Method of extruding multi-component liquid filaments

An apparatus for extruding multiple types of liquid materials into multi-component filaments. A pair of outer manifold elements sandwich an intermediate manifold element. Respective channels are formed between opposing sides of the outer manifold elements and the respective opposite sides of the intermediate manifold element. These recesses form channels which diverge or widen away from associated inlets at the top of the manifold assembly. A die tip is coupled to the manifold assembly at a lower side and communicates with the outlets of the channels. The die tip includes a combining member for producing a desired multi-component filament configuration.

FIELD OF THE INVENTION

The present invention generally relates to apparatus for extruding thermoplastic filaments and, more particularly, apparatus for spunbonding multi-component filaments.

BACKGROUND OF THE INVENTION

Spunbonding or other techniques for extruding fine diameter filaments find many different applications in various industries including, for example, in nonwoven material manufacturing. This technology generally involves extruding a thermoplastic material from multiple rows of discharge outlets extending along the lower surface of an elongate spinneret. Spunbonded materials are used in such products as diapers, surgical gowns, carpet backings, filters and many other consumer and industrial products. The machines for spunbonding such materials can be very large with the filament discharge outlets numbering in the thousands.

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 or extrusion to produce filaments of the desired cross-sectional configuration.

One problem associated with multi-component extrusion 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 extrusion apparatus.

For these reasons, it would be desirable to provide multi-component extrusion 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.

SUMMARY OF THE INVENTION

The present invention therefore provides an apparatus for extruding multiple types of liquid materials into multi-component filaments including a unique manifold structure coupled with a multi-component die tip. Generally, the invention pertains to melt spinning apparatus, such as spunbonding and meltblowing apparatus. The preferred or illustrative embodiment specifically disclosed herein relates to a spunbonding apparatus. In one general aspect, the apparatus comprises an intermediate manifold element having first and second opposite surfaces. First and second outer manifold elements respectively couple to the first and second opposite surfaces and have respective opposed surfaces. Each opposed surface respectively abuts one of the first and second opposite surfaces of the intermediate manifold element. A first channel is formed between the opposed surface of the first outer manifold element and the first opposite surface of the intermediate manifold element. A second channel is formed between the opposed surface of the second outer manifold element and the second opposite surface of the intermediate manifold element. The first and second-channels have inlets for respectively receiving the first and second liquids and outlets for respectively discharging the first and second liquids. These inlets and outlets may be formed in the intermediate manifold element, in the outer manifold elements, or between the intermediate manifold element and the respective outer manifold elements. The first and second channels may comprise recesses formed in the first and second opposite surfaces of the intermediate manifold element, or recesses formed in the opposed surfaces of the first and second outer manifold elements, or any combination thereof which forms the necessary channels.

A die tip is coupled adjacent the manifold elements. The die tip includes a plurality of multi-component filaments discharge outlets and at least first and second liquid distribution passages. The first and second liquid distribution passages are adapted to receive the first and second liquids respectively from the outlets of the first and second channels. A liquid combining member communicates between the first and second liquid distribution passages and the filament discharge outlets. The liquid combining member is configured to receive the first and second liquids and combine the first and second liquids into respective multi-component filaments.

In a more specific preferred embodiment of the manifold structure, the first and second outer manifold elements have respective recesses and, more preferably, a plurality of recesses on their respective opposed surface. The intermediate manifold element is coupled between the respective opposed surfaces of the first and second outer manifold elements. The recesses on the respective first and second opposite surfaces of the intermediate manifold element communicate, and preferably align with corresponding recesses on the opposed surfaces of the first and second outer manifold elements. The communicating recesses together form at least first and second channels and, preferably, first and second pluralities of channels each having a liquid inlet and a liquid outlet communicating with the die tip on the opposite sides of the intermediate manifold element.

Various advantages, objectives, and features of the invention will become more readily apparent to those of ordinary skill in the art upon review of the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIGS. 1 and 2, a spunbonding apparatus10constructed in accordance with the inventive principles includes first and second outer manifold elements12,14. An intermediate manifold element16is coupled between outer manifold elements12,14in sandwiching relation. A die tip or spin pack assembly18is coupled to outer manifold elements12,14and intermediate manifold element16by fastener assemblies20. Threaded fasteners (not shown) are inserted through holes22,24in the respective outer manifold elements12,14and thread into internally threaded holes26contained in intermediate manifold element16. Although only holes26are shown, it will be appreciated that the opposite side of manifold element16has similar threaded holes. A liquid supply block30is mounted to an upper surface of intermediate manifold element16and includes a plurality of pumps32a,32bfor respectively pumping first and second types of liquid, such as thermoplastic material. The first type of liquid is pumped into each inlet40and the second type of liquid is pumped into each inlet42in the top of intermediate manifold element16. Although three sets of pumps32a,32bare shown in this preferred embodiment, it will be understood that a greater or fewer number of pump sets32a,32bmay be provided instead. Alternatively, other manners of supplying manifolds12,14,16with multiple types of liquids may be employed instead. In addition, the side-by-side manifold concepts of this invention may be employed to form filaments from more than two component liquids.

As shown best inFIG. 2, outer manifold elements12,14include respective opposed notches44,-46communicating with liquid supply inlets40,42. Corresponding notches48,50are formed in opposite side surfaces of intermediate manifold element16such that respective channels52,54are formed for receiving the component liquids from inlets40,42. Recesses56,58are formed in opposed sides of outer manifold elements12,14and align with corresponding recesses60,62formed on opposite sides of intermediate manifold element16. These aligned recesses form respective channels64,66which communicate at respective upper ends thereof with channels52,54and which further include discharge outlets70,72at lower ends thereof. It will be appreciated that channels64,66may instead be formed by recesses formed only on intermediate manifold element16or only on outer manifold elements12,14and, in that case, the abutting manifold element will serve as a cover plate. As appreciated fromFIG. 1, each channel64,66formed respectively between recesses56,60and recesses58,62diverges or widens in a lengthwise direction relative to the lengthwise extents of manifold elements12,14,16from inlet channels52,54to outlets70,72.

Referring toFIGS. 2 and 3, die tip18more specifically comprises a conventional spin pack assembly. The details of assembly18are more specifically disclosed in U.S. Pat. No. 5,562,930, the disclosure of which is hereby incorporated by reference in its entirety. Generally, die tip18comprises a top plate80, a screen support plate82, a metering plate84, an etched distributor plate86and a spinneret plate88held together by fasteners90. The respective first and second liquids enter slots100,102formed on the upper surface of top plate80from outlets70,72of channels64,66. The first and second liquids then enter a series of passages104and a series of passages106communicating with respective cavities108,110. The two liquids then respectively travel through filters112,114and enter liquid component slots116,118. Slot116communicates with holes120and slot118communicates with holes122. One of several slots124is shown inFIGS. 2 and 3for receiving one of the two component liquids from hole120or hole122. Although not shown in the drawings, another alternating series of slots is provided for the other component liquid. Apertures128are provided for the first component liquid and apertures130are provided for the second component liquid in metering plate84.

The etched distributor plate86receives the mutually separated component liquids and combines these liquids in the desired manner as the liquids reach the discharge passages140. The multi-component filaments are then discharged through outlets142. Holes160or162located along the length of each outer manifold element12,14receive heater rods for heating the two liquids and the process air to an appropriate application temperature. Temperature sensing devices (not shown), such as RTD's or thermocouples are also placed in manifold elements12,14to control the temperature. A more complete description and operation of the die tip or spin pack18may be found in the above incorporated U.S. Pat. No. 5,562,930. In addition, it will be appreciated that many other die tip assemblies may be used for spunbonding applications or other multi-component filaments extrusion applications and that this disclosure is merely illustrative of one preferred configuration.

While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments has been described in some detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The various features of the invention may be used alone or in numerous combinations depending on the needs and preferences of the user. This has been a description of the present invention, along with the preferred methods of practicing the present invention as currently known.