| HS Code | 920323 |
| Product Name | Sinopec VAM HP High Purity Refined Grade |
| Chemical Name | Vinyl acetate monomer |
| Chemical Formula | C4H6O2 |
| Cas Number | 108-05-4 |
| Molecular Weight | 86.09 g/mol |
| Appearance | Clear, colorless liquid |
| Purity | >=99.9% |
| Boiling Point | 72.7 °C at 1013 hPa |
| Melting Point | -93 °C |
| Flash Point | -8 °C (closed cup) |
| Autoignition Temperature | 427 °C |
| Specific Gravity | 0.934 at 20/20 °C |
| Vapor Pressure | 115 hPa at 20 °C |
| Solubility In Water | 20 g/L at 20 °C |
| Refractive Index | 1.3953 at 20 °C |
| Viscosity | 0.41 mPa·s at 20 °C |
As an accredited Sinopec VAM HP High Purity Refined Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Sinopec VAM HP High Purity Refined Grade is packaged in 200 kg drums, ensuring safe handling, secure storage, and product purity. |
| Container Loading (20′ FCL) | 20′ FCL: drums/IBCs of Sinopec VAM HP High Purity secured, ventilated, segregated from incompatibles, with proper labeling and spill containment. |
| Shipping | Sinopec VAM HP High Purity Refined Grade ships as a flammable liquid in dedicated ISO tanks, drums, or bulk containers. Transport requires proper hazard labeling, ventilation, and grounding to prevent static discharge. Keep away from heat, ignition sources, and oxidizers. Ensure compliance with international chemical transport regulations. |
| Storage | Store in tightly sealed, corrosion-resistant containers under a nitrogen blanket to prevent polymerization. Keep in a cool, dry, well-ventilated area away from heat, sparks, and direct sunlight. Maintain temperature below 30°C and ensure inhibitors remain active. Use grounded equipment and follow all safety guidelines for flammable and reactive materials. |
| Shelf Life | Shelf life is typically 12 months when stored properly in sealed containers, away from heat, moisture, and ignition sources. |
Continuous polyvinyl alcohol production from Sinopec VAM HP high purity refined grade proceeds through methanolic radical polymerisation followed by base-catalysed transesterification. In the polymerisation stage, the inhibitor-reduced monomer stream is blended with methanol to a vinyl acetate concentration of 20–45 wt% and fed into a stirred jacketed reactor or continuous screw-type polymeriser at 55–65°C. Free-radical initiation with 0.05–0.3 wt% 2,2'-azobisisobutyronitrile or bis(4-tert-butylcyclohexyl) peroxydicarbonate relative to vinyl acetate produces a solution polymer with a degree of polymerisation between 500 and 3,000. Unreacted vinyl acetate is stripped in a steam-heated distillation column to below 100 mg/kg in the PVAc/methanol solution. Alcoholysis is carried out with sodium methoxide in methanol at 40–50°C using a molar alkali ratio of 0.005–0.02 mol per mol ester. The degree of hydrolysis is controlled between 87 mol% and >99 mol% depending on the downstream target. Impurities in VAM, particularly acetaldehyde, act as chain transfer agents and reduce attainable molecular weight, while acetic acid shifts the alkali balance in the alcoholysis step and increases sodium acetate formation. High-purity refined-grade VAM with low acidity therefore reduces caustic demand and improves fibre-grade PVOH colour. The finished PVOH is used in textile warp sizing, paper surface sizing, polyvinyl butyral interlayer feedstock, and water-soluble detergent film. Food-contact use is evaluated under FDA 21 CFR 177.1670 and European Commission Regulation EU No 10/2011. Viscosity and hydrolysis ratio are measured per ISO 15023-1 and ISO 15023-2. Operational boundary: vent condensers are maintained below 40°C during monomer handling because vinyl acetate vapours can form peroxide species under upset conditions.
| Parameter | Test method | High-purity refined-grade acceptance window | Downstream consequence when exceeded |
|---|---|---|---|
| Vinyl acetate purity | ASTM D2190 GC assay | ≥99.9 wt% | Non-monomer compounds dilute active feedstock and alter bubble-point in stripping columns |
| Water content | Karl Fischer ASTM D1364 or equivalent | ≤0.02 wt% | Hydrolyses PVAc in solution; raises caustic demand in PVOH alcoholysis |
| Acidity as acetic acid | ASTM D2192 titration | ≤0.005 wt% | Consumes alkali catalyst; increases sodium acetate residue in PVOH |
| Acetaldehyde | ASTM D2191 derivatisation or GC | ≤0.005 wt% (50 mg/kg) | Chain transfer lowers molecular weight; yellowing in EVOH and encapsulant films |
| Methyl acetate | Internal GC or ASTM D2190 related impurity profile | ≤0.05 wt% | Solvent balance alteration and reduced effective monomer concentration |
| Hydroquinone inhibitor | ASTM D2193 or UV method | 3–15 mg/kg | Induction period variation in high-pressure EVA and batch emulsion processes |
For high-clarity ethylene-vinyl acetate encapsulant films, Sinopec VAM HP high purity refined grade is copolymerised with ethylene in a continuous high-pressure autoclave or tubular reactor at 140–200 MPa and 180–280°C. The VAM content in the finished EVA is maintained between 28 wt% and 33 wt%, because film transparency and crosslinking density shift sharply outside this window. Low-boiling impurities in the monomer, particularly acetaldehyde and methyl acetate, are stripped before injection to limit gel specks and chromophore formation in the molten polymer. The high-pressure plant typically operates with a chain transfer agent such as propylene or isopropanol to hold melt flow index within 15–45 g/10 min at 190°C and 2.16 kg, determined per ISO 1133-1:2022. For encapsulant grade EVA, optical transmission is required to exceed 90% in the 380–1,100 nm range when measured on a 0.46 mm film according to ASTM D1003. Volume resistivity after lamination is monitored above 1×1014 Ω·cm under IEC 60093 or ASTM D257 to reduce potential-induced degradation risk. The compounded EVA sheet is used as a crosslinked encapsulation layer in glass–backsheet and glass–glass photovoltaic modules. Adhesion to glass is verified by ASTM D903 peel testing after lamination at 145–155°C for 12–18 min. Monomer purity is screened against ASTM D2190, and any batch with acidity above 0.005 wt% is rejected for encapsulant service because residual acid reacts with the silane adhesion promoter and accelerates crosslinker premature hydrolysis. Pellets exposed to ambient humidity above 60% require pre-drying at 60°C for 4–6 h to reduce moisture below 300 mg/kg before film extrusion.
Façade mortar binders formulated with Sinopec VAM HP high purity refined grade use semi-batch pressure vessels to produce vinyl acetate ethylene copolymer emulsions. The monomer feed normally contains 70–90 wt% vinyl acetate and 10–30 wt% ethylene, and the reactor is operated at 60–85°C under 30–70 bar ethylene pressure. A redox initiation system consisting of ammonium persulfate and sodium metabisulfite is used at 0.1–0.4 wt% total oxidising/reducing agent on total monomer, with polyvinyl alcohol or water-soluble cellulose ether as protective colloid. The solids content is held at 53–58 wt%, viscosity at 500–4,000 mPa·s per ISO 2555 using a Brookfield viscometer at 23°C and 20 rpm, and the final dispersion pH is adjusted to 4.0–5.5. Low acidity in the VAM feedstock is essential because free acetic acid destabilises the colloidal system, consumes buffering capacity, and increases corrosion in downstream spray-drying equipment. The emulsion is often converted to redispersible polymer powder by spray drying at inlet temperatures of 120–160°C and outlet temperatures of 60–80°C, with 10–25 wt% anti-blocking mineral addition. The resulting powder is incorporated into dry-mix formulations at 2–6 wt% for cementitious tile adhesives classified under EN 12004 as C1 or C2 when tensile adhesion strength after immersion is verified at ≥0.5 N/mm² for C1 and ≥1.0 N/mm² for C2 on standard concrete. Iron contamination above 10 ppm is avoided because it promotes redox instability and premature coagulation in storage.
The homopolymer emulsion route depends on Sinopec VAM HP high purity refined grade as the sole monomer in aqueous polyvinyl acetate systems. A batch reactor charged with demineralised water, 1–5 wt% partially hydrolysed PVOH, and 0.1–0.5 wt% ammonium persulfate is heated to 65–80°C. Vinyl acetate is added over a 3–5 h delay feed at a monomer-to-water ratio that produces final solids of 50–55 wt%. The reaction exotherm is controlled by jacket cooling to maintain a temperature differential of 2–5°C between the jacket and the batch. Residual free monomer is reduced to <1,000 mg/kg during a post-reaction chase using a redox pair. Final adhesive viscosity measured per ISO 2555 at 23°C is typically 3,000–12,000 mPa·s for D3 assembly grades with spindle 4 at 20 rpm. The adhesive is formulated with 0.5–2 wt% coalescent, 0.1–0.3 wt% defoamer, and 0.1–0.5 wt% preservative. D3 and D4 wet-use bond strength is evaluated under EN 204 and EN 205, and D4 requires a shear strength of at least 4.0 N/mm² after 6 h boiling for birch-to-birch bonds. For food packaging adhesion, the formulated adhesive is evaluated under FDA 21 CFR 175.105 as an indirect food additive. Amine-based buffers should not be used because they complex with the free-acid fraction and shift pH above 5.5, causing rapid viscosity loss and separation.
For multilayer chilled-food trays and medical blister films, Sinopec VAM HP high purity refined grade is first converted to an EVA precursor with a VAM content of 32–44 mol% in a high-pressure radical copolymerisation train. The EVA is then subjected to alcoholysis with methanol and sodium methoxide in a continuous twin-screw devolatilisation reactor. The base-catalysed conversion replaces acetate groups with hydroxyl groups, yielding an EVOH copolymer with ethylene content between 27 mol% and 48 mol%. Residual acetic acid and acetaldehyde in the VAM monomer are amplified during the high-pressure step and appear in the EVOH as aldehyde-addition products and colour bodies. A high-purity refined-grade VAM with acetaldehyde content below 50 mg/kg is therefore used to keep the EVOH yellowness index below 1.0, measured per ASTM E313. The EVOH layer is typically 5–20 μm thick inside a multilayer polypropylene or polyethylene sheet. Oxygen transmission rate is verified at 23°C and 0% relative humidity per ASTM D3985 at below 0.5 cm³·mm/m²·day·atm for a 15 μm cast film. Food-contact compliance is assessed under FDA 21 CFR 177.1360 and EU No 10/2011. Operational limitation: hot-melt processing above 250°C is avoided because EVOH can form gel particles and undergo thermally induced colour shift in coextrusion dies.
| Requirement | Standard or method | Typical acceptance criterion for a 15 μm EVOH layer |
|---|---|---|
| Oxygen transmission rate at 23°C, 0% RH | ASTM D3985 | <0.5 cm³·mm/m²·day·atm |
| Yellowness index | ASTM E313 | <1.0 |
| Ethylene content | ISO 1133 or NMR | 27–48 mol% |
| Vinyl acetate monomer specific migration | EU No 10/2011 | <0.01 mg/kg |
| Food-contact resin status | FDA 21 CFR 177.1360 | Complies as EVOH copolymer |
Dry-spun acrylic fibre producers use Sinopec VAM HP high purity refined grade as a comonomer in acrylonitrile–vinyl acetate copolymers at 8–15 wt% VAM in the monomer feed. The polymerisation is performed in dimethylformamide or aqueous sodium thiocyanate solution at 50–70°C using a redox initiator. The VAM unit disrupts polyacrylonitrile crystallinity and increases dye site accessibility, which improves cationic dye uptake without over-reducing the glass transition temperature. High-purity VAM limits chain transfer, gel formation, and discolouration during dope preparation and filtration through 20–50 μm absolute filters before dry spinning. The resulting fibre is used in knitwear, hand-knitting yarns, and outdoor furniture covers. Colour fastness is controlled under AATCC TM 107 for water fastness and AATCC TM 61 for laundering, while residual vinyl acetate in the finished fibre is monitored against OEKO-TEX Standard 100 limit values. Residual moisture above 0.5% in the spinning dope is avoided because it destabilises the solution and causes spinneret drips. Published data for this specific high-purity VAM grade in acrylic fibre copolymerisation is limited, but the monomer impurity profile aligns with standard dry-spinning requirements for low-colour dope formation.
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Sinopec VAM HP High Purity Refined Grade is a high-purity vinyl acetate monomer supplied for free-radical polymerization, copolymerization, and transacetalization. The product code is VAM HP. The substance is identified by CAS 108-05-4, molecular formula C4H6O2, and molecular weight 86.09 g/mol. At 101.325 kPa the normal boiling point is 72.7 °C; density at 20 °C is approximately 0.933 g/cm³. The refined grade is stabilized with hydroquinone at a typical concentration of 3–20 mg/kg, with the exact inhibitor level printed on the certificate of analysis. The material is a Class IB flammable liquid and is assigned UN 1301, vinyl acetate, stabilized. Table 1 lists representative release data for high-purity refined vinyl acetate monomer; lot-specific limits may be tighter after distillation and inhibited filling.
| Parameter | Unit | Limit | Test method |
|---|---|---|---|
| Appearance | — | Clear, free from suspended matter | Visual inspection |
| Purity | wt% | ≥99.9 | ASTM D2190 |
| Water | wt% | ≤0.030 | ASTM E203 |
| Acidity as acetic acid | wt% | ≤0.005 | ASTM D1613 |
| Aldehydes as acetaldehyde | wt% | ≤0.004 | ASTM D2190 |
| Color, Pt-Co | — | ≤5 | ASTM D1209 |
| Density at 20 °C | g/cm³ | 0.933–0.935 | ASTM D4052 |
These limits align with ASTM D2190 while tightening acidity and water below the general technical-grade upper boundary. The compressed impurity envelope is the principal distinction between this refined grade and standard vinyl acetate monomer used for lower molecular-weight commodity homopolymers.
The refined-grade designation does not rest on a single purity figure; it reflects a narrower budget for water, acidity, and carbonyl-bearing species. Residual acetaldehyde functions as a chain-transfer agent in vinyl acetate polymerization, lowering number-average molecular weight and broadening molecular weight distribution. Residual water hydrolyzes vinyl acetate to acetic acid and acetaldehyde under warm storage, shifting monomer acidity and consuming buffer in water-based polymerization. Commodity technical VAM commonly carries a minimum purity of 99.5 wt%, whereas refined VAM HP is specified at ≥99.9 wt%. The difference in major impurity content is shown in Table 2.
| Parameter | Unit | Commodity technical VAM | Sinopec VAM HP refined grade |
|---|---|---|---|
| Purity | wt% | ≥99.5 | ≥99.9 |
| Water | wt% | ≤0.05 | ≤0.030 |
| Acidity as acetic acid | wt% | ≤0.01 | ≤0.005 |
| Aldehydes as acetaldehyde | wt% | ≤0.008 | ≤0.004 |
| Color, Pt-Co | — | ≤10 | ≤5 |
The lower water content also matters in moisture-sensitive ethylene-vinyl acetate copolymerization using organometallic catalysts, where hydrolytic cleavage of vinyl ester bonds produces acetic acid and can reduce catalyst productivity. The water limit of ≤0.030 wt% is intended to keep monomer feed water below the threshold at which buffer demand in emulsion polymerization and catalyst poisoning in high-pressure EVA become detectable by plant instruments. No other difference in the base molecular structure exists; the improvement is compositional, not a change in the monomer itself.
In production-scale polyvinyl acetate and vinyl acetate-ethylene emulsion lines, residual water in the monomer feed is not an inert diluent. In a jacketed 316L stainless steel continuous stirred-tank reactor with a residence time of 4–8 h and an operating temperature of 70–85 °C, water present above 0.05 wt% hydrolyzes the vinyl ester to acetic acid and acetaldehyde. The resulting pH drift lowers persulfate initiator half-life and forces addition of sodium bicarbonate or sodium acetate buffer to maintain latex stability. Acetaldehyde generated by hydrolysis competes with monomer for propagating radicals, reducing kinetic chain length and final polymer molecular weight. This is observed as a shift in latex viscosity and a change in grit formation threshold under high-shear mixing.
Refined-grade water control at ≤0.030 wt% reduces the frequency of buffer correction and narrows batch-to-batch variation in continuous reactor trains. In vinyl acetate-ethylene copolymer emulsions, aldehyde impurities can also react with ethylene glycol or other crosslinkers during post-cure, affecting gel content. Plant trials across different reactor scales are limited in public literature; therefore the exact viscosity shift for a given CSTR configuration should be derived from lot-specific impurity data and on-line pH/molecular weight measurements rather than from a single fixed offset.
For high-shear dispersion downstream, residual acetic acid above 0.01 wt% in the monomer feed can accelerate hydrolysis of polyvinyl acetate in the presence of water and heat, generating free acetic acid during stripping of residual monomer. The refined grade's acidity limit of ≤0.005 wt% keeps this contribution below levels that require additional neutralization in the final dispersion. On continuous lines using shell-and-tube condensers and monomer preheaters, lower acidity also reduces pitting tendency in carbon steel portions of older equipment, although 316L stainless steel remains the preferred wetted material.
Vinyl acetate-ethylene copolymer dispersions formulated for low-odour architectural paints and low-solvent adhesives expose acetaldehyde to headspace during film formation. Refined VAM with aldehyde content ≤0.004 wt% is used where formulation audits under ISO 16000-6 or similar indoor-air protocols require reduced volatile carbonyl contribution from the binder. Polyvinyl alcohol grades produced by saponification of PVAc derived from refined VAM show lower residual carbonyl defects, which is relevant for polyvinyl butyral interlayer used in laminated glass; carbonyl groups in PVB absorb at 280–400 nm and contribute to yellowness under accelerated weathering according to ISO 4892-2. Ethylene-vinyl acetate copolymer pellet lines using high-pressure autoclave or tubular reactors benefit from low water because water consumes organometallic catalyst and introduces hydrolytic end groups. For EVA compounds with a melt mass-flow rate of 1.5–2.5 g/10 min measured at 190 °C, 2.16 kg under ISO 1133-1:2022, the monomer feed impurity level influences melt rheology and adhesion to polyethylene in coextruded films. Published data for this specific refined grade in high-pressure EVA autoclave reactors are limited; plant-specific and catalyst-specific threshold verification is required before changing monomer sourcing.
In polyvinyl acetate wood adhesives and paper laminating emulsions, chain transfer from acetaldehyde can depress molecular weight below the minimum needed for shear resistance. The refined grade lowers this source of chain-transfer variability, but formulators must still adjust initiator, buffer, and surfactant feeds according to reactor temperature, solids target, and residual monomer stripping conditions. In semi-continuous emulsion polymerization using persulfate initiators, reduced acidity in the monomer feed allows a tighter pH control window in the aqueous phase, particularly for surfactant systems sensitive to ionic strength drift.
VAM HP is classified as a Class IB flammable liquid with a closed-cup flash point of −8 °C. Storage tanks for refined vinyl acetate should be fabricated from 316L stainless steel or aluminium, fitted with pressure/vacuum relief, and inert-gas padded at 5–10 kPa gauge. Hydroquinone inhibitor is oxygen-dependent; prolonged nitrogen blanketing can deplete inhibitor activity if oxygen ingress is too low. Refined monomer stored for more than 30 days should be tested for inhibitor concentration and polymer content, particularly after any tank temperature excursion above 30 °C. The product should not be combined with strong oxidizers, free-radical initiators, or strong acids, since these classes can initiate bulk polymerization or accelerate ester hydrolysis. Return of partially emptied drums to bulk storage is discouraged unless inhibitor concentration has been confirmed by titration or UV spectroscopy.
During transfer, positive-displacement pumps with carbon steel internals are avoided because iron contamination can promote oxidative degradation; 316L stainless steel or PTFE-lined equipment is used. Filling lines are earthed because the liquid resistivity is in a range where electrostatic accumulation is possible. At relative humidity above 60%, transfer points and sample lines should be purged and sealed to limit atmospheric moisture ingress during drumming or day-tank loading.
Under REACH, vinyl acetate monomer is a registered substance and the refined grade does not have a separate CAS registry entry from technical-grade vinyl acetate. Chemical inventory listings therefore follow CAS 108-05-4. Transport classification is UN 1301, Class 3, Packing Group II. For indirect food-contact applications, vinyl acetate monomer is referenced in FDA 21 CFR 175.105 and FDA 21 CFR 175.300 for adhesives and resinous coatings, but the finished polymer article must still meet overall migration limits under the applicable national or EU regime. Under Regulation (EU) No 10/2011, compliance is evaluated on the final plastic article, not on the monomer alone. Sinopec VAM HP High Purity Refined Grade is supplied for industrial and polymer production use; it is not intended for direct consumer use.
