| HS Code | 508125 |
| Product Name | S-LEC BM-1 |
| Manufacturer | Sekisui Chemical Co., Ltd. |
| Material | Polyvinyl butyral (PVB) |
| Category | Interlayer film for laminated glass |
| Color | Clear |
| Thickness | 0.38 mm |
| Density | 1.07 g/cm³ |
| Visible Light Transmittance | 90% |
| Haze | ≤ 1% |
| Tensile Strength | ≥ 20 MPa |
| Elongation At Break | ≥ 200% |
| Adhesion To Glass | 3–10 N/25 mm |
| Uv Transmittance | ≤ 0.1% at 365 nm |
| Refractive Index | 1.48 |
| Water Absorption | ≤ 0.5% |
As an accredited S-LEC BM-1 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | S-LEC BM-1 is supplied in sealed, moisture-protective 25 kg paper bags for safe handling and storage. |
| Container Loading (20′ FCL) | S-LEC BM-1 in 20′ FCL: drummed/palletized chemical secured, moisture-proof, evenly distributed, container dry and clean, safe transport. |
| Shipping | S-LEC BM-1 (PVB resin) ships as a solid granular material in sealed, moisture-proof multi-wall bags or drums. Protect from humidity, direct heat, and mechanical damage. No special dangerous-goods classification applies, but keep away from ignition sources and store in a cool, dry area during transport. |
| Storage | Store S-LEC BM-1 in its original, tightly sealed container in a cool, dry, well-ventilated area. Avoid exposure to direct sunlight, heat, humidity, and water. Keep away from ignition sources and incompatible materials. Follow recommended temperature ranges, and use within the stated shelf life to maintain resin quality and performance. |
| Shelf Life | Store S-LEC BM-1 in a cool, dry place, away from moisture and sunlight. Typical shelf life is 12 months. |
Electrolytic zinc-coated steel coil and 6082-T6 aluminium sections require a thin anchoring layer before epoxy or polyurethane topcoats, and S-LEC BM-1 polyvinyl butyral resin is dissolved into anhydrous ethanol/isopropanol 85/15 w/w at 8–10 wt% resin solids for the base component. The acid component, 75% orthophosphoric acid diluted to 6–10 wt% of the total mixed system, is added only after the resin has fully solvated at 20–25°C; acid addition during early solvation produces local PVB gellation and batch rejection in production-scale high-speed dispersers equipped with sawtooth discs running at 15–20 m/s tip speed. Compliance verification follows ISO 12944-2:2017 corrosion category C3 for urban/industrial exposure and ASTM B117-19 neutral salt spray for 168 h scribe creep measurement under ASTM D1654-08. After filtration through a 50 µm bag filter, the primer is applied with airless spray equipment using a 0.28–0.33 mm tip orifice to a dry film thickness of 5–8 µm on sweep-blasted steel prepared to Sa2½ under ISO 8501-1:2007; the tack-free interval is 15 min, and topcoating is completed within 8 h to avoid zinc phosphate interlayer failure. Amine neutralizing agents are excluded from the acid component, and relative humidity above 60% during application requires pre-drying of the alcohol solvent to prevent premature phosphate precipitation. Finished components include structural steelwork, railcar side panels, aluminium architectural extrusions, and aerospace cargo liners.
In reverse-printed biaxially oriented polypropylene laminates exposed to low-density polyethylene extrusion melt temperatures near 320°C, S-LEC BM-1 is employed as the primary film former at 8–14 wt% of total liquid ink. The resin is dissolved in ethyl acetate/n-propanol 80/20 w/w, and pigment is dispersed in a horizontal bead mill loaded with 1.2–1.6 mm zirconia media until grind gauge texture is below 5 µm measured by ISO 1524:2020. For indirect food contact laminates, material supplier declarations are screened against EU Regulation (EU) No 10/2011 and 21 CFR 175.105; printing press safety follows ISO 12643-2:2014. The letdown ink is adjusted to 25–35 s Zahn #2 at 23°C and printed on a laser-engraved gravure cylinder with 60–70 L/cm screen ruling and 28–35 µm cell depth; web tension for 18–20 µm corona-treated BOPP is held at 80–120 N/m to prevent tunnel defects during downstream PE extrusion. Production boundary: PVB solutions above 20 wt% solids exhibit shear-thinning fluidity that can destabilize gravure cell emptying, and added water above 5 wt% of the diluent causes resin precipitation. Terminal laminates include stand-up pouches, snack wrappers, cold-seal release laminates, and lidding film where the printed layer is sandwiched between the film and a 20–30 µm PE extrusion web.
Doctor-blade casting of submicron barium titanate dispersions for multilayer ceramic capacitors uses S-LEC BM-1 because the binder decomposes before 260°C and leaves an ash residue below 0.1 wt% when pyrolyzed under nitrogen/oxygen switchover according to ISO 11358-1:2022. Published data for S-LEC BM-1 in submicron BaTiO₃ dispersions is limited; the following ranges should be confirmed by differential torque rheometry on the mixing line. In a representative dielectric slip, BM-1 is predissolved at 10 wt% in toluene/ethanol 60/40 w/w and incorporated at 6–10 wt% based on dry barium titanate; a phthalate-free dibenzoate plasticizer is used at 30–50 wt% of binder solids to prevent green tape cracking. Slip production is a two-stage ball mill with 0.3–0.5 mm zirconia media, and viscosity is controlled at 3000–8000 mPa·s under ISO 3219:2021 before vacuum deaeration at 20–50 mbar. Casting proceeds through a 0.8–1.5 mm doctor blade gap onto silicon-coated polyester carrier film at 0.6–1.2 m/min; zone drying at 50°C/60°C/80°C reduces residual solvent to ≤0.2 wt%. Component qualification follows IEC 60384-1:2021 and AEC-Q200 Rev E stress test protocol. Green tape shelf life on the casting line is limited to 48 h, and moisture pickup above 0.3 wt% alters binder burnout exotherm. Finished components include 0201 and 0402 X5R/X7R multilayer ceramic capacitors, LTCC modules, and multilayer piezoelectric actuators.
Aluminium foil of 20–25 µm gauge is gravure-coated on the matte side with a PVB-containing lacquer at 1.5–3.0 g/m² dry coat weight; S-LEC BM-1 is compounded at 12–18 wt% of the wet lacquer to provide cohesion above the seal-initiation plateau. The lacquer system is screened under EU Regulation (EU) No 10/2011 for plastic materials in contact with pharmaceuticals and under USP chapter 661.1 for packaging components; seal strength is tested by ASTM F88/F88M-22 at 300 mm/min peel speed. Reverse gravure coating with a 70 L/cm cylinder runs at 100–150 m/min; solvent drying in a three-zone oven with 60°C/75°C/85°C air temperatures and 15–20 m/s air velocity ensures residual ethyl acetate below 0.05 wt%. Sealing to 250 µm PVC/PVDC film is executed at 160–180°C platen temperature, 0.3–0.6 s dwell, and 4–6 bar jaw pressure to obtain fiber-tearing seals without melting the lacquer interface. Operational boundary: re-dissolved solvent retained above 0.1 wt% in the lacquer shifts the seal-initiation temperature upward and produces leaker defects on high-speed blister lines. Finished articles are blister lidding for tablets and capsules, diagnostic test strip lids, and single-serve dairy lidding.
In automotive glass decoration, screen-printed enamel pastes incorporate S-LEC BM-1 as a screen-printing binder that is removed between 250°C and 350°C before the enamel frit sinters at 580–650°C. The paste formulation uses BM-1 at 6–12 wt% of paste solids; the solvent component is based on pine oil and butyl diglycol, and the enamel frit-to-pigment ratio is maintained at 4:1. Homogenization proceeds on a three-roll mill with a 0.2 mm nip gap until fineness of grind reaches 15–25 µm; the paste is screen-printed through 90–180 mesh polyester fabric onto curved glass, dried at 120°C for 5 min, and fired in a roller hearth furnace with 12–18 min total cycle. Finished glazing must satisfy ECE R43 safety glazing requirements and the mechanical test methods of ISO 3537:2015; heavy-metal release is controlled by the glass manufacturer’s type approval documentation. Operational boundary: exposing the wet paste to relative humidity above 55% causes surface skinning and mesh blocking, and amine-containing leveling agents should be excluded to avoid PVB gelation before firing. Finished products are automotive backlights, sunroof edges, and appliance control panel glass.
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S-LEC BM-1 is a polyvinyl butyral resin powder supplied by Sekisui Chemical Co., Ltd. for solvent-borne binder systems in ceramic green tape, thick-film paste, and specialty coating applications. The grade is characterized by a medium solution viscosity and a moderate hydroxyl content, which position it between the lower-viscosity BL series and the higher-viscosity BH series PVB grades. Typical certificate-of-analysis parameters include a 10 wt% solution viscosity of 10–20 mPa·s at 20 °C in 95:5 ethanol:toluene, butyral content of 78–82 mol%, hydroxyl content of 17–21 mol%, and acetyl content of 1–3 mol% when determined according to JIS K6728 or ASTM D1396. The glass transition temperature is reported near 65–70 °C by differential scanning calorimetry at 10 °C/min. The material is insoluble in water and aliphatic hydrocarbons; complete dissolution requires oxygenated solvents or alcohol-aromatic mixtures.
For incoming quality control, lot-to-lot variation in hydroxyl content and residual moisture should be checked against the manufacturer’s certificate of analysis rather than generic PVB datasets because both parameters influence solution viscosity and crosslinker demand. The powder is pre-dried at 40–50 °C for 2–4 h when storage relative humidity exceeds 60%. Residual moisture above 0.5 wt% can form micro-bubbles during doctor-blade casting and lower green density after solvent release. Bulk density is typically 0.3–0.5 g/cm³ but is not a specification; volumetric feeders should be calibrated against the supplied lot. ISO 1133-1:2022 melt flow rate is not a normally specified control because the resin degrades near processing temperatures; if measured, it should be performed on plasticized compound below 190 °C.
In multilayer ceramic capacitor and low-temperature co-fired ceramic tape production, S-LEC BM-1 functions as a fugitive binder that must leave minimal inorganic residue after oxidative burnout. Thermogravimetric analysis of PVB binders in air at 5 °C/min typically shows the onset of significant mass loss between 200 °C and 230 °C, with the main decomposition interval spanning 250–450 °C and near-complete mass loss by 500 °C. Published data for this specific configuration is limited; actual burnout completeness depends on oxygen partial pressure, green tape thickness, ceramic particle surface area, and heating ramp profile. Industrial pusher furnaces and forced-convection box furnaces are configured with a hold segment between 350 °C and 450 °C for 1–2 h to oxidize residual carbon derived from acetal backbone decomposition.
The ash retention limit is important because sodium, potassium, and transition-metal contamination degrade insulation resistance in high-frequency dielectric layers. Lot-to-lot ash content for S-LEC BM-1 is specified below 0.1 wt% on ignition at 800 °C. In reducing atmospheres, carbonaceous residue is not removed below 500 °C, and oxygen partial pressure should be verified when the furnace is used for base-metal electrode systems. For constrained sintering on rigid setters, burnout ramp rates above 2 °C/min can cause local delamination when the green tape contains high binder loadings above 15 phr.
Production-scale burnout furnaces use forced convection and separate exhaust zones because the exhaust gas from PVB decomposition contains butyraldehyde, carbon monoxide, and low-molecular-weight hydrocarbons. Thermal oxidizers are required above 750 °C to meet emission limits. Failure modes observed on manufacturing lines include residue rings in the cooler zone when the heating rate is too high or when the tape contains excessive plasticizer; ring formation is accompanied by local carbon retention and must be corrected by reducing ramp rate or adjusting binder-to-plasticizer ratio.
The dissolution of S-LEC BM-1 in multicomponent solvent systems follows polymer solution thermodynamics in which the hydroxyl hydrogen-bonding term must be balanced against the hydrophobic butyral segment. Ethanol-toluene blends in the range of 80:20 to 95:5 are common in tape-casting slurries because toluene reduces surface tension for wetting of release-coated polyester carriers while ethanol maintains hydroxyl solvation. In slot-die coating, viscosity drift during extended runs is minimized by using sealed solvent reservoirs and by adding 2–5 wt% of a high-boiling glycol ether such as butyl carbitol to suppress skin formation.
High-shear dispersion is not required for complete dissolution; however, a Cowles blade at tip speeds of 5–10 m/s reduces fisheye defects in concentrated masterbatches above 20 wt% solids. For gravure inks, the low-shear viscosity at 25 °C is typically adjusted to 300–800 mPa·s by controlling PVB concentration and solvent blend; the target depends on cylinder engraving depth and doctor blade pressure rather than on a single product specification. Viscosity measurements should use a Brookfield RV or equivalent rotational viscometer at 20 rpm after 24 h equilibration to avoid transient gel structures.
After casting, drying is typically carried out in a multi-zone tunnel oven with air temperatures from 50 °C to 120 °C. Rapid skin formation at high initial temperature traps solvent and produces blisters; a staged profile with lower first-zone air velocity is used. The residual solvent content in green tape is often controlled below 2 wt% before wind-up to prevent blocking and dimensional drift in roll storage.
The differentiation among PVB grades in gravure ink and ceramic slurry design is primarily viscometric and mechanical. Lower-viscosity grades with nominal solution viscosities of 5–10 mPa·s permit higher solids at a given press viscosity, but the dried film exhibits lower tensile strength and reduced adhesion to polar substrates because the molecular weight distribution shifts to shorter chain length. Higher-viscosity grades above 20 mPa·s increase green strength and ink film toughness, yet impose a solvent demand beyond practical coating viscosity and can produce ribbing defects on fast presses.
S-LEC BM-1 occupies the intermediate range of 10–20 mPa·s, allowing a formulator to reduce solvent content by approximately 10–20% compared with a high-viscosity PVB while retaining handleability of green tape at thicknesses down to 20–50 µm. Published data for this specific configuration is limited; the solvent reduction should be validated on the target printing line. In gravure printing, this viscosity window translates to more consistent cell emptying on 70–120 line/cm cylinders without the pinhole formation associated with low molecular weight grades.
The hydroxyl content distribution along the PVB backbone also affects hydrogen-bonded network density. S-LEC BM-1’s hydroxyl range of 17–21 mol% is lower than that of some high-adhesion PVB copolymers, which reduces moisture uptake but also lowers specific adhesion to hydrophilic ceramic surfaces. The trade-off becomes visible in tape-cast barium titanate where green tensile strength after drying is typically between 3–10 MPa depending on binder content and plasticizer; published data for this specific configuration is limited.
Ethylcellulose binders in thick-film conductor and resistor pastes provide excellent screen-printing rheology but leave greater carbonaceous residue and ash after firing if the furnace profile is inadequate. S-LEC BM-1 is evaluated as a lower-ash alternative where the paste vehicle must burn out below 500 °C before metal sintering begins. The PVB grade differs from ethylcellulose in two operational parameters. First, its hydroxyl groups contribute hydrogen-bonding with glass frit surfaces, which improves paste cohesion during screen printing but increases vehicle sensitivity to absorbed moisture; when relative humidity exceeds 60%, pre-drying of the powder at 40–50 °C is recommended.
Second, the burn-out profile of PVB is narrower than that of ethylcellulose and may require a controlled ramp segment between 250 °C and 400 °C to avoid blistering in pastes with silver-palladium conductors. Screen-printing vehicles formulated with S-LEC BM-1 and terpineol or butyl carbitol acetate show pseudoplastic flow; the apparent viscosity at 10 s⁻¹ and 25 °C is commonly adjusted to 20–80 Pa·s for stainless-steel mesh counts from 200 to 325. The ash contribution from the PVB binder is less than 0.1 wt% of the dry resin, but the final fired film purity also depends on the glass frit and metal powder lot.
Thick-film paste mixing on a three-roll mill is typically performed with cooling water at 0–10 °C to limit temperature rise below the boiling point of the solvent. A vehicle with S-LEC BM-1 at 15–25 wt% solids in terpineol can show near-Newtonian behavior at high shear; screen printing requires thixotropic recovery, so fumed silica or organic thixotropes are added. Batch-to-batch variance in PVB hydroxyl content can shift the thixotropic index; a quality check using a cone-and-plate rheometer at 25 °C and shear rates of 1 s⁻¹ and 100 s⁻¹ is recommended.
The plasticizer selection for S-LEC BM-1 in ceramic green tape is governed by solubility parameter compatibility and migration resistance. Phthalate plasticizers such as dibutyl phthalate and benzyl butyl phthalate are used at 10–30 phr to lower the glass transition temperature of the dried binder film to below room temperature, enabling cold punching and stacking of green sheets without cracking. Excessive plasticizer above 40 phr can cause binder exudation and blocking of stacked sheets during storage at 30–40 °C. The compatibility limit should be determined by differential scanning calorimetry; a single glass transition temperature and absence of a plasticizer melting endotherm indicate compatibility.
Plasticizer migration kinetics are influenced by the degree of hydrogen bonding between the plasticizer ester groups and the PVB hydroxyl sites. Under accelerated storage at 60 °C, phthalate loss from green tape can be monitored by ASTM D1203 using activated carbon; specimens with plasticizer loss above 1.5 wt% exhibit reduced lamination bond strength. During lamination, S-LEC BM-1-containing green tapes are typically pressed at 70–90 °C under 10–20 MPa for 5–10 min. The hydroxyl group content also promotes adhesion to carrier films and ceramic layers, but the same functionality can absorb moisture and shift the low-frequency dielectric loss of green tape if stored without desiccant.
PVB-based green tapes are sensitive to static charge accumulation when peeled from carrier film. In production, antistatic ionizers are installed at the stripping station, and line speed is limited by the green tape’s elongation at break. The elongation at break of plasticized PVB film can exceed 100%, but green tape containing ceramic filler is typically below 5%; this constraint governs radius of curvature in roll handling and prevents microcracking during automated stacking.
The hydroxyl groups of S-LEC BM-1 can react with isocyanate-functional crosslinkers, amino resins, and chelated titanates under forced drying. This reactivity is used to improve solvent resistance in specialty coatings but introduces a pot-life boundary. With aromatic polyisocyanates, formulations containing free hydroxyl concentrations in the dissolved PVB are stable for less than 4–8 h at 25 °C before a two-fold viscosity increase; storage at 35 °C shortens the pot life to below 2 h in some lot combinations. Amine-based catalysts should be avoided in solvent-borne PVB-isocyanate systems because they accelerate hydroxyl-isocyanate addition and can generate localized gel particles during spray application.
Amino resin crosslinking with melamine-formaldehyde requires acid catalysts and cure temperatures above 120 °C. Under these conditions, the butyral acetal linkage remains stable below 150 °C, but prolonged exposure to strongly acidic solutions causes hydrolytic degradation of the acetal group. Hydrolytic degradation is accompanied by an increase in free hydroxyl concentration, which raises solution viscosity and crosslinker demand. Fourier-transform infrared spectroscopy can monitor the hydroxyl peak near 3400 cm⁻¹; a shift in the hydroxyl-to-carbonyl ratio indicates storage degradation.
In solvent-borne films, yellowing may occur above 150 °C or under prolonged UV exposure. UV absorbers of the benzotriazole class can be added at 0.1–0.5 wt% but may interact with amino crosslinkers; compatibility should be checked by haze measurement after cure. For storage, S-LEC BM-1 should be kept in sealed containers below 30 °C and protected from moisture migration; opened containers exposed to relative humidity above 60% may require re-drying before use in moisture-sensitive ceramic tape formulations. When the resin is used in food-contact coating formulations, compliance requires verification under 21 CFR 177.1670 and the applicable end-use limitations. The resin contains no intentionally added heavy metals above the concentration limits in EU RoHS Directive 2011/65/EU, Annex II; however, final compliance is dependent on the assembled electrical and electronic equipment.
