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Enhancing Seed Performance with KURARAY POVAL™ Coatings
Seeds are the foundation of agriculture, and maximizing their potential is key to achieving optimal yields. One innovative method for enhancing seed performance is through the use of polyvinyl alcohol (PVOH) coatings.
Protective Film for Enhanced Performance
When seeds are coated with KURARAY POVAL™, they are enveloped in a protective film. This film serves multiple purposes, including dust reduction and protection against environmental stressors. The water solubility and mechanical strength of the PVOH film can be precisely controlled, ensuring tailored protection for each seed.
Improved Germination and Performance
One of the most significant benefits of KURARAY POVAL™ coatings is their ability to improve germination rates. By creating an optimal microenvironment around the seed, PVOH coatings promote faster and more uniform germination. Additionally, the enhanced protection provided by the PVOH film can lead to improved seedling vigor and overall crop performance.
Versatile Application Methods
KURARAY POVAL™ coatings offer versatility in application methods, allowing for seamless integration into existing seed treatment processes. Whether through seed coating equipment or specialized application techniques, PVOH coatings can be efficiently applied to a wide range of seed varieties.
Aiding Delivery of Active Ingredients
Beyond their protective properties, KURARAY POVAL™ coatings serve as an effective binder for incorporating active ingredients into seed treatments. This technology facilitates the precise delivery of agrochemicals, fertilizers, and other additives directly to the seed surface. By enhancing the efficiency of nutrient uptake and pest control, PVOH coatings contribute to improved crop health and yield potential.
The KURARAY POVAL™ polymers with a solubility of more than 2 g/L are exempted from the synthetic polymer microparticles definition.
In October 2023, the regulations by the European Union Commission have attention to the issue of synthetic polymer microparticles, commonly known as microplastics. Regulation (EU) No. 2023/2055 aims to restrict the use of microplastics in various products and applications.
According to the regulation, polymers with a solubility of more than 2 g/L are not designated as microplastics. Additionally, degradable polymers that meet the specific criteria outlined in the regulation are also exempt.
We can state that partially saponified KURARAY POVAL™ grades (with a degree of hydrolysis less than 92%), have passed the solubility test (>2 g/L) in accordance with the Regulation (EU) No. 2023/2055 Appendix 16`Rules on proving solubility.
For various applications, the following KURARAY POVAL™ grades are specified:
ENCRUSTING:
KURARAY POVAL™ 5-74 and KURARAY POVAL™ 22-88.
FILM COATING:
KURARAY POVAL™ L-508W and EXCEVAL™ RS-1717.
PELLETING:
KURARAY POVAL™ 18-88 and KURARAY POVAL™ 13-88.
These KURARAY POVAL™ grades are recommended for their specific properties suited to each application. However, recommendations may vary depending on the customer's specific needs and requirements.
As we navigate the challenges of environmental sustainability, it is crucial for industries to prioritize the use of materials that meet regulatory standards and contribute to a sustainable future.
Key Benefits in Seed Coatings:
The utilization of KURARAY POVAL™ in seed coatings offers a multitude of benefits, including:
1. LOW DUST-OFF PROPERTIES:
Dust generation of soya beans is significantly reduced by coating seeds with PVOH, leading to improved handling efficiency and reduced environmental impact.
2. IMPROVED GERMINATION:
Contrary to concerns about coating materials negatively impacting germination rates, soya bean seeds coated with KURARAY POVAL™ demonstrated no negative or even enhanced germination performance. Cold germination rates, in particular, have shown improvement with KURARAY POVAL™ coatings, potentially due to the controlled moisture content provided by the coating.
3. HIGH BONDING POWER:
KURARAY POVAL™ coatings exhibit exceptional bonding power, ensuring that the coating layer adheres well to the seed surface, providing durable protection throughout the germination and early growth stages.
4. INHERENT BIODEGRADABILITY:
KURARAY POVAL™ is recognized as one of the few vinyl polymers that are water-soluble and inherently biodegradable in the presence of microorganisms.
KURARAY POVAL™ and Seed Encrusting
Various grades of KURARAY POVAL™ can be used for seed encrusting. A good balance between polymer molecular weight as well as viscosity and concentration of the binder solution is very important.
The data in Figure 5 shows that higher molecular weight KURARAY POVAL™ grades (13-88 and 22-88) demonstrate lower dust-off compared to lower molecular weight grades (6-88) at the same concentration. This is linked to higher mechanical strength and binding power of the high molecular weight grades.
This outcome is expected, as higher molecular weight grades offer greater mechanical strength and binding power. To ensure good coating quality and binder dispersion, the coating liquid must maintain proper flow behavior, which can be challenging with high molecular weight polymers due to increased solution viscosity at higher concentrations. Therefore, selecting the appropriate concentration for a specific grade is very important.
Besides molecular weight, the degree of hydrolysis (DH) is the second key parameter that largely influences the properties of PVOH and thus the final coating quality. Based on the data obtained from the laboratory screening, the lower DH grades KURARAY POVAL™ 5-74 and 5-82 seem to perform better than KURARAY POVAL™ 6-88 at the same concentration, demonstrating reduced dusting and agglomeration (Figure 6). This effect may be attributed to lower surface tension resulting from a reduced degree of hydrolysis.
Influence of polymer molecular weight on dust-off
Figure 5. This graph illustrates the effect of polymer molecular weight on the dusting properties of coated seeds. A total of 100 g of grass seed (Festuca rubra) was encrusted with 100 g of pure CaCO₃ using 34 mL of a 7% solution of KURARAY POVAL™. The coating process was carried out in a Hoopman HR 160 laboratory rotary coater (⌀16 cm).
Influence of degree of hydrolysis on dust-off
Figure 6. This graph illustrates the effect of the degree of hydrolysis (DH) on the dusting properties of coated seeds. All tested grades had comparable molecular weight while having variations in the degree of hydrolysis from 74-88%. A total of 100 g of grass seed (Festuca rubra) was encrusted with 100 g of pure CaCO₃ using 34 mL of a 7% solution of KURARAY POVAL™. The coating process was carried out in a Hoopman HR 160 laboratory rotary coater (⌀16 cm).
Conclusion
In summary, KURARAY POVAL™ with up to 92% hydrolyzation is a cutting-edge solution for seed treatment, enhancing crop productivity through tailored protection, improved germination, and efficient delivery of active ingredients. Its superior encrusting ensures strong adhesion, minimal dust-off, and high-quality coatings for reliable and efficient seed treatment. Discover now how KURARAY POVAL™ can add value to your products.
About Kuraray
Kuraray is a globally active specialty chemicals company and manufacturer of innovative high-performance materials. The company produces in Japan, Singapore, Germany, and the USA its wide range of polyvinyl alcohol (PVOH/PVA) grades under well-known brands such as KURARAY POVAL™, EXCEVAL™, ELVANOL™, and MOWIFLEX™.
The latest Life Cycle Assessment (LCA) estimates that the CO2 footprint can be reduced to 1.62 kg CO2 equivalent, containing bio-ethylene (mass balance approach).
Kuraray’s global production and service network makes us your partner of choice for innovative high-quality PVOH resins.
Kuraray's Event Schedule for 2025
ISF World Seed Congress 2025
Location: Istanbul, Turkey
Dates: May 19-21
Booth: 1.19
Euroseeds 2025 Congress
Location: Edinburgh, Scotland
Dates: October 19-22
ASTA Field Crop Seed Convention 2025
Location: Orlando, Florida
Dates: December 9-12
APSA 2025
Location: Mumbai, India
Dates: November 17-21
We look forward to seeing you there!
Visit our website at www.kuraray-poval.com and discover our solutions for agriculture. For more information about KURARAY POVAL™, please contact Heiko Mack at heiko.mack@kuraray.com or use our contact form at the website.
This story was initially published in the 2025 Seed Treatment Special. Download the magazine to read more stories.
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