| HS Code | 882583 |
| Productname | Formaldehyde |
| Synonyms | Methanal; Formalin; Methyl aldehyde; Oxomethane |
| Iupacname | Methanal |
| Casnumber | 50-00-0 |
| Ecnumber | 200-001-8 |
| Rtecsnumber | LP8925000 |
| Chemicalformula | CH2O |
| Molarmass | 30.026 g/mol |
| Appearance | Colorless gas |
| Odor | Pungent, irritating |
| Odorthreshold | 0.5–1.0 ppm |
| Density | 0.8153 g/cm3 at -20 °C (liquid) |
| Vapordensity | 1.03 (air = 1) |
| Meltingpoint | -92 °C |
| Boilingpoint | -19 °C |
| Solubility | Soluble in water, ethanol, ether, acetone, benzene |
| Vaporpressure | 3,890 mmHg at 25 °C |
| Autoignitiontemperature | 430 °C |
| Explosivelimits | 7–73% by volume in air |
| Logp | 0.35 |
| Ph | 2.8–4.0 (37% aqueous solution) |
| Unnumber | 2209 (formaldehyde solution, ≥25% formaldehyde) |
As an accredited Formaldehyde factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Formaldehyde supplied in 4 L amber glass bottles, sealed with leak-proof caps and hazard labels, packaged in UN-approved fiberboard boxes. |
| Container Loading (20′ FCL) | 20′ FCL formaldehyde solution, packed in UN-approved drums, labelled hazardous, and securely stowed/lashed for IMDG-compliant ocean transport. |
| Shipping | Formaldehyde is shipped as a hazardous material, typically UN 2209, Formaldehyde solution, Class 8 corrosive, Packing Group III. It requires UN-approved packaging, corrosive labels, placards, shipping papers, and trained handlers complying with DOT, IATA, or IMDG regulations. Flammable formulations may use UN 1198, Class 3. |
| Storage | Store formaldehyde in a cool, dry, well-ventilated, fire-resistant area away from heat, sparks, flames, and direct sunlight. Keep containers tightly closed, properly labeled, and upright; use secondary containment. Segregate from oxidizers, acids, bases, amines, and other incompatible materials. Maintain appropriate temperature to prevent polymerization; provide local exhaust and spill-control measures. Access restricted. Store only in approved areas equipped with eyewash and safety shower. |
| Shelf Life | Formaldehyde shelf life: about 1–2 years if kept tightly sealed, cool, dark; it may oxidize to formic acid and polymerize. |
Mole ratio control in urea-formaldehyde resin synthesis is the principal lever for reconciling internal bond strength with airborne formaldehyde emission from finished wood panels. Aqueous formaldehyde at 37–50 wt% is condensed with urea in a two-stage alkaline-to-acid cook, with the final F/U molar ratio held at 0.97–1.05 for low-emission grades and 1.05–1.15 for conventional E1 grade boards; the lower ratio shifts the oligomer distribution toward substituted urea and away from methylol and dimethylene ether species, but it also reduces hot tack and requires longer cure. In particleboard manufacture, the resin is metered at 6–10 wt% dry resin on dry wood, and ammonium sulfate hardener is added at 0.5–1.5 wt% on resin solids to force mat pH to 4.0–4.5 during pressing; industrial continuous presses are run at 165–185°C with a pressing factor of 6–12 s/mm, and the upper edge of that range is necessary when F/U falls below 1.00. The production bottleneck on low-F/U board lines is degassing at mat centre: residual water and formaldehyde vapour form internal steam pressure in boards thicker than 18 mm, causing blowout if press closing is too fast or mat moisture exceeds 9–10 wt%. Emission compliance for CE-marked panels is based on EN 13986 and chamber testing under EN 16516; for North American shipments, EPA TSCA Title VI and CARB Phase 2 limits are measured with ASTM E1333-14, with typical panel category limits spanning 0.05–0.13 ppm. Melamine is introduced after the UF condensation at 5–15% of total amine co-reactant mass to produce MUF resin; this adds triazine rings that improve hydrolysis resistance and reduce formaldehyde release but raises resin cost and shortens acid-hardener pot life to 2–4 h at 25°C. Downstream lines convert the resinated mat into finished products including EN 312 furniture-grade particleboard, EN 622 MDF for millwork, and melamine-faced board for component furniture.
Commercial liquid resole binders for engineered wood and laminate are prepared with a formaldehyde-to-phenol molar ratio of 1.2–2.0 under sodium hydroxide catalysis, while novolac resins for abrasive and textile bonding use a molar ratio of 0.75–0.85 with oxalic or sulfuric acid; the resole route retains reactive methylol groups and therefore cures without hexamine, whereas novolac requires a separate methylene donor. On OSB strand lines, resole solids are applied at 2.5–4.0 wt% on dried wood strands, along with paraffin wax at 0.5–1.0 wt% to limit edge swell; the formed mat is densified at 190–215°C for 4–6 s/mm, with local mat temperature kept below 220°C to avoid excessive phenol vapour generation from uncured resin. Wet-bond performance of exterior-grade panels is specified by EN 314-2 Class 3, and structural classification of OSB follows EN 300; production failure in exterior plywood and OSB usually appears as low shear bond after 72-hour boil tests on boards from the mat edges, where resin distribution is most uneven. The same resole chemistry saturates decor paper for high-pressure laminates, with resin-impregnated kraft processed through a B-stage oven at 120–160°C to a controlled volatile content of 6–8% before pressing between polished plates at 140–160°C and 7–10 MPa; high-pressure laminate classification follows EN 438. Terminal product types are exterior OSB sheathing, film-faced plywood for concrete formwork, and high-pressure decorative laminate sheets for countertops and laboratory work surfaces.
Thermal degradation of polyoxymethylene above 230°C is the main processing constraint in formaldehyde-derived acetal resins; the polymer unzips from the chain end to release formaldehyde, so stabilizer addition, vacuum venting, and melt temperature control are not optional. Aqueous formaldehyde feedstock at 50 wt% is first cyclicized to trioxane over sulfuric acid at 95–100°C, and copolymerization with 2–4 wt% 1,3-dioxolane comonomer disrupts crystallinity and provides chain-end stability; unreacted trioxane is stripped under vacuum and the finished resin is melt compounded on a twin-screw extruder with L/D 40 and vent pressure of -0.08 MPa. The resulting POM copolymer is injection molded at a barrel melt temperature of 190–215°C and mold temperature of 80–110°C; cycle time is constrained by cooling of the high-crystallinity melt, and residence time beyond 15 min at melt temperature raises formaldehyde outgassing, causing silver streaks and brittle near-gate sections. Melt volume-flow rate is determined under ISO 1133-1:2022 at 190°C and 2.16 kg, tensile properties under ISO 527-2:2012, and designation under ISO 9988-1:2004; a standard injection grade typically reports tensile modulus of 2800–3100 MPa and MVR of 7–9 cm³/10 min. Terminal products are precision gears, fuel-system clips, aerosol valve components, and conveyor chain links where creep resistance and low moisture uptake are specified.
Aniline condensation with aqueous formaldehyde in hydrochloric acid produces methylenedianiline and its higher oligomers, with the stoichiometric demand of 2 mol aniline per 1 mol formaldehyde; industrial reactors maintain an excess aniline ratio near 2.4–3.0 mol per mole formaldehyde to reduce high-ring polymethylene polyaniline content and to control the isomer distribution of the MDA. The downstream phosgenated stream is sold as polymeric MDI with NCO content of 30.5–32.0% and viscosity of 200–350 mPa·s at 25°C, with isocyanate content measured by ISO 14896:2009 and viscosity by ISO 3219:1993; monomeric diphenylmethane diisocyanate is recovered by vacuum crystallization for prepolymer and elastomer grades. Because the resulting diisocyanate is moisture sensitive, storage and mixing are conducted under dry nitrogen at 20–25°C, and water content in polyol must be below 0.05 wt% to avoid carbon dioxide pinholes and viscosity rise. Regulatory compliance is governed by REACH Annex XVII Entry 74, which requires training for industrial users handling diisocyanates above 0.1% concentration by weight. In rigid polyurethane foam production, the PMDI stream is metered against a formulated polyether polyol at an isocyanate index of 105–120, with pentane or hydrofluorocarbon blowing agents; the expanding mixture is laid down on a continuous sandwich panel line to form EN 13165 PUR or PIR insulation board. Terminal product types include closed-cell insulation panels for flat roofs, automotive headliners, and cavity-wall injection foam.
In the acetylene-based Reppe route to butanediol, methanol-stabilised aqueous formaldehyde at 37 wt% is reacted with acetylene over a supported copper-bismuth catalyst in a slurry bed at 90–100°C and 1–2 bar back pressure; the molar feed ratio is held at 2.05–2.15 formaldehyde per acetylene to account for minor Cannizzaro losses, and formaldehyde conversion before the hydrogenation section must remain above 99.5% because residual aldehyde contributes to nickel catalyst fouling and shortened catalyst cycle. The resulting 35–40 wt% butynediol solution is hydrogenated in a fixed-bed unit to crude butanediol, then distilled to 99.5 wt% minimum purity. The production limitation in this sequence is the acetylene handling system: because acetylene is thermodynamically unstable above 2 bar in the absence of dilution, the entire butynediol reactor train operates under strict flow and pressure interlocks. For downstream polyester synthesis, the butanediol is esterified with terephthalic acid to produce polybutylene terephthalate; PBT molding compounds are characterized by melt volume-flow rate under ISO 1133-1:2022 and tensile properties under ISO 527-2:2012. Additional terminal products include tetrahydrofuran and PTMEG for spandex and cast elastomer prepolymers, as well as thermoplastic polyether ester elastomers for automotive boots and connectors.
Hexamethylenetetramine is crystallized from the reaction of ammonia and aqueous formaldehyde at a molar ratio of 4:6 ammonia to formaldehyde; the synthesis is run at 30–50°C and pH 7–8, with cooling to 20°C to precipitate the solid from mother liquor. The material functions as a methylene donor in novolac phenolic molding compounds at 8–14 phr; below 8 phr the crosslink density is too low for dimensional stability under heat, and above 14 phr the cured part releases ammonia and formaldehyde during compression molding, causing porosity and die staining. Molding is performed on compression or transfer presses at 150–175°C and 15–40 MPa; the cure time for a standard 3 mm tensile slab is 60–90 s, and hot-runner injection molding of phenolic is avoided because the material thermosets in the barrel. Specification of the molding compound follows ISO 14526-2:1999 for phenolic powder or granulate, and the cured article is tested for flexural strength under ISO 178:2019; standard filled grades typically deliver flexural strength of 80–110 MPa after post-bake. Terminal components are commutator rings in electric motors, automotive brake pistons, and pump impellers handling hot glycol–water mixtures.
Pentaerythritol production consumes 4 mol formaldehyde per 1 mol acetaldehyde under calcium hydroxide-catalyzed aldol conditions; the ratio of mono- to di-pentaerythritol is controlled by formaldehyde excess, reaction time, and caustic strength, and the crude reaction liquor is neutralized with formic or sulfuric acid before crystallization. For long-oil alkyd resins, technical-grade pentaerythritol is charged at 10–18 wt% of final resin solids; its tetrafunctionality raises branching and gloss retention but also makes the cook more prone to gelation, so the reactor is held at 240–250°C under xylene azeotrope until the acid number drops below 12 mg KOH/g. The alkyd is then reduced in white spirit and formulated into air-drying enamels; coating performance is evaluated under ISO 11998 for wet-scrub resistance and ISO 15184 for pencil hardness, while outdoor durability uses ISO 16474-2 weathering cycles. Terminal product types are architectural alkyd enamels, stoving enamels for metal furniture, and pentaerythritol ester base stocks for high-temperature lubricant applications.
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Formaldehyde (CAS 50-00-0, molecular weight 30.03 g/mol) is supplied in aqueous solution, solid depolymerising polymer, and concentrate forms. The dominant commercial product is methanol-stabilised formalin, typically containing 37.0–37.4 wt% formaldehyde and 10–12 wt% methanol, with the balance water. Paraformaldehyde, containing 91–93 wt% formaldehyde, is used where water must be limited. Urea-formaldehyde concentrate such as UFC 85 contains approximately 60 wt% formaldehyde, 25 wt% urea, and 15 wt% water. Although pure formaldehyde is a gas with a boiling point near -19.5 °C, the commercial product is handled as a liquid solution or a solid flake, prill, or granular material. Principal end uses include urea-formaldehyde, melamine-formaldehyde, and phenol-formaldehyde resins, hexamethylenetetramine, pentaerythritol, 1,4-butanediol via the Reppe process, dimethyloldihydroxyethyleneurea textile crosslinkers, and paper wet-strength resins. The product differs from glutaraldehyde and glyoxal in that formaldehyde is a monoaldehyde with lower molecular weight, higher aqueous solubility, and greater vapour-phase mobility from solution, which makes it a faster methylolation agent but also a more significant emission-control challenge.
The formalin assay is determined by sulfite titration according to ISO 2227:1972, while methanol is measured by ISO 2228:1972 or gas chromatography. Acidity, expressed as formic acid, is controlled under ASTM D2379, commonly below 0.05 wt%; iron is restricted to avoid resin discoloration, with supplier certificates frequently stating ≤0.5 mg/kg. The methanol stabiliser prevents precipitation of paraformaldehyde during storage at 15–25 °C; low-methanol grades require heated storage or circulation loops. pH is typically 3.0–4.5, reflecting residual formic acid. The product is a reducing agent and must be kept away from strong oxidisers, nitric acid, and peroxides. Containment in stainless steel or lined carbon steel is specified, while aluminium and unprotected carbon steel are avoided because of corrosion and hydrogen generation. REACH harmonised classification under Regulation (EC) No 1272/2008 includes Acute Tox. 3 H301/H311/H331, Skin Corr. 1B H314, Skin Sens. 1 H317, Muta. 2 H341, and Carc. 1B H350. These classifications drive closed transfer, ventilation, and exposure monitoring rather than product performance in resin syntheses.
Transfer systems for formalin are designed for closed-loop operation with nitrogen blanketing on storage tanks. Pumps with magnetic or double mechanical seals are preferred over packed pumps because formalin leakage forms white paraformaldehyde deposits at the stuffing box. Low-emission resin sites use vapour-phase scrubbers on tank vents and reactor condensers; water scrubbers recover 90–95% of vent formaldehyde, but actual recovery depends on gas flow and temperature. Workplace atmospheric monitoring is performed by NIOSH Method 2016 or equivalent HPLC analysis. The OSHA permissible exposure limit is 0.75 ppm as an 8-hour time-weighted average and 2 ppm as a short-term exposure limit. The NIOSH recommended exposure limit is 0.016 ppm as a time-weighted average and 0.1 ppm as a ceiling, while the ACGIH threshold limit value is 0.1 ppm as a ceiling. These values constrain tank-farm design and reactor condenser vents, particularly where low-methanol formalin is held in warm climates.
In urea-formaldehyde resin synthesis, the methylolation stage is operated at pH 7.5–8.5 and 70–80 °C; the condensation stage is then shifted to pH 4.5–5.5 and 80–95 °C until the desired Gardner-Holdt viscosity is reached. The formaldehyde-to-urea molar ratio is the main stoichiometric lever for particleboard binders, commonly between 1.1:1 and 1.3:1; reduction below this range lowers free formaldehyde but slows cure and can reduce internal bond strength unless press time is extended. Free formaldehyde in the liquid resin is measured by ISO 11402:2004 and is typically held below 0.5 wt% for low-emission board grades. Batch reactors require external jacket cooling and pH-controlled metering of 50 wt% sodium hydroxide or 20 wt% formic acid; overshooting the alkaline methylolation stage beyond 85 °C increases trimethylolurea and creates higher resin viscosity at the condensation endpoint. In continuous particleboard lines, the resin is blended with wax emulsion, urea scavenger, and catalyst in high-shear mixers before forming and pressing at 180–220 °C; residence time and press factor are adjusted to the resin gel time and board thickness.
Urea-formaldehyde concentrate is produced by reacting formalin with urea under vacuum to reduce water load. The concentrated product contains approximately 60 wt% formaldehyde, 25 wt% urea, and 15 wt% water, and is shipped as a viscous liquid. It reduces freight cost and reactor heat load relative to 37% formalin, but its higher viscosity requires heated transfer lines and controlled metering. In hexamethylenetetramine synthesis, formalin is reacted with ammonia at 20–60 °C; the exothermic reaction forms crystalline hexamine, which is used as a novolac curing agent. For this route, residual methanol and formic acid affect mother-liquor recycling and crystal handling. The same formalin specification may therefore be inadequate across different downstream processes: amino resin synthesis is sensitive to acidity and iron, hexamine production to methanol and ammonia demand, and paraformaldehyde production to water content and inhibitor balance.
Paraformaldehyde containing 91–93 wt% formaldehyde replaces 37 wt% formalin where water must be limited. Replacing 100 kg of formaldehyde as formalin with 92 wt% paraformaldehyde reduces the water load from approximately 140 kg to below 10 kg, which shortens drying and raises throughput in resole and novolac kettles. Depolymerisation is carried out in phenol at 80–120 °C under acid or base catalysis; because dissolution and depolymerisation are rate-limiting, controlled addition and longer reaction times are required to avoid unreacted particles and batch-to-batch viscosity drift. The solid is handled with dust extraction and is incompatible with strong acids and oxidisers; concentrated sulfuric acid contact can generate heat and formaldehyde gas rapidly. In phenolic moulding compounds, low water content improves flow and dimensional stability after transfer press moulding, but the operator must verify that paraformaldehyde-grade purity and particle size distribution match the mixing intensity of the specific twin-screw or kneader line. Published data for the effect of particle size on depolymerisation rate in phenolic resole kettles is limited; validation on the actual reaction system is therefore required before grade substitution.
Textile easy-care finishing with dimethyloldihydroxyethyleneurea consumes formalin as the methylolation agent. Pad-dry-cure processing on a stenter frame at 150–170 °C crosslinks cellulosic fibre; residual free and released formaldehyde are determined on finished fabric by ISO 14184-1:2011 and ISO 14184-2:2011. Regulatory limits of 75 mg/kg for adult clothing and 20 mg/kg for infant clothing under Japanese Law 112 require tight control of formalin assay, methanol, and acidity because impurity excursions shift reaction selectivity and increase after-wash burden. In this application, formaldehyde differs from glyoxal-based or polycarboxylic acid alternatives by yielding higher durable-press ratings and lower raw-material cost, but at the expense of higher potential aldehyde release unless catalysts and scavengers are optimised. The product specification therefore includes not only total formaldehyde but also acidity and methanol because both affect pad-bath pH drift and fabric yellowing.
Formaldehyde is selected over glutaraldehyde when reaction rate and raw-material cost outweigh the need for low volatility. Formaldehyde has a molecular weight of 30.03 g/mol, whereas glutaraldehyde is 100.12 g/mol; the monoaldehyde diffuses rapidly into lignocellulosic or protein substrates but is also emitted from the bath at ambient temperature, so local exhaust ventilation and air monitoring to the OSHA PEL of 0.75 ppm TWA and 2 ppm STEL are required. Glutaraldehyde and glyoxal possess two aldehyde functions, which produces more stable but slower crosslinks and lower formaldehyde release. In wood modification and paper impregnation, formaldehyde provides rapid resin penetration and cure at lower temperatures, while glutaraldehyde is reserved for applications where residual vapour is unacceptable. The choice is not based on single-property superiority but on emission-control cost, crosslink density, and substrate compatibility; amine-containing substrates can react prematurely with formaldehyde and must be evaluated for exothermic condensation during impregnation. Product substitution therefore requires a process-level comparison of ventilation capacity, dwell time, and end-use emission specifications rather than a simple aldehyde reactivity ranking.
Emission compliance for particleboard and MDF is evaluated by EN 717-1:2004 chamber testing, with the E1 limit usually quoted as 0.1 ppm in chamber air, or by ASTM E1333 large-chamber testing under U.S. EPA TSCA Title VI. The formalin fed to amino resin synthesis for these panels cannot be treated as a commodity without specification. Methanol content shifts resin compatibility with urea scavenger; acidity variation alters condensation endpoint and free formaldehyde measured by ISO 11402. Producers of low-emission boards often specify formalin with lower acidity and lower iron than standard 37/10 material to avoid board colour changes and to maintain predictable cure rates across continuous presses. Closed transfer and vapour recovery are specified because formaldehyde vapour from storage vents and reactor condensers contributes to workplace exposure and to emission inventories under REACH and local air permits. In this context, formaldehyde-based aminoplast binders are compared with polymeric diphenylmethane diisocyanate binders mainly on emission profile, press cure speed, and moisture resistance, not on raw aldehyde concentration alone.
Free formaldehyde in urea-formaldehyde and melamine-formaldehyde resins is determined by ISO 11402:2004 using hydroxylamine hydrochloride titration or by High Performance Liquid Chromatography after derivatisation. The method must be selected to avoid interferences from urea, melamine, and methanol. Resin samples are cooled to 20–25 °C before analysis because residual condensation continues in hot samples and biases results. In process control, a target of ≤0.5 wt% free formaldehyde is common for low-emission liquid urea-formaldehyde resins, while standard grades may run 0.5–1.5 wt%; the exact specification is tied to downstream press temperature, board thickness, and scavenger addition. The analytical value is not a direct predictor of panel emissions; chamber testing such as EN 717-1 or ASTM E1333 is required because hydrolysis of the cured resin under heat and moisture releases additional formaldehyde. This distinction is critical when comparing formaldehyde-containing aminoplasts against alternative binders: the product may meet resin free-formaldehyde limits while the finished board fails emission testing if cure is incomplete or moisture resistance is insufficient.
