| HS Code | 556464 |
| Product Name | S-LEC BH-A |
| Material | Polyvinyl butyral (PVB) |
| Application | Laminated safety glass interlayer |
| Thickness | 0.76 mm |
| Specific Gravity | 1.08 |
| Refractive Index | 1.49 |
| Light Transmittance | 90% |
| Haze | <1% |
| Tensile Strength | ≥20 MPa |
| Elongation At Break | ≥240% |
| Glass Transition Temperature | 20°C |
| Uv Cutoff | 380 nm |
As an accredited S-LEC BH-A factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | S-LEC BH-A is supplied in 25 kg net sealed polyethylene-lined kraft bags, palletized and wrapped for safe transport. |
| Container Loading (20′ FCL) | Load S-LEC BH-A in 20′ FCL, keep dry, secure pallets, avoid contamination and excess heat during transport. |
| Shipping | S-LEC BH-A is a polyvinyl butyral resin supplied as fine powder. Shipping should follow standard non-hazardous dry chemical handling: keep containers sealed, avoid moisture and humidity, store away from heat. No special transport classification required, but use adequate packaging to prevent spillage and maintain product quality. |
| Storage | Store S-LEC BH-A in a cool, dry, well-ventilated area away from direct sunlight, heat sources, and moisture. Keep the container tightly sealed when not in use to prevent water absorption and contamination. Avoid stacking heavy loads. Under recommended conditions, shelf life is typically 12 months from receipt. |
| Shelf Life | Shelf life: 24 months from manufacture date when stored in a cool, dry place in original sealed packaging. |
A two-component anti-corrosion wash primer is produced by dissolving S-LEC BH-A at 7.0–10.0 wt% in a solvent blend of methyl isobutyl ketone, n-butanol, and isopropanol in a 60:25:15 mass ratio; dissolution is completed in a jacketed mixer at 35–45 °C for 3–5 h under nitrogen. The acid component contains 85 % phosphoric acid at 3.0–4.5 wt% of the combined wet paint and a corrosion-inhibitive pigment, either zinc tetroxychromate or zinc phosphate, at a pigment-volume concentration of 20–30 %. The two components are mixed at the point of use, and pot life is limited to 8 h at 25 °C because acid-catalysed acetal ring opening increases viscosity and lowers adhesion. The primer is sprayed onto blasted carbon steel or conversion-coated aluminium as a 10–15 μm dry film. Cross-cut adhesion is tested according to ISO 2409:2020; classification 0 or 1 is required after 24 h at 23 ± 2 °C and 50 ± 5 % RH. Neutral salt spray resistance is evaluated per ISO 9227:2022 for 144–240 h under corrosivity class C3 or C4 selected from ISO 12944-2:2017. The base component is strained through a 100 μm mesh before loading into pressure-feed spray equipment; nozzle fluid pressure is 0.7–1.2 bar and atomizing air pressure is 2.5–3.5 bar for an air-assisted airless unit. Powder handling limitation: storage above 60 % RH or above 35 °C causes inter-particle sintering and gel seeds during dissolution; pre-drying in a hot-air oven at 40 °C for 2–4 h may be necessary. End products include structural steel primers, aircraft maintenance coatings, and rail rolling stock pre-paint systems.
Slip formulation for multilayer ceramic tape casting begins with dissolution of S-LEC BH-A at 4.0–8.0 wt% of dry ceramic powder in an ethanol/toluene 60:40 azeotrope or a methyl ethyl ketone/ethanol 2:1 mixture using a dissolver fitted with a saw-tooth disc. Butyl benzyl phthalate is added at 25–50 phr on resin; below 20 phr green tape edge curl occurs during casting, while above 55 phr blocking on the take-up reel occurs. Alumina with a median particle size of 0.4–0.8 μm or BaTiO₃ with 0.5–1.0 μm D50 is dispersed with a phosphate ester or menhaden fish oil at 0.5–1.2 wt% of solids. The slip is milled for 16–24 h with 3 mm zirconia media, then deaerated under 200–500 Pa vacuum for 15–30 min before casting. Tape is cast through a doctor blade gap of 100–300 μm onto 75–150 μm silicone-coated PET at 0.5–2.0 m/min. Three-zone drying at 50–80 °C should leave less than 1.0 % residual solvent measured by thermogravimetric analysis to prevent blocking and lamination shifts. Binder burnout is the critical threshold; profiles are typically 0.3–0.5 °C/min ramp to 350 °C, a 2 h hold, then a second ramp to 550–600 °C. A heating rate above 1.0 °C/min between 220 °C and 320 °C produces delamination, carbon residue, and degraded sintered density. Residual carbon after burnout should remain below 0.05 % by combustion infrared detection. End products are multilayer ceramic capacitors, oxygen sensors, and low-temperature co-fired ceramic packages.
| Parameter | Boundary value | Observed failure mode |
|---|---|---|
| Plasticizer loading | 20 phr | Edge curl and slitting cracks |
| Plasticizer loading | 55 phr | Blocking on take-up reel |
| Burnout ramp | 1.0 °C/min | Carbon residue and delamination |
| Residual solvent | 1.0 % | Lamination shift and pinholes |
S-LEC BH-A enters laminated safety glass interlayer compounding as the glass-binding polymer in a dry-blend process. The resin is stored in a dehumidified hopper at ≤ 30 °C and ≤ 40 % RH; moisture above 0.3 % by Karl Fischer titration creates steam pinholes at the extrusion die. The resin is gravimetrically fed into a co-rotating twin-screw compounder with an L/D ratio of 40:1 and compounded with triethylene glycol di-2-ethylhexanoate at 28–38 phr. Barrel temperatures ramp from 120 °C at the feed zone to 180 °C at the melt pump, with die temperature kept below 200 °C to suppress volatile formation. The extrudate passes through a melt filter with 60–100 μm screen packs before calendering to 0.38 mm, 0.76 mm, or 1.52 mm sheet thickness. The film is embossed with a surface roughness of 20–40 μm to allow air escape during glass assembly. A glass/PVB/glass stack is pre-pressed at 10–15 °C and 0.6–0.8 bar, then autoclaved at 130–140 °C and 10–12 bar for 60–90 min. Plasticizer retention is checked by ASTM D1203-22 with maximum weight loss of 1.2 % after 24 h at 100 °C. Qualification testing is performed under ISO 12543-2:2021 for haze and optical defects, ECE R43 for automotive glazing, and ANSI Z26.1 for North American vehicle glass. The interlayer should not be conditioned in an amine-rich cleanroom atmosphere because amine species migrate into the PVB surface and reduce adhesion. End products include automotive windshields, architectural laminated glass, and acoustic glazing configurations.
Reverse-printed flexible packaging inks require a binder that balances adhesion to corona-treated PET and resistance to heat during lamination. The S-LEC BH-A masterbatch is prepared at 25–35 % solids in n-propanol/ethyl acetate 70:30 at 45–50 °C with a low-shear propeller mixer; the solution is cooled to 25 °C and filtered through a 10 μm bag filter. The dry-weight ratio of PVB to nitrocellulose is maintained between 1:3 and 1:4 so that the resin contributes adhesion to PET while nitrocellulose supplies release and heat resistance. Pigment dispersion is completed on a horizontal bead mill charged with 0.6–0.8 mm chrome-steel media at a tip speed of 8–12 m/s; the millbase is then let down with the PVB masterbatch and ethyl acetate. Final viscosity is adjusted to 22–28 s on a Zahn cup #2 at 25 °C, corresponding to approximately 40–60 mPa·s by rotational viscometer. Ink freeze-thaw stability is verified over 5 cycles from 0 °C to 25 °C; viscosity drift greater than 10 % indicates pigment flocculation. Printed films are dried through a forced-air tunnel at 50–60 °C to a residual solvent level below 5 mg/m² measured by headspace gas chromatography. Tape adhesion is checked per ASTM D3359-23 method B with a maximum acceptable removal of 5 %; laminated pouch heat resistance is tested at 120 °C for 30 min in a jaw sealer. Regulatory requirements include REACH Annex XVII and heavy-metal limits from Directive 94/62/EC. End products include retort pouches, snack food laminates, and shrink sleeve labels.
The casting of dry film photoresist for printed circuit board imaging uses S-LEC BH-A as the acid-resistant binder matrix for acrylate monomers and photoinitiators. The photopolymer composition is cast from a solvent solution containing 35–50 wt% solids onto 25 μm polyester base film; dry resist thickness is controlled at 15–50 μm. Lamination to cleaned copper-clad laminate is performed at 100–115 °C, 3–5 bar roll pressure, and 0.4–0.6 m/min. UV exposure through a phototool uses a 365 nm source at 50–100 mJ/cm² to crosslink the image areas. Development is carried out in a 1.0 wt% sodium carbonate spray at 28–32 °C; developer temperature above 35 °C causes swelling of unexposed binder and via closure. Copper etching follows with cupric chloride or ferric chloride at 45–55 °C, and resist stripping uses a 3 % sodium hydroxide solution at 40–50 °C. Post-development residue is inspected at 50× magnification; scumming on copper traces indicates incomplete dissolution of the binder phase. Adhesion loss after etching is monitored by the tape test method in IPC-TM-650 2.4.1. The binder’s acid resistance is evaluated by immersion in 20 % hydrochloric acid for 30 min at 25 °C; published data for this specific configuration is limited, so qualification should be repeated on each copper surface finish. End products include double-sided and multilayer printed circuit boards.
Glass-to-metal and glass-to-glass bonding applications draw on S-LEC BH-A as a high-tack binder in heat-curing adhesive films. The resin is dissolved at 20–30 wt% solids in a solvent blend of methyl ethyl ketone and cyclohexanone 80:20; the solution is combined with an epoxy or blocked isocyanate co-resin and cast onto release liner to form film. Laminating conditions for glass-to-aluminium bonds are 150–170 °C for 20–40 min under vacuum bag pressure of 0.8–0.95 bar. Lap shear strength is evaluated per ISO 4587:2003 on 25 mm × 12.5 mm bonded coupons; typical initial values exceed the substrate-tear threshold for photovoltaic glass and anodized aluminium, but published data for this specific configuration is limited, so substrate preparation must be controlled. Thermal shock resistance is checked over 100 cycles from -40 °C to 85 °C with a 30 min dwell at each temperature. The working boundary is the added co-resin: amine-based epoxy hardeners should be avoided because residual amine accelerates acetal ring opening and increases film yellowing above 120 °C. The cured adhesive film is evaluated for water immersion resistance per ISO 9142:2003 using 72 h at 60 °C in deionized water. End products include decorative glass-metal panels, optical mirror mounts, and laminated smart glass connectors.
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S-LEC BH-A is a plasticised polyvinyl butyral interlayer supplied in roll form for laminated safety glass. The product identifier S-LEC BH-A denotes a grade within the Sekisui S-LEC B interlayer family. It is used in architectural glazing, overhead panels, and transport glazing where the interlayer must transfer shear stress across fractured glass and retain residual load-bearing capacity. The resin class consists of polyvinyl alcohol acetalised with butyraldehyde and compounded with plasticiser systems. Product-specific numerical values for the BH-A grade are established in the manufacturer’s current technical data sheet; the data below presents the class-level performance envelope and the processing constraints that control industrial use.
Order configuration for this grade is not defined by the product designation alone. Thickness, roll width, adhesion class, and surface roughness are selected at specification. Commercial roll goods in this interlayer class are typically supplied in calipers from 0.38 mm to 1.52 mm in 0.38 mm increments, with widths up to 2.1 m or 2.6 m subject to manufacturer confirmation. The rolled sheet is sealed in moisture-barrier packaging. Unopened shelf life is commonly stated as 12 months from the production date when stored at 10–25 °C and 30–50 % RH, but the grade-specific packaging film and desiccant loading determine the actual limit.
The specification must include residual polyvinyl alcohol content, butyral content, plasticiser type and content, moisture content, and surface roughness. For commercial PVB interlayers, polyvinyl alcohol content is commonly observed in the 18–22 mol% range, while butyral content is commonly observed in the 76–88 mol% range. Adhesion-controlled grades may deviate outside these ranges. Plasticiser loading is commonly observed at 20–35 parts per hundred resin, but the exact plasticiser system is proprietary. Surface roughness on the deaired pattern is critical because the embossed profile controls air escape during pre-lamination. A roughness amplitude of 20–40 µm is representative of commercial PVB sheet, although grade-specific values must be confirmed.
In a horizontal laminating line, the cut blanks are equilibrated in a controlled layup room before glass stacking. A layup room at 18–24 °C and 20–30 % RH is common for PVB interlayer handling; exposure times at higher humidity produce edge moisture uptake that shifts glass adhesion and changes the autoclave thermal profile. The pre-lamination stage uses vacuum bagging or nipping rolls to remove air from the glass-interlayer-glass stack. Cold deairing is performed at 0.08–0.09 MPa vacuum, followed by heating to 60–90 °C while maintaining vacuum. The subsequent autoclave cycle for standard PVB laminates is typically 1.0–1.5 MPa pressure and 125–140 °C glass temperature for 30–90 min. Process windows near 5 °C deviations at the upper plateau can produce edge bubbles, optical distortion, or adhesion shift; multi-zone autoclave control is therefore required.
The primary functional property of S-LEC BH-A in laminated glass is the transfer of shear stress from glass through the interlayer. In Europe, laminated glass is tested to EN 14449 and ISO 12543; in North America, safety glazing is evaluated to ANSI Z97.1, CPSC 16 CFR 1201, and forced-entry resistance to ASTM F1233. The relationship between adhesion grade and post-fracture load is quantified by compressive shear strength and pummel adhesion values. For standard PVB, pummel values from 3 to 7 on a 0–10 scale are common, but high-adhesion interlayers can be specified to higher ranges. Exact pummel values for S-LEC BH-A are grade-specific and are not inferable from generic PVB data; published data for this specific configuration is limited.
Below a critical plasticiser content or at low moisture, adhesion rises sharply and glass fracture can show adhesive failure at the interface; above the critical moisture content, edge bubbles and premature delamination occur. This property cliff-edge is the reason that laminate processors control layup-room humidity before autoclaving. The interlayer also exhibits viscoelastic response during thermal cycling: stiffness drops as temperature rises above the glass transition region, and shear transfer becomes time-dependent. For architectural glazing, this means that creep under sustained load must be assessed separately from short-term impact performance.
For balustrade and overhead glazing, the structural consequence of using a high-adhesion PVB such as S-LEC BH-A is that glass plies can remain adhered after fracture, but the residual load capacity is a system property of glass type, lite thickness, support hardware, and interlayer thickness. Certification testing on the completed laminate assembly is required because interlayer adhesion alone does not establish post-breakage load resistance.
Compared with standard PVB interlayers used in automotive windshields, S-LEC BH-A is not assumed to have the same adhesion grade solely because it shares the PVB polymer backbone. Standard windshield interlayers are formulated for optical clarity, penetration resistance, and adhesion to curved glass at thicknesses of 0.76 mm. Architectural safety-grade grades such as S-LEC BH-A may be specified in thicker stacks up to 1.52 mm or multiple plies for impact and post-breakage retention. Unlike ionoplast interlayers, PVB interlayers exhibit pronounced plasticiser loss and stiffness reduction above 60 °C; therefore ionoplast may be selected for point-supported glazing where high-temperature creep is unacceptable. Unlike acoustic PVB interlayers, S-LEC BH-A does not necessarily carry a declared acoustic loss factor; if sound control is required, the project must request third-party octave-band transmission loss data.
When the interlayer is used adjacent to laminated-glass edge sealants, silicone structural sealants and neutral-cure silicones are generally used. Amine-containing sealants, high-pH curing agents, and solvent-borne edge seals can cause interfacial haze and local adhesion loss in PVB interlayers. Compatibility must be demonstrated according to ASTM C1087 or an equivalent manufacturer protocol. Edge sealants that release amine or ammonia during cure should be excluded unless compatibility testing confirms no interfacial haze or adhesion shift. This incompatibility is an operational boundary, not a cosmetic concern; it can produce delamination at the laminate edge within months of installation.
Unsealed roll stock exposed to layup-room relative humidity above 60 % requires reconditioning in a conditioned enclosure at 20–25 °C and 20–30 % RH before use; oven drying is not a substitute. Moisture uptake is nonuniform, with the highest gain at the exposed edges. Processing without reconditioning produces a moisture gradient that shifts adhesion locally and can create optical defects after autoclaving. This is particularly relevant on humid production lines where roll stock is opened outside the controlled environment for extended periods.
Optical quality for clear PVB interlayers is controlled by thickness uniformity, surface roughness, and contamination. Visible light transmittance for clear PVB interlayers is commonly 87–90 % when tested to ASTM D1003. Haze is commonly below 1.5 % for clear grades, but colour-tinted and solar-control interlayers have different spectral transmission curves. The optical path through the laminate is also influenced by glass type, coating position, and residual air pockets. A single interlayer defect, such as a particle inclusion or local thickness deviation, can be magnified when the laminate is viewed at an angle.
Moisture content at lamination is usually specified in the 0.35–0.45 wt% range for PVB interlayers. Moisture content is measured by coulometric titration to ASTM D6869 or by an equivalent validated method. High moisture reduces the autoclave processing window and shifts adhesion downward; low moisture raises adhesion beyond the safe pummel range and can reduce impact resistance. Because moisture uptake is temperature-dependent, cold roll stock moved into a warm layup room can condense surface moisture even when the room relative humidity is within specification. Roll stock should be allowed to equilibrate in sealed packaging until the film surface temperature is within 5 °C of the layup room temperature.
| Property | Typical commercial PVB interlayer range | Test method |
|---|---|---|
| Nominal density | 1.07–1.10 g/cm³ | ISO 1183-1 |
| Tensile strength at break | 20–30 MPa | ISO 527-3 |
| Elongation at break | 150–300 % | ISO 527-3 |
| Tear resistance | 25–45 kN/m | ASTM D1004 |
| Moisture content at lamination | 0.35–0.45 wt% | ASTM D6869 |
| Visible light transmittance, clear grade | 87–90 % | ASTM D1003 |
| Haze, clear grade | <1.5 % | ASTM D1003 |
Grade-specific values for S-LEC BH-A may fall outside these class ranges; the table is not a certificate of analysis. The property envelope is useful for feasibility screening only. Final laminate performance must be established by testing the completed glass-interlayer-glass assembly because the interlayer does not behave as an isolated tensile specimen in service.
Production lots are supplied with certificates of analysis recording moisture, thickness profile, haze, and adhesion. Compliance with REACH, RoHS Recast 2011/65/EU, and food-contact provisions under FDA 21 CFR 175.105 or EU 10/2011 requires grade-specific confirmation from the manufacturer. These regulatory claims are not automatically transferable to all applications. The user must verify whether the specific roll stock, including all surface treatments and slip agents, is covered by the regulatory declaration.
On horizontal laminating lines with infrared preheating, the interlayer is drawn through the layup room and the pre-lamination nip at line speeds that depend on glass size and thickness. The limiting parameter is not the glass cutting line but the interlayer’s moisture uptake during layup. A large architectural panel may remain in the layup room for 20–40 min before autoclave loading; during this interval, the exposed edges can gain enough moisture to reduce local adhesion. For this reason, the layup room is often maintained at 20–25 °C and 20–30 % RH, and unsealed roll stock is consumed within the same shift. The pre-lamination stage must remove air before the interlayer’s surface roughness is lost; if the nip roll temperature is too high, the embossed pattern collapses prematurely and trapped air remains. If the temperature is too low, edge sealing is incomplete and the stack may slip during transfer.
The autoclave pressure must be held until the glass surface temperature reaches the specified minimum across the entire load. Large multi-stack loads can show temperature differences of 10–15 °C between the centre and the exterior stacks. Multi-zone autoclave control, load thermocouples, and recipe validation are required to bring all stacks into the processing window. Failure to do so produces variable adhesion within the same batch, which is a known batch-to-batch variance issue on high-capacity architectural laminating lines. This is why production-scale equipment behaviour, not laboratory-scale press data, governs the final processing specification.
For projects requiring documented post-breakage retention, the laminate should be tested to the applicable regional standard: ANSI Z97.1 for safety glazing, CPSC 16 CFR 1201 for architectural and consumer glazing, EN 14449 for laminated glass in European construction products, and ISO 12543 for laminated safety glass classification. Impact testing result interpretation must account for interlayer adhesion, glass type, and laminate thickness. A high-adhesion interlayer can delay glass separation after impact, but it cannot compensate for inadequate glass design or support hardware. The residual load capacity after fracture is time-dependent and temperature-dependent; short-term impact testing alone does not establish long-term creep performance.
When S-LEC BH-A is specified for insulating glass unit inner lites, the edge seal of the insulating glass unit must be compatible with the laminated interlayer edge. Polyisobutylene primary seals and neutral-cure secondary silicones are commonly used. Solvent-borne polysulfide systems and amine-containing curing agents require compatibility testing because fugitive components can migrate to the PVB edge and cause local haze. The insulating glass unit edge seal should not be assumed to protect the laminate from moisture; the laminate edge must be protected by the glazing system or by an appropriate edge cover.
The differentiation between S-LEC BH-A and other S-LEC B grades is established by the manufacturer’s classified test results rather than by inferred generic PVB data. Published performance differentiation for S-LEC BH-A against other S-LEC B grades is limited in open literature and should be validated against the manufacturer’s current technical bulletin. Users who require a specific pummel adhesion range, a declared acoustic loss factor, or a high-temperature creep modulus must request the corresponding grade-specific data. Substituting a standard PVB grade without verifying adhesion and moisture limits can produce laminate failure in service even when the interlayer thickness and glass build remain unchanged.
