Eco-Friendly (Next-Generation) Polyurethane Systems with High Sound Absorption Capacity and Curing Speed

Zeolites are hydrated aluminium silicates found in nature or produced synthetically. Their natural and synthetic forms are used as desiccants in various industries. Depending on the industry in which they are used, they have a quality and efficiency-enhancing effect on the final product.

What Do We Do?

Brenntag, one of the sector's leading chemical distribution companies, meets manufacturers' demands with its deep product range and extensive service network across all sectors. Based in Germany and operating in more than 70 countries across 450 different locations, it acts as a bridge between end-users and chemical manufacturers, offering solution proposals with specialized and commercial products to meet the sector's needs. As Brenntag Kimya, we are the European distributor of Zeochem, supplying Purmol products in the moisture-absorbing zeolite groups to the market. General information about Purmol and its main types are as follows:

2. Purmol and Its Types

Purmol adsorbents are synthetic powdered zeolites with a complex alkali aluminosilicate structure. They consist of regular and uniformly sized structures. Based on this polarity and molecular size, they selectively adsorb molecules. Purmol is a desiccant used in polyurethane coatings, adhesive and sealant applications. Purmol excludes large organic molecules while adsorbing small-diameter molecules. During application, while Purmol adsorbs water molecules, it prevents the absorption of solvents and resins and similar materials. We recommend adding Purmol to the polyol component at a rate of 2.5-5%. Purmol powder should be mixed for a minimum of 2 hours before isocyanate addition to adsorb all water.

2.1. Purmol 3ST

Purmol 3ST is a potassium (K) type zeolite with a pore size of 3Å, a primary crystal size of 4.6 μm and a particle size of 24 μm. It is particularly recommended for use with high-quality coatings.

2.2. Purmol 4ST

Purmol 4ST is a sodium (Na) type zeolite with a pore size of 4Å, a primary crystal size of 4.6 μm and a particle size of 24 μm. It is particularly recommended for use with high-quality coatings. Purmol 4ST combines high adsorption capacity for water and is characterized by a lower pH value.

3. Application Areas

Purmol has a wide variety of applications. While many current applications focus on polyurethane and plastics, Purmol can be used in many formulations where selective adsorption of small polar molecules in a liquid or solid medium is required. Purmol's fine particle size ensures good mixing and excellent dispersion in any formulation. In each of the example applications listed below, Purmol is a vital component if the highest quality formulation is required. • One and two-component polyurethane coatings, • One and two-component polyurethane adhesives, • PUR / Epoxy-electrical insulation resins for applications, • Metallic pigment coatings (zinc-rich primers, aluminium paints), • Polysulfide and silicone systems.

3.1. Moisture Removal in Polyurethane Systems

The biggest problem encountered in polyurethane adhesives is the amount of moisture in their content. If moisture in the system is not removed, it will react with the isocyanate. The reaction mechanism releasing CO2 is as follows: RNCO + H2O → RNH2 + CO2 Activated zeolite powder / molecular sieve powder is an extremely effective and non-toxic desiccant for 1K and 2K polyurethane systems, preventing foam and bubble formation by suppressing the reaction of free water with the isocyanate group. At the same time, activated zeolite powder / molecular sieve powder is also compatible with commonly used polyols, polyethers and isocyanates. It is easily dispersible and has a regulatory effect on curing times. We recommend adding Purmol to the polyol component at a rate of 2.5-5%. Purmol powder should be mixed for a minimum of 2 hours before isocyanate addition to adsorb all water.

3.2. High-Quality Pipe Coating

Purmol products are the best solution to protect the quality of the polymer against chemical wear.

3.3 Cast Compounds for High-Voltage Electrical Insulation

In high-voltage insulation products, the homogeneous nature of the insulation body is extremely important. Defects in cast compounds can cause short circuits. Purmol is used to ensure high quality in this application.

3.4. Moulding Compounds:

Moulding compounds, such as the soles of sports shoes, must be clean, flawless and soft. It is important that products are produced robustly under pressure. Purmol should be used for moulding compounds.

3.5. Floor Coating:

Floor coatings must be resistant to wear, have a flat, soft surface and high stability. Polyurethane coatings are often used in such areas. The polymer is applied like a liquid layer and then forms a flat and resistant floor coating. Purmol prevents water droplets and gas bubbles and roughness resulting from water presence in floor coating systems.

3.6. Thermal Glass Sealant:

Recently, polymer foam has been used as an intermediate layer in glass insulation systems to conduct aluminium heat. At the same time, Purmol adsorbs moisture entering between the plates during the preparation of the insulation system. A glass pane shows its effect over ten years at low external temperatures without drying and without condensation inside.

4. Properties of Synthetic Zeolite

4.1. Selectivity: Gas molecules can be separated by molecular size or polarity difference. For example: a sieve with an average pore size of 3 Angstroms can only adsorb H2O or HF. 4.2. High Performance: Even at very low moisture or gas concentration, at high or low temperature, it can bring moisture or gas to ppm levels; 4.3. Stability: It is inorganic. Therefore, it does not react with most other organic chemicals and cause unwanted by-products. When used in polyurethane systems, zeolite absorbs moisture, suppresses the above reactions and ultimately prevents gas, gelation, irregular viscosity and sticky, paste, coating, plastic and rubber system problems.

5. General Safety Notice

Purmol products, the zeolite product group, are not toxic, carcinogenic, mutagenic or teratogenic. They do not contain harmful substances or traces of harmful substances. Products are not flammable or explosive. Synthetic zeolites are not listed as a hazardous substance in Regulation 1272/2008 and its amendments. Zeynep Köknaroğlu Arslan - Paints & Construction Group Product Manager - Brenntag Kimya Emre Günay - Paints & Construction Group Sales Manager - Brenntag Kimya