| HS Code | 999450 |
| Product Name | S-LEC BM-5 |
| Material | Polyvinyl butyral (PVB) |
| Product Form | Interlayer film for laminated glass |
| Thickness | 0.76 mm |
| Density | 1.08 g/cm³ |
| Refractive Index | 1.49 |
| Visible Light Transmittance | 89% |
| Haze | 0.5% |
| Tensile Strength | 22 MPa |
| Elongation At Break | 300% |
| Glass Transition Temperature | 25°C |
| Water Absorption | 4.5% |
As an accredited S-LEC BM-5 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | S-LEC BM-5 is supplied as a white powder in 20 kg polyethylene-lined paper bags, ensuring dry, safe storage. |
| Container Loading (20′ FCL) | 20′ FCL: S-LEC BM-5 resin loaded on palletized, sealed bags, securely stowed, fully containerized for safe transport. |
| Shipping | S-LEC BM-5 is a polyvinyl butyral (PVB) resin powder, shipped in sealed, moisture-proof packaging to prevent clumping. It is non-hazardous under standard transport regulations, but avoid dust generation. Keep dry, away from oxidizers, and store at moderate temperatures. Ensure proper labeling and clean, covered transport for safe delivery. |
| Storage | Store S-LEC BM-5 in its original sealed container in a cool, dry, well-ventilated area away from direct sunlight, heat sources, and ignition sources. Keep the container tightly closed to prevent moisture absorption and contamination. Maintain ambient room temperature; avoid high humidity and temperature extremes. Use within recommended shelf life to ensure consistent resin performance. |
| Shelf Life | S-LEC BM-5 has a shelf life of approximately two years when stored in a cool, dry place away from sunlight. |
S-LEC BM-5 is introduced as the primary polymeric binder in solvent-based tape casting slurries for alumina and glass-ceramic green sheets when roll-to-roll blanking requires a balance of cohesive strength and residual flexibility. The binder is first dissolved at 8–12 wt% in an ethanol/toluene blend at 70:30 w/w under slow agitation at 40–50°C for 120–180 min. The final slurry is compounded with 100 parts calcined alumina, 3.5–5.5 parts S-LEC BM-5, 1.5–2.5 parts butyl benzyl phthalate or dioctyl phthalate, and 0.5–1.0 part phosphate ester dispersant. Mixing is completed in a planetary centrifugal mixer or high-shear disperser for 20–40 min while temperature is kept below 30°C. Slurry viscosity is adjusted to 1,500–4,000 mPa·s at 10 s⁻¹ using a Brookfield RVDT-II+ with SC4-27 spindle. Tape is cast through a doctor blade gap of 150–350 µm at line speeds from 0.5 m/min to 2.5 m/min. Drying is staged through three zones at 60°C, 75°C and 90°C, with residual solvent reduced below 1.0 wt% before rewinding. Retained toluene above 1.5 wt% causes blocking and dimensional distortion during storage. Green tensile strength is measured with a universal testing machine according to ASTM D882-18 using a 25 mm gauge width and 50 mm/min crosshead speed. Binder burnout is programmed in air at 1–3°C/min from 200°C to 600°C; heating rates above 5°C/min produce delamination in tapes thicker than 200 µm. Published lot-specific data for S-LEC BM-5 in this exact slurry configuration is limited, and the ranges above are used industrially as an operating envelope for medium-viscosity PVB grades rather than as fixed batch targets.
Pot life is governed by acid esterification of the PVB hydroxyl sites rather than by solvent evaporation inside a closed pressure pot. The base component is prepared by dissolving S-LEC BM-5 at 7.0–10.0 wt% in a solvent blend of methyl ethyl ketone, ethanol and isopropanol at 40:30:30 w/w. The binder concentration in the wet primer is maintained near 10–12% to deposit a dry film thickness of 5–10 µm from a single gravity-feed spray pass. The activator contains orthophosphoric acid at 10–12 wt% in butanol, and the base-to-activator volume ratio is set at 4:1. Mixed viscosity measured with a DIN 53211 4 mm cup is 18–24 s at 25°C. After 30–40 min, acid consumption and viscosity rise above 30 s degrade atomization and reduce wetting on zinc-phosphate-treated steel. The applied primer should be overcoated within 24 h; longer outdoor exposure leads to chalking and loss of intercoat adhesion. Salt spray exposure according to ASTM B117-19 with scribe creep rated under ASTM D1654-08 is used for production qualification. Prepared surfaces follow ISO 8501-1 Sa 2½ for steel and SSPC-SP 1 solvent cleaning for aluminium. Chromate-free formulations replace zinc tetroxychromate with zinc phosphate or calcium strontium zinc phosphosilicate at 8–12 wt% on total solids. Dry-film primer overcoated with an epoxy or polyurethane topcoat within 48 h provides the main corrosion barrier; the thin PVB wash coat alone is not designed to withstand outdoor exposure without a topcoat.
In solvent-based flexographic surface printing, S-LEC BM-5 is used as a hard resin binder in combination with nitrocellulose and a polyurethane co-binder. A starting ink formula contains BM-5 at 6–9 wt%, nitrocellulose at 5–7 wt%, polyurethane resin at 2–4 wt%, and organic pigment at 12–18 wt%, with a solvent blend of ethyl acetate, n-propanol and propylene glycol monomethyl ether acetate at 50:35:15 w/w. Ink viscosity at press is normally held at 25–35 s with a Zahn #2 cup at 25°C; dilution is performed with an 80:20 ethyl acetate/n-propanol blend. An anilox roll of 360–500 lines/cm and cell volume 4.0–6.0 cm³/m² transfers the ink to a plate with a Shore A hardness of 65–75. Corona discharge on BOPP must maintain surface energy above 38 dyn/cm measured according to ISO 8296:2003. Insufficient treatment produces pinholes and adhesion failure after extrusion lamination. Bond strength after laminating with LDPE is evaluated per ASTM F88/F88M-21 at 150 mm/min jaw separation. Food-contact status for the printed side is not inherent to the ink and requires a functional barrier, overprint varnish, or formulation clearance under 21 CFR 175.300 or equivalent national food-contact legislation. The resin also increases ink resolubility on press if solvent balance shifts toward ethanol-rich late additions, which must be controlled to avoid plate swelling during extended stops.
Heat-seal lacquers on aluminium blister foil require a resin that flows quickly under short dwell pressure but does not block on the coater. S-LEC BM-5 is dissolved at 12–16 wt% in a solvent blend of ethanol and methyl ethyl ketone at 80:20 w/w, with rosin ester at 5–8 wt% on total solids and silica matting agent at 0.5–1.5 wt% to prevent roll blocking. The lacquer is applied by gravure cylinder at a dry coat weight of 2.0–4.0 g/m² on soft-tempered aluminium foil of 20–25 µm. Drying is performed in a floating oven with maximum web temperature 80–90°C, because residual methyl ethyl ketone above 1.0 wt% causes organoleptic defects in pharmaceutical packaging. Heat-seal activation is performed at 150–180°C, 1.0–2.0 s dwell and 2–4 bar jaw pressure. Seal strength on PVC-laminated aluminium foil is measured per ASTM F88/F88M-21 at 100 mm/min; production-grade lacquers generally require 4–8 N/15 mm depending on foil temper and lidding film type. Regulatory compliance for pharmaceutical packaging invokes EU Regulation (EC) No 1935/2004 and, for the United States, 21 CFR 175.105 as a general adhesive-component framework. Published data for S-LEC BM-5 on high-amylose starch-filled biodegradable film is limited; production trials are required because seal initiation and hot tack may deviate from PVC-PVDC lidding stock.
| Application | Standard reference | Core test condition | Operational boundary |
|---|---|---|---|
| Ceramic tape casting | ASTM D882-18 | Green sheet tensile, 25 mm wide strip, 50 mm/min | Residual solvent below 1.0 wt% before rewinding |
| Wash primer | ASTM B117-19 / ASTM D1654-08 | Scribe creep after salt spray exposure | Overcoat within 24–48 h after primer application |
| Flexographic ink | ISO 8296:2003 | Surface tension of corona-treated BOPP | Minimum 38 dyn/cm before printing |
| Heat-seal lacquer | ASTM F88/F88M-21 | Seal peel at 100 mm/min | Sealing jaw at 150–180°C, 1–2 s |
In solvent-processed flexographic printing plates, S-LEC BM-5 functions as a non-crosslinked binder in the photopolymer layer. The plate formulation contains BM-5 at 15–25 wt% together with an aliphatic urethane acrylate oligomer, a monofunctional acrylate monomer, a benzil dimethyl ketal photoinitiator and a polymerization inhibitor. After UV exposure through a negative film at 365 nm with a dose of 8–15 J/cm², the image areas are crosslinked while the unexposed binder remains soluble in a developer system based on perchloroethylene or a 50:50 blend of butanol and water. Relief depth in thin plate applications is typically 0.5–1.0 mm. Developer residence time is adjusted to remove uncured resin without swelling the crosslinked network beyond 10% linear swell. Excessive developer residence produces shoulder rounding and dot gain above 15% at 150–175 lpi. Brush agitation in common plate processors is maintained at 40–80 rpm. The non-crosslinked PVB phase contributes to solvent accessibility but raises developer loading over production campaigns. Published performance data specific to S-LEC BM-5 in photopolymer plates is limited; the above processing envelope is derived from PVB binders of comparable hydroxyl number and requires plate-line confirmation for each developer chemistry.
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Poly(vinyl butyral) grade S-LEC BM-5 is a white, free-flowing powder supplied by Sekisui Chemical Co., Ltd. under the S-LEC B series. It is a raw resin intended for dissolution in organic solvent systems, not a pre-compounded film or coating. The polymer is produced by the acid-catalyzed acetalization of poly(vinyl alcohol) with n-butyraldehyde; the resulting terpolymer retains vinyl butyral, vinyl alcohol, and residual vinyl acetate repeat units. The residual hydroxyl concentration is typically reported in the 22–24 mol% range and the acetate concentration at ≤3 mol% when tested by ASTM D1396-14; the balance is predominantly vinyl butyral. This composition places BM-5 in the medium-high molecular weight segment of Sekisui’s S-LEC B series. The grade is specified for ceramic green sheet casting, solvent-based printing inks, temporary peelable coatings, and non-ionic binder applications in which clean thermal decomposition is required. The principal differentiator from S-LEC BM-1 and BM-2 is the higher solution viscosity at equivalent solids in a standard solvent blend.
Solution preparation for S-LEC BM-5 requires a binary solvent system rather than a single nonpolar solvent because the residual hydroxyl groups form hydrogen bonds with polar solvents. A frequently used reference solvent is ethanol:toluene at a 1:1 w/w ratio; methyl ethyl ketone, ethyl acetate, propylene glycol monomethyl ether acetate, and diacetone alcohol are also employed when coating thickness or drying rate must be adjusted. Brookfield viscosity is determined according to ISO 2555 using a 5 wt% solution at 20 °C; because PVB solutions are mildly pseudoplastic, spindle geometry, speed, and container diameter must be reported with any viscosity value. Rheological characterization under controlled shear rate should follow ISO 3219 when shear-rate dependence is required. Moisture in the powder resulting from storage above 60% RH can shift measured solution viscosity by more than 10% relative to dry resin. Drying at 60–70 °C for 2–4 h in a forced-air oven is therefore recommended before final dissolution and viscosity measurement.
The hydroxyl groups in BM-5 are the principal hydrogen-bond donor sites. They allow adhesion to silanol-terminated glass, alumina, barium titanate, nickel, and metal oxide surfaces. The same hydroxyl groups restrict solubility in low-polarity hydrocarbons. With the hydroxyl content in the 22–24 mol% range, BM-5 remains fully soluble in alcohol/ketone and alcohol/ester blends but may show haze or graininess in toluene without ethanol. Practical adhesion to glass can be quantified by pull-off testing according to ISO 4624 using a prescribed dolly. The butyral rings contribute bulky nonpolar character, lowering the glass transition below that of the parent poly(vinyl alcohol) and permitting compatibility with conventional PVB plasticizers such as dibutyl phthalate and triethylene glycol bis(2-ethylhexanoate) within ranges determined by compatibility testing. Glass transition of the dry resin measured by ISO 11357-2 at 10 K/min heating rate is typically reported between 60 °C and 70 °C for S-LEC B grades in this hydroxyl range; plasticizer addition depresses this value. Because BM-5 has a higher molecular weight than BM-1 or BM-2, the same hydroxyl content produces a larger solution viscosity and a higher cohesive strength of the dried binder phase. This is why BM-5 is selected when green tape strength is insufficient but BH-3 would raise slurry viscosity beyond a processable range in a tape-casting die.
In multilayer ceramic capacitor tape casting, the binder must maintain a stable slurry under low shear, allow bubble release after casting, and deliver green tape tensile strength sufficient for handling, cutting, and stacking. S-LEC BM-5 is introduced at binder additions typically between 5 and 12 wt% of the inorganic powder when the slurry is formulated at 55–70 vol% solids in a mixed ketone/alcohol vehicle. The higher viscosity contribution of BM-5 compared with BM-2 requires either a lower solids loading or a small increase in solvent volume to hold the same blade gap. On a production tape-casting line, this is normally managed by adjusting the doctor blade gap, slot-die feed rate, and zoned air temperature in the drying tunnel. The relative viscosity of a BM-5-based slurry is higher than that of BM-2 by an amount controlled by solids volume fraction and dispersant type; a controlled-stress rheometer operated according to ISO 3219 should be used to compare the two grades. Published numerical data for BM-5 slurry viscosity in a defined barium titanate formulation are limited because dispersant-binder interactions dominate. The general relationship is that increasing binder molecular weight from BM-2 to BM-5 increases green strength while reducing slurry flow. The trade-off is resolved by adjusting casting speed, blade gap, and downstream drying air temperature.
Binder removal is the limiting thermal step. Polyvinyl butyral decomposes in air beginning near 250 °C, with the major mass loss occurring between 300 °C and 450 °C. In multilayer capacitor production with nickel internal electrodes, burnout is conducted in a reducing or inert atmosphere; residual carbon from incomplete decomposition can degrade electrode continuity. The ash content of S-LEC BM-5, when confirmed by ISO 3451-1 or equivalent, is relevant because inorganic residue remains in the ceramic after burnout and may affect dielectric properties. In a forced-air thermogravimetric run at 10 °C/min to 600 °C, a well-oxidized PVB grade should leave less than 0.2 wt% residue; the exact lot value should be verified against the certificate of analysis. Production ramp rates often must be slowed near 200–250 °C to avoid bubble formation from plasticizer volatilization, although the raw resin TG curve does not capture this effect. A burnout profile therefore must be validated with the full green tape, including dispersant, plasticizer, and ceramic powder.
| Test method | Parameter | Relevance to S-LEC BM-5 |
|---|---|---|
| ASTM D1396-14 | Vinyl butyral, vinyl alcohol, and vinyl acetate content | Confirms the 22–24 mol% hydroxyl and ≤3 mol% acetate acceptance window |
| ISO 2555 | Brookfield viscosity of 5 wt% solution | Sets dissolution and coatability limits |
| ISO 11357-2 | Glass transition temperature | Indicates film hardness, blocking resistance, and plasticizer efficiency |
| ISO 3451-1 | Ash content | Predicts inorganic residue after binder burnout |
| ISO 15512 | Water content | Controls viscosity drift and solvent compatibility |
S-LEC BM-1, BM-2, BM-5, and BH-3 share approximately the same butyral and hydroxyl content but differ in degree of polymerization. BM-5 occupies the boundary at which the resin still dissolves rapidly at 20 °C in ethanol:toluene but already provides enough chain entanglement to raise green tape strength. A displacement study comparing BM-5 with BM-2 in a solvent-based nickel paste would be expected to show higher vane torque at equal solids loading; the magnitude must be measured with an ISO 3219 rheometer because it depends on shear rate. In contrast, replacing BM-5 with BH-3 may cause cracks in dried green tape due to increased drying stresses, although published data in a defined ceramic composition are limited. The lower-viscosity BM-1 grade is generally reserved for high-solids, low-viscosity coatings in which binder strength is secondary.
This substitution requires a rebalancing of solvent and solids loading rather than a direct drop-in. At a constant binder mass fraction of 8 wt% based on inorganic solids in a 65 vol% barium titanate slurry, the apparent viscosity at 10 s−1 is expected to be higher for BM-5 than for BM-2 by a factor that depends on dispersant chemistry; manufacturers often increase solvent content by 5–15 wt% or reduce casting speed to maintain a defect-free tape. Green tensile strength measured on dry tapes typically improves with the higher-molecular-weight BM-5 grade because longer chains bridge more ceramic particles; exact tensile data must be generated according to an internal method because no ASTM standard exists for green ceramic tapes. Lamination temperature and pressure may also require adjustment because the glass transition of the resin is similar, but the cohesive strength of the BM-5 adhesive phase is higher. Operators should monitor dryer fouling and blade edge build-up; higher-molecular-weight PVB can form gel-like residues under high shear and localized solvent evaporation.
S-LEC BM-5 also functions as a film-forming resin for ceramic decal inks, glass-edge coatings, and temporary protective masks. The dissolved resin can be applied by screen printing, slot-die coating, or gravure; solvent selection determines drying rate and final film thickness. Optical clarity of cast films can be quantified with a haze meter according to ISO 14782. In peelable temporary coatings, BM-5 is formulated with plasticizer to reduce brittleness and allow mechanical removal without tearing. Plasticizer compatibility is confirmed by glass transition measurement with ISO 11357-2 to detect phase separation. Film tensile properties can be measured according to ISO 527-3 when a freestanding film is cast. The resin is not intended as a moisture barrier in humidity-critical environments because PVB is inherently hygroscopic; if moisture exclusion is required, water vapour transmission rate must be measured according to ISO 15106-1.
Industrial hygiene and regulatory screening should be completed before scale-up. The powder is combustible as an organic dust; handling equipment should be grounded to prevent static discharge. Compliance with the Japan Chemical Substances Control Law and EU REACH (EC) No 1907/2006 must be confirmed by the importer or formulator for the specific use. Food-contact applications require independent confirmation against the applicable positive list because S-LEC BM-5 is not a universal food-contact grade. These procedural constraints do not replace the manufacturer’s safety data sheet.
Powder hygroscopicity is the main storage concern. At 23 °C and 50% RH, PVB resins typically absorb water in the range of 1–3 wt%; at 80% RH the equilibrium moisture content is markedly higher. Water in the powder reduces dissolution efficiency in low-polarity solvent blends, may cause haze, and can shift solution viscosity. Drying at 60–70 °C in a forced-air oven for 2–4 h before use is recommended when storage relative humidity exceeds 60%. The powder should be stored in closed containers away from direct sunlight; prolonged exposure to strongly acidic or alkaline aqueous media can hydrolyze the acetal rings. In solvent-based paste compounding, avoid adding strong amine or alkali additives without compatibility testing because such materials may accelerate acetal hydrolysis or produce discoloration at elevated processing temperatures. The operational boundary for clean decomposition of S-LEC BM-5 in air is generally below 450 °C; formulations requiring higher thermal stability should be evaluated with thermogravimetric analysis according to ISO 11358-1.
