To ensure the quality and performance of coatings, there are still many factors that need attention in the production process under the premise of equipment, formula and raw material quality assurance.
Storage and transportation of raw materials
Raw materials are the prerequisite for quality assurance. In addition to the preferred suppliers, to ensure the quality of raw materials, storage and transportation of raw materials are important, especially chemical raw materials such as polyether, TDI and solvents. In order to ensure the stability of the viscosity of the raw materials in various environments Polyether is stored in storage tanks. Each storage tank is equipped with energy-saving heaters, and the transmission pipeline is heat-conducting oil. The low-temperature storage of TDI raw materials will reduce its effect. Therefore, a constant temperature drying room and a separate feeding question are set up. Given that TDI is a toxic raw material, we have established a strict acceptance system.
Accurate metering throughout the entire feeding process
The raw materials for the coating production are divided into powder and liquid materials. Liquid material transmission is automatically controlled by PLC control. Different flowmeters are selected according to viscosity. Volumetric flowmeters with large viscosity and vortex flow with small viscosity are used. As the reaction kettle is equipped with a weighing and weighing system, the conveying pipelines are connected by high temperature resistant metal hoses. For hoses with a diameter greater than 40 mm, a horizontal connection is adopted at the connection part with the reactor to avoid weighing errors.
Reactor temperature and pressure control
In the production process of polyurethane waterproof coatings, the temperature and pressure process indicators are strict at all stages. We have set up on-site pressure gauges for the problem of low reliability of remote pressure gauges, even for highly reliable instruments such as thermal resistance. An on-site temperature measurement device is also set up to ensure that the process indicators of the production process are completely controlled, and ultimately ensure production safety and product quality.
Dehydration and stirring
Dehydration is the key process in the production of polyurethane waterproof coatings, especially after the single component is added to the liquid and powder, before the TID is added for the reaction, vacuum heating, air extraction and dehydration must be performed. The temperature of the reactor should be controlled during the dehydration process. Above 100 ° C until the moisture drops to the level required by the process. Stirring is also a key factor in the preparation of coatings. By stirring, the components (liquid-liquid, solid-liquid) are evenly mixed to make the reaction fully. When the powder is added, the TID is added quickly and fully. Because friction generates heat during the stirring process, heat dissipation measures must be taken to stabilize the material at the process requirements.
For the preparation of one-component coatings, the nitrogen filling system is very important in the entire production process. It provides protection to the reaction kettle. When discharging, nitrogen is charged from above the reaction kettle to separate the polyurethane product from the moisture in the air. Protect polyurethane.
Strict process management
The production of polyurethane waterproof coatings is different from the production of traditional waterproof coatings (such as modified asphalt coils). It is a chemical production in a complete sense. The requirements for personnel quality, strict management regulations, and rigorous accuracy in operation control are not comparable to the production of general waterproofing materials. Operation and safety accidents are not alarmist and should be paid enough attention. To this end, strict process management methods and safety systems have ensured safe and smooth production since the production line was put into operation.
The market needs high-quality polyurethane waterproof coatings, which rely on high-level production equipment, staff quality and factory management. The production of high-quality polyurethane waterproof coatings is a test and improvement for relatively weak waterproof companies in all aspects. In order to ensure the quality of polyurethane waterproof coating products, it is necessary to formulate corresponding regulations and regulate its production equipment.