By [email protected] — Charting the depths of expertise
Microfiber cleanroom wipes are made by splitting coarse composite fibers into many fine ones. The most common technique combines the sea-island method (dissolving heterogeneous components) with low-energy mechanical splitting.
In contrast, standard and sub-microfiber cleanroom wipes undergo surface etching (alkali reduction), a different process targeting polyester fibers. This method slightly etches the fiber surface with a low-concentration caustic soda to improve softness and moisture absorption, rather than dissolving a component. It acts on single-component polyester, slightly reducing fiber diameter (by 10%-15%) without creating independent microfilaments.
Common Splitting Methods
The table below compares common splitting methods. For cleanroom wipes, the most relevant are the Sea-Island, Synergistic, and Surface Etching methods.
| Process Category | Specific Method | Core Mechanism | Applicable Materials/Combinations | Advantages | Disadvantages & Challenges | Impact on Fiber Integrity | Typical Applications |
|---|---|---|---|---|---|---|---|
| Chemical Splitting (Composite) | Sea-Island (Heterogeneous Dissolving) | Selectively dissolves the "sea" component with a solvent, leveraging chemical differences to release the "island" fibers. | Heterogeneous Composite: PET/Nylon (island) + PE/Soluble Copolyester (sea). The most common method. | Efficient splitting, uniform fineness, stable performance; ideal for mass production. | Higher cost (two materials); environmental/safety concerns with organic solvents (e.g., toluene); high COD wastewater. | Excellent. Minimal damage to "island" fibers with proper process control. | High-end suede, microfiber cleanroom wipes, precision optical wipes, performance filters, artificial blood vessels. |
| Chemical Splitting (Composite) | Sea-Island (Homogeneous Dissolving) | Uses polymers of the same type but with different properties (e.g., high/low melt polyester) and removes the "sea" component via heat or a selective solvent. | Homogeneous Composite: Regular PET (island) + Low-melt/Soluble Modified PET (sea); Regular Nylon + Modified Nylon. | Achieves single-component splitting (e.g., "100% polyester"), avoiding compatibility and dyeing issues. | More complex process and higher costs; requires precise polymer rheology matching; difficult to control uniformity. | Excellent. Yields pure, single-component ultra-fine fibers. | High-simulation silk, ultra-soft fleece, special functional filters, premium artificial leather. |
| Chemical Treatment (Single Fiber) | Surface Etching (Alkali Reduction) | Uses a low-concentration alkali (NaOH) for layer-by-layer hydrolytic corrosion to make the entire fiber thinner. Not true splitting, but surface modification. | Polyester (ineffective on nylon). Often used as a finishing process. | Simple process; directly treats fabrics for a softer, silk-like feel and improved moisture absorption. | Inherently damaging, causing significant strength loss; high chemical use and environmental impact. | Poor. Sacrifices fiber integrity for hand-feel; significant strength loss. | "Silk-finishing" for polyester apparel; auxiliary treatment for a peach-skin effect. |
| Physical Splitting (Composite) | Segmented Pie Hydroentangling | High-pressure micro-water jets strike a web of segmented-pie fibers, tearing them along weak interfaces and entangling them into a fabric simultaneously. | Segmented Pie Composite: PET/PA composite fibers. Different from sea-island fibers. | Eco-friendly (no chemicals); can split and form a nonwoven web in one step. | High equipment investment and energy use; for specific fiber structures only; requires high-quality water systems. | Good. Purely physical action causes minimal damage to the fiber itself. | Medical materials (gowns, dressings), high-end wet wipes, synthetic leather bases, automotive headliners. |
| Physical Treatment (Single Fiber) | Mechanical Abrasion (Sanding) | Grinding rollers or sandpaper abrade the fabric surface at high speed, causing surface fibers to tear and fibrillate, creating a fine, short pile. | Various staple or filament fabrics (polyester, nylon, cotton, etc.). | Imparts a soft, full hand-feel and a unique peach-skin appearance; mature technology. | Incomplete splitting (surface fibrillation only); damages fiber strength, creates lint/dust, reduces abrasion resistance. | Poor. Causes clear mechanical tearing and damage to fibers. | Peach-skin fabrics, corduroy, thermal underwear, and brushed/sanded finishes for home textiles. |
| Synergistic Splitting (Composite) | Chemical Pre-treatment + Low-Energy Mechanical Splitting | Two-step process: 1. Chemical Weakening: A mild chemical agent weakens the bond between fiber components. 2. Mechanical Separation: Low-energy forces (e.g., water jets in a dyeing machine, roller friction) fully separate the weakened interfaces. | Woven or knitted PET/Nylon composite fabrics (sea-island or segmented pie). | Combines high efficiency of chemical methods with the low damage of physical ones; less chemical/energy use; superior overall performance (strength, feel). | Longer, more complex process control; requires precise coordination of chemical and physical parameters. | Good. Optimized processes can minimize fiber damage and maximize performance. | Demanding high-end products: premium automotive interiors (Alcantara-like), microfiber cleanroom wipes, performance sportswear. |
Nonwoven Cleanroom Wipes Do Not Undergo Splitting
The following table clarifies that the hydroentangling of nonwoven wipes is for entanglement, not splitting.
| Characteristic | Sea-Island Composite Fiber | Segmented Pie Composite Fiber | Nonwoven Cleanroom Wipe |
|---|---|---|---|
| Core Concept | Solvent Dissolving Splitting | Physical Impact Splitting | Physical Entanglement into Fabric |
| Raw Material | 100% Chemical Fiber (composite filament) | 100% Chemical Fiber (composite filament) | Natural + Chemical Fiber (Cellulose + Polyester staple) |
| Fiber Morphology | "Islands" encased in a "sea"; one coarse fiber holds hundreds of ultra-fine "island" filaments. | "Petals" joined together; one fiber consists of 8, 16, or 32 wedge-shaped "segments." | A physical mix of two separate, short fibers. |
| Core Process | 1. Composite Spinning 2. Chemical Splitting (dissolving the "sea") | 1. Composite Spinning 2. Physical Splitting (tearing segments with water jets) | 1. Web Blending 2. Physical Consolidation (entangling fibers with water jets) |
| Requires "Splitting"? | Yes (Chemical) | Yes (Physical) | No, this concept does not apply. |
| Fiber Fineness | Ultra-fine | Very fine | Coarse (fibers are not made finer) |
| Advantages | Top-tier performance: finest, softest fibers Maximum surface area, strongest adsorption | Eco-friendly process (no chemical pollution) Efficient (can split and form web in one step) | Fast liquid absorption (from cellulose) Low cost Maintains some wet strength |
| Disadvantages | Highest cost, complex process Environmental impact (solvents/wastewater) | Not as fine as sea-island fibers High equipment investment and energy use | Sheds particles (from staple fibers) Lowest cleanliness, poor durability |
Potential Problems from Improper Splitting
Incomplete Separation: Fibers remaining stuck together reduces the wipe's softness and loft, impairing cleaning performance. Fiber Damage: Excessive damage (breakage, deformation) during splitting reduces strength and durability and can cause shedding. Uneven Distribution: Non-uniform fiber distribution on the surface, with variations in thickness and density, prevents consistent contaminant removal. Reduced Strength: A significant loss of fiber strength makes the wipe prone to tearing during use, shortening its lifespan and creating contamination.
