Styrene-piperylene-styrene block copolymer and its synthesis method and application

Abstract

The present invention relates to the field of thermoplastic elastomers, disclose styrene-piperylene-styrene block copolymer and its synthesis method and application, in the styrene-piperylene-styrene block copolymer (SPS), the content of 1,2 structures is 20-50 weight %. Compared to SBS and SIS, the SPS has the advantages of high anti-1,4 structures, high branching degree, high hardness, high elasticity low plasticity and high coupling efficiency. The present invention uses the initiation system consisting of organic lithium and tetrahydrofuran-based compounds, not only can SPS branching 1,2 structures be regulated, while polymerization rate can be improved, and the normal progress of subsequent coupling reaction can also be ensured without carrying out temperature control to polymerization process. The use of tetrahydrofuran-based compounds can greatly reduce SPS single kettle polymerization time, contributes to reducing energy consumption, material consumption, while polymerization process microstructure regulation stability is excellent, with great industrial application prospects.

Description

Technical Field

[0001] The present invention relates to the field of polymers, and in particular to a styrene-piperylene-styrene block copolymer, a synthesis method and applications thereof. Background Art

[0002] Triblock copolymers based on butadiene and isoprene are important members of the traditional lithium-based thermoplastic elastomer family. This type of material combines the properties of plastic and rubber, with high elasticity, high strength and excellent resilience of rubber, while also being injection moldable. SBS / SIS has become the most consumed styrene-based thermoplastic elastomer (TPE) (global thermoplastic elastomer market demand exceeds 6 million tons).

[0003] The structure of polyconjugated dienes determines their properties. Butadiene, isoprene, and isoprene, upon polymerization, all form unsaturated elastic carbon chains containing a certain amount of branching. Their unique cis-trans isomerization of double bonds and their differential side chain structures endow elastomers with unique properties. For example, side-chain vinyl SBS elastomers are primarily used in footwear (sole), hoses, and tapes. They can also serve as modifiers for polypropylene (PP), polyethylene (PE), and polystyrene (PS) resins, significantly improving their low-temperature performance and impact strength. As an adhesive, SBS exhibits high solids content, quick drying, and low-temperature resistance. As a modifier for construction and road asphalt, SBS can significantly improve the asphalt's weathering and load-bearing properties. The main chain double bonds of SIS elastomers tend to form cis-4,1-polymerization, producing highly elastic carbon chains, which are commonly used in pressure-sensitive adhesives.

[0004] Therefore, the development of new specific thermoplastic elastomer materials will further expand the existing TPE market and has great economic value. Summary of the Invention

[0005] The present invention aims to provide a styrene-piperylene-styrene block copolymer (SPS) and a synthesis method and application thereof. Compared with SBS or SIS, the SPS copolymer has the advantages of high trans-1,4-structure, high branching degree, high hardness, high elasticity and low plasticity, and high coupling efficiency.

[0006] In order to achieve the above object, the first aspect of the present invention provides a styrene-piperylene-styrene block copolymer, wherein the content of 1,2-structure in the styrene-piperylene-styrene block copolymer is 20-50 wt%.

[0007] A second aspect of the present invention provides a method for synthesizing a styrene-piperylene-styrene block copolymer, the method comprising: contacting styrene and piperylene in the presence of an organic lithium initiator and a tetrahydrofuran-based compound to carry out a polymerization reaction.

[0008] Preferably, the tetrahydrofuranyl compound has a structure shown in formula (I),

[0009]

[0010] Wherein, R1 is H or a C1-C3 alkyl group; R2 is H or a C1-C3 alkyl group; and R3 is a group containing O or N.

[0011] More preferably, the tetrahydrofuranyl compound has at least one of the structures represented by formula (II), formula (III), formula (IV) and formula (V),

[0012]

[0013] Wherein, R4 is a C1-C6 alkyl group or a C6-C12 aryl group, R5 is a C1-C4 alkyl group, R6 is a C1-C4 alkyl group; and n is an integer of 1-4.

[0014] The third aspect of the present invention provides a styrene-piperylene-styrene block copolymer prepared by the method described above.

[0015] A fourth aspect of the present invention provides the use of the styrene-piperylene-styrene block copolymer described above in hot melt adhesives, high-hardness elastomers, and thermal memory deformation materials.

[0016] The styrene-piperylene-styrene block copolymer of the present invention has the advantages of controllable molecular weight, high trans-1,4-structure, high branching degree, high hardness, narrow molecular weight distribution and excellent mechanical properties.

[0017] The present invention utilizes an initiation system composed of an alkyl lithium and a tetrahydrofuran-based compound, which not only regulates the branched 1,2-structure of SPS but also ensures a relatively fast reaction rate between styrene and piperylene. In particular, it significantly increases the conversion rate of piperylene monomer, thereby increasing the polymerization rate and shortening the polymerization time to 25-45 minutes. Furthermore, due to its enhanced hydrophilicity, it results in extremely low post-processing residues, leaving virtually no regulator residue in the SPS, which is beneficial for improving product quality.

[0018] The method of the present invention can ensure the normal progress of the subsequent coupling reaction without temperature control during the polymerization process, and the coupling efficiency can reach more than 85%.

[0019] The method described in the present invention can greatly shorten the SPS single-reactor polymerization time, help reduce energy consumption and material consumption, and at the same time, the microstructure control stability of the polymerization process is excellent, and has great industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 13 is the conversion kinetic curve of piperylene under different ratios of N,N-dimethyltetrahydrofurfurylamine to n-butyllithium in Example 3 of the present invention;

[0021] Figure 2 This is the conversion kinetic curve of isopentadiene under different temperature conditions in Comparative Example 2 of the present invention without adding dimethyltetrahydrofurfurylamine. DETAILED DESCRIPTION

[0022] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0023] During the research process, the inventors of the present invention discovered that compared with the differences in double bond configuration and branching structure of SBS and SIS triblock copolymers, SPS has a high trans 1,4-structure and a stable and controllable high steric branching structure, which is similar to the structure of thickening piperyl petroleum resin. The trans 1,4-structure is beneficial to improving the viscosity of piperyl copolymers and also helps to improve the hardness of the product. The 1,2-structure can be evenly inserted into the trans 1,4-structure to destroy the crystallinity of the SPS structure, increase the degree of branching, and help to improve the elastic properties of the product and reduce the plastic properties.

[0024] A first aspect of the present invention provides a styrene-isopentadiene-styrene block copolymer, wherein the content of 1,2-structure in the styrene-isopentadiene-styrene block copolymer is 20-50% by weight, for example, 25, 28, 30, 32, 35, 38, 40, 42, 45, 48, 50% by weight and any range between any two values.

[0025] Preferably, the 1,2-structure content in the styrene-piperylene-styrene block copolymer is 30-50% by weight. Within this preferred range, the 1,2-structure can be stably and uniformly inserted into the high-trans 1,4-structure unit, which helps reduce the crystallization performance of the high-trans structure and improve its elastic deformation.

[0026] In the present invention, the content of the trans-1,4-structure in the styrene-piperylene-styrene block copolymer is preferably 35 to 60% by weight.

[0027] In the present invention, the styrene monomer content in the styrene-piperylene-styrene block copolymer can be selected within a wide range. Preferably, the styrene monomer content is 20-50% by weight; more preferably, the styrene monomer content is 25-40% by weight. Within this preferred range, the excellent mechanical properties, high hardness, and high softening point introduced by the polystyrene physical crosslinking can be maintained.

[0028] In the present invention, the content of the piperylene monomer in the styrene-piperylene-styrene block copolymer can be selected within a wide range. Preferably, the piperylene monomer content is 50-80% by weight; more preferably, the piperylene monomer content is 60-75% by weight. Within this preferred range, the introduction of the soft segment polypiperylene ensures good elastic deformation, viscosity-increasing properties, and low-temperature applicability.

[0029] Preferably, the number average molecular weight of the styrene-piperylene-styrene block copolymer is 20,000-1,000,000, more preferably 50,000-500,000.

[0030] Preferably, the molecular weight distribution of the styrene-piperylene-styrene block copolymer is less than 1.3, preferably 1.04-1.2.

[0031] Preferably, the permanent deformation of the styrene-piperylene-styrene block copolymer is 30-70%.

[0032] Preferably, the 300% modulus of the styrene-piperylene-styrene block copolymer is 3.5-8 MPa.

[0033] Preferably, the tensile strength of the styrene-piperylene-styrene block copolymer is 10-25 MPa.

[0034] Preferably, the elongation at break of the styrene-piperylene-styrene block copolymer is 600-1200%.

[0035] Preferably, the hardness of the styrene-piperylene-styrene block copolymer is 70-100 Shore A. Under the condition of the same styrene structural unit content, the hardness of SPS is generally about 10 Shore A higher than that of SBS.

[0036] Preferably, the content of tetrahydrofuranyl compounds in the styrene-piperylene-styrene block copolymer is below 25 ppm. The types of tetrahydrofuranyl compounds are described in detail in the second aspect.

[0037] In the present invention, the styrene-piperylene-styrene block copolymer may be a conventional type in the art, such as a styrene-piperylene-styrene triblock copolymer and a styrene-piperylene-styrene star block copolymer.

[0038] In the present invention, the styrene content, 1,2-structure content, trans-1,4 structure and other microstructures can be measured using an AVANCE DRX 400 MHz nuclear magnetic vibration spectrometer produced by Bruker, Switzerland.

[0039] In the present invention, the molecular weight of the block copolymer can be measured using a LC-10A series gel permeation chromatograph produced by Shimadzu Corporation of Japan.

[0040] In the present invention, the physical and mechanical properties of the block copolymer can be tested using a G7-AI-3000 tensile testing machine in accordance with the GB / T528-2009 standard.

[0041] In the present invention, the hardness of the block copolymer can be tested using a Shore durometer according to GB / T 531.1-2008.

[0042] While preparing SPS, the inventors discovered that tetrahydrofuran (THF) or tetramethylethylenediamine (TMEDA), commonly used as modifiers in conventional lithium-based polymerization processes, can regulate the content of branched structures in the soft segment and improve polymerization initiation and propagation rates. However, THF or TMEDA have the following drawbacks: First, these modifiers have a low boiling point at atmospheric pressure and are more likely to remain after the solvent refining process, ultimately leading to large fluctuations in the quantitative amount of the modifier in the solvent system and affecting product quality stability; second, these modifiers have good solubility in the glue solution and are difficult to completely remove during the post-treatment water washing process, resulting in volatilization during the molding and extrusion process; and because THF has a weak coordination effect with alkyl lithium, the second-stage polymerization rate is extremely fast and the temperature rise is extremely significant (instantaneous high temperature exceeds 120°C). Large temperature fluctuations will reduce the coordination effect, resulting in unstable 1,2-structure regulation. Finally, to ensure the smooth progress of the branched structure and / or coupling reaction of the product, it is necessary to manually control the polymerization process by lowering the polymerization initiation temperature and controlling the maximum polymerization temperature. Lowering the polymerization temperature will prolong the polymerization reaction time, and temperature control will cause unstable product quality. At the same time, when using silicon tetrachloride (SiCl4) for the active species end group coupling reaction, a higher reaction temperature is required to facilitate the reduction of the system viscosity, and controlling the reaction temperature will be detrimental to the coupling reaction.

[0043] The results unexpectedly found that in the synthesis of polystyrene-polyisopentadiene-polystyrene block copolymers (SPS), the use of an initiation system consisting of organic lithium and tetrahydrofuran compounds can not only achieve steady-state regulation of the 1,2-structure and polymerization rate, but also significantly shorten the polymerization time of isoprene. Interestingly, unlike the rapid increase in temperature during butadiene polymerization, the temperature and reaction rate can remain basically stable during isoprene polymerization, without the need for heat removal treatment, and the content of the obtained 1,2-structure has basically no significant difference over time, which is conducive to obtaining products with stable 1,2-structure content. In addition, when preparing star-shaped block copolymers, high coupling efficiency can also be achieved in the later stage of polymerization, and the coupling efficiency can reach more than 85%. Moreover, compared with other types of regulators, the use of tetrahydrofuran compounds can ensure that there is no regulator residue in the SPS product, thereby improving the quality stability of the product.

[0044] A second aspect of the present invention provides a method for synthesizing a styrene-piperylene-styrene block copolymer, the method comprising: contacting styrene and piperylene in the presence of an organic lithium initiator and a tetrahydrofuran-based compound to carry out a polymerization reaction.

[0045] In the present invention, the organic lithium initiator is preferably an alkyl lithium initiator and / or a functionalized organic lithium initiator.

[0046] The organolithium initiator suitable for the present invention is preferably an alkyllithium initiator, for example, an organolithium initiator represented by RLi, wherein R is a linear or branched alkyl, cycloalkyl or aryl group.

[0047] Examples of organolithium initiators include, but are not limited to, ethyllithium, propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, pentyllithium, hexyllithium, cyclohexyllithium, phenyllithium, methylphenyllithium, and naphthyllithium, with n-butyllithium or sec-butyllithium being preferred. In the preferred embodiment, the organolithium initiator can be well dissolved in the polymerization solvent, is convenient to store, has a faster initiation rate, and is easily dissociated.

[0048] According to some embodiments of the present invention, the amount of initiator used during the polymerization process can depend on the designed molecular weight. Preferably, the amount of the organolithium initiator used is 0.2-3 mmol / 100 g monomer, preferably 0.8-1.5 mmol / 100 g monomer, based on the total weight of the monomers. It should be understood that the monomers are styrene monomers and piperyl monomers.

[0049] In the present invention, preferably, the tetrahydrofuranyl compound has a structure shown in formula (I),

[0050]

[0051] Wherein, R1 is H or a C1-C3 alkyl group; R2 is H or a C1-C3 alkyl group; and R3 is a group containing O or N.

[0052] Preferably, the tetrahydrofuranyl compound has at least one of the structures represented by formula (II), formula (III), formula (IV) and formula (V),

[0053]

[0054] Wherein, R4 is a C1-C6 alkyl group or a C6-C12 aryl group, R5 is a C1-C4 alkyl group, R6 is a C1-C4 alkyl group; and n is an integer of 1-4.

[0055] The C1-C6 alkyl group is, for example, selected from one of methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, and n-hexyl.

[0056] The C6-C12 aryl group may be, for example, phenyl, o-tolyl, m-tolyl, p-tolyl, o-ethylphenyl, m-ethylphenyl, p-ethylphenyl or naphthyl.

[0057] Preferably, the tetrahydrofuranyl compound is selected from at least one of tetrahydrofurfuryl alcohol ethyl ether, tetrahydrofurfuryl alcohol methyl ether, tetrahydrofurfuryl alcohol isopropyl ether, tetrahydrofurfuryl alcohol butyl ether, tetrahydrofurfuryl alcohol benzyl ether, ditetrahydrofurfuryl propane, N,N-dimethyltetrahydrofurfurylamine, N,N-diethyltetrahydrofurfurylamine, N-pyrrolidinotetrahydrofurfurylamine and N-piperidinotetrahydrofurfurylamine.

[0058] In a more preferred embodiment of the present invention, the tetrahydrofuranyl compound is selected from at least one of tetrahydrofurfuryl alcohol ethyl ether, ditetrahydrofurfuryl propane, N,N-dimethyltetrahydrofurfurylamine, and pyrrolidinetetrahydrofurfurylamine. Within this preferred range, the alkyl lithium can be more rapidly decomposed, providing a more stable and efficient branched structure regulation effect. Furthermore, due to its strong hydrophilicity, it is less likely to remain in the post-processing glue solution.

[0059] In a preferred embodiment of the present invention, the tetrahydrofuranyl compound has the characteristic of a high boiling point (above 140° C.).

[0060] In the present invention, the molar ratio of the tetrahydrofuran-based compound to the organolithium initiator is preferably 0.01-1:1, for example, 0.01:1, 0.02:1, 0.04:1, 0.06:1, 0.08:1, 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, and any range between any two values, more preferably 0.1-0.5:1. Within this preferred range, butyl lithium can be deassociated, the 1,2-structure of the polypiperylene soft segment can be controlled within a range of 20%-50%, and the molecular weight distribution of the multi-block copolymer can be maintained below 1.30.

[0061] According to some embodiments of the present invention, the polymerization reaction is carried out in the presence of an organic solvent, preferably a hydrocarbon solvent. The hydrocarbon solvent can be any inert hydrocarbon solvent, preferably a non-polar hydrocarbon solvent. More preferably, the hydrocarbon solvent is selected from at least one of C5-C12 alkanes, C5-C12 cycloalkanes, and C6-C12 aromatic hydrocarbons.

[0062] Among them, C5-C12 alkanes include but are not limited to pentane, hexane, heptane, octane and decane.

[0063] Among them, C5-C12 cycloalkanes include but are not limited to cyclopentane, methylcyclopentane, cyclohexane, cycloheptane and cyclooctane.

[0064] Among them, C6-C12 aromatic hydrocarbons include but are not limited to benzene, toluene, xylene and ethylbenzene.

[0065] When the hydrocarbon solvent contains two or more components, it can be a mixture of pure substances, such as a mixed solvent of n-hexane and cyclohexane; or it can be a mixed hydrocarbon solvent in a conventional form in the art, such as raffinate oil.

[0066] In a preferred embodiment of the present invention, the hydrocarbon solvent is selected from at least one of cyclopentane, methylcyclopentane, cyclohexane, n-hexane and raffinate oil.

[0067] Wherein, the main component of the raffinate oil may be C5-C8 alkanes.

[0068] In a preferred embodiment of the present invention, the organic solvent is a mixed solvent of cyclohexane and n-hexane, and the content of n-hexane in the mixed solvent of cyclohexane and n-hexane is 5-25% by weight.

[0069] In a preferred embodiment of the present invention, the organic solvent is cyclopentane, which can significantly increase the monomer concentration of SPS and is beneficial for increasing production capacity.

[0070] In the present invention, the amount of the organic solvent used is preferably such that the monomer concentration is 5-30% by weight, preferably 10-25% by weight. Within the preferred range, the low viscosity of the polymerized monomers and the polymer can be ensured, which is beneficial to the mass and heat transfer characteristics of the polymerization process.

[0071] It should be understood that the monomer concentration refers to the ratio of the sum of the weights of styrene and piperylene relative to the total weight of styrene, piperylene and the organic solvent.

[0072] In the present invention, the polymerization reaction can be carried out in a batch polymerization mode or a continuous polymerization mode.

[0073] In the present invention, the polymerization reaction conditions may be conventional polymerization conditions in the art. Preferably, the polymerization reaction conditions include: a temperature of 25-150° C., more preferably 50-120° C.; and a pressure of 0.1-1.5 MPa, more preferably 0.1-0.3 MPa.

[0074] In the present invention, different types of products can be prepared by different contact methods. For example, a styrene-piperylene-styrene triblock copolymer can be prepared by a three-step sequential addition method, and a styrene-piperylene-styrene star block copolymer can be prepared by a two-step method followed by coupling.

[0075] In one embodiment of the present invention, the method of contacting styrene and piperylene includes: subjecting a first portion of styrene to a first polymerization in the presence of an organic lithium initiator and a tetrahydrofuran-based compound, then adding piperylene to the material after the first polymerization for a second polymerization, and then adding a second portion of styrene to the material after the second polymerization for a third polymerization, to obtain a styrene-piperylene-styrene triblock copolymer. Preferably, the temperature for the first polymerization is 60-70°C, the temperature for the second polymerization is 60-100°C, and the temperature for the third polymerization is 60-70°C.

[0076] Preferably, the ratio of the first part of styrene to the second part of styrene is 1:0.5-2; more preferably 1:0.8-1.2.

[0077] Preferably, based on the total weight of the monomers, the amount of piperylene is 50-80 wt%, more preferably 60-75 wt%; the total amount of the first part of styrene and the second part of styrene is 20-50 wt%, more preferably 25-40 wt%.

[0078] In one embodiment of the present invention, the method of contacting styrene and piperylene includes: performing a first polymerization of styrene in the presence of an organic lithium initiator and a tetrahydrofuran-based compound, adding piperylene to the material after the first polymerization for a second polymerization, and adding a coupling agent to the material after the second polymerization for coupling to obtain a styrene-piperylene-styrene star copolymer. Preferably, the temperature for the first polymerization is 60-70°C, the temperature for the second polymerization is 60-100°C, and the temperature for the coupling is 60-100°C.

[0079] In the present invention, preferably, based on the total weight of the monomers, the amount of piperylene used is 50-80% by weight, more preferably 60-75% by weight; the amount of styrene used is 20-50% by weight, more preferably 25-40% by weight.

[0080] In the present invention, the coupling agent can be a coupling agent conventionally used in the art. Preferably, the coupling agent is selected from at least one of a multifunctional Lewis acid, divinylbenzene, a polyvinyl derivative and a polyepoxy compound, more preferably at least one of silicon tetrachloride, tin tetrachloride, divinylbenzene and epoxy soybean oil; further preferably silicon tetrachloride.

[0081] More preferably, the molar ratio of the coupling agent to the organic lithium initiator is 0.1-0.25:1, for example, it can be 0.1:1, 0.15:1, 0.2:1, 0.25:1, and any range between any two values.

[0082] Preferably, the coupling time is 20-30 min. Under the preferred coupling time, higher coupling efficiency and coupling rate can be achieved.

[0083] Among them, the star-shaped block copolymer can be represented by the general formula (SB) n R' represents, preferably, n is an integer of 2-5, and R' represents a coupling agent residue. For example, when the coupling agent is silicon tetrachloride, R' represents a silicon atom.

[0084] In the present invention, the method may further include: adding a terminator to the product after the polymerization reaction to terminate the polymerization.

[0085] The terminator may be a conventional terminator in the art. Preferably, the terminator is selected from at least one of water, C1-C10 fatty alcohols, C6-C15 phenols and C7-C15 aromatic alcohols.

[0086] The C1-C10 fatty alcohol may be a monohydric alcohol or a polyhydric alcohol having a C1-C15 alkyl group, including but not limited to methanol, ethanol, isopropanol, butanol, pentanol, hexanol, cyclohexanol, heptanol, octanol, nonanol, and decanol.

[0087] The C6-C15 phenols may be monophenols or polyphenols having a C6-C15 aromatic hydrocarbon group, including but not limited to phenol, hydroquinone, p-cresol and naphthol.

[0088] The C6-C15 aromatic alcohol may be a monohydric alcohol or a polyhydric alcohol having a C6-C15 aromatic hydrocarbon group, including but not limited to benzyl alcohol, phenylethyl alcohol, phenyl isopropyl alcohol, naphthalene methanol and anthracene methanol.

[0089] Preferably, the molar ratio of the amount of the terminator to the amount of the organic lithium initiator is 1-1.5:1.

[0090] Preferably, the method further comprises: adding an antioxidant to the product after the polymerization reaction. Generally, the antioxidant can be added before removing the organic solvent from the product after the polymerization reaction.

[0091] The antioxidant can be an antioxidant commonly used in the art, such as a classification or amine. Preferably, the antioxidant is selected from 2,6-di-tert-butyl-p-cresol (antioxidant 264), tert-butyl catechol and 2,2′-methylene-bis(4-methyl-6-tert-butylphenol) (antioxidant 2246).

[0092] The amount of the antioxidant can be selected within a wide range. Preferably, the amount of the antioxidant is 0.1-2 wt % of the total weight of the styrene-piperylene-styrene star copolymer, more preferably 0.5-0.8 wt %.

[0093] In the present invention, preferably, the polymerization reaction is carried out under an inert atmosphere. The inert atmosphere can be an inert atmosphere commonly used in the art, including but not limited to at least one of nitrogen, argon and helium.

[0094] In the present invention, the reagents and materials involved can all be obtained commercially.

[0095] The third aspect of the present invention provides a styrene-piperylene-styrene block copolymer prepared by the method described above.

[0096] A fourth aspect of the present invention provides the use of the styrene-piperylene-styrene block copolymer described above in hot melt adhesives, high-hardness elastomers, and thermal memory deformation materials.

[0097] In the present invention, the high-hardness elastomer refers to an elastomer having a hardness of 70 Shore A or higher.

[0098] The present invention will be described in detail below through examples.

[0099] In the following examples, the molecular weight and coupling efficiency of the polymers were measured using a Shimadzu LC-10A series gel permeation chromatograph at room temperature with THF as the mobile phase solvent.

[0100] The microstructures such as styrene content, 1,2-structure content and trans-1,4-structure content were measured using an AVANCE DRX 400 MHz nuclear magnetic vibration spectrometer from Bruker, Switzerland, at room temperature using the liquid cell method and CS2 as the solvent.

[0101] The solvent composition and monomer conversion were determined by Agilent GC-7820 hydrogen flame gas chromatograph and calculated by internal standard method.

[0102] Polymer samples were preformed into sheets according to GB 6734 standard and then compression molded according to GB / T528-2009 standard. The sample weight was generally 34-36 g and the sheet thickness was 1 mm.

[0103] The physical and mechanical properties of polymers were tested using a G7-AI-3000 tensile testing machine according to GB / T528-2009 standard.

[0104] In the following examples, except for Example 8, the organic solvent was a cyclohexane / n-hexane mixed solvent (weight ratio of 82 / 18).

[0105] In the following examples, unless otherwise specified, the reagents and materials used were commercially available.

[0106] In the following examples, tetrahydrofuranyl compounds and tetrahydrofuran were purchased from Aladdin Reagent Company.

[0107] In the following examples, a specific temperature is provided by a heat preservation device.

[0108] Example 1

[0109] This example is used to illustrate the method for synthesizing styrene-piperylene-styrene triblock copolymer according to the present invention.

[0110] Under high-purity nitrogen, 2.35 L of organic solvent, 38 g of styrene, and 0.375 mmol of a tetrahydrofuranyl compound were added sequentially to a 10 L polymerization reactor. After the polymerization system was deoxygenated by displacement with high-purity nitrogen, 2.5 mmol of n-butyl lithium was added to initiate polymerization at a temperature of 60°C and a pressure of 0.3 MPa. 15 minutes into the polymerization, styrene conversion reached 100%. Subsequently, 175 g of piperylene was added, and the reaction was continued at 80°C for 40 minutes, achieving a 100% conversion of the piperylene monomer. Finally, 38 g of styrene was added, and the reaction was continued at 60°C for 20 minutes. The reaction was terminated with methanol (molar ratio of methanol to n-butyl lithium: 1.1:1). The tetrahydrofuranyl compound was tetrahydrofurfuryl alcohol ethyl ether (THFE).

[0111] The glue solution was removed for structural and physical property analysis. Structural analysis included number average molecular weight (Mn), molecular weight distribution (PDI), 1,2-structure content, trans-1,4-structure content, and styrene content. Detailed results are shown in Table 1. Physical property analysis included permanent set, 300% modulus, tensile strength, and elongation at break. Detailed results are shown in Table 2.

[0112] Example 2

[0113] This example is used to illustrate the method for synthesizing styrene-piperylene-styrene triblock copolymer according to the present invention.

[0114] The operation was carried out according to the method described in Example 1, except that the tetrahydrofuran compound was ditetrahydrofurfuryl propane (DTHFP), and the added amount thereof was 0.25 mmol.

[0115] The structural analysis includes number average molecular weight (Mn), molecular weight distribution (PDI), 1,2-structure content, trans-1,4-structure content and styrene content. The specific results are shown in Table 1. The physical property analysis includes permanent deformation, 300% modulus, tensile strength and elongation at break. The specific results are shown in Table 2.

[0116] Example 3

[0117] This example is used to illustrate the method for synthesizing styrene-piperylene-styrene triblock copolymer according to the present invention.

[0118] The operation was carried out according to the method described in Example 1, except that the tetrahydrofuranyl compound was N,N-dimethyltetrahydrofurfurylamine DMTHFA, and the added amount thereof was 0.25 mmol.

[0119] The structural analysis includes number average molecular weight (Mn), molecular weight distribution (PDI), 1,2-structure content, trans-1,4-structure content and styrene content. The specific results are shown in Table 1. The physical property analysis includes permanent deformation, 300% modulus, tensile strength and elongation at break. The specific results are shown in Table 2.

[0120] The operation was carried out under the above conditions, except that the content of N,N-dimethyltetrahydrofurfurylamine was adjusted, and the conversion kinetic curve of piperylene was measured at different ratios of N,N-dimethyltetrahydrofurfurylamine to n-butyllithium (0.05-0.5). Figure 2 As shown. Figure 2 It can be seen that the use of this technical solution can achieve complete conversion of piperylene within 25-45 minutes.

[0121] Example 4

[0122] This example is used to illustrate the method for synthesizing styrene-piperylene-styrene triblock copolymer according to the present invention.

[0123] The operation was carried out according to the method described in Example 1, except that the tetrahydrofuranyl compound was pyrrolidine tetrahydrofurfurylamine THPTHFA, and the added amount thereof was 0.5 mmol.

[0124] The structural analysis includes number average molecular weight (Mn), molecular weight distribution (PDI), 1,2-structure content, trans-1,4-structure content and styrene content. The specific results are shown in Table 1. The physical property analysis includes permanent deformation, 300% modulus, tensile strength and elongation at break. The specific results are shown in Table 2.

[0125] Example 5

[0126] This example is used to illustrate the method for synthesizing styrene-piperylene-styrene star block copolymers according to the present invention.

[0127] Under high-purity nitrogen, 2.35 L of organic solvent, 76 g of styrene, and 0.5 mmol of a tetrahydrofuranyl compound were added sequentially to a 10 L polymerization reactor. After deoxygenation of the polymerization system by displacement with high-purity nitrogen, 2.5 mmol of n-butyl lithium was added to initiate polymerization. The polymerization initiation temperature was 60°C, and the reaction pressure was 0.3 MPa. Fifteen minutes into the polymerization, 100% styrene conversion was measured. Then, 175 g of isopentylene was added and reacted at 80°C for 35 minutes. Finally, 0.54 mmol of silicon tetrachloride was added for a coupling reaction. After 25 minutes of coupling, the reaction was terminated with isopropanol (molar ratio of isopropanol to n-butyl lithium: 1.1:1), and antioxidant 264 was added at 0.5% by weight of the monomers. The tetrahydrofuranyl compound was pyrrolidine tetrahydrofurfurylamine (THPTHFA).

[0128] The glue solution was removed for structural and physical property analysis. Structural analysis included number average molecular weight (Mn), molecular weight distribution (PDI), 1,2-structure content, trans-1,4-structure content, styrene content, and coupling efficiency. Detailed results are shown in Table 1. Physical property analysis included permanent set, 300% modulus, tensile strength, and elongation at break. Detailed results are shown in Table 2.

[0129] Example 6

[0130] This example is used to illustrate the method for synthesizing styrene-piperylene-styrene star block copolymers according to the present invention.

[0131] The operation was carried out according to the method described in Example 5, except that the tetrahydrofuran compound was ditetrahydrofurfuryl propane DTHFP, and the added amount thereof was 0.5 mmol.

[0132] The glue solution was removed for structural and physical property analysis. Structural analysis included number average molecular weight (Mn), molecular weight distribution (PDI), 1,2-structure content, trans-1,4-structure content, styrene content, and coupling efficiency. Detailed results are shown in Table 1. Physical property analysis included permanent set, 300% modulus, tensile strength, and elongation at break. Detailed results are shown in Table 2.

[0133] Example 7

[0134] This example is used to illustrate the method for synthesizing styrene-piperylene-styrene star block copolymers according to the present invention.

[0135] The operation was carried out according to the method described in Example 1, except that the tetrahydrofuranyl compound was tetrahydrofurfuryl alcohol butyl ether.

[0136] The glue solution was removed for structural and physical property analysis. Structural analysis included number average molecular weight (Mn), molecular weight distribution (PDI), 1,2-structure content, trans-1,4-structure content, styrene content, and coupling efficiency. Detailed results are shown in Table 1. Physical property analysis included permanent set, 300% modulus, tensile strength, and elongation at break. Detailed results are shown in Table 2.

[0137] Example 8

[0138] This example is used to illustrate the method for synthesizing styrene-piperylene-styrene star block copolymers according to the present invention.

[0139] The operation was carried out according to the method described in Example 1, except that the solvent was selected to be an equal volume of cyclopentane and the monomer concentration was 20 wt%.

[0140] The structural analysis includes number average molecular weight (Mn), molecular weight distribution (PDI), 1,2-structure content, trans-1,4-structure content and styrene content. The specific results are shown in Table 1. The physical property analysis includes permanent deformation, 300% modulus, tensile strength and elongation at break. The specific results are shown in Table 2.

[0141] Example 9

[0142] This example is used to illustrate the method for synthesizing styrene-piperylene-styrene star block copolymers according to the present invention.

[0143] The procedure described in Example 5 was followed, except that divinylbenzene was used as the coupling agent.

[0144] The structural analysis includes number average molecular weight (Mn), molecular weight distribution (PDI), 1,2-structure content, trans-1,4-structure content and styrene content. The specific results are shown in Table 1. The physical property analysis includes permanent deformation, 300% modulus, tensile strength and elongation at break. The specific results are shown in Table 2.

[0145] Comparative Example 1

[0146] This comparative example is used to illustrate the method for synthesizing styrene-piperylene-styrene triblock copolymers.

[0147] Under high-purity nitrogen, 2.35 L of organic solvent, 38 g of styrene, and 5 mmol of tetrahydrofuran (THF) were added sequentially to a 10 L polymerization kettle. After the polymerization system was deoxygenated by displacement with high-purity nitrogen, 2.5 mmol of n-butyl lithium was added to initiate polymerization. The polymerization initiation temperature was 60°C, and the reaction pressure was 0.3 MPa. Fifteen minutes into the polymerization reaction, the styrene conversion reached 100%. Then, 260 mL (175 g) of di-piperylene was added and the reaction was continued at 80°C for 60 minutes. The conversion of the di-piperylene monomer was measured to be 70%. Finally, the tri-piperylene was added and the reaction was continued at 60°C for 20 minutes. Methanol was then added to terminate the reaction.

[0148] The glue solution was removed and subjected to structural and physical property analysis. Structural analysis included number average molecular weight (Mn), molecular weight distribution (PDI), 1,2-structure content, trans-1,4-structure content, and styrene content. Detailed results are shown in Table 1. Physical property analysis included permanent set, 300% modulus, tensile strength, and elongation at break. Detailed results are shown in Table 2.

[0149] Comparative Example 2

[0150] This comparative example is used to illustrate the method for synthesizing styrene-piperylene-styrene triblock copolymers.

[0151] The operation was carried out according to the method described in Example 1, except that tetrahydrofurfuryl alcohol ethyl ether was not added, and the conversion rate of piperylene was 60%.

[0152] The structural analysis includes number average molecular weight (Mn), molecular weight distribution (PDI), 1,2-structure content, trans-1,4-structure content and styrene content. The specific results are shown in Table 1. The physical property analysis includes permanent deformation, 300% modulus, tensile strength and elongation at break. The specific results are shown in Table 2.

[0153] Under the above conditions, during the polymerization of piperylene, different temperatures were adjusted and the kinetic conversion curve of piperylene was measured, such as Figure 2 As shown, from Figure 2 It can be seen that even at a high temperature of 353 K, the complete conversion of isopentadiene monomers requires at least 2 h.

[0154] Table 1

[0155]

[0156] Table 2

[0157] Physical property analysis Permanent deformation / % 300% tensile strength / MPa Tensile strength / MPa Elongation at break / % Example 1 39 3.9 10.2 1100 Example 2 44 5.1 16.8 920 Example 3 50 5.8 19.1 800 Example 4 59 7 22.3 670 Example 5 45 4.9 17.1 900 Example 6 43 5 18.0 870 Example 7 45 4.9 18.2 1100 Example 8 54 5.0 16.5 990 Example 9 60 5.9 19.0 890 Comparative Example 1 89 3.8 8.9 510 Comparative Example 2 80 3.2 6.1 340

[0158] The results in Tables 1 and 2 show that the SPS triblock copolymer prepared by the scheme described in the present invention has a better 1,2-structure regulation effect than the comparative example, the conversion of the isoprene soft segment is complete, and the molecular weight distribution of the obtained SPS is narrow, which has a significant effect on the stable improvement of mechanical properties.

[0159] The results in Tables 1 and 2 show that when the SPS star-shaped block copolymer is prepared using the scheme of the present invention, the coupling efficiency is ≥85%, the conversion rate of piperylene is high, the branched structure is high, and the prepared SPS has excellent mechanical properties.

[0160] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A styrene-piperylene-styrene block copolymer, characterized in that: The styrene-piperylene-styrene block copolymer has a 1,2-structure content of 20-50% by weight, the styrene-piperylene-styrene block copolymer has a trans-1,4-structure content of 35-60% by weight, and the styrene structural unit content of the styrene-piperylene-styrene block copolymer is 20-50% by weight and the piperylene structural unit content is 50-80% by weight. The synthesis method of the styrene-piperylene-styrene block copolymer comprises: contacting styrene and piperylene in the presence of an organic lithium initiator and a tetrahydrofuran compound to carry out a polymerization reaction; The tetrahydrofuranyl compound has at least one of the structures represented by formula (IV) and formula (V), Formula (IV), Formula (V), wherein R1 is H or a C1-C3 alkyl group, R2 is H or a C1-C3 alkyl group, R5 is a C1-C4 alkyl group, and R6 is a C1-C4 alkyl group; n is an integer from 1 to 4; Relative to the total weight of 100g of styrene and piperylene, the amount of the organic lithium initiator is 0.2-3mmol, and the molar ratio of the tetrahydrofuran compound to the organic lithium initiator is 0.01-1:

1.

2. The styrene-piperylene-styrene block copolymer according to claim 1, wherein The number average molecular weight of the styrene-piperylene-styrene block copolymer is 20,000-1,000,000.

3. The styrene-piperylene-styrene block copolymer according to claim 1 or 2, wherein The molecular weight distribution of the styrene-piperylene-styrene block copolymer is less than 1.

3.

4. The styrene-piperylene-styrene block copolymer according to claim 1 or 2, wherein The content of tetrahydrofuranyl compounds in the styrene-piperylene-styrene block copolymer is below 25 ppm.

5. The styrene-piperylene-styrene block copolymer according to claim 1 or 2, wherein The permanent deformation of the styrene-piperylene-styrene block copolymer is 30-70%.

6. The styrene-piperylene-styrene block copolymer according to claim 1 or 2, wherein The 300% modulus of the styrene-isopentadiene-styrene block copolymer is 3.5-8 MPa.

7. The styrene-piperylene-styrene block copolymer according to claim 1 or 2, wherein The tensile strength of the styrene-piperylene-styrene block copolymer is 10-25 MPa.

8. The styrene-piperylene-styrene block copolymer according to claim 1 or 2, wherein The elongation at break of the styrene-piperylene-styrene block copolymer is 600-1200%.

9. The styrene-piperylene-styrene block copolymer according to claim 1 or 2, wherein The hardness of the styrene-piperylene-styrene block copolymer is 70-100 Shore A hardness.

10. The styrene-piperylene-styrene block copolymer according to claim 1, wherein The organic lithium initiator is an alkyl lithium initiator and / or a functionalized organic lithium initiator.

11. The styrene-piperylene-styrene block copolymer according to claim 10, wherein The organic lithium initiator is an alkyl lithium initiator.

12. The styrene-piperylene-styrene block copolymer according to claim 10, wherein: The alkyl lithium initiator is at least one selected from 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.

13. The styrene-piperylene-styrene block copolymer according to claim 11 or 12, wherein The alkyl lithium initiator is n-butyl lithium and / or sec-butyl lithium.

14. The styrene-piperylene-styrene block copolymer according to claim 1, wherein: The amount of the organic lithium initiator used is 0.8-1.5 mmol relative to the total weight of 100 g of styrene and piperylene.

15. The styrene-piperylene-styrene block copolymer according to claim 1, wherein The polymerization reaction is carried out in the presence of an organic solvent.

16. The styrene-piperylene-styrene block copolymer according to claim 15, wherein The polymerization reaction is carried out in the presence of a hydrocarbon solvent. 17 . The styrene-piperylene-styrene block copolymer according to claim 16 , wherein the hydrocarbon solvent is at least one selected from the group consisting of C5-C12 alkanes, C5-C12 cycloalkanes, and C6-C12 aromatic hydrocarbons.

18. The styrene-piperylene-styrene block copolymer according to claim 17, wherein: The hydrocarbon solvent is selected from at least one of cyclopentane, methylcyclopentane, cyclohexane, n-hexane and raffinate oil.

19. The styrene-piperylene-styrene block copolymer according to claim 15, wherein: The organic solvent is used in an amount such that the monomer concentration is 5-30 wt %.

20. The styrene-piperylene-styrene block copolymer according to claim 19, wherein The organic solvent is used in an amount such that the monomer concentration is 10-25 wt %.

21. The styrene-piperylene-styrene block copolymer according to claim 1, wherein: The polymerization reaction conditions include: temperature of 25-150° C. and pressure of 0.1-1.5 MPa.

22. The styrene-piperylene-styrene block copolymer according to claim 1, wherein: The polymerization reaction conditions include: temperature of 50-120° C. and pressure of 0.1-0.3 MPa.

23. The styrene-piperylene-styrene block copolymer according to claim 1, wherein: The method of contacting styrene and piperylene comprises: subjecting a first portion of styrene to a first polymerization in the presence of an organic lithium initiator and a tetrahydrofuran compound, then adding piperylene to the material after the first polymerization to conduct a second polymerization, and then adding a second portion of styrene to the material after the second polymerization to conduct a third polymerization to obtain a styrene-piperylene-styrene triblock copolymer.

24. The styrene-piperylene-styrene block copolymer according to claim 23, wherein: The mass ratio of the first part of styrene to the second part of styrene is 1:0.5-2.

25. The styrene-piperylene-styrene block copolymer according to claim 23 or 24, wherein Based on the total weight of the monomers, the amount of the piperylene is 50-80% by weight, and the total amount of the first part of styrene and the second part of styrene is 20-50% by weight.

26. The styrene-piperylene-styrene block copolymer according to claim 23, wherein: Based on the total weight of the monomers, the amount of the piperylene is 60-75% by weight, and the total amount of the first part of styrene and the second part of styrene is 25-40% by weight.

27. The styrene-piperylene-styrene block copolymer according to claim 1, wherein The method of contacting styrene and piperylene comprises: first polymerizing styrene in the presence of an organic lithium initiator and a tetrahydrofuran compound, adding piperylene to the material after the first polymerization for second polymerization, and adding a coupling agent to the material after the second polymerization for coupling to obtain a styrene-piperylene-styrene star copolymer.

28. The styrene-piperylene-styrene block copolymer according to claim 27, wherein Based on the total weight of the monomers, the amount of piperylene used is 50-80% by weight, and the amount of styrene used is 20-50% by weight.

29. The styrene-piperylene-styrene block copolymer according to claim 27 or 28, wherein Based on the total weight of the monomers, the amount of piperylene used is 60-75% by weight, and the amount of styrene used is 25-40% by weight.

30. The styrene-piperylene-styrene block copolymer according to claim 27, wherein: The coupling time is 20-30 min.

31. The styrene-piperylene-styrene block copolymer according to claim 27, wherein: The coupling agent is selected from at least one of multifunctional Lewis acid, divinylbenzene, polyvinyl derivatives and polyepoxy compounds.

32. The styrene-piperylene-styrene block copolymer according to claim 27 or 31, wherein The coupling agent is selected from at least one of silicon tetrachloride, tin tetrachloride, divinylbenzene and epoxy soybean oil.

33. The styrene-piperylene-styrene block copolymer according to claim 27, wherein: The molar ratio of the coupling agent to the organic lithium initiator is 0.1-0.25:

1.

34. Use of the styrene-isopentadiene-styrene block copolymer according to any one of claims 1 to 33 in hot melt adhesives, high hardness elastomers and thermal memory deformation materials.

Images