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The partially hydrolyzed polyvinyl alcohol (PVA) grade designated CCP BP-14, manufactured by Chang Chun Petrochemical Co., Ltd., is characterized by a hydrolysis degree of 87–89 mol% and a 4% aqueous solution viscosity of 13–15 mPa·s at 20°C (Brookfield method, spindle #1, 60 rpm, per ISO 15023-1:2019). This medium-viscosity, intermediate-alcoholysis product bridges the performance gap between fully hydrolyzed grades that deliver maximum water resistance and low-hydrolysis grades that dissolve readily in cold water. Its residual acetyl content imparts a balance of surface activity, film flexibility, and adhesion to low-energy substrates—attributes that are not simultaneously achievable with either high-hydrolysis or low-viscosity alternatives. Supplied as a free-flowing granular powder with an ash content below 0.5 wt%, a volatile matter typically under 5.0% (as determined by loss on drying at 105°C), and a pH of 5.0–7.0 in a 4% aqueous dispersion, BP-14 is engineered for applications where controlled penetration into porous media, moderate film strength, and compatibility with secondary binders are required. The product is routinely specified in adhesive compounding, surface sizing of paper and board, textile warp sizing, and as a protective colloid in emulsion polymerization. Unlike the manufacturer’s BP-17 grade, which offers a higher viscosity range of 20–26 mPa·s at comparable hydrolysis, BP-14 reduces solution viscosity by approximately 35–40%, enabling higher solids content in size-press formulations without exceeding target pickup viscosities and decreasing drying load on the machine.

What Are the Critical Parameters for Aqueous Solution Preparation?

Aqueous processing of BP-14 requires controlled dissolution conditions to avoid gel particle formation and ensure batch-to-batch consistency. The powder is introduced gradually into deionized water (conductivity <10 μS/cm) at 25–30°C under agitation in a jacketed vessel equipped with a high-shear disperser (Cowles blade tip speed 10–15 m/s). Once wetted, the slurry is heated to 85–95°C and stirred at reduced speed (300–500 rpm) for 30–60 minutes after complete dissolution to eliminate microgels. The hot solution is then filtered through a 100 µm stainless steel mesh and cooled to below 35°C before storage to minimize skin formation on tank walls. Storage tanks must be constructed of 304 or 316 stainless steel; prolonged contact with mild steel or copper alloys induces discoloration and viscosity drift via metal-catalyzed oxidation. The pH of the finished solution is adjusted to 5.5–6.5 with dilute acetic acid or sodium hydroxide as needed, because the product’s residual acetyl groups can slowly hydrolyze under acidic conditions (pH <4), releasing acetic acid and increasing solution viscosity over a 48-hour period. Pre-drying of the raw powder is recommended if the storage environment exceeds 65% relative humidity: exposure for 2–4 hours at 60°C in a forced-air oven restores flowability and prevents clumping in the feed hopper. Incompatible chemical additives include strong oxidizing agents (e.g., persulfates at concentrations above 1%) which cleave the polymer backbone, and certain amine-functional silanes that can initiate premature gelation if added directly to a hot PVA solution. The working shelf-life of a 15% BP-14 solution preservative-free is 72 hours at 20°C; beyond this, microbial growth or viscosity drift exceeding 5% is likely.

In starch- and dextrin-based adhesive systems, BP-14 is incorporated as a secondary binder to improve specific adhesion to varnished and clay-coated paperboard. A pre-dissolved 15–20% PVA solution is metered into a cooked starch paste (typically 25–30% solids) at a ratio of 2–5 parts PVA per 100 parts dry starch, while the blend temperature is held below 70°C to avoid thermal degradation of the starch component. The resultant adhesive exhibits a Brookfield viscosity (ASTM D1084-21) of 2,000–4,000 mPa·s at 25°C, with a viscosity stability of <5% drift over 24 hours at 50°C—compared to a 10–15% decrease for unmodified starch pastes due to retrogradation. Tensile-shear adhesion to clay-coated SBS board (ASTM D1876-08, T-peel geometry) improves by 15–25%, with failure mode shifting from interfacial separation to substrate fiber tear. The lower molecular weight of BP-14 relative to higher-viscosity partially hydrolyzed grades such as BP-17 enhances its ability to wet low-energy coatings without reducing the cohesive strength of the dried film below 8 MPa (ASTM D882). Trials on high-speed (300 m/min) case-sealing lines have demonstrated that adhesive containing BP-14 deposits a more uniform film through a 0.5 mm slot die, reducing skip gaps by 30% compared to starch-only formulations. Care must be taken to avoid ionic cross-contaminants: iron concentration above 5 ppm in process water can complex with acetyl groups and discolor the bond line from pale yellow to brown within 48 hours of application, particularly when exposed to UV light. Equipment should be purged with a 0.5% caustic solution weekly to prevent biofilm accumulation that thrives in the nutrient-rich PVA/starch medium.

Surface Sizing Press Application Parameters

At the size press of a paper or board machine, BP-14 is applied as a 3–6% solids solution at temperatures of 50–60°C to enhance surface strength and control liquid penetration. Unlike oxidized starch, which typically delivers a Cobb₆₀ value (TAPPI T441 om-20) of 45–55 g/m² at 4% pickup on linerboard, BP-14 at equivalent pickup reduces Cobb₆₀ to 30–38 g/m² while simultaneously raising Scott bond (TAPPI T833 pm-19) by 10–15 J/m². The lower Brookfield viscosity of BP-14 (13–15 mPa·s at 4%) relative to BP-17 (20–26 mPa·s) permits operation at up to 10% solids without exceeding the 150 mPa·s threshold at which splashing and uneven film transfer become problematic on metering size presses running at 800–1,200 m/min. Nip pressure is maintained between 30–50 kN/m and the drying cylinder temperature profile set to 80–100–120°C for the first three cylinders ensures film formation without skinning. Because BP-14 contains minimal ash (0.5%), the accumulation of deposits on the size-press roll surface is slower than with starches containing bound calcium; roll cleaning frequency can be extended from every 8 hours to every 24 hours. However, the solution must be continuously circulated and maintained at temperature—stagnant sections of the supply loop can develop localized viscosity increases due to evaporative water loss, which, if exceeding 10% of the original concentration, may result in gel streaks on the paper web.

For weaving preparation, BP-14 is applied to cotton and polyester/cotton warp yarns at a size box temperature of 60–70°C and a solids content of 8–12%. The film exhibits a peel adhesion to sized roving (modified ASTM D1876) of 6–8 N/cm, sufficient to withstand the abrasive forces in air-jet looms operating at 600–800 picks per minute. The low ash characteristic translates to reduced size shedding in the weaving shed; dust concentration measured by a gravimetric sampler at the loom bank typically remains below 0.5 mg/m³, which is within the ACGIH TLV of 3 mg/m³ for inert particulates. Desizing is accomplished in a continuous open-width washer with a two-stage configuration: first compartment at 80°C with 0.5 g/L non-ionic surfactant (e.g., ethoxylated linear alcohol, HLB 12–13), second compartment at 90°C with overflow rinse. Complete size removal, verified by negative iodine/potassium iodide staining, occurs in 30–45 seconds—a reduction of 15–20% in residence time compared to fully hydrolyzed PVA of similar viscosity. The energy saving arises from the lower heat of dissolution of BP-14, which has a reduced degree of crystallinity (approx. 30–35% vs. 45–50% for fully hydrolyzed grades, as measured by DSC). Textile technologists must note, however, that ambient relative humidity above 70% on the weaving floor can plasticize the size film and reduce its cohesiveness, potentially increasing end-break rates. In such conditions, the size formulation is often modified with 1–2% wax or a polyacrylate ester to reduce moisture sensitivity.

When BP-14 Replaces Gelatin as a Protective Colloid in Emulsion Polymerization

In the semi-continuous emulsion polymerization of vinyl acetate and vinyl acetate/ethylene, BP-14 serves as the primary protective colloid at 2–4% by weight on total monomer. The partially hydrolyzed architecture provides a surface activity that stabilizes monomer droplets and growing polymer particles via a combination of steric stabilization and limited graft-copolymerization, with grafting efficiencies reported in the range of 15–25% under persulfate initiation at 70°C. This results in a final latex with a mean particle size of 800–1,200 nm and a polydispersity index below 0.1, as measured by dynamic light scattering (ISO 22412:2017). Compared to gelatin or cellulosic colloids, BP-14 produces emulsions with more Newtonian flow behavior; the latex viscosity at 55% solids is typically 2,000–5,000 mPa·s (Brookfield, 20 rpm), allowing downstream formulation without large additions of water. However, the protective colloid efficiency of BP-14 diminishes if the polymerization temperature exceeds 80°C. At such elevated temperatures, hydrolysis of residual acetate groups accelerates, releasing acetate ions that alter the ionic strength of the aqueous phase and reduce the colloid’s boundary layer thickness, leading to coagulum levels that can rise above 1% of the batch mass. Therefore, jacket temperature control maintaining a reaction medium of 70–75°C is critical. The product also demonstrates compatibility with non-ionic surfactants (HLB 15–18) used as co-stabilizers, but anionic surfactants containing sulfonate groups should be evaluated in pilot quantities first, as they can displace the adsorbed PVA layer and generate a bimodal particle size distribution.

BP-14 meets the requirements of FDA 21 CFR §176.170 for use as a component of paper and paperboard in contact with aqueous and fatty foods, and §176.180 for dry food contact, provided that the finished packaging article does not exude PVA or its hydrolysis products in excess of the extraction limitations specified therein. The product holds a valid EINECS registration (no. 209-183-3 for PVA homopolymer) and is compliant with EU REACH; residual vinyl acetate monomer is controlled below 5 ppm, and methanol extractables are below 1.0 wt%. In the storage warehouse, bags should be stacked no more than 8 layers high to prevent powder compaction, and the environment maintained at <30°C, <65% RH. Under such conditions, the shelf life from the date of manufacture is 24 months. Once a bag is opened, the contents should be transferred to a sealed, desiccant-lined intermediate bulk container if not consumed within 8 hours; moisture uptake beyond 1.5% leads to lump formation that cannot be readily dispersed in the standard dissolution equipment. For cleanroom or electrostatic-sensitive environments, BP-14 powder, like all polyvinyl alcohols, can generate an airborne dust of minimum ignition energy <10 mJ; appropriate grounding and dust collection per NFPA 61 are required.

A rapidly growing application for BP-14 is in water-soluble unit-dose packaging for liquid laundry detergents. Film produced from a 15% aqueous solution cast onto a 100°C chrome-plated belt yields a film of 40–60 µm thickness that dissolves completely in 10–15 seconds in 20°C water (modified ISO 14851). Its partial hydrolysis ensures dissolution at temperatures as low as 5°C, whereas fully hydrolyzed films typically require water above 25°C for complete disintegration. To avoid premature dissolution in humid storage conditions, the pouch material is typically laminated with a thin overprint varnish that functions as a moisture barrier; however, BP-14’s intrinsic slower moisture vapor transmission rate (120–150 g/m²/day at 38°C, 90% RH, ASTM E96) compared to lower-hydrolysis grades provides additional shelf-life robustness. Compatibility with nonionic surfactants (up to 30% of package contents) enables broad formulation freedom, but direct contact with concentrated anionic surfactants above 40% activity can soften the film and reduce seal strength; pouch designs therefore avoid aggressive solvents in the composition adjacent to the film layer.

Many converting operations select BP-14 over fully hydrolyzed grades to reduce desizing energy by at least 15%.

The table below compares key properties of BP-14 with other standard grades in the CCP BP series. Selection typically balances viscosity for application method and hydrolysis for end-use water resistance or solubility.

BP-14 occupies a middle ground, offering sufficient film strength for structural applications while maintaining cold-water solubility that is absent in the fully hydrolyzed BP-05 and BP-24. Compared to BP-17, its reduced viscosity permits higher formulation solids, translating into energy savings in drying-limited processes.