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Sea-Island (Islands-in-the-Sea) Yarn

-- Steady & Reliable Manufacturer --

What Is Sea-Island Yarn

Sea-island yarn, also called islands-in-the-sea yarn or matrix-fibril yarn, is a bicomponent filament made of two polymers spun together in a single cross-section. One polymer forms the continuous "sea" phase, while the other polymer is dispersed inside it as dozens or even hundreds of tiny "island" filaments. Once the sea component is dissolved away in a later finishing step, what remains is a bundle of ultra-fine microfilaments, often well below 0.1 dtex per filament.

This structure is one of the most effective ways to produce true microfiber without relying on mechanical splitting alone. At GCFYARN, we run this on dedicated composite spinning lines with precise control over island count, island distribution, and sea/island ratio, so the fiber fineness and hand-feel can be tuned to match a specific downstream fabric.

Typical Polymer Combinations

The most common pairing is polyester (PET) islands inside a co-polyester or alkali-soluble PET "sea," which is removed with a hot alkali (NaOH) treatment during dyeing and finishing. Nylon (PA6) islands in a soluble sea are also used where extra softness and dye affinity are required. We can advise on which combination fits your finishing line and target fabric hand.

Why It Matters for Your Production

Because the island count and cross-section are fixed at the spinning stage, fabric mills get consistent, repeatable fineness batch after batch, which matters a lot when you are running large volumes of suede or artificial leather base fabric and cannot afford lot-to-lot variation.

Related products

Services

We insist on timely and fast service, the implementation of all-weather tracking service, adequate spare parts inventory, so that our customers have no worries.

  • Wide Variety

    Wide Variety

    Design & Manufacturing. In stock or customizable.

  • Sample and Catalog

    Sample & Catalog

    OEM/ODM available.

  • Production and Delivery

    Production & Delivery

    Flexible production and delivery policies

  • Business Experience

    Business

    Over 19 years of experience in eco-friendly textile products

Specification

Fiber CompositionSea: co-PET / alkali-soluble PET or PA6; Island: PET or PA6 (customizable pairing)
Island Count16 / 32 / 37 / 52 / 64 / 108 islands per filament (custom counts available)
Sea/Island RatioTypically 30:70 to 50:50 by weight, adjustable on request
Total Denier Range75D – 300D (custom deniers on request)
Fineness After Sea Removal0.01 – 0.10 dtex per single filament
Filament Count36F / 48F / 72F / 96F / 144F (custom filament counts available)
Cross-SectionRound islands dispersed in a round or near-round sea matrix
Tenacity2.8 – 4.0 cN/dtex (before alkali reduction)
Elongation at Break25% – 45%
Boiling Water Shrinkage≤ 8%
Alkali Weight Loss (Sea Removal)30% – 45%, depending on sea ratio and treatment time
ColorRaw white / dope-dyed / customer-specified shade
PackageCone (1.5 – 2.5 kg net), carton packing, tube diameter on request
MOQ500 kg per specification for standard colors; contact us for trial orders

Application

Sea-island yarn is the base material for products that depend on an extremely fine, soft, and high-surface-area fiber structure. Once the sea component is removed, the remaining microfilament bundle behaves very differently from a standard filament yarn, which is why it is used in the following areas:

  • Microfiber synthetic leather: base cloth for shoe leather, bag leather, upholstery leather, and automotive interior leather.
  • Artificial suede: nap-raised suede fabric for garments, sofas, and car seat covers with a soft, peach-skin touch.
  • High-performance cleaning cloths: glass cleaning cloths, lens cloths, and industrial wipes that rely on the huge fiber surface area to trap dust and oil.
  • Filtration media: fine-particle air and liquid filters where pore size needs to be controlled at the micron level.
  • Sportswear and innerwear: ultra-soft, lightweight knit fabrics where hand-feel and moisture management are priorities.

Advantage

  • True microfiber fineness: fineness below 0.1 dtex is difficult to reach with direct spinning, but achievable through the sea-island process.
  • Consistent island distribution: our spinneret design and process control keep island count and placement stable across production lots.
  • Excellent softness and drape: the finer the individual filament, the softer and more fluid the resulting fabric feels.
  • Higher dye uptake and color depth: the larger surface area after sea removal absorbs more dye, giving deeper, more even shades.
  • Customizable to your finishing process: island count, denier, and sea ratio can be adjusted so the alkali reduction step matches your existing dyeing line.
  • Stable factory-direct supply: as the manufacturer, GC FIBER controls spinning parameters end to end, so repeat orders keep the same fineness and hand-feel.

Payment Terms

We accept T/T (30% deposit, balance before shipment or against copy of B/L), L/C at sight for larger volume orders, and Western Union / PayPal for small sample orders. Pricing is quoted in USD by default; other currencies can be discussed for regular buyers.

Shipping & Delivery

Standard trade terms are FOB Shanghai / Ningbo, with CIF and DDP also available on request. Sample orders usually go out by express courier (DHL, FedEx, UPS) within 3-5 working days. Bulk orders are shipped by sea freight (FCL/LCL) with a typical production lead time of 15-25 days after deposit and artwork/color confirmation, or by air freight when the schedule is tight.

  • Q: What exactly is sea-island yarn used for?
  • A: It is mainly used as the raw fiber for microfiber synthetic leather, artificial suede, and premium cleaning cloths, since removing the sea component leaves an ultra-fine microfilament bundle.
  • Q: What is the difference between sea-island yarn and a regular bicomponent yarn?
  • A: A regular bicomponent yarn usually keeps both components in the final fabric, while sea-island yarn is designed so the sea component is dissolved away later, leaving only the fine island filaments behind.
  • Q: Can the island count and denier be customized?
  • A: Yes, island count, denier, filament count, and the sea/island ratio can all be adjusted to match the fineness and hand-feel you need for your fabric.
  • Q: Do you provide samples before a bulk order?
  • A: Yes, small quantity samples are available for testing your alkali reduction and dyeing process before committing to a bulk order.
  • Q: What is the minimum order quantity?
  • A: Standard MOQ is 500 kg per specification; please contact our sales team if you need a smaller trial batch.
  • Q: How much weight is lost during the alkali reduction step?
  • A: Weight loss is typically 30% to 45%, depending on the sea/island ratio you choose and your alkali treatment time and concentration.
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.

WHY WE ARE SO TRUSTED

We have got a high reputation in both domestic and overseas markets.

Professional

We will communicate with customers professionally, listen to their opinions and give useful suggestions, and spend time and energy to solve every problem, no matter all the problems you encounter.

Quality

We have strict quality control requirements and the advanced testing equipment in the industry. Every process has professionals to conduct inspections to ensure product quality.

Cost

We have a number of production lines, a number of production machines, comprehensively improve product quality and production efficiency.

Design and R&D

We devote to research, development, production and sales of special and functional eco-friendly textile product.

Diversity

Our product includes PBS biodegradable product, recycled easy dyeing cationic yarn, PLA yarn, Low melting yarn, Anti-Static yarn ,PBS fiber, PLA fiber, FR nylon fiber etc.

Capacity

The company has sufficient production capacity and high control over raw material prices, quality and stable supply, which can meet the needs of customers with different procurement volumes.

Service

We insist on timely and fast service, the implementation of all-weather tracking service, adequate spare parts inventory, so that our customers have no worries.

Shipment

We are near Ningbo Port and Shanghai Port, and are very convenient and quick to transport cargo to other national capitals.

Diversified Professional Team

GC FIBER has unique sales, research and development, design, production departments and expertise to provide customers and stakeholders in various industries with specialty, functional and environmentally friendly textiles.

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