| HS Code | 787648 |
| Material | Polyvinyl butyral (PVB) |
| Thickness | 0.76 mm (standard) |
| Density | 1.07 g/cm³ |
| Refractive Index | 1.488 |
| Visible Light Transmittance | ≥88% |
| Haze | ≤1% |
| Tensile Strength | ≥20 MPa |
| Elongation At Break | ≥250% |
| Tear Strength | ≥50 kN/m |
| Glass Transition Temperature | 30°C (nominal) |
| Moisture Absorption | ≤1.5% |
| Adhesion To Glass | High (typical peel adhesion >10 N/cm) |
As an accredited S-LEC BL-1H factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | S-LEC BL-1H is packaged in 25 kg moisture-resistant multi-layer paper bags, ensuring safe delivery of the resin pellets. |
| Container Loading (20′ FCL) | S-LEC BL-1H is containerized in a 20′ FCL, with palletized bags secured and moisture-protected for safe transit. |
| Shipping | S-LEC BL-1H is a polyvinyl butyral resin supplied as a free-flowing white powder. Ship in sealed, moisture-proof packaging such as lined bags or drums. Protect from water, humidity, and direct sunlight. Avoid high temperatures and open flames. Keep upright during transport in a clean, dry, well-ventilated area. |
| Storage | Store S-LEC BL-1H in a cool, dry, well-ventilated area away from direct sunlight, heat sources, and open flames. Keep the original container tightly sealed to prevent moisture absorption and contamination. Avoid dust accumulation on surfaces. Follow local regulations for chemical storage and handling. Keep out of reach of unauthorized personnel. |
| Shelf Life | Store in a sealed container in a cool, dry place; typical shelf life is two years from manufacture. |
In non-aqueous tape casting of barium titanate formulations for multilayer ceramic capacitors, doctor-blade splitting instability manifests as longitudinal ribbing and edge-thickness deviation when viscous shear stress at the blade lip exceeds the yield stress of the green sheet slurry. S-LEC BL-1H polyvinyl butyral resin is introduced at 8–12 phr relative to ceramic powder mass; the accompanying ester plasticizer is maintained at 3–6 phr, and the solvent system is azeotropic toluene/ethanol at 55:45 volume ratio. The slurry is dispersed in a zirconia-lined bead mill at 1,200–1,800 rpm with 2 mm zirconia media until the viscosity stabilises between 800–2,500 mPa·s at 10 s⁻¹, then deaerated under 10–20 kPa vacuum for 30–45 min. Casting proceeds through a doctor blade with a gap set between 25–150 μm on a Mylar or stainless-steel carrier at line speeds of 0.4–1.5 m/min; multi-zone drying between 60–90 °C is staged so that the top surface remains open while residual solvent drops below 1 wt%. The green tape is then slit, laminated at 60–80 °C under 10–20 MPa, and sintered with a debinding plateau at 300–450 °C to remove the PVB without leaving more than 0.5 wt% residual carbon. Finished components include multilayer ceramic capacitors in metric footprints from 0.4 mm × 0.2 mm to 3.2 mm × 2.5 mm and low-temperature co-fired ceramic substrates for RF modules. Compliance references for the dielectric components are IEC 60384-1:2021 and IEC 60384-22:2019; materials controls follow REACH Annex XVII and RoHS 2011/65/EU. The system should not be mixed with amine-functional dispersants because acetal ring opening accelerates and the slurry thickens beyond pumpability within 6–8 h at 25 °C.
The primary adhesion-limiting variable is the exact ratio of phosphoric acid etchant to polyvinyl butyral carrier solids, since too little acid leaves zinc oxide scale and too much acid precipitates the resin as a gelled phase. S-LEC BL-1H is dissolved into a mixture of isopropanol, n-butanol, and methyl ethyl ketone at 5–9 wt% of the total liquid; phosphoric acid 85% is added at 2–4 wt%, and anti-corrosive pigment is incorporated at 5–10 wt%. The substrate is prepared to Sa 2½ according to ISO 8501-1, and the mixed primer is sprayed with an HVLP gun at 0.18–0.28 MPa cap pressure to a dry film thickness of 8–15 μm; induction before application is 20–30 min, pot life at 25 °C is 8 h, and the overcoat window is 4–24 h at 23 °C and 50% RH. The primed substrate is normally topcoated without sanding to avoid cutting through the passivation layer. Compliance testing follows ISO 12944-5:2019 for protective paint systems, ASTM D3359-23 for cross-cut adhesion, and ASTM B117-19 for salt spray resistance. Terminal products include automotive refinish, structural steel, aircraft aluminium, and galvanised cladding. Operational boundaries: dry film thickness above 15 μm produces cohesive failure under humidity load, and contact with amine-cured epoxies should be delayed until the acid is fully reacted; otherwise intercoat blistering occurs within 72 h of immersion exposure.
For flexographic inks on corona-treated polyolefins, solvent release and rub resistance are controlled by the molecular weight of the polyvinyl butyral binder and the true solvent fraction remaining after the final print station. S-LEC BL-1H is used at 5–10 wt% of the finished ink, with pigment loading between 20–35 wt% and solvent blend consisting of ethyl acetate, ethanol, and n-propanol in a 65:25:10 volume ratio. The ink is dispersed on a horizontal bead mill with 1.0–1.4 mm yttria-stabilised zirconia media at 30–40 °C, adjusted to printing viscosity of 25–45 s Zahn cup #2, and transferred via chambered doctor blade onto 360–440 lpi anilox rolls at press speeds of 150–300 m/min. Drying is performed at 60–80 °C with an impingement velocity of 20–30 m/s, maintaining total retained solvent below 2 wt% before the substrate enters the rewind. Terminal printed structures include BOPP, PET, LDPE, and top-coated paper labels. Compliance for printing machinery is ISO 12643-1:2023; indirect food-contact printed packaging must meet Regulation (EC) No 1935/2004 and EC 2023/2006 GMP, with route-specific migration assessment under EU 10/2011 where a plastic food-contact layer is involved. Operational limitations: an alcohol-rich true solvent fraction above 80% causes ink blushing on gravure cylinders, and residual water above 0.5 wt% in the solvent blend promotes gelation during prolonged press stoppages longer than 30 min.
Published data for this specific BL-1H extrusion formulation is limited; the following ranges derive from standard PVB interlayer compounding practice and should be confirmed against Sekisui grade-specific technical service approvals. The resin is dry-blended with triethylene glycol bis(2-ethylhexanoate) at 26–32 phr based on resin mass, with optional UV stabiliser added at 0.1–0.5 phr. Compounding uses a co-rotating twin-screw extruder with L/D 44:1 and a segmented barrel profile of 140–190 °C; the melt is filtered through 250 μm screen packs and delivered to a coat-hanger sheet die at 150–170 °C. The die lip gap is 0.5–0.8 mm, and quenching is performed on polished chill rolls at 15–30 °C to control residual stress. Extruded interlayer thickness is 0.38–1.52 mm, with caliper tolerance of ±0.02 mm maintained by a beta gauge upstream of the winder. Lamination of glass-interlayer-glass assemblies occurs in an autoclave at 12–14 bar and 130–140 °C for 60–120 min. Final products include automotive windshields, architectural laminated glass, and ballistic/security glazing. Compliance references include ISO 12543-1:2021, UN Regulation No. 43 for windscreen light transmission and fragmentation, and ANSI Z26.1 for North American glazing materials. The resin must be pre-dried to <0.5 wt% moisture at 50–60 °C for 4 h when ambient RH exceeds 60%; otherwise hydrolysis lowers molecular weight and creates visible bubbles at the glass interface during autoclave heating. Aliphatic amine-based silane adhesion promoters should be excluded from the compounding recipe because alkaline residues catalyse acetal hydrolysis and reduce interlayer tensile strength measured by ASTM D638-14 after 1,000 h of 85 °C oven ageing.
On magnetic stripe and high-coercivity ticket coating lines running at 100–200 m/min, S-LEC BL-1H functions as a binder matrix holding acicular gamma-Fe₂O₃ or doped Fe-Co pigments in a 10–30 μm dried film. The formula addition ratio is 10–18 wt% binder solids relative to total coating solids, with magnetic pigment loading at 50–65 wt% and a methyl ethyl ketone/toluene 80:20 solvent system. Dispersion is carried out in a horizontal sand mill with zirconia media 1.2–1.6 mm at chamber temperature 40–50 °C, followed by gravure or slot-die coating onto PVC, PET, or composite card stock and calendering between heated steel rolls at 60–80 °C under linear pressure 300–500 kN/m. The coated substrate is then slit and magnetically encoded. Compliance for the finished card is verified against ISO/IEC 7811-2:2018 for low-coercivity magnetic stripe encoding, ISO/IEC 7811-6:2018 for high-coercivity media, and ISO/IEC 10373-2:2018 for test methods. Terminal products include hotel key cards, bank and transit cards, gift cards, and access-control badges. Operational boundaries: residual solvent above 2 wt% after drying causes blocking on the take-up reel, and the binder must not be combined with amine-catalysed topcoats because they soften the PVB matrix within 24 h at 45 °C.
When a ceramic frit paste is screen-printed onto automotive glazing prior to bending and tempering, S-LEC BL-1H is incorporated at 5–12 wt% of wet paste while the low-melting glass frit or black pigment is 70–80 wt%, and the solvent fraction is 10–20 wt%. The paste is three-roll milled through a 5 μm gap to a Hegman gauge reading of at least 6, then screen-printed through 80–150 mesh polyester or stainless screens onto the inner surface of the glass. Drying at 150–200 °C removes solvent; subsequent firing in an infrared or gas furnace at 600–700 °C sinters the glass frit, while the PVB decomposes completely between 250–400 °C. Residual carbon from incomplete burn-off must remain below 0.2 wt% or the enamel line darkens along the frit edge. Compliance references for the final glazing include UN Regulation No. 43 for light transmittance and mechanical resistance and ISO 3537:2015 for glazing tests; production of the paste itself is controlled under REACH and RoHS 2011/65/EU where the finished component is sold into the EU market. Terminal products include windshield obscuration bands, defogger and antenna enamel patterns, and side-lite privacy or decorative frames. Operational boundaries: binder loadings above 15 wt% generate gas bubbles during firing, and ambient storage of the paste above 30 °C shortens press-ready viscosity stability to 6–8 h.
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S-LEC BL-1H is a polyvinyl butyral resin manufactured by Sekisui Chemical Co., Ltd. through acid-catalyzed acetalization of polyvinyl alcohol with n-butyraldehyde. The grade is positioned in the low-viscosity segment of the S-LEC B series and is supplied as a white powder or granular solid. Compositional control focuses on residual hydroxyl content, butyral ring content, and acetyl content; these substituents govern solubility in ethanol/toluene blends, pigment wetting, adhesion to metals and polar substrates, and reactive site density for thermosetting crosslinkers. Routine lot certification includes non-volatile content, loss on drying, rotational solution viscosity, free acidity, and ash content. Non-volatile content is tested according to ISO 3251:2019. Solution viscosity is measured after dissolution at 10% non-volatile content in a 1:1 by mass ethanol/toluene mixture at 20°C following ASTM D2196-20 Method A.
Lot acceptance for low-viscosity PVB resins relies on solution viscosity rather than melt index because the polymer is normally processed from organic solvent. The 10% solution viscosity of BL-1H remains below 50 mPa·s in the ethanol/toluene blend at 20°C; the exact acceptance band is established on the producer’s certificate of analysis because standard technical bulletins do not publish a single fixed midpoint for every production lot. By comparison, medium-viscosity BM grades are commonly reported between 45 mPa·s and 70 mPa·s, and high-viscosity BH grades range from 180 mPa·s to 280 mPa·s under the same test conditions. Glass transition values measured by differential scanning calorimetry per ISO 11357-2:2020 are typically reported in the 55°C to 70°C interval at 10 K/min for low-hydroxyl PVB resins, but BL-1H should be verified against the lot-specific Tg result because residual hydroxyl content and acetal distribution shift the transition. Hydroxyl content is usually determined by near-infrared or titration methods calibrated against the producer’s reference polymer; published data for the exact BL-1H configuration remain limited. Table 1 summarizes class-typical bands for comparative qualification.
| Property | Test standard | BL-1H class | BM series | BH series |
|---|---|---|---|---|
| Solution viscosity at 10% non-volatile content, 1:1 ethanol/toluene, 20°C | ASTM D2196-20 | 5–25 mPa·s | 45–70 mPa·s | 180–280 mPa·s |
| Glass transition temperature | ISO 11357-2:2020 | 55–70°C | 65–75°C | 68–78°C |
| Non-volatile content | ISO 3251:2019 | ≥98% | ≥98% | ≥98% |
| Solution appearance after 10 µm filtration | Producer specification | transparent to slight haze | transparent | transparent |
The lower solution viscosity of BL-1H reduces solvent demand at a given non-volatile content; this is the principal selection driver in high-solids coatings and inks where volatile organic compound limits constrain formulation latitude. Because exact viscosity ranges depend on production lot, a feedstock specification should always supersede the class-typical bands shown above.
In flexographic and gravure packaging inks, low-viscosity PVB binders are introduced when nitrocellulose and acrylate binders show insufficient adhesion to metallized polyethylene terephthalate or corona-treated polyolefin film. BL-1H is typically dissolved with a co-solvent blend of ethanol and ethyl acetate to a resin concentration between 8 wt% and 15 wt% depending on press viscosity limits. Dispersion is performed in a bead mill with the PVB binder present in the vehicle to limit reagglomeration; grind fineness is checked by Hegman drawdown according to ASTM D1210-21. Target values below 10 µm are common for gravure inks. Efflux time through a DIN EN ISO 2431:2020 cup with a 4 mm orifice is adjusted to 18–24 s at 23°C for flexographic applications. On a Windmöller & Hölscher Miraflex CM flexographic press running at 150–250 m/min, ink transfer and dot reproduction are sensitive to solvent retention; high-molecular-weight BH grades tend to increase retarded-solvent retention and block resistance loss under the same drying airflow. BL-1H reduces viscosity build at equivalent binder solids and permits higher pigment loading while maintaining more Newtonian flow under high shear. Print adhesion is evaluated by cellophane tape pull after 24 h conditioning at 23°C and 50% relative humidity; results on treated polyethylene should meet ASTM D3359-23 classifications 5B or 4B depending on surface energy. The low molecular weight reduces cratering on films but also lowers final film cohesive strength; therefore, BL-1H is generally not used as the sole binder in retortable lamination inks without an additional crosslinker or higher-molecular-weight PVB resin.
Metal pretreatment wash primers convert rusted or weathered steel surfaces and provide a temporary corrosion-inhibiting film. The pigment system is typically composed of zinc phosphate or zinc tetroxychromate, phosphoric acid at 0.5–2.0 wt% of formulation, and the PVB binder dissolved in ethanol/toluene. The acid moiety reacts with steel to form an iron phosphate conversion layer; PVB film formation then seals the surface against oxygen and moisture ingress. BL-1H is used at 8–12 wt% non-volatile content on total formulation, and wire-wound drawdown panels are cured at 150°C metal temperature for 10–20 min. Salt spray resistance is measured according to ISO 9227:2022; scribe creep at 240 h is often below 2 mm when the formulated primer is applied at 8–10 µm dry film thickness on blasted carbon steel. If the acid concentration is excessive, ethanol/toluene solutions can show viscosity drift after 72 h storage at 40°C, because acetal linkages in the PVB backbone undergo acid-catalyzed hydrolysis; published data for the exact rate under BL-1H lot-specific hydroxyl content is limited. The difference from BM and BH grades is mainly observed in spray and dip application. High-molecular-weight grades produce pinhole-free films at higher thickness but require lower solids and more solvent; BL-1H can be sprayed at higher solids without excessive viscosity, reducing volatile organic compound emissions in air-spray booths. Film hardness and solvent resistance after crosslinking with phenolic or melamine resins are determined by methyl ethyl ketone double rubs per ASTM D5402-19. Table 2 consolidates the principal compliance designations for industrial formulations containing BL-1H.
| Control domain | Reference designation | Application check for BL-1H-containing formulations |
|---|---|---|
| Volatile organic compounds in coatings | EU Directive 2004/42/EC | Solvent-borne wash-primer and coating categories require VOC mass balance; use ISO 11890-2:2020 for determination. |
| Heavy metal restrictions in electrical and electronic equipment | RoHS Directive 2011/65/EU | Lead, cadmium, mercury, hexavalent chromium, PBB, and PBDE limits apply to formulated coatings on EEE; raw lot should be free of restricted pigments and stabilizers. |
| European chemicals restriction screening | REACH Regulation (EC) No 1907/2006, Annex XVII | Check restricted phthalates, alkylphenol ethoxylates, and any intentionally added Annex XIV substances in solvent and additive packages. |
| Food-contact adhesives and coatings | FDA 21 CFR 175.105 / EU Regulation (EU) No 10/2011 | Verify that the migrated fraction of unreacted aldehydes and PVB additives does not exceed specific migration limits in the intended food simulant. |
| Neutral salt spray exposure | ISO 9227:2022 | Scribe creep and blistered area are contractually defined; original equipment manufacturer approvals may require automotive tri-cation phosphate panels. |
Solubility of BL-1H is strong in lower alcohols, glycol ethers, ketones, and aromatic/alcohol co-solvents; aliphatic hydrocarbons and water are non-solvents and function as diluents. Cloud point titration with n-heptane or toluene is used to define the precipitation boundary for lot acceptance; the Hansen solubility parameter distance between the polymer and solvent blend controls the margin before gel formation. In flexible packaging laminating adhesives, residual solvent in the dried PVB film must be kept below 5 mg/m² total residual volatile content when measured by headspace gas chromatography under ISO 11890-2:2020. The lower molecular weight of BL-1H accelerates solvent release in short air-float drying tunnels but also increases migration of low-molar-mass oligomers into low-density polyethylene sealant layers under heat and pressure. Migration kinetics under food-contact conditions are evaluated using EU Regulation (EU) No 10/2011 protocols with 10-day exposure at 40°C for aqueous simulants; the specific migration limit for unreacted butyraldehyde-derived substances must be confirmed against the authorized monomer and additive list. Binder selection influences heat-seal strength: a laminating formulation containing 5–10 wt% BL-1H can maintain T-peel adhesion above 2 N/15 mm on polyolefin films after 24 h at 50°C, but values decline when plasticizer migration softens the bond line. If crosslinking is required, addition of aromatic polyisocyanate at 1–3 wt% of binder solids extends creep resistance but shortens pot life below 8 h at 25°C; viscosity rise should be monitored every 30 min with a falling-sample viscometer. These operational boundaries are formulation-dependent and should be confirmed by pilot trials because lot-to-lot viscosity and hydroxyl-content variation in PVB can shift solvent release and crosslinker demand.
Batch-to-batch variance in low-molecular-weight PVB resins is most often observed as solution haze, final filtration pressure rise, and slight differences in hydroxyl-specific crosslinker demand. On a 300 L stainless steel dissolver equipped with a high-shear dispersion blade, BL-1H is dissolved into ethanol/toluene at 15°C to 25°C under nitrogen; temperatures above 40°C during resin dissolution can increase aldehyde-like odor and acid number drift. Once dissolved, the solution is passed through a 10 µm depth filter, and differential pressure across the housing is recorded; lot rejections typically occur when pressure rise exceeds 0.2 MPa before the full batch volume has passed. In ceramic tape casting, the same binder variability affects slurry rheology: a 5% shift in PVB hydroxyl content can alter binder adsorption on alumina surfaces and requires adjustment of dispersant demand in methyl ethyl ketone/ethanol slips. These practical control points explain why BL-1H is selected for high-flow coating applications rather than for high-toughness laminated glass interlayer uses; the product is not a direct substitute for high-viscosity PVB film grades used in safety glass systems tested under national laminated-glass standards.
