Carboxyl-terminated liquid polybutadiene polymer, preparation method and application thereof, composition and application thereof, and polymer coating

Abstract

The invention relates to the field of polymer synthesis, and discloses a carboxyl-terminated liquid polybutadiene polymer, a preparation method and application thereof, a composition and application thereof, and a polymer coating. The functionality degree of the carboxyl-terminated liquid polybutadiene polymer is 1.85 to 2; on the basis of the total weight of the carboxyl-terminated liquid polybutadiene polymer, the content of the 1, 2-structural unit is 60-74.5 wt%, and the content of the 1, 4-structural unit is 25.5-40 wt%; based on the weight of the 1, 2-structural unit in the carboxyl-terminated liquid polybutadiene polymer, the content of the cyclized 1, 2-structural unit is 15-35 wt%. The carboxyl-terminated liquid polybutadiene polymer has a cyclized structure, meets high 1, 2-structural unit content and has high functionality, and a polymer coating formed by the polymer has a lower coefficient of thermal expansion under the condition of maintaining high peel strength and bending strength.

Description

Technical Field

[0001] This invention belongs to the field of polymer synthesis technology, and relates to a carboxyl-terminated liquid polybutadiene polymer, its preparation method and application, as well as compositions and applications and polymer coatings. Background Technology

[0002] Liquid polybutadiene, with its unique chemical structure and excellent physical properties, occupies an important position in many industrial fields. Especially in the field of high-frequency electronic circuits, liquid polybutadiene is highly favored due to its extremely low dielectric constant and dielectric loss. However, with the continuous advancement of technology and the rapid development of high-frequency communication technology, traditional liquid polybutadiene is finding it difficult to meet the demands of modern industry in certain aspects.

[0003] Carboxyl-terminated liquid polybutadiene possesses unique properties due to the carboxyl functional groups at the ends of its molecular chains. These functional groups not only provide the polymer with more reactivity possibilities but also endow it with higher reactivity and superior physical properties. However, due to the low reactivity of the carboxyl-terminated polybutadiene chains, it requires a long curing time and exhibits low strength at high temperatures.

[0004] Therefore, the development of improved performance end-carboxyl liquid polybutadiene is expected to drive the continuous progress and development of high-frequency communication technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the technical problems of long curing time and low strength at high temperatures in existing liquid polybutadiene polymers, and to provide a carboxyl-terminated liquid polybutadiene polymer, its preparation method and applications, as well as compositions, applications, and polymer coatings. The carboxyl-terminated liquid polybutadiene polymer has a cyclic structure and terminal carboxyl groups, and satisfies a high 1,2-structural unit content, while also possessing high functionality. The polymer coating formed after curing this carboxyl-terminated liquid polybutadiene polymer exhibits a lower coefficient of thermal expansion while maintaining high peel strength and flexural strength.

[0006] The first aspect of the present invention provides a carboxyl-terminated liquid polybutadiene polymer, wherein the functionality of the carboxyl-terminated liquid polybutadiene polymer is 1.85-2; based on the total weight of the carboxyl-terminated liquid polybutadiene polymer, the content of 1,2-structural units is 60-74.5% by weight, and the content of 1,4-structural units is 25.5-40% by weight; based on the weight of 1,2-structural units in the carboxyl-terminated liquid polybutadiene polymer, the content of cyclized 1,2-structural units is 15-35% by weight.

[0007] A second aspect of the present invention provides a method for preparing a carboxyl-terminated liquid polybutadiene polymer, characterized in that the method comprises:

[0008] (1) In the presence of a solvent and a structure modifier, 1,3-butadiene monomer is contacted with an initiator to carry out an anionic solution polymerization reaction to obtain a polymerization reaction solution containing polybutadiene polymer; wherein, the structure modifier is an alkali metal alkoxide, the initiator is an organic bislithium initiator, the molar ratio of the structure modifier to the initiator is 0.1-0.8:1, and the solvent contains an alicyclic solvent;

[0009] (2) The polymerization reaction solution obtained in step (1) is subjected to a capping reaction with an epoxy compound capping agent;

[0010] (3) After the end-capping reaction is complete, cyclic carboxylic anhydride is added to react and obtain a carboxyl-terminated liquid polybutadiene polymer.

[0011] The contact described in step (1) is carried out at a temperature of 50-100°C.

[0012] A third aspect of the present invention provides a carboxyl-terminated liquid polybutadiene polymer prepared by the above method.

[0013] A fourth aspect of the present invention provides a composition comprising a carboxyl-terminated liquid polybutadiene polymer and at least one additive, wherein the carboxyl-terminated liquid polybutadiene polymer is the carboxyl-terminated liquid polybutadiene polymer described in the first and third aspects above.

[0014] The fifth aspect of the present invention provides a polymer coating comprising the carboxyl-terminated liquid polybutadiene polymer described in the first and third aspects above, or the composition described in the fourth aspect above.

[0015] The sixth aspect of the present invention provides the use of the carboxyl-terminated liquid polybutadiene polymer described in the first and third aspects above, or the composition described in the fourth aspect above, as a crosslinking agent, adhesive, or electrical insulating material.

[0016] Through the above technical solution, the carboxyl-terminated liquid polybutadiene polymer provided by the present invention has a high content of 1,2-structural units, as well as a cyclized structure and carboxyl-terminated ends, and high functionality, which endows the liquid polybutadiene polymer with excellent photo (or thermal) crosslinking reactivity, thereby increasing the crosslinking density of the polymer coating made from the polymer; and ensures that the liquid polybutadiene polymer has high peel strength and flexural strength after crosslinking and curing under relatively harsh conditions, and maintains better thermal stability; and the preparation process is simple and efficient, which is conducive to actual production. Detailed Implementation

[0017] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0018] In this invention, the term "liquid polybutadiene polymer" refers to a polybutadiene polymer that is fluid at 25°C and 1 standard atmosphere.

[0019] In this invention, the term "1,2-structural unit" refers to the structural unit formed by the 1,2-polymerization of 1,3-butadiene, and the content of 1,2-structural units can also be referred to as the vinyl content.

[0020] In this invention, the term "1,4-structural unit" refers to the structural unit formed by the 1,4-polymerization of 1,3-butadiene.

[0021] In this invention, the term "cyclized 1,2-structural unit" refers to the formation of a five-membered ring from the vinyl bonds in two adjacent 1,2-structural units, as shown in the following structure:

[0022]

[0023] In this invention, the contents of 1,2-structural units, 1,4-structural units, and cyclized 1,2-structural units in the polymer were determined by nuclear magnetic resonance spectroscopy.

[0024] In this invention, the specific testing method of the nuclear magnetic resonance spectroscopy is as follows: a Bruker AVANCE 400 superconducting nuclear magnetic resonance spectrometer is used. 1 H-NMR test, 1 The resonance frequency of the H nucleus was 300.13 MHz, the spectral width was 2747.253 Hz, the pulse width was 5.0 μs, the data point was 16 K, the sample tube diameter was 5 mm, the solvent was deuterated chloroform (CDCl3), the sample concentration was 15% (mg / mL), the test temperature was room temperature (25℃), the number of scans was 16, and the calibration was performed with a tetramethylsilane chemical shift of 0 ppm.

[0025] In this invention, molecular weight and molecular weight distribution index (Mw / Mn) were determined by gel permeation chromatography. The specific test method was as follows: an HLC-8320 gel permeation chromatograph from Tosoh Corporation of Japan was used, with a TSKgel SuperMultipore HZ-N column, a TSKgel SuperMultipore HZ standard column, and chromatographically pure tetrahydrofuran (THF) as the solvent. Narrow distribution polystyrene was used as the standard sample. The polymer sample was prepared into a tetrahydrofuran solution with a concentration of 1 mg / mL. The injection volume was 10.00 μL, the flow rate was 0.35 mL / min, and the test temperature was 40.0 °C.

[0026] In this invention, the linear coefficient of thermal expansion is determined by thermomechanical analysis (TMA) according to the method specified in GB / T 36800.2-2018.

[0027] In this invention, the peel strength between the polymer coating and the metal substrate (copper foil) is tested using the method specified in IPC-TM-650.

[0028] In this invention, the bending strength is determined according to the method specified in IPC-TM-650 2.4.4.

[0029] The first aspect of the present invention provides a carboxyl-terminated liquid polybutadiene polymer, wherein the functionality of the carboxyl-terminated liquid polybutadiene polymer is 1.85-2; based on the total weight of the carboxyl-terminated liquid polybutadiene polymer, the content of 1,2-structural units is 60-74.5% by weight, and the content of 1,4-structural units is 25.5-40% by weight; based on the weight of 1,2-structural units in the carboxyl-terminated liquid polybutadiene polymer, the content of cyclized 1,2-structural units is 15-35% by weight.

[0030] In some embodiments of the present invention, preferably, the functionality of the carboxyl-terminated liquid polybutadiene polymer is 1.85-2, for example, it can be 1.85, 1.86, 1.87, 1.88, 1.89, 1.9, 1.91, 1.92, 1.93, 1.94, 1.95, 1.96, 1.97, 1.98, 1.992, or any value within a range of any two values, preferably 1.88-1.95. The carboxyl-terminated liquid polybutadiene polymer of the present invention has high functionality, which is beneficial for improving the adhesion between the polymer coating formed under the same crosslinking conditions and the metal matrix.

[0031] In some embodiments of the present invention, preferably, the content of 1,2-structural units is 60-74.5% by weight, based on the total weight of the carboxyl-terminated liquid polybutadiene polymer. For example, it can be 60% by weight, 61% by weight, 62% by weight, 63% by weight, 64% by weight, 65% by weight, 66% by weight, 67% by weight, 68% by weight, 69% by weight, 70% by weight, 71% by weight, 72% by weight, 73% by weight, 74% by weight, 74.5% by weight, or any value within a range of any two of these values. More preferably, the content of 1,2-structural units is 65-74.5% by weight, based on the total weight of the carboxyl-terminated liquid polybutadiene polymer.

[0032] In some embodiments of the present invention, preferably, the content of 1,4-structural units is 25.5-40% by weight, based on the total weight of the terminal carboxyl liquid polybutadiene polymer. For example, it can be 25.5% by weight, 26% by weight, 27% by weight, 28% by weight, 29% by weight, 30% by weight, 31% by weight, 32% by weight, 33% by weight, 34% by weight, 35% by weight, 36% by weight, 37% by weight, 38% by weight, 39% by weight, 40% by weight, or any value within a range of any two values. More preferably, the content of 1,4-structural units is 25.5-35% by weight, based on the total weight of the terminal carboxyl liquid polybutadiene polymer. In the present invention, a content of less than 25.5% by weight affects the content of cyclized structural units in the polymer; a content of more than 35% by weight reduces the number of double bonds that can participate in curing crosslinking, resulting in a lower crosslinking density in the polymer coating made from the polymer.

[0033] In some embodiments of the present invention, preferably, the content of cyclized 1,2-structural units is 15-35% by weight, based on the weight of the 1,2-structural units in the terminal carboxyl-terminated liquid polybutadiene polymer. For example, it can be any value within the range of 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, or any combination of two such values. More preferably, the content of cyclized 1,2-structural units is 20-30% by weight, based on the weight of the 1,2-structural units in the terminal carboxyl-terminated liquid polybutadiene polymer. In this invention, the weight of the 1,2-structural units and the cyclized 1,2-structural units is controlled within the above-mentioned range, resulting in better overall performance of the polymer coating after curing. When the content of the cyclized 1,2-structural units is less than 15% by weight, the improvement in the coefficient of thermal expansion of the polymer coating after curing is not significant. When the content of the cyclized 1,2-structural units is greater than 35% by weight, it is not conducive to increasing the total 1,2-structural content of the polymer, and the crosslinking density of the polymer coating made from this polymer is reduced, resulting in poorer mechanical properties.

[0034] In some embodiments of the present invention, preferably, the number average molecular weight of the carboxyl-terminated liquid polybutadiene polymer is 1000-5000 g / mol, more preferably 1300-4500 g / mol, and even more preferably 1500-4000 g / mol.

[0035] In some embodiments of the present invention, preferably, the molecular weight distribution index of the carboxyl-terminated liquid polybutadiene polymer is 1-1.2, more preferably 1-1.15.

[0036] In some embodiments of the present invention, preferably, the linear coefficient of thermal expansion of the carboxyl-terminated liquid polybutadiene polymer after curing is 40 × 10⁻⁶. -6 m / m / ℃-80×10 -6 m / m / ℃, preferably 50×10 -6 m / m / ℃-70×10 -6 m / m / ℃.

[0037] In some embodiments of the present invention, preferably, the peel strength between the coating formed by the carboxyl-terminated liquid polybutadiene polymer and the metal substrate is 0.9-1.1 N / mm.

[0038] In some embodiments of the present invention, preferably, the flexural strength of the carboxyl-terminated liquid polybutadiene polymer is 190-220 MPa.

[0039] This invention discloses a method for preparing carboxyl-terminated liquid polybutadiene polymer, characterized in that the method comprises:

[0040] (1) In the presence of a solvent and a structure modifier, 1,3-butadiene monomer is contacted with an initiator to carry out an anionic solution polymerization reaction to obtain a polymerization reaction solution containing polybutadiene polymer; wherein, the structure modifier is an alkali metal alkoxide, the initiator is an organic bislithium initiator, the molar ratio of the structure modifier to the initiator is 0.1-0.8:1, and the solvent contains an alicyclic solvent;

[0041] (2) The polymerization reaction solution obtained in step (1) is subjected to a capping reaction with an epoxy compound capping agent;

[0042] (3) After the end-capping reaction is complete, cyclic carboxylic anhydride is added to react and obtain a carboxyl-terminated liquid polybutadiene polymer.

[0043] The contact described in step (1) is carried out at a temperature of 50-100°C.

[0044] In this invention, the content of 1,4-structural units, 1,2-structural units, and cyclized 1,2-structural units in the terminal carboxyl liquid polybutadiene polymer is determined by step (1). The end-capping reaction and subsequent reactions do not affect the content of 1,4-structural units, 1,2-structural units, and cyclized 1,2-structural units in the liquid butene polymer.

[0045] In some embodiments of the present invention, preferably, the initiator is an organolithium initiator. The type of bislithium initiator is not particularly limited and can be any existing compound containing two lithium atoms capable of bidirectionally initiating anionic polymerization reactions. For example, the organolithium initiator can be selected from at least one of alkane-based bislithium, naphthalene-based bislithium, and diene-based bislithium. Specifically, the general formula of the alkane-based bislithium is LiRLi, where R is C4-C. 10 Alkyl groups, specific examples of which include, but are not limited to, at least one of Li(CH2)4Li, Li(CH2)6Li, and Li(CH2)8Li; the naphthalene-based bislithium is naphthalene lithium and / or α-methylnaphthalene lithium; the diene-based bislithium is selected from at least one of butadiene-based bislithium, 1,1'-(1,3-phenylene)-bis[3-methyl-1-(4-tolyl)pentyl]bislithium and 1,1'-(1,4-phenylene)-bis[3-methyl-1-(4-tolyl)pentyl]bislithium.

[0046] In this invention, the amount of initiator can be selected based on the expected molecular weight of the carboxyl-terminated liquid polybutadiene polymer. Preferably, the amount of initiator is such that the number-average molecular weight of the prepared carboxyl-terminated liquid polybutadiene polymer is 1000-5000 g / mol, more preferably 1300-4500 g / mol, and even more preferably 1500-4000 g / mol. The method for determining the specific amount of initiator based on the expected polymer molecular weight is well known to those skilled in the art and will not be described in detail herein.

[0047] In some embodiments of the present invention, preferably, the structure modifier is selected from one or more compounds represented by Formula I.

[0048] R1-O-M1 (Formula I)

[0049] In Formula I, R1 is a heteroatom-substituted or unsubstituted C1-C 20 Alkyl groups, or C4-C 20 cycloalkyl groups;

[0050] M1 is an alkali metal atom; for example, it can be Li, Na or K, preferably Na.

[0051] In Formula I, the unsubstituted C1-C 20 Alkyl groups include C1-C 20 Straight-chain alkyl and C3-C 20 Branched alkyl groups, specific examples of which may include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl and its isomers, n-hexyl and its isomers, n-heptyl and its isomers, n-octyl and its isomers, n-nonyl and its isomers, n-decyl and its isomers, undecyl and its isomers, dodecyl and its isomers, tridecyl and its isomers, tetradecyl and its isomers, pentadecyl and its isomers, hexadecyl and its isomers, heptadecanyl and its isomers, octadecyl and its isomers, nonadecanyl and its isomers, and eicosyl and its isomers.

[0052] In Formula I, the heteroatom-substituted C1-C 20 In the alkyl group, heteroatoms exist on the alkyl carbon chain in the form of substituents, wherein the substituents are preferably cycloalkyl groups containing heteroatoms, and specific examples of heteroatoms may include, but are not limited to, oxygen atoms, sulfur atoms, or nitrogen atoms. In a preferred embodiment, the heteroatom substituted is an oxygen atom, and the substituent substituted is an oxygen-containing cycloalkyl group, such as: ethylene oxide substituent, propylene oxide substituent, tetrahydrofuran substituent, or pentane oxide substituent.

[0053] In Equation I, C4-C 20The cycloalkyl groups include cyclobutyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 4-ethylcyclohexyl, 4-n-propylcyclohexyl, 4-n-butylcyclohexyl, or 2-isopropyl-5-methylcyclohexyl.

[0054] In some embodiments of the present invention, preferably, the structure modifier is selected from at least one of sodium tetrahydrofurfuryl alcohol, sodium tert-pentoxyl, sodium tert-butoxyl, sodium ethoxyl, sodium n-hexanolate, and sodium menthol.

[0055] In this invention, the amount of the structure modifier can be adjusted according to the amount of monomer and / or polymerization initiator. In some embodiments of this invention, preferably, the molar ratio of the structure modifier to the initiator is 0.1-0.8:1, for example, it can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, and any value within any range of any two values, more preferably 0.2-0.6:1.

[0056] In some embodiments of the present invention, preferably, the solvent contains an alicyclic solvent. The term "alicyclic" refers to a cycloalkanes in which at least one carbon atom in the ring is replaced by a heteroatom. The heteroatom in the alicyclic ring can be an oxygen atom, a nitrogen atom, or a sulfur atom, preferably an oxygen atom.

[0057] In this invention, the solvent can be used alone or in combination. The type of solvent has a wide range of choices. Preferably, the solvent is an oxacycloalkane. The oxacycloalkane of this invention can be selected from at least one of tetrahydrofuran, cyclopentane oxide, cyclohexane oxide, and 1,4-dioxane. Preferably, the solvent is tetrahydrofuran.

[0058] In this invention, the amount of 1,3-butadiene monomer used has a wide range of selection. Preferably, based on the total weight of solvent and 1,3-butadiene monomer, the content of 1,3-butadiene monomer is 1-10% by weight, more preferably 1.5-10% by weight, and even more preferably 2-8% by weight. In this invention, monomer content refers to the total weight percentage of 1,3-butadiene monomer determined based on the total weight of solvent and 1,3-butadiene monomer after the polymerization reaction.

[0059] In some embodiments of the present invention, preferably, the 1,3-butadiene monomer is contacted with an initiator in the presence of a solvent and a structure modifier to carry out an anionic solution polymerization reaction. Preferably, the 1,3-butadiene is contacted with the structure modifier and the initiator at a temperature of 50°C to 100°C to carry out the anionic polymerization reaction. More preferably, the 1,3-butadiene is contacted with the structure modifier and the initiator at a temperature of 60°C to 90°C. Even more preferably, the 1,3-butadiene is contacted with the structure modifier and the initiator at a temperature of 65°C to 85°C.

[0060] In this invention, the pressure of the anionic solution polymerization reaction is not particularly limited. For example, the anionic polymerization reaction can be carried out at a pressure of 0.005-1.5 MPa, preferably at 0.1-1 MPa, and more preferably at 0.2-0.6 MPa. In this invention, all pressures refer to gauge pressure. The polymerization reaction time can be selected according to the final monomer concentration and polymerization temperature, generally 10-120 minutes after monomer feeding, preferably 30-80 minutes.

[0061] In this invention, the anionic solution polymerization reaction is carried out in an atmosphere formed by an inert gas. The inert gas refers to a gas that does not chemically interact with the reactants, reaction products, and solvent under polymerization conditions, such as nitrogen and / or group zero element gases (e.g., argon).

[0062] In this invention, preferably, after the anionic polymerization reaction is completed, an epoxy compound end-capping agent is added to carry out the end-capping reaction.

[0063] In this invention, the type of epoxy compound is not particularly limited. Preferably, the epoxy compound is at least one selected from ethylene oxide, propylene oxide, and butane oxide, and more preferably ethylene oxide and / or propylene oxide.

[0064] In this invention, the amount of epoxy compound used is not particularly limited, as long as it is sufficient to completely end the polymer. However, excessive epoxy compound may interfere with subsequent reactions. Preferably, the molar ratio of the epoxy compound to the initiator is 2-3:1.

[0065] In this invention, the conditions for the end-capping reaction are not particularly limited. Preferably, the temperature of the end-capping reaction is 10-80°C, more preferably 30-70°C; and the time of the end-capping reaction is 5-90 min, more preferably 20-60 min.

[0066] In this invention, preferably, after the end-capping reaction is complete, a cyclic carboxylic anhydride is added to react and obtain a carboxyl-terminated liquid polybutadiene polymer. Specifically, in this invention, an epoxy compound is added to the obtained polymerization reaction solution containing the polybutadiene polymer to perform an end-capping reaction. The epoxy compound reacts with the terminal anionic active centers on the polybutadiene polymer chain, converting polybutadiene-based lithium into less active polybutadiene-based lithium oxide. After the end-capping reaction is completed, a cyclic carboxylic anhydride is added to the system to react. The polybutadiene-based lithium oxide attacks the carbon-oxygen bonds of the cyclic carboxylic anhydride, causing a ring-opening reaction and forming carboxyl groups at the ends of the polymer chains, thus obtaining a liquid polybutadiene polymer with carboxyl-terminated groups.

[0067] In this invention, the type of cyclic carboxylic anhydride is not particularly limited, and various cyclic carboxylic anhydrides conventionally used in the art can be used in this invention. Preferably, the cyclic carboxylic anhydride is selected from aliphatic monohydric anhydrides and / or aromatic monohydric anhydrides, more preferably from at least one of maleic anhydride, succinic anhydride, phthalic anhydride and malonic anhydride, and even more preferably from maleic anhydride and / or phthalic anhydride.

[0068] In this invention, the amount of the cyclic carboxylic anhydride has a wide range of selection. Preferably, the molar ratio of the cyclic carboxylic anhydride to the initiator is 3-5:1, for example, it can be 3:1, 3.5:1, 4:1, 4.5:1, 5:1, or any value within the range of any two values, preferably 3.5-4.5:1.

[0069] In this invention, the conditions for the reaction of adding cyclic carboxylic anhydrides are not particularly limited. Preferably, the reaction temperature for adding cyclic carboxylic anhydrides is 10-80°C, more preferably 30-70°C; the reaction time is 5-90 min, more preferably 20-60 min.

[0070] In this invention, preferably, the method further includes: adding a terminator after reacting with a cyclic carboxylic anhydride solution, followed by washing, precipitation, and drying to obtain the terminal carboxyl liquid polybutadiene polymer.

[0071] In this invention, there are no particular limitations on the type and amount of the terminating agent. Conventional terminating agents in the art can be used and added in the conventional amounts in the art.

[0072] In this invention, the washing and precipitation method includes: contacting the mixed solution obtained after termination with a detergent for washing; after the washed mixed solution is separated by precipitation and stratification, separating the oil phase from the mixed solution, removing at least some volatile components, and obtaining the terminal carboxyl liquid polybutadiene polymer.

[0073] In this invention, the washing method and conditions can be those known to those skilled in the art, as long as they can further remove at least some of the metal ions from the polymer reaction solution. Preferably, the washing solution is water or an aqueous solution containing acid.

[0074] In this invention, the precipitation method and conditions can be any precipitation method and conditions known to those skilled in the art, as long as they can cause the washed mixed solution to separate into layers and separate the oil phase.

[0075] In this invention, the drying method and conditions can be those known to those skilled in the art, and will not be described in detail here.

[0076] In this invention, the various reagents used in the preparation method are preferably purified using conventional methods in the art before use to remove impurities (especially moisture). Methods for purifying reagents are well known in the art and will not be described further herein.

[0077] In this invention, the anionic solution polymerization reaction can be carried out by either batch polymerization or continuous polymerization, without any particular limitation.

[0078] A third aspect of the present invention provides a carboxyl-terminated liquid polybutadiene polymer prepared by the above method.

[0079] The carboxyl-terminated liquid polybutadiene polymer prepared by the method described in the second aspect of this invention not only has a high content of 1,2-structural units, but also some of these 1,2-structural units form a cyclic structure, giving the polymer coating formed by the liquid polybutadiene polymer excellent crosslinking density and maintaining good stability even under relatively harsh conditions. Furthermore, the carboxyl-terminated liquid polybutadiene polymer contains carboxyl groups at both ends, enhancing the interaction between the polymer and the metal surface, and improving the adhesion and peel strength between the polymer coating and the metal substrate. The polymer coating formed using the carboxyl-terminated liquid polybutadiene polymer prepared by the method described in this invention exhibits superior thermal expansion properties while maintaining high peel strength and flexural strength.

[0080] A fourth aspect of the present invention provides a composition comprising a carboxyl-terminated liquid polybutadiene polymer and at least one additive, wherein the carboxyl-terminated liquid polybutadiene polymer is the carboxyl-terminated liquid polybutadiene polymer described in the first and third aspects above.

[0081] In this invention, the additive can be a substance that imparts new properties to the composition and / or improves the existing properties of the composition. As a preferred example, the additive contains an antioxidant. The antioxidant can be of conventional selection, for example, the antioxidant can be a phenolic and / or amine antioxidant. Specifically, the antioxidant can be one or more of 4,6-dioctylthiomethyl o-cresol, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (i.e., antioxidant 264), tris(2,4-di-tert-butylphenyl) phosphite (i.e., antioxidant 168), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (i.e., antioxidant 1076), 2,6-di-tert-butyl-p-cresol, tert-butylcatechol, and 2,2'-methylenebis(4-methyl-6-tert-butylphenol). The antioxidant content can be 0.005-2 parts by weight, preferably 0.01-1 parts by weight, relative to 100 parts by weight of liquid polybutadiene polymer.

[0082] The fifth aspect of the present invention provides a polymer coating comprising the carboxyl-terminated liquid polybutadiene polymer described in the first and third aspects above, or the composition described in the fourth aspect above.

[0083] In this invention, the polymer coating not only has high adhesion and bonding to the metal substrate, but also has high flexural strength and a low coefficient of thermal expansion, showing improved thermal expansion performance.

[0084] The sixth aspect of the present invention provides the use of the carboxyl-terminated liquid polybutadiene polymer described in the first and third aspects above, or the composition described in the fourth aspect above, as a crosslinking agent, adhesive, or electrical insulating material.

[0085] The present invention will be described in detail below through embodiments.

[0086] Unless otherwise specified, room temperature and room temperature are both expressed as 25±3℃.

[0087] In the following examples and comparative examples, the microstructure of the polymer was determined using a Bruker AVANCE 400 superconducting nuclear magnetic resonance spectrometer. 1 H-NMR) determination, 1 The resonance frequency of the H nucleus was 300.13 MHz, the spectral width was 2747.253 Hz, the pulse width was 5.0 μs, the data point was 16 K, the sample tube diameter was 5 mm, the solvent was deuterated chloroform (CDCl3), the sample concentration was 15% (W / V), the test temperature was room temperature, the number of scans was 16, and the calibration was performed with a tetramethylsilane chemical shift of 0 ppm.

[0088] In the following examples and comparative examples, the molecular weight and molecular weight distribution index of the polymers were determined by gel permeation chromatography. The gel permeation chromatography was performed using an HLC-8320 gel permeation chromatograph from Tosoh Corporation, Japan. The chromatographic column was TSKgel SuperMultipore HZ-N, the standard column was TSKgel SuperMultipore HZ, and the solvent was chromatographically pure tetrahydrofuran (THF). Narrow distribution polystyrene was used as the standard sample. The polymer sample was prepared into a tetrahydrofuran solution with a mass concentration of 1 mg / mL. The injection volume was 10.00 μL, the flow rate was 0.35 mL / min, and the test temperature was 40.0 °C.

[0089] In the following examples and comparative examples, the carboxyl value of the polymer was tested according to the method specified in GBJ5178-2003, and the functionality was calculated as: carboxyl value (mmol / g) * Mn (g / mol) / 1000.

[0090] In the following examples and comparative examples, the linear thermal expansion coefficient was determined by thermomechanical analysis (TMA) according to the method specified in GB / T 36800.2-2018.

[0091] In the following examples and comparative examples, the peel strength between the polymer coating and the copper foil was tested using the method specified in IPC-TM-650 2.4.08C.

[0092] In the following examples and comparative examples, the bending strength was tested using the method specified in IPC-TM-650 2.4.4.

[0093] The following examples and comparative examples involve the following chemical reagents:

[0094] Antioxidant 264, Antioxidant 168 and Antioxidant 1076 were purchased from Sinopharm Reagent Company;

[0095] Butadiene-based bislithium initiator: self-made, chemical formula C4H6Li2;

[0096] 1,3-Butadiene: Polymer grade, purchased from Yanshan Petrochemical;

[0097] Sodium tert-pentoxygenate (STA): purchased from Bailingwei Reagent Company, 1.4 mol / L tetrahydrofuran solution;

[0098] Sodium tetrahydrofurfuryl alcohol (THFOA): purchased from Inokai Reagent Company, 1.0 mol / L tetrahydrofuran solution;

[0099] Sodium menthol (SMT): purchased from Inokai Reagents, 1.0 mol / L tetrahydrofuran solution;

[0100] Ethylene oxide (EO): Purchased from Inokai Reagents, 98% purity. After distillation in the presence of calcium hydride, it was prepared into a 20 wt% tetrahydrofuran solution for use.

[0101] Propylene oxide: purchased from Inokai Reagents, 99% purity, distilled in the presence of calcium hydride, and then prepared as a 20 wt% tetrahydrofuran solution for use.

[0102] Maleic anhydride, purchased from Inokai Reagent Company, with a purity of 99%, was purified by sublimation recrystallization and prepared into a 20 wt% tetrahydrofuran solution for use.

[0103] Phthalic anhydride, purchased from Inokai Reagent Company, with a purity of 99%, was purified by sublimation recrystallization and prepared into a 20 wt% tetrahydrofuran solution for use.

[0104] Preparation Example

[0105] The preparation process of the butadiene-based bislithium initiator is as follows:

[0106] (1) Vacuuming, high-temperature baking and nitrogen replacement of 250mL reaction bottle 1 and absorption bottle were repeated 5 times to remove impurities such as water and oxygen in the system. Then cyclohexane and butadiene were added to the absorption bottle to obtain a butadiene cyclohexane solution with a concentration of 2.8mol / L.

[0107] (2) Vacuuming, high-temperature baking, and nitrogen replacement of 250mL reaction flask 2 were repeated 5 times to remove impurities such as water and oxygen in the system. Under nitrogen protection, lithium was cut into small pieces. Naphthalene, lithium and THF were added to reaction flask 2 in sequence. The molar ratio of naphthalene, lithium and THF was 1:1.2:5. The reaction was carried out at 25℃ for 2 hours under electromagnetic stirring to obtain naphthalene-lithium solution. The solution was then placed in a freezer for refrigeration.

[0108] (3) Add 36 mL of the naphthalene lithium solution described in step (2) to reaction flask 1, and add 95 mL of the butadiene cyclohexane solution described in step (1) to reaction flask 1. React at 35 °C for 1 h under electromagnetic stirring to obtain butadiene-based bislithium initiator (C4H6Li2).

[0109] Example 1

[0110] This embodiment is used to illustrate the carboxyl-terminated liquid polybutadiene polymer and its preparation method of the present invention.

[0111] (1) Under nitrogen protection, tetrahydrofuran (THF), structure modifier, and 1,3-butadiene (the types and amounts are shown in Table 1, and the amounts listed in Table 1 are all measured as pure compounds) are added to a 5L reactor. The temperature inside the reactor is controlled to the polymerization reaction temperature listed in Table 1. The designed amount of butadiene-based bislithium initiator described in the preparation example is added to the reactor (the specific amount is shown in Table 1, and the amounts listed in Table 1 are all measured as pure compounds). Anionic solution polymerization reaction is carried out at the temperature and pressure listed in Table 1 to obtain a polymerization reaction mixture of liquid polybutadiene polymer.

[0112] (2) Controlling the polymerization reaction temperature (as shown in Table 1), an epoxy compound solution (the specific amount is shown in Table 1, and the amounts listed in Table 1 are all measured by pure compounds) is added to the polymerization reaction mixture of the liquid polybutadiene polymer obtained in step (1). The end-capping reaction is carried out at the end-capping temperature and end-capping time listed in Table 1. Then, a tetrahydrofuran solution of cyclic carboxylic anhydride is added (the specific amount is shown in Table 1, and the amounts listed in Table 1 are all measured by pure compounds). The reaction is carried out at the temperature listed in Table 1. Then, an ethanol solution is added to terminate the reaction. After washing with water and precipitation, the oil phase is subjected to vacuum distillation. An antioxidant (the specific amount is shown in Table 1, and the amounts listed in Table 1 are all measured by pure compounds) is added to the distillation residue to obtain a liquid polybutadiene polymer PB1 containing carboxyl-terminated groups. The structural property parameters of the liquid polybutadiene polymer containing carboxyl-terminated groups are listed in Table 2.

[0113] Example 2-10

[0114] Examples 2-10 illustrate the carboxyl-terminated liquid polybutadiene polymer and its preparation method of the present invention.

[0115] Examples 2-10 were prepared using the same method as in Example 1 to prepare carboxyl-terminated liquid polybutadiene polymers. The difference was that steps (1) and (2) were carried out under the conditions shown in Table 1 to obtain carboxyl-terminated liquid polybutadiene polymers PB2-PB10, respectively. The structural property parameters of the carboxyl-terminated liquid polybutadiene polymers are listed in Table 2.

[0116] Comparative Example 1

[0117] Carboxyl-terminated liquid polybutadiene polymers were prepared using the same method as in Example 1, except that the polymerization temperature in step (1) was 20°C, resulting in carboxyl-terminated liquid polybutadiene polymer DPB1. The structural properties of the carboxyl-terminated liquid polybutadiene polymers are listed in Table 2.

[0118] Comparative Example 2

[0119] Carboxyl-terminated liquid polybutadiene polymers were prepared using the same method as in Example 1, except that no structure modifier was added in step (1) to obtain carboxyl-terminated liquid polybutadiene polymer DPB2. The structural property parameters of the carboxyl-terminated liquid polybutadiene polymers are listed in Table 2.

[0120] Comparative Example 3

[0121] The carboxyl-terminated liquid polybutadiene polymer was prepared using the same method as in Example 1, except that in step (1), the STA structure modifier was replaced by an equal amount of sodium dodecylbenzenesulfonate to obtain the carboxyl-terminated liquid polybutadiene polymer DPB3. The structural property parameters of the carboxyl-terminated liquid polybutadiene polymer are listed in Table 2.

[0122] Comparative Example 4

[0123] The carboxyl-terminated liquid polybutadiene polymer was prepared using the same method as in Example 1. The difference was that in step (1), cyclohexane was used in an equal amount to replace tetrahydrofuran to obtain the carboxyl-terminated liquid polybutadiene polymer DPB4. The structural property parameters of the carboxyl-terminated liquid polybutadiene polymer are listed in Table 2.

[0124] Comparative Example 5

[0125] Carboxyl-terminated liquid polybutadiene polymers were prepared using the same method as in Example 1. The difference was that in step (1), the dilithium initiator was replaced with an equal amount of n-butyllithium to obtain carboxyl-terminated liquid polybutadiene polymer DPB5. The structural property parameters of the carboxyl-terminated liquid polybutadiene polymers are listed in Table 2.

[0126] Comparative Example 6

[0127] Liquid butadiene polymer was prepared using the same method as in Example 1, except that ethylene oxide and maleic anhydride were not added, resulting in liquid butadiene polymer DPB6. The structural properties of the liquid butadiene polymer are listed in Table 3.

[0128] Table 1

[0129]

[0130]

[0131] Table 1 (continued)

[0132]

[0133]

[0134] Table 2

[0135]

[0136] Note: PB represents polybutadiene block, Mn represents the number average molecular weight of the liquid polybutadiene polymer, Mw / Mn represents the molecular weight distribution of the liquid polybutadiene polymer, 1,2-PB represents the 1,2-structure content in the liquid polybutadiene polymer, C-1,2-PB represents the cyclized 1,2-structure content in the liquid polybutadiene polymer based on the weight of 1,2-PB, and 1,4-PB represents the 1,4-structure content in the liquid polybutadiene polymer.

[0137] As can be seen from Table 2, the end-carboxyl liquid polybutadiene polymer provided by the present invention has a 1,2-structural unit content between 60-74.5% by weight. Based on the weight of the 1,2-structure in the end-carboxyl liquid polybutadiene polymer, the cyclized 1,2-structural unit content is between 15-35% by weight. It has a high 1,2-structural unit content, high functionality, and narrow molecular weight distribution, making it an ideal adhesive for the field of high-frequency communication.

[0138] Test case

[0139] Compositions PB1 to PB10 (containing 100 parts of carboxyl-terminated liquid polybutadiene polymer and 1 part of dicumyl peroxide) prepared in Examples 1-10 were uniformly coated onto the surface of copper foil with a coating thickness of 0.8 mm. The coatings were crosslinked and cured at 150 °C for 1 hour. The peel strength and flexural strength were determined using the methods specified in IPC-TM-650 2.4.08C and IPC-TM-650 2.4.4. The linear coefficient of thermal expansion was determined using thermomechanical analysis (TMA) according to the method specified in GB / T36800.2-2018. The experimental results are listed in Table 3.

[0140] Test comparison

[0141] The peel strength, coefficient of thermal expansion and flexural strength of compositions DPB1 to DPB6 prepared in Comparative Examples 1-6 were measured using the same method as in the test examples. The experimental results are listed in Table 3.

[0142] Table 3

[0143]

[0144]

[0145] As can be seen from the results in Table 3, the polymer coating formed by the carboxyl-terminated liquid polybutadiene polymer of the present invention can exhibit a lower coefficient of thermal expansion while maintaining high peel strength and flexural strength.

[0146] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A carboxyl-terminated liquid polybutadiene polymer, characterized in that, The functionality of the terminal carboxyl liquid polybutadiene polymer is 1.85-2; based on the total weight of the terminal carboxyl liquid polybutadiene polymer, the content of 1,2-structural units is 60-74.5% by weight, and the content of 1,4-structural units is 25.5-40% by weight; based on the weight of 1,2-structural units in the terminal carboxyl liquid polybutadiene polymer, the content of cyclized 1,2-structural units is 15-35% by weight.

2. The carboxyl-terminated liquid polybutadiene polymer according to claim 1, wherein, The functionality of the carboxyl-terminated liquid polybutadiene polymer is 1.88-1.95; Preferably, based on the total weight of the terminal carboxyl liquid polybutadiene polymer, the content of 1,2-structural units is 65-74.5% by weight, and the content of 1,4-structural units is 25.5-35% by weight. Preferably, the content of cyclized 1,2-structural units is 20-30% by weight, based on the weight of 1,2-structural units in the terminal carboxyl-terminated liquid polybutadiene polymer.

3. The carboxyl-terminated liquid polybutadiene polymer according to claim 1 or 2, wherein, The number-average molecular weight of the terminal carboxyl liquid polybutadiene polymer is 1000-5000 g / mol, preferably 1300-4500 g / mol, and more preferably 1500-4000 g / mol; the molecular weight distribution index of the terminal carboxyl liquid polybutadiene polymer is 1-1.2, preferably 1-1.

15.

4. The carboxyl-terminated liquid polybutadiene polymer according to any one of claims 1-3, wherein, The linear thermal expansion coefficient of the carboxyl-terminated liquid polybutadiene polymer after curing is 40 × 10⁻⁶. -6 m / m / ℃-80×10 -6 m / m / ℃, preferably 50×10 -6 m / m / ℃-70×10 -6 m / m / ℃; Preferably, the peel strength between the coating formed by the carboxyl-terminated liquid polybutadiene polymer and the metal substrate is 0.9-1.1 N / mm; Preferably, the flexural strength of the carboxyl-terminated liquid polybutadiene polymer after curing is 190-220 MPa.

5. A method for preparing carboxyl-terminated liquid polybutadiene polymer, characterized in that, The method includes: (1) In the presence of a solvent and a structure modifier, 1,3-butadiene monomer is contacted with an initiator to carry out an anionic solution polymerization reaction to obtain a polymerization reaction solution containing polybutadiene polymer; wherein, the structure modifier is an alkali metal alkoxide, the initiator is an organic bislithium initiator, the molar ratio of the structure modifier to the initiator is 0.1-0.8:1, and the solvent contains an alicyclic solvent; (2) The polymerization reaction solution obtained in step (1) is subjected to a capping reaction with an epoxy compound capping agent; (3) After the end-capping reaction is complete, cyclic carboxylic anhydride is added to react and obtain a carboxyl-terminated liquid polybutadiene polymer. The contact described in step (1) is carried out at a temperature of 50-100°C.

6. The method according to claim 5, wherein, The structure modifier is selected from one or more compounds shown in Formula I. R1-O-M1 (Formula I) In Formula I, R1 is a heteroatom-substituted or unsubstituted C1-C 20 Alkyl groups, or C4-C 20 cycloalkyl, M1 is an alkali metal atom; Preferably, the structure modifier is selected from at least one of sodium tetrahydrofurfuryl alcohol, sodium tert-pentoxyl, sodium tert-butoxyl, sodium n-hexanolate, sodium ethoxyl, and sodium menthol.

7. The method according to claim 5 or 6, wherein, The molar ratio of the structure modifier to the initiator is 0.2-0.6:1; Preferably, the contact in step (1) is carried out at a temperature of 60°C to 90°C.

8. The method according to any one of claims 5-7, wherein, The epoxy compound is at least one selected from ethylene oxide, propylene oxide and butane oxide; Preferably, the molar ratio of the epoxy compound to the initiator is 2-3:1; Preferably, the temperature of the end-capping reaction is 10-80℃, more preferably 30-70℃; and the time of the end-capping reaction is 5-90 min, more preferably 20-60 min.

9. The method according to any one of claims 5-8, wherein, The molar ratio of the cyclic carboxylic anhydride to the initiator is 3-5:1, preferably 3.5-4.5:1; Preferably, the cyclic carboxylic anhydride is selected from aliphatic monohydric anhydrides and / or aromatic monohydric anhydrides, more preferably from at least one of maleic anhydride, succinic anhydride, phthalic anhydride and malonic anhydride, and more preferably from maleic anhydride and / or phthalic anhydride. Preferably, the reaction temperature for adding cyclic carboxylic anhydride is 10-80℃, more preferably 30-70℃; the reaction time is 5-90 min, more preferably 20-60 min.

10. The method according to any one of claims 5-9, wherein, The solvent is an oxacycloalkane, preferably tetrahydrofuran.

11. A carboxyl-terminated liquid polybutadiene polymer prepared by the method according to any one of claims 5-10.

12. A composition comprising a carboxyl-terminated liquid polybutadiene polymer and at least one additive, wherein the carboxyl-terminated liquid polybutadiene polymer is the carboxyl-terminated liquid polybutadiene polymer according to any one of claims 1-4 and 11.

13. The composition according to claim 12, wherein, The additive contains antioxidants.

14. A polymer coating comprising any one of claims 1-4 and 11. I92000BHY The carboxyl-terminated liquid polybutadiene polymer described in the above claim, or the composition described in claim 12 or 13.

15. Use of the carboxyl-terminated liquid polybutadiene polymer of any one of claims 1-4 and 11, or the composition of claim 12 or 13, as a crosslinking agent, adhesive, or electrical insulating material.

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