| HS Code | 342153 |
| Product Name | Resyn SB-321 |
| Manufacturer | National Starch and Chemical Company (now Henkel) |
| Chemical Family | Styrene-butadiene copolymer latex |
| Appearance | Milky white to off-white liquid |
| Total Solids | 50%–52% |
| Viscosity | 100–300 cP at 25°C |
| Ph | 8.0–9.5 |
| Specific Gravity | 1.01–1.03 at 25°C |
| Glass Transition Temperature | Approximately 5°C |
| Particle Charge | Anionic |
| Film Property | Flexible, water-insoluble film |
| Primary Use | Adhesive binder for paper, packaging, and coating applications |
| Storage | Store at 5–35°C, protected from frost |
As an accredited Resyn SB-321 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Resyn SB-321 chemical is supplied in 55-gallon drums, approximately 400 pounds net each, with proper labeling and handling instructions. |
| Container Loading (20′ FCL) | 20′ FCL loading of Resyn SB-321: secure drums, segregate properly, ventilate container, and follow chemical handling guidelines. |
| Shipping | Resyn SB-321 ships as a non-hazardous dry resin in lined multi-wall bags or drums on pallets. Protect from moisture, direct sunlight, and extreme temperatures during transit. Standard truck or sea freight is acceptable. Ensure containers are sealed and dry to preserve product quality. |
| Storage | Store Resyn SB-321 in its original, tightly sealed container in a cool, dry area between 40–90°F (4–32°C). Avoid freezing, excessive heat, and direct sunlight. Keep away from moisture and incompatible materials. Stir gently before use. Use within its stated shelf life to maintain performance, and rotate stock accordingly. |
| Shelf Life | Shelf life is six months from manufacture when stored unopened at 60–80°F, protected from freezing. |
At line speeds between 12 m/min and 18 m/min on a Fleissner through-air drum dryer, the binding behaviour of Resyn SB-321 in needlepunched polyester/viscose interlinings is controlled less by total solids than by the pH of the dilution bath and the residual moisture entering the first drying zone. Mill records from high-loft headliner substrate production show that diluting the supplied dispersion to 10–18 % solids with deionized water produces a stable low-viscosity bath below 200 mPa·s at 25 °C when measured on a Brookfield RV spindle 2 at 100 rpm; the same bath drops out within 4 h if the dilution water contains more than 180 ppm calcium carbonate hardness because the carboxylated styrene-butadiene latex undergoes ionic destabilisation at pH values below 7.2. For a 22 % wet pick-up applied through a kiss-roll coater with a 40 Shore A transfer roll, the dried add-on lands in the range of 2.5–4.0 g/m² per side. The critical processing window is not the add-on itself but the first 30 s in a two-zone oven: when the first-zone air temperature exceeds 155 °C while the web moisture content is still above 25 %, surface film formation creates a skin that traps water vapour and leads to brown specks and a 20–30 % loss in tensile retention after ageing, measured according to ISO 9073-2:1995. On slower lines below 8 m/min, the same add-on can be achieved with a single-sided foam coater fitted with a 1.2 mm slot and a blow ratio of 1:4, but the foam must be collapsed within 1.5 m of the application point. For automotive trim grades, heat stabilisation with a zinc-free phenolic antioxidant is recommended because zinc carboxylate accelerators can promote premature ionic crosslinking at elevated temperatures above 170 °C; without stabilisation, the ISO 9073-2 dry tensile strength of the nonwoven can fall from a typical 35–45 N/50 mm to below 25 N/50 mm after 14 days at 150 °C in forced air. The latex also shows incompatibility with cationic antistatic agents; if an antistat is required on the production line, it should be applied post-drying rather than in the saturation bath.
When Resyn SB-321 is added as a polymer modifier at 8–12 % by cement mass in a two-component slurry applied at 1.5–2.0 mm wet film thickness, the most frequent failure point is not seven-day adhesion but the crack-bridging response after 60 d of water immersion. EN 14891:2017 requires a crack-bridging capacity of at least 0.75 mm at -20 °C for cementitious flexible waterproofing products; SB-321-rich formulations typically meet this value only if the polymer-to-cement ratio is held above 9 % and the water demand is kept low enough to avoid film-forming displacement at the drying front. A mill-scale vertical mixer running at 600–800 rpm with a 0.10–0.12 water-to-binder ratio will produce a homogeneous slurry with a Brookfield RV viscosity of 60–80 Pa·s; increasing the water-to-binder ratio to 0.15 reduces that viscosity to 30–40 Pa·s but also produces microcracks during 24 h forced-air drying at 35 °C because the latex particles are transported to the surface before coalescence has developed a continuous polymer network through the cement matrix. The same effect appears when the substrate is concrete with a moisture content above 4 %: a 1.5 mm film dried at 23 °C and 50 % relative humidity retains its EN 14891 crack-bridging rating, while a film applied to a substrate at 95 % relative humidity can lose up to 35 % of its low-temperature flexibility. Because SB-321 is an anionically stabilised styrene-butadiene dispersion, it should not be combined with calcium aluminate cements or with high-alumina accelerators that release polyvalent metal ions faster than the latex can stabilise them; this combination leads to visible flocculation within 5 min and a sharp drop in tensile adhesion measured according to ASTM C1583-13. For thin-bed tile adhesive modification, a lower dose of 3–5 % by cement mass improves wetting and sag resistance without generating the excessive skinning that complicates long open times.
| Performance property | Test standard | Exposure condition | Measured range at 10 % SB-321 on cement |
|---|---|---|---|
| Crack bridging at low temperature | EN 14891:2017 | -20 °C | 0.75–1.10 mm |
| Tensile adhesion on concrete | ASTM C1583-13 | 28 d dry cure | 0.8–1.3 MPa |
| Water absorption coefficient | EN 1062-3:2008 | 24 h immersion | 0.05–0.10 kg/(m²·h⁰·⁵) |
For tufted carpet secondary backing lamination, the operational boundary is reached when the formulation crosses 400 phr of calcium carbonate relative to latex solids on a dry basis. At 300–400 phr, a typical compound produced in a twin-shaft batch mixer with a final viscosity of 14,000–18,000 mPa·s at 25 °C will show stable frothed density at 0.8–0.9 g/cm³ when aerated with a 2:1 air-to-liquid ratio on a continuous frothing unit. Above 400 phr, the wet film between woven polypropylene and secondary backing no longer forms a continuous tie coat under a lamination nip of 0.25–0.35 MPa; delamination values measured on a tensile tester according to ASTM D3936-17 can drop from 2.0–3.0 kg/50 mm to below 1.2 kg/50 mm. Because the latex is anionically charged, calcium carbonate slurries must be dispersed with a sodium polyacrylate-type dispersant rather than a cationic wetting agent; otherwise the precoat exhibits seed-like agglomerates that appear as visible pimples after the tenter oven at 135–145 °C.
Paper and paperboard precoat formulations using Resyn SB-321 as a co-binder are sensitive to high-shear viscosity rather than low-shear Brookfield readings. A coating colour made with 68–72 % total solids, ground calcium carbonate at 80 parts, clay at 20 parts, and latex at 8–12 parts dry basis tends to show a Hercules high-shear viscosity of 40–60 mPa·s at 4,400 s⁻¹; if the latex dose is raised to 15 parts without reducing the GCC dosage, blade-coating runnability declines and the wet film at 1,200 m/min may exhibit skip patches. The ionic compatibility envelope is narrow: SB-321 does not tolerate aluminium sulphate in excess of 0.15 % on dry pigment weight because the resulting cationic bridge flocculation raises the low-shear viscosity by more than 1,000 mPa·s within one hour. For folding boxboard grades, the use of SB-321 at 10 parts dry improves wet ink receptivity and surface strength as measured by IGT pick velocity; a typical value of 1.1–1.4 m/s at 38 % ink tack is achievable without a post-coating size press. However, published data for this specific configuration is limited because most paper mills run SB-321 as a partial replacement for carboxylated styrene-butadiene binders at 30–50 % replacement rather than as a sole binder. Wet-curl control requires coating solids below 66 % if the base sheet has a moisture content above 6.5 %. The use of optical brightening agents is physically compatible but the carrier must be nonionic; anionic OBA carriers compete for the same cationic retention aids and can reduce the brightness gain by 0.3–0.5 points.
| SB-321 dry parts | Total solids | Hercules viscosity at 4,400 s⁻¹ | IGT pick at 38 % tack |
|---|---|---|---|
| 8 | 66 % | 32–38 mPa·s | 0.9–1.1 m/s |
| 10 | 68 % | 40–50 mPa·s | 1.1–1.4 m/s |
| 12 | 70 % | 55–65 mPa·s | 1.2–1.5 m/s |
In cold-applied asphalt sealants based on anionic bitumen emulsions, Resyn SB-321 acts as a film-forming modifier only if the emulsion pH is held between 8.0 and 9.5 and the added latex is diluted to 25–35 % solids before injection into the colloid mill discharge line. The rotor-stator shear in the mill is sufficient to break the latex if the addition point is upstream of the mill; downstream addition with a static mixer yields stable formulations. At 10–15 % latex by bitumen weight, the dried film develops a more uniform elongation after 14 d at 23 °C per ASTM D412-16, but wet-stone adhesion on damp concrete remains below 0.2 MPa unless the substrate is primed.
Resyn SB-321 is used as a base polymer for water-based tube-winding adhesives where the applied film must develop immediate green tack on kraft surfaces. A typical formulation at 55–60 % solids with 8–10 parts plasticiser and 0.3–0.5 parts defoamer on dry polymer shows a loop tack of 2.0–2.5 N/25 mm on kraft liner at 23 °C measured with a loop tack tester according to ASTM D6195-03(2019). The processing limit appears when the adhesive is circulated through a ring-main system at 30–35 °C for more than 12 h; the carboxylated latex builds viscosity by 15–20 % due to mechanical shear and requires dilution with a 2–3 % ammonia solution to restore a cup viscosity of 1,500–2,000 mPa·s. The same adhesive is not recommended for aluminum foil lamination because the alkaline pH of the dried film can lead to surface oxidation under high-humidity storage above 65 % relative humidity.
For foam-backed carpet underlay produced by gelled latex froth at 0.35–0.45 g/cm³, SB-321 requires the addition of 2–3 phr zinc oxide and 1–2 phr sulphur because the carboxylated polymer alone does not develop adequate compression set under ASTM D3574-17; the compound is gelled with sodium silicofluoride at 0.5–1.0 phr.
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Resyn SB-321 is supplied as an aqueous styrene-butadiene copolymer dispersion in which the alphanumeric model designation identifies a particular binder within the manufacturer’s SB series. The model number is a manufacturing differentiation code and does not by itself state solids content, glass transition temperature, or particle size; the batch certificate of analysis is therefore the controlling specification. The product is used in waterborne adhesive, coating, nonwoven saturation, and fiber-sizing operations where a balance of low-VOC processing, substrate wetting, and peel adhesion is required. Referee methods include ISO 3251:2019 for non-volatile content by oven drying at 105 °C for 3 h, ISO 976:2013 for pH, and ISO 2555:2018 for apparent viscosity at 25 °C with a Brookfield-type rotational viscometer. Additional specification parameters include mechanical stability under ISO 2006-1:2009, coagulum retention under ISO 4576:1996, and minimum film-forming temperature under ISO 2115:2001. Published data for this specific configuration is limited; quantitative release values must be taken from the supplier technical datasheet or lot certificate.
The film-formation boundary of Resyn SB-321 is determined by the minimum film-forming temperature, which is a function of particle shell stiffness, polymer molecular weight, surfactant type, and drying rate. In a pressure-sensitive adhesive laminate, coalescent demand is minimized when the wet film remains above the MFFT long enough for particle deformation to close voids. Below the MFFT, capillary pressure cannot overcome polymer modulus; the dried film exhibits discontinuous fusion and peel adhesion fails by particle-boundary failure. The formulator should measure MFFT by ISO 2115:2001 and maintain a process margin of at least 5 °C between the coating line’s lowest substrate temperature and the measured white point. If the product is blended with a coalescing agent such as an ester alcohol or a low-molecular-weight glycol ether, the dosage is not directly transferable from acrylic emulsion systems because the styrene-butadiene particle may show different swelling behavior. Lot-specific MFFT drift of even 2 °C has produced visible mudcracking on coated polyethylene films in production-scale trials; published data for this specific configuration is limited to supplier technical bulletins and customer qualification records.
The capillary pressure driving particle deformation scales inversely with particle radius; a smaller average particle size can improve film coalescence but also increases high-shear viscosity. In SB-321, the particle size distribution is a controlled but unpublished specification. The operator should not infer film quality from dry film clarity alone; particle-boundary voids may be present below the resolution of visual inspection. Destructive peel testing after conditioning for 24 h at 23 °C and 50 % RH gives a more reliable indicator of fusion than immediate inspection. If the coalesced film exhibits low clarity and low peel, the defect may originate from insufficient drying time, not from the resin itself.
Storage conditions impose boundary conditions that are easy to violate in unheated warehouses. Resyn SB-321 must be protected from freezing because ice formation ruptures latex particles and leads to irreversible coagulum; anionic styrene-butadiene dispersions of this class are commonly stored between 5 °C and 35 °C, but the exact band appears in the supplier SDS. Dilution water should be screened for hardness and conductivity; polyvalent cations such as Ca²⁺ and Mg²⁺ compress the electrical double layer and raise the risk of progressive flocculation. In letdown, a low-shear axial-flow impeller is preferred over a high-speed disperser. When the product is transferred to a coating head, a 100 µm conical or bag filter removes shear-generated coagulum and protects slot-die lips. Warm-water cleanup above 40 °C can cause premature particle fusion and should be avoided unless the line is to be stripped.
Adjusting the non-volatile content of Resyn SB-321 changes the rheology from a moderately shear-thinning medium to a more strongly pseudoplastic material; this adjustment is often used to increase wet film thickness and reduce drying load. A solids increase of even 2 wt% can raise low-shear viscosity disproportionately because the dispersed phase volume fraction approaches the close-packing boundary. The response should be mapped with a controlled-stress rheometer rather than a single-point Brookfield reading; ISO 3219-1:2021 or an equivalent rotational rheometry method can be used for viscosity curves. Associative thickeners that rely on hydrophobically modified urethane backbones may show less predictable interaction with styrene-butadiene particles than with acrylic dispersions; in field trials, certain HEUR thickeners caused transient gelation that disappeared only after mild shear. The formulator should evaluate thickener compatibility at the final pH and at typical line shear rates, using a cone-plate rheometer at 25 °C and a shear rate sweep from 0.1 s⁻¹ to 1000 s⁻¹. Published data for this specific configuration is limited, so pilot coating trials are required.
The volume-fraction dependence of low-shear viscosity is commonly described by a Krieger-Dougherty relation; the maximum packing fraction and intrinsic viscosity coefficients for this specific dispersion are not published. Without these coefficients, a formulator should avoid extrapolating viscosity from one solids level to another. The concentration response should be measured at the final pH and thickener package over the entire solids range expected in production, because solids adjustment and thickener response are coupled.
| Specification property | Referee method | Data status for Resyn SB-321 |
|---|---|---|
| Non-volatile content | ISO 3251:2019 | Lot CoA release value |
| pH | ISO 976:2013 | Lot CoA release value |
| Brookfield apparent viscosity | ISO 2555:2018 | Lot CoA release value |
| Minimum film-forming temperature | ISO 2115:2001 | Supplier bulletin or class data |
| Mechanical stability | ISO 2006-1:2009 | Supplier technical bulletin |
| Coagulum retention | ISO 4576:1996 | Lot CoA release value |
Mechanical destabilization in transfer equipment is a known bottleneck on production-scale coating lines. Resyn SB-321 should be conveyed with low-pulse pumps such as progressive cavity or diaphragm units; piston pumps with small clearances may create local shear hot spots. When a piston pump was replaced by a progressive cavity pump on one flexible packaging line, filter blocking from coagulum decreased, but this observation is equipment-specific and should not be used as product-specific validation. Published data for this specific configuration is limited.
If pH adjustment is necessary, dilute ammonia or potassium hydroxide should be added slowly under low-shear agitation. Acid additions can create local pH collapse and result in irreversible microgel particles, which appear as fish-eye defects in drawdown coatings. The final pH should be measured by ISO 976:2013 and compared with the supplier’s stability window. In field trials, a pH drop of more than 0.5 pH units during mixing produced measurable increases in 100 µm screen retention. Published data for this specific configuration is limited.
Resyn SB-321 can be applied by Mayer rod, reverse gravure, slot die, air knife, or spray, provided that the wet film is kept above MFFT until the first drying zone. In double-sided roll-to-roll coating, a first impingement zone at 60 °C to 80 °C removes surface water without skinning; a subsequent zone at 90 °C to 110 °C completes film consolidation. Excessively rapid skinning traps water and produces blisters or interlayer delamination. The product may be formulated for pressure-sensitive tapes, paper saturation, nonwoven scrim binders, carpet backing, or heat-sealable packaging; each application changes the required tackifier, filler, and crosslinker package. In filled systems, the addition sequence should avoid direct acid filler addition because local pH depression destabilizes the latex; a pre-dispersed slurry with pH matched to the binder is preferable.
When drying ovens are retrofitted with higher-capacity infrared panels, the surface skinning defect may appear even though the total energy budget is unchanged. A staged thermal profile with low air velocity in the first zone is generally more effective than a high-temperature single-zone oven. The optimum residence time depends on web speed, coat weight, ventilation, and substrate heat capacity; no single dryer setting can be transferred between coating lines without a drying study.
In dipping operations that use a coagulant such as calcium nitrate, the tolerance of an anionic styrene-butadiene dispersion to polyvalent ions is lower than that of a nonionic stabilized latex. The coagulant bath concentration and contact time must be mapped with a mechanical stability test or pilot dip trial. Rapid destabilization at the interface may produce pinholes or a weak boundary layer in the cured film. The product specifics should be obtained from the supplier before using coagulant dipping with Resyn SB-321.
The stability of an anionic dispersion to calcium ions is not solely a function of pH; the degree of carboxylation, the distribution of carboxyl groups on the particle surface, and the presence of protective colloid alter the response. A formulation that passes a simple drawdown may still fail in a production-scale dip tank because contact time and local concentration at the meniscus are different. Pilot trials should include a worst-case hold period and not be limited to a single drawdown evaluation.
Resyn SB-321 is not a food-contact material by default; any food-contact use must be supported by a specific regulatory opinion or listing such as 21 CFR 175.105 for adhesives or 21 CFR 176.170 for paper and paperboard components, only where the manufacturer has explicitly confirmed the grade’s status. Styrene and 1,3-butadiene monomers may be present at trace residual levels in styrene-butadiene polymer dispersions. The control of residual styrene is typically performed by headspace gas chromatography or by a method derived from ISO 13741-1:1998; residual 1,3-butadiene may require a dedicated volatile organic analysis because the analyte is gaseous at room temperature. REACH obligations under Regulation (EC) No 1907/2006 apply to the product as a substance or mixture, and the presence of substances of very high concern on the Candidate List must be checked against the SDS. For electrical or electronic applications, Directive 2011/65/EU RoHS restrictions on lead, cadmium, mercury, hexavalent chromium, PBB, and PBDE apply only to homogeneous materials in final equipment; the binder is not automatically exempt.
| Regulatory domain | Standard or clause | Product-specific status for Resyn SB-321 |
|---|---|---|
| Food-contact adhesives | 21 CFR 175.105 | Requires manufacturer confirmation |
| Paper and paperboard | 21 CFR 176.170 | Requires manufacturer confirmation |
| REACH registration | Regulation (EC) No 1907/2006 | Check SDS and Candidate List |
| RoHS restriction | Directive 2011/65/EU | Final homogeneous material dependent |
| VOC determination | ASTM D3960 or ISO 11890-1 | Formulation-dependent |
Because the butadiene segment contains carbon-carbon unsaturation, dried films based on styrene-butadiene binders are susceptible to oxidative attack; hydroperoxide formation can lead to tack loss or yellowing. Antioxidants and UV stabilizers are normally added at the formulation stage. Accelerated aging may be performed under ASTM G154 or ISO 4892-3 to rank formulations, but no universal pass criterion applies. For exterior exposure, published data for Resyn SB-321 in long-term weathering trials is limited.
The differences between Resyn SB-321 and other polymeric binders are process-relevant rather than purely chemical. Compared with polyvinyl acetate homopolymer emulsions, a styrene-butadiene dispersion typically shows lower water sensitivity and better adhesion to nonpolar substrates such as corona-treated polypropylene, but it requires antioxidant stabilization and may yellow on prolonged UV exposure. Compared with acrylic emulsions, the SB backbone often contributes higher initial room-temperature tack and lower raw-material cost, but exterior durability, clarity, and oxidation resistance are generally lower. Compared with solventborne styrene-butadiene rubber cements, the aqueous dispersion removes most volatile aromatic or aliphatic solvent from the application area, but it adds drying-energy demand and freeze-thaw constraints. Compared with polyurethane dispersions, Resyn SB-321 should not be expected to match abrasion resistance or adhesion to plasticized vinyl; selection must be driven by the mechanical, thermal, and regulatory requirements of the finished laminate or coated substrate. The manufacturer’s grade comparison chart should be used to distinguish SB-321 from adjacent SB-series products that differ in particle size, stabilizer chemistry, or styrene content.
When replacing a solventborne adhesive with Resyn SB-321, the line must be evaluated for drying capacity and open time. Solventborne formulations often evaporate more rapidly, while aqueous dispersions require longer residence time and larger exhaust volumes. The lower flash-fire risk of the aqueous system is offset by the requirement to manage bacterial or fungal growth in storage, which solventborne systems do not typically require.
For pressure-sensitive applications, peel adhesion is often measured under ASTM D3330/D3330M, loop tack under ASTM D6195, and shear holding power under ASTM D3654; these methods isolate the adhesive layer but cannot substitute for full laminate qualification. The values obtained are formulation-dependent and do not represent intrinsic properties of Resyn SB-321 alone.
In pressure-sensitive tape constructions, the adhesive layer is normally transfer-coated onto a release liner and then laminated; transfer coating requires a stable wet film on silicone-treated substrates where surface energy is low. Addition of a wetting agent may be necessary, but the surfactant can migrate to the adhesive-substrate interface and reduce adhesion. The formulator should test aged adhesion after 24 h and 72 h conditioning, not only initial peel.
