Polyurethane

There are some concrete release agents that are low or zero VOC. This needs to be investigated when discussing the characteristics and attributes of different release agents with potential suppliers.

This is an area of growing concern and interest and there are products available that have low and zero VOC materials.

Chem-Trends High Performance Release Agents are usually VOC free or VOC reduced. Before using these products, the legal requirements on site and the application parameters must be determined (e.g. 5 tonnes VOC or TA-Luft 50mg/m³).

Depending on the production set up a wide variety of configurations can be utilized. From manual HVLP guns to automated spray systems, assistance with determining the best selection to efficiently apply concrete release agents should be provided by the release agent supplier.

Watch our video tutorials for more information.

Materials may be diluted through very reliable wall mounted or floor model proportioners. These units provide a consistent water to concentrate ration that allows for a dependable mix without the use of valuable manpower.

By using a piece of cardboard a spray pattern may be tested. First make sure the spray equipment nozzle and air cap are clean and unrestricted. Hold the spray gun a distance from the cardboard that is a normal distance from the spray gun to the moulding surface. Spray the mould release onto the cardboard in a sideways sweeping motion. The pattern should be solid yet dry quickly. Any splotches will show areas that may be under sprayed or unevenly applied. Liquid running down the surface means the liquid is being applied too heavily.

Please see our tutorial application video how to correctly apply a mould release agent in polyurethane moulding applications.

When applying a release agent with manual spray it is important to establish a baseline throughput to maintain a consistent spray. Required throughput amounts will vary based on the tooling grain, part complexity, and the speed of the line. When a proper spray amount is determined the throughput in grams or milliliters per second should be recorded. This should be checked each shift to make sure there is consistency between operators. This information will help to train new operators to correctly apply the release agent. Consistent fluid and atomizing air pressures are also a must for repeatable application.

The key is to have a dry mould surface before the foam is poured. A liquid carrier is used to deliver the release agent to all surfaces of the tooling. This carrier should be evaporated before the foam is poured or injected into the tool.

Key selection factors are:

• Type of foam being produced (rigid, seating, RIM, etc.)
• Moulding temperature range
• Mould material (aluminum, steel, etc.)
• Time between mould release application and foam pour
• Cure time
• Foam density
• Post moulding requirements (bonding, painting, etc.)

The more information on the process the easier it is to determine the perfect release agent.

Obviously enabling the easy removal of cured parts from different moulded materials is an important reason for using a release agent. What many do not consider is that these same materials can greatly increase mould life by maintaining a lubricious film on the mould surface that will prevent the cured concrete from deteriorating the interface. These products can also aid in the wetting out of pigments and improve colour transfer from the mould substrate to the stone. This can help to minimize scrap caused by colour changes. All of these benefits result in a more efficient operation.

Hybrid products provide the benefits of a solvent based material, such as an open surface and faster film formation and evaporation, but they utilize a waterborne carrier with a small amount of solvent to provide these benefits. This technology significantly minimizes VOC emissions.

Various release agents can be used with many forms of spray equipment. While HVLP systems are the most common method of application, many other methods can be used based on equipment and plant configurations.

Please see our tutorial application video about that topic.

Release agents for veneer/masonry stone applications and other specific concrete applications should be designed to allow pigments to wet out on the surface and to keep moulds clean through improved colour transfer. Maintaining a proper application amount and/or dilution is important in achieving these goals and the effectiveness of the release agent should be fully evaluated in a field trial prior to full scale adoption.

By using a piece of cardboard a spray pattern may be tested. First make sure the spray equipment nozzle and air cap are clean and unrestricted. Hold the spray gun a distance from the cardboard that is a normal distance from the spray gun to the moulding surface. Spray the mould release onto the cardboard in a sideways sweeping motion. The pattern should be solid yet dry quickly. Any splotches will show areas that may be undersprayed or unevenly applied. Liquid running down the surface means the liquid is being applied too heavily.

Watch our polyurethane application tutorial video about how to test the spray equipment.

When applying a release agent with manual spray it is important to establish a baseline throughput to maintain a consistent spray. Required throughput amounts will vary based on the tooling grain, part complexity, and the speed of the line. When a proper spray amount is determined the throughput in grams or milliliters per second should be recorded. This should be checked each shift to make sure there is consistency between operators. This information will help to train new operators to correctly apply the release agent. Consistent fluid and atomizing air pressures are also a must for repeatable application.

For manual application, it is important to determine the appropriate parameters via nozzle size, release agent quantity and atomising air. In order to obtain a clean spray pattern according to the specifications of the moulded part, the release agent quantity must first be determined via nozzle and material pressure. Then the atomising air must be adjusted so that the mould can be wetted evenly and quickly.

Paste waxes provide an excellent barrier for starting up on clean moulds. These materials provide protection in scratched, cold, or high pressure areas, and provide a durable layer that will help to minimize complications due to defects on the metal surface. Mould sealers improve the performance of the release agent by creating an optimal surface to release the parts from. Sealers are applied only to freshly cleaned tools but the benefit lasts throughout the production and cleaning cycle.

Please watch our polyurethane tutorial video about how to clean and seal a mould.