| HS Code | 300025 |
| Product Type | Clear Polyvinyl Butyral (PVB) Interlayer |
| Appearance | Transparent colorless film |
| Density | 1.08 g/cm³ |
| Refractive Index | 1.47 |
| Haze Value | < 1% |
| Visible Light Transmittance | ~90% |
| Tensile Strength | 22 MPa |
| Elongation At Break | 250% |
| Youngs Modulus | 12 MPa |
| Glass Transition Temperature | 30°C |
| Adhesion To Glass | Strong; greater than 10 N/25 mm peel strength |
| Uv Light Transmittance | Less than 1% below 380 nm |
As an accredited Saflex Clear factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Saflex Clear interlayer sheets are packaged in resealable, moisture-proof foil bags, with a standard quantity of 100 sheets per package. |
| Container Loading (20′ FCL) | Saflex Clear rolls are safely loaded into a 20′ FCL, edge-protected, ventilated, and shielded from sunlight to prevent damage. |
| Shipping | Saflex Clear is shipped as polyvinyl butyral (PVB) interlayer sheeting on pallets, wrapped in moisture-barrier packaging. It is non-hazardous for transport and requires no UN number. Keep dry, protect from direct sunlight, and handle to avoid distortion. Store between 5–30°C during transit. |
| Storage | Store Saflex Clear in a cool, dry, well-ventilated area away from direct sunlight, heat sources, and moisture. Keep in original sealed packaging until use, protect from physical damage, and maintain temperatures below recommended limits. Avoid exposure to rain or condensation. Follow manufacturer’s guidelines to preserve clarity and performance. |
| Shelf Life | Saflex Clear should be stored cool, dry, and protected from moisture; typical shelf life is one year from manufacture. |
In laminated passenger-car windshield production, Saflex Clear PVB interlayer is positioned between two plies of soda-lime float glass that have been cut, edge-seamed, washed, and dried to remove surface tin-side residues and grinding fines. The interlayer is conditioned at 18–22 °C and 20–25% relative humidity for 24–48 h prior to lay-up because absorbed moisture above supplier specification produces edge clouding and reduces impact adhesion during autoclave bonding. The standard windshield configuration uses a 0.76 mm interlayer between two plies of 2.0–2.3 mm annealed glass, yielding a nominal total laminate thickness of 4.8–5.4 mm; at a PVB density of 1.07 g/cm³, the interlayer mass per unit area is approximately 0.81 kg/m². Production-scale processing begins with a cleanroom lay-up station where interlayer overhang is controlled before edge-trimming after deairing. Deairing is carried out on either a nip-roller line with heated rollers at 60–80 °C surface temperature or in a vacuum-bag system pulling −0.08 MPa to −0.09 MPa before autoclave transfer. The autoclave cycle is ramped to 120–140 °C and 1.0–1.5 MPa, held for 30–90 min depending on load mass, glass thickness, and interlayer stack count, then cooled while pressure is maintained to prevent bubble nucleation. Batch-to-batch optical haze variation is monitored against interlayer moisture, autoclave pressure, and deairing residual pressure; edge bubble formation on multi-batch lines is most frequently traced to humidity shifts above the cleanroom specification during lay-up. Final windshields are validated under ECE R43, ANSI Z26.1, GB 9656-2021, and relevant OEM fragment-retention and optical quality specifications. Terminal finished products include passenger-car windshields, laminated sidelites, and rear lites for series production.
Coastal building envelope components under windborne-debris risk use Saflex Clear PVB in laminated glass that must pass missile-impact and cyclic-pressure differential testing. The governing test regime includes ASTM E1996-17 for missile size definitions and ASTM E1886-19 for impact and post-impact pressure cycling, with acceptance criteria referenced from ICC 500-2020; Florida-specific protocols TAS 201, TAS 202, and TAS 203 are applied in high-velocity hurricane zone product approvals. A frequently used large-missile construction places a 2.28 mm Saflex Clear interlayer between two plies of 6 mm annealed glass, producing a laminated glass with an interlayer-to-glass thickness ratio of approximately 0.19 and a nominal total thickness of 14.28 mm before edge sealants. Processing begins with CNC cutting and edge seaming of annealed float glass to minimize edge microcracks; the glass is washed with demineralized water and inspected for tin-side orientation before PVB lay-up. Interlayer conditioning occurs in a dedicated cleanroom at 18–22 °C and 20–25% RH to prevent moisture-induced adhesion loss. The lay-up stack is deaired using a vacuum-bag system that reaches residual pressure below −0.09 MPa, transferred to an autoclave, and processed at 1.0–1.5 MPa and 120–140 °C for 45–120 min; longer cycles compensate for thicker interlayer stacks and the low thermal conductivity of PVB. After autoclaving, the laminate undergoes visual inspection for edge voids, delamination, and optical distortion, then is mounted in tested aluminum or steel fenestration frames with structural setting blocks and glazing gaskets capable of transferring cyclic loads without allowing glass-to-metal contact. Terminal finished products include hurricane-rated sliding glass doors, curtain wall panels, and storefront fenestration for coastal commercial and residential buildings.
Because the coincidence dip of monolithic glazing lies in the 1.0–4.0 kHz range where speech intelligibility is concentrated, laminated glass incorporating Saflex Clear PVB can alter the mass-spring-mass response of a double glazing system and improve the weighted sound reduction index. The test methodology is ISO 10140-2:2021 for laboratory measurement of airborne sound insulation, classified by ISO 717-1:2020; North American project specifications often cite ASTM E90-09 and ASTM E413-16 for transmission loss and STC ratings. In a typical façade application, replacing a monolithic 6 mm outer lite with a laminate consisting of 3 mm glass / 0.76 mm Saflex Clear PVB / 3 mm glass can raise the STC by 1–2 dB and damp the coincidence dip, but the change is modest compared with a specialized acoustic interlayer; published data for Saflex Clear-specific configurations is limited, and extrapolation from general PVB acoustical literature should be validated with full-scale samples. The production process follows standard laminated glass procedures: glass cutting, edge seaming, washing, PVB conditioning, lay-up, vacuum deairing, and autoclave bonding at 120–140 °C and 1.0–1.5 MPa. Because acoustic performance is strongly dependent on interlayer thickness, glass thickness asymmetry, and air cavity width, production-control records should include as-built glass thickness, interlayer thickness, and autoclave pressure for each batch. Terminal finished products include acoustic laminated glass panes for hotel, office, and residential façades, as well as interior partitions where speech privacy requirements are specified.
In forced-entry glazing configurations, Saflex Clear PVB functions as the energy-absorbing and fragment-retaining interlayer in laminated glass assemblies designed to delay manual attack. The relevant product classifications are EN 356:2000 for burglary-resistant glazing, UL 972:2006 for burglary-resisting glazing material, and ASTM F1233-08 for security glazing materials; end-use specifications often require a minimum classification of P6B or equivalent. A foundational construction uses two plies of 3 mm annealed glass and one 1.52 mm Saflex Clear interlayer; higher resistance configurations stack multiple glass/PVB sequences, for example, 4 mm glass / 1.52 mm PVB / 4 mm glass / 1.52 mm PVB / 4 mm glass, with total interlayer thickness 3.04 mm and total laminate thickness of 15.04 mm. Manufacturing of multi-layer stacks demands longer autoclave soak times because the central interlayer reaches setpoint temperature more slowly than the outer plies; typical cycles operate at 1.0–1.5 MPa and 120–140 °C, with cycle time extended to 60–180 min based on stack mass and glass emissivity. Prior to lay-up, glass plies are washed, inspected for edge defects, and conditioned with the PVB at 18–22 °C and 20–25% RH to avoid edge bubbles that weaken forced-entry performance near the glazing bite. The finished laminate is installed in structurally anchored frames with sufficient edge engagement to prevent interlayer tearing at the perimeter under sustained prying loads. Terminal finished products include security doors, glazed storefront barriers, and interior partition glazing in commercial and institutional buildings.
The retained-fragment requirement for overhead glazing and structural balustrades derives from post-breakage load capacity rather than initial impact resistance alone. Saflex Clear PVB is used in laminated glass to bond fractured glass particles to the interlayer after upper-plate breakage, reducing the risk of falling fragments. Compliance is assessed using EN 12600:2002 for pendulum-impact classification and fall-off behavior, EN 14449:2005 for laminated safety glass in overhead-glazing and balustrade applications, and DIN 18008-1 for design of glazing supports; ASTM project specifications may reference ASTM C1172-19 for laminated architectural flat glass. A typical point-fixed overhead installation uses two plies of 8 mm heat-strengthened glass laminated with a 1.52 mm Saflex Clear interlayer, yielding a nominal laminate thickness of 17.52 mm; where walk-on glass floors are specified, thicker build-ups such as 10 mm glass / 1.52 mm PVB / 10 mm glass / 1.52 mm PVB / 10 mm glass are used. Glass plies are heat-strengthened and heat-soak-treated to reduce nickel sulfide inclusion risk before lamination. The cleanroom lay-up, vacuum deairing, and autoclave cycle use the same 120–140 °C, 1.0–1.5 MPa window, but post-breakage adhesion is verified through visual inspection of interlayer adhesion near point-fixing holes and edge notches. Terminal finished products include skylights, sloped glazing canopies, frameless glass balustrades, and walk-on glass floors in commercial buildings.
Ballistic-resistant glazing fabricated with Saflex Clear PVB relies on sequential glass and interlayer lamination rather than a single chemical treatment of the glass surface. The interlayer functions as a fragment-retention and spall-control element within a multi-layer composite; it is not a standalone bullet-resistant material. Compliance testing is conducted under UL 752, EN 1063:1999, or NIJ 0108.01 depending on jurisdiction and threat level. Typical low-threat configurations combine multiple glass plies of 6–10 mm with Saflex Clear PVB interlayers of 1.52 mm or 2.28 mm and often include a polycarbonate backing layer; total composite thickness may range from 25 mm to more than 50 mm as threat level increases. Manufacturing requires especially long autoclave dwell periods because the central glass and PVB layers are insulated by surrounding plies; each additional glass plate and interlayer adds thermal resistance that slows the heating rate. Autoclave pressure is maintained at 1.0–1.5 MPa and temperature at 120–140 °C, but total cycle time may extend to several hours, and load size must be reduced to avoid internal temperature gradients that create optical distortion. After lamination, panels are inspected for haze, edge voids, and adhesive bonding at glass/PVB interfaces; ballistic testing is destructive and performed on representative sampling. Terminal finished products include bullet-resistant bank teller barriers, government building glazing, and security windows in high-risk commercial properties.
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Saflex Clear is a plasticized polyvinyl butyral (PVB) interlayer supplied as an extruded roll for lamination between glass plies. The commercial designation covers a clear, colorless sheet formulated without acoustic damping cores, solar-absorbing additives, or ionoplast chemistry. Standard single-ply calipers are 0.38 mm, 0.76 mm, and 1.52 mm; thicker interlayers are assembled from multiple plies that fuse during autoclaving. Roll widths typically include 1.83 m and 2.44 m, but exact slitting and roll length should be confirmed against current manufacturer scheduling. The product acts as a thermoplastic adhesive that bonds to glass under heat and pressure and retains fractured glass in the event of breakage. Laminated safety glass prepared with Saflex Clear is evaluated under EN ISO 12543-2, ANSI Z97.1, and ASTM C1172 for architectural use, and under ECE R43 for automotive glazing where applicable. As a PVB material, it is hygroscopic and requires controlled storage, conditioning, and autoclave processing; the processing limits are not interchangeable with those of ionoplast interlayers.
Clear PVB sheet is specified by optical clarity, color, and haze. For a laminate fabricated with two 2.1 mm clear glass plies, visible light transmittance can exceed 88% when measured according to ISO 9050; the exact value depends on glass iron content. The clear interlayer itself does not introduce significant tint. Representative clear PVB sheet values measured by standard methods are listed in the following table; these values are drawn from general clear PVB literature and should not replace lot-specific certificates. Ultraviolet absorption is another defining property: PVB sheet with UV stabilizer blocks most ultraviolet radiation below approximately 380 nm, with UV transmittance below 1% in the 300-380 nm band. This behavior is relevant for protection of interior materials, but it does not imply UV stability of exposed interlayer edges.
| Property | Test method | Representative clear PVB range |
|---|---|---|
| Density | ISO 1183-1 | 1.07 g/cm³ |
| Refractive index | ISO 489 | 1.48 |
| Haze, 0.76 mm sheet in clear laminate | ASTM D1003 | ≤1.0% |
| Yellowness index | ASTM E313 | ≤1.0 |
| Tensile strength at break | ASTM D638, 50 mm/min | 20-25 MPa |
| Elongation at break | ASTM D638 | >200% |
Mechanical behavior of PVB is strongly viscoelastic. The tensile response measured at 50 mm/min provides only a single point on a rate-temperature spectrum. At loading rates relevant to glass impact, the effective modulus rises; under sustained static loads, creep and stress relaxation dominate. Small-strain tensile modulus at room temperature is frequently reported below 10 MPa for low-frequency testing, whereas high-rate or low-temperature conditions produce higher stiffness. This rate dependence means that structural design calculations must not use single-point tensile data without shear transfer models such as EN 16612 or ASTM E1300. Published data for Saflex Clear across the full viscoelastic master curve is available from the manufacturer for some grades; for other specific configurations, published data is limited.
PVB sheet is extruded on production-scale plasticized polymer lines, typically on twin-screw systems with L/D ratios of 30:1 to 40:1 and chilled-roll calibration. Incoming roll condition affects lamination more than many variables: the sheet must be stored below 20 °C and at 20-35% RH in moisture-barrier packaging. Cold rolls should be acclimated before opening to avoid surface condensation. Pre-lamination conditioning is carried out to bring the sheet to an equilibrium moisture content of 0.4-0.5% by weight. At 0.2% moisture, adhesion to glass can drop below acceptable values, producing large unbonded zones and poor pummel values. Above 0.6%, excessive moisture can generate bubbles during hot de-airing and can reduce edge quality in the autoclave.
De-airing is accomplished by vacuum bag, vacuum ring, or nip-roller methods. With vacuum bag systems, cold evacuation below 0.08 MPa residual pressure for 20-40 min is followed by heating under vacuum to 80-110 °C for 20-45 min. The hot de-airing step seals the glass edges with tacked PVB. Autoclave cycles for clear PVB laminates typically operate at 1.2-1.4 MPa and 130-140 °C. The load must be held for 60-120 min after the coldest point reaches target temperature; thermocouples placed in the thickest glass corner provide better control than autoclave vessel setpoint alone. Cooling under pressure to below 45 °C before venting prevents bubble formation from dissolved air and water. Field failure modes observed on production lines include edge bubbles from incomplete de-airing, central haze from excessive moisture, glass breakage from uneven cooling, and adhesive delamination from contaminated glass surfaces. Each of these is controlled more effectively by pre-lamination moisture audits and thermocouple data than by extending autoclave time alone.
Batch-to-batch variation in clear PVB interlayers typically arises from plasticizer content, sheet thickness profile, and residual surface texture. Incoming inspection should record roll caliper at the center and edges using a calibrated thickness gauge; a sheet intended for a 0.76 mm layer should be checked for deviations exceeding ±0.05 mm across the roll. Plasticizer-related viscosity shifts can be detected by melt flow rate or by controlled-temperature tensile response; direct lot-to-lot comparison is advisable before a new roll enters production. Moisture content is measured by Karl Fischer titration or by a calibrated moisture analyzer on a sample taken from the roll after conditioning. Production lots are often qualified using a pummel test on a standard clear float substrate after a fixed autoclave cycle. A pummel value of 3-7 on the 10-point scale is commonly targeted for architectural and automotive constructions, but pummel is operator- and substrate-dependent; it is best used as an internal SPC tool rather than a release criterion.
The glass surface also determines batch consistency. Float glass with residual cutting fluids, silicone release agents, or label adhesives can produce local delamination even when PVB moisture is correctly managed. Wash lines should operate with deionized water at 30-50 °C and forced air dryers; glass surface temperature should not drop below 10 °C before layup. Published data for Saflex Clear in combination with all commercial coatings and frits is limited; low-emissivity coatings, ceramic enamel frits, and silicone edge seals require pre-qualification on the specific stack. Because the interlayer is not a primer-based adhesion system, unlike some ionoplast products, the cleaning and moisture-control steps are the primary adhesion levers.
Along exposed cut edges in exterior glazing, the PVB edge is the primary moisture-diffusion path. Unlike the laminated face, the cut edge permits direct water vapour uptake into the plasticized matrix. Continuous wetting of unsealed edges can create delamination fronts and visible white edge clouding that advance at rates influenced by temperature, adhesion level, and edge geometry. In balustrades, spandrel panels, and glass floors, Saflex Clear laminates should therefore be detailed with edge cover profiles, compatible sealants, and drainage paths that avoid standing water. Alkaline or amine-containing sealants can increase local pH and accelerate interlayer degradation at the edge; polyurethane and neutral-cure silicone systems are typically screened using the sealant manufacturer's PVB compatibility documentation. Pre-drying cut edges at 60-80 °C for 20-30 min before sealing lowers interfacial moisture, but if the interlayer contains more than 0.6% moisture at the edge, the drying step alone may not restore full adhesion. The use of PVB laminates in continuously immersed or highly humid pressure-glazed systems is excluded unless the specific build has been tested for the application.
When a specification is migrated from an acoustic PVB interlayer to Saflex Clear without recalculating the façade acoustic performance, the sound transmission loss can change most in the coincidence-dip region because the standard clear PVB lacks the multilayer damping core used in acoustic grades. Sound reduction measurements should be repeated on the actual laminated build according to ISO 10140-2 or ASTM E90. Similarly, replacing an ionoplast interlayer with Saflex Clear in a point-supported overhead panel reduces post-breakage stiffness and increases deflection under sustained load; structural calculations must account for the lower shear modulus and greater creep of plasticized PVB. Ionoplast materials are often specified for glass fins, structural balustrades, and hurricane-resistant façades because their small-strain tensile modulus is reported in the 100-300 MPa range, whereas clear PVB is far more rate-dependent and lower in modulus at architectural service temperatures.
| Design property | Saflex Clear PVB | Acoustic PVB layer | Ionoplast interlayer |
|---|---|---|---|
| Base polymer class | Plasticized PVB | Plasticized PVB with damping core | Ionomer copolymer |
| Typical density | 1.07 g/cm³ | 1.07 g/cm³ | 0.95-0.96 g/cm³ |
| Small-strain modulus at room temperature | <10 MPa at low frequency; rate-dependent | Similar bulk modulus; higher damping | 100-300 MPa |
| Primary post-breakage behavior | Glass retention with lower residual stiffness | Glass retention with improved vibration damping | Higher post-breakage stiffness and creep resistance |
| Typical use when replacing clear PVB | Baseline architectural and automotive glazing | Acoustic glazing, façades with traffic noise | Overhead glass, fins, balustrades, high load panels |
Saflex Clear also differs from solar-control interlayers that contain IR-absorbing particles or spectrally selective dyes. In high solar-load façades, substituting clear PVB for a solar-control interlayer raises the g-value and may increase thermal stress in partially shaded glass. Mechanical and optical comparisons are meaningless without a fixed glass build, because the laminated composite response depends on glass thickness, glass type, interlayer thickness, and edge boundary conditions. Published data for Saflex Clear in every possible glass configuration is limited; therefore comparative testing on the actual stack is required for acoustics, structural creep, and solar performance.
In automotive windshield production, Saflex Clear sheet is positioned between two bent glass plies and processed by vacuum ring or nip-roll de-airing before autoclaving. The cut sheet is oversized and trimmed after lamination. Automotive laminates must satisfy ECE R43 fragmentation and optical requirements; the interlayer supplies glass retention after impact but is not a substitute for windshield geometry or glass heat strengthening. The processing window is narrower for curved glazing because the de-airing step must accommodate the bent glass profile; folds and trapped air are common failure modes when the sheet temperature is too low or the vacuum ring seal is worn. Periodic replacement of vacuum seals and verification of autoclave load thermocouples are field-level controls that reduce these defects.
