RU2210575C2 - Cyclopolyisoprene production method - Google Patents

Abstract

FIELD: rubber industry. SUBSTANCE: invention provides a method for production cyclopolyisoprene showing good film-forming properties and having weak coloration. Method consists in cyclization of polyisoprene dissolved in organic solvent in presence of titanium tetrachloride as catalyst in combination with electronodonor compound, the latter being compound reacting with titanium tetrachloride and/or forming chelate complex therewith, whereas cyclization process is carried out at titanium tetrachloride-to-polyisoprene ratio from 0.01:1 to 0.03:1. Once cyclization process is ended, protonodonor compound can be added to solution. Catalyst is prepared either preliminarily by mixing titanium tetrachloride with electronodonor compound or directly in polyisoprene solution, electronodonor compound-to-titanium tetrachloride molar ratio varying between 0.1:1 and 0.4:1. EFFECT: achieved desired properties of cyclopolyisoprene. 7 cl, 2 tbl, 34 ex

Description

 The invention relates to the synthetic rubber industry and relates to a method for producing cyclopolyisoprene by cyclization with partial destruction of polyisoprene, preferably cis-1,4-polyisoprene, in particular natural or synthetic isoprene rubber.

 It is known that the cyclization of polyisoprene with its partial destruction in order to obtain cyclopolyisoprene (CPI) with reduced unsaturation, containing cyclic structures and having film-forming properties necessary for its use in paints and varnishes, is carried out in solution in an appropriate solvent without subsequent isolation of the polymer. It is desirable that there is no need for an operation to remove catalyst residues, complicating the process and increasing production costs.

A known method of producing cyclized polyisoprene in the presence of a catalyst containing titanium or tin halide and a sulfonic acid selected from methane, ethane, propane, butane and toluenesulfonic acids, with a ratio of catalyst components from 1: 200 to 200: 1 and a temperature from 0 to 200 ^o C, preferably from 30 to 100 ^o C (US patent 4678841, C 08 C 19/10, 1987). The disadvantage of this method is that the process takes place, as a rule, in a heterophasic system, which leads to the production of an inhomogeneous polymer with unsatisfactory film-forming properties having a noticeable color in the absence of a washing step.

There is a known (see E. Ceausescu. New research in the field of macromolecular compounds. M .: Chemistry, 1983, p. 201-221) a method for producing cyclized polyisoprene by cyclization of polyisoprene in an organic solvent in the presence of a catalyst representing titanium tetrachloride in an amount of 7-19 % per polymer, at 80-100 ^o C; after 5 hours, a CPI with an intrinsic viscosity of 0.34 dl / g is obtained. However, the uncertainty of the obtained CPI is 66-69% of the original, which indicates an insufficient degree of cyclization and unsatisfactory film-forming properties of such a CPI, which also has an intense color.

Closest to the proposed method for producing a CPI is a method for producing a CPI by cyclizing synthetic isoprene rubbers in a solution in white spirit at a rubber concentration of 25-35%, a temperature of 100-140 ^° C., using titanium tetrachloride as a catalyst in combination with an electrode donor compound ( EMF) at a dosage of titanium tetrachloride 5% wt. on the polymer and the ratio of EMF / titanium of 0.5: 1-1: 1 mol. (see "Production and use of elastomers", 1997, 8, p.3-5). According to the authors of this application, acetone or methyl ethyl ketone was used as the electron donor compound in this work. The CPI obtained by this method has an intrinsic viscosity of 0.1-0.34 dl / g, low residual unsaturation, and good film-forming properties. A disadvantage of the known method is that the CPI polymer obtained by this method is colored red-brown due to the presence of catalyst residues and its decomposition products. The use of aqueous washing of the solution from the catalyst residues in this case is inconsistent, since the saturation of the CPI solution with moisture impairs its film-forming properties, and the drying of the CPI solution after washing is difficult.

 The objective of the invention is to provide a method for producing a CPI, which, along with a weak color, has good film-forming properties, in particular water resistance.

 This problem is solved by the fact that in the method for producing cyclized polyisoprene (CPI) by cyclizing polyisoprene in a solution in an organic solvent in the presence of a catalyst based on titanium tetrachloride and an electron-donating compound (EMF), a compound selected from the group consisting of alcohols, diketones, cyclic alkylene oxides, simple di- and polyesters, complex di- and polyesters, di- and polyamines, amino alcohols, as well as mixtures of these compounds, with a molar ratio of EMF and titanium tetrachloride from 0.1: 1 to 0.4: 1, and the process iklizatsii carried out at a molar ratio of titanium tetrachloride and polyisoprene from 0.01: 1 to 0.03: 1.

The essence of the method is as follows. In the apparatus with a stirrer and a heating jacket, connected with a thermostat, the required amount of polyisoprene and solvent is loaded, heated to 50-150 ^o With stirring and kept under stirring for 10-60 minutes. Then, an electron-support compound and titanium tetrachloride or, alternatively, a catalyst prepared in advance from the indicated components are fed into the reactor, and the contents of the reactor are kept under stirring for 1-8 hours under the same conditions. Preferably, at the end of the cyclization process, while stirring, the proton donor compound (PDS) is fed into the reactor, in an amount that ensures the deactivation of the catalyst residues, is maintained for the time required for the catalyst deactivation, after which the contents of the reactor are discharged.

 Natural or synthetic rubber, for example SKI-ZS (TU 38.103241-90), can be used as polyisoprene, for example, nefras (TU 38. 401-67-108-92) or toluene is used as a solvent.

 It is preferable to use emfs soluble in organic solvents in which cyclization is carried out. As the electron donor compound (EMF), a compound selected from the group consisting of alcohols is used, including glycols (eg ethylene glycol, propylene glycol), glycerin, pentaerythritol, sugars (eg glucose, fructose, sucrose); diketones, including beta diketones (e.g. acetylacetone); cyclic alkylene oxides (e.g. ethylene oxide, propylene oxide); di- and polyesters (eg, diglyme, triglyme), di- and polyesters (eg, dibutyl malonate, dibutyl phthalate), in particular glycol ethers and esters; di- and polyamines (e.g. ethylenediamine, diethylenetriamine), amino alcohols (e.g. triethanolamine), as well as mixtures of these compounds.

 In this application, the terms polyesters, polyamines, etc. mean compounds with the number of corresponding groups of more than two.

 The molar ratio of EMF and titanium tetrachloride is from 0.1: 1 to 0.4: 1. A higher ratio than 0.4: 1 does not give any advantages and is uneconomical, and when the ratio is less than 0.1: 1, the effect of the specified connections are not effective enough.

 The cyclization of polyisoprene is usually carried out over a period of 1-6 hours, preferably 1.5-4 hours. For a time shorter than 1 hour, it is usually not possible to carry out cyclization in a controlled mode to the desired degree, that is, with a decrease in unsaturation to 20-50% from the initial and to a characteristic viscosity of 0.1-1.0 dl / g, which provides good film-forming CPI properties. On the other hand, a process that takes too long (more than 8 hours) is not technologically advanced, and is also accompanied by an undesirable cis-trans isomerization process, which worsens the properties of the resulting CPI.

 Preferably, the cyclization of polyisoprene is carried out until an unsatisfactory CPI of 20-50% of the original. The degree of cyclization with an unsaturation of less than 20% is too large, which leads to a polymer with poor properties - not flexible enough, with reduced adhesion. The degree of cyclization with an unsaturation of more than 50% is insufficient, which leads to a polymer with poor film formation.

 Cyclization of polyisoprene is carried out, as a rule, until the characteristic viscosity of the CPI is 0.1-1.0 dl / g, preferably 0.2-0.8 dl / g. A viscosity above 1.0 dl / g makes it difficult to use a CPI solution, usually having a concentration of 10-40%, preferably 20-30%, in paints and varnishes, and a viscosity of a CPI below 0.1 dl / g corresponds to a polymer having too low a molecular weight, not providing sufficient durability of paints and varnishes based on it.

In one embodiment of the invention, a catalyst based on titanium tetrachloride and an electron-donor compound is formed in advance and then fed to a solution of the polyisoprene subjected to cyclization. In this case, it is preferable to mix titanium tetrachloride and the electron-donating compound at a temperature of 0-80 ^° C. for 1-60 minutes. The preparation of the catalyst is carried out in an apparatus with a stirrer or in a mixer of any type, and the temperature and duration are determined by the nature of the electron-donor compound.

 In another embodiment, titanium tetrachloride and an electron donor compound are directly fed to a reactor containing a solution of polyisoprene in an organic solvent. Moreover, it is possible to regulate the specified ratio during the process in order to optimize its implementation. Typically, an increase in the amount of electron donor compound leads to a decrease in catalyst activity, but to a more stable process.

 As the proton donor compound (PDS) added at the end of the cyclization process, for example, organic compounds with acidic properties, such as carboxylic acids and phenols, can be used; C acids, for example beta diketones, such as acetylacetone; acetoacetic ester, malonic mono- and diesters; mono-, di- and polyhydric alcohols, amines, amides, mercaptans, etc., as well as monoesters of dihydric acids, for example maleic, simple and complex monoesters of ethylene glycol, diethylene glycol, propylene glycol, ethylene diamine, polyamines such as diethylene triamine, polyethylene polyethylene ), ethylenediaminetetraacetic acid (EDTA) and its derivatives.

 The molar ratio of said proton donor compound added at the end of cyclization and titanium can be from 1: 1 to 5: 1. As a rule, a higher ratio than 5: 1 does not give any advantages and is simply uneconomical, and when the ratio is less than 1: 1, the effect of this compound is not effective enough.

 The following are non-limiting examples illustrating the invention.

Example 1
35 g of SKI-ZS rubber and 200 ml (about 140 g) of white spirit solvent are loaded into a 250 cc apparatus with a shielded stirrer and a heating jacket connected with a thermostat, the apparatus is closed, and heated to 120 ^° C with stirring and stand 30 minutes. Then, a catalyst obtained by pre-mixing titanium tetrachloride (1 g TiCl ₄ as a 10% solution in toluene) and tetramethylethylenediamine (TMEDA) as an emf (0.25 g as a 5% solution in toluene) in a flask with a stirrer is then fed into the reactor for 10 minutes at a temperature of mixing titanium tetrachloride (1 g of TiCl ₄ as a 10% solution in toluene) and tetramethylenediamine (TMEDA) as an emf (0.25 g as a 5% solution in toluene) in a flask with a stirrer for 10 minutes at 20 ^o C. (molar ratio EMF / TiSl ₄ is about 0.4: 1, and the weight from elations TiSl ₄ / SKI-AP about 0.03). The contents of the reactor are maintained at 120 ^{° C.} with stirring for 4 hours, and then the polymer solution is discharged. The resulting CPI solution has a light yellow color, and the CPI has an unsaturation of about 30% of the initial, characteristic viscosity of about 0.4 dl / g and has good film-forming properties.

Examples 2-11
Under the conditions of Example 1, polyisoprene was cyclized using various electron-donor compounds and different TiCl ₄ / SKI-3C ratios, and proton-donor compounds (PDS) were introduced at the end of the cyclization process (with the exception of Example 10) (Table 1). The obtained CPI has an intrinsic viscosity in the range of 0.2-0.5 dl / g, an unsaturation of 25-48% of the original, light color and good film-forming properties.

Examples 12-34
Cyclization of polyisoprene (SKI-ZS) is carried out under the conditions of example 1 using various electron-donating compounds and ratios (table 2), except that the catalyst components were fed directly to the reactor.

 The legend in table 2 is the same as in table 1.

On the basis of CPI samples, pigmented coatings (films) with a white TiO ₂ pigment content _of about 50% were obtained. The main indicators of coatings were as follows:
White color,
Impact strength - 50 kg • cm,
Hardness - 0.3-0.33
Water resistance - 750-820 h,
Adhesion - 1 point,
Spreading rate - 100-105 g / sq.m.

 Thus, the proposed method allows to obtain a CPI having a lighter color compared to a CPI obtained in a known manner, eliminating the washing step, and having good film-forming properties, in particular water resistance.

Claims (7)

 1. A method of producing a cyclized polyisoprene (CPI) by cyclization of polyisoprene in an organic solvent in the presence of a catalyst based on titanium tetrachloride and an electron-donor compound, characterized in that as the electron-donor compound (EMF), a compound selected from the group consisting of alcohols, diketones, cyclic alkylene oxides, di- or polyesters, di- and polyester, di- or polyamines, amino alcohols, as well as mixtures of these compounds, with a molar ratio of EMF and tetrachloride t tana 0.1: 1 - 0.4: 1, and the cyclization process is carried out at a ratio of titanium tetrachloride and polyisoprene 0.01: 1 - 0.03: 1.  2. The method according to p. 1, characterized in that at the end of the cyclization process, a proton donor compound is added to the solution.  3. The method according to p. 1 or 2, characterized in that the catalyst obtained by pre-mixing titanium tetrachloride and an electron-donor compound is fed into a solution of polyisoprene subjected to cyclization.  4. The method according to p. 1 or 2, characterized in that the supply of titanium tetrachloride and electron-donating compounds is carried out directly in a solution of polyisoprene subjected to cyclization.  5. The method according to any one of paragraphs. 2-4, characterized in that as a proton donor compound added at the end of the cyclization process, organic compounds selected from the group consisting of carboxylic acids, phenols, C-acids, mono-, di- and polyhydric alcohols, mono-, di - and polyamines, mono-, di- and polyamides, mercaptans, monoesters of dihydric acids, simple and complex monoesters of ethylene glycol, diethylene glycol, propylene glycol, as well as mixtures thereof.  6. The method according to claim 5, characterized in that acetoacetic ester, malonic monoesters and diesters and beta-diketones, such as acetylacetone, are used as C-acids.  7. The method according to p. 5, characterized in that ethylene diamine, diethylene triamine, triethylenetetramine, polyethylene polyamine, ethylenediaminetetraacetic acid and its derivatives are used as an amine.

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