| HS Code | 224477 |
| Product Name | Butvar B-79 |
| Chemical Family | Polyvinyl butyral (PVB) |
| Cas Number | 63148-65-2 |
| Physical Form | White granular powder |
| Specific Gravity | 1.083 |
| Refractive Index | 1.490 |
| Glass Transition Temperature | 70°C |
| Softening Point | 130°C |
| Tensile Strength | 27.6 MPa |
| Elongation At Break | 60% |
| Hydroxyl Content | 10.5-12.5% typical |
| Solubility | Soluble in alcohols, ketones, glycol ethers, and tetrahydrofuran; insoluble in water |
As an accredited Butvar B-79 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Butvar B-79 polyvinyl butyral resin is supplied as a free-flowing white powder in 25 kg multi-layer paper bags with polyethylene liner. |
| Container Loading (20′ FCL) | Butvar B-79 resin in 25 kg bags, palletized and shrink-wrapped, loaded into a 20′ FCL container, approximately 16–18 metric tons. |
| Shipping | Butvar B-79 is a polyvinyl butyral resin powder, typically shipped as a non-hazardous material. It should be packed in sealed, moisture-proof bags or containers, kept dry, and stored away from heat and ignition sources. No special transport classification is required under normal conditions. |
| Storage | Store Butvar B-79 in a cool, dry, well-ventilated area away from heat, open flames, and strong oxidizing agents. Keep the container tightly sealed to prevent moisture absorption and contamination. Avoid exposure to excessive humidity and direct sunlight. Under recommended conditions, the resin remains stable with a typical shelf life of several years. |
| Shelf Life | Shelf life of Butvar B-79 is typically two years from manufacture when stored in original, unopened containers under cool, dry conditions. |
On a coil-coating line running 0.8 mm cold-rolled steel at 60 m/min, a two-component wash primer based on Butvar B-79 is mixed inline at 7.0–9.0 wt% resin solids. Supplier-published data for Eastman Butvar B-79 list a weight-average molecular weight of approximately 90,000 g/mol and a polyvinyl alcohol content between 10.5 and 13.0 wt%. The high molecular weight fraction produces shear-thinning flow in ketone-alcohol solvent blends. A representative starting formulation contains 8.0 wt% Butvar B-79, 1.8–2.4 wt% orthophosphoric acid of 85% concentration, 2.5–3.5 wt% zinc borate, 0.3 wt% fumed silica, and a 60:20:20 mass ratio of methyl ethyl ketone, ethanol, and toluene. The phosphoric acid is added slowly after the resin is fully dissolved at 20–25°C; acid addition to an undissolved pellet slurry causes localized gelation because the acetal ring hydrolyzes at the pellet surface. Air-atomized spray application deposits 15–20 µm dry film thickness. Overcoating must occur within 4 h at 25°C and 50% RH; longer open times reduce intercoat adhesion with epoxy or polyurethane topcoats. Corrosion resistance is verified by ASTM B117 salt spray and ASTM D1654 scribe evaluation. A target scribe undercut is below 2 mm after 500 h. Dry-film adhesion is measured by ASTM D3359; acceptance is class 4B or 5B on abraded steel. Compliance for chromium-free formulations is assessed against REACH Annex XVII entry 47 for chromium(VI) compounds and MIL-DTL-15328E where applicable to military metal pretreatment. Operational boundaries include pot life below 8 h at 25°C; above 65% RH solvent evaporation causes water condensation and film blush. Incompatible pigments include zinc oxide and calcium carbonate, which consume phosphoric acid and suppress etch adhesion. Amine-based anti-flash additives are also incompatible in this acid-catalyzed primer because they neutralize phosphoric acid before the steel surface is etched.
| Variant | Butvar B-79 wt% | 85% H3PO4 wt% | Zinc borate wt% | Flash-off at 25°C min |
|---|---|---|---|---|
| Low etch | 7.0 | 1.8 | 2.5 | 8 |
| Standard | 8.0 | 2.1 | 3.0 | 10 |
| High etch | 9.0 | 2.4 | 3.5 | 12 |
In retort-grade gravure lamination ink, Butvar B-79 is cold-cut at 10.0–12.0 wt% of total liquid ink solids in a blend of ethyl acetate and ethanol at 40–45°C. The resin is co-dissolved with nitrocellulose in a mass ratio of PVB to nitrocellulose between 1:2 and 1:4. Pigment concentrates are prepared on a horizontal bead mill with 0.6–0.8 mm zirconia media at 3,000–4,000 rpm; dispersion is continued until a Hegman gauge reading of 7 or finer is reached. The final ink is adjusted to 18–25 s with a Zahn cup #2 at 25°C, corresponding to 150–300 mPa·s under low shear. Print transfer is specified for laser-engraved ceramic anilox rolls with 140–180 lines/cm and cell depth 10–12 µm. On corona-treated biaxially oriented polypropylene at 38–42 dyn/cm surface energy, the dried ink film at 1.5–2.5 g/m² is laminated with adhesive to a sealant web. Heat-seal strength of the finished laminate is tested according to ASTM F88; delamination at the ink layer at seal temperatures below 85°C is classified as a coating-anchorage failure under ASTM F904 film lamination bond testing. Compliance for food-contact use rests on FDA 21 CFR 175.105 for components of coatings and adhesives and EU Regulation 10/2011 overall migration limit of 10 mg/dm² for plastic materials in contact with food. Butvar B-79 is hygroscopic; solvent blends must be monitored to maintain water content below 0.1 wt%. Water above this threshold precipitates PVB and blinds press filters. Retort delamination is observed if printing deposits exceed 3.0 g/m² dry film, because the PVB layer softens and swells under 121°C steam sterilization. Press viscosity must be checked every 2 h; solvent loss through evaporation shifts both print density and lamination bond.
A solvent-based wood sanding sealer uses Butvar B-79 at 5.0–7.0 wt% of total liquid to increase early sanding hardness and adhesion to oak and maple substrates. The complete resin matrix consists of 5.0–7.0 wt% Butvar B-79, 10.0–12.0 wt% nitrocellulose of 1/4–1/2 s viscosity, 4.0–6.0 wt% maleic-modified rosin, and 4.0–5.0 wt% dibutyl phthalate. Butvar B-79 is pre-dissolved in ethyl acetate at 20–25°C for 4 h before nitrocellulose is introduced. High-shear mixing with a Cowles disperser at 1,000–1,500 rpm is limited to 20 min because prolonged shear raises stock temperature above 40°C and causes solvent loss. The material is sprayed at 30–35 µm wet film thickness through an airless unit at 80–100 bar; flash-off occurs for 15 min at 50°C in a forced-air tunnel before sanding with 320-grit aluminium oxide paper. Adhesion is tested by ISO 2409 cross-cut; production acceptance is class 1 or 0 on both bare wood and sealed wood. Block resistance is assessed by ASTM D3003; panels are stacked at 40°C for 24 h under 1 kg/cm². Volatile organic compound limits are determined by EU Directive 2004/42/EC Annex II category A/D. Process conflicts exist above 35 wt% total solids, where the high molecular weight fraction of B-79 raises spray viscosity beyond 40 s DIN 53211 and causes orange peel; below 28 wt% solids, pore filling becomes insufficient and two coats are required. Before weighing, B-79 powder should be pre-dried at 60°C for 2 h if ambient storage humidity has exceeded 60% RH.
For multilayer ceramic capacitor green tape, Butvar B-79 is dissolved at 8.0–12.0 wt% of ceramic powder in a 60:40 toluene-ethanol mixture. The ceramic slurry is compounded at 68–72 wt% solids using barium titanate powder with a median particle size 0.6–1.2 µm, B-79 binder, butyl benzyl phthalate at 3.0–5.0 wt% of binder solids, and a phosphate ester dispersant at 0.5–1.0 wt% of ceramic powder. Milling is performed in a polyurethane-lined ball mill with 5 mm zirconia media for 24 h at 45 rpm; the slurry is vacuum-degassed at 700 mbar for 30 min. Tape casting uses a doctor blade with a gap of 150–250 µm and a carrier speed of 1.0–2.5 m/min. Drying takes place in a three-zone air flotation oven with zone temperatures of 50°C, 70°C, and 85°C; residual solvent in the green tape is targeted below 0.5 wt%. Viscosity at 10 s⁻¹ is maintained between 2,000 and 4,000 mPa·s using a cone-plate rheometer; slurries outside this range produce edge defects or pinholes. Binder burnout is monitored by thermogravimetric analysis at 10 K/min; the decomposition onset occurs near 250°C and ash content is specified below 0.02 wt% after 600°C in air. Compliance for lead-free capacitors is linked to RoHS Directive 2011/65/EU and to an ISO 9001-certified process for trace metal control. A moisture-controlled weigh room at 30% RH or lower prevents viscosity drift from PVB water absorption. Incompatible additives include strong mineral acids that would hydrolyze the acetal ring and cause irreversible viscosity loss.
| Property | Method | Control limit |
|---|---|---|
| Slurry viscosity | Cone-plate 10 s⁻¹ | 2,000–4,000 mPa·s |
| Residual ash | TGA in air to 600°C | <0.02 wt% |
| Residual solvent | IR balance | <0.5 wt% |
Phenolic-PVB structural film adhesives for metal-to-metal bonding are compounded with Butvar B-79 at 20.0–40.0 phr of a resol-type phenolic resin. The adhesive is coated onto 6061-T6 aluminium adherends at a dry film thickness of 20–25 µm using a reverse-roll coater at 5–8 m/min. B-stage curing takes place in a forced-air oven at 90°C for 5 min. Final cure is conducted under vacuum-bag pressure of 0.7 MPa at 177°C for 60 min. The PVB phase increases peel toughness while the phenolic network retains high-temperature shear resistance. Floating roller peel is measured according to ASTM D1876; a target minimum for production release is 2.8 N/mm at 23°C. Single-lap shear is tested by ASTM D1002; typical acceptance for a 0.25 mm bondline is 18–22 MPa. Compliance for aerospace secondary structures may require batch traceability to FAR 25.853 for flammability when the adhesive film is used in cabin interior assemblies. Water resistance is checked after 7 days immersion at 50°C; lap shear retention above 85% of dry strength is expected. Limits of processing include moisture sensitivity of the B-staged film; exposure above 60% RH before cure creates blistering during the 177°C cure. Published data for specific B-79-modified phenolic configurations are limited; qualification must therefore be run on production-scale reverse-roll equipment rather than scaled directly from laboratory drawdowns.
An aluminium foil lidding primer is prepared from Butvar B-79 at 8.0–12.0 wt% solids in methyl ethyl ketone and toluene at 70:30. The formulation includes castor oil as a 3.0–5.0 phr plasticizer and fumed silica at 0.5 wt% to reduce blocking. Foil of 20–25 µm thickness is gravure-coated with a 2.0–4.0 g/m² dry film; the coating is dried in a 70–90°C tunnel. Heat-sealing to PVC or PVdC blister sheet is performed at 180–200°C seal bar temperature, 0.3 MPa pressure, and 0.8–1.2 s dwell. Seal strength is tested according to ASTM F88; a minimum of 8 N/15 mm is typical for pharmaceutical lidding. The primer must not block to the adjacent foil side during storage at 40°C; block resistance is checked using ASTM D3354. Compliance for food-contact and pharmaceutical packaging is assessed under FDA 21 CFR 175.300 for resinous and polymeric coatings and USP <661.1> for plastic packaging systems. Adhesion to the foil is sensitive to rolling oil residues; a chromate-free titanium-zirconium conversion treatment improves wetting and wet adhesion. Foil with a water contact angle above 70° before coating shows reduced seal strength due to residual organic contamination. The PVB primer must not be exposed to ketone cleaning solvents after drying because the layer may redissolve and lose coating weight before sealing.
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Butvar B-79 is a thermoplastic polyvinyl butyral resin, CAS 63148-65-2, supplied as a free-flowing white powder. The polymer is produced by condensation of polyvinyl alcohol with butyraldehyde, leaving residual hydroxyl and acetate groups along the acetal backbone. Manufacturer-published typical properties list a weight-average molecular weight of approximately 34,000 g/mol, a glass transition temperature of 72 °C by differential scanning calorimetry according to ISO 11357-2:2020, a hydroxyl content of 10.5–13.0% by weight expressed as polyvinyl alcohol, and a specific gravity of 1.10. The powder is soluble in lower alcohols, glycol ethers, ketones, and esters; it is insoluble in aliphatic hydrocarbons and has limited tolerance for aromatic hydrocarbon diluents. Compared with higher-molecular-weight grades such as Butvar B-72, B-74, and B-76, this product permits higher solids at equal solution viscosity. The polymer is used in high-solids industrial maintenance coatings, flexographic and gravure ink vehicles, acid-activated wash primers, heat-seal adhesives, ceramic green body binders, and as a toughening resin in thermosetting adhesives. Residual hydroxyl sites permit crosslinking with phenolic, isocyanate, and melamine-formaldehyde resins, while the butyral segments provide film flexibility and adhesion to metals, glass, and minerals. The lower hydroxyl content relative to grades such as Butvar B-76 reduces water sensitivity of unpigmented films, but it also limits some crosslinking pathways. Formulators select B-79 when a narrow molecular weight distribution and low solution viscosity are more important than maximum film toughness at elevated temperature.
Solution viscosity of polyvinyl butyral resins in organic solvents is governed by coil size, solvent quality, and interchain hydrogen bonding between residual hydroxyl groups. Butvar B-79 occupies the low-molecular-weight end of the commercial Butvar range. The practical consequence in manufacturing is that a Cowles-type high-shear disperser can dissolve B-79 at 25–35 wt% solids without exceeding 500 mPa·s at 25 °C in ethanol/toluene blends, whereas higher-molecular-weight grades require lower solids or more aggressive agitation to reach similar viscosities. Comparative typical values are given in Table 1; these are manufacturer-published ranges, not product specifications, and incoming raw material retain samples are tested in-house because residual moisture and acetate content shift viscosity. Routine production checks use a Brookfield viscometer according to ASTM D2196-20 at 25 °C and 20 rpm. The ratio of low-shear to high-shear viscosity for B-79 solutions below 20 wt% solids in ketone/alcohol blends is close to 1.0, indicating near-Newtonian behavior. Viscosity drift during storage can occur if the solvent blend contains more than 10% water or if the resin has not been fully dissolved; gel particles and microgels smaller than 25 µm can produce apparent thixotropy and downstream filtration pressure increase.
| Grade | Weight-average molecular weight (g/mol) | Hydroxyl content (% as polyvinyl alcohol) | Solution viscosity at 10 wt% in 60:40 toluene/ethanol at 25 °C (mPa·s) |
|---|---|---|---|
| Butvar B-72 | 170,000–250,000 | 17.5–20.0 | 25–35 |
| Butvar B-74 | 120,000–150,000 | 17.5–20.0 | 15–25 |
| Butvar B-76 | 90,000–120,000 | 17.5–20.0 | 10–15 |
| Butvar B-79 | 34,000–40,000 | 10.5–13.0 | 5–9 |
In crosslinking formulations, the lower hydroxyl content of B-79 influences stoichiometry. For an aliphatic polyisocyanate based on hexamethylene diisocyanate trimer at an NCO:OH ratio of 1.05:1.0, pot life at 25 °C is typically 2–4 h; higher hydroxyl grades shorten pot life because of greater reactive-site density. In phenolic resole systems, curing at 180 °C for 60 s produces a solvent-resistant film; the same cure cycle with unpigmented B-79 yields lower gel content than a high-hydroxyl grade, so catalyst level and cure time require adjustment. Published data for all co-reactant combinations is limited.
Manufacturing solutions of B-79 are prepared in closed jacketed vessels fitted with explosion-proof variable-speed dispersers. The resin is added slowly to the vortex at 20–25 °C; jacket temperature is maintained below 35 °C to reduce solvent evaporation and avoid film formation on the vessel wall. Tip speeds below 8 m/s limit shear heating. After 60–120 min of mixing, the solution is filtered through 25 µm filter bags or cartridge filters. Non-volatile content is checked according to ISO 3251:2019 after 1 h at 105 °C. Viscosity is checked according to ASTM D2196-20; batch records include spindle number, rotational speed, and solution temperature. Solvent classes and solubility behavior are summarized in Table 2. The resin has poor tolerance for aliphatic hydrocarbons; addition of more than 5–10 wt% aliphatic diluent can cause precipitation depending on solvent strength and temperature. Aromatic hydrocarbons can be used as limited diluents in alcohol-rich blends, but cloud point should be confirmed by titration because aromatic tolerance varies with hydroxyl content and moisture.
| Solvent class | Representative solvents | Behavior |
|---|---|---|
| Lower alcohols | Ethanol, isopropanol, n-butanol | Soluble; solution viscosity increases with alcohol chain length |
| Glycol ethers | Propylene glycol monomethyl ether, ethylene glycol monobutyl ether | Soluble; provides coalescing and wetting in coatings |
| Ketones | Methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone | Soluble; fast solvency for high-solids ink vehicles |
| Esters | Ethyl acetate, n-butyl acetate | Soluble; limited use as sole solvent due to lower hydrogen bonding |
| Aromatic hydrocarbons | Toluene, xylene | Limited diluent tolerance; cloud point depends on alcohol co-solvent ratio |
| Aliphatic hydrocarbons | Heptane, mineral spirits | Insoluble; cause precipitation even at low addition levels |
In solvent-based flexographic and gravure ink vehicles, Butvar B-79 is combined with nitrocellulose and polyurethane at 10–15 wt% resin solids of the vehicle. The resin is first dissolved in ethanol or n-propyl acetate at 25–35 wt% solids, then let down with ethyl acetate and n-propanol. Press-ready viscosity is adjusted to 18–22 s by DIN 53211 cup 4 at 25 °C. On a 600 mm web flexographic press running at 300–400 m/min, the lower molecular weight reduces splashing and misting compared with higher-molecular-weight grades. Adhesion to corona-treated polyethylene and polypropylene films with surface energy above 40 mN/m is assessed by tape pull and cross-cut after 24 h conditioning at 23 °C and 50% relative humidity. Total retained solvent in printed film is measured by headspace gas chromatography and maintained below 10 mg/m² according to internal production specifications.
In maintenance and marine coating systems, B-79 is incorporated into a two-component acid-activated wash primer. A reference production batch uses 9–12 wt% resin, 5–8 wt% phosphoric acid 85%, and 0.5–1.0 wt% zinc phosphate in a solvent blend of isopropanol, methyl ethyl ketone, and n-butanol. The acid etches the metal surface and partially hydrolyzes the acetal, generating hydroxyl-rich polar species that improve adhesion to steel and aluminum. The mixed primer exhibits limited pot life because the acid continues to react with the polymer; viscosity is monitored at 1 h intervals and the batch is discarded when viscosity increases by more than 25% from initial value. Production batches are held at 15–25 °C and filtered through 45 µm bags before filling. Adhesion is evaluated on steel and aluminum after 168 h water immersion according to ISO 2812-1:2017 and rated by ISO 2409:2020 cross-cut. The lower hydroxyl content of B-79 relative to B-72 reduces water uptake of unpigmented primer films but also lowers crosslink density when melamine or isocyanate co-reactants are used. For high-humidity application, addition of 2–5 wt% epoxy resin improves wet adhesion but shortens pot life. Published data for this specific configuration is limited; batch records from production lines are the primary source for formulation adjustments.
For dry pressing and tape casting of alumina, silicon carbide, and barium titanate, Butvar B-79 is added at 2–6 wt% of dry solids from a 10 wt% solution in ethanol or methyl ethyl ketone. The low molecular weight allows high green density and lower mixing torque in a planetary mixer or twin-screw extruder with an L/D of 25:1. Thermogravimetric analysis according to ISO 11358-1:2022 in air at 10 °C/min shows complete oxidative decomposition below 600 °C; residual ash after burnout in air is typically below 0.1 wt% when kiln airflow exceeds 0.5 m/s. Under low-airflow or nitrogen-rich conditions, residual carbon can exceed 0.5 wt%, and published data for specific ceramic formulations is limited. Binder removal cycles should use heating at 0.5 °C/min from 200 °C to 500 °C to avoid delamination of green tape. In ceramic injection molding, barrel temperatures are maintained below 90 °C to avoid premature binder loss and screw seizure. The lower hydroxyl content of B-79 compared with Butvar B-76 reduces water adsorption from humid ambient air during green body storage; green bodies are nonetheless stored below 40% relative humidity to maintain dimensional stability.
The hydroxyl content of Butvar B-79 is reported as 10.5–13.0% by weight as polyvinyl alcohol. This is lower than the 17.5–20.0% range typical of Butvar B-72, B-74, and B-76. The practical consequence is a measurable reduction in unpigmented film water uptake after 24 h immersion at 23 °C according to ISO 62:2008; however, the lower hydroxyl density also reduces the number of reactive sites available for melamine-formaldehyde and isocyanate crosslinking. Residual acetate groups, typically below 2.5%, are substantially inert and act as internal chain defects that lower crystallinity and increase solubility in certain solvent blends. Batch-to-batch hydroxyl variation within the allowed range can shift stoichiometric demand by up to 5%, which is why production formulations include an incoming-resin titration correction. Free acidity is kept below 0.05%; elevated acidity accelerates acetal hydrolysis during storage and can appear as a decrease in solution viscosity over time. Ash content is controlled to below 0.05% by ASTM D5630-22 for applications requiring low ionic contamination.
In heat-seal adhesives for lidding films and foil-laminated packaging, B-79 is blended with epoxy or phenolic co-resins at 5–15 wt% of total solids. A typical rotary heat-seal unit operates at 120–150 °C jaw temperature, 0.5–1.0 s dwell time, and 3–6 bar sealing pressure. The low melt viscosity of B-79 promotes wetting of paperboard and aluminum foil without excessive squeeze-out. Peel strength is measured according to ASTM F88/F88M-21; values are substrate-dependent and are not specified without a defined film structure. Storage stability of the formulated adhesive is evaluated by viscosity retention over 30 days at 23 °C; an increase greater than 20% indicates premature crosslinking or solvent loss.
Incoming resin release testing includes hydroxyl content, acetate content, free acidity, ash, and moisture. Ash is determined according to ASTM D5630-22; moisture is measured by Karl Fischer titration and reported as percentage by weight. Storage of the powder below 38 °C and below 60% relative humidity is required to prevent blocking. When ambient relative humidity exceeds 60%, pre-drying in a desiccant drier at 40–50 °C for 2–4 h is used before solution preparation. Avoid storage near strong oxidizing acids; acid-catalyzed hydrolysis of the acetal group can reduce molecular weight and shift solution viscosity. The product is subject to REACH registration. Food-contact use is possible only after review of the manufacturer's compliance statement under 21 CFR 175.105 and 21 CFR 175.300, because extractive limitations vary with end use and food type. A complete VOC compliance assessment requires the solvent blend, not the resin alone, to be evaluated against the applicable regulatory category.
