FLAMEPROOF ACRYLATE

Abstract

Method for manufacturing oxaphosphaphenantrene oxide acrylate monomers by Phospha-Michael addition to acrylates, which comprises reacting oxaphosphaphenantrene oxide with an α,ω-alkyl diol diacrylate in a molar ratio of 1:1.5 to 1:10 in the presence of a base and a polymerisation inhibitor at temperatures from 70 to 120° C. and unreacted α,ω-alkyl diol diacrylate is separated off, monomers obtainable with the method and their use for manufacturing flame retardant thermoplastic (meth)acrylate polymers and method for manufacturing flame retardant thermoplastic (meth)acrylate polymers with the monomers, polymers obtainable in this way and their use for manufacturing transparent films and panels.

Claims

1-18. (canceled)

19. Method for manufacturing oxaphosphaphenantrene oxide acrylate monomers by Phospha-Michael addition to α,ω-alkyl diol diacrylates having 2 to 6 carbon atoms in the alkyl chain, wherein the oxaphosphaphenantrene oxide is reacted with the α,ω-alkyl diol diacrylate in a molar ratio of 1:1.5 to 1:10 in the presence of a base and a polymerisation inhibitor, at temperatures from 70 to 120° C. and in the absence of water, and unreacted diol diacrylate is separated off.

20. Method according to claim 19, wherein the oxaphosphaphenantrene oxide is 9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide.

21. Method according to claim 19, wherein the separation of unreacted diol diacrylate is carried out by vacuum distillation and/or liquid-liquid extraction with a hydrocarbon solvent.

22. Method according to claim 21, wherein the hydrocarbon solvent is n-pentane, n-hexane, n-heptane or a mixture of two or all of them.

23. Method according to claim 19, wherein the Phospha-Michael addition is carried out in toluene, o-xylene, m-xylene, p-xylene or mixtures of two or more thereof as solvent.

24. Method according to claim 19, wherein a sterically hindered tertiary amine is used as base.

25. Method according to claim 19, wherein the base is used in an amount of from 0.15 to 2.0 mol per mol of oxaphospha-phenantrene oxide.

26. Method according to claim 19, wherein the α,ω-alkyl diol diacrylates has 2 to 4 carbon atoms in the alkyl chain.

27. Oxaphosphaphenantrene oxide acrylate monomer obtained by a method according to claim 19.

28. Oxaphosphaphenantrene oxide acrylate monomer according to claim 27, wherein a maximum of 3 mol-% diol diacrylate is present.

29. Method for manufacturing flame retardant, thermoplastic (meth)acrylate polymers by copolymerisation of at least one (meth)acrylate monomer with a phosphorus-containing acrylate monomer, wherein the phosphorus-containing acrylate monomer used is oxaphosphaphenantrene oxide acrylate monomer obtained according to claim 19.

30. The method according to claim 29, wherein the (meth)acrylate monomers are selected from the group consisting of ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butymethacrylate, tert-butymethacrylate and mixtures thereof.

31. Method according to claim 29, wherein additionally copolymerized phosphorus compounds active in the solid phase are polymerized in.

32. Film or panel produced from a flame retardant, thermoplastic (meth)acrylate polymer obtained according to claim 29.

33. Film or panel according to claim 32, wherein the films or panels are transparent.

34. Film according to claim 32, wherein the film is a decorative film comprising a layer containing the (meth)acrylate polymer.

35. Method according to claim 24, wherein the separation of unreacted diol diacrylate is carried out by vacuum distillation or by vacuum distillation and liquid-liquid extraction with a hydrocarbon solvent before and/or after vacuum distillation.

36. Method according to claim 35 wherein the solvent is selected from the group consisting of n-pentane, n-hexane, and n-heptane.

37. Method according to claim 35, wherein the base is used in an amount from 0.9 to 1.1 mol per mol of oxaphosphaphenantrene oxide.

38. Method according to claim 35, wherein the α,ω-alkyl diol diacrylate is ethylene glycol diacrylate or n-butylene glycol diacrylate.

39. Method according to claim 37, wherein the α,ω-alkyl diol diacrylate is ethylene glycol diacrylate or n-butylene glycol diacrylate.

40. Method according to claim 31, wherein the copolymerized phosphorus compounds active in the solid phase selected from ##STR00005## and mixtures of two or more thereof.

41. Film or panel according to claim 32, wherein additionally copolymerized phosphorus compounds active in the solid phase are polymerized in into the flame retardant, thermoplastic (meth)acrylate polymer, and the phosphorus compounds are phosphorus-containing monomers based on alkyl acrylate or hydroxyalkyl (meth)acrylate.

42. Film or panel according to claim 32, wherein additionally copolymerized phosphorus compounds active in the solid phase are polymerized in into the flame retardant, thermoplastic (meth)acrylate polymer, and the phosphorus compounds are selected from ##STR00006## and mixtures of two or more thereof.

Description

EXAMPLES

[0047] The oxaphosphaphenantrene oxide acrylate monomers were prepared in three-neck flasks of various capacities equipped with a stirrer, a Claisen attachment with reflux condenser and a nitrogen supply. The temperature was controlled by an oil bath. Before each reaction, the apparatus was dried by heating in a vacuum and filled with nitrogen. For the reaction, the α,ω-alkyl diol diacrylate was filled into the flask with the solvent (toluene) and the base (triethylamine) in a nitrogen countercurrent. Then 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) was added in portions over several hours. The α,ω-alkyldiol diacrylates used contained methoxyhydroquinone (4-methoxyphenol) as polymerisation inhibitor. In order to keep this active during the reaction, about 20 ml of air was injected at intervals of about 20 minutes. The course of the reaction was followed by taking samples and determining .sup.31P NMR spectra.

Example 1

[0048] 1,4-Butanediol diacrylate was reacted with DOPO in a molar ratio of 3.5:1. For this purpose, 0.6 mol (118.93 g) of 1,4-butanediol diacrylate and 14.05 g of DOPO were added to the 500 ml three-neck flask filled with nitrogen. Then 80 ml toluene and 0.17 mol (approx. 23.56 ml) triethylamine were added. Subsequently, the mixture was heated under stirring and nitrogen atmosphere to just below its boiling point (approx. 96° C., oil bath temperature approx. 107° C.). At intervals of 60 minutes each, 2 further portions of DOPO were added (11.89 g, 10.81 g, total 36.75 g, 0.17 mol). Stirring was continued for another 60 minutes at unchanged internal temperature (approx. 96° C.). Subsequently, an NMR sample was taken, the NMR indicated a complete reaction.

[0049] Toluene and triethylamine were distilled off on a rotary evaporator in vacuo. The residue was subjected to vacuum distillation. At an oil bath temperature of 90° C. and a vacuum of 0.063 mbar, distillation was continued until no more diacrylate condensed in the receiver. Afterwards, the temperature was increased to 125° C. over several steps (vacuum 0.042 mbar). For a further vacuum distillation, the oil bath temperature was slowly increased to 150° C. (vacuum 0.044 mbar). The distillation was stopped because the reaction product started to polymerise.

[0050] The obtained reaction product (49.91 g) of formula:

##STR00002##

[0051] was then copolymerised with methyl methacrylate in an approximate molar ratio of 1:2.7. For this purpose, the reaction product was dissolved in 200 ml toluene and transferred to a three-neck flask. Then approx. 33.3 g of destabilised methyl methacrylate was added and the solution was heated to 97° C. under nitrogen. Since the solution must not contain oxygen due to the 4-methoxyphenol inhibitor during copolymerisation, stirring was carried out for 1.5 hours at constant temperature under nitrogen. Then, with vigorous stirring, 1 ml of a 0.2 M AlBN solution in toluene was added within 2 minutes and the temperature of the oil bath was raised to 117° C. After 10 minutes, another 1 ml of AlBN solution was added. The reaction solution started to boil strongly. After 25 minutes the solution became more viscous and after 30 minutes a voluminous, gel-like substance precipitated from the solution. The copolymerisation was then continued for 1 hour.

[0052] The polymer product obtained was dried for 24 hours at 100° C. in a vacuum drying oven. After drying, the product was slightly rubbery and could not be ground small.

[0053] A thermogravimetric analysis (TGA) was carried out. Hereby, the sample was heated in a nitrogen stream at a heating rate of 10 K/min from 35° C. to 800° C. The analysis showed a decomposition temperature of 318° C. with a mass loss of 5%. The polymer product was used to produce a test specimen in a laboratory press at a pressure of 25 bar within 4 minutes. At a temperature of 190° C., it remained very elastic and rubbery. At a temperature of 225° C. and above, the test specimen became firm and brittle, indicating post-crosslinking, i.e. not yet complete polymerisation.

[0054] The specimen obtained at 225° C. was examined in a UL94 chamber. In the flame test, the pressed specimen showed a strongly slowed burning behaviour compared to pure PMMA, but did not achieve a V1 classification, as it was not self-extinguishing.

Example 2

[0055] The procedure was the same as in example 1, except that the reaction product was shaken out several times with n-hexane after vacuum distillation (oil bath temperature 140° C., vacuum 0.031 mbar). First 3 times with 50 ml n-hexane each, then after addition of 20 ml toluene 4 times with 40 ml n-hexane each and after addition of further 20 ml toluene again 4 times with 40 ml n-hexane each. The solvents were then removed on the rotary evaporator.

[0056] For the copolymerisation, the reaction product (52.82 g) was dissolved in 200 ml toluene and transferred to a three-neck flask. Then approx. 35 g of destabilised methyl methacrylate were added, the solution was heated to 97° C. under nitrogen atmosphere and stirred for 2 hours at constant temperature. Then 1 ml of the 0.2 M AlBN solution was added within 2 minutes under vigorous stirring and the temperature of the oil bath was increased to 117° C. After 14 minutes, 1 ml more of AlBN was added. After 14 minutes, another 1 ml of AlBN was added. The solution started to boil strongly. After 27 minutes the solution became more viscous and after 34 minutes a voluminous gel-like substance precipitated from the solution. The reaction was continued for 1 hour.

[0057] The polymer product obtained was dried for 24 hours at 100° C. in a vacuum drying oven. After drying, the product remained slightly rubbery and could not be ground small with a mortar. The TGA analysis showed a similar decomposition temperature as in example 1, 312° C. with a mass loss of 5%. Test specimens were prepared with the product in a laboratory press at a pressure of 25 bar within 4 minutes. At 190° C. the test specimen remained very elastic and rubbery. At a temperature of 225° C. and above, the test specimen became firm and brittle. The specimen showed good transparency. When tested in the UL94 chamber, the specimen pressed for a short time at 225° C. went out directly after the first flame exposure of 10 seconds and after the second it burned for only about 4 seconds, i.e. it achieved a classification V0.

Comparative Example VB1

[0058] The procedure was analogous to example 1, except that butylene glycol dimethacrylate and DOPO were reacted in a molar ratio of 1:1. 0.2 mol (45.25 g) butylene glycol dimethacrylate and 9.24 g DOPO were added to the 500 ml three-neck flask filled with nitrogen. Then 100 ml toluene and 0.12 mol (approx. 16.6 ml) triethylamine were added. Subsequently, the mixture was heated under stirring and nitrogen atmosphere to just below its boiling point (approx. 96° C., oil bath temperature approx. 107° C.). At intervals of 30 minutes, 6 further portions of DOPO were added (8.54 g, 6.99 g, 6.50 g, 4.9 g, 4.00 g, 3.00 g, a total of 43.24 g, 0.2 mol). Stirring was continued for a further 30 minutes at unchanged internal temperature (approx. 96° C.). Subsequently, an NMR sample was taken. The reaction was not yet complete and stirring was continued at the same conditions (approx. 96° C. internal temperature) for 3 hours and then an NMR sample was taken. As the reaction was still not complete, another 5 ml of triethylamine was added and stirring was continued for 1 hour at unchanged conditions. Another NMR sample was taken. DOPO was now completely reacted.

[0059] For copolymerisation, the oxaphosphaphenantrene oxide acrylate monomer was first stirred at an internal temperature of about 97° C. for 30 minutes. Then 0.4 mol (40.07 g) of destabilised methyl methacrylate was added in a nitrogen countercurrent. Since the solution must not contain oxygen during copolymerisation due to the 4-methoxyphenol, stirring was continued for another 1.5 hours at constant temperature. Then 2 ml of the 0.2-molar AlBN solution in toluene was added within 2 minutes with vigorous stirring. The solution began to boil strongly and a voluminous gel-like substance precipitated from the solution after a few minutes of reaction time. The temperature of the oil bath was raised to 117° C. and the reaction continued for 1 hour.

[0060] The polymer product obtained was dried for 24 hours at 100° C. in a vacuum drying oven and then ground into small pieces. A white powder was obtained. A thermogravimetric analysis (TGA) was then carried out. The analysis showed a decomposition temperature of 255° C. with a mass loss of 5%.

[0061] An attempt was made to produce test specimens with the powder in a laboratory press at temperatures of up to 260° C. and pressures of up to 25 bar. However, the powder could not be melted and no test specimen could be produced. A solubility test showed that the polymer obtained could not be dissolved in organic solvents. This shows that no thermoplastic was obtained.

Comparative Example VB2

[0062] Compared to comparative example VB1, the amount of DOPO was slightly increased (45.40 g, 0.21 mol) to reduce the number of unreacted dimethacrylates. In addition, the amount of base and the time between DOPO additions was increased to 60 minutes to ensure a faster conversion of the DOPO. To the 500 ml three-neck flask filled with nitrogen, 0.2 mol (45.25 g) of butylene glycol dimethacrylate and 9.5 g of DOPO were added. Then 100 ml toluene and 0.21 mol (approx. 29.11 ml) triethylamine were added. Subsequently, the mixture was heated to just below its boiling point (approx. 96° C., oil bath temperature approx. 107° C.) under stirring and in a nitrogen atmosphere. At intervals of 60 minutes each, 6 further portions of DOPO were added (8.5 g, 7.5 g, 6.5 g, 5.5 g, 4.5 g, 3.4 g, a total of 45.40 g, 0.21 mol). Stirring was continued for 60 min at unchanged internal temperature (approx. 96° C.). Subsequently, an NMR sample was taken. The reaction was not yet complete. Therefore, stirring was continued for another 2.5 hours at unchanged conditions (approx. 96° C. internal temperature) and another NMR spectrum was recorded. After 3 hours, DOPO was completely consumed according to .sup.31P NMR.

[0063] The reaction product was copolymerised with methyl methacrylate in a molar ratio of 1:2 after removal of 4-methoxyphenol as in Comparative Example 1. The polymer product obtained was dried for 24 hours at 100° C. in a vacuum drying oven and then ground into small pieces using a ceramic mortar and pestle. The TGA analysis showed a decomposition temperature of 275° C. with a mass loss of 5%. However, as in comparative example VB1, it was not possible to produce a test specimen with the product.

Comparative Example VB3

[0064] Analogous to example 1, ethylene glycol dimethacrylate was reacted with DOPO in a molar ratio of 1.76:1. 0.25 mol (49.60 g) of ethylene glycol dimethacrylate and 8.65 g of DOPO were added to the 500 ml three-neck flask filled with nitrogen. Then 70 ml toluene and 0.10 mol (approx. 13.7 ml) triethylamine were added. Subsequently, the mixture was heated under stirring and nitrogen atmosphere to just below its boiling point (approx. 96° C., oil bath temperature approx. 107° C.). At intervals of 45 minutes each, 4 further portions of DOPO were added (7.57 g, 6.49 g, 5.41 g, 4.32 g, a total of 32.44 g, 0.15 mol). Stirring was continued for a further 60 minutes at unchanged internal temperature (ca. 96° C.). A .sup.31P NMR sample revealed traces of unreacted DOPO 1 hour after the last DOPO addition. The reaction mixture was stored overnight and a further NMR sample showed a now essentially complete conversion of the DOPO.

[0065] To separate the excess ethylene glycol dimethacrylate, 31 ml n hexane was added. To achieve a better phase separation, the flask was stored in the freezer for 12 hours. Both phases were separated in the separating funnel. Afterwards, 100 ml of n-hexane were added again and the phases were separated again in the separating funnel.

[0066] The reaction product was then copolymerised with 36 g methyl methacrylate (molar ratio 1:2). For this purpose, the reaction product as well as 200 ml toluene and 36 g destabilised methyl methacrylate were placed in a three-neck flask and the solution was heated to 97° C. under a nitrogen atmosphere. Since the solution must not contain oxygen, it was stirred for 1.5 hours at a constant temperature. Then, while stirring vigorously, 3 ml of the 0.2 M AlBN solution was added within 5 minutes. The solution began to boil strongly. After 10 minutes, the temperature of the oil bath was increased to 117° C. After 10 minutes, a voluminous gel-like substance precipitated from the solution and the reaction was continued for 1 hour.

[0067] The polymer product obtained was dried for 24 hours at 150° C. in a vacuum drying oven and then ground into small pieces. A yellowish-white powder was obtained. The drying temperature may have been too high and the product had partially decomposed. The TGA analysis showed a decomposition temperature of 258° C. with a mass loss of 5%. A test specimen was made with the powder in the laboratory press. This was yellowish, slightly transparent and very brittle, it could not be removed from the mould without breaking. The degree of cross-linking was still too high.

[0068] The pieces obtained were examined in a UL94 chamber. In the flame test, the pressed test specimen showed a strongly slowed burning behaviour compared to pure PMMA, but not the desired self-extinguishing after flame exposure.

Comparative Example VB4

[0069] Compared to example 3, the excess of ethylene glycol dimethacrylate was increased to 2.5:1. 0.75 mol (148.6 g) ethylene glycol dimethacrylate and 26 g DOPO were added to the 1 l three-neck flask filled with nitrogen. Then 140 ml toluene and 0.5 mol (approx. 68 ml) triethylamine were added. Subsequently, the mixture was heated under stirring and nitrogen atmosphere to just below its boiling to point (approx. 96° C., oil bath temperature approx. 107° C.). At intervals of 60 minutes, 2 further portions of DOPO were added (21.6 g, 17.3 g, a total of 64.88 g, 0.3 mol). Stirring was continued for 60 minutes at unchanged internal temperature (approx. 96° C.). An NMR sample was then taken, which indicated complete conversion of DOPO.

[0070] Triethylamine and toluene were distilled off on the rotary evaporator in vacuo. Next, it was shaken out 3 times with 100 ml n-hexane. Vacuum distillation was then carried out until no dimethacrylate condensed in the receiver at an oil bath temperature of 85° C., a head temperature of 50° C. and a vacuum of 0.05 mbar. The vacuum distillation was repeated twice more, each time at a higher temperature, 95 and 105° C. oil bath temperature. However, the product solution partially polymerised spontaneously. The .sup.1H NMR showed that dimethacrylates were still present in the reaction product.

[0071] The reaction product (119 g) was dissolved in 450 ml toluene and transferred to the three-neck flask. Then approx. 36 g of destabilised methyl methacrylate were added and the solution was heated to 97° C. under nitrogen atmosphere. It was stirred for 1.5 hours at constant temperature. Then, while stirring vigorously, 2 ml of the 0.2 M AlBN solution was added within 4 minutes and the temperature of the oil bath was raised to 117° C. After 10 minutes, another 1 ml of AlBN was added.

[0072] The solution started to boil strongly. After 15 minutes, the solution became more viscous. White flakes were visible. After 17 minutes, a voluminous gel-like substance precipitated from the solution and the reaction was continued for 1 hour.

[0073] The polymer product obtained was dried for 24 hours at 100° C. in a vacuum drying oven and then ground into small pieces using a ceramic mortar and pestle. The TGA analysis showed a decomposition temperature of 241° C. with a mass loss of 5%. A test specimen was made with the powder in the laboratory press. This was more transparent than in the comparative examples VB1, VB2 and VB3, but still very brittle. It could not be removed from the mould without breaking.

[0074] The pieces obtained were tested in a UL94 chamber, the pressed specimen did not show improved fire behaviour compared to VB3.

Comparative Example VB5

[0075] The excess ethylene glycol dimethacrylate was further increased to a molar ratio of 3.5:1. 0.7 mol (138.8 g) of ethylene glycol dimethacrylate and 17.3 g of DOPO were added to the 1 l three-neck flask filled with nitrogen. Then 100 ml toluene and 0.4 mol (approx. 55.5 ml) triethylamine were added. Subsequently, the mixture was heated under stirring and nitrogen atmosphere to just below its boiling point (approx. 96° C., oil bath temperature approx. 107° C.). At intervals of 60 minutes each, 2 further portions of DOPO were added (15.3 g, 10.8 g, total 43.24 g, 0.2 mol). Stirring was continued for 60 minutes at unchanged internal temperature (approx. 96° C.). An NMR sample was then taken, which showed complete conversion of DOPO.

[0076] Triethylamine and toluene were distilled off on a rotary evaporator in vacuum and the residue was subjected to vacuum distillation (oil bath temperature 80° C., vacuum 0.04 mbar). During the vacuum distillation, a spontaneous polymerisation of the product occurred when the oil bath temperature was increased to 110° C., it could no longer be stirred.

[0077] The examples and comparative examples show that neither with approximately equimolar amounts of reactant nor with an excess of oxaphosphaphenantrene oxide a useful acrylate comonomer is obtained. Only if a sufficient excess of diacrylate is used as provided according to the invention, can a diacrylate reacted only once with oxaphosphaphenantrene oxide be obtained. The excess of α,ω-alkyl diol diacrylate could be separated sufficiently well. In the case of the α,ω-alkyl diol dimethacrylates, however, this is not successful. In particular, comparative examples 1 and 2 show that no thermoplastic (meth)acrylate polymers are obtained with a direct copolymerisation of oxaphosphaphenantrene oxide acrylate monomers with further (meth)acrylate monomers as suggested in WO 2019/141572 A1 and JP 2016-060865 A. In addition to the selection of α,ω-alkyl diol diacrylate and an excess thereof, the separation of the unreacted α,ω-alkyl diol diacrylate as provided according to the invention is also necessary to obtain thermoplastic (meth)acrylate polymers. Table 1 below provides an overview of the examples and comparative examples.

TABLE-US-00001 TABLE 1 Molar ratio TGA: decom- (comparative) diacry- Molar ratio position tem- fire thermo- example No. Diacrylate late:DOPO Workup MMA:Monomer perature behaviour plast? 1 1,4 Butanediol- 3.5:1 a) vacuum distillation 125° C./0.042 mbar 2.7:1.sup.  318° C. better than yes diacrylate b) vacuum distillation 150° C./0.044 mbar PMMA 2 1,4 Butanediol- 3.5:1 a) vacuum distillation 140° C./0.031 mbar 2.7:1.sup.  312° C. V0 yes diacrylate b) extraction: 3x 50 ml hexane, c) +20 ml toluene 4x 40 ml hexane d) +20 ml toluene 4x 40 ml hexane VB1 1,4 Butanediol- .sup. 1:1 direct copolymerization 2:1 255° C. no test no dimethacrylate specimen VB2 1,4 Butanediol-   1:1.05 direct copolymerization 2:1 275° C. no test no dimethacrylate specimen VB3 1,2-Ethanediol- 1.76:1  a) +70 ml toluene 31 ml hexane 2:1 258° C. better than brittle dimethacrylate b) 100 ml hexane PMMA VB4 1,2-Ethanediol- 2.5:1 a) +140 ml toluene 3x 100 ml hexane 2:1 241° C. better than brittle dimethacrylate b) vacuum distillation 85° C./0.05 mbar PMMA c) vacuum distillation 95° C./0.05 mbar d) vacuum distillation 105° C./0.05 mbar VB5 1,2-Ethanediol- 3.5:1 polymerized during addition ./. ./. ./. ./. dimethacrylate PMMA 219° C. ja

Example 6

[0078] Analogous to Example 2, a DOPO acrylate monomer was prepared from DOPO and 1,4-butanediol diacrylate, but with a molar ratio of butanediol diacrylate to DOPO of 7:1. To this end, 1.25 mol (297.3 g) of distilled butanediol diacrylate, 13.6 g of DOPO and 30 mg of 4-methoxyphenol were added to a 250 ml three-neck flask filled with nitrogen. Then 35 ml triethylamine was added by syringe through the septum and the mixture was heated up to 85-87° C. (oil bath temperature) under stirring and nitrogen atmosphere in the course of 20 min. Then a further 9.0 g of DOPO was added. After another 20 min, a third portion of DOPO was added (9.0 g). Three further portions (7.5 g each) were added at intervals of 20 min each. The reaction mixture was stirred for another 30 min at unchanged temperature. Then the heating was turned off. During the Phospha-Michael addition, 20 ml of air were injected at intervals of approx. 15 min. each to keep the inhibitor active.

[0079] For the isolation of the DOPO monomer, the obtained product solution was divided into two parts. The product isolation was done for both parts by first distilling off the triethylamine, applying a partial vacuum at the beginning and heating the oil bath to max. 50° C. Then the main part of the excess butanediol diacrylate was distilled (ca. 0.02 mbar), heating up to 105° C. to avoid spontaneous polymerisation. To the distillation residue was added 250 ml of cyclohexane, and then heated rapidly to boiling. After about 5 min of intensive stirring under reflux, the oil bath was removed. The contents of the flask were then cooled to about 40° C. in a water bath, then cooled in a refrigerator, whereupon the supernatant, slightly milky turbid phase was decanted. A further nine extractions were carried out in a similar way (cyclohexane was recovered in each case). Now the extraction residue was heated to 105° C. within 45 min. and the pressure was lowered to approx. 0.02 mbar. These conditions were maintained for approx. 20 min. After cooling, the DOPO monomer was obtained as a slightly turbid, viscous and colourless oil. The .sup.1H NMR spectrum recorded in deutero-chloroform of the DOPO monomer thus obtained showed good purity. In particular, it showed the successful separation of the excess 1,4-butanediol diacrylate (<1% by weight diacrylate; the amount of doubly DOPO-functionalised product was about 6% by weight).

[0080] 52.82 g of the DOPO monomer was dissolved in 200 ml toluene for copolymerisation with methyl methacrylate and transferred to a three-neck flask. Then about 35 g of destabilised methyl methacrylate was added, the solution was heated to 97° C. under nitrogen atmosphere and stirred for 2 hours at constant temperature. Then, with vigorous stirring, 1 ml of a 0.2 M AlBN solution was added within 2 minutes and the temperature of the oil bath was increased to 117° C. After 14 minutes, another 1 ml of AlBN was added. The solution started to boil strongly. After 27 minutes the solution became more viscous and after 34 minutes a voluminous gel-like substance precipitated from the solution. The reaction was continued for 1 hour.

[0081] The polymer product obtained was dried for 24 hours at 100° C. in a vacuum drying oven. After drying, the product remained slightly rubbery and could not be ground small with a mortar. The TGA analysis showed a similar decomposition temperature as in examples 1 and 2, 312° C. with a mass loss of 5%. Test specimens were made with the product in a laboratory press at a pressure of 25 bar within 4 minutes. At 190° C. the test specimen remained very elastic and rubbery. At a temperature of 225° C. and above, the test specimen became firm and brittle. The specimen showed good transparency. When tested in the UL94 chamber, the specimen pressed for a short time at 225° C. went out directly after the first flame exposure of 10 seconds and after the second flame exposure it burned for only about 4 seconds, i.e. it achieved a classification V0. The results of the fire behaviour test are listed in table 2.

Example 7

[0082] The DOPO monomer of Example 6 was reacted in various amounts with methyl methacrylate and DDPO-HEMA,

##STR00003##

both with and without the addition of another monomer, such as methyl acrylate or n-butyl methacrylate, to form a methyl acrylate polymer. A suspension polymerisation was carried out in water with 1-decylthiol as regulator and dibenzoyl peroxide (BPO) as initiator. The liquid monomers were destabilised before polymerisation; DDPO-HEMA (A) was recrystallised from tert-butyl methyl ether (melting point 50.5° C.). The syntheses of the methacrylate polymers were carried out in a reaction apparatus consisting of a 250 ml three-neck flask, magnetic stirrer, heating bath, a dropping funnel and a reflux condenser on which a three-way tap with bubble counter was mounted. Both the dropping funnel and the three-way tap on the reflux condenser were connected with a Schlenk line.

[0083] From the methacrylate polymers obtained, compact transparent test rods as well as transparent films of different thickness were produced with an oil-hydraulic laboratory press of the type HB 20 300 (Schmidt Maschinentechnik; Bretten-Bauerbach, Germany). The test bars had the following dimensions: 70 mm×10 mm×0.8 mm. Temperatures of 210-245° C. were applied during pressing (depending on the melting behaviour of the methacrylate polymers). The quantities and results of the fire behaviour test are listed in table 2.

Example 7a

[0084] For copolymerisation, a mixture of 1.35 g DDPO-HEMA (A), 1.35 g DOPO monomer, 7.3 g methyl methacrylate, 34 mg 1-decyl mercaptan and 67 mg water-bearing BPO was added to the dropping funnel. Vacuum was then applied twice briefly and nitrogen was allowed to flow in again each time. To remove the oxygen, the mixture of water and 1.3 ml of a 2% solution of the suspension stabiliser Kuraray Poval 25-88 (partially hydrolysed polyvinyl alcohol) was stirred for 30 min at 85-90° C., with a moderate flow of nitrogen through the three-way stopcock into the apparatus and to the bubble counter. After the aqueous solution had cooled to about 62° C., the solution from the dropping funnel was added. Then the contents of the flask were heated to 73° C. within 20 min. with stirring. A milky emulsion was formed. The connection to the bubble counter was shut off 10 min after the monomer addition. Now the temperature was increased by 1° C. at intervals of approx. 15 min. each until a temperature of 82° C. was reached. Stirring was continued vigorously for four hours. After that, a solution of 65 mg BPO and 500 mg methyl methacrylate was added and the temperature was increased to 87° C. At this temperature, the reaction mixture was stirred for 12 h under a nitrogen atmosphere. Spheres were formed, as well as some compact material. The supernatant aqueous solution was decanted, then water was added and sucked off through a paper filter. The methacrylate polymer was dried for 5 h at 80° C. and for one hour at 100° C. in vacuum (approx. 0.02 mbar). The .sup.31P NMR spectrum of this polymer recorded in deutero-chloro form contained only the signals of the DOPO unit (approx. 36 ppm) and the DDPO unit (−8.2 ppm). The ratio of the signal integrals was nearly the expected value of 1.00:1.50. Approximately 9 g of the methacrylate polymer was obtained.

Example 7b

[0085] For the copolymerisation, 65 ml of deionised water and 1.3 ml of a 2% by weight aqueous solution of Kuraray Poval 25-88 KL (suspension stabiliser, partially hydrolysed polyvinyl alcohol) were added to the three-necked flask. A solution consisting of 1.7 g of DDPO-HEMA (A), 1.5 g of the DOPO monomer, 6.0 g of methyl methacrylate, 0.8 g of methyl acrylate, 45 mg of 1-decyl thiol and 80 mg of water-bearing BPO (60 mg of pure BPO) was added to the dropping funnel. The dropping funnel was partially evacuated twice and refilled with nitrogen to remove the atmospheric oxygen from the reagent mixture. The reaction flask containing the aqueous solution was also partially evacuated twice and each time filled again with nitrogen. Then the contents of the flask were heated to 95° C. with stirring, and a moderate flow of nitrogen was passed through the three-way stopcock into the apparatus and to the bubble counter. After 30 min. of stirring, the temperature was lowered to approx. 65° C. The contents of the dropping funnel were added to the aqueous solution thus freed from oxygen. Then the contents of the flask were heated to 73° C. within approx. 20 min. in a weak nitrogen stream with stirring. Over the course of two hours, the temperature was increased to 83° C. A moderate nitrogen flow continued to be directed to the bubble counter. After another hour, a solution of approximately 35 mg of water-bearing BPO in 0.37 g of methyl methacrylate was added through the dropping funnel. Subsequently, the temperature of the heating bath was increased to 87° C. After a further 30 min, the bubble counter was disconnected. Stirring at 87° C. was continued for 12 h. Then the aqueous phase was decanted. A methacrylate polymer was obtained as compact pieces and film-like material. This polymer was soluble in chloroform and dimethyl sulphoxide. To remove monomer residues as well as water, the polymer was heated in vacuum (approx. 0.02 mbar) first to 90° C. for 3 h and then to 105° C. for 45 min. In the .sup.31P NMR spectrum of the methacrylate polymer thus obtained, the signals of the DOPO unit and the DDPO unit were present at about 36 ppm and about −8 ppm, respectively, and the intergral ratio was close to the expected value.

Example 7c

[0086] For copolymerisation, 55 ml of deionised water and 1.5 ml of a 2% by weight aqueous solution of Kuraray Poval 25-88 KL (suspension stabiliser, partially hydrolysed polyvinyl alcohol) were added to the three-neck flask. Then a solution of 1.9 g of DDPO-HEMA, 1.7 g of the DOPO monomer, 5.4 g of methyl methacrylate, 1.0 g of methyl acrylate, 25 mg of 1-decylthiol and 90 mg of water-bearing BPO (corresponding to 67 mg of pure BPO) was added to the dropping funnel. The dropping funnel was partially evacuated twice and refilled with nitrogen to remove the atmospheric oxygen from the reagent mixture. The reaction flask containing the aqueous solution was also partially evacuated twice and each time filled again with nitrogen. Then the contents of the flask were heated to 95° C. while stirring, and a moderate flow of nitrogen was passed through the three-way stopcock into the apparatus and to the bubble counter. After 30 min of stirring, the temperature was lowered to about 65° C. The contents of the dropping funnel were added to the aqueous solution thus freed from oxygen. Then the temperature of the oil bath was raised to 75° C. while vigorously stirring the reaction mixture, producing a milky-white suspension. Stirring was continued for 3.5 h, gradually increasing the temperature of the heating bath to 84° C. Then a solution of 35 mg BPO, 0.33 g methyl methacrylate and 0.07 g methyl acrylate was added in nitrogen countercurrent through the dropping funnel. Subsequently, the temperature of the heating bath was increased to 87° C. After another hour, the connection to the bubble counter was interrupted and the cooling water was turned off. The reaction mixture was stirred for another 12 h under these conditions. Then the aqueous solution was decanted from the methacrylate polymer, which had formed partly as spheres and partly as a compact or film-like material. The methacrylate polymer was washed three times with water and dried on filter paper. The .sup.1H NMR spectrum of the polymer recorded in deutero-chloroform showed that unreacted monomers were present. Therefore, the polymer was heated in a fine vacuum (approx. 0.02 mbar) first to approx. 87° C. (4 h) and then to 93° C. (1 h). Afterwards, the .sup.1H NMR spectrum of the methacrylate polymer showed the almost complete disappearance of the acrylate/methacrylate groups. In the .sup.31P NMR spectrum, the signals of the DOPO unit and the DDPO unit were present at about 36 ppm and about −8 ppm, respectively, with an intergral ratio close to the expected value of 1.00:1.66.

Example 7d

[0087] For copolymerisation, 60 ml of deionised water and 2.0 ml of a 2% by weight aqueous solution of Kuraray Poval 25-88 KL (suspension stabiliser, partially hydrolysed polyvinyl alcohol) were added to the three-neck flask. Then a solution of 2.22 g of DDPO-HEMA, 1.8 g of the DOPO monomer, 7.08 g of methyl methacrylate, 0.9 g of butyl methacrylate, 35 mg of 1-decylthiol and 108 mg of water-bearing BPO (corresponding to 81 mg of pure BPO) was added to the dropping funnel. The dropping funnel was partially evacuated twice and refilled with nitrogen to remove the atmospheric oxygen from the reagent mixture. The reaction flask containing the aqueous solution was also partially evacuated twice and each time filled again with nitrogen. Then the contents of the flask were heated to 95° C. with stirring, and a moderate flow of nitrogen was passed through the three-way stopcock into the apparatus and to the bubble counter. After 60 min. of stirring, the temperature was lowered to about 63° C. The contents of the dropping funnel were added to the aqueous solution thus freed from oxygen. The temperature of the heating bath was then increased to 75° C. This temperature was maintained for 20 min; then the set temperature was increased to 77° C. and 30 min later to 80° C. This temperature was maintained for 50 min. Then the set temperature was increased to 85° C. A milky emulsion had formed. Stirring was very intensive for three hours and a stream of nitrogen continued to be fed into the apparatus and to the bubble counter. The formation of polymer could be seen. Afterwards, the connection to the bubble counter was interrupted, the cooling water was turned off and stirring was continued for another 12 h at 85° C. under slight nitrogen counterpressure. Then the aqueous solution was decanted from the methacrylate polymer, which had formed partly as small spheres and partly as compact material. The methacrylate polymer was washed three times with water and dried on filter paper. The NMR spectra of the polymer obtained in this way showed about 95% conversion of the acrylate and methacrylate groups. The polymer was dried in vacuum (0.02 mbar) for three hours at 87-95° C. to remove water residues. The .sup.1H NMR spectrum of the methacrylate polymer showed the almost complete disappearance of the acrylate/methacrylate groups. In the .sup.31P NMR spectrum, the signals of the DOPO unit and the DDPO unit were present at about 36 ppm and about −8 ppm, respectively, with an intergral ratio close to the expected value of 1.00:2.33. The methacrylate polymer thus obtained was readily soluble in organic solvents such as chloroform. It softened at about 160° C. and melted at about 200° C.

Example 8

[0088] The DOPO monomer of example 6 was reacted in various amounts with methyl methacrylate and DEPO-HEMA,

##STR00004##

both with and without the addition of another monomer, such as methyl acrylate or n-butyl methacrylate, to form a methyl acrylate polymer. A suspension polymerisation was carried out in water with 1-decylthiol as regulator and dibenzoyl peroxide (BPO) as initiator. The monomers were destabilised before polymerisation. The syntheses of the methacrylate polymers were carried out in a reaction apparatus consisting of a 250 ml three-neck flask, magnetic stirrer, heating bath, a dropping funnel and a reflux condenser on which a three-way tap with bubble counter was mounted. Both the dropping funnel and the three-way valve on the reflux condenser were connected with a Schlenk line.

[0089] Compact test bars and films of different thicknesses were produced from the methacrylate polymers obtained using an oil-hydraulic laboratory press of the type HB 20 300 (Schmidt Maschinentechnik; Bretten-Bauerbach, Germany). The test bars had the following dimensions: 70 mm×10 mm×0.8 mm. Temperatures of 220-245° C. were applied during pressing (depending on the melting behaviour of the methacrylate polymers). The quantities and results of the fire behaviour test are listed in table 2.

Example 8a

[0090] The polymerisation was carried out analogously to example 7c. Most of the methacrylate polymer was obtained in compact pieces, which were detached from the glass wall and washed with water. The .sup.1H NMR spectrum of this polymer, recorded in deutero-chloroform, showed that unreacted monomers were present. Therefore, the polymer was heated in a fine vacuum (approx. 0.02 mbar) first to approx. 87° C. (4 h) and then to 93° C. (1 h). Afterwards, the .sup.1H NMR spectrum of the methacrylate polymer showed the almost complete disappearance of the acrylate/methacrylate groups. In the .sup.31P NMR spectrum, the signals of the DOPO moiety and the diethyl phosphate moiety were present at about 36 ppm and 1.3 ppm, respectively, with an intergral ratio close to the expected value of 1.00:1.74.

Example 8b

[0091] The polymerisation was carried out analogously to example 7c. The methacrylate polymer was obtained as relatively large polymer beads (granules) which were washed twice with water. The polymer was dried for 5 h in vacuum (0.02 mbar) at 87-105° C. and then analysed by NMR spectroscopy. The .sup.1H NMR spectrum of the methacrylate polymer showed the complete disappearance of the acrylate/methacrylate groups. The .sup.31P NMR spectrum was also as expected: the signals of the DOPO unit and the diethyl phosphate unit were present at about 36 ppm and −1.3 ppm, respectively, with an intergral ratio close to the expected value of 1.00:1.74.

Comparative Example VB8a

[0092] The polymerisation was carried out analogously to Example 7c. The methacrylate polymer was obtained in compact pieces, which were detached from the glass wall, and washed with water. The .sup.1H NMR spectrum of this polymer recorded in deutero-chloroform showed a relatively high proportion of unreacted monomers. The polymer was heated in a fine vacuum (approx. 0.02 mbar) first to approx. 87° C. (3 h) and then to 97° C. (1 h). Afterwards, the .sup.1H NMR spectrum of the methacrylate polymer showed the almost complete disappearance of the acrylate/methacrylate groups. The methacrylate polymer thus obtained had a phosphorus content of about 4% by weight.

TABLE-US-00002 TABLE 2 (compar- ative) DOPO- mass example Monomer A or B MMA MA BMA fraction No. [mol-%] [mol-%] [mol-%] [mol-%] [mol-%] fire behaviour P 6 26.7 — 73.3 — — V0, specimen 2.2% self-extinguishing 7a 4.0 A 6.0 90.0 — — Burns slowly, not 2.5% self-extinguishing 7b 4.6 A 7.7 75.9 11.8 — better than 6a .sup. 3% 7c 5.4 A 8.9 70.5 15.2 — Film & specimen 3.4% self-extinguishing 7d 3.9 A 11.8 77.4 —  6.9 Specimen burns .sup. 3% slowly, film (approx. 0.2 mm) self-extinguishing 8a 5.3 B 9.3 70.2 15.1 — with prolonged 3.5% second flaming, specimen continues to burn 8b 5.7 B 10.0 72.6 — 11.8 Slightly worse 3.5% than 7a VB8a — B 11.4 74.4 14.2 — Specimen ignites .sup. 4% after prolonged flame exposure, continues to burn slowly; 0.4 mm film self- extinguishing Worse than 7a, slightly worse than 7b

[0093] These examples show that the combination of the oxa-phosphaphenantrene oxide acrylate monomer according to the invention with a copolymerised, solid-phase active phosphorus compound offers an optimal flame retardant effect. The solid-phase active phosphorus compound alone is not sufficiently effective. This is shown by the methacrylate polymer of Comparative Example 8a, whose flame retardant effect was worse than that of Examples 7c, 8a and 8b, despite a higher phosphorus content.