Monovinylarene-conjugated diene block copolymer as well as preparation method and application thereof

Abstract

The invention relates to the field of preparation of monovinylarene-conjugated diene copolymers, and discloses a method for preparing a branched monovinylarene-conjugated diene segmented copolymer through a continuous polymerization reaction. The preparation method of the block copolymer comprises the following steps: under the condition of anionic polymerization, preparing the block copolymer, the method comprises the following steps: continuously introducing reaction materials of a first part of monovinylarene monomer, a first part of conjugated diene monomer, a solvent, a polarity regulator, a gel inhibitor and a single organic lithium initiator from a first kettle of a continuous polymerization reaction device comprising a plurality of serially connected reaction kettles to carry out primary polymerization reaction; when the conversion rate reaches 97 wt% or above, a second part of monovinylarene monomer is introduced for secondary polymerization reaction, and when the conversion rate reaches 97 wt% or above, a second part of conjugated diene monomer is introduced for tertiary polymerization reaction. According to the invention, the damping material containing the branched structure, which is simple in process, suitable for large-scale implementation and wider in damping temperature range, and the preparation method of the damping material can be provided.

Description

Technical Field

[0001] The present invention relates to the field of preparing copolymers of mono-vinyl aromatic hydrocarbons and conjugated dienes. Specifically, it relates to a method for continuously polymerizing to prepare a branched mono-vinyl aromatic hydrocarbon-conjugated diene block copolymer, and a branched mono-vinyl aromatic hydrocarbon-conjugated diene block copolymer prepared by this method. More specifically, it relates to a branched mono-vinyl aromatic hydrocarbon-conjugated diene block copolymer having high damping in a wide temperature range, and its preparation method and application. Background Art

[0002] Vibration and noise not only seriously affect the accuracy, stability and service life of equipment, but also inappropriate vibration and noise will cause environmental pollution and endanger people's physical and mental health. Therefore, vibration reduction and noise reduction have always attracted much attention.

[0003] Applying damping materials or structures with excellent performance is an effective way to solve vibration and noise problems. Damping materials can convert mechanical vibration energy into heat energy and dissipate it, thereby effectively eliminating vibration and reducing noise. Currently, the damping materials studied more include polymer-based damping materials, metal-based damping materials, ceramic-based high-temperature damping materials, and composite damping materials, etc.

[0004] Polymer-based damping materials have a small relative density and are easy to process, and have become the main research direction of damping materials. Polymer-based damping materials have special viscoelasticity in the glass transition region, that is, they have deformations with two different mechanisms, elasticity and viscosity. Under the action of an external force, the molecular chains inside the damping material will produce deformations such as stretching and twisting, and at the same time, relative slip and torsion will also occur. When the external force is removed, the deformed molecular chains will reset, and the relative movement between the chain segments will also partially return to the original situation, that is, the material exhibits elasticity; but the molecular chain segments cannot fully recover, resulting in permanent deformation, that is, the material exhibits viscosity.

[0005] The damping performance of polymer-based damping materials mainly comes from the internal friction of the materials. Under the action of an alternating external force, the molecular chain segments inside the materials need to overcome the internal friction resistance to do work, resulting in the strain lagging behind the stress, and the vibration energy is converted into heat energy and dissipated through the viscous component of the materials. The glass transition region of an excellent damping material should be consistent with the working temperature range of the material, and at the same time, it should have high internal friction and a wide effective damping temperature range.

[0006] The microstructure and sequence structure of polymers, the saturation degree of the main chain, polarity, the length and content of side chains, the distribution state of monomers in copolymers, etc., have a significant impact on the molecular movement of polymers, thereby affecting the damping performance of polymer materials.

[0007] The glass transition temperatures (Tg) of general homopolymers and copolymers have a relatively narrow range, and the temperature range for generating effective damping is approximately ±(10 - 15)°C near Tg. The glass transition temperature region of a single polymer is also often narrow, and the effective damping temperature range is only 20 - 30°C.

[0008] In order to obtain a polymer with high damping performance in a relatively wide temperature range, the polymer needs to be modified. Blending two or more polymers is a common method to broaden the glass transition temperature range. Introducing pendant chains into the polymer network is also an effective means for the design of damping materials.

[0009] Patent US6268427B1 discloses a method for improving the damping performance of rubber. The method includes: adding a saturated damping material to a vulcanizable composition, where the damping additive contains a hyperbranched polymer formed by crosslinking a functionalized polymer with a polyfunctional crosslinking agent. However, this method improves the damping performance of the product by physical blending and adding a general elastomeric material, without improving the internal structure of the matrix rubber material.

[0010] Wang Pei et al. (Journal of Materials Engineering, 2009, S1: 192 - 195) prepared a styrene - butadiene rubber damping material with a high vinyl content using ethoxyethylmorpholine (EOEM). This method improves the damping characteristics of the material by increasing the side - group content. The temperature range where the loss factor tanδ of the prepared rubber is ≥0.3 is approximately from - 1°C to 23°C, which affects the application of the material as a shock - absorbing damping material below zero degree.

[0011] CN102558465B discloses a polymerization method for producing solution - polymerized styrene - butadiene rubber. This method copolymerizes butadiene and styrene in a hydrocarbon solvent by adding monomers and a structure regulator in a distributed manner, and then adds a coupling agent with 2 - 4 functionality (such as tin tetrachloride) for a coupling reaction. After the rubber prepared by this method is vulcanized, the temperature range where the loss factor tanδ is ≥0.3 is approximately from - 45°C to 0°C, which affects the application of the material as a shock - absorbing damping material above zero degree. At the same time, the presence of the coupling agent not only increases the manufacturing cost but also easily causes corrosion of equipment and pipelines, affecting the water quality of circulating water.

[0012] CN110128606B discloses a block copolymer and a preparation method thereof. By means of sequential feeding and coupling with a coupling agent having 2-4 functionality (such as tin tetrachloride), a PSIB1-PS-PB2 type block copolymer is synthesized. After the rubber prepared by this method is vulcanized, the temperature range with a loss factor tanδ≥0.3 is about -25.8°C to 30.1°C. The damping value of this material is improved, but its application as a damping and shock-absorbing material at higher temperatures is still limited. At the same time, the presence of the coupling agent not only increases the manufacturing cost, but also easily causes corrosion of equipment and pipelines, affecting the water quality of circulating water.

[0013] Therefore, there is still a need in the art to develop damping materials with a branched structure having a wider damping temperature range and their preparation technologies. Summary of the Invention

[0014] The object of the present invention is to overcome the deficiencies in the prior art, in which, in order to improve the damping performance of polymer-based damping materials, a coupling process using a branched polymer and a coupling agent having 2-4 functionality (such as tin tetrachloride) is adopted, and to provide a damping material (monovinyl aromatic-conjugated diene block copolymer) with a branched structure, a preparation method and an application thereof, which have a simple process, are suitable for large-scale implementation and have a wider damping temperature range.

[0015] To achieve the above object of the invention, on the one hand, the present invention provides a method for preparing a monovinyl aromatic-conjugated diene block copolymer, wherein the method includes: under anionic polymerization conditions, introducing reaction materials of a first part of monovinyl aromatic monomers, a first part of conjugated diene monomers, a solvent, a polar regulator, a gel inhibitor and a mono-organolithium initiator continuously into the first kettle of a continuous polymerization reaction device including a plurality of series-connected reaction kettles for a first continuous polymerization reaction. When the conversion rate of the first continuous polymerization reaction reaches more than 97% by weight, introducing a second part of monovinyl aromatic monomers for a second continuous polymerization reaction. When the conversion rate of the second continuous polymerization reaction reaches more than 97% by weight, introducing a second part of conjugated diene monomers for a third continuous polymerization reaction, wherein the polymerization temperature of the first and second continuous polymerization reactions is 70-115°C, and the polymerization temperature of the third continuous polymerization reaction is 120-160°C.

[0016] Based on the total amount of the block copolymer, the total amount of monovinyl aromatic added in the second continuous polymerization reaction is 3-20% by weight.

[0017] Preferably, the polymerization temperature of the first and second continuous polymerization reactions is 80-105°C.

[0018] Preferably, the polymerization temperature of the third continuous polymerization reaction is 125-140°C.

[0019] Preferably, the polymerization reaction pressure is 0.3 - 1.5 MPa, more preferably 0.6 - 1.2 MPa; the total residence time of the reaction materials in the continuous polymerization reaction apparatus is 40 - 140 min, more preferably 60 - 120 min.

[0020] Preferably, based on the total amount of the first part of conjugated diene monomers and the second part of conjugated diene monomers introduced, the introduced amount of the second part of conjugated diene monomers is 15 - 50 wt%, more preferably 20 - 40 wt%.

[0021] Preferably, based on the total amount of the block copolymer, the total added amount of the monovinyl aromatic hydrocarbon is 10 - 50 wt%, more preferably 15 - 40 wt%;

[0022] Preferably, based on the total amount of the block copolymer, the total added amount of the monovinyl aromatic hydrocarbon in the secondary continuous polymerization reaction is 5 - 15 wt%.

[0023] Preferably, the conjugated diene is a conjugated diene having 4 - 12 carbon atoms, more preferably 1,3 - butadiene and / or isoprene.

[0024] Preferably, the monovinyl aromatic hydrocarbon is a monovinyl aromatic hydrocarbon having 8 - 20 carbon atoms, more preferably styrene.

[0025] Preferably, the mono - organolithium initiator is selected from at least one of ethyl lithium, propyl lithium, isopropyl lithium, n - butyl lithium, sec - butyl lithium, pentyl lithium, hexyl lithium, cyclohexyl lithium, phenyl lithium, methylphenyl lithium, and naphthyl lithium, more preferably n - butyl lithium.

[0026] Preferably, based on 100 g of the total amount of the monovinyl aromatic hydrocarbon and conjugated diene monomers, the dosage of the mono - organolithium initiator is 0.25 - 2.5 mmol, more preferably 0.3 - 2.0 mmol.

[0027] Preferably, the solvent is a hydrocarbon solvent and / or an ether solvent.

[0028] Preferably, the hydrocarbon solvent is at least one of cycloalkanes, aromatic hydrocarbons, and isoparaffins having 5 - 7 carbon atoms.

[0029] Preferably, the ether solvent is a mono - ether and / or a poly - ether having 4 - C 15 of the mono - ether and / or the poly - ether.

[0030] Preferably, the dosage of the solvent is such that the concentration of the total amount of the monovinyl aromatic hydrocarbon and conjugated diene monomers is 8 - 30 wt%, more preferably 10 - 22 wt%.

[0031] Preferably, the polarity regulator is an electron-donating Lewis base, preferably a polar compound selected from at least one of nitrogen, oxygen, sulfur, and phosphorus, preferably tetrahydrofurfuryl ethyl ether.

[0032] Preferably, the weight ratio of the polarity regulator to the solvent is (0.05 - 0.3):1000, preferably (0.1 - 0.25):1000.

[0033] Preferably, the gel inhibitor is selected from at least one of 1,2-butadiene, potassium tert-pentyloxide, silicon tetrachloride, tetramethylethylenediamine, and tetrahydrofuran, preferably 1,2-butadiene.

[0034] Preferably, the weight ratio of the total amount of conjugated diene monomers to the amount of the gel inhibitor used is 1000:(0.45 - 0.75), preferably 1000:(0.50 - 0.70).

[0035] Preferably, the method further comprises contacting the polymerization reaction product with a terminator and an antioxidant in sequence.

[0036] Preferably, the number of reaction vessels is any integer from 3 to 6, more preferably the number of reaction vessels is 3 or 4.

[0037] According to the second aspect of the present invention, there is provided a vinyl aromatic-conjugated diene block copolymer prepared by the method of the first aspect of the present invention, wherein,

[0038] a. The block copolymer comprises a conjugated diene-vinyl aromatic random copolymer segment, a vinyl aromatic homopolymer segment, and a conjugated diene homopolymer segment;

[0039] b. The block copolymer has a branched crosslinked structure, and the molecular weight distribution index is 2 - 4, preferably 2.5 - 3.5;

[0040] c. The content of side groups is 20 - 65% by weight;

[0041] d. Based on the total amount of the block copolymer, the content of the vinyl aromatic homopolymer segment is 3 - 20% by weight.

[0042] According to the third aspect of the present invention, there is provided the use of the vinyl aromatic-conjugated diene block copolymer prepared by the first aspect of the present invention or the vinyl aromatic-conjugated diene block copolymer of the second aspect as a damping material or a sound absorption material.

[0043] The method of the present invention can obtain a branched mono-vinyl aromatic-conjugated diene block copolymer with a wider damping temperature range by controlling the polymerization temperature, especially the polymerization temperature of the third-stage conjugated diene polymerization. The material formed from the branched mono-vinyl aromatic-conjugated diene block copolymer of the present invention has a wider damping temperature range and is particularly suitable for use as a damping material or a sound-absorbing material.

[0044] The method of the present invention does not add a coupling agent, which reduces the cost and eliminates the adverse effects of the coupling agent on the circulating water quality, equipment and pipeline corrosion. At the same time, the polymerization reaction temperature of the method of the present invention is high, the monomer conversion rate is fast, the production efficiency is high, and it has good industrial application value.

[0045] Other features and advantages of the present invention will be described in detail in the following specific embodiments section. Specific Embodiments

[0046] The following provides a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not used to limit the present invention.

[0047] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0048] According to a first aspect of the present invention, there is provided a method for preparing a mono-vinyl aromatic-conjugated diene block copolymer, the method comprising: under anionic polymerization conditions, continuously introducing a reaction material of a first part of mono-vinyl aromatic monomer, a first part of conjugated diene monomer, a solvent, a polar regulator, a gel inhibitor and a mono-organolithium initiator into the first reactor of a continuous polymerization reaction device including a plurality of series-connected reactors for a first continuous polymerization reaction. When the conversion rate of the first continuous polymerization reaction reaches more than 97% by weight, a second part of mono-vinyl aromatic monomer is introduced for a second continuous polymerization reaction. When the conversion rate of the second continuous polymerization reaction reaches more than 97% by weight, a second part of conjugated diene monomer is introduced for a third continuous polymerization reaction, wherein the polymerization temperature of the first and second continuous polymerization reactions is 70-115°C, the polymerization temperature of the third continuous polymerization reaction is 120-160°C, and based on the total amount of the block copolymer, the total amount of mono-vinyl aromatic introduced in the second continuous polymerization reaction is 3-20% by weight.

[0049] During the research process, the inventors of the present invention unexpectedly found that in the preparation process of an anionic polymer continuous polymerization reaction mode involving conjugated dienes, by using a stable mono-organolithium as an anionic polymerization initiator and controlling the reaction temperature, a conjugated diene polymer with a branched structure can be obtained. Presumably, the reason may be that: under certain temperature conditions, a double bond in the side chain of the molecular chain of the linear conjugated diene polymer in the polymerization reaction system reacts with the active chain end of other active molecules, thereby bonding two or more molecular chains of the linear conjugated diene polymer together to form a branched structure; after exceeding the temperature at which the branching reaction occurs, the higher the reaction temperature, the more intense the branching reaction.

[0050] According to the present invention, the conjugated diene refers to various unsaturated chain hydrocarbons containing conjugated double bonds (i.e., -C=C-C=C-) in their molecular structures. The type of the conjugated diene can be reasonably selected according to the application scenarios of the finally obtained conjugated diene polymer, and it is usually a conjugated diene of C4-C12, preferably a conjugated diene of C4-C8. Specifically, the conjugated diene can be at least one of 1,3-butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene, and substituted 1,3-butadiene (such as 2-chloro-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1-phenyl-1,3-butadiene); preferably, the conjugated diene is selected from at least one of 1,3-butadiene, isoprene, 1,3-pentadiene, and 1,3-hexadiene. From the perspective of the wide application of the conjugated diene polymer, the conjugated diene is particularly preferably 1,3-butadiene and / or isoprene.

[0051] In the present invention, the mono-vinyl aromatic monomer refers to an aromatic monomer with a vinyl substituent on its aromatic ring, such as a C8-C20 mono-vinyl aromatic hydrocarbon, preferably a C8-C12 mono-vinyl aromatic hydrocarbon. Specific examples thereof include styrene, C1-C6 alkyl-substituted styrene, such as m-methylstyrene, p-methylstyrene, or p-tert-butylstyrene, or styrene derivatives with substituents on the vinyl group, such as α-methylstyrene. More preferably, the mono-vinyl aromatic hydrocarbon is styrene.

[0052] In the present invention, the "vinyl as a side group" comes from the structural unit formed by the 1,2-polymerization mode of butadiene; the "allyl as a side group" comes from the structural unit formed by the 3,4-polymerization mode of isoprene; when the side group is vinyl and / or allyl, the "side group content" refers to the total content of vinyl as a side group and allyl as a side group in the block copolymer.

[0053] The "homopolymerized segment of monovinyl aromatic hydrocarbon" refers to the content of five or more consecutive monovinyl aromatic hydrocarbon structural units in the molecular chain of the linear monovinyl aromatic hydrocarbon-conjugated diene copolymer.

[0054] In the present invention, although there is no particular requirement for the number of reaction kettles connected in series in the continuous polymerization reaction device, and it can be appropriately selected according to the conversion rate and residence time of the reaction, preferably, from the perspective of reaction efficiency and reaction cost, the number of reaction kettles is any integer from 3 to 6, and more preferably the number of reaction kettles is 3 or 4.

[0055] In the present invention, the first kettle is the first reaction kettle of the continuous polymerization reaction device, and the reaction material containing the first part of the conjugated diene monomer is added to the first kettle. The last kettle is the last reaction kettle of the continuous polymerization reaction device, and the second part of the conjugated diene monomer is added to the last kettle.

[0056] According to the present invention, the conjugated diene and the monovinyl aromatic hydrocarbon can be introduced into the reaction kettle from any position of the reaction kettle, for example, from the top, middle, bottom, etc. of the reaction kettle.

[0057] In a preferred embodiment of the present invention, the polymerization reaction is carried out in 3 series-connected polymerization reaction kettles, adopting a feed mode of bottom-in and top-out, and full-kettle operation is implemented. After the reaction material stays in the first kettle for a period of time, it overflows from the top of the first kettle to the bottom of the second reaction kettle; the reaction material in the second reaction kettle enters from the bottom of the second reaction kettle and overflows from the top of the second reaction kettle, and so on.

[0058] In the present invention, the monovinyl aromatic hydrocarbon-conjugated diene copolymerization reaction carried out in the continuous polymerization reaction device may include a primary continuous polymerization reaction, a secondary continuous polymerization reaction, and a tertiary continuous polymerization reaction. Specifically, the reaction material containing the first part of the conjugated diene monomer is added to the first kettle. When the conversion rate of the primary continuous polymerization reaction reaches more than 97% by weight, the second part of the monovinyl aromatic hydrocarbon monomer is introduced to carry out the secondary continuous polymerization reaction. Depending on the conversion rate of the primary continuous polymerization reaction, the secondary polymerization reaction can be carried out in the second reaction kettle or the third reaction kettle. When the conversion rate of the secondary continuous polymerization reaction reaches more than 97% by weight, the second part of the conjugated diene monomer is introduced to carry out the tertiary continuous polymerization reaction, and the tertiary continuous polymerization reaction is carried out in the last kettle.

[0059] According to the present invention, the polymerization reaction is an exothermic reaction. Therefore, as the polymerization reaction proceeds, the polymerization temperature spontaneously rises. Under adiabatic conditions, the polymerization temperature for the first and second consecutive polymerization reactions is preferably 80 - 105°C. The polymerization temperature for the third consecutive polymerization reaction is preferably 125 - 140°C. Under non-adiabatic conditions, if the heat of polymerization is not sufficient to control the polymerization temperature within the above range, appropriate heating is required to bring the temperature of each reaction kettle or each region to the required temperature.

[0060] As specific examples of the polymerization temperature for the first and second consecutive polymerization reactions, for example, the following can be cited: 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C, 100°C, 101°C, 102°C, 103°C, 104°C, 105°C, 106°C, 107°C, 108°C, 109°C, 110°C, 111°C, 112°C, 113°C, 114°C, 115°C, etc., and the ranges formed by any two of the above.

[0061] As specific examples of the polymerization temperature for the third consecutive polymerization reaction, for example, the following can be cited: 120°C, 121°C, 122°C, 123°C, 124°C, 125°C, 126°C, 127°C, 128°C, 129°C, 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, 139°C, 140°C, 141°C, 142°C, 143°C, 144°C, 145°C, 146°C, 147°C, 148°C, 149°C, 150°C, 151°C, 152°C, 153°C, 154°C, 155°C, 156°C, 157°C, 158°C, 159°C, 160°C, etc., and the ranges formed by any two of the above.

[0062] According to the present invention, in order to more favorably carry out the first consecutive polymerization reaction, the second consecutive polymerization reaction, and the third consecutive polymerization reaction, preferably, the polymerization pressure of the conjugated diene is 0.3 - 1.5 MPa, preferably 0.6 - 1.2 MPa; the total residence time of the reaction material in the continuous polymerization reaction device is 40 - 140 min, preferably 60 - 120 min. In the present invention, the pressures involved are all gauge pressures.

[0063] According to the present invention, preferably, based on the total amount of the first part of the conjugated diene monomer and the second part of the conjugated diene monomer introduced, the introduction amount of the second part of the conjugated diene monomer is 15 - 50% by weight, preferably 20 - 40% by weight.

[0064] According to the present invention, preferably, based on the total amount of the block copolymer, the total amount of the mono-vinyl aromatic hydrocarbon added is 10-50% by weight, preferably 15-40% by weight.

[0065] According to the present invention, preferably, based on the total amount of the block copolymer, the total amount of the mono-vinyl aromatic hydrocarbon added in the secondary reaction is 5-15% by weight.

[0066] Specific examples of the total amount of the mono-vinyl aromatic hydrocarbon added in the secondary continuous polymerization reaction, based on the total amount of the block copolymer, include, for example: 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 13% by weight, 14% by weight, 15% by weight, 16% by weight, 17% by weight, 18% by weight, 19% by weight, 20% by weight, etc., and ranges composed of any two of the above.

[0067] According to the present invention, there is no particular limitation on the amount of the mono-organic lithium initiator used, and it can be reasonably selected according to the designed molecular weight. It should be easily understood by those skilled in the art that when it is necessary to prepare the block copolymer with a larger molecular weight, the amount of the mono-organic lithium initiator can be reduced, but the polymerization rate will also decrease accordingly; when it is necessary to prepare the block copolymer with a smaller molecular weight, the amount of the mono-organic lithium initiator can be increased, but the polymerization rate will also increase accordingly. Therefore, considering the polymerization rate and the molecular weight of the obtained block copolymer comprehensively, preferably, based on 100 g of the total amount of the monomers of the mono-vinyl aromatic hydrocarbon and the conjugated diene, the amount of the mono-organic lithium initiator used is 0.25-2.5 mmol, preferably 0.3-2.0 mmol.

[0068] According to the present invention, the mono-organic lithium initiator can be represented by the general formula RLi, where R is a linear or branched alkyl group, a cycloalkyl group or an aryl group. Specifically, the mono-organic lithium initiator is selected from at least one of ethyl lithium, propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, pentyl lithium, hexyl lithium, cyclohexyl lithium, phenyl lithium, methyl phenyl lithium and naphthyl lithium, and preferably n-butyl lithium.

[0069] According to the present invention, in the process of preparing the block copolymer, the solvent can be various substances that can serve as a reaction medium, and the amount of the solvent can be selected according to the total amount of the monomers of the mono-vinyl aromatic hydrocarbon and the conjugated diene. Preferably, the amount of the solvent is such that the concentration of the total amount of the monomers of the mono-vinyl aromatic hydrocarbon and the conjugated diene is 8-30% by weight, preferably 10-22% by weight.

[0070] According to the present invention, the solvent is a hydrocarbon solvent and / or an ether solvent. The hydrocarbon solvent may be at least one of C5-C7 naphthenes, aromatics and isoparaffins. Specific examples of the hydrocarbon solvent may include, but are not limited to, one or more of benzene, toluene, xylene, ethylbenzene, propane, butane, n-pentane, cyclopentane, methylcyclopentane, n-heptane, cycloheptane, n-hexane, cyclohexane, n-octane, decane and cyclooctane. The ether solvent may be a C4-C15 monoether and / or polyether. Specific examples of the ether solvent may include, but are not limited to, tert-butoxyethoxyethane and / or tetrahydrofuran. Among them, these solvents can be used alone or in combination.

[0071] According to the present invention, in order to control the content of side groups in the block copolymer, the polymerization reaction is usually carried out in the presence of a polarity regulator. The polarity regulator may be a substance that is conventionally used in an anionic polymerization system and can regulate the microstructure of the molecular chain. Further, the polarity regulator is an electron-donating Lewis base, preferably a polar compound selected from those containing at least one of nitrogen, oxygen, sulfur and phosphorus. Specifically, examples of the polarity regulator include, but are not limited to, diethyl ether, di-n-butyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-butyl ether, 2,2-(bis(tetrahydrofurfuryl)propane), bis(tetrahydrofurfuryl)methylal, tetrahydrofurfuryl methyl ether, tetrahydrofurfuryl ethyl ether, tetrahydrofurfuryl butyl ether, α-methoxytetrahydrofuran, dimethoxybenzene, dimethoxyethane, triethylamine, pyridine, N,N-diethyl ethanolamine methyl ether, N,N-diethyl ethanolamine ethyl ether, N,N-diethyl ethanolamine butyl ether, preferably tetrahydrofurfuryl ethyl ether. Preferably, the weight ratio of the polarity regulator to the solvent is (0.05-0.3):1000, more preferably (0.1-0.25):1000.

[0072] According to the present invention, in the process of preparing the block copolymer, there is no particular limitation on the content of the gel inhibitor, and it can be a conventional choice in the art. Preferably, the weight ratio of the total amount of conjugated diene monomers to the amount of the gel inhibitor used is 1000:(0.45-0.75), more preferably 1000:(0.50-0.70). The total amount of conjugated diene monomers refers to the total amount of the first part of conjugated diene monomers and the second part of conjugated diene monomers.

[0073] According to the present invention, after the polymerization reaction is completed, it is usually necessary to terminate the obtained block copolymer product and add an antioxidant. This method also includes contacting the polymerization reaction product with a terminator and an antioxidant in sequence.

[0074] In the present invention, the terminator can be various existing substances capable of deactivating anionic active centers. For example, it can be one or more of water, methanol, ethanol, and isopropanol, and is preferably isopropanol. The dosage of the terminator can be such that the molar ratio of the terminator to the mono-organolithium initiator is (0.1 - 1):1. The specific process of the termination treatment can be a method conventionally used in the art and will not be elaborated herein.

[0075] In the present invention, after the termination treatment, contacting the polymerization reaction product with an antioxidant can obtain a block copolymer with more excellent anti-aging performance. The antioxidant can be various existing substances capable of preventing rubber aging. For example, it can be a phenolic antioxidant and / or an amine antioxidant, and specifically can be selected from one or more of 2,6-di-tert-butyl-p-cresol (abbreviated as Irganox 264), tert-butylcatechol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (abbreviated as Irganox2246), and 2,4-bis(n-octylthiomethylene)-6-methylphenol (abbreviated as Irganox 1520). Based on the total weight of 100 parts by weight of the block copolymer, the dosage of the antioxidant is generally 0.1 - 2 parts by weight. The specific process of contacting with the antioxidant can be a method conventionally used in the art and will not be elaborated herein.

[0076] In the present invention, after the polymerization reaction is completed, the solvent in the finally obtained block copolymer needs to be removed. The solvent removal can be carried out on the obtained polymer solution after the polymerization reaction product is successively contacted with a terminator and an antioxidant. The methods for removing the solvent are well-known to those skilled in the art. For example, the block copolymer can be precipitated from the solvent by alcohol precipitation, centrifugation, filtration, decantation, steam condensation, etc., or the volatile solvent in the block copolymer can be separated by stripping. Those skilled in the art can all know this and will not be elaborated herein.

[0077] According to the second aspect of the present invention, there is provided a mono-vinyl aromatic-conjugated diene block copolymer prepared by the method of the present invention, wherein: a. the block copolymer comprises a conjugated diene-mono-vinyl aromatic random copolymer segment, a mono-vinyl aromatic homopolymer segment, and a conjugated diene homopolymer segment; b. the block copolymer has a branched crosslinked structure and a molecular weight distribution index of 2 - 4; c. the content of side groups is 20 - 65% by weight; d. based on the total amount of the block copolymer, the content of the mono-vinyl aromatic homopolymer segment is 3 - 20% by weight.

[0078] According to the present invention, preferably, the content of the conjugated diene-mono-vinyl aromatic random copolymer segment is 45 - 85% by weight; more preferably, the content of the conjugated diene-mono-vinyl aromatic random copolymer segment is 50 - 82% by weight.

[0079] According to the present invention, preferably, the content of the homopolymer segment of the mono-vinyl aromatic hydrocarbon is 3-15% by weight.

[0080] According to the present invention, preferably, the content of the homopolymer segment of the conjugated diene is 10-45% by weight; more preferably, the content of the homopolymer segment of the conjugated diene is 15-40% by weight.

[0081] According to the present invention, preferably, the block copolymer is composed of a conjugated diene-mono-vinyl aromatic hydrocarbon random copolymer segment, a homopolymer segment of the mono-vinyl aromatic hydrocarbon, and a homopolymer segment of the conjugated diene.

[0082] According to the present invention, preferably, the number-average molecular weight of the mono-vinyl aromatic hydrocarbon-conjugated diene block copolymer is 80,000-350,000; more preferably, the number-average molecular weight of the mono-vinyl aromatic hydrocarbon-conjugated diene block copolymer is 100,000-300,000.

[0083] According to the present invention, preferably, the molecular weight distribution of the mono-vinyl aromatic hydrocarbon-conjugated diene block copolymer is 2.3-3.5.

[0084] According to the present invention, preferably, the content of the side group is 20-66% by weight; more preferably, the content of the side group is 30-66% by weight.

[0085] According to the present invention, preferably, in the mono-vinyl aromatic hydrocarbon-conjugated diene block copolymer, the content of the structural unit derived from the mono-vinyl aromatic hydrocarbon monomer is 10-45% by weight, and the content of the structural unit derived from the conjugated diene monomer is 55-90% by weight; more preferably, in the mono-vinyl aromatic hydrocarbon-conjugated diene block copolymer, the content of the structural unit derived from the mono-vinyl aromatic hydrocarbon monomer is 15-40% by weight, and the content of the structural unit derived from the conjugated diene monomer is 60-85% by weight.

[0086] The material formed by the mono-vinyl aromatic-conjugated diene block copolymer provided by the present invention has good damping performance in a wider temperature range (generally -35°C to 50°C), and is suitable as a damping material or a sound-absorbing material, especially suitable as a damping material or a sound-absorbing material used at low temperature and room temperature.

[0087] The present invention will be described in detail below through examples, but the present invention is not limited to the following examples.

[0088] In the following examples and comparative examples:

[0089] (1) The number-average molecular weight and molecular weight distribution of the block copolymer were measured using a Shimadzu LC-10A gel permeation chromatograph, in which tetrahydrofuran (THF) was used as the mobile phase, narrow-distribution polystyrene was used as the standard sample, and the column temperature was 25°C.

[0090] (2) The microstructure of the block copolymer was determined using an AVANCE DRX 400 MHz nuclear magnetic resonance spectrometer from Bruker Corporation, Switzerland. Among them, the test temperature was 25 °C, the liquid cell method was used, and the solvent was CS2. The test conditions were as follows: 1 The resonance frequency of the H nucleus was 400 MHz, the spectral width was 2747.253 Hz, the pulse width was 5.0 μs, the number of data points was 16K, and the number of scans was 16 times; the diameter of the sample tube was 5 mm. The block copolymer sample was dissolved in deuterated chloroform (CDCl3) to prepare a solution with a mass fraction of 2 - 3%, and the chemical shift of tetramethylsilane was calibrated to 0 ppm. Among them, 1,2 - BD% represents the content of the structural unit formed by 1,2 - polymerization of butadiene in the block copolymer, 3,4 - IP% represents the content of the structural unit formed by 3,4 - polymerization of isoprene in the block copolymer, St% represents the content of the structural unit formed by styrene in the block copolymer, and IP% represents the content of the structural unit formed by isoprene in the block copolymer.

[0091] (3) The calculation formula for the monomer conversion rate is as follows:

[0092]

[0093] (4) The loss factor was measured using a DMA - 2980 viscoelastic spectrometer from TA Instruments, USA. Among them, the frequency was 2 Hz, the heating rate was 5 °C / min, the test temperature range was - 120 °C to 100 °C, the size of the specimen was 40 mm × 5 mm × 1 mm, and the three - point bending mode was used for testing. The full width at half maximum is the difference between the two temperatures corresponding to when tanδ is half of the maximum value.

[0094] (5) The samples for measuring the loss factor were mixed and vulcanized according to the A - series formula in GB / T8656 - 1998. Mixing: The raw rubber was mixed using an open mill at a roll temperature of 50 ± 5 °C; Vulcanization: The vulcanization temperature was 145 °C, the pressure was above 10 MPa, and the vulcanization time was 35 minutes.

[0095] In the following examples and comparative examples:

[0096] The polymerization reaction was carried out in 3 series - connected polymerization reactors, with a bottom - up feeding method and full - kettle operation. After the reaction materials stayed in the first kettle for a period of time, they overflowed from the top of the first kettle to the bottom of the second reaction kettle; the reaction materials in the second reaction kettle entered from the bottom of the second reaction kettle and overflowed from the top of the second reaction kettle, and so on. The residence time was controlled by the size of the material flow. The reaction temperature of each reaction kettle was controlled by comprehensively controlling the internal heat medium in the jacket and the reaction heat release. The raw materials were fed at room temperature, and the reaction materials underwent adiabatic reactions in the kettle.

[0097] Example 1

[0098] This example illustrates the preparation method of the vinyl aromatic-conjugated diene block copolymer of the present invention.

[0099] A continuous polymerization reactor consisting of three 5-liter polymerization reactors in series is used.

[0100] In the continuous polymerization reactor, under the protection of high-purity nitrogen atmosphere, the total residence time of the reaction materials in the three reactors is 60 minutes, and the polymerization reaction pressure is controlled at 1.0 ± 0.05 MPa:

[0101] (1) The reaction materials are added from the bottom of the first reactor: 7605 g / h of hexane fraction, 1.90 g / h of ethyltetrahydrofurfuryl ether, 0.9 g / h of 1,2-butadiene, 536.25 g / h of styrene, 321.75 g / h of isoprene, 321.75 g / h of 1,3-butadiene, and 21.45 mmol / h of effective n-butyllithium. The first-stage continuous polymerization reaction is carried out at a temperature of 110 °C in the first reactor, and the polymerization conversion rate of the first reactor is 100%;

[0102] (2) 321.75 g / h of styrene is added from the bottom of the second reactor. The temperature of the second reactor is 110 °C, and the polymerization conversion rate of the second reactor is 100%;

[0103] (3) 643.50 g / h of 1,3-butadiene is added from the bottom of the third reactor. The temperature of the third reactor is 140 °C, and the polymerization conversion rate of the third reactor is 100%;

[0104] (4) The reaction is terminated by adding 0.19 g / h of terminator water at the outlet of the third reactor, and 0.2% of antioxidant Irganox 1520 based on the weight of the monomers is added to obtain a copolymer latex. Then, the copolymer latex is subjected to steam coagulation and solvent removal treatment to obtain a block copolymer.

[0105] The microstructure, base molecular weight, and dynamic mechanical property data of the copolymer are shown in Table 1.

[0106] Comparative Example 1

[0107] This comparative example illustrates the preparation method of the reference polymer. The difference from Example 1 is that the polymerization temperatures of the first and second reactors are 95 °C, and the polymerization temperature of the third reactor is 115 °C. The microstructure, base molecular weight, and dynamic mechanical property data of the block copolymer prepared under these process conditions are shown in Table 1.

[0108] Comparative Example 2

[0109] This comparative example illustrates the preparation method of the reference polymer. The difference from Example 1 is that the addition amount of styrene monomer in the secondary polymerization reaction is reduced from 15% by weight to 2% by weight, and the remaining styrene monomer is added to the first reactor. The microstructure, base molecular weight, and dynamic mechanical property data of the block copolymer prepared under these process conditions are shown in Table 1.

[0110] Example 2

[0111] This example illustrates the preparation method of the mono-vinyl aromatic-conjugated diene block copolymer of the present invention.

[0112] A continuous polymerization reactor consisting of three 5-liter polymerization reactors in series is used.

[0113] In the continuous polymerization reactor, under a high-purity nitrogen protective atmosphere, the total residence time of the reaction materials in the three reactors is 90 minutes, and the polymerization reaction pressure is controlled at 0.9 ± 0.05 MPa:

[0114] (1) The reaction materials are added from the bottom of the first reactor: 5776 g / h of a mixed solvent (a mixture of cyclohexane and n-hexane with a weight ratio of 88:12), 1.12 g / h of ethyl tetrahydrofurfuryl ether, 0.47 g / h of 1,2-butadiene, 244.80 g / h of styrene, 367.20 g / h of 1,3-butadiene, and 6.12 mmol / h of effective n-butyllithium. The first-stage continuous polymerization reaction is carried out at a temperature of 105 °C in the first reactor, and the polymerization conversion rate in the first reactor is 99.9%;

[0115] (2) 122.40 g / h of styrene is added from the bottom of the second reactor. The temperature in the second reactor is 105 °C, and the polymerization conversion rate in the second reactor is 99.9%;

[0116] (3) 489.60 g / h of 1,3-butadiene is added from the bottom of the third reactor. The temperature in the third reactor is 135 °C, and the polymerization conversion rate in the third reactor is 100%;

[0117] (4) Water as a terminator is added at a rate of 0.06 g / h at the outlet of the third reactor to terminate the reaction, and 0.2% of antioxidant Irganox 1520 based on the weight of the monomers is added to obtain a copolymer latex. Then, the copolymer latex is subjected to steam coagulation to remove the solvent to obtain a block copolymer.

[0118] The microstructure, base molecular weight, and dynamic mechanical property data of the copolymer are shown in Table 1.

[0119] Comparative Example 3

[0120] This comparative example illustrates the preparation method of the reference polymer. The difference from Example 1 is that the polymerization temperature in the first and second reactors is 85 °C, and the polymerization temperature in the third reactor is 119 °C. The microstructure, base molecular weight, and dynamic mechanical property data of the block copolymer prepared under these process conditions are shown in Table 1.

[0121] Comparative Example 4

[0122] This comparative example illustrates the preparation method of the reference polymer. The difference from Example 1 is that the addition amount of styrene monomer in the secondary polymerization reaction is reduced from 10% by weight to 2% by weight, and the remaining styrene monomer is added to the first kettle. The microstructure, base molecular weight and dynamic mechanical property data of the block copolymer prepared under these process conditions are shown in Table 1.

[0123] Table 1

[0124] Number Example 1 Comparative Example 1 Comparative Example 2 Example 2 Comparative Example 3 Comparative Example 4 Content of the first segment, wt% 55 55 68 50 50 58 Content of the second segment, wt% 15 15 2 10 10 2 Content of the third segment, wt% 30 30 30 40 40 40 Base of the first segment, wt% 41.5 45.2 33.7 26.6 28.4 26.1 Side group of the third segment, wt% 24.6 28.6 24.5 20.2 23.5 20.4 Content of side group, wt% 65.1 73.8 58.0 46.8 51.9 46.5 St, wt% 39.9 39.9 40.0 30.1 30.1 30.2 IP, wt% 15.0 15.0 15.0 - - - Mn, ten thousand 10.01 9.99 9.98 19.9 20.1 20.0 Mw / Mn 3.51 2.02 3.48 3.21 1.97 3.18 Half-peak width, °C -39.5-55.1 -24.8-30.6 -30.4-15.4 -38.1-53.2 -22.4-28.7 -27.6-14.1

[0125] Note: The content of the first segment, the second segment and the third segment are calculated by the weight of the monomer feed.

[0126] It can be seen from the data in Table 1 that when the temperature of the three - stage polymerization reaction is lower than 120 °C, the branching reaction does not occur, and the Mw / Mn of the polymer is about 2.0, indicating that the polymer does not contain a branched structure. At this time, although the side - group content of the polymer increases significantly under the same addition amount of the regulator due to the decrease in the polymerization temperature, the half - peak width of the material becomes significantly narrower. This is because the branched chains have relaxation behaviors on different time scales from the main chain, and their stretching and contraction movements under dynamic stress can contribute additional damping performance, indicating that the presence of the branched structure can significantly broaden the damping temperature range of the copolymer. When the content of the styrene homopolymer segment in the block polymer is less than 3%, the damping temperature range of the polymer decreases significantly.

[0127] Example 3

[0128] This example illustrates the preparation method of the mono - vinyl aromatic - conjugated diene block copolymer of the present invention.

[0129] Using three 5 - liter polymerization reactors in series as the continuous polymerization reaction device.

[0130] In the continuous polymerization reaction device, under the protection of high - purity nitrogen atmosphere, the total residence time of the reaction materials in the three kettles is 80 minutes, and the polymerization reaction pressure is controlled at 0.8 ± 0.05 Mpa:

[0131] (1) Add reaction materials from the bottom of the first kettle: 6215.63 g / h of hexane, 0.93 g / h of ethyl tetrahydrofurfuryl ether, 0.58 g / h of 1,2 - butadiene, 186.47 g / h of styrene, 109.67 g / h of isoprene, 438.75 g / h of 1,3 - butadiene and 7.31 mmol / h of effective n - butyllithium, and carry out the first - kettle continuous polymerization reaction. The temperature of the first kettle is controlled at 100 °C, and the polymerization conversion rate of the first kettle is 99.5%;

[0132] (2) Add 87.75 g / h of styrene from the bottom of the second kettle. The temperature of the second kettle is controlled at 100 °C, and the polymerization conversion rate of the second kettle is 99.9%;

[0133] (3) Add 274.22 g / h of 1,3-butadiene to the bottom of the three reactors. Control the temperature of the three reactors at 128 °C, and the polymerization conversion rate of the three reactors is 100%;

[0134] (4) Add water as a terminator to terminate the reaction at a rate of 0.07 g / h at the outlet of the three reactors, and add 0.2% of antioxidant Irganox 1520 based on the weight of the monomer to obtain a copolymer latex. Then, perform steam condensation and desolventization treatment on the copolymer latex to obtain a block copolymer.

[0135] The microstructure, base molecular weight and dynamic mechanical properties data of the copolymer are shown in Table 2.

[0136] Example 4

[0137] This example illustrates the preparation method of the monovinyl aromatic-conjugated diene block copolymer of the present invention.

[0138] On the basis of Example 3, replace all of the isoprene monomers in the first polymerization with 1,3-butadiene monomers, and control the temperature of the three reactors at 130 °C to obtain a block copolymer.

[0139] The microstructure, base molecular weight and dynamic mechanical properties data of the copolymer are shown in Table 2.

[0140] Example 5

[0141] This example illustrates the preparation method of the monovinyl aromatic-conjugated diene block copolymer of the present invention.

[0142] Use three 5-liter polymerization reactors in series as a continuous polymerization reaction device.

[0143] In the continuous polymerization reaction device, under the protection of high-purity nitrogen atmosphere, the total residence time of the reaction materials in the three reactors is 100 minutes, and the polymerization reaction pressure is controlled at 0.7 ± 0.05 Mpa:

[0144] (2) Add reaction materials to the bottom of the first reactor: 5148 g / h of hexane, 0.62 g / h of ethyltetrahydrofurfuryl ether, 0.39 / h of 1,2-butadiene, 98.28 g / h of styrene, 451.20 g / h of 1,3-butadiene and 2.81 mmol / h of effective n-butyllithium, and carry out the first-stage continuous polymerization reaction. Control the temperature of the first reactor at 95 °C, and the polymerization conversion rate of the first reactor is 99.0%;

[0145] (2) Add 42.12 g / h of styrene to the bottom of the second reactor. Control the temperature of the second reactor at 95 °C, and the polymerization conversion rate of the second reactor is 99.5%;

[0146] (3) Add 140.4 g / h of 1,3-butadiene to the bottom of the third reactor. Control the temperature of the third reactor at 125 °C, and the polymerization conversion rate of the third reactor is 100%;

[0147] (4) At the outlet of the third reactor, the reaction was terminated by adding terminator water at a rate of 0.03 g / h, and antioxidant Irganox 1520 at 0.2% of the monomer weight was added to obtain a copolymer latex. Then, the copolymer latex was subjected to steam condensation for desolventization treatment to obtain a block copolymer.

[0148] Data on the copolymer microstructure, base molecular weight, and dynamic mechanical properties are shown in Table 2.

[0149] Example 6

[0150] This example illustrates the preparation method of the monovinyl aromatic-conjugated diene block copolymer of the present invention.

[0151] Based on Example 5, all of the 1,3-butadiene monomers in the three-stage polymerization were replaced with isoprene monomers, and the temperature of the three reactors was controlled at 122 °C to obtain a block copolymer.

[0152] Data on the copolymer microstructure, base molecular weight, and dynamic mechanical properties are shown in Table 2.

[0153] Example 7

[0154] This example illustrates the preparation method of the monovinyl aromatic-conjugated diene block copolymer of the present invention.

[0155] A continuous polymerization reaction apparatus consisting of 3 series-connected 5-liter polymerization reactors was used.

[0156] In the continuous polymerization reaction apparatus, under a high-purity nitrogen protective atmosphere, the total residence time of the reaction materials in the 3 reactors was 120 minutes, and the polymerization reaction pressure was controlled at 0.6 ± 0.05 Mpa:

[0157] (3) The reaction materials were added from the bottom of the first reactor: hexane 4387.50 g / h, ethyl tetrahydrofurfuryl ether 0.44 g / h, 1,2-butadiene 0.29 g / h, styrene 58.50 g / h, isoprene 109.67 g / h, 1,3-butadiene 341.25 g / h, and effective n-butyllithium 1.63 mol / h. The first-stage continuous polymerization reaction was carried out with the temperature of the first reactor controlled at 80 °C, and the polymerization conversion rate of the first reactor was 98.5%;

[0158] (2) Styrene 14.63 g / h was added from the bottom of the second reactor, and the temperature of the second reactor was controlled at 80 °C, with the polymerization conversion rate of the second reactor being 99.0%;

[0159] (3) 1,3-Butadiene 73.13 g / h was added from the bottom of the third reactor, and the temperature of the third reactor was controlled at 121 °C, with the polymerization conversion rate of the third reactor being 100%;

[0160] (4) At the outlet of the three reactors, the reaction was terminated by adding terminator water at a rate of 0.01 g / h, and 0.2% of antioxidant Irganox 1520 based on the weight of the monomers was added to obtain a copolymer latex. Then, the copolymer latex was subjected to steam condensation for desolventization treatment to obtain a block copolymer.

[0161] The copolymer microstructure, base molecular weight and dynamic mechanical property data are shown in Table 2.

[0162] Table 2

[0163] Number Example 3 Example 4 Example 5 Example 6 Example 7 Content of the first segment, wt% 67 67 74 74 82 Content of the second segment, wt% 8 8 6 6 3 Content of the third segment, wt% 25 25 20 20 15 Base of the first segment, wt% 18.7 17.9 15.2 14.9 10.1 Side group of the third segment, wt% 15.3 14.6 12.5 13.1 9.9 Content of side group, wt% 34.1 32.5 27.7 28.0 20.0 St, wt% 25 25 20 20 15 IP, wt% 10 - - 20 - Mn, ten thousand 15.1 15.2 25.3 25.1 30.0 Mw / Mn 2.99 3.01 2.81 2.75 2.46 Half-peak width, °C -37.5-51.6 -36.1-51.9 -36.4-48.7 -36.2-49.2 -35.1-45.3

[0164] Note: The contents of the first segment, the second segment and the third segment are calculated based on the feeding weight of the monomers.

[0165] As can be seen from Table 1 and Table 2, by controlling the polymerization reaction temperature, especially the polymerization reaction temperature of the third segment of conjugated diene, a branched mono vinyl aromatic-conjugated diene block copolymer with a wider damping temperature range can be obtained. The material formed by the branched mono vinyl aromatic-conjugated diene block copolymer of the present invention has a wider damping temperature range and is particularly suitable for use as a damping material or a sound absorption material.

[0166] Moreover, in the method of the present invention, no coupling agent is added, which reduces the cost and eliminates the adverse effects of the coupling agent on the circulating water quality, the corrosion of equipment and pipelines. At the same time, the polymerization reaction temperature of the method of the present invention is high, the monomer conversion rate is fast, the production efficiency is high, and it has good industrial application value.

[0167] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing a vinyl aromatic-conjugated diene block copolymer, characterized in that, The method includes: under anionic polymerization conditions, continuously introducing the reaction materials of the first part of the monovinyl aromatic monomer, the first part of the conjugated diene monomer, the solvent, the polar regulator, the gel inhibitor, and the mono-organolithium initiator from the first kettle of a continuous polymerization reaction device including a plurality of serially connected reaction kettles for a first continuous polymerization reaction, when the conversion rate of the first continuous polymerization reaction reaches more than 97% by weight, introducing the second part of the monovinyl aromatic monomer for a second continuous polymerization reaction, when the conversion rate of the second continuous polymerization reaction reaches more than 97% by weight, introducing the second part of the conjugated diene monomer for a third continuous polymerization reaction, wherein, the polymerization temperature of the first and second continuous polymerization reactions is 70 - 115 °C, and the polymerization temperature of the third continuous polymerization reaction is 120 - 160 °C, Based on the total amount of the block copolymer, the total amount of the monovinyl aromatic hydrocarbon added in the second continuous polymerization reaction is 3 - 20% by weight.

2. The preparation method according to claim 1, wherein, The polymerization temperature of the first and second continuous polymerization reactions is 80 - 105 °C.

3. The preparation method according to claim 1 or 2, wherein The polymerization temperature of the third continuous polymerization reaction is 125 - 140 °C.

4. The preparation method according to any one of claims 1-3, wherein, The polymerization reaction pressure is 0.3 - 1.5 MPa, preferably 0.6 - 1.2 MPa; the total residence time of the reaction materials in the continuous polymerization reaction device is 40 - 140 min, preferably 60 - 120 min.

5. The preparation method according to any one of claims 1-3, wherein, Based on the total amount of the first part of the conjugated diene monomer and the second part of the conjugated diene monomer introduced, the introduced amount of the second part of the conjugated diene monomer is 15 - 50% by weight, preferably 20 - 40% by weight.

6. The preparation method according to any one of claims 1-3, wherein, Based on the total amount of the block copolymer, the total amount of the monovinyl aromatic hydrocarbon added is 10 - 50% by weight, preferably 15 - 40% by weight; Preferably, based on the total amount of the block copolymer, the total amount of the monovinyl aromatic hydrocarbon added in the second continuous polymerization reaction is 5 - 15% by weight.

7. The preparation method according to any one of claims 1-3, wherein, The conjugated diene is a conjugated diene of C4 - C12, preferably 1,3 - butadiene and / or isoprene.

8. The preparation method according to any one of claims 1-3, wherein, The monovinyl aromatic hydrocarbon is a monovinyl aromatic hydrocarbon containing C8 - C20, preferably styrene.

9. The preparation method according to any one of claims 1-3, wherein, The mono-organolithium initiator is selected from at least one of ethyl lithium, propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, amyl lithium, hexyl lithium, cyclohexyl lithium, phenyl lithium, methyl phenyl lithium, and naphthyl lithium, preferably n-butyl lithium; Preferably, based on 100 g of the total amount of the monovinyl aromatic hydrocarbon and the conjugated diene monomers, the dosage of the mono-organolithium initiator is 0.25 - 2.5 mmol, preferably 0.3 - 2.0 mmol.

10. The preparation method according to any one of claims 1 to 3, wherein, The solvent is a hydrocarbon solvent and / or an ether solvent; Preferably, the hydrocarbon solvent is at least one of a C5 - C7 cycloalkane, an aromatic hydrocarbon, and an isoparaffin; Preferably, the ether solvent is a monoether and / or polyether of C4-C 15 ; Preferably, the dosage of the solvent is such that the concentration of the total amount of the monovinyl aromatic hydrocarbon and the conjugated diene monomers is 8 - 30% by weight, preferably 10 - 22% by weight.

11. According to the preparation method described in any one of claims 1-3, wherein, The polar regulator is an electron-donating Lewis base, preferably a polar compound selected from at least one of those containing nitrogen, oxygen, sulfur, and phosphorus, preferably tetrahydrofurfuryl ethyl ether; Preferably, the weight ratio of the polarity regulator to the solvent is (0.05 - 0.3):1000, preferably (0.1 - 0.25):1000.

12. The preparation method according to any one of claims 1-3, wherein, The gel inhibitor is selected from at least one of 1,2 - butadiene, potassium tert - amyl oxide, silicon tetrachloride, tetramethylethylenediamine, and tetrahydrofuran, preferably 1,2 - butadiene; Preferably, the weight ratio of the total amount of the conjugated diene monomer to the dosage of the gel inhibitor is 1000:(0.45 - 0.75), preferably 1000:(0.50 - 0.70).

13. The preparation method according to any one of claims 1-3, wherein, This method further includes contacting the polymerization reaction product with a terminator and an antioxidant in sequence.

14. The preparation method according to any one of claims 1-3, wherein, The number of reaction vessels is any integer from 3 to 6, and more preferably the number of reaction vessels is 3 or 4.

15. A vinyl - aromatic monomer - conjugated diene block copolymer prepared by the method according to any one of claims 1 - 14, characterized in that: a. This block copolymer contains a conjugated diene - vinyl - aromatic monomer random copolymer segment, a vinyl - aromatic monomer homopolymer segment, and a conjugated diene homopolymer segment; b. This block copolymer has a branched cross - linked structure, and the molecular weight distribution index is 2 - 4, preferably 2.5 - 3.5; c. The content of side groups is 20 - 65% by weight; d. Based on the total amount of this block copolymer, the content of the vinyl - aromatic monomer homopolymer segment is 3 - 20% by weight.

16. Use of the vinyl - aromatic monomer - conjugated diene block copolymer prepared by the preparation method according to any one of claims 1 - 14 or the vinyl - aromatic monomer - conjugated diene block copolymer according to claim 15 as a damping material or a sound - absorbing material.

Images