In high-speed weaving of ring-spun cotton yarns with counts between
Ne 30 and
Ne 60, a size that penetrates the yarn core yet leaves a tough, abrasion-resistant surface film determines loom efficiency and warp breakage rates under combative shedding conditions on air-jet looms operating beyond
1,200 picks/min. Sinopec PVA
100-78—a fully hydrolysed grade delivering a Brookfield LVF viscosity of
72–78 mPa·s at
20°C and
4% aqueous solution, with saponification degree ≥
99.5 mol% per manufacturer’s certificate of analysis—is dissolved at
95–98°C in a continuous jet cooker equipped with an in-line high-shear rotor-stator (typical tip speed
18–25 m/s) to obtain a defect-free stock solution at
12–18% solids. The formulation is completed by blending this PVA size with acid-thinned corn starch (fluidities
70–80 WF) and a polyacrylate co-binder (e.g., an ammonium salt of a methacrylic acid–ethyl acrylate copolymer) in a ratio of
40 : 50 : 10 on dry-weight basis, with
0.5–1.0% of a PEG-400 plasticiser and
0.1% of a silicone-based defoamer added to the final size mix to suppress foam in the supply box under turbulent circulation. Viscosity of the size liquor measured at
85–90°C via an automatic viscometer (e.g., VaCoSens or Prüftechnik online unit) is held within
8–14 mPa·s by adjusting the solids content; a sustained drop below
7 mPa·s indicates thermal-mechanical degradation of PVA chains and requires immediate makeup. The size is applied on a pre-wet split-sheet sizing machine (e.g., Karl Mayer or Zell RKM system) with a squeeze pressure of
12–18 kN/m to achieve a size add-on of
10–14% on Ne
40 combed cotton warps. Dried cans are profiled in four temperature zones from
110°C to
140°C, with residual size film moisture maintained below
6% to prevent blocking during lease-to-release beam winding. The resulting sized yarns exhibit an abrasion resistance increase of at least
200% against a standard reciprocating yarn-on-yarn wear tester per
ASTM D2256/D2256M-21 §12, while desizing in a pad-batch enzyme bath (α-amylase
0.5–1.0 g/L at
65°C for
6–8 h) removes ≥
99% of the PVA film without alkali-boiling, meeting the restricted substance lists of
OEKO-TEX® Standard 100 Annex 4 when a heavy-metal-free catalyst was used in the PVA polymerisation. End fabrics from these warps include high-density downproof cotton shell fabrics and mercerised shirtings, where the elimination of size film defects translates to a first-quality dye uptake at a
ΔE ≤ 0.8 across loom widths.
What Makes 100% Hydrolysed PVA Viable for Structural Wood Adhesives Under EN 204?
For humidity-resistant assembly of hardwood edge-glued panels and laminated veneer lumber, PVA
100-78 furnishes an aqueous polymer matrix whose glass transition temperature of
73–76°C (DSC,
20 K/min) and degree of crystallinity near
42% impede cold-creep while permitting thermal reactivation during hot pressing. The adhesive is prepared by dispersing
14 kg of PVA granules in
86 kg of demineralised water, swelling for
30 min at ambient temperature, then heating under vacuum mixing to
93–96°C in a jacketed planetary mixer (e.g., Ross VMC-100) until the solution is entirely free of visible gel particles. From this base, a D3-grade formulation is compounded by adding
8–12 phr of a blocked polyisocyanate emulsion (NCO content
5–7%, deblocking onset
65°C) and
2–4 phr of fumed silica (BET
200 m²/g) as a thixotrope, while a D4-type crosslinked system incorporates
3–5 phr of ammonium zirconium carbonate (AZC) solution at
20% solids, buffered with triethanolamine to pH
9.2–9.8 to extend working life beyond
90 min. At this pH, premature gelation is delayed because the active zirconium species remain coordinated, whereas a drop below pH
8.5 induces instantaneous crosslinking and unusable stringing. The mixed adhesive is applied via a double-roller spreader (approx.
3–5 mm gap, coating weight
140–180 g/m²) onto beech or oak lamellae conditioned to
8–10% moisture content; under a cold-press cycle of
0.8–1.2 MPa for
45–60 min, followed by a hot-press stage at
90–100°C for
5–8 min, the AZC-crosslinked film develops a solvent-insoluble fraction exceeding
55% when extracted in boiling water for
6 h per
EN 204:2016 §5.4.1. A systematic comparative data set is presented in the table below.
| Crosslinker Type & Loading (phr) | Dry Shear Strength (EN 205) [MPa] | Wet Shear (24 h/23°C immersion) [MPa] | 7-day Cyclic D4 Rating |
|---|
| None (thermoplastic H-PVA only) | 12.8 | 3.1 (delamination) | Fail |
| Blocked pMDI (10 phr) | 16.4 | 8.7 | D3 pass (≥ 6.0 MPa) |
| AZC (4 phr, pH 9.5) | 15.2 | 11.3 | D4 pass (≥ 8.0 MPa) |
| Glyoxal (4 phr) | 13.9 | 5.6 (film embrittlement at knots) | D3 marginal |
Operational boundaries must be respected: wood surface temperature during adhesive application must not fall below
10°C to avoid film-forming temperature collapse; the AZC-crosslinked system is incompatible with strong anionic surfactant carriers, which displace zirconium ligands and degrade wet-strength retention below
50%. Avoid combination with primary amine-functionalised co-additives (e.g., amino silanes) that trigger premature crosslinking in the pot. The final products, ranging from solid wood tabletops to load-bearing laminated beams, are tested according to
EN 12765:2016 for classification C1 to C4 service classes, with the described formulation achieving C3 permanence under combined humidity and temperature cycling.
Alkaline Surface Sizing in Fine Paper Production
In mill-scale operations on a Valmet OptiSizer equipped with a film-transfer applicator, an alkaline surface-sizing liquor containing high-viscosity fully hydrolysed PVA strengthens the stock surface and suppresses dusting of uncoated woodfree sheets destined for high-voltage insulating papers and grease-resistant folding cartons. The size press formulation is built by cooking PVA
100-78 to an
11% solution at
93–96°C, then diluting with an oxidised cassava starch slurry (carboxyl content
0.15–0.25%) to a final weight ratio of
1 : 2.5 PVA-to-starch and a total solids of
9–12%. The elevated film-forming temperature of the fully hydrolysed grade—its dissolution temperature in water is
>88°C—demands that the size press sump be jacketed and held at
60–65°C during circulation to prevent skinning on transfer rollers, a process constraint that low-viscosity partially hydrolysed grades do not impose. Calendered reels exiting the dryer section at a moisture of
5–6% and a Cobb
60 value (
ISO 535:2014) of
22–28 g/m² exhibit an IGT pick velocity above
3.4 m/s when tested with medium-tack oil per
ISO 3783:2006, a measurable increase over the starch-only control which typically fails at
2.0–2.4 m/s. This improvement is accompanied by an ash-binding effect that reduces linting tendency in laser-printer converting, measured by a scotch-tape pickup test (
TAPPI T 495 cm-17) with a visual rating improvement of at least
2 points on a
5-point scale. The grade’s high molecular weight (viscosity-average DP ≈
1,850) yields a low migration rate into the wet-web pores, minimising closed-loop water contamination that would otherwise create biological oxygen demand excursions in the mill effluent—a critical compliance factor under
EU BAT Reference Document for Pulp and Paper Industry (2017). End-use products include microwave-safe paperboard trays coated only with aqueous barrier primers and archival-grade folders meeting
ISO 9706 permanence requirements.
When Corrugated Core Lamination Demands Immediate Tack and Cold-Crush Resistance
Manufacturing lines producing double-wall corrugated packaging for agricultural cold-chain transport utilise high-solids PVA
100-78 laminating adhesives on a corrugator running at
180 m/min because the grade contributes immediate green tack that prevents flute slippage before starch-gelatinisation is complete. A single-component suspension is prepared by swelling
28 kg of fine-mesh PVA in
100 L of cold water containing
0.2% sodium benzoate preservative, then passing the slurry through a continuous cook-extruder (e.g., Brabender Do-Corder or Leistritz ZSE-27 twin-screw) set to a barrel profile of
80/95/105/110°C and a screw speed of
120 rpm, resulting in a smooth solution of
20–22% solids that still flows at
40–50°C. The compounder adds a liquid plasticiser blend of glycerol and sorbitol (
4 phr total) and a Sepiolite-based thixotropic agent (
2 phr) to give a viscosity profile measured on a Brookfield RV-DV2T at
20 rpm of
4,800–6,200 mPa·s at
35°C. During application via a three-roll kiss coater at a nip gap of
0.15 mm on E-flute Kraft liners, the open time is
25–35 seconds under
65% RH at
25°C, sufficient for a combined double-backer and a downstream rotary die-cutter. The joint strength after
48 h conditioning is measured by the FEFCO No. 50 pin-adhesion method and exceeds
500 N/m on
150 g/m² Testliner, a threshold unattainable by conventional starch adhesives run at identical speed without thermal booster sections. Because the
100-78 film is fully reversible in hot water, the scrap board is repulpable under normal
50°C hydropulper conditions without persistent tacky residue, satisfying
EN 13430:2004 requirements for material recycling. The final packaging—typically wet-strength containers for broccoli and floral shipments—are qualified under
ASTM D5635/D5635M-18 for box compression when exposed to interior condensation.Production of cordierite honeycomb catalyst carriers via extrusion shaping imposes stringent demands on the organic binder phase: it must plasticise the alumina-silica-magnesia mass at water contents below
30%, provide adequate die-lubrication, and combust cleanly below
550°C without carbonaceous residue exceeding
0.05 wt%. A binder system based on PVA
100-78 is prepared by pre-dissolving the granulate at
14% concentration in deionised water at
96°C using a scraped-surface heat exchanger, then blending this solution with a cellulose ether (methylhydroxypropyl cellulose, methoxyl substitution
1.6–1.9) as a co-binder at a ratio of
3 : 1 PVA-to-cellulose ether, together with a modified ethylene-vinyl acetate wax emulsion (
2.5% on dry ceramic mass) serving as die-release agent during piston-extrusion at ram pressures of
12–18 MPa. The PVA grade is selected over lower-viscosity analogues because its high degree of polymerisation preserves green-body bending strength above
3.5 MPa after drying at
80°C to
60% rh (measured by three-point bend per
ASTM C674-13), which is critical for maintaining cell-wall integrity during automatic face-machining of the dried honeycomb logs to
400 cpsi geometries. Thermal debinding must follow a precisely ramped schedule in a controlled-atmosphere tunnel kiln: heating at
0.3°C/min from
200°C to
350°C under an oxygen-enriched flow (
21% O₂,
79% N₂) to avoid exothermic runaway that causes wall cracking, then a dwell of
2 h at
450°C to complete decarboxylation. Thermogravimetric analysis per
ASTM E1131-08 of the pure binder film shows a
98.5% mass loss between
220°C and
520°C, with a residual ash content of
<0.25% due to the grade’s low ash specification (≤
0.5% per certificate). The fired substrates achieve a median pore size of
4–7 µm and water absorption of
22–26% per
ASTM C373-18, values within the acceptance window for washcoat application in European heavy-duty diesel particulate filters. A secondary benefit observed on full-scale extrusion lines with vacuum pugmills is that the long-chain PVA significantly reduces torque variability by
18–22% compared to starch-based binders, eliminating sporadic micro-checking along hexagonal cell junctions.
Solvent-Resistant Barrier Film Incorporating High-Viscosity PVA
Biaxially oriented films for solvent-barrier laminates in flexographic-printed retort pouches use PVA
100-78 as the core barrier layer because the completely hydrolysed structure plasticised with a controlled amount of polyol remains impervious to ester-, ketone-, and aliphatic-hydrocarbon-based inks even after retorting at
121°C for
30 min. Casting dope is prepared by dissolving the polymer at
22% solids in a
50:50 v/v water–n-propanol mixture heated under reflux to
85°C in a closed stainless-steel vessel, which suppresses surface skinning. The solution is then degassed under vacuum and metered through a slot die onto a chrome-plated steel belt cooled to
5–8°C to gel the film at a thickness of
180–220 µm in the wet state, which upon drying at
80°C in a zoned flotation dryer yields a
25–30 µm clear film with a tensile strength in the machine direction of
55–65 MPa and elongation at break of
120–150% per
ISO 527-3:2018 specimen type 5. Post-casting, the film is tentered at a ratio of
1.5×1.5 at
195°C, which raises the degree of crystallinity to approximately
55% (DSC crystallinity from the melt endotherm) and reduces equilibrium moisture uptake at
50% RH to
<5%. The resultant film’s oxygen permeability measured at
23°C, 50% RH per
ASTM D3985-17 is below
0.5 cm³·mm/(m²·day·atm), a performance competitive with mid-range EVOH films, but without the moisture-sensitivity penalty. A second form factor employs blown-film extrusion where fully hydrolysed PVA is plasticised with
25 phr glycerol and twin-screw compounded with
2 phr nano-clay dispersion, extruded through a spiral-mandrel die at
195°C—a narrow processing window that requires the addition of
0.3% process stabiliser (a hindered phenol/phosphite blend) to prevent chain scission during residence at melt temperature. The film is edge-trimmed and recycled in a closed loop at up to
30% regrind without gel-dot formation, verified by laser-gel counter to a count below
5 defects/dm². Compliance for food contact under
FDA 21 CFR §177.1670 (resinous and polymeric coatings) and
EU Regulation 10/2011 with Annex I migration limits is on record for PVA homopolymers of this hydrolysis level when used in non-alcoholic food simulants. This barrier-grade PVA film is subsequently adhesive-laminated with PET and CPP layers to construct a pouch that retains laminate bond strength above
2.5 N/15mm after hot-fill at
85°C, tested per
ASTM F88/F88M-20.
Poly(vinyl alcohol) grade Sinopec 100‑78 is a partially hydrolyzed granular thermoplastic produced by Sinopec Chongqing SVW Chemical Co., Ltd. via continuous alkali-catalyzed alcoholysis of poly(vinyl acetate). The designation “100” denotes an average degree of polymerization approximating
1 000–1 100 while “78” references the nominal degree of hydrolysis falling in the range
78.0–82.0 mol%. This residual acetate content (
18–22 mol% vinyl acetate repeat units) imparts cold-water swellability, reduced crystallinity, and a surface energy profile that bridges hydrophilic metallic cellulosic substrates and hydrophobic synthetic surfaces. The resin is supplied as a white granular powder packed in
25 kg multi-wall paper sacks with a moisture-proof polyethylene inner liner, and is classifiable under HS code
3905.30. Typical application domains span textile warp sizing, paper surface functionalization, water-redispersible adhesives, and suspension/emulsion polymerization stabilization, each of which exploits a different facet of the interplay between hydroxyl hydrophilicity and acetyl hydrophobicity at the secondary molecular level.
Physicochemical Fingerprint: Sinopec 100‑78 Granular Grade
| Parameter | Typical Value | Test Method |
|---|
| Hydrolysis degree | 78.0–82.0 mol% | ISO 15023‑1:2017 (titrimetric) |
| Viscosity of 4 % aqueous solution at 20 °C | 28.0–32.0 mPa·s | Brookfield LV, spindle 1, 30 rpm |
| Ash content (as Na₂O) | ≤ 0.5 % | ASTM D5630‑13 (muffle 800 °C) |
| Volatile matter | ≤ 5.0 % | ISO 15512:2019 (loss on drying, 105 °C) |
| pH of 4 % aqueous solution | 5.0–7.0 | ISO 6879:1995 (glass electrode) |
| Retention on 180 µm (80 mesh) screen | ≤ 2.0 % | ISO 4610:2001 |
Warp sizing formulations for high-speed air-jet looms impose a dual requirement: a film hard enough to resist yarn-to-yarn abrasion during shedding, yet flexible enough to endure rapid whipping motion without shattering onto loom frames. Sinopec 100‑78 addresses this through a
22 mol% residual acetate block that plasticizes the amorphous domains, delivering dry film tensile strength of approximately
42 MPa (ASTM D882‑18,
25 µm cast film) and elongation at break near
200 %. In a typical cooking regimen a
12–15 % solids slurry is jet‑cooked at
130 °C for
20 min then blended with oxidized corn starch ether (
5 % on PVA) and a low‑molecular‑weight acrylic binder. Field data from shuttleless rapier and air-jet looms running
100 % cotton Ne
20–40 yarns indicate a weaving efficiency gain of
4–7 percentage points over fully hydrolyzed PVA grades, attributable to reduced size shedding at the drop wires and heald frames. Desizing is accomplished in hot water at
80–85 °C without enzymatic pretreatment, yielding a BOD₅/COD ratio typically
0.3–0.4, compatible with activated-sludge mill effluent treatment plants operating at hydraulic residence times above
8 h. A recognized boundary condition: the sizing liquor must be maintained below pH
8.5 to avoid base‑catalyzed de‑esterification of residual acetate groups, which can raise viscosity during extended holding on the slasher beam and generate pick-up inconsistency.
Why Select 78 mol% Hydrolysis for Surface Sizing of Alkaline Writing Papers?
In the alkaline papermaking environment (pH
7.5–8.5, CaCO₃ filler loads
15–25 %), the challenge shifts from purely hydrophobic sizing to controlling liquid penetration while preserving optical brightener efficiency and surface strength. Sinopec 100‑78, applied via a film‑transfer size press (rod‑metering or blade‑metering unit) at dry pick‑up of
0.8–1.2 g/m² per side, yields a Cobb
60 value (ISO 535:2023) of
22–28 g/m² on woodfree uncoated base paper. The hallmark advantage over fully hydrolyzed PVA is low‑temperature solubility – the
4 % aqueous dispersion clarifies at
40–50 °C without the
95 °C jet cooking required for grades above
98 mol% hydrolysis. This allows the mill to operate a stovetop or vessel circuit at
60–65 °C, halving steam consumption per tonne of coat‑weight. Equally important is the non‑ionic character: the partially hydrolyzed polymer neither complexes with cationic polyacrylamide retention aids nor quenches di‑sulfonated stilbene optical brighteners, so ISO brightness (ISO 2470‑1:2016) remains within
0.2 point of the untreated base sheet. Operator‑reported machine‑side observations confirm that at addition rates above
1.5 g/m², surface sizing with 100‑78 can elevate IGT pick velocity (ISO 3783:2014) beyond
3.0 m/s, while maintaining
85 % of the base sheet’s air permeance. The limit exists on low‑basis‑weight (
45 gsm) sheets, where film‑splitting on the forward‑transfer roll may generate mist if the solution viscosity exceeds
40 mPa·s at application temperature; dilution to
8–10 % solids is mandatory.
In spiral tube winding and paper‑to‑paper laminating, adhesive compounders preparing borated dextrin‑PVA hybrid formulas value Sinopec 100‑78 for its rapid cold‑water tack development and rheological responsiveness to borate ion crosslinking. A standard batch procedure on a high‑shear dissolver with a
300 mm saw‑tooth impeller starts by slurrying
22 parts PVA granules in
78 parts water at
25 °C, then heating to
70 °C under
900 rpm agitation for
30 min. The resulting translucent dispersion is cooled to
35 °C and
4 parts of a
10 % borax pentahydrate solution are metered over
15 min under reduced agitator speed (
400 rpm) to avoid localized gel seeding. The resultant tack value (TAPPI T 456 om‑19, modified lap‑shear on
200 g/m² kraft) rises within
30 s from
0.4 N/cm to
3.2 N/cm, sufficient for high‑speed tube winders running at
50–70 m/min without delamination at the ply‑bond. A critical processing note: the sol‑gel transition of 100‑78 in the presence of borate is exquisitely pH‑sensitive; below pH
5.5 crosslinking is insufficient, above pH
8.0 the gel becomes rubbery and loses wet tack, causing pop‑open failures on convolute winding mandrels. Therefore, a citrate or phosphate buffer is required to clamp the pH at
6.2–6.8. The resin conforms to FDA
21 CFR 175.105 (indirect food additive: adhesives) provided overall migration into food simulant does not exceed the
50 ppb industry standard for repeat‑use articles, requiring end‑user validation per
EN 1186‑1.
When PVA 100‑78 Replaces Hydroxyethyl Cellulose in Vinyl Acetate Polymerizations
As a suspension stabilizer for vinyl acetate monomer batch polymerizations in a
10 m³ glass‑lined jacketed reactor equipped with a
2.5 m diameter three‑blade retreat‑curve impeller, Sinopec 100‑78 delivers an Hüppler plastograph torque profile distinct from cellulosic ethers. The PVA is predissolved in deionized water at
90 °C, then the solution is cooled to
60 °C, charged with VAM, and initiated with a persulfate‑bisulfite redox couple at
0.08–0.12 % on monomer weight. The grafting reaction between vinyl acetate macroradicals and the acetate‑bearing segments of the PVA backbone produces a blocky copolymer‑like interphase that stabilizes latex particles in the
0.8–2.5 µm diameter range (ISO 22412:2017, dynamic light scattering). Compared with the same reactor run using hydroxyethyl cellulose at equal
4 % protective colloid loading, 100‑78 yields a
12–15 % lower Brookfield viscosity of the finished latex (
45–52 % solids) while narrowing the particle size span (D₉₀/D₁₀) from
6.8 to
3.4. This translates to improved shear stability under a needle‑gap paint strainer test (ASTM D4977‑03, wet abrasion). A well‑recognized operational boundary emerges when the latex solids are pushed above
55 %: the short‑chain branching distribution inherent to 100‑78’s
78 mol% hydrolysis lowers the critical overlap concentration, leading to early onset of dilatancy in the polymerizing medium that can exceed the torque limitation of a
45 kW drive. Production records therefore cap solids at
54 % for this grade, in contrast with fully hydrolyzed
99 % grades that permit
58 % solids in the same vessel.
Property Offset Across the Hydrolysis Spectrum
| Property | Sinopec 100‑27 (fully hyd.) | Sinopec 100‑48 (intermediate) | Sinopec 100‑78 (present grade) |
|---|
| Hydrolysis degree | 99.0–99.8 mol% | 86.0–89.0 mol% | 78.0–82.0 mol% |
| 4 % solution viscosity at 20 °C | 26.0–30.0 mPa·s | 27.0–31.0 mPa·s | 28.0–32.0 mPa·s |
| Water dissolution temperature (clear point) | 93–98 °C | 55–65 °C | 40–50 °C |
| Dry film tensile strength (ASTM D882) | 68–74 MPa | 52–58 MPa | 40–45 MPa |
| Elongation at break (ASTM D882) | 40–60 % | 120–160 % | 180–230 % |
| Adhesion to corona‑treated PET (EN 1939) | 1.8–2.5 N/25 mm | 3.5–4.8 N/25 mm | 5.2–7.0 N/25 mm |
| Oil‑in‑water emulsifying efficiency | Poor | Moderate | High |
| Crystalline melting point (onset, DSC) | 228–233 °C | 190–205 °C | 170–185 °C |
Experience from compounding batches exceeding
500 kg on agitated jacket vessels points to a set of handling prerequisites specific to 100‑78. The powder, received at
5–7 % volatiles, must be pre‑blended with an equal weight of cool waterside at
15–20 °C under low‑shear paddle agitation (
60–80 rpm) to form a lump‑free slurry before live steam injection. Direct introduction of powder into hot water above
50 °C invariably produces fused gel agglomerates that require
45–60 min of additional high‑shear dispersion and may retain
0.5–1.0 mm translucent “fish‑eye” defects visible in downstream cast films. Foam generation during dissolution is a recognised nuisance; a dimethylpolysiloxane‑based antifoam (e.g.,
50 ppm active silicone) dosed after the solution temperature drops below
35 °C prevents foaming without interfering with the surface‑active acetate groups. Long‑term storage stability of aqueous solutions at
15–20 % solids is governed by microbial susceptibility; preservation with
0.05 % sodium benzoate or
0.02 % methylisothiazolinone is recommended if holding time exceeds
48 h. The resin is registered under REACH (EC
209‑183‑3) and carries a RoHS self‑declaration for
10 restricted substances according to
IEC 62321‑8:2017, but does not implant a formal EN
13432 compostability certification, limiting its applicability in biodegradable film structures unless formulated with certified compostable co‑components. Iron contamination from mild‑steel mixing equipment catalyses oxidative chain scission upon thermal aging of the dry powder above
140 °C; stainless‑steel conveying and storage under nitrogen blanket are therefore standard in compounding plants processing >
200 tonnes/year.
