Document rBR18LabGv7n2zXb2gnrE7yJa

,J APR 1 1971 Technical Service: BULLETIN AROCLORS IN POLYESTER AND EPOXY RESINS MONSANTO CHEMICALS LIMITED Monsanto JtffA HONS 080003 AROCLORS IN POLYESTER AND EPOXY RESINS Tichmcal Slavics Bourn* No. G3/1 Copyright Rutnod PuhUttmg I960 ILM_omnsaJnto MONSANTO CHEMICALS LIMITED MONSANTO HOUSE, 10-18 VICTORIA STREET, LONDON, S.W.l MOMS 080004 AROCLORS IN POLYESTER AND EPOXY RESINS Polyester glass-fibre laminates are becoming The Aroclors may be used to similar effect in more and more widely used Tor the manu facture of industrial and consumer goods, epoxy resins as well as polyesters, being com patible with both types. their chief recommendation being their high strength-to-weight ratio and the ease with which large and complex forms can be fabri cated. 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 C.l. Certain applications of polyester laminates call for the modification of some of their inherent characteristics. Those which most commonly require modification are fireresistance 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. 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, itself a fire retardant. This combination is particularly effective, as The recommended Aroclors are readily mis the two substances are synergistic and to cible with uncured polyesters at the con centrations necessary to impart fire resistance, gether give a degree of fire resistance which is adequate for most possible uses. The though the solid ones dissolve more easily at Aroclor imparts self-extinguishing properties 60C. Once mixed they have no tendency to separate on standing nor to migrate to the to the resin and the antimony trioxide reduces afterglow. The latter also plays the part of an surface of the cured resin. In this respect they inert filler, replacing a proportion of which are superior to certain other chlorinated com ever of the many possible fillers is being used, pounds whose poor compatibility with poly and is usually included even in inherently fire esters could lead to separation after mixing resistant resins which contain chemically and thus to unsightly blooming and greasiness combined chlorine in the polyester molecule. on the surface of the cured resin. The Aroclors The properties of the Aroclors as fire retard also have the advantage of being practically odourless. ants were evaluated in a series of laboratory tests using a general purpose polyester with a acaoclor is Refiltered Trade Mark. 3 HONS 080005 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 cobalt naphthenate was used as an acceler ator. Specimens measuring 9" x }' x |* were cast 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 5537 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 Aroclors 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 FIRE RETARDANCY Per cent of antimony trioxide and Aroclor Aroclor 1260 5 per cent Semi inflammable 7J per cent Semi inflammable Aroclor 4465 Aroclor 5460* Inflammable Self extinguishing 60 secs. Self extinguishing 5 secs. No test 10 per cent Self extinguishing 30 secs. Self extinguishing 5 secs. Self extinguishing 5 secs. 15 per cent Self extinguishing Immediate Self extinguishing Immediate Self extinguishing Immediate 2|% addition of Aroclor 5460 is insufficient to make the polyester self-ostinguithing. verse axis inclined at 45', and placing a bunsen burner with the tip of the flame )' to (' 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 I j oz. woven glasscloth, giving a final thickness of approximately ~iV' 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 HUNS 080006 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 T bridge support. The effect of the Aroclors 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 Aroclors 4465 and 5460 dissolve more readily at 60C. TABLE II MECHANICAL PROPERTIES Resin Formulation Unmodified Polyester Polyester +plasticising polyester Polyester +Aroclor 1260 Polyester +Aroclor 4465 Polyester 4-Aroclor 5460 Elastic Modulus Flexural Strength in bending Impact Strength (P-si) (p.s.i. x 10-*) (ft. lb.) 47,210 21 9 1-73 10% 20% 43,310 39,930 200 15-6 1-64 1-24 10% 20% 45.600 33,880 20-9 16-9 1-33 204 10% 20% 40,740 33,390 21 9 12-9 1 41 248 10% 20% 37,400 35,890 17 0 15-5 1 85 306 properties of polyester resins is shown in Table II. It will be teen that at 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, Aroclor 1260 reduces the flexural strength less than the solid 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 Aroclor 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 MONS 08000 7 resin (Shell Epikote 834) cured with 8% diethylenetriamine, added after the epoxy resin, antimony trioxide and Aroclor were mixed. Specimens were prepared in waxed moulds 9` x i* x )' and the results obtained are shown in Table III. If Arodors are spilled on the skin, it should be washed with soap and water. If acridental burns occur from contact with hot Arodors, the burn should be treated in the same way as an ordinary bum. Aroclor adhering to the burned area should be removed carefully by table in Per cent addition of Aroclor and antimony trioxide Aroclor 1242 J5 per cent 7J per cent Inflammable | No test Aroclor 1260 Aroclor 446S Aroclor 5460 Inflammable Semi inflammable Inflammable Semi inflammable Inflammable Self extinguishing 40 sea. 10 per cent Inflammable Self extinguishing 30 secs. Self extinguishing 20 secs. Self extinguishing 20 secs. 15 per cent Self extinguishing 30 secs. Self extinguishing Immediate Self extinguishing Immediate Self extinguishing Immediate HANDLING AND TOXICITY The Arodors are non-oxidising and non corrosive and they are not hydrolysed by water, alkalis or adds. At ordinary tempera tures they have not presented industrial toxi cological problems, but they should neverthdess 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 on animals indicates that the maximum safe concentration of vapours in workrooms is in the range of O S 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 MONS osoooe 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 are beyond our control, cannot accept responsibilityfor any results of its use. Forme No. P.B.649* El - 6001. Publiihrd by Monunio Chemical* Limited and printed by Tb Chi*.ik Pre,.. London, N il MUNi U80009