US 2373876 A
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April 17, 1945. R, CUTLER 2,373,876
TEXTILE FIBER WORKING UNIT Filed Aug. 3, 1940 ATTORNEY.
attributed to static electricity, and it Patented Apr. 17, 1945 UNITED .STATES PATENT OFF] 2,873,876 TEXTILE FIBER WORKING UNIT Roger Wilson Cutler, Boston, Mass. Application August 3, 1940, Serial No. 350,896 g 7 Claims. (Cl. 19-143) This invention relates to rolls, aprons, and similar devices used in various branches of the textile industry for such purposes as drawing, feeding, or otherwise working textile fibers. The invention will be herein disclosed as embodied in a top roll of the type customarily used in the drawing mechanisms of cotton spinning and roving frames.
Such a drawing mechanism comprises two or more pairs of rolls, arranged one in advance of the other, for gripping and feeding cotton slivers toward the spindles. During this feeding movement the slivers are drawn out or attenuated to reduce them to the proper size and to arrange the fibers in a more nearly parallel relationship. In order to improve the character of the grip of the rolls on the slivers the top rolls are equipped with yielding jackets or covers, such as cork, or leather stretched over an underlying layer of felt.
blesome condition always present is the tendency cling to the yielding surface of the front top roll action is commonly referred to as a lap-up and it is very likely to occur immediately following the breakage of any strand between the front rolls and the spindle. It is a condition commonly is objectlonable not only because it interrupts the cover on the Thus a lap-up is very likely to require the replacement of the roll on which it occurs.
A fair idea of the frequency of this occurrence in a spinning room may be gained from the fact that it is practically the universal custom in cotton mills to keep a record of the ends-down" per thousand spindle hours. As a rule the number will run somewhere between twenty and fifty per thousand spindles per hour. Anything under twenty-five is regarded as and a typical number is about thirty-five. most of the cases where an lap-up results. of lap-ups with In end-down occurs a Consequently, when the number spindles per hour, the rolls are considered to be substantially static free. In this connection it and to wind up around it. This exceptionally good, 1
for the relatively high humidity normally maintained in a spinning room is to assist in controlling this factor of static electricity.
The inherent resilience of rubber would naturally lead one to infer: that this would be an ideal material for a top roll'cover, and it was proposed long ago to make roll' covers of this material. They proved, however, to be highly unsatisfactory, chiefly for three reasons: Y
1) They were exceedingly troublesome from a static or lap-up standpoint.
(2) They deteriorated rapidly due to the action of the oily constituents in the cotton and such lubricating oils and greases as necessarily came in contact with them.
(3) They oxidized and hardened up after a relatively short period of wear.
For these reasons the use of rubber roll covers has practically disappeared in connection with cotton spinning. When the new synthetic rubbers of the more elastic and oil-resistant type, market, it was attempted to use them as roll covers, and they were successful in avoiding the last two objections above mentioned to the natural rubber compositions. They were equally as unsatisfactory as the latter, however, in their static characteristics.
Applicant succeeded in overcoming this difficharacteristics had been very greatly modified.
In the commercial manufacture of these synthetic rubber compositions, however, diiliculties in control have appeared ,tvhich seem to be characteristic of this class of compounds, and the present invention aims to improv and perfect rolls of this type with a view to overcoming these difiiculties.
The nature of the invention will be readily understood from the following description when read in connection with the accompanying drawing, and the novel features will be particularly pointed out in the appended claims.
In the drawing, 1
Figure 1 is a front elevation, partly in section, showing a top roll made in accordance with this invention; and
Fig. 2 is an end view of the roll shown in Fig. 1.
2 asrasre The roll illustrated in the drawing comprises a lents and alternatives for them will be readily solid metal body of the usual shape provided with understood by those skilled in this art, with the two bosses 2-2 separated by. an intervening" "neck" '8 of reduced diameter and provided with the usual stub shafts or gudgeons 4-4 projecting from opposite ends. thereof. The bosses customarily are roughened in some appropriate manner to assist in holding in place the roll covers 5-5. Usually these covers are made in the form of tubing and they are anchored on the bosses either by their own resilience or with the aid of an adhesive.
As above indicated, the present invention is especially concerned with the characteristics of these cots or covers 8 andalso with those considerations responsible for variationsin these elements, or in other words, for the lack of uniformity in the physical characteristics of these' cots.v These factors have been exceedingly dinicult to discover. Among the various expedients tried in an endeavor to locate and cure the trouble were difierent fillers, additives and modifiers used in the compositions of which the covers disclosed in applicants earlier patent were made. In the course of these experiments it was found that the substitution of acetylene black for the soft gas black of the formula given in the patent produced exceptionally favorable and uniform resultS.
This particular form of black is understood to be produced by the thermal decomposition of acetylene gas. As is well known, the acetylene molecule is very simple, consisting simply of two atoms each of carbon and hydrogen, and it is thought that this may be responsible for the fact that the acetylene black is an exceptionally pure form of finely divided carbon having unique properties as compared to other blacks, one of such properties being that it approaches rather closely the character of finely divided graphite. Just why this material should operate more satisfactorily and simplify the matter of control by producing compositions having a greater degree of uniformity and better static dissipating characteristics is not at all clear. It may perhaps be due, at least in some measure, to the fact that it is a more nearly pure form of carbon, its particle size is smaller, or-that it has less tendency to polymerize than the blacks produced from hydrocarbon compounds. As to these matters applicant ventures no opinion but merely recites the facts. "j
Acetylene black is commonly obtainable in a somewhat compressed form and I have found it more convenient to use that grade known as the "Fifty Percent. Compression Grade" which weighs approximately six and one-quarter pounds per cubic foot. The more highly compressed grades or those not compressed at all can, however, be used if desired.
Also, another formula which has proved very satisfactory, and in some respects is preferred, is as follows:
Parts by weight Neoprene 100 Altax 1 Extra light calcined magnesia 4 Neozone D 2 50% compression acetylene black 40 Paraflin wax 1 Stearic acid 1 Process oil '2 Zinc oxide 5 The nature of these constituents and equivapossible exception of the Altax. This is a dispersing agent readily obtainable in the market under this name. The process oil is included in this formula because the compound is intended to be extruded as tubing, and such a constituent is useful in facilitating this operation. Naturally the fillers and other compounding agents to be used with the synthetic rubber base and with the acetylene black will be selected in accordance with the requirements of the particular product to be made. -The formula above given ha been found highly satisfactory for the drawing roll covers of spinning and roving frames. In them a high degree of resistance to abrasion, good elasticity, and a hardness of somewhere between 60 and 90, as measured on a Shore durometer, customarily are required. The proportion of the synthetic rubber base used also will, of course, be varied in accordance with the requirements of individual products. Usually, however, it forms somewhere between 16% and 65% of the total weight of the composition.
If acetylene black is substituted for the soft gas black of the formula given in the patent above mentioned, the proportion of it can be reduced-while still producing a roll cover havin satisfactory static dissipating properties. Or, a better roll can be made with the same weight of acetylene black as that called for by the formula in the patent. In fact, there seems to be a critical P int in the proportion of the acetylene black used with-reference to the static characteristics of the product. This point is between 30% and of the black figured on the weight of the Neoprene or other synthetic rubber base. The proportion of acetylene black may be increased above 40% without unfavorable results, so far as static characteristics are concerned and,- in fact, with more favorable results up to even 100%, or more, of the weight of the Neoprene. However, a point ultimately is reached at which the proportion of carbon begins to mark the fibers and such a result obviously cannot be tolerated. Moreover, an excessive loading with acetylene black has the effect of reducing the elongation and elasticity of the product. Where high elongation is desirable this acetylene black is not as satisfactory as channel black, but the former can be used with the letter or with other blacks in such proportions as to yield a product having both a high degree of elongation and also the electrical characteristics desirable from the standpoint of rapid dispersion of static. It has been found entirely possible to replace a small proportion (less than 10%) of the acetylene black with exceptionally finely divided graphite, such as that known as air-spun micromatic graphite, while still producing a satisfactory product. For roll covers there is ordinarily no object in making this substitution, and the proportion of acetylene carbon should in no ca e be less than 20%, by weight, of the synthetic rubber base. It is far more preferable to use a minimum of 40%.
In performing the milling or mixing operations, no special precautions need be taken except that it is preferable to work the mix as little as possible after the acetylene black has been added. Just the reason for this is not altogether clear, but it has been determined that acetylene black is of the acicular, fibrous or chain type, and it is believed that this fact is responsible, in some way or other, for its superior static dispersing characteristics. In any event, excessive milling seems to have a somewhat adverse effect on the properties of these r011 covers. While the size of the acetylene black fibers is extremely small, usually not over two microns in length, it seems probable that excessive milling breaks up these particles even further with the adverse results just mentioned.
The general physical characteristics of these covers should resemble closely those disclosed in my earlier patent. That is, for drawing rolls the hardness should run somewhere within the limits mentioned, although for some units the hardness may be reduced very materially, say as low as 25, while for feed rolls it often should be higher, say in the neighborhood of 95. Diluents, coloring materials, and various other ingredients designed to modify the characteristics of-the cover for particular uses also may, of course, be added.
The synthetic rubbers best suited to use in the manufacture of drawing rolls are those of the highly elastic type referred to in my earlier patent. Of these the polymerized halogenated acetylenes are preferred and that known as Neoprene, chloroprene, chlorobutadiene, or 2 chloro- 1:3-butadiene is the best. This compound is now readily available. Bromobutadiene can also be used, but is not as good. For many purposes, also, other polymers of butadiene are very satisfactory. Synthetic rubbers of the olefin polysulfide type also work well for some purposes. Where high elasticity and good nerve and snapback are desirable, the Neoprene is superior to all the others.
Such products as those above described having at least approximately 40 parts of acetylene black to 100 parts of Neoprene give exceptionally uniform results and are superior from an operating standpoint even to the rolls produced by the specific formula set forth in my prior patent. No difficulty with problems of control have been experienced with these compounds containing such proportions of acetylene black as those above mentioned. The product also has good surface characteristics and the fiber feeding and drafting qualities desirable in an article of this character.
Having thus described my invention, what I desire to claim as new is:
1. A fiber working unit for textile machines provided with a surface layer having as an essential constituent a base of a highly elastic synthetic rubber of any one of the following types:
polymerized butadiene, chloroprene, bromobutadiene, or olefin polysulfide; said base being compounded with other oonstituents serving to produce a product highly resistant to abrasion and substantially static free under normal working conditions, said layer containing a proportion of acetylene black equivalent to at least 40% of the weight of said base.
2. A fiber working unit for textile machines provided with a surface layer having as an essential constituent a base of a highly elastic synthetic rubber of the polymerized halogenated acetylene type; said base being compounded with other constituents serving to give it the required elasticity and resistance to abrasion, and said constituents also including a suficient proportion of a carbon black of the acicular type to give said surface layer the characteristic of being unable to carry a sufficient static charge to cause the fifber on which it works to adhere to it under normal working conditions, said proportion being equal to between 30% and 100% of the weight of said base.
3. A fiber working roll according to preceding claim 2, containing acetylene 'black in a proportion of at least 40% of the weight of said base.
4. A fiber working roll according to preceding claim 2, in which said layer has a hardness of at least as measured on a Shore durometer and contains acetylene black in a proportion of at least 30% of the weight of said base.
5. A fiber working unit according to preceding claim 2, in which said synthetic rubber base forms from 16% to of the weight of the compound.
6. A drawing roll for spinning and roving frames comprising a metal body and a resilient fiber engaging cover thereon, the composition of said cover including, as an essential constituent, a base of chloroprene compounded with ingredients serving to give it a high degree of elasticity and good resistance to abrasion, and also including as an important constituent a sufiicient proportion of acetylene :black to make said cover substantially static free under normal working conditions, said proportion being equivalent to at least 30% of the weight of the base.
7. A fiber provided with a surface layer having as an essential constituent a base of a highly elastic synthetic rubber of any one of the following types: poly-, merized butadiene, chloroprene, bromobutadiene, or olefin polysulfide; said base being compounded with other constituents serving to produce a product highly resistant to abrasion and substantially static free under normal working conditions, said layer containing a proportion of acetylene black equivalent to at least 20% of the weight of said base and also containing a substantial proportion of exceptionally finely divided graphite, such proportion, however, being less than 10% 0f the weight of said base.
ROGER WILSON CUTLER.
working unit for textile machines.