US3913191A - Fluid aid for needling - Google Patents

Abstract

A highly needled fabric is produced by treating fabric, e.g., a needled fabric having a density of at least 8 pounds per cubic foot, with a needling fluid and then needling to increase the density, e.g., to at least 12 pounds per cubic foot. The needling fluid is preferably an aqueous fluid containing a surface active agent and/or thickening agent and preferably a foam is produced during needling to aid in maintaining add-ons of needling fluid of at least 100%, e.g., 150% to 250%.

Description

United States Patent 1191 1111 Smith, II 1 Oct. 21, 1975 15 FLUID AID FOR NEEDLING 3,506,530 4/1970 Crosby 1, 161/154 x 3,549,475 12/1970 Hcflcy ct a1. 161/154 X Invent Alexander $393,414 2/1974 Buff ct a1. .1 28/722 R ASSlgflEfil Flberwoven Corporation, 1,948,553 4/1971 Germany 11 28/72] R [22] Filed: Oct. 3, 1973 [21] Appl NO: 403,058 Primary Examiner-Mervin Stcin Attorney, Agent, or FirmCushman, Darby & Related US. Application Data c h [63] Continuation-impart 0f Ser No. 221,614, Jan. 28,

1972, Pat. N0. 3,817,820. 57 ABSTRACT [521 US. Cl H 28/722 R; 61,154, fin/55 A highly needled fabric is roduced by treating fabric, 151 1111.01. D0411 18/00 hwmg dens of 8 [58] Field of Search H 28/4 72 2 R 72 2 pounds per cubic foot, with a necdling fluid and then ll/km needling to increase the density, c.g., to at least 12 pounds per cubic foot. The ncedling fluid is prcferably [56] References Cited an aqueous fluid containing a surface active agent and/0r thickening agent and prcferahly a foam is pr0 UNITED STATES PATENTS duced during needling to aid in maintaining add-ons of 33771564 611945 Lundgre" 23/4 R needling fluid of at least c.g1, to 250% 2,908,064 10/1959 Lauterbach et a1 161/154 X 3,235,935 2/1966 Daruwalla 28 72.2 R 39 Claims, 1 Drawing Figure 325 g 300 Q) 275 Q 250 225 200 (r /75 g L50 1 A25 /00 50 25 0 I l l L 1 l l 1 4L DE/VS/ 7' Y, POUNDS/CUB/C FOO 7' US. Patent Oct. 21, 1975 505050505005 7 ZZZ .DF/VS/ 7'), POUNDS/CUB/C FOO 7' FLUID AID FOR NEEDLING This is a continuation-in-part of copending application, Ser. No. 221,614, filed on January 28, 1972, now US. Pat. No. 3,817,820 entitled NEEDLED TEXTILE FABRIC, the entire disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION The said copending application discloses a textile fabric which is composed of staple textile fibers that have been formed into a batt and needled with a large number of needle punches per square inch to produce a needled fabric of high bulk density and very special physical properties. In one form of the invention, the highly needled textile fabric is finished to produce an artificial leather. The properties of the artifical leather, to a large measure, are the result of the properties of the needled textile fabric per se, as opposed to the finish placed thereon. In this process the batt of staple fibers is needled through successive needling steps which progressively increase the overall bulk density of the needled fabric. In a preferred embodiment, the batt of fibers is needled in FIBERWOVEN looms with each side of the batt being needled in excess of 6,000 needle punches per square inch to provide an overall bulk density of at least 12 lbs. per cubic foot. As can be easily appreciated by those skilled in the art, this is a very large number of needle punches per square inch and the bulk density is considerably higher than that normally obtained by needling alone. While the initial needling operations may proceed with the looms being used in the normal and conventional manners, it has been found that as the bulk density and fiber entanglement progressively increased, the fiber mobility in the needled fabric decreased to a point where additional needling could not be practically performed. When fibers are substantially immobilized by high inter-fiber friction, further engagement by the barbs of the needles results in one or a combination of the following:

A. the substantially immobilized fibers exert sufficient force on the needles to cause the needles to deflect and break;

B. the fibers so resist further movement that the barbs of the needles cut or break the engaged fibers; or

C. in the case of less positive barbs, the tensioned fibers slip out of the barbs of the needles and cause the needling process to be substantially ineffective.

However, in order to accomplish the desired properties of the present needled fabric, especially the desired properties for artificial leather, it was necessary to achieve greater fiber entanglement and higher needled densities. The methods which were discovered for allowing efficient needling to these greater fiber entanglements and higher needled densities form a major feature of the invention although other important features will be apparent hereinafter.

OBJECTS OF THE INVENTION It is therefore an object of the invention to provide a method for producing a highly needled and intensely entangled fiber structure. It is a further object to provide a needling method which allows exceedingly high numbers of needle punches per square inch, and the attendant greater fiber entanglement and higher bulk densities of a needled fabric, without substantial deterioration of the needled fabric or substantial harm to the needles of the needle loom performing the needling operation. Other objects will be apparent from the following disclosure and claims.

BRIEF DESCRIPTION OF THE INVENTION According to the present invention, there is provided a method for producing a highly needled textile fabric by treating the textile fabric with a soaking amount of a wetting needling fluid and needling the treated fabric in the presence of the soaking amount of the wetting needling fluid to increase the overall bulk density of the needled fabric, e.g. to a density of at least I2 lbs. per cubic foot. This process will provide a dense highly needled fabric with an intensely entangled fiber structure and without substantial deterioration of the fabric or needles.

The needling fluid preferably contains either a surface active agent and/or a thickening agent, such as aqueous solutions of a wetting agent, soap or thickening agent. The surface active agent or thickening agent may produce any of the characteristic results thereof, e.g., foaming, lubricity, lowering of friction between fibers, etc. In a preferred form of the invention, the textile fabric is first needled until the overall bulk density of the fabric is at least approximately 8 lbs. per cubic foot and the needled fabric is then treated with a needling fluid which will foam during a further needling operation and the foam aids in retaining the soaking amount of the needling fluid in the fabric during this further needling. The foaming may be a result of the surface active agent and/or thickening agent or a separate foaming agent may be added to the fluid. Conveniently the needling fluid is placed on the fabric by dip and nip (e.g. padding or the like) which provides addons of at least e.g. to 200%. After the needling is completed, the needing fluid may be extracted and/or washed from the highly needled fabric and the fabric thereafter processed in any desired way.

DETAILED DESCRIPTION OF THE INVENTION While the present invention is especially useful for fabrics prepared only by needling of staple fibers, it should be appreciated that the invention is applicable to fabrics which have been partly made by other processes, such as weaving, knitting, felting and stitching (e.g., "Malimo" techniques), and then needled, with or without the addition of staple fibers thereto, to produce a needled structure having needled fibers closely entangled, especially at the face surface of the fabric, which presents considerable resistance to further needle penetration. Thus, the term needled fabric," as used herein is to be construed to included such fabrics. The fibers of the textile fabric may be as desired and can include alone or in combination synthetic fibers such as thermoplastics, e.g. polyesters, nylon, acrylics, cellulosics, etc., and natural fibers, such as cotton, wool, hemp and flax. The denier and length of the staple fibers are not critical and can be any or a combination of the conventional deniers and lengths normally used with the needling operations. Thus, the deniers can be from as little as k to 54 denier or less to as great as 8 denier or more but the finer deniers are preferred. The staple fibers may be single or multi-filament fibers. Thus, the fibers of the foregoing deniers may be composed of up to 10 to 20 filaments. In these cases, each of the filaments will have individual deniers generally proportionate to the total number of filaments and total denier, e.g., a ten filament. 1 denier staple fiber will have 10 1/10 denier filaments, etc. The fibers may have a length from as little as A: inch or less to as great as 5 inches or more (either crimped or noncrimped lengths).

It is preferred that the fabric is first needled until an overall bulk density of at least 8 lbs. per cubic foot is reached before the needling fluid is applied to the fab ric. it has been determined that this overall bulk density, and corresponding needling density and fiber entanglement, is the approximate threshold density at which further needling becomes difficult and encounters the problems noted above. This threshold, however, can vary somewhat with the particular needled fabric and the fibers thereof, and may be from as little as 7 lbs. to as high as 11 lbs., but most often considerable needling difficulty is experienced before fabric densities of lbs. per cubic foot are reached. At the lower of these densitites, i.e., 7 lbs. per cubic foot or less, the difficulty is not sufficiently serious as to require the needling fluid of the present invention. Therefore, for partical application, the present needling fluid is not normally placed on the fabric until a density of at least approximately 8 lbs. per cubic foot is reached but certainly before a density of 10 lbs. per cubic foot is reached. However, if desired, the needling fluid can be placed on the fabric prior to reaching the 8 lbs. per cubic foot density. The essential requirement is that the needling fluid be present on the fabric, as defined above, when further needling at densities above 8 lbs. per cubic foot.

As noted above, the fabric may, in part, be made by methods other than needling, e.g., wovem. The woven structure (alone or with staple fibers added thereon) is needled to the point where the needling fluid must be applied to produce additional effective needling. in these cases, the underlining woven structure may be considerably more dense than the 8 lbs. per cubic foot density, where the needling fluid is required. However, the fibers entangled by needling (either added to the woven structure or pulled therefrom by the needles) will form a needled portion of the total structure which will have a needled density of about 8 lbs. per cubic foot. Accordingly, when considering fabircs other than needled fabrics, the calculation of the lower densities where the needling fluid is to be added should be adjusted to account for the higher, non-needled densities. Generally, this adjustment is proportionate to the relative weight of the structure which has the higher nonneedled density. For example, if a woven fabric of 12 lbs. per cubic foot has added thereto an equal weight of staple fibers and then needled, the density of the total structure at which the needling fluid will be required will be higher than the aforementioned 8 lbs. per cubic foot. Of course, the further needling of such composite fabrics will produce correspondingly higher den sities than the 10 to 12 lbs. per cubic foot, noted above.

Since the fabric must be further needled in the presence of the soaking amount of the wetting needling fluid, the needling fluid must be maintained in the fabric throughout the further needling operation, i.e. the needling operation which increases the overall bulk density of the fabric to at least 10, especially at least 12, lbs. per cubic foot. Thus, the needling fluid must be of physical characteristics which will allow the needling fluid to be retained in the fabric during the further needling in amounts sufficient to promote fiber mobility and further flber entanglement and assist and allow the fibers to be permanently moved by the needles, without placing deteriorating stresses on the fibers, i.e., stresses which would cause fiber breakage and/or substantial harm to the needles of the looms, e.g. cause breakage of the needles. This foregoing described minimum amount of needling fluid which must be present during this further needling is referenced herein as the soalc ing amount. This term may be better understood by reference to the following example of the effects on needling with different amounts of needling fluid (water in this case) in the fabric during needling. Thus, with a needled fabric of about 8 lbs. per cubic foot density, no substantial effect of the water is noticed during needling with moisture contents of up to about 8 to 10% water by weight. in other words, at this moisture level, the fabric needles in the same essential manner as if it were dry. Accordingly, when it is attempted to obtain densities much above 8 lbs. per cubic foot at these moisture levels, the difficulties hereinbefore noted are encountered. At moisture contents between above about 8 and 10% and up to about 50% by weight of the fabric, the effect is to dramatically deteriorate the effectiveness of needling. At these moisture levels, needles rapidly break, the fabric tears and the needling is essentially ineffective. Thus, this range of moisture produces most undesired results. At moisture contents above about 50% this undesired effect begins to mitigate and the needling effect with additional moisture contents up to about becomes quite similar to the needling effects of up to 810% moisture contents. At moisture contents at above about 100%, the effective needling and greater fiber entanglement provided by the process of the present invention begins to occur. However, these effects are not obtained to the degree desired for artificial leather at these lower add-ons and add-ons, for this purpose, of at least equal to a soaking amount, are required. At higher fabric densities a soaking amount may be as low as 100% but for lower fabric densities, a soaking amount will usually be at least or as more fully explained hereinafter. Of course, the foregoing effects are not abrupt but are transitional in nature and the exact percentages in the foregoing regards will vary with the particular fabric, fabric density, fiber entanglement, needling fluid and needling technique. However, the example illustrates the most unusual effects produced by fluids in the fabric during needling and the necessity of a soaking" amount of needling fluid, as defined hereinbefore.

Any fluid (liquid) which is stable under ordinary ambient conditions can be utilized in the present process. However, as noted above, the needling fluid must have physical characteristics which will allow the needling fluid to be maintained in the fabric, during needling, in soaking amounts. The primary characteristic in this connection is that the needling fluid must simply be capable of sufficiently wetting (i.e., adhering to) the fibers of the fabric, that the fluid can be relatively uniformly dispersed on the fiber surfaces and entrained in the spaces between the fibers, as opposed to beading" on the surfaces of the fibers in the manner that mercury "beads on glass. This characteristic is defined herein as wetting and the needling fluid as a wetting" needling fluid. However, for commercial operations, it is a practical requirement that the added needling fluid be retained on the fabric during at least one pass through a needling machine, and the needling fluid should, preferably, have properties which assist in retaining the fluid in the fabric during this needling. The needling fluid should not only wet the fibers of the textile fabric but should be entrained in the structure as a foam or should at least be slow to drain from the structure because of high viscosity and/or thixotropic character. Thus, the needling fluid may contain surface active agents or thickening agents, foaming agents or combinations thereof. However, if desired, the needling fluid can be applied at sufficiently frequent intervals, or continuously, such that during the entire further needling operations a soaking amount can be maintained in the fabric without the aid of foaming agents, thickeners, surface active agents, etc. The essential requirement is that a liquid be sufficiently contained in the fabric that inter-fiber friction be reduced and fiber mobility be increased. Thus, the particular chemical make-up of the needling fluid is not critical so long as it is stable at needling conditions and is not harmful to the fabric. The needling fluid may be any of the conveniently available fluids such as alcohols, ethers, esters, aldehydes, hydrocarbons and halogenated hydrocarbons, but especially including lower alkanols, and lower alkanes. It is preferred, for obvious and practical reasons, however, that an aqueous fluid be used, e.g., an aqueous solution or emulsion. Nevertheless, the needling fluid may contain lower alkanols, e.g. methanol, ethanol, propanol, octanol, decanol and dodecanol, or higher fatty acid alcohols, e.g. lauryl alcohol, myristyl alcohol, palmityl alcohol and stearyl alcohol or the corresponding alkanoic acids and higher fatty alkanes and acids. Corresponding polyfunctional compounds of the foregoing may also be used, for example, polyfunctional acids and alcohols, such as glycols, e.g. ethylene glycol, glycerol, sorbitol and pentraerythritol or the glycerides thereof. Also the inter-esters of the foregoing acids and alcohols may be used.

Since the action of the needling fluid depends upon the ability of the fluid to be disposed on the surface of the fibers and entrained in spaces between the fibers, and, thereby reduce inter-fiber friction and increase fiber mobility, and hence effective needling to produce greater fiber entanglement, it is necessary that the needling fluid be a wetting" fluid, as noted above. Accordingly, to assist in this requirement, the needling fluid preferably will contain a surface-active agent. For aqueous needling fluids, many such surface-active agents are known to the art, especially in connection with conventional fibers. Thus, any of the conventional textile wetting or scouring agents may be 'used as the surface-active agent in the needling fluid. Among suitable wetting agents are anionic surface-active compounds having the formulae R SOfA", R C,,I-l SOfA" and R O SOfA, where R is a C to C hydrocarbon residue and A is an alkali metal or alkaline earth metal. Alternately, cationic compounds may be used which are acetates or simple salts of longchain fatty acid amines, such as octadecyl ammonium chloride or the quarternary ammonium salts thereof with cations of the R N type. Alternately, nonionic compounds may be used, for example, a fatty acid esterified with a glycol, usually a lower aliphatic glycol of up to 30 carbon atoms, such as a polyethylene glycol. Or, alkylated phenols or naphtols, e.g. dodecylphenyl ether of hexaethylene glycol, may be used. The particular chemical compound or compounds of the wetting agent are not at all critical and may be simply as desired, so long as they cause the fluid to substantially wet the fibers.

As noted above, commercial operations will usually include multiple passes through needling areas of a needle loom. For example, a FIBERWOVEN needle loom has four sets of needle boards (four needle areas). These looms are most useful for the present needling operations. See U.S. Pat. Nos. 3,112,552; 3,090,099; 3,090,100; 3,112,549; 3,112,548 and 3,132,406 for disclosures of suitable looms and needling techniques, which disclosures are incorporated herein by reference. Thus, for such looms it is not convenient to frequently re-apply needling fluid. Accordingly, it is preferable that the needling fluid be retained in the fabric for a reasonable period of time so that it may stay within the fiber structure during the passage of the structure through a needling area.

In a further preferred form of the invention, the needling fluid contains a thickening agent to aid in retaining the needling fluid in the fabric. Many such thickening agents for aqueous systems are known to the art and include acrylates, modified starches, polyacrylic acid and polyacrylamides, cellulosics, such as carboxy methyl cellulose, hydroxyethyl cellulose, methyl and hydroxypropyl methyl cellulose, polyvinyl acetate and alcohol, water soluble vinyls, including polyvinylpyrrolidone, polyethylene oxide, polyethylenimine, natural and synthetic gums, such as alginates, gum arabic, guar, karaya, locust bean and tragacanth. The particular thickening agent is not critical and may be chosen as desired but it is preferable to select an agent which is easy to remove after the needling process and which provides a substantial increase in viscosity for a given quantity added to the needling fluid, e.g. a needling fluid viscosity of at least 2 cp. or 3 cp. (Brookfield CPS-10 spindle, 12-60 RPM). However, higher viscosities are preferred, especially when the needling fluid does not substantially foam, as discussed in more detail hereinafter. Thus, viscosities of at least 4 to 10 cps are preferred and the viscosity may be as high as 50 to cps.

It should be understood, however, that the same agent may function as both the surface-active agent and the thickening agent. In this regard, the surfaceactive agent may simply be contained in the needling fluid in sufficiently high concentration so as to also provide thickening of the needling fluid. Alternately, an aqueous needling fluid may be thickened by the suspension of an immiscible liquid, i.e., an emulsion of a hydrocarbon and an emulsifier in an aqueous continuous phase. For example, a 50/50 volume ratio of water and naptha cut solvent (such as Varsol) can be emulsified with a fatty acid soap to produce a thickened emulsion.

in a further preferred form of the invention, the needling fluid will have a foaming agent therein so that the action of the needles on the fabric during the further needling will cause the needling fluid to foam and thereby the needling fluid will be entrained in the fiber structure and thus be retained in the fabric during the entire further needling operation. Here again, the foaming agent may be the same or different as either the surface-active agent or the thickening agent, as discussed above. However, many foaming agents, the same as the surface-active agents or different therefrom, are known in the art and include fatty acid soaps,

as discussed above, protein hydrolyzates, longchain florinated ethers and thio ethers. The foaming is more efficiently performed by soaps, as opposed to detergents, and fatty acid soaps are thus preferred. These soaps also give reasonably good wetting, especially the amine coconut fat soaps. Here again, the particular chemical composition of the foaming agent is not critical.

As can be appreciated, the surface active agent, thickening agent and foaming agent (if different from the foregoing) may be contained in the needling fluid in widely varying amounts and the particular concentration thereof is not critical so long as the above functions are provided. However, generally speaking each may be contained in the needling fluid in amounts ofas low as 0.01% to as high as 20% by weight, but usually between 0.1% and 15%, eg. between 0.5% to 1.5% and to 10%.

The needling fluid may be conveniently disposed on the fabric by simply soaking the fabric in the needling fluid. For example, the fabric may be dipped in the needling fluid and then passed through nip rolls to remove excess needling fluid. Alternately, the fabric may be sprayed or otherwise treated with the needling fluid. The dip and nip are, however, most convenient and will supply a soaking amount of needling fluid to promote fiber mobility and is the preferred method. For example, with most fabrics and fibers, this method will result in add-ons which essentially saturate the fabric. The term add-on," as used in this specification and claims, is defined as the weight increase of the treated fabric caused by the addition of needling fluid as compared with the weight of the untreated fabric. Thus, for example, if one pound of dry fabric contained 1% pounds of needling fluid, the add-on would be 150%. Also, as can be appreciated, the number of inter-fiber contact points (interstices) and the space between fibers will vary with the degree of fiber entanglement and the fabric density; thus, the amount of fluid which must be present to obtain further effective needling and further intensity of fiber entanglement depends on the density of the fiber structure, as illustrated in Example 1 hereinafter. Generally, the desired minimum quantity of needling fluid which must be present decreases as the fabric density increases.

While minimum add-ons of needling fluid are required for effective further needling, on the other hand, the add-ons of the needling fluid should not be excessive, since the higher add-ons are more difficult to handle and maintain in the fabric, especially in commercial size needle looms. Further, from a practical point of view, with densities in the present ranges, it is difiicult to obtain add-ons substantially in excess of 275%. In any case, add-ons in excess of 300% are not preferred. With the proper quantity of needling fluid present in the fiber structure further needling may be performed so that the resulting fabric can have intense fiber entanglement as measured by fiber reversals and curvature and at the same time can have overall bulk densities in excess of 13 or 14 lbs. per cubic foot, e.g. 15 lbs. per cubic foot. However, with sufficient needling, bulk densities of as high as 16 to 18 or even 20 to 21 lbs. per cubic foot can be obtained (all densities calculated on a non-woven needled structure or the needled portion of a composite structure.

After the further needling is accomplished, the needling fluid is extracted, eg by vacuum for recovery and reuse, and/or simply washed from the fabric by any of the conventional scouring or washing techniques and the fabric may be dried or otherwise treated as desired.

For purposes of the present specification, the overall bulk density referenced herein is defined as the weight per volume of the fabric, wherein the thickness of a section of fabric is determined for the volume calculation by pressing a 1.129 inch diameter presser foot (1 square inch) against a section of fabric held on a 2 inch diameter anvil where the presser foot is loaded with 10 ounces of weight, and measuring the thickness of the section. This is a standard means in the art of determining the overall bulk density of felt-like fabrics. (For more details see ASTM test D-46l-67). It should be appreciated, however, that the bulk density of primary importance is the bulk density of any portion of a fabric through which the needles must pass. For example, where the fabric has a bulk density gradient, as in the aforenoted parent application, the overall bulk density of the total fabric could be less than the bulk density of the top surface of the fabric. Thus for purposes of the present specification and claims, the bulk density being referenced is any finite bulk density through which the needles must pass.

While the invention will be illustrated in connection with a needled textile fabric according to the process of the aforenoted parent application, it should be understood that the invention is not restricted thereto and is fully applicable to the breadth of the foregoing disclosure.

EXAMPLE 1 According to Example 1 of the aforenoted parent application, a batt of staple polyester fibers (1% to 5 denier and 1% to 3 inches crimped length) was needled in three FIBERWOVEN looms, the first and second looms with l-l6-4C needles therein (l-barb-l6 mil triangular blade-4 mil barb depth) and the third with ll6-3C needles. A first layer of fibers constituted by 3 ounces per square yard of 1% denier and 1% inch length polyester staple fibers was carded onto the batt and then a second layer of the same fibers, except fiveeighths inch in length, was carded on the first layer. The batt was needled in the same manner as the previous needling step and the density of the resulting needled fabric was approximately 8 lbs. per cubic foot. The total number of needle punches to each side of the fabric to accomplish this density was approximately 4,500 needle punches per square inch.

The so-needled fabric was immersed in a water solution of a methylamine salt of coconut fatty acids (PEN- ETRANT GWX, Woonsocket Color and Chemical Co.). The concentration of the amine salt in the water was 6% by weight. This amine salt functioned as a surface active agent, thickening agent and foaming agent. After the fabric had become saturated with the needling fluid, it was removed from the fluid and passed through the nip of two lightly pressed counter-rotating smooth rolls which expressed excess needling fluid from the fabric and produced an add-on of between and 200%. The wetted fabric was then needled in a further FIBERWOVEN loom having the same needles as noted above until the density of the needled fabric was approximately 13 lbs. per cubic foot. The total number of needle punches in this further'needling operation was slightly in excess of 6,500 needle punches per square inch of each side of the fabric. Thus, the

total number of needle punches to produce the final overall bulk density in this example was in excess of 10,000 needle punches per square inch on each side of the needled fabric or a total number of needle punches per square inch in excess of 22,000.

The foregoing overall bulk density was obtained without any significant deterioration of the fabric during the further needling operation and without any signiflcant damage to the needles of the FIBERWOVEN loom. The fabric had the resilient characteristics of an intensely and randomly entangled fiber structure.

It should be noted that during the further needling operation the needling fluid foamed and formed a lather throughout and on top of the fabric, which foam remained during the further needling operation. The add-ons of the needling fluid did not drop below 100% throughout the entire further needling operation and the add-ons, mainly, were about 150% through the entire further needling operation.

As a comparison with the foregoing, the same process was repeated, except that the needling fluid added to the 8 lbs. per cubic foot fabric was water alone. After only about a thousand additional needle punches per square inch on each side of the fabric, the water had significantly drained from the fabric and needling became ineffective. With continued needling, additional water drained and dried from the fabric and the addons of water fell well below a soaking amount needle breadage and fabric deterioration began to occur.

As noted above, the relationship between the density of the fabric to be further needled and the add-ons required to assist in effective further needling and further intensity of fiber entanglement forms a critical basis of the present invention, i.e., there must be present a soaking amount. However, for precise control of any particular fabric and any particular fibers used therein, this relationship can be specifically determined for fabric of different densities upon which needling commences, as well as the add-ons required during needling where the density is increasing. Thus, for a series of densities and a series of add-ons, it can be'determined where substantial deterioration of the fabric and sub stantial harm to the needles occur and where effective needling and further intensity of fiber entanglement take place. By such a series of experiments, one can determine the relationship between density and add-ons for any particular fabric density prior to or during needling.

The Figure is constructed for a fabric of a nature described in the Example. As can be seen, there is a relationship between the density an the add-o'ns useful in increasing fiber entanglement and bulk density during the further needling operation. At above 8 pounds per cubic foot density, the minimum add-on (soaking amount) for effective needling and further intense entanglement of fibers is plotted, along with the maximum practical add-on that can be conveniently used. Any add-on greater than the minimum is satisfactory. The preferred add-on is also shown. As can be seen from the Figure, the soaking amount of the needling fluid varied inversely with the density of the fabric. Thus, the soaking amount decreases as needling proceeds and the density of the further needled fabric increased. For the preferred needling fluids, i.e., aqueous solutions of surface-active agents, thickeners, foaming agents, etc., a fabric, initially provided with at least a soaking amount of needling fluid appropriate for the initial density of the fabric and promptly needled, will retain a soaking amount during the further needling, since the soaking amount decreases with increased fabric density and thereby compensates for mechanical loss of needling fluid during the further needling. On the other hand, if the further needling is delayd or interrupted, it will be necessary to re-apply the same needling fluid to restore at least a soaking amount to the fabric before needling commences.

EXAMPLE 2 A needled batt was prepared according to the process of Example 1 having a bulk density of 7% lbs. per cubic foot. The batt was treated with a 0.13% (by weight) water solution of locust bean gum (Polygum- 260, Polymer Industries, Inc.). The treated batt was then needled essentially in the same manner as that according to the further procedure of Example 1 and the resulting needled product has a bulk density of 12 lbs. per cubic foot and the other physical properties were similar to that of the product of Example 1.

The locust bean gum functioned, essentially only, as a thickening agent and no substantial foaming took place. The locust bean gum did not, however, sufficiently change the wetting" properties of the water so as to render the solution a non-wetting fluid.

It should be understood, however, that while the different additives, e.g. surface-active agent, foaming agent, thickener, etc., will allow the needling to proceed to higher densities and produce similar products, the products resulting from the different needling fluids are not always identical. The different needling fluids can produce somewhat different fiber entanglements and, for this reason, one additive may be chosen over another, or combinations thereof, for making special products.

What is claimed is:

1. A method for producing a highly needled textile fabric comprising:

1. first needling a textile fabric;

2. treating the needled fabric with a soaking amount of a wetting needling fluid and until add-ons of at least are obtained; and

3. further needling the treated fabric while maintaining the soaking amount and the at least 100% add ons of the wetting needling fluid to increase the overall bulk density of the needled fabric.

2. The method of claim 1 wherein the treated fabric is needled to a density of at least 10 lbs. per cubic foot.

3. The method of claim 2 wherein the treated fabric is needled to a density of at least 12 lbs. per cubic foot.

4. The method of claim 3 wherein the needling fluid is an aqueous fluid containing a surfaceactive agent or thickening agent or combinations thereof.

5. The method of claim 4 wherein the needling fluid contains a foaming agent.

6. The method of claim 1 wherein the fabric is dipped into the needling fluid and then passed through nip rolls to remove excess fluid.

7. The method of claim 1 wherein the fabric is saturated with the needling fluid.

8. The method of claim 1 wherein the add-ons maintained during the further needling are at least and less than 300%.

9. The method of claim 8 wherein the add-ons maintained during the further needling are between about and 250%.

l0. The method of claim 1 wherein the said density of the first needled fabric prior to treating with the needling fluid is at least 8 lbs. per cubic foot.

11. The method of claim 10 wherein the density of the first needled fabric prior to treating with the needling fluid is less than 10 lbs. per cubic foot.

12. The method of claim 1 wherein the needling fluid is an aqueous fluid.

13. The method of claim 12 wherein the needling fluid is an aqueous fluid containing a surface-active agent or thickening agent or combinations thereof.

14. The method of claim 13 wherein the aqueous fluid contains a surface active agent.

15. The method of claim 13 wherein the aqueous fluid contains a thickening agent.

16. The method of claim 14 wherein the aqueous fluid contains a foaming agent.

17. The method of claim 16 wherein the aqueous fluid foams during the furthei needling.

18. The method of claim 1 wherein the needling fluid is washed from the further needled fabric after the further needling is completed.

19. The method of claim 1 wherein the treated fabric is needled by mutiple passes through at least one needling zone.

20. A method for producing a highly needled textile fabric comprising:

1. first needling a textile fabric until the overall bulk density of the fabric is at least approximately 7 lbs. per cubic foot;

2. treating the needled fabric with a soaking amount of a wetting needling fluid to increase the overall bulk density of the needled fabric to at least 10 lbs. per cubic foot;

whereby the fabric is further needled to produce an intensely and randomly entangled fiber structure and without substantial deterioration of the fibers of the fabric.

21. The method of claim 20 wherein the treated fabtie is needled to a density of at least 12 lbs. per cubic foot.

22. The method of claim 21 wherein the treated fabric is needled to a density of at least 14 lbs. per cubic foot.

23. The method of claim 20 wherein the needling fluid is an aqueous fluid containing a surface-active agent or thickening agent or combinations thereof.

24. The method of claim 23 wherein the needling fluid contains a foaming agent.

25. The method of claim 20 wherein the fabric is dipped into the needling fluid and then passed through nip rolls to remove excess fluid.

26. The method of claim 20 wherein the fabric is saturated with the needling fluid.

27. The method of claim 20 wherein the fabric is treated by the needling fluid until add-ons of at least are obtained and add-ons of at least 100% are maintained during the further needling.

28. The method of claim 27 wherein the add-ons maintained during the further needling are at least and less than 300%.

29. The method of claim 28 wherein the add-ons maintained during the further needling are between about and 250%.

30. The method of claim 27 wherein the said density of the first needled fabric is less than 10 lbs. per cubic foot.

31. The method of claim 30 wherein the density of the further needled fabric is at least 12 lbs. per cubic foot.

32. The method of claim 20 wherein the needling fluid is an aqueous fluid.

33. The method of claim 32 wherein the needling fluid is an aqueous fluid containing a surface-active agent or thickening agent or combinations thereof.

34. The method of claim 33 wherein the aqueous fluid contains a surface active agent.

35. The method of claim 33 wherein the aqueous fluid contains a thickening agent.

36. The method of claim 34 wherein the aqueous fluid contains a foaming agent.

37. The method of claim 36 wherein the aqueous fluid foams during the further needling.

38. The method of claim 20 wherein the needling fluid is extracted or washed from the further needled fabric after the further needling is completed.

39. The method of claim 20 wherein the treated fabric is needled by miltiple passes through at least one needling zone.

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Claims (42)

1. A method for producing a highly needled textile fabric comprising: 1. first needling a textile fabric; 2. treating the needled fabric with a soaking amount of a wetting needling fluid and until add-ons of at least 100% are obtained; and 3. further needling the treated fabric while maintaining the soaking amount and the at least 100% add-ons of the wetting needling fluid to increase the overall bulk density of the needled fabric.

2. treating the needled fabric with a soaking amount of a wetting needling fluid and until add-ons of at least 100% are obtained; and

2. The method of claim 1 wherein the treated fabrIc is needled to a density of at least 10 lbs. per cubic foot.

2. treating the needled fabric with a soaking amount of a wetting needling fluid to increase the overall bulk density of the needled fabric to at least 10 lbs. per cubic foot; whereby the fabric is further needled to produce an intensely and randomly entangled fiber structure and without substantial deterioration of the fibers of the fabric.

3. further needling the treated fabric while maintaining the soaking amount and the at least 100% add-ons of the wetting needling fluid to increase the overall bulk density of the needled fabric.

3. The method of claim 2 wherein the treated fabric is needled to a density of at least 12 lbs. per cubic foot.

4. The method of claim 3 wherein the needling fluid is an aqueous fluid containing a surface-active agent or thickening agent or combinations thereof.

5. The method of claim 4 wherein the needling fluid contains a foaming agent.

6. The method of claim 1 wherein the fabric is dipped into the needling fluid and then passed through nip rolls to remove excess fluid.

7. The method of claim 1 wherein the fabric is saturated with the needling fluid.

8. The method of claim 1 wherein the add-ons maintained during the further needling are at least 125% and less than 300%.

9. The method of claim 8 wherein the add-ons maintained during the further needling are between about 150% and 250%.

10. The method of claim 1 wherein the said density of the first needled fabric prior to treating with the needling fluid is at least 8 lbs. per cubic foot.

11. The method of claim 10 wherein the density of the first needled fabric prior to treating with the needling fluid is less than 10 lbs. per cubic foot.

12. The method of claim 1 wherein the needling fluid is an aqueous fluid.

13. The method of claim 12 wherein the needling fluid is an aqueous fluid containing a surface-active agent or thickening agent or combinations thereof.

14. The method of claim 13 wherein the aqueous fluid contains a surface active agent.

15. The method of claim 13 wherein the aqueous fluid contains a thickening agent.

16. The method of claim 14 wherein the aqueous fluid contains a foaming agent.

17. The method of claim 16 wherein the aqueous fluid foams during the further needling.

18. The method of claim 1 wherein the needling fluid is washed from the further needled fabric after the further needling is completed.

19. The method of claim 1 wherein the treated fabric is needled by mutiple passes through at least one needling zone.

20. A method for producing a highly needled textile fabric comprising:

21. The method of claim 20 wherein the treated fabric is needled to a density of at least 12 lbs. per cubic foot.

22. The method of claim 21 wherein the treated fabric is needled to a density of at least 14 lbs. per cubic foot.

23. The method of claim 20 wherein the needling fluid is an aqueous fluid containing a surface-active agent or thickening agent or combinations thereof.

24. The method of claim 23 wherein the needling fluid contains a foaming agent.

25. The method of claim 20 wherein the fabric is dipped into the needling fluid and then passed through nip rolls to remove excess fluid.

26. The method of claim 20 wherein the fabric is saturated with the needling fluid.

27. The method of claim 20 wherein the fabric is treated by the needling fluid until add-ons of at least 100% are obtained and add-ons of at least 100% are maintained during the further needling.

28. The method of claim 27 wherein the add-ons maintained during the further needling are at least 125% and less than 300%.

29. The method of claim 28 wherein the add-ons maintained during the further needling are between about 150% and 250%.

30. The method of claim 27 wherein the said density of the first needled fabric is less than 10 lbs. per cubic foot.

31. The method of claim 30 wherein the density of the further needled fabric is at least 12 lbs. per cubic foot.

32. The method of claim 20 wherein the needling fluid is an aqueous fluid.

33. The method of claim 32 wherein the needling fluid is an aqueous fluid containing a surface-active agent or thickening agent or combinations thereof.

34. The method of claim 33 wherein the aqueous fluid contains a surface active agent.

35. The method of claim 33 wherein the aqueous fluid contains a thickening agent.

36. The method of claim 34 wherein the aqueous fluid contains a foaming agent.

37. The method of claim 36 wherein the aqueous fluid foams during the further needling.

38. The method of claim 20 wherein the needling fluid is extracted or washed from the further needled fabric after the further needling is completed.

39. The method of claim 20 wherein the treated fabric is needled by miltiple passes through at least one needling zone.

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