EXCEVAL HR-3010

EXCEVAL HR-3010 is a grade designation within the polyvinyl alcohol resin series supplied under the EXCEVAL trade name. The material is handled as an aqueous solution in coating, sizing, and binder operations. Publicly available lot-specific data for this exact grade is limited; therefore, all numerical acceptance limits must be taken from the supplier’s certificate of analysis rather than from secondary summaries. The information below separates class-level behaviour common to polyvinyl alcohol resins from properties that remain grade-specific.

Specification handling for this product follows the test matrix used for polyvinyl alcohol raw materials. The relevant methods are listed because the certificate of analysis is not a single number but a set of method-dependent results.

What Is Confirmed by the Certificate of Analysis for EXCEVAL HR-3010?

Polyvinyl alcohol grade specifications are conventionally reported for solution viscosity, degree of hydrolysis, volatile matter, ash, and pH. Solution viscosity is measured on a 4% aqueous solution at 20 °C using a rotational viscometer; this value is an indirect measure of molecular weight and affects film tensile potential and solution handling. Degree of hydrolysis is reported in mol% and controls cold-water solubility, solvent resistance, and interaction with co-binders. Volatile matter and ash are specified to control storage stability and thermal discolouration. The certificate of analysis should state the test method revision for each lot because results obtained under JIS K6726 and ISO 15023-2 are not interchangeable without documented correlation.

No cross-grade comparison should be made without normalizing solution solids and test temperature. Two polyvinyl alcohol grades with identical 4% viscosity can differ in degree of hydrolysis, and that difference alters dissolution temperature, film redispersibility, and compatibility with insolubilizers. For EXCEVAL HR-3010, the controlling technical data sheet should be checked for lot-specific viscosity range and hydrolysis target before the resin is substituted into an established formulation. Analytical verification of the lot should also include solution clarity after cooling to 25 °C and after 24 h storage, because microgel or incompatibility may develop slowly.

When the Resin Is Evaluated as a Surface Sizing Agent or Barrier Coating

Application trials for this resin class are typically conducted on a pilot size press, rod coater, or blade coater. The dry coat weight and substrate surface roughness determine whether the applied layer is continuous. On high-roughness paperboard, laboratory rod drawdowns below 1.5 g/m² can produce pinholes and channels, while a blade coater operating with backing roll loads in the 20–40 kN/m range is used to close the gap. These values are equipment conditions common in paper converting and are not grade-specific performance limits.

Grease resistance is measured by TAPPI T 559, water absorption by ISO 535, and oxygen transmission rate by ASTM D3985 at 23 °C and 0% relative humidity. High-humidity exposure of polyvinyl alcohol films increases oxygen permeability because water plasticizes the amorphous phase. Comparative batching trials should fix the conditioning atmosphere and report the relative humidity at which transmission values are obtained. Published data for EXCEVAL HR-3010 under these exact coating conditions is limited, so pilot results should not be extrapolated beyond the substrate lot and coating method used.

Field observations from high-speed coating lines indicate that pinhole defects in polyvinyl alcohol barrier layers are typically caused by foam, filter bypass, or substrate dust rather than by the resin alone. Foam is controlled by vacuum deaeration of the coating colour and by maintaining return-line submergence. Filter bypass occurs when differential pressure across the bag filter exceeds 1.5 bar, forcing solution through the bypass valve. Substrate dust and loose fibre are addressed with a vacuum brush or air knife before the coating station. These equipment failure modes are reproducible across water-soluble polymer coating systems and should be considered in any troubleshooting sequence for EXCEVAL HR-3010.

Surface sizing comparisons against oxidized starch show a practical separation: starch requires in-line thermal or enzymatic conversion and yields lower film continuity, whereas polyvinyl alcohol forms a continuous film after drying. Conventional polyvinyl alcohol may differ from EXCEVAL HR-3010 in viscosity stability under circulation or in gelation tendency with borate-based insolubilizers. These differences must be confirmed by rheological measurement because the grade designation alone does not indicate enough about molecular weight distribution.

Dissolution, Filtration, and Rheological Stability

Solution preparation is the first critical variable in production behaviour. A cold-water pre-slurry at 10–20 °C is prepared under low-shear agitation, then heated in a jacketed vessel to 90–95 °C. Complete dissolution for high-hydrolysis polyvinyl alcohol typically requires 30–60 min after reaching temperature, but the exact hold time depends on particle size, agitator design, and batch volume. Steam-jet cookers reduce heating time but introduce shear and condensate dilution, which must be accounted for in the final solids balance. Undissolved gel particles are removed with a bag filter rated at 100–150 µm before the solution enters the coating circulation loop.

Viscosity stability during circulation is evaluated with a Brookfield or cone-and-plate rheometer. Extended hold at 80–85 °C can shift viscosity through water loss or polymer rearrangement. Closed jacketed tanks with slow sweep agitation are preferred over open tanks at high temperature. Defoamer addition must be controlled because some mineral-oil defoamers reduce film clarity and interact with downstream sizing chemicals. Compatibility tests should be performed with the complete formulation, not with the resin solution alone.

Rheological data for aqueous polyvinyl alcohol solutions generally show shear-thinning behaviour at process concentrations. Viscosity measurements taken on a single-spindle Brookfield at low shear do not predict blade coater behaviour under high shear. Capillary or high-shear viscometry gives more relevant data for metering and film splitting. Lot-to-lot variation in molecular weight may appear as viscosity drift under circulation; a control chart of 4% solution viscosity is therefore more useful than a single acceptance threshold. The certificate of analysis should be trended against process data to detect shifts before they affect coat weight.

When compared with ethylene-vinyl alcohol copolymer, the first difference is water solubility. Polyvinyl alcohol is processed as an aqueous solution, while ethylene-vinyl alcohol is melt-processed and is not water-soluble under typical coating conditions. The second difference is barrier behaviour: ethylene-vinyl alcohol provides oxygen barrier at low relative humidity, whereas polyvinyl alcohol barrier is more sensitive to moisture unless crosslinked or combined with a hydrophobic topcoat. When compared with oxidized starch, the polyvinyl alcohol class generally requires lower coating weight for a continuous grease-resistant layer on smooth substrates, but the cost per dry kilogram is higher. These distinctions are class-level and may not hold for every formulation batch.

Mechanical film comparisons should use standardized film preparation and conditioning. Tensile test specimens are prepared by casting or drawdown and conditioned at 23 °C and 50% relative humidity before testing according to ISO 527-3 or ASTM D882. Without controlled drying thickness and residual moisture, tensile differences between products are confounded by orientation and plasticizer effects. For EXCEVAL HR-3010, published tensile data under these conditions is limited; therefore, any quoted film property should be traced to a specific supplier report or lot certificate.

Degree of hydrolysis is not measured directly in most production laboratories. It is calculated after saponification or infrared analysis according to the method named on the certificate. For grades near the high-hydrolysis end, a difference of 1 mol% can change the solution cloud point and compatibility with pigments. Aqueous solution haze should be measured after cooling to 25 °C and after 24 h storage, because microgel or incompatibility may develop slowly.

Food-contact suitability is not an inherent resin property. Paper and paperboard applications require compliance with FDA 21 CFR 176.170 or the applicable European framework under EU Regulation 10/2011. Overall migration testing under EU Regulation 10/2011 uses simulant selection based on food type, and the limit for overall migration is 10 mg/dm² of contact area. The converter is responsible for documenting that the final coated article meets the relevant national or regional conditions of use.

Industrial hygiene assessments should address dust generation from granular handling. Dust cloud explosibility is characterized according to ASTM E1226 or EN 14034 if the plant dust hazard analysis identifies a combustible dust zone. Dust extraction at bag dumping stations should be commissioned to achieve a dust concentration below the lower explosive limit. Warehouse storage should avoid open flames and strong oxidizers.

Borate-based insolubilizers should not be added directly to an unstabilized polyvinyl alcohol solution without pH buffering and delayed addition. Borates promote gelation through diol complexation, which can blind filters, increase coat weight variability, and produce insoluble deposits in narrow coater lines. Ammonium persulfate or other oxidizers used for viscosity reduction must be evaluated for residual odour and film colour. Pre-drying of resin is recommended when relative humidity repeatedly exceeds 60% in the warehouse, because moisture uptake changes the effective solids if formulations are not adjusted.