JPS6320258B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new method for producing poly(organosilazanes). More specifically, the present invention relates to a method for producing poly(organosilazane) by irradiating organosilazane with plasma. In recent years, the development of so-called inorganic extreme materials having properties such as super heat resistance, super cold resistance, and radiation resistance has become active. On the other hand, the development of new types of silicon-based polymer materials for semiconductor and electronic materials such as ultra-integrated circuits and solar cells has long been desired. In these fields, metal sintered bodies such as metal oxides and amorphous metals are already known. In addition, silicone polymers having siloxane bonds as the main chain have been applied as inorganic polymers having heat resistance and cold resistance, but they have not yet reached the level where they can be called ultimate materials. So-called silazane polymers, which have silicon and nitrogen as their main chains, have been highly anticipated as new polymeric materials with the above-mentioned properties.
Polymerization of this type of compound is generally extremely difficult, and a method for synthesizing a polymer having a high molecular weight by a chemical method has not yet been developed. However, as a result of extensive research in an attempt to find an ultimate material with the above-mentioned characteristics, the present inventors discovered that poly(organosilazane) could be obtained by polymerizing organosilazane using plasma energy. It was about to be completed. That is, the present invention is based on the general formula (): (wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are hydrogen atom organic substituents or inorganic substituents) and/or a linear organosilazane represented by the general formula (): (In the formula, R ¹ , R ² and R ³ are the same as above, and n is an integer of 2 to 4.) This relates to a method for producing poly(organosilazane) by bringing the cyclic organosilazane represented by the formula into contact with plasma. be. General formula (): Linear organosilazane or general formula (): R ¹ , R ² , R ³ of the cyclic organosilazane represented by
R ⁴ , R ⁵ , R ⁶ and R ⁷ are a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group, an alkylimino group, a vinyl group, an allyl group; a carbon number 1
Examples include an arylalkyl group, an arylalkoxy group, or an aryl group having ~12 alkyl or alkoxy groups; or a halogen derivative group thereof; a halogen atom or a hydroxyl group. Examples of the organosilazane compound represented by the general formula () or () include hexamethylcyclotrisilazane, hexamethyldisilazane,
Examples include octamethylcyclotetrasilazane. Plasma polymerization has attracted attention in recent years, and research in both basic and applied fields has made remarkable progress. However, these conventional plasma polymerization methods mainly involve directly vaporizing the organic compound if it is in a gaseous state, or once vaporizing it if it is in a liquid state, and directly converting the reactants in the gaseous state into plasma under reduced pressure to form a polymer onto a carrier. The aim is to create a thin film. The polymer thin film obtained in this way is usually cross-linked every 2 to 3 molecules, and its structure is significantly different from that of the starting material due to the intense plasma chemical reaction. The physical and chemical properties that should be maintained have been lost. The production method of the present invention is essentially different from such conventional gas-phase plasma polymerization methods, and the main polymerization reaction takes place in a so-called condensed phase, which is either a liquid phase or a solid phase. In other words, in the conventional method, the gas phase itself in the plasma state is the reaction site for all reaction processes such as initiation, growth, termination, branching, and restart of polymer thin film formation, and therefore, not only the polymerization rate but also the produced polymer. It was impossible to adjust the structure and degree of branching. In contrast, the plasma-initiated polymerization method of the present invention considers plasma as one energy source for the polymerization reaction. Therefore, although the polymerization initiation reaction occurs in the gas phase in the plasma state, the subsequent polymerization growth reactions proceed in the liquid or solid phase of the organosilazane and are not in the plasma field itself. Therefore, in the present invention, it is possible to change and adjust the polymer structure and the reaction ratio of products, especially the high polymer network structure, the reaction ratio of branched polymers, and the reaction yield of oligomers, by changing the plasma irradiation conditions. It is possible. Furthermore, in the present invention, since the main process of the polymerization reaction proceeds in a condensed phase of liquid or solid phase, the produced polymer can be easily taken out in large quantities as a solid powder or solid lump substance, and it can be used as needed. Another major feature is that it can be processed or molded and filled together with a carrier. In addition, the poly(organosilazane) obtained in the present invention is chemically extremely stable and has acid resistance and alkali resistance, as well as excellent heat resistance, weather resistance, chemical resistance, and insulation properties. , its uses are extremely wide. Describing the manufacturing method of the present invention in detail, the plasma brought into contact with the organosilazane is preferably a stable one, particularly a low-temperature plasma generated by glow discharge. Such low-temperature plasmas are typically 0.0001
It can be generated with an applied power of 20 to 1000 Watts under reduced pressure of ~100 Torr. Alternatively, plasma may be generated using direct current or alternating current over a frequency range of 50 hertz to 30 megahertz. Commercially available radio frequency range, e.g. 90
A plasma generator with a kilohertz to 13.56 megahertz tuned circuit may be used to apply voltage through the electrodes. As the electrode, for example, a coiled electrode or a parallel plate electrode is used. Further, the electrode may be installed inside the reduced pressure gas (internal electrode method) or outside the reactor (external electrode method). When generating plasma, if the pressure is less than 0.0001 Torr, and if it is greater than 100 Torr, plasma will not be generated, and both are unfavorable. and the applied power is less than 20 watts,
If it is higher than 1000 watts, plasma generation will not occur, and both are unfavorable. Furthermore, if the AC current is less than 50 Hz and greater than 100 MHz, plasma will not be generated, and both are unfavorable. Regarding plasma generation, the vapor pressure of the organosilazane compound can be brought into a plasma generation state by temperature control, and the vapor can be used to generate plasma. In other words, the gas as a plasma generation source may be one using the gas molecules of organosilazane itself, or may be hydrogen, methane,
Any gas such as nitrogen, argon, or ethylene may be used. In any case, the shape of the polymerization reactor,
In order to obtain stable plasma, it is important to select the optimal gas pressure depending on the shape and spacing of the electrodes, the applied voltage, etc. In the present invention, the applied voltage used for plasma generation is usually in the range of 50 to 1000 volts, and the current can be appropriately selected in the range of 10 milliamps to 10 amperes. The organosilazane can be brought into contact with the plasma in a condensed phase state such as gas, liquid or solid, and the reaction will be a gas phase reaction, a liquid phase reaction or a solid phase reaction, respectively. The polymerization initiation reaction of organosilazane occurs in the gas phase, which is a plasma state, and the polymerization reaction proceeds by irradiating the solid or liquid raw material with plasma under reduced pressure while cooling or heating as necessary. In gas phase reactions, the produced polymer is inside the reactor,
It is usually produced attached to the inner wall of the reactor. Many of the resulting polymers are thin film-like high polymers that are insoluble in solvents, which is not preferable. Poly(organosilazane) can be obtained by heating and melting organosilazane in a liquid phase, if it is a liquid itself, or by heating and melting it if it is a solid. Poly(organosilazane) can also be obtained by dissolving organosilazane in a solvent such as benzene, toluene, or alcohol, whether it is a liquid or a solid. Alternatively, organosilazane may be immersed or suspended in the coexistence of other chemical reagents or polymers. However, in any case, it is necessary to appropriately control the vapor pressure in the reaction system by cooling or the like in order to continuously generate stable plasma. When organosilazane is irradiated with plasma in a solid state, if the reactant is in a solid state, it is left as is, or if it is a liquid, it is cooled and solidified before being irradiated with plasma. Even if the reactant is in a solid state at room temperature, it is often cooled as necessary to control its vapor pressure. Specifically, if the organosilazane is liquid or solid, it may be charged into a glass reactor, the pressure of this reactor may be reduced using a suitable pressure reducing means, and the organosilazane itself may be partially vaporized. After adjusting the gas pressure inside the reactor using other gases such as argon or argon, plasma is generated by applying a voltage between the electrodes and brought into contact with the plasma. At this time, the initiation of discharge may be facilitated by applying stimulation to the reactor using a high-frequency Tesler tube or the like. In the case of liquid phase or solid phase polymerization, the contact area with the plasma is an important factor in obtaining poly(organosilazane) in good yield, and it is important to renew the liquid or solid surface in contact with the plasma. is also one method. The structure of the poly(organosilazane) produced is also changed by these operations. Although the contact time with plasma is arbitrary, poly(organosilazane) may be generated immediately even after plasma irradiation for several tens of seconds. The yield of the poly(organosilazane) thus obtained varies depending on the number and type of organic substituents, but in general, the higher the applied voltage and the longer the contact time with plasma, the higher the yield. The poly(organosilazane) produced can be broadly classified into network high polymers,
These products are linear high polymers and oily oligomers, and the reaction ratio of these products is closely related to the plasma applied voltage, plasma irradiation time, and the shape of the reactants. In addition, after contact with plasma, the reaction system may be left as it is or in a medium for several days or more at room temperature or under heating to carry out so-called post-polymerization, thereby increasing the amount and molecular weight of poly(organosilazane) produced. can. That is, post-polymerization can be carried out directly after plasma irradiation, or can be carried out after being immersed in a suitable solvent or non-solvent. Next, the method of the present invention will be explained in detail with reference to Examples. Example 1 5 g of hexamethylcyclotrisilazane was placed in a 50 ml round bottom flask with a stopper.
The flask was connected to a glass vacuum apparatus with a reduced pressure of 0.1 Torr. It was then connected vertically to a 13.56 MHz commercially available plasma generator with a tuned circuit.
A round-bottomed flask is inserted between copper parallel electrode plates (50mm apart) that are 120mm wide, 90mm wide, and about 3mm thick. By applying electricity at an output of 100 watts while cooling the flask appropriately, glow discharge is started and plasma is generated. occurred. When the plasma disappeared as the vapor pressure increased, the temperature was appropriately cooled to about -50°C and plasma was generated again. . When the total plasma irradiation time reached 30 minutes, the reactant was taken out, immersed in a large amount of methanol, and stirred. This was then carried out to obtain the insoluble matter. The insoluble matter was dried under vacuum to obtain 1.25 g of a poly(organosilazane) high polymer as a white lump (yield: 25%). When the methanol solution was further dried under reduced pressure, 1.25 g of poly(organosilazane) high polymer was obtained as a colorless and transparent highly viscous oil (yield: 25%). Furthermore, when the methanol solution was dried under reduced pressure, 0.5 g of poly(organosilazane) oligomer was obtained as a colorless and transparent highly viscous oil (yield: 10%). The IR spectrum chart is shown in Figure 1. 1st
In the figure, (a) is the starting material, and (b) is the produced poly(organosilazane) high polymer. In (b), the absorption based on the vibration of Si—N—Si is 900 to 950 cm ^-1
In both (a) and (b ⁾ , absorption of Si—CH ₃ is observed at 800 cm ^-1 .
Furthermore, an X-ray diffraction photograph of the high polymer is shown in FIG. It can be seen from FIG. 2 that the high polymer is amorphous. Example 2 An experiment was conducted in the same manner as in Example 1, except that the total plasma irradiation time was 60 minutes. The results are shown in Table 1. Example 3 An experiment was conducted in the same manner as in Example 1, except that the output was 45 W and the total plasma irradiation time was 45 minutes. The results are shown in Table 1. Example 4 An experiment was conducted in the same manner as in Example 1 except that hexamethyldisilazane was used instead of hexamethylcyclotrisilazane. The results are shown in Table 1.
The IR spectrum chart is shown in Figure 3. In Figure 3, (a) is the starting material, (b) is poly(organosilazane)
It is made of high polymer. Moreover, the X-ray diffraction pattern of the high polymer is shown in FIG. It can be seen from FIG. 5 that the polymer is amorphous. Example 5 An experiment was conducted in the same manner as in Example 4 except that the total plasma irradiation time was 30 minutes. The results are shown in Table 1. Example 6 An experiment was conducted in the same manner as in Example 4, except that the output was 45 W and the total plasma irradiation time was 45 minutes. The results are shown in Table 1.

[Table] Example 7 Put 10 g of octamethylcyclotetrasilazane into a 100 ml round bottom flask with a stopper.
The flask was connected to a glass vacuum apparatus with a reduced pressure of 0.05 torr. Using the same plasma generator and plasma reactor as in Example 1, glow discharge was started at an output of 80 W while the flask was appropriately cooled, and plasma was generated and irradiated to effect polymerization. When the total plasma irradiation time reached 100 minutes, the reactants were taken out and treated in the same manner as in Example 1. As a result, 2.5 g (yield 25%) of methanol-insoluble milky white poly(organosilazane) high polymer,
and highly viscous oily poly(organosilazane)
1.2 g of oligomer was obtained (yield 12%). Example 8 Using 10g of hexamethyltrisilazane, output
The experiment was carried out under the same conditions as in Example 1 except that the plasma irradiation time was 120 Watts and the total plasma irradiation time was 40 minutes, and then the sample was left in a constant temperature bath at 80° C. for 40 hours to carry out post-polymerization. Thereafter, the same treatment as in Example 1 was carried out to obtain 4.5 g (yield 45%) of a methanol-insoluble milky white poly(organosilazane) high polymer and 1 g of a highly viscous oily poly(organosilazane) oligomer.
(yield 10%). Example 9 White poly(organosilazane) obtained in Example 1
5g was placed in a platinum crucible and heated to 1000 ml under a nitrogen atmosphere.
When heat treated at ℃ for 24 hours, a black powdery substance was obtained. The first IR spectrum chart of this compound
It is indicated by C in the figure. It can be seen that the compound obtained from C in FIG. 1 is a completely mineralized polymer. This mineralized polymer was found to be extremely stable even at 1200°C, and was found to be an extremely heat-resistant inorganic polymer. An X-ray diffraction photograph of the inorganic polymer is shown in FIG. It can be seen from FIG. 4 that the inorganic polymer is amorphous. Example 10 5 g of the white poly(organosilazane) obtained in Example 4 was placed in a platinum crucible and an experiment was conducted under the same conditions as in Example 9, resulting in a black powder. The IR spectrum chart of this compound is shown in Figure 3 (c).
Indicated by From FIG. 3(c), it can be seen that the obtained compound is a completely mineralized polymer. This mineralized polymer was found to be extremely stable even at 1200°C, and was found to be an extremely heat-resistant inorganic polymer. An X-ray diffraction chart of the inorganic polymer is shown in FIG. It can be seen from FIG. 5 that the inorganic polymer is amorphous.

[Brief explanation of the drawing]

FIG. 1 is an IR spectrum chart of the starting material and the produced high polymer of Example 1 and the produced inorganic high polymer of Example 9 in the present invention, FIG. 2 is an X-ray diffraction photograph of the produced high polymer of Example 1, Figure 3 is an IR spectrum chart of the starting material and high polymer produced in Example 3 and the inorganic polymer produced in Example 10, Figure 4 is an X-ray diffraction photograph of the inorganic polymer produced in Example 9, and Figure 5. is an X-ray diffraction chart of the inorganic polymer produced in Example 10.

Claims (1)

[Claims] 1 General formula (): (wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are each a hydrogen atom, an organic substituent or an inorganic substituent) and/or General formula (): (In the formula, R ¹ , R ² , R ³ are the same as above, n is 2 to
1. A method for producing poly(organosilazane), which comprises contacting a cyclic organosilazane (which is an integer of 4) with plasma. 2 R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ² and R ⁷ are each a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group, an alkylimino group, a vinyl group, an allyl group; 2. The method according to claim 1, which is an arylalkyl group, an arylalkoxy group, or an aryl group having an alkyl group or an alkoxy group having 1 to 12 carbon atoms; or a halogen derivative group thereof. 3. The manufacturing method according to claim 1, wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ is each a halogen atom or a hydroxyl group. 4. The manufacturing method according to claim 1, wherein the organosilazane is in a gas phase, liquid phase, or solid phase. 5. The manufacturing method according to claim 1, characterized in that the organosilazane is brought into contact with plasma in a condensed phase state such as liquid or solid. 6. The method according to claim 1, wherein the vapor pressure of the organosilazane is brought into a plasma generation state by temperature control, and the vapor is used to generate plasma. 7. The production method according to claim 1, wherein the reaction system is left as it is or in a medium at room temperature or under heating after contacting with the plasma. 8. The manufacturing method according to claim 1, characterized in that plasma is generated under reduced pressure of 0.0001 to 100 torr and with a low applied power of 20 to 1000 watts. 9 Plasma at 50 Hz or higher with DC or AC
2. The manufacturing method according to claim 1, wherein the generation is performed over a frequency range of 100 MHz.