| HS Code | 412460 |
| Product Name | Low Viscosity PVB Resin LV-3/LV-5 |
| Appearance | White free-flowing powder |
| Lv 3 Viscosity | 20-40 mPa·s (10% ethanol solution, 20°C) |
| Lv 5 Viscosity | 40-60 mPa·s (10% ethanol solution, 20°C) |
| Molecular Weight | 30000-50000 g/mol |
| Butyral Content | 70-80% |
| Hydroxyl Content | 18-23% |
| Acetyl Content | 0.5-3% |
| Glass Transition Temperature | 60-70°C |
| Softening Point | 100-120°C |
| Density | 1.08-1.12 g/cm³ |
| Tensile Strength | 30-45 MPa |
| Elongation At Break | 40-80% |
| Solubility | Soluble in alcohols, esters, ketones, glycol ethers; insoluble in water |
As an accredited Low Viscosity PVB Resin LV-3/LV-5 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Low Viscosity PVB Resin LV-3/LV-5 is packaged in 200 kg drums with moisture-proof lining. |
| Container Loading (20′ FCL) | Low Viscosity PVB Resin LV-3/LV-5 loaded in 20′ FCL, palletized, secured, labeled, ventilated for safe chemical transport. |
| Shipping | Shipping: Low Viscosity PVB Resin LV-3/LV-5 is packed in moisture-proof sealed bags or drums, then shipped via dry containers or covered trucks. Keep dry, ventilated, and away from heat, sparks, and direct sunlight. Handle gently to prevent bag damage. Transport complies with standard non-hazardous chemical regulations. |
| Storage | Store Low Viscosity PVB Resin LV-3/LV-5 in a cool, dry, well-ventilated area away from direct sunlight, heat sources, and ignition. Keep containers tightly sealed to prevent moisture absorption and contamination. Maintain temperatures between 5–30°C. Under proper conditions, shelf life is typically 12 months from manufacture. Avoid open flames. |
| Shelf Life | Shelf life is typically 12 months when stored in a cool, dry place in original sealed packaging. |
Two-component etch primers for cold-rolled steel, galvanized coil, and aluminium dissolve low-viscosity PVB in the base component at 9–12 wt% with a mixed alcohol solvent. The acid component is diluted phosphoric acid at 3–5 wt% of total mixed primer. After mixing at a 4:1 base-to-acid volume ratio, the working fluid is sprayed through HVLP equipment with nozzle diameters of 1.2–1.4 mm and air cap pressure of 0.2–0.35 MPa. Dry film thickness is held at 8–12 µm. Above 15 µm, cohesive failure within the primer reduces cross-cut adhesion and salt-spray resistance. Spray viscosity at 25 °C is typically 18–25 s on a Zahn #2 cup, and the material is applied in a single cross-coat pass to avoid acid etching of previously deposited film.
Pot life is controlled by continuous reaction of acid with metal and by progressive neutralization of the acidic component. At 25 °C, viscosity remains sprayable for 6–8 h; above 30 °C, the same formulation gels within 2–3 h because phosphate reaction products aggregate more rapidly. High relative humidity above 65% further shortens pot life because moisture accelerates partial hydrolysis of ester-containing co-solvents, shifting pH downward. Field practice is to chill the mixed primer to 18–20 °C in pressure pots and to consume the batch within one working shift. Mixing equipment with static in-line mixers rather than high-speed dispersers is preferred because shear-induced temperature rise in a 5 L disperser can reduce pot life by 30–40%.
Adhesion and corrosion performance are assessed by ASTM D3359-17 method B and ASTM B117-19. On grit-blasted cold-rolled steel, a properly applied wash primer achieves 5B cross-cut adhesion and less than 2.0 mm scribe creep after 500 h neutral salt spray. On smooth aluminium, adhesion drops to 3B–4B unless a chromate-free conversion coating or phosphoric acid surface etch precedes priming. Chromium-based inhibitors such as zinc chromate are effective but are subject to authorization under REACH Annex XIV. Current formulations replace them with zinc phosphate or calcium strontium phosphosilicate at 5–8 wt% on total base component, with a measurable early scribe creep trade-off of approximately 1.0–2.5 mm after 500 h salt spray on zinc-galvanized substrates.
In solvent-based flexographic and gravure lamination inks, low-viscosity PVB grades LV-3 and LV-5 are incorporated at 8–15 wt% of total formula to raise binder solids while holding efflux time below 24 s on an ISO 2431:2019 4 mm cup. The binder is predissolved in an 80:20 w/w ethanol/ethyl acetate blend to 20–25 wt% solids before addition to the dispersion base. Low molar mass shifts high-shear dispersion viscosity, measured on a cone-and-plate rheometer at 10 000 s⁻¹, into a range that permits bead milling without excessive heat build-up. Chamber exit temperature is controlled below 55 °C because viscosity drift and colour shift become measurable on a 10 L horizontal bead mill charged with 0.6–0.8 mm zirconia beads when residence time exceeds 45 min per pass. The resin phase is not the primary dispersant; phosphate ester or high-molecular-weight polyurethane dispersants are still required at 2–5 wt% on pigment.
PVB functions simultaneously as film former and adhesion promoter to corona-treated biaxially oriented polypropylene and polyethylene terephthalate. Wetting is achieved when substrate surface energy is kept above 38 mN/m; dyne depletion below this threshold produces pinholing and tape delamination. Lamination bond strength after conversion with solventless polyurethane adhesive is evaluated by ASTM D1876-08(2015) T-peel. Typical values for 12 µm PET-based structures range from 2.0 N/15 mm to 4.5 N/15 mm depending on ink coverage and adhesive coat weight. Block resistance of printed reels is screened under 0.15 MPa at 40 °C for 24 h per ASTM D2793; blocking defects occur when the binder fraction exceeds 15 wt% or when residual solvent lifts the film surface above 40 °C under winding tension.
Retained solvent remains the primary process conflict. The residual hydroxyl fraction in PVB binds ethanol and isopropanol through hydrogen bonding; solvent release in high-speed printing is governed by dryer air temperature, web speed, and exhaust humidity. Headspace gas chromatography after lamination per ASTM F1884-04 should show total retained solvents below 150 mg/m². Above this threshold, delamination and reverse-side odour defects appear after 48–72 h ageing at 40 °C. This is a known bottleneck on gravure lines above 250 m/min; slow solvents are partially replaced by ethyl acetate or methyl ethyl ketone to maintain release without destabilizing pigment dispersion.
Non-aqueous tape casting slurries for barium titanate multilayer ceramic capacitors use low-viscosity PVB LV-5 because it permits ceramic solids loading of 58–65 wt% while maintaining slurry viscosity at 1 500–3 000 mPa·s on a Brookfield RV spindle at 20 rpm. The solvent blend is commonly toluene/ethanol 60:40 w/w. The slurry is milled in a ball mill with 5 mm zirconia media for 16–24 h, then de-aired under vacuum at 50–100 mbar absolute. A typical formulation is shown below.
| Component | Function | Mass fraction (wt%) |
|---|---|---|
| Barium titanate powder | Dielectric filler | 58–65 |
| Toluene/ethanol 60:40 w/w | Solvent system | 25–32 |
| PVB LV-5 | Binder | 4–7 |
| Benzoate ester plasticizer | Green flexibility | 2–4 |
| Phosphate ester dispersant | Particle dispersion | 1–2 |
Tape casting occurs through a doctor blade gap of 100–300 µm at carrier speeds of 0.5–2.0 m/min. Drying is staged: first zone 40 °C, second zone 50 °C, final zone 60 °C. Low-viscosity PVB increases green tape density because higher solids loading narrows interparticle voids, but it reduces green tensile strength relative to higher-molecular-weight PVB grades. This creates a processing window: binder below 3.5 wt% produces edge chipping during blanking, while binder above 7 wt% lengthens debinding and increases carbon residue risk. Green tape tensile properties are measured on 75 µm dried tape using ISO 527-3:2018; fracture strain below 2% typically indicates premature binder migration to the tape surface during forced air drying.
Debinding behaviour is evaluated by thermogravimetric analysis at 5 °C/min to 600 °C under air per ASTM E1131. PVB degradation onset is observed near 220 °C and the main weight-loss event occurs between 350 °C and 400 °C. Ash content after 600 °C should remain below 0.2 wt% for capacitor-grade tape. Above this limit, residual carbon shifts dielectric loss tangent. The debinding profile must include a hold at 350–400 °C for 60–120 min to avoid blistering from rapid volatilisation. Furnace exhaust flow is set to 6–10 air changes/h because unburned organic decomposition products condense in cold trap zones and can drip onto ware surfaces during later sintering.
Applied at 2.5–4.0 g/m² dry coat weight to bright-side aluminium foil, low-viscosity PVB heat seal lacquers are gravure-coated from 20–30 wt% solids solutions in ethanol or ethanol/methyl ethyl ketone blends. The low solution viscosity at 25 °C, typically 40–120 mPa·s at 20 wt%, allows a gravure cylinder with cell volume 8–12 cm³/m² to lay a uniform film at 150–250 m/min without streaking. Foil surface tension is maintained above 36 mN/m before coating; otherwise, the wet film dewets on release-contaminated material. Coating room relative humidity is controlled below 60% to prevent moisture blush during solvent evaporation.
Seal initiation temperatures for PVC/PVDC blister lidding fall between 160 °C and 180 °C with a jaw dwell of 0.8–1.0 s and pressure of 0.3 MPa. Peel strength per ASTM F88/F88M-21 is specified at 5–10 N/15 mm; values below the lower bound indicate undertransferred PVB, while values above 12 N/15 mm can tear the lidding rather than peel. Blocking resistance is evaluated at 40 °C and 70% RH for 24 h under 0.1 MPa. Addition of 0.3–0.6 wt% erucamide or amide wax on total dry film prevents reel blocking, but excessive slip lowers seal strength by more than 20%. Food-contact status must be confirmed for the specific lacquer formulation; the resin alone does not confer approval.
When low-viscosity PVB replaces 20–30 wt% of nitrocellulose in alcohol-borne sanding sealers, spray viscosity measured by ASTM D1200-22 Ford cup #4 is held at 18–22 s while total binder solids increase from 9 wt% to 12 wt%. The resin is dissolved in anhydrous isopropanol/n-butanol blends to avoid whitening at relative humidity above 60%. On oak and maple panels, cross-hatch adhesion by ASTM D3359-17 remains at 5B after 24 h ambient cure, and the PVB-modified film sands to a fine dust without clogging P240 stearated paper. The formulation is applied on flat-line spray equipment with 1.2 mm air-atomising nozzles and flash-off between coats of 5–10 min at 25 °C.
The main compatibility boundary is with high-acid-number alkyds and some acid-catalysed urea-formaldehyde topcoats. PVB can interact with amine-based additives or remain soft under two-component polyurethane topcoats if the sealer is not fully cured. Published data for long-term recoat adhesion over PVB-modified sealers in exterior joinery is limited. Accelerated testing under ASTM D4587-11 UV-A cyclic exposure for 500 h shows acceptable intercoat adhesion only when the topcoat is applied within 48 h and the sealer is sanded to remove surface release.
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Low Viscosity PVB Resin LV-3/LV-5 consists of two polyvinyl butyral grades within the low-viscosity class of terpolymers of vinyl butyral, vinyl alcohol, and vinyl acetate. The product is supplied as free-flowing white granules or powder and is used in solventborne coatings, printing inks, ceramic green tapes, heat-seal coatings, and adhesion-promoting primers where high application solids and low solution viscosity are required. Polyvinyl butyral is produced by acid-catalyzed acetalization of polyvinyl alcohol with n-butyraldehyde; the resulting polymer retains a controlled distribution of hydroxyl groups that participates in hydrogen bonding with glass, aluminum oxide, steel oxides, and polar pigments. The LV-3 and LV-5 designations refer to differentiated molecular-weight and solution-viscosity profiles within the low-viscosity segment, not to different backbone chemistries. In practice, LV-3 is the lower-viscosity grade, while LV-5 provides higher molecular weight and greater film cohesion at a moderate viscosity penalty. Both grades are soluble in lower alcohols, esters, ketones, and glycol ethers, and are insoluble in water and aliphatic hydrocarbons.
The low-viscosity classification is operationally defined by Brookfield rotational viscosity measured at 25 °C on a 10 wt% solution in a 95:5 ethanol/toluene mixture. Published technical data for low-viscosity PVB indicates LV-3 typically falls between 25 mPa·s and 40 mPa·s; LV-5 typically falls between 60 mPa·s and 90 mPa·s. Medium-viscosity PVB grades used in safety-glass interlayers and high-toughness coatings generally exceed 100 mPa·s under the same conditions. The lower degree of polymerization in LV-3 and LV-5 shortens chain relaxation time, reduces extensional viscosity in high-speed coating heads, and permits faster solvent diffusion from the wet film. A rotogravure ink formulated to an application viscosity of 18–22 s in a DIN 4 mm cup can be produced at higher solids with LV-3 than with a medium-viscosity PVB, which generally reduces retained solvent in a given drying tunnel, although the extent depends on solvent blend, film weight, air impingement, and co-binder architecture. The lower solution viscosity also reduces misting and cobwebbing on chambered doctor blade units. However, low-viscosity grades do not generate the same chain entanglement as medium- and high-viscosity PVB, so formulations requiring high film toughness, block resistance, or low-temperature flexibility may need a high-molecular-weight co-binder.
LV-3 and LV-5 differ primarily in weight-average molecular weight, solution viscosity, and residual hydroxyl content. LV-3 is the lower molecular weight grade and permits higher solids at equal application viscosity; LV-5 provides higher cohesive strength and better pigment wetting stability under extensional shear and after solvent dilution. The higher hydroxyl content of LV-5 increases hydrogen-bond density and adhesion to metal oxides and glass, but it also increases moisture sensitivity and can raise solution viscosity in alcohol-rich systems. Under capillary shear in flexographic anilox cells, LV-3 permits faster cell emptying and higher press speeds; LV-5 retains more film structure on non-porous substrates and shows lower separation in alcohol-rich diluents. Table I summarizes representative analytical ranges compiled from low-viscosity PVB technical literature. Lot-specific certificates of analysis must be used for production release.
Table I. Representative analytical profiles for LV-3 and LV-5.
| Property | LV-3 typical range | LV-5 typical range | Test method |
|---|---|---|---|
| Volatile matter | ≤ 0.5 wt% | ≤ 0.5 wt% | ISO 3251 |
| Solution viscosity | 25–40 mPa·s | 60–90 mPa·s | ISO 2555 |
| Weight-average molecular weight | 28,000–36,000 g/mol | 48,000–62,000 g/mol | DIN 55672 |
| Polyvinyl alcohol content | 11–13 mol% | 13–16 mol% | ASTM D1396 |
| Polyvinyl acetate content | 1.0–2.5 mol% | 1.0–2.5 mol% | ASTM D1396 |
| Vinyl butyral content | 78–82 mol% | 76–80 mol% | ASTM D1396 |
| Glass transition temperature | 63–67 °C | 66–70 °C | ISO 11357-2 |
| Acid number | ≤ 1.0 mg KOH/g | ≤ 1.0 mg KOH/g | ISO 2114 |
When formulated into non-aqueous tape-casting slips for alumina or barium titanate substrates, LV-3 and LV-5 act as the primary binder phase because their low solution viscosity permits slurry solids loadings above 65 wt% without exceeding a tape-casting viscosity of 2,000–4,000 mPa·s at 25 °C. The binder is dissolved in an ethanol/toluene or ethanol/MEK system with dibutyl phthalate or dioctyl adipate as plasticizer. After casting onto polyethylene terephthalate carrier film, the wet tape is dried with forced air at 50–70 °C. Low molecular weight in LV-3 accelerates solvent diffusion and reduces residual solvent in the green tape, which is critical for avoiding delamination during multilayer lamination at 10–30 MPa and 60–80 °C. Binder burnout in air reaches complete oxidation above 450 °C; heating rates between 1–3 °C/min are normally required to prevent cracking and carbon residue. LV-5 is preferred when green tape requires higher tensile strength for automated handling; LV-3 is preferred when high solids and low drying shrinkage are the dominant constraints. The resin must be pre-dried when storage relative humidity exceeds 60% because absorbed moisture alters slurry rheology and can generate bubbles during vacuum de-airing.
In a high-solids rotogravure ink for surface-printed polypropylene or polyester, the replacement of a medium-viscosity PVB with LV-3 shifts the solids-viscosity curve toward higher solids at constant press viscosity. A mill-base dispersion produced on a bead mill or three-roll mill with pigment-to-binder ratios between 4:1 and 6:1 can be reduced with ethanol/ethyl acetate while maintaining viscosity below 25 s in a DIN 4 mm cup. The lower molecular weight of LV-3 reduces chain entanglement and yields a shorter Newtonian plateau; this can improve pigment wetting and lower yield stress, but it also reduces low-shear viscosity that prevents settling. Consequently, formulations may require an anti-settling rheology modifier at addition rates of 0.2–0.5 wt% on total liquid ink. On a gravure cylinder with 60–80 lines/cm and an engraved cell depth of 28–35 µm, the low-viscosity binder improves cell emptying and supports higher line speeds, although actual press speed is set by drying tunnel capacity and substrate heat distortion. Compared to LV-5, LV-3 gives lower retained solvent but less film toughness and lower heat-seal strength; compared to medium-viscosity PVB grades, LV-3 and LV-5 improve film clarity on treated films and reduce solvent retention at a given film weight.
Solvent compatibility is broad with alcohols, esters, ketones, and glycol ethers; aliphatic hydrocarbons are non-solvents and can be used as diluents up to 20–30% depending on the blend and resin content. In heat-seal lacquers for aluminum foil, LV-3 is dissolved in ethanol/ethyl acetate at 15–25 wt% and coated at 2–4 g/m² with a gravure coater. Heat-seal activation occurs at 110–130 °C under 0.2–0.4 MPa jaw pressure for 1–2 s. The low-viscosity grade reduces foaming in the coating pan and permits faster line speeds without roping. Compared to higher-viscosity PVB, LV-3 yields lower seal strength but better wetting of primerless foil; LV-5 provides intermediate sealing performance for lidding films.
Polyvinyl butyral resins are commonly referenced in food-contact coating regulations. LV-3/LV-5 is typically evaluated against 21 CFR 175.300 for resinous and polymeric coatings used in contact with food, subject to extraction limits for the specific food type and coating weight. End-use compliance requires testing of the finished coating under conditions of use. Under European Union chemicals legislation, the product is subject to registration under REACH (EC) No 1907/2006; the safety data sheet provides registration status and exposure scenarios. RoHS compliance for electrical and electronic equipment applications is generally evaluated under Directive 2011/65/EU and its delegated amendments for lead, cadmium, mercury, hexavalent chromium, and brominated flame retardants. The resin is not intentionally doped with heavy-metal stabilizers; lot-specific certificates of analysis should be requested when compliance data are required.
Table II. Regulatory assessment domains.
| Regulatory domain | Reference | Typical assessment |
|---|---|---|
| US food-contact coatings | 21 CFR 175.300 | Finished coating extraction; compliance depends on final formulation and food type |
| EU chemicals regulation | REACH (EC) No 1907/2006 | Safety data sheet exposure scenario and registration status apply |
| EU RoHS | Directive 2011/65/EU | Heavy metal content below RoHS limits in homogeneous material |
| VOC emissions from paints | Directive 2004/42/CE | Applicable to finished coating formulation, not resin alone |
In two-component wash primers for cold-rolled steel and aluminum, the function of LV-3 or LV-5 is to form a thin adhesion-promoting film after phosphoric acid etching of the metal surface. The resin is dissolved in isopropanol, n-butanol, or ethanol/toluene at 5–10 wt% solids; a separate acid component containing phosphoric acid at 10–20 wt% of the total primer is added before spray application. The pot life of the mixed primer is governed by acid-catalyzed transacetalization and can be limited to 8–12 h, depending on temperature and water content. Low-viscosity PVB permits atomization through conventional HVLP spray guns with a fluid nozzle of 1.3–1.5 mm and air cap pressure of 0.15–0.25 MPa. The dried film at 5–10 µm dry film thickness provides a polar hydroxyl-bearing interface for subsequent epoxy or polyurethane primer layers. LV-5 is selected where higher film strength and solvent resistance are needed; LV-3 is selected when wetting of zinc-coated or aluminum surfaces is difficult because it allows lower application solids without viscosity instability. The product should not be combined with amine-based additives or amine-cured epoxy co-binders in the same liquid phase, because basic amines accelerate PVB hydrolysis and can cause viscosity drift. Storage should be below 30 °C in closed containers; opened packages should be re-sealed under dry conditions.
