Polyvinyl-1-butene random copolymer, preparation method thereof and application of polyvinyl-1-butene random copolymer as lubricating oil viscosity index modifier

Abstract

The invention discloses a polyethylene-1-butene polymer, a preparation method thereof and application of the polyethylene-1-butene polymer as a lubricating oil viscosity index modifier. The polyethylene-1-butene polymer has the following molecular structure: # imgabs0 #, wherein n, m and x are all polymerization degrees; y is a branched node, and the number of the branched nodes is greater than or equal to 6; n / (n + m + x) = (40-50)%, and m / (n + m + x) = (50-60)%; and the double bond hydrogenation degree is 99.0-99.5%. The polymer is easy to dissolve in lubricating oil, has strong thickening ability, shows low shear shift index (SSI) and excellent viscosity-temperature effect, and is especially suitable for being used as a lubricating oil viscosity index modifier.

Description

Technical Field

[0001] The invention relates to a polyethylene-1-butene random copolymer, in particular to a branched, highly hydrogenated polybutadiene polymer, and also to a preparation method thereof and application of the polyethylene-1-butene random copolymer as a lubricating oil viscosity index modifier, belonging to the technical field of hydrocarbon rubber. Background Art

[0002] From the appearance, polyethylene-1-butene random copolymer can be formed by copolymerization of ethylene and 1-butene. Polyethylene-1-butene random copolymer is similar in structure to the existing commercially available polyolefin elastomer (POE), but POE is copolymerized by ethylene and a small amount of 1-butene or 1-octene, and the α-olefin contained in its molecular structure is 10-15%. The presence of 1-butene or 1-octene chain segments in the POE molecule destroys the regularity of the polyethylene chain, but also gives the copolymer excellent transparency and good elasticity. The crystallization of the polyethylene chain at room temperature serves as a physical crosslinking point, and the amorphous region of the random copolymer chain of the ethylene-comonomer makes the copolymer plastic. The insufficient molecular weight distribution makes POE have higher tensile strength and impact resistance, and also reflects good processing performance, but the disadvantages are high modulus, high hardness, poor resilience and high crystallinity, and incompatibility with mineral oil. It has been widely used in photovoltaic panels and blending with polyolefin resins, but it is not suitable as a thickener for lubricating oil.

[0003] Chinese patent (CN104342231B) discloses a lubricating oil viscosity index improver and its preparation method. The viscosity index improver is obtained by hydrogenation modification of polyisoprene-b-polybutadiene-b-polystyrene triblock copolymer. The corresponding commercially available polymer SV-260 has a number average molecular weight Mn=(32-36)×10 4 It is obtained by coupling and hydrogenation of conjugated diene-styrene polymer. The number average molecular weight of the polymer before coupling is Mn = (5.5-6.5) × 10 4 Hydrogenated polymers are non-crystallizing and are mainly used as lubricating oil viscosity index improvers. Their preparation method is a proprietary technology of Kraton. This type of polymer has a thickening effect when added to mineral oil, but has poor shear resistance. The viscosity of the modified oil drops significantly in the later stage, and it is not suitable for long-term use as internal combustion engine oil.

[0004] Most of the existing EPDMs are high Mooney and semi-crystalline models, with poor solubility in oil products. They are mainly used for rubber or modified polyolefin resins, and cannot be used as viscosity index modifiers. As a tackifier in internal combustion engine oil, it is required to have high thickening power, low pour point and low shear stability index. Existing ethylene-propylene copolymer (EPDM) tackifiers such as J-0010, J-030, J-050 of Jilin Petrochemical Company, V-785, V8900, V9999 of Exxon Mobil Company, 3430, 0415 of Dow Chemical Company, Binary 5250 of Lion Chemical, 043, 058, 059 of Eni Chemical, 7067, 7065 of Lubrizol Company, etc. are used in large quantities. For example, Dow 3430 has a Mooney viscosity of 27, a vinyl content of 42%, and an ENB content of 0.8%, and is a non-crystalline polymer. The EPDM used as lubricating oil viscosity index modifier should also be considered comprehensively based on the requirements of viscosity index modifiers for different grades of internal combustion engine oils. Currently, J-0010, J-0030, and J-0050 cannot meet the industry standards for producing RHY-614 oil.

[0005] As a viscosity index modifier, it is essential to add a viscosity index modifier to multi-grade internal combustion engine oil. Polyolefin viscosity index modifiers were developed in the 1970s and are still the first choice. As the requirements for the viscosity-temperature characteristics and comprehensive performance of lubricating oils become higher and higher, modifiers with good oxidation stability and shear stability, good oil solubility, low price, and long service life or time have not yet appeared. Summary of the invention

[0006] The existing polyolefin and styrene-diene viscosity index modifiers have the defects of poor shear stability and viscosity-temperature performance and cannot be used to prepare high-end lubricating oils, and the random non-crystalline polyethylene-1-butene polymer has not yet been industrialized.

[0007] The first object of the present invention is to provide a polyethylene-1-butene polymer having non-crystalline, random chain segments, asymmetric branched chains and a large number of side ethyl groups, which is easily soluble in lubricating oil, has strong thickening ability, and exhibits a low shear shift index (SSI) and excellent viscosity-temperature effect, and is particularly suitable for use as a lubricating oil viscosity index modifier.

[0008] The second object of the present invention is to provide a method for preparing polyethylene-1-butene polymer, which is simple, low-cost, can be produced using existing mature equipment and processes, and is easy to industrialize.

[0009] The third object of the present invention is to provide a polyethylene-1-butene polymer for use as a lubricating oil viscosity index modifier. The polyethylene-poly-1-butene polymer is easily soluble in lubricating oil, has strong thickening ability, and exhibits a low shear shift index (SSI) and excellent viscosity-temperature effect, and has a good modification effect on oil products.

[0010] In order to achieve the above technical objectives, the present invention provides a polyethylene-1-butene polymer (EBR) having the following molecular structure:

[0011]

[0012] Among them, n, m and x are all polymerization degrees; Y is a branch node, and the number of branch nodes is ≥6; n / (n+m+x)=(40-50)%, m / (n+m+x)=(50-60)%; and the degree of double bond hydrogenation is 99.0-99.5%.

[0013] The EBR molecular structure model of the present invention is as follows:

[0014]

[0015] Among them, the molecular structure model It is a hydrocarbon segment composed of covalent bonds. The hydrocarbon segment is obtained by highly hydrogenating polybutadiene with randomly distributed 1,2-polymer units and 1,4-polymer units, so that the ethyl short branch chain formed by the 1,2-polymer unit is also randomly distributed in the entire hydrocarbon chain. In addition, since the hydrogenation activity of the side vinyl formed by the 1,2-polymer unit of butadiene is much higher than the alkenyl on the main chain formed by the 1,4-polymer unit of butadiene, its side vinyl is almost completely hydrogenated, and the degree of hydrogenation of the alkenyl on the main chain is also higher than 99%, with only a very small amount of alkenyl on the main chain remaining. At the same time, the hydrocarbon chains are connected by branching nodes "Y", thus forming an EBR molecule with an asymmetric long chain, and the number of branching nodes Y ≥ 6.

[0016] The EBR molecule of the present invention contains a high proportion of side ethyl units, and the side ethyl units are randomly distributed. The side ethyl units are obtained by hydrogenating the 1,2-polymerization units of butadiene, and their proportion reaches 50-60% of the entire butadiene unit. At the same time, the 1,2-polymerization units and 1,4-polymerization units of butadiene are randomly distributed. The EBR molecule of this structure has a non-crystalline state, which is conducive to the dissolution of the EBR molecule in the lubricating oil and the reduction of the pour point of the oil. At the same time, the EBR has a high degree of hydrogenation, which is beneficial to its high temperature resistance and good heat aging resistance.

[0017] As a preferred embodiment, the number average molecular weight M of the polyethylene-1-butene polymer is n =(12~15)×104 , molecular weight distribution index M w / M n = 1.1 to 1.2. A further preferred polyethylene-1-butene polymer Mooney viscosity is (ML 100 The preferred polyethylene-1-butene polymer has a narrow molecular weight distribution, a narrow molecular fraction, and relatively few polymers with low molecular weight, which is beneficial to thickening oil products. However, if the Mooney viscosity of the polyethylene-1-butene polymer is too high and the molecular chain is too long, the viscosity-temperature effect is poor and the molecular chain is easily sheared and broken.

[0018] The present invention also provides a method for preparing a polyethylene-1-butene polymer, which comprises heating an anionic polymerization system containing a branching agent and a structure regulator to 50-55°C, adding an initiator and butadiene to initiate and polymerize, maintaining the system temperature not exceeding 75°C during the polymerization process, and after the polymerization is completed, subjecting the obtained colloid to a catalytic hydrogenation reaction to obtain the obtained colloid.

[0019] In the process of preparing the pre-gel polybutadiene of the polyethylene-1-butene polymer of the present invention, since butadiene mainly tends to 1,4-polymerize at high temperature, it is necessary to strictly control the polymerization temperature in order to obtain a high proportion of 1,2-polymer units.

[0020] As a preferred solution, the structure regulator is at least one of tetrahydrofurfuryl alcohol ethyl ether, tetrahydrofurfuryl alcohol hexyl ether and ditetrahydrofurfuryl propane. The preferred structure regulator has a high regulating ability for 1,2-polymerization of butadiene at low temperature, so that the polymerization of butadiene tends to 1,2-polymerization, which is conducive to obtaining a higher proportion of 1,2-polymer units.

[0021] As a preferred solution, the dosage of the structure regulator is 200-240 mg / kg solvent. The dosage of the structure regulator affects its regulating ability. Under the preferred dosage of the structure regulator, polybutadiene with 1,2-polymerization units as high as 50-60% can be obtained.

[0022] As a preferred embodiment, the branching agent is divinylbenzene.

[0023] As a preferred solution, the amount of the branching agent is 1 / 2.0 to 1 / 2.2 of the molar amount of the initiator. The preferred amount of the branching agent can ensure that the number of branching nodes of the EBR molecule is more than 6, and sufficient branching degree can ensure the performance of the EBR molecule.

[0024] As a preferred solution, the polymerization time is 30 to 35 minutes.

[0025] As a preferred solution, the conditions of the catalytic hydrogenation reaction are: hydrogen pressure of 13-16 bar, temperature of 75-110° C., and hydrogenation time of not less than 120 min. Under the preferred hydrogenation conditions, a higher hydrogenation rate can be guaranteed.

[0026] As a preferred solution, the catalytic hydrogenation adopts a nickel-based catalyst system or a titanium-based catalyst system. Nickel-based catalyst systems include triisobutyl aluminum / nickel isooctanoate. Titanium-based catalyst systems include dicyclopentadiene titanium dichloride. Further preferred is a titanium-based catalyst system, which has the characteristics of small dosage and easy removal. More specifically, the titanium-based catalyst system uses a mixed solution of dimethyl phthalate and methyl o-toluate as a co-catalyst, dicyclopentadiene titanium dichloride as a main catalyst, the main catalyst dosage is 0.020-0.040 g / 100 g polymer, and the main catalyst / co-catalyst (mol) is 3-8.

[0027] As a preferred solution, the glue solution is terminated with a small amount of water, dehydrated by a centrifuge, condensed by water vapor, extruded for dehydration, and pressed into blocks to obtain the glue solution.

[0028] As a preferred solution, the anionic polymerization system uses cyclohexane solvent, and the amount of cyclohexane solvent used ensures that the concentration of butadiene monomer in the solvent is 12-14 g / 100 g.

[0029] The EBR preparation method of the present invention is as follows:

[0030] The first step: In an anionic polymerization system containing a branching agent and a structure regulator, heat to 50-55°C, then add a certain amount of n-butyl lithium (NBL), and then add a certain amount of butadiene to carry out homopolymerization for 25-35 minutes, during which the maximum polymerization temperature is maintained at no more than 75°C, to obtain BR raw rubber solution.

[0031] Step 2: Add a certain amount of NBL, a promoter, and a hydrogenation catalyst to the BR original rubber solution, and carry out the hydrogenation reaction for no less than 120 minutes under the conditions of a hydrogen pressure of 13 to 16 bar and a temperature of 75 to 110°C to obtain an EBR rubber solution.

[0032] Step 3: The EBR glue solution is terminated with a terminator, and a small amount of catalyst residue in the glue solution is removed by sedimentation centrifugation. The solvent in the glue solution is removed by water vapor condensation, and the EBR dry glue is obtained by drying.

[0033] The invention also provides an application of the polyethylene-1-butene polymer, which is used as a lubricating oil viscosity index modifier.

[0034] As a preferred solution, the polyethylene-1-butene polymer is added to the lubricating oil in an amount of 1.0 to 1.3 g / 100 g of lubricating oil.

[0035] The polyethylene-1-butene polymer of the present invention is directly added to the lubricating oil, and the additives known in the lubricating oil industry such as antioxidants are also added, and stirred at 80-100° C. until the polymer is completely dissolved. The lubricating oil is a base oil known in the lubricating oil industry, such as commercially available 150BS. The antioxidant is preferably at least one of antioxidant 3114, antioxidant 1076, etc., and its preferred dosage is 0.3-0.4 g / 100 g of lubricating oil.

[0036] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0037] Compared to traditional linear or slightly branched EPDM, the EBR polyethylene-poly 1-butene chain segments of the present invention are randomly distributed, non-crystallized, and have asymmetric long chain branches, and contain a large number of side ethyl structures, are easily soluble in base oil, have strong thickening ability, and simultaneously embody low shear shift index (SSI) and excellent viscosity-temperature effect, which refers to that the modified oil maintains the best oil viscosity in a wide temperature range. At low temperatures, this EBR modifier has a low solubility in oil, and the polymer chain is wrapped and flexed, which has little effect on the viscosity of the oil. However, at high temperatures, the solubility in the oil increases, and the molecular chain is fully extended under the shear traction effect, so that the viscosity of the oil becomes larger, thereby changing the lubricity of the oil, compared to EPDM of equal molecular weight, all benefit from the fact that the molecular chain of EBR presents asymmetric long chain branching and a large number of side ethyls, and the side ethyls and branched chains have a greater resistance to the movement of the oil than the side methyl resistance in the EPDM molecule. Therefore, among many polymers, EBR has the best modification effect in oil products.

[0038] The EBR preparation process of the invention belongs to a homogeneous reaction, has simple preparation, can be synthesized by using existing mature processes, and is easy to control and industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the GPC spectrum of the polymer EBR raw rubber BR of Example 1.

[0040] Figure 2 H of the polymer EBR raw rubber BR in Example 1 1 -NMR.

[0041] Figure 3 H is the H of the hydrogenated polymer EBR of Example 1 1 -NMR. DETAILED DESCRIPTION

[0042] 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.

[0043] 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 technical parameters of the modified oil are determined according to the corresponding experimental methods.

[0044] Example 1

[0045] In a 5-liter polymerization kettle under nitrogen protection, 3500 mL of cyclohexane, 0.75 mL of tetrahydrofurfuryl alcohol ethyl ether (ETE), 0.18 mL of divinylbenzene (DVB), and 4.5 mL of 0.50 mol / L NBL were added in sequence, and the temperature was raised to 55°C with hot water, and then 450 mL of butadiene was added. The polymerization was carried out for 30 minutes under a nitrogen pressure of 4.0 bar while controlling the maximum polymerization temperature not to exceed 75°C. The original BR rubber (GPC and H 1 -NMR spectra are attached Figure 1 and attached Figure 2 ).

[0046] The rubber liquid was pressed into a hydrogenation kettle with nitrogen, and 2 mL of 0.5 mol / L NBL, 3 mL of 0.02 mol / L cyclohexane solution of dimethyl phthalate and methyl o-toluate (molar ratio 1:1), and 0.16 g of dicyclopentadiene titanium dichloride were added, and the mixture was stirred and hydrogenated for 130 min at a hydrogen pressure of 14 bar and a temperature of 105°C to obtain EBR rubber liquid. The hydrogenated rubber liquid was then terminated with a small amount of water, and the mixture was subjected to water vapor condensation at 98°C, solvent removal, and drying to obtain EBR block rubber (labeled as EBR-1, its H 1 -NMR spectrum see Figure 3 ), the characteristic behaviors of the polymers are shown in Table 1.

[0047] Example 2

[0048] The relevant process conditions in Example 1 were kept unchanged, except that during polymerization, 0.85 mL of ETE and 0.20 mL of DVB, 4.0 mL of 0.50 mol / L NBL, and 150 min of hydrogenation time were changed.

[0049] Results The characteristic behavior of the polymer (designated as EBR-2) is shown in Table 1.

[0050] Example 3

[0051] The relevant process conditions in Example 1 were kept unchanged, except that ETE was changed by 1.0 mL during polymerization.

[0052] The results show that the characteristic behavior of the polymer (designated as EBR-3) is shown in Table 1.

[0053] Example 4

[0054] The relevant process conditions in Example 1 were kept unchanged, except that during polymerization, ETE was changed to 0.80 mL, 0.50 mol / L, NBL to 4.2 mL, and hydrogenation time to 140 min.

[0055] Results The characteristic behavior of the polymer (designated as EBR-4) is shown in Table 1.

[0056] Example 5

[0057] As a control.

[0058] The relevant process conditions in Example 1 were kept unchanged, except that during polymerization, ETE was changed to 0.50 mL, NBL was changed to 4.2 mL, and the hydrogenation time was changed to 140 min.

[0059] Results The characteristic behavior of the polymer (designated as EBR-5) is shown in Table 1.

[0060] Example 6

[0061] As a control.

[0062] The relevant process conditions in Example 1 were kept unchanged, except that DVB was changed by 0.25 mL during polymerization.

[0063] Results The characteristic behavior of the polymer (designated as EBR-6) is shown in Table 1.

[0064] Example 7

[0065] As a control.

[0066] The relevant process conditions in Example 1 were kept unchanged, except that DVB was changed by 0.14 mL during polymerization.

[0067] Results The characteristic behavior of the polymer (designated as EBR-7) is shown in Table 1.

[0068] Example 8

[0069] As a control.

[0070] The relevant process conditions in Example 4 remain unchanged, except that the hydrogenation time is selected to be 100 minutes.

[0071] Results The characteristic behavior of the polymer (designated as EBR-8) is shown in Table 1.

[0072] Table 1 Characteristic analysis of original rubber BR and hydrogenated rubber EBR in the examples

[0073]

[0074] Example 9

[0075] The hydrogenated products of Examples EBR-1, EBR-2, EBR-3, EBR-4, EBR-5, EBR-6, EBR-7, and EBR-8, as well as commercially available ethylene propylene rubber Dow 3430 and styrene-diene hydrogenated product SV-260 were added to 150BS base oil at 1.10 g / 100 g oil, and 3114 antioxidant was added at 0.35 g / 100 g oil, and the mixture was stirred at 90°C for 2 h. Then, the oil products containing the polymers were tested respectively.

[0076] The results showed that the pour point of the oil prepared with sample EBR-5 was -31°C, and an insoluble swollen gel appeared in the oil prepared with sample EBR-6. The physical behaviors of other samples are shown in Table 2.

[0077] Table 2 Measured values ​​of different polymers as viscosity index modifiers

[0078]

[0079]

[0080] As can be seen from Table 2, compared with polymers with low hydrogenation degree and slightly lower molecular weight and SV-260, the polymer of the present invention exhibits excellent comprehensive performance in base oil and can be used as a viscosity index modifier for high-end lubricating oil.

Claims

1. A polyethylene-1-butene polymer, characterized in that: It has the following molecular structure: in, n, m and x are the degrees of polymerization; Y is a branching node, the number of branching nodes is ≥ 6; n / (n+m+x)=(40~50)%, m / (n+m+x)=(50~60)%; The degree of double bond hydrogenation is 99.0 to 99.5%.

2. A polyethylene-1-butene polymer according to claim 1, characterized in that: The number average molecular weight M of the polyethylene-1-butene polymer n =(12~15)×10 4 , molecular weight distribution index M w / M n =1.1~1.

2.

3. A polyethylene-1-butene polymer according to claim 1, characterized in that: The Mooney viscosity ML of the polyethylene-1-butene polymer 100 ℃ is 55~65.

4. The method for preparing a polyethylene-1-butene polymer according to any one of claims 1 to 3, characterized in that: The anionic polymerization system containing a branching agent and a structure regulator is heated to 50-55°C, and an initiator and butadiene are added to initiate and polymerize. During the polymerization process, the system temperature is maintained at no more than 75°C. After the polymerization is completed, the obtained rubber solution is subjected to a catalytic hydrogenation reaction to obtain the obtained product.

5. The method for preparing a polyethylene-1-butene polymer according to claim 4, characterized in that: The structure regulator is at least one of tetrahydrofurfuryl alcohol ethyl ether, tetrahydrofurfuryl alcohol hexyl ether and ditetrahydrofurfuryl propane.

6. The method for preparing a polyethylene-1-butene polymer according to claim 4 or 5, characterized in that: The dosage of the structure regulator is 200-240 mg / kg solvent.

7. The method for preparing a polyethylene-1-butene polymer according to claim 4, characterized in that: The branching agent is divinylbenzene.

8. The method for preparing a polyethylene-1-butene polymer according to claim 4 or 7, characterized in that: The amount of the branching agent used is 1 / 2.0 to 1 / 2.2 of the molar amount of the initiator.

9. The method for preparing a polyethylene-1-butene polymer according to claim 4, characterized in that: The polymerization time is 30 to 35 minutes.

10. The method for preparing a polyethylene-1-butene polymer according to claim 4, characterized in that: The conditions of the catalytic hydrogenation reaction are: hydrogen pressure of 13-16 bar, temperature of 75-110° C., and hydrogenation time of not less than 120 min.

11. The method for preparing a polyethylene-1-butene polymer according to claim 10, characterized in that: The catalytic hydrogenation adopts a nickel-based catalyst system or a titanium-based catalyst system.

12. The use of a polyethylene-1-butene polymer according to any one of claims 1 to 3, characterized in that: Used as a lubricating oil viscosity index modifier.

13. The use of a polyethylene-1-butene polymer according to claim 12, characterized in that: The polyethylene-1-butene polymer is added in an amount of 1.0 to 1.3 g / 100 g of lubricating oil.

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