RU2563253C1 - Siloxane block-copolymers containing methyl (hexafluoroalkyl) siloxane links - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention discloses siloxane block-copolymers which contain methyl(hexafluoroalkyl)siloxane links of general formula [A]{(R_f(CH₃)SiO)_n((CH₃)₂SiO)_m}_l [A], where n=100-30, m=0-70, n+m=100, l=1-15, k=25-125, q=5-100, where R_f and [A] are given below, for heat- and fuel-resistant materials. R_f:

[A]:

.

EFFECT: disclosed siloxane copolymers have high heat resistance and vulcanisates thereof have high fuel resistance.

1 tbl, 5 ex

Description

The invention relates to new macromolecular compounds, namely, block copolymers containing siloxane flexible blocks and rigid blocks, which can be phenylsilsesquioxane or silicate. These compounds can be used as the basis for thermo-, fuel-, oil-and-petrol-resistant materials intended for use in automotive, aviation and space technology.

Known polyphenylsilsesesquioxane-polymethyl (3,3,3-trifluoropropyl) siloxane block copolymer obtained by heterofunctional polycondensation of polyphenylsilsesquioxane and polymethyl (3,3,3-trifluoropropyl) siloxane in an organic solvent in the presence of diethylhydroxyl amoxysilane massyl ° C and polydiorganosiloxane from 10:90 to 50:50 (RF patent No. 2439092 C08G 77/06, C08G 77/38, C08G 77/44 with prior. from 06.25.2010).

The swelling of the vulcanizates of such a polymer in TS-1 rocket fuel for 24 hours is 5.9-6.2% (wt).

However, the heat resistance of this polymer is low, the onset of decomposition occurs at 223 ° C.

Known poly (methyl hexafluoroalkyl) siloxane (Pat RF 2078097 C08G 77/24, with prior, from 06.27.1995) of the General formula:

where R _f :

Obtained by copolymerization of 1,3,5-trimethyl-1,3,5-tris- (hexafluoroalkyl) cyclotrisiloxane and 1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane in a molar ratio of 1: 0.0015-0.009 at 100 -120 ° C in a stream of nitrogen in the presence of a disodium hydroxypolymethyl-3,3,3-trifluoropropylsiloxane catalyst.

The polymer has high heat resistance, 13% weight loss occurs at 430 ° C, but its fuel resistance is insufficient: the swelling in the TS-1 rocket fuel for 14 hours is 14%.

The closest analogue to the achieved result is polydimethylmethyl (hexafluoroalkyl) siloxane of the formula

where R _f :

n = 99-30, m = 1-70, l = 3-15 (Application No. 2013106048, 2013. C08G 77/24 with priority from 02/12/2013)

The polymer has a fairly high fuel and heat resistance, 13% weight loss occurs at 430 ° C, the swelling of its vulcanizate in TS-1 rocket fuel within 6 hours is 6-10%.

However, the temperature range of its operation does not exceed 430 ° C, which nevertheless limits the scope of its use.

The objective of the invention is the creation of siloxane copolymers with high heat resistance, the vulcanizates of which have high fuel resistance.

This goal is achieved by the synthesis of siloxane block copolymers of the general formula:

[A] {(R ^f (CH ₃ ) SiO) _n ((CH ₃ ) ₂ SiO) _m } _l [A]

where R _f :

n = 100-30, m = 0-70, n + m = 100, l = 1-15,

where [A]:

k = 25-125, q = 5-100.

These block copolymers are obtained by hydrolytic polycondensation of low molecular weight siloxanes containing methyl (hexafluoroalkyl) siloxane units, with phenyl trichlorosilane or with a mixture of tetraethoxysilane with methyl (hexafluoroalkyl) dichlorosilane (in a ratio of 1 / 2.0 ÷ 2.3), followed by condensation by hydrolysis solvent.

The essence of the invention is as follows:

At the first stage, a solution of siloxane containing methyl (hexafluoroalkyl) siloxane units and pyridine in butyl acetate is added, with stirring and ambient temperature, to a solution of phenyltrichlorosilane or a mixture of tetraethoxysilane with methyl (hexafluoroalkyl) dichlorosilane (in the ratio 1 / 2.0 ÷ 2.3) in butyl acetate for 0.5-1.5 hours. After the feed is complete, the reaction mixture is stirred at a temperature of 100-130 ° C for 1-1.5 hours, then cooled to ambient temperature.

Then, a solution of potassium hydroxide and triethylbenzylammonium chloride in water is separately prepared and, after cooling to ambient temperature, the solution of the siloxanes obtained above is supplied at such a rate that the temperature of the reaction mixture does not exceed 40 ° C, and after feeding it is stirred for 1.5-2 hours at ambient temperature and left to delaminate. Then the lower aqueous layer is separated, and the organic layer is washed first with a solution of hydrochloric acid, and then with water until the washings are neutral.

The block copolymer is isolated from the solution by distillation of butyl acetate with steam, then it is dried for 1-3 hours at 110-140 ° C.

The starting siloxane containing methyl (hexafluoroalkyl) siloxane units is prepared according to a known method described in RF application No. 2013106048.

The starting methyl (hexafluoroalkyl) dichlorosilane is prepared according to the known method described in RF patent No. 2101286, 1997.

The number average molecular weight of the polymers is determined by gel chromatography. The structure and composition of the links are confirmed by ¹ H and ²⁹ Si NMR.

Heat resistance is determined by thermogravimetric analysis on a GTA-6000 device from Perkin Elmer. The weight of the samples is 12-20 mg, the heating rate is 10 deg / min in the range from 40 to 600 ° C.

The fuel resistance of vulcanizates based on the obtained polymers is determined by the change in mass according to GOST 9.030. The samples are kept in TS-1 rocket fuel at a temperature of (70 + 2) ° C for (72.00 + 0.25) hours.

The invention is illustrated by the following examples.

Example 1

A solution of 120 g of polymethyl (hexafluoroalkyl) siloxane (n = 100; m = 0; l = 10) and 5 ml of pyridine in 350 ml of butyl acetate are poured with stirring and ambient temperature to a solution of 213 ml (284 g) of phenyltrichlorosilane in 350 ml of butyl acetate in within 1.5 hours. After the feed is complete, the reaction mixture is kept at 100 ° C and stirring for 1 hour, then cooled to ambient temperature.

Separately, 78.4 g of potassium hydroxide and 0.9 g of triethylbenzylammonium chloride are dissolved in 315 ml of water and cooled to ambient temperature. The siloxane solution obtained above is supplied to the aqueous alkali solution at such a rate that the temperature of the reaction mixture does not exceed 40 ° C, after the feed is completed, it is stirred for 1.5 hours at ambient temperature and left to delaminate. Then the lower aqueous layer is separated, and the organic layer is washed first with a solution of 100 ml conc. hydrochloric acid in 300 ml of water, and then with water (in 300 ml portions) until the washings are neutral (4 washes).

The block copolymer is isolated from the solution by distillation of butyl acetate with steam, then dried for 2 hours at 120 ° C.

¹ H and ²⁹ Si NMR spectra and gel chromatograms confirm the structure of the siloxane block copolymer, where n = 100; m is 0; l = 10; k = 25.

Example 2

According to the method described in example 1, a solution of 60 g of polydimethylmethyl (hexafluoroalkyl) siloxane (n = 30; m = 70; l = 15) and 3 ml of pyridine in 350 ml of butyl acetate are poured with stirring at ambient temperature to a solution of 320 ml (425 g) phenyltrichlorosilane in 350 ml of butyl acetate for 1.0 hour. After the feed is complete, the reaction mixture is kept at a temperature of 130 ° C and stirring for 1.5 hours, then cooled to ambient temperature.

Separately, 40 g of potassium hydroxide and 0.8 g of triethylbenzylammonium chloride are dissolved in 315 ml of water and cooled to ambient temperature. The siloxane solution obtained above is supplied to the aqueous alkali solution at such a rate that the temperature of the reaction mixture does not exceed 40 ° C, at the end of the feed, it is stirred for 2 hours at ambient temperature and left to delaminate. Then the lower aqueous layer is separated, and the organic layer is washed first with a solution of 100 ml conc. hydrochloric acid in 300 ml of water, and then with water (in 300 ml portions) until the washings are neutral (5 washes).

The block copolymer is isolated from the solution by distillation of butyl acetate with steam, then dried for 1 hour at 140 ° C.

¹ H and ²⁹ NMR spectra and gel chromatograms confirm the structure of the siloxane block copolymer, where n = 30; m = 70; l is 15; k = 80.

Example 3

According to the method described in example 1, a solution of 12 g of polydimethylmethyl (hexafluoroalkyl) siloxane (n = 50; m = 50; l = 1) and 0.5 ml of pyridine in 35 ml of butyl acetate are poured with stirring at ambient temperature to a solution of 64 ml (85 g) phenyltrichlorosilane in 100 ml of butyl acetate for 0.5 hours. After feeding, the reaction mixture was kept at a temperature of 120 ° C and stirring for 1 hour, then cooled to ambient temperature.

Separately, in 32 ml of water, 7.8 g of potassium hydroxide and 0.1 g of triethylbenzylammonium chloride are dissolved and cooled to ambient temperature. The siloxane solution obtained above is supplied to the aqueous alkali solution at such a rate that the temperature of the reaction mixture does not exceed 40 ° C, after the feed is completed, it is stirred for 1.5 hours at ambient temperature and left to delaminate. Then the lower aqueous layer is separated, and the organic layer is washed first with a solution of 10 ml conc. hydrochloric acid in 30 ml of water, and then with water (in 30 ml portions) until the washings are neutral (4 washes).

The block copolymer is isolated from the solution by distillation of butyl acetate with steam, then dried for 3 hours at 110 ° C.

¹ H and ²⁹ Si NMR spectra and gel chromatograms confirm the structure of the siloxane block copolymer, where n = 50; m is 50; l is 1; k = 125.

Example 4

According to the method described in example 1, a solution of 12 g of polymethyl (hexafluoroalkyl) siloxane (n = 100; m = 0; l = 12) and 0.5 ml of pyridine in 50 ml of butyl acetate are poured with stirring at ambient temperature to a solution of 47 ml tetraethoxysilane and 100 ml of methyl (hexafluoroalkyl) dichlorosilane (1/2 ratio) in 250 ml of butyl acetate for 0.5 hour. After the feed is complete, the reaction mixture is maintained at a temperature of 110 ° C and stirring for 1 hour, then cooled to ambient temperature.

Separately, 8.0 g of potassium hydroxide and 0.1 g of triethylbenzylammonium chloride are dissolved in 50 ml of water and cooled to ambient temperature. The siloxane solution obtained above is supplied to the aqueous alkali solution at such a rate that the temperature of the reaction mixture does not exceed 40 ° C, after the feed is completed, it is stirred for 1.5 hours at ambient temperature and left to delaminate. Then the lower aqueous layer is separated, and the organic layer is washed first with a solution of 10 ml conc. hydrochloric acid in 30 ml of water, and then with water (in 30 ml portions) until the washings are neutral (5 washes).

The block copolymer is isolated from the solution by distillation of butyl acetate with steam, then dried for 2 hours at 130 ° C.

¹ H and ²⁹ Si NMR spectra and gel chromatograms confirm the structure of the siloxane block copolymer, where n = 100; m is 0; l is 12; q = 100.

Example 5

According to the method described in example 1, a solution of 120 g of polymethyl (hexafluoroalkyl) siloxane (n = 50; m = 50; l = 7) and 0.5 ml of pyridine in 35 ml of butyl acetate are poured with stirring and ambient temperature to a solution of 94 ml tetraethoxysilane and 260 ml of methyl (hexafluoroalkyl) dichlorosilane (1 / 2.3 ratio) in 400 ml of butyl acetate for 0.5 hour. After the feed is complete, the reaction mixture is maintained at a temperature of 110 ° C and stirring for 1 hour, then cooled to ambient temperature.

Separately, in 32 ml of water, 7.8 g of potassium hydroxide and 0.1 g of triethylbenzylammonium chloride are dissolved and cooled to ambient temperature. The siloxane solution obtained above is supplied to the aqueous alkali solution at such a rate that the temperature of the reaction mixture does not exceed 40 ° C, at the end of the feed, it is stirred for 2 hours at ambient temperature and left to delaminate. Then the lower aqueous layer is separated, and the organic layer is washed first with a solution of 10 ml conc. hydrochloric acid in 30 ml of water, and then with water (in 30 ml portions) until the washings are neutral (4 washes).

The block copolymer is isolated from the solution by distillation of butyl acetate with steam, then dried for 2 hours at 130 ° C.

¹ H and ²⁹ Si NMR spectra and gel chromatograms confirm the structure of the siloxane block copolymer, where n = 50; m is 50; l is 7; q = 5.

A prototype example was also reproduced.

Of all the obtained block copolymers (examples 1-5 and the prototype), vulcanizates were prepared according to a standard formulation and tested for resistance in TC-1 rocket fuel.

The properties of the obtained polymers and their vulcanizates are shown in table 1.

Thus, as can be seen from the data given in the table, vulcanizates based on the obtained block copolymers along with high fuel resistance have improved heat resistance.

Claims (1)

Siloxane block copolymers containing methyl (hexafluoroalkyl) siloxane units, of the general formula:
[A] {(R _f (CH ₃ ) SiO) _n ((CH ₃ ) ₂ SiO) _m } _l [A]
where R _f :

n = 100-30, m = 0-70, n + m = 100, l = 1-15,
where [A]:

k = 25-125, q = 5-100
for heat and fuel resistant materials.