Applications
Because of its hydrophilic character, Bayhydur® ultra 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® ultra 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® ultra 304 is recommended to crosslink adhesive dispersions containing 40 – 60 % polymer. Effective mechanical stirring is required to emulsify Bayhydur® ultra 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® ultra 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.
Specification
| Property | Test Condition | Value | Unit | Standard |
|---|---|---|---|---|
| NCO content | 18,2 ± 0,5 | % | M105-ISO 11909 | |
| Viscosity | at 23 °C | 4,000 ± 1,500 | mPa*s | M014-ISO 3219/A.3 |
| Color value | (Hazen) | ≤ 60 | M017-EN 1557 | |
| Monomeric HDI | < 0,10 | M106-ISO 10283 |
Typical Values
| Property | Test Condition | Value | Unit | Standard |
|---|---|---|---|---|
| Equivalent weight | approx. 230 | |||
| Density | approx. 1,16 | g/ml | DIN 51757 | |
| Flash point | 226 | °C | DIN EN 22719 |
Solubility / thinnability
Generally speaking, Bayhydur® ultra 304 has good compatibility with the solvents listed: esters, ether esters, xylene and solvent naphtha® 100. However, the solubility/compatibility should be tested in each individual case.Only PU grade solvents (< 0.05 % water) should be used.
Storage
- Storage in original sealed Covestro container. - Recommended storage temperature: 0 - 30 °C. - Protect from moisture, heat and foreign material. General information: Hydrophilic isocyanates are very moisture-sensitive and react with water to form carbon dioxide and insoluble ureas. The containers must always be kept tightly closed. The access of water in all forms (moist air, solvents, moist containers) must be prevented, because the generation of carbon dioxide can lead to dangerous increases in pressure. Storage at higher temperatures will result in increase of color and viscosity. Due to the raw materials, the product may show visible turbidity caused by the cold. This turbidity occurs at approx. + 5 °C and is reversible when heated to room temperature. The product properties are not affected.
Storage time
Covestro represents that, for a period of nine months following the day of shipment as stated in the respective transport documents, the product will meet the specifications or values set forth in section "specifications or characteristic data" above, what ever is applicable, provided that the product is stored in full compliance with the storage conditions set forth in and referenced under section "storage" above and is otherwise handled appropriately.The lapse of the nine months period does not necessarily mean that the product no longer meets specifications or the set values. However, prior to using said product, Covestro recommends to test such a product if it still meets the specifications or the set values. Covestro does not make any representation regarding the product after the lapse of the nine months period and Covestro shall not be responsible or liable in any way for the product failing to meet specifications or the set values after the lapse of the nine months period.
