US1898601A - Clothlike fabric - Google Patents

Description

Feb. 2l, 1933. l M. J. sHoEMAKER 1898601 CLOTHLIKE FABRIC Filed Aug. 18, 1930 Patented Feb. 21, 1933 UNITED sTATEsvPATl-:NT OFFICE MILTON J. SHOEMAKER, OF MADISON, WISCONSIN, ASSIGNOR TO C. F. BURGESS LABORATORIES, INC., OF MADISON, WISCONSIN, A CORPORATION OF DELAWARE CIIOTIILIKEk FABRIC Application led August 18, 1930. Serial No. 476,017.

This invention relates4 to the production and composition of cloth like fabrics produced from unwoven fibers.

The object of this invention is to produce a soft and flexible water absorbent fabric of unwoven fibers, such as wood pulp, which is cheap,`washable and resistant'to disintegration.

This invention, which is animprovement over the invention claimed and described in the application of Milton J. Shoemaker, Serial No. 299,454, filed August 13, 1928, issued as U. S. Patent No. 1,786,781, December 30, 1930, covers a method of making fabrics from unwoven fibers such as wood pulp which are water absorbent and may be used as wash cloths, towels, napkins and thelike without disintegrating when wetted. Furthermore, the fabric which is described and claimed may be washed in the usual way without disintegration.

At the present time towels are made of paper but such towels are without strength when wet and must be discarded after being used. The resistance to disintegration by water of such towels may be increased by hydrating some of the pulp by prolonged beating. This increased resistance to disintegration is obtained, however, at a-sacrifice of pliability and speed of absorption of water. Such towels cannot be used as wash cloths. Consequently, wash cloths are made almost exclusively of knitted or woven fabrics. With my process I produce a satisfactory wash cloth from unwoven fibers which need not be hydrated mechanically.

Ordinary fibers, especially cellulose fibers such as wood pulp, when felted into a sheet such as soft absorbent paper, have little strength when wet with water. Such a paper may be coated with a sizing material or a varnish to increase the water resistance. However, the water absorption is decreased thereby as varnish, lacquers and the like are water repellant. The utility of the product is decreased thereby. If viscose or other cellulose ester as described in the aforesaid Shoe`- maker patent is substituted for varnish and the like and the. cellulose then regenerated in the usual manner, the fibers are held in an in soluble mass of regenerated cellulose which does not disintegrate in water. In contrast to the water repellant nature of varnish, lacquer and the like, the regenerated cellulose is water absorbent, so that the impregnated sheet loses little or none of this desirable property. However, if the sheet is coated over its entire surface the resulting product is not soft and pliable but is stiff and crackles much like paper. In the Shoemaker -patent the cellulose is applied in discontinuous films as hereinafter described and a soft and pliable cloth like fabric results. I have discovered that if an hydroxy-alphyl ether of cellulose is employed like the viscose vor cellulose ester of Shoemaker, further advantages are obtained.

The hydroxy-alphyl ethers of cellulose used 1n my invention may be made as described in a series of applications of Arlie W. Scliorger, Serial Numbers 47 5,249 filed August 14, 1930, 475,250 filed August 14, 1930, 475,251 filed August 14, 1930, 477,752 filed August 25, 1930, (now Patent No. 1,863,208 granted June 14, 1932), and 477,753 filed August 25, 1930, each of said applications being entitled Manufacture of ether derivatives of carbohydrates like cellulose.

In said applications the ether may be prepared by subjecting alkali cellulose, preferably soda cellulose, to the action of an olefine oxide. The oxides at the lower end of the seriesmthat is, those of ethylene to amylene inclusive, apparently produce the most practical cellulose derivatives. Of these the oxides of ethylene and propylene are preferred, especially the former because it is a soda cellulose. This ether y, resembles the hydroxy-ethyl ether closely.

When ethylene oxide or ethylene chlorhydrin is used it is preferable to keep the ethylene oxide content of the final product below 20% of the cellulose used or substantially less than one molecule of oxide to one unit of cellulose (CBHNOS). In this range, an ether containing less than one molecule of ethylene oxide to two units of cellulose is preferable and especially one contalning one molecule of oxide to three to four units of cellulose, that is, from 7% to 9%. Such ethers, high in cellulose units, are cheaper because of their relatively high cellulose content, are stronger, are more resistant chemically, are easier to handle, are insoluble 1 n water, have a limited Asolubility in caustlc soda solutions, that is, they are not soluble in all strengths of solutions, and are practically insoluble in caustic potash solutions.

As aneXample of my invention, an hydroXy-ether containing from 7 70 to 9% of ethylene oxide is dissolved or dispersed (since these ethers apparently form colloidal solutions in the caustic alkalies) in a solution of 71/70 to 8% sodium hydroxide so that the solution contains from 6% to 7% of the ether. Its viscosity is adjusted by regulating the age of the alkali cellulose as set forth in said Schorger applications and as is well known to those skilled in the art of making various cellulose esters and ethers. Other hydroxyalphyl ethers may be used, the solutions being prepared with due regard for the varying properties of these ethers.

The discontinuous film of hydroxy alphyl ethers of cellulose may be obtained by applying the ether dissolved in a caustic alkali solution, and especially caustic soda solution for the preferred ethers, 4from which the ether is subsequently precipitated. The properties of the ether are varied to suit the fibrous product which is to be impregnated but should in general slowly penetrate the sheet without fiooding. The fibers which are used are preferably cellulosic. Wood fibers are especially suitable because of their cheapness and availability. Sincethe product is to be water absorbent it is best to use sheets of wood fibers or pulp which contain little or no sizing and which are not calendered. It is also preferable to use a long fibered stock for reasons which will become apparent as the process is described further. Long fibered pulp may be made from spruce, tamarack or jack pine. Spruce. is especially suitable since it not only is long fibered but it yields when bleached a product of high white color which is usually desirable. Various special treatmentsof the fibers or the sheeted fibers may be carried out to modify the physical properties of the fibers, such as the absorption qualities.

In the accompanying drawing thel nyention is illustrated by one exemplary embodiment thereof but it will be understood that the invention is not to be considered as limited by the illustrated disclosure.

Fig. 1 is an illustration of' the simplest form of' my invention with a' portion broken away and somewhat further enlarged more clearly to show the structure of the sheet,

Fig. 2 is a transverse sectional View of the sheet shown in Fig. l along line 2-2 thereof, and along lille 2-2 of Fig. 3,

Fig. 3 is a sectional view along line 3--3 of Fig. 2,

Fig. 4 is a transverse sectional'view of a composite sheet comprising two of the sheets of Fig. 1 superimposed upon each other,

Fig. 5 is a sectional view along line 5--5 of Fig 4,

Fig. 6 is a transverse sectional view of a modified form of my invention,

Fig. 7 is a sectional View along line 7-7 of Fig. 6. Y

T o make a thin product suitable for towels and napkins, I use for the base a thin sheet 1, of suitable fibers such as bleached sulphite pulp. A sheet weighing from .07-.09 lbs. per square yard gives excellent results. I coat this sheet with a discontinuous film of the hydroXy-alphyl ether preferably of the concentration and quality hereinbefore described. The discontinuous film may be produced in any one of a number of ways. I prefer applying itin the form of lines 2 by means of a corrugated roller the ridges applying the cellulose ether to the sheet. For the above longfibered sulphite pulp a coater of 12 lines per inch with ridges .025 inches wide may be used with an ether of the previously described quality. The ether is thereby applied discontinuously over the sheet and if it is of the correct viscosity it does not flood the space between the lines. It spreads only slightly on either side of the lines. also through the sheet. The areas between the lines of ether are substantially free from ether but most of the uncoated fibers are anchored at one or the other end in the contiguous lines of impregnating cellulose ether. The lines may be straight as shown or they may be in the form of curves or any other desired configuration or pattern. The ether may also be applied in the form of a series of dots. Other methods will suggest themselves to those skilled in the art. I do not wish to be limited to the exact methods described but comprehend any method which gives a product which has the ether distributed discontinuously throughout the sheet forming fibrous areas substantially free from the ether. Most of the fibers in the unimpregnated areas being anchored by contiguous portions of the ether.

Although a suitable product may be made by impregnating the pulp sheet on one side in discontinuous areas with an hydroXy-alphyl ether of cellulose, I prefer to impregnate both sides of the sheet in asimilar manner. If one side of the sheet has been impregnated with parallel lines of ether as hereinbefore described and as illustrated in Fig. 2 I then impre ate the other side in the same way except t at the impregnating lines 3 as shown in Fig. 3 are substantially at right angles to the lines 2 on the first side. reinforcement of impregnated cellulose ether in the form of lines, squares, or other configurations. This produces a product of excellent strength and anchors practically all of the fibers 4 of the unimpregnated areas on both sides of the sheet. In general the maximum dimension of the unimpregfnated areas is bt most equal to the average length of the The impregnated sheet is then passed through the various baths for precipitating and washing the`cellulose ether. It isat this l stage of the manufacture of the cloth like fabrics that the advantages of the hydroxyalphyl ethers of cellulose over viscose become apparent. The fabric needs merely to be dipped into a precipitating bath to precipitate the ether after which it is washed free of the precipitating bath. On the other hand, when viscose is used as disclosed in the -earlier application, the fabric has to be first run into a precipitating bath then desulphurized and then bleached and washed. The procedure necessary with the hydroxy-alphyl ether is less strenuous, affects the fabric less, and is more economical in time, material and apparatus. No odors or poisonous gases are liberated when the hydroxy-alphyl' ether is used. In the case of viscose, the large quantities of sulphur in the impure coagulated product must be eliminated. This requires a number of Washing operations.

A suitable precipitating solution may be dilute sulphuric acid or it may be any other suitable acid or combination of salts as is well known in the art. Asolution containing 68% water, 20% sodium sulphate and 12% sulphuric acid is suitable. An ammonium sulphate bath ma be used followed by a dilute mineral aci bath instead of the above bath. The fabric is then passed into about 0.2% caustic soda after which it is washed in water. The-fabric may be driedbut I prefer to pass it through an emollient bath. Various emollients may be used such as'glycerine alone or associated with other materials, paraffin, oil, etc. I prefer to use a bath containing about 1% soap, such as the brand Ivory, 2% sulphonated castor oil and 4% glycerine. The fabric retains a small portion of this emollient which softens it, thereby producing. a/ fabric with a soft cloth like texture. y

The fabric may be d ied either before or after passing it throug' the emollient solution.' After the treatment to introduce emol- '66 lient thesheet is f rstvsqueezed as, dry asl pos- This results in a` ether sible. Iip'referto dryit vunder-slight ten- 3, 5 and 7. -This gives the abric apleasing appearance and a feel similar to a woven fabric which is desirable. The fabric may be colored and embossed to give pleasing effects similar to those of woven fabrics.

A paper towel made in the above manner has a decided advantage over ordinary paper towels in that it is non-linting, highly absorbent, and has a higher wet strength. Such a towel made from thin pulp sheets weighing from .07 to .09 pounds per square yiard may contain'from 7.0 to 8.0 grams of per 'square yard when coated on Vboth sides.

The above procedure is satisfactory for thin fabrics. For heavier fabrics, such as wash cloths and pads, the procedure and raw materials are changed somewhat. I prefer making a heavy fabricby packing several thin fabrics such as fabrics 6 and 7 shownV .in Figs. 4 and 5 and pressing them into a unitary structure, the cellulose ether'8'with which they are lined serving as the adhesive to cement the several sheets together. A

' heavy single fabric offibers-cannot be impregnated thoroughly 'without flooding thetop surface as'the cellulose ether travels more readily along the surface ibers,'which are in general in paralle relation tothe surface of the sheet. Such a heavy fabricmay therefore. have an unsaturated plane in the center along which it will cleave readily when used inthe wet condition; The impregnating` agent should penetrate sufficiently inwardly from the surface toward the opposite .surface-to prevent such cleavage.

In one method of carrying out m invention in, which the hereinbefore descrlbed viscous cellulose ether solution is 'used in conjunction with a plurality of cellulosic ber sheets, I prefer using as the fabric base a pulp sheet i) (see Figs. 6 and 7) which is heavier than those previously described. I

l,prefer to use mercerized bleached ,sulphite stock instead of using a pulp sheet o f .07 to .O9 pounds per square yard. I use a sheet weighing from .15 to .17 pounds per square ard. f y I pass this heavier-sheet through the hereiribefore described coating machine and line or otherwise coat one side of said pulp sheet with a discontinuous film 11 of cellulose ether. Aesecond'sheet 10 of similar pulp but weighing .07 'to .09 lbs. per sq. yd. is then Y placed on the coated side of the heavier rst sheet and said stacked sheets are then pressed through squeeze rolls which cause the two sheets to adhere firmly to each other since the cellulose ether on the heavier sheet penetratesthe bers of the thinner sheet and causes adherence between the two sheets.

The above composite sheet is then passed through the coater to line or otherwise coat the two outside surfaces with film12 of ether, the pattern preferably being applied in a direction at right angles to the rst coat. This insures the roper anchoring .of the fibers in the ummpregnated areas. The sheet may then be passed through the cellulose ether precipitating, washing and other baths as described previously. Instead of using the two -pulp sheets as described, additional thin sheets of pulp may be added by the same'method before precipitation and the fabric built up by the same procedure into any desired `thickness. Two sheets, one thick and one thin, are suicient to serve as a wash cloth. By this method the final product consists of a plurality of sheets of unwoven fibers which have a reinforcement comprising precipitated cellulose ether distributed discontinuously throughout the sheet and forming brous areas or sections substantially free from the I ether, most of the fibers in the unimpregnated The wet fabric sheets t areas or sections being anchored by contiguous portions of the ether. The reinforclng material extends in all directions and cements or ties the sheets together into a unit. The hydroxy-alphyl ethers used have a further advantage over the regenerated cellulose obtained from viscose in that these ethers when wet may be stretched. as much as 50% before tearing as against 8% to 10% for the regenerated cellulose previously referred to. erefore may be abused to a greater extent while wet if the hydroxyalphyl ethers are used. After drying the hydroxy ether of cellulose is much more pliable than the sheet having cellulose material regenerated from viscose. As a result l cerine or other emollient is not essential` wlt the fabric made with the cellulose ether reinforcing, whereas it is important with the regenerated cellulose. The invention is not limited to the process above described for adding the hydroxy-alphyl ether cement to the bers. It is not necessary to produce a regular relation of.the cementing areas as exemplified by` lines or dots mechanically applied, for it is contemplated that a spray', controlled in character and in proportion to ber be applied' to felted fibers or to individual fibers or groupsl of fibers to be felted or in process ofbeing felted so that contacting sections of fibers or a frac-- tional portion of the bers are cemented together in the nished product, leaving a sub-l.

It will be noted that whatever method is employed, the sheet or mass which results is supported by a continuous network of celclaims Ihave used the term al hyl as indi-- cating a radical of the aliphatlc series inasmuch as the term alkyl which is sometimes used to make this distinct reference is frequently indicative of both aliphatic and aromatic radicals. The term alphyl is specic to the aliphatic series in the same manner as aryl is specific to the aromatic series. See Richters Organic Chemistry vol. 1, page 43, first English edition, 1916,.

Various other modications of the process and of the product are contemplated as coming within the scope of the invention as dened by the appended claims.

I claim:

1. A reinforced, water-'absorbent sheet of unwoven fibers, the reinforcing material comprising a water. insoluble hydroxy-alphyl ether of cellulose distributed discontlnuously throughout said sheet forming brous areas substantially free from said ether, most of the bers in said areas being anchored by contiguous portions of said ether.

2. A reinforced, water-absorbent sheet of unwoven cellulosic bers, the reinforcing material comprising hydroxy-alphyl ether of cellulose containing substantially less than one hydroxy-alphyl radical to one unit of cellulose distributed discontinuously throughout said sheet forming fibrous areas substantially free from said ether, a substantial porred los terial comprising an hydroxy-cth l ether of l cellulose containing a lhydroxy-et yl radical and cellulose units in a range of ratios from' one to three to one tofour distributed continuously throughout said sheet forming fibrous areas substantially free from said .ether, the-maximum dimensions of said areasl being at most equal tothe average length of said bers, said sheet being impregnated with a sma`l amount of emollient'.

5. A brous sheet comprising water absorb-v ent cellulose bers, fractional portionsof 1n- 13o dividual bers being cemented together by an hydroxy-a1 hyl ether of cellulose containing substantia y less than one hydroxy-alphyl radical to one unit of cellulose into a supporting network to leave uncemented substan-V tial portions of said cemented bers. f

6. A fibrous cellulosic material in an a gregate of bers having portions of single bers cemented to portions of `other single bers by an hydroxy-alphyl ether of cellulose, whereby to unite the aggregate into a cemented whole.

.In testimony whereof, I have subscribed my name.

MILTON J. SHOEMAKER.

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