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| HS Code | 308785 |
| Chemical Name | n-Butyl Acrylate |
| Cas Number | 141-32-2 |
| Molecular Formula | C7H12O2 |
| Molecular Weight | 128.17 g/mol |
| Appearance | Clear colorless liquid |
| Boiling Point | 145 °C |
| Melting Point | -64.9 °C |
| Flash Point | 40 °C (closed cup) |
| Density | 0.894 g/cm3 at 20 °C |
| Vapor Pressure | 4.3 mmHg at 20 °C |
| Solubility In Water | 1.4 g/L at 20 °C |
| Refractive Index | 1.4185 at 20 °C |
As an accredited N-Butyl Acrylate factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | N-Butyl Acrylate is packaged in 180 kg steel drums or 900 kg IBC totes, sealed under nitrogen to ensure stability. |
| Container Loading (20′ FCL) | Loading N-Butyl Acrylate into a 20′ FCL: secure drums/IBCs, prevent movement, ensure compatibility, ventilation, and proper labeling. |
| Shipping | N-Butyl Acrylate is shipped as UN 2348, Butyl Acrylates, stabilized, Class 3 flammable liquid. It must contain polymerization inhibitor, be packed in approved drums/IBCs or tank containers, and kept away from ignition, heat, and oxidizers. Proper labeling, grounding, and ventilated transport are required to ensure safety. |
| Storage | Store N-Butyl Acrylate in tightly sealed, grounded containers in a cool, dry, well-ventilated area away from heat, sparks, open flames, oxidizers, and direct sunlight. Maintain proper inhibitor (e.g., MEHQ) levels to prevent polymerization. Avoid elevated temperatures. Use explosion-proof equipment and follow local regulations for flammable liquid storage. |
| Shelf Life | Shelf life is typically 6 months when stored cool, dark, and tightly sealed with inhibitor present. |
In waterborne acrylic architectural coatings, n-butyl acrylate is incorporated at 40–55 wt% of total vinyl monomers in the emulsion polymer when a pure acrylic binder with a calculated Fox glass transition temperature between -10 °C and 15 °C is specified for exterior durability and low-temperature film formation. The comonomer composition includes methyl methacrylate or styrene at 40–60 wt%, acrylic acid or methacrylic acid at 1.0–2.5 wt%, and n-dodecyl mercaptan at 0.1–0.4 wt% as molar mass regulator. The emulsion polymer is produced by seeded semi-batch emulsion polymerization in a jacketed glass-lined or stainless reactor charged with deionized water and a seed latex representing 3–5 wt% of total monomer mass. A monomer pre-emulsion containing anionic and nonionic surfactants is metered over 180–240 min at 80–85 °C while ammonium persulfate is fed at 0.3–0.6 wt% based on total monomer. After complete feed, residual n-butyl acrylate is reduced below 0.10 wt% through a redox chase with tert-butyl hydroperoxide and sodium formaldehyde sulfoxylate at 65–70 °C. The latex is then neutralized with ammonia to pH 7.5–8.5 and filtered through 100–150 µm bag filters. Compliance for such binders in the European Union is determined under Directive 2004/42/EC Phase II category A/d for water-borne interior/exterior trim and cladding coatings, with a VOC limit of 130 g/L, while GB 18582-2020 restricts VOC in interior architectural coatings to 80 g/L for ready-to-use materials. Film hardness is assessed by ISO 1522 pendulum damping and early block resistance by ASTM D4946-89. Finished goods include interior and exterior flat, satin and semigloss architectural paints, elastomeric roof coatings, waterborne direct-to-metal primers, and high-durability exterior insulation and finishing system basecoats.
The measured viscoelastic coupling in pressure-sensitive adhesives based on n-butyl acrylate depends on residual monomer concentration because low-molecular-weight n-butyl acrylate acts as an internal plasticizer and depresses shear holding power while transiently increasing tack. In high-solids solution acrylic PSAs, n-butyl acrylate is typically charged at 45–70 wt% of total monomers, 2-ethylhexyl acrylate at 15–30 wt%, vinyl acetate at 10–20 wt%, and acrylic acid at 2–5 wt%. Crosslinking agent such as aluminum acetylacetonate or polyfunctional aziridine is added at 0.1–0.5 phr on dry polymer to control shear. Polymerization proceeds in ethyl acetate/toluene at 75–80 °C with azobisisobutyronitrile as thermal initiator, followed by vacuum stripping at 60–70 °C and 20–40 kPa to reduce residual n-butyl acrylate below 0.10 wt% in the dry film. On high-speed transfer coating lines, the adhesive solution is applied to a release liner by comma roll or slot die at 15–60 g/m² dry coat weight, dried in zones at 70–90–110 °C, and laminated to BOPP, PET or paper facestock. Compliance for food-contact tape and label constructions in the United States is anchored in FDA 21 CFR 175.105 for adhesives and 21 CFR 175.125 for pressure-sensitive adhesives intended for contact with food under conditions of use A through H. Loop tack is measured according to ASTM D6195-03(2019), peel adhesion by ASTM D3330/D3330M-04(2018), and holding shear by ASTM D3654/D3654M-06(2019). Terminal product types include masking tapes, permanent and removable labels, surface protection film, double-sided foam bonding tape, and medical adhesive dressings.
A styrene-acrylic or vinyl acetate-acrylic nonwoven binder formulated with 40–65 wt% n-butyl acrylate in the monomer feed develops film flexibility at -20 °C to -10 °C calculated by the Fox equation, while self-crosslinking N-methylolacrylamide monomer at 2–5 wt% provides wet strength after cure. The balance is styrene or vinyl acetate at 20–50 wt%, acrylonitrile at 5–10 wt% where solvent resistance is specified, and acrylic acid at 1–3 wt% to stabilize the latex and improve adhesion to cellulose and polyester nonwoven substrates. The emulsion polymerization is conducted as a semi-batch redox or thermal process at 30–45 °C when using tert-butyl hydroperoxide/isoascorbic acid, or at 80–85 °C with ammonium persulfate when a conventional thermal initiation route is selected. After monomer addition, residual n-butyl acrylate is reduced to below 0.05 wt% by redox initiator addition, and the dispersion is neutralized to pH 5.5–6.5 and adjusted with formaldehyde scavenger, typically urea or acetoacetamide, to limit free formaldehyde. In production, the binder is applied by saturation bonding, foam finishing, or spray bonding on carded or airlaid webs at pad pressure of 1.5–4.0 bar, then dried and cured at 150–170 °C for 1–3 min in a stenter. Compliance is assessed against OEKO-TEX Standard 100 Annex 4 limit values for formaldehyde below 16 mg/kg for baby articles, ZDHC MRSL v3.1 restricted substance lists, and REACH Annex XVII entry 46a restrictions on nonylphenol and nonylphenol ethoxylates. Finished goods include hydroentangled wet wipes, airlaid nonwoven paper, needlepunch automotive carpet binders, medical gown fabrics, and interlinings for garment manufacture.
On industrial leather finishing lines, n-butyl acrylate-containing acrylic emulsion binders are selected for the basecoat and compact intermediate coats because the low glass transition temperature contribution of poly(n-butyl acrylate), approximately -49 °C, permits film coalescence at plate temperatures of 70–90 °C without external coalescing solvent. In a typical finish formulation, n-butyl acrylate represents 20–45 wt% of the monomers in the acrylic binder, with methyl methacrylate or styrene at 40–60 wt%, acrylonitrile at 5–15 wt% for solvent fastness, and acrylic acid or methacrylic acid at 1.0–2.5 wt%. The polymerization is run as a semi-batch emulsion process at 75–85 °C using ammonium persulfate initiation and anionic/nonionic surfactant stabilization, yielding a dispersion of 45–50 wt% solids with particle size 80–150 nm and pH 6.5–7.5. The finish is applied by HVLP or airmix spray at 3–6 bar atomization, by roller coater, or by reverse roller coater, with intermediate drying tunnels set at 60–90 °C and final crosslinking promoted by polyfunctional aziridine or isocyanate at 0.3–0.8 wt% based on binder solids. To avoid premature gelation, the aziridine crosslinker is added only after pH adjustment and the pot life is limited to 8–12 h; contact with acidic residues or strong oxidizing agents must be avoided. Leather complying with automotive or furniture specifications is tested for wet and dry crocking according to ISO 11640:2018, for formaldehyde according to ISO 17226-2:2019, and for APEO and restricted substances according to ZDHC MRSL v3.1. Finished goods include corrected-grain and split-grain automotive upholstery leather, footwear upper leather, garment leather, handbag and small leather goods, and upholstered furniture leather.
Because n-butyl acrylate-rich acrylic sealant dispersions show shear-thinning flow and rapid skin-over above 35 °C ambient dry-bulb temperature, production batches are processed under vacuum at 0.08–0.095 MPa absolute pressure with jacket water maintained below 45 °C to prevent irreversible bodying. The formulation contains a high-molar-mass acrylic dispersion with n-butyl acrylate in the polymer backbone at 25–45 wt% on wet sealant, ground calcium carbonate filler at 30–45 wt%, coalescents and plasticizers at 5–15 wt%, titanium dioxide at 2–5 wt%, and a hydroxyethylcellulose or associative polyurethane rheology modifier at 0.1–0.5 wt%. Mixing is carried out in a planetary mixer or high-shear dissolver with a peripheral speed of 10–25 m/s, followed by vacuum deaeration and filler addition under nitrogen blanketing to control pH at 8.5–9.5. Compliance for movement capability is verified under ISO 11600:2002 + Amd 1:2011 class 12.5P for interior and exterior joints, and in the United States under ASTM C834-17 for latex sealants, with adhesion-in-peel after water immersion assessed by ASTM C794-18; staining potential is evaluated by ASTM C1248-06(2012). Terminal product types include paintable acrylic caulks for interior wall and ceiling joints, exterior door and window perimeter sealants, coving and skirting joints, and crack-filling compounds for rendered facades.
In coated paper and paperboard manufacture, n-butyl acrylate is incorporated into styrene-acrylic or all-acrylic latex binders at 25–50 wt% of total monomers to depress the minimum film-forming temperature below 20 °C and improve web offset wet pick strength. The binder copolymer includes styrene or methyl methacrylate at 40–60 wt%, acrylonitrile at 5–10 wt% for dry pick resistance, and acrylic acid at 1–3 wt% to provide latex colloidal stability and pigment wetting. In coating color preparation, the latex is added at 8–15 pph on pigment, with ground calcium carbonate and fine kaolin at 100 parts total pigment, carboxymethylcellulose or starch co-binder at 0.3–1.0 pph, and optical brighteners and dispersants at 0.2–0.5 pph. The coating is applied by blade coater or roll applicator on calendered paper at machine speeds of 800–1500 m/min, with drying initially by infrared radiation and then air flotation dryers at 120–180 °C web surface temperature. Compliance for coated paper and paperboard intended for dry and aqueous food contact is regulated under FDA 21 CFR 176.170 and 176.180, with migration testing under EN 1186-1:2002 and sensory evaluation under EN 1230-1:2009; for packaging in the European Union, Regulation (EC) No 1935/2004 and BfR Recommendation XXXVI/1 apply. Terminal products include coated fine paper, gloss and matte label face stock, coated recycled paperboard, and folding carton stock for dry and aqueous food packaging.
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n-Butyl acrylate, CAS Registry Number 141-32-2, is a linear acrylate ester monomer with the molecular formula CH₂=CHCOO(CH₂)₃CH₃ and a molar mass of 128.17 g/mol. At 20°C the liquid monomer has a density of approximately 0.898 g/cm³, a boiling point of 145–146°C at 101.3 kPa, a closed-cup flash point reported near 39°C, and a vapor pressure of approximately 0.53 kPa. Dynamic viscosity is near 0.8 mPa·s at room temperature. The commercial product is normally supplied as an inhibited technical grade; the inhibitor is commonly a hydroquinone derivative such as monomethyl ether of hydroquinone. Oxygen is required to maintain the activity of phenolic inhibitors, and storage practice must therefore avoid prolonged inert-gas blanketing unless the inhibitor system has been specifically qualified for oxygen-free operation. In polymerization, the butyl side chain reduces dipole-dipole interaction between acrylate repeat units and lowers the glass transition temperature relative to shorter-chain acrylate esters. Published differential scanning calorimetry values for poly(n-butyl acrylate) homopolymer determined according to ISO 11357-2 typically fall between -49°C and -54°C. The principal industrial role is as a flexibilizing backbone monomer in acrylic solution, emulsion, and suspension polymers used in coatings, adhesives, sealants, and polymer dispersions. Commercial grade designations vary by supplier, but the formal technical description is n-butyl acrylate, inhibited, technical grade, with low-water, low-acid, and reduced-inhibitor variants available for specific downstream processes.
The selection among acrylate monomers in a polymer formulation is governed primarily by volatility during reactor feeding, water solubility, homopolymer glass transition temperature, and processing behavior. Methyl acrylate, CAS 96-33-3, has a boiling point of approximately 80°C and yields a homopolymer with a reported glass transition temperature near 10°C. Its higher volatility and greater water sensitivity make it less suitable than n-butyl acrylate when low-temperature flexibility and reduced monomer loss are required. Ethyl acrylate, CAS 140-88-5, boils near 99°C and produces a homopolymer glass transition temperature around -24°C, placing it between methyl acrylate and n-butyl acrylate in flexibility. n-Butyl acrylate provides a longer linear ester substituent than ethyl acrylate, giving lower polarity and lower water absorption in the resulting polymer while retaining a manageable reactor vapor pressure. 2-Ethylhexyl acrylate, CAS 103-11-7, boils at approximately 213–214°C and imparts pronounced chain flexibility, but its branched alkyl chain introduces different rheological response in solution polymers because side-chain entanglement and free-volume contributions are not equivalent to those of the linear butyl chain. In free-radical copolymerization, n-butyl acrylate and 2-ethylhexyl acrylate are both electron-poor acrylate esters, but direct replacement usually requires revalidation of reactor temperature, feed rate, residual monomer stripping, and film mechanical properties.
| Property | Methyl acrylate | Ethyl acrylate | n-Butyl acrylate | 2-Ethylhexyl acrylate |
|---|---|---|---|---|
| CAS registry number | 96-33-3 | 140-88-5 | 141-32-2 | 103-11-7 |
| Molar mass, g/mol | 86.09 | 100.12 | 128.17 | 184.28 |
| Boiling point at 101.3 kPa, °C | 80 | 99 | 145–146 | 213–214 |
| Reported homopolymer DSC Tg range, °C | 10 | -24 | -49 to -54 | -50 to -70 |
The higher boiling point of n-butyl acrylate compared with ethyl acrylate reduces monomer loss from the reactor condenser and lowers the volatile organic load during emulsion processing. The linear butyl group also gives a more compact polymer chain than 2-ethylhexyl acrylate at the same molar incorporation, which can raise tensile storage modulus measured by dynamic mechanical analysis at low frequency. Published data for this specific comparison is limited because differences in copolymer composition, crosslinking, and molecular weight dominate the final dynamic mechanical response.
Within the commercial supply chain, product grades are separated by n-butyl alcohol concentration, acidity, water, color, and inhibitor loading. n-Butyl alcohol is the principal residue from acid-catalyzed esterification of acrylic acid with n-butanol. In downstream free-radical polymerizations it can act as a chain-transfer agent, and elevated concentrations can reduce number-average molecular weight in high-solids acrylics where solvent chain transfer must already be limited. Purchasing specifications for resin manufacture therefore frequently include a maximum n-butanol content that is not automatically present in the standard bulk monomer specification and must be agreed with the supplier. Acidity as acrylic acid is also closely controlled because carboxyl groups influence adhesion to metal substrates, water sensitivity, and the viscosity response of neutralized latex.
Commercially available inhibited technical grades are not a single product. They include standard inhibited monomer, reduced-inhibitor monomer for continuous polymerizers, and low-water or low-acid variants for moisture-sensitive urethane acrylate production. The correct grade is selected by evaluating induction time in the intended polymerizer, storage temperature, and initiator half-life at the reactor operating temperature. A specific supplier model code is not standardized across the industry; therefore, purchasers normally reference the chemical name with the required impurity and inhibitor limits on the purchase specification.
The table below lists representative limits for an inhibited technical-grade monomer offered for bulk tank truck or isotank delivery. Actual supplier certificates of analysis may differ, and compliance is verified against the specified test method on each lot.
| Parameter | Typical limit | Test method |
|---|---|---|
| Purity, n-butyl acrylate by gas chromatography | ≥ 99.5 wt% | ASTM D3362 |
| Water, Karl Fischer titration | ≤ 0.05 wt% | ASTM E203 |
| Acidity, as acrylic acid | ≤ 0.009 wt% | ASTM D1613 |
| Color, Pt-Co/APHA | ≤ 10 | ASTM D1209 |
| Inhibitor, monomethyl ether of hydroquinone | 15 ± 5 mg/kg | HPLC-UV |
| Appearance | Clear, free of suspended matter | Visual inspection |
Bulk storage of inhibited n-butyl acrylate is typically conducted in 304 or 316L stainless steel tanks fitted with a vacuum/pressure relief device and a flame arrestor. Storage temperature is maintained below 35°C; lower temperatures reduce inhibitor consumption and slow ester hydrolysis. Copper, brass, and rust must not contact the monomer because transition metals, particularly copper ions, can promote radical formation and initiate polymerization. The vapor space above the liquid should be maintained with air to keep the phenolic inhibitor active. Transfer piping and pumps are designed for a liquid with a closed-cup flash point near 39°C, and electrically grounded stainless steel lines are used to avoid static discharge. Sampling ports should be kept sealed because water contamination increases hydrolysis to n-butanol and acrylic acid, and the resulting acid can corrode carbon steel storage systems over time.
In emulsion pressure-sensitive adhesive syntheses, n-butyl acrylate commonly constitutes 60–90 wt% of the total monomer charge. The balance is typically methyl methacrylate or styrene for modulus control, plus acrylic acid or methacrylic acid at 1–5 wt% for colloidal stability and adhesion to polar substrates. Polymerization is carried out in jacketed stainless steel reactors equipped with a reflux condenser and an anchor or pitched-blade turbine agitator. The surfactant package is usually an anionic ether sulfate with a nonionic alcohol ethoxylate, at total levels between 0.5 and 1.5 parts per hundred monomer, and the monomer is introduced as a pre-emulsion over 3–4 h. Thermal initiation with ammonium persulfate at 75–85°C or a redox couple is used; the exotherm is controlled by adjusting feed rate and jacket cooling. The heat of polymerization is significant, and a temporary loss of agitation in a starved-feed reactor can produce localized hot spots and rapid exothermic polymerization.
The butyl ester content lowers film modulus and increases room-temperature tack. Peel adhesion is commonly measured by ASTM D3330, loop tack by ASTM D6195, and shear holding power by ASTM D3654. Higher n-butyl acrylate content generally reduces shear resistance and increases peel and tack, so formulators compensate by adding internal crosslinkers such as diallyl phthalate or acetoacetoxyethyl methacrylate plus diamine post-crosslinking. Film tensile properties may be characterized by ASTM D882. Production-scale experience indicates that coagulum and filter plugging are more sensitive to pre-emulsion stability when n-butyl acrylate content exceeds 80 wt%; coarse-particle formation increases if the pre-emulsion is not shear-stabilized or if agitation is interrupted during feed. Published data for optimized shear-stable formulations is formulation-specific, and no universal coagulum limit applies across surfactant packages.
Compared with butyl methacrylate, n-butyl acrylate has no α-methyl group. The homopolymer of butyl methacrylate has a glass transition temperature near 20°C, while that of n-butyl acrylate is below -49°C. This difference is exploited in acrylic copolymers: n-butyl acrylate contributes flexibility and tack, while butyl methacrylate raises modulus and hardness without introducing styrenic groups. In polymerization, the α-methyl group also lowers the propagation rate constant and increases resistance to alkaline hydrolysis of the ester group, so a direct replacement of butyl methacrylate by n-butyl acrylate requires reformulation of initiator level, reaction temperature, and crosslinker.
Beyond emulsion pressure-sensitive adhesives, n-butyl acrylate is used in solvent-borne coil coatings, industrial maintenance topcoats, and UV-curable oligomers. For solvent-borne acrylic resin production, the monomer is typically reacted in a continuous stirred tank reactor or a solution polymerization train at 130–150°C with a peroxide initiator, after which the solvent and unreacted monomer are stripped under vacuum. In high-solids resins it is preferred over ethyl acrylate because of lower vapor pressure and preferred over 2-ethylhexyl acrylate when lower steric hindrance and more uniform copolymerization are required. Published quantitative comparisons of molecular weight distribution are usually specific to reactor configuration and initiator type. n-Butyl acrylate is also used in urethane acrylate oligomers for radiation-curable coatings, where residual acid and water must be controlled to avoid pigment wetting defects and side reactions with isocyanates. In that use the low-water grade is selected because water competes with hydroxyl-functional acrylics for free isocyanate and can reduce crosslink density in the cured film.
