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>\ a* PLASTICS FEBRUARY, 1948 FEBRUARY, 19*8 PLASTICS 85 pur sq. in. and a temperature of 150 degrees C. for one hour. The article produced was hard, insoluble, clear, transparent and free from fractures' Intcrpolymerization products of allyl crolonatc and unsuturalcd aIkyd resins are suitable for coatings or moulded articles. They are formed from allyl crolonatc and at least one unsaturated alkyd resin. Example: Allyl crolonatc, 10 parts, and , dieihylcne glycol malcute, 90 parts, yielded a hard, tough, insoluble and infusible interpolyrner when co-polymerized for 2 hrs. at 80 degrees C. in the, presence of 0.5 part benzoyl peroxide. When the proportions of ally! crotpnate and diethylene glycol maleate were ' reversed, a white, opaque, non-flowing gel was obtained after 24 hrs.' heating at -.80 degrees C. and a fairly hard gel with rubbery characteristics after healing for 144 hrs.,-`" Co-polymers with Vinyl or Vinylidcne Compounds To illustrate the variation in properties of co-polymers of vinyl compounds ;md imsatmuled allyl esters and clhers, vinyl acetate may . be mixed with I/25th, 1/I0th. I and 3 pier cent, of allyl crotonatc. I per cent, of benzoyl peroxide being added in each instance, and healed in completely lilted iron Masks for 90 hrs. at 35 degrees C,, the soft, flexible polymers being removed from the flasks and hardened by heating in air for 15-30 mins, at 100-120 degrees C. A product prepared in this manner from vinyl acetate alone is hard at room temperature, but is so soft at 120 degrees C. as to be almost liquid, and is easily , soluble in acetone. The products con taining allyl crotonate are equally hard at room temperature, but much less plastic and soluble, Ihc product containing l/25lh per cent, being a soft plastic at 12(1 degjecs C. and dissolving slowly in acetone. The product containing I/I0th per cent, being still plastic at 120 degrees C., but only partly soluble in acetone; thpse containing t or 3 per cent, are elastic but not plastic at 120 degrees CH and swelling somewhat in acetone with out dissolving.'1 * , REFERENCES (1) Shasvinijan Chemicals Lid,, mpuilidud rrtwi*, C. C. Ggfin, 1927. (2) U.S.P. 2,310.9W (1943), /. . Muscat, M. A. Pollack, F. Simla and n. A. Fronto, to Pittsburgh Plate Clou Co. (3) BJ>. 494.575 (1938). Distiller, Co. Lid., H. M. Stanley and H. P. Staudinger. (4) B.P. 530,37) n40). Distiller, Ca. Ltd. (S) B.P. 533,174 (1941), Distiller, Co. Ltd. (8) USJ>. 2,330.527 (1943). H, P- Stesudinfer, to Distillers Co. Ltd. (7) B.P. 547,328 (1942), BriliA Thoauon-Houston Co. Ltd, (*) US.P. 2^65,640 (194!), B. S. Carney andC. H. Alexander, to B. F. Goodrich Co. (9) U.S.P. 2,306,139 (1942). M. A. Pollack, to Piltsha,,k Plato Glass Co. (10) US.P. 2.260005 (1941), G. F. D'Alelio, to Ceneral Electric Co. (11) US.P. 2,202^46 (1940), & S. Garvey aad C. H. Ala- ander, tB,F. Goodrich Co. CELLULOSE ACETATE PLASTICS {continued jrctn page 69.) Mottles can be simply made by blend ing two batches of stock of different vis cosity and different colour at the rolling stage and then ^pressing as before. Another method is to drop dice cut from a blanket of one colour into stock of another colour whilst on the lulls, again followed by sheeting and pressing, etc. This type of treatment, however, can only produce simple and comparatively uncont rolled colour ctTccts. In some cases alter nate sheets of different colours are pressed together, sliced, and the sliced sheets cut down and stacked on end and rewelded into a block. For moire-type variations, the- bloet would then be cut, restacked and welded for a third lime. Grained-ivory finishes can be made by welding a block made up of alternate thin hides of dilferent shades of ivory, followed by slicing, cutting down, stacking vertically and rewelding. Finishes such as imitation mother-ofpearl and tortoiseshell are easy to make when only u rough imitation is required, but to produce a really first-class sheet, closely resembling he natural product, great skill is required; the exact method of producing these materials is kept a close secret. {To 6c continual.) Health Hazards for an! l0Acr^fe^? Some medico! aspects of handling rubber and plathcr, In manufacture or in uie. are iutrtftd by Or. George Blaine, of the itrangewayi Research Laboratory, Cambridge, jo the issue of "Chemical Products" far No,-Det,, 1947. By hind permission of that ' journal we give the' fallowing extracts. reaction thus dejwndsShjIitiiitJjp on the contents of the plastic mixTV. C* Polyvinyl chloride is extensively used in the production of anasthetic airways, etc., - in medical practice. Stoppers of penicillin solution containers cun also be made in p.v.c. provided the least reactive THE basic property to be considered type of material is used; with some from the me'dical point of view for polyvinyl stoppers rapid loss of penicillin any material which is in contact with potency has been recorded. human tissues', or to which such tissues , The hazards of manufacture for are exposed, is the, reaction elicited by i.t. acrylics are of a different kind. The A material cart be safety handled or used methyl methacrylate monomer is a strong only if it is proved by suitable experi - respiratory irritant, and good ventilation ments that it does not give rise to toxic 1 is essential to reduce the risk of exposure. reactions. If the material is both indis In larger concentrations it may cause pensable and somewhat toxic, precautions irritation and inflammation of the have to be devised tq minimize damage respiratory passages, inhaled, it may act to health. as a narcotic and convulsant. Persons The fact that rubber, manufacture is not used to it are liable to get headaches subject to the Dangerous Trades Regu when exposed to minimal concentrations. lations under Section (>0 of Ihc Factories Act is due to the solvents and accelerators which arc used. Skin irritation and resulting dermatoses It has little local action on the skin and few cases of dermatitis arc on tecoid. The polymer, however, produces no reaction whatsoever. jre the most common sequels of exposure Methyl methacrylate is used on a large la these solvents and accelerators. The scale in dental laboratory practice. Since toxicology of handling polyvinyl com the dental technique involves handling pounds is similar to that of rubber proces- and mixing into a doughy or paslc-like iing. Processing shops in the plastics ..mass, and is a process often done by industry, however, are, on the whole, of hand, the lack of cases of dermatitis is newer design than rubber factories and good evidence of its non-toxieity. In the hazard of dustborne irritants and - animal experiments, too, acrylic plastic lames is therefore reduced. ' was found to be the least irritant of all An investigation of. polyvinyl chloride plastics, creating only a minimal tissue compounds in the course of the last year reaction; there is no reaction from the revealed that the majority of welt-cured fully polymerized material. tad produced products have a good (issue tolerance. The tissue reaction elicited by polyvinyls is always a local one; it is marked by a defensive junction on Ihc part of the tissue into which it is embedded. Material containing no dye etkited the least i.amount of tissue ttactbn.' The dyes and plasticizers used teparately in control experiments,' were rirong protoplasmic poisons. The tissue Further evidence of the non-toxicity of methyl methacrylate is afforded in - brain surgery with it new method of using this plastie. Monomer and polymer mixed in suitable proportions, rapidly become tacky and soon after become fully plastic, in which stage the mixture can be moulded. This whole process can be done under sterile conditions, {Continued on page t08.) UCC 041224 -Spr- 10S PLASTICS FEBRUARY. 1944 HEALTH HAZARDS FOR P.V.C. AND ACRYLICS? iCcNJi.'iuit/ front AOL'r 83.) nude the easier by the strong antiseptic properties of the monomer. Such plastic masses have been implanted into skull gaps and the skin sewn over them whilst the moulded mass was still comparatively soft. Rapid polymerization takes place under normal conditions inside the body tissues, and during this process some free monomer escapes. There were, however, no general reactions on the part of the patients thus treated. Adhesive films for surgical use are' also made from acrylics. Here there does not seem to be any. contra-indication to the use of such films, other than irritable or inflamed skin. The cellulose plastics were among the first known plastics used as surgical appliances and dental prostheses. They set up a fairly marked irritant reaction, but it must be kept in mind that solvents and plasticizers are apt to create the reaction. The risks, however, are both a general and a local type of reaction, as with rubber solvents and accelerators; the precautions to be taken with regard to dust, fume and gas control are the same and the need for effective barrier creams or emulsions cannot be too strongly emphasized. Vol. XII. No. 130 MARCH, 1948 Profif/etorr AUhoging Director Editor' Office* HTf5*JLE PR|;ss LIMITED BOLAND E. DANGERF1ELD Index to Advertisers Page Albert*, Government of x Imperial Chemical Industries, Ltd, Almex Ltd. ,. xJviii Irene Products, Ud................... Ashdowns Ltd... Jetsop, Wn,, I Sons, Messrs. Bat*. A. E, .......................... Bafccllce Ltd. ., .. Bardey* Bank Ltd...................... Barber lit Duffy, Ltd.................. B.B. Chemical Co., Lid. Birkby't Ltd................................ Blackfriar* Engineering Co., Ltd. British Gas Council British Gcon, Ltd....................... British Industrial Plastics, Ltd, British Moulded Watties, Ltd. British Mouldcx Rubber Co., Ltd. British Resin Produces Led. .. Butcher, Henry, Co. BX Plastic*. Ltd. Byton Appliance Co., Ltd. .. Cattiin, Ltd. Chamberlain Willow* Cohen. George, Sons Co., Ltd. Cole, E. K., Ltd.......................... Cole, R. H., Co., Ltd. Cotlis, i., Sons, Ltd. Cornercrofc (Plastics), Ltd. .. Cryttalite, Ltd. (and Subsidiary ,. hri ,. xxxfv u .. lx ,. xiviii .. XJtxifl .. xlvi xxiv xliii Nx .. xxxvl .. I lx InsiIido Front Cover Ivi Insldlie Back Cover .. Mil .. iv . . aclie xxMii xlix xxxi .. xsvi shies) .. xl Jones. E. H. (Machine Tools), Ltd* Kent Mouldings Kcnur*. T. F-, lu Law, f. W.. Sons, Ltd. Londex, Ltd. . M.C.L. and Ropotitfea* Ltd, ., M.C.M. {Tools). Ltd. .. Melwood Thermoplastic!, Ltd. Micanit* Insulators Co., Ltd., The Mica Product* Ltd. Minittrr ol Fuel ud Power Ministry of Labour .. Ministry o( Supply Monsanto Chemicals, Ltd, Monsanto Chemicals Ltd, (Lunron). Moulded Product*, Lid. National Saving* Newell Engineering Co,, Page, W,, Sons moil Engineering Co., Ltd., TJm Peace, Harold E., Co., Lid. Potu Engineers, Ltd. Radio Heaters Ltd. Read Brea. (Enflsstrind, Ud. Rubber Improvement, Ltd. .. Detouecer Bros,, Ltd,., Runbaken Electrical Products, Ltd, . Dingwall, T. Ltd. .. (viii Schorl Matalialag Process, t Dohro. Ltd. Ixi Scott, Bader Co. Ltd, Dominion Export Co., Ltd. ,. Seaward Engineering Ltd, Duraplex (Plastics) Ud. .. Sehotapo Duratube Wire, Ltd, .. xlvi) SJIcosna Ltd. Erinoid, Ltd. .. .. .. Bade Cover Swala Cowliahaw, Ltd, Ether. Ltd.................................... .. xM Ttnaola*. Ltd. * .. Evans, Frederick W,, Ltd. Ferguson, Jimes, Sons, Ltd. .. lx Tarry, Herbert, Son*, Ltd.. Ml Thompson Norris Ltd. Ferodo, Ltd........................... .. i* Toolmakers Design* (Coventry), Ud. Firth, Thoa., John Brown Ltd. .. Vi Trapleex, Ltd, .. Firth-Vicker* Stainless Steels, Ltd. Floxtol Engineering Co., Ltd. I Tuffi*. RuuoU Co.. Ltd. .. llx Turner Brea. Asbwtoa Cm* Ud, Foe Chemical Engineering Work* Li .. Mi Tumor Mfg, Co, Ud, Fraser, Andrew, Ltd. .. ,. Galea, Gilbert ., .. . ,. vili U.K. Ptsstics. Ltd. ,, Ul UidlW Ebo.lt. loritru, ltd. oon Gardner, Wn Sons (Gloucester), Ltd. .. XXXV Unlnrol Tool., Ltd. . Gee, William, Ltd. xjiv Util**, Lid. .. Gosheron, John, Co,, Ltd, C.R.L. Plastics, Ltd.................... Ul VI*eo En,i,,v]ni Co. Lid. .. Ivi ' Wriwra Kueio udr.. i\i Haigh, John, Co., Ltd. .. Ilv Wltilni Tup* A A1>* Hri, <Sal*>, I HartfieM industrial Products Ltd, .. Ivi VniunMa ItuMor Linux. Ud. CONTENTS Editorials .. Page 110 Flexible Moulds from Vinyl Compounds, by Dr. H. Reichard 113 Cellulose Acetate Plastics, by Vivian Stannett IIS Cup and Saucer of Novel Design......................... 125 World's Industry Employs Plastics' ......................... 126 New Uses for Nylon Mono filament in Brush Making 128 . Plastics In Germany ,. 130 Perspex Caskets 131 Page Hard Nickel Electro-formed Moulds, by P. Spiro 132 Letters to the Editor 137- Production News 139 New Productions from the Moulding Shops.. 141 Quality Control in Plastic Moulding, by W. M. Halliday......................... 142 Microscopic Examination of Plastic Products, by J. H. Wreddon.............. 1S2 Patent Review 161 NOTICES "PLASTICS- b puhfahod in London, England, on th* eecond Wednesday of the month. Annuo--!--a--u-b-e--c--ri-ption frw*tmk. Stator period*. pro ret*. AkMinduswotrfucerdiovna*rt.Umeamttaenrteanmdulat-t-u--r-edJac-phr-o(hoe'f* HofeaadU 06c*of "PLASTICS" by the 24th of prtcedw* month to oaauxo fnoortian. HufQCait * Bowtiag Croon Un* London, E.CL hMTtkifmm* ."Awri.umJWload*.1'. Cdlo r r - - fyeadonw, Leaden, fdidw* Tifetiot^3636 (Fnvak Exchange). MidlaadOfficer--5, Suffolk Street, Birmingham, t. TtiepAoae - - - Mtdtad 4117-B.50, Hertford Strom. Coveniry. TtUpfoat - CetxnJru 62464. Northern Offie**--L Bra**iw*o*eStreet. Tthptar * - BfoMckaMncahr*ec50te3r8,-29,. Scoittah OfficeTrt--te1tr2a,mRon"EPertcdttuSntrrkeieMt, aGnctihuegiiocwr.". t T'ttatar - GUtgom CtnlruJ 9036.