EXCEVAL HR-3010

During seeded semi-batch emulsion copolymerization of vinyl acetate and ethylene at reactor pressures between 3.0 MPa and 7.0 MPa, the aqueous-phase stabiliser must satisfy conflicting requirements. It must provide colloidal protection during monomer emulsification. It must not suppress radical entry into polymer particles. It must graft to developing polyvinyl acetate chains without forming crosslinked reactor foulant. EXCEVAL HR-3010 acts as a polyvinyl alcohol protective colloid in this service. Its addition mode influences final dispersion particle size, shear stability, and coagulum formation.

Aqueous PVOH is prepared by dispersing the granular resin in demineralised water at 25 °C and heating to 85–95 °C under low-shear agitation for 45–60 min. The stock solution is then cooled to 60 °C before feed-tank transfer. For vinyl acetate-ethylene dispersion production, colloid input is normally controlled between 3.0 phm and 8.0 phm relative to total vinyl acetate monomer. Higher colloid loadings reduce coagulum and median particle size but increase hydrophilicity of the free film. Lower loadings produce more water-resistant films but raise reactor fouling risk. The exact set point is determined by desired emulsion viscosity, dry-film water resistance, and end-use adhesive performance.

Process monitoring uses a 20 m³ glass-lined stirred tank reactor rated for 6.0 MPa ethylene pressure. A 45 kW two-stage impeller maintains specific power input near 1.3 kW/m³. Ethylene mass transfer is enhanced by a gas circulation compressor and a dip-pipe sparger. Reaction temperature is held at 55–85 °C with a jacket and external heat exchanger. Redox initiation using persulfate and sodium formaldehyde sulfoxylate is common. The pH is kept between 4.0 and 5.5 with a bicarbonate buffer. Deviation above 5.8 reduces grafting efficiency and increases free PVOH in the serum. Deviation below 3.8 accelerates equipment corrosion and may destabilise the dispersion.

Dispersion quality is checked after monomer reduction. Viscosity is determined according to ISO 2555:2018 with a Brookfield RVT viscometer, spindle 4, 20 rpm, 25 °C. Solids are measured by ISO 3251:2019. pH is measured by ISO 976:2013. Particle size distribution is determined by laser diffraction or dynamic light scattering using ISO 22412:2017. A production batch containing 6.0 phm colloid may exhibit median particle diameter between 0.8 µm and 1.4 µm; published product-specific data for EXCEVAL HR-3010 at this exact configuration is limited. Coagulum is separated through a 100 µm in-line screen. The accepted level is below 0.05 mass% of total discharge. Higher coagulum indicates poor colloid distribution, insufficient mixing, or incorrect initiator feed profile.

Formulation constraints must be observed in hold tanks and post-treatment vessels. Polyvalent metal salts, borate ions, and cationic coagulants must not enter the hold tank. They destabilise PVOH-stabilised dispersions by ionic bridging. The resulting grit causes screen blockage and downstream filter plugging. Mineral-oil-based defoamers can reduce dispersion stability if overdosed. Plasticising comonomers and coalescing solvents must be added slowly under agitation. Insufficient blending produces localised gel bodies. The dispersion then fails filtration. These limits are consistent across vinyl acetate homopolymer and vinyl acetate-ethylene copolymer production lines; product-specific optimisation for EXCEVAL HR-3010 is required.

What Limits Add-On Uniformity on High-Speed Slasher Lines Running Cotton-Wrapped Elastane Warps?

Slasher add-on variability is controlled less by size solids than by nip geometry, size-box viscosity, and drying-cylinder temperature balance. On a modern sizing machine running 900–1,200 m/min, size pick-up must remain between 8 wt% and 12 wt% dry add-on for ring-spun cotton warps. Below this range, hairiness increases and loom stop motion rises. Above 14 wt%, the sized yarn becomes brittle and shedding accumulates in the weaving shed.

A size mix for this application can contain 85 parts oxidised corn starch, 15 parts EXCEVAL HR-3010, and 3 parts tallow-based lubricant on dry solids. Size solids are held at 10–13 wt%. The mixture is cooked at 90–95 °C for 30 min and held at 85 °C in the size box. Viscosity is checked with a No. 2 Zahn cup. The control window is 9–12 s. Lower viscosity causes excessive penetration into the yarn core. Higher viscosity creates a surface film that splits unevenly at the front nip.

Squeeze pressure is set between 25 kN/m and 60 kN/m on the front nip. The rear nip runs at 10–20 kN/m to pre-wet the warp. Drying cylinder surface temperatures decrease from 130 °C at the feed end to 95 °C at the delivery section. This staged profile prevents surface skinning. Skin formation traps moisture in the yarn core and reduces size adhesion. Batch-to-batch variation in size-box pH above 7.5 can shift PVOH solubility and alter pickup; pH is therefore recorded every 30 min during the run.

Sized warp tensile strength is measured according to ASTM D2256/D2256M-21 at 65% RH and 21 °C. Warp strength retention is normally not less than 85% of the unsized value. Weaving performance is tracked by warp stops per 100,000 picks. A well-formulated starch-PVOH size film reduces stops by increasing abrasion resistance. Do not combine this PVOH with borate-modified starch. Borate ions crosslink dissolved PVOH. The size-box viscosity then rises above 20 s, causing uneven add-on and poor desizing.

Desizing is carried out with α-amylase at 0.5–1.0 g/L and 70–80 °C. Starch hydrolysis exposes PVOH. Hot water washing at 90 °C then removes PVOH. The corresponding effluent load is lower than with fully synthetic size chemistry. This is advantageous in mills with biological treatment limits or strict chemical oxygen demand discharge caps.

A metering size press cannot function as a simple coater when the surface size contains a high-molecular-weight PVOH. On a high-speed paper machine operating near 1,200 m/min, size viscosity above 80 mPa·s at 60 °C creates film-split instability and rod bleed. EXCEVAL HR-3010 is introduced as a co-binder into thermally oxidised starch to raise surface strength without producing excessive film splitting. The addition level is low. It is typically 0.5–2.0 parts per 100 parts dry starch. Total size solids are maintained at 8–12 wt%.

Size preparation uses a jet cooker at 105–120 °C. The PVOH is pre-dissolved as a 10 wt% solution and added after starch cooking. This sequencing prevents retrogradation and local gel formation. Calcium stearate dispersion at 0.2–0.5 parts is added as a sizing aid to reduce rod bleed. The size is filtered through 100 µm screens before the metering headbox. Screens are inspected at each reel turn-up. Accumulation of gel particles on the screen indicates incomplete PVOH dissolution or starch retrograde.

Performance is assessed by water absorptiveness using ISO 535:2014. A reduction in Cobb60 values of 5–15 g/m² is common when PVOH replaces part of the starch, but actual results depend on base paper porosity and film thickness. Surface pick strength is measured by the IGT accelerated method according to ISO 3783:2006. The PVOH-containing film resists picking more effectively because it forms fewer microcracks at the starch film surface. Surface dusting is evaluated by a ten-point tape pull method. Dried size films containing PVOH generally show less starch dusting than starch-only controls.

Limitations exist above 3.0 parts PVOH per 100 parts starch. The dried size film becomes moisture-sensitive. Offset printing fountains with high conductivity cause partial redissolution. Blanket picking then increases. This failure appears as star-shaped fibre pulls on the printed sheet. It is not a defect of the PVOH alone. It is a dosage conflict between water resistance and film strength. The size formulation also must avoid free borate ions because PVOH responds to borate crosslinking at the size press, changing rheology within the applicator loop.

Ranges represent production-control references for formulations containing EXCEVAL HR-3010. They must be validated for each line because substrate porosity, dryer capacity, and operator set points shift the measured outcomes.

Binder Burnout Ramp Design for Spray-Dried Alumina Granulate

Dry-pressed technical alumina components require a green body that survives ejection, machining, and kiln loading before sintered density develops. EXCEVAL HR-3010 is used as a temporary binder in spray-dried ceramic granulate at 0.8–2.0 wt% on dry solids. The ceramic slip is prepared with alumina powder, deflocculant, and water. The PVOH solution is added as the final component to avoid interaction with anionic dispersants. Slip solids are typically 60–70 wt%. The slip is atomised through a rotary atomizer at 14,000 rpm. Inlet temperature is 210–230 °C and outlet temperature is 95–105 °C.

Granulate moisture is controlled to 0.5–1.0 wt%. Particles between 75 µm and 250 µm are preferred for die filling. Green flexural strength is evaluated by three-point bending at 2 mm/min crosshead speed over a 50 mm support span. The load cell is calibrated to ISO 7500-1:2018. At 1.5 wt% binder, green flexural strength commonly falls between 1.5 MPa and 3.0 MPa. Published data for EXCEVAL HR-3010 in this exact alumina system is limited; a laboratory binder dose-response test is required before kiln-scale introduction.

Burnout is a process-critical step. The green body is heated at 1–2 °C/min from 20 °C to 450 °C and held for 2 h. Faster ramps produce carbon residue because oxygen diffusion becomes rate-limiting in thick sections. PVOH begins oxidative decomposition near 220 °C in air. The differential thermal analysis exotherm must not overlap the sintering ramp. If the exotherm is too rapid, internal pressure cracks appear at the transition to densification. Kiln atmosphere is controlled with excess air above 400 °C to complete oxidation.

Process limitations include interaction with fine metallic powders. Iron or copper contaminants catalyse PVOH decomposition at lower temperatures. This shifts the burnout exotherm and can generate volatile by-products within the kiln. Ash specification after binder burnout is usually below 0.1 wt% for technical ceramics. Granulate storage must be sealed below 60% RH. Moisture absorption softens granules and reduces die fill uniformity. Dry-press tooling should be cleaned after each 10,000 cycles because PVOH residues accumulate in vents and increase ejection force.

The conversion of EXCEVAL HR-3010 into a cold-water-soluble film for unit-dose household chemical packaging is governed by residual moisture, plasticiser distribution, and drying-zone humidity rather than by dissolution temperature alone. A casting solution of 14–18 wt% solids is prepared in demineralised water. The solution is deaerated under vacuum at 10 kPa absolute for 30 min. A slot die at 80–85 °C deposits the solution onto a stainless steel belt. Drying zones operate from 90 °C to 130 °C. Final film moisture is conditioned to 8–12 wt%. Moisture outside this range changes blocking behaviour and tensile elongation on converting lines.

Film properties are measured according to ISO 527-3:2018 at 23 °C and 50% RH. For a 75 µm film, tensile strength is evaluated in machine and transverse directions. The ratio of transverse to machine tensile strength is used as an orientation indicator. Glycerin or sorbitol at 10–20 phr is added to reduce brittleness. Higher plasticiser content slows dissolution. Lower plasticiser content raises film modulus but increases pinholing risk at die edges. The film should not be exposed to relative humidity above 60% without moisture barrier packaging. Unprotected film blocks and becomes unprocessable on high-speed form-fill-seal machines.

Dissolution performance is tested in deionised water at 20 °C under magnetic stirring. Thin films typically disintegrate below 90 s, but the exact value depends on film crystallinity, plasticiser type, and water chemistry. Hard water ions and alkaline salts alter solubility. The converting line must control static charge. A 25 kV static pinner is used with a 1,200 mm slot die. Line speed is limited by drying capacity rather than melt rheology because PVOH is processed from aqueous solution. High carbonate levels in alkaline detergents above 30% can plasticise the film prematurely and reduce pouch burst resistance.

When Reverse-Gravure Deposition Replaces Roller Coating on Repulpable Label Stock

If the adhesive is applied at 2.0 g/m² dry coat weight through a reverse gravure applicator, then rewetting tack and paper repulpability are retained without the solvent load associated with hot-melt systems. An aqueous PVOH adhesive prepared from EXCEVAL HR-3010 is coated on lithographic label stock. The solution solids are 12–15 wt%. Viscosity is controlled between 200 mPa·s and 600 mPa·s at 25 °C using ISO 2555:2018, spindle 2, 30 rpm. The reverse gravure station uses a 200 mm ceramic anilox roll with 120 cells/cm. Drying is carried out in a hot-air tunnel at 80–110 °C with 3–5 s dwell. Residual moisture is held at 5–8 wt%.

Rewetting performance is evaluated by applying 15 g/m² water mist and measuring open time. Acceptable open time is 10–20 s on clay-coated paper. Below 10 s the operator cannot register the label accurately. Above 20 s the adhesive may dry again before lamination pressure is applied. Adhesive film thickness above 3.5 g/m² creates blocking in ream storage. Blocking is measured under 10 kN/m² pressure at 40 °C for 24 h according to an internal laboratory method based on ISO 11556:2005.

Repulpability is a key requirement. The dried adhesive must disperse under neutral repulping at 45 °C. A 0.08 mm slotted screen is used to measure rejects. Well-dried PVOH adhesive films generally break into small fragments that pass the screen. The resulting fibre yield is sufficient for paper machine operation; published data for this specific label construction is limited and must be verified on the mill stock preparation line.

Process limitations include incompatibility with UV-curable topcoats. UV ink must be fully cured before adhesive application. Residual photoinitiators can cause yellowing of the PVOH film. The adhesive is also sensitive to high wet-end pH above 9.5 in repulping. Under these conditions the PVOH swells but does not dissolve cleanly. The label stock must be unsupported film-free. Film liners must be removed before repulping because liner fragments block the slotted screen and increase rejects.