* These values provide general information and are not part of the product specification.
Product description
Water-thinnable, aliphatic, blocked polyisocyanate.
Applications
Bayhydur® BL 2781 was developed as a hardener for water-thinnable, lightfast, one-component polyurethane stoving coatings. The properties of paint films formulated with Bayhydur® BL 2781 can be influenced like conventional two-component polyurethane coatings via the degree of crosslinking and the choice of polyol.
Typical areas of application include:
- Automotive production coatings (impact-resistant primers, fillers, topcoats)
- High-quality stoving industrial coatings (e.g., electrical appliances, small parts, automotive components)
Form supplied
Dispersion in water/dimethylethanolamine (61.1 : 2.4) with a non-volatile content of approx. 36.5 %.
Specification
| Property | Test Condition | Value | Unit | Standard |
|---|---|---|---|---|
| Non-volatile content | 1.0 g / 60 min / 125°C | 35.0 - 38.0 | % | M020 - ISO 3251 |
| Dynamic viscosity | D = 40 1/s / 23°C | 800 - 9,000 | mPa·s | M014 - ISO 3219/A.3 |
| pH-value | 20 °C | 8.0 - 10.0 | M022 - ISO 976 |
Typical Values
| Property | Test Condition | Value | Unit | Standard |
|---|---|---|---|---|
| NCO content, blocked | theoretical | approx. 3.5 | % | |
| Equivalent weight | approx. 1,200 |
Principal properties
In combination with Bayhydrol® polyols in the formulation of water-thinnable, lightfast, one-component polyurethane stoving coatings. Also as an additive to improve the flexibility, impact strength and adhesion of conventional aqueous stoving systems.
Solubility / thinnability
Bayhydur® BL 2781 can be thinned with water, alcohols, glycols and glycol ethers.
Storage
- Storage in original sealed Covestro container.
- Recommended storage temperature: 5 - 30 °C.
- Protect from direct sunlight, frost, heat and foreign material.
General information: The product is sensitive to frost. Freezing can damage the product irreversibly. Prolonged storage at higher temperatures may affect the product properties. Containers must be kept sealed and protected from direct sunlight as otherwise the evaporation of water will result in the formation of a non-redispersible polymer film.
Contamination with certain bacteria, fungi or algae may render the product unusable.
Storage time
Covestro certifies that the product meets specifications for 3 months from the date of shipment, provided it is stored and handled in accordance with the conditions specified in the ‘Storage’ section. After this period, product performance is not assured; Customers are responsible for retesting material before use. Covestro assumes no liability for product performance after 3 months.
Processing
Depending on the degree of crosslinking and the co-reactant used, Bayhydur® BL 2781 crosslinks at temperatures in the range of 130 °C – 180 °C in 30 – 60 min.
Depending on the stoving temperature/time and the polyol used, slight to severe thermal yellowing may occur.
Health and Safety Information
Before working with this product, you must read and become familiar with the available information regarding its risks, proper use, and safe handling. This information is provided in various formats, including the current Safety Data Sheet (SDS) and product label. SDS can be accessed via the following link:
Safety Data Sheets (SDS) for Covestro products | Covestro
For further questions, please use the contact information provided on this technical data sheet.
Disclaimer
Responsibility and Liability
The use of Covestro products, technical assistance, and information (regardless of how provided) is outside Covestro’s control and is solely the responsibility of the customer. The customer must conduct adequate testing to determine the suitability of products for its intended use, including but not limited to technical, health, safety, and environmental aspects. Unless otherwise agreed in writing, all products are sold exclusively under Covestro’s standard conditions of sale, which prevail in case of conflict and are available upon request.
The terms and conditions of sale and delivery are available via the following link:
https://order.covestro.com/covestrostorefront/saleConditions
All information is provided “as is” without warranties, express or implied, including merchantability or fitness for a particular purpose, and is subject to change without notice. To the maximum extent permitted by law, Covestro disclaims, and the customer assumes all liability for losses, damages, or claims arising out of use of Covestro products, technical assistance, or information. Any statement or recommendation not expressly contained in Covestro documentation is unauthorized and shall not bind Covestro. Nothing herein shall be construed as encouraging or recommending the use of any product in conflict with any claim of any patent. No license is implied or in fact granted under the claims of any patent.
Restrictions on Regulated Applications
This product is not intended for use in regulated applications such as agriculture, cosmetics, drinking water contact, food contact, medical products (e.g., medical devices), toys, or similar uses subject to specific regulatory requirements. Prior written approval from Covestro is required before this product may be used in any regulated application. The customer is solely responsible for ensuring compliance with all applicable laws and determining product suitability. Covestro disclaims all liability and warranties for unauthorized regulated uses.
Typical Value
The values provided are typical only and do not represent binding specifications. Unless expressly confirmed in a written contract, these values are not part of the contractual quality agreement and must not be relied upon as a warranty or guarantee of product performance.
Sample
Samples provided by Covestro are intended solely for evaluation and testing purposes by the customer and may not be used in commercial applications, resold, transferred to third parties (except qualified testing service providers acting on behalf of the customer), reverse engineered, modified, or used in any manner not explicitly authorized in writing by Covestro. Samples are provided ‘as-is’ without any warranties, express or implied, including fitness for a particular purpose. Customers are solely responsible for ensuring safe handling, regulatory compliance, and suitability of the material for their intended evaluations. Covestro disclaims all liability for damages or losses arising from the use of samples.
Contact Information
Please use our contact form or contact us directly by sending an e-mail to technical-datasheets@cx.covestro.com .
