MatWeb - Material Property Data Advertise with MatWeb!     Register Now
Data sheets for over 170,000 metals, plastics, ceramics, and composites.
MatWeb - Material Property Data HOME  •   SEARCH  •   TOOLS  •   SUPPLIERS  •   FOLDERS  •   ABOUT US  •   FAQ  •   LOG IN    
Recently Viewed Materials (most recent at top)  

Login to see your most recently viewed materials here.

Or if you don't have an account with us yet, then click here to register.

  Searches:   Advanced  | Category  | Property  | Metals  | Trade Name  | Manufacturer  | Recently Viewed Materials
Master Bond adhesives
Covestro Bayhydur® 304 Polyurethane Coating
Categories: Polymer; Thermoplastic; Adhesives, Sealants, and Coatings; Thermoset; Polyurethane, TS

Material Notes: Hydrophilically modified, aliphatic polyisocyanate based on hexamethylene diisocyanate (HDI). As the hardener/binder component for high-quality waterborne polymer dispersions and as an additive to improve the property level of waterborne coating and adhesive systems. With respect to its composition, the product corresponds to the following sections of the U.S. FDA ’s guidelines Title 21 CFR: Section 175.105.

Properties / Applications: Because of its hydrophilic character, Bayhydur® 304 can be easily emulsified in the aqueous phase. It is used mainly as the crosslinking partner for waterborne polyol binders (Bayhydrol®) and as a crosslinker for largely pH-neutral waterborne polymer dispersions, including polyurethane (Dispercoll® U), polyvinyl acetate, polyacrylate and synthetic rubber dispersions. After addition of Bayhydur® 304, the ready-to-use two-component formulation must be used within the pot life. This is not only governed by the polymer content but also by its other constituents (resin, thickener, plasticizer, etc.). Within many dispersions, the end of this pot life – usually several hours – is not marked by gelling. The addition of 3 – 10 % Bayhydur® 304 is recommended to crosslink adhesive dispersions containing 40 – 60 % polymer. Effective mechanical stirring is required to emulsify Bayhydur® 304 in adhesive dispersions. Manual stirring by hand is not sufficient to ensure good homogenization, especially in the case of low-viscosity adhesive dispersion. Inadequate dispersion may result in the formation of granular deposits in the adhesive. Should Bayhydur® 304 be modified with an additive, this may contain no groups which react with isocyanate and no secondary components which may do so. In particular, any additives used must be free of secondary components which are alkaline or have a catalytic effect on isocyanate groups. Even at very low concentrations, these can cause an increase in viscosity or even solidification.

Information provided by Covestro

Available Properties
  • Specific Gravity, DIN 53 217/3
  • Viscosity, DIN EN ISO 3219/A.3
  • Flash Point, DIN EN 22 719
  • FDA, See notes for details.
Property Data

This page displays only the text
of a material data sheet.

To see MatWeb's complete data
sheet for this material (including
material property data, metal
compositions, material suppliers,
), please click the button below.

Manufacturer Notes:
Covestro Deutschland AG, Bayer MaterialScience

Category Notes

Some of the values displayed above may have been converted from their original units and/or rounded in order to display the information in a consistent format. Users requiring more precise data for scientific or engineering calculations can click on the property value to see the original value as well as raw conversions to equivalent units. We advise that you only use the original value or one of its raw conversions in your calculations to minimize rounding error. We also ask that you refer to MatWeb's terms of use regarding this information. Click here to view all the property values for this datasheet as they were originally entered into MatWeb.


Elmet Technologies
Please read our License Agreement regarding materials data and our Privacy Policy. Questions or comments about MatWeb? Please contact us at We appreciate your input.

The contents of this web site, the MatWeb logo, and "MatWeb" are Copyright 1996-2023 by MatWeb, LLC. MatWeb is intended for personal, non-commercial use. The contents, results, and technical data from this site may not be reproduced either electronically, photographically or substantively without permission from MatWeb, LLC.