Industrial process of making phenolic resin adhesive for phenolic plywood.

First add the melted phenol to the reaction kettle and start the agitator. Add sodium hydroxide solution and the actual water consumption, heat to 42℃~45℃, let it hold for 25 minutes.

Tip: Phenol is colorless acicular crystal or white crystalline frit at room temperature. Skin contact with phenol aqueous solution or pure phenol will cause anesthesia poisoning.

And become ulcers, has a strong corrosive, use should pay special attention to.

Note: Reaction kettle is the main equipment for glue production. The volume of the common reaction kettle is 0.5-5m3, and most of it is lined with acid-resistant enamel material. As the enamel surface is prone to crack porcelain, it is strictly prohibited to use metal tools and other hard objects to hit the porcelain surface, which brings inconvenience to installation, use and maintenance. At present, there is a stainless steel reactor, the capacity can be up to 10m3, built-in cooling and heating coil, heat exchange effect is much better than the sandwich, higher production efficiency, but the cost is also high. For large rubber producers, this kind of reaction kettle can be considered, which is convenient for manufacturing and maintenance, but requires a higher level in operation. Because the reaction is not easy to control, relevant cooling facilities should keep up.

Then add the first batch of formaldehyde, let the temperature control at 45℃~50℃, this state for 30 minutes.

Tips: 1. Formaldehyde solution generally contains 37% formaldehyde and 12% methanol polymerization inhibitor. Due to the existence of formic acid, it has certain corrosion. Formaldehyde solution is easy to polymerize into paraformaldehyde at low temperature, resulting in difficulties in use, so formaldehyde storage tank should have insulation facilities, but the tank temperature should not be too high, high temperature, The content of formic acid in formaldehyde solution will increase. Because formic acid is corrosive, it is easy to cause local corrosion and perforation of storage tank. Both will cause inconvenience and uneconomy in use. The adhesive storage tank is mostly made of stainless steel. In winter and northern areas, the temperature requirements of adhesive storage should be considered, and the external insulation layer should be generally applied.

The temperature rises from 50 ° C to 87 ° C (0.5 ° C/min) in 74 minutes and from 87 ° C to 95 ° C (0.3 ° C/min) in 24 minutes. The temperature stays between 95 ° C and 96 ° C for 18-20 minutes. It is suggested that the quality of adhesive is not only related to the quality of raw materials, but also the reaction temperature. In the past, most of the glue production relied on the on-site thermometer to show the temperature, but its deficiency was that the production control lagged behind, affecting the quality of control. The current level of technology can be the temperature and pneumatic valve linkage, and the temperature data transmission to the computer, can set up automatic operating system, remote control and display of the temperature, greatly improve the degree of automation of the operating system. And using the data and curves collected by the computer monitoring system, the production process can be counted, analyzed and compared to determine the better production status and parameters. Similarly, the weight of each ratio of raw materials can also be controlled by electronic Settings to reduce human errors.

After heat preservation, it was cooled to 82℃ within 24 minutes, and a second batch of formaldehyde was added to keep it at 82℃ for 13 minutes. Note: most of the previous rubber production relied on on-site thermometers to show the temperature, which caused the production control lag, affecting the quality of control. The current level of technology can be temperature and pneumatic valve linkage, and the temperature data transmission to the computer, can be set up automatic operation system, temperature remote control and display, greatly improve the degree of automation of the operating system. Tip: Waste water treatment is a big problem for rubber production enterprises. Due to the content of volatile phenol and formaldehyde exceed the standard, under the current conditions of environmental protection and clean production, enterprises have to spend a lot of money to treat wastewater, and often due to the immature technology treatment, but also can not get ideal results. The fundamental solution is to adopt the method of blocking the source of interception and recycling. Glue manufacturers can set up a laboratory table at the side of the reaction kettle, and connect it with the reaction kettle through a flexible tube.

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The sample glue is directly returned to the pot, and the wastewater from cleaning the laboratory instrument is recycled to the reaction kettle as production process water, which fundamentally limits the amount of water used by operators and reduces pollution. In the process of producing dehydrated rubber, how to deal with distillated water and wastewater rich in formaldehyde and other harmful ingredients has become an urgent problem to be solved.After 13 min, the second heating is started, rising from 82℃ to 92℃ (0.3℃/ min) within 30 min, and the reaction is continued at 92℃~96℃ for 20 ~60 min (depending on the viscosity). After the viscosity meets the requirements, the central sleeve shall be cooled by water to 40℃ to lower the material. Note: the production of glue is carried out at a certain temperature, and the storage of glue liquid also has certain requirements on temperature. Therefore, the cooling facilities of glue production have a certain influence on the quality of adhesive control, especially in summer, because of high temperature and high water temperature of circulating cooling, the glue liquid cooling is slow and the production efficiency is low. Therefore, the cooling water can be directly discharged according to the water source, or the cooling plate can be set in the reaction kettle Pipe, strengthen the cooling effect, according to the need, sometimes with frozen water cooling, so, but also add refrigeration unit system, which will increase enterprise investment.

Measurement of viscosity: generally, the foaming method is used to control the viscosity of the reaction liquid, that is, a 100mm long tube with an inner diameter of GMM, and the number of foaming flow seconds is controlled within 6-8 seconds (20 ℃).

In China, adhesive production using intermittent reactor, intermittent production because is a single kettle production; High flexibility, suitable for the production of many varieties of adhesive, but low production efficiency. If we can solve the technical problems related to the continuous measurement of pH value and viscosity value in industrial production, then the continuous production of adhesive can be completely realized, and the degree of automation of production technology can be greatly improved. The development trend of adhesive production is to use automatic control technology to carry on continuous clean production under the condition of existing production equipment.

Review and Prospect of The Brilliant Twenty Years of Chinese adhesive Industry:

China adhesives industry in L987 in September formally established China adhesives industry association, this 20 years adhesives production scale continues to expand, product output, sales growth, China has been the world’s adhesives and sealants production and consumption.

Phenolic resin (PF) is one of the earliest synthetic polymers and used in adhesive industry. It is formed by condensation of phenol (cresol, xylenol or resorcinol) with formaldehyde in the presence of acidic or alkaline catalysts.

Phenolic resin adhesive has excellent heat resistance, chemical resistance, aging resistance, water resistance and electrical resistance insulation, high bonding strength, can withstand high temperature, at 300℃ still has a high bonding strength. But the biggestThe disadvantage is that the brittle adhesive layer and low peel strength. Nitrile butadiene rubber, polyvinyl acetal and nylon were used for modification. In industry due to the raw material and catalyst the same, its many brands, can be divided into: thermosetting phenolic resin, thermoplastic phenolic resin and water-soluble phenolic resin.

Adhesives are widely used in wood processing, construction, light industry, medicine, electronics, instrumentation, machinery manufacturing and other departments. With the development of modern industry, the performance of adhesives has been put forward higher requirements. At present the market for sale of polyvinyl acetate vinegar emulsion adhesive kimonaldehyde resin adhesive agent,the disadvantages of these adhesives are: water resistance, heat resistance and moisture resistance. The phenolic resin adhesive introduced in this topic has good water resistance and aging resistance.

Suitable for indoor and outdoor long-term use. Here are the simple steps to make:

1. Add the melted phenol to the reaction kettle and stir.

2. Add the first batch of formaldehyde and keep at a certain temperature for 30 minutes.

3. Start heating up in stages.

4. Add the second batch of formaldehyde and keep the temperature constant for 13 minutes.

5. After heating up for the second time and the viscosity reaches the requirements, cooling with water.

6. The viscosity of the glue was measured by the foaming method.

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