RU2405003C2 - Liquid-phase method of preparing rubber mother batches containing white soot - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: rubber filled with silica filler relates to solution and emulsion types of vinyl-styrene rubber, butadiene rubber, mixtures thereof in weight ratio of 5-98:95-2 and isoprene rubber. The silica filler, particularly white soot, is prepared in form of a suspension in a hydrocarbon solvent, and its hydrophobisation is carried out during preparation of the suspension due to content of polysiloxane additives or mixtures thereof with a coupling agent and a reaction initiator in a silica filler-coupling agent-rubber system.

EFFECT: high degree of dispersion of white soot with low power consumption, simple method of filling rubber and preparing a rubber mixture.

7 cl, 22 tbl, 315 ex

Description

The invention relates to a liquid-phase method for the preparation of masterbatches based on rubber and silicic acid filler, which can be used for the manufacture of rubber compounds and vulcanizates based on them.

To obtain rubber-based mixtures used in the manufacture of tires and rubber products, it is important that the elastomer used has a set of strictly defined characteristics, and the filler is well dispersed in its matrix. All this leads to an improvement in viscous and elastic-strength properties, and in the case of tire rubbers it can significantly reduce rolling resistance, provide good adhesion to dry and wet roads, which accordingly reduces fuel consumption and ensures greater traffic safety.

In addition to rubber and filler, plasticizers, softeners, accelerators, dyes, etc. can be used in such mixtures [Vostroknutov EG, Novikov MI, Novikov VI, Prozorovskaya NV Processing of rubbers and rubber compounds (rheological basis, technology, equipment). - M: Chemistry, 1980. - 280 p.].

The components are mixed in a rubber mixer or, less commonly, on rollers [Hans-Detlef Luginsland. Mixtures fed a filler and an organosilicon compound. Pat. No. 6624230. Degussa AG. Application 04/13/2001. Publ. 09/23/2003 .; Paul Harry Sandstrom, Richard Robinson Smith, Kevin James Pyle. Tire with silica reinforced tread and / or sidewall components. Pat. No. 6046266. The Goodyear Tire & Rubber Company. Application September 24, 1998. Publ. 04/04/2000.] In the technology for the preparation of rubber compounds, a two- or three-stage process is widely used [US patent No. 6686408 B2. Bridgestone Corporation .; US patent No. 6809146. Bayer Aktiengesellschaft.]. Between stages, the resulting mixture is cooled.

This process is quite labor-consuming and energy-consuming, especially in the case of the use of silicic acid fillers. Due to the different polarity of the rubber and the filler, they mix poorly with each other, which causes a deterioration in the quality of the mixture. The presence of a large number of silanol groups on the surface of the silicic acid filler leads to the adhesion of its particles and their repeated agglomeration during mixing, increasing the viscosity of the mixture and, consequently, energy consumption. Silicon acid filler can also form densely mesh structures, and the rubber compound is difficult to process and vulcanize. To improve the compatibility of rubber and silicic acid filler, various combination agents are used, among which organosilane compounds are most widely used. However, their use increases the mixing time, especially in comparison with mixtures filled with carbon black. In addition, it is necessary to control the temperature of preparation of the mixture for the proper course of the reaction of silanization and to avoid scorching, leading to a significant deterioration in the processability of the resulting mixture.

The solution to the above problems is possible by using a liquid-phase filling process. All methods for implementing the liquid-phase process of filling rubbers can be divided into three main groups:

a) Emulsion filling of rubber.

In this case, a mixture of an aqueous suspension of a silicic acid filler and a rubber emulsion is mixed, followed by precipitation of the resulting mixture, or a mixture of a rubber emulsion is mixed with an aqueous alkali metal silicate solution [Mark J. Marquisee. Du Pont de Nemours and Company. U.S. Pat. No. 4,212,918. Dec. 30.09.1977. Publ. 07/15/1980; Udo Gorl, Reinhard Stober, Hartmut Lauer, Uwe Ernst. Pulverformige, modifizierte Fullstoffe enthaltende Kautschukpulver, Verfahren zu ihrer Herstellung und Verwendung. Patent No. DE 19843301 Al. PKU Pulver Kautschuk Union Gmbh. Application 09/22/1984. Publ. 03/23/2000; Erhardt Fischer. US Pat. No. 4,482,657. Polysar Limited. Claim 07/12/1983. Publ. 11/13/1984; Thomas Scholl. Bayer AG. 6025415. Decl. 07/02/1998. 02/15/2000; Ahti Koski. U.S. Patent No. 6323260. Bayer Inc. Claim 11/20/1998. Publ. 11/27/2001.]

b) Filling the rubber solution.

With this filling method, the rubber solution is either converted into an emulsified form and the filling proceeds similarly to the filling of emulsion rubbers, or the rubber solution is filled with a suspension of the filler or in water [Ahti Koski. 6420456. Bayer Inc. Claim 05/21/1998. Publ. 07/16/2002], or in a solvent [Zhong-Ren Chen, Sunji Araki, William M. Cole, William Hergenrother. Solution masterbatch process using fine particle silica for low hysteresis rubber. US patent No. 7312271 B2. Bridgesone Corporation. Application December 29, 2005; publ. 12/25/2007; G. Agostini. U.S. Patent No. 6,555,606. The Goodyear Tire & Rubber Company. Claim 03/20/2000. Publ. 04/29/2003].

All of these methods have disadvantages. In particular, the disadvantages include the multiplicity and complexity of the stages of the process, processing and preparation of raw materials, the need for special emulsifiers and coagulants. Yet one of the main disadvantages is the need to use a more expensive hydrophobized silicic acid filler or to separately carry out long stages of modification of a silicic acid filler or rubber. Using the finished hydrophobized filler, as well as conducting a separate modification step before preparing the suspension, increases the cost of the process and increases its duration. Modification of rubber when introduced into the industry will also require changes in the technology for its production.

In connection with the foregoing, it is still necessary to develop a simple and relatively cheap liquid-phase process for filling rubber, characterized by a short implementation time and low energy consumption, while a high degree of dispersion of the filler must be achieved.

The developed liquid-phase process for obtaining masterbatches includes the following stages:

- preparation of a rubber solution or the use of a polymerizate. Moreover, the removal of monomer residues from the polymerizate is not required;

- hydrophobization of the silicic acid filler with polysiloxane additives or mixtures thereof with a combining agent and an initiator of interactions in the system "silicic acid filler - combining rubber agent" at the stage of preparation of the suspension in an organic solvent;

- mixing a solution of rubber in an organic solvent (s) and a suspension of silicic acid filler;

- removal of solvent (s) and drying of the resulting product.

The filled rubbers can be solution and emulsion (oil-, soot- and soot-filled soot) styrene-butadiene rubbers (DSSK-2545, SKS-30, etc.), butadiene rubbers (SKD-ND, SKD) and isoprene rubbers (SKI brands) -3, SKI-5, etc.).

Aliphatic, alicyclic, aromatic hydrocarbons, as well as mixtures thereof in various ratios, are used as a solvent for the preparation of the rubber solution. So, among them can be called pentane, isopentane, hexane, heptane, cycloheptane, cyclohexane, methylcyclohexane, cycloheptane, isooctane, n-octane, hexane-heptane fraction of hydrocarbons in various ratios of hexane to heptane, benzene, toluene, xylenes, ethylbenzene, diethyl isobutylbenzene, petroleum ether, etc. The most suitable are hexane, heptane, cyclohexane and toluene, and mixtures thereof.

The concentration of the rubber solution may be 5-60 wt.%.

The rubber solution can be obtained in two ways. Firstly, by dissolving the rubber in a solvent. Secondly, a polymer solution obtained by the process of (co) polymerization can be used.

In the first case, the rubber is dissolved with stirring 10-1500 rpm and a temperature of 10-120 ° C to a homogeneous consistency.

Well-known grades with a specific surface area measured by the BET method or the CTAB method of 30-400 m ² / g, oil number (adsorption of dibutyl phthalate), which should be 120-350 ml / 100 g and an average projection area, are used as a silicic acid filler. aggregates should be 7000-8800 nm ² , and pH 5-8.

The most currently used brands of silicic acid fillers are Zeosil 1165 MP (Rhone-Poulenc SA); Ultrasil VN2, Ultrasil VN3, Ultrasil 7000 GR (Evonik Degussa AG); Hi-Sil 210, Hi-Sil 190, Hi-Sil 215, Hi-Sil 233, Hi-Sil 255 ("PPG Industries Inc."); KS 404, KS 300 and Perkasil 233 (“Akzo Nobel”), Zeopol 8745, Zeopol 8755 (“Huber”); Rosil-175 (Soda OJSC).

For the preparation of a suspension of silicic acid filler, the same solvents are used as for the preparation of the rubber solution. The concentration of the suspension of silicic acid filler varies from 5 to 60 wt.%.

To improve the compatibility of the silicic acid filler and rubbers, so-called combining agents are used. Among them, organosilane and organosiloxane combining agents, which may contain alkenyl, aryl, halogen, amine, and other functional and non-functional groups and their mixtures, are most widely used. So, bis (triethoxylylpropyl) tetrasulfide (TESPT) (Si-69® Evonik Degussa AG; Silquest® A-1289, OSi Specialties Group / Crompton Corporation), bis (triethoxylpropyl) disulfide (TESPD ) (Silquest® A-1589, OSi Specialties Group / Crompton Corporation), 3-mercaptopropyl triethoxysilane (MPTES) (Silquest® A1891, OSi Specialties Group / Crompton Corporation), 3-octanoylthio-1- propyltriethoxysilane ("General Electric"), 3-methyldimethoxysilyl-1 propyl mercaptosilane ("Crompton Corporation"), 3-mercapto-1-propyltrimethoxysilane ("Crompton Corporation") and others. The bis-3 combining agent is currently widely used. triethoxy ililpropil tetrasulfide (TESPT, Si-69®) «Evonik Degussa AG» firm.

Surfactants are also used (stearates, oleates, palmitates, polyalcohols, etc.). It should also be noted the use of oligo- and polyhydridesilanes as water repellents [Christian Hans Dieter, Schubert Jurgen, Schmeier Uwe. Precipitated silica whose surface is modified with polyorganosiloxane polymer and preparation method thereof. DPRK patent No. 1020040098585 A. Application 05.13.2004; publ. November 20, 2004].

The hydrophobization reactions in all cases described in the technique and technology are carried out before the stage of preparation of the suspension of the silicic acid filler or a pre-hydrophobized silicic acid filler is used.

There are liquid phase filling methods for rubbers described in US Pat. Nos. 6,420,456 to Bayer Inc. and No. 7312271 B2 developed by employees of Bridgesone Corporation, in which the rubber solution was filled with a suspension of pre-hydrophobized silicic acid filler, and also a patent in which white carbon black was hydrophobized with polyorganosiloxanes [DPRK patent No. 1020040098585].

As the closest analogue to the claimed method, the method of producing rubber filled with treated water-repellent compound (hydrophobizing additive) with silicon dioxide (US 6025415 from 02.15.2000), in which the silicic acid filler (silicon dioxide) is first subjected to preliminary hydrophobization, at a temperature of 200-220 ° C in for 4-7 hours, using 0.5-200 mass parts of a hydrophobizing additive per 100 mass parts of the filler, while before, during and after hydrophobization, the filler is dried to remove moisture to ≤3 wt.%. Then, the already hydrophobized silicic acid filler is introduced into a solution of rubber in an organic solvent, the resulting suspension of filler in rubber is supplied dropwise for 2 hours in 2 l of water preheated to 70 ° C, while steam is supplied simultaneously (Tpara = 100-110 ° C) . Then, the solvent was removed from the mixture by steam distillation.

The disadvantage of this method is the need to remove water within 4-7 hours, which is formed as a result of the interaction of the surface of the silicic acid filler and water-repellent additives, as well as the need to mix droplet suspension of the filler in rubber with water within 2 hours. In addition, the disadvantage is the difficulty of uniformly mixing 500 g of silicic acid filler and 50 g of hydrophobizing additive due to the large surface area of the silicic acid filler.

The objective of the invention is to increase the efficiency of the process of filling rubbers with silicon dioxide fillers, namely: reducing the time of the method, reducing energy consumption and increasing the degree of dispersibility of the silicic acid filler in rubber.

The technical problem is solved in that the filled rubber is in the form of a solution. The silicic acid filler is in the form of a suspension in a hydrocarbon solvent, and its hydrophobization occurs at the stage of preparation of the suspension due to the content of polysiloxane additives or their mixture with a combining agent and an initiator of interactions in the system “silicic filler - combining agent-rubber”.

At the same time, a better degree of dispersion of the silicic acid filler is achieved at lower energy consumption, the staging of the filling of rubber and the manufacture of the rubber compound are reduced.

The technical solution is illustrated by the following examples of specific performance.

Example 1

Liquid-phase filling with a silicon-acid rubber filler ДССК 2545-М27 (OJSC "Voronezhsintezkauchuk") was carried out in a glass reactor with an 800 ml stirrer.

Rubber was charged into the reactor in a nitrogen atmosphere of 23.8 g. Next, a mixed solvent was fed (a mixture of nephras (hexane-heptane fraction with a boiling point of 65-75 ° C, or 85-125 ° C) with cyclohexane in a ratio of 92: 8 by weight) in the amount of 112.9 g. Mixing is carried out at a temperature t equal to 65 ° C until homogeneity is achieved, which was determined visually by the absence of heterophase inclusions (approximately 13 minutes).

In parallel, the preparation of the suspension was carried out as follows.

A solution of polymethylsiloxane in toluene was charged into a glass vessel in a nitrogen atmosphere, and a mixed solvent was supplied with stirring and gradual heating. Then, Ultrasil VN3 grade silicic acid filler (Evonik Degussa AG) was added to the solution in an amount of 10 g. The suspension was stirred for 1 minute at a temperature of 65 ° C.

Then, the resulting suspension with stirring in a nitrogen atmosphere is fed into the reactor with a solution of rubber. Mixing lasts 10 minutes. After that, the mixing is stopped and the solvent is distilled off in the vessel by vacuum. The resulting composition is dried in a vacuum oven at 50-60 ° C for 4 hours. The properties of the vulcanizates based on the obtained compositions, as well as comparison with samples of the company "Evonik Degussa AG" are presented in tables 1-9.

The rubber compounds were prepared in a mini-rubber mixer f. "Haake" in two stages according to ISO 2322 (replacement of 100 parts by weight of rubber and 50 parts by weight of carbon black by 150 parts by weight of the composition). The first stage - load factor - 0.43; initial temperature - 60 ° C; unloading upon reaching a temperature of 125 ° C, the mixing time is 9 minutes; the second stage - on the rollers at a surface temperature of the rolls - 50 ° C. Vulcanization was carried out in a vulcanization press at 155-165 ° C for 25 minutes.

The preparation of rubber compounds and vulcanizates according to the examples below, as well as on the basis of the masterbatch "Evonik Degussa AG" was carried out similarly.

Example 2

It is carried out in the same way as example 1, but steam degassing is used with constant stirring. The product is filtered on a Buchner funnel and dried in a vacuum oven at 50-60 ° C for 1-4 hours.

Example 3

It is carried out in the same way as example 1, but it is used to isolate the resulting masterbatch with alcohol, or acetone, or their mixtures in various ratios. The resulting composition is dried in a vacuum oven at 50-60 ° C for 1-4 hours

Example 4

It is carried out in the same way as example 1, but the mixing is carried out in a screw vacuum mixer. Next, the solvent is removed by vacuum and the resulting composition is dried in a vacuum oven at 50-60 ° C for 1-4 hours.

Example 5

It is carried out in the same way as example 4, but steam degassing is used. The suspension is filtered on a Buchner funnel, and the resulting composition is dried in a vacuum oven at 50-60 ° C for 1-4 hours.

Examples 6-10 are performed in the same way as examples 1-5, but a mixture of 3.5 parts by weight is used as a hydrophobizing additive in the preparation of a suspension of silicic acid filler. silicone sealant 3.5 parts by weight Si-69® (F. Evonik Degussa AG) and dinitrilazobisisobutyric acid (DAC), taken with a molar ratio to Si-69® of 1: 1.

Examples 11-15 are performed in the same way as examples 1-5, but a mixture of 3.5 parts by weight is used as a hydrophobizing additive in the preparation of a suspension of silicic acid filler. silicone sealant 3.5 m.h. Si-69® (F. Evonik Degussa AG) and potassium persulfate taken in a molar ratio of Si-69® as 1: 1.

The properties of the vulcanizates based on the composition obtained, as well as a comparison with samples of the company "Evonik Degussa AG" are presented in table 2.

Examples 16-30 are performed in the same way as examples 1-15, but SKD-ND (OJSC Voronezhsintezkauchuk) is used as rubber.

The properties of the vulcanizates based on the composition obtained, as well as a comparison with samples of the company "Evonik Degussa AG" are presented in table 3.

Examples 31-45 are performed in the same way as examples 1-15, but rubber of the SKS-30ARKM M15 brand (OJSC Voronezhsintezkauchuk) is used as rubber.

The properties of the vulcanizates based on the composition obtained, as well as a comparison with samples of the company "Evonik Degussa AG" are presented in table 4.

Examples 46-60 are performed in the same way as examples 1-15, but SKI-3 rubber is used as rubber (OOO Tolyattikauchuk).

The properties of the vulcanizates based on the composition obtained, as well as a comparison with samples of the company "Evonik Degussa AG" are presented in table 5.

Examples 61-75 are performed in the same way as examples 1-15, but as an elastomeric matrix, a mixture of DSSK-2445 M27 and SKD-ND is used (weight ratio 80/20, respectively).

Examples 76-150 are performed in the same way as examples 61-75, but the filler using a silicon acid filler brand Rosil-175 (JSC "Soda").

Examples 151-225 are performed in the same way as examples 61-75, but Zeosil 1165 MP (“Rhone-Poulenc”) silicic acid filler is used as the filler.

Examples 226-300 are carried out in the same way as examples 61-75, but Ultrasil 7000GR grade silicic acid filler (Evonik Degussa AG) is used as a filler.

Examples 301-315 illustrate the implementation of the invention using various combination agents and initiators.

Examples 301-305 are performed in the same manner as examples 6-10, but a mixture of 3.5 parts by weight is used as a hydrophobizing additive in the preparation of a suspension of silicic acid filler. silicone sealant, 3.5 parts by weight 3-mercaptopropyl triethoxysilane (f. OSi Specialties Group) and dinitrilazobisisobutyric acid (DAC), taken in a molar ratio to 3-mercaptopropyl triethoxysilane as 1: 1.

Examples 305-310 are performed in the same way as examples 6-10, but as a hydrophobizing additive in the preparation of a suspension of white carbon black, a mixture of 3.5 parts by weight is used. silicone sealant, 3.5 parts by weight 3-thiocyanatopropyl triethoxysilane and benzoyl peroxide taken in a molar ratio of 3-thiocyanatopropyl triethoxysilane as 1: 1.

Examples 311-315 are performed in the same way as examples 6-10, but as a hydrophobizing additive in the preparation of a suspension of silicic acid filler, a mixture of 3.5 parts by weight is used. silicone sealant, 3.5 parts by weight bis (diisopropyl) thiophosphoryl disulfide and isopropylbenzene hydroperoxide taken in a molar ratio to bis (diisopropyl) thiophosphoryl disulfide as 1: 1.

Claims (7)

1. A method of obtaining a solution filled with a silicic acid filler and emulsion grades of divinyl styrene rubber, butadiene rubber, mixtures based on them (mass ratio 5-98: 95-2) and isoprene rubber, including hydrophobization of a non-acidic filler using a hydrophobizing additive followed by by mixing this suspension and a solution of rubber in an organic solvent, characterized in that the hydrophobization of the silicic acid filler is carried out at the stage of preparing its suspension in a hydrocarbon solution rer with hydrophobizing additive, coupling agent, or mixtures thereof, in the presence of an initiator system interact silicic filler - coupling agent-resin. 2. The method according to claim 1, characterized in that the use of silicic acid fillers with a specific surface area, measured by the BET method, or by the CTAB method, component 30-400 m ² / g, oil number (adsorption of dibutyl phthalate), which should be 120- 350 ml / 100g, and the average projection area of the aggregates should be 7000-8800 nm ² , pH 5-8. 3. The method according to claim 1, characterized in that polysiloxane additives are used as hydrophobic additives, or mixtures thereof with a coupling agent and an initiator of interactions in the silica filler - rubber combining agent system. 4. The method according to claim 1, characterized in that as hydrophobic additives use polysiloxane additives in an amount of 0.1-100 parts by weight per 100 parts by weight rubber. 5. The method according to claim 1, characterized in that as the combining agent use organosilane or organosiloxane combining agents. 6. The method according to claim 1, characterized in that the combining agent is used in an amount of 1-20 parts by weight per 100 parts by weight rubber. 7. The method according to claim 1, characterized in that the initiator of interactions in the system of silicic acid filler - combining agent rubber is used in an amount of 0.001-5 mol per 1 mol of combining agent.