can be adapted to your logistics.
• Storage (TDS/SDS): keep in a cool, dry, well-ventilated place in closed containers, away from sources of ignition and heat, separated from foodstuffs; do not store together with strong oxidising agents.
• Handling (SDS): avoid generating or inhaling dust (dust can form an explosive mixture with air), take precautionary measures against electrostatic charge, avoid contact with skin and eyes and wash after handling.
• Transport and classification (SDS): not classified as dangerous under GHS/CLP (no pictogram, no signal word, no hazard statement) and not regulated as dangerous goods for ADR/RID, IMDG or IATA.
• Toxicology and ecology (SDS): acute oral toxicity rat LD50 above 15,000 mg/kg; fish 96-hour LC50 above 100 mg/L; no known skin or eye irritation; not PBT/vPvB.
• Inventory listing (SDS): listed on EINECS, TSCA, DSL, IECSC, NZIoC, PICCS, KECI and AICS.
• Documentation: grade TDS and SDS are available on request, together with evaluation samples. Food-contact or other regulated end uses depend on your market, full formulation and measured migration, so we scope that documentation per application rather than issuing a blanket statement.

Related Products

• Pigment Red 176 (PR176) – HP RED 2585 – the neighbouring high-performance red for coatings and inks.
• Pigment Red 254 (PR254) – HP RED 2135 – DPP red for automotive and industrial coatings.
• Pigment Red 254 (PR254) – HP RED 2634 – the second PR254 grade in the range.
• Pigment Red 122 (PR122) – HP RED 23126 – quinacridone magenta-red for the same high-performance segment.
• Pigment Red 122 (PR122) – HP RED 2574J – PR122 grade for plastics and inks.

Frequently Asked Questions

What is the heat stability of Pigment Red 177 (HP RED 2160)?

The HP RED 2160 TDS (FEB 2024) states heat stability of 300 °C for a 10-minute stoving cycle in full shade and in reductions, and the SDS records a decomposition temperature of 300 °C (the pigment decomposes without discernible melting). The other PR177 grades in the range — HP RED 2628, HP RED 26246 and HP RED 2645 — are stated at 200 °C on their own TDS. Match the grade to your process window and confirm on a drawdown; the decomposition figure is a material property, not a processing window.

What are the light fastness and weather resistance of PR177?

For HP RED 2160 the TDS rates light fastness 8 (full shade) / 8 (tint) on the 1–8 Blue Wool scale and weather resistance 5 (full shade) / 5 (tint) on the 1–5 grey scale. The older 2628 / 26246 / 2645 sheets rate light fastness 8 / 7 and weather resistance 5 / 4–5. On top of the TDS rating, an independent 15-month outdoor exposure test (Hainan, 2003–2005) on PR177 A3B topcoat panels recorded colour change below 0.5 ΔE*ab units and about 91–93% gloss retention.

Which grade should I choose — HP RED 2160 or HP RED 2628 / 2645 / 26246?

All four are the same colour index, Pigment Red 177 (C.I. 65300, CAS 4051-63-2). The practical difference is the heat window on each TDS: 300 °C for HP RED 2160 and 200 °C for the 2628 / 26246 / 2645 grades. Start from the grade whose stated window covers your cure or processing temperature — HP RED 2160 where the process runs hotter — then confirm shade and strength by drawdown. This is a grade-to-process match rather than a performance ranking.

Can Pigment Red 177 (HP RED 2160) be used in plastics and printing inks?

Yes within the TDS limits. The HP RED 2160 TDS rates polyolefins, polystyrene, PVC and PVC leather cloth, EVA and ABS as recommended (Y), and rates spun fibres (PP, nylon, PET) as not recommended (N). For printing inks it rates metal-decorative, polyamide-base, NCPU, vinyl, CLPP-base, PU and NCPA inks as recommended (Y) and silkscreen, sheet-fed offset and water-based inks as suitable (O). Inkjet inks of any type and electrophotographic toners are not recommended (N); migration resistance in PVC is rated 5.

How is HP RED 2160 regulated, and is it approved for food contact?

The SDS states the product is not classified as dangerous under GHS/CLP, is not regulated as dangerous goods for ADR/RID, IMDG or IATA, and is listed on EINECS, TSCA, DSL, IECSC, NZIoC, PICCS, KECI and AICS. Acute oral toxicity is low (rat LD50 above 15,000 mg/kg). A blanket food-contact approval is not stated on the TDS or SDS: compliance for a regulated end use depends on your market, the full formulation and measured migration, so confirm on CoA and per-application documentation. Packaging is 10 kgs/bag, 400 kgs per pallet, with a 5-year shelf life.