Raffia Grade PP vs Ordinary PP: Key Differences For Recycling Machine Operators

Polypropylene is one of the largest categories of plastics in terms of global recycling volume, mainly divided into two types in the recycling industry: Raffia Grade PP and ordinary PP. In actual pp raffia recycling production, many recycling equipment operators fail to distinguish the characteristics of the two materials, easily causing production problems such as granulation blockage, granule foaming, insufficient tensile strength, and large fluctuations in production capacity when using the same equipment. This article comprehensively analyzes the core differences between the two types of PP from five dimensions: material characteristics, waste sources, processing parameters, equipment compatibility, and finished product quality, providing professional reference for the practical operation of PP recycling production lines.

1. Basic Definitions and Waste Sources

1.1 Raffia Grade PP (also known as woven PP) is a homopolymer polypropylene with high crystallinity and high tensile strength, specifically developed for flat filament drawing processes, possessing extremely strong fiber toughness. Common recycled waste includes PP woven bags, ton bags, packaging raffia yarn, agricultural woven tarpaulins, and industrial woven packaging products. The vast majority of Raffles PP waste contains UV-resistant additives, dust impurities, and printing inks. Woven bags and ton bags often contain residues of packaged cement, chemical raw materials, mineral powder, or grains, requiring professional cleaning appropriate to their contamination levels, which is the core processing target of a professional PP raffia washing line.

1.2 Regular PP: General-purpose injection molding and extrusion grade polypropylene, with lower crystallinity and more flexible toughness. Typical waste includes PP plastic bottles, plastic containers, plastic buckets, injection molded parts, rigid PP scraps, and everyday plastic products. Common contaminants include dust, sand, and metal contaminants. Plastic recycling equipment manufacturers customize hard plastic washing line specifically for it.This type of waste has lower additive content, more uniform material, and a more stable overall appearance.

2. Differences in Core Physicochemical Properties

Crystallinity and Toughness: Raffi-grade PP has high crystallinity and excellent tensile strength, but poor melt uniformity; ordinary PP has low crystallinity, is easy to plasticize, and is very easy to melt and process.

Additive Content: Raffi-grade PP generally contains UV stabilizers and anti-aging additives, resulting in a higher melting temperature; ordinary PP has almost no additional additives and stable melt performance.

Material Form: Raffi-grade PP is mostly fiber-woven waste, which easily entangles in the equipment shaft during shredding, a primary consideration when configuring professional pp raffia recycling equipment; ordinary PP is mainly hard, blocky, and sheet-like waste, allowing for smooth feeding.

Impurity Characteristics: Raffi-grade PP waste has a large amount of dust, sand, and printing ink adhering to its surface; ordinary PP has fewer impurities and a higher level of cleanliness.

3. Core Differences in Recycling and Processing

Differences in practical debugging of shredding and washing lines and pelletizing lines:

Shredding Stage: Woven Raffia PP has high toughness and requires a heavy-duty shredder, such as the AGX heavy-duty single-shaft shredder, equipped with a solid steel rotor with a diameter of 750 mm and a speed of 52 rpm. The concave cutter head is equipped with 4-directional rotating aggressive blades to solve the problem of material entanglement on the shredder's main shaft. For ordinary rigid PP, depending on the material size, an AGS single-shaft shredder or an AGD dual-shaft shredder can be selected. However, considering the possibility of metal impurities in the post-consumer material, a metal detector needs to be added during the belt conveyor feeding process.

Washing Stage: Raffia PP requires intensive friction washing to thoroughly remove mud, sand, and residual ink. The washing steps generally involve floating washing – low-speed friction washing – high-speed friction washing. A customized PP raffia washing line is precisely designed for this multi-stage cleaning process to eliminate stubborn contaminants. Improper handling in this stage has a much greater impact on the final pellet quality than in the pelletizing stage. Ordinary PP requires floating washing – low-speed friction washing, while some PP materials with only dust only require floating washing to meet standards.

Extrusion pelletizing stage: Both processes follow the same extrusion pelletizing procedure. The cleaned and dried material is fed into the extruder, undergoes vacuum degassing, filtration and slag removal, water ring (underwater) granulation, and vibration drying, before entering the silo system. However, it is important to note that machine debugging requires engineer guidance. For Raffia PP, professional production via a PP raffia pelletizing line requires increased extrusion temperature and reduced feed rate to avoid unmelted particles; for ordinary PP, standard granulation parameters are suitable for more stable production capacity and quality.

4. Differences in Recycled Pellets Quality and Applications

Raffia-grade recycled PP granules processed by mature pp raffia recycling systems boast high strength and excellent toughness, primarily used for reproducing woven bags, ropes, and industrial packaging. Regular recycled PP granules offer good flowability and uniform texture, suitable for injection molding of daily necessities, plastic parts, and general-purpose plastic products. Equipment operators must strictly separate these two types of waste materials to ensure consistent granule quality and maximize the market price of the recycled granules.

5. Key Practical Points for Operators

Operators must strictly distinguish between raffia PP and ordinary PP waste before processing, and adjust equipment temperature and feed rate in real time according to material type.

• Key points for operating a braided raffia PP recycling line:

-Unpack and break up the materials first. Do not feed whole bales to avoid raffia getting tangled on the cutter shaft, causing a surge in load, reduced output, frequent overload alarms, or even shutdown.

-Check the shredder blade gap to avoid excessively large gaps, which can lead to incomplete shredding of long filaments and subsequent material blockage in the conveyor.

-Strengthen the cleaning process with a standard PP raffia washing line and check the moisture content of the dehydrated material to avoid black spots and bubbles in the particles caused by incomplete cleaning and high moisture content.

-Regularly replace the extruder filter screen of the PP raffia pelletizing line to effectively improve production efficiency and particle quality rate.

• Key operational points for PP hard material recycling lines:

-Control the gap between the moving and fixed blades to prevent large pieces of material from jamming the crusher.

-Regularly grind or replace the blades, and feed materials of varying thicknesses separately to prevent inconsistent output sizes and excessive fine powder.

-If there is residual adhesive or paper labels on the material surface, a label removal and hot washing process is required.

-Try to maintain a uniform crushed material size and a stable feeding speed; otherwise, the main unit current will fluctuate, and the extrusion pressure will jump.

-Regularly clean the screw, vent, and die; drain the material from the barrel after shutdown.

6. In conclusion

Lafite-grade PP differs significantly from ordinary PP in material properties and recycling processes. Accurate material classification and matching with professional pp raffia recycling equipment, including tailored PP raffia washing line and high-precision PP raffia pelletizing line, can help recycling equipment operators reduce malfunctions, lower energy consumption, and produce high-quality recycled PP pellets. If you require a free solution configuration, contact Kitech engineers for further advice!