HP Orange 3357 — Plastics-Grade Pigment Orange 13 (PO13) for Low-Warpage PP & PVC | Honor Pigments

Technical Information

What Is PO13

A plastic part coming out of the mold warped is not a pigment problem — until the pigment is what’s causing the warpage. In semi-crystalline polymers like polypropylene, organic pigment particles act as heterogeneous nucleation sites during cooling. Uneven nucleation means uneven crystal growth, differential shrinkage, and parts that fail dimensional inspection — even when every other process parameter is dialed in. Pigment Orange 13 (CAS 3520-72-7, CI 21110), the disazopyrazolone organic pigment that delivers the brightest, most cost-effective orange across global manufacturing, carries a hidden plastics problem: its untreated particle surface is a strong nucleating agent, and in thin-wall PP molding, that means warpage. The standard solution — add a nucleating agent, adjust mold temperature, extend cycle time — treats the symptom. HP 3357 treats the cause, by engineering the pigment surface itself to moderate nucleation. It is the grade that makes PO13 a plastics pigment, not a pigment that happens to be used in plastics.

Why Choose HP 3357

HP 3357 is the plastics-optimized grade in Honor Pigments’ six-grade PO13 family — the only variant engineered for polymer melt processing. Where HP 3434 is tuned for solvent-based gravure and flexo inks with high tinting strength, HP ORANGE 3632 is the water-based coating specialist, HP ORANGE 3545 is the solvent-based gravure and offset benchmark, and EARTH COLOUR ORANGE and Permanent Orange G serve the cost-first and yellow-shade ends of the ink and coating market — HP 3357 is built for a different set of problems entirely. Its surface treatment is designed to reduce the nucleating effect that causes untreated PO13 to trigger uneven polypropylene crystallization, delivering approximately 30% less warpage in thin-wall PP injection molding. It carries a migration resistance rating of 6-7 in PVC, verified against standard phthalate and trimellitate plasticizer systems, which makes it the correct choice for flexible PVC compounds, artificial leather, and cable sheathing where pigment extraction into the plasticizer phase is a field-failure risk. The thermal window extends to 200°C, covering the processing range of PP, PVC, and polyurethane cast elastomers. HP 3357 is not an ink grade — its recommended applications in solvent-based coatings are a secondary capability, not the design intent. For ink and coating formulators, HP 3434 or HP ORANGE 3545 will deliver better dispersion speed and color development. For plastics, HP 3357 is the only PO13 grade designed for the melt.

Key Features

• Low-warpage surface treatment for thin-wall PP injection molding: the pigment particle surface is modified to moderate nucleation during polypropylene crystallization, reducing differential shrinkage that causes part warpage — documented at approximately 30% less distortion versus untreated PO13 in 1mm-wall PP parts, which means fewer dimensional rejects and less mold-tuning downtime on the production floor.
• Migration resistance of 6-7 in plasticized PVC prevents interlayer staining: the disazopyrazolone molecule has inherently limited solubility in common phthalate and trimellitate plasticizers, and HP 3357’s surface engineering preserves that resistance — so flexible PVC sheet, artificial leather, and cable sheathing can be stacked, rolled, or placed in contact with other materials without orange pigment transferring to adjacent surfaces.
• 200°C thermal stability covers standard PP, PVC, and PUR processing: the pigment holds shade and color strength through injection molding, extrusion, calendering, and cast-elastomer cure cycles within this window, providing a single orange pigment option for compounders whose product mix spans multiple polymer families without crossing into engineering-resin temperature territory.
• Solvent-based coating compatibility as a secondary capability: while HP 3357 is plastics-first, it disperses adequately in alkyd, acrylic, and epoxy solvent-based coating systems via standard bead-mill processing — useful for the compounder who also runs a small solvent-based paint line and wants to consolidate pigment purchasing without qualifying a separate grade.
• Documented batch quality with spectrophotometric release: every production lot is tested against the master standard under D65 (ΔE ≤ 1.2) and ships with a Certificate of Analysis covering shade, color strength, and dispersibility — giving the plastics compounder auditable incoming quality data that correlates pigment lot number to molded-part color consistency across production campaigns.

Recommended Applications

Primary: PP injection molding — thin-wall food containers, caps and closures, consumer packaging where part flatness is a dimensional requirement and warpage-induced scrap directly erodes margin. PVC soft compounds — flexible sheet, artificial leather, cable sheathing, and flooring where plasticizer migration resistance prevents color transfer during storage, stacking, and end-use. Polyurethane cast elastomers — colored PUR parts requiring uniform pigment distribution without affecting cure chemistry.

Secondary: Solvent-based industrial coatings — alkyd, acrylic, and epoxy systems where the compounder or converter also runs a solvent-based paint line and values single-pigment purchasing. PP masterbatch production at standard letdown ratios of 0.5-3% for cost-effective, warp-controlled coloring of downstream molded goods.

PO13 Family Product Lineup — Select Your Grade:

Grade	Positioning	Best For	System
Permanent Orange G	Yellow-shade generalist	Warm-tone offset inks, packaging where yellower orange extends process-color gamut	Solvent-based
EARTH COLOUR ORANGE	Cost-first commodity	High-volume commodity ink and coating work, earth-tone packaging	Solvent-based
HP ORANGE 3545	Gravure & offset benchmark	Sheet-fed offset inks, solvent-based industrial coatings, multi-process consolidation	Solvent-based
HP ORANGE 3632	Water-based specialist	Water-based architectural coatings, retort packaging inks, low-VOC formulations	Water-based only
HP 3434	Ink & textile high-strength	Solvent gravure/flexo/offset inks, textile pigment printing, high-tinting-strength formulations	Solvent-based
HP 3357	Plastics low-warpage	PP injection molding, PVC soft compounds, PUR cast elastomers	Plastics melt

Not sure which grade fits your process? Contact Honor Pigments technical support with your polymer system, processing temperature profile, and critical performance requirements for a grade-specific recommendation — including warpage comparison data between HP 3357 and standard PO13 grades in your target resin.

Technical Data

HP 3357 — Technical Specifications

Property	Value	Notes
CI Number	21110	C.I. Pigment Orange 13
CAS Number	3520-72-7	—
Chemical Class	Disazopyrazolone	Benzidine-derived disazo
Molecular Formula	C₃₂H₂₄Cl₂N₈O₂	—
Molecular Weight	623.49 g/mol	—
Appearance	Orange powder	Free-flowing, low-dusting
Heat Stability	180–200°C	PP injection molding window 200–230°C; not for engineering plastics (ABS/PA/PC) >230°C
Lightfastness	4–5 (Blue Wool Scale 1–8)	Indoor and limited semi-outdoor applications
Migration Resistance (PVC)	6–7	Documented for standard phthalate and trimellitate plasticizer systems
Warpage Control	~30% less warpage vs untreated PO13	In PP thin-wall (1mm) injection molding — surface treatment moderates crystallization nucleation rate
Acid Resistance	4–5	—
Alkali Resistance	4–5	—
Specific Density	~1.4–1.5 g/cm³	Estimated from PO13 family data
Oil Absorption	Contact manufacturer	Not specified in grade documentation; PO13 family typical range 40–55 g/100g
Chemical Resistance — Soap	Good	—
Chemical Resistance — Paraffin	Good	—
Chemical Resistance — Sterilization	Good	—
Resin Compatibility (Plastics)	PP, PVC, PUR	Not for engineering plastics (ABS/PA/PC)
Resin Compatibility (Coatings)	Alkyd, Acrylic, Epoxy	Solvent-based only; secondary application
Typical Dosage (PP Masterbatch)	0.5–3%	Letdown ratio in finished molded part
Typical Dosage (PVC Compound)	1–5%	Direct compounding or masterbatch letdown
Packaging	25 kg/bag	400 kg/pallet standard
Shelf Life	5 years	Cool, dry, ventilated storage

Rating Scale Notes

• Lightfastness (Blue Wool Scale): 1 = very poor, 8 = outstanding. 4–5 is suitable for indoor and limited semi-outdoor applications.
• Heat Stability: Temperature at which the pigment maintains shade and color strength after 10 minutes at temperature in the specified medium.
• Migration Resistance: 1 = severe bleeding, 8 = no migration. Tested in PVC with standard plasticizer systems.
• Chemical Resistance: 1 = severe attack, 5 = no visible change.

Packaging

Standard packaging: 25 kg per bag, 400 kg per pallet. Custom packaging available upon request for high-volume contract customers. Sample quantities available for first-time evaluation — contact the Honor Pigments sales team with your target polymer system and processing conditions.

Storage & Shelf Life

Store in a cool, dry, well-ventilated area away from direct sunlight and moisture. Keep containers sealed when not in use. Shelf life: 5 years from date of manufacture when stored under recommended conditions. For pre-compounded masterbatch containing HP 3357, consult the masterbatch manufacturer’s specific storage recommendation — the pigment’s inherent stability does not extend to the polymer carrier’s aging characteristics.

Transportation

Non-hazardous for transport under UN, IMDG, and IATA regulations. Not classified as dangerous goods. Standard freight options: sea freight (FCL/LCL), air freight for urgent orders, and rail freight to Central Asia and Europe. All shipments include batch-specific Certificate of Analysis (COA), Technical Data Sheet (TDS), and Material Safety Data Sheet (MSDS/SDS).

Frequently Asked Questions About PO13

HP 3357 warpage control in PP thin-wall injection molding — how does it work?

HP 3357 controls warpage through a surface treatment applied during pigment manufacturing that moderates the nucleating effect Pigment Orange 13 (CAS 3520-72-7, CI 21110) particles exert on semi-crystalline polypropylene during cooling. Untreated organic pigment particles provide heterogeneous nucleation sites that trigger uneven spherulite growth — the polymer crystallizes faster around pigment particles than in the bulk, creating internal stress gradients that manifest as part warpage after ejection. HP 3357’s surface treatment reduces this nucleation anisotropy, documented at approximately 30% less warpage versus untreated PO13 in thin-wall PP injection molding at 1mm wall thickness. For the molder producing food containers, caps, and thin-wall packaging, this translates to parts that meet flatness specifications without the additional nucleating-agent cost, mold-temperature adjustments, or extended cycle times that compensate for pigment-induced warpage.

PO13 migration resistance in PVC soft compounds — does HP 3357 prevent plasticizer bleeding?

HP 3357 carries a migration resistance rating of 6-7 in PVC tested against standard phthalate and trimellitate plasticizer systems. The mechanism is fundamental to the disazopyrazolone molecule itself: the pigment has inherently limited solubility in common plasticizers, so it does not dissolve into the plasticizer phase during thermal compounding or long-term service contact. HP 3357’s surface treatment preserves this intrinsic resistance — the same particle engineering that moderates nucleation in PP does not compromise the molecule’s plasticizer-fastness. For the PVC compounder producing flexible sheet, artificial leather, flooring, and cable sheathing, a rating of 6-7 means finished products can be stacked, rolled, or placed in direct contact with light-colored materials without the orange pigment transferring across the interface — a failure mode that generates visible staining and customer returns in PVC leather goods, multi-layer flooring, and wire harness assemblies.

HP 3357 processing temperature window for polypropylene masterbatch?

HP 3357 is thermally stable through 200°C, with a recommended PP injection molding operating window of 200-230°C. The pigment’s disazopyrazolone chromophore maintains shade and color strength across this range without the decomposition or shade drift that affects less thermally robust organic pigments at elevated melt temperatures. For the masterbatch producer compounding HP 3357 at 30-50% pigment loading and letting down to 0.5-3% in the final molded part, this thermal window comfortably covers standard PP homopolymer and copolymer grades. The limitation: HP 3357 is not formulated for engineering thermoplastics (ABS/PA/PC) whose processing temperatures exceed 230°C. For those polymer systems, a more thermally robust pigment chemistry — benzimidazolone or phthalocyanine — is required. For the PP injection molding segment that represents the overwhelming majority of plastics orange consumption, HP 3357’s thermal window is fit for purpose and well-documented.

HP 3357 vs HP 3434 vs HP ORANGE 3632 — which PO13 for plastics coloring?

HP 3357 is the only Pigment Orange 13 (CI 21110) grade engineered for polymer melt processing. HP 3434 is the ink-and-textile specialist — optimized for solvent-based gravure, flexo, and offset inks with high tinting strength and rapid dispersion in low-viscosity vehicles; its particle characteristics are tuned for ink milling, not melt compounding, and it carries no warpage control data for plastics. HP ORANGE 3632 is the water-based coating specialist with hydrophilic surface treatment — incompatible with melt processing. HP ORANGE 3545 and EARTH COLOUR ORANGE are solvent-based ink and coating grades. The consequence of selecting a non-plastics PO13 for injection molding: untreated pigment particles act as uncontrolled nucleation sites, warpage can increase from 1% to 8% scrap rate at production volumes, and the cost of dimensional rejects quickly exceeds any pigment price difference. For any application involving PP, PVC, or PUR melt processing, HP 3357 is the correct specification — the only PO13 with documented low-warpage performance and migration resistance optimized for the thermal and chemical environment of polymer compounding.

HP 3357 pigment loading for PVC artificial leather coloring?

For PVC artificial leather and flexible sheet coloring, HP 3357 is typically dosed at 1-5% of total compound weight. Processing routes include pre-dispersion into a PVC masterbatch followed by letdown, or direct compounding via two-roll mill or internal mixer at 160-190°C. The migration resistance rating of 6-7 is the critical specification for this application: in roll-stored PVC leather, pigment extraction into the plasticizer phase causes visible staining where orange-colored material contacts light-colored or uncolored adjacent layers — a failure mode that generates customer returns and brand-owner rejection. HP 3357’s combination of plasticizer-fastness and the surface treatment that also delivers low-warpage behavior in PP means the pigment distributes uniformly through the PVC melt, supporting consistent shade across production lots. Honor Pigments recommends a dispersion and migration trial at the compounder’s specific plasticizer type and loading to confirm performance before adopting HP 3357 for full-scale PVC leather production.

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Disclaimer: The technical data and application recommendations provided on this page are based on Honor Pigments’ internal testing and industry-standard evaluation methods. Actual performance may vary depending on specific polymer grades, processing parameters, plasticizer systems, and end-use conditions. Always conduct application-specific testing before full-scale production. Contact Honor Pigments technical support for the most current batch-specific Certificate of Analysis, regulatory documentation, and formulation guidance for your target polymer system.