Document 1g6oqmLvpVeKJyv53ddEEnL25

Votes on visit to Tfe-gy - Chemical Crrp^v. Cembrl . on November 27, 1934 end December 11, 1934 end to the Multlbestos Cor, -any.* 77eloole. on November 28, 1954. By: E. B. Elkins Officials met: ( Ur. Egan (chief chemist) Mr. Ferguson (plent manager) Ur. Leach Ur. Edwards Ur. Ross Mr. Jensen Mr. Taggart Mr. McMordie Mr. Bateson LiT Sl&^ld Mr. Martin Ur. Meera Mr. Stowe (engineer) (superintendent, Multibestos) Hie more important contacts are underlined. Note: Due to the nature of its business many of the processes of this company are unique. Items which it is believed mey not be general practice ere marked with an asterisk and should be treeted as confidential until passed upon by an official of th9 company. The Dewey and limy Chemical Carr'any manufactures primarily latex cements and alli*d products, such es solvent rubber cements, rubberized fabrics, and rubber*bonded brake linings. It was because of their developments in this last field that they acquired the Multlbestos Company, which manufactures brake linings and clutch facings of all types. Eewey end limy Company Mr. 2gen showed me about the plant in Cambridge. Latex cements: Rubber latex is obtained in solutions containing 35, 6C or 75 per cent solids. In the *ilute solutions there is about three fourths of a per cent of ammonia, which keeps the solution at a pH of 11, and so prevents fermentation end spoilage. In the most concentrated solutions the alkalinity la maintained by a mixture of ceustic potash and a potassium cocoanut oil soap. Lmnonia is preferable for most purposes because it evaporates off. Its concentration is so low that it is no problem except when the cement or compound is used in very large quantities. ^Various materials such as pigments end fillers are Bdded to the l6t3Z solution in making the compound. One such material ia a modifying soap made from beeswax and emmenia under high pressure. Sulfur is added whenever it ia desirable and possible to cure the rubber in the cement or other product. In the linings for tin cans sulfur can not be used but fortunately an uncured material la more aetlsfactory. For many purposes a latex cement is inferior to an artificial rubber emulsion, made by masticating vigorously coagulated rubber and then dispersing it with protective colloids and other suitable chemicals. A cement of this type seemed much finer and more homogeneous than corresponding latex cements, and its cost was said to be the same. Latex cements ere of interest to us because they cdmpete with solvent Rubber cements. One of the chief uses of benzol is as a solvent ror the latter. Tot some purposes non--toxic non-inflammable latex cements are better substitutes for toxic^ inflammable benzol cements than the slightly toxic but inflammable naptha cemsnts. ISr. Ferguson said that there had been a siring anay from latex sealing compounds toward solvent compounds, but that he felt that its peek had passed end the immediate future would see an Increased use of the l6tex products. Solvent room: This company makso both benzol end naphtha solvent cementB and com pounds. The .letter constitute about tiro thirds of the total, and it was said that probably next yerr three quarters of the solvent compounds would be mode from naphtha. The so-called solvent roam is th9 second floor of an isolated building. It is <?bout 35r x IS* x 8', and contains two mixers, for naphtha and benzol products, respectively. Each mixer holds about e hundred gallons. Exposure to the solvent raey occur chiefly in three pieces; the pump room, the solvent room, enc muddier room, in which the finished cement is - loaded into drums for shipment. In the pump room there is some leakege of vepor, or seemed to be, but the pumps ere operated from outside, and the room is rerely entered. In filling the drums there is undoubtedly some exposure, but the greatest hazerd is certeinly in the solvent room. The solvent is ordinarily pumped through a meter into the mixer. The stirrers ere heavy spiral shaped knives which twist and tear the smell pieces of rubber which are introduced. Some beat is evolved in trie operation, so that the temperrture of the mixture is raised, the outside of the mixer being above body temperature when the process wes observed. The mixers are closed exce'jt for an opening in the top Fbout IP" x 10" which is covered loosely exce :t when mf-terials ere being added, 7/hen the batch is being in s'ected, and ./hen it Is being emptied. The addition of rubber (cut in small pieces) takes some time, as the saverel layers are torn epert by hand or they are fed into the machine. Some other m^tericls, such as wax, are usually ad/led. In the operation observed inspections of the batch as it was being mixed were frequent. As the top of the mixer is about five feet from the floor the tendency is for the workman to put his face close to the opening in looking in et the batch. After two to eight hours, depending chiefly on the kind of rubber used, the mixer i6 tipped on its side and the batch of finished product is dumped through an opening in the floor into the muddler. The dumping operation observed took four minutes, including the time required to rake out the residual compound. The opening in the mixer through which the substance is poured Is about three feet from the floor, and the operator stands three to four feet ewey except when he is cleaning out the residue. The extremely viscous end elastic mess ./as said to contain only thirty per cent of solids. Its vapor pressure would presumably be appreciably more than 70 per cent of that of pure benzol, but the viscosity of the mixture should cut down Its rate of evapora tion considerably. A blower wes operating In the well opposite the nixfer, near the floor, and above It the window was opened. The operator was between the window and the mixer, but a little to one side most of the time. The efficiency of this system of ventilation seems somewhat questionable. Tests on the elr in this room (made by the insurance company) showed satisfactory conditions, however, it was said. The men working on this job are given blood counts every three months end as a rule are transferred after six to nine montkB. No real cases of benzol poisoning heva been encountered. AH dope: This impregnating material, is a mixture of about five parts coal tar pitch end one part toluol. The componsnts are heated in mixing, and ventilating equipment has been ordered for the process. The fumes did not seem bad at the time a finished batch was observed in the open mixer. Rubber bonded brake lining material: Certain brake linings, especially those for heavy work, are made from asbestos to which carbon black and other substances may be added, end rubber latex. The various materials ere mixed in a paper beating machine, spread on a wire screen and the weter sucked out, than pressed in a hydraulic press, cured and brought' to the proper thickness ./1th a sanding machine. The last operation is well ventilated, but the method of feeding the paper beater was said to be dusty and needs Improvement. Probably some such method*as was worked out at Walpole will be applied here. None of these processes were in operation. Artifical leather: A soft absorbent paper is passed through a latex solution containing sulfur, coloring natter, etc., end thon over a series or heated rolls where the water end ummonia are given off and the rubber is cured. An exhaust system provides for the removal of the ammonia given off (estimated at three pounds, or about sixty cubic feet, per hour). It is necessary to stop the machine for brief periods in order to attach new rolls of neper. If the ston is ^or too lor.i- the paper in contact with the hot rolls tends to disintegrate. Sven the short stops unavoidably made nay cause variations in quality in the finished material. The rubberized sheet is psored through a calender to bring it to the proper thickness. T.7c or more sheets ere often cemented together, sometimes two cr throe rolls being combined on e machine similar to the impregnating machine, but smaller. No provision for the removal of ammonia is mode in this case, but there was no appreciable odor of emcnia around the machine. If still thicker sheets are to be made, pieces about fivs feet square are cemented together by hand. In the operation observed e naphtha solvent cement was used. Other products: Soda lime, used in ges masks for absorbing phosgene, chlorine and acid gases, is nude in some quantity. Zinc chloride solutions and zinc erunonium. chloride crystals are also mads. Sore dermatitis has been caused by these materials. Chloroform end toluene ere used as preservatives. Carbon tetra chloride la also used for sane purposes. Apparently these are used In rel atively small amounts. Another small use of benzol Is in cleaning out drums. s The Multibestos Company Ur. Mcltordie, who designed e large part of the ventilating equipment used at the plent, showed me about. There have been numerous cases of asbestosis developed here, end as a result the methods of manufacture have been greatly modified. TOie carding proc ess has been dropped, the yarn being bought already spun, end a wet weave sub stituted for a dry weave process. Ur. Bateson said that more oases of asbestosis were developed in the weave room where the dust count was about seven and a halfmillion particles per cubic foot, than in the carding room, where the dust count was much higher. The most recent counts ran from half a million to two million, except at a carboloy saw, where it was 6.7 million, end at the paper beater during Its feeding (21 million). A new process has been developed for feeding the paper.beater the use of the carboloy saw is discouraged pending its removal, and the general ventilation has been greatly improved since these counts were made. Woven fabrics are used chiefly for brake linings, but for some clutch fecingB ea well. Most of the latter and some brake linings, especially for heavy brakes, are moulded, or made originally es an asbestos paper. For impregnating materials asphelt, chinawood oil, and bek -lite resins are used. Rubber bonded linings are not im_.r3gnE.ted; the rubber bonding is done* in Cambridge, but all cutting, shaping and finishing is done in .'clpole. Weave room; The yrm consists of cctton and asbestos fibre wound erc-und e snail wire. The warn is dry as it leaves the spools but passes over a vet roll before -going through the guide so that the dust given off by the vigorous agitation of the dry warp in tr.e weaving process is largely eliminated, since the yarn is wet at this stage. The spindles of weaving: yarn are soEhed in ?/etar before use. The Icon spools of cry yarn are shaken somewhet but undoubtedly by far the largest pert of the potential dust is prevented from coning off. *0n some of th3 loons e process of im-rsgntting the yarn as it la woven is being tried. The roll wet with weter is replecod with one wet with impregna ting solution, in most cases asphalt in kerosene. This is eu.posed to give a more thorough impregnation and eliminates a process. It has the .disadvantage of dirtying up the loon, however, and the fumes of the solution contaminate the sir of the weave room. A solution of resin was also being applied in this way; they have succeeded in eliminating toluol from th solvent for these mixtures. On one section of a loom a water emulsion of a resin lm^regnant wes being tried, it being both non-toxic and non-inflammable. The fum-'s of kerosene near the loons using the asphaltic impragnent were sonswhat obnoxious. Impregnating room: The method still used for most of the woven linings is thft of impreg nating the fabric after it is woven. A long strip is run through e bath of solu tion, before and after which are placed drying ovens. Conditions in this room seemed setisfectrry. 6 Grinding room: . Hers the clutch facings and brake linings are ground down to the proper size, the required holes are drilled, etc., and in this room the moat strenuous efforts In ventilrtion have been mede. The removal of visible dust seemed almost perfect in the case of all the grinding operations observed. TCie chief source of dust seemed to lie In the handling of piles of articles In loading or unlosdinr s mechlne. In some ceses ventilation was even pro vided for these operations. One of the men operating an inside grinder (for the inside of clutch facings) wore a respirator, however. - Clutch department: In the process of making moulded brake linings and specially clutch facings, asbestos is fed into a paper beating machine, where It is mixed with water, pigments, fillers end a little red lead, which helps the lmpragnant to harden. From here it is pumped to the paper machine where a layer of the mixture is sprcr.d continuously on an andless belt, the water drained off, end the re sulting sheet of asbestos paper is removed, pressed, end cut up. Formerly the act of feeding asbestos into this mechine wes very dusty. JTcw the bags of asbestos are emptied into a chute (in an enclosed roam on thesecond floor) end the weter for the mixture Is sprayed in simultaneously, wetting down the asbestos so that It is soaked with water when it enters the beater, and little or no dust is given off. The man handling the bags of asbestos wears a respiretor, the operation taking but a few minutes. The room where this wes done seemed surprisingly free from visible dust. This s&uned'tc ms e vary setisf sst'ry, common sense end economical solution of this particular problem. Twenty pounds of rad laud ere sprinkled with e hand scoop into each batch mixed up in tho paper bact=r. This is heavier then many lead compounds end none of it seemed tc be dissipated in the form of dust. I understood the workman to say that tha maximum output of tha machine was five batches a day. Clutch impregnating room: Lost of the clutch facings ere impregnated with AR dopo, a solution of e coal tar pitch in toluol, which is made in the Cambridge plant. A raok about 4* x 3* x 6' is filled with elute':: facings and tl.en submerged in one of the tanks of dope, of which `bare era three or ""our in a room about 28* x 12* x 6*. The solution is kept at SC degrees ?. or higher, and the tenks are covered except v/her the solution cr solvent is bein_ added, when the rack of clutch facings Is heinc introduced, and -.hen the clutch facings heve Just bean re moved and the excess solution is allowed to drain beck into the tenks. There is no ventilation in this room and the fumes ere said to be had ct times. The foreman said h9 wouldn't enter the piece on a damp day, end that the men often got Jegs from the fumes. One of the men said he wes often neds dizzy by the toluol veper, er.d thrt he and his colltsegue suffered con siderable discomfort generally. It seemed to me thct unless these men were exaggerating greatly the 'oonditions should by all means be Improved. JL determination of the toluol concentration in the air might be worth while. Two or three willow blowers, to be operated when the tanks were open, might Improve the situation suffi ciently for practical purposes. iThile the insurance company was said to have investigated these con ditions and to be satisfied, and while it is true that toluol is not as In sidious a poison as benzol, or asbestos dust, and while there is some doubt about its ever causing chronic poisoning, it is still classified with benzol in Bulletin 582 of the TJ. S. Dept, of Labor. Certainly conditions such as apparently exist here should not be tolerated if they can be easily remedied. Drums containing toluol were in soma cases lebelled es containing alcohol. ^ General: Ur. licUordie said that some dermatitis was caused by the formaldehyde used with tar acid in the manufactura of bakelite resins. Respirators were ?/orn on meny odd Jobs, such as sweeping the flcor, using the carboloy sew, etc. In general the firm has been edmircbly thorough, Ingenious, end, I believe, effective In the steps taken to eliminate dusty conditions. 7