| HS Code | 616935 |
| Product Name | Ningxia Dadi PVA 2088 |
| Chemical Name | Polyvinyl alcohol |
| Cas Number | 9002-89-5 |
| Appearance | White powder or granules |
| Hydrolysis Degree Mol Percent | 88 |
| Viscosity Mpa S | 20.0-24.0 (4% aqueous solution, 20°C) |
| Ph Value | 5-7 |
| Volatile Content Percent | ≤5.0 |
| Ash Content Percent | ≤0.5 |
| Solubility | Soluble in hot water, partially soluble in cold water with swelling |
| Density G Per Cm3 | 1.27-1.31 |
| Melting Point Deg C | 180-230 (decomposes before melting) |
As an accredited Ningxia Dadi PVA 2088 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Ningxia Dadi PVA 2088 is packaged in 25 kg multi-layer woven bags, with 40 bags per pallet, totaling 1,000 kg. |
| Container Loading (20′ FCL) | 20′ FCL: Ningxia Dadi PVA 2088 packed in 25kg bags on pallets, securely loaded for safe transport. |
| Shipping | Ningxia Dadi PVA 2088 ships as non-hazardous, water-soluble polyvinyl alcohol in 25 kg multi-layer bags on pallets. Use sealed containers or dry containers with ventilation; avoid moisture, direct heat, and sharp objects. Standard handling and clean, dry storage ensure product integrity during transit. |
| Storage | Store Ningxia Dadi PVA 2088 in a cool, dry, well-ventilated area away from direct sunlight, heat, and ignition sources. Keep containers tightly sealed to prevent moisture absorption and contamination. Avoid generating dust; use appropriate grounding. Maintain temperatures below 30°C (86°F) and follow first-in, first-out rotation to preserve quality within shelf life. |
| Shelf Life | Shelf life: 2 years when stored sealed, in a cool, dry place, protected from moisture and sunlight. |
On high-speed air-jet and rapier looms weaving polyester/cotton shirting and denim constructions, Ningxia Dadi PVA 2088 is applied as a high-viscosity film-forming size component in the warp size formulation. The 4% aqueous solution viscosity of 20–26 mPa·s at 20 °C and the 87–89 mol% degree of alcoholysis produce a film with sufficient elongation to survive cyclic extension at the shed crossing. In a pure 2088 size mix, the solution concentration is maintained at 8–12 wt% dry solids; in starch/2088 blends, 2088 is dosed at 25–40 wt% of dry size solids, while the size-box temperature is held at 80–90 °C and the size liquor is cooked at 130–140 °C in a closed jet cooker. Size-box level dilution from residual wash water is a known source of add-on drift; a 0.5–1.0 wt% drop in size solids can increase warp hairiness on air-jet looms running above 1,200 rpm, so inline refractive-index or viscosity control is used on lines producing high-count blends. The downstream sizing process uses pre-wetting of the warp sheet followed by high-pressure squeeze nips to control wet pick-up at 8–12% of dry yarn mass, drying over 110–130 °C cylinder banks, and leasing before beam doffing. For cotton/polyester blends containing wax-like cotton components, a 2088/starch size formulation may require two-stage desizing: amylase for starch and hot-water washing at 70–80 °C for PVA removal; residual PVA can redeposit as an insoluble film if wash water temperature drops below 60 °C. Finished fabric compliance under OEKO-TEX Standard 100, Annex 4, applies after desizing; ZDHC MRSL v3.1 does not carry an explicit PVA prohibition in the recoverable size stream, but reclaim systems utilising ultrafiltration are recommended because PVA shows high chemical oxygen demand when discharged without recovery. Terminal product types include denim bottomweights, cotton/polyester shirting, bed sheeting, and twill workwear.
Paper surface sizing with partially hydrolysed 2088 operates within a narrow solids-viscosity window because the nominal 20–26 mPa·s 4% viscosity imposes pump shear limits in film press circulation lines. In a typical oxidized starch/2088 size formulation for wood-free printing paper, the total size solution solids are 4–8 wt%, with 2088 metered at 0.5–2.5 wt% of the total size solution; blending above 2.5 wt% can raise holdout but increases film split and doctoring load on metering rod stations, while starch-only solutions below 0.5 wt% 2088 often fail to meet IGT surface strength targets. The downstream process for fine paper runs a film press or puddle size press at 55–65 °C, followed by after-drying cylinders at 90–110 °C and a soft calender; size press solution viscosity is checked after starch cooking because thermomechanical starch degradation can shift the blend rheology and alter 2088 distribution in the metered film. For food-contact packaging board, the formulated sheet is evaluated under FDA 21 CFR 176.170 component migration requirements for paper and paperboard in contact with aqueous and fatty foods, and for general printing grades surface absorbency is measured by ISO 535:2014 Cobb60, while IGT surface strength is assessed according to ISO 3783:2013. Terminal product types include offset printing papers, inkjet recording base papers, release liner baseboard, and folding carton board.
When hydroxyethyl cellulose is replaced by 2088 as the protective colloid in vinyl acetate and VAE emulsion polymerisation, the reactor rheology at equal solids shows a measurable increase in latex viscosity and a narrower particle size distribution when the colloid is pre-dissolved. In a jacketed stainless-steel reactor with a pitched-blade turbine running at 80–120 rpm, a 10 wt% aqueous solution of 2088 is charged at 4–8 wt% based on total monomer mass for vinyl acetate homopolymerisation, or at 2–5 wt% on total monomer plus ethylene in low-pressure VAE systems. The polymerisation is maintained at 70–80 °C with delayed monomer feed over 3–5 h and a redox initiation pair of potassium persulfate/sodium metabisulfite; the presence of 2088 sterically stabilises the growing latex particles, and final particle size typically shifts to the 0.5–3.0 µm range depending on colloid loading and agitation shear. A charge below 2 wt% can produce coarse final latex and reactor wall fouling, while charges above 8 wt% raise reactor viscosity sufficiently to reduce heat transfer and extend cooling. The resulting polyvinyl acetate dispersions are classified for wood bonding according to EN 204:2016 durability classes, and adhesive films for indirect food-contact packaging are conditioned under FDA 21 CFR 175.105. Terminal product types include D2 and D3 interior wood adhesives, paper converting laminating adhesives, nonwoven binder dispersions, and interior architectural paint binders.
In suspension PVC plants operating stainless steel or glass-lined autoclaves of 50–100 m³ with top-entering impeller agitation, 2088 is dissolved in demineralised water before the vinyl chloride monomer is charged. The total dispersant package is typically held at 0.05–0.15 wt% of VCM, with 2088 constituting 20–40 wt% of the dispersant system; the remaining fraction is usually a lower hydrolysis grade near 72–74 mol% that governs primary particle size, while 2088 contributes secondary droplet stabilisation and influences final resin porosity and plasticizer absorption. Polymerisation for a K-value 66–68 resin is run at 56–58 °C with an organic peroxydicarbonate initiator and a water-to-VCM ratio near 1.1:1. Poor pre-dissolution of 2088 can produce gel aggregates that deposit on reactor baffles and cause fish-eye defects in the finished PVC; dissolution in water at 25–30 °C is therefore completed before charging. After pressure drop and degassing, the slurry is centrifuged and dried in a fluid bed at 55–65 °C. Residual vinyl chloride monomer in the dried resin is measured according to ISO 6401:2008; K-value and viscosity number are determined using ISO 1628-2:2020; and the finished PVC grade may be registered under REACH Regulation (EC) No 1907/2006. Terminal product types include rigid pipe and profile compounds, injection-moulded fittings, and flexible calendered sheet compounds.
A dry-mix cementitious tile adhesive line running a horizontal ploughshare mixer will incorporate 2088 at 0.2–0.8 wt% of total dry mix, always after pre-blending with silica sand and before addition of cement fractions. The downstream production process uses a mixing cycle of 5–15 min; moisture content of the finished dry powder is controlled below 0.3 wt% because 2088 has a high affinity for atmospheric humidity and lump formation can occur above 60% RH during bulk bag filling. When the dry mix is gaged with water at 20–25 °C, 2088 raises the cohesive strength of the fresh mortar and reduces skin formation on open assembly; however, because 2088 alone has limited resistance to alkaline hydrolysis in cement pore solution, it is not recommended as the sole water-retention polymer. Published data for freeze-thaw durability of 2088-only modified C2TE formulations is limited; therefore, formulators typically blend 2088 with a cellulose ether and a redispersible polymer powder. The hardened tile adhesive is tested for tensile adhesion after water immersion and heat ageing under EN 12004-1:2017 and EN 1348:2007, and for indoor emissions under the Eurofins or GEV EMICODE EC1 Plus scheme. Terminal product types include C2TE cementitious tile adhesives, external thermal insulation composite system base coats, and gypsum-based skim coats.
For PVP-free solid glue sticks, the hot-melt mixing sequence begins with the slow addition of 2088 into deionised water in an open steam-jacketed mixer at 85–90 °C; the formula comprises 8–12 wt% 2088, 5–10 wt% glycerin, 4–6 wt% sodium stearate, and deionised water to 100 wt%. The 2088 powder must be added slowly into the vortex with high-shear dispersion because rapid dumping can form gel aggregates that persist above 90 °C and block downstream filling nozzles. After a homogeneous molten mass is reached, the batch is deaerated under vacuum at −0.08 MPa to remove entrained air, then filled into lipstick-style moulds at 70–75 °C and shock-chilled in a cooling tunnel at 10–15 °C. For school and craft products intended for children, migration of soluble heavy metals from the cured stick is assessed according to EN 71-3:2019+A1:2021; for industrial office products, chronic health labelling requirements are evaluated under ASTM D4236-94(2021). Terminal product types include school glue sticks, office adhesive sticks, and craft-bonding solid adhesives.
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Ningxia Dadi PVA 2088 is a partially hydrolysed poly(vinyl alcohol) resin, CAS 9002-89-5, supplied as a white to pale-yellow granular powder. The grade designation 2088 follows the standard PVA nomenclature: 20 indicates a nominal degree of polymerisation of 2000, and 88 indicates a nominal alcoholysis degree of 88 mol%. The polymer therefore contains approximately 12 mol% residual acetate side groups. These residual groups interrupt the regular hydrogen-bonded poly(vinyl alcohol) crystal lattice and reduce the dissolution temperature relative to fully hydrolysed grades such as 1799 and 2099. The nominal repeat-unit mass calculated from the vinyl alcohol repeat unit, 44.05 g mol⁻¹, and vinyl acetate repeat unit, 86.09 g mol⁻¹, is approximately 49.1 g mol⁻¹; the nominal average molar mass is therefore near 9.8 × 10⁴ g mol⁻¹. Producer specification limits for the grade are summarised below.
| Property | Method | Specification |
|---|---|---|
| Appearance | Visual inspection | White to pale-yellow granules or powder |
| Alcoholysis degree | GB/T 12010.5-2010 | 87.0–89.0 mol% |
| Dynamic viscosity, 4% aqueous solution at 20 °C | GB/T 12010.3-2010, NDJ-1 rotational viscometer | 20.0–26.0 mPa·s |
| Volatile matter | GB/T 12010.2-2010 | ≤5.0 wt% |
| Ash content | GB/T 12010.2-2010 | ≤0.5 wt% |
| pH, 4% aqueous solution at 20 °C | GB/T 12010.4-2010 | 5.0–7.0 |
Viscosity and alcoholysis degree are the two most consequential incoming-lot parameters. They determine solution preparation, machine pickup, film formation, and desizing or remoistening behaviour downstream.
Grade 2088 occupies the intermediate-viscosity band between 1788 and 2488. Compared with 1788, the higher polymerisation degree raises solution viscosity at equal solids and increases the cohesive strength of dried films; this improves yarn hairiness suppression in warp sizing but reduces penetration into dense paper stock. Compared with 2488, 2088 gives lower viscosity at equal solids, permitting higher size-press or adhesive solids without excessive machine loading. Compared with fully hydrolysed grades such as 1799 or 2099, the 88 mol% hydrolysis level of 2088 provides faster dissolution at moderate temperature, lower hot-water resistance, and easier removal in conventional desizing. The residual acetyl groups reduce film crystallinity, lower tensile modulus, and increase elongation. In applications requiring water-resistant bonds, fully hydrolysed grades or crosslinked systems should be selected instead.
At production scale, the preferred dissolution sequence for 2088 is cold-water dispersion before heating. The powder is dispersed at 20–25 °C into deionised water at 8–12 wt% solids using a low-speed paddle or anchor agitator at 60–80 rpm. Direct addition to water above 50 °C forms gel clumps that are not recoverable by later heating. The dispersion is heated to 88–92 °C and held for 45–60 min; this is a narrow processing window because dissolution below 85 °C leaves fisheye particles, while extended holding above 95 °C accelerates oxidative chain scission and colour development. The finished solution is cooled to 60–65 °C and strained through a 100–150 µm bag or slotted-screen filter. Tanks and lines are preferably 316L stainless steel; copper, brass, and unlined carbon steel should be avoided because PVA solutions and trace acetates can stain the solution and generate metallic contamination. At relative humidity above 60%, dry powder can absorb moisture and cake; the original packaging should be closed immediately after use, and storage below 30 °C in a dry area is recommended.
On a conventional single-size-box slasher running spun polyester/cotton warps at 60–80 m/min, PVA 2088 is typically applied at size solids of 8.0–10.0 wt%. The size-box temperature is maintained at 85±3 °C. Sized-yarn breaking tenacity and elongation can be monitored according to ASTM D2256-22; yarn abrasion resistance is commonly checked on a Zweigle yarn-abrasion tester or equivalent laboratory abrasion rig. The intermediate viscosity of 2088 provides enough binder for hairiness control without requiring excessive squeeze pressure, which can crush the size film and generate lint. Desizing of sized fabric in hot water at 70–80 °C for 10–15 min generally removes the size without oxidative treatment, because the residual acetate groups maintain water sensitivity. This is an operational advantage where mill effluent limits oxidant use. Size formulations containing denatured starch or acrylic size should be evaluated for phase separation at the size-box temperature, because PVA 2088 and high-amylose starch can form cloudy two-phase mixtures if the cooking sequence is reversed.
In water-based paper and packaging adhesives, PVA 2088 is used at solution solids between 10 wt% and 20 wt%. Plasticisers such as glycerine, sorbitol, or polyethylene glycol 400 are added at 5–15 parts by weight per hundred parts of PVA to reduce dry-film brittleness. Borax or boric acid can be used at 0.5–1.5 wt% of solution to increase tack and build viscosity by reversible borate complexation; above 2.0 wt% or at pH above 8.5, the solution may gel irreversibly during storage. Viscosity should be measured on a Brookfield RVT or equivalent rotational viscometer according to ISO 2555:2018 at 25 °C. Paper-bond performance can be evaluated as 180° peel strength per ASTM D903-17. The open time and wet tack are controlled by water content and humectant level; at high relative humidity, films remain tacky because of plasticisation by moisture. The grade is not recommended for exterior wood bonds unless crosslinked.
During emulsion polymerisation of vinyl acetate-ethylene or vinyl acetate-acrylic systems, 2088 is pre-dissolved in the aqueous phase at 4.0–6.0 wt% on total reactor charge. The solution is charged to a jacketed reactor with anchor or pitched-blade agitation at 60–80 rpm. Polymerisation is typically initiated with persulfate or a redox couple at 70–80 °C. The higher molecular weight of 2088 compared with 1788 increases the viscosity of the seed and final emulsion at constant solids; this can improve roll-coating film build but may reduce spraying ease. Final emulsion viscosity is measured according to ISO 2555:2018; particle-size distribution is determined by laser diffraction according to ISO 13320:2020. In production-scale batches, the target final viscosity and particle size depend on monomer ratio, initiator level, and post-stabiliser addition; data for a specific reactor configuration must be confirmed by pilot runs. Films cast from emulsions stabilised only with 2088 retain water sensitivity because the protective colloid is hydrophilic. For water-resistant coatings, post-crosslinking with glyoxal, glutaraldehyde, or a blocked acid catalyst is required.
At the size press of fine-paper machines, 2088 is commonly co-applied with oxidised starch at a dry ratio of 1:3 to 1:1. A combined size-press bath solids of 4.0–6.0 wt% can increase IGT pick resistance measured according to ISO 3783:2016 and reduce linting tendency on offset printing units. Oil holdout is assessed by kit testing according to TAPPI T 559 cm-12; films from partially hydrolysed PVA provide reasonable oil and grease holdout but are not moisture barriers. Water absorption measured according to ISO 535:2014 may be higher than that obtained with fully hydrolysed PVA grades. Filtration through 100 µm slotted strainers before the size press prevents streaking from undissolved gel particles. The grade can be used as a sole surface-size film former, but cost and solution viscosity normally favour starch blends.
Cast films prepared from a 12 wt% solution and dried at 23 °C and 50% RH for 7 days according to ISO 291:2008 can be tested under ISO 527-3:2018. Published data for this specific Ningxia Dadi configuration is limited; comparative literature for 88 mol% PVA films commonly places tensile strength in the 35–50 MPa range and elongation at break in the 150–250% range. These values shift significantly with moisture: at higher relative humidity the film plasticises, tensile strength falls, and elongation increases. The mechanical response is relevant to temporary paper coatings and release-free interleaving films where tear propagation and blocking must be controlled.
In cementitious tile adhesives and gypsum-based compounds, PVA 2088 is occasionally used as a secondary polymer modifier or as the water-soluble protective colloid in spray-dried redispersible polymer powders. The benefit is process-related: the grade raises water-retention and slip resistance during trowelling. However, technical-grade PVA alone is not a substitute for a formulated redispersible polymer powder, because films are water-sensitive and cement compatibility varies with aggregate alkali content. Published data for this specific configuration is limited; trials should include compressive strength testing per ISO 679:2009 or equivalent mortar standards, and open-time evaluation per EN 1346:2007 for tile adhesives.
Aqueous solutions of 2088 held at 90–95 °C for more than 6–8 h can undergo measurable viscosity loss and yellowing, particularly if the solution is exposed to air. In a 12 wt% solution, viscosity can drift more than 10% during an 8 h hot hold; sealed or nitrogen-blanketed vessels reduce the drift. At temperatures above 95 °C, the rate of chain scission increases and odour development may occur. For this reason, continuous size press or coating supply should be prepared as day-use batches and cooled below 65 °C when holding is unavoidable. Biocide addition is required if cooled solutions are stored beyond 24 h. Strong mineral acids, strong alkalis, and certain amine-based additives are generally incompatible with PVA solutions because they accelerate hydrolysis or crosslinking. Dry powder handling requires dust control and earthing of transfer lines because PVA fines can form combustible dust clouds. Technical-grade PVA 2088 must be verified against the applicable regulatory schedule, such as 21 CFR 175.105 or 21 CFR 176.170, before use in direct food-contact formulations.
