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| HS Code | 312865 |
| Product Name | Pentaerythritol |
| Chemical Formula | C5H12O4 |
| Iupac Name | 2,2-Bis(hydroxymethyl)-1,3-propanediol |
| Cas Registry Number | 115-77-5 |
| Molecular Weight | 136.15 g/mol |
| Appearance | White crystalline powder |
| Odor | Odorless |
| Density | 1.396 g/cm3 at 20°C |
| Melting Point | 260.5°C |
| Boiling Point | 276°C |
| Water Solubility | Approximately 5.5 g/100 mL at 25°C |
| Vapor Pressure | Negligible at room temperature |
As an accredited Pentaerythritol factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Pentaerythritol is supplied in 25 kg multi-layer paper bags with an inner plastic lining for moisture protection. |
| Container Loading (20′ FCL) | Pentaerythritol loaded in 20′ FCL as palletized, packed in plastic-lined bags, stowed dry, secured to prevent shifting. |
| Shipping | Pentaerythritol is a non-hazardous, crystalline solid typically shipped in multi-layer paper bags or FIBCs. Keep dry and away from ignition sources, as fine dust may form explosive mixtures. Store in ventilated containers, protected from moisture. No special transport classification applies under standard conditions. |
| Storage | Pentaerythritol should be stored in a cool, dry, well-ventilated area, away from heat, open flames, and ignition sources. Keep containers tightly closed when not in use. Protect from moisture and avoid dust accumulation. Store separately from strong oxidizers and incompatible materials. Use appropriate bonding and grounding during handling to prevent static discharge. |
| Shelf Life | Pentaerythritol has a long shelf life if stored in a cool, dry, well-ventilated area away from oxidizers. |
In long-oil alkyd resin production, pentaerythritol is introduced at polyol contents between 8 wt% and 18 wt% of reactor charge to exploit its four primary hydroxyl groups for branch-point density in tall oil, soybean, and linseed fatty acid systems. A 15,000-litre stainless steel alkyd reactor fitted with an anchor agitator, a decanter, a xylene-filled azeotropic separator, and a thermal oil heating/cooling jacket is used for the alcoholysis stage at 238°C to 247°C after the pentaerythritol is dispersed in the pre-heated oil. Calcium hydroxide at 0.03 wt% to 0.05 wt% based on oil weight is charged as the alcoholysis catalyst. The alcoholysis endpoint is checked by methanol solubility of a 1:3 resin-methanol mixture; incomplete alcoholysis leaves unreacted pentaerythritol granules that later form highly insoluble tetraester microgels. Phthalic anhydride is then added with the reactor held at 220°C to 235°C, water of esterification is removed by xylene azeotrope, and the acid value is driven to 8 mg KOH/g to 12 mg KOH/g as determined by ISO 3682; viscosity at 60% non-volatile in xylene is adjusted to 3,000 mPa·s to 6,000 mPa·s as determined by ISO 3219. The resulting resin, when formulated with cobalt/zirconium driers, exhibits hard dry time measured per ASTM D1640 at 6 h to 8 h under 23°C and 50% RH, with gloss retention after 500 h QUV exposure measured by ASTM D523. A critical process boundary is the gel point: if acid value falls below 6 mg KOH/g during stripping, the high pentaerythritol functionality may increase molecular weight to the point of irreversible gelation in less than 10 minutes. Conversely, if alcoholysis temperature exceeds 250°C, pentaerythritol sublimes at the cool top head and can block the vapour line to the decanter, creating back-pressure and batch-to-batch cycle time variation.
Gum rosin with an initial acid number of 165 mg KOH/g to 172 mg KOH/g per ASTM D465-15 is charged with pentaerythritol at a stoichiometric ratio calculated from the rosin acid equivalent weight, typically 0.92 to 1.05 equivalents of rosin acid per equivalent of hydroxyl. The reaction is carried out in a fixed stainless steel esterifier equipped with a bottom nitrogen sparge ring at 2 m³/h to 3 m³/h and a packed column to return entrained rosin droplets. The melt temperature is raised from 180°C to 270°C over 4 h and held at 270°C to 280°C until the acid number drops below 15 mg KOH/g and the ring-and-ball softening point reaches 95°C to 105°C per ASTM E28-18. Above 285°C, disproportionation of abietic acid raises Gardner colour above 7 per ASTM D1544-04 and generates low-molecular-weight neutrals that soften the finished tackifier. The use of a thin-film evaporator at 245°C to 250°C with a jacket vacuum of 5 kPa to 10 kPa strips unreacted rosin and neutral oil from the ester, concentrating the pentaerythritol rosinate to 98 wt% ester content. In hot-melt pressure-sensitive adhesives, the rosinate is compounded with styrene-isoprene-styrene block copolymers and naphthenic process oil at 35 wt% to 45 wt% tackifier loading, and loop tack is evaluated by ASTM D6195-03(2022). A limitation is that excess pentaerythritol pushes the softening point above 115°C and reduces compatibility with aliphatic process oil, while incomplete esterification above acid number 20 mg KOH/g increases hygroscopicity and reduces humid-ageing adhesion.
The carbon skeleton in acrylic intumescent basecoats is derived from pentaerythritol, whose hydroxymethyl groups dehydrate rapidly when the acid source, ammonium polyphosphate, releases phosphoric and polyphosphoric acids above 210°C. In intumescent basecoats, pentaerythritol is dispersed at 15 wt% to 30 wt% of total dry film solids, with ammonium polyphosphate at 25 wt% to 35 wt% and melamine at 10 wt% to 15 wt%; the widely cited APP:PER:MEL mass ratio of 3:1:1 provides a starting formulation, but commercial systems are adjusted for char strength with epoxy-acrylic hybrid binders and mineral fibre reinforcement at 2 wt% to 5 wt%. High-speed dispersion at 15 m/s to 20 m/s tip speed under jacket cooling below 45°C prevents dissolution of pentaerythritol into water during waterborne latex grind and preserves particle size. Fire resistance of the applied system is assessed under EN 13381-8 or ASTM E119 by measuring the time for the protected steel substrate to reach the limiting temperature; pentaerythritol-based intumescents usually achieve 45 min to 120 min ratings on I-section steel at dry film thicknesses from 0.8 mm to 3.5 mm. The critical operational boundary is water immersion: pentaerythritol has significant cold-water solubility, so an unsealed intumescent basecoat loses char-forming capacity after exterior weathering, and a two-component polyurethane topcoat with 50 µm to 100 µm dry film thickness is specified for exterior structural steel. Published expansion-ratio data for specific commercial formulations is limited, but cone calorimeter testing under ISO 5660-1 shows that char expansion and peak heat release rate are highly sensitive to pentaerythritol particle size distribution, with sieve cuts above 100 µm producing non-uniform intumescence and lower char strength.
Direct esterification of pentaerythritol with glacial acrylic acid in a glass-lined or stainless steel reactor produces a mixed pentaerythritol triacrylate/tetraacrylate product with average acrylate functionality near 3.3 to 3.6. Toluene or cyclohexane is used as the azeotropic entrainer at 80°C to 110°C; p-toluenesulfonic acid at 0.5 wt% to 1.5 wt% on acrylic acid catalyses the reaction, and methyl ether of hydroquinone at 50 ppm to 200 ppm based on the final product inhibits radical polymerisation. Product work-up includes caustic neutralisation of the catalyst, vacuum stripping at 60°C to 70°C under 10 kPa to 20 kPa, and filtration to yield a liquid ester with viscosity 600 mPa·s to 1,200 mPa·s at 25°C per ISO 3219 and acid number below 5 mg KOH/g. In ultraviolet-curable clearcoats, pentaerythritol acrylate is blended at 20 wt% to 40 wt% with aliphatic urethane acrylate and reactive diluents such as hexanediol diacrylate to reduce applied viscosity; photopolymerisation is initiated by 2 wt% to 4 wt% of bis-acylphosphine oxide or alpha-hydroxy ketone under a mercury fusion lamp with 120 W/cm irradiance and 400 mJ/cm² to 900 mJ/cm² UVA dose. Cure is monitored by ASTM D5402-19 methyl ethyl ketone double rubs, with 50 to 100 rubs expected for a fully crosslinked film. The high functionality causes surface tack from oxygen inhibition unless the cure atmosphere contains less than 500 ppm residual oxygen or the formulation includes an amine synergist; shrinkage can exceed 8% linear, and thin films on polycarbonate require an adhesion-promoting primer because crosslinked pentaerythritol acrylate films show brittle failure in ASTM D3359-23 cross-cut testing after thermal cycling at -20°C to 70°C.
For aviation gas-turbine lubricating oils, pentaerythritol is esterified with saturated C5–C10 fatty acids to produce a neopolyol ester basestock whose quaternary carbon centre eliminates beta-hydrogen abstraction, giving oxidative stability in high-temperature service. The esterification is run in a stainless steel reactor under nitrogen with 1.05 to 1.15 molar equivalents of acid per hydroxyl group at 220°C to 240°C, followed by removal of excess acid in a short-path thin-film evaporator at 250°C and 5 Pa to 20 Pa. The finished basestock is filtered with activated alumina or clay to remove trace metal soaps and reduce total acid number below 0.05 mg KOH/g per ASTM D974-22. Kinematic viscosity at 100°C is controlled to 4.9 mm²/s to 5.5 mm²/s per ASTM D445-21, and the pour point is measured below −40°C per ASTM D97-17 when branched acids such as 2-ethylhexanoic acid are part of the acid mix. In aviation turbine oil applications, the pentaerythritol ester basestock must remain hydrolytically stable; plant handling should keep dissolved water below 50 ppm because water can cleave ester linkages and raise TAN above specification limits. High-temperature oxidation tests indicated in SAE AS5780 and MIL-PRF-23699 require cleanliness ratings and deposit control on hot surfaces at 204°C to 274°C; lubricant formulations based on pentaerythritol esters are compounded with phenyl-alpha-naphthylamine and phosphate antiwear additives at levels below 2 wt%. The main processing bottleneck is the high melting point and dusting tendency of pentaerythritol feed; loss-in-weight feeding into the esterifier must be sealed to avoid powder carryover into the vacuum system, which raises maintenance intervals on the reactor condenser and can reduce batch consistency.
In rigid and flexible PVC, pentaerythritol is used as a secondary polyol co-stabiliser in calcium-zinc one-pack systems, typically at 0.1 phr to 0.5 phr. The mechanism is coordination of zinc chloride released during the early stages of PVC dehydrochlorination; pentaerythritol hydroxyl groups occupy zinc coordination sites and delay the catalytic zip elimination that causes sudden colour shift. Thermal stability is measured by the Congo red method at 180°C to 200°C per ISO 182-1, with longer induction times in Ca-Zn formulations containing pentaerythritol compared with neat zinc stearate controls. Processing is restricted to twin-screw extrusion barrel temperatures below 210°C because higher temperatures can lead to plate-out of unreacted pentaerythritol on calibrator surfaces if the dry blend contains more than 0.3 phr free polyol. The powder is hygroscopic and requires pre-drying to 110°C for 2 h when storage relative humidity exceeds 60%; otherwise hydrolysis in the extruder reduces the effectiveness of the calcium-zinc primary stabiliser. Published comparative data for pentaerythritol versus trimethylolpropane in the same Ca-Zn formulation is limited, but laboratory Congo red screening is the established method for dosage optimisation.
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Pentaerythritol, C(CH2OH)4, CAS 115-77-5, is a tetrafunctional primary alcohol produced by base-catalyzed aldol condensation of acetaldehyde and formaldehyde followed by crossed Cannizzaro disproportionation. The commercial product is a white crystalline powder with a theoretical hydroxyl number of 1648.4 mg KOH/g, a molecular weight of 136.15 g/mol, and a density of 1.396 g/cm³ at 25 °C. The melting range is commonly 258–262 °C, and solubility in water is approximately 7 g/100 mL at 25 °C; solubility in nonpolar solvents is negligible. Commercial grades are differentiated by mono-pentaerythritol content: technical grade is commonly specified at 98.0% minimum, refined grade at 99.0% minimum, and nitration grade above 99.5% with low ash and aldehyde limits. Typical designations include PE-98 for technical grade, PE-99 for refined grade, and PE-N for nitration grade, although manufacturer prefixes are not globally standardized. Residual dipentaerythritol, CAS 126-58-9, in technical grades generally ranges from 1.0% to 8.0% depending on reactor residence time and the formaldehyde-to-acetaldehyde ratio; dipentaerythritol raises average hydroxyl functionality and melt viscosity but can reduce solubility in nonpolar solvents. Manufacture is completed by crystallization, washing, and drying to remove sodium formate coproduct; residual sodium is monitored because alkali metal contamination above 5 ppm can poison esterification catalysts in downstream resin production.
| Parameter | Typical range or limit | Test method |
|---|---|---|
| Mono-pentaerythritol content | 98.0–99.5% | GC after trimethylsilylation |
| Hydroxyl number | 1645–1655 mg KOH/g | ASTM E222 |
| Moisture | ≤0.20% | ASTM E203 |
| Ash | ≤0.01% | ASTM D482 |
| Melting point | 258–262 °C | Capillary method |
| Color, APHA | ≤20 | ASTM D1209 |
The powder is commonly packaged in 25 kg multiwall paper bags or 500 kg flexible intermediate bulk containers. Compacted bulk density typically ranges from 0.50 g/cm³ to 0.70 g/cm³, and the angle of repose frequently exceeds 45°; hopper discharge therefore requires bin vibrators or fluidizing pads. Pentaerythritol powder must be kept below 60% relative humidity because the crystalline surface adsorbs moisture, leading to agglomeration, bridging in hoppers, and gravimetric feeder variability. Pre-drying at 60–80 °C for 2–4 h in a fluid-bed dryer is applied before charging to anhydrous esterification reactors when the moisture specification exceeds 0.10%. The product is combustible as a dust; conveying lines should be grounded and inerted to reduce the ignition hazard described in NFPA 77. Thermogravimetric analysis under nitrogen shows 5% mass loss near 280 °C; bulk storage above 200 °C is therefore avoided. Pentaerythritol is incompatible with strong oxidizers, mineral acids, and amine-based additives; the combination with amines can produce exothermic side reactions and discoloration in resin systems.
Quality control for pentaerythritol relies on chromatographic purity, hydroxyl number, moisture, and color. Gas chromatography after trimethylsilylation quantifies mono-pentaerythritol and dipentaerythritol simultaneously; the method is preferred over wet chemical methods because it resolves the dimer and higher oligomers. High-purity grades are also tested for sulfated ash, carbonyl number, and iron content; iron is controlled below 5 ppm in some resin applications because iron accelerates color development during esterification. When the product is shipped in bulk, retained samples from each lot are stored for 24 months; the certificate of analysis includes the lot number, production date, and the specification values.
In alkyd resin manufacture, pentaerythritol is charged with soybean oil or tall oil fatty acid in a 6–10 m³ stainless steel reactor equipped with an anchor agitator, partial condenser, and xylene azeotropic decanter. Alcoholysis is carried out at 230–250 °C under inert gas until the methanol solubility endpoint or refractive index reaches the target. The tetrafunctionality of pentaerythritol permits a lower molar charge than glycerol at the same oil length; a 55% oil-length alkyd formulated with pentaerythritol develops higher crosslink density but also higher solution viscosity. At 70% solids in xylene, Brookfield viscosity at 25 °C measured per ASTM D2196 with spindle 4 at 20 rpm can exceed 3,000 mPa·s when conversion is pushed above 95%. The alcoholysis temperature window is critical: below 225 °C the reaction rate becomes uneconomical, while excursions above 260 °C by more than 5 °C increase Gardner color by 2–3 units per ASTM D1544 and reduce yield by 0.5–1.0%. Catalyst loadings of lithium hydroxide or dibutyltin oxide are typically 0.01–0.05 wt% of the oil charge. Batch-to-batch variation in mono-pentaerythritol content of ±0.5% shifts the final acid number by approximately 2–5 mg KOH/g under identical cook logs; the drift is corrected by reducing the phthalic anhydride charge rather than extending the cook, because extended cooking can raise color above 8 Gardner and increase the thixotropic index.
High mono-pentaerythritol content alone does not guarantee stable downstream processing. Residual formaldehyde and acetaldehyde from incomplete condensation can react with phthalic anhydride during alkyd synthesis to form colored byproducts; carbonyl number is therefore controlled, and nitration-grade pentaerythritol is commonly specified with aldehydes below 0.05%. Sulfated ash above 0.01% per ASTM D874 accelerates ester hydrolysis and lowers the electrical resistivity of insulating varnishes. When railcar quantities are unloaded into 50 m³ silos, median particle size can vary from 40 μm to 250 μm depending on the crystallization and milling campaign. This variation changes bulk density and can cause gravimetric feeder drift if the feeder calibration is not reset. Plant records indicate that fine fractions dissolve earlier in the alcoholysis reactor and can temporarily lower the batch temperature by 3–8 °C, delaying the methanol solubility endpoint; published data for the effect of particle size on alcoholysis induction time is limited. Nitration-grade material is also specified for low dipentaerythritol and low ash because these impurities can create byproducts in downstream nitration operations; suppliers ship the material with a certificate of analysis covering mono-pentaerythritol content, hydroxyl number, moisture, ash, and aldehyde content.
Pentaerythritol differs from glycerol by providing four primary hydroxyl groups rather than two primary and one secondary hydroxyl group. The primary hydroxyl groups of pentaerythritol react faster in esterification than the secondary hydroxyl of glycerol, and the neopentyl-like carbon skeleton reduces β-hydrogen elimination and improves thermohydrolytic stability. Compared with trimethylolpropane at the same hydroxyl excess, pentaerythritol increases the gel fraction and glass transition temperature of the cured polyester or alkyd film but reduces impact flexibility; formulators often replace only 20–40% of trimethylolpropane hydroxyl equivalents to avoid embrittlement. Neopentyl glycol, with two hydroxyl groups, yields flexible but lower crosslink density systems. Dipentaerythritol, the main dimer impurity, has a functionality of 6 and a lower hydroxyl number but can introduce haze in solventborne alkyds. The following table summarizes the primary differences.
| Polyol | Functionality | Molecular weight | Hydroxyl number | Melting point | Typical resin effect |
|---|---|---|---|---|---|
| Glycerol | 3 | 92.09 g/mol | 1827 mg KOH/g | 17.8 °C | lower viscosity, softer films |
| Trimethylolpropane | 3 | 134.17 g/mol | 1255 mg KOH/g | 58–59 °C | hydrolytic stability, moderate hardness |
| Neopentyl glycol | 2 | 104.15 g/mol | 1077 mg KOH/g | 127 °C | flexibility, lower crosslink density |
| Pentaerythritol | 4 | 136.15 g/mol | 1648 mg KOH/g | 258–262 °C | high hardness, high viscosity, thermal stability |
| Dipentaerythritol | 6 | 254.28 g/mol | 1324 mg KOH/g | 215–225 °C | very high crosslink density, limited solubility |
Acrylation of pentaerythritol with acrylic acid under acid catalysis yields pentaerythritol triacrylate and pentaerythritol tetraacrylate, used in ultraviolet-curable coatings, inks, and adhesives. The tetrafunctionality raises the acrylate equivalent weight and crosslink density of the cured film. Because high-functionality acrylates shrink on polymerization, coating thickness above 50 μm can cause warpage on polycarbonate or ABS substrates unless adhesion promoters are used; surface cure inhibition by oxygen is more pronounced, so inert-gas blanketing or amine synergists are used in practice. The viscosity of commercial pentaerythritol tetraacrylate at 25 °C is commonly in the range 200–500 mPa·s when measured by cone-and-plate viscometer per ASTM D4287, depending on the diester/triester ratio. Published data for the elongation at break of these cured films below 25 μm is limited.
Pentaerythritol esters of carboxylic acids are also used as synthetic lubricants and refrigeration lubricants. The tetrafunctional structure yields higher viscosity index and lower pour point than simple mineral oil fractions. Esterification with C5–C9 acids is conducted in stainless steel reactors with vacuum stripping at 200–240 °C; the residual hydroxyl number is driven below 5 mg KOH/g to minimize moisture sensitivity and acid formation. The finished ester is filtered through 1 μm absolute filters and dried under vacuum at 100–120 °C. Performance testing includes kinematic viscosity at 40 °C and 100 °C per ASTM D445, total acid number per ASTM D664, and pour point per ASTM D97. Published data for long-term oxidation stability in refrigeration compressors is limited.
In rosin ester production, pentaerythritol is charged into 2,000 L stainless steel reactors at 270–290 °C under nitrogen sparge. The reaction is tracked by acid number per ISO 2114; commercial tackifiers are often specified at ≤15 mg KOH/g acid number and a ring-and-ball softening point of 95–105 °C per ASTM E28. Compared with glycerol rosin esters, pentaerythritol versions raise heat resistance and reduce cold flow in hot-melt adhesives, but hot-melt viscosity measured per ASTM D3236 at 180 °C can be 30–60% higher depending on the degree of esterification and residual rosin acid content. Published data for adhesion performance below 150 μm coat weight is limited; pilot coating trials are recommended before replacing glycerol rosin esters in a commercial hot-melt line.
For zinc/calcium PVC stabilizers, partial esters of pentaerythritol with C8–C18 fatty acids or maleic anhydride are used as intermediates. During rigid PVC extrusion on a 25:1 L/D counter-rotating twin-screw extruder at 160–190 °C, the residual hydroxyl groups of the partial ester can complex with zinc chloride generated during dehydrochlorination; thermal stability is commonly assessed by Congo red discoloration per ISO 182-1. Overdosing above 0.6 phr increases die lip plate-out because unreacted polyol migrates to the metal surface. The ester intermediate must be stored below 60% relative humidity and kept away from strong bases and amines, which accelerate ester hydrolysis and reduce stabilizer activity.
