The dyeing process of sewing thread (especially premium synthetic threads like polyester and nylon 66) imposes specific technical requirements on perforated PP dyetubes. Twisting manufacturers must choose and use dyetubes carefully in greige twisted yarns dye package winding.
Core Overview: The Role of Perforated PP Dyetubes in Sewing Thread Cheese Dyeing
In high-temperature, high-pressure package dyeing machines, sewing threads (in package form) are tightly mounted on dyeing tube. The dye liquor, driven by high-pressure pumps, circulates from the tube’s inner core outward through the yarn layers or vice versa. Thus, the dyeing tube serves as the "skeleton" and "channel" for dye circulation, ensuring uniform, stable, and low-resistance flow. Throughout this process, the tube must not negatively affect the sewing thread’s quality.
Greige yarn polyester filament twisted on dye tube
1. Hardness Requirements: Balancing Rigidity and Elasticity
1.1 Adequate Rigidity (High Hardness):
● Resistance to Compression Deformation: During dyeing, dye pressure can reach 0.2–0.4 MPa (equivalent to 2–4 atmospheres), and yarn packages expand when wet, exerting immense radial pressure on the tube wall. If the tube is too soft, it may collapse, blocking or distorting dye flow, leading to issues like uneven dyeing or ring dyeing (color difference between inner and outer layers).
● Supportiveness: The tube must support tightly wound yarn packages, preventing collapse or deformation under high temperatures due to weight and pressure. farerthread.com
● Requirement: This is typically achieved through formulation modifications (e.g., adding stiffening and toughening masterbatches) to enhance PP’s flexural modulus and hardness.
1.2 Moderate Elasticity (Low Hardness/Toughness):
● Sealing: Tube ends must tightly fit with machine seals (e.g., chrysanthemum cores or mushroom heads) to prevent dye leakage. Slight elasticity ensures minor deformation under pressure for effective sealing.
● Impact Resistance: The tube should withstand handling impacts during loading/unloading without brittle fracture.
● Vibration Damping: It absorbs vibrations and reduces noise during high-speed dye circulation.
1.3 Conclusion: Ideal PP dye tubes hardness requires an optimal balance between high rigidity and moderate toughness, often achieved using reinforced and toughened polypropylene composites.
2. High-Temperature and High-Pressure Resistance: Dimensional Stability and Durability
Sewing thread (e.g., polyester) dyeing typically occurs at 125°C–135°C under saturated steam pressure, sometimes up to 140°C.
2.1 High Heat Deflection Temperature (HDT): Pure PP homopolymer has a low HDT (~100°C) and would soften excessively. Thus, tubes must use heat-resistant modified PP (e.g., copolymer PP, glass fiber reinforcement, or additives) to maintain HDT above 150°C, preventing softening, creep, or collapse.
2.2 Excellent Pressure Creep Resistance: The material must resist slow plastic deformation under prolonged high-temperature and high-pressure cycles, avoiding wall bulging or inner diameter shrinkage.
2.3 Low Thermal Expansion Coefficient: PP naturally has high thermal expansion. Modified tubes should minimize this to ensure minimal changes in outer/inner diameters from room temperature to 135°C, preventing fit issues with yarn cores or seals.
2.4 Resistance to High-Pressure Steam Permeation: Dense structure prevents steam and dye penetration, avoiding structural damage during drying or cooling.
3. Elimination of Fluorescence in Dyeing bobbin
PP dyeing bobbins must be optically inert, producing no autofluorescence under UV light (e.g., from inspection lamps) or specific light sources.
3.1 "Invisible" Contamination of Sewing Threads: Many high-end textiles (e.g., light-colored apparel, medical textiles) strictly limit fluorescence. If tubes contain fluorescent brighteners or pigments/additives that glow under UV, these may leach in trace amounts during dyeing, contaminating white threads.
3.2 Implementation Measures:
● Raw Material Control: Use non-fluorescent grade PP resin as the base.
● Pigment/Masterbatch Selection: If colored tubes are used (e.g., for specification differentiation), pigments must pass strict fluorescence tests. Choose professional suppliers providing "non-fluorescent" or "suitable for high-temperature dyeing tubes" colorants.
4. No Color Migration in Colored Dye Tubes
Tube colors (pigments) must have high thermal and chemical stability, preventing migration to sewing threads under high-temperature, high-pressure dyeing.
4.1 Color Contamination (Staining): Direct risk where migrated color causes irreversible stains, spots, or shade changes in light or bright threads, leading to downgrading or waste.
4.2 Synergy with Fluorescence Issues: Color migration may introduce other contaminants, exacerbating fluorescence problems.
4.3 Impact on Dye Uptake: Migrated impurities can interfere with dye absorption, affecting color fastness or uniformity.
4.4 Solutions: Use high-performance pigments with superior migration resistance and thermal stability well above dyeing temperatures. Pigments must be evenly dispersed and firmly "locked" in the PP matrix. Tubes should undergo simulated high-pressure migration tests under extreme conditions to ensure no yarn discoloration. farerthread.com
5. Smooth Surface Free of Burrs
The entire tube surface, especially conical ends contacting yarn and all hole edges, must achieve high smoothness without molding flashes, burrs, debris, or sharp edges.
5.1 Yarn Snagging/Breakage: Common physical damage where burrs hook fibers during loading/unloading, causing fuzzing, breakage, or tangling that hampers unwinding and sewing efficiency.
5.2 Yarn Strength Damage: Sharp edges can notch threads under pressure, weakening them and creating potential break points during use.
5.3 Disrupted Dye Flow: Internal burrs disturb laminar flow, causing turbulence or fiber buildup, potentially clogging holes over time.
5.4 Prevention: Employ high-precision molds to minimize flashes, optimize injection processes (pressure, temperature, time), and include post-processing for smooth finishing of ends and holes.
6. Other Key Technical Requirements
Summary
Perforated plastic dyetube as the carrier of sewing threads to package dyeing, delivered to dyeing house with greige yarn and used in dyeing together, the dyetubes’ functionality and quality deserve attention from twisting manufacturers or dyehouses. This is essential producing high-quality filament high strength polyester sewing thread, embroidery thread and bonded nylon thread.
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