Transparent polyethylene-butylene rubber granule as well as preparation method and application thereof

Abstract

The invention discloses transparent polyethylene-butylene rubber granules as well as a preparation method and application thereof. The preparation method comprises the following steps: carrying out anionic polymerization on a butadiene monomer to obtain a BR raw rubber solution, and carrying out catalytic hydrogenation on the BR raw rubber solution to obtain a polyethylene-butylene rubber solution; the polyethylene-butylene glue solution is subjected to falling film evaporation and concentration and then is subjected to deep devolatilization and extrusion granulation through twin-screw extrusion to obtain transparent glue particles (EBBR) with the volatile matter content of less than or equal to 0.35% (mass fraction), and the EBBR has the characteristics of wide molecular mass, no crystallization, good elasticity, high strength, low volatile matter and the like, has excellent physical properties after being blended and vulcanized with PP (polypropylene), and can be widely applied to the field of PP (polypropylene). And meanwhile, good processability is reflected.

Description

Technical Field

[0001] The invention relates to a transparent polyethylene-butene rubber granule, and also relates to a preparation method thereof and application thereof as a polyolefin resin toughening agent, belonging to the technical field of synthetic rubber. Background Art

[0002] Existing polybutadiene rubber (BR-9000), lithium-based styrene-conjugated diene elastomer (SBC), K-resin and ethylene-propylene rubber all adopt solution polymerization, and the solvent is usually hexane, cyclohexane, etc. BR-9000, rare earth BR, rare earth IR and SBC usually use water vapor wet condensation to remove the solvent from the polymer, while for styrene-butadiene copolymer transparent resin with hardness higher than Shao 60A and polyolefin elastomer (POE), the dry method is used to remove the solvent from the polymer.

[0003] Wet devolatilization is a post-processing equipment that undergoes water vapor condensation, solvent recovery and refining, rubber particle extrusion dehydration, drying, etc. For polymer rubber with a wide molecular weight distribution, it will produce glue hanging, agglomeration, and clogging equipment in the condensation kettle, conveying machinery, pipelines, and drying ovens. Wet devolatilization has the disadvantages of many equipment, long process flow, large floor space, poor operating site environment, wastewater generation, high energy consumption, and large investment. In addition, for polymers with high transparency requirements and water content, the products of wet devolatilization are far from meeting the living needs of contemporary people.

[0004] Ethylene propylene rubber (EPDM) has excellent chemical resistance, ozone resistance, aging resistance, electrical insulation and other properties. It is widely used in building waterproof membranes, automotive seals, heat-resistant hoses and tapes, wire and cable casings, lubricant additives and polyolefin modification. Solution polymerization is the dominant process technology for the production of EPDM in the world. There are two main post-processing technologies: wet devolatilization and dry devolatilization. Wet devolatilization technology adopts the traditional rubber post-processing process. In the early stage, DSM, JSR, Exxon and other companies all adopted wet devolatilization technology in the post-processing of rubber production. However, with the development of dry technology in recent years, new EPDM units built by DOW Chemical, Mitsui Chemicals, Exxon-Mobile and other companies, especially the production of titanocene catalytic hydrogenated rubber, have adopted dry devolatilization technology. Compared with wet devolatilization technology, dry devolatilization technology has the characteristics of short process flow, less equipment, clean operation site environment, no wastewater generation due to direct flash evaporation and extrusion to remove solvents, and low energy consumption, but its technology and equipment requirements are very high. At present, China does not have the ability and experience to manufacture large-scale dry devolatilization equipment. For example, in (“Study on the Dry Devolatilization Process of EPDM Rubber, Elastomer, 2013.12”), it is introduced that the Jilin Petrochemical Company Research Institute has built a 200t / a EPDM pilot plant. The post-processing of the plant adopts the dry devolatilization technology of NFM in the United States, including heating system, vacuum system, flash evaporation system and extrusion system. However, the main core equipment parameters of the plant have not been disclosed.

[0005] In recent years, with the development of economy, the consumption of EPDM / PP composite materials for automobile bumpers and instrument panels has reached 600,000-700,000 tons / year. However, there is no literature report on the application of transparent polyethylene-butylene rubber granules to modify polyolefin resins. Summary of the invention

[0006] In view of the defects of the prior art, the purpose of the present invention is to provide a transparent polyethylene-butylene rubber granule (EBBR), which has the characteristics of a wide molecular weight, no crystallization, good elasticity, high strength and low volatility, and has excellent physical properties after blending and vulcanization with PP, and also exhibits good processing performance.

[0007] The second object of the present invention is to provide a method for preparing transparent polyethylene-butylene rubber pellets. The pellets prepared by the method have a volatile content of ≤0.35% (mass fraction). The preparation method is simple and low in cost. It can be produced using existing mature equipment and processes and is easy to industrialize.

[0008] The third object of the present invention is to provide an application of transparent polyethylene-butene rubber granules, which are used for toughening and modifying downstream polyolefin resins to improve the comprehensive physical properties of polyolefin resins.

[0009] In order to achieve the above technical purpose, the present invention provides a method for preparing transparent polyethylene-butylene rubber granules, which comprises the following steps:

[0010] 1) obtaining a polybutadiene raw rubber solution by an anionic polymerization method of butadiene monomer;

[0011] 2) the polybutadiene raw rubber solution is subjected to catalytic hydrogenation to obtain polyethylene-butylene rubber solution;

[0012] 3) After the polyethylene-butylene rubber solution is concentrated by falling film evaporation, it is deeply devolatilized and extruded into granules by twin-screw extrusion.

[0013] The technical solution of the present invention adopts a combined process of falling film evaporation tower pre-concentration and twin-screw machine volatilization for polyethylene-butylene rubber solution. The falling film evaporation tower pre-concentration process can avoid the occurrence of glue hanging and agglomeration of high melt index polymer rubber, and can perform efficient and continuous pre-concentration on the dilute rubber solution. The twin-screw machine can achieve deep devolatilization, and can ensure that the w (total volatile matter) of the extruded sample is less than 0.5%, avoiding the residual solvent from affecting the transparency of the polymer. At the same time, the twin-screw machine has the characteristics of high production capacity.

[0014] As a preferred solution, in step 1), after the cyclohexane solution containing the structure regulator is heated to the temperature required for initiating polymerization, alkyl lithium, butadiene and a branching agent are continuously and evenly added to initiate and carry out polymerization reaction to obtain a polybutadiene raw rubber solution.

[0015] As a more preferred solution, the concentration of the structure regulator is 50-60 mg / Kg solvent.

[0016] As a more preferred solution, the structure regulator is selected from at least one of tetrahydrofurfuryl alcohol ethyl ether, ditetrahydrofurfuryl propane, tetrahydrofurfuryl alcohol butyl ether, and tetrahydrofurfuryl alcohol hexyl ether. Selecting a suitable structure regulator and controlling its appropriate usage amount can effectively adjust the ratio of 1,2 polymerization units in polybutadiene.

[0017] As a more preferred solution, the branching agent is divinylbenzene. As a more preferred solution, the mass of the branching agent is 0.03-0.04% of the mass of the butadiene monomer. By introducing an appropriate amount of divinylbenzene as a branching agent, the molecular weight distribution can be effectively expanded. If the proportion of the branching agent is too low, the effect of expanding the molecular weight distribution cannot be achieved. If the proportion of the branching agent is too high, a macromolecular gel will be produced.

[0018] As a more preferred solution, the mass fraction of the butadiene monomer in the cyclohexane solution is 10-12%.

[0019] As a preferred solution, the molecular ratio of the butadiene monomer to the alkyl lithium is (7-8)×104 The amount of alkyl lithium added is based on the designed molecular weight, which is well known in the industry. The most common alkyl lithium is butyl lithium.

[0020] As a preferred solution, the temperature required to initiate the polymerization reaction is 58-65°C, and the maximum temperature during the polymerization reaction is no higher than 75°C.

[0021] As a preferred solution, alkyl lithium, butadiene and branching agent are continuously and evenly added within 30 to 40 minutes to ensure that the polymer presents a medium molecular weight distribution fraction. If the time is too long, the molecular weight distribution is too wide, and if the time is too short, the molecular weight distribution is too narrow.

[0022] As a preferred solution, in step 2), the conditions of the catalytic hydrogenation reaction are: alkyl lithium as an activator, dimethyl phthalate and methyl o-toluate as co-catalysts, dicyclopentadiene titanium dichloride as a main catalyst, a hydrogen pressure of 13 to 16 bar, a temperature of 75 to 110° C., a total hydrogenation time of not less than 150 min, and a hydrogenation endpoint of a polymer unsaturation of 0.30 to 0.40%.

[0023] As a more preferred solution, the dosage of the main catalyst is 0.030-0.040 g / kg polymer.

[0024] As a more preferred solution, the molar ratio of the main catalyst to the co-catalyst is 3 to 8:1.

[0025] As a more preferred solution, the molar ratio of the alkyl lithium to the co-catalyst is 6 to 12:1.

[0026] The invention can ensure that the hydrogenation effect of the polybutadiene rubber is maintained at a high level by adopting the preferred hydrogenation catalyst and hydrogenation reaction conditions.

[0027] As a more preferred scheme, the process of the catalytic hydrogenation reaction is: first add alkyl lithium and part of the co-catalyst for activation, then add the main catalyst, under the conditions of hydrogen pressure of 13 to 16 bar and temperature of 75 to 110° C. for 70 to 90 minutes; then add part of the co-catalyst and continue hydrogenation for 60 to 80 minutes, and the total hydrogenation time is not less than 150 minutes.

[0028] As a preferred scheme, in step 3), the polyethylene-butene rubber solution is sent to a falling film evaporation tower for preliminary evaporation, and the gas obtained by evaporation enters a condenser from the top of the falling film evaporation tower for condensation, and the solvent is recovered; the concentrated polyethylene-butene rubber solution obtained by evaporation enters a twin-screw extruder from the bottom of the falling film evaporation tower, and the concentrated polyethylene-butene rubber solution is heated and volatilized in the twin-screw extruder, and the volatilized gas is sequentially drawn into a front condenser and a rear condenser for condensation, and the solvent is recovered; the polymer melt obtained by volatilizing the solvent is subjected to screw extrusion, underwater pelletizer pelletizing and centrifugal dehydrator dehydration to obtain finished rubber particles. More specifically, the technical solution of the present invention is to send the polyethylene-butene rubber liquid into the falling film evaporation tower, and distribute it through the distributor arranged at the top of the falling film evaporation tower. Under the action of the distributor, the polyethylene-butene rubber liquid forms a "shower" and is evenly distributed on the semi-circular sieve plate in the falling film evaporation tower to form a thin layer. The falling film evaporation tower is heated by setting a jacket and using steam as a heating medium. The solvent in the polyethylene-butene rubber liquid is evaporated in large quantities. At the same time, the polyethylene-butene rubber liquid with part of the solvent removed flows to the next semi-circular sieve plate under the action of gravity to further evaporate the solvent, and so on. The evaporated gas After the liquid is condensed by the condenser (including water vapor formed by solvent gas or water used to terminate the glue liquid), it enters the condensation tank until the solid content of the glue liquid reaches the required set amount. The concentrated polyethylene-butene glue liquid enters the inlet of the twin-screw devolatilization extruder from the bottom of the falling film evaporation tower. The concentrated polyethylene-butene glue liquid is heated in the twin-screw extruder. The residual solvent in the concentrated glue liquid is forcibly extracted from the gas phase outlet of the twin-screw extruder under a certain temperature and vacuum and enters the front condenser. The condensed solvent enters the front condensation tank. The uncondensed small amount of solvent or water is sent to the rear condenser by the Roots vacuum pump, and the condensed solvent enters the rear condensation tank. At the same time, the desolvated polyethylene-butene melt is transported to the finished product silo through twin-screw extrusion, underwater pelletizing, centrifugal dehydration, and vibration screen to obtain pellets.

[0029] As a preferred solution, the falling film evaporation tower is a vertical structure with an aspect ratio of L / D=10-15. A plurality of large semi-circular sieve plates are arranged on the vertical inner wall of the falling film evaporation tower. The distance between the chord center point of the large semi-circular sieve plate and the inner wall of the tower is 1 / 5-1 / 4 of the diameter of the falling film evaporation tower. Any two adjacent large semi-circular sieve plates are evenly arranged in reverse symmetry, and the spacing between any two adjacent large semi-circular sieve plates is 300-350 mm. It is worth further explaining that the falling film evaporation tower adopts a multi-layer sieve plate structure. Under the action of gravity, the glue liquid forms a thin layer on the sieve plate from top to bottom and gradually evaporates without the solvent boiling. The glue liquid gradually concentrates during the flow from top to bottom, has a short residence time, does not overheat, and avoids the glue liquid from plasticizing under a long time and overheating state. In addition, the glue liquid can be concentrated continuously by using the falling film evaporation tower, and the solid content of the glue liquid can be adjusted at will, which is beneficial to large-scale production and operation.

[0030] As a more preferred solution, the semi-circular sieve plate has sieve holes of Φ=7-12 mm evenly distributed, and the center distance between any two adjacent sieve holes is 16-24 mm.

[0031] As a more preferred solution, the polyethylene-butene glue liquid is sent to the top of the falling film evaporation tower, and after being evenly distributed by the distributor, it is evenly distributed on the first layer of semi-circular sieve plates to form a film layer. Under the action of heating and gravity, the solvent in the film layer evaporates, and the thin glue liquid of the evaporated solvent flows to the next layer of semi-circular sieve plates to continue evaporating, and so on. The solid content of the concentrated glue liquid entering the twin-screw extruder is controlled to be 50-60%; the solid content of the thin glue liquid is 12-14%. If the solid content of the concentrated polyethylene-butene glue liquid is too low, the processing load of the subsequent twin-screw extruder is too large, and the vacuum extraction solvent and condensation recovery efficiency are low; if the solid content of the concentrated polyethylene-butene glue liquid is too high or the melt conveying temperature is too low, the melt flow performance is poor, the conveying is difficult, and it is not easy to enter the twin-screw devolatilization extruder. The solvent used for the polyethylene-butene glue liquid is cyclohexane (boiling point 80°C, and azeotropic with water). If the traditional intermittent kettle evaporation concentration is adopted, the efficiency is low, and the polymer on the kettle wall or the surface of the heating coil heated by the jacket is heated first and for a long time, which causes the double bonds in the polymer molecules to undergo thermal polymerization to produce crosslinking and gel; at the same time, it is also not conducive to the use of a continuous method for dry devolatilization.

[0032] As a more preferred solution, the steam pressure in the falling film evaporation tower is 1-2 bar, the temperature is 80-90° C., and the operating pressure in the falling film evaporation tower is normal pressure.

[0033] As a preferred solution, the total length-to-diameter ratio of the screw of the twin-screw extruder is L / D=42~58, and the extrusion chamber is divided into 9 sections from the inlet to the die; among them, the screw length-to-diameter ratio of the first section is L / D=10~12, the screw length-to-diameter ratios of the second, third, fourth, fifth, sixth, seventh and eighth sections are all L / D=4~5, and gas phase outlets are provided in the fourth, fifth, sixth, seventh and eighth sections.

[0034] As a preferred solution, the parameters of the twin-screw extruder are controlled as follows: die pressure 3.0-5.0 MPa, die temperature 160-170°C, temperature distribution of each section from low to high, temperature range of each section 80-185°C, extruder speed 90-150 r / min, melt residence time 3-5 min. The preferred parameter control can ensure that w (total volatile matter) of the extruded sample is less than 0.5%.

[0035] As a preferred solution, the gas volatilized by heat in the twin-screw extruder is extracted by a Roots vacuum machine and sequentially enters the front condenser and the rear condenser for condensation, and the vacuum degree in the extrusion chamber of the twin-screw extruder is -0.3 to -0.5 bar. If the vacuum degree is too high, the solvent is not easy to be condensed and recovered from the condenser. The Roots vacuum machine is selected to absorb the small amount of solvent gas removed from the twin-screw extruder, which will not cause damage to the Roots vacuum machine, while the use of a common vacuum pump to suck gas and a small amount of water will cause damage to the vacuum pump piston.

[0036] As a preferred solution, the heat transfer medium used by the front condenser and the rear condenser is industrial water at 5-20°C. The condenser and the rear condenser are operated under normal pressure. The front condenser and the rear condenser are respectively equipped with a condensation tank. The condenser and the condensation tank are both well-known equipment to people in the chemical industry.

[0037] The cooling water used by the underwater pelletizer of the present invention is reused through a circulation system, and the recovered solvent is sent to a polymerization unit for cyclic use.

[0038] The falling film evaporation tower of the present invention adopts jacketed steam for heating.

[0039] The twin-screw extruder of the present invention is derived from the continuous horizontal devolatilization extruder of Jiangsu Chengmeng Equipment Co., Ltd.

[0040] The twin-screw heating method of the present invention is electric heating.

[0041] The underwater pelletizer, colloidal pellet centrifugal dehydrator, vibrating screen, finished product silo and water circulation system of the present invention are all well-known equipment to people in the chemical industry.

[0042] The invention also provides a transparent polyethylene-butylene rubber granule, which is obtained by the preparation method.

[0043] The transparent polyethylene-butylene rubber (EBBR) granules prepared by the present invention have the following structural formula:

[0044]

[0045] in,

[0046] x, y, m, n are the polymerization degrees, and x, y, m, n are all integers greater than or equal to 0. Among them, the polymerization degree ratio of the saturated "CC" unit to the unsaturated "C=C" unit is (y+n) / (x+m)=25-35; the unsaturation degree in the EBBR molecule is 0.30-0.40%; (y+x)% / (y+x+n+m)=23-30%.

[0047] The side ethyl content in the EBBR of the present invention can control the crystallization of the polymer, prevent the polymer from losing its elasticity, ensure that the polymer has suitable elastic recovery and strength, and has good flexibility when compounded with polyolefin resin.

[0048] The EBBR of the present invention has a relatively low unsaturated double bond, which is beneficial to form micro-crosslinks with the crosslinking agent, thereby improving the elastic modulus and anti-aging properties of the composite material. The larger the number of uncrosslinked double bonds, the worse the anti-aging properties of the composite material, which is why the EBBR of the present invention is determined to have a low degree of unsaturation.

[0049] The preferred Mooney viscosity of the EBBR of the present invention is 18 to 24 (ML / 125°C); the molecular weight distribution is medium distribution, M w / M n = 1.4 to 1.6. If the Mooney viscosity is too large, melt fracture will occur when it is blended with polyolefin resin and extruded, and the product will have defects. That is, the melting point difference between polymer and polyolefin is not too big, which is more suitable.

[0050] The present invention also provides an application of transparent polyethylene-butylene rubber granules, which is applied to toughening and modifying polyolefin resins, such as PP.

[0051] The present invention uses EBBR pellets to modify toughened polypropylene (PP / EBBR) to prepare pellets and a formula and method:

[0052] The formula of PP / EBBR granules is: PP 100 parts, EBBR 20-30 parts, light calcium carbonate 50-60 parts, cross-linking agent BIPB 0.12-0.15 parts, antioxidant 1010 0.2-0.5 parts.

[0053] The preparation of PP / EBBR pellets can be done by conventional methods known to technicians in the field, such as dry mixing, twin-screw mixing, vulcanization cross-linking, extrusion granulation, etc. For example, light calcium carbonate may not be added when preparing colorless and transparent PP / EBBR pellets; light calcium carbonate and colorants may be added to reduce costs and prepare colored products. PP / EBBR pellets can be used for automotive interior decoration parts, such as bumpers, instrument panels, and home appliance housings.

[0054] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0055] The EBBR provided by the present invention has a short polymerization time and controllable molecular weight distribution during the preparation process of the raw rubber BR, and can be synthesized by using an existing mature anionic polymerization process, which is simple and conducive to industrial production. The synthesized raw rubber BR is hydrogenated to the maximum extent by using an existing titanocene catalyst, retaining a low degree of unsaturation, and after a small amount of double bond cross-linking, the comprehensive physical properties of the composite material can be improved.

[0056] The EBBR provided by the invention has a wide molecular weight, is non-crystallizable, and the polymer has good elasticity and strength.

[0057] The EBBR pellets provided by the present invention adopt falling film evaporation and twin-screw extrusion to collaboratively devolatilize in the preparation process, so as to efficiently obtain high-quality transparent pellets, the polymer volatile content of which is ≤0.5% (mass fraction), the appearance is granular or granular, and the processing performance is good, which is convenient for downstream processing and application.

[0058] The EBBR prepared by the present invention has the characteristics of wide molecular weight, no crystallization, good elasticity, high strength and low volatility, etc., has excellent physical properties after being blended with PP and vulcanized, and also shows good processing performance.

[0059] The EBBR preparation process of the present invention belongs to a homogeneous reaction, has simple preparation, can be synthesized using existing mature processes, and is easy to control and industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is the GPC spectrum of hydrogenated polymer EBBR-1# raw rubber BR.

[0061] Figure 2 The H of hydrogenated polymer EBBR-1# original rubber BR 1 -NMR.

[0062] Figure 3 H is the hydrogenation polymer EBBR-1# 1 -NMR.

[0063] Figure 4 This is the falling film evaporation-twin screw extrusion combined dry devolatilization process of the present invention. DETAILED DESCRIPTION

[0064] The following examples are intended to further illustrate the present invention in detail and are not intended to limit the scope of protection of the claims of the present invention.

[0065] In the following examples, the number average molecular weight and molecular weight distribution index of the polymers were determined by gel permeation chromatography (GPC); 1 -NMR spectrum is used to quantitatively determine the microstructure of the polymer; the mechanical properties of raw rubber and blended alloys are tested according to GB / T36089-2018 method.

[0066] The devolatilization process of the polyethylene-butene glue solution of the present invention is as follows Figure 1 .

[0067] The devolatilization process of the present invention mainly includes a falling film evaporation unit and a granulation unit. The falling film evaporation unit is mainly composed of a falling film evaporation tower, a condenser and a condensation tank; the granulation unit includes a twin-screw extruder, an underwater pelletizer, a colloidal pellet centrifugal dehydrator, a vibrating screen, a finished product silo and a water circulation system, etc. The twin-screw extruder is also provided with a solvent recovery component, including a front condenser, a front condensation tank, a vacuum pump, a rear condenser and a rear condensation tank, etc.

[0068] The specific devolatilization process of the high melt index and high transparency lithium polymer glue of the present invention is as follows: the polyethylene-butylene glue is sent from the top of the falling film evaporation tower into the falling film evaporation tower, and is distributed through the glue distributor under pressure to form a "shower" and evenly distributed on the first layer of semi-circular sieve plates in the falling film evaporation tower to form a thin layer. The falling film evaporation tower is heated by jacket steam, so that the solvent in the polyethylene-butylene glue is evaporated in large quantities. At the same time, the polyethylene-butylene glue flows to the next layer of semi-circular sieve plates under the action of gravity to continue solvent evaporation, and this cycle is repeated, and the evaporated solvent gas or the water content of the glue is formed when the glue is terminated. The water vapor is output from the top of the falling film evaporation tower, and after condensation in the condenser, the liquid is recovered and enters the condensation tank until the solid content of the polyethylene-butene rubber liquid reaches the required set amount, and the concentrated polyethylene-butene rubber liquid enters the inlet of the twin-screw extruder from the bottom of the falling film evaporation tower. The concentrated polyethylene-butene rubber liquid is heated and evaporated in the extrusion chamber of the twin-screw extruder. The evaporated solvent is forcibly extracted from the gas phase outlet of the twin-screw extruder by the vacuum pump and first enters the front condenser. The condensed solvent is recovered and enters the front condensation tank. The uncondensed small amount of solvent or water is sent to the rear condenser by the Roots vacuum pump, and the condensed solvent is recovered and enters the rear condensation tank. The polymer melt after devolatilization is transported to the finished product silo through twin-screw extrusion, underwater pelletizing, centrifugal dehydration, and vibration screen to obtain polymer pellets.

[0069] Example 1

[0070] 5m under nitrogen protection 3 Add 0.8 L of 12.5% ​​tetrahydrofurfuryl alcohol ethyl ether (ETE) and 3 mL of cyclohexane into the polymerization kettle. 3 , start stirring and raise the material temperature to 58°C, then add 8.0L of 0.6mol / L NBL to the polymerization kettle, and continuously and evenly add a mixed solution consisting of 130mL of divinylbenzene and 450L of butadiene within 30min. After the addition of the materials, react for another 30min, maintaining the polymerization temperature at 70°C to obtain BR glue solution. The GPC and H 1 -NMR spectrum attached Figure 1 and attached Figure 2 .

[0071] The glue liquid was pressed into a hydrogenation kettle with nitrogen, and 4L of 0.6mol / L NBL, 4L of 0.02mol / L cyclohexane solution of dimethyl phthalate and methyl o-toluate (cocatalyst, the molar ratio of the two was 1:1), and 10.5g of dicyclopentadiene titanium dichloride were added, and stirred for hydrogenation for 80min under 14bar hydrogen pressure; then 3L of cocatalyst was added, and hydrogenation was carried out for 70min under the same hydrogen pressure. The unsaturation of the polymer was measured by nuclear magnetic hydrogen spectroscopy and was 0.33% (moL), and the EBBR glue liquid was obtained.

[0072] Selection Figure 1 EBBR dry devolatilization equipment is used to devolatilize EBBR glue.

[0073] The falling film evaporation tower is set with an inner diameter of 0.4m and a height of 4.8m. It is equipped with an external jacket for steam heating. The chord center point of the sieve plate is 90mm away from the falling film evaporation tower wall. The diameter of the sieve holes on the sieve plate is Φ7mm, the spacing between the holes is 15mm, and the spacing between the upper and lower sieve plates is 350mm.

[0074] The twin-screw devolatilizer is TSD-65 manufactured by Jiangsu Chengmeng Equipment Co., Ltd. The main motor is 55kw, the maximum output speed is 300rpm, the screw outer diameter is Φ61.5mm, and the barrel inner diameter is The screw length-to-diameter ratio L / D=42, and the barrel is composed of 8 sections connected in series, including 5 sections of vacuum exhaust barrels.

[0075] The heat transfer area of ​​the condenser used for solvent recovery is 4m 2 Other equipment are designed and manufactured according to standards.

[0076] First, the falling film evaporator was preheated to about 85°C with 1.3 bar steam, and then 1000 L / h of EBBR glue solution with a mass fraction of 10.68% was delivered to the distributor at the top of the falling film evaporator by a screw pump. The pressure in the tower was maintained at normal pressure and the temperature was 85°C. The evaporated cyclohexane gas was recovered by entering the condenser from the top of the tower, and the concentration of the pre-concentrated glue melt entering the twin-screw inlet from the bottom of the tower was 50.6% (mass fraction).

[0077] The temperatures of the feed inlet, zones 1, 2, 3, 4, 5, 6, 7, 8 and the die of the TSD-65 devolatilizer were set to 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C and 170°C, respectively; five gas phase outlets were provided in zones 4, 5, 6, 7 and 8, the screw speed was 200rpm, the melt residence time was 170S, and the die pressure was 3.8MPa; the suction vacuum of the Roots aspirator was -0.40bar; each condenser was cooled with circulating water at 20°C; and the underwater pelletizer was cooled with circulating water at about 20°C.

[0078] As a result, 283.3 kg of EBBR pellets were produced. The appearance of the prepared EBBR (designated as EBBR-1) was transparent columnar pellets. The behavior parameters of the raw rubber and hydrogenated rubber are shown in Table 1. Among them, the GPC of the raw rubber of EBBR-1 and the H 1 -NMR spectra are attached Figure 1 , Figure 2 and Figure 3 .

[0079] Example 2

[0080] The relevant process conditions in Example 1 remain unchanged, except that the total amount of 0.6 mol / L NBL is changed to 7.2 L, and the amount of ETE with a mass fraction of 12.5% ​​is changed to 0.65 L.

[0081] Results The prepared EBBR was designated as EBBR-2, and the behavior parameters of the raw materials and hydrogenated rubber are shown in Table 1.

[0082] Example 3

[0083] The relevant process conditions in Example 1 remain unchanged, and only the total amount of 0.6 mol / L NBL is changed to 6.6 L, and the amount of ETE with a mass fraction of 12.5% ​​is changed to 0.42 L.

[0084] The prepared EBBR was designated as EBBR-3. The behavior parameters of the original rubber and hydrogenated rubber are shown in Table 1.

[0085] Example 4

[0086] The relevant process conditions in Example 1 remain unchanged, except that the total amount of 0.6 mol / L NBL is changed to 9.2 L, and the amount of ETE with a mass fraction of 12.5% ​​is changed to 0.35 L. The prepared EBBR is designated as EBBR-4.

[0087] Results: The rubber solution condensed into wax at 18°C ​​and lost fluidity. The pelletized rubber slightly agglomerated at room temperature. Other behavioral parameters of the original rubber and hydrogenated rubber are shown in Table 1.

[0088] Example 5

[0089] The relevant process conditions in Example 1 were kept unchanged, except that the total amount of 0.6 mol / L NBL was 6.2 L, the amount of ETE with a mass fraction of 12.5% ​​was 1.05 L, and the material addition time was 40 min. The prepared EBBR was designated as EBBR-5.

[0090] Results: The pelletized rubber completely agglomerated at room temperature. Other behavior parameters of the original rubber and hydrogenated rubber are shown in Table 1.

[0091] Table 1 Characteristic analysis of original rubber BR and hydrogenated rubber EBBR in the examples

[0092]

[0093]

[0094] Note: "Sticky to the finger" means that the pellets have a slightly sticky feeling to the fingers.

[0095] Example 6

[0096] EBBR-1, EBBR-2, EBBR-3 in Table 1 and DOW 3720P with a Mooney viscosity of 20 and DOW 3745P with a Mooney viscosity of 45 are used to prepare PP / EBBR alloy according to the toughened modified polypropylene formula of the present invention. The preparation method is to mix the respective formula materials in a mixer at room temperature for 2 minutes, and then put them into a twin-screw extruder at 160-190°C for a residence time of not less than 3 minutes for mixing, micro-crosslinking, extrusion, and pelletizing to prepare PP / EBBR modified alloy. The physical properties of each type of modified material are shown in Table 2.

[0097] Table 2 Physical properties of PP and PP / EBBR modified alloys

[0098]

[0099] Note: (1) "【1】" is PP; "【2】" formula is K9015 100 parts, EBBR-125 parts, BIPB 0.12. (2) Other sample formulas: K9015 100 parts, EBBR / DOW 25 parts, light calcium carbonate 50 parts, crosslinking agent BIPB 0.12, antioxidant 10100.3 parts. (3) K9015 is PP, MFR is 15-17g / 10min.

Claims

1. A method for preparing transparent polyethylene-butylene rubber pellets, characterized in that: The following steps are involved: 1) obtaining a polybutadiene raw rubber solution by an anionic polymerization method of butadiene monomer; 2) the polybutadiene raw rubber solution is subjected to catalytic hydrogenation to obtain polyethylene-butylene rubber solution; 3) After the polyethylene-butylene rubber solution is concentrated by falling film evaporation, it is deeply devolatilized and extruded into granules by twin-screw extrusion.

2. The method for preparing a transparent polyethylene-butylene rubber granule according to claim 1, characterized in that: In step 1), after the cyclohexane solution containing the structure regulator is heated to the temperature required for initiating polymerization, alkyl lithium, butadiene and a branching agent are continuously and evenly added to initiate and carry out polymerization reaction, thereby obtaining a polybutadiene raw rubber solution.

3. The method for preparing a transparent polyethylene-butylene rubber granule according to claim 2, characterized in that: The concentration of the structure regulator is 50-60 mg / Kg solvent; The structure regulator is selected from at least one of tetrahydrofurfuryl alcohol ethyl ether, ditetrahydrofurfuryl propane, tetrahydrofurfuryl alcohol butyl ether and tetrahydrofurfuryl alcohol hexyl ether; The branching agent is divinylbenzene; The mass of the branching agent is 0.03-0.04% of the mass of the butadiene monomer; The mass fraction of the butadiene monomer in the cyclohexane solution is 10-12%; The molecular ratio of the butadiene monomer to the alkyl lithium is (7-8)×10 4 .

4. The method for preparing a transparent polyethylene-butylene rubber granule according to claim 2, characterized in that: The temperature required to initiate the polymerization reaction is 58-65°C, and the maximum temperature during the polymerization reaction is no higher than 75°C.

5. The method for preparing a transparent polyethylene-butylene rubber granule according to claim 1, characterized in that: In step 2), the conditions of the catalytic hydrogenation reaction are: alkyl lithium as an activator, dimethyl phthalate and methyl o-toluate as co-catalysts, dicyclopentadiene titanium dichloride as a main catalyst, a hydrogen pressure of 13 to 16 bar, a temperature of 75 to 110° C., a total hydrogenation time of not less than 150 min, and a hydrogenation endpoint of a polymer unsaturation of 0.30 to 0.40%.

6. The method for preparing a transparent polyethylene-butylene rubber granule according to claim 5, characterized in that: The main catalyst is used in an amount of 0.030 to 0.040 g / kg polymer; The molar ratio of the main catalyst to the co-catalyst is 3 to 8:1; The molar ratio of the alkyl lithium to the co-catalyst is 6 to 12:

1.

7. The method for preparing a transparent polyethylene-butylene rubber granule according to any one of claims 1 to 6, characterized in that: In step 3), the polyethylene-butene rubber solution is sent to a falling film evaporation tower for preliminary evaporation, and the gas obtained by evaporation enters a condenser from the top of the falling film evaporation tower for condensation, and the solvent is recovered; the concentrated polyethylene-butene rubber solution obtained by evaporation enters a twin-screw extruder from the bottom of the falling film evaporation tower, and the concentrated polyethylene-butene rubber solution is heated and volatilized in the twin-screw extruder, and the volatilized gas is sequentially drawn into a front condenser and a rear condenser for condensation, and the solvent is recovered; the polymer melt obtained by volatilizing the solvent is subjected to screw extrusion, underwater pelletizer pelletizing and centrifugal dehydrator dehydration to obtain finished rubber particles.

8. The method for preparing a transparent polyethylene-butylene rubber granule according to claim 7, characterized in that: The falling film evaporation tower is a vertical structure with an aspect ratio of L / D=10-15. A plurality of semi-circular sieve plates are arranged on the vertical inner wall of the falling film evaporation tower. The distance between the chord center point of the semi-circular sieve plate and the inner wall of the tower is 1 / 5-1 / 4 of the diameter of the falling film evaporation tower. Any two adjacent semi-circular sieve plates are evenly arranged in reverse symmetry, and the spacing between any two adjacent semi-circular sieve plates is 300-350 mm. Sieve holes with a diameter of Φ=7-12 mm are evenly distributed on the semi-circular sieve plates, and the center distance between any two adjacent sieve holes is 16-24 mm.

9. The method for preparing a transparent polyethylene-butylene rubber granule according to claim 7 or 8, characterized in that: The polyethylene-butene rubber solution is fed into the top of the falling film evaporation tower, and after being evenly distributed by the distributor, it is evenly distributed on the first layer of semi-circular sieve plates to form a film layer. Under the action of heating and gravity, the solvent in the film layer evaporates, and at the same time, the thin rubber solution with part of the evaporated solvent flows to the next layer of semi-circular sieve plates to continue evaporating, and this cycle is repeated to control the solid content of the concentrated rubber solution entering the twin-screw extruder to be 50-60%; the solid content of the thin rubber solution is 12-14%.

10. The method for preparing a transparent polyethylene-butylene rubber granule according to claim 9, characterized in that: The steam pressure in the falling film evaporation tower is 1-2 bar, the temperature is 80-90° C., and the operating pressure in the falling film evaporation tower is normal pressure.

11. The method for preparing a transparent polyethylene-butylene rubber granule according to claim 7, characterized in that: The total screw length-to-diameter ratio of the twin-screw extruder is L / D=42-58, and the extrusion chamber is divided into 9 sections from the inlet to the die; among them, the screw length-to-diameter ratio of the first section is L / D=10-12, the screw length-to-diameter ratios of the second, third, fourth, fifth, sixth, seventh, and eighth sections are all L / D=4-5, and gas phase outlets are provided in the fourth, fifth, sixth, seventh, and eighth sections.

12. A method for preparing a transparent polyethylene-butylene rubber granule according to claim 7 or 11, characterized in that: The parameters of the twin-screw extruder are controlled as follows: die head pressure 3.0-5.0 MPa, die head temperature 160-170°C, the temperature of each section is distributed from low to high, the temperature range of each section is 80-185°C, the extruder speed is 90-150 r / min, and the melt residence time is 3-5 min.

13. The method for preparing a transparent polyethylene-butylene rubber granule according to claim 1, characterized in that: The gas volatilized by heat in the twin-screw extruder is extracted by a Roots vacuum machine and sequentially enters the front condenser and the rear condenser for condensation. The vacuum degree in the extrusion chamber of the twin-screw extruder is -0.3 to -0.5 bar.

14. The transparent polyethylene-butylene rubber granules according to claim 1, characterized in that: The method is obtained by any one of claims 1 to 13.

15. The use of a transparent polyethylene-butylene rubber granule according to claim 14, characterized in that: Used to toughen and modify polyolefin resins.

Images