| HS Code | 315621 |
| Chemical Name | Polyvinyl Butyral (PVB) |
| Appearance | White or pale yellow free-flowing powder |
| Molecular Weight | Moderate to high, typically 40,000 to 200,000 |
| Glass Transition Temperature | Approximately 60-70°C |
| Solubility | Soluble in alcohols, ketones, and ester solvents |
| Adhesion | Excellent adhesion to wood and metal surfaces |
| Film Flexibility | High flexibility with excellent impact resistance |
| Transparency | Optically clear with high gloss when applied |
| Tensile Strength | Good tensile strength in cured films |
| Abrasion Resistance | Provides durable, wear-resistant coating finish |
| Moisture Resistance | Moderate water resistance after proper curing |
| Uv Stability | Resistant to UV degradation when formulated with stabilizers |
| Compatibility | Compatible with alkyd, epoxy, and nitrocellulose resins |
As an accredited PVB Coating Resin for Wood & Metal Finishes factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Available in 25 kg sealed drums, moisture-proof packaging ensures safe handling, transport, and storage of PVB coating resin for wood and metal finishes. |
| Container Loading (20′ FCL) | 20′ FCL: PVB Coating Resin for wood/metal finishes, packed in UN-approved drums, loaded with secure dunnage, ventilated container. |
| Shipping | PVB Coating Resin ships as non-hazardous goods in moisture-proof lined bags or fiber drums. Keep sealed, dry, and away from heat sources during transport. Suitable for standard truck, sea freight, and container loading. Provide SDS, COA, and product labels; no IMDG/IATA restrictions apply. Handle with care to prevent bag damage. |
| Storage | Store in a cool, dry, well-ventilated area away from direct sunlight, heat, and open flames. Keep the container tightly sealed to prevent moisture ingress and contamination. Ideal storage temperature is 5–30°C. Avoid excessive humidity, which can degrade resin quality. Shelf life is typically 12 months; stir well before use. |
| Shelf Life | Shelf life is typically 12 months when stored in a cool, dry place, away from direct sunlight and moisture. |
A two-component wash primer based on PVB resin is charged immediately before use on abrasive-blasted structural steel because the acid component reduces wet-film pH to 1.5–2.5 and initiates hydrolysis of high-hydroxyl PVB grades when contact time exceeds 8–12 h at 20 °C. Formulation additions of PVB resin at 7.0–10.0 wt% of total wet batch are combined with 0.8–2.0 wt% phosphoric acid 85%, 5.0–15.0 wt% water, and a solvent blend of isopropanol and ethanol; the resulting binder solids are generally held at 8–12 wt% to prevent over-thickening during spray application. Production-scale mixing uses a high-speed dissolver fitted with a 600 mm stainless steel disc running at 15–20 m/s tip speed, followed by 150 μm bag filtration. Application through 30:1 airless spray at 50–75 μm wet-film thickness over Sa 2½ surfaces in accordance with ISO 8501-1 yields a 6–10 μm dry conversion film. The cured primer is further qualified under ISO 12944-5:2019 for C3/C4 atmospheric corrosivity and ASTM B117-19 for 500 h scribe-creep resistance; production records on galvanized HVAC housings show that scribe creep remains ≤2.5 mm when the PVB addition is maintained above 7.0 wt%, while lower additions result in edge ringing and intercoat adhesion loss. Operational boundaries include the exclusion of amine-based additives, which neutralize the phosphoric acid and suppress zinc phosphate conversion at the substrate interface. At relative humidity above 80%, condensation fogging on the wet film produces ghosting; preconditioning of the steel surface and solvent dew-point control are therefore required. Terminal finished products include structural steel bridge girders, galvanized steel duct housings, aluminium curtain-wall fixing brackets, and blast-cleaned process skids.
On open-pore oak and ash interior millwork, waterborne cationic primers are displaced by alcohol-borne PVB sealers when tannin bleed-through after 24 h in a humidity cabinet exceeds visual rating 3 on a 1–5 scale. A blocking sealer formulated with 4.0–8.0 wt% PVB resin on wet batch, 0.5–2.0 wt% dibutyl phthalate or castor-oil plasticizer on resin solids, and 0.3–1.0 wt% silica matting agent in a 95% ethanol and 2-propanol mixture is applied by curtain coater at 35–50 μm wet film. Drying at 25 °C for 25 min, followed by sanding with 320–400P aluminium oxide paper, yields a two-pass coat build of 20–30 g/m². The high hydroxyl content of the PVB grade, typically 18–21% polyvinyl alcohol content, contributes to alcohol solubility and rapid release from sanding media without clogging 280P abrasive belts. Compliance for interior millwork includes EN 71-3:2019+A1:2021 migration limits where furniture may enter children’s rooms, and Council Directive 2004/42/EC Annex II category limits for solvent-borne wood coatings. Production-line records from curtain-coating of MDF door skins indicate that batch-to-batch viscosity drift of ±3 s DIN 4 cup at 20 °C occurs with moisture ingress above 0.3% water in the solvent blend; molecular sieves installed in the solvent feed suppress this variability. Terminal finished product types include solid oak interior doors, ash veneer office furniture, window frames, loudspeaker cabinets, and coated interior wall panels.
Reverse roller coating lines processing 30–45 μm aluminium foil for pharmaceutical lidding operate within a narrow viscosity envelope, typically 25–35 s DIN 53211 cup at 25 °C, to avoid ribbing and edge mist. A PVB-rich primer at 2.0–6.0 wt% of the wet coating, corresponding to 15–25% of total binder solids, is applied at 2.5–4.0 g/m² dry film weight and cured at 193–232 °C peak metal temperature for 25–45 s. When topcoated with heat-seal lacquers, the primer maintains T-peel adhesion after sterilization at 121 °C for 30 min in a saturated autoclave, with failure mode remaining cohesive within the sealant film. The coating is referenced against FDA 21 CFR 175.300 and EU No 10/2011 for food-contact metal coatings; specific migration testing is conducted on finished laminate structures because PVB residual hydroxyl content can bind polar food simulants at elevated temperature. On coil lines running at 60 m/min, cratering and odour retention are controlled by maintaining drying-air solvent concentration below 25% lower explosive limit and by using 1.5 mm slit-die air knives to remove boundary-layer solvent. Terminal downstream products include push-through blister lidding, peelable retort pouches, induction-seal cap liners, and aluminium foil over-lacquers for confectionery.
Humidity exposure of aftermarket refinished zinc-coated panels reveals adhesion loss when the intermediate primer contains no hydroxyl-bearing binder capable of interacting with residual zinc phosphate and ambient moisture. A one-component PVB-based adhesion promoter with 5.0–10.0 wt% resin wet, 0.5–1.2 wt% phosphoric acid, and 10–15% 2-butoxyethanol in isopropanol is sprayed at 10–15 μm dry-film thickness using a gravity-fed HVLP sprayer with a 1.3 mm nozzle. After 10 min flash-off, a two-component isocyanate-crosslinked topcoat is applied and baked for 30 min at 60 °C. Cross-cut adhesion measured to ISO 2409:2013 on DX56D+Z electrogalvanized substrates remains classification 0 after 480 h ASTM B117-19 salt-spray exposure; blistering under ASTM D714-02 is rated 10. Panels without the PVB primer fail to classification 3 after 240 h, with blistering at weld seams and stone-chip zones. The operational pot life of the two-component system is 2 h at 22 °C; batching beyond this window increases surface roughness and reduces gloss retention. Production-scale refinish booths report that bake-temperature overshoot above 65 °C causes edge mapping and visible ghost lines on silver metallic topcoats, requiring infrared thermography calibration of booth heat gradients to ±3 °C. Terminal finished product types include replacement galvanized fenders, door skins, sill sections, and aftermarket commercial vehicle panels.
| Downstream application | Cited standard | Test or requirement | Typical target |
|---|---|---|---|
| Two-component wash primer | ISO 8501-1, ISO 12944-5:2019, ASTM B117-19 | 500 h salt spray scribe creep | ≤2.5 mm |
| Wood tannin-blocking sealer | EN 71-3:2019+A1:2021, 2004/42/EC | Migration of elements, VOC category limit | Category A/d compliant |
| Aluminium foil primer | FDA 21 CFR 175.300, EU No 10/2011 | Food-contact coating migration | Specific migration limit compliant |
| Automotive refinish adhesion promoter | ISO 2409:2013, ASTM D714-02 | Cross-cut, blister rating | Classification 0, rating 10 |
| Wood sanding sealer | ASTM D1211-97, EN 12720:2013 | Cold-crack resistance, cold-liquid resistance | No film rupture after 25 cycles |
| Temporary peelable coating | ISO 11339:2018, ISO 9227:2017 | T-peel, salt spray | <0.6 N/mm, 1,000 h no red rust |
| Epoxy-PVB coil primer | AAMA 2605-22, EN 13523-8:2017 | Architectural coating durability, salt spray fog | No creep from stylus scribe at 1,000 h |
In alcohol-borne wood sanding sealers, nitrocellulose is replaced at 6.0–12.0 wt% wet with PVB resin when intercoat adhesion after 24 h re-coating and cold-check resistance under ASTM D1211-97 are specified for large-format veneer office furniture. The PVB is dissolved under 600–900 rpm turbine agitation at 25 °C in an ethyl acetate and ethanol blend; 3.0–8.0 wt% zinc stearate or silica matting agent is then dispersed for 15 min at 15 m/s tip speed. Viscosity after 24 h aging is 25–35 s DIN 53211 cup at 20 °C; application by curtain coater at 60–80 μm wet film on MDF subsequently overcoated with 100 g/m² topcoat yields a dry-film build of 30–40 g/m². The PVB grade selected for this application carries a weight-average molecular weight near 75,000 g/mol and a polyvinyl alcohol content of 18–21%, balancing alcohol solubility with sanding release and solvent release from films below 35 μm. Qualifying tests include EN 12720:2013 cold-liquid resistance on furniture surfaces and recoating after 24 h under shop air at 45–55% relative humidity. Terminal finished product types include kitchen cabinet doors, laminate-surfaced office desktops, wood-framed acoustic panels, and loudspeaker cabinets.
Prevention of interstage corrosion on polished 304 stainless steel sheet during fabrication is addressed with a solvent-cast PVB peelable film applied at 25–40 μm dry thickness. The coating is formulated at 15.0–20.0 wt% PVB resin wet, 2.0–5.0 phr plasticizer on resin solids, and 5.0–10.0 wt% ethanol and toluene diluent, then applied by reverse roller coater at 10–15 m/min and dried at 80–110 °C for 3–5 min. Peel initiation measured with a 180° fixture adapted from ISO 11339:2018 is maintained below 0.6 N/mm after 6 months of indoor storage so that removal does not tear the film or leave adhesive residues on brushed metal surfaces. Because the temporary coating is not a permanent corrosion-control system, qualification is limited to ISO 9227:2017 salt-spray exposure for 1,000 h with no red rust on 304 stainless steel. Terminal downstream products include stainless steel architectural cladding strips, aluminium extrusion profiles, copper sheet blanks, and polished metal nameplate stock awaiting subsequent braking, punching, or laser cutting.
Chromate-free coil primers formulated with epoxy resin and 5.0–15.0 wt% PVB on total binder solids are applied to 0.5 mm aluminium alloy 3005 strip before PVDF topcoating at 25 μm. The primer is deposited at 5–8 μm dry using a three-roll reverse coater at 60 m/min, cured at 232–249 °C peak metal temperature, quenched to 40 °C, and immediately recoated. PVB contributes hydroxyl groups for epoxy-phenolic crosslinking, reduces edge pull-away on cut edges after 1,000 h ISO 9227:2017 exposure, and maintains flexibility in EN 13523-8:2017 salt-spray fog testing of stylus-scribed panels. The primer is qualified under AAMA 2605-22 architectural coating requirements for exterior aluminium; process capability studies on coil lines show that viscosity drift of ±2 s DIN 4 cup at 25 °C occurs when PVB solution temperature falls below 15 °C, producing ribbing in reverse roll application. Terminal finished product types include architectural aluminium cladding panels, curtain-wall cassettes, rain-screen boards, and soffit sheets.
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PVB Coating Resin for Wood & Metal Finishes is a free-flowing polyvinyl butyral powder supplied in three model designations: PVB-WM-11, PVB-WM-16, and PVB-WM-20. The numeric suffix identifies the nominal residual hydroxyl content in mol%, which is the primary parameter controlling solvent selection, crosslinking density, adhesion to polar substrates, and film toughness. The polymer backbone contains residual secondary hydroxyl groups, acetate groups, and butyral acetal rings. Acetate content is kept below 3.0 mol% to reduce acid-catalyzed hydrolysis during storage in alcohol-containing solvent blends. The resin is soluble in ethanol, n-propanol, isopropanol, glycol ethers, methyl ethyl ketone, butyl acetate, and selected aromatic/aliphatic mixtures; it is insoluble in aliphatic hydrocarbons and water. Density measured by ISO 1183 is 1.08–1.12 g/cm³. Table 1 lists representative specification ranges for the three models.
| Property | Test method | PVB-WM-11 | PVB-WM-16 | PVB-WM-20 |
|---|---|---|---|---|
| Residual hydroxyl content | ASTM D1396-19 | 10.5–12.0 mol% | 16.0–18.0 mol% | 19.0–21.0 mol% |
| Acetate content | ASTM D1396-19 | ≤3.0 mol% | ≤2.5 mol% | ≤2.0 mol% |
| Weight-average molecular weight | ISO 16014-2 | 90,000–120,000 g/mol | 90,000–120,000 g/mol | 30,000–60,000 g/mol |
| Solution viscosity, 10 wt% in ethanol/toluene 60:40 at 25 °C | ASTM D2196, Brookfield RVT, 20 rpm | 15–25 mPa·s | 20–35 mPa·s | 8–15 mPa·s |
| Glass transition temperature | ISO 11357-2, DSC, second heating | 58–64 °C | 66–72 °C | 70–75 °C |
| Volatile content | ISO 3251, 105 °C, 3 h | ≤2.0% | ≤2.0% | ≤2.0% |
| Ash residue | ISO 3451-1, 750 °C | ≤0.05% | ≤0.05% | ≤0.05% |
PVB-WM-11 is specified for softer films and formulations requiring lower solvent polarity and reduced moisture sensitivity. PVB-WM-16 is the standard wood sealer, sanding primer, and general metal lacquer resin. PVB-WM-20 is used in wash primers and thermoset systems because the higher hydroxyl concentration increases reaction density with phenolic, melamine, or isocyanate crosslinkers. The molecular weight range of each model is matched to hydroxyl content to maintain a practical spray viscosity without excessive solvent demand.
For acid-catalyzed wood primers, PVB-WM-16 is dissolved at 10–15 wt% resin solids in a solvent blend of ethanol, n-butanol, and butyl acetate. Methylated melamine formaldehyde is added at 5–20 phr on resin solids, with p-toluenesulfonic acid at 0.3–0.6 wt% on total resin solids. Cure is measured by solvent double rubs according to ASTM D5402; a qualified film typically withstands 50–100 double rubs after a forced-air oven schedule of 80–100 °C for 15–25 min in a convection oven with 5–8 air changes per minute. Oven temperature must be controlled within ±5 °C. Below 75 °C, incomplete crosslinking produces surface blocking on sanding belts; above 105 °C, edge discoloration on white oak veneer and intercoat adhesion loss with nitrocellulose topcoats are observed.
On a production wide-belt sander using P220 aluminum oxide belts at 18–22 °C, crosslinked PVB-WM-16 primer produces a compact white powder without clogging the abrasive. Undercured film smears, and over-cured film chips. High-hydroxyl PVB-WM-20 in two-pack aliphatic polyisocyanate systems gives cross-cut adhesion of 0–1 on birch veneer according to ISO 2409 after 7 days at 25 °C. Ready-to-spray pot life at 20 °C is 4–6 h; a rise above 30 s in a DIN 4 mm cup indicates the end of the working window. Amine neutralizers such as triethylamine and dimethylethanolamine must be avoided because they inhibit acid catalysis and retard isocyanate reaction.
Application as a wash primer on metal substrates uses PVB-WM-20 in a two-part system. The base component contains 10–12 wt% resin solids in a solvent blend of 15–20 wt% ethanol, 30–35 wt% n-butanol, 35–40 wt% isopropanol, and 5–10 wt% methyl ethyl ketone. The activator contains phosphoric acid and alcohol. The mixed material is applied at 8–15 µm dry film thickness with conventional or HVLP spray equipment using a 1.0–1.3 mm nozzle and 1.5–2.0 bar atomizing pressure. On degreased cold-rolled steel, cross-cut adhesion per ASTM D3359 Method B is rated no lower than 4B after 24 h at 23 °C and 50% relative humidity. For chromium-free zinc phosphate conversion coatings, neutral salt spray testing according to ISO 9227 for 240 h typically allows scribe creep no greater than 2 mm when evaluated by ISO 4628-8 or ASTM D1654. The primer alone is not intended as an exterior topcoat. Water immersion at 23 °C for 96 h can produce visible whitening in unpigmented films because the resin is hygroscopic. On hot-dip galvanized steel, the acid activator must be reduced to 0.3–0.5 wt% phosphoric acid to prevent zinc dissolution and black staining.
PVB solutions exhibit pseudoplastic flow. At spray viscosity of 20–25 s in a DIN 4 mm cup at 20 °C, a 12 wt% PVB-WM-16 solution in ethanol/n-butanol/butyl acetate 50/30/20 by weight shows Brookfield RVT viscosity of 150–250 mPa·s at 20 rpm and 50–80 mPa·s at 100 rpm. The shear-thinning index between 20 and 100 rpm is typically 2–4. Zinc phosphate pigment dispersion is performed under high shear with a cowles blade at 15–20 m/s tip speed, with dispersion temperature maintained below 40 °C to prevent solvent loss and pigment wetting failure.
Solvent release is rapid during the first 2–3 min after application. Surface dry occurs in 7–10 min at 23 °C and 50% relative humidity. Through-dry for a 20 µm dry film is 25–35 min under the same condition and 8–12 min in a forced-air oven at 50 °C. Films skinned at 50 °C may retain residual butanol and exhibit solvent popping if topcoated within 10 min; a recoat interval of 20–30 min is generally specified. When relative humidity exceeds 60%, the resin powder should be predried at 35–40 °C for 4–6 h to reduce moisture content below 0.5% before dissolution, thereby preventing haze and microcracking.
Substitution of nitrocellulose in metal lacquers is evaluated where the nitrate ester functionality of nitrocellulose imposes storage, transport, and stabilizer requirements. PVB-WM-16 contains no nitrate ester groups and is supplied dry without alcohol wetting. In accelerated heat aging at 60 °C for 14 days in a closed container, PVB-WM-16 does not release acidic decomposition gases, whereas nitrocellulose requires stabilizer monitoring. Relative to nitrocellulose, PVB-WM-16 provides broader alcohol tolerance, better adhesion to bare aluminum and cold-rolled steel, and lower ultraviolet yellowing. Its free secondary hydroxyls permit thermoset crosslinking that nitrocellulose cannot provide. Compared with cellulose acetate butyrate, PVB-WM-16 has lower cost per unit solids and higher reactive functionality, but slower solvent release after surface skin formation. Compared with acrylic polyols, PVB-WM-16 forms a film primarily by solvent evaporation before crosslinking and can be sanded and recoated more readily. Table 2 summarizes comparative properties using standard test methods.
| Parameter | PVB-WM-16 | Nitrocellulose 1/2 sec | CAB 551-0.2 | Acrylic polyol |
|---|---|---|---|---|
| Available hydroxyl functionality | 16.0–18.0 mol% | none | 0.5–2.0 wt% | 2.5–4.2 wt% on solids |
| Adhesion to untreated Al 2024-T3, ASTM D3359 | 3B–4B | 2B–3B | 1B–2B | 4B–5B |
| Flexibility, ISO 1519, 20 µm dry film | no crack at 6 mm mandrel | no crack at 10 mm mandrel | no crack at 12 mm mandrel | no crack at 6 mm mandrel |
| Crosslinking with melamine or isocyanate | yes | no | limited | yes |
| Solvent release rate at 25 °C | medium | high | low | low |
PVB coatings are not intended for continuous immersion or exterior exposure without topcoating. Under 500 h QUV-B cyclic exposure according to ISO 16474-3, unpigmented PVB-WM-16 films retain adhesion on aluminum but develop yellowing and slight embrittlement unless benzotriazole ultraviolet absorbers and hindered amine light stabilizers are incorporated. Compatibility with alkyd resins is limited to low oil length types; addition above 25 wt% on total resin solids can produce phase separation. The powder should be stored in sealed polyethylene-lined kraft bags at 5–30 °C and <60% relative humidity. Dust should be controlled with local exhaust ventilation. Regulatory status under REACH must be confirmed for the specific grade; RoHS Directive 2011/65/EU Annex II screening for cadmium, lead, mercury, and hexavalent chromium commonly uses the 1000 ppm threshold. FDA 21 CFR 175.300 may apply to certain PVB resins as components of coatings for food contact, but supplier confirmation is required for the exact model.
On grit-blasted steel prepared to Sa 2.5 per ISO 8501-1, a 12–15 µm dry film of PVB-WM-20 wash primer exhibits cross-cut adhesion of 0–1 according to ISO 2409 and pencil hardness of HB–F per ASTM D3363 after 7 days at 23 °C. Cupping flexibility measured by ISO 1520 reaches 5–7 mm without cracking. PVB-WM-11 produces lower hardness and lower adhesion on bare steel, indicating that residual hydroxyl content below 12 mol% is insufficient for durable wash primer performance unless an external adhesion promoter is added. On chromate-free conversion coatings, the mixed primer must be applied within 15–20 min after acid activator addition. Delayed application beyond 20 min causes viscosity rise and adhesion loss from acid attack on the resin.
On a high-speed reverse roll coater processing 0.4–0.6 mm aluminum coil at 120–180 m/min, PVB-WM-16 is applied at 8–10 µm dry film. Coating head viscosity is held at 18–22 s DIN 4 cup. Below 17 s, film splitting produces streak defects; above 24 s, transverse chatter marks appear. The first oven zone is set at 75–85 °C for 8–12 s, followed by a second zone at 95–105 °C for 8–12 s. Premature crosslinking in the first zone causes blocking at the exit nip; insufficient temperature leaves residual solvent that blisters under the external topcoat. These process limits apply to the specified line speed range; published data for this specific configuration is limited for coil lines operating below 30 m/min.
