US2609320A

US2609320A - Method of making flexible unwoven fabric

Info

Publication number: US2609320A
Application number: US200020A
Authority: US
Inventors: Modigliani Piero
Original assignee: Johns Manville
Current assignee: Johns Manville Corp; Johns Manville
Priority date: 1947-05-29
Filing date: 1950-12-09
Publication date: 1952-09-02
Anticipated expiration: 1969-09-02

Description

Sept. 2, 1952 P. MODlGLlANl 0 METHOD OF MAKING FLEXIBLE UNWQVEN FABRIC Original Filed May 29, 1947 2 SHEETS-SHEET 1 IN VEN TOR.

Puma MODIGLIANI IBYIVWQ Sept. 2, 1952 P. MODIGLIANI METHOD OF MAKING FLEXIBLE UNWOVEN FABRIC Original Fiied May 29, 1947 2 SHEETS-SHEET 2 INVENTOR. PIERO MoDlLl/IN/ Patented Sept. 2, 1952 METHOD OF MAKING FLEXIBLE UNWOVEN FABRIC Piero Modigliani, Manhasset, N. Y., assignor to Johns-Manville Corporation, New York, N. Y., a corporation of New York 7 Original application May 29, 1947, Serial No.

751,481. Divided and this application December 9, 1950, Serial No. 200,020 g 11 Claims. 1

The instant invention relates to improved methods of making unwoven fabrics'of thermoplastic filaments, such as glass, and is a division of my copending application, S. N. 751,481, filed May 29, 1947, in which the products of the instant method are claimed.

Heretofore, filamentary mats of glass have been formed in various ways. In one method glass fibers are drawn directly from a melting-furnace tor furnaces and accumulated on a rotating drum. The furnace and drum are relatively reciprocated ;so that the filaments of each of the layers acicumulated on the drum are crossed with respect to the filaments of adjacent layers. In the normal practice the reciprocation is relatively slow as compared to the rate of fiber drawing, whereby the angles between the filament of adjacent layers are acute. When the mat is built up to the desired thickness it is removed from the drum by slitting its longitudinally of the drum, and the mat is then stretched in a direction substantially perpendicular to the original lay of the filaments, whereby it is expanded or opened in a manner similar to that of a lazy tongs, the angles between the filaments opening to increase the porosity and to reduce the density and thickness of the product. The relatively loose, weak, fibrous product thus formed has, for a number of uses, been impregnated witha suitable binder to strengthen it and give it sheet-like characteristics; The impregnation of the product, however, binds the filaments relatively rigidly in their positions and greatly reduces the flexibility .of the product. The principal object of the instant invention is the provision of methods of making unwoven fabric or sheets composed of glass filaments which will have the ability to readily fiex and conform to irregular surfaces. More particularly an object of the invention is the provision of a method in which a minor proportion of an uncured adhesive or binder is dis- ;tributed in an unexpanded mat of the type made .on the drawing drum' of the known equipment .described above, thebinder being applied during the drawing operation or after the mat is removed from the drum, but preferably theformer. The mat is treated to soften the binder and urge it toward the crossing points of the filaments and is then expandedto a predetermined degree and in a direction at substantially right angles to the original layof the filaments, and the binder is set or cured. The expansion step may be carried out in different ways and to different exitends depending upon the characteristics desired for'the finished product. However, in all another product made by the method of 2 s casesthe operations are such that the fibers are reoriented and the product, as compared to theoriginal mat, is relatively soft, thick and open.

My invention will be more fully understood and further objects and advantages will becomeapparent when reference is made to the more-detailed description of a preferred embodiment of the invention which is to follow and to the accompanying drawings in which:

Fig. 1 is a perspective View of a product made in accordance with the method of the instant invention;

Fig.2 is a view similar to Fig. 1 illustrating the instant invention;

Fig. 3 is a diagrammatic, end elevational view of an apparatus employed in the instant invention for carrying out the method thereof;

Fig. 4 is a front elevational view of the apparatus of Fig. 3; t

Fig. 5 is a diagrammatic, plan view of further apparatus employed in the instant inventionparticularly for the production of the product 'of Fig. 2;

Fig. 6 is a side, elevational view of theapparatus of Fig.5; v

Fig. '7 is a view similar to Fig. 5 illustrating apparatus employed to produce the productiof Fig.1;and

Fig. 8 is a side elevational view of the apparatus of Fig.7.

Referring now to the drawings and particularly to Fig. 1, one product made by the method of the instant invention consists of an vm woven fabric 10 composed of a plurality'ef layers [2, each formed of continuous, or substantially cone tinuous filaments l4. Fine glass filaments are preferably employed and the following description is directed particularly to such case. The filaments of each layer lie in approximate par allelism and, in this embodiment of thepro'duct, the filaments of adjacent layers cross each other at relatively acute angles; that is, the. filaments lie generally longitudinally of the product, "but at a sufiicient angle to the longitudinal to cross the fibers of the adjacent. layers. Intermingled with the filaments is a relatively minor proportion of a cured or hardened binder, the proportion of the binder being, say, 0.2 to 20%by weight of the product. The binder, illustrated at l6, exerts its binding action for the most part only at the intersection or crossing points of the filaments to bind the filaments firmly together at these points. It will be understood thatFig. 1

is a diagrammatic illustration of the product and that in actual practice the binder will be visually relatively insignificant.

A glass fabric having the construction features describedabove is readily flexible and distortable due to the inherent flexibility of the individual filaments and the concentration of the binding action at the crossing points whereby the fila ments may bend and distort intermediate such points. The product can readily be applied to irregular surfaces. It is very porous, open, and expanded or puffed up in thickness, and is adapted to absorb large percentages of impregnants.

It can be used in many places in substitution for woven fabrics and in such uses has the further advantage that it contains none of the lubricants or sizings required for weaving operations.

The product may also be of a character to be highly stretchable and elastic, a product of this type being illustrated in Fig. 2. Fundamentally the product is similar to that in Fig. 1, except ha t the filaments lie at greater angles to the longitudinal dimension and, hence, cross each other at wider angles than before. The binder it exerts its binding function at the crossing points of the filaments, as in the case of the fabric of 1. The product is open and porous and relati-vely inflated or puffed up in thickness. When a. product of this type is subjected to a pulling stress, although the fibers are firmly secured together at their crossing points, stretching will take place, due to the bending of the individual filaments, the filaments retaining their fixed relative positions in the fabric. When the pulling stress is released, the resilient characteristic of the fine glass rods which constitute the filaments, will urge them to again straighten out and return the fabric to substantially its original dimensions.

The binder employed for the products of both types may be either a thermo-setting or thermoplastic adhesive composition. The preferred matfer'ial is an acrylic resin. Other binders, such as plienolrformaldehyde resins, urea-formaldehyde resins, polyvinyl alcohols, latex and the like may lie-us d.-

Referring now particularly to Figs. 3-8 inclusive, the method of making the products described .above will be. explained in detail. The initial mat, known as the condensed mat, is inadeby substantially the conventional drawing proces's'previously described. Figs. 3 and 4 diagrammatically. illustrate the essential steps in the formation of the initial mat and the apparatus employed therein. Fine glass filaments Z2 insuitable number and integrally connected to glassissuing through the spinning orifices of p.' ,glass furnace 24, are brought into contact with a rawing drum 26, rotated in the direction indicated by the arrow in Fig. 3 by any suitable drivl ng means and at relatively high speed, and continuously drawn directly from the glass furnace and accumulated on the drum. Furnace 24 is reciprocated relatively to the drum as indicated by the double-headed arrow in Fig. 4, to lay the glass filaments on the drum. in a plurality of layers of continuous spirals with the filaments of each layer crossing the filaments of adjacent layers. The rate of reciprocation of the furnace relatively to the drawing speed, that is, the rotational speed of the drum, is such that the filaments of the adjacent layers cross each other at acute angles.

The binder application is preferably performed at suitable intervals during the drawing opera tlon bya spray device 26 (see Fig. 3) which may be a hand spray and which is moved back and forth across the mat on the drum to uniformly apply the binder material. The amount of binder used is carefully controlled to provide a solids binder content in the finished mat of, 788W 0.2 to 20% by weight of the mat.v The binderis preferably applied in the form of an emulsion, a waterdispersion of the preferred acrylic resin being suitable. However, a solution of the binder in a solvent may be employed. Due to the relatively high speed of movement of the mat carried on the drum. and the temperatures prevalent during the filament drawing operation, the binder rapidly dries by evaporation of the water, or the solvent, as the case may be, so that upon completion of the drawing operation, the mat contains a substantially dry, but unset binder.

Alternatively to apply the binder during the mat drawing operation, it may be sprayed or brushed on the mat after removal of the mat from the drum, and the mat then permitted to air dry. A conventional wetting agent of any suitable type may be used to insure penetration of the binder.

When the condensed mat is completed itis placed on a conveyor 28 in such a manner that the direction of the filament is generally transverse of the conveyor, as illustrated in Fig-5 that is, the dimension of the mat measured'by the circumference of the drum extends transversely of the conveyor. While the mat is on conveyor 23 it is treated with a binder softener. In the case of a binder such as the preferred acrylic resin, the softener is water which, in effect, again places the finely divided binder in suspension. If binders are employed of a type which cannot be practically softened with water, an appropriate solvent is used. The softener is applied by brushing it onto the mat, suitablywith a hand brush 82, the brush strokes, beingmade transvers ly of the conveyor; that is, insubstantially the direction of the filaments on the conveyor. This operation softens or liquifies the uncured binderand tends to concentrate the binder at the crossing of the filaments. Inlieu of the brush application of the binder, it may be applied by spraying or by a brush roll, but the hand brushing operation is preferred as it aids in the concentration of the binder at the crossing points. In addition to, the softener a part of; the bindermay be applied at this stage. Thus a suitable percentage, say up to 70% of the total binder, may be applied at this time, the added binder being the same as that already used or one of the other binders, for example, a ureaformaldehyde resin. This may be spreadonto the mat similarly as the softener. When the binder has been wetted and additional binder applied if desired, as described above. thematis stretched and the binder set,

The stretching operations employed for the flexible, and, for the flexible and elasticproducts, are fundamentally the same, but, for best results vary in details. The apparatus illustrated in Figs. 5 and 6 is particularly adapted for the production of fabrics of; the type shown in Fig. 2. The apparatus consists of a roll 30 adapted to overlie the conveyor 28 and to be pressed toward the conveyor by suitable means (not shown) to confine the mat between it and the conveyor, the roll and conveyor-constituting a feeding device. Spaced from conveyor 28 and roll- 30 a relatively short distance, say a foot or less, is a drafting or drawing device 34 of a suitable type which may consist as shownof driven rolls 36-48 and an overlying roll 40 restagainst the lower surface of the web. As will be appreciated. other binder curing devices maybe used. A table 46 may be located between the conveyor 28 and drafting device to aid particularly in the threading of the mat through the device. Conveyor 28, roll 30, rolls 36 and 38 of the drafting device and the driven rolls 43 of winder 42 are driven by motors or devices (not shown) of conventional :v type, the drive being such that the speeds of the different driven elements may be respectively varied .to permit. necessary adjustments in the operation.

In the operation of the apparatus described above, a mat on conveyor 28 is carried into positino to be confined between the conveyor and roll 30 and the mat is fed forwardly at a controlled rate by the conveyor and roll. As illus-, trated, more than one mat may be placed on a conveyor 28 whereby a mat may be undergoing treatment with the binder softener while a previously treated mat is being subjected to the stretching operation. In starting up the operation, the mat, as it emerges from between roll 30 and conveyor 28, is taken manually and as soon as a sufiicient length of mat has appeared, is manually stretched .out into the form of an extended web and inserted beneath roll 40 of the stretching device and thence carried to takeup spindle 45 of take-up device 42 and fastened to the'spindle. At the completion of these starting steps the machine is operated to continuously stretch the mat. For this purpose rolls and 38 are driven at a speed relative to the delivery rate of roll 30 and conveyor 28 to secure the desired elongation of the mat. In the production of the stretchable, elastic, resilient mat for which this apparatus is'particularly adapted, the relative .speed is such that the mat is stretched to, say, two to thirty times its original'length, the filaments in the stretched product being shifted from positions where they lie approximately transversely of the mat to positions at wider angles,'say, atangles approaching 45 in the commercial form. During the stretching operation, the filaments shift and slide on one another and the angles therebetween open up as illustrated in Fig. 5 to the extent determined by theirelative speedsof the drawing and feeding devices. Inasmuch as the binder is in a softened and unset condition at this stage, it does not prevent the opening and stretching operation. The series or rows of lamps between the feeding and stretching devices initiates the curing of the binder but does not carry it through to such an extent as to harden the binder before the stretching operation is completed. As-, the stretched product leaves the drafting or stretching device 34 it is subjected to the binder setting action of the rows of lamps above and below the web which completes the setting and curing of the binder and removes the water or solvent employed to soften it. The finished web is then wound on winder 42 from whence it may be removed and divided into sheets, strips, tapes or the like, of the desired 6f shapes and dimensions. Rol1s43of the winder are preferably driven at a speed only, slightly greater than that of the rolls of the drafting device to tension the web or fabric so that it will not unduly wrinkle during the winding operation. I

Referring now to Conveyor 28 and roll 30 may be thesarne as used in the previous case. A stretching or drafting device 48 which may be identical with the drafting device 34 of Figs. 5 and 6 is located at a substantial distance from the conveyor, say, a distance of 6 to 10 feet or more. Although not essential, a tensioning device 49 of anysuitable or conventional type is located between the drafting rolls and the feeding means. In, the construction .illustrated, the tensioning device consists of bars 55 mounted on a frame. pivoted as at 52, the bars tending to rotate in a' clockwise direction on their pivot under the influence of a weighted lever arm 54. Devices for setting or curing the binder, consisting preferably of series of infra-red ray lamps, are located as in,

the previous embodiment, one series being supported between the feeding and drafting device.

and a second and third series being supported between the drafting device and a take-up 58.

The latter may bein all respects the same as the take-up devices used in the embodiment of Figs. 5 and 6. I

In the operation of this form of the appara tus the mat, after the application of the binder softening medium, is fed through the feeding device as before, and the drafting device is driven at a speed relative to the speed of the delivery device so as to stretch the mat into a web in which the filaments extend generally lengthwise and at acute angles to one another. For example, in commercial operations the mat has been stretched to over thirty times its original length. The wide spacing of the delivery device from the stretching means provides sufficient time for the extensive movement of thefila ments necessary to secure their desired reorien tation. The tensioning device, although not essential, is employed to aid in controlling the tension in the mat to obtain the desired rearrangement of the filaments. p l

The product produced by the method of Figs. 7 and 8 isvery flexible and distortable as-the filaments are free to bend between the adhesively locked crossing points. However, due to the arrangement of the filaments substantially-lon -v gitudinally of the product, theproductis relatively unstretchable.

bending of the filaments between their crossing points and, hence, stretching of the product, but

due to the'natural resilience of the filaments,-

Figsh'i an d 8, an apparatusis illustrated which is adapted particularly for; the production of the fiexible product of Fig. 1..

The mat made by. thev method and apparatus ofFigs. 5"a'nd6 on the. other hand, is not only flexible and distortable' but also is stretchable and elastic. The application of pulling stresses to thisproduct will cause described my invention in rather What i claim: is

l; A method of formingan unwoven fabric comprising forming a condensed mat of a p111-- rali'ty' of layers of filaments with the filaments extending generally transversely of the mat and with the filaments of adjacent layers crossing at acute angles, applying an unset binder to the mat, expanding themat'in a direction-trans versely of the general'lay' of the filaments to form an elongated web, and" setting the binder.

2. A method of; forming" an unwoven fabric comprising forming a condensed'mat of a plu rality of layers of filaments with the filaments extending generally transversely of the mat and with the filaments of adjacent layers crossing at acute angles, applying an unset hinder tothe mat during its formation, expanding the mat in a direction transversely'of the general lay of'the filaments toform' anelongated web, and-"setting thebinderj 3. 1 method of forming an unwoven fabric comprising forming a condensed mat bywindinga plurality of layers of filaments" ona drum with the filaments of adjacent-layers crossing'at acuteangles, applying an unset binder to the filaments on the drum periodically during winding expending the mat to 'form anelongated web, and

setting the binder.

4. A method of forming an unwoven fabric comprising forming a; condensed mat of a plurality of layers of filaments with the filaments extending generally transversely of the mat and with the filaments of adjacent layers crossing at acute angles, applying an unset binder to the mat periodically during its formation, expanding the mat in a direction transversely of the general'lay of the filaments to form an elongate web, and setting the binder.

"5. A method of forming an unwoven fabric comprising forming a condensed mat'of a plurality of layers of filaments with the filaments extending generally transversely of the mat and with the filaments of adjacent layerscrossing at'acute angles, applying an unset binder to the mat, the weight of theunset'binder so applied being a minor proportion of the weight of said fabric, expanding the mat in a direction at right angles tothe general lay of the filaments'to form an elongated web, and setting the binder.

6. A method of forming an unwoven fabric comprising forming a condensed mat of a plurality of layers of filaments with the filaments extending generally transversely ofthe mat and with the filaments of adjacent layers crossing at acute angles, applying an unset binder to the met during its formation, the weight of the binder so" sprayed being a minor proportion of the weight. of said fabric, expanding the mat in a. direction at right'angles' to the general lay of thefilaments to form an elongated web, and setting the binder.

LA- method of forming an unwoven fabric comprising forming a condensed mat of a. plurality of layers of filaments with. the filaments extending generally transversely of the mat and with the filaments of adjacent layers crossing at acute angles, spraying an unset binder on the mat periodically during its formation, the weight of the binder so spra ed-being a miiior propos tion or the weight of said fabric";- expanding the mat in a direction at right angles: to the general lay ofthe filaments to: form an elongated web, and setting the binder; i

'8. A method of forming an unwoven fabric comprising 'forming'a condensed mat of a phrrality of layers of filaments with the filaments extending generally transversely of themat and with the filaments of adjacent layers crossingat acute angles; applying an unset binder to the mat, the weight or. the binder so-applied being a minor roportion of. the weight'of said-fabric,- applying an agent to said matto soften the binder, expanding the mat in a dire'cti'on at right'angles to the general lay of the filaments to'fonn an elongated web, and setting. the hidden. 1 I

9. A: method. of" forming anunwoven fabric comprising forming a condensed mat or a filth rality of layers of filaments with the filaments extending in one general direction and with: the

filaments of adjacent layers" crossing at acute angles, saidmat" containing a distributed, dried but unset binder, the weight ofxsaid binder being.- a minor proportion of theweight of said fabric, brushing'a binder softener onto said mat in'a direction to urge the binder toward the crossing points of thefilaments, expanding .the'mat in-a direction at right angles tothe general layof the" filaments to form anelongated web,- and setting'the binder;

10. -A method of form-ingan unwoven" fabriceomprisingforming a condensed mat of a pinrality of'layers of filaments with the filaments extending in onegeneral directionand with'the:

extendingin one. general direction and with 1' the:

filaments of." adjacent layers crossing ati'aoute'.

. angles, applying a thermoasetting binder in aqueous suspension to said mat during its. format v tion, brushing a binder 'softeneronto 'said mat in a direction. to urge the-binder toward. the crossing:- pfointsoii the filaments, expanding the matwin a direction at right angles tothe-generalclayoi' Number Name Date 2,546,230 Modigliani- -l -;-Mari 27,.1'1'951' 2,578,534 Giles'et allega- Dec. 11; 1953:

Claims

1. A METHOD OF FORMING AN UNWOVEN FABRIC COMPRISING FORMING A CONDENSED MAT OF A PLURALITY OF LAYERS OF FILAMENTS WITH THE FILAMENTS EXTENDING GENERALLY TRANSVERSELY OF THE MAT AND WITH THE FILAMENTS OF ADJACENT LAYERS CROSSING AT ACUTE ANGLES, APPLYING AN UNSET BINDER TO THE MAT, EXPANDING THE MAT IN A DIRECTION TRANSVERSELY OF THE GENERAL LAY OF THE FILAMENTS TO FORM AN ELONGATED WEB, AND SETTING THE BINDER.