CCP PVA BF-14

CCP PVA BF-14 is a granular, partially hydrolyzed polyvinyl alcohol grade manufactured by Chang Chun Petrochemical Co., Ltd. Its viscosity, measured on a 4 % aqueous solution at 20.0 ± 0.1 °C according to JIS K6726 (Brookfield LVT, 60 rpm, spindle No. 2), lies in the range 13.5 – 16.5 mPa·s. The degree of hydrolysis is 86.5 – 89.0 mol%, determined by saponification back‑titration per the same standard. The residual acetyl content imparts a balance of water solubility, film flexibility, and interfacial activity that differentiates BF‑14 from both fully hydrolyzed and higher‑viscosity partially hydrolyzed PVA varieties. The product contains ≤ 0.5 % ash (JIS K6726 5.5) and ≤ 5.0 % volatile matter at 105 °C, ensuring minimal inorganic interference in emulsion systems. Bulk density typically falls between 0.40 and 0.55 g/cm³, permitting efficient pneumatic conveying when the conveying air dew point is maintained below −15 °C to avoid hydrate formation on pipe walls.

Technical specification summary, CCP PVA BF-14

Property	Test method	Typical range
Viscosity (4 % aq., 20 °C)	JIS K6726	13.5 – 16.5 mPa·s
Degree of hydrolysis	JIS K6726	86.5 – 89.0 mol%
pH (4 % solution)	JIS K6726	5.0 – 7.0
Ash	JIS K6726 5.5	≤ 0.5 %
Volatile matter	105 °C, 3 h	≤ 5.0 %
Bulk density	Tap method	0.40 – 0.55 g/cm³

What Controls Particle Size Distribution in VAc Emulsion Systems?

When employed as a protective colloid in vinyl acetate semi‑continuous emulsion polymerization, BF‑14 governs nucleation kinetics and colloidal stability through its interfacial grafting activity. In a 5 m³ stainless‑steel reactor equipped with a pitched‑blade turbine (D/T = 0.4) and operated at a tip speed below 3.5 m/s, a continuous aqueous BF‑14 feed of 4–6 wt% (relative to total monomer) restricts mean particle diameter to 0.4–1.2 µm. Exceeding 0.5 wt%/h addition rate during the nucleation phase, however, produces local viscosity elevation in the monomer‑droplet interfacial region, which retards radical flux and triggers bimodal distributions detectable by laser diffraction as a secondary peak above 2 µm. The molecular weight (weight‑average) of BF‑14, maintained within a narrow specification band, determines the rheological percolation threshold in the aqueous phase. At reactor solids contents above 55 %, the zero‑shear viscosity of the finished latex correlates with the number‑average number of PVA grafts per particle, as measured by ¹³C NMR integration; BF‑14’s relatively low solution viscosity keeps the latex below 2000 mPa·s (Brookfield RVT, 20 rpm) even at 60 % solids, avoiding the torque‑overload alarm common to higher‑molecular‑weight grades such as BF‑17.

The intermediate hydrolysis level introduces a narrow processing window with respect to pH and temperature. Post‑addition of vinyl acetate monomer with a free‑radical initiator system (typically potassium persulfate at 0.2–0.4 wt% on monomer) requires buffering to pH 4.5–5.5 using sodium acetate or sodium bicarbonate. Below pH 4.2, acid‑catalyzed chain scission of the 1,2‑glycol linkages in the PVA backbone reduces the effective hydrodynamic volume, leading to a rise in coagulum exceeding 0.5 % on total monomer. Conversely, operating above pH 6.0 in the presence of residual vinyl acetate accelerates base‑catalyzed transesterification, gradually raising the in‑situ hydrolysis degree of the protective colloid and reducing its interfacial activity—an effect that manifests as a coarse emulsion with a D[4,3] exceeding 1.5 µm after three consecutive monomer recharges. Published data for this specific pH‑drift interaction in BF‑14‑stabilised systems is limited, yet industrial campaigns with 8–12 h monomer feed windows confirm that mid‑campaign replenishment of fresh BF‑14 at 10 % of the initial charge offsets the colloid aging effect.

Warp Yarn Hairiness Reduction and Weave Room Humidity Control

In high‑speed air‑jet weaving, BF‑14 forms a flexible sizing film on cotton and polyester‑cotton blends that reduces hairiness index (Zweigle G565, ≤ 3 mm hairs per 100 m) by 40–60 % compared to unsized yarn. A sizing liquor concentration of 8–10 % (w/v) applied on a multi‑cylinder slasher at 80–85 °C yields a size add‑on of 12–14 % owf. The critical factor for filament cohesion lies not in the ultimate tensile strength of the film, which averages 38–42 MPa (ASTM D882‑18, 23 °C, 50 % RH), but in its elongation at break, kept at 160–200 % by the residual acetyl groups. This flexibility accommodates the cyclic extension of warp yarns during shed formation without micro‑cracking, which would generate fly accumulation on loom harnesses.

The BF‑14 film’s water solubility remits after weaving through an oxidative or amylase‑based desizing step. Solubility remains> 99 % at 70 °C in deionised water within 20 min, a rate 1.5–2.0× faster than that of an equivalent‑viscosity fully hydrolyzed grade (e.g., BF‑24). This rapid dissolution is critical for continuous open‑width washing ranges operating at line speeds exceeding 80 m/min, where a residual size content above 0.2 % on fabric causes dye‑speck defects in subsequent reactive dyeing. To prevent re‑deposition of dissolved PVA onto fabric, a hard water tolerance of up to 150 ppm CaCO₃ is achievable without cloud point precipitation; beyond this, the bath must be softened, otherwise BF‑14‑calcium complexes form, raising the turbidity to 50 NTU and above.

Storage of sized beams at relative humidity above 65 % necessitates moisture‑barrier wrapping, as BF‑14 exhibits a moisture regain of 12–14 % at 65 % RH and 25 °C, sufficient to plasticise the film and reduce its tensile modulus by 30 %. If unwrapped beams are held longer than 48 h in uncontrolled mill conditions, yarn stickiness in the loom shed increases shedding break frequency by 3–5 breaks/10⁵ weft insertions compared to controlled‑humidity storage.

Detailed examination of the binder segment in pigmented blade‑coating formulations reveals BF‑14’s dual role as a secondary binder and rheology modifier. In a typical coating colour containing 100 parts ground calcium carbonate (90 % <2 µm), 10 parts styrene‑butadiene latex, and 0.5–1.5 parts BF‑14 (dry on pigment), the Brookfield viscosity at 100 rpm remains 800–1200 mPa·s while high‑shear viscosity measured on a capillary viscometer (ACAV A2, 1.0 × 10⁶ s⁻¹) drops to 35–45 mPa·s. This shear‑thinning profile, coupled with a water‑retention value of 85–90 % (TAPPI T 701 pm‑01, pressure filtration at 1.5 bar for 90 s), prevents binder migration during IR‑dryer impingement on a blade coater operating at 1200 m/min. The resulting coating structure exhibits a gloss improvement of 3–5 points (Gardner 75°) relative to an all‑latex binder system at identical coat weight, attributable to the plasticising effect of the PVA on latex film formation and its ability to fill micro‑voids between pigment particles during calendering at 80 °C nip temperature and 150 kN/m linear load. Compatibility with optical brightening agents and polyacrylate dispersants must be verified by jar testing. Anionic dispersants with a charge density above 800 µeq/g can compete with BF‑14 for pigment surface sites; when dispersant demand exceeds 0.3 % on pigment, a 10‑min equilibration period with 500 rpm agitation before PVA addition avoids instantaneous shock‑gelation that elevates grit content (≥ 250 ppm on a 45 µm screen). Conversely, cationic starches cause heterocoagulation and must be avoided unless an anionic charge‑blocking layer is pre‑adsorbed on the pigment.

When Borax‑Free Crosslinking is Required for Aqueous Adhesives

BF‑14 provides the film‑forming backbone for water‑based paper‑laminating and tube‑winding adhesives where the presence of borates is prohibited due to corrosion risks on aluminium‑wound cores. A formulation containing 8–12 % BF‑14, 2–5 % glycerine, and 0.1 % defoamer delivers a wet‑tack value of 300–400 g/cm (FINAT FTM‑9) on kraft linerboard. Open time, governed by the rate of free‑water evaporation, can be extended from 40 s to 90 s by increasing the glycerine/PVA ratio from 0.25 to 0.50, though the compressive shear strength of the bonded joint after 24 h conditioning at 23 °C/50 % RH falls from 4.2 MPa to 3.1 MPa (ASTM D905‑08). For high‑speed case‑sealing lines equipped with wheel applicators running at 300–400 m/min, the pseudo‑plasticity index (η_{5 rpm}/η_{50 rpm}) should be maintained between 3.5 and 4.5 to prevent stringing.

In comparison with higher‑molecular‑weight partially hydrolyzed grades, BF‑14’s lower solution viscosity enables easier pumping and reduces adhesive‑drying energy by approximately 15 % when transitioning from a 25 mPa·s grade. However, the film’s lower tensile modulus (0.8–1.2 GPa vs. 1.4–1.8 GPa for BF‑17) renders it unsuitable for structural wood joints exposed to > 85 % RH cyclic conditioning, where creep compliance exceeds 2 × 10⁻⁶ Pa⁻¹ after 72 h. Pre‑drying of the powder at 80 °C for 2 h is mandatory before compounding if the moisture content exceeds 1.5 % above the as‑packaged value, else lump formation in the dissolver raises the undissolved particle count above 50 per 100 g (63 µm sieve).

Comparative viscosity and hydrolysis range for selected CCP PVA grades

Grade	4 % Viscosity (mPa·s)	Degree of hydrolysis (mol%)	Typical application differentiation
BF-14	13.5 – 16.5	86.5 – 89.0	Low‑viscosity partially hydrolyzed; VAc emulsion, low‑basis‑weight paper coating
BF-17	25.0 – 30.0	87.0 – 89.0	Higher wet‑tack adhesives, extrusion‑grade binder for ceramics
BF-24	44.0 – 50.0	98.0 – 99.0	Fully hydrolyzed; high‑barrier films, polarising‑film substrate

Distinctions between BF‑14 and other partially hydrolyzed PVA types extend into permissible initiator chemistry. BF‑14 tolerates persulfate initiation in emulsion polymerisation without the instantaneous discoloration observed with high‑ester‑content PVAs that release acetaldehyde, provided the reactor jacket temperature stays below 80 °C. In contrast, grades with hydrolysis below 85 mol% can generate sufficient acetaldehyde to catalyse crosslinking with residual PVA hydroxyls, producing insoluble micro‑gels that foul heat exchanger surfaces. When dissolution is performed in hard water containing> 200 ppm Ca²⁺, BF‑14’s solution remains clear for 48 h at 25 °C, whereas lower‑hydrolysis grades exhibit calcium‑induced haze within 6 h, jeopardising continuous slot‑die coating operations where optical clarity of the wet film is essential for automatic defect detection. These operational boundaries, informed by production‑scale batch records, underscore the necessity of selecting the appropriate PVA grade not solely on viscosity and hydrolysis averages, but on the entire set of secondary properties that dictate long‑run manufacturability.