US2450408A - Textile fiber drafting element - Google Patents

Description

. BUTADIENE- 7x ACRYLONITRILE COPOLXMER )vlm ul 6 TREATED wo NG Oct. 5, 1948. J. w. BAYMILLER TEXTILE FIBER DRAFTING ELEMENT Filed Sept. 16'. 1945 SURFACE Patented (let. 5, 1948 TEXTILE FIBER DRAFTING ELEMENT John W. Baymiller, Manheim Township, Lancaster County, Pa., assignor to Armstrong Cork Pennsylvania Company, Lancaster, Pa., a corporation of Application September 16, 1943, Serial No. 502,553 6 Glaims. (cl. 19-131) Thi application is a continuation-in-part of my copending application Serial No. 457,717, now abandoned, entitled Textile fiber drafting elements and method of making the same, and filed September 9, 1942.

This invention relates to drafting aprons, spinning rolls, drawing rolls, and the like used in the textile industry and commonly known as textile fiber drafting elements. The invention finds particular usefulness in the so-called long draft aprons used in the drafting of fibers, particularly rayon, and in the spinning roll covers used in drawing fibers, such as cotton, rayon, and the like.

The invention will be described with particular reference to long draft spinning aprons but it is here pointed out that the invention is not limited to aprons. Additionally, the example chosen for illustration is used in the drafting of rayon fibers since the invention finds unusual commercial acceptability in that field. Here again, it is pointed out the invention is not limited to textile fiber drafting elements for the processing of rayon. It contemplates all textile fiber drafting elements, regardless of the particular work performed or the type of fibers operated upon.

The invention also includes a method of treating textile fiber drafting elements to improve their workingsurf aces.

synthetic rubber aprons have been tried on longer staple fibers, such as rayon, it has been found that the frictional resistance or grip of the apron surface is so great that a positive holding action is exerted against the drafting of the front rolls resulting in broken fibers, a mutilated roving, and excessive waste which collects and falls into the roving, causing defective work. For these reasons, synthetic rubber aprons have been completely inoperative in many instances on long staple rayon. These results indicate that a similar action probably takes place in the processing of the shorter staple fibers such as cotton but to a lesser degree. Improved results in the processing of such fibers should be attained by my invention, although satisfactory operation is now obtained on such short staple fibers with the synthetic rubber aprons now available.

There has also been a noticeable tendency for the synthetic rubber aprons to be damaged or destroyed because of failure of the apron to move freely over the stationary supporting bar in the Whitin-Casablancas, the Saco Lowell-Roth, and other similar systems; the physical characterise tics of the inner surface of the aprons impairing their movement over the stationary surface under usual drafting tension.

In drawing textile fibers, one commonly employed machine is the drawing frame which inrolls arethe same as those used on a regular three-roll drafting frame. However, in place of a pair of middle rolls to engage the fiber under treatment, a pair of aprons is provided which reaches forward close to the nip of the front rolls. The back rolls and aprons serve to break draft the roving and the front rolls and aprons pertensively of leather. Attempts have been made to utilize synthetic rubber aprons but acceptable 1 operation of these has been limited largely to the processing of the shorter staple fibers. when cludes a series of spaced pairs of drawing rolls, the lower roll of each pair being in the form of a fluted metal roll. The upper rollof each pair in certain types of drawing frames has a resilient working surface and in many such units the upper rolls are covered with cork composition,

leather, and synthetic rubber. Front rolls covered with these materials give considerable difficulty in operation due to the factthat fibers,

particularly rayon fibers, tend to stick to the rolls and "lap up on or wrap around the front roll. Synthetic rubber is especially susceptible to "lapping up." This fiber drawing illustration has been given as typical of the problems involved in fiber drafting. The same or similar difllculties may be encountered in roving frames, spinning frames, and in worsted and woolen processing equipment as well as in other services where fiber drafting elements are used.

From the foregoing it will be clear that the use of synthetic rubber surfaces in the drafting and spinning of textile fibers, particularly rayon and similar long staple fibers, has met with limited success. In the case of aprons used in long drafting, the frictional qualities of the synthetic rubber aprons have been too great, resulting in breaking of the fiber and concomitant mutilated rovings, as well as damage or destruction of the aprons due to impaired movement of the aprons over the stationary supporting bars. In the case of drawing rolls, the problem has been one of lapping up on the front roll due to excessive amnity of the synthetic rubber for the fibers.

Synthetic rubbers are well suited in many re- It is an object of my invention to provide a textile fiber drafting element possessing the foregoing desirable characteristics of synthetic rubbers and at the same time possessing an improved working surface which overcomes the difficulties heretofore encountered. Another object of my invention is to improve the inner synthetic rubber surface of'drafting aprons to provide a surface which will permit unimpaired movement of the aprons under usual drafting tension. It is a further object of my invention .to provide a method whereby these desired surface chameteristics may be imparted to synthetic rubber textile fiber drafting elements.

The synthetic polymerization products of openchain aliphatic conjugated dlenes, particularly those having the formula H2C=CRCH=CH2, wherein R is hydrogen, a halogen, or a methyl radical, are useful in the practice of my invention for they respond well to my treatment. The polymerization products of butadiene, chloroprene, and isoprene, such as polybutadiene, butadiene-acrylonitrile, butadiene-styrene, and butadiene-isobutylene copolymers; polychloroprene; polyisoprene; and isoprene-acrylonitrile copolymers, all have the formula H2C=CR'-CH=CH:, wherein R is as defined above, and the polymerization products of this class of polymerizable open-chain aliphatic conjugated dienes is preferred. w

, In the course of experimental work in connection with the manufacture of textile fiber drafting elements, I have discovered that those vulcanized or unvulcanized synthetic polymerization products of open-chain aliphatic conjugated dienes which in their final form have a carbon to carbon bond may be treated with a free halogen, to thereby change the surface characteristics of the product. By such treatment, the surface characteristics of the product are materially altered, and improved; all afilnity which would cause lapping up is eliminated; the frictional characteristics of the surface are changed, resulting in a surface ideally suited for the long drafting of rayon and other fibers heretofore difficult to work; and all tendency for aprons to be damaged or destroyed because of impaired movement over the stationary supporting bars is eliminated. Drawing rolls produced from such composition and having the treated surface have been found to work satisfactorily on rayon and long staple cotton, while untreated rolls of the same composition operating in an adjacent frame have lapped up to a degree sufficient to make their use impracticable. Likewise, long 'draft aprons formed from such composition and so treated have been found to operate remarkably well on machines employing the Whitin-Casablancas long draft system without undue tearing or breaking the fibers, whereas untreated aprons operating in an adjacent frame have proved inoperative on ny on fibers.

I will describe a long drafting apron produced in accordance with my invention using a vulcanized butadiene-acrylonitrile composition as the base. A composition may be formed from the following constituents:

In the foregoing example, butadiene-acrylonitriie copolymer is the base composition, sulfur is the vulcanizing agent, zinc oxide is an activator,

the phenyl-beta-naphthylamine is an anti-oxidant, the dibutyl phthalate is a plasticizer, the stearic acid is also an activator and may be omit-' ted, and the benzothiazyl disulfide is an accelerator.

As will be more fully discussed, other synthetic polymerization products may be substituted for the butadiene-acrylonitrile copolymer and the product may be vulcanized or unvulcanized, depending upon the service to be performed. As is obvious, the base composition may be compounded with various ingredients to produce a final product having the desired physical properties.

This material is formed into an apron in the desired manner, with or without a backing cloth, fabric, or reinforcing cord. A preferred practice is to provide an inner layer of a polymerization product of an open-chain aliphatic-conjugated diene into which a reinforcing cord is embedded and to superimpose a layer of a polymerization product of an open-chain aliphatic conjugated diene thereover to constitute the outer portion. The whole is then cured and vulcanized. After curing and vulcanization, the outer surface is buffed to the desired fineness. This apron is found to have an outer working surface which in itself would not be satisfactory for drafting long staple rayon. The apron thus formed is subjected to the action of a free halogen for a period of time suiilcient to permit a chemical reaction to take place at the desired surfaces of the apron. Preferably, with drafting aprons both the inner and outer working surfaces are treated but either surface maybe selectively treated if this is desired.

As a specific example, the apron may be im- ,mersed in a water solution of chlorine, the

strength of which is equivalent to 6 to 8 cc. of a tenth normal sodium thio-sulfate solution, for a period of about twenty minutes. The chlorine water may be prepared by .passing chlorine gas into water until the required strength is obtained, by acidifying a solution of a chlorine compound such as sodium or calcium hypochlorite, an organic solution of chlorine may be used, or any other means of getting free chlorine into contact with the surface of the polymerization product. The strength of the chlorine solution is not critical provided, of Y course, there is free chlorine present. The desired chemical reaction will take place in a very weak solution or in a substantially saturated solution. The duration of the treatment is not critical but depends upon the halogen used, the degree of unsaturation of the polymerization product, the strength of the treating solu-- tion and other variable factors.

After the twenty-minute immersion in the chlorine water, the apron is removed and dried. If solutions of sodium or calcium hypochlorite have been used, it is advisable to wash the aprons after treating in order to remove any trace of deposited salts.

In place of chlorine, any other halogen may be used, such as fluorine, bromine or iodine. Fluorine is so chemically reactive that its use is commercially impracticable and bromine and iodine are not as reactive as chlorine. Therefore, I prefer to use chlorine because'it is cheap, readily available, clean, light-colored, and sumciently active to produce satisfactory results in a relatively short period of time.

The polymer unit of the butadiene-acrylonitrile composition referred to in the foregoing example has the following formula:

H H H H H H [-co=c-cc-c H H H CN I believe that upon treatment with a halogen, the carbon to carbon double bond in the polymer is saturated and the material at the surface which has been treated would have the following It is recognized that vulcanization causes a modification of the polymer but I have found that the final effect of the halogen treatment is substantially the same when applied to the polymerization product in either the vulcanized or unvulcanized state.

Other polymerization products which have the following chemical polymer formulas may be treated in accordance with this invention:

It will be observed that in each of the foregoing examples there is a degree of unsaturation represented by the carbon to carbon double bond and any synthetic polymerization product of an openchain aliphatic conjugated diene in which there is a substantial degree of unsaturation, represented-by carbon to carbon double bonds in the polymerization product will be found to work satisfactorily. Of course, those polymerization products having a high degree of unsaturation will be more reactive than those of a lesser degree of unsaturation. Where the degree of unsaturation is low, it is desirable for best results to increase the proportion of the conjugated diene in the copolymer.

In addition to the attack at the carbon to carbon double bond which is believed to constitute the major part of the reaction, there may also be some substitution of halogen for hydrogen but,

in any event, the flnal result is the production of a product having an improved surface for textile fiber drafting. It should be remembered that the foregoing polymer formulas each represent a single polymer unit and highly polymerized products having a high molecular weight with an unsaturated bond in the polymer units will possess a high degree of unsaturation suflicient even after vulcanization to the desired degree to be highly receptive to the halogenation treatment.

It wi1l be understood that this is purely a surface treatment and that the reaction does not take place throughout the entire thickness of the apron. If the fiber drafting unit is rebuifed after use, because of wear, it will be necessary to retreat it in order to again provide the desired surface.

I have established that the reaction which takes place and provides the desired working surface is not an oxidation reaction which might be expected in the treatment of such organic materials with halogen and water. I have treated butadiene-acrylonitrile copolymers and other polymerization products having a high degree of unsaturation with hydrogen peroxide in ammonium hydroxide thereby liberating oxygen very rapidly and have found no substantial difference in the surface characteristics of the products so treated. On the other hand, I have treated the same materials with an organic solution of chlorine such as an ethylene dichloride solution of chlorine thus eliminating all oxygen and have obtained the same results as when the materials were .treated with a chlorine water solution. This establishes that the reaction is not an oxidation reaction but a halogenation reaction.

I have treated polymerization products which do not have the carbon to carbon double bond and have found that no substantial change in the surface characteristics occurs. For example, I have treated the material known as "Koroseal and having a polymer formula as follows:

The surface was not changed. Apparently, the reaction takes place only with those polymerization products having carbon to carbon double bonds or at least the reaction is sufliciently great to be important only in such compositions.

In the attached drawing:

4 Figure 1 is a diagrammatic view illustrating a so-called long draft apron as employed in the Saco Lowell-Roth system;

Figure 2 is a similar view showing the Whitin- Casablancas system; and

Figure 3 is a perspective view showing an apron having inner and outer working surfaces treated in accordance with my invention.

In both the Saco Lowell-Roth and Whitin- Casablancas systems as illustrated, the drafting aprons move over a stationary supporting bar. This bar is indicated at 2 in Figure 1 and at 3 in Figure 2. The apron 4 in Figure 1 is driven by a roll 5 and a tension roll 6 and guide' roll 'I are provided. The roving 8 is drafted between the pair of back rolls 9, front rolls l0, and intermediate roll i I. The fiber is supported during draft- 7 ing by the apron 4 moving over the stationary supporting bar I and the driving roll I, drafting tension being supplied to the apron by the tension roll I.

In the Whitin-Casablancas system shown in Figure 2, the drafting is accomplished between the pair of back rolls I 2 and front rolls II. In this system a pair of drafting aprons l4 and II is provided, the lower apron II is driven by roll I and the upper apron is driven by frictional en-' gagement with the lower driven apron. A guide roll I! is provided and this roll is weighted to obtain the desired pressure between the aprons. The roving i is supported and operated upon by the aprons moving over their stationary supporting bars 2 and rolls i0 and I1.

Figure 3 illustrates a typical drafting apronembodying my invention. It consists of an outer portion I8 of a synthetic polymerization product of an open-chain aliphatic conjugated diene such as the butadiene-acrylonitrile copolymer of the example previously referred to and an inner portion I! formed of the same composition and preferabl having a helically disposed reinforcing cord embedded therein; In this embodiment, both the inner and outer working surfaces are indicated as having been treated. Of course, with cots and other drafting elements where there is no problem of impaired movement only the outer working surface may be treated and in drafting aprons it may be desirable to treat but one of the surfaces, although the simplicity of the process where the article is immersed in the treating solution recommends itself for most articles.

For most textile drafting purposes oil resistance is desirable in the drafting element and, where this is a factor, the oil resistant polymerization products, such as the copolymers of butadiene and acrylonitrile. isoprene and acrylonitrile, and polymerized chloroprene will be generally preferred.

While I have illustrated and described certain preferred embodiments of my invention, it will be understood that the same may be otherwise embodied and practiced within the scope of the following claims.

I claim:

1. A lap-resistant textile fiber drafting element having a fiber working surface comprising the reaction product of a free halogen and a vulcanized synthetic polymerization product of -an openchain aliphatic conjugated diene, said polymerization product having carbon to carbon double 2. A lap-resistant textile fiber drafting element having a fiber working surface comprising the reaction product of free chlorine and a vulcanized synthetic polymerization product of an openchain aliphatic conjugated diene, said polymerization product having carbon to carbon double bonds, said fiber working surface being characterized by its lap resistance.

3. A lap-resistant textile fiber drafting element having a fiber working surface comprising the reaction product of a free halogen and a vulcanized copolymer of butadiene and acrylonitrile, said fiber working surface being characterized by its working surface being characterized by its lap resistance.

6. A lap-resistant textile fiber drafting element having a fiber working surface comprising the reaction product of a free halogenand a vulcanized polymerization product of chloroprene, said fiber working surface being characterized by its lap rebonds, said fiber working surface being characterized by its lap resistance.

sistance.

JOHN W. BAYMILLER.

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

r UNITED STATES PATENTS Number Name Date 1,532,234 Dennison Apr. 7, 1925 1,810,560 Garvey June 16, 1931 2,012,223 Cutler Aug. 20, 1935 2,126,733 Catt Aug. 16, 1938 2,132,268 -Mallard' Oct. 4, 1938 2,201,931 Sullivan May 21, 1940 2,287,780 Carman 1 .June 30, 1942 2,293,266 Mitchell A118. 18, 1942 2,304,656 Rockofi' Dec. 8, 1942 2,341,656 Rockofi' Feb. 15, 1944

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