Improvements in the production process of a coating product

0 Introduction
coatings consist of film forms, pigments/fillers, solvents and additives. In the production process of coatings, through effective processing, solid powdered pigments/fillers are evenly distributed in the paint to form a stable dispersion system. The properties and dosing of various ingredients in coating formulations determine the performance and use of coatings,
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. The process and equipment used in the production of coatings, especially the dispersion of pigments in color paints and the use of the best pigment performance, also play an important role in the quality of coating products. Therefore, as with carefully designed coating formulations, choosing the right production process can improve productivity and product passability. The production process includes dispersion mode, selection of equipment, process control and so on. In the production process control, the order of feeding is a process worth studying, appropriately change the casting order of various components in the coating formula, you can get different effects, which is intuitively reflected in the viscosity of the finished coating products, fluidity.
1 Experimental part
1.1 experimental background
the choice of Xiamen Shuangrui Ship Coatings Co., Ltd. developed heavy anti-corrosion coatings (mainly used in pipe corrosion, paint material heating up can be sprayed work, detection indicators for viscosity of 40 degrees C 5,000 to 8,000 cP, flow hanging ≥675 sm) based formula for product production. Before the improvement of the production process, the trial production was carried out according to the operating instructions provided by the research and development department, and the process was shown in Figure 1.
production process
the resulting viscosity of the finished product (the viscosity value when the paint is measured at 40 degrees C) is below 3,500 cP, the flowability is about 475 m, can not meet the formulation design requirements. For non-conforming products, often using sit overnight, add fillers and other ways to increase viscosity and enhance the adhesion. However, product performance is still difficult to meet the standards, production efficiency is very low.
1.2 Raw materials and equipment
mica powder, glass microbeads, heavy crystal powder, T-31 phenolic amine epoxy resin curing agent, resin, additives. All raw materials are for industrial use. Production kettle (0.5 t, s89.2 cm, H 85.6 cm), explosion-proof high-speed dispersion machine (0 to 1 500 r/min, 22 kW, Jiangyin City Double Leaf Machinery Co., Ltd.), rotary viscosity meter (RVDV-II.?Pro, BROOKFIELD), QAG hangability tester (Tianjin Yonglida Material Tester Co., Ltd.).
1.3 Experimental Scheme
The production process of heavy corrosion-resistant coatings is improved by changing the order in which raw materials are cast and added without changing the formulation. By measuring the viscosity and adhesion of the finished product, to determine whether it meets the requirements of the factory testing index of the product, to determine the best production process of the product, so that the product performance meets the construction requirements, to ensure the long-term stability of product quality. The experiment was carried out 3 times, each feeding process and dispersion process as follows.
scheme one: according to the original process into the kettle resin liquid, additives, low-speed mixing mixing, in turn, add mica powder, glass microbeads, heavy crystalline powder, high-speed dispersion, determination of semi-finished viscosity (as a reference), and finally add T-31 phenolic amine epoxy resin curing agent, high-speed dispersion, to obtain paint;
Option II: put resin liquid, additives, T-31 phenolic amine epoxy resin curing agent into the kettle, low-speed mixing and mixing, in turn, add mica powder, glass microbeads, heavy crystal powder, high-speed dispersion, to obtain paint;
program three: into the kettle into the resin liquid, additives, T-31 phenolic amine epoxy resin curing agent, low-speed mixing, in turn, add heavy crystal powder, glass microbeads, mica powder, high-speed dispersion, to obtain paint.
2 Experimental Results and Discussion
2.1 Experimental Results
According to the viscosity and adhesion of the finished coating products obtained from the three experiments, we can see that the production effect of Scenario III is the best. According to the feeding order and dispersion mode of scenario three, the production of two kettles of heavy anti-corrosion coatings was carried out, and the products obtained better performance, and the viscosity value and flowability were better reproducible (see Table 1).
different programs produced product viscosity, flow-on test results
for the first kettle products, before adding T-31, the semi-finished viscosity of 9 180 cP, the addition of T-31 dispersion uniform after the finished product viscosity reduced to 3,320 cP, after overnight measurement of viscosity of 3,400 cP, the viscosity change is not significant. By adding 2% of the total quality of the paint to the filler, the viscosity rose to 4,600 cP, and then to 2% of the total quality of the paint filler, the viscosity rose to 5,620 cP, detecting the flowability ≥675 m.
of the experiment, according to the plan three revised the heavy anti-corrosion coating production work instructions, the production of the product to standardize. Table 2 is the value of the viscosity determination of the finished product of the heavy anti-corrosion coating in 2 batches (one batch containing 6 kettles) after the process improvement.
two batches of 12 kettle heavy anti-corrosion coating finished viscosity value
From Table 2, it can be seen that the finished product viscosity is in line with product indicators, small fluctuations, stable production.
2.2 Powder suction size in the production process of the application
oil absorption refers to the liquid grease (also contains resin or solvent) slowly dried into a certain amount of powder, dry powder surface absorption grease, particles themselves are moisturized, when the powder is completely moisturized by grease required the lowest value, that is, powder is easily wet by liquid. The oil absorption of mica powder, glass microbeads and heavy crystal powder was measured at 34.2 mL/100 g, 23.12 mL/100 g, and 15.03 mL/100 g.
first, according to the process improvement before the order of feeding products. Option 2 first add liquid raw material T-31 phenolic amine epoxy resin curing agent, resin liquid, additives, and then add a large amount of oil absorption of mica powder and glass microbeads, and then add a small amount of heavy crystal powder. Scenario 3 After adding liquid raw materials, the heavy crystal powder and glass microbeads with a small amount of oil absorption are added, and then the large amount of oil-absorbing mica powder is added. Experimental results show that the addition of T-31 phenolic amine epoxy resin curing agent is the main reason for the performance of the finished product is not up to standard, it may be that the amount of oil absorption of powder has not reached saturation. At the same time, according to the size of the amount of oil absorbed by the powder to change the order of the powder cast and add, to obtain different effects.
2.3 Comparison of production efficiency before and after process improvement
Before the improvement of the production process of heavy anti-corrosion coatings, the production efficiency is very low, the performance of the finished product is unstable, the time spent to deal with non-conforming products is more, the equipment takes a long time, and the loss of raw materials is large. Excluding equipment occupancy and additional raw filler losses, the productivity is approximately 840 kg/person d. With the improvement of the production process, the production efficiency is 2,240 kg/person d, the production efficiency is increased by more than 1.7 times, and the equipment takes up a short time, the additional loss is small, the product performance is stable.
3 Conclusion
(1) By improving the production process of heavy anti-corrosion coatings, the viscosity of the finished product reaches more than 5,000 cP, and the flow-hanging is greater than 675 m, which conforms to the factory detection index of the product;
(2) Improved production efficiency is more than 1.7 times higher than the original, and the equipment occupies a short time, the additional loss is small, the product performance is stable
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