RU2073019C1 - Process for preparing modified 1,4-polybutadiene containing dichlorocyclopropane groups - Google Patents

Abstract

FIELD: synthetic rubber industry. SUBSTANCE: reaction of 1,4- polybutadiene in hydrocarbon solvent by portionwise addition of aqueous chloroform solution with phase- transfer catalyst dissolved terein to give hydrocarbon solution of 1.4-polybutadiene at molar ratio of 1,4- polybutadiene to chloroform to alkaline metal hydroxide to phase-transfer catalyst of 1:(1-3): (0.3-2):(0.002- 0.2), respectively. EFFECT: chlorine containing rubber having greater efficiency life.

Description

 The invention relates to a technology for producing modified 1,4-polybutadiene and can be used in the synthetic rubber industry, and the resulting polymer can be used to produce oil-benzo-ozone-frost-resistant rubber products, in particular sealing parts, conveyor belts, sleeves, rubberized fabrics etc.

A known method of producing a modified 1,4-polybutadiene (1,4-PB) containing dichlorocyclopropane (DHCP) groups, the interaction of a hydrocarbon solution of cis-1,4-polybutadiene with chloroform and an aqueous solution of an alkali metal hydroxide in the presence of phase transfer catalyst (CMP) (Japanese Acc. Application VI-13727, C O8 D 8/18, 1989). The process is carried out by supplying a solution of 1,4-PB (cis-1,4-units of 97.5%) in toluene (benzene, dichloromethane, chloroform) an aqueous solution of alkali metal hydroxide (NaOH, KOH) with a concentration of 30-65 wt. . and KMP, for which quaternary ammonium or phosphonium salts are used, as well as crown ethers (triethylbenzylammonium chloride (TEBAH), tetraphosphonium bromide, 18-kpaun-6, etc.). After emulsification at 30-60 ^o C for 10 min, 1.5-5 hours. The molar ratio of reagents 1,4-PB: CHCl ₃ : OH: KMP is 1: (0.6-9) :( 0.6- 5.2): (0.001-0.05).

n=k+m
k/n содержание ДХЦП-групп.The modification process is described by the scheme

n = k + m
k / n is the content of DHCP groups.

 The content of DHCP groups (degree of modification) is proportional to the amount of alkali metal hydroxide and chloroform. One of the main process parameters is the degree of conversion of the supplied reagents to the final product. Due to the fact that chloroform is usually taken in excess, and in addition, the remaining chloroform can be returned to the process, the degree of conversion of an alkali metal hydroxide, which is also lost irrevocably, is the main indicator of the effectiveness of the process for producing modified 1,4-PB unused alkali metal hydroxide in the main reaction is consumed in adverse reactions).

 The degree of conversion of alkali metal hydroxide in the prototype method is 4-20%. The resulting polymers contain from 10 to 97% of DHCP groups, which tend to block distribution of units.

 The disadvantages of the prototype method include the low degree of conversion of alkali metal hydroxide to DHCP groups and obtaining a polymer in which the distribution of DHCP groups tends to block.

 An object of the invention is to increase the degree of conversion of alkali metal hydroxide to DHCP groups and to obtain a polymer with their static distribution.

This problem is solved in that in the known method for producing a modified 1,4-PB containing DCCP groups, by the interaction of 1,4-PB in a hydrocarbon solvent with chloroform and an aqueous solution of an alkali metal hydroxide in the presence of a phase transfer catalyst, the interaction is carried out by fractional feeding an aqueous solution of an alkali metal hydroxide and chloroform with a catalyst for interphase transfer into a hydrocarbon solution of 1,4-PB at a molar ratio of 1,4-PB-CHCl ₃ : OH: KMP equal to 1: (1-3): (0, 3-2): (0.002-0.2). Quaternary ammonium salts selected from the group are used as CMP: TEBAX, tetraethylammonium chloride (TEAC), tetrabutylammonium chloride (TBAC) or tetraethylammonium chloride (TEAC), trimethylamine (TMA), triethylamine (TEA), tributylate and 1 tributyl amine , 4-PB in the form of a pre-prepared complex with chloroform. According to the specified method receive a modified 1,4-polybutadiene containing statistically distributed dichlorocyclopropane groups.

The essence of the invention lies in the fact that in a solution of 1,4-PB in a hydrocarbon solvent (toluene, gasoline, nefras, cyclohexane or a mixture thereof), an aqueous solution of an alkali metal hydroxide and chloroform with dissolved CMF in a molar ratio of 1.4- PB: chloroform: alkali metal hydroxide: CMP, equal to 1: (1-3) :( 0.3-2.0) :( 0.002-0.02). The process is carried out for 0.5-4 hours at 20-40 ^o C. As a 1,4-PB used cis-1,4-PB, containing from 87 to 98% cis-1,4-units (rubbers SKD, obtained on Ti-, Co-, Ni-systems or on the rare-earth catalytic system rubbers SKD, SKD-2, SKD-3, SKD-5). SKD contains 87-93% cis-1,4 units, SKD-2 - 93-96% SKD-3 94-97% SKD-5 98% 1,4-links or 1,4-PB with a mixed structure (45 -55% cis-1,4 units, 45-55% trans-1,4 units, 10% 1,2-units). SKDI (butadiene copolymer with small amounts of isoprene), SKDL-250, obtained under the influence of an organolithium initiator. The concentration of the solution of 1,4-PB 5-15 wt. As a solution of 1,4-PB can also be used a polymerizate of the above grades of rubbers. KMP is prepared by dissolving a quaternary ammonium salt in chloroform or alcohol. CMP based on trialkylamine (TEF, TMA, TBA) is prepared in advance in the form of a complex with chloroform, dissolving it in a 3-4-fold excess of the latter. As the alkali metal hydroxide, sodium or potassium hydroxide is used in the form of a 40-60% aqueous solution.

 At the end of the process, the solution of the modified 1,4-PB is washed with cold or hot water (the volume of water is equal to the volume of the reaction mixture), repeating the operation 2-5 times, then it is isolated by water degassing and dried by a known method.

 The process is characterized by the degree of conversion of sodium hydroxide into dichlorocyclopropane groups of the polymer with the content of DCCP units, the nature of their distribution, the glass transition temperature according to the DSC method, oil and petrol resistance (swelling according to GOST 9.030-74), and elastic strength properties.

The content of DHCA groups is determined by the C ¹³ NMR method or calculated from the amount of chlorine bound in the polymer determined according to the Schoniger method (Klimova EA, “Basic micromethods for the analysis of organic compounds”, M. Chemistry, 1967, p. 115), according to
[DHCP] mol. 54 • 100: (7100: / [Cl] wt. -83)
The nature of the distribution of DCCP units is determined by the C ¹³ NMR method on a Bruker AM-500 spectrophotometer with an operating frequency of C ¹³ 125.74 MHz, determining the length of the sequence of units of the same nature (DCCP or butadiene units in the considered version) in comparison with theoretically calculated for random joining. Correspondence of theoretical and experimental data indicates the static nature of the distribution of links. Their significant discrepancy indicates a tendency to block polymer.

Based on a polymer with dichlorocyclopropane units, a rubber mixture of the following composition is prepared, m.h. rubber 100; carbon black 50; ZnO - 1; MgO 5; sulfur 1.5; sulfenamide C 0.5. Vulcanization is carried out for 20-30 minutes at 143 ^o C.

Example 1 (control prototype). To a solution of 1,4-cis-PB (SKD rubber) containing 80 ml of toluene and 5 g of polymer, 0.5 g of TEBAH and 5 g of NaOH in the form of a 50% solution are added and then 25 ml are added at 45 ^° C with vigorous stirring chloroform. The synthesis is carried out for 1.5 hours, then the reaction mixture is washed 4 times with an equal volume of the reaction mixture with an amount of water. The polymer is isolated in alcohol, dried in vacuum at 60 ^o C and characterized by NMR. The molar ratio of 1,4-PB: CHCl ₃ : OH: KMP is 1: 2.7: 1.35: 0.01. The content of DHCP-links 23.7%
The degree of conversion of sodium hydroxide is 17.7%. The conditions for obtaining the polymer from this example and all subsequent ones, as well as the properties of the obtained polymers are given in Table 1.

Example 2. To a solution containing 54 g (1 mol) of 1,4-PB (rubber SKD: 93% 1,4-cis units) in toluene (concentration of 10 wt.) Served 119.5 g of chloroform (1 mol) s dissolved in it 0.68 g TEBAH, and then with vigorous stirring, maintaining the temperature at 25 ^o C, for 1.5 h serves 28 g (0.7 mol) of sodium hydroxide in the form of a 50% solution and 119.5 g (1 mol) of chloroform with 0.68 g TEBAH dissolved in it at a rate of 0.3 g / min and 1.33 g / min, respectively. After 2 hours, water is added to the reaction mixture in an amount equal to the volume of the reaction mixture: the water is drained. The washing operation is repeated 4 times. The polymer was isolated by water degassing, dried in vacuum at 60 ^o C. The molar ratio of 1,4-PB: CHCl ₃ : OH: KMP is 1: 2: 0.7: 0.006. The content of DHCP-links 25% The degree of conversion of sodium hydroxide 35.7%
Example 3. To a solution containing 54 g (1 mol) of 1,4-PB (rubber SKD: 93% 1,4-cis units) in toluene (concentration of 10% wt.) Serves a mixture of 239 g of chloroform and 4.54 g (0.02 mol) of TEBAH in ethanol and then, with vigorous stirring, maintaining a temperature of 20 ^° C., 54 g of sodium hydroxide in the form of a 50% solution are supplied over 2 hours. The process is completed 4 hours after the start of the supply of reagents. The molar ratio of the reagents is 1,4-PB: CHCl ₃ : OH: KMP, equal to 1: 2.7: 1.35: 0.01. The content of DHCP groups is 45%; the degree of conversion of sodium hydroxide is 33%
Example 4. To a solution containing 54 g (1 mol) of 1,4-PB (rubber SKD-2: 96% 1,4-cis units) in gasoline (concentration of 9 wt.) Served 119.5 g of chloroform (1 mol) and 0.45 g (0.002 mol) of TEBAH dissolved in it, and then, at 20 ^° C. and vigorous stirring, 16.8 g (0.3 mol) of potassium hydroxide (in the form of a 60% solution) are supplied for 1 hour. After 1.5 hours, the polymer was washed as described in Example 2, but the operation was repeated only twice. The polymer is isolated by water degassing and dried on rollers. The molar ratio of 1,4-PB: CHCl ₃ : OH: KMP is 1: 1: 0.3: 0.02. The content of DHCP-links 10% The degree of conversion of sodium hydroxide 33%
Example 6. To a solution containing 54 g (1 mol) of 1,4-PB (rubber SKD-3: 97% of 1,4-cis units) in toluene (concentration of 8 wt.), Served in equal portions every 5 minutes for 1 h, maintaining a temperature of 40 ^o C, 358.5 g (3 mol) of chloroform with dissolved in it 2.3 (0.01 mol) TEBAH and 80 g (2 mol) of sodium hydroxide (in the form of a 50% solution) . After 2 hours, the reaction mass is washed as described in Example 2. The operation is repeated 4 times. The polymer is isolated by water degassing and dried in an air dryer. The molar ratio of 1,4-PB: CHCl ₃ : OH: KMP is 1: 3: 2: 0.01. The content of DHCP-links 80% the degree of conversion of sodium hydroxide 40%
Example 7. To a solution containing 54 g (1 mol) of 1,4-PB (rubber SKD-5: 98% 1,4-cis units) in a mixture of nefras-cyclohexane (concentration of 10 wt.), Serves a mixture of 179 g (1.5 mol) of chloroform and 4.54 g (0.02 mol) of TEBAH in ethanol. Then, with vigorous stirring, while maintaining the temperature at 30 ^° C, 40 g (1 mol) of sodium hydroxide (in the form of a 40% solution) is supplied over 0.5 h, after which another 119.5 g (1) is fed over 0.5 h mol) chloroform. After 2 hours, hot water is added to the solution (the volume of water is equal to the volume of the reaction mixture), emulsify. The operation is repeated 2 more times. The polymer was isolated and dried as described in Example 2. The molar ratio of reagents (1,4-PB: CHCl ₃ : OH: KMP is 1: 2.5: 1: 0.02. The content of DCCP groups is 33%; the degree of conversion of sodium hydroxide is 33 %
Examples 8-10. Obtaining a modified 1,4-PB containing DHCP groups is carried out according to the method of example 2, but instead of TEBAH use TEAC (example 8), TBAC (example 9) and TBAB (example 10), instead of rubber SKD rubber SKDL-250 (45 % cis, 45% trans-10% 1,2-units). The content of DHCP groups is respectively 27, 24.5, and 24.5%; the degree of conversion of sodium hydroxide is 38.5, 35, and 33%
Example 11. The process of obtaining modified 1,4-polybutadiene is carried out according to a continuous scheme. In a cascade of three devices with mixers, an intensive type mixer is installed at the inlet of each of them. At the inlet in front of the first apparatus, the flows of 1,4-PB polymerizate (rubber SKD: 91% 1,4-cis-units, 10% solution in toluene), chloroform with a complex of TEA with chloroform, and sodium hydroxide (50% aqueous solution) in the following molar ratio of 1,4-PB: CHCl ₃ : OH: KMP = 1: 1: 0.30: 0.005. The reaction mixture, having passed the first complex of TEA and sodium hydroxide (total molar ratio of 1,4-PB: CHCl ₃ : OH: KMP = 1: 1.5: 0.5: 0.001). Having passed the second apparatus, the reaction mixture is fed to the inlet of the third mixer, where it is mixed with sodium hydroxide and a TEA complex with chloroform (total molar ratio 1: 1.5: 0.75: 0.015). The temperature is maintained at 35 ^o C. After passing through the third apparatus (total reaction time 0.5 h), the reaction mixture is washed, undergoing water degassing, drying.

The content of DHCP-links 26% degree of conversion of sodium hydroxide - 35%
Example 12. A modified 1,4-polybutadiene is produced in a continuous circuit on a cascade of three apparatuses with agitators, an intensive emulsification mixer is installed at the input of each of them. At the inlet in front of the first apparatus in the mixer, flows of polymerizate (solvent - gasoline) of rubber SKDP-250 (45% of 1,4-cis units, 45% of 1,4-trans and 10% of 1,2 units) of chloroform are dissolved in it TEA and 50% PB: CHCl ₃ : OH: KMP = 1: 1: 0.75: 0.005. The reaction mixture after the first apparatus is fed to the inlet of the second mixer, where it is emulsified with chloroform containing a complex of TEA and sodium hydroxide. The total ratio of the reagents 1,4-PB: CHCl ₃ OH: KMP = 1: 2: 1.5: 0.01. After the second apparatus in the third mixer, the reaction mixture is emulsified with chloroform sodium hydroxide. The total ratio of the reagents 1,4-PB: CHCl ₃ : OH: KMP = 1: 3: 2: 0,01. The synthesis time is 2 hours, the temperature is 30 ^o C. The content of DCC units is 78%; the degree of conversion of sodium hydroxide is 36%
Examples 13, 14. A modified 1,4-polybutadiene containing DCCP groups is prepared according to the procedure of Example 12, but instead of TEA, TMA (Example 15) and TBA (Example 16) are used, and instead of sodium hydroxide, potassium hydroxide with a concentration of 60% mass The content of DCCP units is 23 and 24% and the degree of conversion of potassium hydroxide is 30.6 and 32%, respectively.

 From the presented examples it follows that the polymers obtained by the proposed method with the same ratio of reagents to the prototype contain 1.89 times more DHCP groups (examples N 1 and 4), and to obtain polymers with the same ratio of DHCP groups is required in 2 times less alkali metal hydroxide (examples 1K and 2, 9, 10). This indicates a more efficient use of the reagents used. In addition, the polymers obtained by the proposed method have a lower glass transition temperature and the degree of swelling at the same content of DHCP groups than the polymers obtained in a known manner (examples 1k, and 2, 9, 10, 13, 14), which is associated with the structure polymer, namely with the distribution of DHCP groups along the polymer chain.

Table 2 shows the distribution of DCCP units determined by the C ¹³ NMR method *) and the elastic-strength properties (rubber strength according to GOST 19920.20-74 and elongation according to GOST 19920.20-74).

In addition, the polymer obtained by the proposed method is the most frost-resistant of all oil-resistant hydrocarbon rubbers, surpassing BNK or polychloroprene by 15-20 ^o C in frost resistance with the same oil resistance.

Thus, the proposed method allows to increase the degree of conversion of alkali metal hydroxide to DHCP groups and to obtain a polymer with their statistical distribution, which, in turn, leads to an increase in frost resistance and benzine resistance of the obtained polymer. * The larger the deviation n $\genfrac{}{}{0ex}{}{\text{op}}{\text{dhtsp}}$ from n $\genfrac{}{}{0ex}{}{\text{ntjh}}{\text{dhtsp}}$ (characterizes the static distribution), the greater the blockiness of the polymer.

Claims (3)

 1. The method of obtaining a modified 1,4-polybutadiene containing dichlorocyclopropane groups, the interaction of 1,4-polybutadiene in a hydrocarbon solvent with chloroform and an aqueous solution of an alkali metal hydroxide in the presence of an interphase transfer catalyst, characterized in that the interaction is carried out by fractional supply of an aqueous hydroxide solution alkali metal and chloroform with a catalyst for phase transfer into the hydrocarbon solution of 1,4-polybutadiene dissolved in it at a molar ratio of 1,4-polybutadiene n chloroform alkali metal hydroxide, phase transfer catalyst 1 (1 3) (0.3 2) (0.002 0.2), respectively.  2. The method according to claim 1, characterized in that the quaternary ammonium salts selected from the group: triethylbenzylammonium chloride, tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide are used as a phase transfer catalyst.  3. The method according to claim 1, characterized in that a trialkylamine selected from the group: trimethylamine, triethylamine, tributylamine, in the form of a pre-prepared complex with chloroform, is used as a phase transfer catalyst.

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