| HS Code | 568581 |
| Product Name | S-LEC BH-S |
| Product Type | PVB Interlayer Film |
| Material | Polyvinyl butyral resin with plasticizer |
| Appearance | Transparent |
| Density | 1.07 g/cm³ |
| Thickness | 0.76 mm |
| Width | Up to 3000 mm |
| Tensile Strength | 25 MPa |
| Elongation At Break | 280% |
| Young S Modulus | 55 MPa at 20°C |
| Glass Transition Temperature | 28°C |
| Refractive Index | 1.48 |
| Light Transmittance | 88% |
| Haze | ≤1.0% |
| Moisture Absorption | ≤0.4% |
As an accredited S-LEC BH-S factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | S-LEC BH-S is packaged in sealed 25 kg multilayer bags to protect against moisture and contamination during handling, storage, and transport. |
| Container Loading (20′ FCL) | S-LEC BH-S resin is loaded into a 20-foot container on pallets, secured firmly, with moisture protection for safe transport. |
| Shipping | S-LEC BH-S is a polyvinyl butyral resin supplied as powder/pellets. Ship in sealed moisture-proof packaging, away from heat, ignition sources, and direct sunlight. Keep dry during transit to prevent clumping or degradation. Standard non-hazardous chemical handling applies; use ventilated transport and secure loads to prevent bag damage. |
| Storage | Store S-LEC BH-S in a cool, dry, well-ventilated area, away from direct sunlight, heat, and ignition sources. Keep the container tightly sealed to prevent moisture absorption and contamination. Maintain stable temperatures and avoid exposure to humidity. Ensure compatibility with surrounding materials and follow local regulations for polymer resin storage. |
| Shelf Life | Shelf life is 24 months from manufacture when stored unopened in original packaging in a cool, dry place. |
In solvent-based flexographic and gravure packaging ink systems on corona-treated biaxially oriented polypropylene (BOPP), polyester (PET), and coextruded polyamide films, S-LEC BH-S polyvinyl butyral is introduced as a co-binder resin to improve pigment wetting, scuff resistance, and re-solubility balance during long-run printing. In a typical non-toluene solvent blend of ethanol and ethyl acetate, the resin addition level is 6 wt% to 12 wt% of total wet ink, while the PVB solution is prepared at 15%–25% solids. Ink manufacturers disperse the premix on high-shear dissolvers at 25–35 m/s tip speed; the letdown is adjusted to a flow time of 36–42 s at 25°C using a 4 mm Ford cup. Gravure printing uses 60–80 lpcm electromechanically engraved cylinders and a wet film thickness of 8–12 μm; forced-air ovens at 60–80°C remove solvent before rewind. Regarding compliance, low-migration packaging inks produced for food-contact surfaces are formulated to EuPIA guidelines and Swiss Ordinance SR 817.023.21, with REACH Annex XVII restrictions on residual monomers and solvents; where no functional barrier is present, migration testing according to EN 1186-1:2002 is required. Print adhesion on film is evaluated by ISO 2409:2013 cross-cut adhesion, and rub resistance is measured by ASTM D5264-98. Terminal products include surface-printed snack packaging, retort lidding, and monolayer lamination inks. S-LEC BH-S powder is pre-dried at 55–60°C for 4–6 h when ambient relative humidity exceeds 60% to prevent solvent-cloudy solutions; amine-functional dispersants are withheld from the premix because aldehyde-amine condensation can produce yellow chromophores and viscosity drift.
Solvent-borne anti-corrosion etch primers for ferrous and aluminum substrates use S-LEC BH-S as a film-forming resin whose pendant hydroxyl groups interact with phosphoric acid and metal oxide surfaces. The primer is prepared by dissolving PVB at 7.0 wt%–9.0 wt% of total primer weight in a 1:1:0.5 blend of isopropanol, methyl ethyl ketone, and toluene; plasticizer such as dibutyl phosphate or tricresyl phosphate is incorporated at 1.5 wt%–2.5 wt%, and then an 85% phosphoric acid solution is added at 2.5 wt%–3.5 wt% after the base solution has cooled below 35°C. High-speed dispersion at 600–900 rpm for 10–15 min produces a translucent pale yellow primer with a mixed solvent system designed to evaporate as a single wet film. Process boundaries are narrow: the acidified primer exhibits a practical pot life of 8–12 h because phosphoric acid slowly hydrolyzes the PVB acetal linkage, causing viscosity drift; published kinetic data for acid-catalyzed hydrolysis under these exact formulation conditions is limited, so viscosity is checked every 4 h using a 4 mm Ford cup. Compliance with SSPC-Paint 27 and ISO 12944-5:2019 is intended for corrosion protection on structural steel; dry-film adhesion to prepared carbon steel is evaluated by ISO 2409:2013 cross-cut, and salt spray resistance is tested per ISO 9227:2022. The terminal product range includes aluminum aircraft skin pretreatment primers, steel repair primers for maintenance, and non-chromate replacement primers for shop application; modern formulations replace zinc chromate with zinc phosphate or borosilicate inhibitors because REACH Annex XVII restricts chromate pigments. When applied via conventional air-atomizing spray at 8–12 μm dry film thickness, the primer is recoated with a compatible epoxy or polyurethane topcoat within 24 h; adhesion loss occurs on oily substrates when degreasing is incomplete.
On non-aqueous ceramic tape-casting lines producing multilayer ceramic capacitors (MLCCs), LTCC substrates, and piezoelectric actuators, S-LEC BH-S is dissolved as the primary binder phase in a 3:2 toluene/ethanol mixture to control green tape strength, flexibility, and clean thermal debinding. The addition rate is 8 wt%–12 wt% based on dry ceramic powder, with PVB solution solids fixed at 15 wt%; a phthalate plasticizer such as dibutyl phthalate is added at 30 wt%–40 wt% of the PVB mass, and a phosphate ester dispersant at 0.5 wt%–1.5 wt% of ceramic powder is milled separately. First-stage dispersion uses yttria-stabilized zirconia beads 0.3–0.5 mm in a bead mill at 1200–1500 rpm for 12–18 h; the PVB BH-S solution is then added and homogenized on a slow roll mill for 12–24 h before vacuum de-airing at 100–200 mbar. Tape casting proceeds at 0.5–1.5 m/min with a doctor blade gap of 100–300 μm, followed by three-zone drying at 60–80°C. The dominant processing cliff is binder concentration: below 7 wt% PVB, green elongation measured by ASTM D882-18 falls below 5% and edge cracking increases; above 13 wt%, green density increases but retained solvent causes closed porosity during burnout. Debinding uses a ramp of 0.5°C/min from 220°C to 450°C under air flow, with residual carbon held below 0.05 wt% by lot-wise verification. Compliance for MLCC products is governed by IEC 60384-22:2019 and user-specified AEC-Q200 qualification. Terminal products are X7R and C0G multilayer ceramic capacitors, LTCC RF modules, and piezoelectric actuators. S-LEC BH-S powder is pre-dried at 55–60°C for 4–6 h when storage RH exceeds 60% before dissolution; residual moisture above 0.3% accelerates slurry gelation and reduces lot-to-lot tape thickness reproducibility.
As a toughening polyvinyl butyral in resole phenolic adhesive solutions, S-LEC BH-S is used to bond aluminum foil to Nomex aramid paper honeycomb cores and to fabricate fire-resistant composite panels. The formulation combines S-LEC BH-S at 12–20 phr per resole phenolic solids, dissolved at 20–30% solids in methyl ethyl ketone and toluene. The adhesive is roll-coated at dry film thickness 15–25 μm onto 5052 or 3003 aluminum alloy foil; after solvent flash-off at 80–100°C for 3–6 min, the coated foil is B-staged to a tack-free state. Final cure is performed in a heated platen press at 150–180°C under 0.7–1.4 MPa for 45–90 min. Bond performance is assessed by ASTM D1002-10 single-lap shear and ASTM D1876-08 T-peel; fire-smoke-toxicity characteristics for rail or aerospace panels reference EN 45545-2:2020 and ASTM E662-19 smoke density. Compliance for fire-resistant panel markets is tied to EN 13501-1:2018 classification and surface preparation according to ISO 4588:1995. Terminal products include aluminum honeycomb sandwich panels for aircraft interiors, marine bulkheads, and architectural cladding. The operational boundary is that PVB BH-S is not formulated with amine-cured epoxy components because amine compounds catalyze PVB acetal hydrolysis and cause bond-area discoloration; storage of the adhesive solution beyond 6 months at 25°C requires viscosity re-certification per ISO 2555:2018.
Board and pharmaceutical lidding converters substituting S-LEC BH-S into solvent-based heat-seal lacquers obtain a hard, alcohol-dilutable binder with adhesion to aluminum foil, paperboard, and poly(vinyl chloride) blister webs. The resin is formulated at 20–35 wt% of dry coating solids in a mixture of ethanol and ethyl acetate; the lacquer is applied by gravure cylinder at 70–90 lpcm in a coat weight of 1.5–3.0 g/m² and dried at 70–90°C with residual solvent below 10 mg/m² before rewind. Heat sealing to 250 μm rigid PVC film is executed at 150–180°C jaw temperature under 0.3–0.5 MPa sealing pressure with 0.5–1.0 s dwell; seal strength is verified by ASTM F88/F88M-21. Compliance for food-contact board coatings requires FDA 21 CFR 175.300 and EU Regulation 1935/2004/EC Article 3; pharmaceutical blister lidding additionally uses USP <661.1> extractables assessment. Terminal finished products are push-through pharmaceutical blister foils, unit-dose lidding for clinical trials, and overprint varnishes for cosmetic cartons. The substitution is not recommended for direct-contact aqueous foodboard where PVB lacks the moisture-barrier performance of polyvinylidene chloride copolymers; published data on long-term seal integrity under tropical storage for this specific formulation is limited.
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S-LEC BH-S is a plasticised polyvinyl butyral interlayer manufactured by Sekisui Chemical Co., Ltd. for the fabrication of laminated safety glass. The material is supplied as a clear roll-form film and is typically built up in 0.38 mm thickness increments; common architectural make-ups are 0.76 mm and 1.52 mm. In the finished laminate, the film acts as both a thermoplastic adhesive and an energy-absorbing layer, bonding the glass plies after heat and pressure processing. The performance of the interlayer is evaluated in the laminated assembly, not as an isolated free film.
BH-S is produced through acetalisation of polyvinyl alcohol with butyraldehyde in an acid-catalysed reaction, followed by neutralisation, washing, and compounding with a plasticiser system before cast-film extrusion. The resulting polymer carries hydroxyl groups, butyral rings, and residual acetate groups. The hydroxyl content contributes to hydrogen bonding with silanol sites on glass and provides the controlled adhesion required for safety glazing. The grade does not incorporate a tuned acoustic core or a high-modulus structural core, which places it in the general-purpose PVB interlayer segment for architectural and automotive laminated glass.
The glass transition temperature of plasticised PVB typically lies below 0°C, producing rubbery behavior at room temperature. The low glass transition is set by plasticiser loading and distinguishes BH-S from stiff PVB structural grades that have lower plasticiser content and higher modulus. The exact glass transition temperature for BH-S is grade-specific and should be obtained from the supplier dynamic mechanical analysis data.
Interlayer thickness influences finished laminate performance. Standard PVB lamination uses multiples of 0.38 mm; two plies produce 0.76 mm, four plies 1.52 mm. In overhead glazing, a minimum interlayer thickness of 0.76 mm is commonly specified, but building codes and impact classes may require thicker stacks. Thicker interlayers increase fragment retention after breakage and provide greater penetration resistance, but they also increase total film moisture capacity and require a longer autoclave soak at the glass centre. Roll gap and edge squeeze-out must be adjusted for the full stack thickness.
Acoustic PVB interlayers contain a viscoelastic multilayer construction that reduces coincidence-dip transmission loss in laminated glass. BH-S does not contain that intermediate damping layer. A building facade using BH-S is tested under ISO 10140-2:2021 and rated under ISO 717-1:2020, but no acoustic improvement factor is assigned at interlayer level. The sound insulation result is governed principally by glass mass, airspace depth, and frame sealing. If a project specification requires a defined weighted apparent sound reduction improvement from the interlayer, an acoustic-grade S-LEC product should be substituted.
Structural interlayers, including ionomer-based products and stiff PVB formulations, provide higher post-breakage flexural coupling and lower creep compliance than BH-S. The lower modulus of BH-S at room temperature and its temperature-dependent shear stiffness make it unsuitable as a stand-alone structural interlayer in point-supported glass fins, glass floors, or cantilevered balustrades where post-breakage load capacity is a design input. Design calculations based on an ionomer or structural PVB long-term shear modulus cannot be transferred directly to BH-S laminates. Published data for this specific configuration is limited, and grade-specific impact test reports should not be carried over from other interlayer types.
Compared with EVA-based interlayers, BH-S is processed on standard PVB lamination lines without peroxide curing and does not require a chemical crosslinking step. Compared with ionomer interlayers, BH-S has higher moisture uptake, which requires controlled storage and edge protection but provides established safety-glazing performance when processed within the supplier-defined window.
BH-S is hygroscopic. The film should be stored in a room conditioned to 18–21°C and 20–35% relative humidity, with the original roll packaging intact until layup. Moisture uptake occurs preferentially at exposed cut edges and can produce edge clouding or delamination in service. If storage relative humidity exceeds 60%, pre-conditioning may be required; the supplier’s roll-specific guidance should be applied before lamination.
The critical process step for BH-S lamination is deairing before the perimeter edge seal forms. In roller-press lines, published PVB processing guidance places roll press preheat surface temperatures near 60°C before the nip entry, with nip roll hardness in the 65–75 Shore A range. These starting values are equipment-dependent and are not product constants. If the film softens too early and seals the glass perimeter, trapped air channels are no longer accessible to vacuum extraction and the subsequent autoclave pressure cannot reabsorb them. The result is a bubble defect that is process-related, not an intrinsic film impurity.
Autoclave cycles for BH-S are commonly operated with glass temperature plateaus of 120–140°C and pressure plateaus of 1.0–1.3 MPa. Pressure should be ramped only after the glass reaches a uniform soak temperature. A centre-to-edge temperature lag greater than 15°C at the start of the pressure plateau is a known cause of incomplete perimeter bonding. Monolayer BH-S does not require the additional melt-compression step used for some acoustic trilayer films, but abrupt full-pressure application before uniform heat-up is not recommended. Controlled cooling under pressure is used to stabilise the laminate and reduce residual stress.
Asymmetric glass make-ups, such as thin glass laminated to thick glass, introduce uneven heat transfer and bending during cooling. The interlayer must accommodate differential expansion between plies. Production experience indicates that asymmetric laminates with a thickness ratio greater than 2:1 require additional attention to edge temperature at autoclave exit. Published data for this specific configuration is limited, and trial lamination is recommended.
Pummel adhesion is used to monitor the interlayer-to-glass bond. The test classifies adhesion on a 0 to 10 scale, with architectural laminated glass often targeting 3–7. Values below 3 may indicate insufficient glass retention after breakage, while values above 7 can reduce impact energy absorption by creating overly brittle adhesion. The BH-S target range is not universal; it changes with glass tin side, washing chemistry, and autoclave conditions.
Incoming film is checked for gauge, width, surface defects, and moisture. Tensile properties may be measured using ISO 527-3:2018 or JIS K 6772:2022, with specimens conditioned at 23°C and 50% relative humidity. Plasticised PVB typically exhibits tensile stress at break above 15 MPa and elongation at break above 200% at 23°C, but BH-S acceptance limits are taken from the supplier certificate of analysis because plasticiser content and film gauge influence the measured curve. The density of PVB interlayers is approximately 1.07 g/cm³, used for roll weight and yield calculations.
Optical haze is assessed in accordance with ISO 14782:2021. BH-S is supplied as a clear film intended for vision glazing, but point defects, bubble trains, and delamination are classified in the finished laminate under ISO 12543-6:2021. Inspection on production lines uses backlit viewing booths with illuminance specified by the customer; automated scanning systems detect inclusions, gel particles, and edge voids. BH-S rolls are edge-trimmed and can be slit to specified widths for automated layup cells.
Glass surface condition changes pummel adhesion. Float-glass tin side, detergent residues, rinse water conductivity, and final rinse temperature all shift the interlayer-to-glass bond. Production-scale lamination lines typically maintain final rinse water conductivity below 5 µS/cm and final rinse temperature between 40°C and 60°C. Changing glass suppliers, washing detergents, or low-emissivity coating suppliers requires pummel test recalibration because the glass surface chemistry is part of the adhesion system.
BH-S contains UV stabilisers to reduce discoloration from sunlight. Finished laminates are evaluated for radiation resistance under ISO 12543-4:2021, which includes exposure to high temperature, humidity, and simulated solar radiation. Edge discoloration can still occur if incompatible edge sealants or trapped volatiles create local chemical attack. Long-term colour stability in a specific facade should be verified by the glass fabricator’s qualification program.
Neutral-cure silicone sealants formulated for PVB contact are used for edge seal applications. BH-S should be isolated from amine-based or strongly alkaline sealants that can saponify the polymer or migrate into the interlayer. Solvent-based cleaners and aromatic hydrocarbons must be fully evaporated before glass layup because residual solvent can plasticise the film surface and create local optical distortion. Acetone and methyl ethyl ketone are used only on glass substrates before layup and are not applied directly to the interlayer.
Low-emissivity coated glass, ceramic frit, and decorative interlayers alter the lamination cycle. Low-emissivity coatings reduce heat transfer through the glass build and may require a longer autoclave soak to reach the target glass temperature. The coating edge deletion width must allow direct interlayer-to-glass bonding at the perimeter; insufficient edge deletion creates a weak edge seal and allows moisture ingress. Fritted surfaces change local surface energy and adhesion, so trial lamination is recommended before production batches. Published data for this specific configuration is limited.
The interlayer is not a finished glazing product. Compliance is demonstrated on the completed laminate. Table 1 outlines typical compliance pathways for laminated safety glass containing S-LEC BH-S.
| Standard designation | Scope | Application to S-LEC BH-S laminates |
|---|---|---|
| ISO 12543-2:2021 | Laminated safety glass | Impact and penetration performance of finished laminates |
| ISO 12543-4:2021 | Laminated glass durability | Heat, humidity, and radiation exposure of finished laminates |
| EN 14449:2005 | Glass in building — laminated glass and laminated safety glass | Evaluation of conformity and factory production control |
| ANSI Z97.1-2015 | Safety glazing materials used in buildings | Safety performance classification in the United States |
| JIS R 3205:2021 | Laminated glass | Japanese product requirements for laminated glass |
Temperature-dependent stiffness is a design boundary. PVB interlayers soften at elevated service temperatures, and laminates with large unsupported spans may deflect more than glass-alone calculations indicate. In structural silicone glazing systems, interlayer shear transfer is load-rate- and temperature-dependent. Creep under sustained wind or dead load should be modelled as a viscoelastic response rather than a fixed shear modulus. Published data for BH-S in this specific configuration is limited, and project-specific testing is required for critical structural applications.
Moisture and chemical exposure boundaries apply at the edge. BH-S is not a barrier layer for long-term water immersion, and glazing channels must drain standing water. In coastal or high-humidity environments, failed edge seals can raise edge moisture content and lead to delamination. The edge condition and drainage design are part of the system performance, not the interlayer alone. Direct chemical exposure to strong acids, strong bases, or prolonged immersion is not recommended.
For automotive laminated side lites and windscreens, BH-S may be used in laminated glass evaluated under ECE R43 or ANSI/SAE Z26.1. Automotive lamination lines often use higher line speeds and shorter autoclave dwells than architectural lines. The grade is not positioned as an acoustic windscreen interlayer unless combined with an acoustic-grade film in the layup. Edge retention is provided by encapsulation or the glass edge profile; the interlayer is not exposed to weather.
In production troubleshooting, the first inspection point for edge bubbles in BH-S laminates is the interlayer moisture log and glass washer rinse water quality. The second inspection point is the roll press exit temperature and nip pressure uniformity. The third is autoclave pressure ramp timing relative to glass temperature. These are process-related failure modes rather than intrinsic film defects. When the process envelope is controlled within the supplier-recommended window, BH-S laminates exhibit consistent clarity and adhesion in standard safety glazing.
