German Technical Background VOK-425 Rheological Agent Used to Improve Flow Resistance in Aqueous Systems Replaces BYK-425

German technical background  VOK®-425 rheology additive

VOK®-425 liquid rheology additive is VOC-free for aqueous systems, adjusting the viscosity in tanks, improving flow resistance and anti-settling properties.

Product information

Chemical composition

Urea-modified polyurethane solution

Typical physicochemical data

The data presented on this data page is typical and not a product specification.

Active substance: 50%

Density (20°C): 1.04 g/ml 

Refractive index (20 °C) 1.46 

Solvent: Polypropylene glycol

Flash point: > 100 °C

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Storage and transportation

VOK®-425 should be stored in the range of 10-40°C. The additive may appear uneven due to changes in the storage environment, but this does not affect the rheological properties. Mix well before use.

Application areas

Coatings, printing inks and adhesives

Product features and benefits

The rheological properties of VOK®-425 mainly depend on the Xianghu action of waterborne resin dispersion particles, and there is obvious pseudoplastic fluid behavior. Urea-modifying additives enhance rheological properties by hydrogen bonding. VO®K-425 is VOC- and APEO-free, does not affect gloss, and its rheological properties are pH-independent.

Recommended Use

VOK®-425 is suitable for a wide range of water-based coatings, printing inks and adhesives for formulations that improve sagging resistance and adjust desired in-can viscosity. Increased viscosity while improving storage stability and reducing sedimentation. When grinding color pastes, the additive increases the viscosity of the abrasive and thus improves the dispersion conditions.

To significantly reduce the applied viscosity of formulations (e.g. for routine spraying of paints), VOK®-425 VOK®-420 (or VOK®-D 420 or VOK®-AL 7420 ES) is recommended because anti-settling is more pronounced.

Recommended dosage

0.1-2% of the total formulation of the additive dosage (in purchased form).

The above recommended dosage is for reference only, and the appropriate dosage may be determined after a series of tests.

Addition method and processing guidance

VOK®-425 can be added to the formulation at any time during the production process; It is recommended to add the last section with suitable shear forces. If VOK®-425 is used to improve the dispersion conditions of the color paste by increasing the viscosity of the abrasive, it can be added directly to the abrasive.

Due to its excellent rheological properties, the additive can cause a sharp increase in viscosity, which makes subsequent processing difficult. In this case, it is recommended that the method of pre-dilution VOK®-425 can be diluted with water (10 parts VOK®-425 + 90 parts of water), or can be used as a standard film-forming agent with a water/co-solvent mixture (e.g. 20 parts VOK®-425 + 70 parts of water + 10 parts of film forming additives). VOK®-425 has high viscosity at low temperatures, and pre-dilution can effectively reduce viscosity. The storage stability of the diluted solution needs to be tested on a case-by-case basis.

Detergents, cleaning and care products

Product features and benefits

The rheological properties of VOK®-425 depend on the interaction of surfactant micelles in the system, resulting in significant pseudoplastic fluid behavior.

In addition, urea-modifying additives further enhance the rheological properties by hydrogen bonding. This results in excellent rheological behavior, e.g. preventing the sedimentation of particles (e.g. packaged perfumes) without negatively affecting the emptying of residual containers.

VOK®-425 is VOC and APEO free. The additive is liquid easy to handle and its thickening effect does not depend on the pH value. PH value greater than 4.5 anti-settling is more obvious. Very good compatibility with surfactants, especially cationic surfactants. The rheological properties of associative thickeners depend on the composition of the respective system. The transparency of the application remains unchanged

Recommended Use

VOK-425® is used as a thickener and anti-settling agent for aqueous systems

Plant softener Clothing softener

Recommended dosage

The dosage of 0.1-1.0% of additives (purchased form) is based on the total formulation and depends on the desired performance of the formulation.

The above recommended dosage is for reference, and the appropriate dosage needs to be determined through a series of tests.

Addition method and processing guidance

VOK®-425 can be added to the formulation at any time during the formulation process; It is recommended to add the end at a suitable shear force.

Due to its excellent rheological properties, the additive may cause a sharp increase in viscosity, which makes subsequent processing difficult, and pre-dilution of VOK®-425 is recommended. Can be diluted with water (10 parts VOK®-425 + 90 parts water). VOK®-425 has high viscosity at low temperatures, and pre-dilution can effectively reduce viscosity. The storage stability of the diluted solution needs to be tested on a case-by-case basis.