| HS Code | 538921 |
| Thickness | 0.76 mm |
| Standard Width | 2,000 mm |
| Standard Length | 300 m |
| Density | 1.07 g/cm³ |
| Tensile Strength | 18 MPa |
| Elongation At Break | 220% |
| Tear Strength | 50 kN/m |
| Light Transmittance | 90% |
| Haze | 0.5% |
| Refractive Index | 1.48 |
| Uv Cutoff | 380 nm |
| Glass Transition Temperature | 20 °C |
As an accredited S-LEC BL-5 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | S-LEC BL-5 is supplied as a powder in sealed multi-layer paper bags, with a net quantity of 20 kg per bag. |
| Container Loading (20′ FCL) | S-LEC BL-5 is loaded into a 20′ FCL as palletized, secured bags, ensuring safe, stable transport without damage. |
| Shipping | S-LEC BL-5 (polyvinyl butyral resin) is shipped as dry, free-flowing powder in sealed moisture-resistant bags or drums. Protect from humidity, rain, and heat during transit. Not classified as dangerous goods, but keep packaging intact and store in a cool, dry, ventilated area. |
| Storage | Store S-LEC BL-5 in a cool, dry, well-ventilated area away from direct sunlight, heat sources, and moisture. Keep containers tightly sealed when not in use to prevent contamination and humidity absorption. Avoid stacking heavy loads on packaging. Use within recommended shelf life and follow material handling guidelines. |
| Shelf Life | S-LEC BL-5 has a shelf life of two years when stored in a cool, dry place, away from moisture and direct sunlight. |
In barium titanate-based multilayer ceramic capacitor dielectric tape casting, S-LEC BL-5 is introduced as the primary green-sheet binder phase at 6–12 wt% of inorganic dry weight. The resin is first dissolved in a 60:30:10 by weight toluene–ethanol–n-butyl acetate carrier to 15–20 wt% solids, then blended with BaTiO3 powder, dispersant, and a phthalate-free plasticizer such as dioctyl sebacate at 5–10 phr. The slip is passed through a three-roll mill with zirconia rolls until a Hegman fineness below 5 μm is recorded and viscosity is adjusted to 8,000–25,000 mPa·s at 25 °C. Tape casting onto silicone-coated PET release liner uses a doctor blade gap of 25–40 μm at 0.5–1.5 m/min; drying in a two-zone oven at 60 °C and 80 °C reduces retained solvent to 0.3–0.8 wt%. Green sheets are laminated at 75 °C and 50 MPa. The burnout profile is critical: heating at 0.5 °C/min to 300 °C with a 2 h hold, then 1.0 °C/min to 600 °C with a 1 h hold, limits carbon residue to <0.05 wt% before sintering at 1,100–1,300 °C. Finished MLCCs are qualified under IEC 60384-1 and, for automotive, AEC-Q200. Compliance is maintained to RoHS Directive 2011/65/EU Annex II. If ambient relative humidity exceeds 60%, the resin should be pre-dried at 40 °C for 4 h; nitric acid additions are incompatible because nitration of hydroxyl sites can produce a sudden viscosity climb and gel formation.
High-speed central-impression flexographic and gravure printing lines running at 200–400 m/min require a binder that retains pigment dispersion under high shear while maintaining lamination bond strength. BL-5 is introduced at 8–15 wt% of the liquid ink. A standard letdown vehicle is ethyl acetate–ethanol–n-propyl acetate at 40:40:20 by weight, adjusted with n-propyl acetate until the ink measures 18–22 s on a Zahn #2 cup at 25 °C. Plasticizer addition is dibutyl sebacate at 5–10 phr of resin, and a polyethyleneimine adhesion promoter is used at 0.5–1.0 wt% total formula on primed polyester and polyamide substrates. After printing and adhesive lamination, bond strength is determined under ASTM F904-16; values on coextruded polypropylene typically fall in 3.5–6.0 N/15 mm after 48 h ageing. Solvent resistance is checked by methyl ethyl ketone double rubs per ASTM D5402-19, and coefficient of friction is measured under ISO 8295:1995. For food-contact packaging, the formulated ink must comply with FDA 21 CFR 175.300, EU Regulation 1935/2004, and Swiss Ordinance 817.023.21. The operational boundary is that BL-5 is not suitable for high-boiling ketone wash-up systems above 35 vol% cyclohexanone because prolonged exposure can redissolve the binder and degrade rub resistance; high-acid nitrocellulose co-resins should also be avoided because free acidity accelerates acetal hydrolysis.
On alkaline-cleaned cold-rolled steel and aluminium coil entering a coating line, S-LEC BL-5 forms the film-forming fraction of a solvent-borne etch primer at 10–15 wt% resin solids. Part A is a 50:30:20 methyl ethyl ketone–xylene–n-butanol solution of BL-5 at 20–25% non-volatile; Part B is 85% phosphoric acid added at 4–6% of total formula, with zinc phosphate pigment at 5–8 wt%. The mixed primer is applied by reverse roll coater to a dry film thickness of 5–10 μm, followed by flash-off at 25–35 °C and curing at 80–120 °C for 30–60 s. Cross-hatch adhesion after 24 h is class 5B under ASTM D3359-17, and reverse impact resistance is evaluated at 80 in·lb per ASTM D2794-93. Neutral salt spray resistance of the primed panel before topcoating reaches 500 h with less than 1 mm scribe creep under ISO 9227/ASTM B117-19. The coated coil then receives a polyester–melamine topcoat. Under REACH Annex XVII, hexavalent chromium inhibitive pigments are not used; zinc phosphate is the compliant alternative. Pot life is the main process limitation: with the acid catalyst present, viscosity doubles within 8–12 h at 25 °C, so line-side mixing is mandatory.
Glass-to-aluminium and glass-to-stainless-steel assembly lines use BL-5-based heat-seal coatings where nitrocellulose formulations fail due to exudation or insufficient cohesive strength after thermal cycling. The coating is prepared at 25% solids in 80:20 2-butanone–cyclohexanone, plasticized with dibutyl sebacate at 20–30 phr of resin, and crosslinked with a blocked isocyanate at 1.0–2.0 wt% of total solids. Coating application is by gravure or slot die at 15–25 μm dry film on the metal component. Heat sealing is performed at 150–170 °C under 0.5–1.0 MPa for 3–5 min. Lap-shear strength on glass-to-stainless-steel test pieces is measured under ISO 4587:2003; published values for plasticized PVB–metal systems commonly fall between 5 MPa and 10 MPa, with cohesive failure inside the PVB layer rather than adhesive failure at the glass interface. Thermal shock resistance is cycled from −40 °C to 85 °C per IEC 60068-2-14, test Na, for 500 cycles without delamination when the coating thickness is kept below 25 μm. The main incompatibility is free amine-containing silane promoters; when added above 1.0 wt%, they accelerate isocyanate consumption and shorten pot life to <2 h at 30 °C.
Interlayer film producers dry-blend BL-5 with triethylene glycol di-(2-ethylhexanoate) at 20–35 phr and extrude the compound on a co-rotating twin-screw extruder with an L/D 40:1 configuration. Temperature zones are set from 120 °C near the feed throat to 180 °C at the die, with melt pump pressure 8–12 MPa and barrel vacuum below −0.09 MPa to strip water and acetaldehyde. Extruded film is calendered to 0.76 mm or 1.52 mm and wound at 20–30 m/min. Before extrusion, moisture must be below 0.2 wt%; otherwise bubble defects appear in the film and adhesion to glass becomes inconsistent. Lamination to glass uses a pre-press at 80–100 °C and autoclave at 140 °C and 1.2 MPa for 60–90 min. Optical quality is inspected under ISO 12543-2, with transmittance above 85% and haze below 2%. Aged interlayer performance is evaluated by ISO 4892-2 Xenon-arc exposure and ISO 12543-3 for impact resistance. Edge stability is the dominant storage concern: plasticizer migration causes visible edge whitening when film is stored above 35 °C or above 70% RH for more than 4 weeks, so slit rolls must be kept in sealed polyethylene with desiccant.
For polyester-based thermal transfer ribbon coatings, BL-5 is compounded at 3–6 wt% of the transfer layer to balance release and adhesion; blocking is assessed after 24 h at 50 °C under 0.1 MPa load following ASTM D3354-15.
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S-LEC BL-5 is a polyvinyl butyral (PVB) resin manufactured by Sekisui Chemical as a white free-flowing powder with CAS registry number 63148-65-2. It occupies the medium-viscosity segment of the S-LEC B series and is specified as a binder in solvent-borne flexographic and gravure inks, washcoat primers, heat-sealable adhesives, and film-to-foil laminating adhesives. Published technical data list a butyral content of 74.0–78.0 wt%, a hydroxyl content of 20.0–24.0 wt%, and a solution viscosity of 5.0–7.0 mPa·s measured at 10 wt% solids in 1:1 ethanol/toluene at 20 °C under JIS K6728. The glass transition temperature is typically reported at 70–72 °C, with ash content ≤ 0.05 wt% and moisture content ≤ 0.5 wt%. These specifications distinguish S-LEC BL-5 from lower-viscosity grades used in low-solids size-coat and primer applications, and from higher-viscosity S-LEC B-series grades that require stronger solvent blends for equivalent application solids.
The hydroxyl groups in PVB are the primary determinants of solubility in polar solvents, compatibility with polar co-resins, and adhesion to glass, metal oxides, and corona-treated films. S-LEC BL-5, with a hydroxyl content of 20.0–24.0 wt%, dissolves readily in ethanol/toluene, methanol/ethyl acetate, diacetone alcohol/ethyl acetate, and glycol ether/ester blends used in flexographic press-side dilution. The same hydroxyl functionality raises the resin’s affinity for moisture and increases the viscosity of high-solids ethanol solutions compared with lower-hydroxyl PVB grades. In gravure ink formulations, press-side flow time is maintained at 18–28 s on a Zahn #3 cup at 25 °C for engravings of 200–300 lines/cm. When the ink film is applied to corona-treated polypropylene or aluminum foil, the hydroxyl groups orient toward the substrate and contribute to bond formation through polar and hydrogen-bonding interactions; adhesion is therefore higher than that obtained with low-hydroxyl PVB but can decline after prolonged water immersion if substrate treatment is inadequate. The hydroxyl content also determines reactivity toward isocyanate crosslinkers; formulations designed for stoving at temperatures above 140 °C may incorporate blocked isocyanates to react with the resin, while ambient-drying systems generally use S-LEC BL-5 as a non-reactive physical binder.
The solution viscosity range of 5.0–7.0 mPa·s corresponds to a medium molecular weight distribution that balances film toughness and coatability. In comparison with lower-viscosity PVB grades, S-LEC BL-5 produces films with greater cohesive strength and better resistance to flex cracking, but it requires more aggressive solvent blends at equal solids. In comparison with higher-viscosity PVB grades, the resin allows higher application solids at a given press viscosity and gives lower foaming tendency during high-speed mixing. The molecular weight distribution also influences shear stability: repeated passes through a gear pump at 35–40 °C do not significantly reduce viscosity when dissolved in ethanol/ethyl acetate, whereas nitrocellulose-based binders may shear-degrade under similar conditions.
In high-speed rotogravure and flexographic printing, the medium chain length of S-LEC BL-5 allows higher application solids than ketone or aldehyde resins while maintaining cylinder-wipe viscosity. At 30 wt% solids in 2:1 ethyl acetate/ethanol, solution viscosity is typically below 150 mPa·s at 25 °C; closed-lid viscosity drift after 48 h at 20 °C is normally less than ±5 % when the solvent blend contains ≥ 10 wt% ethanol. Solvent release is governed by the difference between solvent evaporation rate and the resin’s polar retention. Residual solvent levels of 2–4 wt% may remain after forced-air drying at 60 °C, particularly with slow ester solvents. Drying tunnels on gravure coating lines should therefore be operated with a final zone temperature of 70–80 °C and air impingement velocity of 15–25 m/s to reduce blocking in rewind stacks. The resin is insoluble in neutral water and is not recommended for direct waterborne ink conversion without a suitable co-solvent or neutralization mechanism.
Powder handling on compounding floors requires humidity control. S-LEC BL-5 absorbs atmospheric moisture above 60 % RH; when moisture content before dissolution exceeds 0.5 wt%, solution clarity in ketone/ester blends can decrease and viscosity can increase by hydrogen bonding between water and the resin’s hydroxyl groups. Opened bags should be pre-dried at 50–60 °C for 2–4 h in a desiccant dryer with a dew point below -40 °C before charging to a high-shear dissolver. Powder addition should be carried out at impeller tip speeds below 3 m/s to control dust. Filtering the final solution through 10–25 µm bag filters is recommended before ink or adhesive transfer to application equipment. Strong mineral acids and oxidizing agents should be avoided because cleavage of the acetal linkages can reduce molecular weight and lower solution viscosity over 24–72 h.
Replacement of nitrocellulose by S-LEC BL-5 in flexographic lamination inks changes thermal stability, photostability, and adhesion balance. Nitrocellulose provides rapid solvent release and high film hardness, but nitrate ester groups are thermally labile and can yellow under UV exposure. PVB resin offers better long-term non-yellowing and adhesion to aluminum foil and polyester, but at equal solids the ink may exhibit higher viscosity and different re-solubility on the plate. Reformulation typically involves reducing pigment loading by 2–5 wt% and substituting ethyl acetate with ethanol/ethyl acetate blends at 1:1 to 2:1 to maintain press-side viscosity. Compared with polyamide binders, S-LEC BL-5 is less sensitive to viscosity drop in alcohol-rich diluents and does not require high-amine solubility; however, adhesion to untreated or low-treatment polyethylene may be lower unless an organosilane adhesion promoter is added at 0.5–1.0 wt% of total solids. In laminate structures, PVB-containing inks often show higher room-temperature T-peel strength on aluminum foil than polyamide-based inks when tested according to ASTM D1876, although published data for this specific grade under production lamination speeds is limited.
The following properties are representative certificate-of-analysis values for S-LEC BL-5. They are suitable for incoming inspection and quality-control comparison rather than for direct formulation calculations.
| Property | Representative range | Test method |
|---|---|---|
| Butyral content | 74.0–78.0 wt% | JIS K6728 |
| Hydroxyl content | 20.0–24.0 wt% | JIS K6728 |
| Solution viscosity (10 wt%, 1:1 ethanol/toluene, 20 °C) | 5.0–7.0 mPa·s | JIS K6728 |
| Glass transition temperature | 70–72 °C | DSC |
| Moisture content | ≤ 0.5 wt% | JIS K6728 |
| Ash content | ≤ 0.05 wt% | JIS K6728 |
Regulatory status should be confirmed against the current supplier document. S-LEC BL-5 is subject to REACH Regulation (EC) 1907/2006; registration and pre-registration obligations apply to the legal entity importing or supplying the material in the European Economic Area. The polymer is not expected to contain cadmium, lead, mercury, hexavalent chromium, polybrominated biphenyls, or polybrominated diphenyl ethers above the threshold concentrations of RoHS Directive 2011/65/EU. For food-contact uses, the resin may be evaluated as a component of an adhesive under 21 CFR 175.105 or under the relevant national food-contact legislation, but the finished printed article must meet applicable migration limits. Halogen-free claims should not be inferred from the PVB backbone alone if chlorinated co-resins or additives are used.
Laminating adhesives formulated with S-LEC BL-5 are commonly prepared at 20–30 wt% solids in ethyl acetate/ethanol mixtures. Drying tunnel temperatures are typically set at 70–90 °C with web speeds of 100–200 m/min on solvent-based laminating machines. The dried adhesive film develops immediate green tack on corona-treated polyethylene and aluminum foil; T-peel strength after 24 h aging at 23 °C/50 % RH commonly falls in the 2–6 N/15 mm range when tested according to ASTM D1876, depending on coating weight and surface treatment. The resin functions as a tie layer and does not provide heat-seal performance without a heat-sealable polymer layer. If polyisocyanate crosslinkers are added to improve chemical resistance, pot life at 25 °C is determined by the reaction between isocyanate groups and the resin’s hydroxyl groups; viscosity should be monitored over 4–8 h to define the working window for the specific coating line. Storage of the mixed adhesive above 30 °C shortens pot life and can cause gelation in transfer lines.
The glass transition temperature of 70–72 °C places S-LEC BL-5 above room-temperature coating conditions; films are hard and non-blocking under normal storage but can be plasticized with dibutyl phthalate or acetyl tributyl citrate at 10–20 phr to reduce brittleness in cold-flex applications. Plasticizer compatibility is influenced by the hydroxyl content; higher-hydroxyl PVB grades may accept plasticizers less readily than lower-hydroxyl grades. In printed films, plasticizer addition reduces tensile modulus but also lowers heat resistance; formulators must verify that the selected plasticizer does not migrate to the ink surface under 50 °C aging.
For ink concentrates, S-LEC BL-5 is dispersed with high-toughness organic pigments in a bead mill charged with 0.6–1.0 mm zirconia media at mill-base solids of 35–45 wt%. The resin wets phthalocyanine blue and carbon black sufficiently for many formulations without high-acid-value dispersants; high-surface-area carbon black may still require a styrene acrylic dispersant at 5–10 wt% of pigment weight. Letdown solvent composition should keep aromatic hydrocarbon content below 30 wt% of the total solvent to avoid precipitation of PVB. Final printed film adhesion is assessed by cross-hatch tape adhesion after 24 h at 40 °C and 90 % RH, a condition that exposes moisture sensitivity more strongly than dry-room testing. S-LEC BL-5 is not recommended for continuous immersion in strong acidic or oxidizing media because acetal hydrolysis can reduce film integrity.
