About Spun-Lace Nonwoven

• The aged practice for consolidating a web is mechanical bonding process, and this process entangles the fibers to provide better strength to the web. Under mechanical bonding, there is several ways, but out of them, one of most broadly used method is spun-lacing or hydro-entanglement method.
• There are several diverse specific terms, which are used for Spunlace nonwoven as jet-entangled, water entangled, hydro-entangled or hydraulically needled. However, the term, Spunlace, is most popular in the nonwoven industry.
• The Spunlace process can be defined as:

The Spunlace process is a nonwovens manufacturing system that employs jets of water to entangle fibers and thereby provide fabric integrity.

• After the production of Spunlace fabric, it can be further undergone to finishing process according to the customers need. The main finishing done are mainly dying or printing. It can also be treated with binders to permit for wash sustainability. In some special cases, fire retardants can be applied to Spunlace fabric to resist burning. Further antimicrobial agents can treat the Spunlace fabric to enhance resistance against microorganisms.

Special parameter of the Spunlace nonwoven line:

• Fibre:

In general, fibres with low bending modulus entangle more easily than fibres with high bending modulus. The fibre length is directly proportion to the tie point or entangle areas & inversely proportional to the fabric strength. Therefore, compromise is done for the fibre length. It is seen that 1.8-2.4 cm length of fibre gives best result.

• Web forming method:

The method used to produce the Spunlace nonwoven web are dry-process (card, air-laid) & recently incorporated wet-laid.The main property, which is very much desired in the web, is the isotropic character of the fibre.

• Water jet:
• The diameter of the holes are range normally from 0.08 to 0.25, but the maximum cases the hole size is either 0.12 or 0.18.
• Density of jets: 10 – 30 jets/cm
• Jet diameter: 80 – 800 mm
• Pressure inside the jet manifold: 25-60 MPa
• Velocity of water jet: 10 – 350 m/sec

• Water:

It is expected that the water used for bonding should be neutral pH, contains almost no particulate matter, is low in metallic ions such s Ca, contains bacteria or other microorganisms.

Process Description

The steps characteristic for producing Spunlace nonwoven fabric include:

• The web which is formed usually by means of air-laid or wet-laid process is initially compressed and then pre-wetted to remove air pockets and then only water-needled. The water pressure usually increases from the first to the last injectors. Generally, there is a thumb rule for pressure, and it is as high as 2200 psi, used to direct the water jets on top of the web. This pressure is more than enough for most of nonwoven fibers, even though higher pressures are also being used in some specialized end use.

• The high-pressure jet of water does the entanglement of the fibres in the web. The jets tire out most of the kinetic energy
• Primarily in rearranging fibers inside the web, and
• Secondly, during bounce back against the substrates, dissipating energy to the fibers.

• A vacuum inside the roll take out used water from the product, which put a stop to flooding of the product and reduction in the effectiveness of the jets to move the fibers & cause entanglement.

• Generally, hydro-entanglement is functional on both sides in a stepwise approach. Now the first entanglement roll  active on the first side a number of times in order to impart to the web the desired amount of bonding and strength. The web then passes over a second entanglement roll in an overturn direction in order to treat and, thereby, consolidate the other side of the fabric.

• The fabric is then passed through a dewatering machine where surplus water is detached and the fabric is dried.

Characteristics of Spunlace fabrics are:

• Excellent cover,
• Excellent lint free product
• Excellent process-ability
• Excellent strength to weight ratio
• Good Drape-ability,
• High density,
• High Elongation-to-break,
• Moderate Porosity
• Stability to heat and chemicals
• Textile like fabric feel
• Very even surface
• Very good absorbency
• Very good bulkiness
• Very good burst strengths,
• Durable fabrics
• Printability
• Uniformity,

Raw materials

Application of spun-lace nonwoven fabrics:

Spun-laced fabrics have a broad use in a variety of applications due to comparatively high absorption abilities and absence of a binder in the fabric allowing sterilization of the fabric at high temperatures.

Some of the application areas are:

• Wipes:
• Baby Wipes,
• Household Wipes,
• Industrial Wipes,
• Kitchen wipes
• Facial wipes
• Consumer pre-moistened wipes
• Cosmetic Cotton pads,
• Hospital use:
• Surgical gowns,
• Drapes,
• Operation cover sheets

Comparison of Spunlace bonding with other mechanical bonding