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High Bulk Yarn (HBY)

-- Steady & Reliable Manufacturer --

What Is High Bulk Yarn?

High Bulk Yarn (HBY) is an engineered multifilament yarn in which a proportion of high-shrinkage filaments is blended with low-shrinkage or non-shrinkage filaments, then subjected to a controlled heat treatment. The high-shrinkage component contracts sharply, forcing the stable filaments to buckle outward and form permanent, three-dimensional loops and coils. The result is a yarn with dramatically increased volume — typically 30–80 % more bulk than an equivalent-denier standard yarn — while retaining the continuous-filament strength and consistency that staple-fiber bulky yarns cannot match.

At GC FIBER, we engineer HBY through both bi-shrinkage blending on the spinning line and post-process steam or dry-heat relaxation. Our technical team controls the high-shrinkage / low-shrinkage ratio, heat treatment temperature, and overfeed percentage to hit your exact bulk target — whether you need a soft, airy hand for blanket fabric or a dense, plush surface for carpet backing.

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Specification

ParameterTypical RangeNotes
Polymer BasePET, PA6, PA66, PP, rPETGRS rPET available
Denier Range100D – 1200DFiner HBY (75D) on special request
Filament Count48f – 288fHigher counts give finer, softer bulk
High-Shrinkage Component Ratio20 % – 50 % by weightHigher ratio = greater bulk after relaxation
Boiling Water Shrinkage (pre-bulk)30 % – 55 % (HS component)Relaxed component ≤ 3 %
Bulk Level (after relaxation)Low / Medium / High / Ultra-HighDefined by % volume increase vs. flat FDY reference
Tenacity (bulked)2.2 – 3.8 g/dLower than flat FDY due to filament buckling
Elongation at Break25 % – 50 %Higher elongation after relaxation
LusterSemi-dull / Full-dullBright luster uncommon in bulked yarn
Cross-SectionRound / Trilobal / HollowHollow filaments amplify thermal bulk effect
Heat TreatmentSteam (105–120 °C) / Dry heat (160–200 °C)Steam gives softer hand; dry heat gives more stable bulk
Cone Weight2 kg / 5 kgBulked yarn requires larger cone diameter
ColorRaw white, dope-dyed, space-dyed basePost-bulk dyeing also available

Application

HBY's defining characteristic — maximum volume from minimum weight — makes it valuable wherever thermal comfort, visual fullness, or cost-efficient coverage is the design goal:

  • Blankets & Throws — HBY gives woven and knitted blankets their lofty, airy hand feel while keeping the fabric lightweight. The trapped air between bulked filaments provides natural thermal insulation without the weight of fill fibers.
  • Carpet & Rug Pile — HBY in BCF (Bulked Continuous Filament) form is the standard pile yarn for tufted carpet. The permanent bulk provides resilience — the pile springs back after foot traffic rather than flattening permanently.
  • Upholstery & Furniture Fabric — Medium-bulk HBY used as weft in upholstery weaves creates a full, padded surface texture that reduces the need for additional foam underlays.
  • Faux Fur & Plush Fabric — Ultra-high bulk HBY (50 % HS ratio) mimics the density and loft of natural fur when knitted on a warp knitting machine and then napped or sheared.
  • Nonwoven Batting & Filling — Chopped or continuous HBY is used as thermal batting in quilts, sleeping bags, and outerwear padding, offering a down-alternative fill with consistent loft.
  • Automotive Headliners & Trunk Liners — HBY fabric provides the required sound-absorption and thermal insulation in automotive interior applications, meeting OEM specifications for dimensional stability after heat aging.
  • Technical Filtration Media — High-bulk, high-surface-area HBY nonwovens are used in HVAC filtration and liquid filtration where depth-loading capacity (bulk) determines filter service life.

Advantage

  • Up to 80 % More Volume vs. Flat Yarn — Same denier, dramatically more coverage. HBY allows fabric designers to achieve a full, luxurious hand without increasing yarn weight or fabric cost per square meter proportionally.
  • Permanent Bulk Stability — Unlike mechanically textured yarns that partially relax in hot-wash cycles, HBY's bulk is set by the differential shrinkage mechanism and is thermally stable at temperatures up to 140 °C (PET grade) — well above typical laundering or autoclave conditions.
  • Superior Thermal Insulation — The air pockets trapped within the bulked filament matrix give HBY fabrics a CLO value 15–25 % higher than equivalent flat-yarn fabrics of the same area weight, without added thickness.
  • Customizable Bulk Level — By adjusting the HS/LS ratio, heat treatment temperature, and overfeed, we tailor bulk from a subtle texture upgrade (Low) to a full faux-fur density (Ultra-High) — all within the same production platform.
  • Continuous Filament Consistency — Unlike staple-fiber bulky yarns (acrylic, wool), HBY sheds no fiber lint, pills far less, and maintains consistent denier from cone to cone, reducing fabric defects in high-speed knitting.
  • Hollow Filament Option — Combining hollow cross-section filaments with the bi-shrinkage bulk mechanism amplifies both thermal insulation and bulk volume simultaneously, ideal for lightweight outerwear padding alternatives.

Payment & Shipping

  • Payment Terms — T/T: 30 % deposit upon order confirmation, 70 % before shipment. L/C at sight for orders ≥ USD 20,000. PayPal / Western Union for sample invoices.
  • Sample Policy — Sample cones (200 g – 500 g, pre-bulked) provided free; buyer covers express freight or provides courier account. Bulk level and shrinkage data sheet included.
  • Lead Time — Standard HBY in raw white (100D–300D, medium bulk): 10–18 business days. Custom HS ratio, hollow filament, or dope-dyed base: 25–40 business days after specification approval.
  • MOQ — 500 kg per denier / bulk-level / color SKU. Custom bi-shrinkage blend or hollow-filament HBY: 1,000 kg minimum. Repeat orders of confirmed specs: 300 kg.
  • Shipping — Sea freight FCL / LCL from Ningbo or Shanghai. Note: bulked yarn has lower packing density than flat yarn — consult us for accurate CBM-to-weight ratio before booking container. Air freight available for samples. Incoterms: FOB, CIF, DAP, DDP.
  • Documentation — COA including denier, tenacity, elongation, bulk level measurement, and heat treatment conditions. REACH, OEKO-TEX, and GRS certificates available for applicable grades.
  • Q: What is the difference between High Bulk Yarn and Air-Textured Yarn?
  • A: Both add volume to multifilament yarn, but through different mechanisms. ATY creates surface loops by air-jet entanglement — the bulk is primarily a surface texture effect and the yarn diameter increase is moderate. HBY achieves bulk through differential shrinkage — high-shrinkage filaments contract and physically force low-shrinkage filaments to buckle outward, creating a true three-dimensional loft throughout the yarn cross-section. HBY fabrics are therefore warmer, softer, and more voluminous than equivalent ATY fabrics, but ATY has better abrasion resistance for hard-wear applications like upholstery.
  • Q: Does High Bulk Yarn lose its loft after repeated washing?
  • A: No, for properly heat-set HBY. The bulk is created by a permanent differential shrinkage that has already occurred before the yarn leaves our factory. Subsequent exposure to temperatures below the original heat-setting temperature (typically 160–200 °C for PET) will not cause further shrinkage or bulk loss. Fabrics made from our HBY pass ISO 5077 dimensional stability testing at 60 °C wash without measurable bulk reduction after 20 wash cycles.
  • Q: Can I dye High Bulk Yarn after receiving it?
  • A: Yes. Raw-white HBY can be piece-dyed or yarn-dyed using standard disperse dyeing conditions for polyester (130 °C, HT dyeing machine). The key consideration is liquor ratio — bulked yarn absorbs more liquor than flat yarn at the same denier, so your dyehouse should adjust liquor ratio upward (typically 1:15 to 1:20 vs. standard 1:10) to ensure even dye penetration through the bulked filament matrix. We can provide dyeing recommendations with each shipment.
  • Q: Is BCF carpet yarn the same as High Bulk Yarn?
  • A: BCF (Bulked Continuous Filament) is the carpet industry's specific term for HBY produced in coarse deniers (600D–2200D) using a dedicated BCF spinning and bulking line. The bulking mechanism is the same — differential shrinkage followed by hot-air or steam relaxation in a stuffer box — but BCF lines are optimized for the high throughput and heavy denier ranges required for carpet pile. GC FIBER's HBY production covers the finer denier range (100D–1200D) for apparel, home textiles, and technical applications; we can refer heavy-denier BCF requirements to our partner facilities.
  • Q: What does "bulk level" mean in practice, and how is it measured?
  • A: Bulk level is typically expressed as the percentage increase in yarn volume (or diameter) after relaxation versus the pre-bulk flat yarn reference, measured under a standard low tension. A practical in-lab method is the boiling-water skein bulk test: a fixed-weight skein is measured before and after 30-minute boiling-water relaxation, and the length change is expressed as crimp contraction (%). We report bulk level on our COA and can supply reference skeins for your lab to replicate the measurement independently.
About
GC FIBER
GC FIBER has been a special textile factory in China since 2006 years. We are devoted to researching, developing, producing, and selling special and functional eco-friendly textile products.
Our products include Biodegradable Yarn, Low Melting Yarn, ECDP Yarn, Anti Static Yarn, HDPE Yarn, Bio-component Yarn, and Polyester Filament Yarn.
We are always interested in cooperating with our guests to develop new material.
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