JPH04314737A - Method for producing phosphazene polymer - Google Patents

Abstract

PURPOSE:To produce the title polymer in a short time at a high yield under relatively mild conditions without causing any problem with residual chlorine by polycondensing an N-silylphosphazene compd. using an alkali metal alkoxide as a catalyst. CONSTITUTION:The title polymer of formula II is produced by polycondensing an N-silylphosphazene compd. of formula I using an alkali metal alkoxide represented by R<7>OM (wherein R<7> is an optionally substd. monovalent aliph. hydrocarbon group) as a catalyst. In formulas I and II, R<1> is a monovalent hydrocarbon group wholly or partially substd. by fluorine; R<2>, R<3>, R<4>, R<5>, and R<6> are each independently an optionally substd. monovalent hydrocarbon group; and n is the degree of polymn. The polycondensation proceeds almost quantitatively to produce the polymer at a very high yield.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing phosphazene polymers which are useful as elastic bodies having excellent properties such as heat resistance, cold resistance and oil resistance.

0002

[Prior Art and Problems to be Solved by the Invention] Phosphazene polymers are polymeric compounds having a P=N skeleton, and have excellent retardancy and low smoke generation properties, as well as organic groups bonded to phosphorus atoms. Various properties can be imparted depending on the type, and it is attracting attention as a highly functional material.

[0003] Conventionally, as a method for producing this phosphazene polymer, a method has been known in which hexachlorocyclotriphosphazene is subjected to ring-opening polymerization to form dichlorophosphazene, and then the chlorine atom in this compound is replaced with various organic groups. (U.S. Pat. No. 3,370,020). Also,
As a method for producing phosphazene polymers by polycondensation reaction, a method of polycondensing N-(dichlorophosphoryl)trichlorophosphazene has also been proposed (Japanese Patent Publication No. 1986-50).
1144).

However, in the method of ring-opening polymerization of hexachlorocyclotriphosphazene, when the polymer yield reaches around 60%, a crosslinking reaction occurs and gelation occurs. The process must be stopped at a certain point, and it takes time and effort to replace the chlorine atoms in the polymer with various organic groups after polymerization, making the resulting polymer extremely expensive. Furthermore, even in the above substitution reaction, it is difficult to completely replace chlorine atoms, and there is a problem that trace amounts of residual chlorine may affect the performance of the polymer. Further, in the method of polycondensing N-(dichlorophosphoryl)trichlorophosphazene, although the polymer yield is improved, the problem regarding residual chlorine is not solved.

[0005] Therefore, as a method for producing phosphazene polymers without causing the problem of residual chlorine, a method has been proposed in which N-trimethylsilylphosphazene, which is an organophosphazene monomer, is polycondensed (US Pat. No. 4, No. 412,053).

However, although this production method improves the problems of polymer yield and residual chlorine, it has the problems of a high reaction temperature of 190° C. or higher and a reaction time of 40 hours or more. are doing.

The present invention was developed in view of the above circumstances, and it is possible to produce a phosphazene polymer in a short time and in high yield under relatively mild reaction conditions without causing the problem of residual chlorine. The purpose of the present invention is to provide a method for producing a novel phosphazene polymer.

[0008]

[Means and effects for solving the problem] As a result of intensive studies to achieve the above object, the present inventors have discovered that by heating an N-silylphosphazene compound represented by the following general formula (1), When condensing to obtain a phosphazene polymer, an alkali represented by the general formula R7OM (where R7 represents a substituted or unsubstituted monovalent aliphatic hydrocarbon group, and M represents an alkali metal) is used as a polycondensation catalyst. By using a metal alkoxide compound, the polycondensation reaction can be efficiently promoted, and the phosphazene polymer represented by the following general formula (2) can be produced with high yield in a short time of 3 to 30 hours at a relatively low temperature of 50 to 180°C. The present inventors have completed the present invention by discovering that it is possible to produce a polymer without causing the problem of residual chlorine mentioned above, since neither the starting material nor the catalyst contains chlorine atoms in this case. It is something.

[0009]

[Case 2]

Therefore, the present invention uses an N-silylphosphazene compound represented by the general formula (1) as a polycondensation catalyst to form a polycondensation compound of the general formula R7OM (where R7 represents a substituted or unsubstituted monovalent aliphatic hydrocarbon group). , M represents an alkali metal) The present invention provides a method for producing a phosphazene polymer represented by the general formula (2), which is characterized by polycondensation using an alkali metal alkoxide compound represented by the formula (2).

[0011] The present invention will be explained in more detail below. In the production method of the present invention, the starting material N
As mentioned above, the -silylphosphazene compound is a phosphazene monomer represented by the following general formula (1).

0012

[Chemical 3]

Here, R1 in the above formula (1) is a monovalent aliphatic hydrocarbon group such as an alkyl group, an alkenyl group, a cycloalkyl group, an aralkyl group, preferably having 1 to 10 carbon atoms,
More preferably, it is a monovalent aliphatic hydrocarbon group having 1 to 5 carbon atoms in which part or all of the hydrogen atoms are replaced with fluorine atoms, specifically trifluoromethyl group, 2,2,2-
Examples include trifluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 2,2,2,3,3,3-hexafluoroisopropyl group, and the like. Also, R2, R
3, R4, R5, and R6 are the same or different unsubstituted or substituted monovalent hydrocarbon groups, preferably having 1 to 2 carbon atoms.
0, more preferably one having 1 to 6 carbon atoms, specifically alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, vinyl group, isopropenyl group, etc. Examples thereof include alkenyl groups such as a group, an allyl group, a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group, an aralkyl group such as a benzyl group, and an aryl group such as a phenyl group, a tolyl group, and a naphthyl group.

On the other hand, the alkali metal alkoxide compound used as a polycondensation catalyst in the production method of the present invention is represented by the general formula R7OM, where R7 is a substituted or unsubstituted monovalent aliphatic hydrocarbon. A group having preferably 1 to 20 carbon atoms, more preferably 1 to 6 carbon atoms. Specifically, R7 includes alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, and isobutyl group, cycloalkyl groups such as cyclopentyl group and cyclohexyl group, and aralkyl groups such as benzyl group. Examples include groups. Further, M is an alkali metal, and specific examples thereof include lithium, sodium, potassium, rubidium, and cesium. Specifically, the alkali metal alkoxide compounds include lithium methoxide, lithium ethoxide, lithium 2,
2,2-trifluoroethoxide, lithium n-propoxide, lithium isopropoxide, lithium n
-butoxide, lithium t-butoxide, sodium methoxide, sodium ethoxide, sodium 2,2,2-trifluoroethoxide, sodium n
-propoxide, sodium isopropoxide, sodium n-butoxide, sodium t-butoxide, potassium methoxide, potassium ethoxide, potassium 2,2,2-trifluoroethoxide, potassium n-propoxide, potassium isopropoxide,
Potassium n-butoxide, potassium t-butoxide, rubidium methoxide, rubidium ethoxide,
Examples include rubidium 2,2,2-trifluoroethoxide, cesium methoxide, cesium ethoxide, cesium 2,2,2-trifluoroethoxide, and among these, sodium ethoxide, potassium methoxide, etc. Potassium t-butoxide, potassium t-butoxide, and the like are preferably used.

The production method of the present invention provides (1) of the above starting materials.
) The phosphazene monomer represented by the formula is heated and polycondensed using the above alkali metal alkoxide compound as a polycondensation catalyst. In this case, the amount of the alkali metal alkoxide compound used should be a catalytic amount. The molar ratio is usually about 1/10 to 1/106 to the starting material phosphazene monomer. Further, the alkali metal alkoxide compound may be added to the reaction system as it is, or it may be added after being dissolved in an appropriate solvent. In addition, as a solvent in this case, N,N-dimethylformamide, tetrahydrofuran, etc. can be used.

In this polycondensation reaction, the phosphazene polymer shown in formula (2) is produced according to reaction formula (A) below, and in this case, the reaction may be carried out without a solvent or in a suitable organic solvent. In this case, the reaction solvent may be diglyme, triglyme, tetraglyme, N
, N-dimethylformamide, N-methyl-2-pyrrolidone, hexamethylphosphoramide, and the like. Moreover, this polycondensation reaction is preferably carried out under an inert gas atmosphere such as nitrogen gas or argon gas. Further, the reaction conditions are a reaction temperature of 50 to 180°C, especially 80 to 130°C, for 3 hours or more, especially 5 to 130°C.
It is preferable to carry out the reaction for 20 hours, and it is preferable to carry out the reaction while distilling off volatile condensates from the reaction system. In addition, in the case of bulk polymerization, the generated phosphazene polymer can be directly subjected to the next processing step, or in the case of solution polymerization using a solvent, it can be separated using ordinary separation means, such as a non-solvent such as methanol. It can be easily separated and purified by methods such as reprecipitation.

[0017]

[C4]

In the production method of the present invention, the polycondensation reaction proceeds almost quantitatively, making it possible to produce a phosphazene polymer in an extremely high yield. After stopping the polymerization reaction, it is possible to restart the polymerization reaction by adding the starting material phosphazene monomer and heating it to return the reaction system to the temperature of the polymerization conditions, and the polymer obtained by this operation The degree of polymerization can be increased.

[0019]

[Examples] The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to the following Examples. In the following examples, the molecular weight of the polymer was measured using a GPC molecular weight measuring device (HLC-8020 manufactured by Toso).

[Example 1] Sufficiently dried content 20
A 0 ml four-necked flask was equipped with a thermometer, a stirrer, a nitrogen gas cock, and a Liebig condenser connected to a receiver, and P-tris(2,2,2-trifluoroethoxy)-N was placed in the flask. -trimethylsilylphosphazene 2
0.8g and 1.0ml of a 50mM solution of sodium ethoxide in dimethylformamide and 1 part of dimethylformamide
5 ml, and the inside was replaced with dry nitrogen. The flask was immersed in a silicone oil bath while blowing dry nitrogen into the interior, heated at 120°C for 20 hours with stirring to perform a polycondensation reaction, and 2,2,2-trifluoroethyltrimethylsilyl ether was added to the receiver. At the same time, the reaction mixture in the flask was poured into 100 ml of methanol to separate and recover the phosphazene polymer as a precipitate, which was dried in a vacuum dryer to give polybis(2,2 , 2-trifluoroethoxy)phosphazene was obtained.

The number average molecular weight of the obtained phosphazene polymer was 157,000, and the weight average molecular weight was 174,000. Further, this polymer was soluble in acetone, tetrahydrofuran, N,N-dimethylformamide, ethyl acetate, etc., but insoluble in methanol, toluene, xylene, hexane, heptane, dichloromethane, chloroform, etc.

[Example 2] Using potassium methoxide instead of sodium methoxide as a polycondensation catalyst,
A polycondensation reaction was carried out in the same manner as in Example 1 except that diglyme was used instead of dimethylformamide as the reaction solvent, and 7.3 g of a volatile condensate consisting of 2,2,2-trifluoroethyltrimethylsilyl ether was placed in the receiver. At the same time, a part of the reaction mixture in the flask was sampled, and the phosphazene polymer was separated from this sample. This phosphazene polymer has a number average molecular weight of 15
．． 00,000, and the weight average molecular weight was 167,000.

Next, P- is added to the reaction mixture in this flask.
10.4 g of tris(2,2,2-trifluoroethoxy)-N-trimethylsilylphosphazene and 10 ml of diglyme were added and a polycondensation reaction was carried out at 120°C for 6 hours with stirring, and 2,2,2- Volatile condensate 3 consisting of trifluoroethyltrimethylsilyl ether
．． 7 g was collected, and the reaction mixture in the flask was reduced to 1
The phosphazene polymer was poured into 50 ml of methanol, separated and recovered as a precipitate, and dried in a vacuum drier to obtain 17.2 g of polybis(2,2,2-trifluoroethoxy)phosphazene. This phosphazene polymer had a number average molecular weight of 214,000 and a weight average molecular weight of 231,000. From this, it was confirmed that the once stopped reaction can be restarted by adding a monomer and heating again, and that the molecular weight of the resulting polymer increases in this case.

[Example 3] Lithium 2,2 prepared from equimolar amounts of 2,2,2-trifluoroethanol and a 15% n-hexane solution of n-butyllithium instead of sodium methoxide as a polycondensation catalyst , 50mM tetrahydrofuran solution of 2-trifluoroethoxide 1
．． A polycondensation reaction was carried out in the same manner as in Example 1 except that 0 ml was used, and a volatile condensate consisting of 2,2,2-trifluoroethyltrimethylsilyl ether 7.3 was placed in the receiver.
At the same time, the reaction mixture in the flask was reduced to 100 g.
ml of methanol to separate and collect the phosphazene polymer as a precipitate, and dry it in a vacuum dryer to obtain polybis(2,2,2-trifluoroethoxy)phosphazene 1.
0.8g was obtained.

The number average molecular weight of the obtained phosphazene polymer was 168,000, and the weight average molecular weight was 177,000.

[Example 4] P-diphenoxy- in place of P-tris(2,2,2-trifluoroethoxy)-N-trimethylsilylphosphazene as a raw material monomer
A polycondensation reaction was carried out in the same manner as in Example 1 except that 20.3 g of 2,2,2-trifluoroethoxy-N-trimethylsilylphosphazene was used, and 2,2,2-
7.4 g of a volatile condensate consisting of trifluoroethyltrimethylsilyl ether was recovered, and the reaction mixture in the flask was poured into 100 ml of methanol to separate and recover the phosphazene polymer as a precipitate, which was then dried in a vacuum dryer. 9.0 g of polydiphenoxyphosphazene was obtained.

The number average molecular weight of the obtained phosphazene polymer was 173,000, and the weight average molecular weight was 187,000. This polymer also contains acetone, tetrahydrofuran,
It was soluble in N,N-dimethylformamide, ethyl acetate, toluene, xylene, etc., but insoluble in methanol, ethanol, hexane, heptane, etc.

[0028]

Effects of the Invention As explained above, according to the method for producing a phosphazene polymer of the present invention, the polymerization temperature is 50 to 180°C.
A phosphazene polymer that does not contain any chlorine atoms can be produced easily and in high yield under relatively mild reaction conditions such as temperature and reaction time of 3 hours or more. It is possible to omit post-treatment steps such as a monomer separation step and a substitution reaction step, and the phosphazene polymer can be industrially produced very advantageously.

Claims (1)

[Claims] Claim 1: Using an N-silylphosphazene compound represented by the following general formula (1) as a polycondensation catalyst, a compound of the general formula R7O
The following formula ( A method for producing a phosphazene polymer represented by 2). [Chemical formula 1]