Ultradur B4520: specs and equivalent grades
BASF standard unreinforced PBT for injection molding of functional parts, in natural and black. Published data, grades from other producers to ask about, and how to request a quote from one gaylord.
Request a QuoteThe short answer
Ultradur B4520 (BASF writes it B 4520) is a standard, unreinforced polybutylene terephthalate (PBT) injection molding grade for functional parts. BASF lists density 1.30 g/cm³ (ISO 1183), MVR 20 cm³/10 min at 250°C / 482°F, 2.16 kg (ISO 1133) and HDT 55°C / 131°F at 1.8 MPa (ISO 75). Grades from other producers to ask about include Valox 325, Celanex 2002 and Pocan B1305. They are not identical, so compare the data sheets and run a trial before switching.
Also written as: Ultradur B 4520; supplied uncolored (UN) and black (BK). B4520 FC Aqua and B4520 High Speed are separate BASF grades with their own data. Quote the full code from your drawing or bag label; color and additive suffixes change the grade.
Buying Ultradur B4520: one gaylord to a railcar · supplier COA on every prime lot · ships from 22+ partner warehouse locations · a polymer chemist checks the grade code before we quote · we aim to quote within one to three business days
Have a part number or drawing callout?
Paste it as written. A polymer chemist will tell you which grade it calls for, suggest equivalents and quote it by email.
Ultradur B4520 specs from the data sheet
Typical values from BASF’s data for Ultradur B 4520 as published in Material Data Center, with processing settings from BASF’s processing data sheet dated 09/2026. Typical values are not specifications; the lot COA shows what you actually receive. Values only compare at the same test method and condition.
| Property | Value | Test method or note |
|---|---|---|
| Producer (brand owner) | BASF | BASF data sheets |
| Polymer | PBT, unreinforced | ISO 1043-1: PBT |
| Process | Injection molding; BASF also gives extrusion settings | Material Data Center |
| Colors | Natural and black | BASF range chart; Material Data Center |
| Density | 1.30 g/cm³ | ISO 1183 |
| Melt flow | MVR 20 cm³/10 min | 250°C / 482°F, 2.16 kg, ISO 1133 |
| Viscosity number | 130 cm³/g | ISO 307, 1157, 1628 |
| Tensile modulus | 2,400 MPa (348,000 psi) | ISO 527 |
| Yield stress | 55 MPa (8,000 psi) | ISO 527 |
| Yield strain / nominal strain at break | 3.7% / more than 50% | ISO 527 |
| Flexural modulus | 2,400 MPa (348,000 psi) | ISO 178 |
| Flexural strength | 85 MPa (12,300 psi) | ISO 178 |
| Charpy notched impact | 5 kJ/m² at 23°C; 3 kJ/m² at -30°C | ISO 179/1eA |
| Charpy unnotched impact | No break at 23°C; 180 kJ/m² at -30°C | ISO 179/1eU |
| Notched Izod impact | 50 J/m (0.94 ft-lb/in), 3.2 mm bar | ASTM D256 |
| Melting temperature | 223°C / 433°F | ISO 11357-1/-3, 10°C/min |
| HDT at 1.8 MPa | 55°C / 131°F | ISO 75-1/-2 |
| HDT at 0.45 MPa | 165°C / 329°F | ISO 75-1/-2 |
| Molding shrinkage | 1.7% parallel and normal (ISO 294-4); 1.5% free shrinkage on a 150 by 150 by 3 mm film-gated plate | BASF processing data sheet |
| Water absorption | 0.5% saturation in water; 0.25% at 23°C / 50% RH | Similar to ISO 62 |
| Flame rating | HB at 0.8 mm and 1.5 mm, UL recognized | UL 94 |
| Glow wire | GWFI 850°C; GWIT 775°C (1.5 mm) | IEC 60695-2-12 / -13 |
| Comparative tracking index | 550 | IEC 60112 |
| Drying | 80–120°C / 176–248°F for 4 h in a dry-air or vacuum dryer; 0.04% maximum moisture | BASF processing data sheet |
| Melt temperature | 250–275°C / 482–527°F; 260°C / 500°F optimum | BASF processing data sheet |
| Mold temperature | 40–70°C / 104–158°F; 60°C / 140°F optimum | BASF processing data sheet |
| Packaging forms | 25 kg bags, 1,000 kg octabins or 1,000 kg big bags; bulk density about 0.7–0.8 g/cm³ | BASF processing data sheet |
| Food contact | No food-contact statement for B4520 on the sheets we opened; BASF sells a separate B4520 FC Aqua grade | Ask BASF for the regulatory statement for your exact grade |
Source data sheets are listed at the bottom of this page. Confirm against the current sheet for your exact grade code and color.
BASF says Ultradur melts are stable up to 280°C. Open containers stored in cold rooms only after they reach processing-room temperature: in BASF’s test a 25 kg bag at 5°C took 48 hours to reach 20°C.
Grades to ask about instead of Ultradur B4520
These grades from other producers have similar published specs. None is a drop-in replacement: additive packages, flow at molding shear rates, color and approvals differ. If your part, drawing or customer approval names Ultradur B4520, any change needs your approval and usually a trial.
| Grade | Producer | Melt flow | Density | Key property | How it compares |
|---|---|---|---|---|---|
| Valox 325 | NexPoint Materials (former SABIC) | MVR 14 cm³/10 min (250°C / 482°F, 2.16 kg, ISO 1133; SABIC international sheet) | 1.31 (specific gravity, ASTM D792) | Tensile strength at yield 51.7 MPa (ASTM D638); HDT 54.4°C at 1.8 MPa (ASTM D648); notched Izod 53 J/m (ASTM D256) | Close match. General-purpose unreinforced PBT with similar strength, HDT and Izod and a little lower flow (MVR 14 vs 20). SABIC’s Americas sheet asks for drying to 0.02% moisture, stricter than BASF’s 0.04%. Quote this alternative › |
| Celanex 2002 | Celanese | MVR 18 cm³/10 min (250°C / 482°F, 2.16 kg, ISO 1133) | 1.31 g/cm³ (ASTM D792, ISO 1183) | Tensile stress at yield 60 MPa (ISO 527); HDT 55°C at 1.8 MPa; notched Charpy 6 kJ/m² (ISO 179/1eA) | Close match. Medium-flow, general-purpose PBT with nearly the same flow (MVR 18 vs 20) and HDT. Celanese lists a hotter mold (65–93°C) and drying at 120–130°C for 4 h to 0.02%. Quote this alternative › |
| Pocan B1305 | Envalior | MVR 47 cm³/10 min (250°C / 482°F, 2.16 kg, ISO 1133) | 1.31 g/cm³ (ISO 1183) | Yield stress 60 MPa (ISO 527); HDT 65°C at 1.8 MPa (ISO 75); notched Charpy 2.8 kJ/m² | Partial match. Much higher flow (MVR 47 vs 20), with lubricant and release agent, and lower notched impact. Envalior recommends an 80–100°C mold and drying at 120°C to 0.02%. Suits thin walls; check toughness. Quote this alternative › |
From each producer’s published data. Brand owners and grade names change; confirm on the current data sheet.
Typical uses for Ultradur B4520
BASF describes B4520 as a standard injection molding grade for functional parts. Its Ultradur range chart groups it with medium-viscosity grades used for:
- Industrial functional parts (injection molding)
- Thin-walled profiles and pipes (extrusion)
- Automotive parts (listed as an application in Material Data Center)
What to check before you switch
- Check flow. Valox 325 flows a little less than B4520 at 250°C / 2.16 kg, and Pocan B1305 flows much more. A big flow change can shift fill, pack and shrink.
- B4520 High Speed is a different BASF grade with much higher flow (MVR 50 on BASF’s range chart). Do not swap one for the other without a trial.
- Moisture limits differ: 0.04% for BASF, 0.02% on the SABIC, Celanese and Envalior sheets. Dry to the stricter number if you run more than one.
- Mold temperatures differ. BASF lists 40–70°C; the Celanex 2002 and Pocan B1305 sheets list hotter molds.
- Unreinforced PBT shrinks about 1.7–2.0% on these sheets. Check critical dimensions on first articles.
- Ask for the producer’s food-contact or regulatory letter for the exact grade if the part needs one.
- Run a trial lot and check shrinkage, cycle time and appearance before you switch production.
Buying Ultradur B4520: price, lead time and lot size
- Lot size. From one gaylord to a railcar. See gaylord, LTL and truckload for typical weights per box.
- Where it ships from. 22+ partner warehouse locations. Material already in a partner warehouse usually moves sooner than a grade that has to come from the producer; your quote says which applies.
- Price. We do not publish prices because they move with feedstock, freight and order size. What moves your price most: lot size, color, ship-to region, and whether you need Ultradur B4520 itself or can accept a matched alternative. See how resin is priced and the monthly market update.
- Paperwork. Supplier COA on every prime lot (what a COA shows). Ask for the producer’s regulatory letter or UL file if your part needs them.
- Trying an alternative? Start with one gaylord as a trial lot, molded and checked before you commit a full release.
- If Ultradur B4520 itself is not available. Some branded grades are sold only through the producer’s own channels or go on allocation. If we cannot source it, we tell you, then quote a matched alternative with a side-by-side comparison.
Send the grade code, your annual volume and ship-to location. A polymer chemist checks it before we quote; we have been in the resin business for 30+ years. For several grades at once, use the resin RFQ template.
Trade names belong to their owners. ResinBridge is not affiliated with these producers; grade names are used only to identify the material. Data reflects published sheets as of October 2026.
Sources
- BASF Ultradur B 4520 data sheet from Material Data Center (PDF)
- BASF Ultradur B 4520 processing data sheet, 09/2026 (PDF)
- SABIC VALOX 325 Americas data sheet, UL Yellow Card E121562 (PDF copy)
- SABIC VALOX 325 international data sheet, UL Yellow Card E45329 (PDF copy)
- Celanese Celanex 2002 data sheet (PDF copy)
- Envalior Pocan B1305 data sheet from Material Data Center (PDF)
Common questions
What is Ultradur B4520?
Ultradur B4520 is BASF’s standard unreinforced PBT injection molding grade for functional parts, supplied in natural and black. BASF writes it Ultradur B 4520.
What is the melt flow of Ultradur B4520?
MVR 20 cm³/10 min at 250°C / 482°F, 2.16 kg, ISO 1133, per BASF’s processing data sheet dated 09/2026 and Material Data Center.
What is equivalent to Ultradur B4520?
Grades from other producers to ask about include Valox 325, Celanex 2002 and Pocan B1305. None is identical; compare data sheets and run a trial, and get approval if your part names Ultradur B4520.
How do you dry Ultradur B4520?
BASF gives 80–120°C / 176–248°F for 4 hours in a dry-air or vacuum dryer, to 0.04% moisture or less.
Can ResinBridge supply Ultradur B4520?
We quote Ultradur B4520 when our supply partners can source it. If they cannot, we say so up front and quote a matched alternative, named on the quote with its data sheet, so you can decide whether to trial it.
If your grade is not listed, tell us what you run. We source commodity, engineering and specialty resins.
Need Ultradur B4520 or an equivalent?
A polymer chemist reviews every request, then matches your grade or finds a matched alternative and prices it.
What to send for an accurate quote
- The grade name, from any supplier, or a data sheet
- Color (natural, black or a custom match)
- Fill type and percentage, if any
- Melt flow, if you know it
- Quantity for this order and what you use in a year
- Ship-to city and state or province
Quote Ultradur B4520 or a matched alternative
A polymer chemist checks the data sheet and tells you exactly what you would get before you order.
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