US2450409A

US2450409A - Roll cover for textile fiber drafting

Info

Publication number: US2450409A
Application number: US634230A
Authority: US
Inventors: John W Baymiller
Original assignee: Armstrong Cork Co
Current assignee: Armstrong World Industries Inc
Priority date: 1945-12-11
Filing date: 1945-12-11
Publication date: 1948-10-05
Anticipated expiration: 1965-10-05
Also published as: GB637575A

Description

t- 5, 1948- J. w. BAYMILLER 2,450,409

ROLL COVER FOR TEXTILE FIBER DRAFTING Filed Dec. 11, 1945 OIL RESISTANT Vl/L cmwzso SYNTHETIC RUBBER MOD/- FIE'D W/THA/VELECTROLYTE CORK PARTICLES ings in the form of Patented Oct. 5, 1948 ROLL COVER FOR DRAFTING John W. Baymlller,

ter County, Pa.,

Company, Lancaster, Pa.,

Pennsylvania TEXTILE FIBER Manheim Township, Lancasassignor to Armstrong Cork a corporation of Application December 11, 1945, Serial No. 634,230

19 Claims. 1

Reference is had to the accompanying drawings, in which:

Fig. 1 is an elevation and Fig. 2 is a cross-section, respectively, of a test apparatus used in selecting the ionizable materials which are effective when added to synthetic rubbers in accordance withmyinvention; and

Figs. 3 and 4 are perspective views of roll covercots embodying my invention.

This application is a continuation-in-part of my copending applications Serial Nos. 498,680, filed August 14, 1943; 526,380, filed March 14, 1944, and 542,879, filed June 30, 1944, all of which are now abandoned. The invention relates to roll covers or cots for textile fiber drafting machinery used in the drafting of cotton, rayon, worsted and the like fibers. I have discovered that roll covers and cots made of synthetic rubbermay be rendered lap-resistant by the incorpora'tion in the-synthetic rubber of certain electrolytes which are ionizahle in water although not necessarily ionizable in the synthetic rubber itself.

In connection with the drafting of cotton, rayon, worsted and like fibers, it has been found that an unusual tendency exists for the fibers to "lap up" around the drafting roll, and the problem is particularly difllcult in drafting rayon fibers. This problem exists in varying degrees with all types of roll covers with which I am familiar and tends to reduce substantially the field of usefulness of roll covers.

Many attempts have been made to utilize various materials in the formation -of roll covers for textile drafting machinery, such as spinning and drawing frames.. Leather is a material frequently used, Its chief disadvantages reside in its cost, susceptibility to wear, prevalence of damage caused by the clearing of lap-ups from its circumference and the frequency with which replacements are necessary. Cork composition roll covers or cots have been used .to a considerable degree in the textile industry in place of leather.

- uisite resistance to lappin up. Neoprene is not used in the industry at the present time because of its extreme tendency to lap up. Cots of Perbu'nan have been used to some extent, for use with cotton and in certain worsted operations, since only a moderate amount of l-apping up is encountered. Such cots are not satisfactory for rayon fibers and certain cotton fibers, for they lap up excessively when used for drafting such fibers.

l. have discovered that if certain water-ioniza'ble materials or electrolytes are incorporated in certain synthetic rubbers, roll covers of which would normally be non-resistant to lapping u-p, roll covers made of such modified synthetic rubhers are resistant to lapping up under normal conditions of use, that is, under the conditions of humidity and temperature customarily employed in textile mills.

I have also devised a simple test by means of which there may be selected materials which can be incorporated in synthetic rubber to make lapresistant roll covers.

I believe that the lapping behavior of textile cots is connected or relatedto electroklnetic phenomena and that the adhesion of textile fibers to the surface of the cot which causes lapping up depends upon the electrckinetic or zeta potential at the cotsurface. According to electrokinetic theory and experiments described in the literature, when two substances, such as distilled water and glass, are brought into contact, there is an adsorption of charges or ions from the water onto the glass surface, setting up what is known as a Helmholtz electric double layer; Electrokinetic Phenomena, Abramson, 1934; Outlines of Biochemistry, Gortner, second edition, 1938, pages 147-150; Physical Chemistry, Mac- Dougall, revised edition, 1943, pages 686-694. This double layer in the case'just mentioned is believed to consist of a layer of negative charges in water firmly fixed or attached to the glass sur- Their advantage over leather rests in their 1111- tial low cost and the length of service each cot is capable of rendering. These two types of cots comprise the vast majority of all the cots actually used in the textile industry.

Attempts have been made to utilize oil-resistant synthetic rubbers to form the working surfaces of textile fiber draiting roll covers. Such roll covers have beenmade of neoprene (a polymerized chloroprene) and Perbunan (a butadiene acrylonitrile co'poly-mer), two well or zetapotential exists between the two and since the'negative layer and posiknown oil-resistant synthetic rubbers. These materials,,while oil-resistant, do'not possess the reqface, and an adjacent layer of positive charges lying in the water beyond the layer of negative charges and movable with the water. The electrokinetic or zeta. potential is the potential between the layer of charges fixed to the solid surface with respect to the movable charged layer in the water. In the case of a glass -water interface the zeta potential is negative. It is usually expressed in millivolts. Since such electrokinetic layers of char es, tive layer are adjacent to each other, there is an'att'raction between the water and the glass and the two are held comparatively firmly together at the surface of the glass. Proof that there is adhesion of the water to the glass by the mechanism of electrokinetic potential is furnished by measurements of what is called streaming potential." If the water is forced through a capillary tube. the two layers of positive and negative charges will be sheared apart tangentially, and work is performed in the shearing of these two layers. If two electrodes are dipped into the water at the ends of the capillary and these electrodes connected with a wire, it will be found that when the water is mechanically forced through the capillary tube the work necessary to shear the double layer apart is manifested by a current flowing through the wire and the potential between the electrodes is dependent upon the rate at which the water is forced through the tube, Conversely, if an electric current is passed through such capillary tube, the liquid will move toward that electrode which has the charge opposite to that of the movable layer of the Helmholtz double layer.

In the cas of a glass capillary filled with distilled water, the water will move toward the negative electrode since the movable layer in the water consists of positive ions. This is the case with capillaries of most materials.

It has been found that the incorporation of certain water-ionizabie materials or electrolytes in the distilled water will lessen or even reduce to zero the electrokinetic or zeta potential. thereby reducing or completely stopping the electrokinetic flow or electro-osmosis through the capillary. In the literature there are recited various determinations of the zeta potential for varying concentrations of different electrolytes in a simple distilled water-glass system. Some of them, such as sodium chloride, potassium. chloride and sodium sulphate decrease the electroklnetic potential a comparatively small amount, and even with increasing concentrations the electrokinetic' potential between the glass and the water remains appreciably negative. Other electrolytes hav a very pronounced effect and even with limited concentrations lower the electrokinetic potential be tween the glass and the water to substantially zero. Still others, such as thorium salts, reduce the electrokinetic potential to zero very rapidly,

then cause it to reverse to positive, and then, with further increasing concentrations, cause the electrokinetic potential to approach zero. Outlines of Biochemistry," Gortner, pages 147-150; Physical Chemistry," MacDougall, pages 694-696.

I believe the failure of the synthetic rubber cots heretofore produced and-used in textile mills may be explained as follows: A certain amount of water is adsorbed upon the surface of a cot.

particularly under the operating conditions of modern textile mills where a high relative humidity, usually about 60%, is maintained to prevent accumulation of static charges and to render the fibers more amenable to drafting. I believe that. such water forms a Helmholtz double layer upon the surface of the cot and, in the case of synthetic rubber compounds heretofore used, the

rubber surface has a zeta potential with respect to the moisture film. The fibers also have acertein amount of water adsorbed on their surfaces so that I believe that there is present on the fibers also a Helmholtz double layer with the surface of the fiber having azeta potential negative with respect to the adsorbed water film. There is thus a zeta potential set up in the cot-water interface and another zeta potential set up at the tion where their charges are eflective in reducfiber-water interface resulting in firm adhesion of water to both the synthetic rubber and fiber. When the two are pressed firmly together. as in the drawing operation. the water film becomes common to both the cot and the fiber and the forces of cohesion in the water itself tend to bond or cement together the cot and fiber, thus causing lapping of the fiber around the cot. This may be a unique conception, but I believe it acceptably explains the lapping up'action which occurs with the synthetic rubber cots of commerce as heretofore made. While I have set forth the electrokinetic theory in some detail because I believe it offers the best explanation of the phenomena which I have observed, it is to be understood that the invention is not limited to the theory.

I have found by making and testing cot covers that the incorporation of certain electrolytes including animal proteins (preferably glue), ion exchange resins, and the inorganic electrolytes, calcium nitrate, aluminum sulphate, potassium aluminum sulphate, sodium aluminum sulphate, ferric sulphate, potassium ferric sulphate, sodium ferric sulphate, sodium carbonate and phosphoric acid, when incorporated into synthetic rubbers, such as butadiene acrylonitrile copolymers (sold commercially as Perbunan," Chemigum, and Hycar), polymerized chloroprene (sold commercially as neoprene"), and isoprene acrylonitrile copolymers, reduces or overcomes the tendency of the cot to lap or pick up fibers. The test which is hereinafter described shows that the incorporation of these electrolytes into the synthetic rubbers as set forth above reduces the zeta potential at the rubber-water face to substantially zero. I therefore believe that the nonlapping characteristics imparted to the cots by the incorporation of 'such electrolytes is due to the fact that the electrolyte in the synthetic rubber-electrolyte mixture supplies the necessary electric charges to reduce the zeta potential at the cot-water interface to zero or substantially zero, thereby destroying the adhesion between the cot and the water film and thus preventing lapping. While I have made and tested cots made of the specific materials set forth above, I believe that other electrolytes may be used which prevent lapping due, as I believe, to the reduction of the zeta potential between the working face of the cot and water, provided, of course,

that such electrolytes are dispersible in the synelectrolytes, the cots lapped up badly. When the same synthetic rubber-electrolyte composition cots were exposed to the usual humid atmosphere of a textile mill, or dipped in water and the surface wiped' free of water, the cot functioned very well with regard to 1apping.. I believe that the presence of a certain amount of moisture-is required to bring. the electrolytes into water soluing the zeta potential.

I have also found that the eflectiveness of the electrolytes in synthetic rubber cots when moissynthetic rubber containing the electrolyte, the

better the resistance to lapping. I ofler as a possible theoretical explanation of these observations, that the electrolytes incorporated into the synthetic rubber are more readily available at the surface in the case of the synthetic rubbers having the greater water vapor permeability.

The electrolyte should be thoroughly and uniformly dispersible in the synthetic rubber. It may. be dispersed by heating or melting the electrolyte and incorporating it in the synthetic rubher in the usual rubber mill, or by making a concentrated solution and adding it to the synthetic rubber in the usual rubber mill. When the electrolyte has been thoroughly milled into the synthetic rubber, it is apparently uniformly dispersed therein so that the mixture has the appearance of a homogeneous solution. When a thin sheet of the milled mixture is viewed in front of a light it has the same transparent appearance as the untreated synthetic rubber. There are no discrete particles of the electrolyte observable to the naked eye or even under 150 magnifications.

All electrolytes are not satisfactory for the purpose of preventing lapping up when incorporated in synthetic rubber cots. A simple apparatus has been devised and has been used by me by means of which the satisfactory electrolytes may be distinguished from those which are not satisfactory for this purpose. Referring now to Figs. 1 and 2 of the drawings, the apparatus comprises a short length of tubing l of a synthetic rubber in which the electrolyteis incorporated, in the ends of which are inserted two upright L-shaped

glass tubes

2 and 3. In the apparatus as I have used it the rubber tube l is about 2 inches long and has an internal diameter of about 1; inch.

Each of the L-shaped pieces of glasstubing has a total length of about 3 inches and an internal diameter of about /8 inch. Extending into the open ends of the L-shaped

glass tubes

2 and 3 are

platinum electrodes

4 and 5 connected through wires 6 and l to a source of direct current such as a generator 8. A volt meter 8 is connected across the wires 6 and I. A milliammeter i0 is inserted in one of the lead wires 8 or I. A screw pinch clamp ii is applied to the rubber tube l whereby it may be adjustably constricted.

A synthetic rubber composition, as described for instance in the specific examples hereinafter set forth, containing the electrolyte to be tested is compounded, milled. and extruded to form a small tube and vulcanized in the same manner in which the roll covers are vulcanized. The tubes are vulcanized on clean glass rods to prevent any metallic contamination which might affeet the test. The vulcanized tube containing the electrolyte to be tested is inserted in the apparatus as indicated by reference numeral i be-. tween the two

glass tubes

2 and 3. The test aped so as to dip into the distilled water for a distance of approximately one-half inch. The middle of the synthetic rubber tube I is constricted by the pinch clamp ll so as to form a capillary passage and thus produce the condition necessary for electro-osmosis. A suitable direct current electromotive force is impressed upon the

electrodes

4 and 5. In practice, I have employed an electromotive force of 720 volts. The constriction of the tube I by the pinch clamp H is adjusted to give a current of about .04 milliampere at 720 volts. This current is measured by means of the -milliammeter Hi. When the electromotive force of the order of seven hundred volts is impressed acrms the

electrodes

4 and 5, it is found that practically all synthetic rubber compositions, including those compounded with electrolytes, will show a fairly strong initial flow toward the negative electrode through the adjusted capillary opening in the tube l. The flow of current can be observed by the rise of water level in one tube and the fall of the water level in the other tube. The water flow is in accordance with the laws of electro-osmosis as explained, for example, at pages 145 to 147 in Outlines of Biochemistry, by Gortner. The fact that such flow takes place toward the negative electrode indicates that the zeta potential of the synthetic rubber with respect to distilled water is negative. If the electric current is kept constant, the rate of flow through the capillary is directly proportional to the zeta potential at the interface between the synthetic rubber surface and the distilled water.

With some of the better lap-resistant synthetic rubber compounds, such as Chemigum and glue, this negative flow will very rapidly drop off, sometimes in a matter of minutes, to substantially zero. Other lap-resistant synthetic rubberelectrolyte compounds, depending, I believe, upon their water vapor permeability and the effectiveness of the electrolyte incorporated in thevsynthetic rubber, will show a drop to approximately zero in the negative flow in periods up teiortyeight hours. In some cases the flow wilit reverse and go to a slightly positive flow. Occasionally the flow of water will reverse several times from positive to negative and back agaimbut always remaining close to the zero point. From the data which I have collected from my tests, there is quite a clear-cut correlation between the flow recorded in these electro-osmosis tests. and the lapping behavior of the cots made from the same synthetic rubber compositions. The electro-osmotic flow through rubber tubing made from synthetic rubber compositions which show a satisfactory lap resistance will reach the zero point, or substantially the zero point, at the end of forty-eight hours or before, and will show a flow not exceeding one cubic millimeter per minute in either the positive or negative direction when the conditions previously stated obtain, namely, that the pinch clamp is adjusted to provide a current of .04 milliarnpere at 720 volts between the elec- A trodes. 65

i stand for a period'of forty-eight hours and thereupon a determination of the electrokinetic potential is made in the following manner. The electrodes are supplied with 720 volts direct ourrent and the pinch clamp is adjusteduntil the milliammeter reads .04 milliampere. Measurement is then made of any rise in the water column. If little or no flow is noted over a period No water flow through the capillary opening in the tube indicates that the zeta potential between the synthetic rubber composition and the distilled wateris zero. However, it is not necessary that the zeta potential be reduced to exactly zero. If

- the zeta potential is reduced to substantially zero,

which I define as so close to zero that the flow of water under the conditions above set forth is not more than about 1 cubic millimeter per minute, the adhesion between the textile fibers and a cot having a working surface made of such synthetic rubber composition is reduced sufllciently so that the cots are lap-resistant. This, I believe, is due to the fact that the zeta potential across the Helmholtz doublelayer at the surface of the cot is so reduced as effectively to eliminate lapping up.

The water flow can be accurately measured by observing the rise and fall of the water surface in one of the glass tubes. In making the observations above described, the rise of the water level is small enough so that the back pressure of the water from the higher water column and the consequent static pressure against the flow through the capillar opening may be disregarded, particularly as in making the readings the current flow is reversed in checking the results.

The observations made by the test apparatus check with the lapping resistance of the textile c ts and corroborates what I believe to be the reason why certain electrolytes when incorporated in the synthetic rubber cots will work, namely, that such electrolytes are 'eil'ective in reducing the zeta potential between the surface of the synthetic rubber cot and the water which is absorbed from the atmosphere upon the cot surface.

The electrolytes which I have found to be effective have certain common characteristics. They are, of course, materials which are not iniurious to the synthetic rubber in which they are incorporated and do not deleteriously aifect the synthetic rubber mix. They are all readily ionizable in water. They are uniformly dispersible in the synthetic rubber. They are effective when incor. porated in the synthetic rubber in reducing the zeta potential between the synthetic" rubber and water tosubstantially zero. These qualities can be readily ascertained from common knowledge of their chemical and physical characteristics and by simple tests such' as above indicated, so

fourth annual meeting of the American Society I for. Testing Materials.

My tests have been carried out primarily with synthetic rubbers of the following types: butadiene acrylonitrile copolymers, of which "Perb'unan," Chemigum and Hycar" are commercial examples, and whichcontain varying percentages of acrylonitrile; chloroprene polymer, of whichmeoprene is a commercial example; and

isoprene acrylonitrile copolymers, which have been made experimentally. 'These have all proved satisfactory synthetic rubber bases for non-181pping cots when mixed with the proper electrolytes.

These synthetic rubbers have certain common characteristics rw'hich 'adapt them for use in covers for textile drafting rolls. They are vulcanizable. When vulcanized they are oil-resistant, resilient and non-thermoplastic. When vulcanized they are all water permeable to a certain extent, as indicated by the following tests, the results of which are expressed in the terms used in the American Society for Testing Materials, Methods for Water Vapor Permeability, in which the results were obtainedwith a humidity desiccated air and air of 80% relative humidity of 70 F.:

"Chemigum N-1 2.2 10- grms. per sq. cm. per

day

Perbunan l.5 10- grms. per sq. cm. per day Hycar OR.-15"-l.0 10=, grms. per sq. cm. per

day Neoprene GN"-0.8x 10- day While my tests show that synthetic rubbers of the butadiene acrylonitrile ccpolymer type. the polymerized chloroprene type, and the isoprene acrylonitrile copolymer type are satisfactory, I believe that any synthetic rubber having the characteristics above indicated may be employed. As

grms.-per sq. cm. per

contrasted with synthetic rubbers having the that it is possible to foretell whether or not a particular electrolyte will be effective to prevent lapping up by a synthetic rubber cot in which the electrolyte is incorporated By the term synthetic rubber I mean those synthetic. substances which are commonly referredto assynthetic rubbers and which have physical properties resembling those of natural rubber, as set forth, for exampledn the definition h by Harry L. Fisher, being the Edgar Mar-- burg lectures of 1941 presented before the My- ,bly is wrapped with cotton characteristics above indicated as essential for satisfactory operation, there are synthetic rubbers of the butyl and Vinylite types, which are not satisfactory because they cannot bev'ulcanized, or are not sumciently oil-resistant, or are subject to excessive cold flow because of their thermoplastic nature.

I cite the following examples of compositions made of synthetic rubber and containing izonizable substances which prevent lapping up when used in textile drawing rolls.

' Example 1 Parts by weight Perbunan (butadiene acrylonitrile copolymer) Sulphur 10 Triacetin 10 Titanium dioxide 15 Zinc oxide 10 Graphite No. 64 2.6 Benzothiazyl disulphide 1.5 Diphenylguanidine 0.2 Glue 50 In the manufacture of a cot from this composition, the ingredients are incorporated on a rubber mill. The milled mass is fed to a tuber and a body of approximately the desired diameter is formed and placed upon a mandrel. The assemtape and vulcanized by the application of heat at about 300 F, for about one hour. The tube is then removed from the mandrel, cut to the desired lengths, and they are ready for application as covers for drafting mils.

The covers arebufled by grinding to produce a de-' The usual substitutions may be made for these ingredients as is well-known to the synthetic rubber compounder. The glueemployed was Swift's Economy glue. However, otherglues may be used, such for example as Cudahy Packing Companys "Rex glue, Peter Cooper 'AA" glue, etc. Equivalent amounts of other animal proteins, such as gelatin or casein ormixtures thereof, may

- be employed in place'of glue.

- Example 2/ g z a 1 Parts by weight Neoprene (polymerized chloroprene) 100 Magnesium oxide 4 Glue 50 Titanium dioxide Graphite #64 2.6

- Zinc oxide 5.4 Cork. 30 mesh '50 Thiscomposition is prepared and the cot may be formed in the same manner as disclosed above with regard to Example 1. Zinc oxide andmagnesium .oxide used in the above compound are polymerization agents and are effective for vulcanizing the neoprene.

I have found thatthe lap resistance of some synthetic rubber electrolyte-containing cots, particularly those of the chloroprene type, is improved by incorporating cork granules. The cork granules become a part of the exposed surface of the cot after buffing and appear to impart to the cot some of the characteristics of the cork, particularly its lap resistance. By incorporating animal protein into the compound, its lap resistance is increased tremendously. Unless lap resistance is improved, the finished product is unacceptable,

for my work has established that, for satisfactory results, the body material must, in all instances. be substantially resistant to lapping. Attempts have heretofore been made to obtain the desired result by merely incorporating cork particles.

Such attempts failed because the synthetic rubber composition which formed the matrix in which the cork granules were imbedded was not. in itself, resistant to lapping. It should be borne in mind that when a cot is buffed for use. both the severed cork particles and the body'material form the working surface. If either is not resistant to lapping a satisfactory product will not result. If only-a minor portion of this surface be non-resistant to lapping, unsatisfactory results will be obtained for even a small area not so resistant when' engaged by the fibers being drafted will cause lapping, and once lapping starts, the roll must be removed and the fibers stripped off, reducing production.

While neoprene compositions incorporating animal proteins produce satisfactory results, improved results are obtained on certain typesand sizes of fiber when cork is incorporated, and for most uses, I prefer to incorporate both the animal protein and the cork. In the example above, cork of 20-30 mesh is incorporated. This mesh size is determined in accordance with United States Standard sieves. For best results, the

particles should not be larger than 10 mesh ormandrel to form a tube.

smaller than 50 mesh; particularly good results are obtained with cork particles falling within the range of 20-30 mesh.

a l Parts by weight Isopreneacrylonitrile copolymer'. 100 Dibutyl phthalate 10 Sulphur 10 Pigment I, 15 Zinc oxide 10 Santocure" (n cyclohexylbenzothiazylsulphenamlde) 1.5 Casein 1 n 1 50 The composition may be prepared and the cot may be formed in the same manner as disclosed in-connection with Example 1. In the above compound, dibutyl phthalate is a plasticizer, sulphur is a vulcanizing agent, zinc oxide is a vulcanization promoter, and "Santocure is an accelerator. Substitutions may be made in these ingredients-as desired. a I

I have found, as disclosed above, that the incorporation of certain salts 'in synthetic rubber compounds for this purpose also render the cot formed from the compound more resistant toward lapping up under normal conditions of use. A suitable compound illustrating the use of a salt is as follows:

The synthetic rubber ismilled in any suitable rubber mill until it is satisfactory for use. Then the salt is melted or dissolved in water and milled into the syntheticrubber at a suitable temperature. In the above example, the calcium nitrate is melted and milled into the synthetic rubber at a temperature of C. to C. Theremaining ingredients may be added to the milled mass as is customary and well-known in the industry. The compound so prepared is then sheeted or tubed by means of any suitable tubing, device. If the compound be sheeted, it is rolled about a If the compound be tubed, the tube is slipped on the mandrel. In either case, the cot stock disposed about the mandrel is wrapped with wet fabric tape and cured with open steam. The temperature and duration of cure are not material since depending upon the type of compound, the period of cure may be greater or less at low or higher temperatures. For the above compound, I have found a curing time of minutes at 300 F. is satisfactory.

After the curing operation, the tape is stripped from the tubes and the tubes are removed from the mandrel, buffed or ground to remove the tape marks and to obtain a satisfactory surface, and

l l lyte. I have found that certain other salts, such as aluminum sulphate, potassium aluminum sulphate, sodium aluminum sulphate, ferric sul-u the synthetic rubber. and are eifective when incorporated in the synthetic rubber in reducing the zeta potential between the synthetic rubber and water to substantially zero. Zinc oxide is used as an activator for the accelerator, Altax. Other conventional accelerators may be used in place of Altax. Triacetin is used as a softener or plasticiaer and other plasticizers may be used in its place, for example. tricresyl phosphate, dibutyl phthalate, or dibenzyl ether. Titanium dioxide and Gastex are used primarily as pigments to impart a desired color to the cot compound. Sulphur, of course. is the vulcanizing agent. If desired. suitable fillers or other pigments may be inwrporated in the compound.

In accordance with the theory as disclosed above, it would naturally follow that a cot so made if dry would probably not be satisfactory in fiber drawing and this appears to be the case. Before use. the cot should be exposed to water for oedure described above with regard to butadiene acrylonitrile copolymers and the cot so produced possesses improved resistance toward lapping up.

Example 8 v I Parts by weight "Neoprene GN" (polymerised chloroprene)- 100 Light magnesia 4 Stearic acid 8 Titanium dioxide l5 Graphite I 2.8 Neozone A 2 Zinc oxide 6 Calcium nitrate 20 The above materials may be compounded in the same manner as taught for "Perbunan types of compounds and the cot obtained shows considerably sreater resistance to lapping up than is usually secured with cots which include "neoprene." The light magnesia is used as a agent; in ltrplace,

desired, parailln may be'usedin its place. Titanium dioxide and graphite are used primarily to impart a desired color to the stock. Neozone A a sulilcient time for the cot to adsorb some amount or water if it be desired that it possess requisite resistance to lapp g up immediately when it is placed on the frame for use. If desired, the cot may be dipped in water before use, but this is generally not necessary since under the usual conditions of humidity encountered in the textile industry. it is only necessary that the cot remain in such humid atmosphere for a short period of time to adsorb the necessary amount of water to permit its satisfactory use.

Example 6, Example 6, Parts b Parts by Weight Weigh "Pcbunsn" (butadisne acrylonitrile mo so is 5 l0 0. 3 l0 2 The cot compounds of Examples 5 and 6 may be prepared in accordance with the procedure disclosed in Example 4. Cots are formed from such compounds similarly to the procedure disclosed in Example 4. In all cases, the cots so formed are highly satisfactory in use after they are exposed to water for a suiilclent period of time to adsorb a small amount of the water at the surface of the cot.

This compound is formed following the pro- 76 previousLv described.

11 phosphoric acid is is an anti-oxidant and any suitable anti-oxidant may be used in its place. zinc oxide is used primarily as. a curing agent. Other suitable salts may be substituted for the calcium nitrate, as indicated in connection with Example 4, supra.

In the following examples numbered 9, l0 and used as the electrolyte. necessary characteristics indicated above. -It does not deleteriously aifect or desrade the synthetic rubber, as would strong acids such as sulphuric or nitric. Y

E's-ample 9 Parts by weight "Perbunan (butadiene aerylonitrile copolymer) Sulphur l0 Phosphoric acid 10 Titanium dioxide 15 Zinc oxide 5 Gastex 0.3 Triacetin 10 Altax 1.5

The above material may be compounded in the same manner as previously disclosed for the manufactured cots. The cots so formed are highly satisfactory in use after they are exposed to water for a sumcient period of time to adsorb a tsmullamount of water at the surface of the co As pointed out previously. other synthetic rubbers may be used in place of "Perbunan. A satisfactory cot including "neoprene may comprise the following:

Example 10 Parts by weight "Neoprene GN" (polymerized chloroprene) 100 Light magnesia --l- 4 Stearic acid 3 Titanium dioxide l5 Graphite Y 2.6 Neozone A 2 Zinc oxide 8 Phosphoric acid 10 The above compound may be formed into cots as I may use iitharge or lead dioxide. 'Btearic acid is used-as a lubricant and if 3 A similar cot may be formed including isoprene acrylonitrile copolymer. A suitable example oi such compound which may be formed as previously described is as follows:

Example 11 a Parts by weight w Isoprene acrylonitrile copolymer 100 Phosphoric acid 10 Sulphur 10 Titanium dioxide 15 Zinc oxide 5 Gastex 0.3 Triacetin Altax 1.5.

I have found that compounds including combinations of electrolytes, such as'animal proteins and the salts or acids described above, provide cots which in some instances are even more satisfactoryin'resistance toward lapping up than the compounds described above. A suitable formula for cot manufacture which includes an animal protein and a salt is as follows:

Example 12 'Parts by weight Perbunan (butadiene acrylonitrile copolymer) 1. 100 I Calcium nitrate 20 Glue -1 50 Titanium dioxide Zinc oxide 5 Triacetin 10 Gastex 0.3 Sulphur 10 Altax .2

The above compound may be formed into a cut -as disclosed in connection with Example 1. v will'be understood other suitable electrolytes may be used in place of calcium nitrate.

I Example 13 Parts by weight Isoprene acrylonitrile copolymer 100 Calcium nitrate e Glue 'j 50 Titanium dioxide 15 Zinc oxide l '5. Triacetin :10 Gastex 0.3 Sulphur I 1o v Altax 2 This compound is formed following procedure described above and the out so produced possesses greatly improved resistance toward lap ping up.

Example 14 v Parts by weight Neoprene GN (polymerized *chloro-L prene) 100 Glue t 50, Light esia 1 '4 Stearic acid 3 Titanium dioxide 15 Graphite 2 6 Neozone A 2 Zinc oxide 5 Calcium nitrate 1-.. 20

The above materials may be compounded inthe manner disclosed above and the cot obtained shows considerably greater resistanceto lapping 14 up than is usually secured with cots which include ,ne'oprena" Example 15 n Parts by weight Perbun'an'f (butadiene acrylonitrile copolymer) mo Sulphur i0 Phosphoric a 20 Glue t 5Q Titanium dioxide 15 Zinc oxide 5 Gastex I 0.3 Triacetin 10 Altax 1.5

This compound may be formed in the manner described above.

The above materials may be compounded in the same manner as previously described. Cots obtained show greater resistanc to lapping up than is usually secured with cots which include K neoprene. While the animal proteinis preterably glue, other animal proteins may be used.

Example 17 Parts by wei ht Isoprene acrylonitrile copolymer 100 Sulphur 10 Phosphoric acid 20 Titanium dioxide 15 Zinc oxide 5 Gastex 0.3 Triacetin 10 Altax 1.5

Glue 50 The above ingredients may be compounded as described above. I

In the above compounds, it is particularly important that the amount of animal protein, salt or acid be included in an amount suflicient to enhance the resistance of the cot to lapping up but in an amount insufflcient to aflfect deleteriously the essentially rubber-like characteristics of the cot compound.

When an animal protein such as glue is employed as the electrolyte, it is in general undesirable to include less vthan 15 parts by weight of the animal protein to 100 parts by weight of the synthetic rubber, since substantially no im- ,provemcnt in lap resistance is encountered with a lesser amount.

' parts by weight of animal protein to 100 parts It is preferred to use at least byweight of synthetic rubber. For optimum resuits the animal protein should beat least about 40 parts by weight to 100 parts by weight of synthetic rubber, as this amount appears to be in general more effective than 25 parts. The animal protein maybe incorporated nearly to the point where the animal protein ceases to be While in the neighborhood or 50 parts 01' glue to 100 parts of synthetic rubber have been found suits for polymerized chloroprene and isopreneacrylonitrile copolymers.

when the inorganic electrolytes are employed as above indicated, the amounts are in general employ not more than about 30 parts by weight or the inorganic electrolyte to 100 parts by weight or synthetic rubber. For optimum results we have employed. as indicated in the examples. in the neighborhood of 20 parts by weight 01 inorganic electrolyte to 100 parts by weight of synthetic rubber.

Two or more of such inorganic electrolytes may be added together, in which case the aggre-. gate of the added electrolytes should come within the-same ranges oi parts per 100 parts oi synthetic rubber as above stated fora single added electrolyte.

One or more oi such inorganic electrolytes may be added with animal protein if desired, in which case the amounts of the animal'protein and'the inorganic electrolyte added are preferably the same as when added alone. 'I'hecot. however,

these electrolytes alone.

the case oi adding both.

quantities. Ihave should not be larger Amberlite xa-v is an A" stage cation active resin 01 the phenol sulphonic acid formaldehyde type or the into the rubber on. a standard rubber mill in the same manner as the animal proteins mentioned above.

R. J. Myers entitled Synthetic resin ion exchangers, appearing in the book entitled Advances in Colloid Science," edited by E, O. Kraemer, published by Interscience Publishers, Inc., New York, 1942, and in the Adams and Holmes Patents Nos. 2,104,501 and 2,151,883, and the Myers and Eastes Patent No. 2,362,086.

As in the case oi'the other'electrolytes. the ion exchange resin inorganic electrolytes or both.

Cork granules may be included in any of these various synthetic rubber mixes. As noted above in connection with Example 2, the presence of yarn which is called a "nub."

The cork granules may be included in various found that the amount of cork in the various mixes may fall than about mesh or smallmesh and I have found that results are obtained with cork within the range of to er than about particularly good granules railing '17 meshes to the inch United States Standard sieves. The cork granules are preferably added along with the other ingredients which are incorporated in the synthetic rubber on the rubber mill and are thus uniformly distributed in the synthetic rubber mix so that there is a uniform distribution of such particles at the working surface.

Granules or particles of other materials which minimize eyebrowing may be similarly employed in place of cork. Such materials include wood flour, fine mesh sand (preferably about 100 mesh), organic filler particles of a nature similar to cork such as soft wood, balsa, etc., as well as other materials which minimize eyebrowing.

In the drawings, Fig. 3 is a perspective view of a roll cover embodying my invention identified by a suitable legend; and such a roll cover including cork granules.

While I have disclosed certain preferred embodiments of my invention, it will be understood that my invention is not limited thereto since it may be otherwise embodied wthin the scope of the following claims.

I claim:

1. A lap-resistant roll cover for textile fiber drafting having a working surface made of a vulcanized rubber-like butadiene acrylonitrile copolymer, having uniformly dispersed therein as the dispersed phase between about 40 and 60 parts of glue to 100 parts of the butadiene acrylonitrile copolymer, whereby the roll cover is rendered lapresistant.

2. A lap-resistant roll cover for textile fiber drafting having a working surface made of a vulcanized rubber-like butadiene acrylonitrile copolymer, having uniformly dispersed therein as the dispersed phase between about and 30 parts of calcium nitrate to 100 parts of the butadiene acrylonitrile copolymer, whereby the roll cover is rendered lap-resistant.

3. A lap-resistant roll cover for textile fiber drafting having a working surface made of a vulcanized, rubber-like butadiene acrylonitrile copolymer, having uniformly dispersed therein as the dispersed phase between about 40 and 60 parts of glue and between about 10 and 30 parts of calcium nitrate to 100 parts of the butadiene acrylonitrile copolymer, whereby the roll cover is rendered lapresistant.

4. A lap-resistant roll cover for textile fiber drafting having a working surface made of a vulcanized oil-resistant resilient non-thermoplastic somewhat water vapor permeable synthetic rubber which is normally non-resistant to lapping up, having uniformly dispersed therein as the dispersed phase between about 25 and '75 parts of .animal protein which is dispersible in the synthetic rubber to 100 parts of the synthetic rubber, whereby the roll cover is rendered lap-resistant.

5. A lap-resistant roll cover for textile fiber drafting having a working surface made of a vulcanized oil-resistant resilient non-thermoplastic somewhat water vapor permeable synthetic rubber which is normally non-resistant to lapping up, having uniformly dispersed therein as the dispersed phase at least parts of animal protein which is dispersible in the synthetic rubber to 100 parts of the synthetic rubber, whereby the roll cover is rendered lap-resistant.

6. A lap-resistant roll cover for textile fiber drafting having a working surface made of a vulcanized oil-resistant resilient non-thermoplastic somewhat water vapor permeable synthetic rubber which is normally non-resistant to lapping up, having uniformly dispersed therein as the dis- Flg. 4 is a similar view of to 100 parts of the 8 persed phase between about 5 and 40 parts of calcium nitrate to 100 parts of the synthetic rubber, whereby the roll cover is rendered lapresistant.

'7. A lap-resistant roll cover for textile fiber drafting having a working surface made of a vulcanized oil-resistant resilient non-thermoplastic somewhat water vapor permeable synthetic rubber which is normally non-resistant to lapping up, having uniformly dispersed therein as the dispersed phase between about and '75 parts of an ion exchange resin to 100 parts of the synthetic rubber, whereby the roll cover is rendered lapresistant.

8. A lap-resistant roll cover for textile fiber drafting having a working surface made of a vulcanized oil-resistant resilient nonthermoplastic somewhat water vapor permeable synthetic rubber which is normall nonresistant to lapping up, having uniformly dispersed therein as the dispersed phase between about 5 and 40 parts synthetic rubber of an inorganic electrolyte which is readily ionizable in distilled water water and which is capable of reducing the zeta potential of the working surface in contact with roll cover is rendered lap-resistant.

9. A lap-resistant roll cover for textile fiber drafting having a working surface made of a vulcanized oil-resistant resilient nonthermoplastic somewhat water vapor permeable synthetic rubber which is normally nonresistant to lapping up, having uniformly dispersed therein as the dispersed phase between about'10 and 30 parts to 100 parts of the synthetic rubber of an inorganic electrolyte which is readily ionizable in water and which is capable of reducing the zeta potential of the working surface in contact with distilled water to substantially zero, whereby the roll cover is rendered lap-resistant.

10. A lap-resistant roll cover for textile fiber drafting having a working surface made of a vulcanized oil-resistant resilient n'onthermoplastic somewhat water vapor permeable synthetic rubber which is normally nonresistant to lapping up, having uniformly dispersed therein as the dispersed phase between about 25 and '75 parts of glue to 100 parts of the synthetic rubber, whereby the roll cover is rendered lap-resistant.

11. A lap-resistant roll cover for textile fiber drafting having a working surface made of a vulcanized oil-resistant resilient non-thermoplastic somewhat water vapor permeable synthetic rubber which is normally non-resistant to lapping up, having uniformly dispersed therein as the dispersed phase an effective amount of an electrolyte which is readil ionizable in water and reduces the zeta potential of the working surface in contact with distilled water to substantially zero, whereby the roll cover is rendered lap-resistant.

12. A lap-resistant roll cover for textile fiber drafting having a working surface made of a vulcanized synthetic rubber selected from the class consisting of butadiene acrylonitrile copolymers, polymerized chloroprene and isoprene acrylonitrile copolymers, having uniformly dispersed therein as the dispersed phase an effective amount of an electrolyte which is readily ionizable in water and reduces the zeta potential of the working surface in contact with distilled water to substantially zero, whereby the roll cover is rendered lap-resistant.

13. A lap-resistant roll cover for textile fiber drafting having a working surface made of a to substantially zero, whereby the vulcanized oil-resistant resilient nonthermoplastic somewhat water vapor, perm a l s n h t rubber which is normallynon-resistant to lapping up, having uniformly dispersed therein as the dispersed phase an effective amount of an electrolyte which is readily ionizable in water and reducesthe zeta potential of the working surface in contact with distilled water to the point where the electro-osmotic flow obtained through a capillary tube of the synthetic rubber composition is not more than about 1 cubic millimeter per minute under an impressed voltage of 720 volts and a current of .04 milliampere 48 hours after the contact of the distilled water with the synthetic rubber surface of the capillary, whereby the roll cover is rendered lap-resistant.

14. A lap-resistant roll cover for textile fiber drafting having a. workingsurface made of a vulcanized oil-resistant resilient non-thermoplastic synthetic rubber having a. water vapor permeability of at least about 0.8 10- grams per square centimeter per day measured with a humidity differential between that of desiccated air and air at 80% relative humidity at 70 F., which said working surface is normally non-resistant to lapping up, having uniformly distributed therein as the dispersed phase an effective amount of an electrolyte which is readily ionizable in water and reducesthe zeta potential of the working surface in contact with distilled water to the point where the electro-osmotic flow obtained through a capillary tube thetic ruber composition is not more than about 1 cubic millimeter per minute under an impressed voltage of 720 volts and a current of .04 milliampere 48 hours after the contact of the distilled water with the synthetic rubber surface at the capillary, whereby the roll cover is rendered lap-resistant.

15; A lap-resistant roll cover for textile fiber drafting having a working surface made of a vulcanized oil-resistant resilient non-thermoplastic synthetic rubber having a water vapor permeability of the order of 1 or 2 10- grams per square centimeter per day measured with a humidity differential between that of desiccated air and air at 80% relative humidity at 70 E, which of the Syn-- said working surface is normally non-resistant to pping up. having uniformly distributed'therein as the dispersed phase an effective amount of an electrolyte which is readily ionizable in water and reduces the zeta potential of the working surface in contact with distilled water to the point where the electro-osmotic flow obtained through a capillary tube of the synthetic rubber composition is not more than about 1 cubic millimeter per minute under an impressed voltage of 720 volts and a current of .04 milliamperes 48 hours after the contact of the distilled water with the synthetic rubber surface at the capillary, whereby the roll-cover is rendered lap-resistant.

16. A lap-resistant roll cover for textile fiber drafting in accordance with claim 5, having' cork granules uniformly distributed in the synthetic rubber mix at the working surface.

17. A lap-resistant roll cover for textile fiber drafting rolls in accordance with claim 6, having cork granules uniformly distributed in the synthetic rubber mix at the working surface.

18. A lap-resistant roll cover for textile fiber drafting in accordance with claim 11. having cork granules uniformly distributed in the synthetic rubber mix at the working surface.

19. A lap-resistant roll. cover for textile fiber drafting in accordance with claim 11, having particles of a material which minimizes eyebrowing uniformly distributed in the synthetic rubber mix at the working surface.

JOHN W. BAYMILLER.

REFERENCES CITED The following references are 'of record in the file of this patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,450,409. October 5, 1948.

. JOHN W. BAYMILLER It is hereby certified that errors appezir in the printed specification of the above numbered patent requiring correction as follows:

Column 4, line 7, before the word fiber insert the; column 7, line 43, for absorbed read adsorbed; column 8, line 26, after humidity for of read at; lines 51 and 52, forizonizable read ionizablc; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 1st day of March, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommz'asioner of Patents.