| HS Code | 103242 |
| Product Type | Polyvinyl butyral (PVB) interlayer film |
| Base Material | Polyvinyl butyral resin |
| Thickness | 0.38 mm |
| Density | 1.08 g/cm³ |
| Refractive Index | 1.48 |
| Tensile Strength | 25 MPa |
| Elongation At Break | 300% |
| Light Transmittance | 90% |
| Haze | <1% |
| Water Absorption | ≤0.5% |
| Glass Transition Temperature | 5°C |
| Adhesion To Glass | Excellent |
As an accredited S-LEC BH-3 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | S-LEC BH-3 is supplied in sealed paper bags with polyethylene liners, each containing 20 kg. |
| Container Loading (20′ FCL) | 20′ FCL loading of S-LEC BH-3: packed in sealed bags on pallets, securely stowed, protected from moisture and contamination. |
| Shipping | S-LEC BH-3 is a polyvinyl butyral resin supplied as a white, free-flowing powder. It is shipped in sealed, moisture-proof multi-layer paper or woven polypropylene bags, typically 25 kg net. Keep dry, away from heat and ignition sources. It is not classified as dangerous goods for transportation. |
| Storage | Store S-LEC BH-3 in a cool, dry, well-ventilated area away from direct sunlight, heat, and ignition sources. Keep the original container tightly closed to prevent moisture absorption and contamination. Avoid contact with strong oxidizers. Maintain moderate temperatures and low humidity. Use proper handling to prevent dust accumulation. Follow manufacturer’s guidelines for shelf life and disposal. |
| Shelf Life | S-LEC BH-3 has a shelf life of approximately two years when stored in a cool, dry place, avoiding moisture and direct sunlight. |
S-LEC BH-3 is a high-molecular-weight polyvinyl butyral resin whose manufacturer-reported 10 wt% solution viscosity in 1:1 ethanol/toluene at 20°C falls within the 40–80 mPa·s range, placing it in the higher-viscosity segment for solvent-borne binder applications where film toughness and lamination bond are weighted over low-solids flow. In flexographic and gravure lamination inks for non-direct food-contact structures, the resin is introduced as a co-binder at 4–9 wt% of the final press-ready formulation, typically after pre-dissolution to a 15–20 wt% solids solution in an 80:20 ethanol/ethyl acetate blend. The hydroxyl functionality in the 20–24 mol% range contributes pigment wetting on corona-treated polyethylene terephthalate and promotes adhesion to metalized polyester layers without the haze tendency associated with lower-hydroxyl grades. Compliance for printed packaging follows EU 10/2011 where the print is separated from food by a functional barrier, with manufacturing discipline under EC 2023/2006 and formulation documentation aligned to Swiss Ordinance SR 817.023.21; U.S. submissions rely on 21 CFR 175.300 where the dried ink film functions as a resinous or polymeric coating. High-shear predispersion on a Cowles disperser at 12–15 m/s tip speed is followed by letdown and viscosity adjustment to 18–25 s Zahn Cup #2 at 20°C; final fineness of grind is checked by ASTM D1210 at ≤10 µm. The printed substrate proceeds through gravure or flexographic transfer, drying tunnel retention at 60–70°C, and in-line adhesive lamination.
Resin pre-drying at 60°C for 2–4 h is required when warehouse relative humidity exceeds 60%, because absorbed moisture shifts solvent release and may create retained-solvent odour in sealed laminates. On production presses, the addition ratio is adjusted downward when cylinder engraving increases ink film thickness, while higher loading above 9 wt% can raise press viscosity beyond the range suitable for shallow anilox cells and prolong drying tunnel dwell. Terminal formats include surface-printed polyester/polyethylene snack packaging, boil-in-bag lamination structures, and metallized film pouches where interlayer adhesion after lamination is specified by ISO 8510-1 peel testing.
In multilayer ceramic capacitor green tape, S-LEC BH-3 serves as a temporary organic binder that must leave ≤0.05 wt% residual carbon after debinding while maintaining tensile strength in the unsintered sheet. The slip is prepared by dissolving the resin at 15 wt% in a solvent blend of ethanol, toluene, and methyl ethyl ketone, then adding the solution to barium titanate-based dielectric powder at 10–15 parts by weight per 100 parts ceramic powder. External plasticizer is metered at 3–6 phr to keep the dried tape flexible enough for roll handling. The slurry is milled in a planetary ball mill with 1 mm YTZ grinding media for 12–24 h, then cast through a slot-die coater onto silicone-coated PET at 60–80°C drying temperature. Terminal component qualification follows IEC 60384-22 for surface-mount multilayer ceramic capacitors, with material restrictions under Directive 2011/65/EU RoHS and automotive stress testing per AEC-Q200 for engine-control applications.
On production-scale coaters, edge build-up at the die lip occurs when slip viscosity exceeds 3,500 mPa·s at 10 s⁻¹; this is a documented bottleneck because large-area ceramic tape thickness tolerances tighten as dielectric layer thickness falls below 1.5 µm. Published data for S-LEC BH-3 in 10 µm green tape are limited, so pilot-scale ramp studies are required before converting a full production lot. The binder must be protected from humidity above 60% RH and stored in sealed vessels because moisture uptake alters slurry rheology and increases agglomerate formation after milling. Terminal components produced from this process include 0402, 0603, and 0805 MLCCs for handheld devices, power modules, and automotive ECU circuits.
| Stage | Control variable | Operating window | Reference method |
|---|---|---|---|
| Slurry dispersion | Viscosity at 20°C | 1,500–3,500 mPa·s at 10 s⁻¹ | ISO 3219 |
| Tape drying | Residual solvent | ≤1.2 wt% before stacking | ISO 3251 |
| Debinding ramp | Heating rate | 0.5–1.0°C/min between 150°C and 350°C | Thermogravimetry |
| Binder burnout hold | Residual carbon | ≤0.05 wt% after 350°C hold | Combustion analysis |
In two-component wash primer formulation for aerospace and architectural metal pretreatment, S-LEC BH-3 is dissolved into a solvent phase at 6–9 wt% of the mixed primer, with phosphoric acid at 2–4 wt% and a pigment package containing zinc phosphate or zinc chromate where local regulation permits. The acid-etch PVB matrix forms a thin anchor layer for subsequent epoxy or polyurethane topcoats; without adequate PVB film formation, the acid remains unbound and topcoat adhesion under humid service deteriorates. Application by HVLP spray deposits 8–12 µm dry film thickness onto degreased and sanded surfaces prepared to SSPC-SP 1 cleanliness; pot life at 20°C is typically 4–8 h, and ambient temperatures above 30°C accelerate acid-catalysed acetal hydrolysis, shortening usable application time. Adhesion is qualified by ISO 4624 pull-off or ASTM D3359 cross-cut, while neutral salt spray resistance is evaluated per ASTM B117 for 500–1,000 h depending on the topcoat system. The relevant military specification MIL-C-8514C is used in MRO environments where replacement primers must match original shop coats. Terminal components include aluminium wing skins, architectural extrusions, and galvanised steel panels. Amine-based additives should not be blended into the catalyzed wash primer because neutralization of phosphoric acid reduces etch action and can cause premature precipitation of the PVB binder.
Compounding of S-LEC BH-3 into a plasticized interlayer sheet is performed on a co-rotating twin-screw extruder with 40:1 L/D, where the resin fraction is maintained at 60–70 wt% of the compound and triethylene glycol bis(2-ethylhexanoate) plasticizer is metered at 30–38 phr. Melt temperature is held between 150°C and 170°C; excursions above 180°C increase the risk of acetal degradation and yellowing, while insufficient plasticizer dispersion produces haze bands in the cast film. The melt is extruded through a slot die into a calender stack to a final thickness of 0.76 mm for automotive glazing or 1.52 mm for architectural impact glazing. Lamination into glass is completed in an autoclave at 140°C and 1.2 MPa for 90 min, following nip-roll prelamination. Adhesion performance is assessed under ISO 12543, with windshield qualification to ECE R43 and, for North America, ANSI Z26.1.
A documented failure mode is plasticizer edge migration when interlayer rolls are stored above 40°C or at relative humidity above 50%; migrated plasticizer reduces edge tack and produces visible delamination after autoclave cycling. Batch-to-batch variance in resin hydroxyl content alters glass adhesion, requiring incoming lot checks because laminators adjust adhesion control additives only within narrow limits. Terminal finished products include laminated windscreens, side glass, and architectural safety glazing for overhead and impact-rated facades.
Gravure coating of S-LEC BH-3-based heat-seal lacquers onto 20–25 µm hard-rolled aluminium foil is controlled by dry coat weight rather than wet film thickness. The resin is formulated at 15–25 wt% of non-volatile lacquer solids, applied at 3–5 g/m² dry, and dried through a multi-zone tunnel with peak web temperature 120–160°C. The coated foil is subsequently sealed to PVC or PVDC blister webs at 160–180°C under 0.4 MPa for 0.3–0.5 s; peel strength is normally verified at ≥6 N/15 mm by ISO 8510-1. Regulatory conformance is established under EU 10/2011 for plastic materials intended to contact pharmaceuticals, with supporting data per USP Chapter 661.1 for packaging components and FDA 21 CFR 175.300 for resinous coating formulations. Terminal products are push-through blister lidding foils for oral solid dose pharmaceuticals. Storage of coated rollstock above 25°C and 50% RH increases blocking tendency and reduces seal consistency; moisture-permeable interleaving is avoided because PVB is hygroscopic.
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S-LEC BH-3 is a polyvinyl butyral resin manufactured by Sekisui Chemical Co., Ltd. and supplied under the S-LEC trademark. In manufacturer documentation the grade may also be written S-LEC B H-3; both designations refer to the same high-molecular-weight polyvinyl butyral type. The polymer is a random acetal of polyvinyl alcohol with butyraldehyde and contains residual hydroxyl and acetate groups. Published datasheet ranges typically specify a polyvinyl alcohol content of 24.0–27.0 wt% and a polyvinyl acetate content of 0–2.0 wt%, with the balance being polyvinyl butyral. The CAS RN is 63148-65-2. The resin is supplied as a white powder or granules, with non-volatile matter not less than 98.0 wt% when determined by ISO 3251 at 105 °C for 3 h. A 10 wt% solution in ethanol/toluene (1:1) at 20 °C shows a viscosity of 28–44 mPa·s under DIN 53015. The glass transition temperature determined by differential scanning calorimetry under ISO 11357-2 is typically reported at 65–70 °C, and density by ASTM D792 is 1.08–1.11 g/cm³. Acid number is below 0.1 mg KOH/g according to ISO 2114. These values position S-LEC BH-3 between BM-1 and BH-6 in the S-LEC B grade ladder. The present document reviews industrial applications in coatings, ceramic processing, printing inks, and heat-seal formulations; it is not a safety data sheet.
The commercial S-LEC B series is differentiated primarily by solution viscosity rather than by hydroxyl or acetate content alone. S-LEC BH-3 shares the hydroxyl window of 24.0–27.0 wt% with BM-1 and BH-6 but exhibits a higher solution viscosity than BM-1 and a lower solution viscosity than BH-6. This difference controls solvent demand, coating solids, shear stability, and green strength in temporary-binder applications.
| Grade | 10% solution viscosity in ethanol/toluene (1:1) at 20 °C | Polyvinyl alcohol content | Polyvinyl acetate content | Molecular-weight position |
|---|---|---|---|---|
| BL-1 | 7–14 mPa·s | 20–24 wt% | 0–2 wt% | Low |
| BM-1 | 9–16 mPa·s | 24–27 wt% | 0–2 wt% | Medium |
| BH-3 | 28–44 mPa·s | 24–27 wt% | 0–2 wt% | High |
| BH-6 | 54–78 mPa·s | 24–27 wt% | 0–2 wt% | Very high |
A formulator replacing BH-6 with BH-3 can raise solids at equal application viscosity or reduce solvent use, but may sacrifice cohesive strength and upper service-temperature resistance. Conversely, replacing BM-1 with BH-3 raises viscosity and improves film toughness but requires solids adjustment in gravure or roller coating. These trade-offs are evaluated on production equipment because blade gap, nip geometry, and drying-air configuration alter the practical viscosity ceiling.
Polyvinyl butyral is thermally labile before a stable melt can be established, and melt flow rate under ISO 1133-1:2022 is therefore not used as a lot-control parameter. The relevant molecular-weight metric is the 10 wt% solution viscosity measured in ethanol/toluene (1:1) at 20 °C under DIN 53015. For S-LEC BH-3, the 28–44 mPa·s window places the grade in the high-molecular-weight segment, which influences dissolution time, pigment wetting, and the onset of shear-induced phase separation in solvent blends. In a production dissolver, a 10 wt% BH-3 solution in ethanol/ethyl acetate may require 60–90 min at 30–40 °C under low shear; using BH-6 extends this dissolution time, while BM-1 dissolves faster but gives lower solution elasticity. The dissolved resin remains Newtonian over a practical coating-shear range, but the high-molecular-weight tail in BH-3 produces greater extensional viscosity than BM-1, which is beneficial for fiber resistance in roll coating and can cause ribbing if cylinder speed and solvent balance are not adjusted.
On a continuous coil-coating line operating at 25–40 m/min, S-LEC BH-3 is typically introduced as a 10 wt% stock solution in an ethanol/n-butanol blend before letdown. A representative wash-primer composition for zinc-coated steel contains 7.0–9.0 wt% BH-3 solids, 2.0–4.0 wt% phosphoric acid as an 85% aqueous solution, 6.0–10.0 wt% zinc tetroxychromate or zinc phosphate pigment, and an alcohol diluent. Application viscosity is normally controlled at 18–25 s in a DIN 4 mm cup at 20 °C. At 5–8 g/m² dry film weight, the resin’s high hydroxyl content supports wetting of degreased metal and recoat adhesion with epoxy or polyester topcoats. The system is validated under ISO 12944-6 for the relevant C3 or C4 atmospheric corrosivity class. BH-3 is preferred over BM-1 in coil primers because of higher cohesive strength and better resistance to mechanical damage during coil handling. BH-6 may be used in airless spray formulations, but for high-speed roll coaters BH-3 gives a broader application window and lower cobwebbing tendency. Acid should be added slowly to the cooled resin solution, and the mixed primer has a limited pot life; the exact pot life depends on pigment surface chemistry and acid concentration.
Tape casting for multilayer ceramic capacitors uses a solvent-based slurry in which S-LEC BH-3 functions as a temporary organic binder. The resin is predissolved in a toluene/ethanol azeotrope or MEK/ethanol mixture at 8–12 wt% resin based on ceramic powder. Slurry viscosity is generally maintained at 1,500–4,000 mPa·s at 5 s⁻¹ on a Brookfield viscometer. This range supports doctor blade casting at wet thicknesses of 50–200 µm on polyethylene terephthalate carrier film. The plasticizer-to-binder mass ratio is a critical boundary: below 0.20, dried tape shows edge cracks after punching and incomplete lamination at 20–50 MPa and 50–70 °C; above 0.40, sheet distortion occurs during lamination and screen registration. Binder burnout requires a two-stage thermal profile. Initial weight loss is observed at 180–220 °C, with main-chain oxidation at 350–450 °C. Residual carbon above 0.05 wt% of ceramic mass can reduce dielectric insulation resistance in the sintered capacitor body. Air flow and a controlled ramp of 0.5–2.0 °C/min to 650 °C are commonly used to control carbon removal. S-LEC BH-3 is selected over BM-1 when punching, stacking, and electrode printing require higher green strength. It is selected over BH-6 when the slurry must remain flowable at higher solids or when solvent recovery limits require a lower-viscosity binder at the same solids content.
For solvent-based gravure and flexographic inks on surface-treated polyester and biaxially oriented polypropylene films, S-LEC BH-3 functions as the pigment-wetting binder and thermal lamination primer. Compared with BM-1, it increases low-shear viscosity and reduces pigment settling, but at equal press viscosity the formulator must reduce solids by approximately 8–15% relative to BM-1. In ethanol/ethyl acetate blends, dissolution is slower than BM-1; dissolver time at 30–40 °C may extend from 60 min to 90 min. Residual solvent after drying should be controlled below 5 mg/m² by headspace gas chromatography using ISO 11890-2, particularly when the printed film is subsequently laminated with solventless polyurethane adhesives. The high-molecular-weight fraction in BH-3 contributes to bond strength on corona-treated polyester and aluminum foil after a 40–60 °C lamination nip. Quantitative peel values vary with substrate surface energy, ink pigment volume concentration, and adhesive grade; published data for this specific resin-substrate configuration is limited, and production-scale lamination trials on the target line remain the controlling test.
S-LEC BH-3 is used in gravure-applied heat-seal coatings where BH-6 raises high-shear viscosity and increases solvent retention. At 20 wt% solids in a MEK/toluene mixture, BH-3 exhibits lower viscosity than BH-6 and permits cylinder coating without dilution below 20 wt%. Plasticization with dibutyl sebacate or dioctyl adipate at 10–30 phr reduces the heat-seal activation temperature to 95–120 °C on PET and aluminum foil. Below 10 phr, the coating may block on the reel at 35–40 °C; above 30 phr, cold flow and blocking increase. Heat-seal strength is measured by ASTM F2029 on a laboratory press with jaw pressure of 0.3–0.5 MPa. Because BH-3 has a higher molecular weight than BM-1, it gives better hot-tack and seal strength after solvent removal. Because it has a lower molecular weight than BH-6, it shows lower solution elasticity and fewer ribbing defects at high coating speed. The processing advantage is therefore specific to high-solids formulations near the viscosity limit of the metering roll.
Production-scale handling, drying, and storage boundaries are governed by the resin’s hygroscopicity and thermal lability. At relative humidity above 60%, the powder should be pre-dried in a desiccant dryer at 50–60 °C for 2–4 h before dissolution. Dissolution is normally performed in a closed low-shear dissolver at 30–50 °C; temperatures above 60 °C may accelerate acetal hydrolysis and color formation. Strong alkalis, concentrated oxidizing acids, and certain amine-based additives can promote degradation or gel formation and should be kept out of the resin solution unless they are part of a validated wash-primer formulation at controlled concentration. Aqueous alkaline cleaning solutions should not be used on process equipment until PVB residues are removed with alcohol. Storage in original sealed containers at ≤ 35 °C and dry conditions is recommended, with a shelf life of 24 months from the certificate of analysis date when unopened. In ceramic and coating plants, the resin should be metered with loss-in-weight equipment to avoid bridging in hoppers at high humidity. These limits are derived from standard PVB handling practice and supplier technical bulletins, not from a single-lot observation.
Regulatory status for S-LEC BH-3 is lot-dependent. The following matrix is a review aid, not a substitute for supplier certification or a local safety data sheet.
| Regulatory or technical reference | Scope | Typical status for S-LEC BH-3 |
|---|---|---|
| REACH (EC) No 1907/2006 | EU substance registration | Registered for supplied grades; confirm registration number and tonnage band with the EU SDS |
| RoHS Directive 2011/65/EU Annex II | Heavy metal and brominated flame retardant restrictions | No intentionally added Pb, Cd, Hg, Cr(VI), PBB, or PBDE; article-level compliance depends on the formulated product |
| FDA 21 CFR 177.1670 | Polyvinyl butyral film for food contact | Applies to finished film, not resin powder; confirm end-use compliance |
| FDA 21 CFR 175.105 | Adhesives for food packaging | Applicable to formulated adhesive if extraction limits are met; confirm with formulation data |
| TSCA inventory | U.S. chemical inventory | CAS RN 63148-65-2 listed |
| DIN 53015 | Solution viscosity | Lot-control method for molecular-weight classification |
| ISO 9001:2015 | Quality management | Manufacturing site certified; certificate version varies by location |
Substitution of S-LEC BH-3 for adjacent grades is not a direct drop-in where viscosity, drying rate, or solvent release is fixed. In a tape-casting line with fixed doctor blade gap and belt speed, changing from BH-6 to BH-3 without increasing solids or reducing the plasticizer ratio can lower wet-film build and produce edge slump. In a wash primer, replacing BM-1 with BH-3 at the same solids increases application viscosity and may require a solvent blend with more ethanol or n-propanol. In a heat-seal coating, replacing BH-6 with BH-3 improves leveling but reduces the upper block-resistance plateau during elevated ambient storage. Formulators typically run a design-of-experiments with resin solids, solvent ratio, and plasticizer content as variables, starting within ±2 wt% solids around the incumbent grade. Published data for these specific substitution ratios is limited, so production-scale trials on the target line remain the controlling test.
