| HS Code | 423738 |
| Product Name | N-Butyl Cyanoacrylate |
| Common Name | n-Butyl 2-cyanoacrylate |
| Synonyms | NBCA; Enbucrilate; Butyl cyanoacrylate; Butyl 2-cyanoacrylate |
| Cas Number | 6606-65-1 |
| Iupac Name | Butyl 2-cyanoprop-2-enoate |
| Molecular Formula | C8H11NO2 |
| Molecular Weight | 153.18 g/mol |
| Physical State | Liquid |
| Appearance | Colorless to pale yellow |
| Odor | Sharp, characteristic, irritating |
| Density | 0.989 g/cm3 at 25 °C |
| Boiling Point | 83 °C at 0.3 mmHg |
| Flash Point | 85 °C |
| Refractive Index | 1.442 at 20 °C |
| Viscosity | 2-5 mPa·s |
| Solubility | Soluble in acetone, ethanol, chloroform; reacts with water |
| Polymerization Behavior | Anionic polymerization initiated by moisture |
| Reactivity | Polymerizes rapidly in contact with water, alcohols, amines, or bases |
| Storage Conditions | Keep refrigerated, dry, and away from moisture |
| Primary Use | Medical tissue adhesive and embolic agent; industrial cyanoacrylate adhesive |
| Skin Contact Hazard | Rapidly bonds skin; may cause irritation |
| Eye Contact Hazard | May cause eye irritation |
| Inhalation Hazard | Vapor may irritate respiratory tract |
| Ingestion Hazard | May be harmful if swallowed |
As an accredited N-Butyl Cyanoacrylate factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | N-Butyl Cyanoacrylate is supplied in 50 mL amber glass bottles with polyethylene-lined screw caps, individually sealed in moisture-resistant foil pouches. |
| Container Loading (20′ FCL) | N-Butyl Cyanoacrylate is palletized, shrink-wrapped, labeled, and loaded into a 20-foot FCL container with documentation for secure sea transport. |
| Shipping | N-Butyl Cyanoacrylate, stabilized, is shipped in sealed, moisture-resistant containers with polymerization inhibitor. For air transport, it may be classified UN 3334, Aviation Regulated Liquid, n.o.s. (N-Butyl Cyanoacrylate), Class 9, PG III. Ground/surface may be non-regulated. Store cool, dry, upright, and follow DOT/IATA/IMDG rules. |
| Storage | Store N-Butyl Cyanoacrylate in a cool, dry, well-ventilated area away from heat, sparks, open flames, moisture, amines, bases, and alcohols. Keep containers tightly closed, preferably refrigerated at 2–8°C and protected from light. Use original labeled containers with compatible seals. Avoid water contact to prevent polymerization. Store separately from incompatible materials. Maintain spill containment and follow local regulations and the SDS. |
| Shelf Life | N-Butyl cyanoacrylate shelf life is typically 12–24 months when sealed, refrigerated (2–8°C), dry, and protected from light and moisture. |
During embolization of high-flow cerebral arteriovenous malformations, delivery of n-butyl cyanoacrylate (NBCA) is governed by monomer-to-ethiodized oil ratio, microcatheter dead-volume management, and the ionic content of the flush solution. The monomer is a water-white liquid with a polymerisation onset that accelerates sharply in the presence of blood anions; because of this, the delivery microcatheter is purged with 5% w/v dextrose injection before the monomer is aspirated. The ethiodized oil phase, commonly Lipiodol Ultra Fluid, supplies radio-opacity and slows polymerisation, allowing the operator to track the fill under fluoroscopy. Residual saline, blood, or contrast medium in the hub, luer fitting, or catheter lumen initiates polymerisation within 1–2 s, increasing injection pressure and blocking the fluid path. The ratio of NBCA to ethiodized oil controls polymerisation time and distal vessel penetration. In high-flow shunts, a low-oil mixture is used to reduce run-off into the venous outflow; in slow-flow capillary beds, a higher oil fraction delays solidification to permit transcatheter deposition into the selected segment. The table below summarizes representative working ranges used in interventional neuroradiology and visceral embolization procedures, derived from manufacturer instructions for ethiodized oil combination use.
| NBCA:ethiodized oil ratio | Approximate polymerisation time in blood | Typical vascular target |
|---|---|---|
| 1:1 | 1–2 s | High-flow arteriovenous malformations |
| 1:2 | 2–4 s | Medium-flow shunts and varices |
| 1:3–1:4 | 4–8 s | Low-flow capillary beds and distal occlusion |
Polymerisation is exothermic; the temperature rise at the catheter tip is lower for NBCA than for ethyl cyanoacrylate because of the lower monomer concentration when ethiodized oil is added and the reduced reactivity of the butyl ester. In gastric or duodenal varix embolization, the same ratio logic applies, but flow stagnation and varix diameter alter the practical window. The injection is stopped under fluoroscopy when the radiopaque cast reaches the predetermined landmark, and the microcatheter is withdrawn while maintaining light aspiration to avoid leaving solidified polymer on the tip. The cured cast is non-degradable and remains in the target vessel, while the surrounding tissue response is evaluated under ISO 10993-4:2017 for blood-contacting devices and ISO 10993-5:2009 for cytotoxicity. The principal operational boundary is the short working time: any delay between mixing and injection, or any interruption of the fluoroscopic feed, can lead to premature hardening inside the catheter and termination of the procedure.
Topical application of n-butyl cyanoacrylate follows a moisture-initiated anionic polymerisation sequence in which the wound surface provides the initiating hydroxyl species and the monomer wets the epidermal layer before chain propagation forms a flexible film. Compared with ethyl cyanoacrylate, the butyl ester produces a lower exotherm and a more compliant film, which reduces the sensation of heat on application and lowers the risk of cracking over mobile skin areas. The adhesive is applied in a single thin pass with the wound edges approximated manually; a second pass is permitted only after the first has cured to avoid excessive film thickness. Lap-shear testing of polymerised films on skin substrates is performed under ASTM F2255-05, while cytotoxicity and irritation endpoints for medical device registration are assessed under ISO 10993-5:2009 and ISO 10993-10:2010. Film strength is dependent on the moisture content of the skin; an overwet surface leads to rapid superficial polymerisation that prevents adhesion, whereas an excessively dry surface produces a slow cure and a brittle edge. On mobile regions such as the elbow or knee, the film is applied only after the limb is held in flexion, because polymerisation begins within 5–10 s and fixture is complete within 30–60 s at 20–25°C and 40–60% RH. The principal operational limitation is low peel resistance on high-tension wounds; n-butyl cyanoacrylate is therefore indicated for approximated, low-tension incisions and lacerations, not for gaping wounds under muscle load. Sterile single-use applicators are filled on automated filling lines where viscosity is held within a narrow band because monomer uptake into the applicator tip causes premature skin formation at the orifice. The filled applicator is sealed in a moisture-barrier pouch with a desiccant; if the pouch seal is compromised, the shelf life falls below the labelled 24-month window.
In veterinary practice, n-butyl cyanoacrylate is used for skin closure after surgical procedures, ear tip repair, reptile shell and wound coverage, and as an adjunct to hoof crack stabilisation in equine farriery. The bond is formed after the substrate is cleaned and lightly moistened; blood contamination is removed because haemoglobin and serum proteins accelerate polymerisation into a fragile, opaque film rather than a load-bearing interface. In canine flank closures, the monomer is applied to an approximated wound edge with a microswab or a 0.2–0.3 mL single-dose ampule, producing a film that sloughs with normal epidermal turnover. In equine hoof repair, the liquid is used to seal cracks after debridement of the horn wall; the surface must be free of moisture and oil, and the cyanoacrylate is followed by polymethyl methacrylate or acrylic repair material because the cyanoacrylate film alone lacks the flexural modulus required for weight-bearing hoof wall. Biocompatibility data for veterinary use are frequently extrapolated from ISO 10993-5:2009 and ISO 10993-10:2010, with additional local tolerance data generated under the device-specific veterinary protocol. A known failure mode is biofilm formation when the film is applied over contaminated or macerated skin; the resulting exudate accumulates beneath the polymer and separates the adhesive from the epithelium. Another limitation is the incompatibility with residual chlorhexidine gluconate from alcohol-based skin scrubs; the anionic residues can accelerate surface polymerisation before the monomer wets the tissue, reducing tack and producing a chalky interface.
Cosmetic eyelash extension and nail tip adhesion rely on n-butyl cyanoacrylate when the polymerised deposit must remain flexible after curing and the lower vapour pressure reduces bloom around the adhesive line. The adhesive is applied through a 0.5–1.0 mm dispensing orifice in volumes of 5–15 µL per lash fan, depending on fan width and extension weight. Ambient humidity exerts a dominant influence on cure: below 45% RH, the polymerisation rate slows and the lash bond remains tacky, while above 70% RH the surface skins before the extension is seated. The working time under controlled conditions of 20–25°C and 40–60% RH is typically 2–5 s, and final cure is reached within 24 h. For nail tip application, the monomer is applied to the pre-etched nail tip and pressed onto the nail plate for 10–20 s; the bond line must be free of cuticle oil, hand cream, or acetone residues. The cured film is resistant to soap and water but softens under prolonged acetone exposure. The low exotherm of the butyl homologue is relevant for periocular use; however, the formulation must still be assessed for stabiliser content and methacrylate impurities under ISO 10993-5:2009 if the product is placed on skin. Published data for this specific cosmetic configuration is limited; performance claims are typically evaluated by patch testing and repeated open application tests rather than a single ISO mechanical standard.
Bonding of plasticised poly(vinyl chloride), EPDM, SBR, and thermoplastic polyurethane extrusions with n-butyl cyanoacrylate is an industrial process in which surface preparation determines whether the cured joint meets the target peel strength without a primer. On as-moulded EPDM weatherstrip, the bond line is activated by plasma or corona discharge at a surface energy above 38 mN/m; without activation, failure occurs adhesively at the interface and lap-shear values measured under ASTM D1002-10 remain below 0.5 MPa. For plasticised PVC extrusions, the plasticizer migration rate controls long-term performance; low-molecular-weight phthalates migrate into the polymerised cyanoacrylate and reduce joint strength over 7–14 days, whereas medium-molecular-weight polymeric plasticizers produce less interfacial softening. Automated dispensing lines use a needle valve or piezoelectric jet; the fluid path is purged with dry air before shutdown because residual moisture in the actuator seals causes polymerisation at the needle seat. The fixture time at 22°C and 50% RH is typically 15–30 s for EPDM and 5–15 s for polyurethane; full handling strength is achieved in 2–4 h, but crosslinking continues for 24 h at 50% RH. Joint design must avoid continuous immersion in water above 60°C; the cured polymer loses strength through hydrolysis. In production, the primary bottleneck is the open-time window: if the parts are not fixtured within the working time, the resulting joint exhibits surface skinning and loses translucency. Adhesive viscosity is typically held between 2 and 100 mPa·s depending on the dispensing method, with low-viscosity grades specified for primed rubber-to-metal bonding and higher thixotropic grades specified for vertical joints. Peel testing follows ASTM D903-98(2017) or ISO 11339:2010 for flexible-to-flexible assemblies, and the acceptance criterion is typically a substrate-tearing failure rather than an adhesive failure mode.
In loudspeaker voice coil tack bonding and microspeaker surround adhesion, n-butyl cyanoacrylate is used in small dispense volumes where the lower vapour pressure reduces bloom on surrounding diaphragm surfaces and where the flexible butyl ester tail allows the bond line to follow surround excursion. The adhesive is deposited by a pneumatic dispenser at 0.2–0.5 MPa through a 25–33 gauge needle in volumes of 1–5 µL, positioned at the interface between the voice coil former and the cone or spider. The assembly line operates at 40–60% RH; if relative humidity falls below 30% RH, cure speed becomes insufficient and parts require additional exposure to a humidified chamber at 70–80% RH for 30–60 s. The bonded assembly is tested for adhesion after 24 h by a 90° peel pull on the voice coil joint, with visual confirmation that failure occurs within the paper or polyimide former rather than at the adhesive interface. The monomer is incompatible with polycarbonate reservoirs and should be stored in polyethylene or polypropylene packaging; uncured adhesive exposed to air forms a visible skin over 8–12 h in an open tank. Outgassing performance in sealed transducer modules is assessed under ASTM E595-15, with acceptance limits defined by the consumer electronics manufacturer. A persistent production failure is the ingress of thin cyanoacrylate films into voice coil gaps when dispense volume is not matched to needle retraction speed; the resulting increase in moving mass is detected as an impedance shift and a loss of high-frequency output.
Competitive N-Butyl Cyanoacrylate prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please contact us at +8615380400285 or mail to sales2@ascent-chem.com.
We will respond to you as soon as possible.
Tel: +8615380400285
Email: sales2@ascent-chem.com
Flexible payment, competitive price, premium service - Inquire now!
N-Butyl cyanoacrylate (CAS 6606-65-1) is supplied as a one-part, solvent-free monomeric adhesive ester with the molecular formula C8H11NO2 and molar mass 153.18 g/mol. The unthickened liquid is clear and colourless, with density commonly reported at 0.98–1.01 g/cm³ at 25 °C and refractive index near 1.435–1.445 at 20 °C. Commercial grades are differentiated primarily by viscosity; low-viscosity monomer streams of 2–5 mPa·s are used for wicking into tight joints, while thickened formulations from 50 mPa·s to 1100 mPa·s are produced for gap-filling and controlled placement on porous or vertical surfaces. The product designation often encodes nominal viscosity, such as a 100 mPa·s grade for general flexible bonding or a 500 mPa·s grade for cavity-filling applications.
As an alkyl cyanoacrylate, the material polymerizes anionically when the inhibitor-stabilized monomer contacts surface-adsorbed water, hydroxylated surfaces, or other weak bases. Unlike solvent-borne adhesives, no metering of a second component is required, but the cure is moisture-dependent and will not reach full structural strength in joints with zero residual humidity.
Fixture time is governed by the concentration of surface nucleophiles, not by air humidity alone. On polar metal surfaces such as grit-blasted steel at 23 °C and 50% RH, commercial n-butyl cyanoacrylate grades typically develop handling strength in 20–60 s. On acidic wood species with surface pH below 4.5, cure may be delayed until the surface is neutralized with a borate or sodium bicarbonate wash or until a polyolefin primer is applied. On polypropylene and polyethylene, untreated bond strengths are low because the surface lacks polar initiation sites; flame, corona, or plasma treatment to surface free energy above 40 mN/m is generally required before adhesive application. The butyl ester is slower than ethyl cyanoacrylate because the longer alkyl chain reduces monomer mobility and propagation rate, but this lower reaction rate also reduces exotherm generation, which is important in heat-sensitive assemblies.
Industrial bonding with n-butyl cyanoacrylate is frequently performed on flexible polymer components where ethyl cyanoacrylate would cause stress-cracking or excessive stiffness. On nitrile rubber and EPDM production lines, surface preparation is limited to solvent degreasing with acetone or isopropanol; residual solvent must be fully evaporated because chlorinated or alcohol vapours can induce cosmetic frosting and reduce interphase strength. Pneumatic valve dispensing with moisture-excluding reservoirs and Luer-lock tapered tips of 22–25 gauge is typical for low-viscosity grades. For thickened grades, positive-displacement pumps with sealed feed lines are used to prevent moisture ingress at the stuffing box and to maintain consistent bead weight. Production experience shows that intermittent line stoppages exceeding 15 min with a partially open nozzle can cause skin-over and clogging, even when the reservoir is sealed; purge cycles and disposable static mixers are required in high-humidity plants.
Viscosity is measured by Brookfield rotational viscometry under ISO 2555 at 25 °C. Low-viscosity monomer grades typically display Newtonian behaviour, while thickened formulations are pseudoplastic and may be characterised by a thixotropic index calculated from viscosity ratios at 6 rpm and 60 rpm. Commercial n-butyl cyanoacrylate adhesives are thickened with poly(methyl methacrylate) or hydrophobic fumed silica. Polymethyl methacrylate addition increases cohesive strength and reduces migration into porous substrates but can depress interphase adhesion when the loading exceeds roughly 4–6 wt%; the exact threshold depends on molecular weight and residual monomer content. Hydrophobic fumed silica improves slump resistance and provides thixotropy, but excess silica creates yield stress that prevents wetting on low-energy substrates. Rheology modifications above 8 wt% total thickener are uncommon because cure shrinkage and internal stress rise disproportionately.
N-butyl cyanoacrylate is selected for topical skin approximation and wound closure devices because its cured film is more flexible than methyl or ethyl homologues and because the slower polymerisation produces a lower peak cure exotherm. Medical-grade material is manufactured under controlled anionic inhibition and is released against specifications for residual monomer, stabiliser content, and colour. Biological evaluation of skin-contact or wound-contact devices is conducted according to ISO 10993-5:2009 for cytotoxicity and ISO 10993-10:2010 for sensitisation; specific regional regulatory requirements may also apply. Viscosity in surgical formulations is commonly held between 100 mPa·s and 500 mPa·s to prevent capillary flow into wound margins while allowing film formation over opposed skin edges. The exotherm for n-butyl cyanoacrylate polymerising in a thin film is below the threshold generally associated with thermal tissue injury, but pooling of large liquid volumes remains a risk because local heat and formaldehyde generation are possible.
Operational boundaries are explicit. Bulk monomer is stored at 2–8 °C; cold containers must be equilibrated to ambient temperature before opening to prevent water condensation on the liquid surface. Once opened, the product is best used within the manufacturer-stated workpot life because humid plant air continuously initiates surface polymerisation. Pre-drying is required for absorbent substrates when relative humidity exceeds 60%, because rapid skin-over consumes monomer before substrate wetting is complete. N-butyl cyanoacrylate is incompatible with strongly acidic surfaces, alkaline activators, and alcohol-containing cleaning agents that leave residue; these materials either quench initiation or accelerate polymerisation at the interface and weaken the boundary layer.
The selection between n-butyl, ethyl, and 2-octyl cyanoacrylate depends on a conflict among fixture speed, cured flexibility, and bond strength. Ethyl cyanoacrylate produces the highest tensile shear values on metal but forms a rigid film that is prone to impact failure and stress cracking. 2-Octyl cyanoacrylate provides the greatest elongation and the lowest tissue-irritation profile but is slower and more costly. n-Butyl cyanoacrylate occupies an intermediate position: it retains enough cohesive strength for flexible polymer bonding while reducing exotherm and film brittleness compared with ethyl grades. Comparative data from commercial technical bulletins are summarised in Table 1.
| Property | n-Butyl cyanoacrylate | Ethyl cyanoacrylate | 2-Octyl cyanoacrylate |
|---|---|---|---|
| Unthickened monomer viscosity at 25 °C (mPa·s) | 2–5 | 2–5 | 5–15 |
| Fixture time on grit-blasted steel at 23 °C, 50% RH (s) | 20–60 | 5–15 | 60–120 |
| ISO 4587 lap shear on steel (MPa) | 6–12 | 12–20 | 3–8 |
| Cured homopolymer glass transition (°C) | 50–60 | 120–140 | –10 to 10 |
| Cured film flexibility | Moderate; resists flex cracking | Low; rigid and brittle | High; elastomeric |
The lap shear ranges in Table 1 reflect unplasticized formulations tested under a single overlap configuration; published data for specific medical-grade configurations is limited because substrate preparation and film thickness vary widely. For polyethylene or polypropylene, all alkyl cyanoacrylates require surface activation and lap shear values are typically less than 2–4 MPa.
Commercial certificates of analysis for n-butyl cyanoacrylate typically report viscosity, density, water content, stabiliser content, and gas chromatographic purity. Moisture is a critical specification because water is the initiation species; monomer with water content above 0.1 wt% may exhibit shortened storage stability. Gas chromatography-mass spectrometry is used to confirm monomer purity, and density and refractive index are used as rapid identity checks. Representative methods and specification windows are shown in Table 2.
| Parameter | Method | Typical specification window |
|---|---|---|
| Monomer viscosity at 25 °C | ISO 2555, Brookfield LV2, 60 rpm | 2–5, 50–1100 depending on grade (mPa·s) |
| Density at 25 °C | ASTM D4052 | 0.98–1.01 g/cm³ |
| Water content | Karl Fischer titration | ≤ 0.10 wt% for medical grades; ≤ 0.30 wt% for industrial grades |
| Gas chromatographic purity | GC/FID or GC/MS | ≥ 99.0 area% for electronic/medical; ≥ 95.0 area% for general industrial |
| Stabiliser acid content | Potentiometric titration | typically 30–60 ppm SO₂ equivalent |
Regulatory classification depends on the end-use. Industrial cyanoacrylate adhesives may require registration under regional chemical inventories, while medical topical adhesive devices are regulated as medical devices in major jurisdictions and may require biocompatibility data under ISO 10993-1:2018. Food-packaging uses are limited; indirect-contact adhesive compliance with 21 CFR 175.105 may apply to selected industrial formulations, but n-butyl cyanoacrylate is not intended for direct food contact. REACH and RoHS obligations are product-specific; producers or importers must verify whether monomer, stabiliser, or colourant components are subject to candidate-list restrictions. The lower butyl homopolymer modulus means that n-butyl cyanoacrylate is not a direct substitute for flexible 2-octyl cyanoacrylate in high-elongation skin adhesives, and its lower lap shear compared with ethyl grades prevents substitution in rigid metal-to-metal assemblies where maximum shear strength is the controlling requirement.
