What is the difference between spunbond and meltblown?

Spunbond vs. Meltblown: The Core Difference at a Glance

Spunbond nonwoven fabric is made by extruding continuous filaments and bonding them thermally or chemically, resulting in a strong, durable, and breathable fabric. Meltblown nonwoven is made by blowing molten polymer through fine nozzles with high-velocity hot air, creating ultra-fine microfibers (as small as 1–5 microns) with exceptional filtration properties. The two are fundamentally different in fiber diameter, manufacturing process, mechanical strength, and application areas.

In short: spunbond = strength & structure; meltblown = filtration & barrier. Understanding this distinction is essential for selecting the right material in medical, hygiene, industrial, and protective applications.

Manufacturing Process: How Each Fabric Is Made

Spunbond Process

In the spunbond process, thermoplastic polymers (typically polypropylene) are melted and extruded through a spinneret to form continuous filaments. These filaments are then:

1. Drawn and attenuated by high-speed air jets
2. Randomly laid onto a moving conveyor belt to form a web
3. Bonded together via heat calendering, thermal bonding, or chemical bonding

The resulting fibers typically range from 10 to 35 microns in diameter, producing a fabric with high tensile strength and good dimensional stability.

Meltblown Process

In the meltblown process, the molten polymer is extruded through a die with hundreds of tiny nozzles. Simultaneously, extremely high-velocity hot air streams impinge on the molten polymer streams, causing them to attenuate and solidify into very fine fibers before they land on a collector screen.

Meltblown fibers typically measure 1 to 5 microns in diameter — roughly 5 to 10 times finer than spunbond fibers. This ultra-fine structure is what gives meltblown its outstanding filtration efficiency.

Key Differences: Spunbond vs. Meltblown Side by Side

Performance Characteristics Explained

Strength and Durability

Spunbond fabrics are far stronger. The continuous filament structure gives them high tensile and tear strength, making them suitable as outer cover layers, geotextiles, agricultural fabrics, and packaging materials. A typical spunbond fabric at 25 gsm can withstand tensile forces exceeding 150 N/5cm in the machine direction.

Meltblown fabrics, due to their ultra-fine, randomly distributed fibers with weaker inter-fiber bonding, are fragile and cannot withstand significant mechanical stress on their own. They are almost always laminated with spunbond layers for structural support.

Filtration and Barrier Efficiency

Meltblown is the gold standard for filtration. Its dense web of microfibers creates a tortuous path for airborne particles, bacteria, and liquid droplets. Electret-charged meltblown fabric, used in N95 respirators, can filter more than 95% of airborne particles ≥0.3 microns.

Spunbond alone cannot achieve this level of filtration due to its larger fiber diameters and more open structure.

Softness and Comfort

Meltblown fabrics are extremely soft due to their fine fiber structure. However, for skin-contact applications requiring both softness and durability — such as baby diapers, feminine care products, and medical drapes — neither material alone is ideal.

This is where Hot Air-Through Nonwoven Fabric offers a compelling alternative. By using hot air bonding instead of thermal calendering, this fabric achieves a loftier, softer, and more three-dimensional fiber structure, combining comfort with functional performance in hygiene and medical applications.

SMS and SMMS: When Spunbond Meets Meltblown

Because neither fabric is perfect alone, the industry widely uses composite laminate structures that combine both:

• SMS (Spunbond–Meltblown–Spunbond): A three-layer composite providing strength on the outside layers and filtration in the middle.
• SMMS (Spunbond–Meltblown–Meltblown–Spunbond): Adds an extra meltblown layer for higher barrier and filtration performance.
• SMMMS: Used in high-barrier surgical gowns and drapes requiring maximum protection.

SMS at 35–70 gsm is the most common material used for surgical masks, disposable gowns, and protective coveralls. The outer spunbond layers resist abrasion and provide shape, while the meltblown core provides the filtration function.

Application Areas: Where Each Material Excels

Spunbond Applications

• Diaper top sheets and back sheets
• Agricultural ground cover and crop protection
• Geotextiles for road and civil engineering
• Reusable shopping bags
• Medical drape outer layers
• Furniture and mattress covers

Meltblown Applications

• Filtration media for face masks (N95, KN95, surgical)
• HVAC and industrial air filtration
• Oil absorption and environmental spill cleanup
• Liquid filtration cartridges
• Battery separators
• Thermal insulation layers

Cost and Production Considerations

Spunbond production lines are generally more efficient and cost-effective due to their higher output rates and lower sensitivity to process variations. A standard spunbond line can produce up to 400 kg/hour per meter of working width.

Meltblown production is significantly more expensive. The process requires precise temperature control, die design, and air management. Output rates are lower — typically 50–100 kg/hour per meter — and the equipment cost is substantially higher. This is why meltblown fabric costs 3 to 10 times more per kilogram than spunbond fabric of the same polymer.

This cost difference is a major reason why manufacturers seek to optimize the meltblown layer thickness in SMS composites: using just enough meltblown to achieve the required filtration rating, backed by cost-effective spunbond layers.

How to Choose Between Spunbond and Meltblown

When deciding between the two materials — or determining whether a composite or alternative nonwoven is more appropriate — consider these practical criteria:

• Need high filtration or liquid barrier? → Choose meltblown or SMS composite
• Need durability and tear resistance? → Choose spunbond
• Need soft, skin-contact comfort for hygiene products? → Consider hot air-through nonwoven bonded fabrics
• Need both strength and filtration? → Use SMS or SMMS composite
• Cost is primary concern? → Spunbond is significantly more economical

FAQ

Q1: Can meltblown fabric be used alone without spunbond?

Technically yes, but it is rarely practical. Meltblown fabric is fragile and tears easily under mechanical stress. In almost all real-world applications, it is sandwiched between spunbond layers to form an SMS composite that provides both structural integrity and filtration.

Q2: Is spunbond fabric safe for direct skin contact?

Yes. Polypropylene spunbond is widely used in hygiene products like diapers and sanitary pads as the top sheet layer in direct skin contact. It is hypoallergenic, non-toxic, and non-irritating when produced to hygiene-grade standards.

Q3: What is the filtration efficiency of meltblown fabric?

Standard meltblown can achieve filtration efficiency of 50–80% for 0.3-micron particles. When electrostatically charged (electret treatment), efficiency rises to 95%+, qualifying for N95-grade masks. Efficiency degrades over time with moisture and use.

Q4: How does hot air-through nonwoven differ from spunbond?

Hot air-through nonwoven uses hot air bonding instead of calendar roll heat bonding, creating a bulkier, softer, and more three-dimensional structure. It provides superior softness and fluid management, making it preferred for hygiene and medical product cover layers compared to standard spunbond.

Q5: Which nonwoven is used in N95 masks?

N95 respirators typically use an SMS or SMMS structure. The critical filtration layer is the electrostatically charged meltblown middle layer, which captures ≥95% of airborne particles ≥0.3 microns. The outer and inner layers are spunbond for comfort and structural support.

Q6: Are spunbond and meltblown both made from polypropylene?

Polypropylene (PP) is the most common raw material for both, but other polymers like polyester (PET), polyethylene (PE), and polyamide (PA) are also used depending on the performance requirements such as heat resistance, chemical resistance, or biodegradability.