| HS Code | 299504 |
| Product Name | S-LEC BHB |
| Manufacturer | Sekisui Chemical Co., Ltd. |
| Product Type | PVB interlayer film for laminated glass |
| Base Material | Polyvinyl butyral (PVB) |
| Primary Function | Heat shielding / solar control |
| Thickness | 0.38 mm and 0.76 mm |
| Glass Transition Temperature | Approx. 30°C |
| Visible Light Transmittance | Approx. 75% to 80% |
| Uv Cut Off | >99% absorption below 350 nm |
| Haze | Less than 1% |
| Tensile Strength | Approx. 20 MPa |
| Elongation At Break | More than 200% |
| Adhesion To Glass | Excellent |
| Moisture Absorption | Low |
As an accredited S-LEC BHB factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | S-LEC BHB is supplied as a resin in 25 kg sealed multi-wall paper bags with an inner polyethylene liner. |
| Container Loading (20′ FCL) | 20′ FCL container loading of S-LEC BHB: secure palletized drums, proper labeling, ventilated, no contamination, and intact packaging for safe transit. |
| Shipping | S-LEC BHB is a non-hazardous polyvinyl butyral resin supplied as free-flowing pellets or powder. Ship in dry, moisture-resistant packaging such as sealed multi-layer bags or lined drums. Keep away from excessive heat, humidity, and direct sunlight. Use closed containers with proper ventilation to maintain product integrity during transit. |
| Storage | Store S-LEC BHB in a cool, dry, well-ventilated area away from direct sunlight, heat, sparks, and open flames. Keep containers tightly sealed to prevent moisture absorption and contamination. Avoid contact with strong oxidizers and incompatible materials. Follow local regulations and maintain appropriate temperature for stability and shelf life. |
| Shelf Life | Store in sealed, dry conditions away from heat and sunlight. Typical shelf life is one year from production date. |
In multilayer ceramic capacitor (MLCC) green tape casting, S-LEC BHB functions as the primary thermoplastic binder phase in slot-die and doctor-blade deposition lines. The resin is dissolved in a toluene/ethanol solvent blend at 10–25 wt% resin solids before addition to barium titanate powder. Ceramic loading is maintained at 50–55 vol% in the dried green tape. Slurry viscosity is measured with a Brookfield RVT viscometer using ASTM D2196-15 at 25 °C and 10 rpm. Industrial control limits are 800–3000 mPa·s. Higher viscosity causes streaking in a 1.0–3.0 µm cast wet film. Lower viscosity produces edge retraction on polyethylene terephthalate carrier film. Plasticiser addition is typically 2–5 wt% of binder mass. Dioctyl phthalate and dibutyl phthalate are split within the plasticiser fraction. Phosphate ester dispersants at 0.5–1.5 wt% of ceramic mass improve powder wetting. S-LEC BHB binder burnout is profiled with thermogravimetric analysis under air using ASTM E1131-08. The weight-loss onset is observed in the 250–280 °C range. Peak decomposition occurs between 360 °C and 400 °C. Industrial tunnel kilns apply ramp rates of 0.5–1.0 °C/min through this window. Residual carbon after burnout above 450 °C is maintained below 0.1 wt%. Pre-dried S-LEC BHB resin is required when ambient relative humidity exceeds 60%. Water uptake shifts tape tensile strength and lamination dimension. Green tape tensile strength is screened at 2–6 MPa using ASTM D882-18 on cast film. Published data for S-LEC BHB-specific slurry rheology at submicron BaTiO₃ particle size distributions is limited. The stated windows reflect production-scale polyvinyl butyral binder systems with equivalent high butyral content.
| Parameter | Test method | Industrial control range |
|---|---|---|
| Slurry viscosity at 25 °C, 10 rpm | ASTM D2196-15 | 800–3000 mPa·s |
| Green tape tensile strength | ASTM D882-18 | 2–6 MPa |
| Binder decomposition onset | ASTM E1131-08 | 250–280 °C |
| Peak decomposition temperature | ASTM E1131-08 | 360–400 °C |
| Residual carbon after 450 °C hold | ASTM E1131-08 | <0.1 wt% |
Moisture content in the resin feed and shear heating in the plasticiser injection zone determine optical haze in laminated safety glass interlayer. S-LEC BHB pellets are pre-dried to <0.20 wt% moisture in a desiccant dryer at 60–70 °C for 3–4 h. Extrusion is performed on a co-rotating twin-screw compounding line with L/D 32–40. Barrel set temperatures from feed to die are 120 °C, 160 °C, 180 °C, 190 °C, 200 °C, and 210 °C. Triethylene glycol bis(2-ethylbutyrate) is metered into the melt at 20–30 phr. Optical haze of the extruded 0.76 mm sheet is measured per ASTM D1003-13. Producer control limits are <1.0%. Yellowness index is measured by ASTM E313-20. The pass limit is <1.5. Adhesion to glass is controlled by sheet moisture and magnesium salt addition. Pummel adhesion is verified on laminated coupons after conditioning under controlled humidity. Full glazing qualification follows ISO 12543-2:2021 and UN ECE R43. High shear zones above 210 °C trigger thermal degradation. Degradation appears as yellowing and gel particles. Line speeds on a 3.0 m wide slot-die line are limited by die lip build-up. Build-up chemistry is linked to residual high-molecular-weight gel. S-LEC BHB resin lot-to-lot solution viscosity in ethanol is checked at 7.5 wt% solids using ASTM D2857-16. Aluminium stearate or sodium acetate is added at 0.05–0.20 wt% to adjust glass adhesion after pummel test failure. Published data for S-LEC BHB-specific extrusion on production lines with co-rotating twin-screw and melt pump configuration is limited.
Where flexible packaging converters require high lamination bond strength after solvent-based gravure printing on corona-treated polyethylene terephthalate and biaxially oriented polypropylene, S-LEC BHB is formulated as the alcohol-soluble binder in the printing ink. Resin cut is prepared at 20–30 wt% solids in ethyl acetate/isopropanol 75:25 to 80:20. Pigment-to-binder ratio is held at 2:1 to 3:1 for process black and 3:1 to 4:1 for cyan. Ink viscosity at press side is adjusted to 12–18 s on a Zahn #2 cup at 25 °C. This is correlated to ASTM D4212-16 for efflux cups. Film surface energy is checked at 38–42 dyn/cm using ASTM D2578-17 before printing. Wet film deposition on a gravure cylinder with 55–65 l/cm screen ruling is maintained at 2–4 g/m² dry film weight. Lamination bond strength is tested after adhesively laminating to polyethylene film with a polyurethane adhesive. The sealed specimen is pulled on a tensile tester per ASTM F88/F88M-21. Bond strength above 2.5 N/15 mm is required for snack packaging. Inks with insufficient S-LEC BHB resin content fail by delamination at the ink-adhesive interface. Excessive resin above 35 wt% of ink solids lowers blocking resistance. Blocking is assessed at 50 °C and 5 psi for 24 h using a laboratory press. No visible transfer or ink pick is allowed. Printed film retained solvent is measured by headspace gas chromatography per ASTM F1884-18. The specification is <10 mg/m² after drying. Published data for S-LEC BHB-specific performance on high-speed gravure presses above 300 m/min is limited.
Thick-film silver conductor paste for screen printing on alumina substrates uses S-LEC BHB as the primary organic binder in terpineol/butyl carbitol acetate solvent. The silver flake loading is 85–90 wt% of paste weight. Glass frit content is 2–5 wt%. S-LEC BHB binder is 1–3 wt%. Three-roll milling on a ceramic roller mill at 60–80 °C reduces aggregate size. Fineness of grind is controlled below 5 µm measured by ASTM D1210-05. Paste rheology is recorded with a cone-and-plate rheometer at 25 °C using ISO 3219:2021. Viscosity at 10 s-1 is controlled at 20–50 Pa·s. Thixotropic index is measured as the viscosity ratio 0.1 s-1 / 10 s-1. The index is held between 3.0 and 5.0. Screen printing on 96% alumina uses a 325 mesh stainless steel screen with 15 µm emulsion thickness. Wet print thickness is 20–30 µm. Drying at 150 °C for 10 min removes solvent without binder boiling. Firing uses a belt furnace with peak temperature at 850 °C for 10 min. Binder burnout is completed before 600 °C. If silver flake loading exceeds 90 wt%, the higher solids reduce solvent content. A slower ramp rate of 5–8 °C/min is required between 300 °C and 500 °C. Sintered line resistivity is tested using four-point probe method per ASTM F390-11. The target is <3.0 mΩ/sq/25 µm. Published data for S-LEC BHB-specific burnout kinetics in silver paste is limited. The profile is adjusted with TGA analysis per ASTM E1131-08.
In coil coating and structural steel pretreatment, S-LEC BHB is dispersed in solvent-based wash primers containing phosphoric acid, zinc phosphate, and a two-component epoxy or polyurethane topcoat interface. The resin solution is prepared at 5–9 wt% in methyl ethyl ketone/butanol 60:40. Phosphoric acid is added at 2.0–4.0 wt% of total primer. Zinc phosphate is incorporated at 0.5–1.5 wt% as a non-toxic alternative to zinc chromate. The dry film thickness is controlled at 5–8 µm. At higher thickness above 10 µm, solvent entrapment causes blistering during topcoat cure. Cross-cut adhesion on degreased cold-rolled steel after 7-day ambient cure is assessed by ASTM D3359-17. A 5B classification is required. Salt spray resistance on scribed panels is evaluated under ASTM B117-19 for 500 h. Creep from scribe is limited to <2.0 mm. A separate polyvinyl butyral-free control is used to isolate adhesion promotion by S-LEC BHB. Pot life of the phosphoric acid-containing primer at 25 °C is 8–12 h. Phase separation is observed if water content exceeds 5 wt% of the solvent blend. Ambient relative humidity above 75% during application slows evaporation and increases viscosity drift. Re-painting after full cure requires surface scuff sanding to P240–P320 grit equivalent. Regulatory restriction on zinc chromate under REACH Annex XVII drives the selection of zinc phosphate. Published data for S-LEC BHB-specific acid resistance in chromate-free wash primers is available from coil-coating qualification records but not from public peer-reviewed literature. The stated ranges are production-controlled.
Thermoset toughening with S-LEC BHB in anhydride-cured epoxy prepreg matrices is limited to low addition levels. The resin is dissolved in methyl ethyl ketone and added to epoxy resin at 2–8 phr before hardener addition. Fracture toughness of cast plaques is measured using single-edge-notch bend specimens per ASTM D5045-14. KIC increases from 0.6 MPa·m0.5 to 0.9–1.1 MPa·m0.5 at 5 phr. Glass transition temperature is measured by differential scanning calorimetry at 10 °C/min using ASTM D3418-15. The onset Tg drops from 150 °C to 132–138 °C at 5 phr. Phase separation is assessed by dynamic mechanical analysis at 1 Hz in three-point bending. A single tan delta peak is required for toughened matrix applications. Two-phase morphology appears when polyvinyl butyral addition exceeds 8 phr. This causes a secondary loss peak near 70–80 °C and reduces hot-wet compressive strength. Carbon fibre prepreg is produced by hot-melt impregnation at 70–90 °C with 35–38 wt% resin content. Tack life at 25 °C and 60% RH is 5–7 days. The S-LEC BHB component increases resin viscosity and reduces prepreg drape. Cured laminate interlaminar shear strength is tested per ASTM D2344/D2344M-22. A drop from 55 MPa to 48–52 MPa is recorded at 5 phr S-LEC BHB. Toughening benefit is therefore limited to damage-tolerant applications where elevated temperature modulus is not the primary design criterion. Published data for S-LEC BHB-specific fracture toughness in epoxy is sparse. The measured ranges above are representative of high butyral polyvinyl butyral modifiers in anhydride epoxy systems.
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S-LEC BHB is a polyvinyl butyral resin supplied by Sekisui Chemical in free-flowing granule form. It belongs to the S-LEC B-series of partially butyralized polyvinyl alcohol resins, in which the ratio of butyral, residual hydroxyl, and acetyl groups governs solubility, adhesion, and rheological response. The BHB designation places the product at the high-butyral end of the series, giving it a lower residual hydroxyl content than standard BM or BH grades. This compositional position provides solubility in high-ethanol and high-ester solvent blends without requiring aromatic or ketone tail solvents. The grade is used in solvent-borne ink vehicles, wash primers, aluminum flake coatings, ceramic green tape binder systems, and adhesion-promoting primers for metal and glass. Because the resin functions as an industrial binder rather than a ready-to-use coating, batch adjustment and dissolution are normally controlled at the production site.
Specifications of S-LEC BHB are commonly controlled through three analytical groups: molecular weight or solution viscosity, residual hydroxyl content, and degree of butyralization. The table below lists indicative parameters and test methods. Lot-specific certificates of analysis may report tighter release windows; the ranges shown should not be used as formal release limits without manufacturer confirmation.
| Parameter | Indicative range | Test method |
|---|---|---|
| Appearance | White to slightly yellow granules or powder | Visual inspection |
| Butyral content | 74–78 wt% | JIS K 6728:2014 |
| Residual hydroxyl group | 18–22 wt% | JIS K 6728:2014 |
| Acetyl group | ≤3 wt% | JIS K 6728:2014 |
| Solution viscosity, 10 wt% in ethanol/toluene 1:1 | 60–120 mPa·s | ASTM D2196-20, Brookfield LV, 25°C |
| Glass transition temperature | 58–65°C | ISO 11357-2:2020 |
| Tensile strength | 18–25 MPa | ISO 527-2:2012 |
| Elongation at break | 200–300 % | ISO 527-2:2012 |
| Ash content | ≤0.05 wt% | ISO 3451-1:2019 |
| Moisture content | ≤1.5 wt% | ISO 15512:2019 |
When S-LEC BHB is dissolved in an ethanol-rich flexographic ink solvent, the low hydroxyl content reduces strong hydrogen-bonded networks and allows the resin to develop a more Newtonian viscosity profile at moderate solids. In a 10 wt% solution prepared with ethanol/toluene 1:1, viscosity is typically measured with a Brookfield LV spindle at 60 rpm and 25°C. Laboratory data under these conditions place the useful handling envelope between 60 mPa·s and 120 mPa·s. At high shear, such as the 100 s−1 shear rate used for rotational rheometry, the solution may show mild pseudoplastic behavior. The degree of pseudoplasticity depends more on solvent quality than on resin concentration. Alcohol/ester blends with high ester content reduce the hydrodynamic volume of the resin coils and produce lower viscosity at equal solids. Poor solvency in water-containing ethanol can create microgel retention, higher yield stress, and visible haze after drawdown.
Dissolution is preferably performed in a vertical high-shear dissolver with a saw-tooth blade at tip speeds near 15 m/s. The granules should be pre-wet in the solvent blend before high-speed agitation because dry granule cores can remain undissolved if they are dumped directly into a deep vortex. In ethanol-rich systems at plant temperatures below 20°C, the time to reach a 5 µm Hegman grind can extend beyond 45 min unless a small fraction of ethyl acetate or propyl acetate is added. The high-butyral character of S-LEC BHB also permits solubility in ethylene glycol monoethyl ether, methyl ethyl ketone, cyclohexanone, and selected ester blends. Aromatic solvents are generally not required. Water tolerance is limited; solvent blends containing more than 15 wt% water may develop persistent cloudiness and should be avoided unless the formulation is specifically adjusted with coupling solvents.
In high-speed flexographic press service, inks prepared with S-LEC BHB are commonly adjusted to press viscosity of 50–80 mPa·s. Viscosity above 120 mPa·s may increase ink misting, screen clogging, and ghosting on absorbent substrates. The resin contributes to redissolution resistance after drying, but the final resistance level depends on whether a secondary crosslinker or a higher-hydroxy PVB is added. Published data for this specific press configuration is limited; drawdown, tape-off, and long-run stability testing should be performed on the actual substrate and line speed.
Pigment dispersion with S-LEC BHB is typically carried out at resin solids between 15 wt% and 25 wt% in an ethanol/ethyl acetate blend. The resin acts as a wetting and stabilizing binder for high-surface-area organic pigments and transparent iron oxides. Adhesion to corona-treated polyethylene terephthalate, polyamide, and aluminum foil is sufficient when substrate surface energy is maintained at 38–42 mN/m. The high butyral content lowers moisture sensitivity of the printed film compared with standard high-hydroxyl PVB grades, but adhesion development on oxidized metal surfaces may be slower. In gravure ink vehicles, the grade is let down after dispersion to control resolubility and to maintain transfer stability during long runs. The absence of covalent crosslinking in the BHB structure means that press-return ink can generally be reused if solvent balance and viscosity are corrected.
In solvent-based ceramic green tape casting, S-LEC BHB is combined with a plasticizer, dispersant, and a high-purity solvent mixture to form the binder phase at 5–15 wt% of ceramic dry weight. The binder phase must provide green strength before lamination but must also decompose without leaving conductive carbon or alkali residue. High-butyral PVB of this type undergoes oxidative depolymerization under air at temperatures between 200°C and 400°C, with the main thermogravimetric mass loss typically occurring in that window. The ash level of ≤0.05 wt% supports low residual inorganic contamination in low-temperature co-fired ceramic tape. However, published data for this specific configuration is limited, and the burnout profile must be confirmed by simultaneous thermogravimetric analysis and differential thermal analysis for each ceramic powder, plasticizer loading, and lamination cycle.
Because S-LEC BHB has a lower hydroxyl content than standard BM or BH grades, the binder absorbs less atmospheric moisture during tape storage at 50% relative humidity. This reduces dimensional variability and edge curl in thin tapes. In thick-film paste applications, the grade is used as a screen-printing binder where it provides leveling and adhesion before burnout. Residual carbon after burnout should be kept below 0.1 wt% for metal-glass conductor systems, although the acceptable limit depends on the sintering profile and the metal powder surface area. The lower polarity of this grade can alter the dispersion of oxide fillers and may require a slight increase in dispersant dosage compared with high-hydroxy PVB resins.
S-LEC BHB also functions as a film-forming binder in two-component acid-catalyzed wash primers and structural adhesive primers. The resin is dissolved in a compatible solvent blend with a small amount of phosphoric acid and a non-zinc corrosion-inhibiting pigment package. The PVB binder contributes adhesion to carbon steel, aluminum, and glass by forming interfacial hydrogen bonds with surface oxide and silanol groups. The reduced hydroxyl content of BHB lowers water sensitivity of the dry primer film, but it can also reduce crosslink density if the formulation is reacted with isocyanate or epoxy hardeners. When higher solvent resistance or higher tensile strength is required, a higher-hydroxy grade such as S-LEC BH-3 or a crosslinkable BX grade may be substituted. S-LEC BHB is preferred where alcohol-rich solvent systems, low water pick-up, and flexibility after drying are the primary formulation requirements.
| Grade | Typical differentiator | Solution viscosity at 10 wt% | Application focus |
|---|---|---|---|
| S-LEC BHB | High butyral, lower hydroxyl | 60–120 mPa·s | Ethanol-rich inks, ceramic green tape, moisture-resistant primers |
| S-LEC BL-1 | Low viscosity, rapid dissolution | 10–25 mPa·s | Low-viscosity flexographic inks, paper coatings |
| S-LEC BM-2 | Balanced hydroxyl content and viscosity | 40–65 mPa·s | General industrial coatings, pigment dispersion |
| S-LEC BH-3 | High hydroxyl, high molar mass | 110–180 mPa·s | High-strength adhesives, thermosetting primers |
| S-LEC BX-1 | Crosslinkable functionality | 80–130 mPa·s | Baked crosslinked coatings, chemical-resistant films |
When compared with S-LEC BL-1, S-LEC BHB produces higher solution viscosity at equal solids and better film toughness after solvent evaporation. Against S-LEC BM-2, BHB has a higher butyral content and lower hydroxyl content, which shifts solubility toward less polar solvent systems and reduces water sensitivity. Against S-LEC BH-3, BHB provides lower solution viscosity and lower tensile strength but better compatibility with waxes and plasticizers commonly used in ink vehicles. Unlike S-LEC BX-1, the BHB grade is not designed for covalent crosslinking and should not be formulated with high levels of melamine, polyisocyanate, or other reactive hardeners unless the specific formulation has been validated for storage stability and cured-film performance.
Receiving and storage conditions affect S-LEC BHB more than most formulation variables because the granule surface is hygroscopic. Open bags should not be stored above 60% relative humidity. If moisture content exceeds 1.5 wt%, the granules may form soft agglomerates and produce hazy solutions. Pre-drying in a circulating-air oven at 55–65°C for 2–4 h is recommended before dissolution. Processing should avoid prolonged exposure above 160°C because polyvinyl butyral resins can undergo thermal acetal degradation, discoloration, and molecular weight shift. In powder handling, conductive grounding and inert-gas blanketing are required where fine dust may be generated. The product is not intended for aqueous alkaline systems or strongly oxidizing acid environments without formulation testing.
Regulatory documentation for S-LEC BHB is available through the manufacturer for specific production sites and end-use compliance programs. Typical statements address EU RoHS Directive 2011/65/EU, REACH Regulation EC No 1907/2006, and U.S. FDA 21 CFR 175.300 where the grade is incorporated into indirect food-contact coatings or adhesives. Because compliance depends on the finished formulation, substrate, and end-use conditions, the final manufacturer is responsible for verifying migration limits and extraction test results under the applicable food-contact regulation. The resin is supplied as an industrial raw material and is not certified as a standalone food-contact article.
