| HS Code | 666336 |
| Chemical Name | Polyvinyl Alcohol |
| Appearance | White or slightly yellow granular powder |
| Solubility | Soluble in water, especially in hot water |
| Degree Of Hydrolysis | 88% (partially hydrolyzed grade for paint applications) |
| Viscosity 4 Solution At 20 C | 5-50 mPa·s depending on grade |
| Ph 4 Aqueous Solution | 5.0-8.0 |
| Film Formation | Excellent film-forming ability with clear, smooth films |
| Adhesion | Good adhesion to interior wall substrates and pigments |
| Protective Colloid Effect | Stabilizes emulsion paints and prevents pigment settling |
| Re Dispersibility | Easily re-dispersible in water for uniform paint mixing |
| Particle Size | Typically 20-200 mesh |
| Ash Content | ≤ 0.5% |
As an accredited Polyvinyl Alcohol (PVA) for Interior Wall Paints factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 25 kg multi-layer paper bags with moisture-proof lining, designed for safe storage and easy handling in paint production. |
| Container Loading (20′ FCL) | 20′ FCL: 20 metric tons of PVA packed in 25 kg bags, palletized and shrink-wrapped for interior wall paint use. |
| Shipping | Ship Polyvinyl Alcohol in sealed, moisture-proof bags or drums, palletized and wrapped. Protect from humidity, heat, and contamination. Avoid dust generation and ignition sources. Ensure proper labeling and ventilation during transport. Keep upright, secured, and away from incompatible materials. Follow local chemical shipping regulations for safe delivery. |
| Storage | Store Polyvinyl Alcohol (PVA) in a cool, dry, well-ventilated area, away from direct sunlight, heat, and ignition sources. Keep containers tightly sealed to prevent moisture absorption, as PVA is hygroscopic. Avoid contact with oxidizing agents. Use within 12 months of receipt under proper storage conditions to maintain quality. |
| Shelf Life | Shelf life: 12 months when stored sealed in a cool, dry place, away from direct sunlight and extreme temperatures. |
Interior wall paints formulated above the critical pigment volume concentration (CPVC) frequently develop shear-thinning deficiencies and pigment settling within 48 hours of manufacture. Introducing a pre-dissolved polyvinyl alcohol grade with a degree of hydrolysis of 88 mol% and a 4% aqueous solution viscosity between 20 and 25 mPa·s at 20 °C (determined by Brookfield LV DV‑II+ spindle 2 at 60 rpm) alters the rheological profile from a flat Newtonian plateau to a pronounced pseudoplastic curve exhibiting a yield value exceeding 0.8 Pa. The PVA solution—prepared separately in a jacketed dissolution tank at 90–95 °C under low-shear agitation for no less than 40 minutes to erase gel nuclei—is post-added to the pigment grind after letdown, typically at 0.15–0.40 wt% of the liquid paint weight. Process staging is critical: early addition during high-speed dispersion at tip speeds above 18 m/s entrains micro-foam that is not eliminated by standard silicone defoamers, while late addition after thickener hydration causes local gellation pockets and a visible “cottage cheese” surface defect on drawdowns applied to Leneta charts. The terminal application is a flat-to-satin interior decorative coating compliant with GB/T 9756-2018 requirements for in-can stability (no visible syneresis after 28 days at 50 °C) and scrub resistance exceeding 150 cycles per ISO 11998 when blended with a styrene-acrylic primary emulsion. Equipment on production lines often includes a swept-surface heat exchanger on the PVA cook tank to maintain accuracy of ±1.5 °C; deviation beyond this window accelerates transesterification of residual acetate groups in partially hydrolyzed grades, gradually reducing viscosity contribution batch-to-batch.
In dry-mix interior skim coats targeting the Middle East and South Asian markets, where ambient mixing water temperatures routinely reach 35–40 °C in summer months, fully hydrolyzed PVA powder (98.0–98.8 mol% hydrolysis, particle size D90 < 75 µm) is dry-blended with white Portland cement, double-refined calcium carbonate (300–400 mesh), and a cellulose ether of 40,000–60,000 mPa·s Brookfield viscosity. The PVA addition rate sits in a narrow process corridor of 0.5–0.9 wt% of the total dry powder mass; exceeding 1.2 wt% delays cement hydration onset by at least 45 minutes as measured by isothermal conduction calorimetry at 20 °C, a retardation mechanism attributable to PVA adsorption onto C3S grains that blocks dissolution sites. When the hydration crust finally ruptures, the flash-set leads to surface micro-cracking that reduces the paint-holding tensile adhesion measured per JG/T 298-2010 to below 0.28 MPa. Workers on twin-ribbon dry mortar mixers of 2-ton capacity observe that premixing the PVA fraction with filler for 8–10 minutes before cement introduction masks the retardation by creating a buffer layer on calcium carbonate surfaces. The finished skim coat, troweled at 1–2 mm dry film thickness, yields a surface with a 60° gloss of less than 2 GU and a 24-hour surface hardness of 3H pencil per ASTM D3363-22, satisfying application requirements for subsequent emulsion paint topcoats without the cost overlay of imported redispersible polymer powders. An operational limitation persists: PVA grades with residual sodium sulfate above 0.8% (from the neutralization step) induce efflorescence at relative humidity above 85% during curing; specifications from Chinese export suppliers frequently require a sulfate ash content < 0.5% as per GB/T 12010.2.
In interior wall putties designed for machine spray application followed by mechanical leveling, a pre-gelatinized PVA solution with a solids content of 8–10 wt% is combined in a static in-line mixer with the dry powder components at the spray nozzle, bypassing the batch-wise dissolution bottleneck. The PVA grade chosen is a low-viscosity partially hydrolyzed type (86–89 mol% hydrolysis, 4–7 mPa·s as 4% solution) that forms a fluid gel structure shear-thinning enough to pass through a 6-mm nozzle at 0.8 MPa air pressure yet rebuilds gel strength within 12 seconds after deposition to prevent sag on vertical walls. A distinctive compliance demand for this application originates from the EU Regulation (EU) No 10/2011 on plastic materials and articles intended to come into contact with food, when such putty lines indirect-contact walls in food processing facilities; migration of vinyl acetate monomer must remain below the specific migration limit of 12 mg/kg food simulant, necessitating PVA with a residual monomer content no greater than 5 ppm as certified by headspace gas chromatography. During on-site commissioning, technicians record a significant deviation if the compressed air supply moisture content exceeds 100 ppm, because water-laden air prematurely swells the PVA particles at the feed throat of the dry powder eductor, causing a block that requires a full line teardown. The terminal cured putty layer must achieve a surface bond strength per GB/T 9779-2015 exceeding 0.45 MPa when tested by a pull-off adhesion tester with a 50-mm diameter steel dolly; values between 0.29 and 0.44 MPa are considered acceptable only for dry-service interiors without wallpaper adhesion layers.Adding boric acid at a molar ratio to PVA repeating units ranging from 0.02:1 to 0.05:1 in ambient-curing interior wall coatings triggers a transformation from tacky water-soluble film to a clear hydrogel with wet scrub resistance that jumps from under 20 cycles to over 400 cycles under the ASTM D2486 non-abrasive scrub protocol. The crosslinking sequence must follow a precise order: the PVA (98 mol% hydrolysis) is first fully dissolved at 93 °C for 60 minutes, cooled to 55–60 °C, and the boric acid—pre-dispersed as a 5 wt% solution in propylene glycol to prevent localized over-condensation—is metered over 15 minutes under moderate agitation of 300–400 rpm. A pH buffer of sodium tetraborate decahydrate set to maintain a stable slurry pH of 8.0–8.5 is required, because below pH 7.8 the diborate crosslinks are irreversible and lead to gel syneresis within 24 hours of film formation, while above pH 9.2 the monoborate complex dominates and provides no mechanical property uplift. This chemistry anchors an interior clear protective coating applied over decorative lime plasters in heritage restoration projects, where the finished thickness is kept below 15 µm dry to comply with the water vapour transmission rate requirement of >150 g/(m²·day) as tested per ISO 7783:2018, guaranteeing the substrate can breathe. The immersion-cooled double-planetary mixer set at 45 °C for the letdown step has shown that a temperature overshoot of merely 3 °C during catalyst addition initiates premature hydrogen bonding collapse, evidenced by a rapid drop in Brookfield viscosity from 2,500 mPa·s to below 900 mPa·s, rendering the batch unrecoverable.
Construction site protection demands a temporary, peelable film that adheres to glass, anodized aluminium, and cured epoxy floors but can be removed without residue after 30 days of UV exposure through windows. A fully hydrolyzed PVA with a solid content of 15 wt% in deionized water, plasticized with polyethylene glycol (PEG-400) at 12–15 phr on resin solids, is cast via airless spray at 0.8 mm wet thickness onto masked surfaces. The plasticizer ratio is bounded: below 10 phr the dry film fractures under tensile extension, measured by a universal testing machine at a strain at break of 35% (ASTM D882-18, specimen type IV), while above 18 phr the film loses cohesive strength and tears during peel at an angle of 180°, leaving fragments smaller than 5 mm² that require solvent wipe removal. The production tank is a horizontal ploughshare mixer with integrated choppers, operating at a tip speed of 5 m/s for dry PVA pre-wetting, then transitioned to a slow ribbon speed of 1 m/s for hydration over 2 hours. Customers performing outdoor exposure in the Gulf region provide field reports that film embrittlement occurs prematurely at cumulative UV doses exceeding 1,300 MJ/m² (measured by a class I pyranometer) when the PVA contains no hindered amine stabilizer; addition of a low-molecular-weight HALS at 0.3 wt% of total formulation extends the peelable window to 60 days. The formulation meets the landfill disposal compliance of OECD 301B for ready biodegradability, requiring >60% theoretical CO₂ evolution in 28 days, which the PVA backbone achieves without additional additives in standard sludge inoculum testing.
Lime-putty interior finishes matured for at least 6 months in pits exhibit a pore solution pH of 12.6–13.0 during carbonation. When PVA is introduced as a cohesion enhancer at 0.3–0.6 wt% of wet plaster mass—added as a dried powder to the lime at the final tempering stage within a pan mixer of 500 L capacity—a severe hydrolysis of residual acetyl groups occurs within the first 72 hours, dropping the effective degree of hydrolysis by 2–3 percentage points and splitting the polymer backbone as tracked by size-exclusion chromatography (Mw shift from 85 kDa to under 42 kDa). The consequence is a 6-month carbonation strength measured by a Shore D durometer that plateaus at 32 units versus 48 units for lime-only controls, due to premature void collapse. To circumvent this, a grade of PVA internally stabilized with an epichlorohydrin crosslinker during manufacture—classified as a barrier polymer—is used instead, at a matching loading, and the carbonation strength maintains 45–47 Shore D. Applicators must verify that the product data sheet specifies a weight-average molecular weight retention of >85% after immersion in saturated Ca(OH)₂ solution at 23 °C for 28 days per GB/T 17671-2021 modified. This application is covered by the REACH Regulation (EC) No 1907/2006 for substances in articles, with an obligation to communicate safe use information related to respirable crystalline silica from the plaster component, not from PVA.
| PVA Parameter | High-PVC Latex Paint (Thickener) | Cementitious Skim Coat (Binder) | Peelable Protective Film | Boric Acid-Crosslinked Topcoat |
|---|---|---|---|---|
| Hydrolysis (mol%) | 87–89 | 98.0–98.8 | ≥98.5 | 97.5–99.0 |
| 4% Viscosity (mPa·s) | 20–30 | 5–12 (dry powder) | 40–55 | 25–35 |
| Addition Rate (wt%) | 0.15–0.40 of liquid | 0.5–0.9 of dry mix | 15 (solution solids) | 5–7 of liquid coating |
| Critical Process Window | Post-letdown temperature ≤35 °C | Sulfate ash ≪0.5% | Plasticizer at 12–15 phr | Boric acid ratio 0.02–0.05:1 |
| Primary Performance Test | ISO 11998 scrub cycles >150 | JG/T 298-2010 bond >0.28 MPa | Tensile strain >100% (ASTM D882) | ASTM D2486 scrub >400 |
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| Typical designation | Degree of hydrolysis (mol%) | Viscosity of 4% aq. solution at 20 °C (mPa·s) | Ash content (wt%, max) | Volatiles (wt%, max) |
|---|---|---|---|---|
| Partially hydrolyzed, low viscosity | 87.0–89.0 | 3.5–5.5 | 0.5 | 5.0 |
| Partially hydrolyzed, medium viscosity | 87.0–89.0 | 20.0–30.0 | 0.5 | 5.0 |
| Partially hydrolyzed, high viscosity | 87.0–89.0 | 44.0–56.0 | 0.5 | 5.0 |
| Fully hydrolyzed, medium viscosity | 98.0–99.0 | 12.0–18.0 | 0.8 | 5.0 |
| Fully hydrolyzed, high viscosity | 98.0–99.0 | 25.0–35.0 | 0.8 | 5.0 |
| Property | Test method | Partially hydrolyzed PVA (neat film) | PVAc homopolymer (neat film) | Styrene-acrylic copolymer (neat film) |
|---|---|---|---|---|
| Tensile strength (23 °C, 50 % RH) | ISO 527-3 | 45–60 MPa | 15–25 MPa | 8–15 MPa |
| Elongation at break | ISO 527-3 | 5–25 % | 400–600 % | 300–500 % |
| 24-h water absorption | ASTM D570 | Dissolves or >50 % (uncrosslinked) | 2–5 % | 3–8 % |
| MFFT | ISO 2115 | 5–25 °C (grade-dependent) | 15–18 °C | <5 °C |
| Redispersibility in water | Visual after 30-min soak | Excellent (uncrosslinked) | None | None |
| Typical scrub cycles (PVC 75 %, 200 µm DFT) | ASTM D2486 | 100–250 | 200–400 | 400–800 |
| Odour/VOC potential | ISO 11890-2 | Negligible; water only | Trace acetic acid possible | Residual monomers <50 ppm |
