| HS Code | 569141 |
| Chemical Name | Polyvinyl butyral (PVB) |
| Cas Number | 63148-65-2 |
| Physical Form | Granular powder |
| Appearance | White to slightly yellowish powder |
| Viscosity | 55 mPa·s (10 wt% solution in butanol) |
| Glass Transition Temperature | ~70 °C |
| Softening Point | ~60–70 °C |
| Density | 1.1 g/cm³ at 20 °C |
| Refractive Index | 1.49 |
| Hydroxyl Content | ~18–22 wt% |
| Butyral Content | ~70–75 wt% |
| Acetyl Content | ~1–3 wt% |
| Solubility | Soluble in alcohols, ketones, and esters; insoluble in water |
| Tensile Strength | ~40 MPa |
| Elongation At Break | ~80% |
As an accredited Mowital BA 55 HH factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Mowital BA 55 HH is packaged as free-flowing granules in 25 kg multi-ply paper bags with PE liner, palletized. |
| Container Loading (20′ FCL) | 20′ FCL: Mowital BA 55 HH loaded on pallets, secured and braced for safe transport. |
| Shipping | Mowital BA 55 HH is a polyvinyl butyral resin powder, shipped as non-hazardous cargo in sealed bags or drums. Protect from moisture and humidity, and keep in a cool, dry area. Standard road, sea, and air freight are suitable. Avoid excessive heat and damage to packaging during transport. |
| Storage | Store Mowital BA 55 HH in its original, tightly sealed container in a cool, dry, well-ventilated area away from direct sunlight, heat, and ignition sources. Protect from moisture and humidity to prevent caking or degradation. Keep containers upright and avoid prolonged storage above recommended temperatures. Follow label instructions and maintain proper inventory rotation to ensure product stability and performance. |
| Shelf Life | Mowital BA 55 HH has a shelf life of 12 months when stored unopened in a cool, dry place. |
Solvent-borne flexographic and gravure ink formulations demand a binding resin that builds low-shear viscosity during ink transfer and releases solvent quickly after drying. Mowital BA 55 HH, a high-molecular-weight polyvinyl butyral, is dissolved in ethanol/ethyl acetate blends at 40–50°C under high-shear agitation before being introduced at letdown. Resin addition typically ranges from 8 wt% to 15 wt% of total liquid ink, with the upper limit set by viscosity rise on high-volume anilox rolls. The acetal backbone provides adhesion to corona-treated polyethylene terephthalate and aluminum foil, while residual hydroxyl groups allow controlled compatibility with nitrocellulose and polyurethane co-binders. Viscosity is measured with ISO 2431:2019 cup 4 at 25°C; readings above 35 s may require dilution with n-propyl acetate or methoxypropanol to avoid misting and plate cylinder filling defects on press. Pigment dispersion is carried out separately on a bead mill or triple-roll mill; the PVB solution is added after the grind phase to prevent excessive shear heating from degrading the acetal linkage. Blocking resistance after printing is linked to residual solvent levels below 10 mg/m² in the printed OPP/PET laminate, measured by headspace gas chromatography according to internal packaging converter specifications. Lamination bond strength is tested after adhesive lamination by ASTM F88/F88M-23; substrate film failure rather than adhesive peel indicates that the ink film is structurally competent. For food packaging, compliance with Regulation (EC) No 1935/2004 and the EuPIA Good Manufacturing Practice guidelines is required; migration assessment must be performed on the finished printed article because the ink is only one layer in the laminate.
Process conflicts in this application include solvent imbalance during long press runs. Ethyl acetate ratios above 40 wt% of the solvent blend can lower ink viscosity but may also attack plate materials or cause premature drying in the anilox cells, whereas ethanol-rich blends above 60 wt% may reduce solubility of certain nitrocellulose grades. The high molecular weight of Mowital BA 55 HH contributes to dot sharpness at high printing speeds but also increases ink misting at press speeds above 400 m/min if viscosity is not adjusted. Terminal uses include retort pouches, snack food packaging, and overwrap films where ink must survive heat sealing and sterilization.
Mowital BA 55 HH serves as the film-forming binder in single-pack etch primers for cold-rolled steel, hot-dip galvanized steel, and aluminum. The resin is dissolved in a mixture of isopropanol and n-butanol before blending with 7–10 wt% phosphoric acid (85%), 5–8 wt% PVB solids, and 2–4 wt% chrome-free anticorrosive pigment based on zinc phosphate or calcium strontium phosphosilicate. Acid concentration is the critical process variable: above 12 wt% the acetal linkage undergoes progressive hydrolysis, causing viscosity drift, loss of film toughness, and poor intercoat adhesion after topcoating. Below 5 wt% adhesion to mill-scale steel drops below a cross-cut classification that can be accepted by automotive or structural steel specifications. Air spray or wire-wound drawdown applies a dry film thickness of 8–12 µm; heavier films above 15 µm can entrap solvent and cause blistering during force drying at 60–80°C. Adhesion is judged by ASTM D3359-23 method B on degreased panels; a rating of 5B is typical for CRS when the primer is used within 24 h of surface preparation. Neutral salt spray exposure according to ISO 9227:2022 for 500 h is used to assess scribe creep; values below 2 mm are expected only when the wash primer is followed by a compatible zinc phosphate or epoxy topcoat.
Compliance and formulation boundaries shift because chromium(VI) anticorrosive pigments historically used with PVB wash primers are restricted under REACH Annex XVII. Chrome-free variants require additional adhesion promoters or modified PVB grades; Mowital BA 55 HH can be used in chrome-free systems if the PVB solids are maintained above 6 wt% to retain film continuity over abraded steel edges. Surface preparation to ISO 8501-1 Sa 2½ is required for structural steel; for aluminum, chromate conversion coating is replaced by zirconium/titanium oxide treatments. Terminal products include metal furniture, switchgear cabinets, transformer housings, and structural steel sections where a thin pretreatment layer must provide temporary corrosion protection before topcoating.
Multilayer ceramic capacitor and LTCC tape production uses polyvinyl butyral binders with high green strength and clean burnout. Mowital BA 55 HH is dissolved in a methyl ethyl ketone/ethanol mixture at 8–12 wt% resin solids before addition to barium titanate or alumina slip. Binder concentration in the dried green tape is maintained between 8 wt% and 15 wt% of inorganic powder mass. Tape casting is performed through a doctor blade gap of 0.10–0.50 mm and casting speeds of 0.5–2.0 m/min; the wet film passes through a multi-zone dryer from 40°C to 80°C to avoid surface skinning. Green tape tensile strength is measured by ISO 527-3:2018; values below 2 MPa indicate insufficient binder or excessive plasticizer. The binder burnout profile is a two-stage process: heating to 350°C at 0.5–1.0°C/min, holding for 1–2 h, then heating to 550°C at 3°C/min. The acetal structure of Mowital BA 55 HH undergoes thermal decomposition before the inorganic sintering stage, but residual carbon can affect dielectric loss if oxygen flow through the kiln is inadequate. Compliance with RoHS Directive 2011/65/EU requires complete removal of the organic phase before component assembly; residual carbon is monitored by thermogravimetric analysis and is typically specified below 0.1% of sintered weight. Terminal products include multilayer ceramic capacitors, LTCC substrates, and alumina packages.
Slip rheology is controlled with polymeric dispersants at 0.5–1.5 wt% of powder mass; shear viscosity at 10 s⁻¹ is typically maintained between 2,000 mPa·s and 6,000 mPa·s when measured by ISO 3219:2013. Binder migration during drying can produce a resin-rich top surface and a binder-depleted bottom layer, causing camber after burnout; this is mitigated by reducing the upper-zone dryer temperature to below 60°C or increasing the ethanol fraction in the solvent blend. The main operational boundary is moisture pickup in the prepared slip, which can raise viscosity and destabilize the dispersion; closed mixing vessels and dry nitrogen blanketing are used when ambient relative humidity exceeds 60%.
Mowital BA 55 HH is incorporated into solvent-based heat-seal coatings for aluminum foil lidding stock and PVC/PET blister trays. The resin is combined with a polymeric plasticizer at 10–20 phr and a rosin ester tackifier at 5–10 phr; the mixture is applied by gravure cylinder to a dry coat weight of 3–6 g/m². Activation on packaging lines occurs at 120–160°C with dwell times of 0.8–1.5 s and jaw pressure of 2–4 bar. Below 110°C seal strength falls below 8 N/15 mm because insufficient polymer flow prevents wetting of the tray flange. Above 170°C, plasticizer migration to the seal interface can create ghosting on coated foil and reduced resealability. Seal strength is tested by ASTM F88/F88M-23; acceptable lidding seal for dairy cups is typically 10–18 N/15 mm. For food-contact compliance, formal status must be evaluated under FDA 21 CFR 175.105 for adhesives and 21 CFR 175.300 for resinous coatings; EU Regulation (EU) No 10/2011 requires migration testing of the complete lidding system. Terminal products include dairy lidding, condiment portion cups, and pharmaceutical blister pack overcaps.
Coating viscosity at application temperature is monitored by a falling-ball viscometer or ISO 2884-1:2013 rotational viscometer; a reduction in solids below 15 wt% can produce coat weight variations exceeding ±0.5 g/m², which directly alters seal initiation temperature. The main processing conflict is balancing PVB molecular weight against coat weight: high-molecular-weight Mowital BA 55 HH generates stronger heat seals but requires slower gravure coating speeds or higher solvent release in the drying oven. Residual solvent above 20 mg/m² in the coated foil can cause blistering during heat sealing and off-odours in dairy applications. Package integrity after sealing is evaluated by vacuum leak testing per ASTM D3078-13 at −40 kPa; pinholes smaller than 25 µm are detected by dye penetration.
| Application area | Standard or directive | Monitored parameter |
|---|---|---|
| Flexographic/gravure lamination ink | ASTM F88/F88M-23 | Seal strength after lamination |
| Wash primer on CRS | ASTM D3359-23 method B | Cross-cut classification |
| Wash primer corrosion | ISO 9227:2022 | Scribe creep in mm after 500 h |
| Ceramic green tape | ISO 527-3:2018 | Green tape tensile strength MPa |
| Heat-seal lidding | ASTM F88/F88M-23 | Seal strength N/15 mm |
A high-viscosity masking lacquer is prepared by dissolving Mowital BA 55 HH in ethanol or denatured alcohol. The solution is applied by spray or dip to a dry film thickness of 25–60 µm on aluminum, titanium, or glass. Coated parts are force-dried at 50–60°C for 30 min to produce a pinhole-free barrier. The maskant resists ferric chloride etchants and hydrofluoric acid glass etchants but remains removable with anhydrous ethanol or ethyl acetate after processing. Adhesion is balanced to prevent undercutting at the maskant-substrate interface; crosshatch adhesion per ASTM D3359-23 method B typically falls between 3B and 5B depending on substrate roughness. The film must be free of pinholes; inspection under ultraviolet light is used to detect voids before immersion. Terminal products are chemically milled aircraft skin panels, etched glass decorative panels, and precision titanium components. VOC emissions from solvent-borne maskants are governed by Directive 2010/75/EU; solvent recovery or abatement is required in continuous production. Published data for this specific maskant configuration is limited, but industrial use of PVB-based maskants is established in precision etching.
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Kuraray Europe GmbH supplies Mowital BA 55 HH as a pelletized polyvinyl butyral resin obtained by acid-catalysed condensation of polyvinyl alcohol with n-butyraldehyde. The BA 55 HH suffix places the grade in the high-molecular-weight, high-hydroxyl segment of the Mowital PVB range; the HH designation indicates a residual polyvinyl alcohol equivalent above 20 wt% when measured by saponification number according to DIN 53401 or ISO 3681. The resin is directed toward solvent-borne structural adhesives, anti-corrosive wash primers, ceramic green-sheet binders and heat-sealing lacquers in which elevated hydroxyl functionality contributes to polar adhesion, hydrogen bonding and thermoset crosslinking. Because release properties are governed by lot-specific certificates of analysis, the numerical ranges in this document are presented as class-typical screening data for high-hydroxyl PVB of comparable molecular weight, not as product release limits; published product-specific values for this exact configuration are limited and must be verified against the supplier technical data sheet.
| Property | Test method | Typical range |
|---|---|---|
| Residual polyvinyl alcohol equivalent | DIN 53401 / ISO 3681 | 20–24 wt% |
| Density | ISO 1183-1:2019 | 1.08–1.12 g/cm³ |
| Glass transition | ASTM D3418-21 | 68–74 °C |
| Melt flow rate | ISO 1133-1:2022, 21.6 kg, 190 °C | 2–8 g/10 min |
| Tensile yield strength | ISO 527-1:2019 | 24–36 MPa |
| Elongation at break | ISO 527-1:2019 | 60–150 % |
The qualification of Mowital BA 55 HH in regulated applications requires documentary verification as well as physical testing. The matrix below lists the core dimensions; the resin supplier safety data sheet should be checked for the actual REACH registration number and any revision.
| Dimension | Reference standard or regulation | Verification focus |
|---|---|---|
| EU registration | EC 1907/2006 (REACH) | SDS, registration number, SVHC status |
| RoHS restricted substances | IEC 62321 series | Pb, Cd, Hg, Cr(VI), PBB, PBDE |
| Indirect food contact adhesive | FDA 21 CFR 175.105 or FDA 21 CFR 175.300 | Formulation-specific migration testing |
| Melt viscosity | ISO 1133-1:2022 | MFR at 21.6 kg, 190 °C |
| Tensile properties | ISO 527-1:2019, ISO 527-2:2012 | Injection-moulded type 5A specimens |
Residual hydroxyl groups in high-hydroxyl PVB function as both hydrogen-bond donors and acceptors for polar solvents such as ethanol, isopropanol and ethyl acetate. This thermodynamic affinity increases solvent retention after forced-air drying. Gravimetric or gas-chromatographic determination of residual solvent is performed according to ASTM D5403-93 or DIN EN ISO 11890-2:2020. In a rotogravure coating trial on aluminium foil at a dry coat weight of 4–6 g/m², a high-hydroxyl PVB lacquer dried at 60 °C can retain residual ethanol above 1.5 wt% when the line speed exceeds the drying section capacity. Because the higher hydrogen-bond density also restricts chain interdiffusion between coated layers during lamination, peel strength after 24 h aging should be determined to ISO 11339:2022; a decrease relative to immediate peel indicates incomplete interphase formation.
In solution preparation, the resin is dispersed in an ethanol/ethyl acetate mixture with a high-shear dissolver equipped with a diameter-to-vessel ratio of 0.3–0.5. Swelling occurs at 25 °C, and dissolution proceeds at 40–50 °C to form a clear to slightly hazy lacquer at 20–30 wt% solids. Viscosity is measured by DIN 53015 or ISO 12058-1 at 20 °C; a 20 wt% solids solution in 85:15 ethanol/ethyl acetate typically exhibits a dynamic viscosity above 50 mPa·s for high-molecular-weight HH grades. Relative to standard H grades, the higher solution viscosity forces either a reduction in solids of 2–5 percentage points or an increase in co-solvent content to match application viscosity. Filtration through a 60–100 µm bag filter is recommended before gravure or slot-die coating to remove gel specks.
The principal differentiation from adjacent Mowital PVB types is expressed in hydroxyl equivalent, solution viscosity and moisture interaction. Standard H grades with lower hydroxyl content dissolve more readily in ester-rich blends and show lower melt viscosity at equivalent temperature; HH grades require stronger polar solvent fractions and provide a denser crosslinkable network. High-molecular-weight HH grades of the BA 55 HH type additionally show higher low-shear viscosity and may require a reduction in coating solids of 2–5 percentage points to match the rheology of a lower-molecular-weight grade at the same line speed. These differences are quantified by solution viscosity per ISO 12058-1 and by melt flow rate per ISO 1133-1:2022.
Thermogravimetric analysis according to ASTM E1131 at 10 °C/min under nitrogen shows that high-hydroxyl PVB begins mass loss near 200 °C through water elimination from neighbouring hydroxyl pairs in the presence of residual acid catalyst. Isothermal processing above 180 °C accelerates acetal hydrolysis and liberates n-butyraldehyde, producing yellowing and melt-viscosity drift. When BA 55 HH is melt-compounded into a masterbatch or extruded primer feedstock, a co-rotating twin-screw extruder with an L/D 44:1 configuration and a barrel profile of 120–170 °C is used; the die is limited to 170 °C and residence time is held below 120 s. Melt pressure at a screw speed of 200–300 rpm is monitored against the grade-specific viscosity curve. Pre-drying at 40–45 °C for 4–8 h is required after storage above 60 % RH because absorbed water hydrolyzes acetal rings during extrusion and forms bubbles at the die.
Thermal degradation products can be followed by headspace gas chromatography according to ISO 16000-6:2021 or by thermal desorption–GC/MS. A processing window wider than ±5 °C is difficult to sustain because melt viscosity falls sharply with temperature while degradation kinetics accelerate. This is the critical process conflict for BA 55 HH in melt applications: the temperature needed to lower melt viscosity approaches the degradation threshold, so screw design must minimize shear heating and the melt temperature must be measured with an infrared probe at the die exit.
Ceramic green-sheet tape casting uses the high-hydroxyl PVB as a binder phase in a slurry containing 55–65 wt% solids and 4–8 wt% BA 55 HH on dry powder. A doctor-blade gap of 150–300 µm on a polyester carrier at 0.5–2.0 m/min produces green tape that is laminated at 70–85 °C and 10–20 MPa. Green density after lamination is measured by Archimedes immersion according to ISO 18754:2013 and typically falls between 55 % and 60 % of theoretical density. The high hydroxyl content improves adsorption onto oxide powders and reduces particle segregation during drying; however, the same functionality increases moisture uptake, and green tape should be handled below 50 % RH until binder burnout. Binder burnout is usually conducted at 2–5 °C/min to 450–550 °C in air, because rapid decomposition above 10 °C/min can create internal microcracks.
Where BA 55 HH is used as a binder for screen-printing pastes, carbon black and silver flake are dispersed on a three-roll mill with a gap of 20–50 µm. The high hydroxyl content stabilizes polar pigment surfaces; mill paste viscosity is controlled to 15–40 Pa·s at 10 s⁻¹ and measured by cone-and-plate rheometry per ISO 3219:1993. Paste batch-to-batch viscosity drift is controlled by measuring the hydroxyl equivalent of each PVB lot before formulation. This incoming-lot measurement prevents variability in screen-print deposit thickness when the same mesh and squeegee settings are used.
For anti-corrosive wash primers, Mowital BA 55 HH is combined with phosphoric acid and zinc phosphate or zinc tetroxychromate pigments. The PVB content is typically 8–12 wt% of the wet formulation. Corrosion resistance and adhesion are evaluated on degreased cold-rolled steel after 500 h salt spray per ISO 9227:2022 and cross-cut adhesion per ISO 2409:2020. High hydroxyl functionality forms acid-base interactions with metal oxides and hydrolyzes slowly in the acidic medium; the pH of the liquid primer must remain above 3 to limit uncontrolled acetal hydrolysis. In structural adhesive formulations, 10–15 wt% phenolic resole or 5–8 wt% aliphatic isocyanate trimer on PVB solids is used; lap-shear specimens prepared from degreased aluminium are tested according to ISO 4587:2003 after conditioning at 23 °C and 50 % RH for 7 days.
Heat-sealing lacquers formulated with high-hydroxyl PVB show a higher minimum seal-initiation temperature than standard H grades because hydroxyl groups restrict segmental motion until sealing pressure and temperature drive the film into the flow regime. A coated aluminium foil with 4–6 g/m² dry PVB is sealed at a jaw temperature of 120–150 °C, a pressure of 0.3 N/mm² and a dwell of 0.5–1.0 s. Seal strength is reported according to ASTM F88/F88M-21 after conditioning at 23 °C and 50 % RH for 24 h. Compared with a standard high-molecular-weight H grade, the high-hydroxyl BA 55 HH typically shows a 5–10 °C upward shift in heat-seal initiation and improved blocking resistance at 40 °C; the trade-off is higher moisture absorption above 70 % RH, which reduces seal strength and may require re-drying of the coated reel before slitting. This operational limitation must be integrated into winding and slitting schedules when replacing a lower-hydroxyl grade.
