JPH03243627A - Production of high-molecular weight polyorganosiloxane - Google Patents

Abstract

PURPOSE:To industrially advantageously obtain the subject polyorganosiloxane by polymerizing a specific plydiorganosiloxane in the presence of an alkaline catalyst, deactivating the catalyst and purifying in a specific condition. CONSTITUTION:100pts.wt. at least a species of polyorganosiloxane selected from compounds expressed by formula I (R is monofunctional hydrocarbon group; y is 2-100) and formula II (x is integer of >=3) is polymerized preferably at 80-110 deg.C using an alkali catalyst such as a quaternary hydroxyl phosphonium compound preferably in an amount of 0.015-0.030 pts.wt. and CO2 is introduced into the reaction tank, then made to stagnate (preferably in a condition at 10-110 deg.C and 1-10 atm) to deactivate the catalyst, thus a carrier fluid (preferably CO2) is continuously introduced and discharged to purify in its supercritical state or quasicritical state to afford the aimed polyorganosiloxane.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a high molecular weight polyorganosiloxane by polymerizing an organosiloxane oligomer in the presence of an alkali catalyst.

(Prior art) As a method for producing high molecular weight polyorganosiloxane, a method of polymerizing organosiloxane oligomers in the presence of an alkali catalyst is conventionally known (for example, Japanese Patent Publication No. 32-39
Publication No. 92).

Certain alkaline catalysts exhibit catalytic activity under relatively low temperature conditions; for example, in the case of quaternary phosphonium compounds, polymerization proceeds rapidly at reaction temperatures of 80-110°C. Therefore, catalyst deactivation after polymerization reduces the reaction system to 130'
This is carried out by maintaining the catalyst at a relatively high temperature of C or higher, preferably 150 C or higher, for a sufficient period of time to advance thermal decomposition of the catalyst.

The catalyst is also deactivated by reducing the catalytic action by forming a salt through neutralizing solvent treatment or contact treatment with carbon dioxide gas.

Further, the obtained high molecular weight organopolysiloxane is generally purified by removing low molecular weight organopolysiloxane and unreacted organosiloxane oligomers by means such as distillation.

(Problems to be Solved by the Invention) However, in the above-mentioned conventionally known method for producing high molecular weight organopolysiloxane, it is necessary to maintain the reaction system at a high temperature of 150°C or higher, for example, to deactivate the catalyst. In the distillation and purification steps, it is necessary to maintain the temperature at an even higher temperature, which requires a large amount of thermal energy, which is extremely disadvantageous from a thermoeconomic standpoint.

Furthermore, in the production of thermally unstable high molecular weight polyorganosiloxanes, the above-mentioned catalyst deactivation and temperature raising steps in the distillation purification step are extremely undesirable in terms of polymer stabilization.

Further, when the catalyst is deactivated by neutralizing solvent treatment or contact treatment with carbon dioxide gas, the treatment time is long, which is also disadvantageous in terms of production efficiency.

Furthermore, in the conventionally known methods, catalyst deactivation is not carried out sufficiently effectively, resulting in cracking of the high-molecular weight polymer, which results in a decrease in polymer yield.

(Means for Solving the Problems) The present invention performs catalyst deactivation treatment after performing a polymerization reaction by retaining carbon dioxide (Co□) in the reaction system, and performs a subsequent polymer purification treatment. by the extremely simple means of passing a carrier fluid through the reaction system under constant temperature and pressure conditions.
This method succeeded in effectively performing catalyst deactivation treatment and polymer purification treatment without consuming a large amount of thermal energy.

That is, according to the present invention, (a) a polydiorganosiloxane represented by the following formula N), in which R is a monovalent hydrocarbon group, and y is an integer from 2 to 100, and (b) the following ( using at least one polydiorganosiloxane selected from the following: n) Formula, HO(RzSiO) In a method for producing high molecular weight polyorganosiloxane by polymerizing in the presence of an alkali catalyst, after carrying out a prescribed polymerization reaction, carbon dioxide is retained in the reaction system to deactivate the catalyst, and then the catalyst is deactivated. It is characterized by deactivating the catalyst and purifying the produced polymer by passing a carrier fluid through the reaction system under conditions where at least one of temperature and pressure is equal to or higher than a critical value of the carrier fluid. A manufacturing method is provided.

In the production method of the present invention, the starting material is a cyclic diorganosiloxane oligomer represented by the formula [I], i.e., HO An acyclic diorganosiloxane oligomer represented by (RzSiO)xH(n ) is used.These cyclic and acyclic diorganosiloxanes may be used alone or in the form of a mixture can.

In the general formulas [I] and [■], y is 2 to 100
, X is an integer of 3 or more, especially IO or less, and R is a monovalent hydrocarbon group, preferably a monovalent hydrocarbon group with 6 or less carbon atoms, such as methyl, ethyl, propyl, phenyl,
It represents multiple groups such as vinyl, allyl, aryl, etc., and each R may be a mutually different group.

The alkali catalyst used in the present invention is one that causes the polymerization of the cyclic or acyclic diorganosiloxane oligomer at a relatively low temperature (for example, below 130°C), and easily decomposes and becomes active when heated. Any conventionally known alkali catalyst of the type that loses the
H, etc.], quaternary ammonium hydroxide compounds ((CHz)
4NOH, etc.). These are generally the starting materials diorganosiloxane oligomers lO
It is used in a proportion of o, oi to 0.10 parts by weight, preferably 0.015 to 0.030 parts by weight per part by weight of O.

In the present invention, the diorganosiloxane oligomer described above is charged into a suitable reaction tank, and after an alkali catalyst is added, the polymerization reaction is sufficiently carried out.

The polymerization reaction is carried out under relatively low temperature conditions, for example, in a temperature range from room temperature to 130°C, preferably from 80 to 110"C. If the temperature is lower than room temperature, the catalyst activity will not be effectively expressed. , the polymerization reaction does not proceed quickly, and 130
When the temperature exceeds .degree. C., it is not preferable because there is a risk of decomposition of the catalyst or cranking of the produced high molecular weight organopolysiloxane.

The polymerization time varies depending on the charging temperature of the diorganosiloxane oligomer, the polymerization temperature, etc., but if -C is 0.5
~24 hours.

In the present invention, after the polymerization is completed, carbon dioxide is poured into the reaction tank and retained, and the catalyst is deactivated by bringing the carbon dioxide into contact with the reaction system and converting the catalyst into carbonate. Let's do it. By deactivating the catalyst, the polymerization reaction is stopped and the decomposition of the produced high molecular weight polymer is suppressed.

Carbon dioxide (hereinafter referred to as CO) is retained in the reaction tank.

), all of the gas, liquid, temperature and pressure are CO
It may be in either a supercritical state where the temperature or pressure is above the critical value, or a subcritical state where either the temperature or the pressure is above the critical value.

For example, when a quaternary phosphonium hydroxide salt is used as a catalyst, the reaction between Cog and a catalyst is expressed by the following formula, R4POI(+ COz FI4PHCO
represented by x (wherein R represents a monovalent hydrocarbon group),
Generates stable carbonates at relatively low temperatures such as room temperature. Catalyst deactivation is thus carried out by converting the alkaline catalyst to carbonate.

The retention conditions for CO2 are closer to room temperature and lower pressure, which is more advantageous.
For example, the temperature is preferably in the range of 0 to 130"C, especially 10 to 110"C, and the pressure is preferably in the range of 1 to 1100at, especially 1 to 1L.
A range of Oatm is preferred. Further, the residence time varies depending on the temperature and pressure, but is usually in the range of about 0.5 to 5 hours.

Furthermore, in the present invention, it is important to retain CO2 in this catalyst deactivation step. That is, when CO2 is passed through, unreacted diorganosiloxane oligomers and low molecular weight polysiloxanes flow out together with CO□ before the catalyst is deactivated, which upsets the balance of the equilibration reaction. -Cracking of the polysiloxane occurs.

In order to effectively perform the catalyst deactivation process described above, members such as valves for introducing and discharging CO2 are provided at the upper and/or lower part of the reaction tank, and furthermore, the alkali catalyst and CO□
It is desirable to provide suitable forced convection means to increase the chances of contact with

In addition, catalyst deactivation using a carrier fluid is suitably carried out, for example, by filling a reaction tank with CO□ and leaving it at the temperature and pressure as described above.
CO□ is sequentially introduced into the reaction tank, and after being saturated at a predetermined pressure,
This can also be carried out by sequentially causing Ico□ to flow out from the reaction tank in @ amounts and repeating this operation.

According to the present invention, unreacted organopolysiloxane oligomers are then removed by continuously flowing the carrier fluid into the reaction vessel and continuously discharging it in the above-mentioned supercritical state or subcritical state. , the low molecular weight organopolysiloxane and the carbonate of the alkali catalyst generated in the catalyst deactivation step described above are captured and removed, and the produced high molecular weight organopolysiloxane is effectively purified.

The carrier fluid used in the present invention preferably has a critical temperature near room temperature, and examples of such materials include the following.

Critical temperature Critical pressure Carbon dioxide (COz) 31.1'C73 atm Nitrous oxide (NzO) 36.5'C71,7 atm
Ethane (C2H6) 32.4°C48,3a
tm ethylene (c2u,) 9.9°C50,5
atm In the present invention, in the catalyst deactivation step B, CO
Considering that 2 is used, it is most preferred to use CO□ as the carrier fluid.

The purification conditions vary depending on the type of carrier fluid, but generally the pressure is 50 to 500 atn+, especially 1
The range is preferably from 00 to 200 atll. The higher the pressure, the higher the amount of purification per unit time, but as mentioned above, as mentioned above, a portion of the produced high molecular weight organopolysiloxane is also captured and removed by the carrier fluid, reducing the yield. This is not preferable because it causes deterioration. In addition, the temperature is generally in the range of O'C to 200°C, but if the temperature is higher than necessary, the amount of purification per unit time will decrease (because the carrying capacity of the carrier fluid is inversely proportional to the temperature). In order to prevent a decrease in the amount and decomposition of the thermally unstable high molecular weight organopolysiloxane, and to minimize the amount of required thermal energy, the range should be from above the critical temperature to below 100°C. is the most suitable.

Note that the purification rate can be easily controlled by appropriately selecting the supply amount of the carrier fluid.

The carrier fluid containing unreacted organosiloxane oligomers and low molecular weight organopolysiloxanes flowing out of the reaction vessel is collected and the solubility of the carrier fluid is reduced by reducing the pressure and/or increasing the temperature. These components are separated and recovered. The recovered unreacted organopolysiloxane oligomer and low molecular weight organopolysiloxane can be used again to produce a high molecular weight organopolysiloxane.

The carrier fluid can also be recovered and reused in gaseous or liquid form.

(Effects of the Invention) According to the present invention, as is clear from the examples described later,
Everything from polymerization reaction to polymer purification process is 110
It can be carried out at a temperature of 100° C. or lower, particularly 100° C. or lower, and the amount of thermal energy can be effectively reduced, making it extremely useful industrially.

Further, the catalyst is effectively deactivated, the decomposition of the produced polymer can be effectively avoided, and a high molecular weight organopolysiloxane can be obtained in high yield.

(Example) The present invention will be explained with the following example. In the following examples, it is assumed that sufficient stirring and mixing is always carried out in the reaction tank.

As a starting material, a cyclic dimethylsiloxane oligomer represented by the following formula was used.

500 g of the above-mentioned cyclic dimethylsiloxane oligomer was placed in a reaction tank No. 41, and 3ooppm of tetrabutylphosphonium hydroxide was added to the oligomer as an alkali catalyst, and 50ppm of 1,3 divinyltetramethyldisiloxane was added to the oligomer. Added.

The reaction tank temperature was maintained at a constant temperature of 100"C, and the polymerization reaction was carried out for 2 hours. Next, while maintaining the reaction tank temperature, carbon dioxide gas was poured in, and the reaction tank pressure was increased to 1at.
The catalyst was deactivated by bringing it to a saturated state and leaving it for 1 hour. Next, carbon dioxide gas was continuously flowed in while the reactor temperature remained unchanged, and the reactor pressure was increased to 200 at.
While maintaining the temperature at t*, carbon dioxide gas was continuously allowed to flow out from the other port for 60 minutes.

The results obtained at this time, such as the yield of the polymer and the average molecular weight of the purified polymer, are shown in Table 1.

In the purification process using carbon dioxide gas, the reaction tank pressure was set to 50a tI.
Il (Example 2), 100 atm (Example 3)
), 300 atm (Example 4), a high molecular weight organopolysiloxane was produced in the same manner as in Example 1.

The results are shown in Table 1.

A polymerization reaction was carried out in the same manner as in Example 1. After that, the reaction tank pressure was increased to 50a tm with carbon dioxide gas while keeping the reaction tank temperature the same.
The pressure was increased to 100% to deactivate the catalyst.

Subsequently, carbon dioxide gas was continuously flowed in while keeping the reaction tank temperature as it was, and in Example 5, the temperature was maintained at 50 a tm.
In Example 6, the pressure was increased to 200 atm and carbon dioxide gas was continuously flowed out from the other port for 60 minutes.

The results are shown in Table 2.

The temperature of the main manufacturing process was consistently 65°C (Example 7), 80°
Production was carried out in the same manner as in Example 1, except for carrying out C (Example 8). The results are shown in Table 2.

Closed school Kurakami A polymerization reaction was carried out in the same manner as in Example 1.

Next, the reaction temperature was raised to 160°C and left to stand for 1 hour to deactivate the catalyst.

Subsequently, the reaction tank temperature was set to 200°C, and the reaction tank pressure was set to 1.
The pressure was reduced to orr, and distillation purification was performed. The results are shown in Table 3.

comparison group work A polymerization reaction was carried out in the same manner as in Example 1.

Next, after the reaction tank temperature was lowered to 50''C or lower, 50 ppm of triethylamine (neutralizing agent) was added, and the catalyst was deactivated by leaving it for 1 hour.

Subsequently, distillation purification was performed under the same conditions as in Comparative Example 1. The results are shown in Table 3.

Table 1 Table 2

Claims (1)

[Claims] (1) (a) A polydiorganosiloxane represented by the following formula, ▲ Numerical formula, chemical formula, table, etc.▼ In the formula, R is a monovalent hydrocarbon group, and y is an integer from 2 to 100, and (b) Using at least one polydiorganosiloxane selected from the following formula, HO(R_2SiO)_xH, where R is the same as above and x is an integer of 3 or more, In a method for producing high molecular weight polyorganosiloxane by polymerizing in the presence of an alkali catalyst, after carrying out a prescribed polymerization reaction, carbon dioxide is retained in the reaction system to deactivate the catalyst, and then the catalyst is deactivated. A production method characterized in that a produced polymer is purified by passing a carrier fluid through a reaction system under conditions such that at least one of temperature and pressure is equal to or higher than a critical value of the carrier fluid.