RU2429247C1 - Method of producing chlorinated polydienes - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method involves reaction of polydienes with chloroform in the presence of a phase-transfer catalyst and aqueous solution of an alkali metal hydroxide with fractional addition thereof. The reaction takes place while feeding the entire calculated amount of chloroform directly into the polymer. The phase-transfer catalyst is added to the polymer solution in pure form and the process takes place in molar ratio polydiene : chloroform : alkali metal hydroxide : phase-transfer catalyst equal to 1:(2.0-3.0):(0.1-2.5): (0.001-0.0018).

EFFECT: high degree of conversion of alkali metal hydroxide when producing chlorinated polydienes.

1 cl, 6 ex, 2 tbl

Description

The invention relates to the field of producing modified rubbers, and in particular to methods for producing chlorinated polydienes by attaching dichlorocarbenes in double bonds under conditions of interphase catalysis. Chlorinated polydienes are characterized by high cohesive strength, adhesion to various materials, adhesive ability, resistance to aggressive environments and are designed to produce sound-absorbing, vibration-damping and adhesive materials used, for example, in aircraft, shipbuilding, automotive and tire industries.

A known method of producing chlorinated polydienes with a high content of vinyl units (60-80 wt.%) By introducing gaseous chlorine into a solution of polydiene immediately after the polymerization process with preliminary distillation of the monomer (US Pat. US 5089563, C08C 19/12, publ. 18.02.92 ) The introduction of chlorine significantly accelerates the vulcanization process, provides a high level of elastic deformation properties, and therefore is widely used in tire production. The disadvantage of this method is the low degree of chlorination of polydienes (not more than 2.5 wt.%), In addition, the use of gaseous chlorine is harmful to the environment, environmentally unsafe and uneconomical.

There are known processes of chlorination of linear polybutadienes (1,4-polybutadiene) in which chlorine is generated in situ, eliminating the potential danger of using gaseous chlorine or HCl.

For example, there is a method for producing chlorinated 1,4-polybutadiene (US Pat. RF 2073019, C08F 8/18, C08C 19/18, publ. 02/10/97), the essence of which is that in a solution of rubber in a hydrocarbon solvent (toluene, gasoline, nefras, cyclohexane or a mixture thereof) an aqueous solution of an alkali metal hydroxide and chloroform with interfacial transfer catalyst (CMP) dissolved in it (tetraethylbenzylammonium chloride (TEBAH), tetraethylammonium chloride (TEAC), trimethylamine (TMA), triethylamine ( .) with a molar ratio of 1,4-polybutadiene: chloroform: g alkali metal droksid: KMP being 1: (1-3) :( 0.3-2.0) :( 0.002-0.02). The process is carried out for several hours at a temperature of 20-40 ° C. At the end of the process, a solution of the modified 1,4-polybutadiene is washed with water of equal volume, repeating the operation 2-5 times, then it is isolated by water degassing, and dried by a known method.

The disadvantage of this method of producing chlorinated polydiene is the low degree of conversion of alkali metal hydroxide (up to 40%).

The closest in technical essence is the method of producing chlorinated polybutadiene, which consists in the fact that the missing amount of chloroform and a phase transfer catalyst are fed into a solution of 1,4-polybutadiene (1,4-PB) in a hydrocarbon solvent (toluene, gasoline, nefras, chloroform) transfer, which is introduced in the form of a pre-prepared solution of a quaternary ammonium salt in chloroform or alcohol, then an aqueous solution of alkali metal hydroxide is fractionally fed for 0.3-2 hours at a molar ratio of 1,4-polyb tadiene: chloroform: alkali metal hydroxide: phase transfer catalyst 1: (1-20) :( 0.3-2.0) :( 0.002-0.02) respectively (US Pat. RF 2083592, C08F 8/18, C08C 19 / 18, publ. 10.07.97). After alkali supply, stirring is continued for another 2-2.5 hours at a temperature of 20-40 ° C. For modification, 1,4-polybutadiene with a cis-1,4-unit content of 87 to 98% or 1,4-polybutadiene with a mixed structure (45-55% cis-1,4-units; 45-55% trans 1,4-links; 10% of 1,2-links), as well as rubbers SKDL-250, SKDL obtained on the organolithium catalytic system. The concentration of the solution is 1,4-PB 5-15 wt.%, As the solution can be used polymerizate (an intermediate product for the production of rubber), from which the monomer of the above grades of rubbers has been removed. TEBAH, TEAC tetrabutylammonium chloride (TBAC) or trialkylamine selected from the group: trimethylamine, triethylamine, tributylamine are used as CMP and it is introduced into the hydrocarbon solution of polydiene in the form of a pre-prepared complex with chloroform by 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% 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 chlorination process is described by the scheme:

where M is sodium or potassium,

KMP is a phase transfer catalyst.

An indicator of the effectiveness of the process for producing modified polydiene is the degree of conversion of alkali metal hydroxide. The degree of conversion of alkali metal hydroxide in the prototype method is from 30 to 40%.

The main disadvantage of this method of producing chlorinated polydienes is the low degree of conversion of alkali metal hydroxide. The disadvantages of the prototype method include the use of an additional hydrocarbon solvent or a very large dilution of rubber with chloroform (1:20, example 6), the supply of KMP with its preliminary dissolution in chloroform or alcohol, the use of large quantities of KMP (0.002-0.02 mol in calculated on the polymer), which complicates the process of washing the modified polydiene.

The technical task of the invention is to increase the degree of conversion of alkali metal hydroxide in the process of producing chlorinated polydienes by the addition of dichlorocarbenes in double bonds under conditions of interphase catalysis.

This object is achieved in that in the known method for producing chlorinated polydienes by reacting polydienes with chloroform in the presence of an interphase transfer catalyst and an aqueous solution of an alkali metal hydroxide during fractional feeding, the interaction is carried out by feeding the entire calculated amount of chloroform directly to the polymer, and the interphase transfer catalyst a pure polymer solution and the process is carried out at a molar ratio of polydiene: chloroform: silk metal hydroxide: KMP 1: (2.0-3, 0) :( 0.1-2.5) :( 0.001-0.0018).

The essence of the proposed method is as follows. An interphase transfer catalyst is fed into the polymerizate or a solution of polydiene in chloroform and an aqueous solution of an alkali metal hydroxide fractionally for 0.5-1 hours at a molar ratio of polydiene: chloroform: alkali metal hydroxide: KMP 1: (2.0-3.0): (0.1-2.5) :( 0.001-0.0018). The process is carried out with vigorous stirring and a temperature of 20-25 ° C, after completion of the alkali supply, stirring is continued for another 2-3 hours at a temperature of 40-45 ° C. Polydienes are polydienes with a high content of vinyl units (3,4-polyisoprene, 1,2-polybutadiene) containing vinyl units (49.1-75.9 wt.%) And (64.5-66 wt.%), Respectively obtained by anionic polymerization using an environmentally friendly catalytic system based on soluble organic compounds of sodium and magnesium, developed at the Federal State Unitary Enterprise NIISK, as well as organolithium compounds; SKD (content of cis-1,4 units more than 91%). As KMP use TEBAH, TEAC, TEA, which is introduced into the polymer solution or the polymerizate in its pure form. As the alkali metal hydroxide, sodium or potassium hydroxide is used in the form of a 50% aqueous solution. At the end of the process, the solution of the modified polydiene is washed 2-4 times with cold water (1.5-3 times excess relative to the solution of polydiene), if necessary, the excess alkali is neutralized conc. hydrochloric acid. Washed polydiene is isolated by water degassing and dried by a known method. The process is characterized by the degree of conversion of sodium hydroxide to dichlorocyclopropane (DCCP) groups - the content of DCCP groups and, accordingly, chlorine in polydiene.

The content of chlorine bound in the polymer is determined by the Schoniger method (Klimova EA, “Basic micromethods for the analysis of organic compounds”. M: “Chemistry”, 1967, p. 115).

The molecular weight characteristics and microstructure of the starting and chlorinated polydiene are determined using gel chromatography (Waters-2000) and NMR spectroscopy (Bruker-AM 500).

Molecular mass characteristics, microstructure of the starting and chlorinated polydienes, the content of bound chlorine in chlorinated rubbers, molar ratios of polydiene: alkali metal hydroxide, and the degree of conversion of alkali metal hydroxide are given in tables 1-2.

Example 1. To a polymerizate containing 34 g of 3,4-polyisoprene (0.5 mol) and 100 ml of chloroform (1.25 mol), 0.2 g of TEBAH (0.0009 mol) was added, then with vigorous stirring at room temperature at a temperature of 1 hour, 55 g of sodium hydroxide in a form of a 50% solution in water (1.24 mol) are fractionally fed in three doses, maintaining the temperature no higher than 25 ° C, then, at the end of the alkali supply, the chlorination process is continued to increase the conversion at temperature 40 ° C for 3 hours. At the end of the process, a solution of the modified polydiene is washed with 200 ml of water, an excess of alkali is neutralized with 20 ml of hydrochloric acid, and then washed with water 4 more times (200 ml each) until neutral. Washed polydiene is isolated by water degassing and dried on rollers at a temperature of 120 ° C. The molar ratios of polydiene: chloroform: alkali metal hydroxide: KMP 1: 2.5: 2.5: 0.0018. The content of chlorine bound in the polymer is 34.8 wt.%. The degree of conversion of sodium hydroxide is 69.8%.

Example 2. To a solution containing 34 g of 3,4-polyisoprene (0.5 mol) and 100 ml of chloroform (1.25 mol), 0.2 g of TEBAH (0.0009 mol) was added, then with vigorous stirring at room temperature at a temperature of 0.5 hours, 5.5 g of sodium hydroxide are fractionally fed in the form of a 50% solution in water (0.125 mol) in two doses, maintaining the temperature no higher than 25 ° C, then, at the end of the alkali supply, the process is continued to increase the conversion chlorination at a temperature of 40 ° C for 3 hours. At the end of the process, a solution of the modified polydiene is washed with 200 ml of water, an excess of alkali is neutralized with 1 ml of hydrochloric acid, and then washed with water twice more (200 ml each) until neutral. Washed polydiene is isolated by water degassing and dried on rollers. The molar ratios of polydiene: chloroform: alkali metal hydroxide: KMP 1: 2.5: 0.25: 0.0018. The content of chlorine bound in the polymer is 14.3 wt.%. The degree of conversion of sodium hydroxide 72.1%.

Example 3. To a solution containing 170 g of 3,4-polyisoprene (2.5 mol) and 500 ml of chloroform (6.25 mol), 1 g of TEBAH (0.004 mol) was added, then with vigorous stirring at room temperature, fractionally for 0.2 g serves 11 g of sodium hydroxide in the form of a 50% solution in water (0.25 mol), at the end of the alkali supply, the chlorination process is continued at a temperature of 40 ° C for 3 hours. At the end of the process, a solution of the modified polydiene is washed with 1.5 L of water, an excess of alkali is neutralized with 3 ml of hydrochloric acid, and then washed with water twice more (1.5 L each) until neutral. Washed polydiene is isolated by water degassing and dried on rollers. The molar ratios of polydiene: chloroform: alkali metal hydroxide: KMP 1: 2.5: 0.1: 0.0018. The content of chlorine bound in the polymer is 7.9 wt.%. The degree of conversion of sodium hydroxide is 100%.

Example 4. To a solution containing 282 g of 3,4-polyisoprene (4.2 mol) and 1000 ml of chloroform (12.5 mol), 1.2 g of TEAC (0.0073 mol) was added, then with vigorous stirring at room temperature at a temperature of 18.5 g of sodium hydroxide in a form of a 50% solution in water (0.42 mol) is fed in two doses; at the end of the alkali supply, the chlorination process is continued at a temperature of 40 ° C for 3 hours. At the end of the process, a solution of the modified polydiene is washed with 1.5 L of water, an excess of alkali is neutralized with 5 ml of hydrochloric acid, and then washed with water twice more (1.5 L each) until neutral. Washed polydiene is isolated by water degassing and dried on rollers. The molar ratios of polydiene: chloroform: alkali metal hydroxide: KMP 1: 3.0: 0.1: 0.0017. The content of chlorine bound in the polymer is 9.1 wt.%. The degree of conversion of sodium hydroxide is 97.6%.

Example 5. To a solution containing 50 g of 1,2-polybutadiene (0.93 mol) and 150 ml of chloroform (1.9 mol), 0.25 g of TEBAH (0.0011 mol) was added, then with vigorous stirring at room temperature the temperature in two doses serves 4.2 g of sodium hydroxide in the form of a 50% solution in water (0.095 mol), at the end of the alkali supply, the chlorination process is continued at a temperature of 40 ° C for 3 hours. At the end of the process, a solution of the modified polydiene is washed with 300 ml of water, an excess of alkali is neutralized with 0.5 ml of hydrochloric acid, and then washed with water twice more (300 ml each) until neutral. Washed polydiene is isolated by water degassing and dried on rollers. The molar ratios of polydiene: chloroform: alkali metal hydroxide: KMP 1: 2.0: 0.1: 0.001. The content of chlorine bound in the polymer is 7.8 wt.%. The degree of conversion of sodium hydroxide is 67.3%.

Example 6. To a solution containing 50 g of 1,2-polybutadiene (0.93 mol) and 200 ml of chloroform (2.5 mol), 0.16 g of TEA (0.0016 mol) was added, then with vigorous stirring at room temperature at a temperature of 1 hour, 41.2 g of sodium hydroxide in the form of a 50% solution in water (0.93 mol) are fed, at the end of the alkali supply, the chlorination process is continued at a temperature of 40 ° C for 3 hours. At the end of the process, a solution of the modified polydiene is washed with 500 ml of water, an excess of alkali is neutralized with 2 ml of hydrochloric acid, and then washed with water three more times (500 ml each) until neutral. Washed polydiene is isolated by water degassing and dried on rollers. The molar ratios of polydiene: chloroform: alkali metal hydroxide: KMP 1: 2.7: 1: 0.0017. The content of chlorine bound in the polymer is 25.3 wt.%. The degree of conversion of sodium hydroxide is 48.9%.

Example (control prototype).

To a solution containing 27 g of SKD (0.5 mol) and 243 g of toluene (10% solution), 120 ml of chloroform (1.5 mol) with 0.68 g of TEBAH (0.003 mol) dissolved in it are fed and vigorous stirring at a temperature of 25 ° C for 45 minutes fractionally serves 14 g of sodium hydroxide in the form of a 50% solution in water (0.35 mol), maintaining the temperature not higher than 25 ° C, then at the end of the alkali supply, the chlorination process is continued at the same temperature for 2 hours. At the end of the process, 400 ml of water is fed into the solution of the modified polydiene and emulsified for several minutes. After settling, the water is drained, the washing operation is repeated 4 times. Washed polydiene is isolated by water degassing and dried on rollers at a temperature of 120 ° C. The molar ratios of polydiene: chloroform: alkali metal hydroxide: KMP 1: 3: 0.7: 0.006. The content of chlorine bound in the polymer is 15.0 wt.%. The degree of conversion of sodium hydroxide is 46.5%.

Table 1
Molecular mass characteristics and microstructure of the starting polydienes. No. of starting polymers Molecular weight characteristics The content of units, wt.% M _{w *} 10 ^-3 M _{n *} 10 ^-3 M _w / M _n 1,2-PB 133 27.6 4.84 64.5 (1.2 links) 3,4-PI No. 1 191 103 1.85 69.3 (3.4 and 1.2 links) 3,4-PI No. 2 186 79.0 2,35 49.1 (3.4 and 1.2 links) SKD 288 129 2.22 91.1 (CIS-1,4 links)

table 2
Characteristics of chlorinated polydienes Example No. Chlorinated Polydiene Molecular weight characteristics The chlorine content, wt.% The molar ratio of polydiene: alkali metal hydroxide Degree converted alkali,% M _{w *} 10 ^-3 M _{n *} 10 ^-3 M _w / M _n one IIR (3,4-PI No. 1) 184 86.6 2.12 34.8 1: 2.5 69.8 2 IIR (3,4-PI No. 1) 189 88.4 2.13 14.3 1: 0.25 72.1 3 IIR (3,4-PI No. 1) 189 96.7 1.95 7.9 1: 0.1 one hundred four IIR (3,4-PI No. 2) 192 80.1 2,39 9.1 1: 0.1 97.6 5 1,2-PBH 148 15.3 9.6 7.8 1: 0.1 67.3 6 1,2-PBH 153 16,0 9.5 25.3 1: 1 48.9 counter. SKDH 262 110.0 2,38 15.0 1: 0.7 46.5

Thus, the proposed method for producing chlorinated polydienes allows to increase the degree of conversion of alkali metal hydroxide, which ensures a more efficient use of the reagents used. In addition, to obtain chlorinated polydienes, the use of a hydrocarbon solvent or a 20 molar excess of chloroform and the preliminary dissolution of CMP in chloroform are not required, which simplifies the process.

The method allows to obtain chlorinated polydiene with various chlorine content (up to 35 wt.%), While the molecular weight characteristics of chlorinated polydiene do not undergo significant changes.

Claims (1)

A method of producing chlorinated polydienes by reacting polydienes with chloroform in the presence of an interphase transfer catalyst and an aqueous solution of an alkali metal hydroxide during fractional feeding, the process being carried out by feeding the entire calculated amount of chloroform directly to the polymer, and the interphase transfer catalyst is fed into the polymer solution in in pure form and the process is carried out at a molar ratio of polydiene: chloroform: alkali metal hydroxide: phase transfer catalyst 1: (2.0- 3.0) :( 0.1-2.5) :( 0.001-0.0018).