Meltblowing technology is used in many different applications and industries including, for example, in adhesive dispensing and nonwoven material manufacturing. This technology generally involves extruding fine diameter filaments of thermoplastic material from a row of discharge outlets and impinging the extruded filaments with pressurized air immediately upon discharge. The pressurized air may be discharged as continuous sheets or curtains on opposite sides of the discharged filaments or as individual streams associated with the filament discharge outlets. The pressurized air is often referred to as process or primary air. This air draws down or attenuates the filament diameter while the filaments are airborne. The filaments are then randomly dispersed onto a substrate or a carrier.
For certain applications, it is desirable to utilize multiple types of thermoplastic liquid materials to form individual cross-sectional portions of each filament. Often, these multi-component filaments comprise two components and, therefore, are referred to as bicomponent filaments. For example, when manufacturing nonwoven materials for use in the garment industry, it may be desirable to produce bicomponent filaments having a sheath-core construction. The sheath may be formed from a softer material which is comfortable to the skin of an individual and the core may be formed from a stronger, but perhaps less comfortable material having greater tensile strength to provide durability to the garment. Another important consideration involves cost of the material. For example, a core of inexpensive material may be combined with a sheath of more expensive material. For example, the core may be formed from polypropylene or nylon and the sheath may be formed from a polyester or co-polyester. Many other multi-component fiber configurations exist, including side-by-side, tipped, and microdenier configurations, each having its own special applications. Various material properties can be controlled using one or more of the component liquids. These include, as examples, thermal, chemical, electrical, optical, fragrance, and anti-microbial properties. Likewise, many types of die tips exist for combining the multiple liquid components just prior to discharge to produce filaments of the desired cross-sectional configuration.
One problem associated with multi-component meltblowing apparatus involves the cost and complexity of the manifolds used to transmit each of the separate component liquids to the multi-component die tip. Typical manifolds must be machined with many different passages leading to the die tip to ensure that the proper flow of each component liquid reaches the die tip under the proper pressure and temperature conditions. These manifolds are therefore relatively complex and expensive components of the multi-component meltblowing apparatus.
For these reasons, it would be desirable to provide a meltblowing apparatus having a manifold system which may be easily manufactured and yet fulfils the requirement of effectively transmitting each of the component liquids to the multi-component die tip.