US2589765A - Web carrier and method of making - Google Patents

Description

March 18, 1952 o. w. BERGLUND WEB CARRIER AND METHOD OF MAKING Filed Feb. 17, 1950 INVENTOR ORION w. BERGLUND ATTORNEYS Patented Mar. 18, 1952 WEB CARRIER AND METHOD or MAKING Orion W. Berglund, Dayton, Ohio, assignor to The Orr Felt Blanket Company, Piqua, Ohio, a corporation of Ohio Application February 17, 1950, Serial No. 144,749

4 Claims.

This invention relates to paper making machines and particularly to the endless web or felt that is employed in the machine to convey a wet web of paper pulp from the web forming device to and through the couch and press rolls, and then to the driers.

Felts that are used on the Wet end of pulp handling machines such as paper making machines and the like, are notorious for their relatively short life, the life of the average wool fabric felt being as little as a few hours under heavy service conditions as in making asbestos board, but seldom extending beyond a few weeks, such as six or seven weeks under light service conditions as in making tissue papers. These felts or web carriers are subject to much abrasion and/or chemical action in the various machines in which they are used according to the nature of the pulp being handled and the chemical treatment of the pulp.

In using web carriers on the wet end of pulp handling machines, such as paper making machines, it is essential that the Webs have a high wet tensile strength since they are subject to much stress in the machine. Also, it is essential that the wet web carriers shall allow water to drain freely and rapidly through the web carrier as it passes through the various press rolls of the paper making machines. Further, it is necessary that the Web carriers shall not fill up rapidly with foreign matter and small fibers of pulp which reduce water drainage through the felt or carrier. The foreign matter and pulp must be removed regularly from conventional felts in an effort to maintain any degree of satisfactory drainage of water from the wet pulp since the speed of movement of the pulp web through the machine depends upon rapid water removal from the wet pulp. If water drainage from the pulp Web slows down, the speed of the machine must be reduced since the carry over of water to the driers will be too great for the driers to handle in any given time and obtain a determined dryness in the felt.

In manufacturing wet Web carriers for paper making machines and the like, it is' well-known that only the highest quality wool fibers are used. These are the most expensive wool fibers obtainable and thus the life of the felts or wet web carriers is a substantial factor in the cost of producing paper and other articles made from wet P p.

It is, therefore, an object of this invention to provide a wet web, carrier or felt for use in paper :making machines and the like which will have a greater life, will maintain all the necessary physical characteristics and appearance of the usual papermakers felts that are constructed from all wool fibers or from wool fiber base materials so that there will be no change in the character of paper produced on a machine using a felt of this invention and yet has improved characteristics of water drainage and cleanliness not found in other felts.

It is, therefore, another object of the invention to provide a wet web carrier or felt with an improved wet tensile strength and which will withstand abrasion and chemical action for longer periods of time than conventional papermakers felts without in any way impairing the rate at which water can be removed from the paper pulp through the wet web carriers.

It is also another object of the invention to provide a wet web carrier or felt which will not fill up with foreign matter as rapidly as the usual papermakers felts, and which will stay cleaner longer, thus requiring less often cleaning of the felts. By providing such a felt the down time of a paper making machine is greatly reduced, and in many instances prevented entirely, thus providing a definite economic advantage in the operation of the machine continuously for the production of a greater amount of paper in the same length of time.

These and other objects of the invention are accomplished by impregnating the wet web carrier consisting of a-wool fiber base with a phenolformaldehyde resin solution, preferably an aqueous solution, and curing the resin in the felt. It has been found that wool fiber base wet web carriers or felts after treatment with a phenolformaldehyde resin have a better life, an increase in wet tensile strength and will withstand abrasion and chemical action for a much longer time than untreated wool fiber base felts.

Further, the application of the resin to the felt does not affect or reduce the rate at which water is removed from the wet pulp carried by the web carrier as would normally be expected by the addition of a resin to a porous material, in fact, the water drainage rate is actually improved, and additionally improves during the service life of the felt. Also, the felts do not fill up with foreign matter as quickly as untreated papermakers felts, and after cleaning remain cleaner for a greater length of time. The surface characteristics of the felt and fibers therein are improved to prevent accumulation of dirt and foreign matter by wedging in of the dirt, surface attraction, chemical reaction, puncture and abrasive wear, yet the flexibility of the felt and softness of the wool fibers is not aifected as to effect the characteristics of paper produced thereon. In fact, the phenol reacts with the wool to obtain a physical penetration or impregnation of the wool fibers, resulting in a felt that is not changed as to softness and workability from an untreated felt, and is just as easy to put on a papermaking machine as an untreated felt.

These and other advantages are directly attributable to the impregnation of fulled felts with phenol-formaldehyde resin cured in the wet web carrier or felt. h V

For a full and more complete understanding of the invention, reference may be had to the following description and accompanying drawings wherein:

Figure 1 is a schematic illustration of a paper making machine on which a Web carrier 'of this invention is used on the wet end of the machine.

Figure 2 is a schematic cross-sectional view of a Wet Web carrier illustrating generally the construction of such carriers as woven.

Figure 3 is a cross-sectional view of the Wet web ca'rrier illustrating the compactness of the weave of such carrier after fulling.

Figures 4 to 7, inclusive, illustrate generally the steps of a process for treating the wet web carriers, in which Figure '4 illustrates a fulling step, Figure 5 illustrates an impregnation step, Figure 6 illustrates the step of extracting excess resin solution from the felt, Figure 7 illustrates a drying step, while Figure 8 illustrates a step of curing the resin in the felt.

In Figure 1 there is illustrated a cylinder type of paper making machine in which web carriers are used on the wet end of the machine for conducting a wetweb of pulp through the various steps of processing the paper pulp and for conducting the paper pulp to a'drier. Modern paper making machinery requires high rates of speed of movement of the wet pulp web through the machine to make for eco'nomica1 operation, the pulp being adapted to be picked up by a felt or wet web carrier and then conducted through the machine between a pair of felts for subsequent processing.

In Figure 1, therefore, there is shown a paper making machine that includes a cylinder mold l that rotates in a cylinder vat II. The cylinder vat II is supplied with paper pulp in any conventional manner well-known to those skilled in the art. I v

A lower felt [2- passes over the cylinder mold ll to'pick up pulp from the surface of the cylinder mold, a suitable couch roll l3 being positioned above the cylinder mold to cause the lower felt to engage the cylinder mold and to pick up the wet pulp from the cylinder mold. It will, of course, beunclerstood that any number of cylinder molds can be placed in series to obtain paper of different weights.

The lower felt after picking 'up the wet pulp from the cylinder mold passes over a strain roll l4 and isthen met by an upper felt so thatthe wet pulp web will be carried between the upper surface ofthe lower felt l2 and the lower surface of the upper felt I5. The felts l2 and pass over light pressing rolls l6 and from there the As many baby presses I! may be used as'desired. From 'the baby press 11, or presses; the paper web'arid felts pass through the main press I8, or presses.

As the paper leaves the main press I8, it is generally strong enough to carry itself through the drier I9 which consists of a plurality of usual drier drums 19a.

The speed of production of a paper web in a paper making machine depends upon the amount of water that can be removed from the wet pulp web as it passes through the various presses. The amount of water that is removed from the Wet pulp web in turn depends upon the rapidity with which water can pass through the Web carriers or felts l2 and I5. If the water cannot pass from the wet pulp web, the web will enter the driers with a moisture content that will be too high so that the drier cannot effectively dry the paper web by the time it leaves the end of the driers. As the drying of the web is a critical operation, and the web must leave the driers in a determined dry condition, if too much water is carried through the presses l1 and 18 in the wet pulp web and into the driers I9, the speed of the entire machine must be slowed down to give the driers time to drive the excess moisture from the pulp web.

Thus, it is highly important and critical that the web carriers or felts I2 and i5 pass water rapidly and efficiently to permit the wet pulp Web to enter the driers in as dry 2. condition as possible, thus allowing for maximum speed of operation of the paper making machine.

The use of Web carriers or felts treated in accordance with this invention, in a manner hereinafter described, produces a web carrier or felt through which Water can pass more rapidly than through conventional untreated papermakers felts. In fact, mill operation of felts treated according to this invention, and incorporating the subject of this invention, have per mitted increase in speed of operation of paper making machines as much as 10% without in any way affecting the quality of the paper produced. Further, in the mill operation it has been found that felts incorporating the subject of this invention actually permitted water to pass through the felts at a gradually increasing rate during the life of the felts so that machine operation can actually be increased gradually asthe felt is used during its service life, this characteristic being created in the felt without any loss of other normal characteristics of the felt which in any way effect the quality of the paper produce'd'on the machine.

In Figure 2 there is illustrated one general form of construction of a wet web carrier or felt such as the felts l2 and I5, as for example the felt l2. In the felt l2 there is provided a plurality of warp threads 20 that are of a wool fiber base or all wool threads. Interwoven between the warp threads are the woof threads 2| to give the desired surface finish to the felt; These woof threads 2| are also of a wool fiber base, or of all wool fiber. Many felts are used in an'unnappecl condition, but also many of them are mapped in a manner illustrated at 22. The felt l2 can be Woven on any conventional weaving machine, according to the weave desired and can be subsequently napped to obtain a desiredsurface finish according to the use to which-the felt is put.

The handling of the Wool that'goes into the manufacture of the felt l2 through the weaving operation is according to conventional methods of washing and carding the wool, spinning the yarn and thereafter weavingfthe yarn into a fabric which forms the felt l2; 'rhewoo'l fibers are therefore in their natural condition without treatment to give them any special characteristics. This is all according to conventional practice in the manufacture of papermakers felts.

To produce a felt that is satisfactory for use on a paper making machine, the felt is fulled or shrunk in a fulling machine 25 after it is woven,

'as diagrammatically illustrated in Figure 4. In

this fulling or shrinking operation, the felt is placed. in any satisfactory solution, such as a soap solution, in a tank 20. The felt is caused to pass through an eye 21 which squeezes transversely, that is, across the width of the felt, to shrink the felt in width. The felt is also pressed through a pair of squeeze rolls 2B and delivered to a trap 29 which bunches the felt together lengthwise to shrink it in its longitudinal direction.

The apparatus illustrated in Figure 4 is merely illustrative of a fulling operation, and this operation can be'carried out in any conventional fulling machine.

The fulling operation continues until the felt has reached a stabilized dimensional condition after which no further wetting of the felt will develop shrinkage in the felt. Usualy, a felt is woven to approximately twice its finished width, the fulling operation shrinking the felt to the desired finished width and length, and compacts the felt to the condition illustrated in Figure 3.

After the felts or web carrier has been fulled or shrunk to a dimensionally stabilized condition, and properly dried thereafter, the felt is impregnated with a phenol-formaldehyde resin which is preferably an aqueous solution. This impregnation may be carried out in any desired manner, such as dipping or spraying, but as shown in Figure 5, an impregnating tank 30 is provided to receive the fulled felt 12 for impregnation. The felt 12 passes through an impregnating solution contained in the tank 30 and between the squeeze rolls 31' to obtain a thorough impregnation of the fulled felt.

The phenol-formaldehyde solution in the tank 30 may have a concentration of from to 60%; however, a concentration of from 10 to 25% is preferred. The concentration of the phenolformaldehyde solution can vary over a substantial range, but the important factor is the resin pick-up of the felt as determined by the quantity of resin retained in the felt at the time the felt is subsequently dried and the resin cured therein. The resin pick-up in the felt shall be from to based on the dry weight of the felt, with good average results being obtained when the resin content of the felt is approximately 5% of the dry weight of the felt.

Preferably, the phenol-formaldehyde is of the water soluble type which has an extremely small polymer which permits the resin to penetrate the epidermis of the wool fiber and impregnates the fiber without producing any stiffness in the fiber when the resin is cured.

After impregnation of the felt, excess solution is extracted from it by placing the felt in a conventional centrifuge 40, such as shown in Figure 6 until the felt has a wet pick-up of approximately 50% of solution, depending on the solution concentration, as based on the dry weight of the felt, and. such as will deposit in the felt from to 15% of resin after curing, based on dry'weight of the felt. Resin contents of the felt of from 2 Ao to 15% have been found to be particularly effective with a resin content of approximately 5% of the dry weight of the felt giving effective results at a commercially economical level.

After the felt is extracted to the desired wet pick-up, it is then dried on a suitable drying apparatus 4|, such as shown in Figure 7. The drying apparatus may be provided with a heating drum 42 over which the fulled impregnated felt l2 passes and a drum 43 which acts as a stretching drum to stretch the felt to a predetermined length.

The drum 43 is adjustably carried on suitable supports 44 to adjust the stretched length of the felt concurrently with drying. The drying operation is carried out at a temperature well below the curing temperature of phenol-formaldehyde, and preferably at temperatures of from 150 to 200 F. to avoid any polymerization of the resin during the drying operation.

After drying of the felt, the resin may be cured in the felt to a water insoluble condition in a suitable curing apparatus, such as that illustrated in Figure 8.

In the curing apparatus 50 there is illustrated a heating chamber 5| having a drum 52 therein over which the felt l2 passes. A drum 53 is positioned outside the heating chamber 5| and is adjustably carried on supports 54. The drums 52 and 53 are suitably driven to cause the felt to pass through the heating chamber 5| a sulficient length of time so that curing of the phenolformaldehyde resin can be carried out at temperatures of from 225 F. to 320 F., but preferably at a temperature of 275 F. In the apparatus illustrated in Figure 8 hot air is continuously circulated through the apparatus by the blower 60 to obtain uniform temperature distribution in the chamber and air circulation around and through the felt.

With the felt being cured at a temperature of approximately 275, the resin will cure in approximately 12 minutes, but depending upon the specific nature of the resin, the curing time may vary from 2 minutes to approximately 1 hour. Of course, if the curing temperature is reduced to the lower limit at 225 F., the curing time will increase, and if the curing temperature is increased to the upper limit of 320 F., the curing time will be reduced.

The following examples are given to more clearly illustrate the invention:

Example I A woven, fulled paper making felt was immersed into a 15% aqueous solution of phenol formaldehyde resin sold under the trade name Amberlite PR-50 until it was thoroughly impregnated. Thereafter the felt was squeezed between two rolls to remove excessive impregnant and adjust the resin pick-up to a predetermined quantity. The felt was then cured for 2 hours at approximately 250 F. and the pick-up of the cured resin was determined to be 17% with regard to the dry weight felt. The felt thus impregnated with the cured phenol-formaldehyde resin showed an increase of abrasion resistance to wet condition of over the web abrasion resistance of an untreated felt. Also, the wet tensile strength of the warp and of the filler threads was increased by 27%.

Example II A woven, fulled felt was treated with an aqueous solution of phenol-formaldehyde resin solution, which resin is sold under the trade name of Amberlite PR-50, of concentration of 11%,

'Eritrifugedto 'remove excess liquid, dried and Ebdinbie In ghenol forntialdel' yde resin in the form of a 'lj5 aqi1eous solution wasapplicd to a woven,

'fulled 'paper making felt en eared for 1 hour at ately 230 and "far another hour 285 The resin pick-up airloijnteii to l2 The set abrasion resistance W S increased as 'lfllich as 390% and the Wet 'tii's'iie strength 6f the warptiireadsjincreased by 14%; the web tensileisti e 'gth' of the filler threads was decreased by esteem;

T e phenbl-forrnaldehyde resinappnea to a fulled iiiolieli wccirasric pacemakers felt produces a papermakers felt that 'hasiniproved tensile strength in the warp and W601 threads, has improve tear resistance, better fatigue resistsires, greatly improved abrasion resistance, cone nt' and gradually increasing water drainage throughout thelife of the felt, and produces a felt that is highly bacteria proof. Even low perthereafter at aboiit "cei itages of phenol-formaldehyde resin, such as bfthe'dry'weight' of the felt, added to a felt have bee'ii found to give it good bacteria proofhessJSubsta-ntial elimination of bacterial action iri a feItmaiiesfbr increased life of the felt siiie the Wool fibers are not weakened by such 'a'tiohthereby allowing the full strength of the 5766i libel tob utilized throughout the life of the fiber which life is actually increased by the impregnation with a phenol-formaldehyde resin.

It is'consid'ered that the increased rate of passage "of-"water through a felt treatedfwith a phnol foriiialdehyde resin in accordance with invention isbrought about by the factrthat resin t'ratm'ent'jof the fulled felt causes the 'woo'lth'reads andfibe'rs t'o maintaintheir original shapeduring the entire life of the felt regardless cf the repeated pressure applications triatare' given t6 the'feltin'its many passages through the press rolls ofa paper making machine. The high rate of water removal is maintained even though the service life of the felt is usually doubled underimost all condition of operation in a paper making machine.

This application is a continuation in part application of my co-pending application Serial No. 736,387 filed March 21, 1947, now abandoned.

It will be understood that while there have been described certain specific embodiments of my invention, it is not intended thereby to have it limited or circumscribed by the particular details of product proportions, procedures, materials or conditions herein described in view of the fact that this invention is susceptible to modifications according to individual preference and conditions without departing from the spirit of this disclosure and the scope of the annexed claims.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A bacteria resistant Web carrier for use on 8 wet pulp-handling machines to carry wetpulp through the machine consisting of, [a woven fabric belt having warp and woof threads consisting of a wool fiber base, said belt being fulled to a predetermined dimensionally stabilized condition to provide a support for a wet pulp web with porosity to allow for free passage of water through the belt from the wet pulp web, and a phenol-formaldehyde resin in and impregnat ng said belt cured in situ therein comprising 2% to 15% by weight of the dry weight of the belt which maintains substantially the same free passage of water through the belt during its service life and resists the action of bacteria on the felt.

2. A bacteria resistant web carrier foruse on wet pulp-handling machines to "carry wet pulp through the machine consisting of, a woven fabric belt having warp and woof threadsconsisting of a wool fiber base, said belt, being 'full'ed to a predetermined dimensionally stabilized condition to provide a support for a wet "pulp web with porosity to allow for free passage of water through the belt from the wet pulp web, and a phenol-formaldehyde resin in and impregnating said belt cured in situ therein comprising ,4 to 15% by weight of the dry weight of the belt, said cured resin imparting a bacteria resistant quality to the felt.

3. In a process of making papermaking felts resistant to the action of bacteria, the steps of, weaving a fabric felt from warp and woof threads consisting of a wool fiber base, fulling the Woven fabric belt to a stabilized shrink proof state, impregnating the fulled fabric belt with afph'enolformaldehyde resin solution to deposit in the belt to 15% of resin by weight based on the dry weight of the belt, andsubjecting the impregnated fulled fabricfelt to an elevated temperature to cure the resin in situ in the belt to resist the action of bacteria. v

i. A process of making felts for 'papermaking machines and the like consisting of, Weaving a fabric felt from warp and woof threads consisting of a wool fiber base, fulling the woven fabric belt to a stabilized shrink proof state, impregnating thefulled fabric belt with a phenol-formaldehyde resin solution to deposit in the belt to 15% of resin by Weight based on the fulled'fab r'ic felt to an elevated temperature to cure the resin in situ in the belt thereby obtaining water drainage characteristic through the felt that is rentiered unimpaired throughout the life of the felt'and the felt is rendered resistant to the action of the bacteria. .4

ORION W. BERGLUND.

REFERENCES, CITED The following references are (if record the file of this patent: r

UNITED STATES PATENTS Number

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