Revealing the production process of white glue
Author: source: Datetime: 2018-10-31 15:41:41
White glue (polyvinyl acetate adhesive) is a thermoplastic adhesive prepared by polymerization of vinyl acetate monomer under the action of initiator. It can be cured at room temperature, fast curing, high bonding strength, good toughness and durability and not easy to aging.
1. dissolve the PVA powder in deionized water and filtrate it completely. (optional PVA-1788 2488, etc.)
2. Put polyvinyl alcohol glue into stainless steel reaction kettle (or enamel reaction kettle, but the heat transfer effect of enamel kettle is not as good as stainless steel reaction kettle), add emulsifier OP-10, start the mixer, make it mix evenly.
3. 15% (6.9) of the total amount of polyvinyl acetate monomer and 40% (0.036) of potassium persulfate were added to the stainless steel reactor, and the stirring was continued and the temperature began to rise. When the temperature rises to 60-65 C, stop heating. It should be noted that the initiator potassium persulfate should first be mixed with pure water into 8%~10% aqueous solution.
4. Under the action of initiator, although the heating stops, the temperature rises spontaneously. When the temperature is above 65, the reflux device of the reactor begins to appear reflux. When the temperature rises above 80 C, the reflux gradually decreases. At this time, the polyvinyl acetate monomer is dripped from the drop bucket of the reactor, and the dripping acceleration should be controlled at about 10% of the total dripping amount per hour (that is, about 4.6). In the process of reaction, we should pay close attention to the reaction temperature, adding cooling water to the jacket of the reactor to control the reaction temperature, not higher than 80%.
5. In addition to vinyl acetate monomer, initiator is also added, and the amount added per hour is about 4.5% of the formula.
6. vinyl acetate and initiator should be controlled at about 8h. Because of the effect of initiator, the reaction is more intense. After adding monomer, the reaction temperature will rise by itself. When it rises to about 93 C, the reaction is kept for 30 minutes. The polymerization was basically completed.
7. Turn on the cooling water to reduce the temperature in the stainless steel reactor. When the temperature is below 50, add the sodium bicarbonate solution (10% concentration should be dissolved in advance) and dibutyl phthalate, and adjust the pH value to 6-7.
8. The stirrer of stainless steel reactor can not stop all the time. When it is cooled to room temperature, white latex products are obtained. The stirring, discharging and packaging are stopped.
9. When the viscosity of white latex is too high and the water resistance is poor, the amount of polyvinyl alcohol in the formula can be reduced appropriately.
10. if the stability of white latex emulsion is poor, the dosage of some initiators in the formula can be reduced properly. If too little, it will not cause the monomer to be difficult to polymerize.
11. The amount of dibutyl phthalate should not exceed 10% of the monomer. Otherwise, the viscosity of the white latex product will decrease and the cost will increase. Its main function is to increase the toughness of the emulsion and reduce the film forming temperature of the emulsion.
12. if the foam of white latex is more, you can add proper amount of defoamer.
13. Initiator potassium persulfate dosage and adding time should be carefully grasped, when the beginning of reflux, if the reflux is large, indicating that the initiator did not play a role, too many monomers, should stop adding monomers, can be increased as appropriate, when reflux normal monomers.
14. The white latex produced by the above-mentioned formulation and preparation method is a white uniform emulsion liquid with a solid content of about 50% and a pH value of about 5.
In addition, this white latex product can also add 801 glue and anatase titanium dioxide to produce modified white glue.
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