WO1996002695A1

WO1996002695A1 - Bicomponent and long fiber product definition for splittable pack

Info

Publication number: WO1996002695A1
Application number: PCT/US1995/008774
Authority: WO
Inventors: Clarke Ii Berdan
Original assignee: Owens Corning
Priority date: 1994-07-18
Filing date: 1995-07-13
Publication date: 1996-02-01
Also published as: JPH10503247A; AU3097095A; CA2194392A1

Abstract

A splittable pack (78) of long fibers (16) is disclosed by shaping and attaching long fiber (16) wool packs (48) in layered relationship. The resulting wool pack (78) is generally separable along a plane (83) defined between the binderless wool packs (48) for ease of installation around impediments.

Description

BICOMPONENT AND LONG FIBER PRODUCT DEFINITION FOR SPLITTABLE PACK

TECHNICAL FIELD This invention relates to wool materials of mineral fibers and, more specifically, to insulation products of long glass fibers. The invention also pertains to the manufacture of insulation products made of long wool fibers.

BACKGROUND ART Small diameter glass fibers are useful in a variety of applications including acoustical or thermal insulation materials. When these small diameter glass fibers are properly assembled into a lattice or web, commonly called a wool pack, glass fibers which individually lack strength or stiffiiess can be formed into a product which is quite strong. The glass fiber insulation which is produced is lightweight, highly compressible, and resilient. For purposes of this patent specification, in using the terms "glass fibers" and "glass compositions", "glass" is intended to include many of the glassy mineral materials, such as rock, slag, and basalt, as well as traditional glasses.

The common prior art methods for producing glass fiber insulation products involve producing glass fibers from a rotary process. A single molten glass composition is forced through the orifices in the outer wall of a centrifuge or spinner, producing primarily straight glass fibers. The fibers are drawn downward by a blower, and conventional air knife and lapping techniques are typically used to disperse the veil to provide acceptable, generally uniform fiber distribution. The binder required to bond the fibers into a wool product and provide product integrity is sprayed onto the fibers as they are drawn downward. The fibers are then collected and formed into a wool pack. The wool pack is further processed into insulation products by heating in an oven, and mechanically shaping and cutting the wool pack. Once shaped, it is also desirable to highly compress wool packs to reduce shipping costs. Thus, it is also desirable for wool packs to exhibit rapid and reliable recovery from compression when unpacked for use.

Once unpacked, it is desirable for ease of installation that wool packs in certain product applications be separable longitudinally. For example, installers of wool bans used for wall and attic insulation often encounter impediments where wool is to be placed between studs and rafters, such as pipes, conduits, wires, and other building system elements. The conventional practice has been to separate the short fiber batt longitudinally in the field by rending it generally along a plane. The separated portions of the pack are then positioned to straddle the impediment. By their nature, commercial wool packs of short fibers connected by binder have been amenable to such longitudinal separation. Thus, to achieve desirable lattice properties such as generally uniform density, product integrity, and recovery from compression in wool insulating materials of glass fibers, as well as desirable practical features such as longitudinal separability, it has been necessary to use fibers that are relatively short.

Long fibers are not used in wool products of glass fibers because of their tendency to excessive entanglement, and the formation of ropes and strings. Thus, while long fibers display some fiber-to-fiber entanglement even without binder, the nonuniformity of the resulting wool packs has long made them commercially undesirable. For purposes of this patent specification, in using the terms "short fibers" and "long fibers", the term "short fibers" is intended to include fibers of approximately 25.4 mm (1 inch) and less, and "long fibers" are intended to include fibers longer than approximately 50.8 mm (2 inches). Typically, a wool pack of short fibers produced by rotary fiberizing techniques will include some long fibers which, however, will comprise less than 10% of the wool pack.

Long fibers have different aerodynamic properties, and conventional lapping techniques have failed to eliminate, and rather tend to enhance, formation of ropes and strings in veils of long or semi-continuous fibers. Even when undisturbed, veils of long fibers tend to form ropes and strings as the veil slows in its descent to the collection surface. Despite movement of the collection surface, long glass fibers (as do undisturbed veils of short fibers) tend to pile up into nonuniform packs of fibers, and unmanageable fiber accumulations. These nonuniform packs, characterized in part by roping and string formation, have long prevented significant commercial use of long fibers. The ropes of long fibers produce a commercially undesirable appearance and, more importantly, create deviation from the ideal uniform lattice and reduce the insulating abilities of the glass wool. The ropes, strings, and excessive entanglement of long fibers further inhibit the commercially desirable property of longitudinal separation, making practical installation more difficult.

Short fiber insulation is not without its problems, however. Even short fibers that are straight form only a haphazard lattice, and some of the fibers lie bunched together. As a result, existing glass wool insulating materials continue to have significant nonuniformities in the distribution of fibers within the product.

A further problem with short fiber wools is that the binder used is expensive and has several environmental drawbacks. Many binders include organic compounds, and effluent from the production process must be processed to ameliorate the negative environmental impact of such compounds. In addition, the need for curing binder with an oven consumes additional energy, creating additional environmental cleanup costs. A still further problem with short fiber products arises when the product is compressed. While the binder holds firm at fiber-to-fiber intersections while the glass fibers themselves flex, if the stress upon the fiber increases due to excessive compression, the fiber breaks. Thus, current insulation products are limited in the amount of compression possible while still attaining adequate recovery.

Nonetheless, because long fibers are problematic in nearly all respects, commercial wool insulation products of glass fibers have long used only short straight fibers, despite the various drawbacks of short fibers in lattice non-uniformity, need for binder, and limited compressibility. Accordingly, the need remains for further improvements in wool insulation products to improve wool pack properties, reduce cost, and eliminate environmental concerns.

DISCLOSURE OF INVENTION The present invention satisfies that need by providing methods for further defining the shape of wool packs of long glass fibers, which methods generally maintain lattice uniformity, eliminate the need for binder, and result in a wool pack which displays significant compressibility and recovery desired for commercial products.

In accordance with the present invention, a wool pack of long glass fibers is provided including long fibers of a single glass composition, as well as fibers including two glass compositions which produce a non-linear, bicomponent fiber. Collection of long fibers into a wool pack is achieved by receiving a veil from a rotary fiberizer on a pair of high-speed rotating foraminous drum-like surfaces, separating the gases in the veil from the fibers by suction through the drum surfaces, and conveying the remaining fibers at high speed through a narrow gap between the drums to form a web. The drum surfaces are operated at high speeds to have a surface speed in the range of approximately 50% to 150% of the speed of the veil at the drums. The web is then distributed to form the wool pack. The fibers in the resulting wool pack are generally randomly and uniformly distributed. Alternatively, collection of long fibers into a wool pack may be achieved by receiving a veil produced by a rotary fiberizer on opposing first foraminous conveyor surfaces, removing the gases therefrom, and conveying the remaining fibers on second conveyor surfaces through a passage, while substantially maintaining fiber orientation established by the rotary fiberizer. The fibers in the resulting wool pack are oriented, interrelated in a generally spiral relationship.

The methods for producing these wool packs are set forth in greater detail in co-pending applications, commonly assigned with the present application, U.S. Patent AppUcation Serial No. 08/236,067, filed May 2, 1994, entitled WOOL PACK FORMING PROCESS USING HIGH SPEED ROTATING DRUMS AND LOW FREQUENCY SOUND DISTRIBUTION, by Aschenbeck, and U.S. Patent Application Serial No. 08/239,820, filed May 9, 1994, entitled DIRECT FORMING METHOD OF COLLECTING LONG WOOL FIBERS, by Grant, et al, both incorporated herein by reference. The wool packs of long fibers produced in accordance with either method have a generally uniform distribution of fibers, and roping is generally absent. Such wool packs may be shaped initially by the forming process and packaged in plastic to provide product definition, or alternatively shaped in accordance with the methods disclosed in greater detail below. As used herein, the phrase "wool pack of long fibers" refers to wool packs having a substantial proportion of long fibers, generally 50% or more by number or weight, but may also include wool packs having somewhat smaller percentages (greater than approximately 10%) of long fibers which, nonetheless, demonstrate the behavior of wool packs having higher percentages of long fibers. Wool packs of long glass fibers provided in the present invention present unique problems related to product definition. The long fibers are entangled to a lesser degree than short fibers, and are produced without binder. While initial wool pack shape is provided as outlined above, and can be retained by packaging in film, greater definition in the wool pack for various products is desired. The thicker, binderless mats and wool packs of long fibers in the present invention present problems of product definition not previously fully addressed by the prior art. The present invention seeks to provide shape to wool packs including long fibers, particularly irregular, bicomponent fibers, which tend to form bunches, rather than readily adapting to shapes by the conventional application of binder combined with heat setting. As well, while the entanglement of long fibers makes di ficult the commercially desirable feature of longitudinal separation of the pack during installation around impediments, the present invention seeks to provide for a longitudinally separable or "splittable" pack.

The methods of the present invention, thus, first provide various alternative ways to produce product definition in such thick, binderless wool packs of long, single component, and particularly, bicomponent, glass fibers. The present methods are loosely grouped as those including a step which disturbs the fiber matrix, those including a step which adds an element to the fiber matrix, and those including a step of fusing fibers. It has been found, particularly with regard to long irregularly shaped bicomponent fibers, that excessive entanglement induced in the surface of the wool pack has a negative impact on recovery. Further, it has been found that excessive disturbance of the fiber matrix beyond the surface, such as by needling, may cause otherwise entangled, irregularly shaped fibers in the wool pack to become straightened, losing some of the desirable volume filling characteristics otherwise valued in the wool pack. Thus, care must be taken to preserve important commercial and functional characteristics while providing desired product definition.

The methods of the present invention which disturb the fiber matrix include hydroentanglement and air knife entanglement techniques which are adapted in accordance with the present invention for use with thicker fiberglass mats, i.e. those exceeding approximately 76 mm (3 inches) in thickness. Needle-punching is further disclosed herein using heated needles.

Those methods of the present invention which add an element to the fiber matrix include the injection of an adhesive string or thermoplastic string along a plurality of locations through the width of the wool pack; surface application of hot melt thermoplastic spray or thermoplastic fibers with active surface heating; post-production addition of thermoplastic fibers to the wool pack which is still hot from initial forming; and stitching with fiber segments. These methods are generally less intrusive than the first group, and only more defined portions or columns within the fiber matrix are disturbed.

The methods of the present invention which include fusing of fibers include the use of lasers to provide bonding at fiber-to-fiber connections; the fusing of surface areas of fibers with heated platens or other groups of fibers with heated needles; and the use of bicomponent fibers which include as one component a more easily fusible material, such as a glass of lower melting temperature, or other thermoplastic component. These latter methods for fusing are the least intrusive, involving only portions or columns of the fiber matrix, without significantly disturbing the matrix or introducing additional material into the wool pack.

The methods of the present invention, second, further provide various alternative ways to produce longitudinally separable or splittable packs desired for installation. Preparation of a splittable pack of long fibers is achieved in accordance with the present invention by layering predetermined first and second weights of long fiber wool packs. Each layer is sequentially processed into the desired pack shaped by one of the methods just noted. The top layer is attached to the bottom layer during or after the shaping of the top layer. In addition, a wool pack separable along more than one plane may be formed by layering a plurality of wool pack layers. These methods and other features and advantages of the present invention are set forth in greater detail in the drawings and detailed description below.

BRIEF DESCRIPTION OF DRAWINGS Figure 1 is a schematic view in side elevation of the method of the present invention. Figure 2 is a schematic detail view in perspective of one embodiment of the present invention, performed at B in Figure 1.

Figure 3 is a schematic detail view in perspective of a device representative of several embodiments of the present invention, performed at B in Figure 1.

Figures 4 A through 4D are schematic cross-sectional views of fibers in a wool pack interrelated in accordance with the present invention.

Figure 5 is a schematic view in perspective of a layering process representative of the present invention.

Figure 6 is schematic cross-sectional view of wool packs in a layered structure attached in accordance with the present invention. Figure 7 is a schematic view in perspective of a splittable wool pack in accordance with the present invention. MODES FOR CARRYING OUT THE INVENTION The method of the present invention may be used to produce splittable wool packs 78 of long glass fibers 16 as representatively shown in Figures 5 through 7.

Referring to Figures 1 through 7, it may be seen in accordance with the 5 present invention that the method for forming a splittable wool pack begins by defining the shapes of at least two binderless wool packs of long glass fibers (Figures 1 through 4D), and attaching the binderless wool packs together in layered, separable relationship (Figures 5 through 7). In accordance with the preferred methods of producing binderless packs 48 of long fibers 1 , noted below, each wool pack 48 will have long glass fibers 16 generally

10 uniformly distributed therein, and may have long glass fibers 16 which are generally oriented. Defining the shape of each binderless wool pack 48 of long glass fibers 16 includes interrelating first pluralities of long fibers in generally specific portions of the wool pack 48 by any of the various methods further disclosed herein. While the term, "generally specific" is used to describe the portions of the wool pack 48 so interrelated, it is understood

15 that those generally specific portions might also be referred to as "targeted", "defined", "limited", "distinct", "discrete", or like portions of the wool pack 48. As may be seen in Figures 4A through 4D, those pluralities are in portions 88 (shown in Figure 2) or areas, groups, columns 100, diagonals 102, planar sections 104, or other associations of fibers 16 in spaced relationship which result from the various methods disclosed. Regardless, such

20 interrelationships maintain the binderless wool pack 48 in a shape of desired thickness.

Referring to Figures 5 and 6, attaching the binderless wool packs 48 together in layered, separable relationship includes interrelating second pluralities 79 of long fibers in adjacent generally specific portions of the wool packs 48. Attachment of the wool packs 48 includes positioning, at the least, a top wool pack layer 82 over a bottom wool pack layer

25 80. Adjacent surfaces of the pack layers 80, 82 generally define the plane 83 along which the binderless wool packs are separable. Intermediate wool pack layers 81 may be further provided to define multiple planes 83 of separation, as shown in Figure 6. The wool packs 48 are preferably of predetermined weights, and when layered may be provided as completely shaped wool packs, or with at least one of the wool packs, such as the top wool

30 pack, prepared to be shaped before, after or during attachment to the adjacent layer. Defining the shape of the wool packs 48, and attaching the wool packs 48 in layered relationship may, thus, be either sequentially or simultaneously performed. Shaping Techniques

The method of the present invention may be used to define the shape of wool packs 48 of long glass fibers 16 as representatively shown in Figures 1 through 4D.

Referring to Figure 1, it may be seen in accordance with the present invention that the method begins by providing a binderless wool pack 48 of long glass fibers 16 in which the long glass fibers are generally uniformly distributed. A rotary fiberizing apparatus 11 is representatively shown. Stated broadly, defining the shape of the wool pack 48 of long fibers then includes compressing the wool pack 48 to a first thickness (as shown at B), and interrelating first pluralities of long fibers 16 in specific portions of the wool pack 48. Thereafter, the pack is released (as indicated at C), whereupon the first pluralities of long fibers 16 remain substantially interrelated in tension to maintain the wool pack 48 in a shape of desired thickness. The first pluralities of fibers 16 are placed in tension by the tendency of the wool pack 48 to rebound to a less defined bunch or pack having only its initial shape. When further compressed to a thinner, second thickness, as for shipment (indicated at D), the interrelationships established between fibers 16 ideally permit the fibers to flex, and the wool pack 48 recovers to its desired thickness when the further compression is relieved.

Unlike prior art wool packs of short glass fibers interrelated with a generalized application of binder during fiberizing, the present invention discloses primarily post-production methods for interrelating specific portions of binderless wool packs 48 of long fibers 16.

In accordance with the method of the present invention, the first pluralities of fibers 16 in the wool pack 48 may be either interrelated by additional entanglement, or may be interrelated by interconnection, or both. However, inducing substantial additional entanglement of fibers 16 on the surface of the pack, while providing good pack shape definition, has been found to adversely effect recovery of the pack after compression. Accordingly, it is preferred that compressing the wool pack 48 occurs substantially without relative motion between the two faces of the wool pack 48 and compression surfaces 84 in contact therewith, thus generally maintaining the interrelationships between long fibers 16 in contact with the compression surfaces 84. As shown in Figure 2, the compression surfaces 84 may be continuous belts or, alternatively, may be a plurality of smaller continuous belts in parallel or series, or a plurality of rollers oriented transversely to the direction of movement of the wool pack 48, or still other configurations or combinations of such elements. Particularly where the pack is stopped for compressing and interrelating fibers, the compression surfaces 84 may be provided by plates or other more rigid, non-moving surfaces. Regardless, the exact configuration and combination of the compression surfaces 84 is not critical to the present invention, so long as the compression surfaces 84 provide the needed compression and allow for performing the step of interrelating (through a configuration of gaps, spacing, openings) without producing unwanted surface entanglement in the wool pack 48.

The first pluralities of long fibers 16 which are interrelated in the wool packs 48 in accordance with the present invention may be randomly distributed or generally oriented, for example in a generally horizontal or spiral relationship. The long fibers 16 may be straight, made of a single glass, or may be irregularly shaped, bicomponent fibers. Further, the methods disclosed herein can be practiced separately or in combination to interrelate first pluralities of fibers in a wool pack. While the methods of the present invention can also find use with other thermoplastic, polymer and mineral fiber types, their application to binderless, long glass fibers is preferred.

In accordance with the present invention, several methods are provided which include fusing pluralities of long fibers 16 to provide interrelationships, and more precisely, interconnections, therebetween.

In the first such method, with the wool pack 48 compressed to a desired thickness, first pluralities of long fibers 16 in specific portions of the wool pack 48 are interrelated by contacting at least a portion of one face of the wool pack 48 with a heated surface 86, and interconnecting a first plurality of long fibers 16 in that portion of the wool pack 48 by heating the fibers to define the shape of the wool pack 48. Referring to Figure 2, the heated surfaces 86 are preferably applied to a continuous wool pack 48, and move with the pack to avoid excessive surface entanglement. Alternatively, the heated surfaces 86 may be applied to a stationary wool batt. The heated surfaces 86 may, for example, be actively heated platens, or may be passively heated by virtue of placement within an oven.

Heated surfaces 86 may be applied to a portion of the wool pack 48 along an edge, corner or face thereof, or in a pattern at such locations to shape the wool pack 48. Figure 2 shows a series of heated surfaces 86 moving with the wool pack 48 on a track structure (not shown) to representatively interconnect fibers 16 on the faces and edges of a wool pack 48 as indicated at portions 88. The heated surfaces 86 may be specially designed with a targeted power and temperature which determines the number of fibers 16 fused and the depth of penetration through the pack. The texture of the fused surface portions 88 can range from soft and pliable to stiff and hard.

Where the long fibers 16 are bicomponent fibers including two materials having different melting points, the heated surface may be heated to a temperature below the melting or softening point of one material and above the melting point of the other, so that interconnection of the first plurality of long fibers 16 is provided by melting or softening substantially one of the two materials of the bicomponent fibers.

A second method is provided in accordance with the present invention in which first pluralities of long fibers 16 in specific portions of the wool pack 48 inward from the faces of a wool pack 48 are interconnected by positioning a heated surface therein. In this method, the heated surface is preferably a heated needle 90. With the wool pack 48 compressed to a desired thickness, contact with a first plurality of long fibers 16 is made by inserting the heated needle 90 into the wool pack 48 from at least one face thereof. Such insertion defines at least a portion of the path of travel of the needle, and interconnection of a first plurality of fibers 16 is performed along the path of travel of the needle. The path of travel of the needle further includes its path of retraction, as well as any lateral travel relative to the wool pack 48 while inserted therein. The needle thus forms internal interconnections between first pluralities of binderless, long fibers 16. As shown in Figures 4A through 4D, the path of travel may cause those interconnections to be oriented in columns 100, along diagonal directions 102, or along short planar sections 104 if the heated needle 90 moves somewhat relative to the wool pack 48. Needle penetration may be varied in depth and angle, and may be applied from opposite sides of the wool pack 48, all of which depends on the particular requirements of the product being produced. Preferably a plurality of heated needles 90 are inserted at respective spaced locations throughout the wool pack 48 to provide product definition. Some possible patterns in this regard are shown in Figures 4A through 4D; however, there is no intent to limit the present invention to the illustrative patterns shown.

Again, where the long fibers 16 are bicomponent fibers of two materials having different melting points, the needle may be heated to a temperature below the melting point of one material and above the melting point of the other, so that interconnecting a first plurality of long fibers 16 may be performed by melting or softening primarily one of the two materials of the bicomponent fibers.

Needles for use in accordance with this method are preferably smooth conductive metal needles, to minimize related fiber entanglement induced by its use, or could be textured to intentionally provide some level of fiber entanglement.

A third method is provided in accordance with the present invention in which first pluralities of long fibers 16 are interconnected in specific portions of the wool pack 48 inward from its faces by applying laser light energy to heat portions of the fibers in the wool pack 48. Preferably a bank of laser light sources 92 (shown in Figure 3) are provided to apply laser light energy at respective spaced locations throughout the wool pack 48. The laser source 92 may be any conventional laser source capable of generating heat sufficient to initiate fusing between the fibers 16. The intensity (power) and beam width may vary depending on the wool pack 48 density, shape of fibers 16, and the product whose shape is being defined. Variation in the intensity and beam width affects the depth of penetration and the number of fibers 16 interconnected. As well, the glass fibers may include additives to make them opaque or more absorptive of the particular laser light being applied. The laser beam 94 may be applied in a perpendicular or angular orientation to the wool pack 48 to fuse first pluralities of fibers 16 into columns 100 or diagonally oriented groups, and may enter from any face of the wool pack 48, as illustratively shown in Figure 4. This third method may also be used with bicomponent fibers, with the beam intensity targeted to affect one fiber component more than another or additives included for enhanced laser light absorption in one fiber component, and can be applied to provide fusing and interrelationships between fibers of many types in addition to the glass fibers preferred herein. In accordance with the present invention, several methods, denominated the fourth through sixth methods, are also provided which include a step of adding an element, such as polymer materials, to the fiber matrix to provide interconnections between first pluralities of fibers 16. Thus, referring again to Figure 1, the fourth method of the present invention includes, prior to or concurrent with compressing the wool pack 48, the step of distributing hot melt polymer spray or polymer fibers 96 over a portion of the surface of the wool pack 48 (shown at A), and then heating the wool pack 48 (as shown at B) to melt or soften the fibers and provide an interconnection between first pluralities of binderless glass fibers 16. The polymer chosen for the polymer fibers 96 may be any polymer material which is capable of interconnecting glass fibers when melted or softened, which is sufficiently strong to maintain such interconnection when in tension when the compressive force is released, and which is flexible during compression of the wool pack 48. Distribution of hot melt polymer spray or polymer fibers 96 over at least a portion of the surface of the wool pack 48 will provide interconnection of glass fibers 16 wherever those fibers are positioned during melting or softening, whether on or near a face of the wool pack 48, or inwardly disposed from a face. This method may further be practiced by distributing polymer fibers 96 sized to lodge substantially inward from a face of the wool pack 48. Both longer and shorter polymer fibers 96 may be interspersed to provide interconnection through the depth of the wool pack 48.

Alternatively, the fourth method may be practiced immediately after formation of the wool pack 48, which may emerge from forming processes at temperatures as high as approximately 93 to 204 degrees Centigrade (°C) (approximately 200 to 400 degrees Fahrenheit [°F]). Thus, the method may include providing a wool pack 48 having latent heat of production, and distributing polymer fibers 96 over a portion of the surface of the wool pack 48. Polymer fibers 96 may be distributed prior to or during the step of compressing (shown at B). Fibers of different sizes, may be applied to provide interconnections at different depths within the wool pack 48. In addition, the step of heating to further melt or soften the polymer fibers 96 may be either eliminated or performed (as indicated at H) to further melt or soften the polymer fibers 96.

A fifth method is provided which also includes a step adding an element to the wool pack 48 to provide interconnections between first pluralities of fibers 16 therein. In the fifth method, the interconnection of the binderless long fibers 16 is provided by injecting streams of polymer material into a first plurality of spaced locations throughout the wool pack 48, and forming a first plurality of columns 100 including binderless long fibers 16 bonded together by such polymer material. The polymer material is preferably injected by a plurality of injection needles 98, as illustratively shown in Figure 3. The injection needles 98 may be positioned above the wool pack 48 or, preferably, inserted into the wool pack 48 from at least one face thereof. As with the heated needles 90 described above, insertion of the injection needles 98 defines at least a portion of a path of travel along which a stream of polymer material is injected. Such injection is preferably performed concurrently with compressing the wool pack 48 to a desired thickness. Again, the path of travel may cause the interconnections thus formed to be oriented in columns 100, along diagonal directions 102, or along short planar sections 104, as shown in Figures 4 A through 4D, if the injection needle 98 moves somewhat relative to the wool pack 48. Injection needle 98 penetration 5 may thus be varied in depth and angle, and may be applied from opposite sides of the wool pack 48, all of which depend on the particular requirements of the product being produced. As well, the injection needle 98 may expel polymer from its tip, or from at least one opening along its length, or both. The injection needles 98 are specially designed with a targeted pressures and stream width which determines the number of fibers 16 bonded and the depth

10 of penetration through the pack.

A sixth method is provided which also includes adding an element to the wool pack 48 to provide interconnections between first pluralities of fibers 16 therein. The sixth method comprises driving at least one fiber 106 intermittently into the wool pack 48 of long glass fibers 16 concurrently with the step of compressing. The thickness of the wool pack

15 48 is typically greater than 76.2 mm (3 inches). It is preferred in accordance with this method that a plurality of separate fiber segments 106 be driven into the wool pack 48 at spaced locations. So driven, the fibers 106 tend to deform, and otherwise interrelate with the binderless long fibers 16 so as to be locked into place by such deformation, thereby interrelating a first plurality of fibers 16. Alternatively, stitching may be provided by a bank 0 of stitching needles, in like fashion as heated needles 90 in Figure 3. When the pack is compressed to a first thickness, the stitching needles introduce a glass or other material fiber through the pack. This produces columns 100 of fibers 16, interrelated by fibers 106 or a continuous fiber 108. The number of fibers 106 driven into the wool pack 48, and the spacing thereof, however, is dependent on the amount of shape definition for the particular 5 product. Regardless, the spacing is such that the recovery of the overall wool pack 48 is not adversely effected by consequential entanglement produced in the wool pack 48. Moreover, the driven fiber 106 or stitched, continuous fiber 108 results in a rigid column in tension and a flexible column in compression. The thread or fiber 106 or 108 is specially designed with a fineness to resist heat flow and a strength to maintain top to bottom communication in the 0 pack.

Finally, a third group of methods is provided in accordance with the present invention, which include a step which disturbs the fiber matrix of the wool pack 48 to provide interconnections between the first pluralities of fibers 16. These methods include hydroentanglement and air entanglement methods adapted to the thick wool packs 48 of long fibers 16 presented by the present invention. In particular, the eighth method interrelates the long fibers 16 by injecting a high velocity, low volume stream of fluid through the wool pack 48 at spaced locations, concurrently with compressing the wool pack 48 to a desired shape. This may be understood by referring to Figure 3, and substituting water jets for laser beams 94. The fluid is preferably water, but may alternatively be steam, air, other gases or combinations thereof. The stream of fluid drags individual fibers 16 to a new location within the wool pack 48 and results in the entanglement of those fibers 16 with others in the area. After the wool pack 48 is released, the finished product attains the desired shape as a result of the entangled fibers. The volume of fluid used and the pressures with which it is injected are dependent on fiber diameter, product density, and product thickness.

The shaping of wool packs 48 is further discussed in a commonly assigned, copending, related application, U.S. Patent Application Serial No. 08/279,613, filed July 25, 1994, entitled BICOMPONENT AND LONG FIBER PRODUCT DEFINITION, by Berdan, filed contemporaneously herewith, the disclosure of which is hereby incorporated by reference.

The various methods noted above provide desired interrelationships between first pluralities of fibers 16 in wool packs 48 to provide additional shape and product definition thereto. Practice of the methods will vary depending on the product being produced. Nonetheless, the methods share the common end of addressing the unique problems presented by binderless wool packs 48 of long fibers 16, and in particular, irregularly shaped, bicomponent fibers. Layering Techniques

Referring now to Figures 5 through 7, the methods of the present invention further provide various alternative ways to produce longitudinally separable or splittable packs 78 desired for installation. Thus, the step of interrelating the second pluralities 79 of long fibers 16 to attach layered wool packs may be performed by contacting those fibers with a heated surface; such as a platen or needle, heating those fibers with laser light energy; bonding those fibers with polymer material provided, e.g. by intermixture of fibers or injection; or by combinations of those methods. These methods have in common the interrelationship of second pluralities of fibers by interconnection. In accordance with the present invention, it is preferred to interrelate the second pluralities of long fibers by heating them with laser light energy.

As disclosed above, the step of interrelating the second pluralities 79 of long fibers 16 to attach layered wool packs may also be performed by injecting a high velocity stream of fluid through generally specific portions of said wool packs at spaced locations, injecting a needle into said wool pack at spaced locations, driving at least one fiber intermittently into said wool pack, or combinations thereof. These methods have in common the result that the second pluralities of fibers are interrelated by fiber entanglement. As the techniques used for defining the shape of the wool packs 48 and for attaching the wool packs 48 in layered relationship can be the same, the wool packs 48 may be layered before the top pack layer 82 is defined. Thus, in accordance with the present invention, the step of interrelating first pluralities of fibers in a wool pack and the step of interrelating second pluralities 79 in adjacent wool packs 48 may be performed after positioning the top wool pack layer 82 over the bottom wool pack layer 80. Shaping of the top wool pack layer 82 may be conducted either simultaneously or sequentially with attachment of the layers 80, 82. For some methods, shaping and attaching are performed by the same method, but to different depths in the layered wool pack structure 76. That is, interrelating the first pluralities of fibers may be performed to a first depth extending generally into the top wool pack layer 82 only, while interrelating the second pluralities 79 of fibers may be performed generally to a second depth extending through the top wool pack layer 82 into the bottom wool pack layer 80. In this regard, with techniques such as hot needle injection, laser bonding, needle punching, hydroentanglement, and stitching and stapling, the interrelating of second pluralities 79 of long fibers 16 may further accomplish simultaneously the interrelating of first pluralities of long fibers. Other techniques, such as those injecting polymer materials from a face of the wool pack opposite the plane 83 of separation, may be specifically targeted to interrelate only second pluralities 79 of fibers (such as shown in Figure 5) by limiting the injection of polymer until the needle is placed at the second pluralities of fibers. It is understood that where intermediate wool pack layers 81 are provided to define multiple planes 83 of separation, each intermediate wool pack layer 81 may be attached, or shaped and attached, sequentially to one or more of the lower layers, as just described for the illustrative two-layer structure discussed above.

In this regard, however, the second pluralities of fibers may be specifically targeted by each of the methods disclosed by performing those methods from at least one side face 77 of the layered wool pack structure 76. As shown in Figure 6, when performing the various methods from a side face 77, the second pluralities 79 of fibers may be interrelated along columns 110, diagonals 112 or planar sections 114 or areas positioned generally along or crossing between adjacent faces of layered wool packs 48. The plane 83 of separation of the splittable pack 78 is thereby defined, and the methods applied may be targeted more precisely to second pluralities 79 of fibers 16 without requiring penetration through the thickness of a layer. Approach from the side face 77 of the layered structure 76 is advantageous where multiple planes 83 of separation are defined in the splittable pack 78. Some layering techniques require at least partial performance before the wool packs 48 may be placed in layered relationship and joined. Such layering techniques further illustrate that the shaping and layering techniques may be entirely different. For example, referring to Figure 5, regardless of how the wool packs 48 are shaped, the wool packs 48 may be attached in layered relationship with hot melt polymer spray or polymer fibers 96 applied, as representatively shown. Application of the polymer precedes the layering step, and polymer is applied to at least one face of at least one of the wool packs 48 being joined. The second pluralities 79 of fibers being joined are thus generally on or near the opposing faces or surfaces of the wool packs 48.

Where hot melt polymer spray is used, the polymer is pre-heated. Where polymer fibers 96 are used they are melted after application to the wool pack 48 to interconnect the second pluralities 79 of fibers. Heat to melt the polymer and join the glass fibers may be present as latent heat of production of the wool pack 48. Alternatively, heat may be provided to the face of a wool pack 48 prior to or after the application of polymer fibers 96. As representatively shown in Figure 5, prior to application of fibers heat may be mechanically provided to a face by means of a heated roller 89, or radiantly with heat lamps 91. Further, after the application of fibers, or after layering of the wool packs 48, heat may be applied by way of heat lamps, or hot gases to melt the polymer fibers and join the wool packs 48 in layered relationship. Preferred polymer materials for hot melt polymer spray or polymer fibers 96 include polyethylene, preferably linear low density polyethylene; or polypropylene, ethylene vinyl acetate, or combinations thereof; or other suitable polymer materials. Hot melt polymer spray is preferably a polymer which is pressure sensitive, so that when layers of wool packs 48 are compressed into contact, the second pluralities 79 of fibers will bond and interrelate, joining the layers.

Thus, it is understood that the techniques used for defining the shape of the wool packs 48 used in a splittable pack, and for attaching the wool packs 48 in layered relationship, can be the same or different. Regardless, where defining the shape of a wool pack 48 is performed after the wool packs are in layered relationship, the step of defining further preferably includes compressing at least a portion of the layered wool pack structure 76 to a first thickness, and interrelating first pluralities of long fibers 16 in generally specific portions of the wool pack 48 to maintain the wool pack in a shape of desired thickness. It is preferred to substantially simultaneously interrelate the second pluralities 79 of long fibers 16 in adjacent generally specific portions of the wool packs 48, as desired to maintain them in a layered relationship, and then release the wool packs 48 from compression, much as shown illustratively in Figure 1. Alternatively, the wool packs 48 may be released from compression, and the second pluralities 79 of long fibers 16 thereafter interrelated.

Finally, in accordance with the present invention, defining the shape of the wool packs can include layering two continuous wool packs, and after attachment, cutting the attached wool packs into splittable wool packs 78 of defined length as shown in Figure 7. Alternatively, at least one of the wool packs 48 may be cut into a wool batt having a defined length prior to the layering step indicated in Figure 5. Regardless, the methods of the present invention produce a splittable wool pack 78 of long binderless glass fibers, generally separable along at least one plane 83.

While certain representative embodiments and details have been shown for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes in the method and system disclosed herein may be made without departing from the scope of the invention, which is defined in the appended claims.

Claims

1. A method for producing a splittable wool pack of long glass fibers comprising: defining the shapes of at least two binderless wool packs of long glass fibers; attaching said at least two binderless wool packs together in layered, separable relationship.

2. The method of claim 1 wherein said step of defining the shapes of at least two binderless wool packs of long glass fibers includes, for each wool pack, the step of interrelating first pluralities of long fibers in generally specific portions of said wool pack which maintain said wool pack in a shape of desired thickness.

3. The method of claim 1 wherein said step of attaching said at least two binderless wool packs together in layered, separable relationship includes the step of interrelating second pluralities of long fibers in adjacent generally specific portions of said wool packs to maintain said wool packs in layered relationship.

4. The method of claim 3 wherein the step of interrelating said second pluralities of long fibers is performed by heating said second pluralities with laser light energy, and interconnecting said second pluralities of long fibers.

5. The method of claim 3 wherein the step of interrelating said second pluralities of long fibers is a method step performed from the group consisting of: contacting said second pluralities of fibers with a heated surface, heating said second pluralities of fibers with laser light energy, bonding said second pluralities of fibers with polymer material, or combinations thereof.

6. The method of claim 3 wherein the step of interrelating said second pluralities of long fibers is a method step performed from the group consisting of: injecting a high velocity stream of fluid through generally specific portions of said wool packs at spaced locations, injecting a needle into said wool pack at spaced locations, driving at least one fiber intermittently into said wool pack, or combinations thereof.

7. The method of claim 3 wherein said step of interrelating said second pluralities of long fibers comprises fusing said second pluralities of fibers.

8. The method of claim 3 wherein the step of interrelating said second pluralities of long fibers comprises bonding with polymer material limited portions of said binderless wool packs comprising said second pluralities of fibers.

9. The method of claim 1 wherein said step of attaching includes: providing said at least two binderless wool packs in separated relationship; applying a polymer material to second pluralities of long fibers in specific portions of at least one said wool packs generally near a surface thereof; positioning said at least two binderless wool packs in layered relationship, wherein said surface of said at least one wool pack is in contact with an opposing surface of an adjacent wool pack; and interrelating said second pluralities of long fibers by bonding with said polymer material.

10. The method of claim 9 wherein said step of applying a polymer material is a method step performed from the group consisting of: sprinkling, spraying, or distributing polymer material.

11. The method of claim 1 wherein the step of attaching includes positioning at least a top wool pack over a bottom wool pack.

12. The method of claim 11 wherein said steps of positioning further include defining at least one plane along which said at least two binderless wool packs are generally separable.

13. The method of claim 11 wherein: said step of defining the shapes of at least two binderless wool packs of long glass fibers includes, for each wool pack, the step of interrelating first pluralities of long fibers in generally specific portions of said wool pack which maintain said wool pack in a shape of desired thickness; and said step of attaching said at least two binderless wool packs together in layered, separable relationship includes the step of interrelating second pluralities of long fibers in adjacent generally specific portions of said wool packs to maintain said wool packs in layered relationship.

14. The method of claim 11 wherein said step of interrelating first pluralities and said step of interrelating second pluralities are performed to different depths, wherein said step of interrelating first pluralities is performed to a depth extending generally into the top wool pack only and the step of interrelating second pluralities is performed generally to a depth extending through the top wool pack into the bottom wool pack.

15. The method of claim 11 wherein said step of interrelating first pluralities and said step of interrelating second pluralities are performed by different techniques.

16. The method of claim 11 wherein: said step of attaching includes positioning at least one intermediate wool pack between said top wool pack and said bottom wool pack; and said steps of defining and attaching generally define at least two planes along which said wool packs are generally separable.

17. The method of claim 1 wherein said step of attaching is performed sequentially after said step of defining.

18. The method of claim 1 wherein said step of attaching is performed substantially simultaneously with the step of defining at least one of said wool packs.

19. The method of claim 18 wherein said step of defining further includes the steps of: compressing at least a portion of said at least two wool packs to a first thickness; and interrelating first pluralities of long fibers in generally specific portions of said wool pack to maintain said wool pack in a shape of desired thickness; substantially simultaneously interrelating second pluralities of long fibers in adjacent generally specific portions of said wool packs to maintain said wool packs in a layered relationship; releasing said at least two wool packs from compression; whereby said first pluralities of long fibers remain substantially interrelated in tension in at least one wool pack to maintain said pack in a shape of desired thickness, and said second pluralities of long fibers maintain said wool packs in a separable, layered relationship.

20. The method of claim 19 wherein performing said step of interrelating said first pluralities of long fibers further interrelates said second pluralities of long fibers.

21. The method of claim 1 wherein the step of defining comprises cutting at least one wool pack into a wool batt having a defined length.

22. The method of claim 1 further including, after the step of attaching, the step of cutting said wool packs into at least one wool batt having a defined length.

23. A splittable wool pack of long glass fibers comprising at least two binderless wool packs of long glass fibers attached in layered relationship, generally separable along at least one plane.

24. The splittable wool pack of claim 23 wherein said at least two binderless wool packs are maintained in a shape of desired thickness by the interrelation of first pluralities of long fibers in spaced, generally specific portions of said wool pack.

25. The splittable wool pack of claim 23 wherein said binderless wool packs are attached in layered relationship at second pluralities of long fibers in adjacent, generally specific portions of said wool packs.

26. The splittable wool pack of claim 23 wherein at least one of said binderless wool packs includes long glass fibers generally uniformly distributed therein.

27. The splittable wool pack of claim 23 wherein said long glass fibers in at least one of said binderless wool packs include generally oriented fibers.