US3458911A - Method of making papermakers' felt - Google Patents

Description

Aug. 5, 1969 J. F. KOESTER METHOD OF MAKING PAPERMAKERS' FELT Original Filed Dec. 7, 1964 mvmron JOHN P. KOESTER @M/ @ziif United States Patent 3,458,911 METHOD OF MAKING PAPERMAKERS FELT John P. Koester, Piqua, Ohio, assignor to The Orr Felt & Blanket Company, Piqua, Ohio, a corporation of Ohio Original application Dec. 7, 1964, Ser. No. 416,273. Divided and this application Mar. 17, 1967, Ser. No. 623,968

Int. Cl. D04h 18/00; D06c 1/00; D02g 1/16 US. Cl. 28-72.2 3 Claims ABSTRACT OF THE DISCLOSURE A papermakers felt and method of making the same is disclosed in which a woven base material is woven with soluble filler yarns formed of calcium alginate and which are removed after battings have been needled into the base material to form a finished felt substantially free of crosswise structure.

This application is a division of application Ser. No. 416,273, filed Dec. 7, 1964 now abandoned, of which Ser. No. 643,527 is a continuation issued as US. Patent No. 3,401,467 on Sept. 17, 1968.

The surface characteristics of a papermakers felt has a direct bearing upon the finish and quality of paper formed thereon. It has been suggested that if a felt were made with warp yarns only, and with bats of fibers needled into these yarns, a finished felt would be formed which has no filler yarns and therefore has no cross over points or knuckles to mark on finished paper. It has been considered that such a fillerless felt would more nearly approach the ideal papermakers felt to the extent that it would emboss fewer or less prominent felt marks on the wet paper sheet. Athough it is well known that the stock furnished to the paper making machine has an effect on the degree of marking, such a felt would allow the paper maker a Wider latitude in the selection and preparation of the stock.

It has further been thought that a felt which has no filler yarns would exhibit improved drainage characteristics since there would be a less tortuous path for the water to flow through the felt. First, such a felt would offer less resistance to water flow since the water would not meet the high resistance areas of the filling yarn. Second, such a felt could be thinner by reason of the absence of the filler and because of this thickness, the water could flow through more easily.

A fillerless felt would also, at least in some instances, have improved wear resistance. Many conventional felts tend to wear at the cross over points of the warp and filling yarns due to the high pressures at these points." Obviously, this would not occur in a felt which has no filler yarns.

Suggestions have been made for manufacturing a felt without a filler yarn. Such suggestions presuppose an endless array of warp yarns which are somehow formed, and held in proper spatial side-by-side relationship, while a non-woven batting is needled into the array. Both adjacent loop placement and helix winding the warp yarns have been suggested. However, no practical warp forming machine has been described for this purpose. Therefore, no practical or commercial method has been suggested by which a fillerless belt or base may be formed and handled in the lengths and Widths which are required for paper making machines. There would be a difficult problem in forming a parallel array of warp yarns without filler at the proper length and width, and in holding them without twisting, or crossing over of adjacent yarns, and maintaining proper tension throughout to permit sub- 3,458,911 Patented Aug. 5, 1969 sequent handling and needling. The filler material in a conventional woven felt performs an invaluable service in permitting the initial forming and handling of the felt, conventional splicing into an endless belt of desired length, and maintenance of the relationship of the warp yarns prior to and during the needling operation.

The method of this invention and the felts produced thereby includes the weaving of a base material of the desired warp yarns with a filler yarn which is removable in one of the finishing operations of the felt after the felt has been needled. In the preferred embodiment of this invention, a woven base material is formed using the desired warp yarns in a Weave including a filler yarn, at least a substantial portion of which is selectively soluble or removable, as by a solution or liquid which is harmless to the warp yarns and batting. Such a filler yarn may be formed of continuous filament calcium or sodium alginate. It may also be formed of slit and twisted soluble film material such as a polyvinyl alcohol. The woven base material may then be handled in the conventional manner. Such a base material may then be needled to apply one or more bats of non-woven fibres into the base material, interlocking the same with the Warp yarns and providing the desired surface characteristics and resistance to widening. Subsequent to such needling, the felt is dewoven by the removal of the filler material in a suitable solvent. A dewoven and fillerless felt is accordingly formed which may then be subjected to any other desired finishing operations such as washing, fulling, heat treating and the like.

It is accordingly an important object of this invention to provide an endless papermakers felt which has been de-woven after needling to remove part, if not all, of the filling yarns.

A further object of this invention is to provide an improved process for making a fillerless endless papermakers felt.

A still further object of this invention is the provision of a method of manufacturing an endless papermakers felt which, when finished, has only a warp yarn system combined with needled, non-woven battings.

A still further object of this invention is the provision of a method for making an endless papermakers felt by initially supporting the warp yarn structure using a woven and soluble filler material, such as calcium alginate, and removing the same after it has served its purpose, and the provisions of a product manufactured by such process.

A still further object of this invention is the provision of a de-woven endless papermakers felt which has had the filler yarns removed and which has been provided with an arrangement of needled batting material to pro- -vide sufiicient crosswise strength or resistance to widening for operation on a paper making machine in the absence of such filler yarns.

A further object of this invention is the provision of an article of manufacture which is useful as an intermediate product in the manufacture of a papermakers felt which includes a woven base material of a plurality of warp yarns which are held in parallel array by a filler formed at least in part of calcium alginate fibers or other easily and selectively removable fibers as by solvents or otherwise and which woven material is joined as by weaving as a tube or by splicing at its opposite ends to form continuous warp yarns in an endless belt.

These and other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings:

FIG. 1 is a perspective view of a portion of an endless papermakers felt showing the application of a non-woven batting on a needling loom to a base material made in accordance with this invention;

FIG. 2 is a fragmentary perspective, partially broken away view of the one of the products of this invention showing the felt after needling and before the removal of the filler yarns;

FIG. 3 is a perspective view, partially broken away, similar to FIG. 2 following the removal of the filler yarns; and

FIG. 4 is a fragmentary perspective view, partially broken away, similar to FIG. 3, showing a slightly different form of the invention.

Referring to the drawings which illustrate a preferred embodiment of the invention, a woven base material made in accordance with this invention is illustrated generally at 10 in FIG. 1. This base material comprises conventional warp yarns 12 which are more clearly seen in FIGS. 2 and -3. The warp yarns 12 are chosen to provide the desired tensional strength and weight lengthwise of the belt, and are further chosen with regard to the desired material, thickness and weight of the same as is known in the art. Woven into the base 12, such as by a conventional loom, are filler yarns 14. The filler 14 is preferably formed of a selectively soluble material or a material which may be removed by subjecting the felt to a suitable solution harmless to the the remaining fibers. Preferably, the filler 14 is formed of filament type calcium aginate which is soluble in soda ash or sequestering solutions which are harmless to the other materials in the finished felt. However, the invention is not intended to be limited thereto as other suitably selectively removable fibers, yarns or slit and twisted films may be used. Also, sodium alginate filaments may be used which are watersoluble.

Preferably, only so much of the filler material 14 is used as necessary to permit ease of handling of the woven base 10. Accordingly, a relatively light filler 14 may be satisfactory for the purpose of permitting the ease of handling, the joining together of the ends of the base material 10 to form an endless belt and the preparation and handling of the same on a needling loom.

It is also within the scope of this invention to blend the soluble filler yarns or fibers 14 with a small amount of insoluble yarns, such as, for instance, a blend of 75% calcium alginate staple with 25% insoluble fibers such as wool or synthetic. When the calcium alginate is removed, residual fibers 14 (FIG. 4) will be retained to provide a soft, strong, and substantially non-marking crosswise structure which will assist in producing a desired crosswise strength or resistance to widening. It is clear that in the absence of the major portion of soluble filling fiber it would be difiicult, if not impossible, to weave in such a small proportion of non-soluble and substantially non-marking crosswise structure of this type.

The base material 10 may be woven in the conventional endless or tubular form in which the warp 12 is actually the filler in the loom. However, this technique is limited both by the size of the loom and the texture density and size of the warp yarns. Accordingly, when longer finished lengths and higher densities are required, the base material 10 may be woven in the conventional manner and formed in an endless belt by splicing the ends together, also in a conventional manner. This results in the individual warp yarns 12 being joined by overlapping at opposite ends so that, in effect, the warp runs in substantially unbroken continuity. Thus, the use of a removable or fugitive filler 14 permits a woven base material to be handled by wholly conventional techniques.

Following the conventional splicing or tubular weaving of the base materials 10 at the desired length, the resulting belt is placed on a conventional needing machine. T this base material there is needled non-woven batting material such as the bats 15 and 16 shown in FIG. 1 by a needle loom 17 to surfaces of the woven base 10. One or more of such bats 15 and 16 may be applied to one face and preferably both the outer and inner faces, as necessary to provide a desired finished characteristic and resistance to widening in the finished felt. It has been found that first bats 15 and 16 of synthetic fibers needled respectively into both the face and the back of the fabric 10, followed by a second bat 18 (FIG. 4) of woolen fibers needled into the face or outer surfaces, and subsequently fulled, provides a superior resistance to widening in the cross-machine direction.

In FIG. 2 there is shown a fragment of the intermediate product of this invention prior to the removal of the filler 14. The bat 15 has been needled to the upper or outer surface which may actually comprise one or more individual bats of synthetic or woolen material and may preferably be formed with an under layer of synthetic with a woolen face bat applied in separate needling steps. A similar needling bat or layer 16 has been needled into the inner or bottom surface of the woven base 10 with the result that the fibers thereof and of the bat 15 are intimately interlocked and mingled one with the other and with the warp yarns 12 and compacted tightly against the base material.

The relationship of the warp yarns is now fixed and held by the needled bats 15 and 16. The filler yarns 14 have now served their purpose and may be removed. If these yarns are formed of calcium alginate fibers, they may be removed by washing the felt in a suitable sequesterene agent or solvent. For instance, the fibers may be removed in an alkaline solution of soda ash (NA CO and common salt (NaCl). However, where fibers in the remaining felt are not resistant to alkaline conditions, a solvent may be employed which uses sodium hexametaphosphate with a small amount of detergent-dispersant and common salt added.

It has been found that after ten minutes of washing the felt in such solutions, preferably at lukewarm temperatures, the calcium alignate filler 14 is completely removed, as shown in FIG. 3. Preferably, the belt is then rinsed, and prepared for any other wet finishing operations, such as fulling and the like. The felt may then be dry finished in the normal manner. The resulting product is one which has been de-woven by the removal of the filler 14, leaving only the warp yarns 12 in fixed predetermined relationship, locked in place within the needled battings applied to the outer and inner surfaces thereof. The parallel relationship of the warp yarns has easily and conveniently been maintained during the critical forming steps. The filler 14 has made possible the conventional handlling of the base material including the important joining or splicing step in which the woven material is formed into an endless belt, and has further maintained the desired relationship during the needling operation.

As an example, and in no way intended to limit the scope of the invention as defined in the appended claims, a felt was made to operate at 49 feet at the finished length, by 40 inches wide. A warp yarn was selected which weighed 250 grains per yards. A filler yarn 14 of pure calcium alginate filament material was used with a weight of grains per 100 yards. The filler yarn was of twoply construction and was a balanced yarn. The felt was woven in a conventional loom with 26 ends per inch and 22 picks.

After the felt base material was woven the ends thereof were joined by splicing in the conventional manner. The felt was then applied to a needle loom using 32 gauge needles. First, a ounce per square foot polypropylene non-woven fiber was anchored to the back of the base material by needling one round at a rate of 400 strokes per minute using 7s inch penetration and inch advancement.

The felt was then turned so that a batting could be applied to the face. This face batting also consisted of of an ounce per square foot of polypropylene and was anchored to the face using the same stroke per minute, penetration and advancement indicated above.

Next, a finishing layer of wool batting was needled to the face. This consisted of one-half ounce per square foot of wool fibers and was needled in at the same rate, penetration and advancement described above.

The felt was then removed from the needling machine and washed in 100 gallons of solution at 120 P. which contained the following:

Calgon solution (sodium hexametetaphosphate)- gal 8 Sequesterene NA-3 (a metal chelate of Geigy Chemical Corp., Yonkers, NY.) lbs 16 Aqua ammonia, 26 Baum gal 2 The felt was washed in this solution for twenty minutes in a conventional felt washing machine running at relativcly low speed. It was then rinsed in warm water in the same machine for twenty minutes. This procedure completely removed all traces of the filler 14. The felt was then acid fulled until it had lost approximately one-half of its woven width, and wet and dry finished in the normal manner.

Laboratory tests have indicated that the de-woven structure made in accordance with the above example exhibited excellent stability. A measurement of stability is the ratio of the width of the felt at two times the running load to its width in a completely relaxed condition. Since there are no filler fibers or yarns remaining in the structure there is little width reaction. This felt had a ratio of 0.986 to one, which may be compared to approximately 0.9 to one for a normal felt. This relatively high stability and resistance to narrowing under tension indicates that the felt, in use has very little tendency to become more narrow when tensioned on a paper machine.

In use, the felt exhibited superior stability both as to width and as to length. The felt went on a paper machine at 42 inches wide and varied less than A of an inch in width when loaded between 110 pounds per linear inch to 340 pounds per linear inch at the press section. This width stability can be attributed to the absence of the filler 14 resulting in minimum width reaction.

The same felt had only a four inch variation in length between running loose and taut on the machine. In the loose condition, the felt was fifty feet, eight inches long, and when it was running taut the felt was 51 feet long. This stability as to length may be attributed to the fact that no crimp remained in the warp after the filler was removed.

The felt produced paper of superior finish with an almost complete absence of any characteristic marking on the paper surface. The felt also has improved wear capabilities in that it has no cross over points or knuckles and, accordingly, no hard spots to accelerate wear.

The above felt made according to this invention also exhibited superior characteristic with regard to shedding. All fibrous products will lose some fiber as they wear. However, many of the sheddable fibers are removed from the felts of this invention during the processing of the felt, and particularly during fulling. This shedding is primarily restricted to the short fibers in the felt which would be of no advantage to the finished felt and which are probably produced by the cutting action of the needles during the needling steps. The sheddable fibers are more easily removed due to the absence of the filling yarns and provides a finished felt which is more resistant to shedding in use.

It is accordingly seen that this invention provides a practical method of making fillerless endless felts on a commercial basis and a superior papermarkers felt.

While the method and products herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to this precise method and products, and that changes may be made therein without departing from the scope of the invention.

What is claimed is:

1. The method of making an endless papermakers felt comprising the steps of forming an endless belt including weaving in a base material, a warp yarn of sufiicient strength to carry the running tension of said felt and a filler yarn formed substantially of a selectively soluble fiber, needling a hat of non-woven essentially insoluble fiber material into each of the inside and the outside surfaces of said endless belt on a needling loom, and removing said soluble filler fibers by washing said needled felt in a solvent for said filler fibers.

2. The method of making a de-woven endless papermakers felt comprising the steps of weaving in a base material, a warp yarn of sufiicient strength to carry the tension of said felt and a filler yarn formed substantially of calcium alginate fiber, splicing the ends of said base material together to form an endless woven belt, needling a hat of non-woven essentially insoluble synthetic fiber material into each of the inside and the outside surfaces of said endless belt, needling in a finishing layer of nonwoven wool on the outside surface thereof to provide fulled strength and resistance to widening of the finished felt, and removing said calcium alginate filler fibers by washing said needled felt in a solvent for such fibers harmless to said warp yarns, said synthetic fibers and said wool.

3. The method of making an endless papermakers felt free of knuckles and cross-overs and having a light cross-wise array of substantially non-marking filler fibers contributing to the crosswise strength of the felt and being too limited in strength for weaving along into the warp yarns, comprising the steps of forming an endless belt by weaving warp yarns with filler yarns to form a base material in which the filler yarns are comprised of a substantial portion of a selectable soluble fiber, together with a relatively light array of insoluble fibers which, by itself, is too limited in strength for weaving along into the warp yarns, needling non-woven batting into said base material, and washing the combined needled batting and base material in a solvent to remove the soluble filler fibers leaving the insoluble fibers in situ as a residual filler.

References Cited UNITED STATES PATENTS 2,409,319 10/ 1946 Speakman et al. 2,898,665 8/1959 Salem et al. 2,907,093 10/1959 Draper. 3,097,413 7/ 1963 Draper 2872.2 X 2,592,154 4/ 1952 Johnson et al. 3,001,262 9/1961 Parker et al.

LOUIS K. RIMRODT, Primary Examiner US. Cl. X.R. 28-76

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