Adhesive as well as preparation method and application thereof

Abstract

The invention relates to the technical field of compositions of high-molecular compounds, in particular to an adhesive as well as a preparation method and application thereof. The adhesive is prepared from a cardanol-based tackifier and an alpha-pinene-based adhesive; the adhesive prepared by the preparation method disclosed by the invention has excellent comprehensive performance: the adhesive has high heat resistance and tough bonding performance; the resin is especially suitable for the high-end fields of new energy battery packaging, 5G high-frequency substrates and the like, and the problem that traditional resin is poor in metal bonding performance is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer compound compositions, and more specifically, relates to an adhesive and a preparation method and application thereof. Background Art

[0002] In recent years, adhesives have been increasingly used in fields such as composite materials, electronic packaging, automotive manufacturing, construction, and new energy, and the demand for adhesive performance has become increasingly stringent. However, traditional adhesive technology still has many shortcomings, limiting its further application in high-end applications. Traditional adhesives (such as epoxy resins and polyurethanes) are prone to degradation when exposed to harsh environments such as ultraviolet light, high temperature, and high humidity, leading to problems such as decreased bond strength and interfacial failure. For example, adhesives used in outdoor construction tend to yellow and become brittle after long-term exposure to sunlight and rain, compromising structural safety. Although some modified adhesives have improved weather resistance by adding antioxidants or UV absorbers, they still struggle to meet the long-term stability requirements in extreme environments. Solvent-based adhesives release large amounts of volatile organic compounds (VOCs) (such as benzene and formaldehyde) during production and use, which not only pollute the environment but also pose a health risk. Despite the gradual promotion of water-based and UV-curable adhesives, they still have limitations in terms of cure speed, bond strength, and applicable substrate range. For example, water-based polyurethane adhesives have weak adhesion to metal or plastic substrates and require long drying times, impacting production efficiency. Modern industry demands increasingly diverse functional properties from adhesives, such as electrical conductivity, thermal conductivity, flame retardancy, and self-healing. Traditional adhesives typically possess only basic bonding properties and require functionalization through the addition of fillers (such as carbon nanotubes and flame retardants). However, the introduction of fillers often affects the adhesive's rheological properties and interfacial adhesion. For example, the viscosity of highly filled conductive adhesives increases significantly, making coating difficult; the repair efficiency of self-healing adhesives is limited by external stimuli (such as heat and light), making autonomous repair difficult. Some high-performance adhesives (such as high-temperature curing epoxies) require prolonged curing at temperatures above 120°C, which not only consumes a lot of energy but also limits their application on heat-sensitive substrates (such as plastics and electronic components). Although light-curing technology can reduce energy consumption, it relies on a specific wavelength light source and has poor curing performance on opaque substrates. When bonding dissimilar materials (such as metal-plastic and ceramic-polymer), poor interfacial compatibility can easily lead to stress concentration and delamination. Existing adhesives often rely on surface treatments (such as plasma and chemical etching) to enhance adhesion, but these processes are complex and costly.

[0003] Based on the above-mentioned deficiencies in the prior art, the present invention provides an adhesive and a preparation method and application thereof. Summary of the Invention

[0004] The first aspect of the present invention provides an adhesive, comprising: a cardanol-based thickener and an α-pinene-based adhesive;

[0005] The cardanol-based tackifier has the following structure:

[0006]

[0007] The α-pinene-based adhesive has the structure:

[0008]

[0009] A second aspect of the present invention provides a method for preparing an adhesive, comprising the following steps:

[0010] The preparation method of the cardanol-based tackifier comprises the following steps:

[0011] Under a nitrogen atmosphere, cardanol glycidyl ether, 4,4'-dimercaptobiphenyl, and catalyst 1 are reacted to obtain the adhesive.

[0012] The specific reaction pathway is:

[0013]

[0014] Preferably, the catalyst 1 is selected from any one of a Lewis acid catalyst, a protonic acid catalyst, and an ionic liquid catalyst.

[0015] Further preferably, the Lewis acid catalyst is selected from any one of anhydrous halide salts of iron, cobalt, nickel, zinc, and manganese; the protonic acid catalyst is selected from any one of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, 4-methylbenzenesulfonic acid, trifluoromethanesulfonic acid, and methanesulfonic acid; the ionic liquid catalyst is selected from any one of 1-butyl-3-methylimidazolium hydroxide, 1-ethyl-3-methylimidazolium acetate, tetrabutylammonium hydroxide, choline hydroxide, 1-butyl-3-methylimidazolium aluminum chloride, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-sulfonic acid butyl-3-methylimidazolium hydrogen sulfate, and N-methylpyrrolidone hydrogen sulfate.

[0016] Preferably, the molar ratio of the cardanol glycidyl ether, 4,4'-dimercaptobiphenyl, and catalyst 1 is 1:(0.5-1):(0.01-0.1).

[0017] Preferably, the reaction temperature is room temperature (25-120° C.), and the reaction time is 1-8 hours.

[0018] The tackifier's system, which combines cardanol groups, thioether bonds, and biphenyl groups, leverages the reversible crosslinking properties of the thioether bonds to produce excellent self-healing and processability. The introduction of sulfur atoms also significantly enhances the adhesive's adhesion to metal components. Its weak polarity also reduces high-frequency signal loss. Furthermore, the presence of the β-hydroxyl group enhances the compound's resistance to moisture, heat, and aging.

[0019] The preparation method of the α-pinene-based adhesive comprises the following steps:

[0020] S1. 4-tert-butylphenol is placed in a reaction vessel, an aqueous solution of formaldehyde and a catalyst 2 are added, and the reaction is carried out to obtain a condensation monomer;

[0021] The specific reaction pathway is:

[0022]

[0023] S2. The condensation monomer obtained in S1 is heated to 80-100°C and reacted for 1-2 hours to obtain an oligomer;

[0024] The specific reaction pathway is:

[0025]

[0026] S3. The oligomer obtained in S2, catalyst 3, α-pinene was placed in a reaction vessel and reacted at 95-105 ° C for 1.5-3 hours to obtain an α-pinene binder intermediate;

[0027] The specific reaction pathway is:

[0028]

[0029] S4. Add isopropylbenzene into the reaction vessel of S3 and react at 170-190° C. for 0.5-1.5 hours to obtain the α-pinene-based adhesive.

[0030] The specific reaction pathway is:

[0031]

[0032] Preferably, the molar ratio of 4-tert-butylphenol to formaldehyde is 1:(1-1.5), and the proportion of catalyst 2 used is 0.5-1.5% of the total mass of 4-tert-butylphenol and formaldehyde.

[0033] Preferably, the catalyst 2 is selected from any one of NaOH, KOH, LiOH, KF, NaF, LiF, NaHCO3, and Na2CO3.

[0034] Preferably, the molar ratio of the repeating units in the oligomer to α-pinene is 1:(1.1-1.5), and the amount of catalyst 3 used is 1%-5% of the total mass of the oligomer and α-pinene.

[0035] Preferably, the catalyst 3 is a supported Lewis acid ionic liquid catalyst, selected from any one of [BMIM]Cl-AlCl3@SiO2, [BMIM]Cl-AlCl3@Al2O3, [BMIM]Br-AlCl3@SiO2, [BMIM]Br-AlCl3@Al2O3, [BMIM]Cl-AlBr3@SiO2, [BMIM]Cl-AlBr3@Al2O3, [BMIM]Br-AlBr3@SiO2, and [BMIM]Br-AlBr3@Al2O3.

[0036] Preferably, the molar ratio of the repeating unit in the α-pinene adhesive intermediate to cumene is 1:(1-1.5).

[0037] The α-pinene, 4-tert-butylphenol, and cumyl groups work synergistically to impart exceptional overall performance to the resin. The rigid bicyclic structure formed by ring-opening α-pinene significantly enhances heat resistance. Its biobased nature enhances hydrophobicity while also providing toughness through its aliphatic ring structure. The tert-butyl group of the 4-tert-butylphenol group precisely regulates the hydroxyl value through steric hindrance, preventing excessive cross-linking. Its antioxidant properties extend thermal aging life, while its ortho-blocking effect ensures selectivity for linear condensation. The cumyl group performs a dual function: acting as a viscosity reducer to improve processability, and its non-polar aromatic structure enhances compatibility with polyolefins.

[0038] The third aspect of the present invention further provides the use of the above composite adhesive in polar engineering plastics or non-polar plastics or metals or rubber elastomers or fiber composite materials or porous materials.

[0039] The applicant discovered that the synergistic use of the aforementioned cardanol-based tackifier and α-pinene-based adhesive further enhances impact strength, far exceeding that of a single-component system. The two key components of the adhesive disclosed in this application, the cardanol-based tackifier and the α-pinene-based adhesive, contribute to the process of converting biomass resources into high-value-added materials. The rigid bicyclic structure formed by the ring-opening of α-pinene provides a high-strength skeleton and heat-resistant foundation for the system, while the flexible long chain and dynamically reversible sulfide bond (—S—CH2—CH(OH)—) of β-hydroxy sulfide impart excellent toughness and self-healing ability.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1) The cardanol-based tackifier provided by this invention exhibits high reactivity and rapid curing. The click chemistry reaction between the cardanol epoxy resin derivative and the thiol group is highly efficient, with crosslinking completed in 3 minutes at 120°C. The conversion rate of the cardanol epoxy resin derivative is >98%, improving overall production efficiency by at least 50%. The tackifier's inherent β-hydroxysulfide bond exhibits self-healing properties, with a heating repair efficiency of 80%.

[0042] 2) The α-pinene-based adhesive provided by the present invention has high heat resistance (Tg>125°C, Td>300°C) and high hydrophobicity, with a water absorption rate as low as 0.3% (compared to 1.2% for traditional phenolic resin).

[0043] 3) The adhesive composition provided by this invention, due to the presence of hydroxyl groups in the tackifier, forms coordination bonds between the sulfur atoms and the metal. This increases the tensile strength of the adhesive composition for aluminum substrates by 40%, increasing the bonding strength from 15 MPa to 21 MPa. It can be recycled up to five times (>60% of the breaking strength). BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is the hydrogen nuclear magnetic resonance spectrum of the cardanol-based tackifier in Example 1 of the present invention;

[0045] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the condensation polymer synthesized by S1 in Example 1 of the present invention;

[0046] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the oligomer synthesized by S2 in Example 1 of the present invention;

[0047] Figure 4 This is the hydrogen nuclear magnetic resonance spectrum of the product synthesized by S3 in Example 1 of the present invention;

[0048] Figure 5 is the hydrogen nuclear magnetic resonance spectrum of the α-pinene-based adhesive in Example 1 of the present invention;

[0049] Figure 6 This is the hydrogen nuclear magnetic resonance spectrum of the composite adhesive having a hydroxyl value of 25 mg / g in Example 2 of the present invention;

[0050] Figure 7 The differential scanning calorimetry curves of the composite adhesive having a hydroxyl value of 25 mg / g and the α-pinene adhesive in Example 4 of the present invention are shown;

[0051] Figure 8 This is the thermal gravimetric curve of the composite adhesive having a hydroxyl value of 25 mg / g and the α-pinene adhesive in Example 4 of the present invention;

[0052] Figure 9 1 and 2 are tensile-strain curves of Example 5, Comparative Example 1, and Comparative Example 2 of the present invention;

[0053] Figure 10 is the tensile-strain curve of Example 6 of the present invention;

[0054] Figure 11 This is the tensile-strain curve of Example 7 of the present invention. DETAILED DESCRIPTION

[0055] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The experimental methods in the following embodiments are all conventional methods unless otherwise specified. The materials, reagents, etc. used in the following embodiments and comparative examples are all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. unless otherwise specified.

[0056] Cardanol glycidyl ether, CAS number: 171263-25-5, model: XY767, purchased from Anhui Xinyuan Technology Co., Ltd.;

[0057] 4,4'-dimercaptobiphenyl, CAS No. 6954-27-4, was purchased from Zhengzhou Alpha Chemical Co., Ltd.;

[0058] 4-tert-Butylphenol, CAS number: 98-54-4, purchased from Shandong Chuanhe New Materials Co., Ltd.;

[0059] α-Pinene, CAS No. 7785-70-8, was purchased from Jiangxi Huayi Fragrance Chemical Co., Ltd.

[0060] Example 1

[0061] This embodiment provides the preparation of a cardanol-based tackifier and an α-pinene-based adhesive, specifically comprising:

[0062] The preparation method of the cardanol-based tackifier comprises the following steps:

[0063] Under a nitrogen atmosphere, 33g of cardanol glycidyl ether, 20g of 4,4'-dimercaptobiphenyl and 0.72g of ionic liquid catalyst 1-butyl-3-methylimidazole hydroxide were placed in a 500mL three-necked flask with a molar ratio of 1:1:0.05. The mixture was heated to 110°C and reacted for 2.5 hours. After the reaction, the excess 4,4'-dimercaptobiphenyl was removed by column chromatography and dried in an oven to obtain a cardanol-based thickener. The structural formula of the cardanol-based thickener is shown in Formula I:

[0064]

[0065] The cardanol-based thickener was dissolved in d-DMSO and subjected to 1H NMR test. The test results are as follows: Figure 1 The hydrogen peak of 4,4'-dimercaptobiphenyl disappeared before and after the reaction, and the H peak area on the epoxy group decreased, indicating that the thiol groups on both sides of the substrate 4,4'-dimercaptobiphenyl reacted with cardanol glycidyl ether.

[0066] The preparation method of the α-pinene-based adhesive comprises the following steps:

[0067] S1. Place 15g of 4-tert-butylphenol, 9.7g of formaldehyde aqueous solution (37%) and 0.25g of NaOH in a 500ml three-necked flask, the molar ratio of 4-tert-butylphenol to formaldehyde is 1:1.2, the amount of NaOH is 1wt%, the temperature is raised to 50°C, and the reaction is carried out for 2.5 hours to obtain a condensation monomer. In fact, oligomers will also be obtained at this temperature, and the oligomers with a longer residence time can be removed by gel permeation chromatography to obtain a pure condensation product, as shown in Formula II. The condensation product is dissolved in d-DMSO and tested by 1H NMR. It can be observed that the H area at position 2 of 4-tert-butylphenol decreases before and after the reaction (as shown in Figure 2). Figure 2 5), thus 4-tert-butylphenol was successfully converted.

[0068]

[0069] S2. The condensation product of 4-tert-butylphenol and formaldehyde obtained in step 1 is further heated at a temperature of 85° C. for 1 h to obtain the oligomer, the molecular formula of which is shown in Formula III.

[0070]

[0071] The oligomer was analyzed by gel permeation chromatography, and it was found that the weight average molecular weight of the oligomer obtained by the above method was about 8100. It was dissolved in d-DMSO and tested by 1H NMR. The test results are as follows Figure 3 shown. Figure 3 The multiple peaks of peak 1 and peak 6 appear in the graphite, indicating the different environments of the phenolic hydroxyl group and methylene at the end of the chain after the polymerization reaction. Figure 3 The areas of Peaks 2 and 4 are related to the degree of polymerization. The weight-average molecular weight of the polymer produced by this method is approximately 8100. This means that each polymer segment actually has an average of 20 (8100 / 402) polymer units. Therefore, the n value of the polymer is 20, meaning that the ratio of Peak 1 area to Peak 2 area (or Peak 4) is 20:1. Software analysis shows that the peak area ratio of the polymer obtained by this method is 20:0.97, which is close to the theoretical value.

[0072] S3. 8.1 g (approximately 0.001 mol of polymer, 0.02 mol of basic units) of the oligomer, 3.54 g of α-pinene (the molar ratio of basic units to α-pinene in the polymer is 1:1.3), and 0.116 g of [BMIM]Br-AlCl3@Al2O3 (1% of the total mass) were placed in a 100 mL three-necked reaction vessel. The temperature was raised to 98°C and the reaction was carried out for 2.5 hours to obtain an α-pinene adhesive intermediate. The reaction mixture was placed in water to wash away the [BMIM]Br-AlCl3@Al2O3, and then subjected to gel permeation chromatography to discard the lower molecular weight fraction. The molecular formula of the product is shown in Formula IV.

[0073]

[0074] After dissolving in d-DMSO, 1H NMR was performed. Figure 4 The introduction of α-pinene shifts the overall peak of the polymer upfield, with the peak shift of the terminal hydroxyl group being particularly significant, indicating that the introduction of α-pinene reduces the overall aromaticity of the polymer. Furthermore, the peak area ratio of Peak 2 to Peak 4 is 0.97:120, indicating that α-pinene successfully substituted with the phenolic hydroxyl groups on the polymer.

[0075] S4. Add 2.89 g of cumene to the reaction vessel of step 3, with the molar ratio of the basic unit of the α-pinene adhesive intermediate to cumene being 1:1.2. Raise the temperature to 185° C. and react for 1 hour to obtain the α-pinene-based adhesive. The molecular formula of the adhesive is shown in Formula V:

[0076]

[0077] The α-pinene-based binder shown in Formula V was dissolved in d-DMSO and subjected to 1H NMR testing. Figure 5 As shown. Since the reaction site of the polymer unit and isopropylbenzene is the ortho position of the tert-butyl group (see Figure 3 , Peak 5), so after the reaction Figure 3 The area of ​​peak 5 in the equation is halved. Figure 5 The ratio of the total area of ​​peaks 1-5 to the area of ​​peak 6 is 5:9, which also indicates that the final ratio of isopropylbenzene to polymer units is 1:1.

[0078] Example 2

[0079] This embodiment provides an adhesive, the preparation raw materials include the cardanol-based thickener and α-pinene-based adhesive prepared in Example 1, with a molar ratio of 1:0.27, and the preparation method includes: mixing the cardanol-based thickener and α-pinene-based adhesive uniformly to obtain.

[0080] The mixed composite adhesive was dissolved in d-DMSO and the hydroxyl value was calculated using 1H NMR. The 1H NMR spectrum of the composite adhesive is shown in Figure 6 The hydroxyl value of the composite adhesive is calculated using the following formula:

[0081]

[0082] Where x represents the amount of α-pinene-based adhesive used (g), y represents the amount of cardanol-based thickener used (g), M1 represents the weight-average molecular weight of the α-pinene-based adhesive, and M2 represents the molar mass of the cardanol-based thickener. n1 and n2 represent the number of hydroxyl groups in the molecular formulas of the α-pinene-based adhesive and cardanol-based thickener, respectively. When the weight ratio of adhesive to thickener is 1:2.04, the total hydroxyl value (KOH) of the composite adhesive is 25 mg / g. The hydroxyl value was verified using the areas of peaks 1, 1', 2, and 3 in chromatogram 6.

[0083] Example 3

[0084] In this embodiment, the hydroxyl value of the composite adhesive was adjusted by changing the ratio of the α-pinene-based adhesive and the cardanol-based tackifier, as shown in Table 1.

[0085] Table 1 Hydroxyl values ​​of composite adhesives

[0086] Serial number Adhesive usage (g) Thickener usage (g) Hydroxyl value (mg / g) 1 0 1 36.2 2 1 4.5 30 3 1 2.04 25.0 4 1 1.11 20 5 1 0.65 15 6 1 0.31 10 7 1 0 2.1

[0087] Example 4

[0088] In this example, differential scanning calorimetry and thermogravimetry were performed on the composite adhesive sample with a hydroxyl value of 25 mg / g and the α-pinene-based adhesive prepared in Example 1. The test results are shown in FIG. Figure 7 and Figure 8 .

[0089] Figure 7 The glass transition temperature (T g ), T of α-pinene-based adhesive g is 96.9℃, while the T g The results show that the mixing of α-pinene-based adhesive and cardanol-based thickener improves the overall glass transition temperature of the composite adhesive. On the one hand, it proves the strengthening effect of cardanol-based thickener on α-pinene-based adhesive, and on the other hand, it also shows that the composite adhesive has a better processing temperature.

[0090] Figure 8 The thermal weight loss curve of the composite adhesive and α-pinene-based adhesive. When the thermal weight loss reaches 5% (T d), the temperatures are 304°C and 269°C respectively, which also shows that the mixing of α-pinene-based adhesive and cardanol-based thickener improves the thermal stability of the composite adhesive and makes the composite adhesive have a wider range of use conditions.

[0091] Example 5

[0092] This example tests the metal adhesion of a composite adhesive with a hydroxyl value of 25 mg / g. The specific operation method is as follows: dissolve 0.05 g of the composite adhesive in DMF, and evenly apply it on a rough aluminum block with a diameter of 5 cm. Place another rough aluminum block of the same size on it, and use a jack to press it. The pressing pressure is 1 MPa and the pressing time is 2 minutes. Place the pressed aluminum block in air at 25°C to dry. After drying, use a tensile testing machine to perform a tensile-strain test. The test results are as follows: Figure 9 shown. Figure 9 Also included are the test results in Comparative Example 1 and Comparative Example 2.

[0093] Example 6

[0094] This example conducts a repeatability test on a composite adhesive sample with a hydroxyl value of 25 mg / g. The sample preparation method is the same as that in Example 5, except that the firmly bonded sample uses a low-temperature environment to destroy the bonding surface, and then repairs it in a high-temperature environment. The specific operation is as follows: Place the bonded sample in a -50°C refrigerator and keep it warm for 10 minutes to embrittle the bonding surface. Then place the embrittled sample in a drying oven at 150°C for drying to restore the embrittled adhesive and keep it warm for 10 minutes. One cold and one hot cycle is considered as one cycle. Samples with different number of cycles are subjected to fracture-elongation tests, and the test results are as follows. Figure 10 The sample after 5 cycles has a stress retention of 12 MPa, which is 60% of the stress retention of the sample without repeatability testing.

[0095] Example 7

[0096] Repeatability testing was performed using an α-pinene-based adhesive. The sample preparation and repeatability were the same as in Example 6. Figure 11 Without the addition of a cardanol-based thickener, using only an α-pinene-based adhesive, the adhesive's effectiveness could no longer be achieved after two cycles. This suggests that the combination of a cardanol-based thickener and an α-pinene-based adhesive significantly improves the overall performance of the adhesive system.

[0097] Comparative Example 1

[0098] In this comparative example, the adhesiveness of the α-pinene-based adhesive was tested, and the test conditions and methods were the same as those in Example 5.

[0099] Comparative Example 2

[0100] In this comparative example, commercially available 502 glue was used to test the adhesion of the aluminum block, and the test conditions and methods were the same as those in Example 5.

[0101] according to Figure 9 The results show that the commercially available 502 glue has a bonding strength of 13 MPa for aluminum blocks, the α-pinene-based adhesive has a fracture stress of 16 MPa, and the composite adhesive disclosed in the present invention has a fracture stress of 21 MPa. In comparison, the fracture stress of the composite adhesive disclosed in the present invention is 60% higher than that of the commercially available 502 glue and 31% higher than that of the α-pinene-based adhesive, indicating that the cardanol-based tackifier has a strengthening effect on the α-pinene-based adhesive, further demonstrating that the composite adhesive disclosed in the present invention has excellent application prospects.

[0102] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An adhesive, characterized in that: include: Cardanol-based thickener and α-pinene-based adhesive; The cardanol-based tackifier has the following structure: The α-pinene-based adhesive has the following structure:

2. The adhesive according to claim 1, wherein The preparation method of the cardanol-based tackifier comprises the following steps: Under a nitrogen atmosphere, cardanol glycidyl ether, 4,4'-dimercaptobiphenyl, and catalyst 1 are reacted to obtain a cardanol-based thickener.

3. The adhesive according to claim 1, wherein The preparation method of the α-pinene-based adhesive comprises the following steps: S1. 4-tert-butylphenol is placed in a reaction vessel, formaldehyde and catalyst 2 are added, and the reaction is carried out at 40-60 ° C for 1-4 hours to obtain a condensation monomer; S2. The condensation monomer obtained in S1 is heated to 80-100°C and reacted for 1-2 hours to obtain an oligomer; S3. The oligomer obtained in S2, catalyst 3, α-pinene was placed in a reaction vessel and reacted at 95-105 ° C for 1.5-3 hours to obtain an α-pinene binder intermediate; S4. Add isopropylbenzene into the reaction vessel of S3 and react at 170-190° C. for 0.5-1.5 hours to obtain the α-pinene-based adhesive.

4. The method for preparing the adhesive according to claim 2, wherein: The catalyst 1 is selected from any one of a Lewis acid catalyst, a protonic acid catalyst, and an ionic liquid catalyst.

5. The method for preparing the adhesive according to claim 4, wherein: The Lewis acid catalyst is selected from any one of anhydrous halide salts of iron, cobalt, nickel, zinc and manganese.

6. The method for preparing the adhesive according to claim 4, wherein: The protonic acid catalyst is selected from any one of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, 4-methylbenzenesulfonic acid, trifluoromethanesulfonic acid, and methanesulfonic acid.

7. The method for preparing the adhesive according to claim 4, wherein: The ionic liquid catalyst is selected from any one of 1-butyl-3-methylimidazolium hydroxide, 1-ethyl-3-methylimidazolium acetate, tetrabutylammonium hydroxide, choline hydroxide, 1-butyl-3-methylimidazolium aluminum chloride, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-sulfonic acid butyl-3-methylimidazolium hydrogen sulfate, and N-methylpyrrolidone hydrogen sulfate.

8. The method for preparing the adhesive according to claim 2, wherein: The molar ratio of the cardanol glycidyl ether, 4,4'-dimercaptobiphenyl and catalyst 1 is 1:(0.5-1):(0.01-0.1).

9. The method for preparing the adhesive according to claim 2, wherein: The reaction temperature of cardanol glycidyl ether, 4,4'-dimercaptobiphenyl and catalyst 1 is 25-120° C. and the reaction time is 1-8 hours.

10. The method for preparing the adhesive according to claim 3, wherein: The molar ratio of 4-tert-butylphenol to formaldehyde is 1:(1-1.5), and the mass of the catalyst 2 is 0.5-1.5% of the total mass of 4-tert-butylphenol and formaldehyde.

11. The method for preparing the adhesive according to claim 3, wherein: The catalyst 2 is selected from any one of NaOH, KOH, LiOH, KF, NaF, LiF, NaHCO3, and Na2CO3.

12. The method for preparing the adhesive according to claim 3, wherein: The molar ratio of the repeating units in the oligomer to α-pinene is 1:(1.1-1.5), and the mass of the catalyst 3 is 1%-5% of the total mass of the oligomer and α-pinene.

13. The method for preparing the adhesive according to claim 3, wherein: The catalyst 3 is a supported Lewis acid ionic liquid catalyst, selected from any one of [BMIM]Cl-AlCl3@SiO2, [BMIM]Cl-AlCl3@Al2O3, [BMIM]Br-AlCl3@SiO2, [BMIM]Br-AlCl3@Al2O3, [BMIM]Cl-AlBr3@SiO2, [BMIM]Cl-AlBr3@Al2O3, [BMIM]Br-AlBr3@SiO2, and [BMIM]Br-AlBr3@Al2O3.

14. The method for preparing the adhesive according to claim 3, wherein: The molar ratio of the repeating unit to isopropylbenzene in the α-pinene adhesive intermediate is 1:(1-1.5).

15. Use of the adhesive according to any one of claims 1 to 14 in polar engineering plastics, non-polar plastics, metals, rubber elastomers, fiber composite materials, or porous materials.

Images