I. SUMMARY OF SUPPLY SOURCES OF PUSH SUPPLY:
For processing block rubber, the starting materials are latex and mixed latex:
– Latex: accounts for 85% or more of the exploited output, is the main source of raw materials for the production of good products, which are collected from the orchard to the factory in natural liquid form.
– Mixed latex: is the curdled latex remaining in the pus-collecting cup on the scraped mouth after the main season of latex harvesting. Mixed latex accounts for 10-15% of exploited output, this type is often mixed with many impurities, has a bad smell due to collection and storage for many days, oxidized latex and discolored enzymes are used only as raw materials. Production of products SVR10, SVR20
Raw material latex:
1. Composition of latex:
The resin produced from the rubber tree is called latex. Latex is a white liquid like condensed milk or slightly yellow. It is actually a colloidal suspension of very small rubber particles suspended in a solution that is mostly water.
Rubber particles are in the form of spheres with an average diameter of about 0.5 mm, they move chaotically in the solution
Analyzing a typical latex color we have:
Pure rubber 30-40%
Plastic 2 %
Protein 2 %
Minerals 0.5%
Sugar 1 %
Water 50-60%
Depending on the variety, age of the tree and depending on the season, the components in latex can be changed, but the difference is not big, mainly because of the content of pure rubber in latex.
2. Properties of latex water:
The rubber particles suspended in the latex are covered with a thin layer of protein. After about 5-6 hours of exposure to the air, the microorganisms in the latex work to make the latex environment more and more acidic. high, the protein layer covering the rubber seeds is destroyed and these particles stick together. It is natural coagulation, latex coagulates into a soft, milky white mass, the longer it is left, the harder and darker it becomes. color
Latex can coagulate for the following reasons:
– Chemistry: due to alcohol or acids
– Heat: hot or cold
Mobility: agitation
3. Stabilization of latex:
The latex needs to be kept stable i.e. not frozen before processing, which is very important. Latex is stabilized by adding to it certain antifreeze chemicals called stabilizers. The most widely used stabilizing factor is the ammonia solution. Pure ammonia is mixed with water into a solution of low strength, then added to latex and stirred, so that the latex environment is kept in an alkaline state, the protein layer surrounding the rubber beads is protected, so the latex does not freeze. okay again
The concentration of ammonia in latex depends on the type of latex, the time it takes to store and the processing process, usually 0.2% and the highest up to 0.45% by weight of pure rubber in latex.
II. Preliminary processing of latex into rubber com:
– Latex (latex) is transported from the orchard to the factory by truck or tractor, each vehicle has 3 tanks
– The latex is discharged into the receiving ditch through a 60 mesh sieve (60 holes / 1 inch) to remove impurities, bark, leaves….
– When the latex discharges 1/3 of the tank, the chemical laboratory takes a sample to measure the DRC content.
– In the process of receiving latex on the receiving ditch, water is immediately added to the sieve. At the same time, water is also added to reduce the foam in the mixed tank
– This amount of water is calculated before or according to the following experience, so the DRC content in the freezing ditch is about 25-27%.
– Different DRC content in other polymeric tanks leads to different quality. Hence reducing the DRC to even out the latex quality.
– In the mixed lake, people stir the latex with a stirrer for about 10 minutes. Then let it settle for 10-40 minutes and then drain it into the fields to freeze it
– On the drain is arranged acid flow and pus flow tangled together. When latex is discharged into each freezing ditch, the pH must be determined for each ditch
– After entering the ditch to freeze, people use a spray nozzle to lower the foam, after filling the ditch, they also spray with Sodium Metabisulface solution to prevent oxidation of the surface of the pus ditch.
– Finally, we use PE carpet to cover the ditch to prevent dust. The time for the latex to freeze on the ditch is from 6-10 hours, after the latex has completely frozen, the frozen fields can be filled with water to float the pus mass to facilitate the rolling process.
The machine pulls and presses the rubber block on the ditch to remove the serum, reducing the thickness of the latex from 0.4m to 0.1m.
– The latex sheet is continued through 3 crepe machines thanks to the conveyor belt to continue laminating impurities and serum. The thickness of the latex sheet is now reduced from 50mm down to 5-7mm. These three rolling mills have a rotating speed that is gradually increasing and the closing of the shaft is decreasing, on each machine there is a water spray system to wash away impurities in the latex.
– The latex sheet is continued through the conveyor to the cutter (sherdder) to cut into small particles (5mm). These particles fall into the hash pool, which is filled with water and the water is returned from the vibrating floor.
– Particles and water are pumped to the vibrating floor by a latex pump. Vibrating floor will separate water and rubber particles. These particles through the feed hopper fall into the carton (trolley), while the water is circulated to the hash lake. On the vibrating floor and drying barrel, there is a water spray system to wash the nuggets for the last time.
