A terminal-functionalized liquid rubber, its preparation method and products

Abstract

This application discloses an end-functionalized liquid rubber, its preparation method, and the product thereof. The end-functionalized liquid rubber has active functional groups at its end groups and an ortho-dihydroxy functional group and / or an epoxy group in its main chain. It is prepared by degrading the polydiolefin rubber using a homogeneous catalyst, a co-catalyst, an oxidant, and an organic solvent.

Description

Technical Field

[0001] This application belongs to the field of green chemical technology, and more specifically, relates to a method for preparing and applying an end-functionalized liquid rubber. Background Technology

[0002] Currently, common methods for preparing end-functionalized liquid rubbers include free radical emulsion polymerization, free radical solution polymerization, anionic polymerization, end-group conversion, and degradation methods. Besides directly introducing functional groups at the chain ends through polymerization, the "degradation method" for chemical modification of existing polymer rubbers has also become an important technical route. This method typically utilizes specific chemical reactions to selectively cleave the molecular chains of high-molecular-weight rubbers (such as polybutadiene) and introduce target functional groups at the fracture ends, thereby achieving the transformation from solid or high-viscosity rubber to low-molecular-weight, flowable functionalized liquid rubber.

[0003] Chinese patent CN104211838A discloses a typical degradation-based preparation process. This process first epoxidizes the carbon-carbon double bonds in polydiene rubber to generate epoxy groups, then breaks the epoxy structure under the action of an oxidant, ultimately yielding a liquid rubber with functional groups at both ends. However, this method has significant shortcomings in practical applications: firstly, the reaction efficiency of the epoxy groups during the cleavage process is inconsistent, leading to a wider molecular weight distribution of the degradation products and affecting the uniformity of material properties; secondly, the reaction process is divided into two steps—epoxidation and oxidative cleavage—making the process complex and requiring high-level equipment and control, thus limiting its feasibility and economic viability in industrial-scale production. Summary of the Invention

[0004] This application provides a method for preparing end-functionalized liquid rubber, which can be applied to the preparation of adhesives and 3D printing materials. This method is inexpensive, easy to operate, and the functional groups and molecular weight of the resulting functionalized liquid rubber are controllable.

[0005] On the one hand, this application provides an end-functionalized liquid rubber, wherein the end-functionalized liquid rubber has active functional groups at its end groups and the main chain contains ortho-dihydroxy functional groups or epoxy groups, or ortho-dihydroxy functional groups and epoxy groups.

[0006] In some embodiments, the end-functionalized liquid rubber has an aldehyde group as its end group.

[0007] In some embodiments, the end-functionalized liquid rubber has a carboxyl group as its end group.

[0008] In some embodiments, the end-functionalized liquid rubber has carboxyl and aldehyde groups as its end groups.

[0009] In some embodiments, the number-average molecular weight of the terminal-functionalized liquid rubber is 500 to 150,000, or 1,000 to 100,000.

[0010] In some instances, the end-functionalized liquid rubber is in a liquid state.

[0011] On the other hand, this application provides a method for preparing end-functionalized liquid rubber, the method comprising the following steps: mixing polydiene rubber, an oxidant, a catalyst, a co-catalyst, and an organic solvent in a reaction apparatus to carry out a functionalization reaction, thereby obtaining the target product—end-functionalized liquid rubber. The catalyst is a homogeneous catalyst, selected from one or more of azo compounds, peroxides, oxynitride radicals, hydroxyl compounds, halogen radicals, alkoxy radicals, and their derivatives; the co-catalyst is one or more of compounds containing metal elements and compounds containing non-metal elements.

[0012] In some embodiments, the azo compounds refer to compounds with the general formula RN=N-R' (where R and R' are the same or different hydrocarbon groups). Specific examples include, but are not limited to, azobisisobutyronitrile (AIBN), azomethane, azobenzene, p-hydroxyazobenzene, diethyl azodicarbonate, etc.

[0013] In some embodiments, the peroxides include, but are not limited to: hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxy esters, peroxy acids (e.g., m-chloroperoxybenzoic acid), peroxy carbonates, and ketone peroxides.

[0014] In some embodiments, the nitroxide radicals include, but are not limited to, stable radicals of the following structural types: piperidine, pyrrolidine, oxazolidine, and imidazolide nitroxide radicals. A typical example is 2,2,6,6-tetramethylpiperidine oxide (TEMPO).

[0015] In some embodiments, the nitrogen-hydroxy compound refers to a class of compounds containing a nitrogen-hydroxyl group structure (the nitrogen atom and the hydroxyl group are covalently linked), and more specifically, includes, but is not limited to, N-hydroxyphthalimide (NHPI), N-hydroxysuccinimide (NHS), etc. In some implementations, halogen radicals include, but are not limited to, chlorine radicals, bromine radicals, and iodine radicals; In some implementations, an alkoxy radical (RO·) refers to an intermediate formed during the oxidation of hydrocarbons, consisting of a free radical compound with an oxygen atom attached to a hydrocarbon group.

[0016] In some embodiments, the metal-containing compounds include metal salts and metal oxides; the non-metal-containing compounds include, but are not limited to, organic compounds. More specifically, compounds containing metallic elements include metal salts and metal oxides. Metal salts include, but are not limited to, iron salts (FeCl3, FeCl2, FeCl3·6H2O, FeBr3, FeBr2, FeBr3·6H2O, Fe(NO3)2, Fe(NO3)3, Fe(NO3)3·9H2O, etc.); copper salts (CuCl2, CuCl, CuCl2·2H2O, etc.); manganese salts (Mn(acac)2, Mn(OAc)2, Mn(OAc)3, Mn(OAc)3·2H2O, etc.); and zinc salts (ZnCl2, Zn(NO3)2). Cobalt salts, such as Co(OAc)2, Co(acac)2, CoCl2, CoCl2·6H2O, CoBr2, etc.; nickel salts, such as NiCl2, NiCl2·6H2O, Ni(CH3COO)2, etc.; vanadium salts, such as NH4VO3, etc.; potassium salts, such as potassium persulfate, potassium dichromate, potassium permanganate, potassium perchlorate, potassium nitrate, potassium bromate, etc.; metal oxides, including but not limited to Fe2O3, Fe3O4, CuO, CoO, Co2O3, Co3O4, SnO2, V2O5, etc. The non-metallic element compounds include, but are not limited to, nitrogen oxides, nitric acid, nitrous acid, nitrous esters, quinones, hydrazines, aldehydes, and high-valent iodine compounds.

[0017] In some embodiments, the polydiolefin rubber may be one or a mixture of homopolymers and copolymers; Optionally, the homopolymer includes, but is not limited to, natural rubber, isoprene rubber, cis-butadiene rubber, high-vinyl polybutadiene rubber, chloroprene rubber, etc.; or, the homopolymer is a modified product, such as epoxy natural rubber prepared by epoxidation of natural rubber. The copolymers include, but are not limited to, styrene-butadiene rubber, nitrile rubber, butyl rubber, thermoplastic elastomers, etc.; or, the modified products of the copolymers, such as halogenated butyl rubber prepared by halogenation reaction of butyl rubber; In some embodiments, the organic solvent is one or more of the following substances: toluene, chlorobenzene, bromobenzene, xylene, dichlorobenzene, trimethylbenzene, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), tetrahydrofuran (THF), dichloromethane, dimethyl sulfoxide (DMSO), ethylene glycol dimethyl ether, benzonitrile, acetonitrile, ethyl acetate, etc. In some embodiments, the molar ratio of the number of double bonds in the polydiene rubber to the catalyst is 1:(0.00001~10); further, the molar ratio of the catalyst to the co-catalyst is 1:(0.001~1000); In some embodiments, the oxidant includes, but is not limited to, one or more of oxygen, air, ozone, hydrogen peroxide, peroxide, hypochlorous acid, hypochlorite, nitric acid, nitrate, nitrite, nitrite ester, or nitrite. In some embodiments, when the oxidant is a gas, its partial pressure can be 0.01 MPa to 10 MPa, including but not limited to 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 1 MPa, 2 MPa, etc.

[0018] In some embodiments, the heating temperature is controlled between 20 and 400 °C, including but not limited to 60 to 100 °C, 100 to 120 °C, and 120 to 200 °C; optionally, the heating process can be continuous heating or segmented heating.

[0019] In some embodiments, the preparation method is carried out according to the following steps: placing polydiolefin rubber, homogeneous catalyst, co-catalyst, oxidant and organic solvent in a reaction apparatus and mixing them for reaction; at the same time, the reaction is carried out under closed conditions, and the internal atmosphere can be an air atmosphere, a nitrogen atmosphere or a pure oxygen atmosphere.

[0020] In some embodiments, the preparation method further includes purifying the obtained reaction solution to obtain the final degradation product.

[0021] Furthermore, this application provides an end-functionalized liquid rubber prepared using the above-described preparation method; In some embodiments, the number-average molecular weight of the end-functionalized liquid rubber is 500 to 200,000, or 1,000 to 100,000.

[0022] In some instances, the end-functionalized liquid rubber has end-functionalized groups that are aldehyde, carboxyl, or a combination of both.

[0023] In some instances, the end-functionalized liquid rubber is in a liquid state.

[0024] Fourthly, this application provides an article of manufacture, wherein the article of manufacture uses the above-mentioned end-functionalized liquid rubber as its raw material; optionally, the article of manufacture is a 3D printing material or an adhesive.

[0025] Compared with the prior art, the technical effects achieved by this application include at least the following aspects: (1) Raw materials are widely available and have low cost. The reaction raw materials in this application are derived from widely used polydiolefin rubbers. This is not only an effective way to reduce production costs, but also a key technology for realizing high-value utilization of waste and resource recycling, which is in line with the concepts of green chemistry and sustainable development.

[0026] (2) The position of functional groups is controllable (mainly at the end of the chain). This application employs a degradation reaction to prepare end-functionalized liquid rubber. By carefully designing the degrading agent (such as peroxide, ozone, oxidant, etc.), functional groups (such as aldehyde groups, carboxyl groups, etc.) can be precisely introduced into the ends of the degraded molecular chains, resulting in a liquid rubber with the ideal structure for reactive prepolymers. It can react efficiently with systems such as epoxy resins to form a high-performance network structure.

[0027] (3) The microstructure of the original rubber is preserved. Most of the polydiolefin rubbers used in this application possess unique stereoregularity. The functionalization process primarily breaks down molecular chains without significantly altering their original microstructure. This means that the functionalized liquid rubber can inherit the excellent properties of the original rubber, such as excellent elasticity, low-temperature flexibility, and crystallinity.

[0028] (4) Molecular weight and its distribution can be controlled This application allows for relatively precise control of the average molecular weight and molecular weight distribution of the final liquid rubber by controlling functionalization conditions (such as temperature, time, and the amount of degrading agent). Molecular weight directly affects the viscosity, processing properties, and mechanical properties of the final product. A narrower molecular weight distribution contributes to obtaining more uniform and predictable product performance.

[0029] (5) The process is relatively simple The functionalization method described in this application can typically be carried out in conventional reaction vessels, and the process conditions are not as demanding as those of direct synthesis methods such as living anionic polymerization (which require extremely high purity and anhydrous and oxygen-free conditions). This reduces equipment investment and operational complexity, making it easier to achieve large-scale industrial production.

[0030] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the embodiments described in the description and the accompanying drawings. Attached Figure Description

[0031] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0032] Figure 1 This is the 1H NMR spectrum of the functionalized product from Example 1.

[0033] Figure 2 This is the carbon NMR spectrum of the functionalized product of Example 1.

[0034] Figure 3 This is the 1H NMR spectrum of the functionalized product from Example 4.

[0035] Figure 4 This is the carbon NMR spectrum of the functionalized product of Example 4.

[0036] Figure 5 This is the 1H NMR spectrum of the functionalized product of Example 10.

[0037] Figure 6 This is the carbon NMR spectrum of the functionalized product of Example 10.

[0038] Figure 7 This is a schematic diagram of using adhesive to attach a wooden board for hanging heavy objects, as shown in Example 12. Detailed Implementation

[0039] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

[0040] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0041] On the one hand, this application provides an end-functionalized liquid rubber, wherein the end groups are aldehyde, carboxyl, or a combination of carboxyl and aldehyde, and the main chain contains an ortho-dihydroxy functional group or an epoxy group, or an ortho-dihydroxy functional group and an epoxy group.

[0042] On the other hand, this application provides a method for preparing end-functionalized liquid rubber. The method includes: dissolving a polydiene-based rubber in an organic solvent, followed by a functionalization reaction in the presence of a catalyst; the catalyst is selected from one or more of azo compounds, peroxides, oxynitride radicals, nitrogen hydroxyl compounds, halogen radicals, hydroxyl radicals, alkoxy radicals, and their derivatives.

[0043] In one specific embodiment of this application, the polydiolefin rubber is one or more mixtures of homopolymers, copolymers, and rubber products. Specifically, the homopolymers include, but are not limited to, natural rubber, isoprene rubber, cis-butadiene rubber, and high-vinyl polybutadiene rubber; furthermore, the homopolymers also include their modified products, such as epoxy natural rubber obtained by epoxidation of natural rubber. The copolymers include, but are not limited to, styrene-butadiene rubber, nitrile rubber, butyl rubber, thermoplastic elastomers, and chloroprene rubber; furthermore, the copolymers also include their modified products, such as halogenated butyl rubber obtained by halogenation of butyl rubber.

[0044] In one embodiment of this application, the co-catalyst is a metal-containing compound, including metal salts and metal oxides. Metal salts include, but are not limited to, iron salts such as FeCl3, FeCl2, FeCl3·6H2O, FeBr3, FeBr2, FeBr3·6H2O, Fe(NO3)2, Fe(NO3)3, Fe(NO3)3·9H2O, etc.; copper salts such as CuCl2, CuCl, CuCl2·2H2O, etc.; and manganese salts, etc. Mn(acac)2, Mn(OAc)2, Mn(OAc)3, Mn(OAc)3·2H2O, etc.; zinc salts, ZnCl2, Zn(NO3)2, etc.; cobalt salts, Co(OAc)2, Co(acac)2, CoCl2, CoCl2·6H2O, CoBr2, etc.; nickel salts, NiCl2, NiCl2·6H2O, Ni(CH3COO)2, etc.; vanadium salts, NH4VO3, etc.; potassium salts, such as potassium persulfate, potassium dichromate, potassium permanganate, potassium perchlorate, potassium nitrate, potassium bromate, etc. Metal oxides include, but are not limited to, Fe2O3, Fe3O4, CuO, CoO, Co2O3, Co3O4, SnO2, V2O5, etc. Non-metallic element compounds include, but are not limited to, nitrogen oxides, nitric acid, nitrous acid, nitrite esters, quinones, hydrazines, aldehydes, and high-valent iodine compounds, etc.

[0045] In one embodiment of this application, the molar ratio of the number of double bonds in the polydiolefin rubber to the catalyst can be 1:(0.00001~10), preferably 1:(0.00001~0.01), further preferably 1:(0.0001~0.01), and even more preferably 1:(0.001~0.01), such as 1:0.001, 1:0.002, 1:0.003, 1:0.004, 1:0.005, 1:0.006, 1:0.007, 1:0.008, 1:0.009 or 1:0.01, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0046] In one embodiment, the method for preparing end-functionalized liquid rubber includes the following steps: (a) Add polydiolefin rubber, catalyst, co-catalyst, oxidant, and organic solvent to the reaction apparatus. The atmosphere in the reaction apparatus is an air atmosphere, a nitrogen atmosphere, or a pure oxygen atmosphere, and the pressure is 0.01~10 MPa, which can be 0~1 MPa, 0~2 MPa, preferably 0.01~0.3 MPa, such as 0.01 MPa, 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.5 MPa, 1.0 MPa, 2.0 MPa, or 3.0 MPa, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. (b) The system obtained in step (a) is heated at a temperature controlled between 20 and 400 °C, preferably between 60 and 150 °C, and more preferably between 60 and 120 °C. The temperature can be 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C or 120 °C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] (c) After step (b) is completed, the obtained reaction solution is purified to obtain the final degradation product. The purification method can be one or more of the commonly used purification methods such as distillation, column chromatography, recrystallization, adsorption / drying, thin-layer chromatography (TLC), extraction, and precipitation.

[0048] In one embodiment, the organic solvent in step (a) may be selected from toluene, chlorobenzene, bromobenzene, xylene, dichlorobenzene, trimethylbenzene, etc. N,N -Dimethylformamide, N,N - One or more of the following organic solvents: dimethylacetamide, tetrahydrofuran, dichloromethane, dimethyl sulfoxide, ethylene glycol dimethyl ether, benzonitrile, acetonitrile, ethyl acetate, etc.

[0049] In another aspect, this application provides an article using the aforementioned end-functionalized liquid rubber as its raw material; optionally, the article is a 3D printing material or an adhesive.

[0050] Table 1. Rubber source information in the examples and comparative examples (The rubber used in the examples of this invention is as follows, but this invention is not limited to the following sources.) Example 1 (a) Using a pressure-resistant bottle capable of displacing gases as the reaction apparatus, weigh 3.60 g of cis-butadiene rubber (approximately 0.0667 mol of double bonds), dissolve the rubber in 36 mL of dichlorobenzene, and add [the following to the solution] N-Hydroxyphthalimide (0.000667 mol) and potassium persulfate (0.0000667 mol) were used to replace the gaseous atmosphere in the reaction apparatus with oxygen at a pressure of 0.3 MPa.

[0051] (b) The reaction apparatus was then placed in a 75 °C oil bath and the reaction was carried out for 12 h.

[0052] (c) The obtained reaction solution was evaporated to remove dichlorobenzene, and then the product was dissolved in dichloromethane (30 mL). The product was then washed three times with saturated brine, the solvent was removed by vacuum distillation again, and the product was dried in a vacuum oven to constant weight (3.30 g).

[0053] (d) GPC characterization showed that the number average molecular weight of the degradation products was approximately 30,000 g / mol, and the 1H NMR spectrum (see [reference]) further confirmed this. Figure 1 ) and carbon spectrum (see Figure 2 Characterization revealed that the functionalized liquid rubber backbone contained epoxy groups, and 100% of the end functional groups were aldehyde groups.

[0054] Example 2 (a) Using a pressure-resistant bottle capable of displacing gas as the reaction apparatus, weigh 3.60 g of cis-butadiene rubber (approximately 0.0667 mol of double bonds), dissolve the rubber in 36 mL of toluene, add azobisisobutyronitrile (0.000667 mol) and chromium chloride (0.0000667 mol) to the solution, and replace the gas atmosphere in the reaction apparatus with oxygen at a pressure of 0.1 MPa.

[0055] (b) The reaction apparatus was then placed in a 70 °C oil bath and the reaction was carried out for 6 h.

[0056] (c) The obtained reaction solution was evaporated to remove toluene, then the product was dissolved in dichloromethane (30 mL), washed three times with saturated brine, the solvent was removed by vacuum distillation again, and dried in a vacuum oven to constant weight (3.00 g).

[0057] (d) After GPC characterization, the number average molecular weight of the degradation products was approximately 25,000 g / mol. After characterization by 1H NMR and 1C NMR, the functionalized liquid rubber backbone contained epoxy groups, and the terminal functional groups were nearly 50% carboxyl groups and 50% aldehyde groups.

[0058] Example 3 (a) Using a pressure-resistant bottle capable of displacing gas as the reaction apparatus, weigh 3.60 g of cis-butadiene rubber (approximately 0.0667 mol of double bonds), dissolve the rubber in 36 mL of bromobenzene, add azobisisobutyronitrile (0.000667 mol) and chromium sulfate (0.0000667 mol) to the solution, and replace the gas atmosphere in the reaction apparatus with oxygen at a pressure of 0.1 MPa.

[0059] (b) The reaction apparatus was then placed in an 80 °C oil bath and the reaction was carried out for 8 h.

[0060] (c) The obtained reaction solution was evaporated to remove bromobenzene, then the product was dissolved in dichloromethane (30 mL), washed three times with saturated brine, the solvent was removed by vacuum distillation again, and dried in a vacuum oven to constant weight (3.33 g).

[0061] (d) After GPC characterization, the number average molecular weight of the degradation products was approximately 13,000 g / mol. After characterization by 1H NMR and 1C NMR, the functionalized liquid rubber backbone contained ortho-dihydroxyl groups and nearly 100% of the terminal functional groups were carboxyl groups.

[0062] Example 4 (a) Using a pressure-resistant bottle capable of displacing gases as the reaction apparatus, weigh 3.60 g of styrene-butadiene rubber (approximately 0.0667 mol of double bonds), dissolve the rubber in 36 mL of mesitylene, and add [the following to the solution] N -Hydroxyphthalimide (0.000667 mol) and potassium persulfate (0.0000667 mol) were used to replace the gaseous atmosphere in the reaction apparatus with oxygen at a pressure of 0.1 MPa.

[0063] (b) The reaction apparatus was then placed in an oil bath at 100 °C and the reaction was carried out for 6 h.

[0064] (c) The obtained reaction solution was evaporated to remove mesitylene, and then the product was dissolved in dichloromethane (30 mL). The product was then washed three times with saturated brine, the solvent was removed by vacuum distillation again, and the product was dried in a vacuum oven to constant weight (3.25 g).

[0065] (d) After GPC characterization, the number average molecular weight of the degradation products was approximately 20,000 g / mol. After characterization by 1H NMR and 1C NMR, the functionalized liquid rubber backbone contained ortho-dihydroxyl groups and nearly 100% of the terminal functional groups were carboxyl groups.

[0066] Example 5 (a) Using a pressure-resistant bottle capable of displacing gases as the reaction apparatus, weigh 3.60 g of cis-butadiene rubber (approximately 0.05 mol of double bonds) and dissolve the rubber in 36 mL of water. N,NIn dimethylacetamide, azobisisobutyronitrile (0.0005 mol) and chromium trioxide (0.00005 mol) are added to the solution to replace the gas atmosphere in the reaction apparatus with oxygen at a pressure of 0.2 MPa.

[0067] (b) The reaction apparatus was then placed in an oil bath at 120 °C and the reaction was carried out for 3 h.

[0068] (c) Remove the obtained reaction solution by rotary evaporation. N,N -Dimethylacetamide, then dissolved the product in dichloromethane (30 mL), then washed three times with saturated brine, the solvent was removed by vacuum distillation again, and then dried in a vacuum oven to constant weight (3.11 g).

[0069] (d) GPC characterization showed that the number average molecular weight of the degradation products was approximately 33,000 g / mol, and the 1H NMR spectrum (see [reference]) further confirmed this. Figure 3 ) and carbon spectrum (see Figure 4 Characterization revealed that the functionalized liquid rubber backbone contained ortho-dihydroxyl groups, with nearly 20% of the terminal functional groups being carboxyl groups and 80% being aldehyde groups.

[0070] Example 6 (a) Using a pressure-resistant bottle capable of displacing gas as the reaction apparatus, weigh 3.60 g of cis-butadiene rubber (approximately 0.0667 mol of double bonds), dissolve the rubber in 36 mL of tetrahydrofuran, add azobisisobutyronitrile (0.0000667 mol) and potassium dichromate (0.00000667 mol) to the solution, and replace the gas atmosphere in the reaction apparatus with oxygen at a pressure of 0.3 MPa.

[0071] (b) The reaction apparatus was then placed in a 70 °C oil bath and the reaction was carried out for 6 h.

[0072] (c) The obtained reaction solution was evaporated to remove tetrahydrofuran, and then the product was dissolved in dichloromethane (30 mL). The product was then washed three times with saturated brine, the solvent was removed by vacuum distillation again, and the product was dried in a vacuum oven to constant weight (3.25 g).

[0073] (d) After GPC characterization, the number average molecular weight of the degradation products was approximately 15,000 g / mol. After characterization by 1H NMR and 1C NMR, the functionalized liquid rubber backbone contained ortho-dihydroxyl groups, and the terminal functional groups were approximately 22% carboxyl groups and 78% aldehyde groups.

[0074] Example 7 (a) Using a pressure-resistant bottle capable of displacing gases as the reaction apparatus, weigh 3.60 g of cis-butadiene rubber (approximately 0.0667 mol of double bonds), dissolve the rubber in 36 mL of benzonitrile, and add to the solution... N-Hydroxyphthalimide (0.0000667 mol) and potassium permanganate (0.00000667 mol) were used to replace the gaseous atmosphere in the reaction apparatus with oxygen at a pressure of 0.1 MPa.

[0075] (b) The reaction apparatus was then placed in an oil bath at 120 °C and the reaction was carried out for 2 h.

[0076] (c) The obtained reaction solution was evaporated to remove benzonitrile, then the product was dissolved in dichloromethane (30 mL), washed three times with saturated brine, the solvent was removed by vacuum distillation again, and dried in a vacuum oven to constant weight (3.11 g).

[0077] (d) After GPC characterization, the number average molecular weight of the degradation products was approximately 20,000 g / mol. After characterization by 1H NMR and 1C NMR, the functionalized liquid rubber backbone contained ortho-dihydroxyl groups, and the terminal functional groups were nearly 85% carboxyl groups and 15% aldehyde groups.

[0078] Example 8 (a) Using a pressure-resistant bottle capable of displacing gas as the reaction apparatus, weigh 3.60 g of natural rubber (approximately 0.0529 mol of double bonds), dissolve the rubber in 45 mL of ethyl acetate, add azobisisobutyronitrile (0.00529 mol) and potassium chlorate (0.000529 mol) to the solution, and replace the gas atmosphere in the reaction apparatus with oxygen at a pressure of 0.1 MPa.

[0079] (b) The reaction apparatus was then placed in a 65 °C oil bath and the reaction was carried out for 10 h.

[0080] (c) The obtained reaction solution was evaporated to remove ethyl acetate, then the product was dissolved in dichloromethane (30 mL), washed three times with saturated brine, the solvent was removed by vacuum distillation again, and dried in a vacuum oven to constant weight (3.22 g).

[0081] (d) After GPC characterization, the number average molecular weight of the degradation products was approximately 34,000 g / mol. After characterization by 1H NMR and 1C NMR, the functionalized liquid rubber backbone contained ortho-dihydroxyl groups, and the terminal functional groups were approximately 21% carboxyl groups and 79% aldehyde groups.

[0082] Example 9 (a) Using a pressure-resistant bottle capable of displacing gas as the reaction apparatus, weigh 3.60 g of styrene-butadiene rubber (approximately 0.05 mol of double bonds), dissolve the rubber in 45 mL of toluene, add azobisisobutyronitrile (0.005 mol) and potassium nitrate (0.0005 mol) to the solution, and replace the gas atmosphere in the reaction apparatus with oxygen at a pressure of 0.2 MPa.

[0083] (b) The reaction apparatus was then placed in an oil bath at 110 °C and the reaction was carried out for 1.5 h.

[0084] (c) The obtained reaction solution was evaporated to remove toluene, then the product was dissolved in dichloromethane (30 mL), washed three times with saturated brine, the solvent was removed by vacuum distillation again, and dried in a vacuum oven to constant weight (3.30 g).

[0085] (d) After GPC characterization, the number average molecular weight of the degradation products was approximately 35,000 g / mol. After characterization by 1H NMR and 1C NMR, the functionalized liquid rubber backbone contained ortho-dihydroxyl groups, and the terminal functional groups were approximately 44% carboxyl groups and 56% aldehyde groups.

[0086] Example 10 (a) Using a pressure-resistant bottle capable of displacing gases as the reaction apparatus, weigh 3.60 g of cis-butadiene rubber (approximately 0.0667 mol of double bonds), dissolve the rubber in 30 mL of toluene, and add to the solution... N -Hydroxyphthalimide (0.000667 mol) and potassium bromate (0.0000667 mol) were used to replace the gaseous atmosphere in the reaction apparatus with oxygen at a pressure of 0.1 MPa.

[0087] (b) The reaction apparatus was then placed in a 70 °C oil bath and the reaction was carried out for 6 h.

[0088] (c) The obtained reaction solution was evaporated to remove toluene, and then the product was dissolved in dichloromethane (30 mL), followed by washing three times with saturated brine, removing the solvent by vacuum distillation again, and drying in a vacuum oven to constant weight (3.29 g).

[0089] (d) GPC characterization showed that the number average molecular weight of the degradation products was approximately 20,000 g / mol. The 1H NMR spectrum (see [reference]) further confirmed this. Figure 5 ) and carbon spectrum (see Figure 6 Characterization revealed that the functionalized liquid rubber backbone contained ortho-dihydroxyl groups, and 100% of the terminal functional groups were carboxyl groups.

[0090] Example 11 The product derived from Example 4 (1.0 g of liquid styrene-butadiene rubber with o-dihydroxy-terminated carboxyl groups, number average molecular weight 20,000) was dissolved in toluene (10 mL), followed by the addition of trimethylolpropane triglycidyl ether (37.2 mg) and 1,3-dimethyl-2-imidazolinone (7.4 mg). The reaction was carried out at 100°C for 30 minutes under nitrogen protection. The resulting solution was concentrated under vacuum to remove most of the solvent.

[0091] Adhesion Testing and Measurement: Overlap shear bonding measurements were performed on an Instrand machine equipped with a 1 kN load cell, according to the modified ASTM D1002 method (ASTM-d-1002-10), at a speed of 50 mm / min. Overlap shear bonding was defined as the maximum force (in Newtons) on the bonded joint obtained from the overlap shear test divided by the overlap area of ​​the adhesive (in square millimeters). Three samples were used for each measurement.

[0092] Preparation of adhesive bonding sheets: Using a scraper, adhesive (0.1–0.2 g) was evenly applied to the substrate surface. A second substrate was then carefully aligned and pressed onto the adhesive layer with slight pressure to form a uniform film approximately 0.3 mm thick (adhesive contact area: 576 mm² [24 × 24 mm]). All samples were placed in an oven at 80°C for vacuum curing for 12 hours, then slowly cooled to room temperature (25 ± 2°C), followed by lap shear bond testing.

Claims

1. A liquid rubber with end-group functionalization, characterized in that, Its terminal positions contain active functional groups, and its main chain contains ortho-dihydroxy functional groups or epoxy groups, or ortho-dihydroxy functional groups and epoxy groups.

2. The end-functionalized liquid rubber according to claim 1, characterized in that, The terminal functional groups of the terminal functionalized liquid rubber are aldehyde, carboxyl, or a combination of carboxyl and aldehyde, and the main chain contains ortho-dihydroxy functional groups or epoxy groups, or ortho-dihydroxy functional groups and epoxy groups.

3. The end-functionalized liquid rubber according to claim 1, characterized in that, The number-average molecular weight of the terminal-functionalized liquid rubber is 5 million to 150,000, or 10 million to 100,000.

4. The method for preparing the end-functionalized liquid rubber according to any one of claims 1 to 3, characterized in that, The preparation method includes: in the presence of a homogeneous catalyst, a co-catalyst, an oxidant and an organic solvent, the polydiolefin rubber is subjected to a degradation reaction under heating conditions to obtain end-functionalized liquid rubber. Optionally, the homogeneous catalyst is one or more of azo compounds, peroxides, oxynitride radicals, nitrogen hydroxyl compounds, halogen radicals, alkoxy radicals, and their corresponding derivatives; and / or The co-catalyst is one or more of a compound containing metal elements or a compound containing non-metal elements.

5. The preparation method according to claim 4, characterized in that, The polydiolefin rubber is one or more of a homopolymer or copolymer; Optionally, the homopolymer includes, but is not limited to, natural rubber, isoprene rubber, cis-butadiene rubber, high-vinyl polybutadiene rubber, etc.; or, the homopolymer is a modified product, such as epoxy natural rubber prepared by epoxidation of natural rubber. The copolymers include, but are not limited to, styrene-butadiene rubber, nitrile rubber, butyl rubber, thermoplastic elastomers, chloroprene rubber, etc.; or, the modified products of the copolymers, such as halogenated butyl rubber prepared by halogenation reaction of butyl rubber.

6. The preparation method according to claim 4 or 5, characterized in that, The azo compounds include, but are not limited to, azobisisobutyronitrile, azomethane, azobenzene, p-hydroxyazobenzene, diethyl azodicarbonate, etc.; and / or The peroxides include, but are not limited to, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxy acids, peroxy esters, peroxy carbonates, and ketone peroxides; and / or The nitroxide radicals include, but are not limited to, piperidine nitroxide radicals, pyrrolidine nitroxide radicals, oxazolidine nitroxide radicals, imidazolidine nitroxide radicals, etc.; and / or The nitrogen-hydroxy compounds include, but are not limited to, those containing, [missing information]. N 2-Hydroxyphthalimide (NHPI) N -Hydroxysuccinimide (NHS), etc.; and / or The halogen free radicals include, but are not limited to, chlorine free radicals, bromine free radicals, iodine free radicals, etc.; and / or The alkoxy radicals include, but are not limited to, primary alkoxy, secondary alkoxy, and tertiary alkoxy.

7. The preparation method according to any one of claims 4 to 6, characterized in that, The co-catalyst may be absent, or may be one or more of a compound containing a metal element, a compound containing a non-metal element, and their corresponding derivatives; optionally, the compound containing a metal element includes a metal salt or a metal oxide; optionally, the metal salt includes, but is not limited to, iron salts such as FeCl3, FeCl2, FeCl3·6H2O, FeBr3, FeBr2, FeBr3·6H2O, Fe(NO3)2, Fe(NO3)3, Fe(NO3)3·9H2O, etc.; copper salts such as CuCl2, CuCl, CuCl2·2H2O, etc.; and manganese salts such as KMnO4, Mn(acac)2, Mn(OAc)2, Mn(OAc)3. Mn(OAc)3·2H2O, etc.; zinc salts, ZnCl2, Zn(NO3)2, etc.; chromium salts, K2Cr2O7, etc.; cobalt salts, Co(OAc)2, Co(acac)2, CoCl2, CoCl2·6H2O, CoBr2, etc.; nickel salts, NiCl2, NiCl2·6H2O, Ni(CH3COO)2, etc.; vanadium salts, NH4VO3, etc.; the metal oxides include, but are not limited to, MnO2, CrO3, Fe2O3, Fe3O4, CuO, CoO, Co2O3, Co3O4, SnO2, V2O5, etc.; potassium salts, such as potassium persulfate, potassium dichromate, potassium permanganate, potassium perchlorate, potassium nitrate, potassium bromate, etc.

8. The preparation method according to any one of claims 4 to 7, characterized in that, The molar ratio of the double bonds in the polydiolefin rubber to the homogeneous catalyst is 1:(0.00001~10).

9. The preparation method according to any one of claims 4 to 8, characterized in that, The molar ratio of the homogeneous catalyst to the co-catalyst is 1:(0.001~1000).

10. The preparation method according to any one of claims 4 to 9, characterized in that, The organic solvent is selected from toluene, chlorobenzene, bromobenzene, xylene, dichlorobenzene, trimethylbenzene, etc. N,N -Dimethylformamide, N,N - One or more of the organic solvents selected from dimethylacetamide, tetrahydrofuran, dichloromethane, dimethyl sulfoxide, ethylene glycol dimethyl ether, benzonitrile, acetonitrile, and ethyl acetate.

11. The preparation method according to any one of claims 4 to 10, characterized in that, The oxidizing agent includes, but is not limited to, one or more of oxygen, air, ozone, hydrogen peroxide, peroxide, hypochlorous acid, hypochlorite, nitric acid, nitrate, nitrite, nitrite ester, or nitrite. Optionally, when the oxidant is a gas, its partial pressure can be from 0.01 MPa to 10 MPa, including but not limited to 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 1 MPa, 2 MPa, etc.

12. The preparation method according to any one of claims 4 to 11, characterized in that, The heating temperature is controlled at 20~400 ℃, or 60~100 ℃, 100~120 ℃, 120~200 ℃, etc.; Optionally, the heating process can be continuous heating or segmented heating.

13. An article characterized in that, The article uses the end-functionalized liquid rubber prepared by any one of claims 1 to 3 or any one of claims 4 to 12 as its raw material; optionally, the article is a 3D printing material or adhesive.

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