| HS Code | 433651 |
| Chemical Name | Polyvinyl Butyral |
| Cas Number | 63148-65-2 |
| Chemical Formula | (C8H14O2)n with partial hydroxyl and acetate units |
| Appearance | White free-flowing powder |
| Molecular Weight | 25,000 - 350,000 g/mol |
| Butyral Content | 70 - 88% |
| Hydroxyl Content | 14 - 23% |
| Acetate Content | 0 - 5% |
| Viscosity | 5 - 100 mPa·s (20% ethanol solution, 25°C) |
| Glass Transition Temperature | 60 - 80°C |
| Softening Point | 150 - 180°C |
| Tensile Strength | 20 - 40 MPa |
| Elongation At Break | 50 - 200% |
| Specific Gravity | 1.08 - 1.10 g/cm³ |
| Solubility | Soluble in alcohols, esters, glycol ethers; insoluble in water and aliphatic hydrocarbons |
| Moisture Absorption | ≤ 1% |
As an accredited PVB for Transfer Printing Inks factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | PVB for transfer printing inks is supplied in 25 kg sealed multi-layer paper bags, ensuring moisture protection and safe handling. |
| Container Loading (20′ FCL) | 20′ FCL container loading of PVB resin for transfer printing inks, securely packed in bags on pallets for safe transport. |
| Shipping | PVB for Transfer Printing Inks ships as a non-hazardous solid resin powder, packed in moisture-proof sealed bags or drums. Keep dry, cool, and away from ignition sources. Avoid dust accumulation and impact damage. Standard freight and air transport are suitable, with proper labeling and documentation per local chemical shipping regulations. |
| Storage | Store PVB for transfer printing inks in a cool, dry, well-ventilated area, away from direct sunlight, heat, and ignition sources. Keep containers tightly sealed to prevent moisture absorption. Maintain temperatures below 30°C. Avoid contact with strong oxidizers. Under proper conditions, shelf life is typically 12–24 months. |
| Shelf Life | Shelf life is typically 12 months from production date when stored unopened in a cool, dry place. |
Polyvinyl butyral is dissolved at 8–12 wt% in a 95:5 ethanol/diethylene glycol monobutyl ether blend for ceramic decal transfer inks used on tableware. The clear binder solution is let down with ceramic flux and pigment at a binder-to-flux mass ratio of 15:85 to 25:75. Dispersion is carried out on a three-roll mill to a fineness of 10–20 µm measured by ISO 1524:2013. Screen printing through 77–120 threads/cm polyester mesh deposits a wet film on coated release paper. The dried decal is then covered with a poly(methyl methacrylate) covercoat and applied to glazed bisque by water-slide or heat release. Firing is run at 780–850 °C. The ramp through the 220–450 °C binder burn-out window is held at 5–10 °C/min. Polyvinyl butyral and the covercoat must decompose before frit sintering begins near 620–680 °C. Gas evolution from oxidative decomposition can lift printed areas if the kiln ramp exceeds 15 °C/min inside the burn-out window. Residual carbon after binder removal is maintained below 0.1 wt% to avoid black speck defects in white glazes. Tableware release of lead and cadmium is tested according to ISO 6486-1:2019 and checked against the limits in Directive 2005/31/EC. Pre-drying of the printed sheet at relative humidity above 60% requires a 30–40 °C forced-air tunnel for 20–30 min. Without that step, the hygroscopic polyvinyl butyral layer remains tacky and blocking occurs during stack storage.
Adhesion of the unfired decal to release paper is checked per ISO 2409:2013. Blocking resistance is confirmed by stacking dried sheets at 40 °C for 48 h. Medium-molecular-weight grades with solution viscosity near 20–25 mPa·s at 10 wt% in ethanol under DIN 53015 are used for gravure decal covercoats. High-hydroxyl grades give more crosslinkable sites but can retain moisture more strongly. The practical storage limit for printed decal sheets is therefore 18–25 °C and 45–55% RH in sealed polyethylene wrapping.
Container glass transfer enamels fire at lower temperature than ceramic tableware decals, typically 580–620 °C. The issue is not whether polyvinyl butyral survives firing. The binder must decompose before the zinc borosilicate frit seals the glass surface and traps carbon. In this system, a 10 wt% polyvinyl butyral solution in butyl glycol ether and ethanol is added at 30–45 parts for every 100 parts of mixed frit and pigment. The ink is screen-printed through 195–305 threads/cm stainless steel mesh and dried to residual solvent of 1.5–2.5 wt%. A wax release layer applied at 1.0–1.5 g/m² dry film assists hot transfer. The glass surface is preheated to 300–350 °C before application. Softened polyvinyl butyral provides temporary adhesion until the ware enters the lehr. Finished products include decorated beverage bottles and cosmetic containers. Lip-and-rim surfaces must meet California Proposition 65 lead and cadmium release limits and Directive 2005/31/EC requirements where applicable. Destructive burn-out checks are performed by thermogravimetric analysis in air at 10 °C/min. The derivative weight-loss peak for polyvinyl butyral is expected before 400 °C; residual carbon above 0.3 wt% suggests insufficient air supply in the preheat zone. Ware stored before firing at relative humidity above 65% may soften the water-slide transfer edge because polyvinyl butyral is hygroscopic. Production plants therefore run the transfer line and lehr entry at controlled humidity below 55% RH.
Glass transfer inks containing polyvinyl butyral also require a careful solvent tail. Butyl glycol ether improves screen open time but slows drying. A typical letdown solvent is 70:20:10 ethanol/butyl glycol ether/ethyl acetate. Dry film weight after screen printing is held at 20–30 g/m². Heavier films can release cleanly but may trap air bubbles during firing. Lighter films cannot hold the frit layer together during water-slide transfer. The operating window is therefore narrow. Screen shops record batch-to-batch variance in peel adhesion if the polyvinyl butyral lot has a hydroxyl content shift of more than 2 wt%.
Water-transfer hydrographic inks use polyvinyl butyral for its behaviour after solvent activation with butyl glycol ether or a dibasic ester blend. A typical gravure letdown contains 10–14 wt% polyvinyl butyral resin, 65–75 wt% alcohol/glycol ether solvent, 5–10 wt% plasticizer, and 10–20 wt% pigment. The ink is printed at 4–8 g/m² dry on a polyvinyl alcohol carrier film. The printed film is floated on water for 20–40 s. An activator solvent is then sprayed to soften the polyvinyl butyral ink layer. The softened film is pressed onto primed ABS, polyamide, or polycarbonate parts. Full adhesion develops after drying at 50–60 °C for 15–30 min. High-boiling activators with relative evaporation rates above 500 versus n-butyl acetate slow drying and can cause washout on the water surface. Fast solvents lift the film too early and create wrinkles. Polyvinyl butyral with a glass transition temperature near 70 °C provides enough stiffness for film handling but remains flexible over three-dimensional part contours. Blocking of printed film reels occurs when residual solvent exceeds 2.0 wt%. Online gas chromatographic checks at the rewinder are used to stop blocked reels before slitting.
For automotive interior trim, transferred films are tested by cross-cut adhesion under ISO 2409:2013 after humidity ageing at 50 °C/95% RH for 240 h. Emission performance is evaluated by VDA 278:2011 for volatile and semi-volatile organic compounds. Butyl glycol ether is subject to REACH registration and CLP labelling. Finished parts are controlled for residual solvent rather than relying only on raw material declarations.
Polyvinyl butyral hot-split inks are used for decorative heat transfers applied to cosmetic cases, appliance fascias, and automotive interior trim. A screen-printing grade letdown contains 12–16 wt% polyvinyl butyral resin solids, 55–65 wt% high-boiling ester/alcohol solvent, 15–25 wt% pigment, 1–3 wt% fumed silica, and 0.5–2 wt% low-density polyethylene wax. The ink is printed on a silicone-coated polyester carrier. Heat pressing at 150–180 °C and 2–4 bar for 3–8 s fuses the printed layer to the sheet. After cooling, the polyester carrier is peeled away. Polyvinyl butyral heat-seals through interfacial diffusion with PVC or ABS. Press temperatures below 140 °C cause cold-peel adhesion failure. Press temperatures above 190 °C can shrink the polyester carrier and distort fine text. Fogging on automotive glazing is limited by keeping plasticizer content below 3 wt% and selecting triethylene glycol bis(2-ethylhexanoate) rather than an unregistered low-molecular-weight ester. Cross-cut adhesion after transfer is checked on injection-moulded ABS plaques per ISO 2409:2013. Acceptable performance is grade 0–1 with no edge lift after 24 h at room temperature. Chemical resistance is screened by iso-octane and naphtha rub testing according to ASTM D5402-19. Terminal parts include decorated hair-dryer housings, thermostat covers, and automotive ashtray lids. Polyvinyl butyral is not considered a direct food-contact binder in this construction. Converters must confirm end-use regulatory status when the decorated part is used near food.
Blocking of printed carrier rolls is a production bottleneck. Hot-split inks with polyvinyl butyral tend to build static charge during slitting. Static charge attracts dust and causes edge curl. Some lines add 0.2–0.5 wt% of a polyether modified siloxane surface additive to reduce static. The same additive can lower transfer adhesion if it migrates to the interface. The process window is therefore validated by pilot pressing rather than by laboratory drawdown alone.
Room-temperature water-slide transfer inks are used where the final substrate cannot be heated. A 10 wt% polyvinyl butyral solution in 80:20 ethanol/1-methoxy-2-propanol is combined with pigment paste and 3–5 wt% of a blocked aliphatic polyisocyanate based on polyvinyl butyral solids. The ink is screen-printed through 90–120 threads/cm mesh and dried at 40–50 °C. The printed decal is water-dipped for 30–60 s, slid onto glass or coated metal, and left to crosslink at 20–25 °C for 48–72 h. Pot life after isocyanate activation is 4–8 h at 23 °C. High relative humidity shortens pot life because polyvinyl butyral absorbs moisture and water competes with the isocyanate crosslinker. This chemistry is used for short-run marking on cosmetic bottles and appliance panels where fired ceramic transfers are not possible. Rubbing resistance is evaluated by methyl ethyl ketone double rubs using ASTM D4752-20. Adhesion after 24 h water immersion is checked by ISO 2409:2013. The isocyanate component must be handled under local exhaust because airborne isocyanate exposure is controlled under REACH restriction and workplace exposure limits. Finished printed films are not food-contact approved unless separately tested under the relevant finished article framework.
In high-speed gravure printing of transfer release papers, solvent retention is the limiting variable. Polyvinyl butyral can hold alcohols strongly and raise residual solvent. A solution viscosity of 20–30 mPa·s at 10 wt% in ethanol under DIN 53015 is normally selected. The letdown is cut to press viscosity with a blend of 70:20:10 ethyl acetate/ethanol/propylene glycol monomethyl ether and run at 24–28 s efflux time in a 4 mm DIN cup. Drying is performed at 50–70 °C with forced air. Residual solvent after drying is held below 1.5 wt% by weight. Adding more than 5 wt% water to the solvent blend can precipitate polyvinyl butyral, so water cannot be used as a cheap diluent. The printed transfer paper is checked for blocking under 20 kPa pressure at 40 °C for 24 h using ASTM D4946-89. At higher press speeds, some converters switch to a lower-molecular-weight polyvinyl butyral grade. The lower grade reduces viscosity but decreases hot-split peel strength. The formulation must therefore be rebalanced with 1–2 wt% of a polymeric plasticizer to maintain film toughness without creating fogging. Terminal products are transfer papers for hot-peel labels and decorative graphics. The key operational boundary is storage temperature. Printed rolls stored above 35 °C can develop progressive blocking even at acceptable residual solvent levels. Warehouses therefore monitor floor-level temperature rather than setpoint alone.
Polyvinyl butyral solutions in alcohol and glycol ether are sensitive to acidic hydrolysis. Inks with pH below 4.5 can undergo butyral ring cleavage over storage. This causes viscosity drift and print line thickening. Amine-based dispersants should be screened because they can neutralise acidic carbon black pastes and reduce dispersion stability. The final gravure letdown is checked for non-volatile content by ISO 3251:2019 and for density by ISO 2811-1:2016. Viscosity is retested after 24 h because some pigment surfaces adsorb polyvinyl butyral and raise apparent high-shear viscosity on the press. Production-scale gravure lines with enclosed doctor blades show lower solvent loss than open ink troughs. The result is a narrower viscosity drift and more stable transfer paper sheet length.
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Polyvinyl butyral (PVB) for transfer printing inks is supplied as a fine white powder with controlled residual acetate and hydroxyl functionality. The resin is characterized by a butyral content of 75–82 wt%, a hydroxyl content of 18–22 mol% relative to the polyvinyl alcohol backbone, and residual vinyl acetate below 2.5 mol%. It is produced by acid-catalyzed acetalization of polyvinyl alcohol with butyraldehyde, followed by neutralization, washing, and drying to reduce ash and moisture. For transfer-printing applications the resin is selected to give a viscosity number of 40–80 mL/g when measured as a 0.5 g/dL solution in ethanol at 25 °C according to ISO 1628-1:2021. The glass transition temperature determined by differential scanning calorimetry at 10 K/min under nitrogen is 68–72 °C per ISO 11357-2:2020. Density of the solid polymer is 1.08–1.12 g/cm³ when measured by ISO 1183-1:2019. The powder is amorphous and forms clear, flexible films from alcohol/ester solvent blends.
Solubility in transfer-ink solvent blends is graded by haze after 24 h at 25 °C. A clear solution in ethanol/toluene at 80:20 by weight indicates low microgel content. At ethanol contents above 85 wt%, low-viscosity grades remain clear, but medium-viscosity grades can develop thixotropic gel structure below 15 °C. The addition of 5–10 wt% ethyl acetate or methyl ethyl ketone breaks hydrogen-bonded clusters and reduces solution viscosity without changing the PVB concentration. Solution turbidity is measured by nephelometric haze; values above 20 NTU indicate microgel or contamination from inadequate dispersion.
Hydroxyl concentration exerts a direct effect on transfer-release behavior. Hydroxyl units hydrogen-bond with hydroxylated paper surfaces, glass, and ceramic bisque, while butyral segments contribute cohesive film strength and compatibility with silicone-coated polyester release carriers. In laboratory drawdowns on silicone-coated PET, grades with hydroxyl content above 22 mol% exhibit higher release force and occasional blocking after 24 h at 40 °C and 70% RH. Grades below 18 mol% hydroxyl reduce blocking but may lower adhesion to ceramic bisque after heat transfer below 180 °C. The specification window therefore balances two failure modes. Rewet resistance in water-based overcoats is controlled more by residual acetate and low-molar-mass oligomer content than by hydroxyl content alone. Residual vinyl acetate above 2.0 mol% correlates with softer films and greater tack at 35 °C. Acetal content is not uniform along the chain; random block distribution is typical for commercial PVB.
The two standard viscosity grades are distinguished by viscosity number. A low-viscosity grade at 40–50 mL/g is used for gravure and inkjet-assisted transfer coatings where rapid solvent release is required; a medium-viscosity grade at 60–80 mL/g is used for screen-print pastes requiring higher body and edge definition. Table 1 lists the typical acceptance windows and test methods.
| Property | Test method | Low-viscosity grade | Medium-viscosity grade |
|---|---|---|---|
| Viscosity number | ISO 1628-1:2021 | 40–50 mL/g | 60–80 mL/g |
| Ash content | ISO 3451-1:2019 | < 0.1 wt% | < 0.1 wt% |
| Moisture content | ISO 3251:2019 | < 0.5 wt% | < 0.5 wt% |
| Glass transition temperature | ISO 11357-2:2020 | 68–72 °C | 68–72 °C |
| Sieve residue on 315 µm | ISO 2591-1:2022 | < 1.0 wt% | < 1.0 wt% |
| Heavy metals concentration | RoHS 2011/65/EU Annex II | application-dependent | application-dependent |
Molecular weight distribution by size-exclusion chromatography with polystyrene calibration is controlled to Mw/Mn 2.5–3.5. A narrower distribution reduces microgel formation and improves solution clarity. Higher viscosity grades with viscosity number above 80 mL/g produce gels in ethanol/toluene blends below 15 °C. For gravure inks, low-viscosity grades avoid shear thickening in enclosed doctor blade chambers at shear rates above 104 s−1; screen-print pastes are more tolerant of higher viscosity but require a three-roll mill pass to eliminate agglomerates.
In high-speed gravure transfer printing at web speeds of 60–80 m/min, residual solvent in the printed film after the drying hood is a critical threshold. Narrow-molecular-weight grades release retained ethyl acetate more rapidly than broad-distribution grades. Thermogravimetric isothermal scans at 80 °C for 30 min show residual solvent values of 0.2–0.5 wt% depending on final dry film thickness and solvent blend. Production forced-air ovens with nozzle air velocity 20–25 m/s and drying length 2.0–2.5 m are typical for this purpose. If retention exceeds 0.3 wt%, blocking in the windup section becomes measurable. Methyl ethyl ketone is added at 10–20 wt% of the solvent blend to lower viscosity and accelerate vaporization; excess MEK reduces shelf stability and can swell butyl rubber rollers. The low-viscosity grade is preferred for gravure because its solution viscosity at 25 wt% solids is 800–1,200 mPa·s at 20 rpm Brookfield, dropping to 80–150 mPa·s under typical gravure shear. If the solution is diluted below 15 wt% solids, dry film thickness falls below 2 µm, leading to weak transfer and partial coverage.
On a narrow-web gravure line with cylinder circumference 640 mm and enclosed doctor blade chambers, molecular weight heterogeneity outside the specified band produces banding above 70 m/min. Batch-to-batch variation in viscosity number should not exceed ±5 mL/g because larger deviations shift solvent retention and change release force on silicone-coated polyester. Alcohol-rich solvent systems may foam in the ink tray when disperser speed exceeds 1,500 rpm; addition of 0.05–0.1 wt% silicone-free defoamer is often required but must be validated because some defoamers increase residual transfer defects. Viscosity drift during an 8 h press run should remain below 5%; higher drift indicates solvent evaporation imbalance in the ink circulation loop.
Screen-print transfer pastes are compounded at 30–40 wt% solids with PVB medium-viscosity grade. Three-roll mill processing at nip pressures of 0.2–0.5 MPa and roller temperature 25–30 °C disperses pigment and removes air. Paste rheology measured on a cone-and-plate rheometer at 25 °C shows viscosity of 5,000–10,000 mPa·s at 1 s−1 and shear thinning to 1,000–2,000 mPa·s at 100 s−1. Paste yield stress measured by controlled-stress rheometer is 200–400 Pa, supporting stable mesh clearing. High shear thinning is attributed to the PVB polymer network and is necessary for screen snap-off.
Neat PVB films cast from ethanol/toluene at 23 °C and 50% RH show tensile strength of 30–45 MPa and elongation at break of 5–15% when measured according to ISO 527-3. After addition of 5–15 phr of acetyl tributyl citrate or dibutyl sebacate, elongation increases to 150–250% and tensile strength falls to 8–20 MPa. Blocking resistance is evaluated by stacking printed release sheets under 0.1 MPa at 40 °C for 48 h; grades with residual acetate above 2.0 mol% can show fiber pickup and blocking. Dry-film surface remains tack-free at 23 °C when plasticizer migration is controlled. Film haze measured by ISO 14782 is < 2% for clear overprint coats.
Compared with alcohol-soluble polyamide binders, PVB transfer-printing grades show lower moisture absorption at 50% RH and 23 °C, typically 1.5–2.5 wt% versus 4–6 wt% for polyamides. In ceramic decal transfer, PVB films leave lower ash residues after firing at 850 °C because ash specification is < 0.1 wt%. Against cellulose acetate butyrate, PVB provides stronger adhesion to glass and ceramic bisque after heat transfer but lower film hardness. PVB also tolerates wider ethanol/toluene blend ratios than CAB, which requires higher ester content for complete solubility. Unlike PVC/PVAc copolymer binders, PVB does not require epoxy or amino silane adhesion promoters on glass; adhesion to untreated polyethylene remains limited. Because PVB contains both hydrophobic butyral and hydrophilic hydroxyl groups, it acts as a compatibilizer for pigment wetting without requiring hyperdispersants below 5 wt% pigment loading. The presence of butyral rings reduces crystallinity and broadens solvent tolerance relative to unmodified polyvinyl alcohol.
| Property | PVB transfer grade | CAB binder | Alcohol-soluble polyamide | Test method |
|---|---|---|---|---|
| Glass transition temperature | 68–72 °C | 100–130 °C | 40–60 °C | ISO 11357-2:2020 |
| Water absorption at 50% RH, 23 °C | 1.5–2.5 wt% | 0.5–1.5 wt% | 4–6 wt% | ISO 62:2022 |
| Ash content | < 0.1 wt% | < 0.05 wt% | < 0.5 wt% | ISO 3451-1:2019 |
| Hydroxyl content | 18–22 mol% | < 1.5 wt% | high amide density | 1H NMR |
High-porosity ceramic bisque can absorb PVB solution before transfer, altering film thickness and leaving binder residues in pores. When bisque porosity exceeds 12%, a pre-wetting or basecoat sealer is often required to prevent loss of 30–50% of the ink solids into the substrate. In decal transfer, the printed PVB film is applied to bisque and fired. Absorption into pores can delay burnout and leave carbonaceous residue if the ramp through 350–500 °C is shorter than 30 min. Slow ramp of 2–3 K/min through the binder burnout zone prevents glaze pinholes. For bisque porosity above 15%, a low-viscosity grade diluted to 10–12 wt% solids is used as a pore sealer. For glass substrates, porosity is negligible so this failure mode is absent.
Storage moisture pickup and specification stability are process-critical. Multi-wall paper sacks with polyethylene liners stored below 30 °C and 60% RH maintain moisture pickup below 0.3 wt% over 6 months. If powder has been exposed above 60% RH, pre-drying at 60 °C for 2 h is required before dissolution. Moisture above 0.5 wt% extends solution clearing time and increases retained solvent in the dried film. Partially used sacks should be closed under nitrogen to prevent odor uptake and oxidation of residual unsaturation. Sealed bags do not require nitrogen storage, but partially opened bags should be consumed within 30 days.
Thermogravimetric analysis of neat PVB films at 10 K/min under nitrogen shows initial mass loss from residual moisture below 120 °C and a principal degradation onset between 180 °C and 200 °C. At transfer press temperatures above 200 °C, discoloration and acetic acid evolution from residual acetate become measurable. The ceramic firing cycle removes PVB at 350–500 °C before glaze vitrification. In decal production, a slow ramp of 2–3 K/min through this range prevents carbonaceous residues from becoming trapped in the glaze. Flash combustion after binder burnout is performed at 800–900 °C for glass; residual carbon is visible as gray haze if burnout is incomplete. The low ash value is necessary for defect-free glaze surfaces; metallic residues above 50 ppm can cause pinholing.
Regulatory status depends on final artwork transfer end use. RoHS 2011/65/EU Annex II heavy-metal limits apply after curing and require downstream formulation verification. For food-contact printed articles, the cured PVB film may need to comply with 21 CFR 175.300 or equivalent regional positive list; only food-grade plasticizers and solvents should be used. REACH registration is maintained for the polymer under the applicable polymer registration requirements; safety data sheets list residual butyraldehyde below 100 ppm and free formaldehyde below 20 ppm by high-performance liquid chromatography. Some solvent blends containing methyl ethyl ketone may require specific industrial hygiene controls under local VOC regulations.
Release force is measured on a tensile tester equipped with a 25 mm width sample and 180° peel geometry at 300 mm/min per ISO 8510-2. For silicone-coated polyester carriers, target release force for PVB transfer inks is 0.5–2.0 N/25 mm. Higher values produce fiber tear or image distortion; lower values can cause premature delamination during handling. Peel angle and speed are controlled because PVB release is rate-dependent; peel force at 500 mm/min can be 15–20% higher. When transfer occurs to curved ceramic or glass articles, a compressible silicone pad with Shore A hardness 60–70 is used to distribute pressure.
Transfer printing with PVB binder is used on ceramic decals, glass decorations, textile transfer papers, and coated plastics. The ink is printed on release-coated paper or polyester film, dried, optionally overprinted with a cover coat, then heat-transferred. In ceramic decal production, the PVB is burned out before glazing. For textile transfers, PVB is selected when cold-peel or warm-peel performance is specified; warm-peel grades with higher hydroxyl content are peeled at 40–60 °C while cold-peel grades require cooling below 35 °C. Multilayer decal systems use a clear PVB topcoat at 2–4 µm dry film thickness to protect the printed image from scratching. For ceramic decal with covercoat, total film thickness after drying is 8–12 µm; screen-print layers add 15–25 µm.
