What precautions should be taken during the storage and transportation of recycled polyester staple fibers to avoid moisture, clumping, or performance degradation?

1、 Storage procedure: Accurately control the environment to avoid moisture and clumping

Recycled polyester staple fiberAlthough it has low moisture absorption (with a moisture regain of about 0.4%), the temperature and humidity of the storage environment, as well as the stacking method, can still affect its fluffiness and performance. The following 5 points should be noted:

1. Storage environment: strict temperature and humidity control, isolation of pollution sources

Temperature and humidity requirements:

The warehouse temperature should be controlled at 15-30 ℃ (to avoid fiber softening and adhesion caused by high temperature, or fiber brittleness increased by low temperature), and the relative humidity should be ≤ 65% (excessive humidity can easily cause water vapor to adsorb on the fiber surface, and clumping may occur due to gravity compression during stacking, especially when the packaging is damaged, the risk is higher). Temperature and humidity recorders can be installed in the warehouse to record data daily. When exceeding the standard, they can be adjusted through dehumidifiers and air conditioning.

Environmental cleanliness:

The warehouse needs to be kept clean and away from dust sources (such as flour mills, building materials warehouses), oil pollution sources (such as machinery workshops), and chemical pollution sources (such as paint and solvent storage areas) - dust can easily adhere to fiber surfaces, affecting the combing effect during subsequent spinning; Oil pollution can contaminate fibers, leading to uneven dyeing; Chemical substances may react with fibers, damaging their mechanical properties.

Avoid light storage:

The warehouse should avoid direct sunlight (such as using blackout curtains or sealed warehouses). Ultraviolet radiation can accelerate the aging of polyester molecules, leading to a decrease in fiber fracture strength (long-term exposure may reduce strength by 5% -10%), especially for light colored recycled polyester short fibers, which may also experience yellowing.

2. Packaging protection: Ensure complete sealing to prevent moisture from entering

Packaging integrity inspection:

Recycled polyester staple fiberUsually, a combination of PE film bags, kraft paper bags, and trays (or woven bags with PE film inside) is used for packaging. Before storage, it is necessary to check whether the packaging is damaged one by one (such as PE film tearing, paper bag damage), and whether the seal is tight (whether the heat sealed edge is cracked). If the packaging is found to be damaged, it is necessary to immediately repair the PE film with tape or replace the packaging with a new one to prevent moisture and dust from entering.

Moisture proof pad and covering measures:

Fiber trays should be placed on wooden or plastic trays (avoiding direct contact with the ground, as moisture on the ground can easily enter through capillary action), and PE moisture-proof film (thickness ≥ 0.05mm) should be laid at the bottom of the tray; If the humidity in the warehouse is high (such as during the southern rainy season), waterproof canvas or PE film can be covered on top of the pallets to further isolate moisture.

3. Stacking standards: Control height and spacing to avoid squeezing and clumping

Stacking height limit:

The fiber stacking height of a single pallet needs to be determined according to the packaging strength, usually ≤ 1.5m (about 5-6 layers of packaging, total weight ≤ 800kg). Excessive height can cause long-term compression of the bottom fibers, resulting in a decrease in fluffiness (air between fibers is squeezed out, forming dense clumps). Additional combing is required during subsequent unpacking and use, which affects production efficiency; If vertical shelves are used for storage, the load-bearing capacity of each layer should match the weight of the fibers to avoid deformation of the shelves and fiber tipping.

Spacing and channel settings:

A passage of ≥ 50cm should be reserved between the pallets (for ventilation, inspection, and handling). When stacked against the wall, the distance between the fibers and the wall should be ≥ 30cm (to prevent wall condensation from infiltrating the packaging). Do not stack fibers at the entrance of the warehouse, under windows (susceptible to direct rain and cold air), or directly below the air conditioning or dehumidifier vents (excessive local wind speed may cause packaging wear and tear).

Classified stacking:

Recycled polyester staple fibers of different specifications (such as fineness, cutting length) and batches should be stacked separately, and each pile should be labeled with a sign (indicating specifications, batch, production date, shelf life) to avoid mixing and misuse. For example, fibers with a size of 1.56dtex × 38mm are used for spinning, while fibers with a size of 3.33dtex × 51mm are used for non-woven fabrics. Mixing them may result in substandard product quality.

4. Regular inspection: Identify problems in a timely manner to avoid performance degradation

Inspection frequency and content:

During storage, it is necessary to conduct a weekly inspection to check: ① whether the packaging is damaged or damp (such as paper bags becoming soft or water droplets inside the PE film); ② Whether the fibers have clumped (gently push the tray, if there are obvious dents or fiber displacement, it may have clumped); ③ Whether the temperature and humidity in the warehouse exceed the standard.

Agglomeration treatment:

If slight clumps (clumping diameter<5cm) are found, they can be combed and dispersed by a carding machine after opening the package; If the agglomeration is severe (agglomeration diameter>10cm), it needs to be isolated and stored separately to evaluate whether it affects its use (such as for low requirement geotextiles and fillers). It is prohibited to use it for high requirement spinning and fabric production.

5. Storage cycle: Follow the "first in, first out" principle to avoid long-term storage

The recommended storage period for recycled polyester staple fibers is ≤ 6 months (calculated from the production date). Long term storage (such as exceeding 12 months) may result in performance degradation due to slow aging of fiber molecules (such as reduced elongation at break and increased static electricity) even if the environment meets standards. When storing, the principle of "first in, first out" should be followed, and early batches of fibers should be prioritized to avoid backlog.

2、 Transportation process: Reduce vibration and compression to prevent packaging damage and moisture

Transportation is a high-risk link for the quality damage of recycled polyester staple fibers, which needs to be controlled from three aspects: transportation tools, loading standards, and protection during transportation:

1. Selection of transportation vehicles: Match environmental requirements and avoid special conditions

Short distance transportation (≤ 100km):

Priority should be given to enclosed box trucks (to prevent rainwater and dust from entering). If a flatbed truck is used, it should be covered with waterproof canvas (the canvas needs to be fixed with ropes to avoid being blown away by the wind during driving), and a PE moisture-proof film should be laid at the bottom of the carriage. Prohibit the use of open top trucks for transportation (especially on rainy or windy days) to avoid fiber packaging getting wet or contaminated with dust.

Long distance transportation (>100km):

Choose a box truck with temperature control and dehumidification functions (especially in areas with high temperatures in summer or low temperatures in winter), with the cabin temperature controlled between 15-30 ℃ and humidity ≤ 65%. If the transportation route passes through high humidity areas (such as coastal areas) or high temperature areas (such as the south in summer), silicone desiccants (1kg per 10 square meters) should be placed in the carriage to absorb moisture.

Special weather avoidance:

Avoid transportation in rainstorm, blizzard, typhoon and other weather. In case of sudden bad weather on the way, the vehicle shall be parked in the rain shelter and wind shelter in the service area, and the canvas coverage shall be checked to prevent rainwater leakage.

2. Loading standard: light loading and unloading, avoid squeezing and collision

Pre loading inspection:

Before loading, it is necessary to clean the debris inside the carriage (such as stones and oil stains) to ensure that the carriage is flat and dry; Check if the fiber packaging is intact. If the packaging is found to be damaged before transportation, it needs to be reinforced or replaced before loading.

Stacking and fixing:

Fiber trays should be evenly placed inside the carriage, and overloading on one side is prohibited (which may cause the vehicle to tilt or fibers to slide and collide during turns). Wooden square strips or inflatable buffer bags are used to separate pallets to prevent packaging damage caused by friction during driving; Use ropes or barriers to secure the trays on both sides of the carriage to prevent fiber displacement and tipping caused by vibration.

Loading and unloading operations:

When using a forklift for loading and unloading, the forklift forks should be covered with soft rubber sleeves (to avoid scratching the packaging). When picking up pallets, the forks should be lifted smoothly and rough operations (such as sudden lifting, sudden lowering, or colliding with the carriage) are prohibited; When manually transporting small packaging fibers, it is necessary to hold the bottom of the packaging with both hands and avoid dragging (which can easily tear the PE film).

3. On the way monitoring: Real time monitoring of status and timely handling of anomalies

Route planning:

Priority should be given to highways (with smooth road surfaces and low vibration), avoiding bumpy roads (such as rural dirt roads and construction roads), and reducing the compression of fibers by vibration (bumps can easily cause fiber clumping, especially for loosely packaged fibers).

Mid way inspection:

Stop and check once every 200km: ① Check if the packaging is damaged (such as if the canvas has shifted or if the PE film is torn); ② Whether the fibers are tipping or clumping (gently push the tray and observe for stability); ③ Whether the temperature and humidity inside the carriage exceed the standard (if there is a temperature control device, it is necessary to confirm that the parameters are normal).

Emergency Management:

If the packaging is found to be damaged on the way, stop immediately and repair the PE film with tape. If the damage is severe, use spare PE film to wrap it again; If the fibers are found to be damp, they should be immediately opened for inspection upon arrival at the destination, dried or air dried (temperature ≤ 60 ℃, to avoid high temperature damage to the fibers), and evaluated for performance before use.

3、 Special scenario precautions

Export transportation (sea/air):

When shipping by sea, it is necessary to choose containers (preferably dry cargo containers to avoid condensation in refrigerated containers), place moisture-proof agents and temperature and humidity recorders inside the containers, and check the sealing of the containers before transportation (to prevent seawater leakage); Attention should be paid to the weight of fiber packaging during air transportation to avoid overweight, and it is prohibited to mix it with sharp or oily goods.

Anti static requirements:

Recycled polyester staple fiberDuring transportation and storage, static electricity is easily generated due to friction (especially in dry environments), which may adsorb dust or produce sparks when opening packages (although polyester is not flammable, it should be avoided from being close to fire sources). Static eliminators can be installed in the warehouse, transportation vehicles can be grounded (to prevent static electricity accumulation), and operators can wear anti-static clothing and gloves.