RU2161631C1 - Method of stabilization of polymers - Google Patents

Abstract

FIELD: production of diene polymers and technology of preparing synthetic rubbers. SUBSTANCE: method of stabilization of diene polymers comprises introducing amine and/or phenol type antioxidants of mixtures of alkyl derivatives thereof into solution of polymer prepared by (co)polymerization of monomers in hydrocarbon solvent. Mixture of antioxidant with viscous liquid is first prepared title oxidant concentration of 15-50 wt % is attained or antioxidant melt or liquid antioxidant is used, mixture or melt is then diluted with paraffin hydrocarbon to concentration of 5-10 wt % and is admitted to polymer stabilization stage. In this case, viscous liquid includes polydienes, polyolefins, diene-olefin copolymers, esters with molecular weight from 250 to 1500. Antioxidant or mixture thereof in viscous liquid is diluted with paraffin solvent at pressure of 0.15-0.50 Mpa. EFFECT: reduced or complete elimination of toluene losses and lower consumption of steam for degassing natural rubber and improving ecology of the process. 2 cl, 1 dwg, 18 ex

Description

 The invention relates to a technology for producing synthetic rubbers, for example, to the production of diene polymers, and can be used in the petrochemical industry.

 A known method of stabilizing rubbers, for example polyisoprene, obtained by polymerization of isoprene in a hydrocarbon solvent in the presence of a catalyst, which consists in introducing antioxidants in the form of an aqueous suspension into a solution of deactivated and washed polymer, followed by stirring, averaging and directing to the isolation and drying of the rubber / Kirpichnikov P. A . and others. Chemistry and technology of synthetic rubber. L .: Chemistry, 1975, p. 258-261 /.

 The disadvantages of this method are the heterogeneity of the distribution of the antioxidant in the polymer, the loss of antioxidant during transportation, the need to use surfactants to stabilize the suspension.

There is also known a method of stabilizing isoprene or butadiene rubber, which consists in introducing into the isopentane or toluene solution of rubber at a temperature of 18-25 ^o C toluene solution of 2,6-ditret-butyl-4-methylphenol or a mixture of N-phenyl-β-naphthylamine with N, N'-diphenyl-p-phenylenediamine as antioxidants [Synthetic rubber. Ed. N.V. Garmonova. L .: Chemistry, 1976, p.219].

The specified method has an unsatisfactory mixing of a highly viscous polymer solution at a low temperature (18-25 ^o C) with a solution of antioxidants, which reduces the stabilization efficiency and leads to an excessive consumption of antioxidants. In addition, due to the large dosage of toluene with an antioxidant, there are increased losses of toluene with ready-made rubber and an excessive consumption of water vapor for rubber degassing.

The closest in technical essence and the obtained result is a method of stabilizing isoprene rubber by introducing phenolic and / or amine type antioxidants into a polyisoprene hydrocarbon solution, for example, 2,6-ditret-butyl-4-methylphenol, N-phenyl-β-naphthylamine, N, N'-diphenyl-p-phenylenediamine, in a hydrocarbon solvent also containing from 1.5 to 15% by weight of antioxidants stearic acid, and they are stabilized at 45-65 ^o C [RF Patent 2076884, C 08 L 9/00 , op. 04/10/1997].

 Unlike known methods, this stabilization method eliminates clogging of pipelines and equipment with sludge, reduces the loss of antioxidants, but the loss of toluene and the cost of water vapor for rubber degassing are still large.

 The specific loss of toluene reaches 28 kg / t of rubber, the flow rate of water vapor is 2.0-2.1 Gcal / t of rubber. The hydrocarbon content in degassed rubber (mainly toluene) is in the range of 0.35-0.50 wt. %, which worsens the ecology of production.

 The objective of the invention is to reduce or completely eliminate losses of toluene, reducing the consumption of water vapor for degassing rubber and improving the ecology of production.

 This problem is solved in that in the proposed method for stabilizing polymers by introducing amine and / or phenolic type antioxidants or mixtures of their alkyl derivatives into a polymer solution obtained by (co) polymerizing diene and olefin monomers in a hydrocarbon solvent, an antioxidant mixture with heavy boiling aromatic hydrocarbons is first prepared with a viscous liquid until the antioxidant concentration is reached (15-50)% wt. or a melt of antioxidant, then dilute the mixture or melt with paraffin hydrocarbon to a concentration of (5-10)% wt. and served at the stage of stabilization of the polymer, and as a viscous liquid using polydienes, polyolefins, copolymers of dienes with olefins, esters with a molecular weight of from 250 to 15000.

 Dilution of the antioxidant or its mixture in a viscous liquid or in a heavy boiling aromatic hydrocarbon with a hydrocarbon paraffin solvent is carried out under a pressure of 0.15-0.50 MPa.

 Unlike the known method, the proposed method can significantly reduce or completely eliminate the use of an aromatic solvent of toluene at the stabilization stage, which will not only improve the ecology of production, but also increase its technical and economic indicators. The use of polydienes, polyolefins, copolymers of dienes with olefins and esters, for example rubber plasticizers, as a viscous liquid, will improve the physicomechanical and technological properties of the resulting rubbers. The uniformity of the distribution of antioxidants introduced into the stabilization of the polymers is ensured by the use of paraffinic hydrocarbon solvents for dilution, carried out under a pressure of 0.15-0.50 MPa.

 The proposed method for stabilizing polymers is carried out according to the circuit diagram shown in the drawing.

 An antioxidant in the form of a liquid or a melt is fed through lines 1 and 2, respectively, to a steam-heated apparatus with a stirrer 3, where, under the condition of complete or partial exclusion of an aromatic hydrocarbon, for example toluene, a viscous liquid, which is polydienes, polyolefins, and diene copolymers, is fed through line 4 with olefins, esters (plasticizers, oils, substances with functional groups) with a molecular weight of from 250 to 15000, in an amount that ensures the achievement of an antioxidant concentration (15-50) wt.%.

 Polydienes, polyolefins, copolymers of dienes with olefins and esters, if necessary, are mixed with toluene, xylene, benzene, synthetic fatty acids, their salts and alkalis, as well as aliphatic alcohols.

 In contrast to the known method, the proposed methods allow, for example, in the presence of a melting agent for an antioxidant in the technological scheme, the melt is fed both directly to mixing with paraffin hydrocarbon and after mixing with a viscous organic liquid, and the resulting solution or finely dispersed system is then sent to the polymer stabilization stage. When using liquid antioxidants, for example, VTS-60, VTS-150 (TU 6-14-1013-87, TU 38.103613-86), which are respectively alkyl substituted N, N'-diphenyl-1,4-phenylenediamine and diphenylamine, alkylated styrene with a high viscosity (120-400 cP), they are also served as directly after heating or mixing with a small amount of hydrocarbon solvent, and after mixing with a viscous organic liquid for dilution with paraffin hydrocarbon.

 When using a powdered antioxidant and no melting agent, it is preferable to use a viscous organic liquid and melt the antioxidant in apparatus 3 (see drawing), after which it is sent for mixing with paraffin hydrocarbon and then for polymer stabilization.

 When using an organic liquid with a high molecular weight, for example, 10000-15000, toluene or another aromatic hydrocarbon is partially fed into the apparatus 3, then their specific costs for preparing a solution or dispersion of an antioxidant, in contrast to the known method, are significantly reduced.

Water vapor directed to the jacket of the apparatus 3 is supplied via line 5, and the steam condensate is withdrawn through line 6. The apparatus 3 is also provided with line 7 for withdrawing vapors and gases to a reflux condenser (not shown in the diagram). In the presence of a reflux condenser, the temperature in the apparatus 3 is adjusted, if necessary, to (130-150) ^o C.

 From the apparatus 3, the liquid antioxidant or its melt, either directly or together with a viscous liquid - polydienes, polyolefins, copolymers of dienes with olefins, esters and, if necessary, with other substances mentioned above, is sent along line 8 by pump 9 and then through line 10 to the apparatus a diluent 11 with an agitator, into which a paraffin solvent (isopentane, nefras, heptane-isohexane fraction, etc.) is supplied via line 12. The apparatus is also heated with water vapor or hot water supplied through line 13. Condensate or hot water from the jacket of the apparatus 11 is withdrawn through line 14.

 If it is necessary to release rubber that does not contain low molecular weight polymers or esters, for example, small amounts of toluene or other aromatic hydrocarbon fed through line 15 to apparatus 3 are used. In this case, antioxidant is melted in apparatus 3 and a solution or dispersion of antioxidant in toluene or another aromatic hydrocarbon with a concentration of (15-50) wt. %, then it is sent to the apparatus 11, where it is diluted with paraffin hydrocarbon.

In all cases, in the apparatus 11, a solution or dispersion of the antioxidant in a hydrocarbon solvent with a concentration of (5-10) wt.% Is prepared. The pressure in the apparatus 11 is preferably maintained (0.15-0.50) MPa, which allows almost completely to eliminate the loss of hydrocarbons to the atmosphere and achieve a temperature of the solution or dispersion of antioxidants, preferably (45-65) ^o C, which will help reduce the viscosity of the solution or dispersion .

 The prepared solution or dispersion of the antioxidant through line 16 by pump 17 and then through line 18 is sent to the collector 19, then along lines 20-24 they are fed to stabilize the polymer solution introduced through line 25 into the volumeless mixer 26 and together with the polymer solution through line 27 to the apparatus 28 and 29 with a stirrer.

The stabilization of the polymer solution is carried out at a temperature of (25-85) ^o C, preferably at (45-65) ^o C. If necessary, an additional stop for the polymerization process (for example, methanol, alkalized water, etc.) is introduced into line 25 for supplying a polymer solution for stabilization.

 When preparing a solution or dispersion of the antioxidant in the apparatus 11, use the circulation circuit: apparatus 11 - line 16 - pump 17 - line 18 - line 32 - apparatus 11.

 To avoid stagnation, collector 19 uses line 33 — line 32 — apparatus 11. From apparatus 29, a stabilized polymer solution is sent via line 30 to washing the polymer solution from the catalyst residues with water, degassing, and drying the rubber (not shown in the diagram).

 The method is illustrated by the following examples.

Example 1 (control)
The stabilization of isoprene rubber with an antioxidant is carried out according to the prototype (RF patent 2076884) as follows. Dissolve the antioxidants N, N'-diphenyl-n-phenylenediamine (DPPD) and N-phenyl-β-naphthylamine (naphtham-2) in a methanol toluene solution. In this case, methanol is a stopper for the polymerization of isoprene. The volumetric ratio of methanol: toluene is 50:50. The dissolution of antioxidants is carried out at 20 ^o C and additionally introduced into a solution of antioxidants stearic acid in an amount of 8 wt.%. DFFD is introduced 0.3 wt.% From the polymer, naphtham-2 - 0.8% by weight of the polymer.

In this case, the following indicators were obtained:
The solubility of DFFD in the mixture, wt.% - 5.1
The solubility of naphtham-2, wt.% - 16.0
The content in the rubber DFFD, wt.% - 0.28 ± 0.04
The content in the rubber of naphtham-2, wt.% - 0.735 ± 0.07
The content of sludge in a solution of antioxidants, wt.% - 0.05
Loss of DFFD in the process of washing the polymer, stabilization and degassing of rubber, wt.% - 6.67%
Losses of naphtham-2 during washing, stabilization and degassing of rubber, wt.% - 8.13
Loss of toluene, kg / t rubber - 34.3
Loss of methanol, kg / t of rubber - 13.5
The index of conservation of plasticity of the polymer,% - 98.5
The hydrocarbon content in degassed rubber, wt.% - 0.55
Example 2 (control)
The stabilization of isoprene rubber is carried out by a known method. The dosage of DFFD is maintained at 0.21% by weight of the polymer. Toluene containing 8% stearic acid is used as an antioxidant solvent. The concentration of DPPD in the solution of 4.5 wt.%. Into a non-deactivated solution of polyisoprene in isopentane in an amount of 3 l with a solids content of 12.5 wt.%, 129 ml of a solution of DFPD in toluene is introduced, stirred for 45 minutes in an apparatus with a stirrer speed of 1500 rpm, then the polyisoprene solution is degassed by the aqueous method in the presence of calcium stearate (9 kg / ton rubber) crumb rubber was dried at 150 ^o C for 2 hours, then the index is determined preserve ductility of the polymer, the antioxidant content in the rubber, its water-loss rubber Mooney viscosity, plasticity and strength Karrer rubber tear.

Key process indicators:
The content of DFFD in rubber, wt.% - 0.198 ± 0.03
Loss DFFD, wt.% - 5.7
Mooney rubber viscosity - 77.0
Carrer's rubber ductility - 0.34
The plasticity conservation index,% - 89.0
Conditional tensile strength, MPa - 33.1
Loss of toluene, kg / t of rubber - 28.0
The residual hydrocarbon content in degassed rubber, wt. % - 0.45
Examples 3-5
The stabilization of isoprene rubber is carried out by the proposed method. A solution of polyisoprene in isopentane is charged with DPPD at the rate of 0.25% by weight of the polymer. DFPD is introduced in polypiperylene (oligopiperylene) with a molecular weight of 250-15000 obtained by polymerization of piperylene in the presence of diphenyl oxide-modified aluminum chloride. Polyisoprene is prepared by polymerizing isoprene in an autoclave in a solution of isopentane in the presence of a Ziegler-Natta catalyst modified with piperylene and diphenyl oxide (similar to examples 1-2). The content of polyisoprene in a solution of isopentane 12.9 wt.%.

The calculated amount of DFPD is introduced into each of the samples of polypiperylene and the mixture is heated with continuous stirring to 130 ^° C. The concentration of DFPD in polypiperylene is maintained at 20 wt.%.

 A solution of DFFD in piperylene diluted with isopentane to a concentration of 10 wt.% Is introduced into each portion of 3 kg polyisoprene in terms of polymer. %, mixed, then degassed in laboratory degassers, dried the resulting rubber and carried out physical and mechanical tests of the rubber mixture based on isoprene rubber (according to the standard recipe in accordance with GOST 14925-79). The loss of antioxidant during degassing and drying, its content in the finished rubber, as well as the index of conservation of plasticity of the polymer and the content of hydrocarbons in degassed rubber are also determined. The losses of toluene introduced with the catalyst for the polymerization of isoprene are calculated (the dosage of the catalyst is 0.5 wt% of isoprene, the concentration of the catalyst in the toluene solution is 104 g (l of solution). The sludge from the antioxidant solution did not precipitate.

 The main test results are given in table. 1.

Examples 6-7
Butadiene rubber production. Stabilization is carried out according to the known (example 6) and the proposed methods (example 7). Butadiene for polymerization is introduced in nefras (TU 38.1011228-90, grade P-1-65 / 75), the catalyst is a mixture of an organic compound of cobalt and diisobutylaluminium chloride. Agidol-2- 2,2'-methylene-bis- (6-tert-butyl-4-methylphenol) in a toluene solution (Example 6) and in a polypropylene solution with a molecular weight of 6000 are used as antioxidant. Dosage of agidol-2 in both cases of 1.0% by weight of the polymer. The concentration of agidol-2 in toluene is 10 wt.%, The concentration of agidol-2 in polypropylene is 50 wt.%, And after dilution with nefras - 10 wt.%. The dry residue of the polybutadiene solution is 10 wt.%.

 The main process indicators are given in table. 2.

Examples 8-11
The stabilization of isoprene rubber is carried out by the proposed method. Polyisoprene is prepared by polymerizing isoprene in an isopentane solution in the presence of a Ziegler-Natta catalyst modified with diphenyl oxide and introduced at a concentration of 100 g / l in toluene. As an antioxidant use DFFD, dosed in an amount of 0.22 wt. % of polymer. The antioxidant is introduced in ether GF-270 (TU 38.3015-83), obtained by the interaction of aliphatic alcohols C ₈ -C ₁₈ with organic acids C ₈ -C ₁₂ with the formation of esters of the fraction C ₁₆ -C ₃₀ . The bottom residue of the rectification of the hydroforming products after the cobalt regeneration stage is subjected to evacuation and after distillation of the fractions from T _bales to 270 ^° C, a mixture of oxygen-containing aliphatic hydrocarbons from C ₁₂ and higher with various functional groups is obtained. This product contains more than 50% esters, the product is a waste product from the production of butyl alcohols. The concentration of antioxidant in ether GF-270 is prepared in the range of (15-50) wt.%, Melted at 130 ^o C and then diluted to an antioxidant content (5-10) wt.% With isopentane and introduced into the polymer solution after washing it from the catalyst residues (examples 8-10). Example 11 shows the indicators achieved by the known method of stabilization of polyisoprene charged with DFPD in a toluene solution. The solids content of the polymer solution is 12.9 wt.%.

The main process indicators are given in table. 3
In the preparation of the DFPD melt in the plasticizer-ether GF-270, the sludge was not deposited (examples 8-10). In example 11, in the known method, the antioxidant sludge content in the solution reached 0.07%.

Examples 12-14
Stabilization of polyisoprene is carried out by the proposed method. As an antioxidant use DFFD. Isoprene polymerization catalyst — Ziegler-Natta catalyst modified with DFO, is introduced in a toluene solution with a concentration of 110 g / l.

The solids content of the polymer solution is 14 wt.%. DFPD is melted at 130 ^° C. and introduced into an isopentane container to dilute the antioxidant. The pressure in the tank can withstand 0.15-0.50 MPa.

 The main process indicators are given in table. 4.

Examples 15 to 16
The stabilization of butadiene rubber is carried out according to the proposed method (example 15) with an antioxidant BTC-60, dosed in an amount of 0.65% by weight of the polymer. Polybutadiene is obtained on a Ziegler-Natg catalyst. VTS-60 is mixed with nefras to a content of 5 wt.% And sent to stabilize a solution of polybutadiene in toluene. The solids content of 10 wt.% In example 16, the indicators according to the known method of stabilization, when the BTC-60 is introduced in a solution of toluene.

The main process indicators are given in table. 5
Examples 17-18
The stabilization of isoprene rubber obtained on the catalyst, similar in examples 13-15, is carried out by the proposed method (example 17). A copolymer of butadiene with piperylene (liquid rubber SKDPN)) with a molecular weight of 5000 is used as a viscous liquid. Agidol-1 (TU 38.5901237-90), dosed in an amount of 0.85% by weight of the polymer, is used as an antioxidant. Agidol-1 is melted in a copolymer of butadiene with piperylene at 130 ^o C and a concentration of 45 wt. % after dilution with isopentane to 5% concentration serves to stabilize the polyisoprene with a dry residue of 12.5 wt. % In the known method, agidol-1 is introduced in a solution of toluene with a concentration of 5 wt.% (Example 18).

 The main process indicators are given in table. 6.

 As can be seen from the examples, the use of the proposed method allows to reduce the loss of toluene by 8-16 kg / t of rubber, to reduce the consumption of water vapor for degassing rubber by 0.2-0.3 Gcal / t of rubber, to reduce the hydrocarbon content in degassed rubber by 0, 05-0.30 wt.%, As well as reduce the loss of antioxidant by 0.9-9.6% and improve the technological properties of rubber.

Claims (2)

 1. A method of stabilizing polymers by introducing amine and / or phenolic type antioxidants or mixtures of their alkyl derivatives into a polymer solution obtained by (co) polymerizing monomers in a hydrocarbon solvent, characterized in that the liquid antioxidant or antioxidant is in the form of a melt or after mixing with a viscous liquid to achieving an antioxidant concentration of 15-50 wt.% is directed to dilution with a paraffin solvent to a concentration of 5-10 wt.%, then fed to the stage of polymer stabilization, moreover, as a viscous liquid use polydienes, polyolefins, copolymers of dienes with olefins, esters with a mol.m. from 250 to 15000, while the dilution of the antioxidant with a paraffin solvent is carried out under a pressure of 0.15 - 0.50 MPa.  2. The method according to claim 1, characterized in that, if necessary, before dilution with a paraffin solvent, the antioxidant melt is additionally diluted with toluene or another aromatic hydrocarbon to a concentration of 15 to 50 wt. %

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