| HS Code | 265991 |
| Appearance | Spherical or cylindrical granules |
| Form | Free-flowing pellets |
| Color | White to light yellow |
| Specific Gravity | 1.08 - 1.12 g/cm³ |
| Melt Flow Rate | 2 - 10 g/10 min (at 150°C, 2.16 kg) |
| Tensile Strength | 40 - 60 MPa |
| Elongation At Break | 50 - 150% |
| Glass Transition Temperature | 65 - 80°C |
| Processing Temperature Range | 150 - 220°C |
| Water Absorption | 0.3 - 0.6% (24 h immersion) |
| Refractive Index | 1.480 - 1.490 |
As an accredited Granulated PVB Resin for Extrusion,Injection Molding & Melt Spinning factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Supplied in 25 kg sealed moisture-proof bags, ensuring clean, dry granulated PVB resin for extrusion, injection molding, and melt spinning. |
| Container Loading (20′ FCL) | Granulated PVB resin loaded in 20′ FCL, packed in bags on pallets, secured and ventilated for safe transport. |
| Shipping | Granulated PVB resin is shipped in moisture-resistant sealed bags or drums to prevent water absorption. Store in a cool, dry place, avoiding heat and direct sunlight. Transport in clean, dry containers with proper ventilation. Ensure secure stacking to prevent damage. Not classified as hazardous, but handle with care. |
| Storage | Store granulated PVB resin in a cool, dry, well-ventilated area away from direct sunlight and heat sources. Keep the original container tightly sealed to prevent moisture absorption and contamination. Ideal temperature: below 25°C (77°F). Protect from humidity and drastic temperature fluctuations. Under proper conditions, shelf life is 12 months from manufacture date. |
| Shelf Life | Shelf life is typically 12 months when stored in a cool, dry, sealed container away from moisture and direct sunlight. |
Laminated safety glass interlayer sheet extrusion begins with dry blending of granulated PVB resin, not solvent casting. Residual vinyl alcohol hydroxyl content between 18 wt% and 23 wt% controls plasticizer uptake, glass adhesion and moisture sensitivity. Triethylene glycol bis(2-ethylhexanoate) is metered at 26 phr to 33 phr; dipropylene glycol dibenzoate may replace a minor fraction at 5 wt% to 10 wt% of the plasticizer phase when lower migration or adjusted refractive index is required. The dry blend is compounded in a co-rotating twin-screw extruder with L/D 40:1 using loss-in-weight feeders and liquid injection after melt sealing. Pre-drying at 55 °C to 65 °C in dehumidified air with −40 °C dew point for 4 h to 6 h reduces residual moisture to ≤0.08 % by Karl Fischer titration. Melt temperature at the die is held between 175 °C and 205 °C. Screen packs of 20 mesh to 40 mesh remove unmelted acetal-rich agglomerates. The melt is cast through a flexible-lip flat die with a lip gap of 0.5 mm to 1.4 mm onto polished chromium-plated cooling drums maintained at 28 °C to 45 °C. Target sheet thickness is typically 0.38 mm for automotive windshield interlayer and 0.76 mm for architectural laminated glass.
On production-scale lines, edge melt fracture appears when draw ratio exceeds 3:1, particularly when edge trimming is insufficient or die lip polymer temperature drops below 165 °C. Moisture excursions above 0.10 % create microvoids that lower visible light transmittance and increase haze. Thermal degradation above 210 °C releases butyraldehyde and produces yellow specks; residence time in stagnant zones must remain below 5 min. Co-extruded multilayer structures with polycarbonate or ionomer skins are used where improved hardness, chemical resistance or sound damping is required. Optical quality of the single interlayer sheet is tested per ASTM D1003-21; haze is commonly controlled below 1.0 % for high-transparency windshield grades. Laminated impact performance is assessed per ISO 12543-2:2021 or regional equivalents such as ECE R43. Tensile elongation at break of plasticized interlayer sheet is generally above 200 % when measured per ASTM D638-22. The end product is applied as the acoustic and adhesion layer inside automotive windshields, architectural safety glazing, and hurricane-resistant laminated glass assemblies.
| Application context | Standard / test method | Measured parameter | Control point |
|---|---|---|---|
| Safety glazing interlayer sheet | ISO 12543-2:2021 | Laminated safety glass visual and optical quality | No delamination, bubble formation, or optical distortion after lamination |
| Safety glazing interlayer sheet | ASTM D1003-21 | Haze and luminous transmittance | Haze ≤1.0 % for single interlayer sheet |
| Solvent-removable filament | ISO 527-2:2012 | Tensile properties of extruded filament | Diameter 1.75 mm ± 0.05 mm; tensile elongation verified after conditioning |
| Injection-moulded PVB specimens | ISO 294-1:2017 | Specimen preparation for thermoplastics | Mould temperature 25 °C to 45 °C |
| Ceramic injection moulding feedstock | ISO 178:2019 | Flexural strength of green and debound parts | Green flexural strength measured before thermal debinding |
In fused filament support applications, PVB granulate is extruded into round filament of 1.75 mm or 2.85 mm for sacrificial support structures on multi-material additive manufacturing systems. The defining property is solubility in isopropanol or 70:30 isopropanol/water at 25 °C to 35 °C without mechanical scrubbing. Pre-drying is carried out at 55 °C to 65 °C to 0.08 % moisture; higher moisture causes steam blistering, diameter oscillation, and intermittent surfacing after the water bath. In single-screw extrusion lines with L/D 24:1 to 28:1 and a melt pump, barrel zones are set from 165 °C at the feed throat to 195 °C at the adapter. Die head temperature should not exceed 205 °C; excursions above 215 °C initiate carbonyl-linked gel formation that reduces cold isopropanol dissolution and increases die swell variability.
A common production failure occurs when pellet fines accumulate in the hopper throat, causing feed starvation and diameter drift; hopper throat cooling below 45 °C prevents premature plastication. Quench water temperature is maintained between 30 °C and 40 °C, and a closed-loop laser diameter gauge corrects haul-off speed within ±0.05 mm of target. Because PVB is amorphous, the strand does not develop spherulitic scattering, and visible transparency is retained after quenching. Tensile properties are verified on conditioned filament per ISO 527-2:2012. Support structures made from this filament are removed from transparent polycarbonate or PETG components in an ultrasonic isopropanol bath, typically within 10 min to 20 min. The upper melt temperature boundary is therefore not defined by crystallinity or screw torque alone, but by the retention of solvent-removable physical integrity after extrusion.
Ceramic injection moulding feedstocks formulated with PVB binders use the resin as a polar backbone polymer, not as a neat thermoplastic. PVB hydroxyl and acetal groups adsorb onto alumina, zirconia and silicon nitride surfaces, providing green strength after injection moulding. The organic phase typically contains PVB, paraffin wax or low-density polyethylene wax, stearic acid as dispersant, and a low-volatility plasticizer such as dibutyl phthalate or triethylene glycol bis(2-ethylhexanoate). When compounded at ceramic powder loadings of 58 vol% to 64 vol%, the feedstock is processed in a co-rotating twin-screw extruder with L/D 40:1 and gravimetric feeders. Barrel temperatures remain between 120 °C and 150 °C in the early zones and 160 °C to 180 °C at the die to avoid PVB chain scission. Solvent debinding in acetone or ethanol at 30 °C to 50 °C removes wax phases; subsequent thermal debinding ramp at 0.5 °C/min to 1.0 °C/min to 500 °C oxidizes residual PVB. Green flexural strength is measured on injection-moulded bars per ISO 178:2019.
End products include ceramic injection moulded thread guides, micro-gears and pump components requiring complex geometries that cannot be formed by dry pressing. A recognized boundary condition is that oxygen-sensitive powders such as titanium carbide require binder adjustment because thermal decomposition of PVB in air may be less complete below 500 °C. Published data for specific PVB-bound ceramic injection moulding formulations is limited, so binder removal profiles must be established by thermogravimetric analysis for each powder-binder combination. The conversion route demonstrates that PVB granulate can be consumed in downstream ceramic manufacturing without the property profile required of a final thermoplastic part.
When PVB is injection-moulded as a clear damping component, the granulate is first dried at 60 °C to 65 °C in dehumidified air to a moisture level below 0.08 %. PVB is shear-sensitive; screw speed is limited to 60 rpm to 120 rpm on a three-zone machine of 25 mm to 40 mm screw diameter with an L/D ratio of 20:1 to 24:1. Barrel temperature profiles run from 165 °C at the feed throat to 195 °C at the nozzle; actual melt temperature should not exceed 205 °C. The amorphous structure does not show a crystallization exotherm, but stagnation above 190 °C for more than 5 min causes yellowing and butyraldehyde odour. Clamp force requirements are modest because PVB melt at low shear has high viscosity; injection pressure at the screw tip for 2 mm plaques is typically set between 900 bar and 1,200 bar.
Mould temperature is held between 25 °C and 45 °C; lower temperatures increase ejection friction because PVB adheres strongly to polished steel. Forced ejection from untextured cores can scratch optical surfaces. Hot runner systems should use direct gates or open designs without dead spots; hot runner temperature is also kept below 205 °C. Solvent welding of molded PVB is performed with isopropanol, ethanol or methyl ethyl ketone at room temperature, enabling sealed housings and transparent acoustic dampers without additional adhesives. Tensile properties of injection-moulded specimens are measured per ISO 527-2:2012, Izod impact per ASTM D256-23e1, and Vicat softening per ISO 306. The absence of crystallinity reduces through-thickness anisotropy, but shrinkage remains sensitive to wall thickness; published data for specific PVB injection-moulding grades is limited compared with glass-interlayer sheet.
Quench air temperature and draw ratio boundaries in melt-spun PVB monofilament are shaped by the resin’s amorphous, plasticizable character. Melt spinning is performed on a single-screw extruder with a melt pump and spinneret hole diameter of 0.3 mm to 0.8 mm. Barrel temperatures rise from 160 °C at the feed section to 190 °C at the spinneret; melt temperature is held below 195 °C to preserve solubility and avoid gel formation. After exiting the spinneret, the clear monofilament passes through transverse quench air at 10 °C to 20 °C over a fixed quench distance of 50 mm to 150 mm. Draw ratios are limited to 2:1 to 3:1; higher orientation creates fibrillation and poor re-solubility because aligned PVB chains pack densely. The absence of crystallization is confirmed by differential scanning calorimetry through a broad glass transition rather than a melting endotherm.
Published data for commercial melt-spun PVB fiber mechanical properties is limited. When fibers are targeted as temporary binder filaments for nonwoven preforms, dissolution in ethanol at 40 °C to 50 °C is specified rather than mechanical separation. Quench variability, spool tension variations, and residual moisture above 0.08 % introduce whipping and cross-sectional flatting in the monofilament. The practical processing window is therefore narrow: melt temperature, quench air temperature and draw ratio must be controlled simultaneously to retain both dimensional uniformity and solvent-removable behavior after spinning.
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Granulated polyvinyl butyral (PVB) resin produced for extrusion, injection molding, and melt spinning is supplied as free-flowing irregular granules with a bulk density typically in the range 0.45–0.65 g/cm³ and a particle-size distribution controlled to reduce hopper bridging in discrete gravimetric feeders. The polymer consists of vinyl butyral, residual vinyl alcohol, and residual vinyl acetate repeat units; the residual hydroxyl content is the primary specification variable because it influences melt viscosity, plasticizer absorption, adhesion to glass, and moisture uptake. Commercial model suffixes are generally assigned by solution viscosity; for example, low-viscosity grades fall in the 8–14 mPa·s range, medium-viscosity grades between 14–20 mPa·s, and high-viscosity grades above 20 mPa·s when measured as a 10 wt% solution in ethanol at 20 °C according to ISO 3105 or DIN 53015. Certification documents usually report residual hydroxyl content, residual acetate content, moisture by Karl Fischer titration, and melt volume-flow rate according to ISO 1133-1:2022. The granulated form differs from PVB powder, flake, and cast film in particle morphology, bulk density, and dust burden; it differs from pre-plasticized PVB compound in formulation flexibility.
Granulation affects feed behavior and thermal history more strongly than pellet geometry suggests. Granular bulk density is lower than that of dense PVC or PET pellets, which commonly exceed 0.75 g/cm³; this increases volumetric feeder displacement per unit mass but reduces dust and improves flow from conical hoppers. The practical particle-size target keeps fines below 5 wt% to limit shear heating and dust generation during conveying. Compared with PVB powder, granulate reduces airborne dust during unloading and can be pneumatically conveyed over longer distances with less risk of filter blinding. Compared with PVB film scrap, granulate has a defined bulk density and a much lower surface-area-to-volume ratio, so it absorbs moisture more slowly during open hopper storage.
In twin-screw compounding, the granulated form lowers the angle of internal friction relative to flake or powder, which permits a gravimetric feeder to hold mass-flow uniformity within ±0.5% of setpoint on co-rotating twin-screw extruders of 25 mm–40 mm screw diameter and L/D 40:1. The granules require pre-drying to a moisture content below 0.1 wt% because water hydrolyzes the acetal linkages and produces bubbles at the die. Moisture is confirmed at the hopper inlet by Karl Fischer titration per ISO 15512:2019 rather than by loss-on-drying alone. Extrusion grades are usually mixed with 5–20 phr of an ester plasticizer such as triethylene glycol di-2-ethylhexanoate or dibutyl sebacate; the granules absorb the plasticizer more uniformly than powder but require 4–8 h at 60–70 °C to reach steady-state flexural modulus. Barrel temperature profiling from feed throat to die is ordinarily set from 140 °C to 170 °C, with a melt-temperature ceiling of 190 °C for plasticized formulations. Above 200 °C, butyraldehyde evolution becomes detectable and melt yellowness increases. A vacuum vent maintained at -0.08 MPa to -0.095 MPa downstream of plastication removes residual water and low-molecular-weight volatiles. Die pressure measured by a melt-pressure transducer ahead of the breaker plate typically stabilizes at 10–18 MPa for a 3 mm die gap at 15–30 kg/h on a 30 mm twin-screw line. Published comparative feeding trials under identical screw profiles indicate that granulated feed can reduce feed-rate standard deviation by 35–50% relative to powder, depending on particle-size distribution and hopper geometry.
A single-screw extrusion line for PVB sheet or profile generally uses a screw with 24:1 to 30:1 L/D and compression ratio of 2.5:1 to 3.5:1. Starve feeding the granulate maintains screw torque below 70% of motor capacity on 45 mm extruders and reduces thermal history. Melt temperature is controlled at 150–180 °C for formulations containing 10–20 phr plasticizer; the die-lip temperature is held within 3 °C of the melt temperature to avoid surface haze. PVB has higher melt strength than linear low-density polyethylene and permits draw ratios of 2:1 to 5:1 without web sag, but its thermal stability plateau is shorter than that of polycarbonate or polysulfone. Residence time in the barrel should be kept below 20 min at melt temperature, and start-up purging using a low-melt-flow PVB or acrylic purging compound is typical. Unlike rigid PVC, granulated PVB does not need organotin or metal-soap stabilizers for short-dwell extrusion because degradation proceeds through acetal ring opening and butyraldehyde release rather than dehydrochlorination. This does not imply unlimited stability: prolonged exposure above 190 °C raises yellowness index and reduces impact toughness.
| Grade class | Solution viscosity (mPa·s) | Residual hydroxyl content (wt%) | Typical melt-processing route | Distinguishing behavior |
|---|---|---|---|---|
| Low-viscosity | 8–14 | 11–14 | Melt spinning, thin-wall injection molding | Lower melt viscosity; faster plasticizer uptake; lower melt strength |
| Medium-viscosity | 14–20 | 14–18 | Sheet/profile extrusion, medium-wall injection molding | Balanced melt strength, adhesion, and moisture tolerance |
| High-viscosity | 20–28 | 18–21 | Thick sheet, coextruded protective layers | Higher tensile strength; lower melt volume-flow rate; higher die pressure |
The grade distinctions require adjustment of barrel temperature, plasticizer loading, and tooling pressure drop because solution viscosity measured in ethanol is a relative indicator and does not directly predict melt-flow behavior under shear. The hydroxyl content specification for injection and melt-spinning grades is set below 14 wt% to reduce moisture regain and melt viscosity, while high-adhesion sheet grades tolerate hydroxyl content up to 21 wt%. A shift of 2 wt% in residual hydroxyl content can alter melt viscosity enough to require a 5–10 °C change in melt temperature at the same injection speed. Hydroxyl groups also increase moisture equilibrium at 50% RH, extending drying time for high-hydroxyl grades.
Granulated PVB for injection molding is processed on screws with 18:1 to 22:1 L/D and compression ratio 2.0:1 to 2.5:1. Barrel temperatures are profiled from 160 °C in the rear zone to 190 °C at the nozzle, and mold temperature is maintained between 20 °C and 50 °C because the polymer is amorphous and does not require cooling to suppress spherulitic crystallization. Linear mold shrinkage measured on 60 mm × 60 mm × 2 mm plaques under ISO 294-4 is reported at 0.8%–1.6% for unmodified PVB and 0.5%–1.2% for plasticized formulations. Gate freeze-off time is shorter than that of polycarbonate at equal wall thickness because the PVB melt crosses a broad glass-transition range rather than a sharp solidification point. Screw-tip injection pressure is held between 80 MPa and 140 MPa for thin-wall parts, corresponding to clamping requirements of 3–5 kN/cm² of projected area. Jetting occurs when melt passes through a narrow gate at high shear rate; a gate diameter of at least 0.8 mm and melt temperature above 170 °C reduce the defect. Back pressure is limited to 0.5–1.0 MPa because higher back pressure increases melt temperature and shortens stable residence time. Pre-drying to below 0.1 wt% moisture is mandatory; moisture sensitivity is lower than that of polyamide 66 but higher than that of polypropylene. Compared with amorphous ABS, granulated PVB typically shows higher visible-light transmission and lower tensile modulus. Compared with polymethyl methacrylate, it has lower surface hardness and higher elongation. The material is therefore placed in applications where optical transmission, adhesion, and impact resistance are required, not where load-bearing rigidity is the principal criterion.
Melt spinning of granulated PVB remains a smaller-volume processing route than PET or polyamide 6, and published data for this specific configuration is limited. The available technical reports describe low-viscosity grades with residual hydroxyl content below 14 wt% and plasticizer content below 8 phr passing through a single-hole or 24-hole spinneret at melt temperatures of 150 °C to 180 °C. The extrusion system is commonly a 20 mm or 25 mm single-screw unit with L/D 24:1, equipped with a melt pump and 40–60 μm last-chance filtration. Spinneret entrance angle is 30°–60°, and capillary L/D is 2:1–4:1. Quench air at 15–25 °C and cross-flow velocity of 0.5–1.5 m/s is applied below the spinneret to prevent filament fusion. As-spun PVB monofilament is amorphous and transparent, with elongation at break above 200% after drawing at 1:3 to 1:6; tensile strength is commonly reported below 100 MPa, which is lower than drawn PET or polyamide monofilament. The main process limitation is melt viscosity instability: acetal ring opening above 190 °C increases melt volume-flow rate and can produce filament breaks at the spinneret. PVB melt-spun fiber is specified only where adhesion, dyeability, and low-temperature flexibility are more important than tenacity; PET or PA6 is selected when tensile strength above 400 MPa is required.
Post-industrial PVB film scrap cannot be handled as a direct replacement for granulated extrusion resin because film scrap has bulk density below 0.15 g/cm³ and tends to wrap the screw at the feed opening. Co-feeding 20–40 wt% film regrind with granulated primary resin stabilizes the overall bed porosity and reduces feed-phase torque instability on 30 mm co-rotating twin-screw extruders processing sheet with 10–15 phr plasticizer. Higher regrind ratios require forced crammer feeding and are associated with melt-pressure oscillation bands of ±0.8–1.5 MPa. PVB film absorbs moisture in surface folds; the regrind is dried at 70 °C for 6 h, while the granulated resin reaches the same moisture specification after 4 h under identical conditions. The difference is not chemical but morphological: bulk density, specific surface area, and particle aspect ratio govern feed intake and heat-transfer uniformity in the dryer. These observations explain why granulated primary PVB is preferred for precision metering, whereas film scrap is reserved for lower-demand recycled content streams.
For thermoplastic processors, the relevant differences from other products extend beyond chemistry. PVB granules are amorphous, have lower processing temperatures than polycarbonate, and form transparent articles without nucleating agents. In comparison with PVC granules, PVB does not emit hydrogen chloride during off-gassing but emits butyraldehyde and small amounts of acetic acid; this changes the required corrosion protection and ventilation. In comparison with PET, PVB does not require crystallizer or dryer temperatures above 150 °C; instead it requires gentle drying below 75 °C because the granules can block at higher temperatures. In comparison with polymethyl methacrylate, PVB melt is more shear-sensitive and shows greater elongation at break after plasticization. These boundaries determine machine selection and process settings rather than any single property combination.
Regulatory status for granulated PVB in melt processing depends on the final article and jurisdiction. REACH registration is required for the monomer-unit coverage; RoHS restrictions apply only to lead, cadmium, mercury, hexavalent chromium, and specific brominated flame retardant residues, which are not intentionally added in standard PVB granulate. For food-contact applications, the resin may fall within FDA 21 CFR 175.105 for adhesives and coatings, but repeated-contact molded articles require specific migration testing under EU Regulation 10/2011 or EN 1186 and cannot be cleared solely by resin grade. Thermal processing above 190 °C releases butyraldehyde; processors must use local exhaust ventilation and verify exposure against the relevant occupational exposure limit, commonly cited as 20 ppm for an 8 h time-weighted average in safety data sheets. Granulated PVB is not designed for aqueous emulsion formulation; dissolution or plasticization requires organic solvent or heat and compatible ester plasticizer. The granulated form should be stored in sealed packaging below 30 °C and used within the supplier-specified shelf life to limit moisture regain and blocking in storage silos.
