JPS6242843B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a phosphazene polymer, which is characterized by converting a phosphazene oligomer into a high molecular weight phosphazene polymer by heating the phosphazene oligomer to 150 to 350° C. in a closed system using a urea-based compound as a catalyst. More specifically, a substantially single phosphazene polymer is produced by heating a mixture of a linear phosphazene oligomer and a cyclic phosphazene oligomer to 150 to 350°C in a closed system using a urea-based compound as a catalyst to increase the molecular weight. Regarding the method. Phosphazene polymer (polydichlorophosphonitrile) was already developed into hexachlorocyclotriphosphonitrile (hereinafter referred to as trimer) in the early 19th century.
It was first synthesized by igniting. However, it can only be obtained as a gelled product that is insoluble in organic solvents and is extremely easily hydrolyzed, so it has been discarded as it is. In the mid-1960s, H.R.
found that by carefully heating the trimer in a vacuum-sealed tube, a phosphazene polymer soluble in organic solvents was obtained, which was further bonded to the phosphorus atoms forming the molecular backbone of the polymer. By substituting the chlorine atom with a suitable substituent, for example, a nucleophilic group such as a fluoroalkoxy group, perfluoroalkoxy group, allyloxy group, aryloxy group, or other alkoxy group, it becomes highly resistant to water, acids, or bases. It became possible to obtain stable polymers. These phosphazene polymers have excellent heat resistance, flame resistance, oil resistance, etc. due to their inorganic properties, and are suitable for use as flame retardants for fire-resistant foam rubber equipment and plastics.
Because it retains its flexibility even at ℃ and has excellent properties such as oil resistance and resistance to working fluids, it has been extensively researched for use in industrial fields as O-rings, gaskets, hydrocarbon fuel hoses, etc. It is. Furthermore, it has been revealed that the above-mentioned polymers have extremely low interaction with living tissues, and research is being actively conducted on their use in the biomedical field as blood vessel substitutes, artificial organs, and the like. As the field of application of phosphazene polymers expands, various methods for producing phosphazene polymers have been developed, but most of them are based on thermal ring-opening polymerization of trimers as mentioned above, and most of them are based on H. This is an improvement or modification of the manufacturing method of R. Allkottsuk et al. For example, the trimer is heated in a sealed tube in octachlorocyclotetraphosphonitrile (hereinafter referred to as "tetramer") for 200 min.
A method of thermal ring-opening polymerization at ~300℃, a method of adding phosphorus pentachloride to the trimer and thermal ring-opening polymerization in a sealed tube, a method of thermally ring-opening polymerization of the trimer in a sealed tube, and a method of thermally ring-opening polymerization of the trimer in an organic solvent using an acid, metal, quaternary ammonium salt, etc. as a catalyst. A method of thermal ring-opening polymerization of a trimer using water as a catalyst, a method of thermal ring-opening polymerization of a trimer using a Lewis acid as a catalyst, and a method of thermally ring-opening polymerizing a trimer using water as a catalyst. A commonly used method is thermal ring-opening polymerization of chloroalkoxycyclotriphosphonitrile at 200 to 250°C. However, with these conventional techniques, if you try to increase the conversion rate of trimer to phosphazene polymer above several tens of percent (weight %, the same applies hereinafter), gelation will inevitably occur, so the conversion rate will reach several tens of percent. At this point, the reaction must be stopped and the unreacted trimer must be recovered by sublimation or reprecipitation. Moreover, only the trimer undergoes thermal ring-opening polymerization to form a phosphazene polymer; The macrocyclic phosphazene oligomer itself not only does not undergo thermal ring-opening polymerization, but also has a strong tendency to suppress the ring-opening polymerization of the trimer. Therefore, it is necessary that the trimer used for the ring-opening polymerization be of high purity. required. On the other hand, the synthesis of trimer, which is the raw material for producing phosphazene polymers, is usually carried out by reacting phosphorus pentachloride and ammonium chloride in an appropriate solvent system. Phosphazene oligomers and macrocyclic phosphazene oligomers such as tetramer and decachlorocyclopentaphosphonitrile (hereinafter referred to as pentamer) are produced as by-products, and with current technology, it is impossible to produce trimers with a yield of only about 50% from raw materials. The reality is that they cannot be replaced, so it is inevitable that manufacturing costs will increase. In addition, methods for synthesizing phosphazene oligomers (methods for synthesizing the above-mentioned trimers fall within this category) include a reaction between phosphorus and ammonium chloride, a reaction between phosphorus trichloride and chlorine gas and ammonium chloride, Various synthetic methods have been proposed, including those based on the reaction of phosphorus pentachloride and ammonia, those based on the reaction between phosphorus pentachloride and ammonium chloride, and those using metals as catalysts for these reactions, but the basics are as follows. The reaction is simply a reaction between phosphorus pentachloride and ammonium chloride. The reaction mechanism is said to be that a cyclic phosphazene oligomer is produced via a linear phosphazene oligomer, and the product is a mixture of a linear phosphazene oligomer and a cyclic phosphazene oligomer, and the production ratio of each is can be changed depending on the reaction conditions. An outline of this reaction is shown in equation (1).

[Table] [A] is generally a phosphazene oligomer in which n is in the range of 2≦n≦20, but depending on the reaction conditions, it may be a high molecular weight linear phosphazene with n being 10,000 or more. be. The main component of [B] is a trimer, and generally up to a tetramer is obtained as a crystal, and larger cyclic phosphazene oligomers are obtained as an oil. (However, it is known that even hexadecylchlorocyclooctaphosphonitrile (octamer) can be crystallized by careful crystallization.) The production ratio of [A] and [B] changes depending on the reaction conditions, but generally when the reaction is carried out in a system with an excess of phosphorus pentachloride, the production ratio of [A] increases and its molecular weight increases. It is normal for it to be small. However, it is difficult to obtain the product [A] alone or the product [B] alone under any conditions. Of course, it is extremely difficult to obtain only the trimmer. As mentioned above, when phosphorus pentachloride and ammonium chloride are reacted, linear phosphazene oligomers and cyclic phosphazene oligomers are produced, but the former is extracted from the reaction product as petroleum ether insoluble matter, and The latter are separated as petroleum ether solubles. Linear phosphazene oligomers are Cl−( _PCl2N ) _{−o PCl4} or Cl−(
It has a highly polar chain structure with the structural formula _PCl2N ) _-oH , and its phosphonitrile units are 2 to 50,000, and the terminal phosphorus pentachloride or hydrogen chloride is extremely unstable. It is thought that they are connected in a state. As described above, the production of phosphazene polymers is currently in low demand due to the fact that the trimer, which is the raw material for producing phosphazene polymers, is not available in high purity and the yield of the ring-opening polymerization reaction to form phosphazene polymers is low. The reality is that it cannot be manufactured at low cost. However, in order to eliminate the above-mentioned drawbacks and industrially advantageously produce a phosphazene polymer, the present inventors investigated the production raw materials and found that phosphorus pentachloride and ammonium chloride were first mixed at 130% in an open system.
When heating to ~150°C to synthesize phosphazene oligomers and then further raising the temperature to 180~200°C, the reaction system gels; however, when performing the same reaction as above in a closed system, the reaction system gels. However, in the case of an open system, the amount of cyclic phosphazene oligomers produced is small from 130 to 150℃.
It has been found that although there is almost no change before and after raising the temperature to 180 to 200°C, in the case of a closed system, the amount of cyclic phosphazene oligomers decreases after raising the temperature than before raising the temperature. Further research based on this knowledge revealed that ring-opening copolymerization of cyclic phosphazene oligomers is likely to occur in the coexistence of linear phosphazene oligomers, and that this effect is more pronounced in closed systems. However, in such a reaction method, although ring-opening copolymerization of cyclic phosphazene oligomers can occur as described above, on the other hand, linear phosphazene oligomers remain as they are, so the resulting phosphazene polymer has been found to have problems in terms of physical properties. As a result of further research, they discovered that by adding a small amount of a urea-based compound to the reaction system, linear phosphazene oligomers can be converted into phosphazene polymers extremely efficiently, leading to the completion of the present invention. . That is, the present invention involves heating a mixture of a linear phosphazene oligomer and a cyclic phosphazene oligomer containing a linear phosphazene oligomer in a range of 5 to 95% by weight in a closed system at 150 to 350°C using a urea-based compound as a catalyst. The present invention relates to a method for producing a phosphazene polymer, which is characterized by converting the phosphazene polymer into a high molecular weight phosphazene polymer by heating. The mixture of linear phosphazene oligomers and cyclic phosphazene oligomers used in the present invention includes, for example, linear phosphazene oligomers, trimers, tetramers, and larger macrocyclic phosphazenes produced from phosphorus pentachloride and ammonium chloride. Examples include mixtures with oligomers (chlor compounds). In addition, in the present invention, not only the above-mentioned chloride but also other halogens, such as bromine (stabilized with phosphorus pentabromide or hydrogen bromide), may be used, and their linear A mixture of a phosphazene oligomer and a cyclic phosphazene oligomer may be used as appropriate. In the present invention, examples of the catalyst include urea-based compounds such as urea, thiourea, polyurea, and polythiourea, and one or more of these may be used as appropriate. Next, the method of the present invention will be explained using an example in which a chloride is used as a phosphazene oligomer. The urea-based compound catalyst reacts with the terminal phosphorus pentachloride or hydrogen chloride without almost reacting with the chlorine atom bonded to the phosphorus atom of the phosphonitrile unit of the linear phosphazene oligomer and phosphazene polymer, and Since the reaction is gradual, linear phosphazene oligomers can be smoothly converted into polymers without side reactions such as crosslinking reactions. In addition, in such a reaction, a substance that acts like a Lewis base other than the above-mentioned urea-based compound, such as water, sulfur dioxide gas, alcohol, polyhydric alcohol,
Alcoholates, epoxides, ketones, caustic alkalis, metal hydroxides, fatty acid salts, hydrazines,
Quaternary ammonium salt, hydroxide, amine,
Ammonia etc. may be used in combination. Further, ether, benzene, toluene, xylene, olefin, etc. can be used as a solvent and can also be used as a catalyst. The amount of the catalyst used is 0.01 to 10%, preferably 0.1 to 5% of the total phosphazene oligomer.
% is used as appropriate. When the catalyst is used in an amount less than 0.01% of the phosphazene oligomer, the reaction rate is so slow that it is not practical, and when it is used in an amount more than 10%, it does not pose any hindrance to the reaction. However, this is not preferable since it causes trouble in the post-processing operations of the obtained phosphazene polymer. Although the mechanism of increasing the molecular weight of the phosphazene oligomer into a polymer in the present invention is not necessarily clear, the linear phosphazene oligomer or the cyclic phosphazene oligomer has a mixing ratio of the cyclic phosphazene oligomer and the linear phosphazene oligomer, respectively. The chart pattern in the gel vermi-ation chromatography analysis of the phosphazene polymer produced when the It is considered that some kind of interaction exists, and as a result, the polymerization reaction progresses in a copolymerization manner, and the resulting polymer is essentially a single copolymer-like polymer. This is schematically shown in equation (2).

[Table] ↓
phosphazene polymer
2≦n≦50000 (2)
l〓m＞n〓m
That is, the initiation of polymerization is thought to be due to the betaine conversion ([C] in formula (2)) of the linear phosphazene oligomer with a urea-based compound, and this betaine [C] is caused by the head-to-tail polymerization or the starting material. It is thought that the molecular weight is increased by the reaction with the linear phosphazene oligomer, while the cyclic phosphazene oligomer is copolymerized in a ring-opening manner. The reaction temperature is 150~ in a closed system as mentioned above.
A temperature of 350°C, preferably 200-300°C is employed. 150
When the reaction is carried out at a temperature lower than 350°C, the reaction is difficult to occur, and when the reaction is carried out at a temperature higher than 350°C, depolymerization and gelation reactions of the produced polymer occur, so both are not preferred. Further, the reaction time is usually about 0.5 to 300 hours, and a uniform phosphazene polymer can be obtained. The mixture of a linear phosphazene oligomer and a cyclic phosphazene oligomer used in the present invention includes a linear phosphazene oligomer containing a linear phosphazene oligomer in an amount of 5 to 95%, preferably 10 to 90%, and a cyclic phosphazene oligomer. Mixtures with phosphazene oligomers are effectively used. If the amount of linear phosphazene oligomers is less than 5% of the total phosphazene oligomers, the polymerization rate will be low and it is not practical, and if it is more than 95%, the cyclic phosphazene oligomers will be efficiently ring-opening polymerized. This is not preferable from the viewpoint of the purpose of the present invention. When carrying out the present invention, as long as the reaction system is a closed system as described above and is well dried, the reaction system can be carried out in vacuum, air, inert gas, or in a solvent or non-solvent system. It can be carried out regardless of the situation. This is also one of the features of the present invention. The reason why a closed system is effective in the present invention is considered to be that gelation of the polymer is suppressed by hydrogen chloride generated during the polymerization reaction. The method of the present invention can be carried out in either a solvent system or a non-solvent system, but when the reaction is carried out in a solvent system, benzene, toluene, xylene, chlorobenzene, dichlorobenzene, etc. can be used as the reaction solvent. is used. EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples. Example 1 Phosphorus pentachloride 208.3g (1 mol), ammonium chloride 48.2g (0.9 mol) and o-dichlorobenzene
163 g was charged into a 500 cc four-necked flask, and the reaction was carried out at 145° C. for 12 hours with stirring. During this time, hydrogen chloride was distilled out of the system. After the reaction was completed, unreacted ammonium chloride was removed (trace amount), and the liquid was concentrated using a rotary evaporator. This was then extracted with petroleum ether and separated into a petroleum ether insoluble fraction (linear phosphazene oligomer) and a petroleum ether soluble fraction (cyclic phosphazene oligomer). The former was 67.2g, and the latter was 47.4g. The composition of the cyclic phosphazene oligomer is
As a result of GLC analysis, cyclic phosphazene oligomers with 64.9% trimer (3PNC), 17.9% tetramer (4PNC), and 17.2% pentamer (5PNC) were found.
It was %. Furthermore, the molecular weight of the linear phosphazene oligomer was determined to be 1100 by the VPO method. This is thought to have the structure _of Cl-( _PNCl2 ) _-8PCL4 . 6.7 g of the linear phosphazene oligomer and 4.7 g of the cyclic phosphazene oligomer were charged into an approximately 30 cc Pyrex glass polymerization tube, and powdered urea was added.
After adding 200 mg of nitrogen and purging the system with nitrogen gas, the tube was vacuum-treated (10 ^-2 torr) and sealed. This polymerization tube was then left in an oven at 255°C for 5 hours. During this time, the reaction system became homogeneous and viscous solid. This was taken out from the oven, cooled to room temperature, opened, and the contents were taken out using o-dichlorobenzene. After removing the o-dichlorobenzene insoluble matter, the liquid was poured into a large amount of petroleum ether to precipitate the resulting polymer, yielding 9.3 g of a white rubbery polymer (the conversion rate of the starting material to the polymer was 81.6).
%) was obtained. In addition, the petroleum ether layer was concentrated to obtain 0.5 g of an oily substance. As a result of GLC analysis, this oily substance contained 0.1 g of 3PNC, 0.25 g of 4PNC, and 0.15 g of 5PNC or more. If this oily substance is all derived from the cyclic phosphazene oligomer as the starting material, the respective residual rates are 3.3% for 3PNC, 29.8% for 4PNC,
18.5% for 5PNC or more. Incidentally, among the o-dichlorobenzene insoluble matter, 0.2 g of gelled material derived from the phosphazene polymer was found. Since the obtained polymer is sensitive to moisture, it was converted into a 2,2,2-trifluoroethoxy compound (Note 1) using a conventionally known method, and then subjected to GPC.
The molecular weight was measured by the gel permeation chromatography (Note 2) method, and the average molecular weight was 5,335,000.

[Table] Example 2 Linear phosphazene oligomer obtained in Example 1
3.4 g, 2.4 g of cyclic phosphazene oligomer and 8.0 g of dried and purified o-dichlorobenzene at approx.
The mixture was placed in a 30 cc polymerization tube made of Pyrex glass, 100 mg of powdered urea was added, and the inside of the system was replaced with nitrogen gas, followed by vacuum treatment (10 ^-1 torr) and the tube sealed.
Next, this polymerization tube was left in an oven at 255°C for 5 hours, then taken out, cooled to room temperature, opened, and o
- The contents were emptied with dichlorobenzene.
After removing the o-dichlorobenzene insoluble matter, the liquid was poured into a large amount of petroleum ether to precipitate the resulting polymer, yielding 4 g of pale yellow rubbery polymer (conversion rate of starting material to polymer was 69%). I got some).
In addition, the petroleum ether layer was concentrated to obtain 0.1 g of an oily substance. As a result of GLC analysis, this oily substance was found to be
3PNC 0.01g, 4PNC 0.03g, 5PNC or more 0.05g, and others 0.01g. If this oily substance is all derived from the cyclic phosphazene oligomer as the starting material, the residual rate of each is 0.6% for 3PNC and 0.6% for 4PNC7.
%, 5PNC12.1%. Of the o-dichlorobenzene insoluble matter, hardly any gelled product of the phosphazene polymer was observed. The molecular weight of the obtained polymer was measured in the same manner as in Example 1, and the average molecular weight was 838,000.
In this case, the molecular weight is larger than that in Example 1, and it is thought that the solvent effect of o-dichlorobenzene appears. Example 3 Linear phosphazene oligomer obtained in Example 1
30cc of 6g, 4g trimmer and 100mg powdered urea
Pyrex glass polymerization tube, and after replacing the system with nitrogen gas, vacuum treatment (10 ^-2 torr)
and sealed the tube. Next, put this polymerized tube in an oven.
It was left at 255°C for 2 hours. During this period, the reaction system became homogeneous and highly viscous fluid. This was taken out from the oven, cooled to room temperature, opened, and the contents were taken out using monochlorobenzene. After removing the monochlorobenzene insoluble matter, the liquid was poured into a large amount of petroleum ether to precipitate the resulting polymer, yielding 9.3 g of a white rubbery polymer (the conversion rate of the starting material to the polymer was 93%). I got it. The petroleum ether layer was also concentrated, but no residue was obtained. This is considered to be due to almost quantitative conversion of trimer into polymer. Among the monochlorobenzene insoluble materials, 0.2 g of gelled material derived from the phosphazene polymer was found. The average molecular weight of the obtained polymer was 1,230,000. Example 4 Linear phosphazene oligomer obtained in Example 1
30cc of 1g, 9g trimmer and 100mg powdered urea
Pyrex glass polymerization tube, and after replacing the system with nitrogen gas, vacuum treatment (10 ^-2 torr)
and sealed the tube. Next, put this polymerized tube in an oven.
It was left at 255°C for 15 hours. This reaction system became homogeneous and highly viscous fluid. This was taken out from the oven, cooled to room temperature, opened, and the contents were taken out using monochlorobenzene. After removing the monochlorobenzene insoluble matter, the liquid was poured into a large amount of petroleum ether to precipitate the produced polymer, and 8 g of a pale yellow rubbery polymer (the conversion rate of the starting material to the polymer was 80%) was obtained. I got it. The amount of petroleum ether soluble material was 0.5 g, and most of it was trimer. Furthermore, the amount of gelled material derived from the phosphazene polymer in the monochlorobenzene insoluble matter was 0.5 g. The conversion rate of trimer to polymer was 94.4% (including gel), and the gelation rate of the starting material was 5%. The average molecular weight of the obtained polymer was 1,005,000. Example 5 Linear phosphazene oligomer obtained in Example 1
8g, 2g cyclic phosphazene oligomer with 5PNC or more
Then, 200 mg of powdered urea was charged into a 30 cc Pyrex glass polymerization tube and the tube was sealed. This polymerization tube was then left in an oven at 225°C for 20 hours. During this time, the reaction system appeared as a pale and highly viscous fluid. This was taken out from the oven, cooled to room temperature, opened, and the contents were taken out using monochlorobenzene. After removing the monochlorobenzene insoluble matter, the liquid was poured into a large amount of petroleum ether to precipitate the resulting polymer, yielding 7.5 g of a light and colored rubbery polymer.
(conversion of starting material to polymer is 75%). The petroleum ether layer was concentrated to recover 0.2 g of cyclic phosphazene oligomer. The gelation rate derived from the phosphazene polymer in the monochlorobenzene insoluble matter was 0.3 g. Gelation rate of starting material is 3%
The conversion rate of the cyclic phosphazene oligomer to the phosphazene polymer was 90%. The average molecular weight of the obtained polymer was 538,000.

Claims (1)

[Claims] 1. In a closed system, linear phosphazene oligomers are
A mixture of linear phosphazene oligomers and cyclic phosphazene oligomers containing up to 95% by weight was heated at -150 _to 350°C using a urea compound as a catalyst.
1. A method for producing a phosphazene polymer, which comprises heating to convert the phosphazene polymer into a high molecular weight phosphazene polymer. 2. The method for producing a phosphazene polymer according to claim 1, wherein the urea-based compound is urea, thiourea, polyurea or polythiourea. 3. The method for producing a phosphazene polymer according to claim 1, which uses one or more urea compounds as a catalyst.