POLYPHOSPHAZENE AND MOLDING COMPOUND CONTAINING THE POLYPHOSPHAZENE

Abstract

The invention relates to a polyphosphazene produced by a method comprising the steps a) and b): a) converting an in particular cyclical phosphazene by means of phenol in the presence of a base; b) further converting by means of a special aromatic diphenol in the presence of a base, wherein the molar ratio of phenol used to cyclical phosphazene used is in the range from 3.5:1 to 1:1. The invention also relates to a method for producing the polyphosphazene and to a molding compound containing the polyphosphazene and a thermoplastic polymer.

Claims

1. A polyphosphazene produced by a process comprising the steps a) and b): a) reaction of a cyclic phosphazene of formula (1) ##STR00012## wherein k is a natural number between 1 and 10 with phenol in the presence of a base b) further reaction with an aromatic diphenol of formula (2) ##STR00013## wherein R.sup.1 and R.sup.2 independently of one another represent H or C.sub.1- to C.sub.8-alkyl and X represents a single bond, C.sub.1- to C.sub.5-alkylene, C.sub.2- to C.sub.5-alkylidene, C.sub.5- to C.sub.6-cycloalkylidene, —O—, —SO—, —CO—, —S—, or —SO.sub.2— in the presence of a base wherein the molar ratio of employed phenol to the employed cyclic phosphazene of formula (1) is in the range from 3.5:1 to 1:1.

2. The polyphosphazene as claimed in claim 1, characterized in that the molar ratio of employed phenol to the employed aromatic diphenol of formula (2) is in the range from 3:1 to 1:1.

3. The polyphosphazene as claimed in claim 1, characterized in that the phosphazene has a swelling factor $Q=\frac{a-b}{b}$ of 1 to 15 after storage for 3 days in chloroform, wherein a is the mass of the swollen polyphosphazene and b is the mass of the unswollen polyphosphazene.

4. The polyphosphazene as claimed claim 1, characterized in that the base employed in steps a) and b) is preferably selected from 1,8-diazabicyclo[5.4.0]undec-7-ene, N,N-diethylethanamine, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene.

5. The polyphosphazene as claimed in claim 1, characterized in that the polyphosphazene has a glass transition temperature determined by differential scanning calorimetry of 70° C. to 150° C.

6. The polyphosphazene as claimed in claim 1, characterized in that the employed cyclic phosphazene of formula (1) is a compound having a trimer proportion (k=1) of 60 to 100 mol % based on the cyclic phosphazene of formula (1).

7. The polyphosphazene as claimed in claim 1, characterized in that 2,2-bis(4-hydroxyphenyl)propane is used as the aromatic diphenol according to formula (2).

8. A molding compound containing a thermoplastic polymer and a polyphosphazene as claimed in claim 1.

9. The molding compound as claimed in claim 8, characterized in that the thermoplastic polymer is a polyester, polycarbonate, vinyl (co)polymer, polyamide or mixtures thereof.

10. The molding compound as claimed in claim 8, characterized in that the polyphosphazene is present in a proportion of 2% to 20% by weight.

11. A molded article containing a molding compound as claimed in claim 8.

12. A process for producing a polyphosphazene comprising the steps a) and b) a) reaction of a cyclic phosphazene of formula (1) ##STR00014## wherein k is a natural number between 1 and 10 with phenol in the presence of a base b) further reaction with an aromatic diphenol according to formula (2) ##STR00015## wherein R.sup.1 and R.sup.2 independently of one another represent H or C.sub.1- to C.sub.8-alkyl and X represents a single bond, C.sub.1- to C.sub.5-alkylene, C.sub.2- to C.sub.5-alkylidene, C.sub.5- to C.sub.6-cycloalkylidene, —O—, —SO—, —CO—, —S—, or —SO.sub.2— in the presence of a base wherein the molar ratio of employed phenol to the employed cyclic phosphazene of formula (1) is in the range from 3.5:1 to 1:1.

13. The process as claimed in claim 12, characterized in that the employed aromatic diphenol of formula (2) is 2,2-bis(4-hydroxyphenyl)propane.

14. The process as claimed in claim 12, characterized in that the steps a) and/or b) are performed at a temperature between 20° C. and 80° C.

15. The process as claimed in claim 12, characterized in that after step b) there is also a purification step selected from filtration and extraction.

Description

EXAMPLES

[0215] Materials

[0216] Hexachlorocyclotriphosphazene (HCCP, abcr) was recrystallized from hexane. Bisphenol-A (BPA, Covestro), phenol (Ph, abcr), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, Alfa Aesar), sodium phenoxide (Alfa Aesar), tetrahydrofuran (THF, VWR), toluene (VWR) and acetonitrile (MeCN, Roth) were used without further purification.

[0217] The polycarbonate used was Makrolon® 2600 (Covestro).

[0218] Rabitle™ FP 110 (Fushimi, Japan) is a phenoxyphosphazene of formula (6) having a proportion of oligomers with k=1 of 70 mol %, a proportion of oligomers with k=2 of 18 mol % and a proportion of oligomers with k≥3 of 12 mol %. This phosphazene was employed as comparative example 1.

##STR00011##

[0219] Analysis/Characterization

[0220] The TGA-FTIR analyses were performed in a temperature range of 30° C. to 800° C. at a heating rate of 10 K.Math.min.sup.−1 and an oxygen flow of 150 mL.Math.min.sup.−1. The onset temperature was determined by application of tangents. The maxima of the 1st derivative were assumed to be the decomposition temperatures.

[0221] Limiting Oxygen Index (LOI) Measurements were made according to the standard ISO 4589:2017. Prior to measurement the samples were conditioned for at least 88 h at 22° C. and 55% humidity.

[0222] The swelling of the polymers was tested in chloroform. The (poly)phosphazenes were stored in this solvent for 3 days and the weight was determined before and after swelling. Swelling factor Q is calculated as described above according to

[00003]$Q=\frac{a-b}{b},$

wherein

[0223] a is the mass of the swollen polyphosphazene and

[0224] b is the mass of the unswollen polyphosphazene.

[0225] DSC testing for determining the glass transition temperature T.sub.g was performed in the temperature range from 20° C. to 250° C. and −95° C. to 250° C. at a heating rate of 20° C..Math.min.sup.−1.

[0226] The following phosphazene-based FR additives were produced or obtained and processed with Makrolon® 2600 to afford PC/FR blends:

Example According to the Invention: Synthesis of the Polyphosphazene (Molar Ratio of Employed Phenol to Employed Cyclic Phosphazene 3:1)

[0227] DBU (14 mL, 0.09 mol, molar ratio (=MR) to OH groups of the phenol=1) was added dropwise at room temperature to a solution of phenol (8.66 g, 0.09 mol) and HCCP (10.67 g, 0.03 mol) in 2 L of MeCN over 30 minutes. After 2 h, BPA (13.6 g, 0.06 mol) and DBU (18 mL, 0.12 mol, MR to OH groups of BPA=1) were added to the reaction solution and the reaction was stirred overnight. After termination of the reaction the solvent was decanted off and the product taken up in 100 mL of THF/toluene mixture in the form of a gel. The product mixture was washed alternately with THF and MeCN and dried under vacuum for 4 days at 80° C. The product was obtained as a crystalline solid (9.8 g).

Comparative Example 1: Phenoxyphosphazenes Rabitle™ FP110

[0228] For comparative example 1, the commercially available Rabitle™ FP 110 was used and employed as obtained.

Comparative Example 2: Synthesis of a Phenoxyphosphazene Based on EP 1104766 B1 (Molar Ratio of altogether Employed Phenoxide to Employed Cyclic Phosphazene 6:1)

[0229] The phenoxyphosphazene described in the Examples of EP 1104766 B1 was reproduced by a modified route to avoid the use of metallic sodium and lithium. A compound having a molecular weight similar to that described in EP 1104766 B1 was obtained (1403 g/mol compared to 1130 g/mol according to EP 1104766 B1). To this end a mixture of BPA (5.71 g, 0.02 mol), sodium phenoxide (12.9 g, 0.11 mol) and DBU (3.4 mL, MR=0.5) in 80 mL of THF was added dropwise at RT over 1 h to a solution of HCCP (11.59 g, 0.03 mol) in 375 mL of MeCN. After a reaction time of 5 h sodium phenoxide (8.08 g, 0.07 mol) in 100 mL of toluene were added to this solution and the reaction solution was stirred at RT overnight. After termination of the reaction the solvent was concentrated under vacuum and the residue was taken up in 100 mL of toluene and extracted 3 times with 100 mL of a 2% aqueous NaOH solution. The organic phase was additionally extracted 3 times with 100 mL of dist. water and the solvent removed under vacuum. The obtained product was dried under vacuum at 80° C. for 4 days and isolated as a gel (18.6 g).

Comparative Example 3: Synthesis of a Phenoxyphosphazene Based on CN 102675591 A (Molar Ratio of Employed Phenol to Employed Cyclic Phosphazene 4.2:1)

[0230] HCCP (1.00 g, 2.88 mmol) was dissolved in 100 mL of MeCN. A solution of phenol (1.14 g, 12.08 mmol) and DBU (1.8 mL, 12.08 mmol) in 40 mL of MeCN was added dropwise to the HCCP solution over the course of one hour. The reaction solution was stirred overnight. Once the reaction time had elapsed a solution of BPA (1.44 g, 6.33 mmol) and DBU (2.6 ml, 17.26 mmol) in 40 ml of MeCN was added dropwise to the reaction solution over the course of one hour and the mixture was stirred overnight. The reaction solution was then concentrated under vacuum and subsequently admixed with 50 mL of toluene. The organic phase was washed three times with 50 mL of 2% aqueous NaOH solution and extracted three times with 50 mL of dist. water. The solvent was removed under vacuum and the residue dried under vacuum at 80° C. for four days. The product was obtained as a viscous gel (3.04 g).

[0231] Production of PC/FR Blends

[0232] Makrolon® 2600 was mixed with different parts by weight of the polyphosphazene according to the invention and the comparative examples 1-3 in a Micro 15 cc Twin Screw Compounder from DSM. PC/FR blends having a % by weight ratio of PC to FR additive of 90:10, 80:20 and 70:30 were produced in this way. For the LOT measurements test specimens according to DIN EN ISO 4589-2:1999+A1:2006 measuring 70×6.5×3 mm.sup.3 were injection molded and for the DMA measurements test specimens measuring 60×13×2 mm.sup.3 were injection molded.

[0233] The Makrolon® 2600 was pre-dried according to DIN EN ISO 7391-2:2006 (D) for (5 ±1) hat (120±3)° C. in a pellet dryer (HELIOS WINstandard) and immediately subjected to further processing. The compounding was carried out at 270° C. in a nitrogen atmosphere at a screw speed of 100 rpm.

[0234] Results

TABLE-US-00001 TABLE 1 Tg and swelling factors of the pure substances Swelling factor in Example FR additive Tg chloroform Example according to polyphosphazene 107.9° C. 6.07 the invention Comparative example 1 Rabitle ™ FP110 −13.7° C. 0 Comparative example 2 Based on EP 20.6° C. 0 1104766 B1 Comparative example 3 Based on CN −4.7° C. 0 102675591 A

[0235] The results in Table 1 show that the polyphosphazene according to the invention has a markedly higher glass transition temperature than the phosphazenes from the prior art. Furthermore, the measured swelling factor indicates a crosslinked structure.

TABLE-US-00002 TABLE 2 LOI and T.sub.g of the PC/FR blends PC/FR T.sub.g of PC/FR blends blends % by wt. PC/FR with FR additive LOI* 100:00 90:10 80:20 70:30 Example According to 29 149° C. 146° C. 143° C. 143° C. according to the invention the invention Comparative Rabitle ™ 29 149° C. 130° C. 107° C.  89° C. example 1 FP100 Comparative based on EP 28 149° C. 141° C. 129° C. 116° C. example 2 1104766 B1 Comparative based on CN — 149° C. 111° C. — — example 3 102675591 A *The LOI tests were performed for PC/FR blends having a % by weight ratio of PC to FR additive of 90:10

[0236] Table 2 summarizes the results of the various PC/FR blends and illustrates the equally good flame retardant effect of the phosphazenes. However, the phosphazene according to the invention results in a markedly less pronounced reduction in the glass transition temperature of a polycarbonate molded compound than known phosphazenes where the molar ratio of employed phenol to employed cyclic phosphazene is outside the range according to the invention. In particular, the use of the FR additive from comparative example 3 resulted in a very strong reduction in the glass transition temperature and a brittle and easily breakable PC/FR blend even at a proportion of 10% by weight. It was not possible to produce standard-compliant test specimens for determining the LOT value for comparative example 3.