Transparent polyethylene-butene rubber pellets, process for their preparation and use

Abstract

The application discloses transparent polyethylene-butylene rubber granules, a preparation method and application thereof. Butadiene monomers are obtained by an anionic polymerization method to obtain BR raw glue liquid, and the BR raw glue liquid is subjected to catalytic hydrogenation to obtain polyethylene-butylene glue liquid; after the polyethylene-butylene glue liquid is concentrated by falling film evaporation, the transparent glue particles (EBBR) with a volatile matter content of less than or equal to 0.35% (mass fraction) are obtained by deep devolatilization and extrusion granulation through a double screw extruder, the EBBR has the characteristics of a wide molecular weight, non-crystallization, good elasticity, high strength and low volatile matter, and has excellent physical properties after being blended with PP and vulcanized, and simultaneously has good processing performance.

Description

Technical Field

[0001] This invention relates to a transparent polyethylene-butene rubber granule, as well as its preparation method and its application as a toughening agent for polyolefin resins, belonging to the field of synthetic rubber technology. Background Technology

[0002] Existing polybutadiene rubber (BR-9000), lithium-based styrene-conjugated diene elastomers (SBC), K-resins, and ethylene propylene rubber all employ solution polymerization, with solvents typically including hexane and cyclohexane. BR-9000, rare-earth BR, rare-earth IR, and SBC usually utilize wet steam condensation to remove the solvent from the polymer. However, for styrene-butadiene copolymer transparent resins and polyolefin elastomers (POE) with hardness higher than 60A, dry methods are used to remove the solvent from the polymer.

[0003] Wet devolatilization involves post-processing equipment such as water vapor condensation, solvent recovery and refining, particle extrusion dehydration, and drying. However, for polymers with a wide molecular weight distribution, issues like sticking, clumping, and equipment blockage can occur in the condensation tank, conveying machinery, pipelines, and drying oven. Wet devolatilization suffers from drawbacks such as numerous equipment requirements, long process flow, large footprint, poor operating environment, wastewater generation, high energy consumption, and high investment. Furthermore, for polymers requiring high transparency and containing water, the products from wet devolatilization fall far short of modern consumer needs.

[0004] Ethylene propylene diene monomer (EPDM) rubber possesses excellent chemical resistance, ozone resistance, aging resistance, and electrical insulation properties, making it widely used in building waterproof membranes, automotive seals, heat-resistant hoses and tapes, wire and cable conduits, lubricant additives, and polyolefin modification. Solution polymerization is currently the dominant technology for EPDM production worldwide. Post-processing technologies mainly include wet devolatilization and dry devolatilization. Wet devolatilization is a traditional rubber post-processing technique, previously used by companies such as DSM, JSR, and Exxon. However, with the development of dry technology in recent years, newly built EPDM plants by companies such as DOW Chemical, Mitsui Chemicals, and Exxon-Mobile, especially in the production of titanium-based catalytic hydrogenated rubber, have adopted dry devolatilization. Compared to wet devolatilization, dry devolatilization offers advantages such as a shorter process flow, fewer equipment requirements, a cleaner operating environment, and no wastewater generation due to direct flash evaporation and extrusion solvent removal, resulting in lower energy consumption. However, it requires highly sophisticated technology and equipment. Currently, China lacks the capability and experience to manufacture large-scale dry devolatilization equipment. For example, the article "Research on Dry Devolatilization Process of Ethylene Propylene Rubber, Elastomers, 2013.12" introduces a 200t / a pilot plant for ethylene propylene rubber built by the Jilin Petrochemical Company Research Institute. The post-processing of this plant adopts the dry devolatilization technology of NFM in the United States, which includes four parts: heating system, vacuum system, flash evaporation system and extrusion system. However, the main core equipment parameters of this plant are not disclosed.

[0005] In recent years, with economic development, the annual consumption of EPDM / PP composite materials for automotive bumpers and dashboards has reached 600,000 to 700,000 tons. However, there are no literature reports on the application of polyolefin resin modified with transparent polyethylene-butene rubber granules. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a transparent polyethylene-butene rubber granule (EBBR). This EBBR has the characteristics of wide molecular weight range, non-crystallization, good elasticity, high strength and low volatile content. It has excellent physical properties after being blended and vulcanized with PP, and also exhibits good processing performance.

[0007] The second objective of this invention is to provide a method for preparing transparent polyethylene-butene rubber granules. The granules prepared by this method have a volatile content of ≤0.35% (mass fraction). The preparation method is simple, low in cost, and can be produced using existing mature equipment and processes, making it easy to industrialize.

[0008] A third objective of this invention is to provide an application of transparent polyethylene-butene rubber granules for toughening and modifying downstream polyolefin resins, which can improve the overall physical properties of polyolefin resins.

[0009] To achieve the above-mentioned technical objectives, the present invention provides a method for preparing transparent polyethylene-butene rubber granules, which includes the following steps:

[0010] 1) Butadiene monomer was polymerized by anionic polymerization to obtain polybutadiene raw material;

[0011] 2) The polybutadiene raw material is catalytically hydrogenated to obtain a polyethylene-butene raw material;

[0012] 3) After the polyethylene-butene adhesive is concentrated by falling film evaporation, it is subjected to deep devolatilization and extrusion granulation by twin-screw extrusion.

[0013] The technical solution of this invention adopts a combination process of pre-concentration in a falling film evaporator and volatilization in a twin-screw extruder for polyethylene-butene adhesive. The pre-concentration process in the falling film evaporator can avoid the formation of glue residue and agglomeration in high melt index polymer adhesives, and can efficiently and continuously pre-concentrate the dilute adhesive. The twin-screw extruder can achieve deep volatilization, which can ensure that the w (total volatile matter) of the extruded sample is <0.5%, avoiding the impact of residual solvent on the transparency of the polymer. At the same time, the twin-screw extruder has the characteristics of high production capacity.

[0014] As a preferred embodiment, in step 1), after heating the cyclohexane solution containing the structure modifier to the temperature required to initiate polymerization, alkyl lithium, butadiene, and branching agent are continuously and uniformly added to initiate and carry out the polymerization reaction, thereby obtaining polybutadiene raw rubber solution.

[0015] As a preferred embodiment, the concentration of the structure modifier is 50–60 mg / kg solvent.

[0016] As a preferred embodiment, the structure modifier is selected from at least one of tetrahydrofurfuryl ethyl ether, bis(tetrahydrofurfuryl propane), tetrahydrofurfuryl butyl ether, and tetrahydrofurfuryl ethyl ether. Selecting a suitable structure modifier and controlling its appropriate dosage can effectively adjust the ratio of 1,2 polymeric units in polybutadiene.

[0017] As a preferred embodiment, the branching agent is divinylbenzene. As a preferred embodiment, the mass of the branching agent is 0.03–0.04% of the mass of the butadiene monomer. Introducing an appropriate amount of divinylbenzene as a branching agent can effectively expand the molecular weight distribution. If the proportion of the branching agent is too low, the effect of expanding the molecular weight distribution will not be achieved; if the proportion of the branching agent is too high, a macromolecular gel will be formed.

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

[0019] As a preferred embodiment, the molecular ratio of butadiene monomer to alkyl lithium is (7-8) × 10⁻⁶.4 The amount of alkyl lithium used is determined based on the designed molecular weight, which is well known in the industry. Butyl lithium is a common type of alkyl lithium.

[0020] As a preferred option, the temperature required to initiate the polymerization reaction is 58–65°C, and the maximum temperature during the polymerization reaction does not exceed 75°C.

[0021] As a preferred method, alkyl lithium and butadiene are continuously and uniformly fed with the branching agent within 30 to 40 minutes, which can ensure that the polymer exhibits a medium molecular weight distribution. If the time is too long, the molecular weight distribution will be too wide; if the time is too short, the molecular weight distribution will be too narrow.

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

[0023] As a preferred embodiment, the amount of the main catalyst is 0.030 to 0.040 g / kg polymer.

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

[0025] As a preferred embodiment, the molar ratio of the alkyllithium to the cocatalyst is 6 to 12:1.

[0026] By employing preferred hydrogenation catalysts and hydrogenation reaction conditions, this invention ensures that the hydrogenation effect of polybutadiene virgin rubber remains at a high level.

[0027] As a preferred embodiment, the catalytic hydrogenation reaction process is as follows: first, alkyl lithium and a portion of the co-catalyst are added for activation, then the main catalyst is added, and the reaction is carried out for 70 to 90 minutes under conditions of hydrogen pressure of 13 to 16 bar and temperature of 75 to 110 °C; then, a portion of the co-catalyst is added, and hydrogenation continues for 60 to 80 minutes, with a total hydrogenation time of not less than 150 minutes.

[0028] As a preferred embodiment, in step 3), the polyethylene-butene rubber solution is fed into a falling film evaporator for preliminary evaporation. The gas obtained from evaporation enters a condenser from the top of the falling film evaporator for condensation and solvent recovery. The concentrated polyethylene-butene rubber solution obtained from evaporation enters a twin-screw extruder from the bottom of the falling film evaporator. The concentrated polyethylene-butene rubber solution is heated and volatilized in the twin-screw extruder. The gas obtained from volatilization is sequentially drawn into a pre-condenser and a post-condenser for condensation and solvent recovery. The polymer melt obtained from solvent volatilization is extruded by a screw extruder, pelletized by an underwater pelletizer, and dehydrated by a centrifugal dewatering machine to obtain finished rubber granules. More specifically, the technical solution of this invention involves feeding polyethylene-butene adhesive solution into a falling film evaporator. The solution is distributed by a distributor located at the top of the evaporator, forming a thin layer on a semi-circular sieve plate within the tower. The evaporator is then heated by steam using a jacket, causing a large amount of solvent in the polyethylene-butene adhesive solution to evaporate. Simultaneously, the partially solvent-free solution flows under gravity to the next semi-circular sieve plate for further solvent evaporation. This process is repeated, and the evaporated gas... (Including solvent gas or water vapor formed from moisture used for terminating the adhesive solution) After being condensed in the condenser, the liquid enters the condenser tank until the solid content of the adhesive solution reaches the required set amount. The concentrated polyethylene-butene adhesive solution enters the inlet of the twin-screw devouring extruder from the bottom of the falling film evaporator. The concentrated polyethylene-butene adhesive solution is heated in the twin-screw extruder, and the residual solvent in the concentrated adhesive solution is forcibly extracted from the gas phase outlet of the twin-screw extruder under certain temperature and vacuum conditions and enters the pre-condenser. The condensed solvent enters the pre-condenser tank, and the small amount of uncondensed solvent or water is sent to the post-condenser by the Roots vacuum pump. The condensed solvent enters the post-condenser tank. At the same time, the polyethylene-butene melt that has been desolventized is extruded by the twin-screw extruder, underwater pelletized, centrifuged and dehydrated, and conveyed to the finished product silo by a vibrating screen to obtain the pellets.

[0029] As a preferred embodiment, the falling film evaporator is a vertical structure with a length-to-diameter ratio (L / D) of 10–15. The inner wall of the falling film evaporator is equipped with multiple large semi-circular sieve plates. The distance from the chord center of each semi-circular sieve plate to the inner wall is 1 / 5 to 1 / 4 of the diameter of the falling film evaporator. Any two adjacent large semi-circular sieve plates are arranged in a reverse symmetrical and uniform manner, with a spacing of 300–350 mm between them. It is worth further noting that the falling film evaporator employs a multi-layer sieve plate structure. Under gravity, the adhesive gradually evaporates in a thin layer on the sieve plates from top to bottom without boiling over. The adhesive gradually concentrates as it flows from top to bottom, resulting in a short residence time and preventing overheating. This avoids plasticization of the adhesive under prolonged or overheated conditions. Furthermore, the concentration of the adhesive using a falling film evaporator allows for continuous operation, and the solid content of the adhesive can be adjusted arbitrarily, which is beneficial for large-scale production and operation.

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

[0031] As a preferred embodiment, the polyethylene-butene rubber solution is fed into the top of a falling film evaporator. After being evenly distributed by a distributor, it forms a film layer on the first semi-circular sieve plate. Under the action of heating and gravity, the solvent in the film layer evaporates, and the diluted rubber solution with partially evaporated solvent flows to the next semi-circular sieve plate for further evaporation. This process is repeated to control the solid content of the concentrated rubber solution entering the twin-screw extruder to be 50-60%, and the solid content of the diluted rubber solution to be 12-14%. If the solid content of the concentrated polyethylene-butene rubber solution is too low, the subsequent twin-screw extruder will have an excessively high processing load, resulting in low efficiency in vacuum extraction of solvent and condensation recovery. If the solid content of the concentrated polyethylene-butene rubber solution is too high or the melt conveying temperature is too low, the melt flow performance will be poor, making conveying difficult and hindering entry into the twin-screw devouring extruder. The solvent used for the polyethylene-butene rubber solution is cyclohexane (boiling point 80℃, and azeotropic with water). Traditional intermittent autoclave evaporation and concentration methods are inefficient. The polymer is first heated on the jacketed heating vessel wall or the surface of the heated coil, and is heated for a long time, which causes the double bonds in the polymer molecules to undergo thermal polymerization, resulting in cross-linking and gelation. At the same time, it is not conducive to continuous dry devolatilization.

[0032] As a preferred embodiment, the steam pressure inside the falling film evaporator is 1-2 bar, the temperature is 80-90°C, and the operating pressure inside the falling film evaporator is atmospheric pressure.

[0033] As a preferred embodiment, the twin-screw extruder has a total screw length-to-diameter ratio (L / D) of 42 to 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 10 to 12, the screw length-to-diameter ratio of the second, third, fourth, fifth, sixth, seventh, and eighth sections is 4 to 5, and the fourth, fifth, sixth, seventh, and eighth sections are all provided with gas phase outlets.

[0034] As a preferred embodiment, 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 from low to high in each section ranging from 80–185°C, extruder speed 90–150 r / min, and melt residence time 3–5 min. This preferred parameter control ensures that the w (total volatile matter) of the extruded sample is <0.5%.

[0035] As a preferred embodiment, the gases volatilized by heat in the twin-screw extruder are extracted by a Roots vacuum pump and sequentially condensed in the pre-condenser and post-condenser. The vacuum level inside the extrusion chamber of the twin-screw extruder is -0.3 to -0.5 bar. If the vacuum level is too high, the solvent is not easily condensed and recovered from the condenser. Using a Roots vacuum pump to remove the small amount of solvent gas removed from the twin-screw extruder will not damage the Roots vacuum pump. However, using a commonly used vacuum pump to pump out gases and small amounts of moisture can damage the vacuum pump piston.

[0036] As a preferred embodiment, the heat transfer medium used in both the pre-condenser and post-condenser is industrial water at 5–20°C. Both the pre-condenser and post-condenser operate at atmospheric pressure. Each is equipped with a condenser tank. Both the condenser and condenser tank are equipment well-known to those skilled in the chemical industry.

[0037] The underwater pelletizer of this invention uses cooling water that is reused through a circulation system, and the recovered solvent is sent to the polymerization unit for recycling.

[0038] The falling film evaporator of this invention uses a jacketed steam heating system.

[0039] The twin-screw extruder of this invention is derived from the continuous horizontal devouring extruder of Jiangsu Chengmeng Equipment Company.

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

[0041] The underwater pelletizer, granule centrifugal dewatering machine, vibrating screen, finished product silo, and water circulation system of this invention are all equipment well-known to those in the chemical industry.

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

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

[0044]

[0045] in,

[0046] x, y, m, and n represent the degree of polymerization, where x, y, m, and n are all integers greater than or equal to 0. The ratio of the degree of polymerization of saturated "CC" units to unsaturated "C=C" units is (y+n) / (x+m) = 25–35; the degree of unsaturation 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 this invention can control the formation of polymer crystals, prevent the polymer from losing elasticity, ensure that the polymer has suitable elastic recovery and strength, and has good flexibility when combined with polyolefin resin.

[0048] The EBBR of this invention has a low degree of unsaturated double bonds, which is beneficial for forming micro-crosslinks with crosslinking agents, thereby improving the elastic modulus and anti-aging properties of the composite material. The greater the number of uncrosslinked double bonds, the worse the anti-aging properties of the composite material. This is why the EBBR of this invention is designed to have a low degree of unsaturation.

[0049] The preferred Mooney viscosity (ML / 125°C) of the EBBR of this invention is 18–24; the molecular weight distribution is moderate, M w / M n =1.4~1.6. If the Mooney viscosity is too high, melt fracture will occur during extrusion when blended with polyolefin resin, resulting in defects in the product. It is more suitable if the melting temperatures of the polymer and polyolefin are not too different.

[0050] This invention also provides an application of transparent polyethylene-butene rubber granules, which are used to toughen and modify polyolefin resins. The polyolefin is, for example, PP.

[0051] This invention relates to a formulation and method for preparing granules using EBBR granules to modify and toughen polypropylene (PP / EBBR):

[0052] The PP / EBBR granule formulation is as follows: 100 parts PP, 20-30 parts EBBR, 50-60 parts light calcium carbonate, 0.12-0.15 parts BIPB crosslinking agent, and 0.2-0.5 parts 1010 antioxidant.

[0053] PP / EBBR granules can be prepared using traditional methods known to those skilled in the art, such as dry mixing, twin-screw extrusion, vulcanization crosslinking, and extrusion granulation. For example, light calcium carbonate can be omitted when preparing colorless and transparent PP / EBBR granules; however, light calcium carbonate and colorants can be added to reduce costs and produce colored products. PP / EBBR granules can be used in automotive interior trim parts, such as bumpers, dashboards, and appliance housings.

[0054] Compared with existing technologies, the beneficial effects of the technical solution of this invention are as follows:

[0055] The EBBR provided by this invention has a short polymerization time and controllable molecular weight distribution during the preparation of its original BR. It can be synthesized using existing mature anionic polymerization technology, which is simple and conducive to industrial production. Furthermore, the synthesized original BR is hydrogenated to the maximum extent by existing titanium-ceramic catalysts, retaining a low degree of unsaturation. After a small amount of double bond crosslinking, the comprehensive physical properties of the composite material can be improved.

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

[0057] The EBBR granule preparation process provided by this invention adopts falling film evaporation and twin-screw extrusion for synergistic devolatilization, which can efficiently obtain high-quality transparent granules with a polymer volatile content ≤0.5% (mass fraction), and an appearance of granules or cobblestone granules. It also has good processing performance and is convenient for downstream processing applications.

[0058] The EBBR prepared by this invention has the characteristics of wide molecular weight range, non-crystallization, good elasticity, high strength and low volatile content. It has excellent physical properties after being blended with PP and vulcanized, and also exhibits good processing performance.

[0059] The EBBR preparation process of this invention is a homogeneous reaction, simple to prepare, and can be synthesized using existing mature processes, making it easy to control and industrialize. Attached Figure Description

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

[0061] Figure 2 H is the hydrogenated polymer EBBR-1# raw rubber BR 1 -NMR.

[0062] Figure 3 H for hydrogenated polymer EBBR-1# 1 -NMR.

[0063] Figure 4 The present invention provides a combined dry devolatilization process using falling film evaporation and twin-screw extrusion. Detailed Implementation

[0064] The following examples are intended to further illustrate and describe the content of the present invention, and do not constitute a limitation on 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 using gel permeation chromatography (GPC); H2 was used. 1 - The microstructure of the polymer was quantitatively determined by NMR spectroscopy; the mechanical properties of the raw rubber and blended alloys were tested according to the method of GB / T36089-2018.

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

[0067] The devolatilization process of this invention mainly includes a falling film evaporation unit and a granulation unit. The falling film evaporation unit mainly consists of a falling film evaporation tower, a condenser, and a condensation tank. The granulation unit includes a twin-screw extruder, an underwater pelletizer, a pellet centrifugal dewatering machine, a vibrating screen, a finished product silo, and a water circulation system. The twin-screw extruder also has a solvent recovery assembly, including a pre-condenser, a pre-condensation tank, a vacuum pump, a post-condenser, and a post-condensation tank.

[0068] The specific devolatilization process of the high melt flow index and high transparency lithium-based polymer adhesive of this invention is as follows: Polyethylene-butene adhesive is fed into the falling film evaporator from the top. Under pressure, it is distributed through an adhesive distributor, forming a thin layer evenly distributed on the first semi-circular sieve plate within the falling film evaporator. The falling film evaporator is heated by jacketed steam, causing a large amount of solvent in the polyethylene-butene adhesive to evaporate. Simultaneously, the polyethylene-butene adhesive flows to the next semi-circular sieve plate under gravity to continue solvent evaporation. This process is repeated. The evaporated solvent gas or adhesive is then removed by water vaporization. Water vapor is output from the top of the falling film evaporator. After condensation in the condenser, the liquid is recovered and sent to the condenser tank. This process continues until the solid content of the polyethylene-butene rubber solution reaches the required set amount. Meanwhile, the concentrated polyethylene-butene rubber solution enters the inlet of the twin-screw extruder from the bottom of the falling film evaporator. The concentrated polyethylene-butene rubber solution 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 a vacuum pump and first enters the pre-condenser. The condensed solvent is recovered and sent to the pre-condenser tank. The small amount of uncondensed solvent or water is sent to the post-condenser by a Roots vacuum pump. The condensed solvent is recovered and sent to the post-condenser tank. The devolatilized polymer melt is then extruded by a twin-screw extruder, underwater pelletized, centrifuged for dehydration, and conveyed to the finished product silo by a vibrating screen to obtain polymer granules.

[0069] Example 1

[0070] 5m under nitrogen protection 3 0.8 L of tetrahydrofurfuryl ethyl ether (ETE) with a mass fraction of 12.5% ​​and 3 mL of cyclohexane were added to the polymerization reactor. 3 Start stirring and heat the material to 58°C. Then, add 8.0 L of 0.6 mol / L NBL to the polymerization reactor. Simultaneously, over 30 minutes, continuously and uniformly add a mixed solution consisting of 130 mL of divinylbenzene and 450 L of butadiene. After the addition is complete, continue reacting for another 30 minutes, maintaining the polymerization temperature at 70°C to obtain the BR resin. The original BR resin exhibits GPC and H... 1 -NMR spectrum attached Figure 1 and attached Figure 2 .

[0071] The adhesive solution was pressurized into a hydrogenation reactor under nitrogen pressure, and then 4 L of 0.6 mol / L NBL, 4 L of a cyclohexane solution containing 0.02 mol / L dimethyl phthalate and methyl o-methyl benzoate (co-catalyst, molar ratio 1:1), and 10.5 g of dicyclopentadiene titanium dichloride were added. The mixture was stirred and hydrogenated at 14 bar for 80 min. Then, 3 L of co-catalyst was added, and hydrogenation was carried out for 70 min under the same hydrogen pressure. The unsaturation degree of the polymer was measured to be 0.33% (mol / L) by 1H NMR spectroscopy, thus obtaining the EBBR adhesive solution.

[0072] Select Figure 1 The EBBR dry devolatilization equipment is used to devolatilize EBBR adhesive.

[0073] The falling film evaporator has 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 of the sieve plate is 90mm away from the wall of the falling film evaporator. The diameter of the sieve holes on the sieve plate is Φ7mm, the spacing between the holes is 15mm, and the distance between the upper and lower sieve plates is 350mm.

[0074] The twin-screw top-rotor washer selected is the TSD-65 model manufactured by Jiangsu Chengmeng Equipment Co., Ltd., with a main motor of 55kw and a maximum output speed of 300rpm. The screw outer diameter is Φ61.5mm, and the barrel inner diameter is [not specified]. The screw has a length-to-diameter ratio of L / D = 42, and the barrel consists of 8 sections connected in series, including 5 sections of vacuum exhaust barrel.

[0075] The heat transfer area of ​​the condensers used for solvent recovery is 4m². 2 All other equipment is standardized and manufactured according to specifications.

[0076] First, the falling film evaporator is preheated to about 85°C using steam at 1.3 bar. Then, 1000 L / h of EBBR adhesive solution with a mass fraction of 10.68% is pumped into the distributor at the top of the falling film evaporator using a screw pump. The pressure inside the tower is maintained at atmospheric pressure and the temperature at 85°C. The evaporated cyclohexane gas enters the condenser from the top of the tower for recovery. The pre-concentrated adhesive melt concentration entering the twin-screw inlet from the bottom of the tower is 50.6% (mass fraction).

[0077] The temperatures of the TSD-65 devolatilizer's feed inlet, zones 1, 2, 3, 4, 5, 6, 7, 8, and die head are set to 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, and 170℃, respectively. Zones 4, 5, 6, 7, and 8 are each equipped with five gas phase outlets. The screw speed is 200 rpm, the melt residence time is 170 s, and the die head pressure is 3.8 MPa. The suction vacuum of the Roots suction machine is -0.40 bar. Each condenser is cooled with 20℃ circulating water. The underwater pelletizer is cooled with approximately 20℃ circulating water to produce melt pellets.

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

[0079] Example 2

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

[0081] The resulting EBBR was labeled as EBBR-2, and the behavior parameters of the raw materials and hydrogenated gel are shown in Table 1.

[0082] Example 3

[0083] The relevant process conditions in Example 1 were kept unchanged, except that the total amount of 0.6 mol / L NBL was changed to 6.6 L and the amount of 12.5% ​​ETE was changed to 0.42 L.

[0084] The resulting EBBR was labeled as EBBR-3. The behavioral parameters of the virgin and hydrogenated EBBR are shown in Table 1.

[0085] Example 4

[0086] The relevant process conditions in Example 1 were kept unchanged, except that the total amount of 0.6 mol / L NBL was changed to 9.2 L and the amount of 12.5% ​​ETE was changed to 0.35 L. The prepared EBBR was labeled as EBBR-4.

[0087] Results: The glue solution solidified into a waxy state at 18℃ and lost its fluidity. The pelletized glue showed slight clumping at room temperature. Other behavioral parameters of the original glue and hydrogenated glue 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 changed to 6.2 L, the amount of 12.5% ​​ETE was changed to 1.05 L, and the material feeding time was changed to 40 min. The prepared EBBR was labeled as EBBR-5.

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

[0091] Table 1. Characteristic analysis of virgin BR and hydrogenated EBBR in the examples.

[0092]

[0093]

[0094] Note: "Sticky to the finger" refers to the feeling that the granules are slightly sticky to the fingers.

[0095] Example 6

[0096] EPDM granules from Table 1 (EBBR-1, EBBR-2, EBBR-3, and Dow Chemical's DOW 3720P with a Mooney viscosity of 20 and DOW 3745P with a Mooney viscosity of 45) were used to prepare PP / EBBR alloys according to the toughened modified polypropylene formulations of this invention. The preparation method involved mixing the respective formulations at room temperature for 2 minutes in a mixer, then feeding them into a twin-screw extruder at 160-190°C for a residence time of at least 3 minutes for mixing, micro-crosslinking, extrusion, and pelletizing to prepare the PP / EBBR modified alloys. The physical properties of each 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]" is K9015 100 parts, EBBR-12 5 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 1010 0.3 parts. (3) K9015 is PP, MFR is 15~17g / 10min.

Claims

1. A method for preparing transparent polyethylene-butene rubber granules, characterized in that: Includes the following steps: 1) Butadiene monomer is polymerized by anionic polymerization to obtain polybutadiene raw material; 2) The polybutadiene raw material is catalytically hydrogenated to obtain polyethylene-butene raw material; 3) After the polyethylene-butene adhesive is concentrated by falling film evaporation, it is subjected to deep devolatilization and extrusion granulation by twin-screw extrusion.

2. The method for preparing transparent polyethylene-butene rubber granules according to claim 1, characterized in that: In step 1), the cyclohexane solution containing the structure modifier is heated to the temperature required to initiate polymerization, and then alkyl lithium, butadiene and branching agent are continuously and uniformly added to initiate and carry out the polymerization reaction, thus obtaining polybutadiene raw rubber solution.

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

4. The method for preparing transparent polyethylene-butene rubber granules according to claim 2, characterized in that: The temperature required to initiate the polymerization reaction is 58~65℃, and the maximum temperature during the polymerization reaction shall not exceed 75℃.

5. The method for preparing transparent polyethylene-butene rubber granules according to claim 1, characterized in that: In step 2), the conditions for the catalytic hydrogenation reaction are as follows: alkyl lithium is used as the activator, dimethyl phthalate and methyl o-methylbenzoate are used as co-catalysts, dicyclopentadiene titanium dichloride is used as the main catalyst, the hydrogen pressure is 13~16 bar, the temperature is 75~110℃, the total hydrogenation time is not less than 150 min, and the hydrogenation endpoint is when the polymer unsaturation is 0.30~0.40%.

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

1.

7. A method for preparing transparent polyethylene-butene rubber granules according to any one of claims 1 to 6, characterized in that: In step 3), the polyethylene-butene rubber solution is fed into a falling film evaporator for preliminary evaporation. The gas obtained from evaporation enters the condenser from the top of the falling film evaporator for condensation and solvent recovery. The concentrated polyethylene-butene rubber solution obtained from evaporation enters the twin-screw extruder from the bottom of the falling film evaporator. The concentrated polyethylene-butene rubber solution is heated and volatilized in the twin-screw extruder. The gas obtained from volatilization is sequentially drawn into the front condenser and the rear condenser for condensation and solvent recovery. The polymer melt obtained from solvent volatilization is extruded by screw extrusion, pelletized by an underwater pelletizer, and dehydrated by a centrifugal dewatering machine to obtain the finished rubber granules.

8. The method for preparing transparent polyethylene-butene rubber granules according to claim 7, characterized in that: The falling film evaporator is a vertical structure with a length-to-diameter ratio (L / D) of 10-15. Multiple large semi-circular sieve plates are installed on the vertical inner wall of the evaporator. The distance from the chord center of each large semi-circular sieve plate to the inner wall is 1 / 5 to 1 / 4 of the diameter of the falling film evaporator. Any two adjacent large semi-circular sieve plates are arranged symmetrically and uniformly in opposite directions, with a spacing of 300-350 mm between them. The large semi-circular sieve plates have uniformly distributed sieve holes with a diameter (Φ) of 7-12 mm, and the center-to-center distance between any two adjacent sieve holes is 16-24 mm.

9. The method for preparing transparent polyethylene-butene rubber granules according to claim 8, characterized in that: The polyethylene-butene adhesive solution is fed into the top of the falling film evaporator. After being evenly distributed by a distributor, it forms a film layer on the first semi-circular sieve plate. Under the action of heating and gravity, the solvent in the film layer evaporates, and the dilute adhesive solution with some of the evaporated solvent flows to the next semi-circular sieve plate to continue evaporating. This process is repeated to control the solid content of the concentrated adhesive solution entering the twin-screw extruder to be 50-60%; the solid content of the dilute adhesive solution is 12-14%.

10. The method for preparing transparent polyethylene-butene rubber granules according to claim 9, characterized in that: The steam pressure inside the falling film evaporator is 1~2 bar, the temperature is 80~90℃, and the operating pressure inside the falling film evaporator is atmospheric pressure.

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

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

13. A method for preparing transparent polyethylene-butene rubber granules according to claim 1, characterized in that: The gas that evaporates due to heat in the twin-screw extruder is extracted by a Roots vacuum pump and sequentially condensed in the front condenser and the rear condenser. The vacuum degree in the extrusion chamber of the twin-screw extruder is -0.3 to -0.5 bar.

14. A transparent polyethylene-butene rubber granule, characterized in that: It is obtained by the preparation method described in any one of claims 1 to 13.

15. The application of the transparent polyethylene-butene rubber granules according to claim 14, characterized in that: It is used in toughening and modifying polyolefin resins.

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