Document pp9q0n44NjGR73dmMJ3G12Xgw

APR 1 1971 fit m WIKfi flpaad vog) rV7p, &% x>i i/wiO aa-'s (Sterna??- qpoc* (Sliiiifi'*' -' i rr e#w-, -.-eses. rtpwaa? ''-H ' AROCLORS IN POLYESTER AND EPOXY RESINS * MONSANTO CHEMICALS LIMITED * Monsanto ff HONS 078353 \ AROCLORS IN POLYESTER AND EPOXY RESINS Ticmnical Slavics BuuxnH No. G}/1 Copyright Kaaonod ftMUM 1960 I Monsanto l_M_J MONSANTO CHEMICALS LIMITED MONSANTO HOUSE, 10-18 VICTORIA STREET, LONDON, S.W.l HONS 078354 AROCLORS IN POLYESTER AND EPOXY RESINS Polyester glass-fibre laminates are becoming more and more widely used Tor the manu facture of industrial and consumer goods, their chief recommendation being their high trength-to-weight ratio and the ease with which large and complex forms can be fabri cated. Certain applications of polyester laminates call for the modification of some of their inherent characteristics. Those which most commonly require modification are fire- resistance and mechanical properties, and for both purposes the Aroclors are highly suitable. The Aroclors are a range of chlorinated diphenyls and polyphenyls, three of which have proved to be economical and efficient as dual-purpose fire-retardants and plasticisers. The high proportion ofavailable chlorine they contain imparts adequate self-extinguishing properties, while their plasticising powers increase the strength of the resin to a degree equal to that gained by a more expensive plasticising polyester. The recommended Aroclors are readily mis cible with uncured polyesters at the con centrations necessary to impart fire resistance, though the solid ones dissolve more easily at fO'C. Once mixed they have no tendency to separate on standing nor to migrate to the surface of the cured resin. In this respect they ate superior to certain other chlorinated com pounds whose poor compatibility with poly esters could lead to separation alter mixing and thus to unsightly blooming and greasiness on the surface ofthe cured resin. The Aroclors also have the advantage of being practically odourless. Acaocua k a H The Aroclors may be used to similar effect in epoxy resins as well as polyesters, being com patible with both types. Full details of all the Aroclors, which range in physical form from mobile, oily liquids to hard, opaque resins, are given in Technical Service Bulletin G.l. POLYESTER RESINS (1) fire Resistance. Of the possible methods of improving the fire resistance of polyester resins, the use of the Aroclors has the advantage of being both effective and economical. The Aroclors recommended as fire retardants are the soft, sticky resin, Aroclor 1260, and the hard, brittle resins, Aroclors 4465 and 5460. These compounds are more highly chlorinated and less volatile than the mobile liquids, and both these properties improve their efficiency as fire retardants. Like other fire retardants for polyesters, the Aroclors are generally used in combination with antimony trioxide, itselfa fire retardant. This combination is particularly effective, as the two substances are synergistic and to gether give a degree of fire resistance which is adequate for most possible uses. The Aroclor imparts self-extinguishing properties to the resin and the antimony trioxide reduces afterglow. The latter also plays the part of an inert filler, replacing a proportion of which ever of the many possible fillers is being used, and is usually included even in inherently fire resistant resins which contain chemically combined chlorine in the polyester molecule. The properties of the Aroclors as fire retard ants were evaluated in a series of laboratory tests using a general purpose polyester with a itdTnde Mark. 3 MCNS 078355 styrene content of 35%. The catalyst used was 2% of a 60% solution of methyl ethyl ketone peroxide in dibutyl phthalate, added after the Aroclor. 2% of a 1% solution of coball napbthenate was used as an acceler ator. Specimens measuring 9'X|'X {' were east in waxed moulds without reinforcement. The test method used was based on that laid down in the Ministry of Supply Aircraft Specification for unsaturated polyester resins, DTD 3S37 Appendix 10. It consisted of clamping the test specimen in a support with its longitudinal axis horizontal and its trans- again failed to continue burning the material was classed as self-extinguishing. The results obtained are shown in Table I. (2) Effect on Physical Properties. Among the special qualities of the Arodors is the desirable plasticising effect they have on the cured resin. For general purpose poly esters a special plasticising polyester is norm ally included to increase the flexural strength ofthe naturally brittle resin. When an Aroclor is included it effects a similar improvement and thus makes the addition of a more expensive plasticising polyester unnecessary. TABLE I mu RETARDANCY Per cent of antimony trioxide and Aroclor 5 per cent Aroclor 1260 Semi* inflammable 7} percent Semi inflammable Aroclor 4465 Aroclor 5460* Inflammable Self extinguishing SO secs. Self extinguishing 5 secs. No test 10 per cent Self extinguishing 30 secs. Self extinguishing 3 secs. Self extinguishing 3 secs. 15 per cent Self extinguishing Immediate Self extinguishing Immediate Self extinguishing Immediate *21% addtioa ot Arador 5440 is huoflkMat to make tbs poiyaster teir^atiaeuialuna. verse axis inclined at 45*, and placing a bunsen burner with the tip of the flame 1' to 1* in height just in contact with the end of the specimen. At the end of 30 seconds, the flame was removed and the specimen allowed to burn. If burning did not continue, the flame was replaced for a further 30 seconds immediately it ceased, and if the specimen Specimens for mechanical testing were pre pared from laminates with four plies of 1J oz. woven glasscloth, giving a final thickness of approximately -hr' and a resin content of approximately 50%. Woven glasscloth was used in preference to chopped strand mat to ensure that results should be as consistent as possible, the strength of this form of MOMS 078356 reinforcement varying by only 5 %, compared with the 20% variation to' be expected from chopped strand mat . The following standard methods of test were used to determine the mechanical properties of 4* x 1* bars cut from the laminates: flexural strength, ASTM D.790-49T; impact strength, falling weight, B.S.2782:1957, Part 3, Method 3068, modified by the use of beam specimens on a 1* bridge support The effect of the Arodors on the mechanical poses of lamination. For fire-resistant surface coatings, the solid Aroclors are preferred. EPOXY RESINS Epoxy resins, like polyesters, are inflammable unless a fire-retardant additive is included, and those Aroclors which are used in poly esters are equally effective at similar con centrations in epoxies. They are completely miscible with epoxy resins, though Arodora 4465 and 5460 dissolve more readily at 60*C. ft TABLE II II MECHANICAL HOHaUES Resin Formulation Unmodified Polyester Polyester +plasticising polyester Polyester +Aroclor 1260 Polyester +Arodor 4465 Polyester +Aroclor 5460 Elastic Modulus Flexural Strength in bending Impact Strength (P--i) (p.s.i. x 10"*) (ft. lb.) 47,210 21-9 1-73 10% 20% 43,310 39,930 204) 15-6 1-64 1-24 10% 20% 45,600 33,880 20-9 16-9 1-33 2-04 10% 20% 40,740 33,390 21-9 12-9 1-41 2-48 10% 20% 37,400 35,890 170 15-5 1-85 306 properties of polyester resins is shown in Table II. It will be seen thatat a concentration of 10% (enough for purposes of fire-retardance) none of the Aroclors reduced the flexural strength of the cured resin signifi cantly, and that their effect was comparable with that of a plasticising polyester. At 20% addition, the impact strength of the laminate is improved. Of the three, Arodor 1260 reduces the flexural strength less than the olid Aroclors, and is recommended for pur Some diminution of the characteristic mech anical properties ofepoxies must be expected, though careful formulation will enable the manufacturer to strike a balance between fire resistance and strength for applications where the former property is essential. Antimony trioxide is included at the same concentration as the Arodor since the two together are more effective than Aroclor alone. The same laboratory test methods were em ployed as for polyesters, using a liquid epoxy WCNS 0 7835 7 1 rain (Shell Epikote 134) cured with 1% diethylenelriaininc, added after the epoxy ram, antimony trioxide and Aroclor were mixed. Specimen! were prepared in waxed mould! 9'x x (' and the results obtained an shown in Table IQ. If Arodors are spilled on the slrin, it should be washed with soap and water. If accidental burns occur from contact with hot Aroclorx, the burn should be treated in the same way as an ordinary burn. Aroclor adhering to the burned area should be removed carefully by TABLE m Percent addition of Aroclor and antimony trioxide 5 percent 7| percent "\ 10 per cent 15 per cent Aroclor 1242 Inflammable ' NO test Inflammable Self30 secs. Aroclor 1260 Aroclor 4465 Aroclor 5460 > Inflammable Inflammable Inflammable .--- " Semi inflammable Semi inflammable Self extinguishing 40 xctr Self extinguishing 30stcs. Self extinguishing Immediate -Seir- --------- Seir -- extinguishing extinguishing 30xa. Immediate Self extinguishing ~30xa. ` Self extinguishing Immediate ~ HANDLING AND TOXICITY The Arodors are non-oxidising and non corrosive. and they am-not-hydeolysed-by water, alkalis or acids. At ordinary tempera tures they have not presented industrial toxi cological problems, but they should never theless be handled with care and should not be allowed to come into contact with the skin, through which they are absorbed. repeated washing with soap and water, or a vegetable oil may be used. Experimental work onanimalsindkates that the maximum safe concentration of vapours in workrooms is in the range of 0-5 to 1-0 milligrams per cubic metre of air, and where vapours may be en countered, local exhaust ventilation together with general workroom exhaust is necessary. 6 v vrw HONS 078358 Every effort has been made to ensure that the Information in this publication is reliable, but as the conditions under which it may be applied an beyond our control, we cannot accept responsibilityfor any results of Its use. Fonrn N*. P.1.649 - El - 6001. m4 priMl ky Tk* Cktiwtak Nm, lii<^ N.ll HCNS Q7835S