{"id":4139,"date":"2026-05-29T05:38:39","date_gmt":"2026-05-29T05:38:39","guid":{"rendered":"https:\/\/kitech-recycling.com\/?p=4139"},"modified":"2026-05-29T05:40:13","modified_gmt":"2026-05-29T05:40:13","slug":"drying-and-moisture-control-plastic-recycling","status":"publish","type":"post","link":"https:\/\/kitech-recycling.com\/es\/blog\/drying-and-moisture-control-plastic-recycling\/","title":{"rendered":"Control de secado y humedad en el reciclaje de pl\u00e1stico: de 30% a <3%"},"content":{"rendered":"
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In drying and moisture control plastic recycling work, decisions made before material reaches the extruder shape final pellet quality. If free water, surface moisture, and absorbed moisture are not handled after washing, the line can see vapor at the die, rejected batches, and higher energy use.<\/p>\n

This guide offers recycling plants a simple methodology to select an appropriate drying solution based on feedstock form, target moisture content, test point, and downstream risk. It covers the entire scope from washing-line layout and dewatering, through thermal and desiccant drying to moisture-meter controls, and pelletizing release rules.<\/p>\n

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Quick Specs<\/h3>\n\n\n\n\n\n\n\n
Control window<\/td>\nAfter washing and before extrusion or pelletizing<\/td>\n<\/tr>\n
Main moisture types<\/td>\nFree water, surface moisture, and absorbed moisture<\/td>\n<\/tr>\n
Common equipment path<\/td>\nMechanical dewatering, squeezing, hot-air drying, desiccant drying, and moisture testing<\/td>\n<\/tr>\n
Kitech flexible-film signal<\/td>\nJGM plastic squeezing dryer: 200-1000 kg\/h, 3-5% final moisture, and 92-95% water separation for suitable flexible materials<\/td>\n<\/tr>\n
Best decision rule<\/td>\nChoose by material behavior, target moisture, line capacity, and test point, not by dryer name alone<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Contents<\/strong><\/p>\n

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  1. Why moisture becomes a source of loss for quality<\/a><\/li>\n
  2. Moisture targets by material<\/a><\/li>\n
  3. 9-Point Moisture Control Ladder<\/a><\/li>\n
  4. Extruder and pellet quality risk<\/a><\/li>\n
  5. Moisture testing and batch release<\/a><\/li>\n
  6. 2026 outlook<\/a><\/li>\n<\/ol>\n<\/div>\n

    Why moisture becomes the hidden yield loss in plastic recycling<\/h2>\n

    Moisture becomes a costly yield loss because it moves through the recycling process in several forms. Free water on flakes can drain readily from the material. Surface moisture clings to films, labels, fines, and rough-cut edges, while internal moisture can remain trapped inside the feedstock without being obvious at the surface.<\/p>\n

    According to the Association of Plastic Recyclers, a plastics recycling facility processes plastic resin from post-consumer and post-industrial sources through grinding, washing, float\/sink separation, rinsing, drying, elutriation, decontamination, and manufacturing steps. Drying is not a side step; it is a quality gate between water removal and valuable polymer recovery.<\/p>\n

    Plastics Technology warns against trusting surface appearance alone: recycled HDPE and PP can look dry while trapped water remains inside pellets or resin. Without careful moisture management, a plant can send a batch that looks dry into extrusion and then see vapor, foamy melt, inconsistent shot size, or unstable pellet density.<\/p>\n

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    Common mistake<\/strong><\/p>\n

    Many plants assume processed HDPE and PP pellets are dry because the surface looks clear. If batch release skips the dryer-discharge test, wet material can enter extrusion and trigger vapor at startup. Real failure is not simply a lack of drying capacity; it is the absence of a documented pelletizing release rule for pre-processing inspection.<\/p>\n<\/div>\n

    Moisture content targets by material and output form<\/h2>\n

    There is no single correct moisture content value for all types of recycled material. Different recycled materials like PET flake (which can be very wet before filter media), washed LDPE film, or hdpe granules before pelletizing behave very differently and require a target adjusted to feedstock form, downstream processes, and end product specification.<\/p>\n

    \n\n\n\n\n\n\n\n\n\n\n
    Material\/output form<\/th>\nMoisture behavior<\/th>\nPractical target signal<\/th>\nUse-condition note<\/th>\n<\/tr>\n<\/thead>\n
    LDPE film after washing<\/td>\nWater trapped in folds and film bundles<\/td>\n3-5% final moisture from Kitech JGM squeezing dryer data<\/td>\nSingle first-party equipment condition; verify with feedstock test run<\/td>\n<\/tr>\n
    PP woven bags<\/td>\nWater held in fabric structure and fines<\/td>\nSqueezing plus thermal trim drying when pelletizing needs a lower entry moisture<\/td>\nDo not use rigid-flake dryer rules without testing<\/td>\n<\/tr>\n
    Rigid HDPE\/PP flakes<\/td>\nMostly surface moisture, plus fines and hollow geometry<\/td>\nAPR polyolefin lab practice dries flake below 1% by weight<\/td>\nAPR lab practice is a reference point, not a universal production warranty<\/td>\n<\/tr>\n
    PET flakes<\/td>\nMore moisture-sensitive before melt processing<\/td>\nAPR PET practice includes washing, drying, elutriation, and melt filtration controls<\/td>\nUse PET-specific drying and quality checks before extrusion<\/td>\n<\/tr>\n
    Flexible mixed plastic<\/td>\nVariable thickness, surface area, and water retention<\/td>\nIndustrial thermal drying commonly targets residual moisture below 3% in flexible plastic drying context<\/td>\nTie target to flake size, thickness, airflow, and residence time<\/td>\n<\/tr>\n
    Hygroscopic engineering plastics<\/td>\nMoisture can sit inside the polymer<\/td>\nDesiccant drying and dew point control are often required<\/td>\nDo not rely on surface dewatering alone<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

    Drying system choices by type of plastic and recyclability risk<\/h2>\n

    For a recycler, the right recycling machine setup depends on the type of plastic, contaminant load, and downstream processing. Different types of plastics absorb moisture differently: PET and PA can absorb water into the polymer, while PE and PP usually hold surface moisture around flakes, labels, fines, and folded film. A plastic drying machine using hot air can remove moisture from surfaces, but desiccant control may be needed when absorbed water turns into water vapor during extrusion or injection molding.<\/p>\n

    Proper drying protects plastic pellets from excess moisture, high moisture content, discoloration, corrosion around metal parts, and weak melt behavior. Treat the drying machine as part of the full line, not as a standalone fix: washing, sorting, dewatering, moisture testing, and batch release all affect the recyclability and value of recycled plastic.<\/p>\n

    9-Point Moisture Control Ladder: dewater, dry, then test<\/h2>\n

    Do not install a generic plastic dryer as a generic \u201cbox-type\u201d piece of equipment. Instead, map the flow from the raw material condition to the appropriate dewatering, the final drying step, and a testing location prior to pelletizing, to plan the entire washing line properly.<\/p>\n

    \n\n\n\n\n\n\n\n\n\n\n\n\n\n
    Material\/feedstock state<\/th>\nFirst drying move<\/th>\nFinal control move<\/th>\nTest point<\/th>\n<\/tr>\n<\/thead>\n
    Wet film after washing<\/td>\nSqueeze free water<\/td>\nThermal trim drying if extrusion needs it<\/td>\nBefore agglomeration or pelletizing<\/td>\n<\/tr>\n
    Flexible film after dewatering<\/td>\nCheck film bundle moisture<\/td>\nHot-air or squeezing adjustment<\/td>\nDryer discharge<\/td>\n<\/tr>\n
    PP woven bags<\/td>\nSqueezing dryer<\/td>\nResidence-time check<\/td>\nBefore densifier or pelletizer<\/td>\n<\/tr>\n
    Rigid HDPE\/PP flakes<\/td>\nCentrifugal dewatering<\/td>\nThermal dryer if target is not met<\/td>\nFlake silo entry<\/td>\n<\/tr>\n
    PET bottle flakes<\/td>\nCentrifugal and thermal drying<\/td>\nPET-specific pre-drying before melt<\/td>\nBefore extrusion<\/td>\n<\/tr>\n
    Mixed recycled pellets<\/td>\nStorage moisture control<\/td>\nMoisture meter release check<\/td>\nBefore packaging or reuse<\/td>\n<\/tr>\n
    Hygroscopic plastics<\/td>\nDesiccant dryer<\/td>\nDew point, airflow, and residence control<\/td>\nHopper outlet<\/td>\n<\/tr>\n
    Low-value contaminated feedstock<\/td>\nImprove washing and fines removal first<\/td>\nAvoid drying dirt into pellets<\/td>\nAfter rinse and before dryer<\/td>\n<\/tr>\n
    High-value pelletizing feedstock<\/td>\nStage drying by material<\/td>\nDocument batch moisture<\/td>\nBatch release record<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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    Advantages<\/strong><\/p>\n