EP0275280A4

EP0275280A4 - New thiophosphate ester; also polyurethane foam or prepolymer, containing tris- and bis- (2,4,6-tribromophenoxy) (thio) phosphate.

Info

Publication number: EP0275280A4
Application number: EP19870904666
Authority: EP
Inventors: Richard John Maerschel
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-07-09
Filing date: 1987-07-09
Publication date: 1988-11-16
Also published as: KR880701725A; WO1988000199A1; PT85297A; DK128088A; GR871082B; JPH01500908A; PT85297B; ES2004771A6; EP0275280A1; DK128088D0

Abstract

A polyurethane foam including prepolymer forms containing a fire wetardant mixture of formulae (XI) and (XII), wherein X1 et X2 are oxygen or sulphur and RO is 2,4,6-tribromophenoxy; and a new compound of formula (II), where RO is as previously defined.

Description

NEW THIOPHOSPHATE ESTER; ALSO POLYURETHANE FOAM OR PREPOLYMER, CONTAINING TRIS- AND BIS- (2,4,6-TRIBROMOPHENOXY) (THIO) Titl .PHOSPHATE This invention relates to compounds, processes and products. In a particular aspect this invention relates to broninated phenol esters and to their use in mixtures with prepolymers in order to improve certain characteristics of materials to be synthesized from such prepolymers. An additive of this invention is one compound or a mixture of compounds chosen from a group of brominated phenol esters which ha ve exhibited f ire retardent , surf actant and plasticising properties. In a particular aspect of the present invention there is provided a method of producing fire retardent polyurethane foam wherein the additive is mixed into either an isocyanate prepolymer or a polyol prepolymer of the polyurβthane system, and the modified prepolymer thus formed is in turn mixed with polyol prepolymer or isocyanate prepolymer respectively to produce polyurethane foam. The present invention provides a polyurethane foam containing a fire retarding amount of a mixture of a compound of formula XI set out in the accompanying drawings and a compound of formula XII set out in the accompanying drawings wherein X₁ and S₂ are oxygen or sulphur and RO- is 2,4,6-tribromophenoxy. The present invention also provides a polyurethane foam prepolymer containing a fire retarding amount, with respect to a foam which can be produced, of a mixture of a compound of formula XI set out in the accompanying drawings and a compound of fornula XII set out in the accompanying drawings wherein X₁ and X₂ are oxygen or sulphur and RO- is 2,4,6- tribromophenoxy. Preferably X₁ and X₂ are both oxygen or both sulphur. The foam or prepolymer may additionally include a compound of formula V set out in the accompanying drawings. The prepolymer may be a polyol or isocyanate. The latter is preferred. The prepolymer preferably comprises an organic base. That base is preferably selected from triethylamine, ethylene diamine, and triethano 1 amine. Preferably said compound of formula XI is present in said mixture as from 70 to 80%. Preferably said compound of formula XII is present in said mixture as from 20 to 30%. by weight. Preferably said compound of formula XIII is present in said mixture as from 3 to 8% by weight. Preferably said mixture is present in said prepolymer as from 2½ to 20 preferably 8 to 10% by weight. Preferably said organic base is present in said mixture as from 6 to 8% by weight. The present invention also provides the compound of formula II set out in the accompanying drawings wherein RO- is 2,4,6 -tribromophenoxy and mixtures containing same. Various particularly preferred aspects of this invention will now be described. The present invention provides in a preferred aspect for use of five brominated phenol esters with compound of formulae I-V set out in the accompanying drawings. Compound II, which is the preferred component of the additive does not seem to have been previously described. The use of Compound IV as a fire retardent does not seem to have been described. One previous publication [Benbow & Cullis (1975), Combustion and Flame, v.24, p.217-230] describes the use of Compound III for fire retardation of flexible polyurethane foam. Its use was considered by those authors to be unsatisfactory, primarily because of poor solubility. Use of Compounds I, III, and V for fire retardation of various f lammable materials has been described, but always in applications and combinations distinctly different from those described herein. The widespread sale of urethane prepolymers rather than the finished polymer requires the manufacture of prepolymers with high stability during protracted storage. This imposes strict limitations upon the choice of additives including f ire retardents, primarily because of precipitation and/or neutralization of catalysts during storage. The solubility of purified preparations of Compounds III and V in either type of prepolymer is limited? C ompound I h as much g reater so l ub i l it y , but a t h i gh concentrations it stil l tends to precipitate at temperatures below 20°C. However, incompletely esterified preparations of Compound I, that is those which contain some Compound II , are very much more soluble in each prepol ymer. Similarl y, incompletely esterified preparations of Compound III which contain some Compound IV, are very much more soluble in each prepolymer. Either of these preparations alone or when mixed intimately with Conpound V yields easi ly a true solution which seems to be stable indefinitely. The acidity introduced by either Compound II or I V partly neutralizes amine catalysts in the system resulting in a reduced rate of foaming when polyol and isocyanate are mixed. This ef f ect may be at l east in part reduced by addition of an organic base, severa l of which ha ve been tested successful ly. The rema rkab l e ef f ecti v eness of the dies t ers (Compounds I I and I V ) upon th e so l ub i l i ti es o f their corresponding triesters in isocyanate prepolymer is believed to be due to the reversable combination of isocyanate, residues with monophosphoric acid residues possib ly as suggested as Reaction 1 in the accompanying drawings wherein R ¹ represents an organic functional group. The forward reaction is favoured at low temperatures, but the balance begins to shift significantly towards the b ack rea ction a t temperatures abo v e 40 ° C. Thus , a t t empera tur es pr oduced b y a n exoth ermic react ion when isocyanate and polyol prepolymers are mixed, isocyanate is released to recombine immediately with hydroxyl residues to f orm the urethane l inkages. In its esterif ied f orm, the diester (Compound II or I V) is not onl y ful ly solubil ized but also helps to solubilize the triesters, both phosphate (Compound I or III) and phosphite (Compound V), possibly by pi-bonding. An important e f f ect of the p os sib l e chemica l combination of isocyanate with diester and its association with triester, then their re-release during the foaming reaction, is that the uniform dispersion of the esters is thereby promoted. This overcomes one of the main problems with fire retardents in polyurethane prepolymers, namely uneven dispersion and therefore uneven protection against fire. The f ol lowing example provides a process f or manufacture of the additive. The esters were manufactured in acetone solution by esterif ication of bromol (2,4 ,6- tribromophenol) produced in situ from phenol. EXAMPLE In a first procedure, phenol in acetone was mixed with bromine (1:5.2 phenol/bromine w/w) to form bromol, then this mixture was mixed with phosphorus tribromide (1.05:1 pheno 1 /b romi de w/w) at a temperature betwen 15°C and 30°C, thus forming a solution of tribromol phosphite. The initial phenol concentration in acetone was about 80£ w/w, but this value was not critical and was sometimes varied widely according to the mechanics of mixing. This solution was stored under nitrogen until used. In a second procedure, phenol in acetone was mixed with thiophosphoryl bromide in bromine solution while controlling the temperature to below 30°C. Reactant ratios were 1:5.2:1.05-1.09 (w/w/w phenol/bromine/bromide), this forming a mixed solution of tribromol thiophosphate (70-80% ) with the balance being dibromol thiophosphate. This solution was then blended with the phosphite solution from the first process (20:1 w/w phosphate/phosphite) and an amount of organic base (triethylamine) sufficient to neutralize 85-95} of residual acidity. This mixture was then poured into water whereupon a white flocculated precipitate separated immediately. This precipitate was then dried to reduce water content below 5 i w/w. The final mixture then became Compounds I/II/V (approx. 15/5/1). In an al ternative to the second procedure thiophosphoryl bromide was replaced by phosphoryl bromide. Reactant ratios were then 1:5.2:0.94-0.97. The final mixture then became Compounds III/IV/V (approx. 15/5/1). The preferred additive is Itixture A comprised of Compounds I, II and V (approx. 15/5/1). Compound V may be 3- 12% of the mixture; about 5% is considered optimum. Triethylamine is the preferred neutralizing base despite its high flammability; in practice, it evaporates out of foam within 1-2 days. Idhen added to isocyanate prepolymer as provided herein mixture A confers the maximum benefits yet found from use of any of the Compounds I-V. This is illustrated in the following table which lists a consensus of opinions of those persons who have studied the burning of polyurethane foams subject of this invention. Although these assessments are subjective, the inventor regards them as the best current indicators of performance because of a lack of objective measures for some characteristics important for performance. A similar mixture, flixture B, was formed containing compounds III, IV and V in similar proportions. The three types αf foam subject of the following table have no remarkable physical differences. The choice of composition of additive for type K foam depends on the relative importance of cost, fire retardency, smoke suppression, and some other physical characteristics conferred upon the foam by the additive. Those other characteristics include (1 ) enhanced surfactancy of isocyanate prepolymer which tends to improve cell structure and to reduce or remove the need for silicone, (2) improved adhesion to substrate expected from lowering of silicone addition, (3) reduced need for polymerization catalysts, and (4) anticipated marked suppression of embrittlement and catastrophic failure caused by normal or premature aging. Compounds I and II are superior to Compounds III and IV with respect to smoke production, catalysis and solubility, but are inferior with respect to flammability, stability to aerial oxidation and cost. Compound V is a fire and smoke suppressant in its own right but in this application it is provided mainly as an antioxidant for mixing with either of the other compounds to confer long term stability. The effects of each αf these compounds seemed to be proportional to their content.

Table. Relative performance of three compositions of polyurethane foam.

characteristic type S type G type K

1 ) fire retardency -initial flare 10) 3) 5)

)20 )4 )8

-sustained burning 10) 1 ) 3)

2) smoke from burn -carbonaceous 10) 2) 3)

)20 )3 )6

-irritating 10) 1 ) 3)

3) integrity after burn -cell structure 10) 7) 2) -collapse, cracks )20 )20 )a and delaminating 10) 13) 6)

= = == = = = == =

Total 60 27 22

Type S: Bayer Desmodur 44V20 + Bayertherm 4150 (1:1 v/v) Type G: Lackfa Lamoltan Type K: Bayer Desmodur 44V20: Mixture A (100:16 w/w) + Bayertherm 4150 (1,1 v/v),

Subject to the above, fixture B performed similarly.

The table summarizes observations made after use and combustion of polyurethane foams of various manufacture, all of which contain additives designed to reduce flammability and smoke evo lution. Such f oams are most dif f icult with respect to minimizing the eff ects of combustion. Their g r e a t e s t a t t r i b u t e , n a m e l y h e a t i n s u l a t i o n , i s simul taneously responsib l e for their greatest drawback , namel y f lammability, primari ly because their superlati ve insulating capacity ensures very high point temperatures when subjected to heat. Type S foam is a standard, commonly sol d type of pouring f oam. It contains tris(chl oroethyl ) p ho spha t e , a t yp e of f i re ret a rdent common l y used in po l yurethane f oam. Typ e G i s a p r emium qua l ity f oam containing a dif f erent type of fire retardent with much greater efficacy than that of type S, namely polybromophenyl ether. Type K is the standard type S a l tered on l y by addition of the additive of this invention. Thus, the table represents the direct comparison of commercial ly available standard and premium grade foams with the those provided herein. Values for type S have been arbitrarily set at 10; optimum performance would be zero. Thus, low values are preferred. Both type G and type K behave markedly better than type S. With respect to fire and smoke type K is inferior to type G, but type K is so far superior to type G with respect to structural integrity that its overall performance is significantly better than type G. Type K catches fire and burns at a substantially lower temperature than the other two types. This is by design for good reasons: the low burning temperature (1 ) renders extinguishing of burning foam relatively easy, (2) minimizes the rate of spread of fire and the risk of creation of an explosive fireball, and (3) minimizes the production of carbon monoxide which is the major cause of death in polyurethane and other polymer fires. Type K fires are far less dramatic than those of type S, but it is anticipated that in widespread use the most significant advance of type K is to be its relatively low potential to produce those gaseous products which are proven potent killers. Use of polyhalogenated diaryl ethers such as those used in type G is being voluntarily restricted pending availability of satisfactory alternatives because such compounds are known or suspected precursors of diαxins. Additives αf the type provided herein have no inherent capacity to produce dioxins at the temperatures anticipated in any combustion possibly sustained by type K foam. These inventions provided herein have contributed to significant advances in the applicability of polyurethane f oam to situations currently precluded because of flammability. These inventions also provide materials with surfactant and plasticising properties which may be of major, rather than incidental, interest in various applications. The claims form part of the disclosure of this specification.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:- 1. A polyurethane foam containing a fire retarding amount of a mixture of a compound of formula XI

XI and a compound of formula XII

XII

wherein X₁ and X₂ are oxygen or sulphur and RO-is 2,4,6 - tribromophenoxy. 2. A foam as claimed in claim 1 , wherein X₁ and X₂ are both oxygen or sulphur. 3. A foam as claimed in claim 2, wherein X ₁ and X₂ are both sulphur. 4. A foam as claimed in claim 2, wherein X₁ and X₂ are both oxygen. 5. A foam as claimed in any preceding claim and additionally including a compound of formula V.

V

wherein RO - is 2,4,6-tribromophenoxy. 6. A polyurethane foam prepolymer containing a fire retarding amount, with respect to a foam which can be produced, of a mixture of a compound of formula XI

χι and a compound of formula XII XII RO

wherein X₁ and X₂ are oxygen or sulphur and RO-is 2,4,6 - tribromophenoxy.

7. A prepolymer as claimed in claim 6, wherein X₁ and X₂ are both oxygen or sulphur.

8. A prepolymer as claimed in claim 7, wherein X ₁ and X₂ are both sulphur.

9. A prepolyner as claimed in claim 7, wherein X₁ and X₂ are both oxygen.

10. A prepolyner as claimed in any one αf claims 6-9 and additionally including a compound of formula V.

wherein RO - is 2,4,6-tribromophenoxy.

11. A prepolymer as claimed in any one of claims 6-10, wherein said prepolymer is an isocyanate.

12. A prepolymer as claimed in any one of claims 6-11 , wherein said prepolymer is a polyol.

13. A prepolymer as claimed in any one of claims 6-12, and including an organic base.

14. A prepolymer as claimed in claim 13, wherein the organic bass is selected from triethylamine, ethylene diamine, and trlethanolamine.

15. A prepolymer as claimed in any one of claims 6-14, wherein said compound of formula XI is present in said mixture as from 70 to 80% by weight.

16. A prepolymer as claimed in any one of claims 6-14, wherein said compound of formula XII is present in said mixture as from 20 to 30 % by weight.

17. A prepolymer as claimed in claim 10, wherein said compound of fornula XIII is present in said mixture as from 3 to 8 % by weight.

18. A prepolymer as claimed in any one of claims 6-17, wherein said mixture is present in said prepolymer as from 2£ to 20 preferably 8 to 10% by weight. 19. A prepolymer as claimed in claim 13, wherein said organic base is present in said mixture as from 6 to 8% by weight. 20. A compound of formula II

wherein RO- is 2,4,6- tribromophenoxy. 21. A mixture comprising a compound of formula XI set out in claim 1 and a compound of formula XII set out in claim 1. 22. A mixture as claimed in claim 21 and additional ly containing a compound of formula V set out in claim 5. 23. A f oam , prepol ymer or mixture substantia l l y as hereinbef ore described with ref erence to any one the examples. 24. The articles, things, parts, elements, steps, features, methods, processes, compounds and compositions referred to or indicated in the specification and/or claims of the application individually or collectively, and any and all combinations of any two or more of such.