New polyurethane waterproof coating production line and its process

Since the 1980s, polyurethane waterproof coatings have grown rapidly due to their superior performance, especially after rapid application in the 1990s, and their use has increased, as has the proportion of waterproof coatings.
years, Weifang City Hongyuan Waterproof Materials Co., Ltd. business continues to expand, the previous polyurethane waterproof coating production line has been unable to meet the requirements. In order to reduce the labor intensity of workers and improve product quality, the company decided to build a high degree of automation, safety and environmental protection of polyurethane waterproof coating production line
China
. After combining the advanced design concepts provided by experts from the China Academy of Architectural Sciences and the experience of the original polyurethane waterproof coating production line, after 5 months of design, installation and commissioning from October 2013 to March 2014, the company completed and put into operation a production line with an annual output of 30,000 t polyurethane waterproof coatings. The design concept and production level of the production line are in the domestic advanced level, since the start of production, the company's polyurethane waterproof coating product performance and quality stability have been greatly improved. This paper gives a brief introduction to the design concept of the production line and the improvement of key processes.1 Design Concept
1.1 Production line design requirements
1.1.1 production capacity design requirements
single-component polyurethane waterproof coating annual production capacity of 20,000t, two-component polyurethane / polyurethane waterproof coating annual production capacity of 10,000t, to meet the company's growing production demand.
1.1.2 Quality design requirements
to ensure the production stability of polyurethane / polyurethane waterproof coating, product performance is excellent, in line with GB / T 19250-2013 "polyurethane waterproof coating" and GB / T 23446 - 2009 "spray polyurethane waterproof coating" requirements, to provide customers with high-quality polyurethane / polyurethane waterproof coating.
1.1.3 Production line operation design requirements
equipment to achieve electrical control automation, easy operation, accurate measurement, intermediate process control, effectively reduce manual operation, reduce the labor intensity of workers.
1.1.4 Production line environmental design requirements
by vacuum dehydration of the gas treatment, reduce the content of toxic substances in the gas, reduce environmental pollution;
1.2 Production function division
1.2.1 Raw material storage area
synthesis of pre-polymers is the basic reaction of polyurethane waterproof coatings, compounds containing active hydrogen (polyether polyols or polyester polyols) and binary or polyorganic isocyanates containing isocyanate (-NCO) are the main raw materials of polyurethane waterproof coatings. Polyether polyol polyurethane because of its performance advantages, is currently the mainstream polyurethane coating products, the company produces a single-group polyurethane waterproof coating and two-group polyurethane waterproof coating are selected shandong Blue Star Dongda Chemical Co., Ltd. production of polyether DL-2000D and EP-330N. The Company in the raw material arrangement, liquid raw material tank area of 4 150 m3 stainless steel tanks stored polyether DL-2000D, EP-330N and two other major liquid fillers chlorinated paraffin and aromatic oil, while the remaining 2 storage tanks to cope with the formulation adjustment. The raw materials in each of the 4 tanks can be precisely fed to each dosing tank by a central metering pump. Powder is a secondary film material of coatings and an indispensable raw material for the preparation of polyurethane waterproof coatings. The water in the production process of polyurethane mainly comes from powder, powder moisture content is too high, will affect the storage stability of the product, so that the product gradually thickened, so that due to high viscosity can not be used. As a result, the company has set up a powder warehouse of 1,100 m2 on the second floor of the new paint shop to prevent moisture from absorbing from the ground when the powder is stored, especially in summer. At the same time, steam reflow pipe is laid to dry the powder by using steam heat effectively.
1.2.2 Temperature control equipment area (heating, cooling
the new polyurethane waterproof coating production line using boiler steam heating, equipment selection, for environmental protection and energy-saving considerations, the selection of a new type of coal-fired steam boiler. Boilers are designed with a combustion engine to meet the soot emission requirements of coal-fired boilers and can be used in a class of environmentally friendly areas without noise disturbance. Compared with fuel and electric heating steam boilers, coal-fired steam generators can reduce energy consumption by 30%, and the heated area of steam generators can reach 92%, plus the supporting coal savers, so that the heat generated can be fully absorbed by the boiler, greatly saving the operating costs of the boiler.
reactor on the old production line is cooled by cold-conductive oil and is inefficient, especially in summer, when the reactor is cooled from 115 to 80 degrees C, it takes about 150 min. The new polyurethane production line is equipped with jackets, cold water cooling, the reactor from 115 degrees C to 80 degrees C only 70 min, greatly reducing cooling time and improving production efficiency.
1.2.3 vacuum equipment
moisture content is the most needed control indicator in the production of polyurethane waterproof coatings. Since the relative molecular mass of water is only 18, contains 2 hydroxyl, the same mass of water and polyether DL-2000D can consume - the number of NCO difference of more than 100 times, so in the synthesis of polyurethane pre-polymer, to avoid the participation of moisture, to prevent excess water consumption - NCO, resulting in polyurethane coating thickening and sticky. This is the main reason why polyurethane raw materials need to be dehydrated.
vacuum equipment needs stable work reliability to ensure the dewatering effect of raw materials. The new polyurethane production line uses two water ring vacuum pumps, which inhale evenly, work smoothly and reliably and are easy to repair, and are compact in structure and have a higher number of turns of the pump, which can be directly linked to the general motor without deceleration device, with a small structural size to obtain a large exhaust volume. Polyurethane raw materials can be pumped out in a vacuum, so each polyurethane reaction tank is fitted with a buffer tank to check that the material is pumped out and also serve as a storage function.
1.2.4 Hydraulic Equipment Area
The new production line is designed to have an advanced level of polyurethane production line in China, so most control points are electrical control instead of manual operation. Some important operating points, such as discharge valves, retain both manual operation and pneumatic valve control to prevent the pneumatic valve from operating effectively in the event of failure.
the operation of the pneumatic valve needs to be driven by compressed air, and the new polyurethane production line is basically delivered using diaphragm pumps, the working stability of the air compressor is critical. We selected a twin screw air compressor with excellent power balance, which drives the compressor directly by the motor, causing the crankshaft to produce rotational motion and driving the connecting rod to cause the piston to produce revere motion, causing the cylinder volume to change. Due to changes in pressure in the cylinder, air passes through the air filter (mist) into the cylinder through the air valve, and during the compression stroke, compressed air passes through the exhaust valve through the exhaust pipe and check valve (check valve) due to the reduced cylinder volume. Enter the air reservoir, which is automatically shut down by the pressure switch when the exhaust pressure reaches the rated pressure of 0.7 MPa, and the pressure switch is automatically connected when the air tank pressure drops to 0.5 to 0.6 MPa. Figure 1 shows a central operating diagram of a reactor in polyurethane.
1.2.5 Production equipment area
new polyurethane coating production line has a total of 19 enamel reactors, of which 6 6 m3 reactors (1 - 6) produce single-component polyurethane waterproof coatings , 4 3 m3 reactors (9 to 12) serve as a single-group polyurethane dosing tank, and 7 s, 8 s kettles (5 m3) as a single-group polyurethane grinding tank. 17, 18, 19, reactor (3 m3) produces two-group polyurethane A, two 5 m3 reactors (15, 16) produce two-part polyurethane B, 13-reactor as a two-part polyurethane B ingredient tank, 14 s reactor as a two-part polyurethane B abrasive tank. Each enamel reactor is equipped with 4 pressure weighing modules, the quality signal of the kettle body can be transmitted to the central controller, after calculation, the quality of the kettle body is displayed on the reactor data box and the central LED screen. Figure 2 shows the central control system diagram of the new polyurethane coating workshop.
National polyurethane coating workshop control system diagram
the new polyurethane coating production line is equipped with 3 vertical sander, the mixed slurry through the diaphragm pump into the sander, and then the solid material in the slurry is ground and refined and flowed out of the sieve hole. The grinder barrel body is partially equipped with a cooling device to prevent heat from frictioning with polyurethane slurry, grinding media and discs in the barrel from affecting product quality.
1.2.6 Finished storage area
Polyurethane waterproof coating is a chemical product, not stored in the production workshop, to avoid accidents. The new polyurethane waterproof coating workshop is equipped with a 3,000 m2 finished product storage room, divided by product type, placed signs. Product uniform code on the tray, and with forklift access, easy access.2 Improvement of key processes
2.1 segmented production
old polyurethane waterproof coating production line, ingredients, dehydration, reaction processes are carried out in a reactor, must wait for the completion of the last process, in order to carry out the next process, low production efficiency. The new production line divides the production process of polyurethane waterproof coating into three stages: ingredients, grinding and reaction, so that the three stages do not affect each other, can be carried out at the same time, and effectively utilize the working time. For example, polyurethane raw material dehydration time is very long, generally around 3 to 4 h, before this time can not be used, and now workers can carry out the next shift of ingredients and grinding during this time, to achieve continuous production. Figure 3 shows the production process of single-group polyurethane waterproof coatings, and Figure 4 shows the production process of two-group polyurethane waterproof coatings.
2.2 detail process has been
the new polyurethane waterproof coating production line has been improved in many details.
Polyurethane raw materials in the ingredients tank after the preparation, the formation of a very high viscosity of the slurry, if the use of ordinary centrifugal pump, then the feeding speed is slow, because the centrifugal pump work point is set against water as a benchmark, if the material viscosity is slightly higher, it is necessary to support the reducer or inverter regulator, so the cost is greatly increased, for the gear pump is also the same. Therefore, the new polyurethane coating production line uses a diaphragm pump suitable for medium and high viscosity materials, because the diaphragm pump is powered by air, the flow rate can be automatically adjusted with the change of back pressure (export resistance).
For the polyurethane pre-slurry viscosity is large, not conducive to the characteristics of transport, the new polyurethane coating production line also installed heat exchangers, by increasing the temperature of the slurry to reduce the viscosity, to ensure that the slurry will not be due to heat dissipation in the pipe and make the viscosity too high.
the new polyurethane coating production line of single-component polyurethane reaction tank (1 - 6) and two-component polyurethane A reaction tank (17 - 19) are equipped with drip tank, through the mass flow meter, constant speed drop plus TDI-80, control the reaction speed. Experiments have shown that controlling the drop acceleration of TDI-80 can increase the stretch strength of the product by 10%. 3 Conclusion
The new polyurethane (including polyurethane) waterproof coating production line relies on advanced design concepts and process equipment, which not only achieves automated production, but also saves labor costs, reducing the team from 10 to 5 people. Its production and operation shows that the offline polyurethane waterproof coating quality is stable, excellent performance, in the domestic advanced level, for Hongyuan waterproof materials Co., Ltd. to improve the market share of waterproof paint provides a reliable guarantee.