Ultradur B4300 G6: specs and equivalent grades
BASF polybutylene terephthalate (PBT) with 30% glass fiber, a general injection molding grade for automotive and electrical parts. Published data, grades to ask about, and how to request a quote from one gaylord.
Request a QuoteThe short answer
Ultradur B4300 G6 is BASF’s 30% glass fiber reinforced PBT (PBT-GF30) for injection molding. BASF positions it for technical parts in the automotive and electrical industries, and offers it in natural and black. Published values (BASF product information, 09/2026): density 1,530 kg/m³ (ISO 1183), MVR 11 cm³/10 min at 250°C / 2.16 kg (ISO 1133), tensile modulus 9,800 MPa and stress at break 140 MPa (ISO 527), HDT 205°C / 401°F at 1.8 MPa (ISO 75), melting point 223°C, and UL 94 HB at 0.75 and 3 mm. BASF lists a 250–275°C melt, a 60–100°C mold and a maximum of 0.04% moisture at processing. These are typical values; confirm them on the current producer data sheet. Grades to ask about include Celanese’s Celanex 3300 and Crastin SK605 NC010, both PBT GF30. None is a drop-in replacement.
Also written as: Ultradur B 4300 G6 (BASF’s own spacing), B4300G6, PBT-GF30. BASF sells color versions (for example LS BK15141, which it says is optimized for automotive interiors) and a separate hydrolysis-resistant B4300 G6 HR. Quote the full grade and color code from your drawing or bag label.
Buying Ultradur B4300 G6: 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
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Ultradur B4300 G6 specs from the data sheet
Typical values for uncolored product at 23°C from BASF’s Ultradur B 4300 G6 product information (dated 09/2026). Values are ISO unless noted. Typical values are not specifications. Confirm them on the current producer data sheet; 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 | No ownership change found for Ultradur |
| Polymer | PBT-GF30 (polybutylene terephthalate, 30% glass fiber); natural and black offered | ISO 1043. BASF says it can also be supplied as BMBcert or Ccycled mass balance versions with unchanged properties |
| Process | Injection molding | |
| Density | 1,530 kg/m³ (1.53 g/cm³) | ISO 1183 |
| Melt volume-flow rate (MVR) | 11 cm³/10 min | ISO 1133, 250°C / 2.16 kg |
| Viscosity number | 105 cm³/g | ISO 307, 1157, 1628 (phenol / 1,2-dichlorobenzene 1:1) |
| Water absorption, saturated in water, 23°C / moisture absorption, 23°C / 50% RH | 0.4 % / 0.2 % | Similar to ISO 62 |
| Halogen content (Cl, Br, I) | < 100 mg/kg | Schoeniger IC |
| Melting point | 223°C (433°F) | ISO 11357-1/-3 |
| Molding shrinkage, parallel / normal | 0.30 % / 1.10 % | ISO 294-4 |
| Tensile modulus | 9,800 MPa | ISO 527-1/-2 |
| Stress / strain at break | 140 MPa / 3 % | ISO 527-1/-2 |
| Tensile creep modulus, 1000 h, 23°C | 7,500 MPa | ISO 899-1, strain ≤ 0.5 % |
| Flexural modulus / strength | 8,800 MPa / 210 MPa | ISO 178. Outer fiber strain 3.1 % |
| Charpy notched impact, 23°C / −30°C | 9 / 8.5 kJ/m² | ISO 179/1eA. Unnotched: 74 / 74 kJ/m² (ISO 179/1eU) |
| Notched Izod impact, 23°C | 100 J/m | ASTM D256 |
| Ball indentation hardness | 190 MPa | ISO 2039-1, 961 N, 30 s |
| HDT at 1.8 MPa / 0.45 MPa | 205°C (401°F) / 220°C (428°F) | ISO 75-1/-2 |
| Max. service temperature, short cycle | 210°C | BASF value, no test method |
| Temperature index, 50% loss of tensile strength | 150°C after 20,000 h; 165°C after 5,000 h | IEC 60216 |
| Thermal expansion (CLTE), 23–55°C, longitudinal / transverse | 25 / 115 × 10−6 /K | ISO 11359-1/-2 |
| Thermal conductivity / specific heat | 0.27 W/(m K) / 1,050 J/(kg K) | DIN 52612-1 for conductivity |
| Flammability | HB at 0.75 mm and 1.5 mm (IEC 60695-11-10); UL 94 HB at 0.75 mm and 3 mm, yellow card available; HB at 4 mm (IEC 60707) | Passes ISO 3795 / FMVSS 302 at 1 mm and above |
| Oxygen index | 19.5 % | ISO 4589-1/-2 |
| Relative permittivity, 100 Hz / 1 MHz | 4 / 3.8 | IEC 62631-2-1 |
| Dissipation factor, 100 Hz / 1 MHz | 25 / 170 × 10−4 | IEC 62631-2-1 |
| Volume / surface resistivity | > 1E14 Ohm·m / 1E13 Ohm | IEC 62631-3-1 / -3-2 |
| Comparative tracking index | 375 (test liquid A); CTI M 125 (test liquid B) | IEC 60112 |
| Electric strength | 37 kV/mm | IEC 60243-1, 1 mm plate |
| Melt temperature | 250–275°C (482–527°F) | BASF, injection molding and extrusion |
| Mold temperature | 60–100°C (140–212°F) | BASF, injection molding |
| Moisture at processing | Less than 0.04 % | BASF says pre-drying “should generally be the rule.” The product information gives no drying temperature |
| Melt stability | Stable up to 280°C; above 290°C it can give off carbon monoxide and tetrahydrofuran | BASF product safety note |
| Packaging and bulk density | 25 kg bags, 1,000 kg octabins or 1,000 kg big bags; bulk density about 0.7–0.8 g/cm³ | BASF |
Source data sheets are listed at the bottom of this page. Confirm against the current sheet for your exact grade code and color.
PBT hydrolyzes if it is molded wet, and the parts can lose strength without looking different. Dry to BASF’s 0.04% limit before molding, and let cold bags reach room temperature before opening. BASF notes a 25 kg bag at 5°C took about 48 hours to reach 20°C.
Grades to ask about instead of Ultradur B4300 G6
These are PBT with 30% glass fiber from another producer, with flow in a similar range at the same test condition (250°C / 2.16 kg). None is a drop-in replacement: additive packages, flow at molding shear rates, color and approvals differ. Our Valox 420 page covers another PBT GF30 buyers ask about; we did not re-check its numbers against a current producer sheet for this page, so it is not in the table. If your part, drawing or customer approval names Ultradur B4300 G6, any change needs that approval and a trial.
| Grade | Producer | Melt flow | Density | Key property | How it compares |
|---|---|---|---|---|---|
| Celanex 3300 | Celanese | MVR 13 cm³/10 min; MFR 17 g/10 min (250°C, 2.16 kg, ISO 1133) | 1.53 g/cm³ (ISO 1183) | Tensile modulus 10,000 MPa; stress at break 135 MPa (ISO 527); flexural modulus 9,700 MPa (ISO 178); HDT 205°C at 1.8 MPa (ISO 75); Charpy notched 8.5 kJ/m²; CTI 425 | Ask about. Same glass level and density, slightly higher flow (MVR 13 vs 11) and similar strength and HDT. Celanese calls it a general purpose, high flow grade. Shrinkage is given as a range (0.3–0.7 % parallel, 0.7–1.1 % normal), so check part dimensions. Celanese lists drying at 120°C and an 80°C optimum mold. Quote this alternative › |
| Crastin SK605 NC010 | Celanese | MVR 7 cm³/10 min; MFR 10 g/10 min (250°C, 2.16 kg, ISO 1133) | 1.53 g/cm³ (ISO 1183) | Tensile modulus 10,000 MPa; stress at break 140 MPa (ISO 527); flexural modulus 9,000 MPa; HDT 205°C at 1.8 MPa (ISO 75); Charpy notched 10 kJ/m²; CTI 400; RTI electrical 130°C | Ask about. Same glass level, density, HDT and shrinkage (0.3 / 1.1 %), lubricated. Lower flow than B4300 G6 (MVR 7 vs 11), which can matter for thin walls. Formerly a DuPont brand, now Celanese. See our Crastin SK605 page. Quote this alternative › |
From each producer’s published data; typical values, confirm on the current producer data sheet. Brand owners and grade names change.
Typical uses for Ultradur B4300 G6
BASF describes B4300 G6 as a grade for technical parts in the automotive and electrical industries, and says the LS BK15141 color is optimized for automotive interiors. Typical PBT GF30 parts include:
- Automotive technical parts, including interior parts (LS BK15141)
- Electrical parts such as connectors and housings that need low water uptake and stable dimensions
- Parts that must pass FMVSS 302 at 1 mm and above
- Parts that need a 150°C IEC 60216 temperature index at 20,000 h
What to check before you switch
- Owner check: Ultradur is a BASF brand with no ownership change found. See the brand ownership tracker.
- Standard vs hydrolysis resistant. B4300 G6 HR is a separate BASF grade for under-hood connectors and electronics housings. Its processing sheet lists density 1,510 kg/m³, MVR 5.5 cm³/10 min and shrinkage of 0.50 / 1.30 %, so it is not interchangeable without a trial.
- Flame rating. B4300 G6 is HB only. If your part needs V-0, you need a flame retardant PBT and a new approval. See UL 94 flame ratings.
- Warp. BASF’s cross-flow shrinkage (1.10 %) is several times the flow value (0.30 %). Gate location and a grade switch can change how flat parts come out. See PBT GF30 properties.
- Dry it. BASF asks for less than 0.04 % moisture at processing. If you switch to another producer’s PBT, follow that sheet’s limit. See our resin drying guide.
- Glass-filled nylon is not a substitute without approval. It absorbs much more water. See glass-filled nylon vs PBT.
- Run a trial lot and check fill, warp, shrinkage, weld lines and appearance before you switch production.
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Buying Ultradur B4300 G6: 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. Lead time is confirmed with your quote. Material already in a partner warehouse usually moves sooner than a grade that has to come from the producer.
- Price. We do not publish prices because they move with feedstock, freight and order size. What moves your price most: lot size, color code, standard vs HR version, ship-to region, and whether you need Ultradur B4300 G6 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 UL file or compliance letters if your part needs them. Payment terms are confirmed with your quote.
- Trying an alternative? Samples (~50 lb) are available upon credit approval, or start with one gaylord as a trial lot. Custom compounding and color matching are available.
- If Ultradur B4300 G6 itself is not available. If we cannot source it, we tell you, then quote a matched alternative with a side-by-side comparison.
Send the grade and color code, your annual volume and ship-to location. A polymer chemist reviews every request before we quote. 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 November 2026.
Sources
- BASF Ultradur B 4300 G6 product information, 09/2026 (PDF, download.basf.com)
- BASF Ultradur B 4300 G6 HR processing data sheet, 09/2026 (PDF, download.basf.com)
- Celanese Celanex 3300 technical data sheet (SI), revised 2026-03-09 (PDF)
- Celanese Crastin SK605 NC010 technical data sheet (SI), revised 2026-08-12 (PDF)
- Celanese Chemille grade page for Crastin SK605 NC010
Common questions
What is Ultradur B4300 G6?
Ultradur B4300 G6 is BASF’s polybutylene terephthalate (PBT) with 30% glass fiber, an injection molding grade for technical parts in the automotive and electrical industries. BASF offers it in natural and black, and the sheet writes it as Ultradur B 4300 G6.
What is the density of Ultradur B4300 G6?
1,530 kg/m³ (1.53 g/cm³, ISO 1183). The hydrolysis-resistant B4300 G6 HR lists 1,510 kg/m³.
What is the melt flow of Ultradur B4300 G6?
MVR 11 cm³/10 min at 250°C / 2.16 kg (ISO 1133). BASF does not list an MFR in g/10 min on this sheet. Typical value; confirm on the current producer data sheet.
What is the heat deflection temperature of Ultradur B4300 G6?
205°C / 401°F at 1.8 MPa and 220°C at 0.45 MPa (ISO 75). The melting point is 223°C, and BASF lists a short-cycle maximum service temperature of 210°C.
What is the UL 94 rating of Ultradur B4300 G6?
HB at 0.75 mm and 3 mm, with a yellow card available. It is not a flame retardant grade; if your part needs V-0, you need a different PBT and a new approval.
How do you process Ultradur B4300 G6?
BASF lists a melt temperature of 250–275°C, a mold temperature of 60–100°C and less than 0.04% moisture at processing, with pre-drying as the rule. The product information gives no drying temperature, so ask BASF or follow its processing guide.
What is equivalent to Ultradur B4300 G6?
No grade is a drop-in replacement. Grades to ask about include Celanese’s Celanex 3300 (MVR 13 at the same condition, density 1.53, HDT 205°C) and Crastin SK605 NC010 (MVR 7, density 1.53, HDT 205°C). Compare data sheets, run a trial and get approval if your part names Ultradur B4300 G6.
Can ResinBridge quote Ultradur B4300 G6?
Yes. Send the grade, color code and volume. A polymer chemist reviews every request. We quote Ultradur B4300 G6 where our supply partners can source it, or a matched alternative, and say which one. Orders start at one gaylord; U.S. and Canada only.
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What to send for an accurate quote
- The grade name, from any supplier, or a data sheet
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- Fill type and percentage, if any
- Melt flow, if you know it
- Quantity for this order and what you use in a year
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