| HS Code | 523740 |
| Product | Shuangxin SX-I PVA |
| Chemical Name | Polyvinyl alcohol |
| Cas Number | 9002-89-5 |
| Appearance | White or slightly yellow granular powder |
| Degree Of Hydrolysis | 88-99 mol% |
| Viscosity 4 Aqueous Solution 20 C | 20-60 mPa·s |
| Ph | 5.0-7.0 |
| Ash Content | ≤ 1.0% |
| Volatile Content | ≤ 5.0% |
| Average Degree Of Polymerization | 1700-2500 |
| Density | 1.19-1.31 g/cm³ |
| Melting Point | 230°C (decomposes) |
| Solubility | Soluble in hot water, insoluble in most organic solvents |
| Refractive Index | 1.49-1.53 |
As an accredited Shuangxin SX-I PVA factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Shuangxin SX-I PVA is packaged in 25 kg multi-wall paper bags with PE inner lining, labeled and sealed. |
| Container Loading (20′ FCL) | Shuangxin SX-I PVA loaded in 20′ FCL, palletized, secured, moisture-proofed, and ventilated for safe transport. |
| Shipping | Shuangxin SX-I PVA ships as a dry, free-flowing granular solid in sealed multi-layer bags or woven sacks. Keep dry, away from moisture and direct heat during transit. No hazardous classification for general freight, but avoid dust inhalation and use clean, covered containers. |
| Storage | Store Shuangxin SX-I PVA in a cool, dry, well-ventilated area, away from direct sunlight, heat, and ignition sources. Keep containers tightly closed to prevent moisture absorption and contamination. Avoid dust accumulation. Use appropriate personal protective equipment when handling. Maintain stable temperatures, and follow manufacturer’s guidelines for shelf life and disposal. |
| Shelf Life | Shelf life is typically 12 months when stored unopened in a cool, dry place away from moisture. |
For air-jet weaving, a size film must withstand high-frequency whip loading at shed crossing without developing powder deposits in reed or drop wires. Shuangxin SX-I PVA is jet-cooked at 95–105 °C for 20–30 min and then blended with a starch or vinyl ester size mixture at 8–10% dry solids. On dry fiber, the PVA addition is 0.8–1.2 wt% of the warp yarn, with PVA:starch ratio between 20:80 and 40:60 depending on fiber type and loom speed. Wax content is limited to 8–12 wt% of PVA solids to avoid desizing residues. The size liquor is applied on a pre-wetting or dry-warp sizing machine with cylinder drying temperature controlled at 120–140 °C; size-box solids are held within ±0.5% of target to prevent doctor-blade chatter. Viscosity of the cooked liquor at 20 °C is maintained between 25 and 40 mPa·s per DIN 53019-1. Isolated size film tensile properties are measured by ASTM D882, while warp yarn tensile retention after sizing is measured by ASTM D2256/D2256M-21. The finished woven greige fabric is desized in an open-width washer at 80–90 °C using a mild oxidative or amylase scour. Desizing efficiency is confirmed by iodine staining. Compliance for textile chemical inputs is assessed under REACH 1907/2006 and OEKO-TEX Standard 100 listed limits where applicable. The operational boundary is storage humidity: PVA size film softens above 75% RH, and at loom speeds above 900 picks/min insufficient film cohesion may produce reed deposits if the PVA:starch ratio falls below 20:80.
Surface sizing of coated duplex board with Shuangxin SX-I PVA is carried out at the size press after clay coating, where PVA functions as an oil-resistance binder and pick-strength improver. In a film press or gate-roll metering unit, the PVA/starch size solution is maintained at 55–65 °C with a Brookfield viscosity of 15–25 mPa·s at 65 °C per ISO 2555. The addition level is 0.5–1.5 wt% of dry fiber, replacing 10–30% of oxidized starch. PVA is pre-dissolved in a separate side tank at 8–10% solids and fed continuously to the size press head tank; pH is held between 6.5 and 7.5. At pH above 8.0, optical brightener carry-over can shift sheet brightness and increase blade deposits. Surface strength of the finished board is tested by IGT pick resistance per ISO 3783, and water absorbency by Cobb test ISO 535. For food-contact board, the final coated board is assessed under FDA 21 CFR §176.170 and EU 10/2011 when intended for aqueous and fatty food contact. The processed sheet is calendered at linear pressure 40–80 kN/m and surface temperature 60–80 °C. The terminal printed board is used for sheetfed offset packaging; print mottle is reduced when the PVA/starch size film has surface energy below 36 mN/m. An acute process conflict occurs at blade metering: high-hydrolysis PVA above 1.5 wt% of dry fiber can raise viscosity above 25 mPa·s and produce transverse blade streaks. Therefore side-tank age is limited to 12 h to avoid microbial viscosity loss.
Continuous vinyl acetate-ethylene emulsion feeds place a narrow window on protective colloid concentration because excess PVA raises water sensitivity of the redispersible film, while insufficient PVA permits coagulum formation in the reactor. Shuangxin SX-I PVA is pre-dissolved at 5–10 wt% solids in deionized water and charged at 3–7 wt% on total monomer, with the exact level tied to ethylene pressure and particle size target. The polymerization is run at 60–80 °C and 2.0–4.0 MPa ethylene partial pressure in a stirred stainless steel reactor with turbine impeller tip speed 2.2–3.2 m/s. Oxidant and reducing agent are fed separately; pH is maintained at 3.5–5.5 to minimize hydrolysis of vinyl acetate. The resulting latex has particle size 0.5–2.0 µm, solids 50–55%, and Brookfield viscosity 1,000–3,000 mPa·s at 25 °C per ISO 2555. Coagulum is filtered through 250 µm screens; screen residue greater than 0.1% indicates protective colloid starvation. The latex is spray-dried at inlet air 120–160 °C and outlet air 70–90 °C with anti-blocking filler to produce a redispersible polymer powder. In dry-mix tile adhesives, powder dosage is 1.5–3.0 wt%; tensile adhesion after water immersion is measured per EN 12004. Organic volatile content and ash of the powder are checked per ISO 3251 and ISO 3451-1. The terminal product is a C2-type or S1-type cementitious tile adhesive. Incompatibility: borate-containing retarders gel high-hydrolysis PVA and must not be added before spray drying. The process boundary is hydration rate: at reactor solids above 55%, shear stability declines and the product may destabilize during spray-dry feed tank hold.
Shuangxin SX-I PVA is suitable for cast or blown water-soluble film only after pre-drying to 0.3–0.5 wt% moisture and compounding with a plasticizer such as glycerol, sorbitol, or trimethylolpropane at 15–30 wt% of resin. The powder is fed to a co-rotating twin-screw extruder with L/D 30:1 or 40:1, screw speed 180–300 min⁻¹, and barrel temperatures from 160 °C at the feed throat to 205 °C at the die; residence time is limited to 90–120 s to avoid acetalization and yellowing. Cast film is drawn to thickness 25–75 µm over a chill roll at 10–20 °C. Film tensile properties are measured on ISO 527-3 specimens cut in machine direction and transverse direction; a typical high-hydrolysis film has tensile strength 20–40 MPa and elongation at break 150–300%, but published data for this specific SX-I configuration is limited. Cold-water disintegration is evaluated in a standard laundry machine at 10 °C and 30 °C; dissolution below 10 °C can exceed 120 s unless a disintegrating agent is added. The finished unit-dose product must resist alkaline liquid detergents at pH 8.0–10.0 without embrittlement; amine-based additives must be avoided because they can promote premature crosslinking and reduce water solubility. Barrier compliance for the film itself is assessed under EU 10/2011 and FDA 21 CFR §177.1670 where food-contact or household product packaging is claimed. Handling boundary: at storage RH above 60%, unopened film reabsorbs moisture and blocking occurs; the film must be wound with interleaving and packed in moisture-barrier pouches within 24 h of slitting.
Shuangxin SX-I PVA is introduced into aqueous ceramic slips at 1.0–2.0 wt% of alumina solids for tape casting, where the binder must provide green strength without raising drying shrinkage above the tape-carrier release limit. The ceramic slurry is prepared at 55–65 wt% solids in deionized water with ammonium polyacrylate dispersant at 0.2–0.5 wt% on solids, plasticizer PEG 400 at 0.5–1.5 wt%, and PVA solution added slowly under high-shear mixing. Ball milling with 5 mm yttria-stabilized zirconia media continues for 16–24 h; after milling, slurry viscosity is adjusted to 1,500–3,000 mPa·s at 20 s⁻¹ shear rate per ISO 3219. Tape casting uses a doctor blade gap of 200–600 µm and carrier speed 0.5–2.0 m/min; the drying tunnel is zoned from 60 °C to 80 °C. The green tape is cut and laminated to produce alumina substrates. Binder burnout is carried out in a box furnace from 200 °C to 600 °C at a heating rate not exceeding 1 °C/min; faster ramp rates generate internal gas pressure and delamination at the laminate interface. Ash content of Shuangxin SX-I PVA after burnout below 0.5 wt% is critical for electrical substrates; residue is checked by ASTM D5630. Green flexural strength of the tape is tested after conditioning at 25 °C and 50% RH using ASTM C1161 or a three-point bend fixture; the value should exceed 5 MPa for punching and via filling. Incompatibility is observed with soluble borates and high-valence cations, which cause slump and gelation. The terminal product is a thin alumina substrate for thick-film electronic circuits, requiring sintered density above 96% of theoretical.
Corrugated board adhesive systems use Shuangxin SX-I PVA as a supplement to carrier starch when line speeds exceed 150 m/min and green bond must develop before the cut-off knife. The adhesive is prepared with 20–28 wt% corn or wheat starch, 0.5–1.0 wt% sodium hydroxide, 0.1–0.3 wt% borax, and 1.0–3.0 wt% PVA on total wet adhesive. PVA is pre-dispersed in cold water at 25–35 °C without steam and added to the starch carrier after batching; pH is held at 6.0–7.5. The adhesive viscosity is 150–400 mPa·s at 25 °C per ISO 2555. Above 3 wt% PVA, the starch slurry shear-thickens and transfer roll filming becomes uneven; below 1 wt%, no measurable green bond gain is observed. Bond strength is measured on conditioned board per TAPPI T 821; wet bond is evaluated after water spray at 25 °C. The finished product is double-wall corrugated sheet with flat crush and edgewise crush specifications per ISO 3035 and ISO 3037. For food-contact corrugated packaging, the adhesive is cleared under FDA 21 CFR §175.105. Incompatibility: borax above 0.3 wt% reacts with high-hydrolysis PVA to form a gel network and must not be added to the PVA pre-blend; it is added only to the starch carrier phase. The process boundary is cold-water hydration: without jet cooking, undissolved PVA particles can transfer through the applicator and create pinhole bond lines; therefore the pre-dispersion is passed through a 150 µm screen and held for 30 min before use.
In PVB synthesis, the particle size and residual chloride of the precipitated acetal are governed by the degree of polymerization of the starting PVA and the rate of butyraldehyde addition. Shuangxin SX-I PVA is dissolved at 8–10 wt% in demineralized water at 90–95 °C, cooled to 40–60 °C, and reacted with n-butyraldehyde at a molar ratio of 0.55–0.65 mol per vinyl alcohol unit in the presence of hydrochloric acid at 0.5–1.0 wt% on aqueous phase. The reaction is carried out in a glass-lined stirred reactor with acid-resistant baffles and a controlled precipitation step. Degree of acetalization is targeted at 70–80%. The slurry is neutralized, washed, and dewatered in a centrifuge until residual chloride is below 50 ppm. The dried PVB resin is dusted with an anti-blocking agent and screened to a controlled particle size distribution. Film-grade PVB is then plasticized and extruded into interlayer sheet for laminated safety glass. Optical and mechanical compliance is evaluated under ISO 12543-2 and ECE R43 for glazing; the resin itself is supplied under REACH 1907/2006 registration. The process conflict is precipitation control: if butyraldehyde is added faster than the reactor can disperse it, coarse gel particles form and the dried resin may exhibit haze after plasticization. Therefore butyraldehyde feed is limited to 30–60 min per batch with continuous pH monitoring and agitator tip speed above 1.5 m/s.
Competitive Shuangxin SX-I PVA prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please contact us at +8615380400285 or mail to sales2@liwei-chem.com.
We will respond to you as soon as possible.
Tel: +8615380400285
Email: sales2@liwei-chem.com
Flexible payment, competitive price, premium service - Inquire now!
Shuangxin SX-I PVA is a partially hydrolysed polyvinyl alcohol resin produced by continuous alcoholysis of vinyl acetate polymer. The SX-I designation identifies an intermediate-viscosity grade within the producer's SX series, with an acceptance window of 86.0–89.0 mol% for degree of hydrolysis and 11.0–14.0 mol% residual acetate content. Viscosity is specified as 20.0–26.0 mPa·s for a 4% aqueous solution at 20°C using a capillary viscometer according to DIN 53015. The product is supplied as white to off-white granules with bulk density of 0.45–0.60 g/cm³, volatile matter ≤ 5.0%, and ash ≤ 0.5% on dry weight. Primary application areas include textile warp sizing, paper surface sizing, emulsion polymerisation stabilisation, and water-sensitive film formation.
Because the residual acetate content remains between 11.0 and 14.0 mol%, the polymer retains sufficient crystallinity for mechanical strength but dissolves in cold-to-warm water without the 90–95°C cooking requirement typical of fully hydrolysed 98–99 mol% grades. This position within the hydrolysis-viscosity matrix is selected when film flexibility and surface wetting are more important than maximum water resistance.
Dissolution rate is controlled by particle dispersion before heating. When dry granules are introduced directly into water above 60°C, surface hydration forms a swollen gel layer that slows water ingress and produces undispersed gel aggregates. To avoid this condition, SX-I is pre-slurried in cold water at 30–40°C at 10–15% solids with agitation in a baffled tank. The slurry is metered into a jet cooker or jacketed dissolution vessel maintained at 85–95°C with a rotor-stator mixer operating at a tip speed of 15–20 m/s. Complete dissolution is typically achieved within 30–45 min, after which the solution is filtered through a 100–150 μm screen. Holding the solution at 90°C beyond 2 h can reduce viscosity through chain scission, particularly when pH falls outside 5.0–7.0.
Continuous warp sizing lines dilute the cooked concentrate to 8–12% solids and control size box temperature at 75–85°C. Viscosity in the size box is maintained between 60 and 120 mPa·s at the specified temperature, depending on yarn type and add-on target. For polyester/cotton blends, SX-I is commonly combined with corn starch or acrylic size; starch addition is controlled below 30% of total solids to avoid phase separation and size-box skinning. Borate crosslinkers are not recommended because they raise viscosity non-linearly and reduce later desizing efficiency.
Batch-to-batch variation in dissolution time can result from changes in particle size distribution. Coarse fractions above 500 μm require longer wetting. Storage above 60% relative humidity increases moisture content and can cause caking in the feed hopper; pre-drying at 105°C for 2 h is required when moisture exceeds 0.5%.
On a dry basis, analytical release testing for SX-I is performed against the following representative acceptance values. Where a local regulatory or customer specification requires a different method, the value is confirmed against the lot-specific certificate.
| Property | Acceptance range | Reference method |
|---|---|---|
| Degree of hydrolysis | 86.0–89.0 mol% | Alkaline saponification titration |
| Viscosity, 4% aqueous, 20°C | 20.0–26.0 mPa·s | DIN 53015 / GB/T 12010.3 |
| Volatile matter | ≤ 5.0% | ISO 760 |
| Ash, dry basis | ≤ 0.5% | ISO 3451-1 |
| pH, 4% aqueous solution | 5.0–7.0 | GB/T 12010.7 |
| Bulk density | 0.45–0.60 g/cm³ | ISO 60 |
In textile warp sizing, SX-I is applied from a single-size box or twin-size box slasher at solids of 8–12% and box temperature 75–85°C. For spun cotton yarns, the size add-on is controlled between 8% and 14% on dry yarn weight, while for polyester/cotton blends the target is 6–10%. Weaving efficiency is influenced by size film cohesion and adhesion; adhesion to polyester is improved by the residual acetate content. High-humidity weaving rooms above 85% relative humidity may soften the PVA size film, so an acrylic co-binder is often added. Desizing in hot water at 60–80°C with 0.5–1.0% sodium hydroxide achieves film breakout; residual PVA is quantified by iodine-borate complex spectrophotometry after desizing.
SX-I is prepared as a 3–6% solids solution for paper surface sizing and is applied at a size press or film press. The coating bath is maintained at 50–60°C, yielding a Brookfield LVT viscosity of 10–30 mPa·s with a No. 2 spindle at 60 min-1. The lower degree of hydrolysis reduces surface tension and improves wetting of alkaline paper surfaces compared with fully hydrolysed grades. Film formation at the size press improves IGT pick resistance measured according to ISO 3783 and reduces Cobb water absorption according to ISO 535; the extent of reduction depends on base sheet porosity, size press solids, and drying profile. For corrugating medium and linerboard, SX-I is co-formulated with starch at 1:3 to 1:4 PVA-to-starch solids ratio to raise ring crush strength without excessive sheet stiffening. Published data for this specific SX-I configuration in all board grades is limited, so mill-scale trials at single-facer and double-backer positions are conducted before changing the size press formulation.
Following substitution of SX-I for a 98–99 mol% hydrolysed grade, the crystalline fraction is reduced and the dissolution temperature of cast film shifts from the 80–95°C range to the 25–40°C range. This change is attributable to residual acetate groups that disrupt interchain hydrogen bonding. For film prepared by solution casting and conditioned at 23°C and 50% relative humidity, tensile strength measured according to ASTM D882 typically falls between 40 and 55 MPa for SX-I, while elongation at break is in the range of 120–180%. Fully hydrolysed film of similar degree of polymerisation typically exhibits tensile strength above 60 MPa and elongation below 100%. The lower strength is offset by easier cold-water solubility and reduced thermal load during film forming.
In barrier coating formulations, the partially hydrolysed grade has higher gas permeability and lower water vapour barrier performance than fully hydrolysed PVA. Oxygen transmission rates therefore increase when the hydrolysis degree drops, so SX-I is not a direct drop-in where minimal oxygen permeability is required under ASTM D3985. It is selected where cold-water removability or substrate adhesion is a requirement.
| Property/condition | SX-I | Fully hydrolysed PVA | Low-viscosity 88 mol% grade |
|---|---|---|---|
| Degree of hydrolysis | 86.0–89.0 mol% | 98.0–99.0 mol% | 86.0–89.0 mol% |
| Viscosity, 4%, 20°C | 20.0–26.0 mPa·s | 25.0–31.0 mPa·s | 5.0–8.0 mPa·s |
| Cold-water dissolution | 25–40°C | 80–95°C | 20–30°C |
| Film tensile strength, ASTM D882 | 40–55 MPa | 60–75 MPa | 35–45 MPa |
| Water resistance | Moderate | High | Moderate |
| Primary processing role | Warp sizing, paper surface sizing | Barrier films, high-water-resistance adhesives | Emulsion polymerisation protective colloid |
Emulsion polymerisation stabilisation with SX-I begins with dissolution in the aqueous phase at 2–6% of the monomer mass. The grade influences latex particle-size distribution; higher molecular weight fractions increase final latex viscosity and shear-thinning behaviour. Residual acetate groups permit grafting with vinyl acetate during polymerisation, lowering surface tension and stabilising latex against freeze-thaw cycles. In a pilot reactor with a 4-blade pitched turbine and monomer delay time of 3 h, substitution of low-viscosity PVA by SX-I raises final latex viscosity and may shift the volume-mean particle diameter from 250–350 nm to 400–600 nm. Under these conditions the polydispersity index measured by dynamic light scattering according to ISO 22412 is monitored; values above 0.20 indicate secondary particle nucleation or insufficient stabiliser.
For paper and board intended for food contact, SX-I is evaluated under the end-use conditions described in 21 CFR 176.170, which covers components of paper and paperboard intended for contact with aqueous and fatty foods. The polymer is applied as part of a sizing or coating layer rather than as a discrete plastic article, so compliance depends on the total extractives from the finished paper, not on the resin alone. Migration testing is performed according to EN 1186-1 with an overall migration limit of 10 mg/dm² for food contact materials under Regulation (EU) No 10/2011 where applicable. Residual monomer and process aid levels are verified by the converter because polymer-bound vinyl acetate residues may contribute to sensory thresholds. Published data for this specific SX-I configuration in all food-packaging structures is limited; therefore, end-use migration testing on the final formed article is completed before commercial use.
Storage of SX-I in paper bags or bulk silos is maintained below 60% relative humidity at 5–35°C. The free-flowing granular powder can cake when exposed to ambient moisture above this threshold for more than 24 h. If moisture content exceeds 5.0%, drying at 105°C for 2 h is required before extrusion or film casting because excess water causes bubble defects and torque fluctuations in twin-screw compounding. In dry blending, SX-I is not combined with borate ions, aldehydes, or strongly acidic additives; borate crosslinking increases viscosity non-linearly and can form gels in static mixers. For textile warp sizing, desizing with sodium hydroxide or hydrogen peroxide remains feasible after film formation; enzymatic desizing is effective only after oxidative or alkaline breakout of the PVA film.
