CN113929843A

CN113929843A - Styrene-piperylene-styrene block copolymer and synthetic method and application thereof

Info

Publication number: CN113929843A
Application number: CN202010609463.3A
Authority: CN
Inventors: 刘坤; 夏金魁; 李安; 邱旭; 王旭; 佘振银; 燕富成
Original assignee: China Petroleum and Chemical Corp; Sinopec Baling Co
Current assignee: China Petroleum and Chemical Corp; Sinopec Baling Co
Priority date: 2020-06-29
Filing date: 2020-06-29
Publication date: 2022-01-14

Abstract

The invention relates to the field of thermoplastic elastomers, and discloses a styrene-piperylene-styrene block copolymer, a synthetic method and application thereof, wherein the content of a 1, 2-structure in the styrene-piperylene-styrene block copolymer (SPS) is 20-50 wt%. Compared with SBS and SIS, the SPS has the advantages of high trans-1, 4-structure, high branching degree, high hardness, high elasticity, low plasticity, high coupling efficiency and the like. The invention adopts an initiation system consisting of organic lithium and tetrahydrofuran compounds, can adjust SPS branched 1, 2-structure, can improve polymerization reaction rate, and can ensure normal operation of subsequent coupling reaction without controlling temperature in the polymerization process. The tetrahydrofuran compound can greatly shorten the SPS single kettle polymerization time, is beneficial to reducing energy consumption and material consumption, and has excellent microstructure regulation and control stability in the polymerization process, thereby having great industrial application prospect.

Description

Styrene-piperylene-styrene block copolymer and synthetic method and application thereof

Technical Field

The invention relates to the field of macromolecules, in particular to a styrene-piperylene-styrene segmented copolymer, and a synthetic method and application thereof.

Background

Butadiene and isoprene based triblock copolymers are important members of the traditional lithium-based thermoplastic elastomer family, such materials combine the characteristics of plastics and rubber, have high elasticity, high strength and excellent resilience of rubber, and simultaneously have injection molding processing characteristics, and SBS/SIS becomes the styrene thermoplastic elastomer (TPE) with the highest consumption at present (the global market demand of thermoplastic elastomers exceeds 600 million tons).

The structure of the poly-conjugated diene determines the performance, the butadiene, the isoprene and the piperylene are polymerized to generate an unsaturated elastic carbon chain with a certain branched structure content, and the special double bond cis-trans isomerism and the different side chain structure of the unsaturated elastic carbon chain endow the elastomer with special performance. For example, side chain vinyl SBS elastomers are mainly used for making shoes (soles), rubber tubes and adhesive tapes; can also be used as a modifier for polypropylene (PP), Polyethylene (PE) and Polystyrene (PS) resin, and obviously improves the low-temperature performance and the impact strength of the product; SBS as adhesive has high solid matter content, fast drying and low temperature resistance; the SBS serving as a modifier of the building asphalt and the road asphalt can obviously improve the weather resistance, the load resistance and the like of the asphalt. The main chain double bond of the SIS elastomer tends to form cis-4, 1-polymerization to produce a high-elasticity carbon chain, and the method is mainly used in the field of pressure-sensitive adhesives.

Therefore, the development of a novel specific thermoplastic elastomer material further expands the market of the existing TPE and has great economic value.

Disclosure of Invention

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

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

In a second aspect, the present invention provides a method for synthesizing a styrene-piperylene-styrene block copolymer, the method comprising: styrene and piperylene are contacted in the presence of an organolithium initiator and a tetrahydrofuranyl compound to carry out a polymerization reaction.

Preferably, the tetrahydrofuranyl compound has a structure represented by formula (I),

wherein R is₁Is H or C1-C3 alkyl; r₂Is H or C1-C3 alkyl; r₃Is a group containing O or N.

More preferably, the tetrahydrofuranyl compound has at least one of the structures shown in formula (II), formula (III), formula (IV) and formula (V),

wherein R is₄Is C1-C6 alkyl or C6-C12 aryl, R₅Is C1-C4 alkyl, R₆Is C1-C4 alkyl; n is 1-4An integer number.

In a third aspect, the present invention provides a styrene-piperylene-styrene block copolymer prepared by the above-mentioned method.

The invention provides the application of the styrene-piperylene-styrene segmented copolymer in hot melt adhesives, high-hardness elastomers and thermal memory deformation materials.

The styrene-piperylene-styrene segmented copolymer has the advantages of controllable molecular weight, high trans-1, 4-structure, high branching degree, high hardness, narrow molecular weight distribution and excellent mechanical property.

The invention adopts an initiation system consisting of alkyl lithium and tetrahydrofuran compounds, can adjust SPS branched 1, 2-structure, simultaneously can ensure faster reaction rate of styrene and m-pentadiene, particularly remarkably improves the conversion rate of m-pentadiene monomer, further improves the polymerization reaction rate and shortens the polymerization time to 25-45 min. Meanwhile, the hydrophilicity is stronger, so that the residue in the post-treatment is extremely low, and the regulator in the SPS basically has no residue, thereby being beneficial to the improvement of the product quality.

The method can ensure the normal operation of the subsequent coupling reaction without controlling the temperature of the polymerization process, and the coupling efficiency can reach more than 85 percent.

The method can greatly shorten the SPS single kettle polymerization time, is beneficial to reducing energy consumption and material consumption, has excellent microstructure regulation and control stability in the polymerization process, and has great industrial application prospect.

Drawings

FIG. 1 is a graph showing the conversion kinetics of piperylene under different ratios of N, N-dimethyltetrahydrofurfuryl amine to N-butyllithium in example 3 of the present invention;

FIG. 2 is a graph showing the kinetics of piperylene conversion under different temperature conditions in comparative example 2 of the present invention without adding dimethyltetrahydrofurfuryl amine.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The inventor of the invention finds in the research process that compared with the difference of double bond configuration and branched structure of SBS and SIS triblock copolymer, SPS has high trans-1, 4-structure and stable and controllable high steric hindrance branched structure, which is similar to the structure of tackified piperylene petroleum resin, the trans-1, 4-structure is beneficial to improving the viscosity of piperylene copolymer and simultaneously improving the hardness of the product, and the 1, 2-structure can be uniformly inserted into the trans-1, 4-structure to destroy the crystallinity of SPS structure, improve the branched degree, and be beneficial to improving the elastic property and reducing the plastic property of the product.

In a first aspect, 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%, for example, 25, 28, 30, 32, 35, 38, 40, 42, 45, 48, 50 wt%, or any range between any two values.

Preferably, the content of 1, 2-structure in the styrene-piperylene-styrene block copolymer is 30 to 50% by weight. In the preferable range, the 1, 2-structure can be stably regulated and controlled to be uniformly inserted into the high trans-1, 4-structural unit, so that the crystallization performance of the high trans-structure is favorably reduced, and the elastic deformation of the high trans-structure is improved.

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

In the present invention, the content of the styrene monomer in the styrene-piperylene-styrene block copolymer may be selected within a wide range, and preferably, the content of the styrene monomer is 20 to 50 wt%; more preferably, the styrene monomer content is 25 to 40% by weight. Within the preferred ranges, excellent mechanical properties, high hardness and softening point introduced by physical crosslinking of polystyrene can be ensured.

In the present invention, the content of piperylene monomer in the styrene-piperylene-styrene block copolymer can be selected within a wide range, preferably, the content of piperylene monomer is 50-80 wt%; more preferably, the piperylene monomer is present in an amount of 60 to 75 wt%. Within the preferable range, good elastic deformation, tackifying property and low-temperature applicability brought by introduction of soft-segment polypentadiene can be ensured.

Preferably, the styrene-piperylene-styrene block copolymer has a number average molecular weight of 2 to 100 ten thousand, more preferably 5 to 50 ten thousand.

Preferably, the styrene-piperylene-styrene block copolymer has a molecular weight distribution of less than 1.3, preferably from 1.04 to 1.2.

Preferably, the permanent set of the styrene-piperylene-styrene block copolymer is 30-70%.

Preferably, the styrene-piperylene-styrene block copolymer has a 300% tensile strength of 3.5 to 8 MPa.

Preferably, the styrene-piperylene-styrene block copolymer has a tensile strength of 10 to 25 MPa.

Preferably, the styrene-piperylene-styrene block copolymer has an elongation at break of 600-.

Preferably, the styrene-piperylene-styrene block copolymer has a hardness of 70-100 shore a. The hardness of SPS is generally about 10 shore a higher than that of SBS with the same content of styrene structural units.

Preferably, the content of the tetrahydrofuran-based compound in the styrene-piperylene-styrene block copolymer is below 25 ppm. Among them, the kind of the tetrahydrofuranyl compound is explained in detail in the second aspect.

In the present invention, the styrene-piperylene-styrene block copolymer may be of a type conventional in the art, and may be, for example, a styrene-piperylene-styrene triblock copolymer and a styrene-piperylene-styrene star block copolymer.

In the invention, the microstructure such as styrene content, 1, 2-structure content and trans-1, 4 structure can be measured by AVANCE DRX 400MHz nuclear magnetic resonance spectrometer of Bruker company in Switzerland.

In the present invention, the molecular weight of the block copolymer can be measured by a Nippon Shimadzu LC-10A series gel permeation chromatograph.

In the present invention, the physical and mechanical properties of the block copolymer can be measured by using a tensile machine of G7-AI-3000 type according to GB/T528-2009 standard.

In the invention, the hardness of the block copolymer can be measured by a Shore durometer according to the GB/T531.1-2008 standard.

When the inventor of the present invention prepares SPS, it is found that Tetrahydrofuran (THF) or Tetramethylethylenediamine (TMEDA) generally used in the conventional lithium-based polymerization process as a regulator can regulate the soft-segment branched structure content and is also beneficial to increase the initiation and growth rate of polymerization, but THF or TMEDA has the following defects: firstly, the boiling point of the regulator is low under normal pressure, and the regulator is easy to remain after a solvent refining process, so that the quantitative fluctuation of the regulator in a solvent system is large, and the quality stability of a product is influenced; secondly, the regulator has good solubility in glue solution, and is difficult to completely remove in a post-treatment water washing process, so that the regulator is volatilized in a forming extrusion process; meanwhile, the coordination of THF and alkyl lithium is weak, the two-stage polymerization rate is very high, the temperature rise is very obvious (the instantaneous high temperature exceeds 120 ℃), and the coordination is reduced due to the large temperature change, so that the 1, 2-structure regulation is unstable. Finally, in order to ensure the smooth proceeding of the branched structure and/or coupling reaction of the product, the polymerization process needs to be artificially controlled by reducing the polymerization initiation temperature and controlling the maximum polymerization temperature. While lowering the polymerization temperature will prolong the polymerization reaction time, temperature control will cause instability of product quality; at the same time, silicon tetrachloride (SiCl) is used₄) When the reactive species end group coupling reaction is carried out, higher reaction temperature is needed to be beneficial to reducing the viscosity of the system, and the mode of controlling the reaction temperature is not beneficial to the progress of the coupling reaction.

The results show that, surprisingly, in the synthesis of polystyrene-polypentadiene-polystyrene block copolymer (SPS), an initiation system composed of organic lithium and tetrahydrofuran-based compound is adopted, so that the stable regulation of 1, 2-structure and polymerization rate can be realized, and meanwhile, the polymerization time of the piperylene can be obviously shortened. Interestingly, unlike the rapid temperature rise during butadiene polymerization, the temperature and reaction rate can remain substantially stable during piperylene polymerization without heat removal treatment, and the resulting 1, 2-structure content is substantially free of significant differences over time, which is beneficial to obtaining a product with a stable 1, 2-structure content. In addition, when the star-shaped block copolymer is prepared, high coupling efficiency can be realized at the later stage of polymerization, and the coupling efficiency can reach more than 85 percent. Moreover, compared with other types of regulators, the tetrahydrofuran-based compound can ensure that no regulator remains in the SPS product, thereby improving the quality stability of the product.

In the present invention, the organolithium initiator is preferably an alkyllithium initiator and/or a functionalized organolithium initiator.

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

Examples of organolithium initiators include, but are not limited to, ethyllithium, propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, pentyllithium, hexyllithium, cyclohexyllithium, phenyllithium, methylphenyllithium, naphthyllithium, preferably n-butyllithium or sec-butyllithium. Under the preferable condition, the polymer can be well dissolved in a polymerization solvent, is convenient to store, and has faster initiation rate and easy dissociation association characteristic.

According to some embodiments of the invention, the amount of initiator used during the polymerization process may depend on the size of the molecular weight that is set. Preferably, the organolithium initiator is used in an amount of 0.2 to 3mmol, preferably 0.8 to 1.5mmol, per 100g of monomer, based on the total weight of the monomers. It is to be understood that the monomers refer to styrene monomers and piperylene monomers.

In the present invention, preferably, the tetrahydrofuranyl compound has a structure represented by formula (I),

Preferably, the tetrahydrofuranyl compound has at least one of the structures shown in formula (II), formula (III), formula (IV) and formula (V),

wherein R is₄Is C1-C6 alkyl or C6-C12 aryl, R₅Is C1-C4 alkyl, R₆Is C1-C4 alkyl; n is an integer of 1 to 4.

Wherein, the alkyl of C1-C6 is selected from one of methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl and n-hexyl.

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

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, N-dimethyltetrahydrofurfuryl amine, N-diethyltetrahydrofurfuryl amine, N-pyrrolidinetetrahydrofurfuryl amine, and N-piperidinetetrahydrofurfuryl amine.

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-dimethyl tetrahydrofurfuryl amine, and pyrrolidine tetrahydrofurfuryl amine. Within the preferable range, the alkyl lithium can be quickly dissociated, the branched structure adjusting function is more stable and efficient, and the alkyl lithium is not easy to remain in the post-treatment glue solution due to the strong hydrophilic characteristic.

In a preferred embodiment of the present invention, the tetrahydrofuranyl compound has a high boiling point (140 ℃ or higher).

In the present invention, the molar ratio of the tetrahydrofuran-based compound to the organolithium initiator is preferably 0.01 to 1:1, and may be, 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 therebetween, and more preferably 0.1 to 0.5: 1. Within the preferred range, the method can disassociate the butyl lithium, regulate the 1, 2-structure of the polypiperylene soft segment within the range of 20-50%, and keep the molecular weight distribution of the multi-block copolymer below 1.30.

According to some embodiments of the invention, the polymerization reaction is carried out in the presence of an organic solvent, preferably a hydrocarbon solvent, which may be any hydrocarbon solvent that is inert, preferably a non-polar hydrocarbon solvent. More preferably, the hydrocarbon solvent is at least one selected from alkanes of C5-C12, cycloalkanes of C5-C12, and aromatics of C6-C12.

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

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

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

When the hydrocarbon solvent contains two or more components, it may be a mixture of pure substances, such as a mixed solvent of n-hexane and cyclohexane; mixed hydrocarbon solvents, such as raffinate oils, may also be of a form conventional in the art.

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

Wherein the main component of the raffinate oil can be C5-C8 alkane.

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 to 25% by weight.

In a preferred embodiment of the present invention, the organic solvent is cyclopentane, which can greatly increase the monomer concentration of SPS, and is advantageous for increasing the productivity.

In the present invention, the organic solvent is preferably used in an amount such that the monomer concentration is 5 to 30% by weight, preferably 10 to 25% by weight. Within the preferable range, the low-viscosity characteristics of the polymerized monomers and the polymer in the monomers can be ensured, and the mass and heat transfer characteristics in the polymerization process are facilitated.

It is understood that the monomer concentration refers to the proportion of the sum of the weights of styrene and piperylene relative to the total weight of styrene, piperylene and organic solvent.

In the present invention, the polymerization reaction may be carried out in a batch polymerization manner or a continuous polymerization manner.

In the present invention, the polymerization conditions may be polymerization conditions conventional in the art, and preferably, the polymerization conditions include: the temperature is 25-150 ℃, and more preferably 50-120 ℃; the pressure is 0.1 to 1.5MPa, more preferably 0.1 to 0.3 MPa.

In the present invention, different types of products can be prepared by different contacting methods. For example, a three-step method of sequential feeding can be adopted to prepare the styrene-piperylene-styrene triblock copolymer, and a two-step method of post-coupling can be adopted to prepare the styrene-piperylene-styrene star block copolymer.

In one embodiment of the present invention, the contacting of styrene and piperylene comprises: first polymerizing the first part of styrene in the presence of an organic lithium initiator and a tetrahydrofuran-based compound, then adding piperylene into the first polymerized material for second polymerization, and then adding the second part of styrene into the second polymerized material for third polymerization to obtain the styrene-piperylene-styrene triblock copolymer. Preferably, the temperature of the first polymerization is 60 to 70 ℃, the temperature of the second polymerization is 60 to 100 ℃, and the temperature of the third polymerization is 60 to 70 ℃.

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

Preferably, the piperylene is used in an amount of 50 to 80 wt%, more preferably 60 to 75 wt%, based on the total weight of the monomers; the total amount of the first portion of styrene and the second portion of styrene is 20 to 50% by weight, more preferably 25 to 40% by weight.

In one embodiment of the present invention, the contacting of styrene and piperylene comprises: styrene is subjected to first polymerization in the presence of an organic lithium initiator and a tetrahydrofuran-based compound, piperylene is added into the first polymerized material for second polymerization, and a coupling agent is added into the second polymerized material for coupling, so that the styrene-piperylene-styrene star-shaped copolymer is obtained. Preferably, the temperature of the first polymerization is 60 to 70 ℃, the temperature of the second polymerization is 60 to 100 ℃ and the temperature of the coupling is 60 to 100 ℃.

In the present invention, preferably, the piperylene is used in an amount of 50 to 80 wt%, more preferably 60 to 75 wt%, based on the total weight of the monomers; the styrene is used in an amount of 20 to 50% by weight, more preferably 25 to 40% by weight.

In the present invention, the coupling agent may be a coupling agent conventionally used in the art, and preferably, the coupling agent is selected from at least one of polyfunctional lewis acids, divinylbenzene, polyvinyl derivatives and polyepoxy compounds, more preferably at least one of silicon tetrachloride, tin tetrachloride, divinylbenzene and epoxidized soybean oil; silicon tetrachloride is further preferred.

More preferably, the molar ratio of the coupling agent to the organolithium initiator is from 0.1 to 0.25:1, and can be, for example, 0.1:1, 0.15:1, 0.2:1, 0.25:1, and any range of compositions between any two values.

Preferably, the coupling time is 20-30 min. At the preferred coupling times, higher coupling efficiencies and coupling rates are possible.

Wherein the radial block copolymer may be represented by the general formula (SB)_nR 'represents, preferably, n is an integer from 2 to 5, R' represents a coupling agent residue. For example, when the coupling agent is silicon tetrachloride, the R' is a silicon atom.

In the present invention, the method may further include: a terminator is added to the product after the polymerization reaction to terminate the polymerization.

Wherein, the terminator can be a terminator conventional in the field, and preferably, the terminator is selected from at least one of water, C1-C10 fatty alcohol, C6-C15 phenols and C7-C15 aromatic alcohol.

Wherein the C1-C10 fatty alcohol can be a monohydric or polyhydric alcohol having a C1-C15 alkyl group, including but not limited to methanol, ethanol, isopropanol, butanol, pentanol, hexanol, cyclohexanol, heptanol, octanol, nonanol, decanol.

Wherein, the phenols of C6-C15 can be monohydric phenol or polyhydric phenol with C6-C15 aromatic hydrocarbon group, including but not limited to phenol, hydroquinone, p-cresol and naphthol.

Wherein the aromatic alcohol of C6-C15 may be a mono-or polyhydric alcohol having an aromatic hydrocarbon group of C6-C15, including but not limited to benzyl alcohol, phenethyl alcohol, phenylisopropyl alcohol, napthyl alcohol, and anthracyl alcohol.

Preferably, the molar ratio of the amount of the terminating agent to the amount of the organolithium initiator is 1-1.5: 1.

Preferably, the method further comprises: and adding an anti-aging agent into the product after the polymerization reaction. The anti-aging agent can be added before the organic solvent is removed from the product after the polymerization reaction.

The antioxidant may be one conventionally used in the art, and may be classified as an amine, for example, and is preferably selected from the group consisting of 2, 6-di-tert-butyl-p-cresol (antioxidant 264), tert-butyl catechol, and 2, 2' -methylene-bis (4-methyl-6-tert-butylphenol) (antioxidant 2246).

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

In the present invention, preferably, the polymerization reaction is carried out under an inert atmosphere. The inert atmosphere may be an inert atmosphere conventionally employed in the art, including but not limited to at least one of nitrogen, argon, and helium.

In the present invention, the reagents and materials involved are all commercially available.

In a fourth aspect, the present invention provides the use of the styrene-piperylene-styrene block copolymer as described above in hot melt adhesives, high hardness elastomers and thermal memory deformable materials.

In the present invention, the high-hardness elastomer means an elastomer having a hardness of 70 shore a or more.

The present invention will be described in detail below by way of examples.

In the following examples, the molecular weight and coupling efficiency of the polymer were measured by a LC-10A gel permeation chromatograph, Shimadzu corporation, Japan, at room temperature, and THF was used as a mobile phase solvent.

The microstructure of styrene content, 1, 2-structure content and trans-1, 4-structure content is measured at normal temperature by AVANCE DRX 400MHz nuclear magnetic resonance spectrometer of Bruker, Switzerland, and the solvent is CS 2.

The solvent composition and the monomer reaction conversion rate are measured by an Agilent GC-7820 hydrogen flame gas chromatograph and calculated by an internal standard method.

After a polymer sample is prepared into a pre-molded sheet according to the GB 6734 standard, the sheet is molded according to the GB/T528-2009 standard, the sample mass is generally 34-36g, and the thickness of the sheet is 1 mm.

The physical and mechanical properties of the polymer are tested by a G7-AI-3000 type tensile machine according to GB/T528-2009 standard.

In the following examples, the organic solvent was a cyclohexane/n-hexane mixed solvent (weight ratio: 82/18) except for example 8.

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

In the following examples, tetrahydrofuranyl compounds and tetrahydrofuran were obtained from the Aladdin reagent company.

In the following examples, specific temperatures are provided by the holding device.

Example 1

This example illustrates the synthesis of a styrene-piperylene-styrene triblock copolymer according to the invention

Under the protection of high-purity nitrogen, 2.35L of organic solvent, 38g of styrene and 0.375mmol of tetrahydrofuran compound are sequentially added into a 10L polymerization kettle. After the polymerization system is subjected to displacement deoxidation by high-purity nitrogen, 2.5mmol of n-butyllithium is added to initiate polymerization, the polymerization initiation temperature is 60 ℃, and the reaction pressure is 0.3 MPa. When the polymerization reaction is started for 15min, the conversion rate of styrene is measured to reach 100%, then 175g of piperylene is added, and the reaction is carried out for 40min at 80 ℃, and the conversion rate of piperylene monomer is measured to be 100%. Finally, 38g of styrene was added thereto, and after reacting at 60 ℃ for 20min, the reaction was terminated with methanol (molar ratio to n-butyllithium: 1). Wherein the tetrahydrofuryl compound is tetrahydrofurfuryl alcohol ethyl ether THFE.

Taking out the glue solution for relevant structural analysis and physical analysis. Wherein, the structural analysis comprises the number average molecular weight (Mn), the molecular weight distribution (PDI), the 1, 2-structure content, the trans-1, 4-structure content and the styrene content, and the specific result is shown in Table 1; the physical property analysis includes permanent set, 300% elongation, tensile strength and elongation at break, and the specific results are shown in Table 2.

Example 2

The procedure was as described in example 1, except that the tetrahydrofuranyl compound was ditetrahydrofurfuropropane DTHFP, which was added in an amount of 0.25 mmol.

Wherein, the structural analysis comprises the number average molecular weight (Mn), the molecular weight distribution (PDI), the 1, 2-structure content, the trans-1, 4-structure content and the styrene content, and the specific result is shown in Table 1; the physical property analysis includes permanent set, 300% elongation, tensile strength and elongation at break, and the specific results are shown in Table 2.

Example 3

The procedure was as in example 1, except that the tetrahydrofuranyl compound was N, N-dimethyltetrahydrofurfuryl amine DMTHFA in an amount of 0.25 mmol.

The operation was carried out under the conditions as described above except that the content of N, N-dimethyltetrahydrofurfuryl amine was adjusted, and the conversion kinetic curves of piperylene were measured at different ratios of N, N-dimethyltetrahydrofurfuryl amine to N-butyllithium (0.05-0.5), as shown in FIG. 2. As can be seen from figure 2, by adopting the technical scheme, the complete conversion of piperylene can be realized within 25-45 min.

Example 4

The procedure was as in example 1, except that the tetrahydrofuranyl compound was pyrrolidine tetrahydrofurfuryl amine THPTHFA, which was added in an amount of 0.5 mmol.

Example 5

This example illustrates the synthesis of a styrene-piperylene-styrene radial block copolymer according to the invention

Under the protection of high-purity nitrogen, 2.35L of organic solvent, 76g of styrene and 0.5mmol of tetrahydrofuran compound are sequentially added into a 10L polymerization kettle. After the polymerization system is deoxidized by high-purity nitrogen displacement, 2.5mmol of n-butyllithium is added to initiate polymerization. The polymerization initiation temperature was 60 ℃ and the reaction pressure was 0.3 MPa. When the polymerization reaction starts for 15min, the conversion rate of styrene is measured to reach 100%, then 175g of piperylene is added, the reaction is carried out for 35min at the temperature of 80 ℃, then 0.54mmol of silicon tetrachloride is added for carrying out the coupling reaction, the reaction is terminated by isopropanol (the molar quantity ratio of the isopropanol to the n-butyl lithium is 1.1: 1) after the coupling reaction is carried out for 25min, and an anti-aging agent 264 accounting for 0.5% of the weight of the monomer is added. Wherein the tetrahydrofuryl compound is pyrrolidine tetrahydrofurfuryl amine THPTHFA.

Taking out the glue solution for relevant structural analysis and physical analysis. Wherein, the structural analysis comprises the number average molecular weight (Mn), the molecular weight distribution (PDI), the 1, 2-structure content, the trans-1, 4-structure content, the styrene content and the coupling efficiency, and the specific results are shown in Table 1; the physical property analysis includes permanent set, 300% elongation, tensile strength and elongation at break, and the specific results are shown in Table 2.

Example 6

The procedure was carried out as described in example 5, except that the tetrahydrofuranyl compound was ditetrahydrofurfuropropane DTHFP, which was added in an amount of 0.5 mmol.

Example 7

The procedure was as in example 1 except that the tetrahydrofuranyl compound was tetrahydrofurfuryl alcohol butyl ether.

Example 8

The procedure is as described in example 1, except that the solvent is chosen to be an equal volume of cyclopentane and the monomer concentration is 20% by weight.

Example 9

The procedure was followed as described in example 5, except that the coupling agent was divinylbenzene.

Comparative example 1

This comparative example serves to illustrate a reference method for the synthesis of a styrene-piperylene-styrene triblock copolymer

Under the protection of high-purity nitrogen, 2.35L of organic solvent, 38g of styrene and 5mmol of tetrahydrofuran THF are sequentially added into a 10L polymerization kettle. After the polymerization system is deoxidized by high-purity nitrogen displacement, 2.5mmol of n-butyllithium is added to initiate polymerization. The polymerization initiation temperature was 60 ℃ and the reaction pressure was 0.3 MPa. When the polymerization reaction is started for 15min, the conversion rate of styrene is measured to reach 100%, then 260mL (175g) of secondary piperylene is added, the reaction is carried out for 60min at 80 ℃, and the conversion rate of piperylene monomer is measured to be 70%. Finally, three segments of styrene are added, and after the reaction is carried out for 20min at the temperature of 60 ℃, methanol is added to stop the reaction.

Taking out the glue solution and stopping the glue solution to perform related structural analysis and physical analysis. Wherein, the structural analysis comprises the number average molecular weight (Mn), the molecular weight distribution (PDI), the 1, 2-structure content, the trans-1, 4-structure content and the styrene content, and the specific result is shown in Table 1; the physical property analysis includes permanent set, 300% elongation, tensile strength and elongation at break, and the specific results are shown in Table 2.

Comparative example 2

The procedure was followed as described in example 1, except that tetrahydrofurfuryl alcohol ethyl ether was not added and the piperylene conversion was 60%.

Under the above conditions, during the polymerization of piperylene, different temperatures were adjusted and the kinetic conversion curve of piperylene was determined, as shown in fig. 2, it can be seen from fig. 2 that it takes at least 2h for the monomer conversion of piperylene to be complete even at 353K high temperature.

TABLE 1

TABLE 2

Physical Property analysis	Permanent deformation/%)	300% elongation at break/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

As can be seen from the results in tables 1 and 2, when the SPS triblock copolymer is prepared by adopting the scheme of the invention, compared with a comparative example, the SPS triblock copolymer has a better 1, 2-structure regulation and control effect, the pentadiene soft segment is completely converted, and the obtained SPS has a narrow molecular weight distribution and an obvious effect on stable improvement of mechanical properties.

As can be seen from the results in tables 1 and 2, when the SPS star-shaped block copolymer is prepared by adopting the scheme disclosed by the invention, the coupling efficiency is more than or equal to 85%, the piperylene conversion rate is high, the branched structure is high, and the prepared SPS has excellent mechanical properties.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A styrene-piperylene-styrene block copolymer is characterized in that the content of 1, 2-structure in the styrene-piperylene-styrene block copolymer is 20-50 wt%.

2. The styrene-piperylene-styrene block copolymer of claim 1, wherein the content of trans 1, 4-structure in the styrene-piperylene-styrene block copolymer is 35-60 wt%; and/or

The number average molecular weight of the styrene-piperylene-styrene block copolymer is 2-100 ten thousand; and/or

The molecular weight distribution of the styrene-piperylene-styrene block copolymer is less than 1.3; and/or

In the styrene-piperylene-styrene block copolymer, the content of the styrene structural unit is 20-50 wt%; the content of the piperylene structural unit is 50-80 wt%; and/or

The content of the tetrahydrofuran-based compound in the styrene-piperylene-styrene block copolymer is below 25 ppm.

3. The styrene-piperylene-styrene block copolymer of claim 1 or 2, wherein the styrene-piperylene-styrene block copolymer has a permanent set of 30-70%; and/or

The 300% tensile strength of the styrene-piperylene-styrene block copolymer is 3.5-8 MPa; and/or

The tensile strength of the styrene-piperylene-styrene segmented copolymer is 10-25 MPa; and/or

The breaking elongation of the styrene-piperylene-styrene block copolymer is 600-1200%; and/or

The hardness of the styrene-piperylene-styrene segmented copolymer is 70-100 Shore A.

4. A method of synthesizing a styrene-piperylene-styrene block copolymer, the method comprising: styrene and piperylene are contacted in the presence of an organolithium initiator and a tetrahydrofuranyl compound to carry out a polymerization reaction.

5. The process of claim 4, wherein the organolithium initiator is an alkyllithium initiator and/or a functionalized organolithium initiator;

preferably, the organolithium initiator is an alkyllithium initiator;

more preferably, the alkyllithium initiator is at least one selected from the group consisting of ethyllithium, propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, pentyllithium, hexyllithium, cyclohexyllithium, phenyllithium, methylphenyllithium and naphthyllithium, and further preferably is n-butyllithium and/or sec-butyllithium.

6. The method according to claim 4 or 5, wherein the tetrahydrofuranyl compound has a structure represented by formula (I),

wherein R is₁Is H or C1-C3 alkyl; r₂Is H or C1-C3 alkyl; r₃Is a group containing O or N;

7. Process according to any one of claims 4 to 6, wherein the organolithium initiator is used in an amount of 0.2 to 3mmol, preferably 0.8 to 1.5mmol, relative to the total weight of 100g of styrene and piperylene;

preferably, the molar ratio of the tetrahydrofuran-based compound to the organolithium initiator is 0.01-1: 1.

8. The process according to any one of claims 4 to 7, wherein the polymerization reaction is carried out in the presence of an organic solvent, preferably a hydrocarbon solvent;

more preferably, the hydrocarbon solvent is selected from at least one of alkanes of C5-C12, cycloalkanes of C5-C12, and aromatics of C6-C12;

further preferably, the hydrocarbon solvent is selected from at least one of cyclopentane, methylcyclopentane, cyclohexane, n-hexane, and raffinate oil;

wherein the organic solvent is used in an amount such that the monomer concentration is 5 to 30% by weight, preferably 10 to 25% by weight.

9. The process of any one of claims 4-8, wherein the polymerization conditions comprise: the temperature is 25-150 ℃, preferably 50-120 ℃; the pressure is 0.1-1.5MPa, preferably 0.1-0.3 MPa.

10. The process of any one of claims 4-9, wherein the contacting styrene and piperylene comprises: carrying out first polymerization on a first part of styrene in the presence of an organic lithium initiator and a tetrahydrofuran-based compound, then adding piperylene into the material subjected to the first polymerization for second polymerization, and then adding a second part of styrene into the material subjected to the second polymerization for third polymerization to obtain a styrene-piperylene-styrene triblock copolymer;

preferably, the ratio of the first portion of styrene to the second portion of styrene is 1: 0.5 to 2;

11. The process of any one of claims 4-9, wherein the contacting styrene and piperylene comprises: styrene is subjected to first polymerization in the presence of an organic lithium initiator and a tetrahydrofuran-based compound, piperylene is added into the first polymerized material for second polymerization, and a coupling agent is added into the second polymerized material for coupling to obtain a styrene-piperylene-styrene star-shaped copolymer;

preferably, the piperylene is used in an amount of 50 to 80 wt%, more preferably 60 to 75 wt%, based on the total weight of the monomers; the styrene is used in an amount of 20 to 50 wt%, more preferably 25 to 40 wt%;

preferably, the coupling time is 20-30 min.

12. The method of claim 11, wherein the coupling agent is selected from at least one of a multifunctional lewis acid, divinylbenzene, polyvinyl derivatives, and polyepoxy compounds;

preferably, the coupling agent is selected from at least one of silicon tetrachloride, tin tetrachloride, divinylbenzene and epoxidized soybean oil;

preferably, the molar ratio of the coupling agent to the organolithium initiator is from 0.1 to 0.25: 1.

13. A styrene-piperylene-styrene block copolymer prepared by the process of any one of claims 4 to 12.

14. Use of the styrene-piperylene-styrene block copolymer of any one of claims 1 to 3 and 13 in hot melt adhesives, high hardness elastomers and thermo-memory deformable materials.