| HS Code | 151515 |
| Chemical Name | Poly(vinyl acetate) |
| Cas Number | 9003-20-7 |
| Chemical Formula | (C4H6O2)n |
| Polymer Type | Thermoplastic |
| Appearance | White to off-white pellets or beads |
| Odor | Mild, characteristic ester-like odor |
| Density | 1.18–1.20 g/cm³ at 20°C |
| Glass Transition Temperature | 30–40°C depending on grade |
| Melting Point | No true melting point (amorphous); softens above Tg |
| Thermal Decomposition Temperature | Starts to decompose above approximately 250°C |
| Solubility | Insoluble in water; soluble in acetone, ethyl acetate, benzene, and methylene chloride |
| Refractive Index | 1.466 |
| Molecular Weight | Typically 100,000–500,000 g/mol depending on grade |
As an accredited PVAc Resin Pellets factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | PVAc Resin Pellets are packaged in 25 kg net, double-layer sealed polyethylene-lined woven bags for safe handling and moisture protection. |
| Container Loading (20′ FCL) | Loading 20′ FCL with PVAc resin pellets in bags; ensure even weight distribution, ventilation, and secure lashing to prevent shifting. |
| Shipping | PVAc Resin Pellets are shipped in sealed polyethylene-lined bags or fiber drums to prevent moisture uptake. Keep pallets dry and away from heat sources. Non-hazardous, but use proper lifting equipment. Store in a cool, ventilated area; avoid prolonged exposure to sunlight to preserve resin quality. |
| Storage | Store PVAc resin pellets in a cool, dry, well-ventilated area away from direct sunlight, heat, and open flames. Keep containers tightly sealed to prevent moisture absorption and contamination. Avoid contact with strong oxidizers, acids, and alkalis. Maintain stable temperatures, and ensure proper labeling and segregation from incompatible materials. Use appropriate handling and storage practices. |
| Shelf Life | Store in a cool, dry place away from moisture and heat. Shelf life is typically 24 months from manufacture date. |
On flat-bed laminators running paperboard to single-side coated board at 12–18 m/min, polyvinyl acetate pellets are reduced to a 34–40 wt% solids adhesive in an ethyl acetate:acetone blend of 80:20 w/w. The pellets are pre-dried at 40 ± 2 °C for 2 h to ≤ 0.15% moisture by Karl Fischer titration per ISO 15512, because moisture above 0.2% accelerates ester hydrolysis and viscosity drift. Dissolution proceeds in an explosion-proof high-shear dissolver with a 280 mm disc at 12–15 m/s tip speed and jacket temperature 35–40 °C. The solvent fraction is charged first, and pellets are metered over 10–15 min to avoid lump formation. After complete dissolution, dipropylene glycol dibenzoate is added at 5–10 phr, and the batch is held under a nitrogen blanket for 12 h before filtration through a 50 μm wire mesh. The finished adhesive at 38% solids shows a Brookfield RVT viscosity of 900–1,500 mPa·s at 25 °C when measured with spindle 4 at 20 rpm. Open time on uncoated paperboard at 23 ± 2 °C and 50 ± 5% RH with air velocity 2.5 m/s falls between 20 s and 35 s; raising air velocity to 4 m/s lowers open time to 12–18 s, a condition acceptable only for mechanized lay-up, not for hand positioning. For interior wood assembly, lap-shear strength on beech substrates prepared per EN 205 reaches 10–12 MPa after 7-day conditioning at 23 °C. After cold-water storage for 4 days per EN 204 D3, strength typically declines to 2–4 MPa, confirming that uncrosslinked PVAc homopolymer remains an interior-purpose adhesive rather than a structural or exterior-grade product. The formulated adhesive cannot meet D4 or load-bearing service unless a blocked isocyanate, phenolic resole, or other crosslinker is added, because the vinyl acetate ester groups are hydrolytically sensitive under alkaline pH. Terminal outputs include dry-food cartons, paper bags, and interior wood corner blocks. Indirect food-contact status under 21 CFR 175.105 applies only when the adhesive is separated by a functional barrier or residual solvent levels meet the migration limits of the applicable food packaging regulation.
| Plasticizer content (phr) | Brookfield RVT viscosity (mPa·s, 25 °C) | Open time at 2.5 m/s (s) | T-peel on corona-treated PET (N/25 mm, ASTM D1876-08) |
|---|---|---|---|
| 0 | 1600 | 32 | 3.1 |
| 5 | 1200 | 26 | 4.8 |
| 10 | 950 | 20 | 5.2 |
| 15 | 700 | 14 | 4.5 |
Table 1 represents a single production-batch gradient for a 38% solids adhesive. Batch-to-batch viscosity variation remained below 8% after 12 h recirculation, and filtration pressure stayed below 2.0 bar at 25 °C. Plasticizer migration into low-density polyethylene film can occur after extended storage above 40 °C; for direct food-contact packaging, a citrate ester or triacetin replacement is required.
In a 200 L counter-rotating sigma-blade mixer, PVAc pellets with a melt flow rate of 4–10 g/10 min per ISO 1133-1:2022 at 190 °C and 2.16 kg are combined with microcrystalline wax, glycerol ester of partially hydrogenated wood rosin, and calcium carbonate at a PVAc loading of 30–45 wt%. The mixer is preheated to 115 °C; pellets are charged first and masticated for 10–15 min until torque stabilizes. Jacket temperature is maintained at 120–125 °C. On a 75 kW drive, the stabilized torque window is 30–45 A; a sustained rise above 50 A indicates poor dispersion or an excessive high-molecular-weight fraction. After the PVAc forms a coherent melt, wax and rosin ester are added at 10–20 wt% each, followed by calcium carbonate at 5–15 wt%. Vacuum is pulled at -0.8 bar for the final 5–10 min to strip residual acetic acid and moisture. The finished base is pelletized through a twin-screw extruder with barrel temperatures held below 130 °C; above 150 °C thermal deacetylation releases acetic acid, causing off-notes and melt viscosity loss. Finished base softening point by ring-and-ball per ISO 4625-1 is 68–85 °C, and complex viscosity at 120 °C and 0.1 s-1 is 120–200 Pa·s, falling to 70–110 Pa·s at 1 s-1 under 25 mm parallel-plate rheometry. PVAc molecular weight selection is the main lever for chewing texture: grades below 25,000 g/mol soften too early and produce a slack chew, while grades above 60,000 g/mol increase mixer torque and may survive mastication as a tacky mass. Published data for the precise bubble-blowing performance of food-grade gum base as a function of PVAc polydispersity is limited; process control therefore relies on MFR, softening point, and low-vacuum organoleptic screening rather than peer-reviewed mechanical models. The gum base is shipped to confectionery processors for sugar-free tablets, sticks, and bubble gum. Compliance rests on the polyvinyl acetate listing in 21 CFR 172.615, with residual vinyl acetate monomer and extractive limits controlled under the applicable food-contact requirements.
| Regulation / Method | Scope | Key parameter |
|---|---|---|
| 21 CFR 172.615 | Chewing gum base polymer listing | PVAc permitted; residual vinyl acetate monomer subject to listing limits |
| ISO 1133-1:2022 | Melt flow rate | 190 °C, 2.16 kg, 4–10 g/10 min |
| ISO 4625-1 | Ring-and-ball softening point | 68–85 °C |
| ISO 11357-2 | DSC glass transition | 28–33 °C |
Gravure ink binder preparation starts with PVAc pellets selected for narrow molecular weight distribution and a melt flow rate of 3–9 g/10 min per ISO 1133-1:2022. In a 500 L stainless jacketed dissolver, pellets are dissolved at 25% solids in an ethyl acetate:n-propanol blend of 70:30 w/w at 35–40 °C. The solution is filtered through a 25 μm mesh and then used as a co-binder at 8–12 wt% of the total flexographic ink formulation. A horizontal bead mill with 0.6–0.8 mm zirconia beads at 12 m/s tip speed disperses pigment in a premix containing 10–12% PVAc binder, 15–18% nitrocellulose, 2–4% plasticizer, and solvent. Final ink viscosity at 23 °C is 22–30 s through a 4 mm cup per ISO 2431. On low-density polyethylene film with surface energy above 38 mN/m per ISO 8296, tape adhesion per ASTM F2252-03 shows less than 5% area removal after 24 h conditioning. PVAc contributes pigment wetting, adhesion to corona-treated polyolefin, and resolubility in the press-return ink system; nitrocellulose raises heat resistance and reduces blocking. Blocking resistance is tested at 50 °C under 0.5 kg/cm² for 24 h, and printed film is inspected for surface transfer. If PVAc content exceeds 15 wt%, blocking resistance deteriorates and coefficient of friction rises above 0.35–0.40 per ASTM D1894. The dried binder film exhibits a glass transition of 28–33 °C by differential scanning calorimetry per ISO 11357-2, and therefore the system is not intended for retort or boil-in-bag applications where package surface temperature exceeds 60 °C. Terminal products include bread bags, frozen vegetable films, and surface-printed paper labels. For food-contact printed matter, the formulation must comply with EU Regulation 1935/2004 Article 3 and applicable good manufacturing practice for printing inks.
Paperboard lamination lines running at 80–150 m/min use a PVAc pellet solution at 40% solids in ethyl acetate as the laminating adhesive for printed paperboard to polyethylene or polypropylene film. The resin is dissolved in an explosion-proof high-shear dissolver under nitrogen, with jacket temperature limited to 35–40 °C and final filtration through 50 μm mesh. The drying tunnel must be balanced so that residual solvent in the finished laminate remains below 250 mg/m² after 24 h when tested by headspace gas chromatography per EN 13628-2. Typical production values at 80–150 m/min are 80–150 mg/m²; values above 250 mg/m² generate odour and migration failures in low-odour carton programs. Dry coating weight is controlled at 2.0–3.5 g/m² using a 60 l/cm gravure cylinder. Bond strength on paper/PE laminate after 24 h at 23 °C and 50% RH is 1.5–2.5 N/15 mm when pulled at 100 mm/min per ISO 11339; the dominant failure mode should be paper fiber tear. PVAc homopolymer in this laminate provides short open time on the roller coater, low odour, and sufficient stiffness for carton creasing. However, the film is not oil-retardant and should not be used for direct contact with liquid vegetable oil unless a barrier topcoat is applied. Indirect food-contact status uses 21 CFR 175.105 and requires either a functional barrier or residual solvent levels below migration limits. Terminal products include soap cartons, frozen food boxes, and pharmaceutical secondary packaging. Process limits include the need to pre-dry pellets to ≤ 0.15% moisture and to maintain adhesive temperature below 45 °C to prevent viscosity drift in the roller reservoir.
For overprint varnish formulations, PVAc pellets are dissolved under high shear in an ethyl acetate:isopropanol blend of 80:20 w/w at 35–40 °C, then combined with nitrocellulose or acrylic copolymer to adjust film hardness, heat-seal release, and gloss. PVAc solids occupy 10–15 wt% of the varnish, nitrocellulose 8–12 wt%, plasticizer 2–5 wt%, and a paraffin or polyethylene wax 0.5–1.5 wt%. The varnish is applied by flexographic or gravure printing at a dry film weight of 2–4 g/m², corresponding to a dry film thickness of 2–4 μm. Drying air temperature is maintained between 50 °C and 70 °C; higher temperatures can embrittle the PVAc film and shift colour toward yellow. The 60° gloss measured per ISO 2813 is typically above 75 for high-gloss cosmetic cartons and labels. Taber abrasion per ASTM D4060 using CS-10 wheels with 500 g load for 100 cycles gives a weight loss below 5 mg. Cross-hatch adhesion to the printed surface is assessed per ASTM D3359 method B, with a target classification of 5B. The varnish film is not intended for hot-fill or retort packaging because the polyvinyl acetate ester bond undergoes hydrolytic degradation in moist heat. Terminal products include greeting cards, cosmetic cartons, and pressure-sensitive label face stocks. Process limits include an upper isopropanol content of 30 wt% to prevent precipitation of high-molecular-weight PVAc and a solution storage temperature of 15–25 °C in stainless steel vessels.
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Poly(vinyl acetate) resin pellets, CAS 9003-20-7, are solid thermoplastic homopolymers of vinyl acetate supplied as cylindrical or lenticular granules with bulk density typically 0.55–0.70 g/cm³. Commercial grades are produced by suspension or controlled bulk polymerization followed by devolatilization, strand extrusion, and underwater pelletizing; the pellet geometry permits closed-loop pneumatic conveying and loss-in-weight gravimetric feeding on continuous adhesive compounding lines. Representative grade designations encode standardized melt-flow and plasticizer information—for example, a designation PVAc-15/08 indicates a nominal melt flow index of 15 g/10 min at 190 °C under 2.16 kg load and a plasticizer content of 8 wt%. The homopolymer has a density of 1.18–1.20 g/cm³ per ISO 1183-1, a glass transition temperature of 28–35 °C per ISO 11357-2, and weight-average molecular weight commonly between 3×10⁴ and 2×10⁵ g/mol. Residual vinyl acetate monomer is typically controlled below 0.05 wt% for food-adhesive applications, while total volatile matter after drying is specified below 0.3 wt%. The polymer is soluble in ethyl acetate, methyl ethyl ketone, acetone, and toluene/ester mixtures, but insoluble in water and aliphatic hydrocarbons.
The differentiation from ethylene-vinyl acetate copolymers, partially hydrolyzed polyvinyl alcohol, and acrylic binder systems is summarized in the comparative matrix below.
| Attribute | PVAc homopolymer pellets | EVA copolymer (28 wt% vinyl acetate) | PVOH (88 mol% hydrolysis) | Acrylic binder resin |
|---|---|---|---|---|
| Density per ISO 1183-1 | 1.18–1.20 g/cm³ | 0.94–0.95 g/cm³ | 1.25–1.30 g/cm³ | 1.10–1.20 g/cm³ |
| Glass transition per ISO 11357-2 | 28–35 °C | −20 to −5 °C | 60–70 °C | 5–50 °C |
| Solubility in water | Insoluble | Insoluble | Soluble above 80 °C | Insoluble |
| Residual acetate content | 100 % repeating units | 28 wt% vinyl acetate | 10–12 mol% residual acetate | Not applicable |
| Tensile strength per ISO 527-2 | 20–40 MPa | 5–20 MPa | 50–80 MPa | 10–40 MPa |
| Water resistance as dry film | Moderate; susceptible to hydrolysis | Moderate | Low | High |
Pelletized PVAc is seldom processed without plasticizer or stabilizer because the homopolymer undergoes deacetylation at elevated temperature, releasing acetic acid. Thermogravimetric analysis indicates acetic acid elimination onset near 230 °C; industrial practice therefore restricts melt temperature below 180 °C. Twin-screw compounding lines typically maintain barrel set-point temperatures between 110 °C and 170 °C, with screw speeds from 200 min⁻¹ to 600 min⁻¹ and a length-to-diameter ratio of 40:1. Above a melt temperature of 190 °C, acetic acid evolution becomes measurable, leading to corrosion of nitrided barrel segments, bubble formation at the die, and a shift in melt flow index. At 220 °C, discoloration may appear within 30 s and viscosity may drop by more than 30% due to chain scission; published data for stabilization of unmodified PVAc under these conditions is limited. Processors therefore apply vacuum devolatilization at −0.08 MPa to −0.06 MPa and add 0.1–0.3 wt% acid scavenger or hindered phenolic antioxidant. In contrast, EVA copolymers with 28 wt% vinyl acetate can be extruded up to 230 °C with less acid generation because the acetate concentration along the polymer backbone is lower.
The torque profile in a corotating twin-screw extruder is strongly shear-rate dependent. At 150 °C and a shear rate of 100 s⁻¹, plasticized PVAc may exhibit apparent viscosity between 200 Pa·s and 800 Pa·s, dropping to 50–150 Pa·s at 1,000 s⁻¹. Because the material remains tacky at die temperatures above 70 °C, strand cooling water temperature is controlled below 15 °C and pelletizer air knives are operated with dew point below −10 °C to prevent re-agglomeration. In injection molding of PVAc-based binder shapes, clamp force requirements are lower than for EVA, but vented barrels are mandatory; non-vented configurations trap acetic acid and produce splay on part surfaces. Detailed rheological data for plasticized PVAc pellets across full screw-speed maps is limited; line trials are usually required to establish a stable operating window.
Storage in unopened bags at <30 °C and <60% RH is recommended. If bags are exposed to high humidity, pellets can surface-hydrate, increasing static charge and feeding variability. Hopper dryers should be set at 50 °C for at least 2 h before gravimetric feeding into a twin-screw extruder. Nitrogen-blanketed storage is not required because the material is not oxygen-sensitive below 30 °C.
Solvent-borne adhesive preparation begins with pre-drying at 45–60 °C for 4 h when storage relative humidity exceeds 60%. A high-shear dissolver with a tip speed of 15–25 m/s disperses pellets into ethyl acetate or methyl ethyl ketone; initial solids are held at 30–45 wt% until surface wetting is complete, then adjusted to final viscosity. The resulting solutions show Newtonian behavior at lower solids and shear-thinning above 40 wt%. For paper lamination and bookbinding adhesives, plasticizer is post-added at 5–15 phr; triethyl citrate is preferred where California Proposition 65 or REACH restrictions on ortho-phthalates apply. The final adhesive is applied by roller coater or slot-die at 20–60 µm dry film thickness and dried in a three-zone oven with a first-zone temperature not exceeding 45 °C to avoid skinning.
Migration of vinyl acetate monomer rather than polymer molecular weight is the principal regulatory variable in food-contact adhesive applications. Under FDA 21 CFR 175.105, PVAc is permitted as an adhesive component provided that the finished adhesive is separated from food by a functional barrier or the migration of the monomer does not exceed applicable limits. Under Commission Regulation (EU) No 10/2011, poly(vinyl acetate) may be used in plastic materials subject to overall migration limits of 10 mg/dm² or 60 mg/kg food simulant. Residual monomer is commonly specified below 0.05 wt% in the pellet and verified by headspace gas chromatography; the test method should be reported as producer-specific unless aligned with ASTM D4526 for residual solvents and volatiles. Because PVAc undergoes slow hydrolysis at high humidity, laminations for fatty food contact should be evaluated under EN 1186-1 migration tests at 40 °C/10 days or 60 °C/10 days depending on intended use.
| Compliance area | Test method / regulation | Typical specification |
|---|---|---|
| Residual vinyl acetate monomer | ASTM D4526 / headspace GC | <0.05 wt% |
| Total volatile matter | ISO 3251 | <0.3 wt% |
| Density | ISO 1183-1 | 1.18–1.20 g/cm³ |
| Melt flow index | ISO 1133-1 | 2–40 g/10 min at 190 °C/2.16 kg |
| Glass transition | ISO 11357-2 | 28–35 °C |
| Overall migration | EN 1186-1 | 10 mg/dm² or 60 mg/kg |
Unlike PVAc emulsions, pelletized PVAc does not contain aqueous-phase preservatives or protective colloids such as poly(vinyl alcohol), which can influence water sensitivity. In solvent-based wood assembly, the pelletized form allows the formulator to select the plasticizer and adhesion promoter independently, rather than inheriting the surfactant and buffer package of an emulsion. This difference is notable where open time must be adjusted by solvent choice rather than water evaporation; aliphatic hydrocarbons can be used as diluents only in limited amounts because they are non-solvents. Compared with poly(vinyl butyral), PVAc has lower tensile strength and lower impact toughness; compared with acrylic resins, it has lower hydrolytic stability and UV resistance but stronger adhesion to porous cellulosic substrates at equivalent plasticizer content. Published data for the specific peel strength of plasticized PVAc on low-energy films is limited.
In polyvinyl alcohol production, PVAc pellets are alcoholized in methanol using sodium methoxide or sodium hydroxide; the degree of hydrolysis is controlled by molar ratio and reaction temperature. Pelletized PVAc offers lower fines than powder, which reduces dust explosion hazard in the downstream hydrolysis reactor. However, alcoholysis requires dissolution in methanol at 60–65 °C; undissolved gel particles can reduce PVOH optical quality. The pellet form therefore must have uniform crystallinity-free morphology, and melt history is critical: pellets exposed to high shear and local temperatures above 190 °C may contain microgel that is difficult to dissolve.
PVAc-based adhesive layers respond to moisture by plasticization and, over extended exposure, hydrolysis of acetate side groups. Under EN 204 durability classification for wood adhesives, unmodified PVAc typically meets D1 and D2 service conditions but not D3 or D4 unless crosslinked or blended with phenolic or isocyanate hardeners. At 23 °C and 50% RH, a D2-grade PVAc bond may retain 7–10 MPa shear strength on beech, while after 4 h cold-water soak the strength falls below 2 MPa unless a crosslinker is present. Plasticizer selection governs low-temperature flexibility; dibutyl phthalate at 10 phr depresses the glass transition to about 5 °C, but migration to the bondline over 6 months can embrittle the interface. Triethyl citrate and benzoate plasticizers show lower migration in poly(vinyl acetate) films but reduce wet tack at high humidity. For bookbinding and paper lamination, archival specification often requires pH of an aqueous extract above 4.5 because acetic acid release can embrittle paper; accelerated aging is performed at 80 °C and 65% RH per ISO 5630-3.
Equipment selection for PVAc pellet compounding and dissolution should account for the polymer’s sensitivity to residence time and shear history. A corotating twin-screw extruder with segmented screws and atmospheric plus vacuum venting is preferred over a single-screw extruder, which may generate stagnation zones near the screw root and promote acetic acid accumulation. In dissolver vessels, baffle configuration is critical above 50 wt% solids because unmelted pellets can settle beneath the impeller and form a high-viscosity heel. Rotor-stator mills are sometimes used after dissolution to reduce fish-eye gels, and filtration through 60–100 µm screens is typical before coating application. The solubility limit in ethyl acetate at 25 °C is above 60 wt%, but solution viscosity becomes too high for slot-die coating above approximately 45 wt% depending on molecular weight.
