SELVOL Álcool Polivinílico MM-81

SELVOL Polyvinyl Alcohol MM-81 is a partially hydrolyzed medium-molecular-weight polyvinyl alcohol supplied as a granular powder. The hydrolysis degree lies within the producer’s specified 80–90 mol% partially hydrolyzed band, and the 4 wt% aqueous solution viscosity is controlled in the medium-molecular-weight range of 7.0–9.0 mPa·s at 20 °C under the manufacturer’s certificate of analysis referencing ISO 15023-1:2017. The following application scenarios are restricted to industrial processes in which this grade functions as a temporary binder, protective colloid, surface-sizing agent, or water-soluble film modifier.

Emulsion Polymerization Protective Colloid Performance in Vinyl Acetate–Ethylene Systems

In vinyl acetate–ethylene (VAE) emulsion polymerization, MM-81 is pre-dissolved at 8.0–10.0 wt% solids in demineralized water heated to 80–85 °C, then charged to a jacketed high-pressure stirred reactor as the sole protective colloid or in combination with hydroxyethyl cellulose. Dosage is held at 3.0–6.0 wt% on total vinyl acetate monomer, with ethylene maintained at 30–60 bar and polymerization initiated by a redox pair such as hydrogen peroxide/tartaric acid or sodium persulfate/sodium metabisulfite. The reactor is typically fitted with a twin-flight turbine impeller operating at 120–180 rpm; this shear regime, combined with the medium molecular weight of MM-81, limits low-shear thickening while producing particle size distributions in the 0.8–1.8 µm range when measured by laser diffraction. Residual vinyl acetate monomer is stripped below 0.1 wt% before pH adjustment to 4.5–5.5 and filtration through 100–200 µm bag filters. Batch-to-batch viscosity is controlled by Brookfield LV measurement at 20 rpm and 25 °C, and extended storage of unpreserved aqueous solution beyond 8 h can permit microbial growth unless 0.05–0.15 wt% benzisothiazolinone is added. End-use adhesives fall under FDA 21 CFR 175.105 and, for coated board, FDA 21 CFR 176.170(c)(1); the dispersion is also formulated to meet EN 204/205 D3 and D4 wet-service wood-adhesive classes. Terminal products include VAE-based packaging adhesives, furniture edge-banding adhesives, coated paperboard cupstock, and carpet-backing binders.

Aqueous ceramic tape-casting slurries based on MM-81 are compounded at 4.0–8.0 phr on dry ceramic powder mass, with 2.0–6.0 phr polyethylene glycol 400 as plasticizer and 0.1–0.3 wt% ammonium polyacrylate dispersant. Milling is performed in a planetary ball mill using 10 mm zirconia media at 60–80% critical speed for 12–24 h, followed by de-airing under 0.05 MPa vacuum for 30–45 min to remove entrapped bubbles. The target slurry viscosity is 1500–3000 mPa·s at 10 s⁻¹, measured with a cone-and-plate rheometer before tape casting onto a polyethylene terephthalate carrier film at 0.2–0.5 m/s with a blade gap of 100–500 µm. Drying at 60–90 °C produces green tapes with 0.5–1.5% residual moisture; binder burnout is profiled at 1.0–3.0 °C/min through 350–450 °C, and total ash after 600 °C is expected to remain below 0.05 wt% when the PVOH is clean-burning. For electronic substrate applications, ionic surface contamination after burnout is verified by IPC-TM-650 Method 2.3.25, and casting rooms are commonly held to ISO 14644-1:2015 Class 7. Because the binder is removed before sintering, it does not contribute heavy metals regulated under RoHS 2011/65/EU Annex II. Terminal fired products include alumina thick-film substrates, multilayer ceramic capacitor green tapes, silicon nitride heat-dissipation substrates, and solid oxide fuel cell electrolyte tapes. Published binder burnout data for this specific grade are limited; therefore thermal profiles should be confirmed by thermogravimetric analysis on the actual slurry batch.

On flooded-nip size presses and film-transfer metering presses running coated freesheet or recycled linerboard, MM-81 is added to the surface-size formulation at 0.5–2.5 dry wt% based on size-bath solids, or at 3.0–6.0 parts per 100 parts pigment in pigmented coating colors containing ground calcium carbonate and styrene-butadiene latex. The PVOH is jet-cooked as a 12–15 wt% aqueous solution at 105–110 °C for 25–35 min, then cooled to 50–60 °C before blending with oxidized starch or dextrin. Surface-sized sheets are conditioned at 23 °C and 50% RH before verification of Cobb water absorption by ISO 535 or TAPPI T 441, and IGT pick resistance by ISO 3783:2006; typical targets for coated freesheet are 3.0–4.5 m/s pick velocity and Cobb 30–60 g/m². For food-contact board, the finished paper and paperboard fall within FDA 21 CFR 176.170 and 176.180 when the PVOH is used under good manufacturing practice. Terminal stock includes inkjet and laser printing papers, release base paper for silicone coating, folding carton board, and recycled linerboard requiring surface strength without significant pore blocking.

Unit-Dose Film Dissolution and Burst-Strength Boundaries

Where MM-81 is co-blended with higher-molecular-weight fully hydrolyzed PVOH in water-soluble film for monodose detergent packaging, the grade is typically used at 15–30 wt% of total PVOH resin. The formulation contains 10–20 phr glycerin or sorbitol as plasticizer, 0.5–2.0 phr nonionic surfactant for release, and 1.0–5.0 phr talc or starch anti-block. Film casting is conducted from a deaerated 18–25 wt% aqueous solution at 70–90 °C onto a chilled steel belt at 30–50 m/min; the dried film is conditioned to 6.0–9.0 wt% residual moisture, slit, and thermoformed into cavities at 110–130 °C. Increasing MM-81 content accelerates cold-water dissolution but reduces film modulus; package integrity is therefore measured by ASTM F2054 seal-burst testing with a 10 mm/min probe speed, and acceptance values are set by fill weight and pouch geometry. The film polymer is expected to meet OECD 301B inherent-biodegradation criteria, and finished detergent articles are subject to the EU Detergents Regulation (EC) No 648/2004 labeling and biodegradability obligations. Storage of thermoformed unfilled film above 35 °C and 60% RH produces blocking and should be avoided. Terminal products include liquid laundry monodose capsules, automatic dishwasher pouches, and soluble sachets for limited water-contact cleaning applications.

When Warp Sizing Moves to High-Speed Polyester–Cotton Slashers

Blending MM-81 with oxidized starch, acrylic copolymer, and wax in the size kitchen of a slasher sizing machine is typical for high-speed weaving of polyester–cotton blends. The PVOH content is set at 20–50 wt% of total size solids, with size-bath solids controlled at 10–14 wt% and add-on at 8–12% on warp yarn mass. The size liquor is cooked in a high-pressure cooker at 110–120 °C for 20–30 min, transferred to a size box held at 85–90 °C, and applied through a two-bowl squeeze unit with squeezing pressure 2.0–3.5 bar. Drying can temperatures are profiled from 110 °C at wet entry to 130 °C at the final cylinder, with slasher speed between 60–120 m/min depending on yarn count. Weaving performance is evaluated through loom stoppages per 10,000 picks and ends-down per 100,000 ends, rather than only size film strength. Desizing is carried out in hot water at 70–90 °C or with amylase enzyme systems for the starch fraction; PVOH contributes no adsorbable organically bound halogens and is compatible with discharge limits under EU Industrial Emissions Directive 2010/75/EU best-available-technique conclusions for textile wet processing. The formulation should avoid addition of nonylphenol ethoxylates because ZDHC MRSL Version 3.0 bans their intentional use. Finished woven articles include polyester–cotton shirting, denim, automotive upholstery, and industrial workwear.

An aqueous remoistenable adhesive based on MM-81 is applied to envelope flap paper and paper tape at 5.0–15.0 wt% solids, with 5.0–20.0 phr dextrin or sucrose plasticizer and 0.1–0.3 wt% defoamer. Mixing is carried out in a jacketed scraped-wall kettle at 70–80 °C until a homogeneous solution is obtained, then cooled to 40–50 °C before application by gravure cylinder or slot-die coater at 80–150 m/min. Coated paper is dried in an air flotation dryer at 60–90 °C to a dry coat weight of 3.0–8.0 g/m². Rewet tack is assessed after exposing the coated surface to 20–30 µm water film thickness, with peel adhesion measured by ASTM D903 using a 300 mm/min crosshead speed. Food-contact status is covered by FDA 21 CFR 175.105 for the adhesive component and by FDA 21 CFR 176.170 for finished paperboard. The adhesive is not intended for water-resistant bonds; exposure to liquid water after sealing will reverse the bond. Terminal uses include envelopes, paper tapes, labels, stamps, and paper tube winding adhesives.

Dry-mix cementitious tile adhesives and gypsum compounds use MM-81 as a low-dosage water-soluble rheology and adhesion aid at 0.3–1.0 wt% on total dry mix weight for C2-class tile adhesives, or 0.5–2.0 wt% in gypsum-based joint compounds. The grade is dry-blended in a horizontal paddle mixer with cellulose ether, redispersible polymer powder, calcium formate, and cement or gypsum at 60–120 rpm for 5–10 min. After water addition at 20–25 wt%, the wet mortar is mixed with a 600 W low-speed paddle mixer at 400–600 rpm for 3 min, rested for 2 min, and remixed for 1 min. Open time is tested according to EN 12004-2:2017 by fixing tile specimens after 5, 10, 20, and 30 min intervals; tensile adhesion after water immersion and heat ageing should meet the ≥0.5 N/mm² requirement for C2 classification under ISO 13007-1:2014. Because PVOH dissolves in mixing water, the grade is not suitable for permanent water-immersion applications or for areas where wetting and drying cycles exceed the film’s leach resistance; modification with a water-resistant redispersible powder is required. Terminal products include cement-based tile adhesives, repair mortars, gypsum joint compounds, and cement-based grouts.