| HS Code | 955844 |
| Product | S-LEC BL-2H |
| Chemical Family | Polyvinyl butyral (PVB) |
| Appearance | White powder/granule |
| Specific Gravity | 1.10 |
| Refractive Index | 1.488 |
| Glass Transition Temperature | 70 °C |
| Tensile Strength | 40 MPa |
| Elongation At Break | 200% |
| Hydroxyl Content | 30 mol% |
| Acetyl Content | 2 mol% |
| Butyral Content | 68 mol% |
| Solubility | Soluble in alcohols, ketones, and esters; insoluble in water |
As an accredited S-LEC BL-2H factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | S-LEC BL-2H is supplied as granular resin in 25 kg multi-layer paper bags, ensuring safe handling and storage. |
| Container Loading (20′ FCL) | The S-LEC BL-2H (PVB resin) loaded in 20' FCL, typically packed in bags on pallets, ensuring safe and stable transport. |
| Shipping | S-LEC BL-2H is a polyvinyl butyral (PVB) resin supplied as a free-flowing powder. Ship in dry, sealed containers to prevent moisture absorption. Protect from heat, ignition sources, and mechanical damage. No special hazardous transport classification is typically required under normal conditions. Handle with standard industrial hygiene practices. |
| Storage | Store S-LEC BL-2H in a cool, dry, well-ventilated area, away from heat, ignition sources, and direct sunlight. Keep the container tightly closed to prevent moisture absorption and contamination. Avoid contact with strong oxidizers and acids. Maintain stable temperatures, ideally below 30°C, and protect from physical damage. Use proper labeling and segregate from incompatible materials. |
| Shelf Life | Shelf life is typically 2 years from manufacture when stored unopened in a cool, dry place away from moisture. |
On automotive glazing lines where PVB interlayer film is produced from S-LEC BL-2H, jumbo rolls are slit to cut-size blanks and conditioned in a lay-up room at 18–20 °C and 23–28 % RH before sandwich assembly between two soda-lime glass plies. The glass surfaces are washed with deionized water at 40–60 °C, and the tin-side float surface is treated with a dilute silane or adhesion-control primer only when required by the glass supplier. The interlayer film formulation typical for standard windscreens contains plasticizer at 28–38 phr, magnesium or potassium acetate adhesion-control salts at 10–90 ppm equivalent metal ion, and a benzotriazole UV absorber at 0.15–0.40 wt% of film weight. After de-airing by vacuum bag at 0.1–0.4 MPa equivalent differential, the stack is autoclaved at 130–140 °C and 1.2–1.5 MPa for 60–120 min, followed by slow cooling below 40 °C before unloading to prevent optical distortion. The finished laminate is tested for luminous transmittance, optical deviation, and pummel adhesion at -18 °C; pummel values are typically maintained between 3 and 7 to balance impact retention and long-term adhesion. Compliance requires whole-glazing homologation under ECE R43 or FMVSS 205, with interlayer material rated against EN ISO 12543-2:2021 for tensile and optical properties and ANSI Z97.1 for North American replacement glazing. Process control limits are imposed because PVB film moisture above 0.45 wt% produces steam voids during autoclave, while moisture below 0.25 wt% reduces impact toughness; compounding of S-LEC BL-2H with plasticizer in a twin-screw extruder should not exceed melt temperature 200 °C to avoid acetal hydrolysis and residual acetaldehyde rise above 50 ppm. End products include laminated windshields, sidelites, and panoramic roof panels with nominal interlayer thickness of 0.76 mm, increasing to 0.84–1.52 mm for acoustic and head-up-display variants.
The laminated safety glass segment for façades, balustrades, and overhead glazing uses PVB interlayer film compounded from S-LEC BL-2H and plasticizer at 18–30 phr to retain stiffness under continuous service temperatures that can reach 50–70 °C on sun-exposed glass. Architectural interlayers are produced by twin-screw compounding and flat-die extrusion to a thickness tolerance of ±0.025 mm, then wound onto cores with controlled interleave moisture below 0.35 wt%. Laminated panels are assembled by nip-roller pre-press at 120–160 °C surface temperature, followed by autoclave at 135–140 °C and 1.2–1.4 MPa. For large-area panels, the pressure ramp is limited to 0.1 MPa/min to avoid glass edge stress. Compliance for the interlayer is anchored to EN ISO 12543-4:2021 for durability under high-temperature, humidity, and radiation cycling; safety glazing testing follows EN 12600:2002 for pendulum impact. In North America, CPSC 16 CFR 1201 and ANSI Z97.1 define safety glazing acceptance, while load resistance design uses ASTM E1300. End product types include laminated glass floors and stair treads, hurricane-resistant glazing, sound-control curtain wall panels, and glass balustrades with interlayer thickness typically 1.52 mm for commercial façades and 2.28 mm or more for structural balustrade systems.
| Qualification target | Standard/method | Test condition or clause |
|---|---|---|
| Interlayer durability | EN ISO 12543-4:2021 | High-temperature, humidity, and radiation cycling |
| Safety glazing impact | EN 12600:2002 | Pendulum impact with drop heights from 190 mm to 450 mm |
| US safety glazing | CPSC 16 CFR 1201 | Impact and environmental conditioning |
| Glass load resistance | ASTM E1300 | Uniform load on rectangular glass |
The higher mean sheet thickness requirement in architectural glazing is driven by post-breakage retention and deflection service loads rather than passenger head impact. Edge sealant compatibility is an operational boundary: amine-catalyzed silicone sealants can soften PVB at the edge, so neutral-cure silicones are specified. Published data for specific load-bearing performance under prolonged static loads is available through interlayer manufacturer technical bulletins.
In multilayer ceramic capacitor and LTCC substrate production, S-LEC BL-2H is used as a high-molecular-weight PVB binder in tape casting slips formed from barium titanate or glass-ceramic powders. The binder addition ratio is 4–8 wt% relative to ceramic powder; plasticizer content is 30–50 wt% of binder weight; and the solvent system is a toluene/ethanol azeotrope or toluene/isopropanol blend at 60–70 wt% of total slip. A representative slip is prepared in a bead mill using 1–2 mm zirconia media at 40–60 % mill load for 24–48 h, then de-aired at 200–500 Pa residual pressure until viscosity stabilizes. The slip is cast by doctor blade onto silicone-coated PET carrier with a wet gap of 50–300 μm, dried through a three-zone oven at 60–90 °C, and stripped as green tape of 20–150 μm dry thickness. The green tape must exhibit tensile strength above 2–3 MPa and elongation above 10 % to survive via punching, screen printing, and stacking. Binder burnout is performed in air or inert atmosphere with a controlled ramp of 0.5–2 °C/min through 250–350 °C where PVB decomposes; residual carbon after sintering is specified below 0.05 wt%. Fired components are qualified by end-use standards such as IEC 60384-22:2019 for surface-mount multilayer ceramic capacitors or customer-specific LTCC module tests; no global standard governs the PVB binder alone. End products include X5R/X7R multilayer ceramic capacitors, LTCC antenna modules, chip inductors, and ceramic substrates for power modules. When the binder addition exceeds 8 wt%, green tape stiffness increases but burnout emits higher volatile load and can produce delamination defects; below 4 wt%, tape edge cracking and carrier release failures occur. Optimization for S-LEC BL-2H in any given tape casting line requires plant trial because particle surface chemistry and powder deagglomeration history shift the viscosity window; published data for this specific grade in LTCC formulations is limited. Storage of slit green tape below 30 % RH is recommended because PVB absorbs water and changes dimension.
In two-package etch primers, S-LEC BL-2H is dissolved in a base component containing isopropanol and n-butanol at 6–9 wt% of total base resin solids, along with corrosion-inhibitive pigment at 7–12 wt% and talc at 1–4 wt%. The acid component is phosphoric acid diluted in isopropanol at 10–20 wt% acid concentration; mixing ratio is 4:1 by volume base to acid, producing pot life of 6–8 h at 25 °C. The primer is spray-applied at 8–12 μm dry film thickness on steel prepared to Sa 2.5 per ISO 8501-1 or on aluminum after chromate-free conversion coating. Flash-off time before topcoating is 15–30 min at 20–25 °C and 40–60 % RH. The PVB film functions as an adhesion-promoting and passivating layer between the substrate and the subsequent epoxy or polyurethane topcoat. Compliance is tied to coating system qualification under ISO 12944-5:2019 for atmospheric corrosivity categories C2–C4 and adhesion verification under ASTM D4541; specifications requiring chromium(VI)-free systems substitute zinc tetroxychromate with calcium strontium zinc phosphosilicate to meet REACH Annex XVII restrictions. Over-application above 15 μm shifts failure mode to cohesive failure within the primer; under-application below 5 μm reduces scribe creep resistance under ISO 9227 neutral salt spray below 300 h. End products include structural steel bridge primers, aircraft aluminum skin pretreatment, and primers for galvanized HVAC ductwork.
PVB resin meeting packaging migration limits is used as a film-forming binder in solvent-based flexographic and gravure inks at 5–12 wt% of total wet ink. The solvent blend of ethanol, ethyl acetate, and isopropanol accounts for 60–75 wt%; pigments are dispersed at 15–25 wt% in a bead mill with jacket temperature 40–50 °C. The ink is printed on corona-treated BOPP or PET at 150–350 m/min flexographic speed, with inter-deck drying at 60–100 °C web temperature. For food-contact packaging, compliance assessment references FDA 21 CFR 175.300 for resinous coatings and Regulation (EU) 10/2011 for plastic materials and articles intended to come into contact with food; final migration testing is performed on the printed laminate, not on the resin alone. The downstream process includes lamination of the printed web to a sealing film using solvent-free or waterborne adhesives. End products include surface-printed confectionery wrappers, pet food bag stock, and stand-up pouch outer webs where PVB contributes film adhesion and scuff resistance. Published data specific to S-LEC BL-2H in high-speed solvent-based ink applications is limited; therefore press trials should evaluate resolubility, plate open time, and final residual solvent below 5 mg/m² per converter specifications.
In building-integrated photovoltaic module lines, PVB encapsulant film is compounded from S-LEC BL-2H with plasticizer at 15–25 phr, a silane coupling agent at 0.1–0.5 wt%, and a UV/heat stabilizer package at 0.2–0.5 wt%, then extruded into film of 0.76–1.14 mm thickness. The PVB film is laminated over the cell string between glass and either glass or a transparent polymer backsheet in a vacuum laminator at plate temperature 135–145 °C for 20–40 min, followed by autoclave at 0.9–1.2 MPa to remove residual microvoids and to establish interfacial bonding. Unlike crosslinked polyolefin encapsulants, PVB does not require peroxide cure, so lamination time is governed by melt flow and glass wet-out rather than cure conversion. Finished modules are qualified under IEC 61730-1:2016 for safety, IEC 61215-1:2021 for design qualification, and UL 1703 for North America where applicable. Moisture control is critical: PVB film stored above 0.4 wt% moisture content can foam during lamination; film storage at 10–20 °C in sealed aluminum barrier packaging is required. Processing above 160 °C accelerates acetic acid formation and delamination risk. End products include glass-glass BIPV spandrel panels, skylight PV units, and balcony railing PV elements. Published data specific to S-LEC BL-2H in BIPV encapsulant film is limited; the grade selection is generally determined by plasticizer uptake, hydroxyl content, and viscosity stability.
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S-LEC BL-2H is a polyvinyl butyral (PVB) interlayer film supplied by Sekisui Chemical for the manufacture of laminated glass and laminated safety glass. The product belongs to the S-LEC BL series, and the 2H suffix is commonly interpreted by downstream processors as a two-ply nominal build-up of 0.76 mm when the film is used in standard PVB lamination stacks. The manufacturer’s current technical data sheet remains the controlling document for exact thickness, width, roll length, residual moisture, and edge condition. The film is produced as a plasticizer-compounded thermoplastic interlayer with controlled surface roughness to support air egress during vacuum-bag or nip-roller pre-lamination. The polymer matrix is PVB resin compounded with plasticizer, antioxidants, and grade-dependent additives. Because PVB is a viscoelastic thermoplastic, its processing window, adhesion to glass, and optical performance are coupled to residual moisture, plasticizer migration, and thermal history.
De-airing is the first critical control point. The as-cast film is intentionally embossed with a surface roughness profile; during pre-lamination, the roughness channels allow trapped air to escape before the glass and interlayer enter the autoclave. Cold de-airing is typically run at 0.085–0.095 MPa absolute pressure and 10–25 °C for 15–45 min. Warm de-airing, when required for thick stacks or complex curvatures, is commonly carried out at 60–90 °C under similar vacuum. Failure to complete this step produces edge bubbles and visible optical defects after autoclave.
Autoclave cycles for PVB interlayers are typically held at 1.1–1.3 MPa and 130–145 °C for 60–120 min. The pressure ensures bubble dissolution and intimate contact between the PVB and the glass surface, while temperature drives flow and adhesion development. On production-scale autoclaves with glass racks measuring 2.4 m × 3.6 m or larger, heating rate should be controlled to 3–6 °C/min until the load reaches set point; excessive ramp rates can create thermal gradients that cause glass breakage or non-uniform interlayer flow. Published lot-specific viscosity data for BL-2H is limited; therefore, initial ramp-rate and soak-time settings should be verified with a full-size trial.
Vacuum-bag lamination of curved parts uses a silicone membrane of 60–80 Shore A hardness. The membrane must conform to concave curves without trapping air pockets at the glass edges; if the membrane is too stiff, edge bubbles persist. Nip-roller systems with 60–80 Shore A rubber rolls and controlled gap pressure are used for flat or lightly curved parts.
Residual moisture in PVB film before lamination should be controlled to 0.4–0.6 % by mass. Higher moisture depresses glass transition temperature and can generate vapor in the autoclave, causing bubble defects; lower moisture can raise adhesion unpredictably. Glass wash rinse water should have conductivity below 20 µS/cm and near-neutral pH. Contamination from cutting or grinding fluids can lower pummel adhesion and create edge delamination. On production lines, pummel coupon tests from each autoclave load are used to detect drift before laminates are released to fabrication.
Roll conversion is performed on slitter/winders with shear or crush-cut blades; slit edge quality affects lay-up speed and edge sealing. For PVB film of 0.76 mm nominal thickness, typical slit width tolerance is ±2 mm, but tighter tolerances may be required for automated lay-up. The film is shipped in a moisture-barrier bag with desiccant; once opened, the roll should be used within 72 h or re-sealed under nitrogen. Storage at 5–25 °C and 20–60 % relative humidity minimizes blocking and moisture regain. Above 60 % relative humidity, pre-drying at 30–40 °C for 24–48 h may be required before lay-up.
The following table is a representative range for plasticized PVB interlayers in the S-LEC family. Product-specific values for BL-2H must be taken from the current datasheet or certificate of analysis.
| Property | Test method | Typical range or value |
|---|---|---|
| Density | ISO 1183-1 | 1.07–1.10 g/cm³ |
| Tensile strength, machine/transverse direction | ISO 527-3 | 20–30 MPa |
| Elongation at break, machine/transverse direction | ISO 527-3 | 200–350 % |
| Haze | ASTM D1003 / ISO 14782 | 0.3–1.0 % |
| Luminous transmittance, clear unpigmented film | ISO 9050 | 88–91 % |
| Glass transition temperature | DSC | 20–30 °C |
For tinted PVB interlayers, visible transmittance and solar absorption are modified relative to clear PVB. Processors should obtain the spectral transmittance curve for BL-2H from the manufacturer and calculate luminous transmittance, solar direct transmittance, and g-value according to ISO 9050 or EN 410. Published spectral data for this specific grade is limited; glazing energy calculations should not default to clear-PVB optical values.
Adhesion to glass is not captured by tensile or optical data alone. In PVB lamination, adhesion is routinely measured by the pummel test, in which the laminate is fractured and the exposed PVB-to-glass adhesion is rated on a 0–10 scale. Controlled-adhesion PVB grades commonly fall between 3 and 7 pummel units, depending on glass tin side, rinse water quality, drying conditions, and autoclave soak time. S-LEC BL-2H is positioned as a controlled-adhesion interlayer, but the exact pummel target for a specific application must be derived from the manufacturer’s adhesion-control chart and validated on the intended glass line. Adhesion changes of ±1 pummel unit can result from variations in glass washing water conductivity above 20 µS/cm, from residual cutting oil, or from changes in autoclave hold temperature of 5 °C.
PVB interlayer flow in the autoclave is shear-thinning and temperature-dependent. Apparent viscosity at processing temperatures is commonly reported in the range of 10⁴–10⁶ Pa·s at low shear rates, but the exact value for BL-2H is not publicly available. This high viscosity means that PVB does not flow to fill large gaps between glass plies; thickness uniformity, glass flatness, and clean lay-up are more important than in low-viscosity encapsulants.
Laminated safety glass containing PVB interlayers is classified for impact performance under EN 12600. The pendulum test uses a 50 kg impactor dropped from 190 mm, 450 mm, and 1200 mm, yielding classifications 3B3, 2B2, and 1B1. A laminate build of 4 mm glass / 0.76 mm PVB / 4 mm glass typically passes a 2B2 requirement, but the specific classification is not purely additive and must be confirmed by destructive testing on the intended glass type and interlayer lot. Automotive glazing under ECE R43 imposes additional optical, environmental, and fragmentation requirements. The interlayer contributes to retention and occupant protection, while the glass-PVB bond level must be sufficiently high to prevent delamination under high-speed impact but controlled enough to allow the required fracture behavior.
For larger architectural panels, the glass stiffness and PVB shear transfer affect deflection and post-breakage behavior. PVB is a viscoelastic interlayer; its shear modulus is temperature- and load-duration-dependent. At short load durations and ambient temperature, the interlayer behaves stiffer than under long-term lateral loads. This response is relevant when laminated glass is specified for overhead glazing or balustrades. The governing product standard for architectural laminated glass is ISO 12543; impact classification is typically determined by EN 12600. Published data for BL-2H in specific structural glass configurations is limited.
Edge sealant compatibility must be evaluated before installation. Neutral-cure silicone sealants are generally compatible with PVB interlayers; acid-cure silicone, amine-containing curing agents, and certain polysulfides can accelerate plasticizer migration, causing edge cloudiness or adhesion loss. For structural glazing or wet-edge conditions, a factory-applied edge deletion of 2–5 mm is often specified to prevent direct sealant-PVB contact. This dimension depends on the sealant manufacturer’s testing and the glass make-up, not on the interlayer grade alone. Edge deletion can be performed by mechanical abrasion or solvent wiping. For PVB interlayers, solvent-assisted deletion using ethanol or isopropanol is common, but solvent penetration beyond the deletion zone can alter local adhesion. Therefore, the deletion depth and width should be verified by UV fluorescence or peel testing on a first-article basis.
Plasticizer migration to the laminate edge is a slow, temperature-activated process. At sustained temperatures above 50 °C, edge clouding can develop over months in inadequately sealed laminates. This is not a defect unique to BL-2H but a general limitation of plasticized PVB. For exterior glazing, adequate edge cover, proper sealant compatibility, and avoidance of standing water are required.
Within the S-LEC PVB family, clear standard grades are used for general laminated glass; acoustic grades incorporate a soft viscoelastic core layer that increases sound transmission loss in the 1000–3000 Hz coincidence-dip region. UV-blocking grades contain additional organic absorbers to reduce UV transmittance below 380 nm. Standard PVB already absorbs a significant fraction of UV radiation below 380 nm; the distinction for UV-specific grades is the sharper cut-off and long-term retention of the absorber system. BL-2H differs from these grades by its BL-series optical or adhesion configuration, but the precise delta in transmittance, haze, and pummel adhesion requires the manufacturer’s comparative datasheet. Publicly available third-party comparative data for this specific grade is limited.
| Standard or regulation | Application context | Relevant requirement |
|---|---|---|
| ISO 12543-1 / -2 / -3 | Architectural laminated glass | Definitions, safety, durability, and component requirements |
| EN 12600 | Pendulum impact classification | Classes 3B3, 2B2, 1B1 |
| ECE R43 | Automotive safety glazing | Impact, optical, environmental resistance |
| ANSI Z26.1 | US motor-vehicle safety glazing | Equivalent safety glazing performance |
| REACH (EC 1907/2006) | Chemical substances in articles | Registration, authorization, and restriction duties |
| RoHS 2011/65/EU | Hazardous substances | Pb, Cd, Hg, Cr VI, PBB, PBDE restrictions |
Application scope for S-LEC BL-2H includes architectural laminated glass, automotive side and roof glazing, sloped glazing, and interior glass barriers. It is not a replacement for acoustic interlayers where high sound transmission loss is specified, nor for structural interlayers in blast, ballistic, or hurricane-resistant assemblies unless full-system testing demonstrates compliance. Continuous service temperatures outside -40 °C to 80 °C should be reviewed with the manufacturer, particularly when the laminate edge is exposed to moisture or organic solvents. Published data for BL-2H in severe-service configurations is limited, and qualification must be performed on the finished laminate under the applicable building or vehicle code.
