US3342658A - Method of making filamentous mats - Google Patents

Description

Sept. 19, 1967 R. L. JACKSON, JR METHOD OF MAKING FILAMENTOUS MATS Filed Dec. 11. 1963 .IFIGJ INVENTOR. ROBERT L. JACKSON,JR.

ATTORNEY United States Patent 3,342,658 METHOD OF MAKING FILAMENTOUS MATS Robert L. Jackson, Jr., Louisville, Ky., assiguor to American Air Filter Company, Inc., Louisville, Ky., a corporation of Delaware Filed Dec. 11, 1963, Ser. No. 329,714 6 Claims. (Cl. 156-174) This invention relates to a method of making filamentous mats of the type commonly used for decorative purposes in plastic sheet material.

The invention is concerned with, and has as one object, the provision of a method for making a decorative mat in which the decorative character primarily derives from separate strata of the mat presenting distinctly different filament patterns.

Another object is the provision of a method which may be readily practiced with existing apparatus and utilizing recognized glass fiber handling techniques.

It is well known to make a filamentous mat in the following manner: building up a cylindrical compact mat by feeding continuous filaments to a rotatingdrum from a filament feeder which is reciprocated back and forth along a path parallel to the axis of the drum; slitting the mat along an axial line and unwrapping it from the drum to form a planar mat; and stretching the mat in a direction transverse to the general lay of the filaments. The binder which holds the filaments together in the final mat is applied while the filaments are being wound upon the drum and/ or after'the mat has been stretched.

In accordance with my invention the foregoing conventional process is largely followed, but with the important difference of applying a binder to only a selected stratum of the mat during winding, and winding the remainder of the filaments to form a stratum of distinct depth without the application of binder. When the removed mat is stretched, the stretching characteristics of the mat as a whole is influenced by the stretching characteristics of each of the diverse strata. However, the pattern of the filaments in the stretched mat corresponding to the binder wetted stratum presents a distinctly different appearance than the pattern of filaments corresponding to the stratum wound in the absence of binder. Thus the invention provides a very simple method of forming a mat in which a decorative pattern of one particular character overlies a pattern of another distinct character. The winding step of the process may be carried out without interruption with the application of the binder during the winding step being simply stopped at the appropriate time. Hence, a product is formed which gives the appearance of being laminated without any requirement, in fact, of a separate laminating step.

While the invention is primarily intended for use in making decorative filamentous mats and will be described in this connection, it will be appreciated by those skilled in the art that a mat made in accordance with the invention may also serve reinforcing and perhaps other purposes as well.

The invention will be explained in connection with the accompanying drawing wherein:

FIGURE 1 is a partly diagrammatic front elevational view of apparatus for winding a cylindrical compact mat;

FIGURE 2 is a partly diagrammatic side elevational view of the apparatus of FIGURE 1;

FIGURE 3 is a diagrammatic side elevational view of apparatus used during the stretching and further treatment of a mat according to the invention; and,

3,342,658 Patented Sept. 19, 1967 "ice FIGURE 4 is a representation of the appearance of two strata, purposely separated, of a mat made according to the invention.

Referring to FIGURES 1 and 2, a cylindrical compact mat according to the invention is made by feeding a plurality of glass fiber filaments 2, issuing from a glass fiber producing furnace 4, onto the surface of a rotating drum 6. The furnace 4 is driven in a reciprocating path axially along, and back and forth between the ends of the drum. The driving means (not shown) for effecting such reciprocating movement may be of the type which provides a substantially uniform furnace traverse speed between end reversal points, but preferably is of the type disclosed in my US. Patent 2,798,531 which provides a furnace traversing speed which is varied in a cyclically repetitive pattern between maximum and minimum speed value one or more times during each traverse. The drum is rotated a multiplicity of times during each traverse of the furnace so that the successive layers of compact mat built up on the drum during correspondingly suc cessive traverses will each contain a multiplicity of helical turns of filaments extending continuously from one end of the drum to the other. It will be appreciated that with this arrangement, the filaments of adjacent layers of the compact mat lie in crossing relationship.

The binder is applied to the filaments of a selected stratum of the compact mat as it is being built up by a spray applicator 8 which is arranged to periodically traverse the drum in an axial direction. The drum-applied binder selected preferably should be of the type which retains substantial flexibility until the subsequent stretching of the mat takes place. One suitable binder i a resilient polyester resin identified as InterChem 1390 manufactured by InterChemical Corp.

The currently preferred mat according to the invention is made by applying the binder to only the inner or underlying stratum of the compact mat, and then termimating the binder application while an outer or overlying stratum is wound on the drum. This reduces the chance that in the reverse situation the binder being applied during the formation of a wet stratum over a dry stratum will penetrate into the filaments of the dry stratum.

In most instances it is desirable to highlight the differences in pattern between the binder-wetted filaments of the one stratum and the dry filaments of the other stratum. To this end the binder material applied during the winding step has a pigment and/or dye, which is compatible with the binder, added to it.

After a cylindrical compact mat of desired thickness is built up upon the drum, it is slit axially, removed from the drum, and laid out flat on a supporting table 10 to form a planar compact mat 12 (FIG. 3). To facilitate removal of the mat from the drum without disturbing the filament arrangement, one paper sheet is wrapped on the drum before filament winding, and another after winding.

The planar compact mat 12 is then stretched or elongated in a direction generally transverse: to the lay of the filaments by pulling filaments extending along the one edge of mat in that direction. After the initial edge filaments are pulled away from the remainder of that mat, the successively adjacent filaments follow along in succession to ultimately form the stretched mat, which is perhaps equally well characterized as a web and is designated 14. The stretched web is received on an endless conveyor 16 which carries it downwardly into a receptacle 18 containing a binder solution 20. An upper flattening roller 22 cooperating with the conveyor maintains the web in a flattened condition as it moves through the 3 binder liquid. As the wetted web leaves the conveyor it passes over a suction slot arrangement 24 where excess binder liquid is removed. The web then is received by a second conveyor 26 which carries it through a heating oven 28 and to a windup station where the finished web is wound into a roll 30.

During the expansion step the filaments are generally reoriented in lazy tongs fashion so that in stretched form the web is greatly elongated and is narrowed in width. However, during the reorientation, the filaments of the wetted stratum behave differently than the filaments of the dry stratum. It is this difference in behavior that largely contributes to the desirable character of the final web. Specifically, the filaments of the wetted stratum appear to have a greater tendency to cling together as if they had been wound in collected group form. In contrast, the filaments of the dry stratum appear to rearrange themselves more like filaments wound as individual, discrete filaments.

A finished web product derived from a mat composed of a single wet stratum and a single dry stratum is represented by FIGURE 4 which is intended to illustrate generally the variation in pattern of the two diverse strata, with the web shown in delaminated form to emphasize the differences in pattern. The lower Web 32 corresponds to the stratum composed of dry filaments, and the upper web 34 corresponds to the stratum composed of wetted filaments. The wider lines of the stratum 34 represent a substantial number of filaments which have generally behaved during the stretching operation as a collected group of filaments by clinging together. The narrower lines of the stratum 34 indicate individual filaments or small numbers of filaments which have shifted during stretching away from the filaments giving the collected group appearance. In both cases, the degree of swirl or corrugation of the wetted stratum filaments appears to be distinctly greater than that of the filaments of dry stratum 32. The wetted stratum 34 also gives the appearance of an open-work structure having a substantial number of voids.

The filaments of the dry stratum 32 reorient themselves to provide an appearance of uniformity in which groupings of filaments are for the most part absent. That is, the stratum gives the appearance of relatively uniformly distributed individual filaments in which waviness or corrugation of the filaments is largely lacking and generally unnoticed. Thus the dry stratum well serves for background for the distinctive pattern derived from the Wet stratum.

While as shown in FIG. 4 the separate strata of the finished web may be separated for the most part by very carefully delaminating the strata, under normal handling the strata remain together.

For decorative purposes, it is desirable that the web not puff up, i.e., expand in thickness, after passage through the dip tank and during its passage through the oven 28. One way of preventing the puffing is to wind mats which, when stretched, are relatively thin, such as less than 50 mils th of an inch). With a thin mat, the weight of the liquid component of the dip tank binder composition tends to hold the web fiat while the liquid component is being driven off in the oven, with the binder solids progressively setting and holding the web in flat form as the liquid is driven off.

It is of course important when a colored binder is applied to the filaments on the drum that the subsequently applied dip tank binder have light transmitting characteristics which permit the colored filaments to show through. Since many conventional binders are substantially transparent, potential difiiculty in this respect is usually easily avoided. For most applications a starch binder may be used in the tank 18, in which case the dry stratum of the web has a generally whitish appearance with the wetted stratum providing a pattern of filaments of the desired color overlying the whitish background.

Since the filaments forming the wetted stratum 34 of the mat tend to cling together and thus emphasize their presence in the finished mat, it will normally be found adequate to form the wetted stratum of considerably fewer filaments than the filaments required in the dry stratum 32. Thus as one example of a mat in which the distinct pattern of the wetted stratum filaments is presented, the amount of glass used to form the filaments of the wetted stratum is slightly less than one-third of the amount of the glass used for form the filaments of the dry stratum.

While the description has been primarily concerned with the formation of a filamentous mat in which the filaments are glass, the invention is not to be considered as restricted to glass filaments but includes filaments formed of any organic or inorganic material which is susceptible to handling in a process according to the invention.

The invention claimed is:

1. The method of making a filamentous mat, compris- (a) winding a plurality of filaments back and forth upon a rotating drum to form a cylindrical compact filamentous mat of a series of overlying layers having filaments in each layer lying in crossing relation to filaments in adjacent layers;

(b) applying a binder to the filaments Wound in a selected portion, including at least one layer of filaments, of said mat while said portion is being formed, so that said mat includes at least one layer of binder wetted filaments and at least one stratum of filaments which are devoid of binder;

(c) slitting said cylindrical mat in a direction generally transverse to the lay of said filaments and upwrapping the mat as a whole from said drum to form a planar compact mat;

(d) stretching said planar mat in a direction generally transverse to the lay of said filaments to expand said mat; and,

(e) applying a binder to said expanded mat.

2. The method of claim 1 including:

(a) winding said plurality of filaments upon said drum in uncollected form.

3. The method of claim 1 including:

(a) applying a binder to said filaments during winding having a coloration distinct from the coloration of said binder applied to said mat in its stretched condition.

4. The method of claim 1 including:

(a) applying said binder during winding to less than half the filaments wound on said drum.

5. The method of making a filamentous mat, comprising:

(a) winding an inner stratum of a cylindrical compact filamentous mat by winding a plurality of filaments back and forth upon a rotating drum to form said inner stratum of a series of overlying layers having filaments in each layer lying in crossing relation to filaments in adjacent layers;

(b) applying a binder during winding to the filaments forming said inner stratum;

(c) forming an outer stratum of said cylindrical compact filamentous mat by winding a plurality of filaments back and forth upon said rotating drum to form a series of overlying layers having filaments in each layer lying in crossing relation to filaments in adjacent layers, without the application of a binder to the filaments forming said outer stratum;

(d) cutting said cylindrical compact mat formed of said inner and outer strata in a direction generally transverse to the lay of said filaments and upwrapping said cylindrical mat as a whole from said drum to form a planar compact mat;

(e) stretching said planar mat in a direction generally transverse to the lay of said filaments; and

(f) applying a binder to the filaments of both said inner and said outer stratum after said planar mat has been stretched.

6. The method of claim 5 including:

(a) applying a binder to said filaments of said inner stratum having a coloration distinct from the coloration of said binder applied to said mat in i-ts stretched condition.

6 References Cited UNITED STATES PATENTS 2,505,045 4/1950 Holcomb 156-174 X 2,609,320 9/1952 Modigliani 156-174 2,644,780 7/1953 Simkins et a1. 156-174 X 3,036,946 5/1962 Jackson 156-174 EARL M. BERGERT, Primary Examiner.

10 J. P. MELOCHE, Assistant Examiner.

Claims (1)

1. THE METHOD OF MAKING A FILAMENTOUS MAT, COMPRISING: (A) WINDING A PLURALITY OF FILAMENTS BACK AND FORTH UPON A ROTATING DRUM TO FORM A CYLINDRICAL COMPACT FILAMENTOUS MAT OF A SERIES OF OVERLYING LAYERS HAVING FILAMENTS IN EACH LAYER LYING IN CROSSING RELATION TO FILAMENTS IN ADJACENT LAYERS; (B) APPLYING A BINDER TO THE FILAMENTS WOUND IN A SELECTED PORTION, INCLUDING AT LEAST ONE LAYER OF FILAMENTS, OF SAID MAT WHILE SAID PORTION IS BEING FORMED, SO THAT SAID MAT INCLUDES AT LEAST ONE LAYER OF BINDER WETTED FILAMENTS AND AT LEAST ONE STRATUM OF FILAMENTS WHICH ARE DEVOID OF BINDER; (C) SLITTING SAID CYLINDRICAL MAT IN A DIRECTION GENERALLY TRANSVERSE TO THE LAY OF SAID FILAMENTS AND UPWRAPPING THE MAT AS A WHOLE FROM SAID DRUM TO FORM A PLANAR COMPACT MAT; (D) STRETCHING SAID PLANAR MAT IN A DIRECTION GENERALLY TRANSVERSE TO THE LAY OF SAID FILAMENTS TO EXPAND SAID MAT; AND, (E) APPLYING A BINDER TO SAID EXPANDED MAT.

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